stormwater management report · 2016-09-19 · tmk consulting engineers 1606005_smr/c 15th august...

TMK CONSULTING ENGINEERS 1606005_SMR/C 15

th August 2016

STORMWATER MANAGEMENT REPORT

PROPOSED DEVELOPMENT 179 GREENHILL ROAD

PARKSIDE SA 5063

prepared for

TRITAN CORPORATION / JPE DESIGN STUDIO

Document Title: TMK External Document Template Document Code: BF022 Revision Code: 01 Issue Date: 20/05/10 Approved by: MCT K:\2016\06\1606005\Civil Drawings and Calcs\Design Calculations and Details\SMR\1606005_SMR_C.docx 2 of 6

TMK Consulting Engineers Level 6, 100 Pirie Street, Adelaide SA 5000

Civil • Structural • Environmental Geotechnical • Mechanical • Electrical Fire • Hydraulics • Lifts • Green ESD

Tel: 08 8238 4100 • Fax: 08 8410 1405 Email: [email protected]

STORMWATER MANAGEMENT REPORT

1606005_SMR/C

Principal: TRITAN CORPORATION Job Number: 1606005

Contractor: T.B.A Development No: T.B.A

Project Title: PROPOSED DEVELOPMENT Date: 15th

August 2016

Site: 179 GREENHILL ROAD, PARKSIDE 5063

This is a Stormwater Management Report giving specific recommendations for construction of the Proposed Development at the above site. This report must be read in conjunction with all listed attachments. Changes to the design or construction must not be made without further written advice from the Engineer. This report is valid for a period of 24 months, based on current standards and regulations, etc. GENERAL NOTES:

1. These calculations are to be read in conjunction with the relevant associated Civil Drawings and / or details. 2. All work is to comply with relevant SAA Standards and Guides.

AS/NZS 3500.3: Part 3 Stormwater Drainage Australian Rainfall and Run-off Volume 8: Urban Stormwater Management Australian Runoff Quality – A Guide to Water Sensitive Urban Design Storm drainage design in small urban catchments: A handbook for Australian practice Water Sensitive Urban Design (WSUD) Engineering Procedure: Stormwater Water Services Association of Australia Code (WSAA).

ATTACHMENTS: Stormwater Management Report

Stormwater Calculations (SW1-SW6) For and on behalf of TMK Consulting Engineers

BENOIT HOPKINS Engineer

Our Ref: 1606005_SMR/C August 2016

STORMWATER MANAGEMENT REPORT 179 GREENHILL ROAD, PARKSIDE

Document Title: Stormwater management report Document Code: Revision Code: Issue Date: Approved by: 3 of 6

A. General

This report details the stormwater management strategies for the proposed development located at 179 Greenhill Road incorporating 1 George Street, Parkside SA, 5063 (Refer Figure 1 – Site Aerial View). The objective of the report is to demonstrate how stormwater runoff would be captured and conveyed from the subject site safely to the receiving drainage network while considering stormwater quality management and the incorporation of Water Sensitive Urban Design (WSUD) elements.

Figure 1 - Site Aerial View (Source: nearmaps.com)




B. Stormwater Drainage OVERVIEW

The site covers an area of approximately 0.42ha with several existing dwellings, paved areas and a bitumen car park accounting for an impervious area of approximately 0.25ha. The site in its current state discharges to existing Council stormwater infrastructure located on George Street. The proposed development would result in an increase of impervious area of approximately 20%. Stormwater from the site would be routed through the proposed conventional underground drainage system comprising of Grated Sumps and PVC Pipes, coupled with the use of WSUD elements including permeable paving, rainwater harvesting, on-site detention storage and a Gross Pollutant Trap (GPT).

The stormwater management report is prepared in accordance with the design criteria listed below:

The stormwater drainage system is designed using Bureau Of Meteorology (BOM) published rainfall Intensity Frequency Duration (IFD) data as a minor / major system to accommodate the 1 in 10 / 1 in 100 year ARI storm events.

