evaluation of bioretention systems for stormwater quality

1

Evaluation of Bioretention Systems for

Stormwater Quality Improvement and Reuse: A Case Study of Size-Constrained Systems

in Manly, Australia

Master of Science by Research

2011

Patrick James Stuart

School of the Environment Faculty of Science

University of Technology, Sydney

2

Certificate of Authorship/Originality

I certify that the work in this thesis has not previously been submitted for a degree nor has it been

submitted as part of requirements for a degree except as fully acknowledged within the text.

I also certify that the thesis has been written by me. Any help that I have received in my research

work and the preparation of the thesis itself has been acknowledged. In addition, I certify that all

information sources and literature used are indicated in the thesis.

____________________

Patrick Stuart

3

Acknowledgements

I would like to thank my primary supervisor Dr Simon Mitrovic for his expertise and ongoing support

throughout the duration of this research. Thanks to my secondary supervisor, Associate Professor

Richard Lim for helpful discussions and final editing of the thesis and all the technical staff in the UTS

Science Faculty, including Sue Fenech, Gemma Armstrong and Ilona Kramer, who went out of their

way to make my laboratory work possible.

A special thanks to Manly Council for their financial support and accepting me into their organisation

from the first day I started. In particular, Mr Lee Lau for being a great industry supervisor and

Michael Galloway who used countless hours of his own time to assist my research and has

continually opened doors for me into the water industry, for which I will be forever grateful. Also,

many thanks to Sydney Water for funding the bacteria analysis, especially Rodney Kerr and Judith

Winder for their assistance.

Thanks must also be extended to my family, friends from UTS and my many friends at Manly Council

for making the experience extremely memorable.

4

Table of Contents

Chapter 1. Introduction ....................................................................................................................... 11

1.1. Urban Stormwater Pollution ............................................................................... 11

1.2. Bioretention Systems as a Water Quality Improvement Tool ............................ 11

1.3. Size Constraints on Bioretention Systems in Developed Urban Areas ............... 12

1.4. Aims of this Research .......................................................................................... 13

Chapter 2. A Review of the Literature ................................................................................................. 14

2.1. Stormwater ......................................................................................................... 14

2.1.1. Pollutants in Stormwater ......................................................................... 14

2.1.2. Variability in Pollutant Concentrations in Stormwater ............................ 15

2.1.3. Impacts of Stormwater Pollutants on Aquatic Ecology ........................... 17

2.2. Bioretention Systems .......................................................................................... 18

2.2.1. Introduction to Bioretention Systems ..................................................... 18

2.2.2. Removal of Suspended Solids .................................................................. 20

2.2.3. Removal of Nutrients ............................................................................... 21

2.2.4. Alteration of Peak Flows .......................................................................... 24

2.2.5. Removal of Metals ................................................................................... 25

2.2.6. Removal of Bacteria ................................................................................. 27

Chapter 3. Site Description, and Materials and Methods ................................................................... 29

3.1. ‘Case Study’ Site – Manly, NSW, Australia .......................................................... 29

3.2. Bioretention System Design ............................................................................... 30

3.3. Water Quality Monitoring .................................................................................. 33

3.4. Flow Volume Estimation ..................................................................................... 35

3.5. Event Mean Concentration Calculation .............................................................. 36

Chapter 4. Removal of Suspended Solids from Stormwater by Size-Constrained Bioretention Systems .............................................................................................................................. 38

4.1. Introduction ........................................................................................................ 38

4.2. Materials and Methods ...................................................................................... 40

4.3. Results ................................................................................................................. 40

4.4. Discussion ........................................................................................................... 47

Chapter 5. Removal of Nutrients from Stormwater by Size-Constrained Bioretention Systems ....... 51

5.1. Introduction ........................................................................................................ 51


5.3. Results ................................................................................................................. 55

5

5.4. Discussion ........................................................................................................... 63

5.4.1. Phosphorus .............................................................................................. 63

5.4.2. Nitrogen ................................................................................................... 66

Chapter 6. Removal of Metals from Stormwater by Size-Constrained Bioretention Systems ........... 74

6.1. Introduction ........................................................................................................ 74


6.3. Results ................................................................................................................. 77

6.4. Discussion ........................................................................................................... 83

Chapter 7. Removal of Faecal Indicator Bacteria from Stormwater by Size-Constrained Bioretention Systems ........................................................................................................ 87

7.1. Introduction ........................................................................................................ 87


7.3. Results ................................................................................................................. 89

7.4. Discussion ........................................................................................................... 95

Chapter 8. Conclusions and Recommendations ............................................................................... 103

8.1. Conclusions ....................................................................................................... 103

8.2. Recommendations for Design and Management of Bioretention Systems ..... 105

8.3. Research Recommendations ............................................................................ 107

Chapter 9. References ....................................................................................................................... 112

Chapter 10. Appendix .......................................................................................................................... 119

10.1. Published Bioretention Studies - Field Studies - where multiples samples were collected from multiple storms. .......................................................................... 119

10.3. Results from some of the Published Bioretention Studies – Small-scale studies ........................................................................................................................... 120

10.3. Raw Data ......................................................................................................... 121

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List of Figures

Figure 2-1: A typical first flush for a pollutant in stormwater during a rainfall event. .......................... 16

Figure 3-1: Indicative map showing location of the studied bioretention systems in Manly Local Government Area (shaded) on the northern side of Sydney Harbour, Australia. ............... 29

Figure 4-1: Inflow and outflow TSS concentrations throughout each monitored rainfall event at the Tutus St. system. ............................................................................................................ 44

Figure 4-2: Inflow and outflow TSS concentrations throughout each monitored rainfall event at the Beatty St. system. .......................................................................................................... 45

Figure 4-3: Inflow and outflow TSS concentrations throughout each monitored rainfall event at the Jellicoe St. system. ......................................................................................................... 46

Figure 5-1: Total phosphorus, orthophosphate, total nitrogen and inorganic nitrogen inflow and outflow concentrations, throughout the 11/8/09 rainfall event at the Tutus St. system. .. 60

Figure 5-2: Total phosphorus, orthophosphate, total nitrogen and inorganic nitrogen inflow and outflow concentrations, throughout the 16/5/10 rainfall event at the Beatty St. system. 61

Figure 5-3: Total phosphorus, orthophosphate, total nitrogen and inorganic nitrogen inflow and outflow concentrations, throughout the 5/5/10 rainfall event at the Jellicoe St. system. . 62

Figure 5-4: Effect of Antecedent period on Nitrate Outflow EMCs at the Tutus St. and Beatty St. Bioretention Systems, each point is a nitrate outflow EMC for a rainfall event. ................ 68

Figure 5-5: Effect of the Catchment runoff EMCs on Nitrate Outflow EMCs at the (A) Tutus St. and (B) Beatty St. Bioretention Systems. .................................................................................... 69

Figure 6-1: The inflow and outflow concentrations of metals most commonly found in residential stormwater, throughout the 28/1/10 rainfall event at the Tutus St. system. ..................... 80

Figure 6-2: The inflow and outflow concentrations of metals most commonly found in residential stormwater, throughout the 16/5/10 rainfall event at the Beatty St. system. ................... 81

Figure 6-3: The inflow and outflow concentrations of metals most commonly found in residential stormwater, throughout the 5/5/10 rainfall event at the Jellicoe St. system. .................... 82

Figure 7-1: Faecal indicator and Enterococci concentrations in the Tutus St. bioretention system. .... 93

Figure 7-2: Faecal indicator and Enterococci concentrations in the Beatty St. bioretention system. ... 94

Figure 7-3: Faecal indicator and Enterococci concentrations in the Jellicoe St. system. ....................... 95

7

List of Tables

Table 3-1: Antecedent period, sampling duration, approximate rainfall and event duration for each monitored rainfall event. .................................................................................................... 35

Table 4-1: TSS removal rates, EMC values and standard deviations (SD) at the inflow and outflow of each bioretention system, during each sampled rainfall event. ........................................ 41

Table 4-2: TSS inflow and outflow load during each sampled rainfall event and average load removal rates for each bioretention system..................................................................................... 42

Table 5-1: Nutrient results from some of the published bioretention field studies. ........................... 52

Table 5-2: Nutrient Results from some of the published bioretention small-scale studies. ................ 53

Table 5-3: Total phosphorus and orthophosphate removal rates, EMC values and standard deviations (SD) at the inflow and outflow of each bioretention system, during each sampled rainfall event. *This was calculated by weighting each EMC value according to total flow volume in that event. ......................................................................................... 57

Table 5-4: Nitrogen species’ removal rates, EMC values and standard deviations (SD) at the inflow and outflow of each bioretention system, during each sampled rainfall event. ................ 58

Table 5-5: Inorganic nitrogen species’ removal rates, EMC values and standard deviations (SD) at the inflow and outflow of each bioretention system, during each sampled rainfall event.59

Table 5-6: Total nitrogen and total phosphorus inflow and outflow load during each sampled rainfall event and average load removal rates for each bioretention system. ............................... 63

Table 6-1: Flow Weighted Average Inflow Concentrations for Total and Dissolved Metals. ............... 78

Table 6-2: Concentration Reductions (%) of Total and Dissolved Metals. ............................................ 78

Table 6-3: Dissolved Portion of Total Metal Concentrations (%). ......................................................... 78

Table 6-4: Average Total Metal Inflow and Outflow concentrations at the bioretention systems and ANZECC/ARMCANZ (2000) total metal trigger guidelines for the protection of aquatic ecosystems. ......................................................................................................................... 79

Table 7-1: Microbial results from some of the published bioretention field studies. .......................... 88

Table 7-2: Microbial results from published bioretention small-scale studies. ................................... 89

Table 7-3: Faecal coliform removal rates, EMC’s and standard deviations (SD) at the inflow and outflow, during each sampled rainfall event. ..................................................................... 90

Table 7-4: Enterococci removal rates, EMC’s and standard deviations (SD) at the inflow and outflow, during each sampled rainfall event. .................................................................................... 91

Table 8-1: Removal rates of stormwater pollutants by the three bioretention systems ................... 104

8

List of Equations

Equation 3-1: Event Mean Concentration (EMC).................................................................................. 36

Equation 5-1: Inorganic Nitrogen.........................................................................................................55

Equation 5.2: Organic Nitrogen............................................................................................................55

9

Abstract

Stormwater runoff in urban areas is known to carry high concentrations of sediment, organic matter,

nutrients, metals and pathogens, which can cause environmental issues in natural water bodies.

Bioretention systems (also known as bio-filtration basins and rain-gardens) are a type of stormwater

treatment device that attempt to remove pollutants from stormwater by harnessing natural

processes. There has been limited use of bioretention systems due to the lack of sufficient space in

urban areas for stormwater treatment. Size-constrained bioretention systems have a low

bioretention area to catchment size ratio giving them a higher potential for more extensive use in

urban areas.

The aim of this study was to evaluate the effectiveness of sized-constrained bioretention systems in

removing pollutants from stormwater runoff. The studied size-constrained bioretention systems

promote the horizontal sub-surface flow of stormwater through the bioretention media. This is

different to the vertical flow of water seen in conventional bioretention systems. However, once

established, both types of bioretention systems rely on the same pollutant removal processes,

including filtration and adsorption. The three size-constrained bioretention systems that were

studied are located in the Northern Beaches area of Sydney, Australia. These were closely monitored

between August 2009 and December 2010, which involved collecting water samples every 10-15

minutes at the inflow and outflow of the bioretention systems during rainfall events.

The bioretention systems reduced total suspended solids concentrations by an average of 78%,

while total copper, zinc and lead concentrations were reduced by an average of 66%, 58% and 61%,

respectively. Nutrient and faecal indicator bacteria removal rates were more varied, with the oldest

system, located at Jellicoe St. performing the worst of the three systems, leaching all forms of

nitrogen and faecal indicator bacteria. The newest system located at Tutus St. performed the best of

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the three systems, reducing total nitrogen by 44%, total phosphorus by 63%, faecal coliforms by 72%

and Enterococci by 35%. Considering the small area occupied by the sized-constrained bioretention

systems, they were generally found to be effective in removing pollutants from stormwater.

However, size constrained bioretention systems may require greater maintenance compared to

conventionally sized bioretention systems.

11

Chapter 1. Introduction

1.1. Urban Stormwater Pollution

Impervious surfaces in urbanised locations mean that a large percentage of rainfall cannot infiltrate

into the soil and hence becomes overland stormwater runoff, which mobilises deposited pollutants

(Lee and Heaney, 2003). Pollutants commonly entrained in urban stormwater include suspended

solids, nutrients, heavy metals and pathogenic bacteria. These pollutants are universally recognised

as having detrimental impacts on aquatic environments, including smothering of benthic

ecosystems, eutrophication, and chronic toxicity, whilst pathogenic bacteria can pose risks to human

health in recreational waterways (NSWEPA, 1997).

Sources of suspended solids include construction sites, residential gardens, and industrial activities.

Sources of heavy metals include the weathering of paints, roofing, vehicle components and

atmospheric deposition of industrial and vehicle exhaust fumes (Davis et al., 2001b). Sources of

nutrients include gardens and fertiliser use, while, sources of pathogenic bacteria includes faeces of

domestic animals and birds and sewer leaks/overflows (Carroll et al., 2009).

1.2. Bioretention Systems as a Water Quality Improvement Tool

There are a range of stormwater management tools available including gross pollutant traps, nets,

booms, sand filters, sediment basins, vegetated swales, constructed wetlands, street sweeping, and

source control approaches such as community education and regulation. Bioretention systems (also

known as biofiltration basins, biofilters and rain-gardens) are a type of stormwater treatment device

that attempts to replicate natural processes and reconnect the built and natural environments.

12

Bioretention systems contain a sand/soil/organic matter media with various reeds, grasses and

shrubs growing on the surface. During rainfall events, stormwater runoff drains into the bioretention

media, and is vertically filtered through porous soil media, which removes pollutants through

processes including filtration, adsorption and biological uptake (Hsieh et al., 2007). Interest,

knowledge and experience in the application of constructed bioretention systems is currently

undergoing rapid growth in urban areas in south-east Queensland, Sydney, and Melbourne, with

increased emphasis on water sensitive urban design.

1.3. Size Constraints on Bioretention Systems in Developed Urban Areas

In highly urbanised catchments, existing developments severely limit the placement and area

available for stormwater treatment devices. Optimum bioretention system designs typically have a

bioretention area to catchment area ratio of 2% (Bratieres et al., 2008b), which provides sufficient

capacity to treat rainfall events without overloading (Melbourne Water, 2005). However, many

developed urban areas suffer from a lack of sufficient open space suitable for large bioretention

systems.

Very little research has been conducted on the effectiveness of bioretention systems with small

bioretention area to catchment area ratios. It is unclear whether the stormwater retention time in

bioretention systems with small bioretention area to catchment area ratios will be sufficient for the

removal of dissolved pollutants from stormwater. Excessive loading of stormwater pollutants in the

media may be an issue. The capacity of the media to hold accumulated metals without allowing high

concentrations of metals to dissolve back into stormwater is an important issue. Overall, the

pollutant removal efficiencies and effective lifespan of size-constrained bioretention systems are

expected to be less than conventional bioretention systems.

13

The design of existing systems under study has accommodated this constraint by maximising the

bioretention area in the available site and incorporating a media with high hydraulic conductivity to

convey high stormwater flow rates. These systems do not have the typical bioretention design, but

still perform the same function of bioretention systems and involve the same processes, hence they

can be classified as such. The main difference is that these systems do not contain slotted

pipes/drains under the media to remove stormwater after it has filtered vertically through the

media. Instead, stormwater filters vertically into the media then travels via sub-surface flow

horizontally through the media to the outlet point.

Given the opportunities for construction of new bioretention systems in existing urban areas, an

important research question exists as to what the level of water quality improvement performance

is in size constrained bioretention systems. This has implications for decision making by local

government authorities that have the opportunity to invest in the construction and establishment of

stormwater quality improvement systems in size constrained locations.

1.4. Aims of this Research

This study aims to evaluate the effectiveness of size-constrained bioretention systems in improving

the quality of stormwater, with respect to the following parameters: suspended solids, trace metals,

nutrients and faecal indicator bacteria. Size-constrained bioretention systems have small

bioretention surface areas in relation to their catchment size. Three field size-constrained

bioretention systems were monitored in the coastal urban area of Manly in Sydney, Australia. If

found to be effective in removing stormwater pollutants, size-constrained bioretention systems may

have the potential for widespread use in urban areas.

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Chapter 2. A Review of the Literature

2.1. Stormwater

Stormwater runoff is the portion of rainfall that does not infiltrate into soil, evaporate or is absorbed

by plants. Urban areas have a high percentage of hard, impervious surfaces. These impervious

surfaces, such as roads, buildings and pavements, have reduced the natural processes of infiltration

and vegetation interception, resulting in increased runoff. Flood risk management in urban areas has

historically resulted in the construction of engineered drainage networks to transport stormwater

quickly to streams and canals.

2.1.1. Pollutants in Stormwater

Stormwater runoff generally contains non-point source pollution loads, generated and accumulated

over a wide area. The characteristic pollutants in urban runoff reflect human activity and urban

development of the catchment. Non-point source pollutants are directed to a point source as it

discharges from a stormwater pipe into the receiving aquatic environment (Davis and Birch, 2009).

Stormwater carries high concentrations of pollutants in both dissolved and particulate states.

Pollutants have the ability to alter the chemistry of receiving waters and impair the function of a

wide range of organisms. Pollutants of concern are those that frequently occur at concentrations

that can cause ecological damage or human health risks. They include nutrients such as nitrogen and

phosphorus, heavy metals, sediments, bacteria, viruses, organic matter, pesticides, toxic chemicals,

oils and grease.

15

The most common source of stormwater pollutants is from the weathering and mobilisation of

materials, such as roofing, house paint, vehicle components, road surfaces, organic matter, etc.

Sediments, pesticides, nutrients and organic matter are often eroded from building sites, walkways,

parks and gardens (Van Metre and Mahler, 2003, Davis and Burns, 1999, Root, 2000). Another

source contributing to runoff pollution is atmospheric deposition, for example industrial and vehicle

exhausts, which build up on roofs and roads and then carried in stormwater during rainfall events

(Davis et al., 2001a). These contribute heavy metals such as cadmium, copper and lead (Davis et al.,

2001a). Toxic chemicals and metals can also enter surface waters through accidental and regulated

wastewater discharges and runoff from industrial areas. Sources of bacteria include dog faeces, bird

droppings, and sewer/septic leaks (Carroll et al., 2009).

2.1.2. Variability in Pollutant Concentrations in Stormwater

The concentrations of pollutants in stormwater are highly variable, even under the same rainfall

intensity. This is due to the variability in supply of pollutants in urban areas. The magnitude and

duration of pollutant concentration peaks within a rainfall event, and the length of time before it

occurs varies between individual pollutants (Deletic, 1998).

It is common for stormwater to have a ‘first flush’ of high concentration of some pollutants as

accumulated pollutants are washed off at the start of the storm event (Chui, 1997) (Figure 2.1). The

supplies of pollutants are limited so the first flush is usually followed by a sustained lower

concentration of pollutants as the rainfall continues (NSWEPA, 1997, Deletic, 1998).

16

Figure 2-1: A typical first flush for a pollutant in stormwater during a rainfall event has a rapid rise in

the pollutant concentration with time, followed by a rapid decline and a long tail (Galloway et al.,

2006).

However, multiple pollutant concentration peaks in stormwater can also occur throughout the

rainfall event in catchments that consist of different sized sub-catchments (Choe et al., 2002). The

different mobilisation times of pollutants and range of distances to pollution sources can cause such

multiple pollutant concentration peaks. The intensity of the rainfall can influence the amount of

pollutant scouring, the rate of mobilisation of the pollutant and the dilution capacity of the rain

water. Some stormwater treatment devices, for example, gross pollutant traps (GPTs) and onsite

stormwater detention systems can become sources of pollution if they overflow in the later periods

of rainfall events (Grum et al., 1997). Overflowing of sewer pipes into stormwater networks can

result in nitrogen and bacteria concentration peaks after prolonged rainfall (Uchimura et al., 1997).

17

Increased rainfall intensity creates more energy, which mobilises greater pollutant loads. Rainfall

intensity can vary within the one rainfall event as well as between rainfall events. The factor that

causes the greatest variation in pollutant concentrations between rainfall events is the length of

time of the antecedent dry period. This is the length of the non-rainfall period before the rainfall

event (Chui, 1997). The longer the antecedent period, more pollutants will accumulate on roads,

roofs and other impervious surfaces. Sediments and organic matter concentrations in stormwater

are pollutants that are most affected by the antecedent period. However, other non-point source

pollutants are also strongly correlated with antecedent periods (Chui, 1997).

2.1.3. Impacts of Stormwater Pollutants on Aquatic Ecology

Some common pollutants occur naturally and are required at trace levels in surface waters to

support the growth of organisms. Examples are the nutrients nitrogen and phosphorus, which are

used for algal and plant growth, and are essential for ecosystem health and function. Concentrations

that are much higher than what would occur naturally can result in detrimental effects on ecosystem

health.

Short term exposure to high pollutant concentrations can cause acute or shock impacts on aquatic

organisms, which often result in recoveries in subsequent hours to weeks (NSWEPA, 1997).

Suspended sediments and organic matter cause shock impacts by smothering flora, reducing light

penetration and depleting oxygen levels in the water (NBSMPC et al., 1999). Heavy metal pollution

causes the short term impacts of poisoning and death if the concentrations are high enough

(NSWEPA, 1997).

Long term exposure to low and moderate pollution concentrations causes chronic impacts that are

persistent for long periods. Reduced diversity of aquatic plants and animals often results with shifts

18

to more tolerant or resilient species, which are often seen as ecologically undesirable (NSWEPA,

1997). Heavy metals can cause deformities and bio-accumulate in food chains (Beasley and Kneale,

2002). Organic matter and nutrients cause eutrophication of surface waters leading to algal and

macrophyte blooms, reducing species diversity.

Multiple studies have shown that increased urban impervious areas in a catchment cause negative

impacts on stream health. This includes a decline in macroinvertebrate and fish diversity, while,

bacteria diversities increase (Morse et al., 2003, Paul and Meyer, 2008). Higher nitrite, total

suspended solids, dissolved oxygen, increased bank erosion and decreased riparian vegetation have

all occurred with increased urbanisation (Morse et al., 2003).

2.2. Bioretention Systems

2.2.1. Introduction to Bioretention Systems

It is widely accepted that it is necessary to implement measures to prevent contamination of

receiving waters and this has become a significant management issue at the local and state

government level. Many studies have been done on stormwater treatment practices in rural and low

impact urban development areas. In highly urbanised catchments, existing developments severely

limit the placement and area available for stormwater quality improvement (Davis and Birch, 2009).

Natural wetlands have the ability to regulate sediment, nutrient and pollutant loadings to surface

and ground waters. The spread of urban areas and industrialisation resulting in greater stormwater

pollution has meant natural wetlands have been harmed and often removed, threatening their

ability to provide these crucial ecosystem services (Williams, 1993). Bioretention systems and

constructed wetlands have been used increasingly in recent decades to simulate and potentially

19

enhance the pollutant removing properties of natural wetlands. They have also received increasing

interest due to their design flexibility, small footprint, and aesthetic enhancements of landscapes

(Hatt et al., 2009a).

Despite the growing popularity of bioretention as a stormwater treatment device, there have been

few studies conducted in Australia on the effectiveness of such systems. The majority of

bioretention studies in Australia are conducted at Monash University in Melbourne (Bratieres et al.,

2008b, Hatt et al., 2009a). However, bioretention systems have been constructed across Victoria and

Southeast Queensland and to a lesser extent in New South Wales. Internationally, the University of

North Carolina and University of Maryland in the USA have conducted the most laboratory and field

bioretention studies by far (Li and Davis, 2008a, Hunt et al., 2008, Sun and Davis, 2007). Studies have

generally found bioretention systems to be successful in meeting their water quality improvement

objectives (Fletcher and Hydrology, 2004).

Bioretention systems generally consist of approximately 0.7 – 1.0m vertical depth of a porous media,

composed of a sand/soil/organic matter mixture (Davis, 2008). The media layer if often covered in a

mulch layer and this may eventually be covered or replaced by leaves and bark / natural mulch from

the area if surrounded by vegetation. Various reeds, grasses and shrubs are established to promote

evapotransporation, encourage biological activity, promote uptake of pollutants, and maintain soil

porosity and stability (Davis, 2008). Water can pond on the surface, typically up to a depth of 15cm

before it drains into the bioretention media. Infiltration from the bioretention media into

groundwater is encouraged as it reduces peak stormwater discharges and replenishes groundwater

supplies. Where local soil drainage is poor, underdrains channel the processed water out from below

the bioretention area, to prevent long-term saturation of the system (Hsieh et al., 2007).

20

The bioretention media removes pollutants through processes including filtration, ion exchange,

sorption, and biological uptake (Hsieh et al., 2007). The media must have high hydraulic conductivity

to infiltrate large water volumes draining from the impervious area. If permeability is low, significant

amounts of stormwater would run straight past or over the media, negating any possible delay in

peak discharge and reduction of pollutants (Hsieh and Davis, 2005). The hydraulic conductivity of the

media depends on the size of the conducting pores. Generally, larger pores conduct water more

rapidly (Hillel, 1998). Therefore, sandy media is favoured and high clay contents can be detrimental

to infiltration because clay tends to swell after absorbing water then shrink after drying, reducing

pore sizes (Brady and Weil, 1999). However, fine fractions of soils tend to be the most chemically

active, due to their greater surface area in relation to volume (Hsieh and Davis, 2005). Therefore, a

balance needs to be developed between the permeability of the media and pollutant removal

characteristics (Hsieh and Davis, 2005).

2.2.2. Removal of Suspended Solids

Removal efficiencies for total suspended solids (TSS) in laboratory studies are usually reported to be

consistently high, usually greater than 90% (Bratieres et al., 2008b, Hsieh and Davis, 2005).

However, removal efficiencies by field bioretention systems are reported to be less consistent. Hunt

et al. (2008) studied a large bioretention system in North Carolina, USA, with a bioretention area to

catchment area ratio of 6%. The system treated runoff from a car park and was found to reduce TSS

by 60% from an average of 49.5mg/L to 20mg/L. Another bioretention area in North Carolina studied

by Line and Hunt (2009) was found to reduce TSS loads by 76%. Hatt et al. (2009a) found that 3

biofiltration systems in Melbourne reduced TSS by about 90%. A roadside biofiltration system in

Mcdowall, Queensland, which had a bioretention area to catchment area ratio of 2%, was also

studied. It was also found to reduce TSS by about 90%. The Centre for Watershed Protection (Centre

for Watershed Protection, 2007) conducted a literature review of stormwater treatment practices in

21

USA. The study looked at 4 field bioretention system studies that monitored TSS; in these 4, a

median TSS removal of 59% was found. However, the maximum and minimum removal efficiencies

for TSS ranged from 98% to negative 100%. The lack of consistency highlights the extreme variations

of different bioretention systems. The media type, bioretention system age, structural design and

stormwater pollutant concentrations in the catchment can all affect the TSS removal rates.

The capture of suspended sediments can result in the long-term issue of clogging in bioretention

systems. Clogging reduces the pore size in the media, causing reductions in hydraulic conductivity in

the bioretention media. This may mean that during heavy rainfall, the bioretention system may

flood then overflow so water will not be treated by the system. Clay components in stormwater are

usually responsible for clogging the media (Li and Davis, 2008a). Li and Davis (2008a) found that the

hydraulic conductivity in the two media types in the laboratory decreased from original rates of

54±23 cm/h and 72±46 cm/h, to less than 10 cm/h due to clogging. Refer to Appendix 10.1 and 10.2

for a summary of results from published bioretention systems.

2.2.3. Removal of Nutrients

2.2.3.1. Nitrogen

There are several distinct timescales, over which pollutants, specifically with nitrogen compounds

are removed from stormwater in a bioretention system. The first and the shortest timescale is the

runoff infiltration event, at the time of, and shortly after the storm event. During this time,

pollutants in stormwater flow through the bioretention media. For pollutants to be removed,

transport and reactions must be rapid as contacts with individual media particles are extremely brief

(Hsieh et al., 2007). Limited contact times permit pollutants to be removed by physical processes

22

and some very rapid chemical reactions, for example ion exchange, but are too short for slower

biogeochemical transformations (ASA and SSSA, 1983, Hsieh et al., 2007).

The second timescale, in which pollutants are removed in bioretention systems, is the interval

between rainfall events. These may last from a few hours to several weeks, where the bioretention

media may drain and dry. This provides sufficient time for complex biological transformations to

take place. However, in the case of nitrogen, low removal rates of nitrate are seen and in some

studies nitrate production has been noted (Line and Hunt, 2009, Hunt et al., 2008, Hatt et al., 2009a,

Davis et al., 2001a). This is due to aerobic nitrification processes involving Nitrosomas and

Nitrobacter species, where ammonium ions are captured and oxidised to nitrate (Hsieh et al., 2007).

The nitrate accumulates in soil during the dry interval, then is washed out during the next rainfall

event (Line and Hunt, 2009). This explains why bioretention systems sometimes appear to be acting

as a source rather than a sink of nitrate (Line and Hunt, 2009, Hatt et al., 2009b, Kim et al., 2003).

Hsieh et al. (2007) found a similar result when evaluating the ammonia and nitrate removal in

bioretention columns with anoxic layers. Columns with a high permeability layer above a low

permeability layer, holding the stormwater in the media, had a high percentage of ammonia

removal. It also produced nitrate, suggesting that holding the water in the highly permeable aerobic

media in the intervals between rainfall events, allowed for ammonia to be transformed to nitrate,

which is then flushed out at the following input of stormwater. However, less nitrate was produced

than in the bioretention column with the low permeability layer above a high permeability layer.

This may be due to the fact that holding the water stopped oxygen diffusing into part of the media

(Hsieh et al., 2007). This formed small areas of anoxic zones, encouraging denitrification processes,

which removed some of the nitrate (Hsieh et al., 2007).

23

In bioretention systems with poorly drained soils, water impedes the diffusion of oxygen, creating

anoxic zones in the soil suitable for dentrification (Hsieh et al., 2007, Hunt et al., 2006). These zones

may also exist within micro-pores or among soil particles in an otherwise drained, aerobic media

(Hsieh et al., 2007, Hunt et al., 2006). Nitrate trapped in anoxic conditions can undergo biological

dentrification, resulting in the transformation of nitrate to gaseous nitrogen (Hsieh et al., 2007).

