eric strecker2

1

Overview of Unit Processes Approach for BMP Selection and

Design

Overview of Unit Processes Approach for BMP Selection and

Design

1

Eric W. Strecker, [email protected]

DesignDesign

Understanding and Applying Knowledge of Performance of Best Management Practices

2We have a long way to go!But, we have learned a lot!

Stormwater BMP Selection and Design and Design Standards

Stormwater BMP Selection and Design and Design Standards

Should be targeted to “solving the problem's”; not just meet NPDES requirements

Should be targeted to “solving the problem's”; not just meet NPDES requirements

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Design StandardsDesign Standards

Typically have focused almost entirely on “Size of Storm” for runoff treatment with no or little requirements for specifically addressing pollutants/parameters of concern

Typically have focused almost entirely on “Size of Storm” for runoff treatment with no or little requirements for specifically addressing pollutants/parameters of concern

4

Rarely have design standards development efforts started with the questions:

What are the pollutants and parameters of concern?Will/can/how will my design standards for new and re-development address those parameters?

Rarely have design standards development efforts started with the questions:

What are the pollutants and parameters of concern?Will/can/how will my design standards for new and re-development address those parameters?

Setting Design StandardsSetting Design Standards1. Identify Pollutants and Parameters of Concern and

Goals303d listingsTMDLs

Other Typical Pollutants of Concern

1. Identify Pollutants and Parameters of Concern and Goals

303d listingsTMDLs

Other Typical Pollutants of Concern

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o The usual “suspects”

Other Parameters of Concern:o Flow increases and resulting stream erosiono Temperature

o Select a list that represents most of the issues/problems that need to be addressed and develop goals

o The usual “suspects”

Other Parameters of Concern:o Flow increases and resulting stream erosiono Temperature

o Select a list that represents most of the issues/problems that need to be addressed and develop goals

Setting Design StandardsSetting Design Standards

2. Identify Unit Processes Required to Address Pollutants/Parameters of Concern:

Physical

2. Identify Unit Processes Required to Address Pollutants/Parameters of Concern:

Physical

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Physical

Biological

Chemical

Physical

Biological

Chemical

2


3. Apply unit processes and empirical data to set design criteria/standards (or selection and design BMPs)

Hydrologic/Hydraulic Long-term simulations of precipitation/runoff/BMP hydraulicsA h h ff i d d d

3. Apply unit processes and empirical data to set design criteria/standards (or selection and design BMPs)

Hydrologic/Hydraulic Long-term simulations of precipitation/runoff/BMP hydraulicsA h h ff i d d d

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Assess how much runoff is prevented, treated and not treated

Assess effects of BMPs on flow-durationLong-term simulations of particle settling (using particle settling theory)Apply empirical data for other constituents to predict treated effluent quality

Assess how much runoff is prevented, treated and not treated

Assess effects of BMPs on flow-durationLong-term simulations of particle settling (using particle settling theory)Apply empirical data for other constituents to predict treated effluent quality


4. Evaluate various potential options and conduct cost/effectiveness

Select example sites/land usesDevelop potential BMP options

l i l i f

4. Evaluate various potential options and conduct cost/effectiveness

Select example sites/land usesDevelop potential BMP options

l i l i f

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Run long-term simulations for various sizing and hydraulicsEvaluate cost implications and effectiveness looking at “real sites”

5. Select design standards6. Provide for both prescriptive and

performance options

Run long-term simulations for various sizing and hydraulicsEvaluate cost implications and effectiveness looking at “real sites”

5. Select design standards6. Provide for both prescriptive and

performance options

Background and Context Background and Context

Projects:National Cooperative Highway Research Program Project 25-20(01)

“Development of a BMP Evaluation Methodology for Highway Applications”

Chris Hedges PO, Ed Herricks Chair of PSC

Projects:National Cooperative Highway Research Program Project 25-20(01)

“Development of a BMP Evaluation Methodology for Highway Applications”

Chris Hedges PO, Ed Herricks Chair of PSC

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Water Environment Research Federation Project 02-SW-1:

Critical Assessment of Stormwater Control Selection Issues

Jeff Moeller PO, Bob Pitt Chair of PSC

Primary DeliverablesGuidance Manuals on BMP Selection and Design

Water Environment Research Federation Project 02-SW-1:

Critical Assessment of Stormwater Control Selection Issues

Jeff Moeller PO, Bob Pitt Chair of PSC

Primary DeliverablesGuidance Manuals on BMP Selection and Design

Background and Context WERF - Publication

Background and Context WERF - Publication

Available to WERF Subscribers now;Available to others IWA

Available to WERF Subscribers now;Available to others IWA

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IWA

www.werf.orgwww.werf.orgwww.iwahq.org.ukwww.iwahq.org.uk

IWA

www.werf.orgwww.werf.orgwww.iwahq.org.ukwww.iwahq.org.uk

Overall Goal For ProjectsOverall Goal For Projects

Use the “best information” available to provide guidance on the selection and use of stormwater water quality controls

Unit Processes

Use the “best information” available to provide guidance on the selection and use of stormwater water quality controls

Unit Processes

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Observed BMP Performance

Develop stormwater controls selection and evaluation methodology for use by practitioners

NCHRP – Highway Specific

WERF – Urban Environment

Observed BMP Performance

Develop stormwater controls selection and evaluation methodology for use by practitioners

NCHRP – Highway Specific

WERF – Urban Environment

Achieving Project Goals Achieving Project Goals

Emphasize

Treatabilty

Evaluation and design by examination of fundamental unit processes

Emphasize

Treatabilty

Evaluation and design by examination of fundamental unit processes

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Include criteria of practicability, performance, and hydrologic assessment on a control-specific and regional basis

Provide technical guidance documents and related reports/research findings

Include criteria of practicability, performance, and hydrologic assessment on a control-specific and regional basis

Provide technical guidance documents and related reports/research findings

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Definition-Fundamental Unit Process

Definition-Fundamental Unit Process

Underlying Hydrologic, Hydraulic, Physical, Chemical, and Biological Treatment Mechanisms

Underlying Hydrologic, Hydraulic, Physical, Chemical, and Biological Treatment Mechanisms

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Treatment MechanismsTreatment Mechanisms

Definition-Treatment System Component (TSC)

Definition-Treatment System Component (TSC)

Design element or feature of a stormwater control or treatment system that includes one or more

Design element or feature of a stormwater control or treatment system that includes one or more

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system that includes one or more fundamental unit processes or operations

system that includes one or more fundamental unit processes or operations

Definition-Treatment System

“Best Management Practice (BMP)”

Definition-Treatment System

“Best Management Practice (BMP)”

A complete structure or device for removing, reducing, retarding, or A complete structure or device for removing, reducing, retarding, or

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preventing targeted stormwater runoff, runoff constituents, pollutants, and contaminants from reaching receiving waters.

preventing targeted stormwater runoff, runoff constituents, pollutants, and contaminants from reaching receiving waters.

Definition-Treatment Train

Definition-Treatment Train

More than one stormwater control or treatment system in series

i ibl h h

More than one stormwater control or treatment system in series

i ibl h h

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It is possible to have more than one treatment train at a siteIt is possible to have more than one treatment train at a site

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How to apply research to real problems?

How to apply research to real problems?

What approach best incorporates the state of the practice?Focus on selecting treatment trains that

What approach best incorporates the state of the practice?Focus on selecting treatment trains that

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gmeet specific project goals (e.g. address specific pollutants of concern, etc.)

Integrated Unit Process Design Approach

gmeet specific project goals (e.g. address specific pollutants of concern, etc.)

Integrated Unit Process Design Approach

4

BMP Selection

and D i

BMP Selection

and D i

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Design ProcessDesign

Process

Step 1. Problem DefinitionStep 1. Problem Definition

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Key Concepts:What is the overall project scope and what are the regulatory drivers of stormwater management? How do stormwater management objectives relate to or conflict with other project objectives? What site conditions should be evaluated to properly define the problem?

Key Concepts:What is the overall project scope and what are the regulatory drivers of stormwater management? How do stormwater management objectives relate to or conflict with other project objectives? What site conditions should be evaluated to properly define the problem?