The flow rate of stormwater leaving the site shall be designed so that it does not exceed the pre-developed flow rate for both the minor and major rain events.

The total site discharges are modeled as described in Storm Drainage Design in Small Urban Catchments, a handbook for Australian practice by John Argue & Australian Rainfall and Runoff (ARR87),

Book Eight - Urban Stormwater Management. STORMWATER QUANTITY MANAGEMENT

Stormwater runoff from the proposed development will drain into a proposed detention tank designed to control the rate of stormwater leaving the site up to the 1 in 100 year ARI storm event to pre-developed rates, before ultimately discharging to the existing drainage network located adjacent George Street.

PRE-DEVELOPMENT FLOW CALCULATIONS Pre-development flow rates were determined using the Rational Method to calculate the peak flow rates for both the minor 1 in 10 year and major 1 in 100 year ARI storm events. The results are summarized below (refer ‘Appendix A’ for calculations).

Pre-Developed Flow Rates Q10 = 0.037 m

3/sec

Q100 = 0.062 m

3/sec

POST-DEVELOPMENT FLOW CALCULATIONS:

Post-development flow rates were determined using the Rational Method to calculate the stormwater discharge from the site and volume of detention required to limit peak flows to pre-developed rates for both the minor 1 in 10 year and major 1 in 100 year ARI storm events. The results are summarized below (refer to ‘Appendix A’ for

calculations).

Minor Storm (Q10): Maximum flow into detention tank: 0.051 m

3/sec

Maximum flow into existing George Street network: 0.037 m

3/sec

Total detention volume (minimum): 13 m

3

Major Storm (Q100): Maximum flow into proposed detention basin: 0.085 m

3/sec

Maximum flow into existing George Street network: 0.062 m

3/sec.

Total detention volume (maximum): 27 m

3




The post-development stormwater calculations demonstrate that the proposed stormwater detention tank will have sufficient capacity to restrict post-development stormwater flow rates to the pre-development stormwater rates for both the minor 1 in 10 year and major 1 in 100 year ARI storm events.

C. Stormwater Quality Management

The key strategies planned to manage the quality of stormwater discharged from the proposed site include the use of a number of WSUD elements including permeable paving allowing for ground water recharge, on-site detention storage to reduce peak flow rates, rainwater tank for irrigation and a Gross Pollutant Trap (GPT) to ensure water quality improvement targets are achieved. The stormwater treatment objectives for this development, as listed below are to remove the following percentages of pollutants from the annual urban load;

80% reduction of Total Suspended Solids (TSS) from a typical urban annual pollutant load.

45% reduction of Total Phosphorus (TP) from a typical urban annual pollutant load.

45% reduction of Total Nitrogen (TN) from a typical urban annual pollutant load.

99% reduction of litter and Gross Pollutants (GP) from a typical urban annual pollutant load.

Model for Urban Stormwater Improvement Conceptualisation (MUSIC) was used to simulate the treatment potential of the proposed treatment train for the development. Typical urban pollutant loading generation from the Guidelines for Pollutant Export Modeling in MUSIC User Guide has been used to simulate developed conditions.

An Ecosol RSF 4300 GPT was modeled as per the manufacturer specification with treatment effectiveness of 99% reduction of GP, 80% reduction of TSS and 45% reduction of TP and TN for the range of treatable flow.

The results of MUSIC modeling (refer Table 1 – MUSIC Results) obtained indicate that the proposed treatment train meets the treatment objectives and will mitigate the impacts of the proposed development on water quality.

Table 1 - MUSIC Results

D. Garden Irrigation

A portion of the building roof stormwater is proposed to be harvested for collection and reticulated to the garden / landscape areas on the ground level. An optional alternative, whilst not a mandatory requirement is a green water efficient option in line with current initiatives. Used correctly, rainwater tanks are an effective way to take the pressure off our limited water resources, and at the same time help manage stormwater run-off.

A rainwater tank size in the order of 20,000 Litres is proposed, connected to a minimum of 150m2 roof area,

which relates to a potential approximate annual capture volume of 75,000 Litres.