Significant levels of nitrate are usually only removed when small volumes of stormwater travel

through an area of bioretention media, allowing a greater retention time in the system. An

appropriate electron donor and carbon source in the anoxic zone is required to sustain the process

(Kim et al., 2003). Dentrification can be promoted in alternate bioretention designs, where a portion

of the media remains continuously submerged (Davis, 2007, Hunt et al., 2006).

24

2.2.3.2. Phosphorus

The removal of phosphorus in bioretention media is largely a geochemical process involving

different reactions with a variety of substrates (Davis et al., 2001a, Hsieh and Davis, 2005). Initial

bioretention studies suggest they have significant potential to retain phosphorus (Davis et al.,

2001a). Laboratory and field bioretention systems have been shown to regularly remove 70-85% of

total phosphorus (Davis et al., 2006, Bratieres et al., 2008b). Bioretention media with added organic

matter resulted in reduced phosphorus removal, suggesting a filter media with low phosphorus

content should be selected (Bratieres et al., 2008b, Hatt et al., 2009a). The extent of phosphorus

removal is generally related to phosphorus saturation of the media, and the equilibrium reached

with the phosphorus content in stormwater travelling through the system (Lucas and Greenway,

2008).

Hunt et al. (2006) found increased phosphorus concentration in the outflow of field bioretention

systems, which was attributed to high phosphorus saturation of the media. Dietz and Clausen (2005)

reported phosphorus leaching from a bioretention rain garden, probably due to the low phosphorus

concentration in the inflow from the roof surface. An equilibrium would be created as the runoff

passes through media with higher phosphorus concentration, resulting in the export of phosphorus.

However, stormwater usually has a much higher phosphorus concentration so most bioretention

systems consistently remove high percentages of phosphorus.

2.2.4. Alteration of Peak Flows

Another important purpose of bioretention systems is to reduce the peak flows of stormwater in

creek and river systems during a storm event. This is done by slowing the flow rate of stormwater as

it travels through the bioretention media, pooling at the inlet point. Bioretention systems can also

25

act as infiltration basins, allowing water to filter through to the groundwater, dramatically reducing

the peak discharge volumes at the outlet channels from these systems.

Davis (2008) observed mean peak flow reductions of 49 and 58% for their field study of two

bioretention systems. Flow peaks were significantly delayed as well, usually by a factor of 2 or more.

18% of the monitored events were found to be small enough that the bioretention media captured

the entire inflow volume and no outflow was observed. On these occasions the captured stormwater

either infiltrated into the groundwater, stayed in the media or left the system via evapotraspiration.

Hatt et al. (2009a) reported field bioretention systems in Victoria and Queensland to effectively

attenuate peak runoff flow rates by at least 80%. Loss via evapotranspiration was found to reduce

runoff volumes by 33% on average and the size of inflow volumes had the most influence on water

retention. Vegetation was shown to be important in bioretention systems for maintaining hydraulic

conductivity, as growth of roots counteracted compaction and clogging of the media.

2.2.5. Removal of Metals

Laboratory and field studies have found that bioretention systems generally remove over 80% of

metals (Zn, Cu, Pb and Cd usually tested) from stormwater (Hatt et al., 2009b, Line and Hunt, 2009).

However, the capacities of bioretention media to accumulate heavy metals are finite. There are two

common management options for optimising removal of heavy metals in bioretention systems,

aiming to extend the pollutant removal lifespan of the systems. The periodical removal of a shallow

surface layer of the media is one method. This is effective because the highest metal accumulation

concentration is found in the top layer of media (Muthanna et al., 2007, Li and Davis, 2008b).

26

The second method involves promoting metal uptake using selected plants and regular harvesting to

initiate a phytoremediation pathway to remove metals. Two types of plants are suggested for

phytoremediation. Hyper-accumulator plants accumulate potentially phytotoxic elements to

concentrations in their tissues of more than 100 times those found in non-accumulator plants (Salt

et al., 1998). Alternatively, non-accumulator plant species can be used, which have high biomass.

These do not accumulate metals to concentrations nearly as high as hyper-accumulators, but have

far greater biomass so can remove similar total amounts of metals from the media (Sun and Davis,

2007).

Soil conditions can also be manipulated using synthetic chelating agents to increase the

bioavailability of the heavy metals, increasing uptake of the metals (Huang et al., 1997). Shen et al.

(2002) found that certain chelates greatly increased the solubility of lead in soil and resulted in

significant increases in accumulation of lead in high biomass plant species. Using the method of

regular small doses of the chelate EDTA during the growing period was most productive for

accumulating lead in cabbage and avoided possible leaching of the chelate or soil-bound metals to

groundwater (Shen et al., 2002).

Some studies of metal retention in bioretention systems have found that plants accumulate only a

small percentage of metals. Sun and Davis (2007) studied the fate of metals in laboratory

bioretention systems and found that 88-97% of the metals flowing into the system was captured in

the media, 2-11.6% was not captured and 0.5-3.3% were accumulated in the grasses. These plants

had a relatively high concentration of metals, suggesting that greater plant biomass was needed to

remove significant levels from the media. Other studies have shown metal uptake by plants to be 2-

8% of the total metal removal from the stormwater (Muthanna et al., 2007). Despite the low

retention rates, plants in bioretention systems still perform other important functions including

maintaining the porosity of the media.

27

The uptake of metals in plants can depend on soil characteristics and conditions, for example, pH,

soil metal levels and other stresses on the plants, such as drought. Sun and Davis (2007) found the

roots of grasses were the main storage area of metals. This suggests that when harvesting plants for

phytoremediation, the whole plant should be removed, not just pruning stems and branches, as the

majority of metals would still remain in the roots (Baker et al., 1994, Dahmani-Muller et al., 2000,

Sun and Davis, 2007).

2.2.6. Removal of Bacteria

Few studies have tested the bioretention removal rates of bacteria from stormwater, even though

they present the greatest risk to public health in recreational waters. Hunt et al. (2008) is the only

study in the literature to report on a field bioretention system’s ability to remove pathogenic

bacteria. The bioretention system in Charlotte, N.C., USA has a bioretention surface area of 229m2

and treats stormwater from a parking lot with a catchment area of 3700m2 (6.1% bioretention area

to catchment area). Faecal coliform and Escherichia coli were monitored and found to be

significantly reduced, with an average reduction of 69% and 71%, respectively.

Rusciano and Obropta (2007) used bioretention columns in the laboratory to test the retention of

faecal coliforms from synthetic stormwater made from diluted manure slurry. Stormwater flowed

into the bioretention column at 77mL/min, the average and median faecal coliform reduction was

91.6% and 98.6%, respectively.

Jiang et al. (2007) investigated the removal of Escherichia coli after transport through sand columns.

The average percentage adsorption of bacteria for coarse and fine sands was 45.9±7.8% and 96.9±

3.2%, respectively. Column length had no significant effect on the E. coli concentration in the

28

outflow indicating retention occurs in the top layer of sand. Meschke and Sobsey (2003) conducted

column studies on E. coli removal from waste water by bioretention media. Removal rates increased

with less permeable soils, suggesting that media containing fine soil particles (clays and silts) may

physically remove more bacteria than very sandy bioretention media.

29

Chapter 3. Site Description, and Materials and Methods

3.1. ‘Case Study’ Site – Manly, NSW, Australia

Manly is situated on the northern beaches of Sydney, NSW, Australia. Sydney has a yearly average

rainfall of 1214 mm (Australian Government Bureau of Meteorology, 2010c), average maximum

temperature during summer of 25.6oC (Australian Government Bureau of Meteorology, 2010a) and

average minimum temperature during winter of 8.7oC (Australian Government Bureau of

Meteorology, 2010b). Three bioretention systems were selected, which drain developed residential

catchments in the suburb of Balgowlah Heights. Balgowlah Heights is located in the Manly Local

Government Area, about 12 km northwest of the Sydney CBD (Figure 3.1).

Figure 3-1: Indicative map showing location of the studied bioretention systems in Manly Local

Government Area (shaded) on the northern side of Sydney Harbour, Australia.

1: Location of Sydney CBD. 2: Location of the bioretention systems. Shaded area: Manly Local

Government Area.

30

3.2. Bioretention System Design

The design of size constrained bioretention systems could be described as a cross between an

ephemeral mini-wetland and a conventional bioretention system, but overall, the design mostly

relies on pollutant removal processes that occur in bioretention systems. The systems do not allow

for vertical filtration of stormwater through the bioretention media and out slotted pipe under-

drains as found in typical bioretention systems. Instead, stormwater vertically filters into the shallow

media then travels via sub-surface horizontal flow through the media to the opposite end of the

basin. The highly permeable local sandy soils are used as the bioretention media in the system,

allowing stormwater flows to immediately penetrate into the media near the inflow point. The

outflow point is an area of shattered rock in the system’s wall, which allows stormwater flows to exit

the system from above and below the media surface. During extremely heavy rainfall events, a

percentage of the stormwater is expected to flow across the surface of the bioretention media and

exit via the above-ground portion of the shattered rock outflow point. The dense growth of reed-like

plant species are expected to capture gross pollutants and reduce the velocity of the stormwater,

allowing particulates to settle out of the water column.

The retention time and distance travelled by the stormwater in the media increases during most

rainfall events by encouraging horizontal sub-surface flows close to the inflow point of the system to

the opposite end of the system. The build-up of leaf litter and sandy sediment (a result of the

catchment being located in a coastal sandstone area) near the entrance of the system preserves the

hydraulic conductivity of the media and maintains the ability of stormwater flows to penetrate into

the media as soon as it enters the system. Overall, these systems do not have the typical

bioretention design, but still perform the same function of bioretention systems and involve the

same processes, so are classified as bioretention systems.

31

All three systems are surrounded with sandstone boulders to support the structure of the systems

(see Figure 3.2). They are partly lined with geo-textile fabric, which stops water escaping through the

sandstone boulder retaining walls, while still allowing some infiltration into the surrounding soil. The

media is between 0.3m and 0.5m deep, consisting of the local soil, which is very sandy and low in

nutrients. The Beatty St. and Jellicoe St. bioretention systems contain a dense growth of Carex

appressa and Juncas usitatus. The Tutus St. system contains a mixture of Schoenus melanostachys,

Juncus continuous, Carex appressa, Juncas usitatus, Bolboschoenus fluviatillis and Baumea articulate.

Dye testing of the systems showed them to have an approximate retention time of 10-15 minutes

once saturated.

Figure 3-2: Photographs of the three bioretention systems.

Top left: Beatty St. system one year after construction. Top Right: Tutus St. system two years after

construction. Bottom: Jellicoe St. system one year after construction.

32

All three systems were size-constrained and restricted to a very small bioretention area in relation to

the catchment area (<1%). These systems were known respectively as the Jellicoe St. system, Beatty

St. system, and Tutus St. System (Figure 3.3). The Jellicoe St. system was constructed in 2003 and

treats an area of 5,000 m2. The area of the bioretention system is approximated 50 m2 (1% of the

catchment). The Beatty St. system was constructed in 2006; it treats an area of 5,000 m2 and has a

bioretention area of 8 m2 (0.16% of the catchment). The Tutus St. system was constructed in 2007

and treats an area of 11,000 m2. Its bioretention area is approximated 40 m2 (0.36% of the

catchment). The catchments of all three systems have a similar imperviousness (Figure 3.3), however

the Beatty St. catchment had a house construction occurring throughout the study. Also, the Beatty

St. catchment had a greater tree coverage leading to increased bird activity and potentially more leaf

litter entering the stormwater.

33

Figure 3-3: Location of the bioretention systems located in Manly, Sydney, Australia and the

catchment treated by each system (boxed).

3.3. Water Quality Monitoring

Water quality monitoring of three bioretention systems was conducted over a 15 month period

during rainfall events between August 2009 and December 2010. During each rainfall event, only

34

one bioretention system was monitored in detail. Sampling was conducted by hand without the aid

of an auto-sampler. The Australian Government Bureau of Meteorology Online Weather Watch

Radar Network was used so that the sampler could arrive on site at the start of the rainfall event.

Sampling could not be undertaken at night for safety reasons. Therefore, when a rainfall event

started overnight; sampling would begin the next day at the first practical opportunity. Sampling

continued throughout a rainfall event until either rainfall and runoff stopped, or the maximum

number of bottles was exceeded (generally after 3 to 3.5 hours of sampling).

The event duration, sampling duration, antecedent period, and approximate rainfall of the sampled

storms are shown in Table 3-1. The antecedent period and approximate rainfall while sampling were

calculated using data obtained from a rainfall gauge located 3km north of the sites. Therefore, this

data gave an approximate indication of rainfall intensity.

35

Table 3-1: Antecedent period, sampling duration, approximate rainfall and event duration for each

monitored rainfall event.

Antecedent period

Sampled at start of Event?

Approx. Event Duration

Sampling Duration

Approx. Rainfall While Sampling

days Yes/No hrs : mins hrs : mins (mm)

Tutu

s

11/08/2009 15 Yes 3:10 3:10 1.5

24/11/2009 4 Yes 0:40 0:40 0.5 28/01/2010 4 Yes 2:00 2:00 2 29/03/2010 16 Yes 1:40 1:40 2

30/03/2010 <2 No 22:00 2:00 3

23/06/2010 <2 No 2:00 1:15 2.5

Total 39 N/A 31:30 10:45 11.5

Beat

ty

13/02/2010 <2 No 9:00 1:00 1

28/02/2010 13 Yes 1:10 1:10 2.5

6/04/2010 <2 Yes 8:00 2:50 3

16/05/2010 11 Yes 2:30 2:30 5.5

26/05/2010 <2 No 13:00 3:15 10

1/12/2010 <2 No 11:00 1:40 5.5

Total 24 N/A 33:40 10:45 22

Jelli

coe

20/11/2009 8 No 1:25 1:15 0.5

5/02/2010 <2 Yes 1:30 1:30 2

5/05/2010 5 Yes 1:35 1:35 4.5

19/05/2010 <2 No 1:20 1:00 7.5

28/7/2010 <2 No 16:00 3:30 10

Total 5 N/A 21:50 5:20 24.5

During each sampling event, samples were collected every 10-15 minutes starting at the inflow point

of the bioretention system, followed by the outflow, then again at the inflow, and so on. At each

time interval, one bacteria sample and three replicates of each of nutrient, metal and total

suspended solids samples were taken for subsequent analysis. Samples were collected over 18

rainfall events between 11/8/09 and 1/12/10.

3.4. Flow Volume Estimation

Flow was estimated every time a sample was collected (every 10-15 minutes) at both the inflow and

outflow of each bioretention system. This was measured at all inflow and outflow sampling

36

locations, except one, by measuring the time taken for the stormwater flows to fill a container of

known volume. From this flow rate was determined. At the Jellicoe inflow sampling location the

container could not be used to capture the flow. Instead ruler measurement markings were drawn

on the street gutter walls allowing the cross-sectional area of the water flow to be measured at the

time of sampling. The area was then multiplied by the flow velocity, which was determined by

measuring the time taken for a buoyant object to travel a set distance without being impeded.

3.5. Event Mean Concentration Calculation

The event mean concentration (EMC) at the inflow and outflow of each bioretention system was

calculated for each rainfall event using the flow estimations and pollutant concentration at time

steps within each event (refer to the Equation 1). EMC is a flow weighted average that has widely

been used to characterise stormwater pollutant concentrations (Davis, 2007, Hatt et al., 2009b,

Choe et al., 2002)

Equation 3-1: Event Mean Concentration (EMC).

Where Ci = time variable pollutant concentration, Qi = time variable flow volume, N = number of

samples, Mi = pollutant mass

Total event pollutant loads are the event mean concentration multiplied by the stormwater volume.

The average pollutant concentration across all sampled events for the inflow and outflow of each

bioretention system was calculated by the summation of the total pollutant loads for all events,

37

divided by the summation of all stormwater volume for all rainfall events. This creates a flow

weighted average pollutant concentration, which is then used to calculate the average reduction of

pollutants for each bioretention system. Pollutant concentration reductions by the bioretention

systems will be the focus, rather than load reductions because the studied bioretention systems are

not completely lined at the base and the in situ soil is very sandy. Therefore, the majority of

stormwater that does not exit the system at the outflow point, will infiltrate into the surrounding

soils, presumably carrying pollutant concentrations similar to the water being sampled at the

outflow.

38

Chapter 4. Removal of Suspended Solids from Stormwater by

Size-Constrained Bioretention Systems

4.1. Introduction

Suspended solids consist of sediments and organic matter that are carried in stormwater from

gardens, roads, paths and construction sites. Suspended solids are an issue in urban stormwater

because they smother aquatic habitats (Paul and Meyer, 2008, Walsh et al., 2004). Suspended solids

fill the interstitial spaces between cobbles and gravel in freshwater creeks, where aquatic

invertebrates are found (Morse et al., 2003). They smother benthic algae and seagrasses, which

perform extremely important ecosystem services in lagoon, estuary and marine environments

(Walsh et al., 2004). Organic matter decomposes in creeks, rivers, lakes and lagoons, deoxygenating

the water and releasing nutrients that can cause algal blooms (Nogaro et al., 2007, Lapointe and

Bedford, 2011). Fine suspended solids in stormwater can increase the turbidity of receiving water

bodies, reducing light penetration, which can have detrimental effects on aquatic plants and the

organisms that feed on and live amongst the plants.

Pollutants such as heavy metals and nutrients are often bound to sediments (Camponelli et al., 2010,

Jartun et al., 2008) and can therefore be carried in suspended solids loads. These pollutants can later

be dissolved into the water column in aquatic environments, making them bio-available to aquatic

organisms and a potential ecological risk (Boenigk et al., 2005). Pollutants that remain bound to

sediments can cause contamination of benthic ecosystems (Birch and Taylor, 2002, Birch and Taylor,

1999). Benthic organisms, which perform critical functions in aquatic ecosystems, may not be able to

survive under these conditions causing serious ecosystem problems, for example, changes to trophic

dynamics (Boenigk et al., 2005, Fleeger et al., 2003). Even at sub-lethal levels, benthic organisms can

39

ingest these pollutants, introducing pollutants, such as heavy metals into the food chain (Beasley

and Kneale, 2002, Dorchin and Shanas, 2010).

The concentrations of suspended solids in stormwater at different urban locations vary greatly

depending on the: number and types of street trees in the catchment, the slope and the number of

sediment sources such as construction sites. Suspended solids concentrations may also vary

temporally at a site due to substantial mobilisation of sediments during the first flush, variations in

rainfall intensities and length of antecedent period. The average total suspended solids (TSS)

concentration, taken from a range of urban stormwater studies in Australia was calculated to be

99mg/L with a standard deviation of 83.6 (NRMMC et al., 2009).

The primary process for the removal of TSS in bioretention systems is filtration. Suspended solids in

stormwater are physically filtered by the media of bioretention systems. They are generally

contained within bioretention systems as it is uncommon for solids to be leached from a system

unless there is a design fault or the system is still establishing itself. Consistently high removal rates

of stormwater suspended solids (91-98%) have been observed in laboratory-based bioretention

studies (Bratieres et al., 2008b, Blecken et al., 2010, Hsieh et al., 2005). Published results from field

studies are more variable, with reductions in suspended solids concentrations ranging from 22-93%

in studies where multiple temporal replicates were collected over multiple storm events (Hunt et al.,

2008, Hatt et al., 2009a, Line and Hunt, 2009, Passeport et al., 2009, Davis, 2007). This disparity in

bioretention efficiency is often caused by variations in age, structural design, media, catchment land

uses and background stormwater TSS levels.

This section of the study aims to evaluate the effectiveness of three operating field bioretention

systems identified in Chapter 2, for the removal of suspended solids from stormwater. The studied

40

bioretention systems have a smaller than recommended bioretention surface area to catchment

area ratio, as described in Chapter 2.

4.2. Materials and Methods

The site descriptions and general field sampling method is outlined in Chapter 2. Total suspended

solids samples were collected in 1.2L polyethylene bottles and were individually analysed. The “Total

Suspended Solids Dried at 103-105oC” method was used (American Public Health Association et al.,

1998), which was approved by the USEPA and the Standard Method Committee (#2540D) in 1997. It

involves filtering a sample of known volume through a pre-weighed 0.45μm pore size glass fibre

filter disc, drying the filter disc for 1 hour at 103-105oC and weighing the filter disc to determine the

mass of the filtered and dried solids. This was carried out at the University of Technology, Sydney,

School of the Environment laboratories.

4.3. Results

The total suspended solids load and concentration removal rates of the three bioretention systems

are shown in Table 4.1. Large TSS concentration removal rates were seen across all three

bioretention systems with a 70% concentration reduction observed at the Tutus St. system, 79%

reduction at Beatty St. and 85% reduction at Jellicoe St. (Table 4.1). The 24/11/09 was the only

occasion when a rainfall event occurred at the Tutus St. system and it retained all the stormwater

flow, resulting in no flow being recorded at the outflow.

41

Table 4-1: TSS removal rates, EMC values and standard deviations (SD) at the inflow and outflow of

each bioretention system, during each sampled rainfall event.

*This was calculated by weighting each EMC value according to total flow volume in that event.

TSS Concentration

Inflow Outflow Reduction

(%) EMC (mg/L)

Standard Deviation (mg/l)

EMC (mg/L) Standard

Deviation (mg/l)

Tutu

s

11/08/2009 59 ±38 13 ±6 78 24/11/2009 43 ±38 N/A N/A N/A 28/01/2010 78 ±66 20 ±17 74 29/03/2010 248 ±181 11 ±5 96 30/03/2010 15 ±6 6 ±1 60 23/06/2010 19 ±11 14 ±9 23

*Average Concentration

41 - 12 - 70

*Reduction (%) 70

Beat

ty

13/02/2010 26 ±N/A 5 N/A 82 28/02/2010 77 ±56 8 N/A 90 6/04/2010 18 ±12 5 ±2 71

16/05/2010 107 ±74 20 ±11 81 26/05/2010 11 ±5 7 ±5 35


48 - 10 - 79

*Reduction (%) 79

Jelli

coe

20/11/2009 44 ±46 10 ±0.1 76

5/02/2010 20 ±12 7 ±0.7 67

5/05/2010 87 ±46 16 ±8 82

19/05/2010 11 ±0.7 8 ±0.3 26

28/7/2010 58 ±9 7 ±30 88


51 - 8 - 85

*Reduction (%) 85

All

Average Concentration

47 10 79

Average Reduction (%)

78

42

Table 4-2: TSS inflow and outflow load during each sampled rainfall event and average load removal

rates for each bioretention system.

Site Event

TSS Load

Inflow Load (g) Outflow Load (g) Load Reduction (%)

Tutu

s

11/08/2009 192 42 78.1 24/11/2009 41 0 100.0 28/01/2010 609 155 74.5 29/03/2010 1170 8 99.3 30/03/2010 318 118 63.0 23/06/2010 618 481 22.1

Total Reduction (%) 73

Beat

ty

13/02/2010 16 3 82.0 28/02/2010 167 5 97.3 6/04/2010 30 5 82.6

16/05/2010 1668 200 88.0 26/05/2010 267 202 24.4


Jelli

coe

20/11/2009 13 3 76.4

5/02/2010 208 30 85.5

5/05/2010 268 12 95.4

19/05/2010 42 23 46.6

28/7/2010 2669 223 91.7


All Average

Reduction (%) 81

The graphs in Figures 4.1 – 4.3 show the Inflow and outflow TSS concentrations throughout each

monitored rainfall event. All graphs show the actual time of sample collection. The 10-15 minute

sample retention time of the bioretention systems resulted in a 10-15 minute apparent shift in the

inflow and outflow curves, which should be considered when comparing individual samples. It can

be seen that the inflow concentration line is almost always higher than the corresponding outflow

concentration line. The outflow concentration lines remained consistently low, generally less than 10

mg/L. However, the inflow concentrations varied greatly, generally having a higher concentration

43

early in the rainfall event. This large difference between the inflow and outflow concentrations

accounts for the bioretention system’s TSS removal capacity. The high stormwater TSS

concentrations seen at the inflow were often associated with higher rainfall intensities and higher

stormwater flow rates and resulted in the scouring of sediments and organic matter off the

catchment. The high volumes multiplied by the high TSS concentrations equates to very high TSS

loads entering the bioretention systems during these periods.

44

Figure 4-1: Inflow and outflow TSS concentrations throughout each monitored rainfall event at the

Tutus St. system.

45


Beatty St. system.

46


Jellicoe St. system.

47

4.4. Discussion

Substantial TSS concentration reductions were seen across all three bioretention systems (Table

4.2), with a flow weighted average 70.1% concentration reduction observed at the Tutus St. system,

78.8% reduction at the Beatty St. system and 85.1% at the Jellicoe St. system. These TSS reductions

compare well to results published in other field bioretention studies. Line and Hunt (2009) recorded

a 79% reduction in TSS concentration, while the Hunt et al. (2008) study of a bioretention system,

also in North Carolina, USA, showed a 60% reduction in TSS. The systems in North Carolina have a

bioretention area to catchment area of 7.7% and 6.2%, whereas the Tutus, Beatty and Jellicoe St.

systems have bioretention area to catchment area ratios of <1%.

The load reduction and EMC reductions differ slightly because the EMC calculations do not reflect

the volume of stormwater lost from the bioretention system. Water can be lost via

evapotranspiration and infiltration (Winer, 2000). Loss of stormwater to infiltration can result in

incorrect estimations of the pollutant removal efficiencies of bioretention systems. The promotion

of infiltration is often seen as a benefit of bioretention because the volume of stormwater directly

entering surface waters is being reduced. However, if the water undergoing infiltration is high in

pollutants, it can result in the contamination of local soils and groundwater reserves. It is normal for

the concentration reduction efficiency to be lower than the load reduction efficiency due to the loss

of water to infiltration and evapotraspiration (Centre for Watershed Protection, 2007).

Despite being small in relation to their catchment size, none of the systems overflowed during the

monitored storm events indicating that the hydraulic conductivity of the system was fast enough to

convey the encountered stormwater flows. Hydraulic conductivity of the system is generally related

to the porosity of the soil media. Highly porous soil means the system is less likely to overflow.

48

However, it also means there are fewer fine particles in the media for pollutants to adhere to,

reducing the potential improvement of water quality by the bioretention system. Unlike soluble

pollutants, suspended solids are removed from stormwater in bioretention systems by the process

of filtration, not adhesion or ionic bonding. This suggests that bioretention media with a very high

sand content can still be very effective at removing TSS. Hatt (2007a) found non-vegetated

bioretention columns with 100% sand media to have extremely high TSS removal rates of 98-100%.

This compared to 80-97% TSS removal rates for other columns, which had soil based media.

Extensive studies have been conducted on stormwater quality improvement by sand filters and

found them to be very efficient at removing TSS (Winer, 2000). The Centre for Watershed Protection

(2007) reviewed 18 studies of filtering devices, which included mostly sand filters, and found them

to have a median TSS reduction of 86%.

Fast growing plants with extensive root systems, including Juncas usitatus and Carex appressa, were

used effectively in the bioretention systems. Other bioretention studies have found that Juncas spp.

and Carex appressa have a high root mass and root surface area (Read et al., 2010, Read et al.,

2008). Therefore, they are effective in minimising the chances of clogging and maintaining the

media’s hydraulic conductivity by creating a constantly aerating and changing soil structure (Read et

al., 2010, Read et al., 2008).

The difference in pollutant concentration between inflow samples and corresponding outflow

samples is correlated to the initial pollutant concentration of the stormwater at the inflow. This can

be seen in Table 4.1, where the average concentrations of TSS at the inflow of each rainfall event

ranged from 10.7 mg/l to 247.6 mg/l and the average outflow concentrations were consistently low,

ranging from 5.3 mg/l to 20.3 mg/l. This shows that if there is more pollution coming into the

bioretention system, more can be removed. Bioretention systems appear to perform more

49

effectively at removing pollutants when there are higher inflow pollutant concentrations (Muthanna

et al., 2007, Rusciano and Obropta, 2007).

The catchments draining into the Tutus St., Beatty St. and Jellicoe St. bioretention systems were

found to have an average TSS concentration (flow weighted) of about 46 mg/L. The average TSS

concentration, taken from a range of urban stormwater studies in Australia was calculated to be

99mg/L (NRMMC et al., 2009). If TSS concentrations in the stormwater flowing into the bioretention

systems averaged 99mg/L, the studied bioretention systems would be expected to have experienced

higher TSS removal efficiencies.

In terms of potential to reuse stormwater treated by bioretention, TSS is not a water quality issue

that affects public health, so it is not listed in stormwater reuse guidelines. However, a maximum

TSS concentration of 50 mg/L is suggested as a safe concentration limit to protect pumps and

irrigation equipment from excessive wear and clogging (NSWDECC, 2006). TSS concentrations

averaged 46 mg/L at the inflow to the bioretention systems with many rainfall events experiencing

EMC values much greater than 50mg/L. The average of all the outflow TSS concentrations was only

10mg/L, with the highest EMC value during a rainfall event being 20 mg/L. This is far less than the

recommended 50mg/L concentration limit, suggesting that bioretention systems have potential to

be used in stormwater treatment for irrigation purposes. However, the potential for bioretention

systems as a treatment option in stormwater reuse projects is discussed in more detail in Chapter 6,

because pathogens such as bacteria are the water quality parameter that is of most concern for

stormwater reuse projects (NRMMC et al., 2009).

The Jellicoe St. bioretention system had a very high TSS concentration removal efficiency of 85%.

This shows that a bioretention system with a bioretention area to catchment ratio of 1%, can still

efficiently remove TSS from stormwater seven years after its construction. Bioretention systems

50

should be able to efficiently remove TSS from stormwater for many years as filtration is the main

removal process. Decreasing removal rates over time are more likely to occur for nutrients and

metals as they can be dissolved or transformed and released from bioretention, especially after

pollutants have built up in the media over many years (Muthanna et al., 2007, Blecken et al., 2010).

Difficulties can be faced in removing TSS if the bioretention media becomes clogged with fine

particles or the above ground capacity is not sufficient to store the continual influx of sediment and

organic matter carried in stormwater.

Clogging of the bioretention media results in water not being able to pass through the bioretention

system as fast as it should, which can result in the system regularly overflowing, making the media

susceptible to erosion downstream. Clogging is not an issue for bioretention systems with

catchments containing naturally sandy soils because large sand particles do not block and clog the

pore spaces in the bioretention media. Catchments with high numbers of trees are also less likely to

be affected by clogging because the higher concentrations of leaf litter and other plant matter acts

like mulch when it enters a bioretention system, protecting the media from ‘caking’ and hardening.