Urban Runoff Management Objectives Checklist Urban Runoff Management Objectives Checklist Category Typical Objectives of Urban Runoff Management Projects

Hydraulics Manage flow characteristics upstream, within, and/or downstream of treatment system components

Hydrology Mitigate floods; improve runoff characteristics (peak shaving) Reduce downstream pollutant loads and concentrations of pollutants Improve/minimize downstream temperature impact Achieve desired pollutant concentration in outflow

Water Quality

Remove litter and debris Reduce acute toxicity of runoff Toxicity Reduce chronic toxicity of runoff Comply with NPDES permit Regulatory Meet local, state, or federal water quality criteria

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Meet local, state, or federal water quality criteria Implementation Function within management and oversight structure Cost Minimize capital, operation, and maintenance (life-cycle) costs Aesthetic Improve appearance of site and avoid odor or nuisance

Operate within maintenance and repair schedule and requirements Maintenance Design system to allow for retrofit, modification, or expansion

Longevity Achieve long-term functionality Improve downstream aquatic environment/erosion control Improve wildlife habitat Resources Achieve multiple use functionality Function without significant risk or liability Function with minimal environmental risk downstream Safety, Risk and

Liability Contain spills

Public Perception Clarify public understanding of runoff quality, quantity and impacts on receiving waters * Objectives adapted from ASCE/EPA, 2002.

Step 2. Characterize Site Conditions and Constraints Step 2. Characterize Site Conditions and Constraints

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Key Concepts:What watershed characteristics should be evaluated during the data collection stageWhat site characteristics should be evaluated to identify site constraints?What water quality data should be collected for subsequent stages of the project?

Key Concepts:What watershed characteristics should be evaluated during the data collection stageWhat site characteristics should be evaluated to identify site constraints?What water quality data should be collected for subsequent stages of the project?

Step 3. Identify Fundamental Operation and Process Categories

Step 3. Identify Fundamental Operation and Process CategoriesSTEP 3

Identification of Applicable Fundamental Process Categories

(FPCs)

Select Applicable Physical Treatment Operations

(Particle Size Alteration, Size Separation, Density Separation, Aeration, Volatilization,

Physical Agent Disinfection)

Select Applicable Hydrologic Operations

(Peak Attenuation, Volume Reduction)

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Key Concepts:What hydrologic controls may be potentially applicable for your project?What physical unit operations may be of use in your design?What chemical and biological processes may be applicable for water quality treatment?

Key Concepts:What hydrologic controls may be potentially applicable for your project?What physical unit operations may be of use in your design?What chemical and biological processes may be applicable for water quality treatment?

Set of Applicable UnitOperations and Processes

Select Applicable Chemical Processes

(Sorption Processes, Flocculation/Precipitation,Chemical

Disinfection)

Select Applicable Biological Processes

(Microbially Mediated Transformations,Uptake and Storage)

Hydrologic/HydraulicHydrologic/Hydraulic

Fundamental Process Category (FPC)

Unit Operation or Process (UOP)Target Pollutants

Typical Treatment System Components (TSCs)

Hydrologic Flow and Volume Attenuation Extended detention basins

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y gOperations Retention/detention ponds

WetlandsTanks/vaultsEqualization basins

Volume ReductionAll pollutant loads

Infiltration/exfiltration trenches and basins Permeable or porous pavementBioretention cellsDry swalesDry wellExtended detention basins

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Physical Treatment OperationsPhysical Treatment Operations


Unit Operation or Process (UOP)

Target Pollutants


Physical Treatment O ti

Particle Size AlterationCoarse sediment

Comminutors (not common for stormwater)Mixers (not common for stormwater)

Physical Sorption Engineered media granular activated carbon

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Operations Physical SorptionNutrients, metals, petroleum

compounds

Engineered media, granular activated carbon, and sand/gravel (at a lower capacity)

Size Separation and Exclusion (screening and filtration)

Coarse sediment, trash, debris

Screens/bars/trash racksBiofiltersPermeable or porous pavementInfiltration/exfiltration trenches and basinsManufactured bioretention systemsEngineered media/granular/sand/compost filtersHydrodynamic separatorsCatch basin inserts (i.e., surficial filters)

Physical Treatment OperationsPhysical Treatment OperationsFundamental Process Category (FPC)



Physical Treatment Operations

Density, Gravity, Inertial Separation (grit separation, sedimentation , flotation and skimming, and clarification)

Sediment, trash, debris, oil and grease Extended detention basins Retention/detention ponds Wetlands Settling basins, Tanks/vaults Swales with check dams Oil-water separators

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check dams Oil-water separators Hydrodynamic separators Aeration and Volatilization

Aeration and Volatilization Oxygen demand, PAHs, VOCs Sprinklers Aerators Mixers (not common for stormwater) Physical Agent Disinfection

Physical Agent Disinfection Pathogens Shallow detention ponds Ultra-violet systems

Biological ProcessesBiological Processes




Biological Processes

Microbially Mediated Transformation (can include oxidation,

WetlandsBioretention systemsBiofilters (and engineered bio-media

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include oxidation, reduction, or facultative processes)Metals, nutrients, organic pollutants

Biofilters (and engineered bio media filters)

Retention pondsMedia/sand/compost filters

Uptake and StorageMetals, nutrients, organic pollutants

Wetlands/wetland channelsBioretention systemsBiofiltersRetention ponds

Chemical ProcessesChemical Processes




Chemical Processes

Chemical Sorption ProcessesMetals, nutrients, organic

ll t t

Subsurface wetlandsEngineered media/sand/compost filtersI filt ti / filt ti t h d b i

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Processes pollutants Infiltration/exfiltration trenches and basins

Coagulation/FlocculationFine sediment, nutrients

Detention/retention pondsCoagulant/flocculant injection systems

Ion ExchangeMetals, nutrients

Engineered media, zeolites, peats, surface complexation media

Chemical DisinfectionPathogens

Custom devices for mixing chlorine or aerating with ozone

Advanced treatment systems

Step 4. Select Treatment System Components Step 4. Select Treatment System Components

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Key Concepts:How should the treatment train approach be used in system design?What hydrologic controls are available?What pretreatment options are applicable?What conventional treatment system components can be used for the core design?What tertiary enhancements can be incorporated?

Key Concepts:How should the treatment train approach be used in system design?What hydrologic controls are available?What pretreatment options are applicable?What conventional treatment system components can be used for the core design?What tertiary enhancements can be incorporated?

Ranking of Conventional TSCs According to the UOP (unit

operations and processes) Effectiveness Level Ranking of Conventional TSCs According to the UOP (unit

operations and processes) Effectiveness Level Conventional TSCs

Fundamental Process Category

Unit Operations or Processes

Hydr

o-dy

nami

c De

vices

Settli

ng B

asins

Tank

s and

Vau

lts

Fine M

esh S

creen

s

Filter

Fab

ric

Biofi

lters

Media

Filte

rs

Exten

ded D

etenti

on

Pond

s

Reten

tion P

onds

Infiltr

ation

Bas

ins

Typical Location in Treatment Train P P P P P P/S P/S S S S

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Flow attenuation (hydrograph matching) 0 2 3 0 0 1 0 5 4 to 5 3 to 5

Reduce total volume of runoff 0 0 0 0 0 3 to 5 0 2 to 3 1 5 Hydrology / Hydraulics

Flow-duration control and design 0 1 3 0 0 1 0 4 to 5 4 to 5 4 to 5

P - Primary treatment, S - Secondary treatment 0 - TSC does not include unit process OR is not recommended for that process due to operations and maintenance issues (e.g., a filter should not be used to screen) 1 - TSC includes unit process, but likely provides poor effectiveness 2 - TSC includes process, but likely provides marginal effectiveness 3 - TSC designed to include unit process, but other TSCs may be more effective 4 - TSC is specifically designed to include unit process, but design not optimal 5 - TSC is specifically designed to include unit process and is among the best alternatives available

6

Ranking of Conventional TSCs According to the UOP Effectiveness Level


Conventional TSCs



Hydr

o-dy

nami

c De

vices

Settli

ng B

asins

Tank

s and

Vau

lts

Fine M

esh S

creen

s

Filter

Fab

ric

Biofi

lters

Media

Filte

rs

Exten

ded D

etenti

on

Pond

s

Reten

tion P

onds

Infiltr

ation

Bas

ins

Typical Location in Treatment Train P P P P P P/S P/S S S S Screening 3 to 5 0 0 5 0 1 to 5 0 to 5 0 0 0 Filtration 0 0 0 3 3 3 to 5 5 0 0 4

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Settling 2 to 3 3 3 0 0 3 to 5 0 3 5 2 Flotation and Skimming 3 to 5 0 2 0 0 0 0 0 0 0 Sorption processes (absorption) 0 0 0 0 2 3 to 5 4 to 5 0 0 2

Volatilization / Aeration 1 0 0 0 0 1 to 3 0 3 3 0

Physical Operations

Physical agent disinfection (heat and ultra-violet radiation) 0 1 0 0 0 1 0 2 2 1