The rainwater is to be reticulated to the landscaped areas, via a pressurised pump-set.

The rainwater system is to be inter-connected to the town mains supply via an automatic controller, to enable town mains supply to be used when rainwater tank levels are low.




APPENDIX A

Stormwater Calculations

Ref.: 1606005

Date: 12-Aug-16

Design: RP

Page: SW1

STORMWATER CALCULATIONS - DETERMINATION OF DETENTION TANK SIZES

Design Storm Intensity Table (mm/hr) - (from http://www.bom.gov.au/cgi-bin/hydro/has/CDIRSWebBasic)

STORM LOCATION Latitude 34°59'S; Longitude 138°44'E

Adelaide

DURATION 1 2 5 10 20 50 100

5 mins 52.60 69.00 89.40 104.00 123.00 151.00 175.00

6 mins 49.10 64.50 83.50 96.70 115.00 141.00 163.00

10 mins 39.80 52.00 66.90 77.10 91.30 112.00 129.00

20 mins 28.30 36.80 46.80 53.40 62.80 76.20 87.30

30 mins 22.70 29.40 37.10 42.30 49.50 59.80 68.30

1 hour 15.20 19.70 24.60 27.90 32.50 39.00 44.40

2 hours 10.10 13.00 16.20 18.30 21.20 25.40 28.90

3 hours 7.92 10.20 12.70 14.30 16.60 19.90 22.50

6 hours 5.24 6.75 8.37 9.44 11.00 13.10 14.90

12 hours 3.45 4.44 5.52 6.23 7.23 8.65 9.83

24 hours 2.22 2.86 3.58 4.05 4.72 5.66 6.44

48 hours 1.38 1.78 2.24 2.55 2.98 3.60 4.11

72 hours 1.02 1.32 1.67 1.90 2.23 2.70 3.10

PRE-DEVELOPMENT POST-DEVELOPMENT (*Determine Critical Storm)

Critical Storm Variable

Design ARI (yr) 10 yr Design ARI (yr) 10 yr

Design Duration (min) 10 min Design Duration (min) 15 min

Design Storm Intensity (mm/hr) 77.10 mm/hr Design Storm Intensity (mm/hr) 65.25 mm/hr

Design Parameters C Area % Area Design Parameters C Area % Area

(m2) Detained (m

2) Detained

Roof 0.90 970 0.00 Roof 0.90 2250 100.00 O

Paving 0.75 745 0.00 Paving 0.75 1050 100.00 O

Grass / Landscaping 0.12 2455 0.00 Grass / Landscaping 0.12 870 100.00

Total Area 4170 m2

Total Area 4170 m2

Weighted C (Cw)* 0.41 4170 0.00 Weighted C (Cw)* 0.70 4170 100.00

Summary of Design Flows

Max pre-development flow Qi=S(CiA/3600): Undetained flow, Qu=S(CiAu/3600):

Roof 18.70 L/s Roof 0.00 L/s

Paving 11.97 L/s Paving 0.00 L/s

Grass / Landscaping 6.31 L/s Grass / Landscaping 0.00 L/s

Pre-development flow = 36.97 L/s Design undetained flow = 0.00 L/s

Max. outflows from detention tanks:

Use Max Allowable Flow = 36.97 L/s Site water runoff

Pumped 0.00 L/s

Piped 0.00 L/s

Roof water runoff

Orifice-restricted 36.85 L/s

Total Max. Design Outflow = 36.85 L/s

< 36.97 L/s Allowed :. OK

AVERAGE RETURN INTERVAL (YEARS)

Note: The weighted average value of the runoff coefficient, Cw, includes roof, paving, grassed and landscaped areas of the site.

Adelaide

Document Title: Detention Tank2 Revision Code: 02

Issue Date: 28-Jun-2010 Approved By: GC

1606005_MINOR.xlsm

Checked By: ...........................

Checked Date: ....../......./.........