Clogging can be an issue for bioretention systems in catchments with clay soils, which can result in

high levels of very fine silts being transported in stormwater. However, this can be overcome with a

high planting density in the bioretention system or regular mulching.

Overall, the bioretention systems studied have shown that they are effective in removing suspended

solids from stormwater. Suspended solids are of concern in stormwater due to high potential loads

and their ability to smother key habitats in a range of aquatic ecosystems.

51

Chapter 5. Removal of Nutrients from Stormwater by Size-

Constrained Bioretention Systems

5.1. Introduction

Nutrients include nitrogen and phosphorus, which can be in both dissolved and particulate forms.

Sources of nutrients in urban stormwater include fertilized landscapes, pet wastes, plant matter and

vehicle exhausts (Kaushal et al., 2006, Maestre and Pitt, 2005). Stormwater is a major source of

nutrients and can cause eutrophication (nutrient enrichment and algal blooms) in natural receiving

water bodies (Browman et al., 1979, Berge et al., 1997). In freshwaters, phosphorus is often the

limiting nutrient for algae and aquatic plants to increase in biomass (Berge et al., 1997). However, in

large eutrophic systems with long turn over times, nitrogen may be the limiting factor (Murray and

Parslow, 1999). Eutrophication can affect aquatic ecosystems through the development of algal

blooms, which can smother plant and animal habitats through excessive plant or algal growth, result

in depletion of oxygen and potential fish kills, reduce light penetration, in some cases release toxins

and generally have detrimental effects on recreational water quality and aesthetics (Cornett and

Rigler, 1979). It is therefore very important that nutrient capture and management be considered

when dealing with stormwater.

Bioretention systems remove nutrients from stormwater by filtration and biochemical processes.

Phosphorus generally has higher removal rates than nitrogen due to its affinity to soil particles (Davis

et al., 2006, Blecken et al., 2010, Bratieres et al., 2008b). Total phosphorus and orthophosphate have

been observed to have removal rates of 80% to 95% in laboratory studies (see Table 5.1) and 30% to

90% in most field studies (see Table 5.2). Tables 5.1 and 5.2 also show removal rates for forms of

total nitrogen or total phosphorus, including ammonia (NH3), total kjeldahl nitrogen (TKN), nitrate

52

(NO3), nitrite (NO2) and orthophosphate (Ortho-P). The composition of the bioretention media is

important, where media with high phosphorus levels was used, leaching was observed.

Table 5-1: Nutrient results from some of the published bioretention field studies.

Note: Bold figures are the percentage concentration reduction. * Load reduction recorded but <2%

change in volume so load reduction should be very similar to concentration reduction.

Study Hunt et al.

2008 Hatt et al. 2009

Line and

Hunt, 2009

(Passeport et al., 2009) (Yu and

Stanford, 2007)

(Dietz and

Clausen, 2005)

(Davis, 2007)

Location NC, USA VIC, Aus

QLD, AUS

NC, USA

NC, USA NC, USA VA, USA CT, USA MD, USA MD, USA

Comments

Only sampled small & medium storms

Grassed with

Submerged Zone

Grassed with

Submerged zone

Commercial designed

Bioretention System

100% Roof

runoff*

Submerged Zone and Carbon Source

Bioretention to catchment

area (%) 6.1 3.2 3.2 8.6 2.2 2.2

TN 32 -7 37 -17 54 54 32

TP 31 -398 86 37 63 58 55 -111 74 68

NH3 73 64 96 23 70 84 85

NOX or NO3 5 -13 -17 -254 33 8 35 79 86

TKN 44 11 49 59 20 31

Ortho-P -1271 81 57 78 74

53

Table 5-2: Nutrient Results from some of the published bioretention small-scale studies.

Note: Bold figures are the percentage concentration reduction. *Results for columns with effective

bioretention area to catchment area ratio of 1%, 2% and 4% and planted with Carex appressa (other

plant species used are not as effective for bioretention).**Results of testing at 6 hr inflow duration,

4.1cm/hr inflow rate and 91cm media depth system.

Study (Bratieres et al.,

2008b)

(Bratieres et al.,

2008a)

(Davis et al.,

2001a) (Blecken et al., 2010)

(Hsieh et al., 2005)

(Davis et al., 2006)

(Lucas and Greenway,

2008)

Location VIC, AUS

VIC, AUS

VIC, AUS

VIC, AUS MD, USA VIC, AUS MD, USA

MD, USA

QLD, AUS

Comments * 2oC

room 7oC

room 20oC room

** Loamy Sand

Sandy Loam

TN 65 71 62 70 -5 -23 -172 60 64 81

TP 89 95 94 86 60-80% 92 91 91 63 81 87 91

NH3 >90 60-80% 18 51 74 13

NOX or NO3

66 96 79 ‘Some

leaching’ -208 -320 -944 -16 24

TKN 60-80% 68

Ortho-P 79 90 90 75

Total nitrogen and nitrate removal rates vary greatly in both field studies and laboratory studies,

ranging from negative to greater than 80% removal rates (see Table 5.1 and Table 5.2). Nitrogen can

enter bioretention systems in stormwater as particulate organic nitrogen or inorganic soluble

nitrogen in the form of ammonia, nitrate or nitrite. Bioretention systems are able to remove

particulate organic nitrogen by physical processes. However, under aerobic conditions, particulate

organic nitrogen will be transformed either to nitrate or to ammonia (ammonia may then be nitrified

to nitrate). Ammonia readily binds to negatively charged soil particles, and due to the process of

nitrification (transformation to nitrate) and assimilation (nitrogen uptake by plants and microbes),

ammonia has been found to have consistently good removal rates throughout bioretention studies

(Dietz and Clausen, 2005, Passeport et al., 2009, Hatt et al., 2009a). Nitrate is a highly mobile anion,

which readily leaches through soils and other media (Kaushal et al., 2008). This characteristic and the

nitrification of ammonia generally results in negative or low removal rates of nitrate in bioretention

systems (Blecken et al., 2010, Line and Hunt, 2009, Hatt et al., 2009a).

54

Microbial dentrification is a process that results in the permanent removal of nitrogen as it involves

transforming nitrate to N2O or N2 gas, which enters the atmosphere. Denitrification occurs under

anoxic conditions and requires an electron donor, which is usually carbon in bioretention systems.

Due to the complex biochemical process and low affinity of nitrate to soil media, a long stormwater

retention time in the system is required for the process to take place. Therefore, dentrification is not

expected to be a significant process of nitrogen removal in the studied bioretention systems, which

have very short retention times.

This study aims to evaluate the effectiveness of three size constrained field bioretention systems in

removing forms of nitrogen and phosphorus from stormwater.


The site descriptions and general field sampling method is provided in Chapter 2. Nutrient samples

were collected in 1.2L polyethylene bottles after rinsing with sample water. Nutrient samples were

collected throughout six rainfall events at the Tutus St. system and five events at the Beatty St. and

Jellicoe St. systems. For ammonia, nitrate, nitrite and orthophosphate: 10ml of each sample was

filtered using a 0.45μm pore size cellulose acetate syringe filter and the filtrate was stored frozen

until analysis. Concentrations were determined by flow injection analysis colourimetry using a Lachat

Quickchem 8C8500 Automated Ion Analyser. The ascorbic acid method was used to analyse for

orthophosphate, phenate method for ammonia, automated cadmium reduction method for oxidised

nitrogen (NOx-N) and nitrite but the cadmium reduction was omitted for nitrite analysis.

55

Samples to be analysed for total nitrogen and total phosphorus were stored in the freezer in 20 ml

vials. The day before analysis, each sample was digested using the pursulfate method for

simultaneous determination of total nitrogen and phosphorus following Method 4500-P-J of

American Public Health Association (1998). This involved mixing 6ml of sample with 1.5 ml of

oxidising reagent (potassium persulphate, reagent grade water and sodium hydroxide). The sample

was then autoclaved at 121°C for 55 minutes. 50 μl of 3N sodium hydroxide was then added to each

vessel. Carrier water was subjected to the same digestion procedure. Samples were analysed

according to the oxidised nitrogen method and orthophosphate method using a Lachat Quickchem

8C8500 Automated Ion Analyser in the University of Technology, Sydney (UTS), School of the

Environment laboratories.

INORGANIC NITROGEN = AMMONIA + NITRATE + NITRITE

Equation 5-1: Inorganic Nitrogen

ORGANIC NITROGEN = TOTAL NITROGEN – INORGANIC NITROGEN

Equation 5-1: Organic Nitrogen

5.3. Results

Nutrient event mean concentrations and removal rates are show in Tables 5.3, 5.4 and 5.5. The

Tutus St. and Beatty St. systems performed well reducing total phosphorus and orthophosphate

concentrations by between 50% and 63%. Both systems also performed well in achieving

considerable reductions for total nitrogen and all nitrogen species except nitrate. Total nitrogen

concentration was reduced by 44% at the Tutus St. system and 29% at the Beatty St. system. Nitrate,

which makes up the majority of inorganic nitrogen, was increased by 29% at the Tutus St. system

56

and by 2% at the Beatty St. system. The Jellicoe St. bioretention system increased the stormwater

concentrations of all nutrient species except ammonia. Total phosphorus was increased by 9%,

orthophosphate increased by 21%, total nitrogen increased by 24% and inorganic nitrogen increased

by 33%.

Figures 5.1, 5.2 and 5.3 show the inflow and outflow concentrations throughout a rainfall event for

total phosphorus, orthophosphate, total nitrogen and inorganic nitrogen. The longest sampled

rainfall event, where the start of the rainfall event was captured, is graphed for each bioretention

system.

Table 5.6 shows the total nitrogen and total phosphorus loads during each rainfall event at the

inflow and outflow of each bioretention system. All three systems reduced total nitrogen and

phosphorus loads, including the Jellicoe St. system. The better performance of the systems in terms

of the load data, compared to water quality data, is due to infiltration and evapotranspiration in the

systems reducing the volume of stormwater and nutrient load that exits the system at the outflow.

57

Table 5-3: Total phosphorus and orthophosphate removal rates, EMC values and standard deviations (SD) at the inflow and outflow of each bioretention

system, during each sampled rainfall event. *This was calculated by weighting each EMC value according to total flow volume in that event.

Site Event Date

Total Phosphorus ( g/L) Orthophosphate ( g/L) Percentage of TP as Orthophosphate (%) Inflow Outflow

Reduction (%) Inflow Outflow

Reduction (%) EMC SD EMC SD EMC SD EMC SD Inflow Outflow

Tutu

s

11/08/2009 239 ±55 179 35 25 98 40 129 ±21 -32 41 72 24/11/2009 - - - - - 74 ±26 - - - - -

28/01/2010 253 ±61 222 ±60 12 146 ±92 153 ±24 -5 58 69 29/03/2010 4606 ±1786 1185 ±109 74 3074 ±1192 1035 ±69 66 67 87 30/03/2010 276 ±26 356 ±24 -29 236 ±26 317 ±26 -34 86 89 23/06/2010 115 ±25 120 ±8 -4 25 ±21 38 ±7 -52 22 32

*Average Concentration 426 159 63 308 154 50 72 97 *Reduction (%) 63 50 - -

Beat

ty

13/02/2010 144 - 38 - 74 100 - 38 - 62 69 100 28/02/2010 1157 ±438 323 - 72 985 ±443 273 - 72 85 85 6/04/2010 316 ±139 123 ±36 60 224 ±96 89 ±24 62 71 72

16/05/2010 401 ±125 268 ±99 33 286 ±79 193 ±74 33 71 72 26/05/2010 58 ±5 58 ±10 -1 63 ±5 61 ±10 3 109 105

*Average Concentration 240 113 53 191 96 50 80 85 *Reduction (%) 53 50 - -

Jelli

coe

20/11/2009 407 ±280 250 ±20 39 343 ±324 141 ±20 59 84 56 5/02/2010 157 ±20 184 ±23 -17 96 ±30 127 ±32 -32 61 69 5/05/2010 185 ±86 199 ±53 -8 99 ±125 138 ±40 -39 54 69

19/05/2010 173 ±2 138 ±7 20 124 ±9 93 ±11 25 72 67 28/07/2010 41 ±19 59 ±10 -44 43 ±17 61 ±3 -44 105 103

*Average Concentration 77 - 83 - -9 61 - 74 - -21 79 89 *Reduction (%) -9 -21 - -

All Average Concentration 248 118 53 186 108 42 75 92

Average Reduction (%) 36 26 - -

58

Table 5-4: Nitrogen species’ removal rates, EMC values and standard deviations (SD) at the inflow and outflow of each bioretention system, during each

sampled rainfall event.

*This was calculated by weighting each EMC according to total flow volume in that event.

Site Event Date Total Nitrogen ( g/L)

Total Nitrogen

Organic Nitrogen ( g/L) Inorganic Nitrogen ( g/L) Inflow Outflow



Reduction (%) EMC SD EMC SD EMC SD EMC SD EMC SD EMC SD

Tutu

s

11/08/2009 1616 ±335 1700 ±189 -5 414 ±174 158 ±47 62 1202 ±488 1541 ±323 -28 24/11/2009 - - - - - - - - - - - - - - - 28/01/2010 2036 ±698 1179 ±403 42 1417 ±498 644 ±329 55 618 ±321 534 ±174 14 29/03/2010 5801 ±1259 4001 ±605 31 5168 ±1501 2346 ±419 55 634 ±445 1656 ±186 -161 30/03/2010 581 ±107 684 ±214 -18 403 ±97 469 ±163 -16 178 ±37 215 ±51 -21 23/06/2010 216 ±87 242 ±39 -12 166 ±50 182 ±20 -10 50 ±45 60 ±18 -20

*Average Concentration 867 - 482 - 44 646 - 256 - 60 245 - 256 - -4 *Reduction (%) 44 60 -4

Beat

ty

13/02/2010 1033 - 833 - 19 379 - 475 - -25 655 - 358 - 45 28/02/2010 3673 ±1491 2232 - 39 2318 ±1120 487 - 79 1354 ±471 1744 - -29 6/04/2010 615 ±330 487 ±181 21 518 ±285 359 ±114 31 107 ±57 128 ±68 -31

16/05/2010 1616 ±444 1454 ±305 10 1007 ±374 628 ±135 38 609 ±249 826 ±249 -36 26/05/2010 380 ±164 417 ±117 -10 186 ±88 244 ±65 -31 194 ±80 174 ±59 10

*Average Concentration 984 - 699 - 29 588 - 345 - 41 396 - 354 - 11 *Reduction (%) 29 41 11

Jelli

coe

20/11/2009 3333 ±1791 3310 ±269 1 - - - - - - - - - - 5/02/2010 849 ±278 943 ±60 -11 565 ±215 683 ±120 -21 285 ±79 260 ±80 9 5/05/2010 1830 ±1044 2162 ±88 -18 926 ±620 810 ±36 13 904 ±461 1352 ±110 -50

19/05/2010 1047 ±642 1125 ±416 -8 208 ±229 280 ±85 -35 839 ±414 846 ±331 -1 28/07/2010 366 ±225 572 ±109 -56 169 ±96 242 ±113 -43 196 ±156 329 ±135 -68

*Average Concentration 572 - 707 - -24 275 - 309 - -12 284 - 378 - -33 *Reduction (%) -24 -12 -33

All Average Concentration 804 629 22 503 303 40 309 329 -6

Average Reduction (%) 17 30 -9

59

Table 5-5: Inorganic nitrogen species’ removal rates, EMC values and standard deviations (SD) at the inflow and outflow of each bioretention system, during

each sampled rainfall event.

*This was calculated by weighting each EMC value according to total flow volume in that event.

Site Event Date

Inorganic Nitrogen ( g/L)

Nitrate Nitrite Ammonia Inflow Outflow



Reduction (%) EMC SD EMC SD EMC SD EMC SD EMC SD EMC SD

Tutu

s

11/08/2009 897 ±363 1366 ±205 -52 37 ±18 24 ±4 35 268 ±148 151 ±34 44 24/11/2009 483 ±74 - - - 41 ±6 - - - - - - - - 28/01/2010 459 ±189 497 ±178 -8 29 ±14 31 ±5.6 -9 130 ±148 6 ±4 95 29/03/2010 215 ±448 1318 ±146 -513 59 ±91 78 ±18 -34 360 ±268 260 ±66 28 30/03/2010 160 ±33 197 ±49 -23 9 ±1 10 ±1 -10 8 ±4 8 ±2 11 23/06/2010 40 ±43 55 ±17 -35 3 ±1 3 ±0.7 -8 7 ±2 2 ±3 69

*Average Concentration 179 - 231 - -29 13 - 10 - 22 57 - 15 - 74 *Reduction (%) -29 22 74

Beat

ty

13/02/2010 593 - 295 - 50 13 - 6 - 58 48 - 58 - -21 28/02/2010 525 ±107 1030 - -96 45 ±21 61 - -35 784 ±395 653 - 17 6/04/2010 40 ±19 85 ±66 -128 7 ±2 8 ±3 -14 59 ±37 35 ±12 36

16/05/2010 530 ±250 791 ±236 -49 11 ±3 19 ±10 -69 67 ±46 16 ±6 77 26/05/2010 176 ±81 158 ±59 10 4 ±2 4 ±1 10 14 ±4 11 ±2 17

*Average Concentration 316 - 323 - -2 9 - 9 - 5 71 - 23 - 68 *Reduction (%) -2 5 68

Jelli

coe

20/11/2009 795 ±205 980 ±35 -23 28 ±6 33 ±15 -15 - ± - ± 5/02/2010 222 ±71 208 ±62 6 25 ±26 27 ±18 -8 37 ±23 25 ±27 32 5/05/2010 661 ±335 1212 ±149 -83 21 ±8 23 ±6 -9 221 ±139 117 ±48 47

19/05/2010 710 ±443 773 ±341 -9 19 ±0.5 16 ±0.5 17 111 ±30 58 ±9 48 28/07/2010 129 ±154 278 ±124 -114 7 ±3 10 ±3 -40 60 ±7 42 ±19 30

*Average Concentration 209 - 328 - -57 12 - 13 - -11 67 - 43 - 36 *Reduction (%) -57 -11 36

All Average Concentration 235 294 -25 11 11 6 65 27 59

Average Reduction (%) -29 5 59

60

Figure 5-1: Total phosphorus, orthophosphate, total nitrogen and inorganic nitrogen inflow and

outflow concentrations, throughout the 11/8/09 rainfall event at the Tutus St. system.

61


outflow concentrations, throughout the 16/5/10 rainfall event at the Beatty St. system.

62


outflow concentrations, throughout the 5/5/10 rainfall event at the Jellicoe St. system.

63

Table 5-6: Total nitrogen and total phosphorus inflow and outflow load during each sampled rainfall

event and average load removal rates for each bioretention system.

Site Event Date

Total Nitrogen Load Total Phosphorus Load

Inflow Load (g)

Outflow Load (g)

Load Reduction

(%)

Inflow Load (g)

Outflow Load (g)

Load Reduction

(%)

Tutu

s

11/08/2009 5.3 5.6 -5 0.8 0.6 25

24/11/2009 - - - - - -

28/01/2010 15.9 9.1 42 2.0 1.7 12

29/03/2010 27.4 3.0 31 21.8 0.9 74

30/03/2010 12.7 13.8 -18 6.0 7.2 -29

23/06/2010 7.1 8.1 -12 3.8 4.0 -4

Total Load Reduction (%) 49 66

Beat

ty

13/02/2010 0.6 0.5 19 0.1 0.0 74

28/02/2010 7.9 1.3 39 2.5 0.2 72

6/04/2010 1.0 0.5 21 0.5 0.1 60

16/05/2010 25.3 14.3 10 6.3 2.6 33

26/05/2010 9.5 12.1 -10 1.4 1.7 -1


Jelli

coe

20/11/2009 1.0 1.0 1 0.1 0.1 39

5/02/2010 8.9 4.3 -11 1.64 0.8 -17

5/05/2010 5.6 1.6 -18 0.6 0.2 -8

19/05/2010 3.9 3.0 -8 0.6 0.4 20

28/07/2010 16.6 17.4 -56 1.8 1.8 -44


All Average Load Reduction (%) 36 52

5.4. Discussion

5.4.1. Phosphorus

Phosphorus removal rates at the two newer bioretention systems (Tutus St. and Beatty St.) were

good. Both had exactly 50% removal for orthophosphate (dissolved) and 63% and 53% for total

phosphorus, respectively. Other field bioretention studies with much larger bioretention area to

64

catchment area ratios observed similar total phosphorus and orthophosphate removal rates of 31-

86% (Hatt et al., 2009b, Passeport et al., 2009, Hunt et al., 2008). Laboratory studies under

controlled conditions generally have very good removal rates of 80-95% for total phosphorus and

orthophosphate (Bratieres et al., 2008a, Bratieres et al., 2008b). The lower removal rates at the

Tutus St., Beatty St. and Jellicoe St. systems could have been influenced by the particle size/clay

content of the bioretention media. Phosphorus adsorption capacity of a media generally increases

with clay content due to the increased surface area to volume ratio of the media particles and

increased retention time of the stormwater (Rhue and Harris, 1999). The Tutus St., Beatty St. and

Jellicoe St. systems consist of sandy media to convey the large stormwater volumes through the

small bioretention area to minimise overflowing. Therefore, slightly lower phosphorus removal rates

were expected and observed.

The Jellicoe St. bioretention system performed less efficiently than the other two systems, with

increases of 21% for orthophosphate and 9% for total phosphorus. The negative removal rates may

be caused by the media becoming over-loaded with phosphorus during its seven years of operation.

It is it difficult to know if the poor results were site specific or caused by the system’s age, as no

other studies were found that extensively monitored a bioretention system older than a few years. It

should be remembered that the Jellicoe St. system has a bioretention area to catchment area ratio

of 1%, which is low but not outside the 1%-2% suggested ratio in the WSUD Technical Guidelines for

South East Queensland (Morton Bay Waterways and Catchments Partnership, 2006). Bioretention

systems with small bioretention areas to catchment areas are prone to phosphorus overloading

because they contain a smaller volume of media, which can become saturated with phosphorus at a

faster rate.

65

Orthophosphate made up a high proportion of the total phosphorus concentration at the three

bioretention sites, which is the likely reason why total phosphorus and orthophosphate had similar

removal rates. Despite being dissolved, orthophosphate has high removal rates in bioretention

systems, often similar to total phosphorus removal rates (Passeport et al., 2009, Hatt et al., 2009b,

Line and Hunt, 2009). Orthophosphate has a high capacity to bind with soil particles especially during

the early years of a bioretention system’s life before high levels of phosphorus have built up in the

media. Also, free orthophosphate is believed to be the only form of phosphorus to be directly

utilized by algae and macrophytes (Vymazal, 2007, Metcalf and Eddy, 2003). This means that

orthophosphate can be absorbed from soil into plants, which enables the media to capture more

orthophosphate during future rainfall events.

Plants absorb some phosphorus from bioretention media, which increases the nutrient removal

lifespan of bioretention systems (Greenway and Lucas, 2010). However, most phosphorus that is

removed from stormwater is held in the bioretention media (Greenway and Lucas, 2010). As the

plants reach maturity, growth rates reduce and total plant biomass in a system approaches a

maximum level, which means the uptake of nutrients for plant growth will also reduce (Greenway

and Lucas, 2010). This causes a higher proportion of the phosphorus that is removed from

stormwater to remain in the media as systems age. Plants can be harvested or pruned to allow for

increased growth, and thus greater phosphorus removal (Greenway and Lucas, 2010). However,

little research has been conducted on the maintenance or replanting of bioretention systems.

Plant species selection has a significant impact on phosphorus removal by bioretention systems

(Greenway and Lucas, 2010, Read et al., 2008, Bratieres et al., 2008b). Carex appressa, which is

planted among other species in the three studied systems, has been shown in several bioretention

studies to be the most efficient at removing phosphorus (Bratieres et al., 2008b, Read et al., 2008).

This is due to its fast growth rate, high biomass yield and extensive root system (Read et al., 2008,

66

Read et al., 2010). Use of a mixture of plant species compared to just one species has yet to be

researched in a bioretention study, despite often occurring in constructed field bioretention

systems.

The biggest total phosphorus and orthophosphate concentration reductions at the three

bioretention systems occurred when there was a large phosphorus concentration first flush in the

corresponding inflow concentrations. This is simply because at these times there is a larger load of

the pollutant to be removed. Also, the stormwater has a higher concentration of phosphorus than

the media so the equilibrium between the soil-bound phosphate and the phosphate in the

surrounding pore water is shifted so that more phosphate is adsorbed to the soil particles (Vymazal,

2007). This phosphate may then be desorbed from the soil if the phosphorus concentration in the

water decreases to a certain level (Vymazal, 2007). The total phosphorus and orthophosphate

stormwater inflow concentrations observed in this study were lower than mean concentrations for

other studies, approximately half for total phosphorus and less than a third for orthophosphate. It is

likely that higher inflow concentrations would result in higher removal rates, but may lead to more

rapid over-loading of the bioretention media.

5.4.2. Nitrogen

The Tutus St. and Beatty St. bioretention systems removed 44% and 29% of total nitrogen,

respectively. Total nitrogen is made up of inorganic and organic nitrogen (Metcalf and Eddy, 2003).

Inorganic nitrogen consists of nitrate, nitrite and ammonia, which are all dissolved in water (Metcalf

and Eddy, 2003). The remainder, organic nitrogen can be particulate or dissolved. When the

constituents of total nitrogen are looked at individually, there is little or no change in inorganic

nitrogen at the Tutus St. and Beatty St. systems (refer to Table 5.4). Organic nitrogen, on the other

hand, is being reduced by 60% and 41% at the Tutus St. and Beatty St. systems, which is due to a

67

percentage of organic nitrogen occurring in particulate form (Taylor et al., 2005), allowing it to be

filtered from stormwater by the bioretention systems.

The organic nitrogen that is captured in bioretention systems undergoes the aerobic transformation

of mineralisation to form ammonia (Collins et al., 2010, Vymazal, 2007). Ammonia then oxidises

during the process of nitrification becoming nitrite, which in turn becomes nitrate (Collins et al.,

2010, Hatt et al., 2007b). This means that nitrate may be created in the bioretention systems, which

may explain why the three bioretention systems are observed to be leaching nitrate. Nitrate and

nitrite have low removal rates because they are mobile anions so have a low potential to bind to

bioretention media (Kaushal et al., 2008). Ammonia has high removal rates because it readily binds

to soil particles (Collins et al., 2010, Stevenson, 1994). Also, ammonia is the preferred form of

inorganic nitrogen absorbed by micro-organisms and plants because of its reduced state (Collins et

al., 2010). Therefore, ammonia is efficiently captured in bioretention media then either oxidised or

absorbed by plants, resulting in its good removal rates.

The nitrification process that decomposes the captured particulate organic nitrogen and ammonia,

occurs during the periods between rainfall when the bioretention systems may be dry, as well as

during the comparatively brief times when it is actually raining (Hsieh et al., 2007). This explains how

the transformations occur despite the short retention times of the studied systems. Figure 5.4 shows

the positive correlation between antecedent period and nitrate outflow concentration at the Tutus

St. and Beatty St. sites. This correlation is actually stronger than the correlation between outflow

and inflow concentrations (Fig. 5.5). This suggests that nitrate is being formed during the period

between storms and is being washed from the media during the rainfall events. The longer the

antecedent period, the more nitrate is produced, with higher concentrations subsequently flushed

out of the system. Nitrate outflow EMC and total nitrogen inflow concentration appear to be slightly

correlated (Figure 5.5a). This may indicate that a significant level of nitrification is occurring during

68

rainfall events. However, it is extremely unlikely that nitrate is being formed from organic nitrogen in

the very short period that stormwater is retained in the bioretention systems. Nitrification is a two

stage process involving microbial decomposition of organic nitrogen to ammonia, then the oxidation

of ammonia to nitrate (Collins et al., 2010, Vymazal, 2007). Therefore, it is expected that the

antecedent period allows for both nitrate production in the bioretention media (causing high nitrate

outflow concentration) and also allowing total nitrogen to accumulate in the catchment, leading to

increased inflow of total nitrogen concentrations.

Figure 5-4: Effect of Antecedent period on Nitrate Outflow EMCs at the Tutus St. and Beatty St.

Bioretention Systems, each point is a nitrate outflow EMC for a rainfall event.

R² = 0.9434

0

200

400

600

800

1000

1200

1400

1600

0 5 10 15 20

Out

flow

Nir

tate

EM

C (u

g/L)

Antecedent Period (days)

69

(A) (B)

Figure 5-5: Effect of the Catchment runoff EMCs on Nitrate Outflow EMCs at the (A) Tutus St. and (B)

Beatty St. Bioretention Systems.

Note: The r2 values are substantially less than that of the relationship between antecedent period

and nitrate outflow EMC.

Plant uptake of inorganic nitrogen occurs during the periods between storm events. This process

removes nitrogen from the media, allowing more dissolved nitrogen to adhere to soil particles

during future rainfall events (Greenway and Lucas, 2010, Lucas and Greenway, 2008). However, the

level of nitrate flowing into the system and nitrate that is created from nitrified organic nitrogen, is

far greater than the capacity of plants and microbes to absorb nitrate. Some plant species have been

found to absorb nitrogen better than others in bioretention studies. Carex appressa, which is

planted extensively in the Tutus St., Beatty St. and Jellicoe St. systems, was found in all studies to be

the most effective species at removing nitrate. A species of the Juncus genus, similar to Juncus

usitatus that is planted in all three bioretention systems, was found to be very effective in removing

nitrogen (Read et al., 2008). Despite this, the Tutus St., Beatty St. and Jellicoe St. systems leached

varying concentrations of nitrate. The effectiveness of using a mixture of plant species in a

bioretention system has yet to be researched. The Beatty St. and Jellicoe St. systems contain only C.

appressa and J. usitatus, while the Tutus St. system contains five species, most of which are untested

R² = 0.6345

0

200

400

600

800

1000

1200

1400

1600

0 3,000 6,000

Out

flow

Nit

rate

EM

C (μ

g/L)

TN Inflow EMC (μg/L)

R² = 0.4475

0

200

400

600

800

1000

1200

1400

1600

0 500 1,000

Out

flow

Nit

rate

EM

C (μ

g/L)

Nitrate Inflow EMC (μg/L)

70

in bioretention studies. This could be a reason for the poorer nitrate result at the Tutus St. system,

as plant species can have a significant impact on nitrate removal (Bratieres et al., 2008b, Read et al.,

2008).