Conventional TSCs



Hydr

o-dy

nami

c De

vices

Settli

ng B

asins

Tank

s and

Vau

lts

Fine M

esh S

creen

s

Filter

Fab

ric

Biofi

lters

Media

Filte

rs

Exten

ded D

etenti

on

Pond

s

Reten

tion P

onds

Infiltr

ation

Bas

ins

Typical Location in Treatment Train P P P P P P/S P/S S S S Microbially-mediated transformations 0 0 0 0 0 0 to 2 2 3 4 2 Biological

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transformations Biological Processes Uptake and storage 0 0 0 0 0 0 to 2 1 2 3 1

Sorption processes (adsorption) 0 0 0 0 2 3 4 to 5 1 to 2 2 4

Flocculation / Precipitation 0 0 0 0 0 0 0 0 to 2 2 0 Chemical Processes Chemical agent disinfection

(ozone, chlorine and chlorine compounds)

0 0 0 0 0 0 0 0 0 0


Ranking of Tertiary

Enhancements According to the

UOP Effectiveness

Level

Ranking of Tertiary

Enhancements According to the

UOP Effectiveness

Level

Tertiary Enhancements Category Unit Operations and Processes

Soils

/ So

il Am

endm

ents

Micr

obial

Co

mmun

ities

Vege

tatio

n

Disin

fecti

on

Syste

m

Sprin

klers

Aera

tors

Floc

culan

t / Pr

ecipi

tant

Injec

tion S

ys.

Flow attenuation (hydrograph matching)

0 0 1 0 0 0 0 Hydrology / Hydraulics Operations Reduce total volume of

runoff 5 0 2 0 1 1 0

Screening 0 0 3 0 0 0 0 Filtration 5 0 4 0 0 0 0 Settling 0 0 0 0 0 0 5 Flotation and Skimming 0 0 0 0 0 0 1 Sorption processes (absorption)

4 0 2 0 0 0 0

Volatilization / Aeration 1 0 2 0 5 5 0

Physical Operations

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Level Level Volatilization / Aeration 1 0 2 0 5 5 0 Physical agent disinfection (heat and ultra-violet radiation)

0 0 0 5 0 0 0

Microbially-mediated transformations

5 5 3 0 0 0 0 Biological Process Uptake and storage 3 4 2 to 5 0 0 0 0

Sorption processes (adsorption)

4 to 5 0 3 to 4 0 0 0 0

Flocculation / Precipitation 0 0 0 0 0 0 5 Chemical Processes Chemical agent disinfection

(ozone, chlorine and chlorine compounds)

0 0 0 5 0 0 0

0 - TSC does not include UOP or is not recommended due to operations and maintenance issues (e.g., a filter should not be used to screen) 1 - TSC includes UOP, but likely provides poor effectiveness 2 - TSC includes UOP, but likely provides marginal effectiveness 3 - TSC designed to include UOP, but other TSCs may be more effective 4 - TSC is specifically designed to include UOP, but design not optimal 5 - TSC is specifically designed to include UOP and is among the best alternatives available

Conceptual Framework for Selecting TSCs Based on Particle Size.

Conceptual Framework for Selecting TSCs Based on Particle Size.

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Step 5. Practicability Assessment of Candidate Treatment Systems

Step 5. Practicability Assessment of Candidate Treatment Systems

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Key Concepts:How can you identify the best treatment system option based on hydrologic and hydraulic performance?What resources are available to help select the best treatment option from the candidate TSCs based on treatability data and water quality performance?

Key Concepts:How can you identify the best treatment system option based on hydrologic and hydraulic performance?What resources are available to help select the best treatment option from the candidate TSCs based on treatability data and water quality performance?

Recommended Measures of BMP Performance

Recommended Measures of BMP Performance

How much stormwater runoff is prevented? (“hydrological source control”)

How much of the runoff that occurs is treated by the BMP or not (“hydraulic performance”)?

Of the runoff treated, what is the effluent quality?

How much stormwater runoff is prevented? (“hydrological source control”)

How much of the runoff that occurs is treated by the BMP or not (“hydraulic performance”)?

Of the runoff treated, what is the effluent quality?

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Of the runoff treated, what is the effluent quality? (“concentration characteristics achieved”)

Does the BMP address downstream erosion impacts?

Of the runoff treated, what is the effluent quality? (“concentration characteristics achieved”)

Does the BMP address downstream erosion impacts?

Percent Removal is Very Problematic and SHOULD NOT be used as a performance measure for BMPs.

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Biofilters (N=16) (Swale and Filter Strips)

0.0 0.3 0.6 0.9 1.2 1.5 0.0

0.3

0.6

0.9

1.2

1.5

Detention Basins (N=11) (Dry Ponds)

0.0 0.3 0.6 0.9 1.2 1.50.0

0.3

0.6

0.9

1.2

1.5

Inflow (watershed inches) Inflow (watershed inches)

Out

flow

(wat

ersh

ed in

ches

)

Out

flow

(wat

ersh

ed in

ches

) Average Ratio (Out/In) = 0.79

Average Ratio (Out/In) = 1.12

n=144 n=75

RunoffVolumeControl

RunoffVolumeControl

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Retention Ponds (N=20) (Wet Ponds)

0.0 0.3 0.6 0.9 1.2 1.5 0.0

0.3

0.6

0.9

1.2

1.5

Wetland Basins (N=10)

0.0 0.3 0.6 0.9 1.2 1.50.0

0.3

0.6

0.9

1.2

1.5


Out

flow

(wat

ersh

ed in

ches

)

Out

flow

(wat

ersh

ed in

ches

)



n=276 n=195

ET lossesInfiltration

BMP Type Mean Monitored Outflow/Mean Monitored Inflow for Events Where Inflow is Greater

Than or Equal to 0.2 Watershed Inches

Detention Basins 0.70Biofilters 0.62Media Filters 1.00

RunoffVolumeControl

Consider “credit” for

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Hydrodynamic Devices

1.00

Wetland Basins 0.95

Retention Ponds 0.93

Wetland Channels

1.00

volume reduction in

design requirements

Box plots of the fractions of Total Suspended Solids (TSS) removed and of effluent quality of

selected BMP types

Box plots of the fractions of Total Suspended Solids (TSS) removed and of effluent quality of

selected BMP types

0 6

0.8

1.0

0 6

0.8

1.0

Rem

oved

10 00

100.00

mg/

l)

3rdQuartile

1st Quartile

MedianLower 95% CL

Upper 95% CL

Upper Inner Fence

Lower Inner FenceOutside Value

90 % 11 to 18 mg/l

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0.0

0.2

0.4

0.6

- 0.0

0.2

0.4

0.6

Frac

tion

of T

SS

BMP Type BMP Type

0.10

1.00

10.00

TSS

(

Detention Basins

Hydro Dynamic Devices

Bioswales Media Filters

Retention Basins

Wetlands Detention Basins

Hydro Dynamic Devices

Bioswales

Retention Basins

Wetlands

50 %

Box plots of effluent quality of selected BMP types for Total Phosphorus and Total CopperBox plots of effluent quality of selected BMP types for Total Phosphorus and Total Copper

1 0

10.0

us (m

g/l) 100.0

(mg/

l)

3rd Quartile

1st Quartile

MedianLower 95% CL

Upper 95% CL

Upper Inner Fence

Lower Inner FenceOutside Value

r (ug

/l)

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BioswalesDetentionBasins

MediaFilters

Hydro-DynamicDevices

RetentionBasins

Wetlands

BMP Type

0.001

0.010

0.10

1.0

Tota

l Pho

spho

ru 10.0

Tota

l Cop

per (

1.0

0.1 Bioswales Detention Basins Media

FiltersHydro-DynamicDevices

RetentionBasins

Wetlands

BMP Type

Tota

l Cop

per

Box plots of effluent quality of selected BMP types for Fecal Coliform and Fecal Coliform inflow and outflow

by event.

Box plots of effluent quality of selected BMP types for Fecal Coliform and Fecal Coliform inflow and outflow

by event.