Ref.: 1606005

Date: 12-Aug-16

Design: RP

Page: SW2

STORMWATER CALCULATIONS - STORMWATER RUN-OFF - ORIFICE-RESTRICTED

Time of Concentration, TC

Design Storm ARI (yr) 10 yr (from page SW1)

Design Storm Duration (mins) 15 mins (from page SW1)

Design Storm Intensity, i 65.25 mm/hr (from page SW1)

=> For run-off calculations, use TC = 13.0 mins <=Duration :. Use Tc = 13 mins.

Design Parameters C Area % Area

(m2) Detained

Roof 0.90 2250 100.00

Paving 0.75 1050 100.00

Grass / Landscaping 0.12 870 0.00

Detained flow, Qd=S(CiAd/3600):

Roof 36.70 L/s

Paving 14.27 L/s

Grass / Landscaping 0.00 L/s

Design detained flow = 50.98 L/s

=> Try the following retention tank design parameters:

Max Allowable outflow from storage = 36.97 L/s (0.00 L/s is still available for outflow)

Number of orifice detention tanks 1 Each tank volume above orifice 27,500 L

Max. head allowed above orifice 1,250 mm => Each Tank Plan Area = 22.00 m2

Outlet coefficient,CO 0.62

Orifice diameter, DO 150 mm => Orifice area, AO =p*(DO/2)^2 17,671 mm2

Graph Time v Flow:

Time InFlow OutFlow

(mins) (L/s) (L/s)

0 0.00 0.00

13 50.98 29.17

15 50.98 33.32

28 0.00 23.81

Max. Calculated Outflow:

Qmaxout = 36.85 L/s

< 36.97 L/s Max. Allowed :. OK

Max. Calculated Head of Water:

H = 602 mm

< 1,250 mm Max. Allowed :. OK

=> Volume of Water To Be Detained: =>USE

V = 13,242 L

i.e. V = 13.24 m3

0.00

50.98 50.98

0.00 0.00

29.17 33.32

23.81

0.00

10.00

20.00

30.00

40.00

50.00

60.00

0 10 20 30

Flo

w Q

, L/s

Time (mins)

InFlow OutFlow



1606005_MINOR.xlsm

Checked By: ...........................

Checked Date: ....../......./.........

Duration Intensity Proposed Inflow Proposed Inflow Orifice Outflow Orifice Outflow Net Storage Ref.: 1606005

(mins) (mm/hr) Rate (L/s) Rate x Duration (L) Rate (L/s) Volume (L) (L)5 104.00 81.3 24,375 -36.97 -6,655 17,720 Date: 12-Aug-16

6 96.70 75.5 27,197 -36.97 -7,986 19,211 7 91.80 71.7 30,122 -36.97 -9,316 20,805 Design: RP

8 86.90 67.9 32,588 -36.97 -10,647 21,940 9 82.00 64.1 34,594 -36.97 -11,978 22,615 Page: SW3

10 77.10 60.2 36,141 -36.97 -13,309 22,831

11 74.73 58.4 38,533 -36.97 -14,640 23,893

12 72.36 56.5 40,703 -36.97 -15,971 24,731 CRITICAL STORM DURATION

13 69.99 54.7 42,650 -36.97 -17,302 25,348 ORIFICE OUTLOW

14 67.62 52.8 44,376 -36.97 -18,633 25,743

15 65.25 51.0 45,879 -36.97 -19,964 25,915 Critical Storm Duration = 15 mins

16 62.88 49.1 47,160 -36.97 -21,295 25,865 Max Storage Volume = 25,915 Litres

17 60.51 47.3 48,219 -36.97 -22,626 25,593

18 58.14 45.4 49,056 -36.97 -23,957 25,099 *Notes: This calculation is used for determining

19 55.77 43.6 49,670 -36.97 -25,287 24,383 the critical storm duration at the location

20 53.40 41.7 50,063 -36.97 -26,618 23,444 shown on the main calculation sheet for the

25 47.85 37.4 56,074 -36.97 -33,273 22,801 case where the maximum outflow rate from

30 42.30 33.0 59,484 -36.97 -39,928 19,557 the tank orifice is as shown in the table.