The Jellicoe St. bioretention system was found to be the least effective of the three systems,

leaching 24% of total nitrogen. The leaching of total nitrogen is probably the result of the system

being overloaded with nitrogen, which has accumulated in the media during seven years since its

construction. Bioretention systems become overloaded when the soil media has reached its capacity

for absorbing nitrogen. Plants can help extend the life a bioretention system by absorbing nitrogen

from the media. However, net removal rate of nitrogen by plants will decrease once the plants in a

system are fully grown and there is a lack of space for further growth and reproduction. This appears

to have occurred at the Jellicoe St. system, where there does not appear to be any capacity for

further increase in total plant biomass. One option to encourage further nitrogen removal is to

harvest and remove much of the above ground plant biomass, which will promote further growth

(Greenway and Lucas, 2010). Good biomass growth by several monocots that were cropped at a

height of 10 cm every six months, were observed in the Greenway and Lucas (2010) bioretention

study.

The other option for a bioretention system that is at the end of its lifespan, is to dig up and replace

all the plants and the top level of the bioretention media. Almost all the nutrients and other

pollutants in a bioretention system are stored in the media or roots of plants. The cost of buying

new media and plants is only a small percentage of the cost of constructing a whole bioretention

system (Knights et al., 2010). Therefore, this option is generally a substantial, cost-effective and long

term form of maintenance (Knights et al., 2010). The poor nitrogen removal results of the Jellicoe St.

system after seven years since construction, highlights the importance of incorporating maintenance

71

friendly access and design, especially in systems that have a small bioretention area to catchment

area ratio.

The leaching of nitrate at all three sites suggests that dentrification was not occurring. Dentrification

involves the transformation of nitrate to nitrogen gas, which enters the atmosphere (Vymazal, 2007,

Collins et al., 2010). The process requires soil microbes, an electron donor, such as carbon, and is

favoured under anoxic conditions (Vymazal, 2007, Collins et al., 2010). The studied systems are

believed to have aerobic soil conditions in the media because a sandy media was used. Sandy media

has large pore space, which allows air to freely supply oxygen throughout the media. Submerged

zones are a method of encouraging dentrification in bioretention systems (Morton Bay Waterways

and Catchments Partnership, 2006, Blecken et al., 2009). They do this not only by creating an anoxic

zone, but also encourage plant and microbial assimilation processes by retaining moisture in the

media (Bratieres et al., 2008a). There are some very promising results from studies that have

researched the effectiveness of submerged zones (Passeport et al., 2009, Zinger et al., 2007).

However, it is unclear if they will be effective in size constrained bioretention systems, which have

reduced storage capacities and generally sandy aerobic media to accommodate higher hydraulic

conductivity.

Pollutant inflow concentration is expected to have an effect on a bioretention system’s observed

removal rates and this is no different for nitrogen. When there is higher stormwater nitrogen

concentration, there is generally a higher capacity for the nitrogen to bind to the bioretention

media. However, in the long-term, the overall load of nitrogen removed by a bioretention system

may be the same, irrespective of the catchment’s stormwater nitrogen concentration because the

system will reach its capacity sooner. The pollutant inflow concentrations of total nitrogen, ammonia

and NOX (nitrate + nitrite) in the studied catchments were generally 1/2 to 1/3 of the expected

concentrations in Australia’s urban areas (Taylor et al., 2005, NRMMC et al., 2009). This could

72

partially explain the lower removal rates observed in the studied systems, compared to reductions

seen in laboratory studies and some field bioretention studies.

The Jellicoe St. system had especially low concentrations of all forms of nitrogen, which could have

been a factor in the poor reductions seen. The lower concentration could be influenced by specific

catchment land uses and characteristics; also the unintentional sampling of storms with shorter

antecedent periods could have contributed to this effect. Organic nitrogen concentrations in the

Tutus St. and Beatty St. bioretention system inflows were similar to expected concentrations

reported in NRMMC (2009). This, and the particulate nature of organic nitrogen could explain why

the Tutus St. and Beatty St. systems had good removal rates. The very low flow weighted average

concentration of nitrate at the Tutus St. system inflow should be noted as a possible reason for the

29% increase in nitrate concentration at the outflow. The average nitrate inflow concentration at the

Tutus St. system was almost half of that at the Beatty St. system, which had a 2% increase in nitrate.

In conclusion, the removal of nitrogen compounds by bioretention systems is a complex process.

When evaluating nitrogen removal by bioretention systems, Total Nitrogen is the most important

parameter to compare, as specific nitrogen species can transform from one species to another. Total

nitrogen was reduced at the Tutus St. and Beatty St. bioretention systems by 44% and 29%,

respectively. These results were similar to those published in other field bioretention studies, all of

which had larger bioretention area to catchment area ratios (Passeport et al., 2009, Dietz and

Clausen, 2005, Hunt et al., 2008). Inorganic nitrogen, which is bioavailable to plants and

microorganisms, was reduced by -5% and 11% at the Tutus St. and Beatty St. systems, respectively.

These low and negative removal rates, in particular for nitrate, are common in bioretention studies

due to the nitrification of organic nitrogen (Line and Hunt, 2009, Blecken et al., 2010, Hsieh et al.,

2005). The removal rates were poor for all forms of nitrogen at the Jellicoe St. bioretention system

and are believed to be caused by the system becoming overloaded with nitrogen during its seven

73

years since construction. This has important implications for the lifespan and maintenance

requirements of size constrained bioretention systems.

74

Chapter 6. Removal of Metals from Stormwater by Size-

Constrained Bioretention Systems

6.1. Introduction

Stormwater runoff from urban areas has been observed to contain many metals including zinc (Zn),

cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), chromium (Cr), manganese (Mn), iron (Fe),

vanadium (V), cobalt (Co), molybdenum (Mo), aluminium (Al) as well as the metalloid element:

arsenic (As) (Birch and McCready, 2009, Jartun et al., 2008, Sansalone and Buchberger, 1997, Joshi

and Balasubramanian, 2010). Metals in stormwater pollute aquatic ecosystems and can have direct

toxic effects. They are a serious problem for ecological health because of their persistence in the

environment and potential accumulation in living tissue, resulting in increased concentrations at

higher levels of the food chain (Beasley and Kneale, 2002). Runoff from roads and residential areas

has been found to adversely affect growth and development rates in aquatic vertebrates and

invertebrates and has led to increased rates of mortality and morphological deformities (Beasley and

Kneale, 2002, Dorchin and Shanas, 2010).

Cu, Zn and Pb are the most common metals in urban stormwater that can have detrimental effects

on the environment. Therefore, they are the most common metals to be tested in bioretention

studies. Removal rates of total Cu, Zn and Pb in laboratory bioretention studies are consistently very

high, generally ranging from 80-99% for all three metals (Blecken et al., 2008, Hatt et al., 2007b,

Davis et al., 2001a, Bratieres et al., 2008a). Field studies have more variable results, with reductions

in total Cu, Zn and Pb concentrations ranging from 30-98% in studies where multiple temporal

replicates were collected during several storm events (Hunt et al., 2008, Hatt et al., 2009a, Line and

Hunt, 2009, Passeport et al., 2009, Davis, 2007). Metals are captured by bioretention systems

75

because they are often bound to sediments that are filtered out of the stormwater. Also, metals in

solution are positively charged so can be immobilised by negatively charged clay particles through

ion exchange processes and sorption (Brady and Weil, 1999).

Total metal concentrations in stormwater include metals in particulate and dissolved forms.

Dissolved forms of metals are readily bioavailable and very mobile, making them a major concern to

the health of aquatic ecosystems (Boenigk et al., 2005). However, the removal of dissolved metals

from stormwater is rarely monitored in bioretention studies. One laboratory bioretention study that

monitored for dissolved metals (as synthetic stormwater was made with dissolved metal solutions)

recorded very high removal rates of Cu, Cd, Zn and Pb (consistently >90%) (Sun and Davis, 2007).

Muthana (2007) studied the effectiveness of laboratory bioretention systems in the removal of total

and dissolved metals from roadside snow melt. The systems reduced total metal loads, but dissolved

Zn, Cu and Cd were leached from the systems. Only one field bioretention study was found to

monitor dissolved metals; Jonasson (2010) studied two bioretention systems and took a single grab

sample during an actual storm event and two grab samples during an artificial storm event (semi-

synthetic stormwater). The small sampling size led to metal removal rates being extremely variable

with data suggesting total and dissolved Cu was leached from the system, while dissolved Zn had a

strong removal rate despite a negative total Zn reduction at one site.

This section of the study aims to evaluate the effectiveness of the three sized constrained, field

bioretention systems in removing total and dissolved metals from stormwater. Dissolved metals

have not been extensively studied in field bioretention systems.

76


The site descriptions and general field sampling method are described in Chapter 2. Water samples

for metal analysis were collected throughout five rainfall events at each of the three bioretention

systems. Samples were collected in 120ml plastic vials that were pre-soaked in 10% nitric acid for 24

hours. 4ml of each sample was filtered through a 0.2um pore size, cellulose acetate syringe filter into

separate 5ml vials that were also pre-soaked in 10% nitric acid for 24 hours. Samples were stored in

a fridge at 4oC until analysis. The filtrate was analysed for dissolved Cu, Zn, Pb, Cd, Mo, Mn, As, Co,

Ni, V and Cr concentrations using an Agilent 7500 Series Inductively Coupled Plasma – Mass

Spectroscopy (ICP-MS). Nine standards from 0.1ppb to 1ppm and one blank were made to calibrate

the ICP-MS.

To analyse for total concentrations of the nominated metals, a digestion was performed following

the USEPA Standard Method 3005A: Acid digestion of waters for total recoverable or dissolved

metals for analysis by FLAA or ICP spectroscopy. This involved transferring 100ml of unfiltered

sample to a beaker that had been acid washed and rinsed with reagent grade water. 2ml of supra-

pure concentrated nitric acid and 5ml of supra-pure concentrated hydrochloric acid were added.

Beakers containing the samples were heated on a steam bath until the volume of the sample was

reduced to 15-20ml. The sample was diluted back to 100ml and 5ml of sample filtered through a

0.2um pore size syringe filter to remove any insoluble material. Multiple blank samples containing

reagent grade water were subjected to the full digestion procedure for quality control. Digested

samples were analysed for total Cu, Zn, Pb, Cd, Mo, Mn, As, Co, Ni, V and Cr concentrations using

ICP-MS. This was carried out by the author and technical staff at the University of Technology,

Sydney, School of Chemistry and Forensic Science laboratories.

77

6.3. Results

The total and dissolved metal concentrations at the inflow of the three bioretention systems are

shown in Table 6.1. The total metal and dissolved metal concentration removal rates of the three

bioretention systems are shown in Table 6.2. Total Cu, Zn, and Pb were reduced by an average of

66%, 58% and 61%, respectively. Dissolved Zn had the highest concentration of dissolved metals and

had a concentration reduction of 52% at the Tutus St. system, 37% at the Beatty St. system and 4%

at the Jellicoe St. system. The percentage of each metal in the dissolved form, found at the inflow of

each system, is shown in Table 6.3. The portion of total metals that were dissolved, was lowest at

the inflow to the Jellicoe St. catchment. The metals with the highest dissolved percentage were Zn, V

and Mo, metals with the lowest dissolved percentage were Mn and Cr. Figures 6.1, 6.2 and 6.3 show

the inflow and outflow concentrations throughout a rainfall event for total Cu, dissolved Cu, total Zn,

dissolved Zn, total Pb and dissolved Pb. Only the longest sampled rainfall event, where the start of

the rainfall event was captured, is graphed for each bioretention system.

Total and dissolved Cd, Co, Ni and As removal rates are not shown because concentrations above the

background concentrations levels could not be detected. All dissolved metal concentrations (except

Zn) as well as total Cr, Mn and V, were very low at all sites. The calculated reduction concentrations

for these metals may not be a true representation of the actual reduction because many samples

had equal or less concentrations than the background average concentrations. A small change in

pollutant concentration in a few samples can skew the entire data set, leading to a very large,

unrepresentative percentage concentration change. Therefore, it is possible that there was little, to

no change, in the concentrations of these metals at the three sites. However, it is still likely that the

removal rates of dissolved metals are consistently lower than removal rates of total metals,

especially at the Jellicoe St. bioretention system, where leaching of dissolved metals appeared to

occur.

78

Table 6-1: Flow Weighted Average Inflow Concentrations for Total and Dissolved Metals.

*The load at the inflow was divided by the total flow at the inflow to create the average

concentration.

Total Metals (μg/L) Dissolved Metals (μg/L) Tutus Beatty Jellicoe Tutus Beatty Jellicoe

Cu 32.5 5.3 13.0 6.4 1.7 0.7 Zn 156.8 28.7 105.0 85.2 16.0 23.4 Pb 18.5 6.3 39.6 3.9 3.3 3.3 Mn 24.9 29.4 39.1 1.4 4.7 0.1 V 1.0 2.8 4.4 0.2 2.7 0.7 Cr 2.0 1.6 3.8 0.1 0.1 0.4

Mo 3.0 2.2 0.9 1.0 1.2 2.7 Cd <LOD 0.1 0.1 <LOD <LOD <LOD Co <LOD <LOD <LOD <LOD <LOD <LOD Ni <LOD <LOD <LOD <LOD <LOD <LOD As <LOD <LOD <LOD <LOD <LOD <LOD

<LOR – Less than Limit of Detection

Table 6-2: Concentration Reductions (%) of Total and Dissolved Metals.

*The load at the inflow and outflow was divided by the total flow at the inflow and outflow to create

the average concentration, this was used to calculate the concentration percentage reduction.

Tutus

(% reduction) Beatty

(% reduction) Jellicoe

(% reduction) Average

(% reduction) Dissolved Total Dissolved Total Dissolved Total Dissolved Total

Cu 6 55 30 59 -58 85 -7 66 Zn 52 66 37 44 4 74 31 58 Pb 4 43 9 54 -2 87 4 61 Mn 100 75 94 80 100 95 98 82 V 100 100 12 -35 -168 59 -19 41 Cr 57 -5 42 23 -81 57 6 25

Mo -15 15 15 82 57 22 19 27

Table 6-3: Dissolved Portion of Total Metal Concentrations (%).

Tutus

(% dissolved) Beatty

(% dissolved) Jellicoe

(% dissolved) Average

(% dissolved)

Cu 20 32 6 19 Zn 54 56 22 44 Pb 21 53 8 27 Mn 6 16 0 7 V 20 98 15 44 Cr 5 6 9 7

Mo 33 56 311 133

79

The average total metal inflow and outflow concentrations in the bioretention systems are

compared to ANZECC/ARMCANZ (2000) water quality trigger guidelines for the protection of aquatic

ecosystems in Table 6.4 (Agriculture and Resource Management Council of Australia and New

Zealand, 2000). Total Zn and Cu stormwater concentrations were reduced by the bioretention

systems to less than the 80% species protection level for marine environments. While total Pb was

reduced to less than the 90% species protection level for marine environments, only total Pb was

reduced to less than the 80% species protection level for freshwater environments. All other metals

are not shown because there was either no guideline available, or their inflow concentrations were

already under the 99% species protection level for both freshwater and marine environments.

Table 6-4: Average Total Metal Inflow and Outflow concentrations at the bioretention systems and

ANZECC/ARMCANZ (2000) total metal trigger guidelines for the protection of aquatic ecosystems.

Note: Zn, Cu and Pb were the only metals that had inflow concentrations higher than the 99%

species protection level (Agriculture and Resource Management Council of Australia and New

Zealand, 2000).

Species Protection Level (%)

Freshwater Marine Average Inflow Concentration of

the Systems

Average Outflow Concentration of

the Systems 99 95 90 80 99 95 90 80

Zn (μg/L) 2.4 8 15 31 7 15 23 43 97 32

Cu (μg/L) 1 1.4 1.8 2.5 0.3 1.3 3 8 17 6

Pb (μg/L) 1 3.4 5.6 9.4 2.2 4.4 6.6 12 21 6

80

Figure 6-1: The inflow and outflow concentrations of metals most commonly found in residential

stormwater, throughout the 28/1/10 rainfall event at the Tutus St. system.

81


stormwater, throughout the 16/5/10 rainfall event at the Beatty St. system.

82


stormwater, throughout the 5/5/10 rainfall event at the Jellicoe St. system.

83

6.4. Discussion

The concentrations of total Cu, Pb and Zn were reduced by an average of 66%, 61% and 58%,

respectively. These removal rates are encouraging considering the systems’ very small bioretention

area to catchment area ratios. The removal rates were lower than the observed results in published

laboratory bioretention studies (Blecken et al., 2008, Hatt et al., 2007b, Davis et al., 2001a, Bratieres

et al., 2008a). However, the removal rates of Cu, Zn, and Pb at the Tutus St., Beatty St. and Jellicoe

St. sites were similar to and more consistent than the removal rates found in some other

bioretention field studies. This includes a bioretention system with a submerged zone and a

bioretention area to catchment area ratio of 2.2% (Davis, 2007). This system (in Maryland, USA) had

reductions of 51%, 79% and 28% for Cu, Pb and Zn, respectively. Another bioretention system in

North Carolina, with a bioretention area to catchment area ratio of 6.1%, had reductions of 54%,

31% and 77% for Cu, Pb and Zn, respectively (Hunt et al., 2008). Other field bioretention studies

recorded greater metal removal rates (Hatt et al., 2009a). Overall, it is clearly evident that metal

removal rates in field bioretention studies are generally lower than, and not as consistent compared

with laboratory bioretention studies. When taking into account the small bioretention area to

catchment area ratio, the Tutus St., Beatty St. and Jellicoe St. systems showed good removal rates,

similar to other field bioretention studies with greater bioretention to catchment area ratios (Hunt

et al., 2008, Davis, 2007). Outflow total metal concentrations were generally reduced to

concentrations close to or below the 80% Species Protection Level guideline concentration listed in

the ANZECC/ARMCANZ (2000) document.

The total metal reductions showed that the Jellicoe St. system is performing well in removing

particulate metals from stormwater. The higher total metal removal efficiencies at the Jellicoe St.

system, compared to the other two systems are probably due to the larger bioretention area to

catchment area ratio, which allows for a longer detention time, so increased potential for particulate

84

metals to be filtered or settled out of stormwater. The high ratios of particulate metals over

dissolved metals in the stormwater inflow at the Jellicoe St. catchment are another reason for the

high total metal removals (Hares and Ward, 1999, Sun and Davis, 2007). Particulate metals are

bound to suspended solids, so are able to be filtered from stormwater as it passes through the

media in bioretention systems (Hares and Ward, 1999, Sun and Davis, 2007). It is generally believed

that metals that more readily occur in particulate form in stormwater are more likely to have higher

total metal removal rates (Hares and Ward, 1999, Sun and Davis, 2007).

Removal of dissolved metals is expected to be low due to the short retention times of the studied

bioretention systems. This leads to insufficient time for the chemical bonding of dissolved metals to

media particles. Media with high sand content has reduced particle surface area causing reduced

capacity for metal ions to be removed from stormwater as it passes through the system (Muthanna

et al., 2007). Clay particles in soil, not only have a high surface area to volume ratio, but are typically

negatively charged so are easily able to immobilise the positively charged metal cations by ion

exchange processes and sorption (Brady and Weil, 1999). This explains why good total metal

removal rates are common in larger bioretention systems, where large amounts of silt and clay can

be incorporated into the media (Hatt et al., 2009a, Davis et al., 2001a).

Zn was the only metal found in high concentrations in the dissolved form at all sites. Recorded

dissolved Zn concentration reductions were 52%, 37% and 4% in the Tutus St., Beatty St. and Jellicoe

St. systems, respectively. Dissolved Pb concentration had almost no change at all three sites, while

dissolved Cu concentration was reduced by 6% at the Tutus St., 30% at Beatty St. and -58% at Jellicoe

St. systems. The Jellicoe St. system had consistently poor results for dissolved metals, despite very

good reductions in total metal concentrations. This was surprising due to the larger bioretention

area to catchment area ratio and longer retention times. The poor results could be caused by the

system retaining high levels of total metals since its construction seven years ago. This could have

85

resulted in the media being overloaded and very small concentrations of dissolved metals may now

be leaching from the system.

Muthanna (2007) conducted a snowmelt bioretention study that analysed samples for total and

dissolved metals simultaneously. The laboratory bioretention systems increased dissolved Zn, Cu and

Cd by 372%, 14% and 310% above inflow concentrations, respectively. It was assumed that some

dissolved metals were passing through the media without absorption. Cu and Zn leaching tests were

conducted on the media at the conclusion of the study and the media was found to be leaching

concentrations of 30-40 μg/L for both metals.

The poor dissolved metal removal rates observed in present study could have been influenced by

accumulated metals in the bioretention media becoming oxidised during dry periods, then washed

out during the next rainfall event (Blecken et al., 2008). This is supported by the sandy media being

prone to drying, leading to aeration of the pore spaces. Also, Cu is known to have a very high rate of

adsorption to the carbon in organic matter (Reuter and Perdue, 1977). However, other metals have

much less affinity for organic matter and they may be desorbed from media particles in bioretention

systems, if the pH of the stormwater is low enough (Yin et al., 2002). The pH in the inflow and

outflow stormwater at the Beatty, Tutus and Jellicoe St, systems was generally neutral, ranging from

6.0 to 7.8 (Appendix 10.1: Raw data)

It is a common misconception that plants in bioretention systems retain a high percentage of the

metals removed from stormwater. In fact, over 92-99% of the metals removed by bioretention

systems are retained in the media and 0.5-8% is absorbed into the plants (Muthanna et al., 2007,

Sun and Davis, 2007). Plants still play an important role in maintaining hydraulic conductivity and

stability of the media. However, it means that almost all the metals captured by the bioretention

system remains in the media. As metals accumulate, the capacity for further metals to be removed

86

from stormwater reduces and there is an increasing potential for considerable metal loads to

dissolve and detach from media particles. The lifespan and efficiency of bioretention systems at

different ages, is an area that requires further research and will help influence decisions on the

management and maintenance of such systems.

In conclusion, the concentrations of total Cu, Pb and Zn, were reduced by an average of 66%, 61%

and 58%, respectively. These removal rates are encouraging considering the systems’ very small

bioretention area to catchment area ratio. The removal rates of dissolved metals were much lower

than that for total metals. The oldest bioretention system, constructed in 2003, leached extremely

small loads of dissolved metals, suggesting that stormwater may be dissolving metals that have been

captured in the media. Overall, the size constrained bioretention systems in the present study have

shown strong potential to improve stormwater quality emanating from urban areas.

87

Chapter 7. Removal of Faecal Indicator Bacteria from

Stormwater by Size-Constrained Bioretention Systems

7.1. Introduction

Bacteria, Protozoa and viruses are the most common forms of pathogens that are found in

recreational waters (NSWDECCW, 2010). Exposure to pathogens can cause eye, ear, skin and upper

respiratory infections, which can sometimes result in death (NSWDECCW, 2010). Gastroenteritis is

the most common illness associated with polluted water and symptoms include vomiting, diarrhoea,

stomach-ache, head-ache, nausea and fever (NSWDECCW, 2010, NRMMC et al., 2009). In 2003,

approximately 14.4% of water bodies in the USA (8,560 water bodies tested) were impaired by

pathogens (Rusciano and Obropta, 2007). Groundwater is also frequently contaminated with

pathogens (Wellings, 1982, Pitt et al., 1999), which is concerning because groundwater is an

important source of drinking and irrigation water for many populations. The source of pathogens in

stormwater include: dog, bird and other animal faeces, septic tank leakages and sewer overflows

(Carroll et al., 2009, Whitlock et al., 2002, McDonald et al., 2006).

Due to the cost to analyse water samples for pathogen concentrations, faecal indicator bacteria are

often monitored because they indicate the presence of human sewage and pathogens in water.

These include faecal (thermo-tolerant) coliforms and bacteria in the Enterococci genus (Jin et al.,

2004, Rusciano and Obropta, 2007). Faecal coliform bacteria are also known as thermo-tolerant

bacteria and mostly consist of Escherichia coli (E. coli)(NRMMC et al., 2009). Enterococci are

generally seen as a conservative indicator because they persist longer than faecal coliforms in water

(Jin et al., 2004). Faecal indicator bacteria generally do not cause illness (USEPA, 2008, International

Commission on Microbiological Specifications for Foods, 1978), they originate from the digestive

88

tracts of warm blooded animals (McDonald et al., 2006) and their presence suggests the occurrence

of pathogens from the same origin.

Filtration and adsorption to soil particles are the main processes that capture/remove pathogens in

bioretention systems (Rusciano and Obropta, 2007). Adsorption is probably the primary mechanism

for removal because pathogens and the particles they are bound to in stormwater are expected to

be too small to be filtered by bioretention systems (Stevik et al., 2004, Davies and Bavor, 2000,

Sharma et al., 1985, Buchan and Flury, 2004). Pathogens in water and sediment are believed to be

killed by desiccation (drying), UV sunlight, increased temperature, lack of organic matter, contact

with certain surfaces (such as iron oxide) and predation by some protozoans and coliphages

(Rusciano and Obropta, 2007, Buchan and Flury, 2004, Stevik et al., 2004).

Few laboratory and field studies have analysed the effectiveness of bioretention systems in

removing bacteria or indicator pathogens from stormwater. Generally good removal rates have been

observed in studied bioretention systems except for one, which had only a 0.25m media depth (see

Tables 7.1 and 7.2).

Table 7-1: Microbial results from some of the published bioretention field studies.

Note: Bold figures are the percentage concentration reduction.

Field Study Hunt et al. 2008 (Passeport et al., 2009) (Hunt et al., 2010)

Site/Location NC, USA NC, USA NC, USA NC, USA NC USA

Comments Only sampled small & medium storms

Grassed with Submerged

Zone

Grassed with Submerged

zone

0.6m media depth

0.25m media depth

Bioretention area to catchment area ratio (%)

6.1 3.2 3.2

E. coli 71 70 -119

Faecal Coliforms 69 95 85

Enterococci 89 -102

89

Table 7-2: Microbial results from published bioretention small-scale studies.

Note: Bold figures are the percentage concentration reduction.

Laboratory Study (Bratieres et al., 2008a) (Rusciano and Obropta, 2007)

Location of Bioretention Study VIC, AUS NJ, USA

Comments Acidic media

Faecal Coliforms (bacteria) 91.6

E. coli (bacteria) 82

C. perifringens (protozoa) >99

F-RNA phages (virus) 97

This study involved monitoring faecal coliform and Enterococci bacteria at the inflow and outflow of

three size constrained bioretention systems. The aim of this chapter is to evaluate the effectiveness

of three bioretention systems in removing faecal indicator bacteria.


The site descriptions and general field sampling method is provided in Chapter 2. Faecal indicator

bacteria were monitored during 3 rainfall events at the Tutus St. bioretention system, 3 events at

the Beatty St. system and 2 events at the Jellicoe St. system. Samples were collected in 500 ml sterile

bottles and delivered on ice to Sydney Water’s NATA Accredited West Ryde laboratory for analysis

within 18 hours of collection. Each sample was analysed for Enterococci and faecal coliforms by

Sydney Water, the membrane filter technique was used to analyse for both types. The turbidity of

each sample (collected in 1L polyethylene bottles) was also measured. This involved analysing 20ml

of sample using a Hach Turbidity meter in the UTS School of the Environment Labs.

7.3. Results

The Tutus St. and Beatty St. bioretention systems demonstrated good average faecal coliform

concentration reductions of 72% and 82%, respectively (Table 7.3). The Jellicoe St. system showed

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an increase in faecal coliform concentrations, with an average removal rate of -79%. The average

faecal coliform inflow concentrations were 30,121cfu/100ml at Tutus St, 62,994cfu/100ml at the

Beatty St. system and only 507cfu/100ml at the Jellicoe St. system.

Table 7-3: Faecal coliform removal rates, EMC’s and standard deviations (SD) at the inflow and

outflow, during each sampled rainfall event.

*Calculated by weighting each EMC according to total flow volume in that event.

Site Event

Faecal Coliform Concentration


(%) EMC (cfu/100ml)

SD (cfu/100ml)

EMC (cfu/100ml)

SD (cfu/100ml)

Tutu

s

28/01/2010 74,325 N/A 20,000 N/A 73

29/03/2010 83,276 ±59,828 48,212 ±21,595 42

30/03/2010 2,875 ±1,069 2,544 ±551 12

*Average Concentration 30,121 8,435 72

*Total Reduction (%) 72

Beat

ty

28/02/2010 35,500 ±26,801 14,000 N/A 61

16/05/2010 119,213 ±93,871 21,988 ±1,439 82

01/12/2010 4,847 ±1,254 4,230 ±956 13



Jelli

coe

05/05/2010 417 ±239 955 ±251 -129

28/07/2010 513 ±274 907 ±874 -77

*Average Concentration 507 908 -79

*Total Reduction (%) -79

All

Average Concentration 31,207 6,978 78

Average Reduction (%) 25

Enterococci reductions varied, with the Tutus St. system recording an average concentration

reduction of 35% and Beatty St. system recording a -5% concentration reduction (Table 7.4). The

Jellicoe St. system also performed poorly for Enterococci, with an average removal rate -117%. The

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average Enterococci concentrations in the inflow were 2,663cfu/100ml at the Tutus St. system,

4,651cfu/100ml at the Beatty St. system and 1,125cfu/100ml at the Jellicoe St. system.

Table 7-4: Enterococci removal rates, EMC’s and standard deviations (SD) at the inflow and outflow,

during each sampled rainfall event.

*Calculated by weighting each EMC according to total flow volume in that event.