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Lake George Field Study Evaluation Vortechs model 11000

Lake George Field Study Evaluation Vortechs model 11000

Runoff TSSin (mg/L) TSSout (mg/L) % Reduction Event # Interpolated Arithmetic Interpolated Arithmetic Interpolated Arithmetic

1 987.48 693.52 263.18 205.98 73% 70%2 128.73 88.57 59.23 59.18 54% 33%3 1040.04 882.42 337.87 486.75 68% 45%4 213.73 225.42 359.14 388.08 -68% -72%5 1673.57 1217.53 71.39 102.84 96% 92%6 535.16 603.54 70.14 85.23 87% 86%

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7 180.81 132.22 29.76 34.88 84% 74%8 2491.55 2202.78 35.41 35.47 99% 98%9 89.99 76.60 31.98 33.14 64% 57%10 1047.02 2257.46 37.08 31.22 96% 99%11 439.45 344.86 16.57 13.83 96% 96%12 445.19 291.58 17.36 14.91 96% 95%13 1156.16 674.94 44.72 37.91 96% 94%

Averages 802.2215 745.4954 105.6792 117.6477 87% 84%

(Winkler and Guswa 2002)Is an average of 100+ mg/l TSS acceptable performance?Is an average of 100+ mg/l TSS acceptable performance?

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Percent Removal Use ResultsPercent Removal Use Results

BMPs improperly “rejected”

BMPs improperly “accepted”

“Daisy-Chaining” BMPs and applied % removals at each t th t hi hl di t

BMPs improperly “rejected”

BMPs improperly “accepted”

“Daisy-Chaining” BMPs and applied % removals at each t th t hi hl di t

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step that highly over predicts performance

Improper use of TSS as the sole indicator of performance

Etc. Etc.

step that highly over predicts performance

Improper use of TSS as the sole indicator of performance

Etc. Etc.

Our data coincides with the BMP Database publications advocating effluent quality as a performance measure. Our data coincides with the BMP Database publications advocating effluent quality as a performance measure.

TSS Removal Per Storm

60

80

100

out (

mg/

L)

Unimproved Ditches Vaults Wet Ponds Dry Ponds Compost Shoulder Ecology Embankment Bioswale

Percent removal based Performance Goal

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0

20

40

60

0 50 100 150 200 250 300 350 400

Concentration in (mg/L)

Con

cent

ratio

n o Vegetated Filter Strip

What’s the problem with faulty performance goals and perceptions?

What’s the problem with faulty performance goals and perceptions?

Mistake Consequence

Failure to recognize that BMPs perform best when influent is dirtiest.

Overly stringent design requirements.Overestimated project impacts.

Failure to recognize that BMPs are required in places

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Failure to recognize that BMP effectiveness tapers off at the “minimum irreducible concentration”.

BMPs are required in places where they can’t make a difference.Source control may not recognized as the best means for further improvements.

Fail to define effluent load and concentrations.

Focus shifted from environmental consequences.Impacts can’t be quantified.

Step 6. Design Selected Treatment SystemStep 6. Design Selected Treatment System

STEP 6Size and Develop Conceptual Design

of Selected Treatment System

Sizing Methodology(Volume and

Flow-Based Systems)

Design Optimization(Continuous Simulation and

Spreadsheet Methods)

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Key Concepts:What level of analysis is needed to adequately size and conceptually design treatment system options?How do you optimize the design and verify that project goals will be met?

Key Concepts:What level of analysis is needed to adequately size and conceptually design treatment system options?How do you optimize the design and verify that project goals will be met?

Preliminary Design of Treatment System

Adaptive Management and Design Flexibility(Design Elements, Inherently Safe and Functional)

Typical Outlet Structures Used in Detention Basins.Typical Outlet Structures Used in Detention Basins.

47

Integrating Multiple Functions/Outlet Structures

Integrating Multiple Functions/Outlet Structures

48

9

Effective Work Index (W)

Range of Geomorphically Significant flows

49

Characteristics of Bed and Bank

Materials

τc τbi

Stream Flow

( ) tWn

icbi Δ⋅−=∑

=

5.1

1ττ

τc

Normal Dry Weather Flow Level

Illustration of the Flow-Duration Methodology.Source: Santa Clara Valley Urban Runoff Pollution Prevention Program

(SCVURPPP, 2004).

Illustration of the Flow-Duration Methodology.Source: Santa Clara Valley Urban Runoff Pollution Prevention Program

(SCVURPPP, 2004).

50

Erosion Potential (Ep)Erosion Potential (Ep)

ShearShear

pre

post

WW

Ep =( ) tWn

icbi Δ⋅−=∑

=

5.1

1ττ

51

PostPost--UrbanUrban

PrePre--UrbanUrban

Work DoneWork Done

TimeTime

Shear Shear StressStress

τc

Example Comparison of Flow-Duration Control Design.Source: Santa Clara Valley Urban Runoff Pollution Prevention Program (SCVURPPP,

2004).

Example Comparison of Flow-Duration Control Design.Source: Santa Clara Valley Urban Runoff Pollution Prevention Program (SCVURPPP,

2004).

52

Recommended Process ModelingRecommended Process ModelingContinuous simulation, using a model suited to the task

Continuous simulation models can be used to simulate the effects of use of simpler methods for sizing treatment systems.

Event models of “classical” hydrology, using site-specific data.

These models should only be used when verified with a ti i l ti h i ll iti l f

Continuous simulation, using a model suited to the taskContinuous simulation models can be used to simulate the effects of use of simpler methods for sizing treatment systems.

Event models of “classical” hydrology, using site-specific data.

These models should only be used when verified with a ti i l ti h i ll iti l f

53

continuous simulation approach; especially critical for design of systems for reducing downstream erosion.

Generalized regional guidelinesThese can include simplified methods provided by WEF and ASCE (1998), BUT should be adapted/confirmed for local conditions

These regional guidelines might provide a starting point for event and continuous models.

continuous simulation approach; especially critical for design of systems for reducing downstream erosion.

Generalized regional guidelinesThese can include simplified methods provided by WEF and ASCE (1998), BUT should be adapted/confirmed for local conditions

These regional guidelines might provide a starting point for event and continuous models.

Step 7. Performance Monitoring and EvaluationStep 7. Performance Monitoring and Evaluation

54

Key Concepts:What monitoring is needed or required to demonstrate long-term project success

How will the monitoring program be implemented?

Key Concepts:What monitoring is needed or required to demonstrate long-term project success

How will the monitoring program be implemented?

10

Example Conceptual Design Using the Integrated Treatment Process

Approach

Example Conceptual Design Using the Integrated Treatment Process

Approach

Characterize site conditions and identify constraints

Id tif F d t l U it P

Characterize site conditions and identify constraints

Id tif F d t l U it P

55

Identify Fundamental Unit Process Categories (FPCs) and associated Treatment System Components (TSCs)

Formulate design alternatives

Critically assess alternatives and select most feasible alternative

Size/configure the facility

Identify Fundamental Unit Process Categories (FPCs) and associated Treatment System Components (TSCs)

Formulate design alternatives

Critically assess alternatives and select most feasible alternative

Size/configure the facility

Example Site Characterization and Constraint Identification

New highway in an urban setting in warm arid region

Type B soils and groundwater is deep, but sole-if

New highway in an urban setting in warm arid region

Type B soils and groundwater is deep, but sole-if

56

source aquifer

Receiving waters with TSS and dissolved copper TMDLs established

Concern about erosive discharges and a requirement to reduce post-const runoff

Need a BMP with low land requirements or multi-use functionality

source aquifer

Receiving waters with TSS and dissolved copper TMDLs established

Concern about erosive discharges and a requirement to reduce post-const runoff

Need a BMP with low land requirements or multi-use functionality

Consider each of the Fundamental Process Categories (FPCs)

Consider each of the Fundamental Process Categories (FPCs)

Physical Processes:Hydrologic/Hydraulic

Physical Processes:Hydrologic/Hydraulic

57

Treatment

Biological Treatment ProcessesChemical Treatment Processes

Treatment

Biological Treatment ProcessesChemical Treatment Processes

Reduce Runoff Volumes Reduce Runoff Volumes

Emphasis on BMPs that reduce runoff volumes by evapotranspiration and infiltrationManage runoff rates and/or volumes and/or instream measures to reduce

Emphasis on BMPs that reduce runoff volumes by evapotranspiration and infiltrationManage runoff rates and/or volumes and/or instream measures to reduce

58

and/or instream measures to reduce stream erosionand/or instream measures to reduce stream erosion

Biofilters (N=16) (Swale and Filter Strips)

0.0 0.3 0.6 0.9 1.2 1.5 0.0

0.3

0.6

0.9

1.2

1.5

Detention Basins (N=11) (Dry Ponds)

0.0 0.3 0.6 0.9 1.2 1.50.0

0.3

0.6

0.9

1.2

1.5


Out

flow

(wat

ersh

ed in

ches

)

Out

flow

(wat

ersh

ed in

ches

) Average Ratio (Out/In) = 0.79


n=144 n=75

RunoffVolumeControl

RunoffVolumeControl

59

Retention Ponds (N=20) (Wet Ponds)