35 39.90 31.2 65,461 -36.97 -46,582 18,879

40 37.50 29.3 70,313 -36.97 -53,237 17,076 The Net Storage Volume values shown in

45 35.10 27.4 74,039 -36.97 -59,891 14,148 this table are approximate. The design

50 32.70 25.5 76,641 -36.97 -66,546 10,095 uses results obtained from calculations

55 30.30 23.7 78,117 -36.97 -73,201 4,917 where the effects of the change in head

60 27.90 21.8 78,469 -36.97 -79,855 1,386- in the storage tank and the Time of

75 25.50 19.9 89,648 -36.97 -99,819 10,171- Concentration have been included.

90 23.10 18.0 97,453 -36.97 -119,783 22,330-

The critical storm results are shown

highlighted in bold italics.



1606005_MINOR.xlsm

Checked By: ...........................

Checked Date: ....../......./.........

Ref.: 1606005

Date: 12-Aug-16

Design: RP

Page: SW4

STORMWATER CALCULATIONS - DETERMINATION OF DETENTION TANK SIZES

Design Storm Intensity Table (mm/hr) - (from http://www.bom.gov.au/cgi-bin/hydro/has/CDIRSWebBasic)

STORM LOCATION Latitude 34°59'S; Longitude 138°44'E

Adelaide

DURATION 1 2 5 10 20 50 100

5 mins 52.60 69.00 89.40 104.00 123.00 151.00 175.00

6 mins 49.10 64.50 83.50 96.70 115.00 141.00 163.00

10 mins 39.80 52.00 66.90 77.10 91.30 112.00 129.00

20 mins 28.30 36.80 46.80 53.40 62.80 76.20 87.30

30 mins 22.70 29.40 37.10 42.30 49.50 59.80 68.30

1 hour 15.20 19.70 24.60 27.90 32.50 39.00 44.40

2 hours 10.10 13.00 16.20 18.30 21.20 25.40 28.90

3 hours 7.92 10.20 12.70 14.30 16.60 19.90 22.50

6 hours 5.24 6.75 8.37 9.44 11.00 13.10 14.90

12 hours 3.45 4.44 5.52 6.23 7.23 8.65 9.83

24 hours 2.22 2.86 3.58 4.05 4.72 5.66 6.44

48 hours 1.38 1.78 2.24 2.55 2.98 3.60 4.11

72 hours 1.02 1.32 1.67 1.90 2.23 2.70 3.10

PRE-DEVELOPMENT POST-DEVELOPMENT (*Determine Critical Storm)

Critical Storm Variable

Design ARI (yr) 100 yr Design ARI (yr) 100 yr

Design Duration (min) 10 min Design Duration (min) 15 min

Design Storm Intensity (mm/hr) 129.00 mm/hr Design Storm Intensity (mm/hr) 108.15 mm/hr

Design Parameters C Area % Area Design Parameters C Area % Area

(m2) Detained (m

2) Detained

Roof 0.90 970 0.00 Roof 0.90 2250 100.00 O

Paving 0.75 745 0.00 Paving 0.75 1050 100.00 O

Grass / Landscaping 0.12 2455 0.00 Grass / Landscaping 0.12 870 100.00

Total Area 4170 m2

Total Area 4170 m2

Weighted C (Cw)* 0.41 4170 0.00 Weighted C (Cw)* 0.70 4170 100.00

Summary of Design Flows

Max pre-development flow Qi=S(CiA/3600): Undetained flow, Qu=S(CiAu/3600):

Roof 31.28 L/s Roof 0.00 L/s

Paving 20.02 L/s Paving 0.00 L/s

Grass / Landscaping 10.56 L/s Grass / Landscaping 0.00 L/s

Pre-development flow = 61.86 L/s Design undetained flow = 0.00 L/s

Max. outflows from detention tanks:

Use Max Allowable Flow = 61.86 L/s Site water runoff

Pumped 0.00 L/s

Piped 0.00 L/s

Roof water runoff

Orifice-restricted 53.60 L/s

Total Max. Design Outflow = 53.60 L/s

< 61.86 L/s Allowed :. OK

AVERAGE RETURN INTERVAL (YEARS)

Note: The weighted average value of the runoff coefficient, Cw, includes roof, paving, grassed and landscaped areas of the site.