Site Event

Enterococci Concentration


(%) EMC (cfu/100ml)

SD (cfu/100ml)

EMC (cfu/100ml)

SD (cfu/100ml)

Tutu

s

28/01/2010 5,565 ±4,585 3,279 ±447 41

29/03/2010 5,039 ±2,943 794 ±722 84

30/03/2010 1,114 ±375 1,160 ±180 -4



Beat

ty

28/02/2010 1,357 ±126 3,400 N/A -151

16/05/2010 3,518 ±13,811 3,222 ±1,045 8.4

01/12/2010 6,413 ±1,544 6,123 ±2,377 5

*Average Concentration 4,651 4,893 -5


Jelli

coe

05/05/2010 1,561 ±359 1,705 ±360 -9

28/07/2010 1,095 ±735 2,463 ±2,159 -125

*Average Concentration 1,125 2,445 -117


All

Average Concentration 2,813 3,020 -7

Average Reduction (%) -29

The graphs in Figures 7.1 – 7.3 show the Inflow and outflow concentrations for faecal coliforms and

Enterococci throughout each monitored rainfall event. It should be noted that the graphs in Figures

7.1 - 7.3 show the actual time of sample collection. The 10-15 minute sample retention time of the

bioretention systems result in a 10-15 minute apparent shift in the inflow and outflow curves, which

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should be considered when comparing individual samples. The graphs for events on the 28/1/10 and

29/3/10 at the Tutus St. system, which had antecedent periods of 4 and 16 days, respectively,

showed strong ‘first flushes’ for both faecal coliforms and Enterococci. The graphs for events on the

28/2/10 and 169/5/10 at the Beatty St. system, which had antecedent periods of 3 and 11 days,

respectively, showed strong ‘first flushes’ for faecal coliforms but not Enterococci. Antecedent

periods were five days and less than 2 days for the two events at the Jellicoe St. system and no clear

‘first flush’ was observed for both faecal coliforms and Enterococci. The rainfall duration, antecedent

period and rainfall volume for all sampled rainfall events is shown in Table 3.1.

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Figure 7-1: Faecal indicator and Enterococci concentrations in the Tutus St. bioretention system.

Left Column: Inflow and outflow faecal coliform concentrations throughout each monitored rainfall

event. Right Column: Inflow and outflow Enterococci concentrations throughout each monitored

rainfall event.

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Figure 7-2: Faecal indicator and Enterococci concentrations in the Beatty St. bioretention system.

Left Column: Inflow and outflow faecal coliform concentration throughout each monitored rainfall

event. Right Column: Inflow and outflow Enterococci concentration throughout each monitored

rainfall event.

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Figure 7-3: Faecal indicator and Enterococci concentrations in the Jellicoe St. system.

Left Column: Inflow and outflow faecal coliform concentration throughout each monitored rainfall

event. Right Column: Inflow and outflow Enterococci concentration throughout each monitored

rainfall event.

7.4. Discussion

Of the three bioretention systems, the Tutus St. and Beatty St. systems demonstrated very good

faecal coliform reductions, considering their small bioretention area to catchment area ratios, short

retention times and sandy media. Other bioretention studies, which monitored microbial indicators,

have much larger bioretention area to catchment area ratios. Hunt (2008) studied a bioretention

system that had a bioretention area to catchment area ratio of 6.1% and was found to reduce faecal

coliforms by 69% and E. coli by 71%. These reductions are lower than the removal rates of 72% and

82% at the Tutus St. and Beatty St. systems, respectively, despite bioretention area to catchment

area ratios of less than 1%. The two bioretention systems monitored in Passeport (2009) had a

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bioretention area to catchment area ratios of 3.2% and were found to have high faecal coliform

removal rates of 95% and 85%. Bratieres (2008a) observed 82% reductions in E. coli in the studied

columns that had a representative bioretention area to catchment area ratio of 2%. Overall the

performance of the Tutus St. and Beatty St. systems are similar to that of bioretention systems with

much larger bioretention area to catchment area ratios.

The two main processes that enable bioretention systems to remove microbes from stormwater are

filtration and adsorption (Rusciano and Obropta, 2007, Buchan and Flury, 2004). Filtration (straining)

generally removes microbes or particles that have a diameter of at least 5% of the diameter of the

average media grain diameter (Buchan and Flury, 2004, Bouwer, 1984). Individual and clumps of

microbes generally have smaller diameters than this, especially when compared to the grain size of

sandy media (Buchan and Flury, 2004). Even when attached to small clay particles in stormwater,

bacteria and other microbes will generally have diameters of less than 2um so may not be removed

by sandy media (Buchan and Flury, 2004, Davies and Bavor, 2000). As a result, adsorption is believed

to be the most important process for the removal of bacteria by the studied bioretention systems

which contain sandy media (Buchan and Flury, 2004, Hunt et al., 2010, Stevik et al., 2004).

Adsorption involves the binding of microbes (and the particles that they are attached to) to media

soil particles. Adsorption is believed to be more prolific in media that is high in clay particles because

the pore sizes are smaller so retention time of the stormwater in the media is greater, the

electrostatic attraction to clay is higher and the surface area to volume ratio of the particles is

greater (Davies and Bavor, 2000, Huysman and Verstraete, 1993). This is potentially why the

bioretention system studied in Passeport (2009), which had media consisting of 80% expanded slate

fines, was found to reduce faecal coliform concentrations by 95%. However, many sand filters and

bioretention systems with sandy media have been found to be effective at the capture of microbes

through adsorption (Birch et al., 2005, Barrett, 2003). Birch (2005) analysed an infiltration basin with

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over 80% of the media consisting of 2mm diameter sand particles and found faecal coliform

concentrations to be reduced by 96%. More research is needed on the factors that affect the

adsorption of microbes in sandy media, as this will aid in the design and management of stormwater

treatment devices. Adsorption of microbes to media is believed to be influenced by media

composition, pH, particle size, formation of preferential flow paths, organic matter accumulation,

biofilm development, electrostatic attraction (solution ion strength and the charges of cell and

particle surfaces), retention time and rate of hydraulic loading (Stevik et al., 2004, USEPA, 1992).

However, the extent and impact of each factor on microbe adsorption is not well understood.

Following adsorption of microbes from stormwater, the main method of subsequent inactivation of

microbes in bioretention systems and sand filters is believed to be desiccation (Hunt et al., 2008,

Bratieres et al., 2008a). The Tutus St. and Beatty St. bioretention systems have good drainage, which

would assist in the inactivation of bacteria by desiccation between rainfall events.

The removal rates of Enterococci in the studied bioretention systems were considerably lower than

the faecal coliform removal rates. The most probable reason is that Enterococci are more resilient

and able to survive longer in water (Jin et al., 2004). A potential reason is that predation by

protozoans may preferentially favour faecal coliforms over Enterococci (González et al., 1990).

Enterococci may be more likely to be bound to clay particles in stormwater than faecal coliforms

making them more protected from predation (Huysman and Verstraete, 1993, Davies and Bavor,

2000). Decamp and Warren (1998) suggested predation by ciliate protozoans could account for total

removal of E. coli from waste water in constructed wetlands. However, the dry nature of

bioretention systems and short stormwater retention times are not expected to allow for significant

predation. Given that desiccation is believed to be the main process in the inactivation of bacteria by

bioretention systems, the lower removal rates of Enterococci compared to faecal coliforms are

believed to be due to the greater resilience of Enterococci over faecal coliforms. Our results support

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this explanation and highlight the fact that Enterococci is a conservative indicator, making it,

arguably, a more suitable indicator of potential pathogen contamination. However, the differences

suggest that it is important to test for multiple types of microbes when evaluating the removal of

pathogens by bioretention systems.

The Jellicoe St. bioretention system performed much worse than the other two bioretention

systems, increasing faecal coliform concentration by 79% and Enterococci concentrations by 117%.

One possible reason is that the build-up of nutrients in the Jellicoe St. system during its seven years

since construction could have reduced the capacity of the media to bind to bacteria (USEPA, 1992).

This is because organic matter and bacteria are believed to have the same electrostatic charge, so

they may compete for adsorption sites in soil (USEPA, 1992). This suggests that media may have to

be replaced in bioretention systems if organic matter levels become too high, in order improve

bacteria removal rates.

The high levels of organic matter in the media could compound the problem of bacterial removal in

two ways. Bacteria require nutrients to survive, the build-up of organic matter in bioretention

systems is a source of nutrients, which could sustain bacterial survival and reproduction during

periods between rainfall events (Stevik et al., 2004, Buchan and Flury, 2004, Pitt et al., 1999,

Goldshmid, 1974, Hathaway et al., 2009). A moist environment is also critical for bacterial survival

(Hathaway et al., 2009, Stevik et al., 2004), organic matter that has accumulated on the surface of

bioretention systems could act as mulch, reducing water loss from the soil media. The survival and

reproduction of the bacteria in the moist, nutrient rich, bioretention media could have caused the

observed leaching of faecal indicator bacteria concentrations by the Jellicoe St. system. Salmonella

and Shingella have been found to survive for 44 and 24 days in a groundwater recharge site in Israel

(Goldshmid, 1974). Enteric bacteria survive in soil between two and three months and survival times

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of up to five years have been documented (Crites, 1985). This could result in release of higher

concentrations in the outflow compared to the inflow during rainfall events.

It is also possible that the poor faecal coliform and Enterococci results at the Jellicoe St. system

compared to the other two systems were caused by other issues associated with old age or slight

differences in design. For example, preferential flow paths, media scouring and short-circuiting could

result in decreased contact time between stormwater and the media, reducing removal rates

(Bratieres et al., 2008a, Buchan and Flury, 2004). Inefficient drainage caused by poor

design/construction or lack of repair and maintenance could allow the bacteria in the media to

survive and reproduce. Unfortunately, the exact flow path of stormwater in the system cannot be

assessed due to a very tall and thick growth of vegetation covering the entire media surface of the

bioretention system.

Hunt (2010) provides the only published bioretention study that reported negative bacteria removal

rates in a bioretention system. The negative reductions were observed in a bioretention system that

had a very shallow media depth of 0.25 meters, while a very similar system with a media depth of

0.6 meters showed very good removal rates of about 80%. Media with a shallow depth will have

decreased contact time between stormwater and media. It is also more likely that a larger

proportion of the media will be affected if there is poor drainage. This along with increased organic

matter loading per cubic meter of media, could allow microbes to survive and reproduce in the

system and be flushed out during subsequent storms. To reduce this potential risk, it is

recommended that media depths are at least 0.6 meters (Hunt et al., 2010, Morton Bay Waterways

and Catchments Partnership, 2006).

Another possible reason for the observed bacteria leaching at the Jellicoe St. system could be the

sampling of rainfall events that do not represent normal faecal indicator bacteria concentrations at

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the site. Average inflow faecal coliform concentrations were only 507 cfu/100ml at the Jellicoe St.

system, about 2% that of the Tutus St. system and less than 1% of that of the Beatty St. system,

while average inflow Enterococci concentrations were only 1,125 cfu/100ml at the Jellicoe St.

system, less than 50% of that at the Tutus St. system and less than 25% of that at the Beatty St.

system. The lower levels could be caused by catchment land use, but there are similar catchment

land uses (such as dog walking) in the catchments of all three bioretention systems. It appears that

the two rainfall events that were sampled at the Jellicoe St. system had a short antecedent period

and lower faecal indicator bacteria concentrations than previous rainfall events. This could have

meant that bacteria that were captured during the previous rainfall event were still alive in the

media during the sampled rainfall event. They could have then been flushed out of the media,

making the system appear as a source of faecal indicator bacteria during the sampled events.

The potentially high concentrations of illness causing pathogens in stormwater is the main reason

that stormwater must be treated before reuse. The NSWDECC (2006) guidelines for stormwater

treatment and reuse, suggest that stormwater treatment should result in a 96% reduction of viruses

and bacteria and an 82% reduction of protozoan parasites. Both the NRMMC (2009) and NSWDECC

(2006) guidelines suggest median E. coli concentrations of <10cfu/100ml for stormwater to be used

for irrigation of open spaces, parks and sportsgrounds that have no access controls. The NRMMC

(2009) guidelines also have a suggested stormwater E. coli concentrations of <1000cfu/100ml if the

stormwater is to be used for irrigation of open spaces, parks and sportsgrounds that have controlled

access.

Faecal coliforms are mostly made up of E. coli (NRMMC et al., 2009) and it is clear that the studied

bioretention systems cannot reduce faecal coliform concentrations to <1000cfu/100ml, or to the

stormwater reuse guideline of <10cfu/100ml. To our knowledge, no field studies have observed the

>96% reductions in bacteria, which are suggested in the NRMMC (2009) guidelines.

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Where stormwater is also to be used for irrigation, additional factors are also relevant for

consideration. For subsequent stormwater treatment measures to be utilised with bioretention

systems to enable reuse, other parameters must also be considered. If UV light disinfection is to be

used to treat stormwater, guidelines recommend turbidity levels be reduced to 2 NTU (NSWDECC,

2006). This is because particles can shield pathogens from UV light when the turbidity of the water

increases, making UV light less effective at disinfecting stormwater. Few studies have measured the

effectiveness of bioretention systems in reducing the turbidity of stormwater. The bioretention

system analysed in Line & Hunt (2009) was found to increase turbidity by 7% to an outflow of 17

NTU.

The Tutus St., Beatty St. and Jellicoe St. bioretention systems were found to reduce turbidity by an

average of 18% from a flow-weighted average inflow of 5.4 NTU to an outflow of 4.3 NTU. This is

close to the recommended turbidity levels for UV disinfection. The results were varied between the

three systems, with the Tutus St. system reducing turbidity by 43%, while the Beatty St. and Jellicoe

St. systems reducing turbidity by 5% and 6%, respectively. Overall, with more research, an

opportunity exists for size constrained bioretention systems to act as a potential treatment method

for stormwater to reduced turbidity before it is disinfected with UV light for reuse.

To conclude, faecal colifom concentrations in stormwater were reduced by about 70% - 80% at the

Tutus St. and Beatty St. bioretention systems. This shows strong potential for the use of size

constrained bioretention systems in the removal of pathogens from stormwater. The removal of

Enterococci by the Tutus St. and Beatty St. systems was found to be inefficient, suggesting that the

removal of different microbes may vary. The Jellicoe St. system, which is seven years old, was found

to increase faecal coliform and Enterococci stormwater concentrations. The reason for these results

is unclear, but it may have been caused by unrepresentative sampling, poor media drainage or

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accumulation of organic matter in the media. It is recommended that further research is conducted

on the bacteria removing efficiency and lifespan of size constrained bioretention systems.

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Chapter 8. Conclusions and Recommendations

8.1. Conclusions

This research thesis examined the effectiveness of three size constrained bioretention systems

(Tutus St., Beatty St. and Jellicoe St.) in removing suspended solids, nutrients, metals and faecal

indicator bacteria from stormwater. The removal rates of stormwater pollutants by the three

bioretention systems are shown in Table 8.1. Compared to conventionally sized bioretention

systems, the size-constrained systems were found to be effective at improving stormwater quality.

The results show that there is strong potential for the widespread use of size-constrained

bioretention systems in urban areas.

In terms of suspended solids, all three of the studied size-constrained bioretention systems were

effective at removing TSS from stormwater, compared to other field studies of bioretention systems.

This could be due to the ability of the media to filter solids from stormwater. During heavy rainfall,

the reed-like plant species were effective at filtering solids from surface flows and slowed down the

flow rate allowing solids to settle out of the water column.

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Table 8-1: Removal rates of stormwater pollutants by the three bioretention systems

*Extremely small concentrations.

Tutus

(% reduction) Beatty

(% reduction) Jellicoe

(% reduction) Average

(% reduction)

Suspended Solids TSS 70 79 85 78

Nutrients

Total Phosphorus 63 53 -9 36 Orthophosphate 50 50 -21 26 Total Nitrogen 44 29 -24 17

Organic Nitrogen 60 41 -12 30 Inorganic Nitrogen -4 11 -33 -9

Nitrate -29 -2 -57 -29 Nitrite 22 5 -11 5

Ammonia 74 68 36 59

Metals

Total Cu 55 59 85 66 Total Zn 66 44 74 58 Total Pb 43 54 87 61

Dissolved Cu 6 30 -58* -7 Dissolved Zn 52 37 4 31 Dissolved Pb 4 9 -2 4

Microbes Faecal Coliforms 72 82 -79 25

Enterococci 35 -5 -117 -29

In terms of total phosphorus and orthophosphate, the two newer bioretention systems, Tutus St.

and Beatty St. were more effective at removing nutrients. This is believed to be due to the attraction

of phosphorus to soil particles. Total nitrogen was reduced fairly well by the Tutus St. and Beatty St.

systems. The older, Jellicoe St. system performed poorly, leaching all forms of nutrients. This is

probably due to the build up and over-loading of nutrients in the media. There was net leaching of

nitrate in the outflow of all three systems, caused by the aerobic conditions in the systems, which

encouraged the nitrification of influent organic nitrogen and ammonia to nitrate.

In terms of metals, those of most concern in residential stormwater are Cu, Zn and Pb. Total Cu, Zn

and Pb concentrations were reduced by an average of 66%, 58% and 61% across the three systems.

Surprisingly, the older, Jellicoe St. system performed the best of the three systems for total metals

removal, despite poor performance for nutrients. This was probably due to these metals occurring

almost entirely in particulate form in the Jellicoe St. system influent, which allowed them to settle

out of the stormwater or be filtered by the bioretention media. The Jellicoe St. system appeared to

105

perform the worst at removing dissolved metals, probably due to the media having accumulated

large loads of particulate metals during its seven years since construction, which may redissolve back

into stormwater. The observed removal rates of dissolved metals also varied greatly, partly due to

very low inflow concentrations. This meant that slight increases or decreases in concentration

caused large percentage changes.

In terms of faecal indicator bacteria, removal performance was varied at the three bioretention

systems. Faecal coliforms were removed efficiently at the newer, Tutus St. and Beatty St. systems,

while Enterococci removal rates were much lower. The reason for this is unclear but could be due

the fact that Enterococci are more resilient than faecal coliforms or the attraction of the bacterial

types to soil or suspended solids particles. The older, Jellicoe St. system appeared to leach both

types of faecal indicator bacteria. This could have been due to unrepresentative sampling as a result

of limited faecal indicator bacteria monitoring and unintentionally only sampling rainfall events with

short antecedent periods at this bioretention system. However, it may be due to the accumulation

of organic matter in the bioretention media, which helps retain moisture. This allows bacteria to

survive and reproduce, then be flushed out during subsequent rainfall events.

8.2. Recommendations for Design and Management of Bioretention Systems

1. Promote horizontal sub-surface flow of stormwater through size-constrained bioretention

systems

Conventional bioretention systems are designed for only vertical flow of stormwater through the

bioretention media. In the studied size-constrained bioretention systems stormwater travels mostly

via horizontal sub-surface flow from one side of the bioretention system to the other. Highly

permeable local sandy soils, are used as the bioretention media in the system, allowing stormwater

flows to immediately penetrate into the media near the inflow point. The outflow point is an area of

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shattered rock in the downstream side of the systems wall, which allows stormwater flows to exit

the system from above and below the media surface. The design appears to perform well,

potentially by increasing the distance that the stormwater is in contact with the bioretention media.

The build-up of leaf litter and sandy sediment (a result of the catchment being located in a coastal

sandstone area) near the entrance of the system appears to have assisted in preserving the

hydraulic conductivity of the media and maintaining the ability of stormwater flows to penetrate

into the media as soon as entering the system.

2. Size-constrained bioretention systems should still be constructed in suitable locations, even when

they have a bioretention area to catchment area ratio as low as 0.2%

The smallest bioretention area to catchment ratio of the three size-constrained bioretention systems

was 0.2%. The study showed that size-constrained bioretention systems, used in catchments with

sandstone-based soil, can be effective in the removal of several types of stormwater pollutants. They

are most effective at the removal of suspended solids and particulate-bound pollutants. Therefore,

stormwater networks in urban creek and lagoon catchments, where suspended solids are a major

issue, should be given priority for the implementation of bioretention systems. Size-constrained

bioretention systems may be expected to perform poorly in the removal of total nitrogen if not

properly maintained, due to the accumulation then nitrification of large loads of organic nitrogen.

3. Carex appressa and Juncas usitatus should be the primary plant species used in bioretention

systems

Carex appressa and Juncas usitatus were the main species planted in the three bioretention systems.

Their reed-like structure appears to capture suspended solids from surface flows efficiently during

heavy flows. Also, they appear to be reasonably effective in the removal of nutrients compared to

conventionally sized bioretention systems that used different plant species. This has been shown in

other studies to be due to their extensive root structure and high growth rates.

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4. Size-constrained bioretention systems should be maintained at an increased rate compared to

conventional bioretention systems

All bioretention systems require maintenance to achieve optimal performance. This research

suggests that to achieve consistently high removal rates of suspended solids and total metals in size-

constrained bioretention systems, increased maintenance does not seem to be required. However,

the size-constrained bioretention systems appear to become over-loaded with nutrients after

several years of operation, which causes nutrient removal rates to be dramatically reduced.

Suggested maintenance includes pruning the plants and removal of sediment and organic matter

from the system’s entrance every year. Replacement of all bioretention media and plants should

occur approximately every ten years. Nutrient over-loading may also have a detrimental impact on

the removal of faecal indicator bacteria from stormwater. Therefore, regular maintenance, which

reduces nutrient levels in the media, may also assist in increasing the removal rates of pathogens.

8.3. Research Recommendations

1. Examination of size-constrained bioretention systems in different catchments

The effectiveness of size-constrained bioretention systems in clay-based catchments should be

researched further. Clay-based catchments produce stormwater runoff that contains high levels of

fine particles, which may be less effectively removed by size-constrained bioretention systems. Fine

clays may also result in clogging of the bioretention media, which reduces hydraulic conductivity and

allows less stormwater to filter through the media.

2. Examination of the efficiency and processes involved in the removal of pathogens by media-

based stormwater treatment systems

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The removal rates of different types of pathogenic bacteria, viruses and protozoans by bioretention

systems and other media-based stormwater treatment systems are largely unknown. Faecal

indicator bacteria are the only types of microbes to have been assessed for bioretention removal

efficiency in field studies. It is unknown how well faecal indicator bacteria removal rates correlate

with that of pathogens in stormwater. The processes that result in the capture and inactivation of

stormwater pathogens by media-based stormwater treatment systems are also not well understood.

3. Examination of the efficiency of aging bioretention systems

This was the first study to analyse the effectiveness of a bioretention system that was reported as

being older than two years. It is unclear whether the poor removal rates of nutrients, dissolved

metals and faecal indicator bacteria was caused by the age of the system, small bioretention area to

catchment ratio, design and function of the system, lack of maintenance and/or catchment

characteristics. More research is required to understand the effectiveness of older bioretention

systems to help determine their effective lifespan. Along with water quality sampling, cores could be

taken through the media within aging bioretention systems and analysed to show changes in

pollutant build up over time and with depth.

4. Examination of the most cost-effective bioretention system maintenance type and frequency

Research has shown that plants used in bioretention systems generally achieve higher total

cumulative biomass production after pruning. Higher plant growth rates result in the absorption and

assimilation of increased levels of nutrients from the bioretention media, which potentially helps

sustain higher nutrient removal rates from stormwater. The complete replacement of media and

replanting of new plants is an option when a bioretention system’s pollutant removal efficiency

reduces below a certain level. Research is required to determine the likely lifespan of bioretention

media and the effect that bioretention area to catchment area ratio, plant pruning and catchment

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pollution levels have on bioretention media lifespan, which will help plan for maintenance

requirements.

5. Examination of the pollutant loads leached from bioretention systems during their establishment

phase

Bioretention systems have been observed to leach high concentrations of fine particle suspended

solids during the first few rainfall events after they are constructed. No studies have monitored the

loads of suspended solids and nutrients leached during this establishment phase and the impact that

this phase has on the long-term average performance of bioretention systems.

6. Examination of the removal of dissolved metals by stormwater treatment systems

Very few field and laboratory bioretention studies have monitored dissolved metal removal rates

with most monitoring total metals. The overall average proportion of metals in dissolved form in the

influent stormwater at the three catchments researched in this thesis ranged from 6-20% for Cu, 22-

56% for Zn and 8-56% for Pb. The level of dissolved metals in the influent stormwater is an

important factor in the total metal removal effectiveness and being in their free ionic form, they are

more toxic than when in particulate form. Also, dissolved metal concentrations should be monitored

because they have the potential to be released from bioretention systems after metals have

accumulated in the bioretention media. This is potentially occurring in the Jellicoe St. bioretention

system and also observed in bioretention columns studied by Muthanna et al. (2007). The extent of

dissolved metal leaching in aging bioretention systems should be researched further and compared

to other stormwater treatment systems, such as constructed wetlands and sand filters.

7. Examination of the effectiveness of using a mix of plant species in bioretention systems

Several laboratory studies have compared the effectiveness of different plant species in bioretention

studies. However, no studies have compared whether planting a mixture of plant species in a

110

bioretention system is more effective in improving stormwater quality than planting a single species.

This is despite many actual bioretention systems being constructed with a mixture of plant species

due to perceived aesthetic reasons and a ‘hedging of bets’ on the most effective plant species.

8. Examination of the reasons for differences observed in laboratory studies compared to field

studies

Laboratory bioretention studies generally achieve higher stormwater pollutant removal rates than

field studies. The reasons for this have rarely been discussed, some possible reasons include:

o Use of synthetic or semi-synthetic stormwater in laboratory studies that could behave

differently to actual stormwater,

o Constantly changing conditions in field studies, such as pollutant inflow concentration,

antecedent rainfall periods, and temperature could affect removal rates,

o Difficulty in identifying and rectify design and construction mistakes in field bioretention

systems, which could lead to problems such as preferential flow paths, and

o Poor plant or media selection in field bioretention systems designed without scientific

expertise.

More research should be carried out on the above factors to help understand the reasons for

differences in the observed removal rates between laboratory and field bioretention studies.

9. Examination of the impact of infiltration from bioretention systems on the local soil and

groundwater

Bioretention systems are often designed and built to encourage the infiltration of stormwater into

local soils to recharge groundwater reserves. Although bioretention systems generally remove a

large percentage of pollutants from stormwater, they do not remove all pollutants from stormwater.

The transformation and fate of the stormwater pollutants that undergo infiltration into soil and

groundwater, is not entirely known. Stormwater pollutants may be captured in local soils and

111

groundwater, potentially leading to high pollutant accumulation in the soil and groundwater after

extended periods. More research is required to understand these processes as clean groundwater

supply is crucial for many communities and natural ecosystems.

112

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Chapter 10. Appendix

10.1. Published Bioretention Studies - Field Studies - where multiples samples were collected from multiple storms. Note: Bold figures are the percentage concentration reduction. If cells are blank, the data are unknown or not published. Concentration reductions are shown rather than load reductions because load reductions may be dramatically

affected by the infiltration rate of the system. Some field studies are not included, either because concentration reductions were not clearly included in the results or only a single inflow and outflow sample was collected (Hunt et al.,

2010, Hsieh et al., 2005, Hunt et al., 2006, Jonasson et al., 2010).

Study (Dietz and

Clausen, 2005) (Hunt et al., 2008) (Passeport et al., 2009) (Davis, 2007)

(Trowsdale and Simcock, 2010)

(Yu and Stanford, 2007)

(Hatt et al., 2009b)

(Hunt et al., 2010)

(Line and Hunt, 2009)

Location of Bioretention System

CT, USA NC, USA NC, USA NC, USA MD, USA MD, USA

Auk, NZ VA, USA VIC, AUS

QLD, AUS

NC, USA

NC USA NC, USA

Comments 100% Roof

runoff Only sampled small &

medium storms Grassed and

Submerged Zone Grassed

Submerged zone Submerged Zone and

Carbon Source Median

concentrations used Commercial

Bioretention System 0.25m media

Bioretention to catchment area (%)

8.6 6.1 3.2 3.2 2.2 2.2 1.1

Catchment Impervious (%) ~100 40 40 85.6 100 100

Construction date (year) 2002 2003 2005 2005 2003 2006 2004 2005 2006 2003

Sampling date (year) 02-03 04-07 06-07 06-07 03-04 06 04-05 06-07 07-08 07-08

Storms Sampled (number) 23 7-26 5-19 3-12 3-12 12 16 31 13

Water Quality Parameter Removal Rate (%)

Suspended Solids

TSS

60

22 41 90 90 76 93

76

Nutrients

TN 32 32 54 54 -7 37 -17

TP -111 31 63 58 74 68 55 -398 86 37

NH3 85 73 70 84 64 96 23

NO3/NOX 35 5 33 8 79 86 -13 -17 -254

TKN 31 44 49 59 20 11

Ortho-P 78 74 -1271 81 57

Metals

Pb 31 79 86 90 80 98 66

Cu 54 51 57 38 16 67 98

Zn 77 28 63 96 50 84 99 87

Fe -330

Cd 91

Mn 38

Hydraulics Peak Flow 99 18 14 64

Microbes

E. coli 71 70 -119

Faecal Coliforms

69 95 85

Enterococci 89 -102

120

10.2. Results from some of the Published Bioretention Studies – Small-scale studies Note: Bold figures are the percentage concentration reduction. If cells are blank, the data are unknown or not published.