0.0 0.3 0.6 0.9 1.2 1.5 0.0

0.3

0.6

0.9

1.2

1.5

Wetland Basins (N=10)

0.0 0.3 0.6 0.9 1.2 1.50.0

0.3

0.6

0.9

1.2

1.5


Out

flow

(wat

ersh

ed in

ches

)

Out

flow

(wat

ersh

ed in

ches

)



n=276 n=195

Applicable/selected Physical Treatment Processes

Applicable/selected Physical Treatment Processes

Particle/Material Size SeparationFiltration

to remove suspended particulates and attached pollutants (TSCs: screens, biofilters media filters infiltration

Particle/Material Size SeparationFiltration

to remove suspended particulates and attached pollutants (TSCs: screens, biofilters media filters infiltration

60

biofilters, media filters, infiltration facilities)

Particle/Material Density SeparationSedimentation

to remove settable solids and attached pollutants (TSCs: sedimentation basin/forebay, detention facilities, hydrodynamic devices)

biofilters, media filters, infiltration facilities)

Particle/Material Density SeparationSedimentation

to remove settable solids and attached pollutants (TSCs: sedimentation basin/forebay, detention facilities, hydrodynamic devices)

11

Types of DevicesTypes of Devices

FilteringCB Inserts

ScreeningLarger In-conveyance Devices

“Hydrodynamic Devices”In-ground “swirlly” devices

FilteringCB Inserts

ScreeningLarger In-conveyance Devices

“Hydrodynamic Devices”In-ground “swirlly” devices

61

g ySettling

Rapid Settlement for Dense Gross SolidsSeparation and Baffle Devices

Boxes with baffles, plates, hoods, etc.Maceration

Not useful in StormwaterCombination

CDS Unit – Fluid/particle separation and screening

g ySettling

Rapid Settlement for Dense Gross SolidsSeparation and Baffle Devices

Boxes with baffles, plates, hoods, etc.Maceration

Not useful in StormwaterCombination

CDS Unit – Fluid/particle separation and screening

Pollutant Fact Sheets

www.bmpdatabase.org


www.bmpdatabase.org

Copper (Cu) Treatability and available unit operations and processes

Treatability is a function of partitioning (particulate vs. aqueous); if aqueous, treatability is a function of concentration and speciation, and if particulate-bound, treatability is a function of distribution across the gradation. Once complexed in aqueous solution, uncharged aqueous complexes (i.e. CuCO3) are very difficult to remove unless precipitated or advanced unit operations such as reverse osmosis are applied. Complexation or partitioning can be reversible; particulate-bound Cu can be a chronic threat especially in a cyclic redox environment. Cu can partition to both the aqueous and particulate phases as a function of rainfall-runoff chemistry, hydrodynamics and residence time. The important forms of copper from a treatability and regulatory perspective are total, dissolved, and particulate-bound copper. If bound to organic or inorganic particles, viable unit operations include sedimentation and filtration either as separate unit operations or in combination with coagulation/flocculation as pre-treatment to these operations. If present as a complex, precipitation can be effective. If present as an ionic species such as Cu2+, then surface complexation (including adsorption) can be effective.

Form Unit Operation or Process Particulate-bound Sedimentation, filtration, coagulation-flocculation Dissolved Adsorption, surface complexation, ion exchange, precipitation

Description and properties

Copper is a reddish-brown, odorless metal which becomes dull when exposed to air. It is malleable, ductile, and an excellent conductor of heat and electricity, being second only to silver in terms of its high conductivity. Common forms in surface waters include complexes with organics (CuDOM), carbonate (CuCO3), hydroxide (CuOH+), sulfates (CuSO4), , and dissolved ionic forms (Cu2+), and (and to lesser degrees, Cu+ and depending on Cl- levels, CuCl where this species can become significant in coastal areas and areas subject to road de-icing salts containing chlorides). The relative percentages of these species are a function of rainfall-runoff chemistry and to a lesser degree hydrology. Of these, complexes with organics (CuDOM) and carbonate (CuCO3) are predominant in urban rainfall-runoff.

Species Molecular weight Specific gravity Solubility (g/100ml) Cu (metal) 63.6 9.0 Solid metal CuCO3 187.1 4.4 Variable CuSO4 159.6 3.6 75.4

62

CuCl 99.0 4.1 0.0062 Natural sources

Copper is a common element, naturally occurring in rocks, soil, waters, plants, animals, and humans. Besides small amounts of metallic copper, copper is found as sulfide or oxide ores.

Point sources Emissions to air, soil and water may result from mining and primary extraction processes (mineral processing, smelting, electrolytic processing, leaching and solvent extraction), and from manufacturing of products using and/or containing copper (electrical goods, pipes, alloys, etc.).

Diffuse sources and consumer products containing copper Diffuse sources include agricultural and commercial applications, gardening applications, leaching from paint on vessels and infrastructure. Automobile brakes generate abraded copper metal or alloyed copper during their normal use, contributing to copper metal in dry or wet deposition. Consumer products containing copper include coins, cigarettes, jewelry, electrical appliances, cookware, some unwashed agricultural products, some commercial gardening products, some vitamin / mineral dietary supplements, and treated wood products.

Environmental fate and transport Copper can partition to particles and organic matter, but can also be largely dissolved (ionic and complexed) in urban rainfall-runoff depending on rainfall-runoff chemistry, other species and residence time. Re-partitioned particulate-bound copper is distributed across the particle-size gradation. Copper can be transported as particles released into the atmosphere or as dissolved compounds in natural waters. Soluble and free ionic copper are easily taken up by plants. Finely-abraded metallic Cu or Cu-alloy particles are subject to aerodynamic and waterborne transport. Once contacted by poorly-buffered and acidic rainfall or runoff these finely-abraded particles undergo leaching and dissolution. Copper in soils can precipitate with hydroxide, phosphate, carbonate, and silicate to become a component of the amorphous fraction of soil. It can also be adsorbed on the negatively charged sorption sites of clay minerals and Cu can form both soluble and insoluble complexes with components of soil organic matter.

Aquatic toxicity Low pH, soft water, and high temperatures are known to increase toxicity of copper. Mixtures of copper and zinc are known to be additive or synergistic in toxicity to many aquatic organisms. The freshwater and saltwater criteria for dissolved copper are shown below.

CTR Criteria* Freshwater (100 mg/L hardness) Saltwater Acute (instantaneous maximum) 13 µg/L 4.8 µg/L Chronic (4-day average) 9.0 µg/L 3.1 µg/L

* California Toxics Rule, Federal Register May 2000


www.bmpdatabase.org


www.bmpdatabase.org

63

Chemical ProcessesChemical Processes

Flocculation/Precipitation Detention/Retention Ponds Ion Exchange Subsurface wetlands

Media/Sand/Compost filters

Chemical Processes

64

Media/Sand/Compost filtersUltra-Violet Disinfection Shallow retention ponds

Advanced treatment systems Chemical Disinfection Custom devices for mixing chlorine or

aerating with ozone Advanced treatment systems

Sorption Media filters Biofilters Wetlands/Wetland Channels Bioswales Bioretention Systems Media/Sand/Compost filters Catch basin inserts Porous pavement Infiltration/exfiltration trenches and basins

Integrating Unit Processes Into Design

Treatment System Components (TSCs)

Flow-Based TSCs (“flow-through”)

Detention-Based TSCs (“volume based”)

The Treatment Train:

Treatment System Components (TSCs)

Flow-Based TSCs (“flow-through”)

Detention-Based TSCs (“volume based”)


65


Gross Solids Removal (“Primary Treatment”)

Particulate Removal (“Secondary Treatment”)

Dissolved Constituent Removal (“Tertiary Treatment”)

Select Candidate Treatment Systems


Gross Solids Removal (“Primary Treatment”)

Particulate Removal (“Secondary Treatment”)

Dissolved Constituent Removal (“Tertiary Treatment”)

Select Candidate Treatment Systems

Alternative 1 – Flow Management, TSS, Trash and Debris and Dissolved Copper

Alternative 1 – Flow Management, TSS, Trash and Debris and Dissolved Copper

66

c

12

Critically Assess BMP Options

Expected PerformanceRequired Surface and Subsurface AreaCost

Expected PerformanceRequired Surface and Subsurface AreaCost

67

CostMaintenanceAesthetics

CostMaintenanceAesthetics

Low Impact Development (LID) in the Treatment Train

Low Impact Development (LID) in the Treatment Train

On-site/micro scale distributed controlsMany highways are already designed this way

On-site/micro scale distributed controlsMany highways are already designed this way

68

wayLID by accidentMany natural drainage (country drainage) designs are easily adapted/retrofit for improved WQ performance

wayLID by accidentMany natural drainage (country drainage) designs are easily adapted/retrofit for improved WQ performance

LID Center Photo

Recommendations for Setting of BMP Design Requirements


Recommended BMP Performance requirements should not use percent removal

Design standards should account for the hydrologic losses (HSC) that can occur with

Recommended BMP Performance requirements should not use percent removal

Design standards should account for the hydrologic losses (HSC) that can occur with

69

y g ( )some BMP types to encourage their use. o Both biofiltration systems and dry extended

detention ponds appear to show significant reductions in runoff that is routed through them.

o Much of this “loss” is likely evapotranspiration losses.

y g ( )some BMP types to encourage their use. o Both biofiltration systems and dry extended

detention ponds appear to show significant reductions in runoff that is routed through them.

o Much of this “loss” is likely evapotranspiration losses.