Study (Bratieres et al., 2008b) (Bratieres et al.,

2008a) (Davis et al.,

2001a) (Blecken et al., 2010)

(Hatt et al., 2007b)

(Rusciano and Obropta, 2007)

(Hsieh et al., 2005)

(Blecken et al., 2008)

Location of Bioretention Study VIC, AUS VIC, AUS VIC, AUS VIC, AUS MD, USA VIC, AUS VIC, AUS NJ, USA MD, USA VIC, AUS VIC, AUS

Comments Planted with C.

appressa Planted with C.

appressa Planted with C.

appressa

2oC room

7oC room

20oC room

non-vegetated Acidic media Saturated

zone

Equivalent bioretention area to catchment area ratio (%)

1 2 4 5 2 2

Age of System (months) 13 13 13 6 6

Columns Replicates 5 5 5 5 3

Simulated Events 5 5 5 13-15

Water Quality Parameter Removal Rate (%)

Suspended Solids TSS 98 99 98 98 98 98 88-98 91.5 91

Nutrients

TN 65 71 62 70 -5 -23 -172

TP 89 95 94 86 60-80% 92 91 91 63

NH3 >90 60-80% 18 51 74 13

NO3/NOX 66 96 79 “leaching” -208 -320 -944 -16

Ortho-P 79 90 90 75

Metals

Pb 98 >90 95-99 >98 99 91-99

Cu 82 >90 92-97 85-99 72-92

Zn 98 >90 96-99 88-99 93-98

Microbes

E. coli 82

C. perifringens >99

F-RNA phages 97

Faecal Coliforms 91.6

121

10.3. Raw Data

Tutus - 11/8/09

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)

Nutrients (μg/L) Dissolved Metals (μg/L) Totals Metals (μg/L) Faecal Coliforms (cfu/100ml)

Enterococci (cfu/100ml) PO4 NOX NO3 NO2 NH3 TN TP V Cr Mn Cu Zn Mo Pb V Cr Mn Cu Zn Mo Cd Pb

11:00 I 18

62.0 7.0 219.0 308.0 16.0 54.7 1140.0 1106.9 33.1 247.0 2050.0 350.0 - - - - - - - - - - - - - - - - -

74.4 6.9 238.0 338.0 18.0 79.6 1680.0 1605.1 74.9 773.0 2050.0 210.0 - - - - - - - - - - - - - - - - -

62.1 6.5 217.0 311.0 14.0 63.8 1750.0 1680.6 69.4 257.0 2030.0 297.0 - - - - - - - - - - - - - - - - -

11:15 O 0 - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

11:30 I 74

63.2 6.7 63.3 98.8 13.0 113.0 847.0 821.6 25.4 280.0 1530.0 220.0 - - - - - - - - - - - - - - - - -

82.0 6.7 87.2 124.6 12.0 85.4 846.0 820.6 25.4 248.0 1640.0 242.0 - - - - - - - - - - - - - - - - -

84.0 6.6 69.7 99.6 13.0 85.8 801.0 745.7 55.3 245.0 1580.0 271.0 - - - - - - - - - - - - - - - - -

11:45 O 72

13.6 6.7 141.0 201.0 9.0 99.0 1570.0 1545.8 24.2 134.0 1820.0 197.0 - - - - - - - - - - - - - - - - -

16.3 6.6 142.0 203.0 8.6 199.0 1480.0 1453.0 27.0 173.0 1810.0 190.0 - - - - - - - - - - - - - - - - -

18.9 6.6 147.0 210.0 9.6 114.0 1550.0 1524.0 26.0 169.0 1820.0 198.0 - - - - - - - - - - - - - - - - -

12:00 I 12

6.0 6.8 58.1 83.3 4.0 172.0 649.0 628.6 20.4 234.0 1250.0 162.0 - - - - - - - - - - - - - - - - -

5.6 6.8 57.6 82.2 4.0 112.0 635.0 611.4 23.6 179.0 1240.0 155.0 - - - - - - - - - - - - - - - - -

6.6 6.8 59.5 84.8 4.6 114.0 650.0 625.0 25.0 170.0 1270.0 164.0 - - - - - - - - - - - - - - - - -

12:15 O 30

8.1 6.7 92.9 132.8 6.2 101.0 1120.0 1099.1 20.9 141.0 1490.0 154.0 - - - - - - - - - - - - - - - - -

6.4 6.7 93.3 133.4 5.7 147.0 1100.0 1077.7 22.3 171.0 1490.0 154.0 - - - - - - - - - - - - - - - - -

6.6 6.7 93.2 133.3 4.8 98.8 1110.0 1087.9 22.1 131.0 1480.0 151.0 - - - - - - - - - - - - - - - - -

12:30 I 6

4.8 6.8 99.4 141.6 4.8 178.0 1110.0 1088.8 21.2 84.0 1460.0 199.0 - - - - - - - - - - - - - - - - -

5.0 6.8 98.4 141.9 5.2 150.0 1140.0 1116.7 23.3 51.5 1450.0 194.0 - - - - - - - - - - - - - - - - -

4.6 6.8 99.4 142.2 5.0 143.0 751.0 733.1 17.9 75.8 1450.0 194.0 - - - - - - - - - - - - - - - - -

12:45 O 5

3.6 6.7 111.5 159.3 5.1 85.3 1140.0 1120.5 19.5 87.5 1450.0 132.0 - - - - - - - - - - - - - - - - -

2.8 6.8 111.6 159.5 4.7 86.5 1140.0 1140.0 94.8 1450.0 139.0 - - - - - - - - - - - - - - - - -

2.8 6.8 111.9 159.7 4.9 85.2 1140.0 1121.3 18.7 87.6 1440.0 136.0 - - - - - - - - - - - - - - - - -

13:15 O 3

2.4 6.8 122.6 175.1 4.4 75.5 1100.0 1083.0 17.0 65.0 1400.0 115.0 - - - - - - - - - - - - - - - - -

3.0 6.8 122.2 174.4 4.6 170.0 1100.0 1084.3 15.7 177.0 1400.0 114.0 - - - - - - - - - - - - - - - - -

2.6 6.9 122.3 175.3 4.0 89.8 1100.0 1084.9 15.1 63.9 1400.0 110.0 - - - - - - - - - - - - - - - - -

13:30 I 2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

13:40 O 3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

122

Tutus - 24/11/09

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)

Nutrients (μg/L) Dissolved Metals (μg/L) Totals Metals (μg/L) Faecal Coliforms

(cfu/100ml)


7:45 I 34

81.8 - 412.0 - 18.0 44.7 583.0 538.1 44.9 - - - 12.1 1.6 0.0 34.4 1.4 0.7 2.6 14.3 6.5 42.2 52.6 299.1 0.8 0.1 18.7 - -

112.8 - 420.0 - 20.0 45.6 591.0 548.3 42.7 - - - 13.1 2.3 0.0 35.3 0.8 0.9 2.7 14.6 6.6 44.6 53.3 315.8 0.8 0.1 19.2 - -

81.8 - 406.0 - 20.0 38.9 632.0 587.7 44.3 - - - 13.5 2.3 0.0 39.2 0.2 0.9 2.7 14.4 6.1 31.6 56.8 283.6 0.8 0.1 17.8 - -

7:55 I 30

20.0 - 298.0 - 11.0 76.0 552.0 502.5 49.5 - - - 12.7 3.0 0.0 40.0 1.1 0.9 2.7 15.7 6.7 34.2 59.2 299.8 0.9 0.1 18.6 - -

20.8 - 298.0 - 11.0 89.2 488.0 447.3 40.7 - - - 12.3 2.5 0.0 51.4 4.1 0.8 2.7 13.3 5.5 24.9 52.4 276.8 0.7 0.1 19.2 - -

20.0 - 303.0 - 12.0 74.3 541.0 496.2 44.8 - - - 12.7 2.9 0.0 35.8 1.4 0.9 2.9 12.7 5.3 25.2 48.4 275.7 0.6 0.1 19.1 - -

8:05 I 24

13.7 - 268.0 - 8.7 107.0 400.0 365.0 35.0 - - - 13.8 2.7 0.0 41.9 0.6 0.9 2.7 13.4 5.4 21.7 47.7 248.8 0.6 0.1 16.3 - -

13.3 - 256.0 - 8.5 84.1 472.0 434.6 37.4 - - - 14.2 2.9 0.0 42.5 0.7 1.0 2.7 14.9 5.8 23.5 55.0 275.9 0.7 0.1 17.5 - -

13.7 - 275.0 - 8.3 109.0 472.0 447.1 24.9 - - - 13.7 2.9 0.0 40.1 1.0 0.9 2.6 - - - - - - - - - -

8:15 I 10

10.0 - 263.0 - 7.2 101.0 354.0 323.1 30.9 - - - 14.1 2.7 0.0 40.2 1.3 1.0 2.7 - - - - - - - - - -

16.9 - 261.0 - 7.5 97.4 473.0 431.3 41.7 - - - 14.0 3.0 0.0 40.2 1.0 1.0 2.8 - - - - - - - - - -

10.6 - 275.0 - 7.0 87.3 474.0 428.4 45.6 - - - 14.0 2.8 0.0 44.2 1.2 0.9 2.9 - - - - - - - - - -

123

Tutus - 28/1/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


16:30 I 8

29.3 7.6 186.0 - 14.0 159.0 521.0 485.3 35.7 158.0 2850.0 351.0 - - - - - - - - - - - - - - - - -

32.3 6.4 185.0 - 17.0 - - - - - 2705.0 281.5 - - - - - - - - - - - - - - - - -

23.4 6.3 171.0 - 13.0 - - - - - 2495.0 279.0 - - - - - - - - - - - - - - - - -

16:40 I 6

52.2 6.3 255.0 - 30.0 261.0 343.0 303.0 40.0 7.6 2655.0 250.5 - - - - - - - - - - - - - - - - -

46.0 6.7 266.0 - 31.0 - - - - - 2155.0 238.5 - - - - - - - - - - - - - - - - -

47.2 6.8 259.0 - 29.0 - - - - - 2640.0 254.0 - - - - - - - - - - - - - - - - -

16:50 I 5

22.6 6.7 260.0 - 12.5 367.0 622.0 556.5 65.5 7.1 2070.0 199.0 - - - - - - - - - - - - - - - - -

19.3 6.8 267.0 - 12.0 - - - - - 2210.0 200.5 - - - - - - - - - - - - - - - - -

19.3 6.8 266.0 - 12.0 - - - - - 2180.0 186.0 - - - - - - - - - - - - - - - - -

19:35 I 80

88.4 6.6 162.0 - 13.0 84.8 715.0 687.2 27.8 223.0 2240.0 212.0 0.0 0.0 11.6 20.4 274.0 1.0 4.3 10.6 9.0 233.2 122.7 565.1 2.5 0.0 154.9

>100,000 ~12,000 111.2 6.6 162.0 - 14.0 - - - - - 2300.0 217.0 0.0 0.1 0.0 24.3 350.3 1.2 3.4 15.6 11.2 267.0 147.5 979.0 2.6 0.0 130.3

96.0 6.7 159.0 - 13.0 - - - - - 2280.0 222.5 0.0 0.1 8.0 22.8 329.5 1.1 3.8 11.2 9.9 203.6 120.8 706.3 2.7 0.0 141.8

19:45 I 135

310.7 6.6 142.0 - 17.0 197.0 712.0 673.8 38.2 399.0 3035.0 366.5 0.0 0.2 0.0 21.4 188.6 1.2 3.9 0.8 3.2 69.7 81.2 345.8 8.0 0.0 19.2

>200,000 ~10,000 117.8 6.6 141.0 - 15.0 - - - - - 2860.0 351.0 0.0 0.3 0.0 23.3 190.7 1.3 3.8 3.0 4.6 67.2 90.1 331.7 2.1 0.0 90.2

180.0 6.8 130.1 - 17.0 - - - - - 2875.0 321.5 0.0 0.1 0.0 19.6 251.0 0.9 3.4 3.5 5.8 72.0 105.5 444.7 1.6 0.0 124.5

19:55 O 108

57.4 7.4 221.0 - 8.7 156.0 624.0 595.0 29.0 4.2 1865.0 285.0 0.0 0.1 0.0 22.3 78.2 1.1 4.3 0.0 2.2 19.3 48.6 109.0 1.4 0.0 40.3

>20,000 ~3,000 30.0 6.8 220.0 - 6.8 - - - - - 1610.0 261.5 0.0 0.3 0.0 22.1 61.6 1.3 4.4 0.0 2.3 19.7 46.8 108.3 1.5 0.0 39.8

40.0 6.6 205.0 - 7.4 - - - - - 1825.0 278.0 0.0 0.3 0.0 23.9 71.0 1.4 4.7 0.0 2.3 19.2 47.1 112.6 1.6 0.0 38.5

20:05 I 150

28.3 6.9 80.6 - 7.0 137.0 429.0 402.8 26.2 4.8 1955.0 231.0 0.0 0.1 3.2 14.4 103.6 1.2 5.0 0.0 1.4 20.0 31.3 110.7 1.4 0.0 40.3

>20,000 ~2,900 32.2 6.8 79.1 - 7.1 - - - - - 1765.0 223.0 0.0 0.0 0.0 10.2 99.1 1.0 5.3 0.0 1.7 20.3 32.1 114.8 1.3 0.0 45.7

32.4 6.7 82.0 - 6.0 - - - - - 2060.0 253.5 0.0 0.1 0.0 14.3 106.7 1.0 5.3 0.0 1.8 18.7 35.5 128.4 1.3 0.0 48.0

20:15 O 150

14.6 6.8 140.0 - 4.0 156.0 606.0 571.5 34.5 11.1 - 226.0 0.0 0.1 0.0 16.2 47.0 1.3 4.0 0.0 1.2 7.2 28.3 67.1 1.4 0.0 30.8

>20,000 ~3,000 16.8 6.8 140.0 - 4.1 - - - - - 1042.0 228.0 0.0 0.1 0.0 17.0 52.3 1.3 4.9 0.0 1.7 7.2 28.9 69.7 1.5 0.0 25.2

15.2 7.0 140.0 - 5.8 - - - - - 940.0 206.0 0.0 0.2 0.0 16.8 47.6 1.3 4.9 0.0 1.3 7.9 27.4 65.5 1.4 0.0 25.3

20:25 I 60

14.2 6.8 75.9 - 5.3 115.0 228.0 208.8 19.2 3.0 868.0 183.8 0.0 0.0 0.0 10.5 96.2 1.0 3.8 0.0 1.3 11.1 25.0 125.2 1.1 0.0 32.7

>20,000 ~2,800 10.8 7.0 79.4 - 3.0 - - - - - 1170.0 208.0 0.0 0.0 0.0 11.9 111.7 1.0 4.5 0.0 1.1 8.1 30.4 139.8 1.0 0.0 36.3

12.7 6.8 77.9 - 3.1 - - - - - 1174.0 210.0 0.0 0.0 0.0 7.8 70.7 1.0 3.7 0.0 1.2 14.2 21.9 107.7 1.1 0.0 30.0

20:40 O 72

6.3 6.9 118.5 - 3.3 154.0 375.0 344.7 30.3 2.9 902.0 188.2 0.0 0.0 0.0 10.4 41.2 1.2 4.0 0.0 1.3 2.8 24.6 59.2 1.3 0.0 18.4

>20,000 ~4,000 7.7 6.8 125.5 - 2.9 - - - - - 928.0 204.0 0.0 0.0 0.0 10.8 36.8 1.3 3.7 0.0 1.2 3.6 21.6 60.0 1.4 0.0 18.7

6.4 6.9 123.6 - 3.1 - - - - - 922.0 191.2 0.0 0.0 0.0 10.8 41.6 1.3 3.8 0.0 1.0 3.6 18.8 56.9 1.4 0.0 18.3

20:55 I 10

5.1 6.9 88.9 - 3.0 135.0 257.0 227.7 29.3 1.3 1032.0 158.8 0.0 0.0 0.0 12.9 36.6 1.5 4.0 0.0 0.9 0.4 18.5 53.0 1.5 0.0 14.4

>20,000 ~2,500 4.6 6.8 85.8 - 2.9 - - - - - 1038.0 153.8 0.0 0.0 0.0 12.0 37.5 1.5 3.9 0.0 0.8 0.0 19.1 54.5 1.5 0.0 14.4

4.1 6.8 86.3 - 2.8 - - - - - 1042.0 159.6 0.0 0.0 0.0 18.4 42.1 1.5 3.9 0.0 0.8 0.5 28.3 67.7 1.5 0.0 15.0

21:10 O 15

3.2 7.0 145.0 - 3.1 106.0 277.0 252.9 24.1 3.2 1016.0 133.4 - - - - - - - - - - - - - - -

>20,000 ~3,000 3.0 7.2 149.0 - 3.1 - - - - - 964.0 133.4 - - - - - - - - - - - - - - -

2.9 7.1 154.0 - 2.9 - - - - - 974.0 123.4 - - - - - - - - - - - - - - -

21:25 O 6

2.8 6.8 161.0 - 2.9 167.0 235.0 214.8 20.2 3.1 - - - - - - - - - - - - - - - - -

>20,000 ~3,000 2.7 7.1 163.0 - 2.9 - - - - - - - - - - - - - - - - - - - - - -

4.3 7.0 164.0 - 3.0 - - - - - - - - - - - - - - - - - - - - - -

124

Tutus - 29/3/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


22:40 I 180

358.4 6.4 284.0 404.0 12.0 4700.0 14.8 7.2 7.6 208.0 6560.0 6920.0 0.0 0.6 32.0 19.7 104.6 0.4 3.4 10.0 10.1 178.6 137.7 870.6 13.5 0.4 59.4

140000 7700 724.5 6.4 290.0 414.0 14.0 4680.0 17.0 10.0 7.0 345.0 7240.0 7000.0 0.0 0.5 24.8 15.7 88.0 0.3 4.6 7.7 12.5 167.0 139.6 796.9 7.5 0.3 56.4

180.0 6.3 284.0 408.0 12.0 3220.0 19.9 12.7 7.2 70.3 6000.0 4880.0 0.0 0.5 23.0 12.2 106.8 0.2 3.7 11.0 12.0 191.8 132.5 946.2 4.2 0.4 72.3

22:55 I 45

20.9 6.6 178.0 256.0 5.6 1980.0 418.0 214.0 204.0 762.0 6040.0 2496.0 0.0 0.8 24.9 17.9 95.3 0.5 3.7 0.0 3.6 61.9 100.0 500.3 2.7 0.1 23.0

6400 730 23.3 6.5 178.0 255.0 5.0 2120.0 533.0 293.0 240.0 827.0 4520.0 2428.0 0.0 0.5 7.6 13.1 62.0 0.1 3.3 0.0 3.6 61.0 100.0 510.1 1.9 0.1 21.9

22.8 6.6 179.0 256.0 4.7 2060.0 301.0 108.0 193.0 800.0 5840.0 3936.0 0.0 0.7 1.2 16.7 80.5 0.4 3.3 0.0 3.6 62.3 101.5 504.6 1.7 0.1 22.7

23:10 I 15

9.3 6.5 199.0 285.0 3.7 1490.0 422.0 341.6 80.4 629.0 7200.0 4760.0 0.0 1.0 8.5 25.4 70.0 0.9 4.0 0.0 3.1 60.1 110.7 473.4 1.7 0.1 19.4

3600 1000 11.6 6.7 200.0 287.0 3.8 2100.0 648.0 437.0 211.0 843.0 5640.0 2668.0 0.0 0.6 0.0 19.7 57.4 0.4 3.4 0.0 3.5 59.3 107.4 463.3 1.5 0.1 18.6

17.3 6.7 203.0 291.0 3.7 1980.0 632.0 435.0 197.0 786.0 5840.0 3116.0 0.0 0.8 0.0 18.5 44.2 0.5 3.4 0.0 5.7 60.2 113.8 468.4 1.4 0.1 19.1

23:20 I 45

22.9 6.7 186.0 265.0 3.7 973.0 327.0 277.4 49.6 400.0 6400.0 2892.0 0.0 0.6 10.7 10.7 51.0 0.5 4.4 0.1 3.0 55.9 84.5 400.8 1.6 0.1 15.6

15000 2700 19.7 6.3 189.0 271.0 4.4 1440.0 758.0 644.0 114.0 548.0 3548.0 1948.0 0.0 0.8 15.4 16.5 78.5 0.6 4.7 0.0 3.0 55.3 85.2 388.8 1.5 0.1 15.7

17.3 6.2 195.0 280.0 3.5 1600.0 903.0 742.0 161.0 609.0 4760.0 1988.0 - - - - - - - 0.0 3.7 53.9 81.0 386.2 1.6 0.1 15.9

23:30 O 18

18.0 6.5 258.0 370.0 5.0 1080.0 1490.0 1415.0 75.0 276.0 5920.0 1332.0 0.0 0.6 0.0 14.0 35.2 0.6 3.5 0.0 2.2 32.1 53.5 116.8 1.4 0.1 10.9

64000 150 16.3 6.3 259.0 370.0 4.5 1010.0 1410.0 1350.1 59.9 244.0 3712.0 1148.0 0.0 0.6 0.0 14.0 24.9 0.6 3.4 0.0 2.2 32.2 52.9 116.0 1.3 0.1 7.9

10.3 6.2 262.0 376.0 4.7 1010.0 1570.0 1515.0 55.0 325.0 3408.0 1016.0 0.0 0.6 3.2 14.4 39.0 0.6 3.9 - - - - - - - -

23:40 I 30

6.9 6.4 142.0 205.0 2.6 1310.0 784.0 729.3 54.7 364.0 3596.0 1804.0 0.0 0.5 0.0 10.1 39.5 0.2 3.2 0.0 2.3 35.2 56.8 374.8 1.0 0.1 10.6

1800 1000 8.0 6.4 147.0 210.0 2.5 1280.0 681.0 634.5 46.5 328.0 3592.0 1636.0 0.0 0.6 6.1 9.5 62.2 0.3 3.7 0.0 1.9 37.9 57.4 417.2 0.9 0.1 10.3

10.0 6.3 142.0 204.0 2.6 1310.0 826.0 756.3 69.7 317.0 3012.0 1488.0 0.0 0.5 8.6 8.5 60.4 0.3 3.5 0.0 2.3 38.1 58.7 382.0 1.0 0.1 11.8

23:50 O 15

8.0 6.4 228.0 325.0 3.6 1100.0 1400.0 1301.2 98.8 286.0 3968.0 1236.0 0.0 0.5 0.0 10.1 27.3 0.6 2.9 0.0 2.1 24.2 51.8 104.2 1.3 0.1 7.9

39000 1400 7.9 6.5 229.0 326.0 3.3 1100.0 1390.0 1295.7 94.3 268.0 3984.0 1332.0 0.0 0.5 0.0 9.6 24.2 0.6 3.1 0.0 3.4 31.5 53.2 112.0 1.3 0.1 10.1

8.0 6.5 233.0 334.0 3.2 1040.0 1230.0 1155.9 74.1 265.0 3796.0 1248.0 0.0 0.5 0.0 11.3 18.9 0.7 3.1 0.0 2.1 18.6 47.6 103.3 1.3 0.1 6.2

23:05 O 8

3.2 6.5 226.0 323.0 3.2 949.0 1100.0 1014.8 85.2 165.0 2772.0 784.0 0.0 0.5 0.0 11.7 24.5 0.7 3.0 0.0 1.8 8.0 15.2 162.4 0.3 0.1 9.0

21000 1400 8.6 6.6 222.0 318.0 3.3 940.0 1310.0 1203.0 107.0 163.0 2740.0 1064.0 0.0 0.5 0.0 12.3 19.5 0.7 3.1 0.0 1.8 8.2 13.8 167.0 0.2 0.1 7.9

6.4 6.6 223.0 319.0 3.2 943.0 1300.0 1195.0 105.0 162.0 3944.0 1312.0 0.0 0.5 0.0 12.7 19.7 0.8 3.2 0.0 1.8 8.4 17.2 164.3 0.3 0.1 9.7

125

Tutus - 30/3/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


9:15 I 300

19.9 7.0 46.2 66.2 3.6 233.0 183.0 172.4 10.6 28.0 736.0 283.0 0.0 0.1 0.0 7.8 110.1 1.6 4.6 0.0 2.0 23.5 44.6 94.3 1.3 0.1 7.5

3800 1400 15.9 7.0 38.2 54.6 3.3 249.0 170.0 160.9 9.1 4.0 785.0 323.0 0.0 0.1 0.0 7.9 146.2 1.6 4.3 0.0 2.1 21.3 44.0 94.0 1.2 0.1 7.0

17.9 7.0 36.0 51.4 3.0 265.0 192.0 182.2 9.8 4.4 562.0 246.0 0.0 0.1 0.0 6.8 133.7 1.6 3.9 0.0 2.1 21.4 45.5 100.0 1.3 0.1 7.0

9:30 O 270

5.9 7.2 62.1 88.5 3.6 333.0 248.0 236.0 12.0 10.1 1010.0 385.0 0.0 0.1 0.0 12.5 53.0 1.8 3.9 0.0 1.2 4.1 18.9 65.1 0.3 0.1 4.7

3100 1100 6.2 7.2 63.3 91.3 3.4 340.0 264.0 252.5 11.5 9.6 725.0 346.0 0.0 0.1 0.0 12.9 59.7 1.8 4.1 0.0 1.3 4.5 16.3 62.1 0.3 0.1 5.3

7.5 7.3 61.1 88.3 3.2 325.0 263.0 251.6 11.4 7.0 987.0 396.0 0.0 0.1 0.0 13.5 64.2 1.8 3.6 0.0 1.3 5.7 16.5 64.7 0.3 0.1 5.2

9:45 I 300

14.9 7.3 36.1 51.5 3.0 213.0 142.0 133.7 8.3 4.3 530.0 268.0 0.0 0.0 0.0 9.6 102.5 1.6 4.1 - - - - - - - -

2400 1000 13.7 7.2 36.1 51.7 2.8 214.0 146.0 137.1 8.9 5.7 475.0 254.0 0.0 0.1 0.0 9.9 119.6 1.6 4.3 - - - - - - - -

13.0 7.3 36.6 52.4 3.0 217.0 146.0 137.3 8.7 3.5 449.0 250.0 0.0 0.1 0.0 10.1 126.9 1.6 4.3 - - - - - - - -

10:00 O 270

6.9 7.4 58.1 83.0 3.2 249.0 129.0 122.4 6.6 8.1 533.0 326.0 0.0 0.1 0.0 12.2 70.7 1.7 4.3 - - - - - - - -

2200 1300 4.9 7.4 58.0 82.6 3.1 313.0 194.0 183.2 10.8 6.9 534.0 333.0 0.0 0.0 0.0 11.2 63.5 1.7 3.9 - - - - - - - -

5.4 7.4 57.7 82.5 3.0 317.0 202.0 191.1 10.9 2.6 531.0 338.0 0.0 0.1 0.0 9.6 54.2 1.8 3.6 - - - - - - - -

10:20 I 90

6.3 7.4 42.9 61.5 3.2 268.0 215.0 203.7 11.3 11.6 604.0 291.0 0.0 0.1 0.0 10.9 124.8 1.7 5.0 - - - - - - - -

1700 650 10.7 7.4 43.0 61.5 3.3 264.0 215.0 204.2 10.8 10.3 532.0 323.0 0.0 0.1 0.0 10.5 156.6 1.6 4.8 - - - - - - - -

4.1 7.4 43.1 61.7 3.1 265.0 209.0 198.8 10.2 7.9 527.0 312.0 0.0 0.1 0.0 9.8 163.8 1.7 4.6 - - - - - - - -

10:40 O 96

4.4 7.4 67.5 96.6 3.5 321.0 157.0 146.9 10.1 11.8 552.0 374.0 0.0 0.1 0.0 11.0 68.6 1.9 3.9 - - - - - - - -

2100 940 4.3 7.5 67.2 96.0 3.5 353.0 174.0 164.6 9.4 8.5 536.0 363.0 0.0 0.1 0.0 10.3 56.5 1.9 3.8 - - - - - - - -

4.6 7.5 66.9 95.8 3.5 352.0 174.0 164.0 10.0 4.9 531.0 377.0 0.0 0.1 0.0 10.2 58.9 1.8 3.7 - - - - - - - -

126

Tutus - 23/6/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


9:35 I 660

54.0 6.3 83.2 118.5 2.4 25.9 34.0 31.6 2.4 8.5 - - 0.0 0.0 0.0 0.0 79.7 0.7 3.7 0.0 0.9 7.0 15.6 73.4 3.8 0.0 9.9 - -

7.8 6.1 43.6 62.2 2.0 35.6 53.6 49.6 4.0 15.2 258.0 147.0 0.0 0.0 0.0 0.0 74.8 0.7 4.0 0.0 0.8 7.0 10.7 89.9 3.5 0.0 9.7 - -

19.9 6.0 49.5 70.8 2.8 30.7 72.6 70.0 2.6 2.0 297.0 124.0 0.0 0.0 0.0 0.0 48.9 0.8 3.6 0.0 1.0 6.9 12.2 78.6 3.6 0.0 9.6 - -

9:50 O 690

21.1 6.2 49.7 70.6 4.2 42.9 74.5 71.3 3.2 0.9 274.0 129.0 0.0 0.0 0.0 0.0 29.4 0.8 3.6 0.0 1.0 10.4 12.6 57.9 3.5 0.0 10.3 - -

24.9 6.2 50.6 72.4 4.5 43.9 76.1 72.3 3.8 4.7 349.0 138.0 0.0 0.0 0.0 0.0 25.7 0.8 3.7 0.0 1.0 9.6 12.5 55.7 3.5 0.0 10.2 - -

21.1 6.3 48.0 68.6 4.4 41.7 70.8 67.4 3.4 1.2 206.0 114.0 0.0 0.0 0.0 0.0 27.3 0.8 3.7 0.0 10.3 10.6 13.3 56.2 3.6 0.0 10.7 - -

10:00 I 600

9.2 6.2 20.4 29.2 2.0 19.2 33.0 30.7 2.4 5.6 96.6 90.1 0.0 0.0 0.0 0.0 21.7 0.7 3.3 0.0 0.6 3.3 10.8 52.3 3.5 0.0 7.0 - -

9.8 6.0 20.0 28.6 2.0 14.8 24.7 22.3 2.4 5.2 143.0 82.7 0.0 0.0 0.0 0.0 16.7 0.7 3.4 0.0 0.6 2.7 8.0 74.4 3.3 0.0 7.5 - -

13.3 6.1 21.2 30.4 2.4 12.1 17.0 15.5 1.5 5.0 178.0 101.0 0.0 0.0 0.0 0.0 23.3 0.7 3.6 0.0 0.6 2.8 8.0 69.3 3.3 0.0 6.8 - -

10:15 O 600

5.9 6.1 30.2 43.2 3.1 33.4 44.4 42.1 2.4 1.4 203.0 119.0 0.0 0.0 0.0 0.0 29.2 0.7 3.5 0.0 1.1 0.6 6.4 32.3 3.4 0.0 5.7 - -

6.6 6.4 30.1 43.2 3.3 33.1 42.7 40.5 2.2 0.9 209.0 104.0 0.0 0.0 0.0 0.0 21.3 0.7 3.6 0.0 0.5 0.1 6.4 32.3 3.3 0.0 5.7 - -

5.9 6.1 28.7 41.1 2.8 28.9 28.3 26.5 1.8 2.8 190.0 114.0 0.0 0.0 0.0 0.0 25.3 0.7 3.4 0.0 0.5 0.4 6.5 31.8 3.3 0.0 5.9 - -

10:25 I 60

5.4 6.4 55.5 79.3 5.4 57.3 110.0 105.6 4.4 4.5 338.0 143.0 0.0 0.0 0.0 6.2 46.0 0.7 4.4 0.0 0.6 0.5 23.1 84.0 3.3 0.0 10.4 - -

5.3 6.5 56.1 80.2 5.5 58.3 112.0 108.4 3.6 10.0 241.0 127.0 0.0 0.0 0.0 6.9 50.7 0.7 4.6 0.0 0.7 0.8 23.3 85.5 3.3 0.0 10.7 - -

5.4 6.4 56.2 80.3 5.6 56.8 110.0 106.0 4.0 11.2 323.0 133.0 0.0 0.0 0.0 7.5 50.8 0.7 4.8 0.0 2.2 0.7 23.6 85.9 3.4 0.0 10.5 - -

10:40 O 48

3.3 6.5 53.0 75.8 3.5 45.6 56.5 54.1 2.4 2.4 267.0 128.0 0.0 0.0 0.0 1.4 39.2 0.8 3.8 0.0 0.9 0.0 9.1 41.8 3.4 0.0 4.9 - -

3.4 6.8 54.4 78.0 3.5 46.4 58.4 55.7 2.7 9.4 249.0 124.0 0.0 0.0 0.0 1.6 27.6 0.8 3.8 0.0 0.5 0.0 8.7 40.8 3.4 0.0 4.7 - -

3.3 6.6 53.9 77.1 3.4 44.7 58.6 55.8 2.9 12.1 248.0 125.0 0.0 0.0 0.0 1.5 30.2 0.8 3.8 0.0 0.5 0.0 8.6 40.9 3.4 0.0 4.8 - -

Beatty - 13/2/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


19:00 I 10

24.7 - 305.0 - 3.0 101.0 551.0 539.0 12.0 33.4 990.0 174.0 7.5 1.5 7.3 3.0 3.3 33.6 3.0 8.2 0.9 15.2 9.4 25.8 4.0 0.0 3.4 - -

26.8 - 321.0 - 4.0 108.0 660.0 645.2 14.8 79.2 1090.0 128.0 5.7 0.7 10.7 5.7 7.8 5.2 3.0 8.8 0.9 15.1 10.6 45.0 4.1 0.0 2.9 - -

27.4 - 310.0 - 3.8 89.8 609.0 595.6 13.4 31.6 1020.0 129.0 4.6 0.6 9.4 4.0 10.7 2.2 2.9 8.3 1.1 14.3 11.4 56.3 4.0 0.0 2.9 - -

19:15 O 10

4.8 - 444.0 - 1.7 43.9 325.0 318.6 6.4 81.3 824.0 41.1 7.3 0.7 5.5 5.7 9.5 1.8 2.8 8.1 1.4 27.4 13.9 43.4 3.8 0.0 4.5 - -

4.9 - 439.0 - 1.6 41.6 293.0 287.8 5.2 66.3 744.0 44.2 7.9 0.8 10.0 6.7 14.8 1.5 2.9 7.7 1.5 26.2 13.4 32.9 3.8 0.0 4.5 - -

4.5 - 418.0 - 1.8 27.5 283.0 277.9 5.1 26.8 931.0 28.7 7.1 0.7 4.3 5.4 13.9 1.3 2.9 7.1 1.3 26.0 14.3 32.0 3.7 0.0 4.6 - -

20:00 I 10 - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

20:15 O 10 - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

127

Beatty - 28/2/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


16:45 I 18

131.0 - 235.0 - - 496.0 607.0 541.7 65.3 585.0 - 932.0 32.0 0.7 141.0 15.3 45.2 0.6 5.2 134.3 6.1 320.3 62.3 221.7 23.7 0.0 13.5

66000 1400 155.3 - 215.0 - - 531.0 618.0 543.3 74.7 879.0 - 920.0 33.1 0.7 144.6 16.4 48.8 0.7 4.0 131.2 5.6 271.2 60.6 210.0 9.6 0.0 12.4

148.0 - 215.0 - - 504.0 614.0 541.8 72.2 678.0 3960.0 818.0 36.1 0.8 146.1 16.7 48.3 0.8 3.4 59.3 4.1 251.6 42.8 153.3 6.8 0.0 10.9

17:00 I 36

83.8 - 168.0 - - 644.0 361.0 325.0 36.0 345.0 2540.0 894.0 12.2 0.8 151.5 15.9 46.9 0.3 3.5 73.6 5.2 268.5 41.2 145.3 5.6 0.0 10.7

24000 1200 85.5 - 158.0 - - 629.0 381.0 342.5 38.5 290.0 2820.0 882.0 12.2 0.8 148.6 14.6 40.9 0.3 3.1 31.6 3.2 162.2 22.6 92.7 4.7 0.0 7.9

100.0 - 182.0 - - 687.0 323.0 290.2 32.8 322.0 2580.0 896.0 14.4 0.8 136.0 13.9 37.7 0.3 3.0 38.3 2.4 193.9 24.1 106.2 4.4 0.0 8.4

17:15 I 60

66.0 - 172.0 - - 1360.0 555.0 508.7 46.3 1050.0 4820.0 1536.0 8.5 0.5 114.5 6.9 31.0 0.1 3.0 19.8 1.2 4.2 19.9 152.6 4.5 0.0 3.7

38000 1400 59.6 - 169.0 - - 1230.0 587.0 542.7 44.3 1100.0 3520.0 1268.0 7.5 0.5 108.9 6.1 28.0 0.1 2.9 20.4 0.8 8.8 15.1 25.5 4.3 0.0 4.4

69.2 - 174.0 - - 1390.0 597.0 547.9 49.1 1090.0 4840.0 1502.0 7.7 0.5 115.5 7.4 35.0 0.1 2.9 21.1 0.8 7.7 17.0 25.6 4.4 0.0 5.5

17:30 O 40

7.6 - 221.0 - - 312.0 1050.0 986.9 63.1 1280.0 2220.0 342.0 9.8 0.5 9.1 10.3 16.8 0.7 2.7 1.0 0.6 41.6 11.4 33.3 3.8 0.0 2.9

14000 3400 7.3 - 222.0 - - 258.0 1040.0 982.3 57.7 513.0 2380.0 320.0 9.7 0.5 3.2 9.3 16.8 0.6 2.7 0.4 0.1 33.5 5.1 29.1 3.6 0.0 0.9

7.8 - 225.0 - - 250.0 1000.0 937.9 62.1 167.0 2140.0 312.0 9.0 0.4 0.0 6.4 12.4 0.5 2.6 - - - - - - - -

17:40 I 7.5

10.0 - 151.0 - - 313.0 547.0 526.8 20.2 66.8 1232.0 364.0 -0.3 0.6 42.0 6.3 37.4 0.4 16.4 - - - - - - - -

2000 1500 9.0 - 154.0 - - 290.0 533.0 511.2 21.8 514.0 988.0 348.0 -0.8 0.5 39.3 4.1 24.8 0.3 3.9 - - - - - - - -

8.8 - 151.0 - - 302.0 542.0 520.0 22.0 65.1 1022.0 378.0 -0.8 0.6 3.0 5.5 23.4 0.3 3.3 - - - - - - - -

128

Beatty - 6/4/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


19:05 I 20

35.8 6.9 108.6 155.7 4.5 361.0 55.8 47.9 7.9 95.8 1090.0 518.0 111.4 0.0 21.8 6.9 27.3 2.1 3.3 - - - - - - - - - -

27.4 7.0 139.3 199.0 3.8 300.0 60.4 52.1 8.3 82.1 1000.0 410.0 83.5 0.1 17.2 5.2 3.5 2.0 3.1 - - - - - - - - - -

35.0 6.7 100.3 143.4 4.1 385.0 100.0 90.7 9.3 90.4 1140.0 540.0 109.8 0.0 25.3 7.8 13.2 1.9 3.3 - - - - - - - - - -

19:25 O 9

8.5 7.2 165.0 235.0 3.6 113.0 193.0 181.7 11.3 39.3 883.0 185.0 8.9 0.1 0.0 4.4 0.0 1.9 2.8 - - - - - - - - - -

8.8 7.5 160.0 229.0 3.3 101.0 200.0 189.0 11.0 30.7 711.0 163.0 5.8 0.1 0.0 4.5 0.0 2.0 2.9 - - - - - - - - - -

6.5 7.3 159.0 228.0 3.5 105.0 202.0 189.6 12.4 33.3 728.0 159.0 5.7 0.1 0.0 4.2 0.0 1.8 3.0 - - - - - - - - - -

20:45 I 24

14.2 7.1 57.0 81.8 3.8 203.0 38.6 32.7 5.9 15.0 407.0 248.0 25.5 0.0 0.7 0.9 2.0 1.4 3.0 - - - - - - - - - -

17.4 7.0 67.4 96.3 3.4 172.0 21.7 16.2 5.5 16.2 375.0 180.0 7.9 0.0 0.9 1.8 1.6 1.4 3.5 - - - - - - - - - -

11.3 7.1 57.3 81.9 3.3 216.0 44.5 38.2 6.3 15.7 393.0 256.0 25.2 0.0 0.1 1.5 2.5 1.4 3.2 - - - - - - - - - -

21:00 O 12

6.7 6.8 87.5 125.2 3.3 104.0 83.8 77.2 6.6 18.8 407.0 113.0 22.4 0.0 0.0 3.2 2.0 1.7 2.9 - - - - - - - - - -

7.1 6.9 87.0 124.4 3.2 97.5 86.0 78.4 7.6 21.9 391.0 118.0 21.7 0.0 0.0 3.2 0.0 1.7 2.9 - - - - - - - - - -

7.4 6.9 87.5 124.9 3.4 105.0 85.6 78.4 7.2 22.0 456.0 126.0 22.3 0.0 0.0 4.1 6.0 1.7 3.2 - - - - - - - - - -

21:15 I 17

13.4 7.3 80.2 115.7 2.9 164.0 36.7 30.6 6.1 24.9 432.0 216.0 14.2 0.0 0.0 2.2 2.9 1.5 2.9 - - - - - - - - - -

7.5 7.3 78.8 112.6 3.0 176.0 38.6 31.1 7.5 25.7 372.0 222.0 26.8 0.0 0.0 2.3 0.1 1.5 3.0 - - - - - - - - - -

12.5 7.1 76.6 109.5 2.6 186.0 33.9 27.3 6.6 116.0 598.0 259.0 26.0 0.0 0.0 4.5 12.7 1.5 3.1 - - - - - - - - - -

21:30 O 14

2.2 7.0 99.8 142.5 2.8 71.3 43.8 38.1 5.7 46.1 429.0 103.0 17.1 0.0 0.0 4.2 5.4 1.8 2.9 - - - - - - - - - -

5.1 7.0 97.8 139.6 3.3 81.2 47.4 41.2 6.2 64.8 374.0 96.0 17.4 0.0 0.0 4.5 7.7 1.8 3.3 - - - - - - - - - -

2.5 7.1 98.4 140.6 3.2 70.7 45.5 40.2 5.3 42.4 372.0 89.9 17.0 0.0 0.0 3.9 3.8 1.8 2.9 - - - - - - - - - -

21:45 I 22

5.0 7.1 60.6 86.7 1.5 243.0 45.4 35.9 9.5 81.8 370.0 260.0 37.5 0.0 0.0 3.5 7.5 1.5 3.0 - - - - - - - - - -

6.3 7.0 59.9 85.5 1.6 236.0 44.0 35.4 8.6 76.0 392.0 257.0 36.2 0.0 0.0 1.5 2.5 1.4 3.1 - - - - - - - - - -

8.5 7.2 75.8 108.8 2.0 193.0 29.1 22.2 6.9 77.2 377.0 215.0 14.0 0.0 0.0 2.4 5.6 1.4 3.6 - - - - - - - - - -

22:00 O 15

3.0 7.0 88.7 126.9 2.9 91.4 46.1 40.5 5.6 35.8 360.0 115.0 19.5 0.0 0.0 3.5 4.2 1.7 3.1 - - - - - - - - - -

5.2 7.0 89.6 128.2 3.0 92.0 44.0 38.8 5.3 43.3 416.0 117.0 19.3 0.0 0.0 3.5 6.1 1.7 3.0 - - - - - - - - - -

3.4 7.0 87.5 124.0 2.8 94.6 45.6 38.5 7.1 37.8 348.0 131.0 19.6 0.0 0.0 3.6 5.7 1.7 3.2 - - - - - - - - - -

22:15 I 9

3.8 7.4 101.8 145.4 1.6 83.5 14.0 10.8 3.2 4.6 225.0 105.0 3.1 0.0 0.0 2.0 0.0 1.7 2.7 - - - - - - - - - -

1.1 7.7 107.9 154.4 1.7 84.9 12.2 8.5 3.7 4.9 227.0 107.0 2.6 0.0 0.0 2.0 0.0 1.6 2.7 - - - - - - - - - -

1.6 7.6 112.4 160.6 1.7 84.0 14.0 10.4 3.6 0.0 219.0 114.0 2.2 0.0 0.0 2.2 0.0 1.7 2.7 - - - - - - - - - -

22:30 O 7

2.1 7.1 112.4 160.6 3.2 48.7 35.8 29.4 6.4 20.5 309.0 73.8 13.2 0.0 0.0 2.8 0.7 1.9 2.6 - - - - - - - - - -

0.0 7.2 113.0 161.5 3.1 47.5 33.8 27.9 5.9 28.6 331.0 70.3 13.5 0.0 0.0 3.3 1.6 1.9 2.7 - - - - - - - - - -

5.2 7.1 114.8 164.1 3.2 45.7 30.8 26.2 4.6 21.0 321.0 71.6 13.1 0.0 0.0 3.0 1.6 1.9 2.6 - - - - - - - - - -

129

Beatty - 16/5/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)



9:00 I 360

114.8 6.2 69.2 99.0 4.5 405.0 603.0 588.8 14.2 147.0 1588.0 432.0 0.6 0.0 21.3 3.3 31.9 1.4 4.6 1.0 5.6 99.7 13.9 59.7 18.9 0.0 18.0

240000 4900 239.6 6.3 68.2 97.5 5.4 339.0 596.0 583.5 12.5 136.0 1928.0 456.0 0.7 0.0 11.2 2.5 26.6 1.4 4.3 0.0 1.7 78.5 8.0 49.2 5.7 0.0 18.5

240.0 6.2 64.4 92.1 4.5 311.0 556.0 543.3 12.7 93.9 2520.0 556.0 0.7 0.0 12.2 2.3 22.8 1.4 4.3 0.0 1.7 76.5 8.4 48.3 3.1 0.0 16.3

9:10 O 240

34.2 6.4 69.6 99.3 5.4 230.0 696.0 682.1 13.9 22.5 1084.0 293.6 5.3 0.0 0.0 1.5 16.2 1.4 3.4 7.5 1.4 35.0 5.0 28.7 2.3 0.0 12.0

38000 4100 31.8 6.3 67.2 96..1 6.2 226.0 767.0 751.0 16.0 15.5 1656.0 335.2 5.4 0.0 0.0 6.6 16.1 1.4 3.3 7.0 1.5 28.5 4.8 28.8 1.9 0.0 10.3

29.8 6.4 67.6 96.7 6.3 231.0 764.0 748.8 15.2 13.1 1656.0 341.6 5.4 0.0 0.0 3.2 16.5 1.4 3.2 6.6 1.0 27.0 4.3 26.8 1.6 0.0 9.8

9:20 I 240

20.4 6.4 94.5 135.0 6.2 227.0 528.0 518.7 9.3 15.6 1492.0 344.8 1.6 0.1 8.6 1.9 26.0 1.4 3.2 0.5 0.8 44.9 3.8 31.6 1.4 0.0 10.5

20000 2500 25.4 6.5 91.3 130.4 6.1 237.0 592.0 582.0 10.0 23.8 1628.0 374.0 1.8 0.1 11.4 1.8 25.9 1.4 3.2 1.3 1.0 51.2 4.4 35.9 1.3 0.0 10.6

26.0 6.3 78.8 112.8 6.7 240.0 559.0 549.8 9.2 12.4 1540.0 420.0 2.1 0.1 9.5 2.2 27.0 1.4 3.3 0.9 1.0 47.9 5.7 41.2 1.2 0.0 10.5

9:30 O 120

10.5 6.5 107.5 153.8 5.0 169.0 1010.0 981.7 28.3 13.4 1612.0 231.2 7.3 0.1 2.4 2.7 18.6 1.6 3.0 5.6 0.6 6.6 3.6 19.8 1.3 0.0 6.9

8700 2600 15.4 6.6 106.0 151.5 4.6 176.0 981.0 954.5 26.5 11.5 1672.0 246.4 6.8 0.1 2.6 2.3 16.3 1.6 3.0 6.0 0.8 12.1 4.5 21.2 1.2 0.0 7.0

11.4 6.4 106.0 151.9 4.5 178.0 952.0 927.4 24.6 10.0 1612.0 248.8 6.7 0.1 2.3 2.8 17.1 1.6 3.2 5.2 0.5 5.8 3.1 17.8 1.2 0.0 6.2

9:40 I 8

12.7 6.7 206.0 295.0 3.5 155.0 999.0 980.8 18.2 8.3 1604.0 216.8 0.0 0.4 7.4 6.3 18.8 1.9 2.8 0.0 0.6 24.0 7.3 23.2 1.4 0.0 5.8

6500 2400 6.1 7.0 209.0 299.0 3.7 148.0 998.0 980.0 18.0 9.9 1172.0 186.0 0.0 0.3 6.4 6.3 19.0 1.9 2.9 0.0 0.6 22.3 7.6 31.2 1.4 0.0 5.8

7.9 7.1 205.0 294.0 3.7 151.0 1000.0 981.6 18.4 9.5 1588.0 197.2 0.0 0.3 6.9 6.3 19.8 1.9 2.9 0.0 0.6 18.8 7.2 21.5 1.3 0.0 5.5

9:50 O 8

19.3 6.6 153.0 219.0 4.5 51.8 1360.0 1322.5 37.5 20.8 2200.0 97.6 5.6 0.1 0.0 4.5 23.3 1.8 2.8 2.7 0.5 1.0 4.3 12.7 1.3 0.0 6.8

4200 2200 15.0 6.8 156.0 223.0 4.7 50.5 1360.0 1320.4 39.6 34.6 1852.0 91.6 5.5 0.2 0.0 4.6 15.9 1.8 2.9 2.6 0.5 0.7 4.1 14.2 1.3 0.0 6.8

10.4 6.6 155.0 222.0 4.2 49.6 1360.0 1321.8 38.2 29.6 1808.0 79.6 5.4 0.2 0.0 4.6 17.1 1.8 3.0 2.4 0.6 0.5 5.0 17.7 1.2 0.0 6.8

10:00 I 90

33.6 6.6 69.2 98.9 5.2 235.0 328.0 319.8 8.2 14.5 888.0 305.2 8.4 0.0 10.5 1.4 19.0 1.4 3.0 11.6 1.5 37.8 5.0 38.7 1.1 0.0 10.8

9200 2300 61.8 6.5 64.8 92.6 6.0 237.0 302.0 293.8 8.2 15.4 936.0 338.8 9.5 0.0 10.0 1.3 14.9 1.5 2.9 12.4 1.6 49.9 6.7 54.4 1.1 0.0 13.0

62.0 6.4 66.5 95.1 5.4 240.0 308.0 299.4 8.6 18.7 932.0 337.2 9.3 0.0 9.4 1.4 18.3 1.5 3.0 11.0 1.3 28.4 4.9 39.4 1.0 0.0 9.9

10:10 O 72

7.0 6.7 100.9 144.3 3.9 178.0 716.0 695.4 20.6 9.1 1404.0 226.8 9.7 0.0 1.5 2.7 15.4 1.6 2.9 9.3 1.3 10.2 4.6 21.4 1.1 0.0 16.0

6100 2100 7.1 6.7 102.0 145.8 3.7 179.0 733.0 712.0 21.0 19.8 1196.0 269.6 9.0 0.0 1.5 2.6 14.0 1.6 2.9 7.4 0.5 3.2 2.8 17.6 1.1 0.0 7.2

6.4 6.6 101.2 144.6 3.6 179.0 723.0 702.3 20.7 14.3 1204.0 212.4 9.1 0.0 0.6 2.7 13.7 1.6 3.0 8.4 0.6 3.7 3.8 22.1 1.1 0.0 7.5

10:20 I 60

20.0 6.7 114.0 162.9 3.0 224.0 482.0 469.4 12.6 35.6 1040.0 271.6 5.0 0.1 10.0 2.2 21.0 1.5 3.0 1.2 0.5 26.0 4.9 23.3 1.0 0.0 7.0

15000 2100 28.2 6.7 113.1 161.4 3.2 224.0 465.0 452.7 12.3 14.9 740.0 217.2 5.1 0.1 12.0 2.9 22.2 1.5 3.1 2.0 0.8 29.0 6.2 26.5 1.1 0.0 8.7

12.2 6.7 108.2 154.6 2.9 227.0 454.0 442.2 11.8 11.9 608.0 188.4 5.6 0.1 12.1 2.1 15.5 1.5 3.0 1.0 0.6 22.4 5.1 23.0 1.0 0.0 7.7

10:35 O 24

3.5 6.6 127.0 181.5 3.3 114.0 764.0 744.8 19.2 12.2 1244.0 140.8 8.7 0.1 0.0 3.2 15.8 1.7 2.8 5.0 0.4 0.0 3.3 12.4 1.1 0.0 6.2

3500 2800 6.8 6.6 129.8 185.3 3.4 103.0 778.0 759.3 18.7 23.1 1224.0 138.4 8.5 0.1 0.0 3.4 12.5 1.8 2.8 5.0 0.4 0.0 3.4 13.4 1.1 0.0 6.5

3.6 6.6 127.1 181.6 3.2 112.0 755.0 734.8 20.2 21.3 852.0 118.8 8.6 0.1 0.0 3.4 18.7 1.8 2.8 5.3 0.5 0.0 5.0 17.4 1.1 0.0 6.9

10:50 I 6

4.1 7.2 257.0 369.0 3.1 122.0 852.0 838.2 13.8 8.7 1360.0 146.4 0.0 0.4 5.6 6.9 15.3 2.0 2.6 0.0 0.7 10.1 8.0 20.2 1.4 0.0 5.7

2200 400 3.5 7.2 254.0 363.0 3.1 137.0 867.0 852.7 14.3 9.2 1436.0 152.8 0.0 0.4 4.4 7.1 15.6 2.0 2.6 0.0 0.8 13.7 9.6 24.0 1.4 0.0 6.3

3.2 7.3 254.0 363.0 3.0 120.0 841.0 827.8 13.2 8.2 1348.0 147.6 0.0 0.4 4.9 7.2 13.0 2.1 2.6 0.0 0.7 11.5 8.9 22.5 1.4 0.0 6.3

11:05 O 6.7

3.2 6.8 148.0 209.0 3.8 48.7 796.0 788.2 7.8 11.7 1332.0 87.6 6.6 0.2 0.0 4.3 15.6 1.9 2.8 2.9 0.6 0.0 5.4 22.2 1.2 0.0 7.1

1200 900 1.2 6.6 147.0 208.0 4.0 48.6 819.0 811.2 7.8 12.7 1264.0 72.4 6.3 0.2 0.0 4.2 17.1 1.8 2.8 2.8 0.5 0.0 4.5 14.9 1.2 0.0 5.6

3.2 6.7 148.0 212.0 3.9 46.9 801.0 793.4 7.6 16.4 1256.0 58.4 6.3 0.2 0.0 4.4 20.8 1.8 2.8 2.8 0.2 0.0 3.7 13.6 1.1 0.0 5.3

130

Beatty - 26/5/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


11:00 I 60

3.0 7.1 279.0 399.0 3.6 54.7 265.0 259.7 5.3 7.5 0.0 0.0 0.0 0.3 0.0 1.6 19.9 1.1 3.3 0.0 1.5 3.0 6.0 18.4 0.3 0.1 1.4 - -

4.1 6.7 266.0 381.0 3.2 56.9 323.0 316.0 7.0 10.2 635.0 50.1 0.0 0.3 0.0 1.6 12.3 1.1 3.1 0.0 1.8 9.0 6.2 22.0 0.3 0.1 1.8 - -

3.0 6.9 265.0 378.0 3.2 54.3 280.0 274.5 5.6 7.3 565.0 50.7 0.0 0.4 0.0 1.7 9.4 1.1 3.3 0.0 1.6 3.7 12.8 18.7 0.3 0.1 1.3 - -

11:15 O 60

1.8 6.8 227.0 326.0 2.5 44.0 215.0 210.0 5.0 5.4 518.0 34.6 1.3 0.2 0.0 0.7 8.5 1.0 3.0 3.8 1.3 0.0 2.5 12.0 0.3 0.1 0.9 - -

1.8 6.9 226.0 324.0 2.7 38.4 113.0 109.5 3.5 8.1 530.0 41.8 1.3 0.1 0.0 0.5 7.5 1.0 2.9 3.9 1.5 0.0 2.9 12.6 0.3 0.1 1.1 - -

1.9 6.8 227.0 325.0 2.6 43.3 248.0 242.5 5.5 8.2 515.0 35.0 1.4 0.2 0.0 -0.2 6.8 1.0 2.9 3.4 1.4 0.8 2.6 13.7 0.3 0.1 1.1 - -

11:30 I 50

3.8 6.9 242.0 346.0 3.1 67.9 296.0 287.6 8.4 7.1 571.0 65.8 1.5 0.2 0.0 1.0 8.7 1.0 3.0 0.0 1.9 0.3 4.9 17.2 0.4 0.1 1.0 - -

3.3 7.0 258.0 369.0 3.1 66.0 268.0 260.5 7.5 10.0 569.0 60.3 0.4 0.2 0.0 1.1 7.6 1.0 3.0 0.0 3.0 1.1 4.5 16.3 0.3 0.1 1.0 - -

4.7 7.1 239.0 342.0 2.9 69.4 303.0 294.4 8.6 8.5 582.0 66.7 1.5 0.2 0.0 1.0 7.5 1.0 3.0 0.0 1.9 2.1 5.1 17.6 0.3 0.1 1.2 - -

11:45 O 50

1.9 6.8 260.0 372.0 2.6 50.8 281.0 274.8 6.2 12.6 620.0 50.3 1.4 0.3 0.0 1.0 23.8 1.0 3.0 3.5 1.4 1.0 2.7 12.7 0.3 0.1 1.3 - -

1.4 6.6 249.0 355.0 2.3 48.6 272.0 263.3 8.7 6.7 663.0 48.9 1.3 0.3 0.0 1.2 14.6 1.1 3.1 3.2 1.4 0.0 2.6 12.0 0.3 0.1 0.9 - -

2.2 6.5 247.0 354.0 2.4 45.4 278.0 270.9 7.1 4.4 609.0 44.2 1.1 0.3 0.0 0.9 9.7 1.2 3.2 3.3 1.4 0.1 2.9 12.3 0.3 0.1 1.0 - -

12:00 I 44

2.8 6.9 289.0 414.0 2.5 64.1 339.0 331.5 7.5 7.6 716.0 60.4 1.2 0.3 0.0 2.1 9.8 1.1 3.2 0.0 1.6 0.7 5.9 17.6 0.4 0.1 0.9 - -

2.1 6.9 319.0 457.0 2.8 52.3 370.0 363.7 6.3 8.8 800.0 36.9 0.0 0.4 0.0 3.3 11.9 1.3 3.3 0.0 1.7 0.0 5.3 17.8 0.4 0.1 0.8 - -

2.5 7.1 266.0 379.0 2.3 69.6 319.0 312.3 6.7 8.8 634.0 67.9 3.8 0.3 0.0 1.9 9.9 1.1 3.1 0.0 1.5 2.3 5.1 17.1 0.4 0.1 1.2 - -

12:15 O 50

5.1 6.7 212.0 304.0 2.4 55.8 214.0 209.6 4.4 8.1 564.0 57.4 2.5 0.1 0.0 0.2 8.9 1.0 3.1 5.8 1.4 1.6 1.8 12.8 0.2 0.1 1.1 - -

5.0 6.7 259.0 372.0 2.7 49.0 291.0 286.2 4.8 6.7 625.0 47.2 2.3 0.3 0.0 1.7 9.7 1.2 3.1 5.7 1.3 1.6 1.6 11.7 0.2 0.1 1.1 - -

6.2 6.8 261.0 375.0 2.6 48.5 301.0 295.5 5.5 14.9 657.0 34.7 1.5 0.3 0.0 1.9 12.1 1.2 3.1 6.3 1.8 2.1 2.0 13.0 0.3 0.1 1.2 - -

12:30 I 60

4.3 6.8 177.0 253.0 2.0 59.1 203.0 199.2 3.8 9.5 412.0 60.2 0.0 0.0 0.0 0.0 9.7 0.9 3.0 0.0 1.2 0.5 2.2 14.6 0.1 0.1 1.0 - -

2.3 6.8 178.0 255.0 2.1 60.4 207.0 203.3 3.7 11.4 466.0 57.0 0.0 0.0 0.0 1.4 15.8 1.2 3.5 0.0 1.0 0.0 2.0 13.5 0.1 0.1 1.0 - -

2.8 6.6 183.0 261.0 2.3 50.3 121.0 118.2 2.9 12.0 507.0 63.9 0.0 0.1 0.0 0.2 11.7 1.0 3.1 0.0 0.2 0.0 0.0 0.0 0.0 0.1 0.0 - -

12:45 O 150

12.6 6.6 163.0 234.0 3.3 64.0 191.0 186.7 4.3 12.1 462.0 65.3 1.1 0.0 0.0 0.0 14.3 1.0 3.0 7.0 1.7 9.3 2.9 15.1 14.8 0.3 2.6 - -

13.8 6.6 163.0 234.0 4.0 65.4 197.0 192.6 4.4 14.0 456.0 66.7 1.5 0.0 0.0 0.0 10.8 1.0 2.9 5.9 1.7 9.6 2.3 14.8 3.4 0.1 2.0 - -

18.2 6.7 159.0 228.0 4.2 64.9 177.0 173.3 3.7 13.9 305.0 49.9 1.6 0.0 0.0 0.0 10.7 1.0 3.0 6.0 1.7 10.2 2.4 15.2 1.7 0.1 2.2 - -

1:00 I 220

6.9 6.5 118.7 169.5 1.9 69.1 160.0 155.6 4.4 12.3 298.0 59.0 0.0 0.0 0.0 0.0 11.4 0.8 3.3 0.0 1.0 3.1 0.3 12.3 0.8 0.1 2.1 - -

7.3 6.7 123.9 177.2 1.9 66.6 161.0 156.7 4.4 17.9 328.0 65.8 0.0 0.0 0.0 0.0 15.4 0.9 3.4 0.0 1.6 3.4 2.0 14.0 0.6 0.1 2.2 - -

9.1 6.6 117.8 168.1 2.0 63.5 161.0 155.2 5.8 25.0 328.0 64.2 0.0 0.0 0.0 0.0 11.0 0.8 2.8 0.0 1.1 4.2 1.1 13.0 0.2 0.1 1.5 - -

1:15 O 240

4.1 6.7 144.0 206.0 2.0 65.1 181.0 175.9 5.1 12.3 576.0 56.9 0.0 0.0 0.0 0.0 7.9 0.9 3.0 2.5 1.2 2.0 1.1 11.1 0.1 0.1 1.3 - -