Continuous simulation techniques with local rainfall data and local conditions should be employed in developing design requirements to assess potential BMP design sizing vs. “percent capture” to ascertain hydrologic/hydraulic performance

Continuous simulation techniques with local rainfall data and local conditions should be employed in developing design requirements to assess potential BMP design sizing vs. “percent capture” to ascertain hydrologic/hydraulic performance

70

performanceo Expenditures of resources by the private

and public sector on BMPs

performanceo Expenditures of resources by the private

and public sector on BMPs

Example ApplicationExample Application

Lake Tahoe: Factoring potential BMP performance

TMDL Development TMDL “crediting”

Lake Tahoe: Factoring potential BMP performance

TMDL Development TMDL “crediting”

71

TMDL “crediting”TMDL “crediting”

Continuous SWMM modeling Together with BMP Effluent Performance to Assess BMP Performance at a Project Scale

How much runoff is evapotranspirated or infiltrated? Hydrological Source Control

How much runoff is treated (and not)?

What is effluent quality of

How much runoff is evapotranspirated or infiltrated? Hydrological Source Control

How much runoff is treated (and not)?

What is effluent quality of

72

treated runoff?

Evaluations included:Assessed effects of residence time

Evaluated 20 alternate sizing criteria (0.1” to 2”)

Generated performance curves for percent runoff captured as well as percent particle treated

treated runoff?

Evaluations included:Assessed effects of residence time

Evaluated 20 alternate sizing criteria (0.1” to 2”)

Generated performance curves for percent runoff captured as well as percent particle treated

13

BMP Performance Curves for Various Design Sizes and Draw Down times (Scenario Site, Met Grid 42)

BMP Performance Curves for Various Design Sizes and Draw Down times (Scenario Site, Met Grid 42)

73

85 to 95% “Capture” for 1” Depth Design depending on draw-down time

Effect of Sizing and Residence Time on Fine Particle Removal Efficiency

Effect of Sizing and Residence Time on Fine Particle Removal Efficiency

0102030405060708090

100

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2U it B i Si (i h )

% R

unof

f Cap

ture

d

0102030405060708090100

% P

artic

le T

reat

ed

36-hour

5 um

0102030405060708090

100

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2Unit Basin Size (inches)

% R

unof

f Cap

ture

d

0102030405060708090100

% P

artic

le T

reat

ed

24-hour

5 um

74

Unit Basin Size (inches) Unit Basin Size (inches)

0102030405060708090

100


% R

unof

f Cap

ture

d

0102030405060708090100

% P

artic

le T

reat

ed

48-hour

5 um

0102030405060708090

100


% R

unof

f Cap

ture

d

0102030405060708090100

% P

artic

le T

reat

ed

72-hour

5 um

---runoff ---fine particle

Methodology Development toEstimate Pollutant Load Reductions

For Lake Tahoe

Methodology Development toEstimate Pollutant Load Reductions

For Lake Tahoe

Goals and Objectives of Methodology

Focus on stormwater and BMPs in urbanized

Goals and Objectives of Methodology

Focus on stormwater and BMPs in urbanized

75

areasPractical for application by implementers

Include flexibility to modify in the future based on monitoring data or new research

areasPractical for application by implementers

Include flexibility to modify in the future based on monitoring data or new research

Overview – What’s been doneOverview – What’s been done

Summarize Local Practices Literature Review Summarize National

Practices

76

Screening CriteriaAnd Analysis

Develop Initial Methodology and Begin Testing

Overview – What’s been done (cont.)Overview – What’s been done (cont.)

Develop Initial Methodology and Begin Testing

77

Prepare Examples

Develop Working Tool

Present to PAC and Public for Comment

What we learned?What we learned?

Limited examples of similar work/methods developed for other areasExisting examples have typically not applied the latest findings regarding BMP performanceE i ti l f t l

Limited examples of similar work/methods developed for other areasExisting examples have typically not applied the latest findings regarding BMP performanceE i ti l f t l

78

Existing examples for source controls are essentially non-existentThere is limited performance data for many if not most BMPs

Existing examples for source controls are essentially non-existentThere is limited performance data for many if not most BMPs

14

Spreadsheet ToolSpreadsheet Tool

79

Methodology OverviewMethodology Overview

Hydrologic Simulation incl. hydrologic source controls

User Input

80

Pollutant Load Generation including source controls

Pollutant Load Reduction from Treatment BMPs

Pollutant Load

Hydrologic SimulationHydrologic Simulation

Multi-year continuous simulation using EPA SWMM running in background

Spreadsheet tool simplifies data entry requirements for continuous simulation

User inputs site impervious/pervious area, impervious connectivity slopes soils etc

Multi-year continuous simulation using EPA SWMM running in background

Spreadsheet tool simplifies data entry requirements for continuous simulation

User inputs site impervious/pervious area, impervious connectivity slopes soils etc

81

impervious connectivity, slopes, soils, etc.

User inputs site location to access pre-processed, long-term meteorological data (MM5)

User inputs hydraulic design criteria (e.g., drawdown curve) for treatment BMPs

impervious connectivity, slopes, soils, etc.

User inputs site location to access pre-processed, long-term meteorological data (MM5)

User inputs hydraulic design criteria (e.g., drawdown curve) for treatment BMPs

Hydrologic Simulation (cont.)Hydrologic Simulation (cont.)

Potential Scenarios Include:Modifications to soil propertiesImpervious area increase or decreaseChange in connectivity

Potential Scenarios Include:Modifications to soil propertiesImpervious area increase or decreaseChange in connectivity

82

g yModification to natural drainage courseRevegetationOptimization of BMP hydrology

g yModification to natural drainage courseRevegetationOptimization of BMP hydrology

Pollutant Load Generation (cont.)Pollutant Load Generation (cont.)

Specific Source 1

Landuse n

Hydrology

SpatiallyDistributed Specific

83

Specific Source 2

Landuse 2

Landuse 1

Pollutant Load Generation

Specific Source n

DistributedSource

Accounting

SourceAccounting

Source Controls Source Controls

Pollutant Load Generation (cont.)Pollutant Load Generation (cont.)

Potential Scenarios Include:Changes in land use categoryChanges in land use conditionImplementation of pollutant source controls

Road shoulder stabilization

Potential Scenarios Include:Changes in land use categoryChanges in land use conditionImplementation of pollutant source controls

Road shoulder stabilization

84

Drainage course stabilizationBMP maintenance

Gully erosionStabilization and revegetation of disturbed areasRoad sand application and recovery

Drainage course stabilizationBMP maintenance

Gully erosionStabilization and revegetation of disturbed areasRoad sand application and recovery

15

Treatment BMP Pollutant Load Reduction (cont.)Treatment BMP Pollutant Load Reduction (cont.)

BMP1

Influent Load = Volume x Influent Conc.

85

To Next BMP or Outfall?

To Next BMP or Outfall?

BMP 1

Treated Load = Treated Volume x BMP 1 Effluent Conc.

Bypassed Load = Bypassed Volume x Influent Conc.

Routing

Treatment BMP Pollutant Load Reduction (cont.)Treatment BMP Pollutant Load Reduction (cont.)