2.9 6.8 144.0 206.0 1.9 63.0 136.0 131.9 4.1 11.4 396.0 66.0 0.0 0.0 0.0 0.0 8.4 0.8 3.0 2.6 1.0 1.9 1.0 9.7 0.1 0.1 1.3 - -

4.6 6.7 152.0 218.0 2.0 57.9 182.0 177.6 4.4 11.1 405.0 59.3 0.6 0.0 0.0 0.0 9.1 0.9 2.9 3.8 1.1 2.9 1.5 17.1 0.1 0.1 1.5 - -

1:30 I 400

16.2 6.5 120.4 170.9 2.0 64.7 144.0 140.8 3.2 18.4 325.0 59.9 0.0 0.0 0.0 0.0 6.5 0.8 3.0 0.4 1.4 6.6 1.5 13.8 0.0 0.1 2.4 - -

14.5 6.6 118.5 169.6 1.9 64.9 143.0 140.0 3.0 12.4 244.0 56.2 0.0 0.0 0.0 0.0 8.6 0.8 3.0 1.2 1.7 6.7 1.5 14.0 0.0 0.1 2.1 - -

18.1 6.7 127.8 182.4 2.2 57.9 147.0 143.6 3.4 9.8 355.0 49.4 0.0 0.0 0.0 0.0 6.1 0.8 3.2 0.0 1.3 5.0 1.3 12.1 0.0 0.1 2.3 - -

1:45 O 420

6.9 6.7 101.9 145.6 1.9 64.4 121.0 118.4 2.6 10.4 326.0 64.4 0.0 0.0 0.0 0.0 5.4 0.8 2.9 1.7 1.2 5.1 0.2 9.9 0.0 0.1 1.6 - -

7.7 6.6 97.9 139.5 2.3 63.8 118.0 115.5 2.5 8.5 343.0 57.7 0.0 0.0 0.0 0.0 5.9 0.7 3.0 1.5 1.2 3.8 0.9 9.9 0.0 0.1 1.7 - -

7.6 6.7 98.9 141.5 2.0 65.0 122.0 118.5 3.5 15.9 330.0 63.5 0.0 0.0 0.0 0.0 5.5 0.8 3.1 1.7 1.2 5.4 2.0 25.6 0.0 0.1 2.4 - -

131

Beatty - 1/12/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)



12:45 I 360 - - - - - - - - - - - - - - - - - - - - - - - - - - - 4900 8100

12:55 O 360 - - - - - - - - - - - - - - - - - - - - - - - - - - - 5700 9900

13:05 I 300 - - - - - - - - - - - - - - - - - - - - - - - - - - - 6800 6500

13:15 O 300 - - - - - - - - - - - - - - - - - - - - - - - - - - - 4100 5400

13:25 I 300 - - - - - - - - - - - - - - - - - - - - - - - - - - - 3900 7000

13:35 O 300 - - - - - - - - - - - - - - - - - - - - - - - - - - - 3100 5000

13:45 I 240 - - - - - - - - - - - - - - - - - - - - - - - - - - - 4600 4800

13:55 O 240 - - - - - - - - - - - - - - - - - - - - - - - - - - - 3800 4800

14:05 I 210 - - - - - - - - - - - - - - - - - - - - - - - - - - - 3600 4400

14:15 O 210 - - - - - - - - - - - - - - - - - - - - - - - - - - - 4000 3800

Jellicoe - 20/11/09

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)



16:00 I 10

15.2 - 187.0 - 4.3 572.0 992.0 939.5 52.5 - 4260.0 566.0 1.0 1.4 10.7 15.1 43.9 0.8 8.6 - - - - - - - - - -

7.8 - 179.0 - 4.0 - - - - - 4720.0 624.0 1.7 1.7 14.4 16.3 54.9 0.9 8.9 - - - - - - - - - -

11.1 - 181.0 - 4.0 - - - - - 4820.0 624.0 0.8 1.3 10.4 13.4 45.1 0.7 8.3 - - - - - - - - - -

16:15 O 10

10.1 - 312.0 - 10.5 127.0 1080.0 1004.2 75.8 - 3460.0 234.0 2.3 1.2 0.0 14.5 30.3 1.5 6.6 - - - - - - - - - -

10.8 - 308.0 - 10.3 - - - - - 3600.0 234.0 2.1 1.1 0.0 13.3 23.8 1.5 5.7 0.4 1.6 0.0 13.6 40.1 2.0 0.0 17.1 - -

10.4 - 305.0 - 9.7 - - - - - 3440.0 240.0 2.2 1.1 0.0 13.6 27.6 1.4 5.8 0.1 1.5 0.0 14.1 44.6 2.0 0.0 19.0 - -

16:30 I 10

60.4 - 122.0 - 9.8 114.0 711.0 649.8 61.2 - 2080.0 202.0 1.8 0.9 8.7 5.8 36.6 0.5 7.5 2.6 2.5 21.7 12.7 108.4 1.2 0.0 150.1 - -

74.8 - 126.0 - 13.0 - - - - - 2080.0 214.0 2.3 0.9 8.7 6.2 38.5 0.5 7.8 3.7 3.4 25.6 12.4 102.7 1.3 0.0 154.4 - -

93.0 - 130.2 - 14.0 - - - - - 2040.0 212.0 2.2 0.9 8.1 6.1 36.0 0.5 8.2 4.2 3.5 25.1 13.9 113.6 1.2 0.0 160.9 - -

16:45 O 10

10.9 - 303.0 - 11.0 155.0 1010.0 954.8 55.2 - 3180.0 268.0 2.6 0.8 0.0 9.6 25.1 0.9 7.1 3.0 2.2 1.6 13.3 43.3 1.7 0.0 24.6 - -

9.4 - 294.0 - 9.0 - - - - - 3100.0 264.0 5.0 1.1 0.0 14.5 24.9 1.4 6.9 2.8 1.8 1.4 16.0 41.1 1.8 0.0 24.2 - -

10.4 - 296.0 - 9.6 - - - - - 3080.0 260.0 3.7 0.9 0.0 12.4 18.7 1.1 6.0 4.5 2.0 2.3 17.1 49.5 2.1 0.0 25.1 - -

132

Jellicoe - 5/2/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


15:10 I 94

42.0 - 89.7 128.3 9.5 96.9 326.0 309.2 16.8 13.6 1170.0 199.0 - - - - - - - 6.1 2.1 17.4 12.2 90.7 3.6 0.0 32.5 - -

26.5 - 97.9 139.0 9.0 - - - - - 1220.0 191.0 - - - - - - - 5.4 2.4 15.7 14.1 86.5 3.7 0.0 33.3 - -

30.3 - 96.5 138.0 7.5 - - - - - 1150.0 159.0 - - - - - - - 6.2 2.0 15.8 12.1 79.0 3.6 0.0 32.4 - -

15:25 O 60

6.4 - 78.1 113.0 5.0 140.0 222.0 200.5 21.5 56.3 952.0 197.0 - - - - - - - 4.4 0.9 0.0 5.2 27.7 3.5 0.0 7.0 - -

6.4 - 75.7 107.9 5.0 - - - - - 1090.0 210.0 - - - - - - - 4.5 0.8 0.0 5.6 23.4 3.5 0.0 6.9 - -

7.8 - 79.8 114.0 5.8 - - - - - 950.0 201.0 - - - - - - - 1.6 1.0 0.0 2.9 19.4 3.2 0.0 6.9 - -

15:40 I 198

14.7 - 46.4 66.1 5.5 82.6 188.0 169.7 18.3 42.2 676.0 158.0 - - - - - - - 1.6 1.4 2.2 3.5 37.9 3.3 0.0 12.5 - -

17.7 - 46.2 65.9 7.5 - - - - - 676.0 147.0 - - - - - - - 1.5 1.0 0.4 2.4 32.3 3.3 0.0 11.2 - -

19.9 - 46.2 65.9 6.3 - - - - - 573.0 128.0 - - - - - - - -0.2 1.4 1.4 1.4 38.9 3.2 0.0 13.4 - -

15:55 O 84

6.8 - 63.1 90.2 5.9 123.0 230.0 202.1 27.9 3.1 879.0 175.0 - - - - - - - 4.7 1.2 0.0 3.2 16.1 3.5 0.0 6.5 - -

7.3 - 61.8 88.3 6.0 - - - - - 737.0 178.0 - - - - - - - 4.6 1.3 0.0 3.4 16.1 3.5 0.0 6.2 - -

5.3 - 62.8 89.7 5.5 - - - - - 1120.0 168.0 - - - - - - - 4.7 1.2 0.0 3.4 15.9 3.5 0.0 6.1 - -

16:10 I 57

6.8 - 52.2 74.8 5.3 141.0 325.0 262.9 62.1 59.1 1120.0 153.0 - - - - - - - 2.7 1.6 0.0 2.8 36.5 3.4 0.0 10.1 - -

7.4 - 52.5 75.2 5.2 - - - - - 982.0 164.0 - - - - - - - 2.7 1.7 0.0 2.8 65.2 3.4 0.0 9.3 - -

7.5 - 52.1 74.5 5.4 - - - - - 984.0 159.0 - - - - - - - 1.3 1.5 0.0 1.4 34.9 3.3 0.0 9.6 - -

16:25 O 10

4.5 - 82.6 117.9 8.1 77.9 364.0 308.6 55.4 23.9 571.0 137.0 - - - - - - - 4.2 1.7 0.0 6.5 23.0 3.6 0.0 6.6 - -

5.6 - 84.2 120.6 8.1 - - - - - 1090.0 167.0 - - - - - - - 3.9 1.9 0.0 6.1 144.2 3.7 0.0 6.2 - -

6.4 - 84.7 119.5 8.1 - - - - - 984.0 168.0 - - - - - - - 3.7 1.4 0.0 5.9 25.3 3.6 0.0 6.7 - -

133

Jellicoe - 5/5/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


12:00 I 25

39.7 6.4 100.5 143.7 8.6 96.5 1290.0 1260.4 29.6 483.0 3428.0 238.0 1.9 0.4 0.0 8.7 185.7 1.7 4.7 1.9 3.2 19.2 17.6 187.7 0.6 0.2 39.8

510 2200 26.3 6.7 90.7 130.9 8.5 64.8 767.0 749.6 17.4 351.0 2548.0 171.6 2.2 0.4 0.0 7.5 129.9 1.7 5.8 1.3 2.5 14.9 14.0 157.1 0.4 0.2 43.7

58.6 6.6 86.6 123.8 9.3 82.5 1310.0 1284.5 25.5 466.0 2764.0 191.2 2.0 0.4 0.0 7.4 144.4 1.7 5.2 6.2 5.1 42.1 29.0 265.3 0.8 0.2 66.1

12:20 I 9

14.2 6.7 105.5 150.8 6.1 305.0 1050.0 1017.8 32.2 445.0 4160.0 360.4 3.8 0.4 0.0 13.6 61.5 1.8 5.4 1.3 1.7 4.1 16.2 75.0 0.4 0.1 12.9

210 1600 12.2 6.7 103.1 148.0 7.0 318.0 1330.0 1289.8 40.2 491.0 4520.0 360.8 3.6 0.4 0.0 13.5 67.5 1.8 5.4 1.5 1.7 5.6 16.8 76.2 0.4 0.1 14.4

35.2 6.8 91.2 130.6 7.0 206.0 1060.0 1018.4 41.6 388.0 2560.0 292.0 3.7 0.5 0.0 10.6 58.1 1.7 5.1 3.9 2.7 22.7 21.0 108.3 0.5 0.1 24.6

12:40 I 126

92.4 7.0 55.6 73.3 7.4 75.3 541.0 522.7 18.3 144.0 1332.0 154.0 0.0 0.0 0.0 0.6 51.5 0.8 4.2 5.2 3.3 39.9 16.4 143.8 0.5 0.2 38.5

390 1400 125.6 6.9 57.1 81.6 8.5 74.7 508.0 490.9 17.1 139.0 1376.0 159.6 0.0 0.0 0.0 0.3 29.7 0.8 4.0 7.2 4.5 59.8 26.3 187.2 0.6 0.2 50.6

109.3 7.0 57.8 82.6 8.8 80.9 572.0 550.2 21.8 144.0 1456.0 168.0 0.0 0.0 0.0 0.0 37.8 0.8 3.9 10.4 5.7 87.7 31.4 243.7 0.8 0.3 72.6

12:45 O 36

25.1 6.9 93.1 133.1 8.2 146.0 1250.0 1223.6 26.4 135.0 2180.0 223.6 0.0 0.0 0.0 2.8 16.7 0.9 4.7 2.2 1.9 9.1 7.8 37.1 0.3 0.1 12.4

910 1800 16.2 7.0 90.2 129.0 6.7 143.0 1100.0 1077.3 22.7 123.0 2124.0 213.2 0.0 0.0 0.0 2.0 17.9 0.9 4.6 2.0 1.9 7.4 6.6 34.7 0.3 0.1 11.5

13.3 7.0 90.0 128.7 6.5 152.0 1220.0 1196.8 23.2 128.0 2100.0 199.6 0.0 0.0 0.0 2.3 14.3 0.9 4.7 1.7 1.7 4.0 6.0 28.9 0.3 0.1 9.6

12:55 I 8

3.3 7.1 59.0 84.2 2.4 315.0 542.0 516.4 25.6 354.0 1928.0 317.2 0.0 0.0 0.0 2.1 19.3 0.8 3.7 1.0 1.4 0.9 6.3 38.8 0.1 0.1 5.0

780 1500 0.0 7.2 59.2 84.5 3.2 299.0 560.0 532.2 27.8 328.0 1896.0 308.4 0.0 0.0 0.0 2.2 29.1 0.8 3.7 0.9 1.2 0.0 4.8 34.9 0.1 0.1 3.9

0.0 7.1 60.6 86.5 3.6 321.0 552.0 525.6 26.4 337.0 2016.0 311.2 0.0 0.0 0.0 2.2 28.4 0.8 3.7 - - - - - - - -

1:05 O 5

7.5 7.2 128.7 183.6 6.5 113.0 1420.0 1398.4 21.6 71.8 2296.0 150.4 0.1 0.5 0.0 6.7 11.7 0.2 3.1 0.0 1.4 0.0 9.0 15.9 0.3 0.1 2.2

1,300 1300 5.0 7.3 126.7 181.0 6.2 109.0 1490.0 1468.5 21.5 68.2 2312.0 144.0 0.8 0.6 0.0 4.3 11.8 0.3 3.3 0.0 1.3 0.0 4.4 17.8 0.3 0.1 2.0

7.4 7.3 127.4 181.7 6.4 100.0 1500.0 1478.3 21.7 62.8 2292.0 137.6 0.6 0.6 0.0 3.9 10.6 0.2 3.3 0.0 1.2 0.0 4.0 17.1 0.3 0.1 2.4

1:20 O 2

4.8 7.3 146.0 209.0 8.1 62.5 1090.0 1078.9 11.1 35.2 2280.0 112.0 0.2 0.7 0.0 4.8 10.1 0.3 3.7 0.0 1.4 0.0 5.6 17.1 0.4 0.1 2.0

830 1100 3.6 7.3 147.0 209.0 8.0 68.0 1600.0 1584.4 15.6 33.8 2364.0 110.0 0.0 0.6 0.0 5.3 11.5 0.4 3.2 0.0 1.5 0.0 5.5 24.4 0.4 0.1 2.3

3.9 7.4 147.0 210.0 8.3 71.4 1520.0 1506.5 13.5 36.3 2164.0 101.6 0.0 0.6 0.0 4.6 10.4 0.3 3.2 0.0 1.4 0.0 5.1 17.4 0.3 0.1 2.0

134

Jellicoe - 19/5/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


11:35 I 175

11.0 6.9 164.0 234.0 8.9 116.0 528.0 510.2 17.8 122.0 780.0 184.0 5.0 2.1 0.0 2.0 10.8 58.7 4.5 2.6 2.5 2.2 6.1 53.4 3.5 0.0 12.3 - -

12.9 6.6 187.0 268.0 9.8 127.0 560.0 539.9 20.1 128.0 780.0 172.0 1.6 1.1 0.0 1.8 14.7 14.8 3.7 2.3 2.4 1.8 5.8 53.4 3.4 0.0 12.1 - -

10.7 6.6 186.0 267.0 9.2 117.0 531.0 513.6 17.4 120.0 760.0 164.0 1.1 1.0 0.0 1.5 16.7 7.1 3.6 2.0 2.1 0.8 5.2 50.0 3.4 0.0 11.8 - -

11:50 O 108

7.7 6.5 273.0 391.0 9.3 87.3 568.0 553.1 14.9 63.1 735.0 137.0 2.1 0.9 0.0 2.8 13.9 5.4 3.4 2.4 1.6 0.0 4.7 38.4 3.5 0.0 7.3 - -

7.8 6.6 275.0 392.0 9.6 86.8 579.0 563.5 15.5 63.7 800.0 149.5 2.3 1.0 0.0 2.7 11.1 4.2 3.5 1.8 1.6 0.0 5.3 35.5 3.5 0.0 8.2 - -

9.1 6.7 309.0 442.0 10.1 87.2 640.0 622.9 17.1 62.2 1135.0 115.0 2.5 1.1 0.0 3.0 14.5 3.5 3.7 2.5 1.7 0.1 4.9 38.5 3.5 0.0 7.7 - -

12:05 I 75

10.3 7.0 617.0 881.0 10.4 132.0 1230.0 1208.1 21.9 79.4 1745.0 162.0 2.8 1.8 0.0 5.8 29.1 3.3 5.2 5.4 3.0 8.0 16.4 77.2 3.7 0.0 15.5 - -

10.8 6.9 611.0 876.0 10.4 133.0 1230.0 1210.9 19.1 77.8 1750.0 175.5 2.7 1.6 0.0 5.9 27.3 3.1 5.2 3.5 2.6 0.0 8.4 71.8 3.7 0.0 14.1 - -

10.7 7.0 614.0 878.0 10.3 134.0 1040.0 1023.4 16.6 86.4 1550.0 174.5 2.7 1.7 0.0 6.0 37.1 2.7 5.0 3.1 2.5 0.0 8.1 72.4 3.7 0.0 14.4 - -

12:20 O 72

8.2 6.9 505.0 723.0 10.2 114.0 1070.0 1054.2 15.8 63.2 1290.0 129.5 2.4 1.3 0.0 5.6 31.5 2.4 4.1 2.5 1.9 0.0 8.4 49.4 3.7 0.0 9.4 - -

8.6 6.9 508.0 725.0 10.3 97.3 1080.0 1064.9 15.1 41.4 1615.0 143.5 3.1 1.5 0.0 5.7 29.4 2.3 4.4 2.0 1.6 0.0 7.4 45.4 3.7 0.0 8.8 - -

9.0 6.9 506.0 724.0 10.3 96.2 1080.0 1065.5 14.5 44.5 1530.0 158.5 2.7 1.4 0.0 5.6 29.8 2.1 4.3 2.7 2.0 0.0 10.8 48.9 3.7 0.0 9.5 - -

135

Jellicoe - 28/7/10

Time In /

Outflow Flow

(L/min) TSS

(mg/L) pH

TDS (mg/L)

EC (μS/cm)

Turbidity (ntu)


(cfu/100ml)


12:10 I 1008

134.9 6.9 47.7 68.3 7.5 30.9 83.2 76.8 6.4 56.8 393.0 48.0 0.3 0.1 0.0 0.0 20.7 5.4 2.6 4.5 4.5 51.9 16.3 133.4 0.0 0.2 52.7

590 1200 66.5 6.8 60.0 85.8 6.0 33.1 100.0 94.6 5.4 62.7 217.0 23.5 0.9 0.5 0.0 0.0 19.0 2.9 3.4 8.8 7.1 88.3 27.9 186.5 0.2 0.2 79.5

53.4 6.6 56.0 80.0 6.3 31.8 17.7 17.7 0.0 60.6 228.0 23.8 0.6 0.1 0.0 0.0 18.1 2.1 2.6 8.5 6.1 78.2 20.2 146.9 0.2 0.2 64.7

12:25 O 120

46.5 6.6 57.1 81.8 9.0 60.8 226.0 218.4 7.6 68.7 226.0 23.8 0.9 0.2 0.0 0.0 12.1 1.8 2.8 1.0 1.5 6.2 1.4 23.6 0.0 0.1 8.7

2500 6700 16.9 6.6 64.4 92.1 7.3 61.9 231.0 224.1 6.9 64.8 456.0 47.4 1.1 0.2 0.0 0.0 15.0 1.7 2.8 1.0 1.5 6.8 0.6 26.8 0.0 0.1 8.6

21.6 6.5 60.3 86.4 8.0 63.2 226.0 219.3 6.7 61.1 452.0 59.0 1.1 0.2 0.0 0.0 12.1 1.6 2.8 1.1 1.6 5.8 0.8 28.4 0.0 0.1 8.3

12:40 I 72

3.0 6.8 163.0 234.0 3.8 59.2 253.0 246.3 6.7 61.0 408.0 54.9 0.5 0.3 0.0 0.6 20.1 1.6 3.3 0.0 1.3 1.4 0.0 35.9 0.0 0.1 8.5

900 1200 3.2 6.7 168.0 240.0 4.3 66.6 293.0 285.1 7.9 68.0 428.0 45.9 0.6 0.4 0.0 1.3 20.3 1.6 3.3 0.0 1.3 1.4 0.0 35.6 0.0 0.1 8.5

2.9 6.9 151.0 217.0 3.7 63.6 281.0 272.7 8.3 - 434.0 34.6 0.5 0.3 0.0 0.6 21.5 1.5 3.5 0.2 2.0 1.4 0.4 33.2 0.0 0.1 8.2

12:55 O 60

4.7 6.6 186.0 268.0 6.4 62.3 309.0 300.8 8.2 30.5 550.0 45.1 2.5 0.7 0.0 1.8 15.5 1.6 3.3 1.5 1.7 2.0 1.2 32.7 0.0 0.1 5.4

770 4200 5.2 6.8 170.0 243.0 5.7 60.8 286.0 277.5 8.5 33.0 551.0 51.1 2.4 0.7 0.0 1.7 15.1 1.6 3.3 2.1 1.8 2.2 1.0 28.1 0.0 0.1 5.0

5.0 6.9 177.0 254.0 6.0 61.2 312.0 303.1 8.9 13.0 674.0 53.7 2.4 0.7 0.0 1.7 14.8 1.6 3.3 1.6 1.6 1.9 0.8 23.4 0.0 0.1 4.7

1:10 I 32

3.8 7.3 250.0 358.0 6.0 69.9 439.0 427.6 11.4 - 700.0 38.9 1.6 0.8 0.0 2.2 21.0 1.6 4.1 0.9 1.9 1.7 0.9 54.4 0.0 0.1 10.6

680 770 3.9 7.2 250.0 358.0 6.2 75.0 425.0 414.3 10.7 57.3 766.0 62.4 1.5 0.8 0.0 2.7 18.9 1.6 4.0 1.1 5.3 2.7 4.2 119.6 0.0 0.1 10.6

4.3 7.8 290.0 415.0 7.5 76.9 502.0 489.4 12.6 46.8 658.0 42.5 1.8 1.1 0.0 2.9 19.5 1.6 4.2 0.6 3.4 1.8 2.2 59.9 0.0 0.1 10.6

1:25 O 60

4.6 7.3 226.0 325.0 7.3 57.5 354.0 346.1 7.9 - 649.0 42.3 2.7 1.1 0.0 2.9 17.5 1.6 3.6 1.9 2.3 2.9 3.7 30.9 0.0 0.1 5.8

410 1500 4.6 7.1 226.0 324.0 7.0 56.6 370.0 361.9 8.1 - 660.0 42.7 2.6 1.1 0.0 2.2 17.1 1.6 3.4 2.1 2.2 3.3 2.7 30.1 0.0 0.1 6.2

4.8 6.9 226.0 324.0 7.1 56.4 373.0 365.3 7.7 31.9 661.0 46.4 2.5 1.1 0.0 2.3 18.6 1.6 3.3 2.8 2.6 10.0 5.2 41.5 0.0 0.1 11.3

1:40 I 85

22.0 6.7 58.1 83.0 2.2 45.2 108.0 102.5 5.5 36.6 203.0 37.3 0.0 0.0 0.0 0.0 11.7 1.3 2.6 0.0 1.3 7.1 0.4 30.6 0.0 0.1 7.9

300 2700 13.3 6.4 54.1 77.6 3.3 50.7 105.0 101.1 3.9 68.8 200.0 37.8 0.0 0.0 0.0 0.0 12.0 1.3 2.6 0.0 1.2 6.8 0.0 30.4 0.0 0.1 7.9

19.7 6.5 55.5 79.3 2.8 46.1 97.9 94.2 3.7 55.0 202.0 35.4 0.0 0.0 0.0 0.0 13.6 1.3 2.6 0.0 1.4 8.1 1.3 33.3 0.0 0.1 9.2

1:55 O 120

6.7 6.9 99.1 141.7 3.8 67.0 225.0 218.0 7.0 48.0 505.0 72.6 1.2 0.2 0.0 0.0 16.3 1.4 2.9 0.5 1.3 2.0 0.3 18.6 0.0 0.1 3.3

2000 4800 8.5 6.9 105.9 151.4 4.5 51.7 156.0 151.2 4.8 48.0 539.0 72.6 1.1 0.4 0.0 0.0 20.1 1.4 2.8 0.7 1.5 2.5 0.7 18.7 0.0 0.1 3.2

6.9 6.9 101.5 145.1 4.8 65.2 227.0 219.3 7.7 43.3 557.0 69.7 0.9 0.3 0.0 0.0 41.2 1.4 2.8 0.8 1.3 2.8 0.6 19.6 0.0 0.1 3.9

2:10 I 83

2.3 6.8 242.0 346.0 5.1 80.2 450.0 435.2 14.8 61.7 770.0 81.4 0.9 0.7 0.0 1.2 34.5 1.5 4.2 0.0 1.6 0.8 5.9 33.4 0.0 0.1 5.4

290 660 2.4 7.0 239.0 342.0 5.2 78.1 458.0 445.1 12.9 63.5 718.0 86.0 0.8 0.7 0.0 1.3 51.5 1.5 4.6 0.2 1.9 0.6 0.9 58.3 0.0 0.1 5.5

2.7 7.1 226.0 324.0 4.8 78.5 420.0 409.4 10.6 66.5 798.0 89.6 0.6 0.7 0.0 10.1 33.9 1.5 4.3 0.1 1.9 1.1 1.4 34.4 0.0 0.1 5.8

2:25 O 480

3.7 7.1 225.0 322.0 5.3 64.0 364.0 354.1 9.9 54.0 712.0 67.0 1.9 0.8 0.0 0.9 28.6 1.5 3.5 1.5 1.9 1.3 1.3 27.5 0.0 0.1 3.5

490 960 3.3 7.0 230.0 328.0 4.9 61.9 375.0 361.1 13.9 40.5 701.0 67.3 2.1 0.7 0.0 1.0 24.6 1.5 3.4 1.6 1.8 1.2 0.6 35.1 0.0 0.1 3.2

3.7 6.9 221.0 317.0 5.2 63.6 369.0 357.6 11.4 48.0 456.0 57.0 2.0 0.7 0.0 0.9 29.9 1.5 3.5 1.8 1.7 1.8 1.0 23.0 0.0 0.1 3.8

2:40 I 72

2.2 6.9 214.0 306.0 4.0 76.5 430.0 415.3 14.7 83.1 803.0 79.1 0.4 0.6 0.0 1.1 29.1 1.5 4.3 0.0 1.6 1.1 1.0 35.6 0.0 0.1 5.6

270 750 2.1 7.1 217.0 311.0 3.7 78.8 373.0 361.7 11.3 54.9 668.0 74.5 0.4 0.6 0.0 0.9 28.0 1.5 4.3 0.0 1.6 0.6 0.9 36.8 0.0 0.1 5.4

2.3 7.0 204.0 290.0 3.8 73.9 281.0 272.7 8.4 72.0 701.0 59.1 0.2 0.6 0.0 0.5 28.3 1.4 4.3 0.0 1.4 0.9 0.1 31.9 0.0 0.1 5.0

2:55 O 66

3.1 6.9 197.0 283.0 4.6 58.0 260.0 249.7 10.3 40.0 727.0 36.5 2.1 0.7 0.0 1.2 24.8 1.5 3.4 1.2 1.7 1.0 2.2 27.8 0.0 0.1 3.1

400 1500 3.6 7.0 196.0 280.0 4.7 59.2 337.0 326.0 11.0 35.4 661.0 60.8 2.2 1.1 0.0 1.1 21.4 1.5 3.4 1.4 1.7 1.0 2.3 24.9 0.0 0.1 3.3

3.0 7.1 201.0 289.0 5.2 58.7 361.0 338.9 22.1 55.6 663.0 69.5 2.1 0.7 0.0 0.9 22.0 1.5 3.4 1.3 1.6 1.8 1.2 27.9 0.0 0.1 4.0

3:10 I 162.00

5.9 6.9 170.0 242.0 3.2 57.7 283.0 269.7 13.3 57.1 525.0 55.2 0.1 0.3 0.0 0.0 23.9 1.4 3.6 0.0 1.4 2.0 0.0 27.0 0.0 0.1 5.3

140 610 6.2 6.9 170.0 243.0 3.4 57.1 281.0 281.0 0.0 50.0 541.0 61.6 0.1 0.4 0.0 0.0 28.1 1.4 3.8 0.0 1.4 3.1 0.8 33.5 0.0 0.1 7.0

7.8 7.0 168.0 240.0 3.4 56.7 0.0 -6.8 6.8 50.0 518.0 58.4 0.0 0.3 0.0 0.0 21.9 1.4 3.3 0.0 1.3 1.7 0.4 34.1 0.0 0.2 4.8

3:25 O 108.00

4.9 7.2 147.0 210.0 4.1 55.9 9.8 2.6 7.2 - 451.0 48.4 1.7 0.4 0.0 0.0 15.8 1.4 3.1 1.1 1.4 2.1 0.5 20.5 0.0 0.1 3.6

440 2000 7.5 7.1 144.0 207.0 4.6 55.9 9.7 3.1 6.7 - 488.0 64.3 1.9 0.4 0.0 0.0 15.2 1.5 3.0 1.3 1.5 2.7 0.5 20.6 0.0 0.1 4.1

5.9 7.1 144.0 207.0 4.3 57.4 15.0 4.4 10.6 - 469.0 44.3 1.7 0.4 0.0 0.0 15.7 1.4 3.0 1.1 1.4 2.2 -0.4 17.1 0.0 0.1 3.6

evaluation of bioretention systems for stormwater quality

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