Potential Scenarios Include:Swales, media filters, detention basins, wet ponds, wetlands, and user-defined BMPsUp to three BMPs in series, in parallel, or combination of both

Potential Scenarios Include:Swales, media filters, detention basins, wet ponds, wetlands, and user-defined BMPsUp to three BMPs in series, in parallel, or combination of both

86

or combination of bothInfiltration an evapotranspiration simulated in each BMPSedimentation by particle size

or combination of bothInfiltration an evapotranspiration simulated in each BMPSedimentation by particle size

SummarySummary

Hydrologic Simulation

User Input

87

Pollutant Load Generation

Pollutant Load Reduction

Pollutant Load

CCSD#1 Rules & Regs for Stormwater QualityCCSD#1 Rules & Regs for Stormwater QualityCCSD#1 Rules & Regs for Stormwater QualityCCSD#1 Rules & Regs for Stormwater Quality

Stormwater treatment requiredVegetated treatment required for all new development (swales, filter strips, wetlands, wet ponds, and detention basins)Recommendation: Allow additional types: bioretention, green roofs, planters, etc.

Proprietary mechanical devices are acceptable with pre-approval

88

ppRecommendation: Limit use where surface facilities are feasible.

Infiltration required for new development (½-inch in 24-hrs). Treatment required (prior or concurrent with infiltration).

Often implemented in conjunction with treatment, e.g. dead pool within detention basins.Recommendation: Allow compliance through hydrologic source control measures such as roof runoff disconnects, permeable pavement, stormwater planters, etc.

Burgundy Rose DevelopmentBurgundy Rose DevelopmentBurgundy Rose DevelopmentBurgundy Rose Development

150 lots SFR on 35 acres52% impervious coverModerate to

150 lots SFR on 35 acres52% impervious coverModerate to

89

Moderate to steep slopesSoils –Cascade Silt Loam

Moderate to steep slopesSoils –Cascade Silt Loam

Design Standards for WQ facilitiesDesign Standards for WQ facilitiesDesign Standards for WQ facilitiesDesign Standards for WQ facilities

WQ Rainfall Depth – 2/3 of 2-yr 24 hr post-development storm (2.6 inches). WQ rainfall = 1.74 inches.

90%

100%

h

Design Depth

90

0%

10%

20%

30%

40%

50%

60%

70%

80%

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3

Storm Depth (in)

Perc

ent o

f Sto

rms

<= D

epth

About 65% of storms are less than ½ inch.

16

WQ Design Standards WQ Design Standards –– Burgundy RoseBurgundy RoseWQ Design Standards WQ Design Standards –– Burgundy RoseBurgundy Rose

WQ Treatment Volume: Sized by SBUH in accordance with regs. Only considered on-site runoff.

WQ treatment volume = 130,000 ft3

WQ Discharge Rate (based on Regs):Average Rate calculated as: 130,000 ft3 / 24 hrs = 1.5 cfsWQ orifice sized for this outlet for entire 130,000 ft3

91

WQ orifice sized for this outlet for entire 130,000 ft

Detention Basin Sizing: Basin was sized by routing “WQ event” through the basin.

i.e. Pond was draining at the average 1.5 cfs while filling. Therefore 130,000 ft3 could be processed without overtopping weir with small basin size As-built WQ pool volume = 35,000 ft3

Continuous Simulation Analyses to Assess PerformanceContinuous Simulation Analyses to Assess PerformanceContinuous Simulation Analyses to Assess PerformanceContinuous Simulation Analyses to Assess Performance

Hydrologic Processes SWMM Representation

precipitation

evapotranspirationPrecipitation

(hourly)

ETET

Impervious areas(runoff block)

Precipitation (hourly)

Pervious areas(runoff block)

Disconnected runoff

Hydrologic Processes SWMM Representation

precipitation

evapotranspiration

precipitation

evapotranspirationPrecipitation

(hourly)

ETET




Disconnected runoffPrecipitation (hourly)

ETET




Disconnected runoff

92

runoff

infiltration

BMP

Development areaSurface runoff hydrograph

ETInfiltration

GW recharge

Stormwater runoff

hydrograph

BMP (Storage treatment block)

Outflow hydrograph (to receiving waters)

Base flows (not considered for Burgundy Rose)

runoff

infiltration

BMP

Development area

runoff

infiltration

BMP

Development areaSurface runoff hydrograph

ETInfiltration

GW recharge

Stormwater runoff

hydrograph




Surface runoff hydrograph

ETInfiltration

GW recharge

Stormwater runoff

hydrograph




Stage Discharge Relationships for the Burgundy Rose Detention Basin

Stage Discharge Relationships for the Burgundy Rose Detention Basin

24-hr drain time

1.6

2.0

fs)

As-built24-hr single outlet24-hr riser outlet

48-hr drain time

1.6

2.0

fs)

48-hr single outlet48-hr riser outlet

93

0.0

0.4

0.8

1.2

0 0.5 1 1.5 2 2.5 3 3.5 4

Depth (ft)

Dis

char

ge (c

f

0.0

0.4

0.8

1.2

0 0.5 1 1.5 2 2.5 3 3.5 4

Depth (ft)

Dis

char

ge (c

f

Simulated Detention Simulated Detention Basin Influent/Effluent Basin Influent/Effluent

HydrographsHydrographs

Simulated Detention Simulated Detention Basin Influent/Effluent Basin Influent/Effluent

HydrographsHydrographs

As-bulit

0

0.5

1

1.5

2

30/2

000

/6/2

000

13/2

000

20/2

000

27/2

000

Flow

(cfs

)Inflow Outflow

94

1/3 2 2/1

2/2

2/2

48-hr drain time

0

0.5

1

1.5

2

1/30

/200

0

2/6/

2000

2/13

/200

0

2/20

/200

0

2/27

/200

0

Flow

(cfs

)

InflowPerforated Riser OutflowSingle orfice Outflow

Average Detention Time Estimates from SWMM ModelAverage Detention Time Estimates from SWMM ModelAverage Detention Time Estimates from SWMM ModelAverage Detention Time Estimates from SWMM Model

Average detention time in WQ pool (hrs)

Basin design As-built Single

orifice outlet Riser outlet

95

24-hr drain time 1.3 6.4 18.2

36-hr drain time 11.6 23.2



Percent Sediment Removed by Particle RangePercent Sediment Removed by Particle RangePercent Sediment Removed by Particle RangePercent Sediment Removed by Particle Range

50%

60%

70%

80%

90%

100%

Trea

ted

As-Built24-hr single orfice24-hr riser outlet

96

0%

10%

20%

30%

40%

50%

2 to 4 4 to 8 8 to 12 12 to 24 24 to 48 48 to 100

Particle Size Range (um)

Perc

ent

17

Effect of Design Rainfall Depth and Drawdown Time on Sediment Effect of Design Rainfall Depth and Drawdown Time on Sediment Trapping Efficiency and Percent CaptureTrapping Efficiency and Percent Capture

Effect of Design Rainfall Depth and Drawdown Time on Sediment Effect of Design Rainfall Depth and Drawdown Time on Sediment Trapping Efficiency and Percent CaptureTrapping Efficiency and Percent Capture

Basin Size Vs Particle Removal Performance24-hours

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%%

Par

ticle

Tre

ated

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

% R

unof

f Cap

ture

32-64 Particle Size (um)16-32 Particle Size (um)

%Runoff Capture

97

0%0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Design Storm Depth (in)

0%


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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Design Storm Depth (in)

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le T

reat

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16-32 Particle Size (um)%Runoff Capture


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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Design Storm Depth (in)

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32-64 Particle Size (um)16-32 Particle Size (um)

%Runoff Capture

Factoring in Source ControlsFactoring in Source ControlsFactoring in Source ControlsFactoring in Source Controls

Percent Capture without Roof Disconnect

30%

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rcen

t Vol

ume

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ture

24-hr detention period

Percent Capture with Roof Disconnect

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t Vol

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98

0%

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0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

Design Storm (in)

Pe 48-hr detention period72-hr detention period

0%

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Per 48-hr detention period


Assuming that 90 percent capture efficiency provides the best sediment trapping efficiency, recommended design storm is:

0.8 to 1.0 inches (for the three drain times) when roof top runoff is directly connected. 0.5 to 0.8 inches when roof runoff is disconnected

Assuming that 90 percent capture efficiency provides the best sediment trapping efficiency, recommended design storm is:

0.8 to 1.0 inches (for the three drain times) when roof top runoff is directly connected. 0.5 to 0.8 inches when roof runoff is disconnected

Design Standards Recommendations:Design Standards Recommendations:Design Standards Recommendations:Design Standards Recommendations:

Continue to stress vegetated treatment systems. Consider allowing additional types.

Discourage use of underground mechanical systems.

Consider hydrologic source controls for compliance with infiltration requirements

Size WQ pools to be equivalent with design volume

Continue to stress vegetated treatment systems. Consider allowing additional types.

Discourage use of underground mechanical systems.

Consider hydrologic source controls for compliance with infiltration requirements

Size WQ pools to be equivalent with design volume

99

Recommended design storm depth = 0.9 inches.

Recommended draw-down time = 48 hrs, using a perforated riser outlet sized to release top half in 16 hrs and bottom half in 32 hrs.

Size flow based BMPs (swales) using a design rainfall intensity. Suggest 2x 85th percentile or about runoff from 0.15 inches per hour.

Recommended design storm depth = 0.9 inches.

Recommended draw-down time = 48 hrs, using a perforated riser outlet sized to release top half in 16 hrs and bottom half in 32 hrs.

Size flow based BMPs (swales) using a design rainfall intensity. Suggest 2x 85th percentile or about runoff from 0.15 inches per hour.

Stormwater “More Sustainable” Strategy

Stormwater “More Sustainable” Strategy

1. Hydrological Source Control

2. Pollutant Source Control

3 O it T t t l t th

1. Hydrological Source Control

2. Pollutant Source Control

3 O it T t t l t th

100

3. On-site Treatment, close to the source

4. Regional Treatment Systems

5. Stream Stabilization/Function Restoration

Probably need to do all (no silver bullets!)

3. On-site Treatment, close to the source

4. Regional Treatment Systems

5. Stream Stabilization/Function Restoration

Probably need to do all (no silver bullets!)

Design for 25 – Year Shopping Event?Design for 25 – Year Shopping Event?

101

Does the Fire Does the Fire Department Really Department Really Need Huge Fire Need Huge Fire Trucks?Trucks?

Source Controls -Inert Building MaterialsSource Controls -Inert Building Materials

♦Building Materials with High Pollution Potential− Copper/Zinc Roofs− Copper/Zinc Downspouts− Treated wood− Asphalts− Zinc strips

♦Alternatives:− Coated Steel Roofs (Copper Color)− Coated Aluminum downspouts

102

downspouts− Allow moss to grow

♦Results:− Playa Vista, Irvine Company, Rancho MV are including prohibitions on specific exposed materials

18

Applied Materials - Fertilizers and Pesticides

Applied Materials - Fertilizers and Pesticides

CCRs which specify landscaping types and vegetation maintenance procedures to minimize the potential for pollution

Specifically for Stormwater Planters

CCRs which specify landscaping types and vegetation maintenance procedures to minimize the potential for pollution

Specifically for Stormwater Planters

103

Specifically for Stormwater PlantersPlant palette will be those that do not require significant fertilizers and pesticides (minimize)

Any pesticide applications must be completed by licensed applicators

Soils and amendments also selected to minimize release of nutrients

Specifically for Stormwater PlantersPlant palette will be those that do not require significant fertilizers and pesticides (minimize)

Any pesticide applications must be completed by licensed applicators

Soils and amendments also selected to minimize release of nutrients

Pre-Development HydrologyPre-Development Hydrology

Evapotranspiration (ET) is often upwards of 70 to almost 90 percent of precipitationPre-development deep infiltration is often very smallRunoff is also small (except this last few weeks!)

Evapotranspiration (ET) is often upwards of 70 to almost 90 percent of precipitationPre-development deep infiltration is often very smallRunoff is also small (except this last few weeks!)

104

Importance of “Managing the ET Sponge”Loss of CanopyLoss of “Duff” layer

Reliance on Infiltration in many cases results in increased infiltration

Importance of “Managing the ET Sponge”Loss of CanopyLoss of “Duff” layer

Reliance on Infiltration in many cases results in increased infiltration

BMP PrioritiesBMP Priorities

More focus on maximizing “hydrological More focus on maximizing “hydrological source control”:source control”:

Evapotranspiration firstEvapotranspiration firstInfiltration nextInfiltration next

105

Pollutant Source ControlPollutant Source ControlTreatmentTreatment

City and County of Honolulu-Factors Considered in Selecting Standards

Reduce pollutants to “Maximum Extent Practicable”Pollutants of concern - NPDES SamplingWater Quality Limited water bodiesRainfall - Point of diminishing returnRainfall/runoff analysis to ascertain what proposed

106

Rainfall/runoff analysis to ascertain what proposed requirements would achieve for different BMP typesWe have a lot more to learn about stormwater BMP effectivenessHawaii development site conditionsThis is an initial start

20002000

Technical ApproachesTechnical Approaches

Setting water quality facility sizing requirements

Assess rainfall, runoff, and BMP functioning to ascertain what will be achieved

Setting water quality facility sizing requirements

Assess rainfall, runoff, and BMP functioning to ascertain what will be achieved

107

Volume vs. flow-through BMPs need separate approachesMake requirements simpleEncourage “treatment trains”Recognize that standards will need to evolve as we learn more

Volume vs. flow-through BMPs need separate approachesMake requirements simpleEncourage “treatment trains”Recognize that standards will need to evolve as we learn more

Example Site Analyses Approach/Results - Simulation of

the Results of Requirements Performed

Selected Actual Site ExamplesD l d Sit R d i f h i i

108

Developed Site Re-designs for each sizing requirementPredicted Results - Hydrologic, Hydraulic and Pollutant Removal PerformanceDeveloped Cost Implications/EvaluationAssessed Land use/aesthetics

19

COMPARISON OF ON-SITE WATER QUALITY DESIGN STORMS FOR TYPICAL COMMERCIAL

OFFICE BUILDING DEVELOPMENT

COMPARISON OF ON-SITE WATER QUALITY DESIGN STORMS FOR TYPICAL COMMERCIAL

OFFICE BUILDING DEVELOPMENT

WaterQuality

Water Quality Site Design Estimated Annual Pollutant Loadof Total Suspended Solids (TSS)

EstimatedReduction

DesignStorm

Potential WaterQuality BMP

Estimated Percentage ofAnnual Runoff Volume

Treated

Cost Implications1

TraditionalSite

Site WithWater

QualityPercent

Reduction

in AnnualPollutant

Load of TotalRainfallAnalysis

SWMMModeling

Capital Maintenance Design Facilities Copper (Cu)

0 30 i /h t t d l 65% $25 000 $3 000 710 lb 327 lb 54% 45%

109

0.30 in/hr vegetated swales(2’ - 4.5’ bottom width)

65% na $25,000Reduced Cost

$3,000 710 lbsper year

327 lbsper year

54% 45%

0.40 in/hr vegetated swales(2’ - 6.5’ bottom width)



300 lbsper year

58% 50%

0.55 in/hr vegetated swales(2’ - 9’ bottom width)



240 lbsper year

66% 56%

NOTES:1. “Cost Implications” based on comparison to construction and maintenance of conventional storm drainage system.2. Pollutant loads based on stormwater quality data collected on Oahu between 1992 and 1996.3. Pollutant removal based on performance data reported in Portland Stormwater Quality Facilities Design Guidance Manual.

Detention Based Water Quality Control -Design Sizing/Detention Time

Detention Based Water Quality Control -Design Sizing/Detention Time

Figure 1Required Water Quality Design Volume for Detention

Based Systems

2000250030003500

Wat

er Q

ualit

yum

e (c

ubic

ac

re)

Figure 2: Required Average Outlet Discharge Rates for Extended Detention Volume

0.030

0.035

0.040

0.045

Rat

e (c

ubic

p

er a

cre)

full to half fullhalf full to empty

110

0500

10001500

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Impervious Area Percentage

Req

uire

d W

Des

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Vol

feet

/a

0.000

0.005

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0.020

0.025

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Storage Volume Per Acre (cubic feet/acre)

Ave

rage

Out

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feet

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ond p y

Approach Approach --Provided simple charts for sizing of facilitiesProvided simple charts for sizing of facilities

RecommendationsRecommendations

Communities should commit sufficient resources into developing design standards for stormwater that actually “work”

Communities should commit sufficient resources into developing design standards for stormwater that actually “work”

111

“work”

BMP Manuals need to be significantly updated to emphasize unit processes based BMP Selection and Design

“work”

BMP Manuals need to be significantly updated to emphasize unit processes based BMP Selection and Design

BMP PrioritiesBMP PrioritiesMore focus on maximizing “hydrological More focus on maximizing “hydrological source control”:source control”:

Maximize Evapotranspiration firstMaximize Evapotranspiration first

Infiltration nextInfiltration next

112

Pollutant Source ControlPollutant Source Control

TreatmentTreatment

Traditional vs. Integrated Landscape Stormwater Design Approaches – Getting Costs “Right”

Traditional vs. Integrated Landscape Stormwater Design Approaches – Getting Costs “Right”

113

BMP Costs vs. Change in Project Costs

114

eric strecker2

Technology

design eric

stormwater bmp selection

knowledge of performance

long way

size of storm