Adelaide



1606005_MAJOR.xlsm

Checked By: ...........................

Checked Date: ....../......./.........

Ref.: 1606005

Date: 12-Aug-16

Design: RP

Page: SW5

STORMWATER CALCULATIONS - STORMWATER RUN-OFF - ORIFICE-RESTRICTED

Time of Concentration, TC

Design Storm ARI (yr) 100 yr (from page SW4)

Design Storm Duration (mins) 15 mins (from page SW4)

Design Storm Intensity, i 108.15 mm/hr (from page SW4)

=> For run-off calculations, use TC = 13.0 mins <=Duration :. Use Tc = 13 mins.

Design Parameters C Area % Area

(m2) Detained

Roof 0.90 2250 100.00

Paving 0.75 1050 100.00

Grass / Landscaping 0.12 870 0.00

Detained flow, Qd=S(CiAd/3600):

Roof 60.83 L/s

Paving 23.66 L/s

Grass / Landscaping 0.00 L/s

Design detained flow = 84.49 L/s

=> Try the following retention tank design parameters:

Max Allowable outflow from storage = 61.86 L/s (0.00 L/s is still available for outflow)

Number of orifice detention tanks 1 Each tank volume above orifice 27,500 L

Max. head allowed above orifice 1,250 mm => Each Tank Plan Area = 22.00 m2

Outlet coefficient,CO 0.62

Orifice diameter, DO 150 mm => Orifice area, AO =p*(DO/2)^2 17,671 mm2

Graph Time v Flow:

Time InFlow OutFlow

(mins) (L/s) (L/s)

0 0.00 0.00

13 84.49 41.10

15 84.49 47.07

28 0.00 42.13

Max. Calculated Outflow:

Qmaxout = 53.60 L/s

< 61.86 L/s Max. Allowed :. OK

Max. Calculated Head of Water:

H = 1,224 mm

< 1,250 mm Max. Allowed :. OK

=> Volume of Water To Be Detained: =>USE

V = 26,925 L

i.e. V = 26.92 m3

0.00

84.49 84.49

0.00 0.00

41.10 47.07

42.13

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

0 10 20 30

Flo

w Q

, L/s

Time (mins)

InFlow OutFlow



1606005_MAJOR.xlsm

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Duration Intensity Proposed Inflow Proposed Inflow Orifice Outflow Orifice Outflow Net Storage Ref.: 1606005

(mins) (mm/hr) Rate (L/s) Rate x Duration (L) Rate (L/s) Volume (L) (L)5 175.00 136.7 41,016 -61.86 -11,135 29,881 Date: 12-Aug-16

6 163.00 127.3 45,844 -61.86 -13,362 32,482 7 154.50 120.7 50,695 -61.86 -15,589 35,107 Design: RP

8 146.00 114.1 54,750 -61.86 -17,816 36,934 9 137.50 107.4 58,008 -61.86 -20,043 37,965 Page: SW6

10 129.00 100.8 60,469 -61.86 -22,270 38,199

11 124.83 97.5 64,365 -61.86 -24,497 39,869

12 120.66 94.3 67,871 -61.86 -26,724 41,148 CRITICAL STORM DURATION

13 116.49 91.0 70,986 -61.86 -28,950 42,036 ORIFICE OUTLOW

14 112.32 87.8 73,710 -61.86 -31,177 42,533

15 108.15 84.5 76,043 -61.86 -33,404 42,639 Critical Storm Duration = 15 mins

16 103.98 81.2 77,985 -61.86 -35,631 42,354 Max Storage Volume = 42,639 Litres

17 99.81 78.0 79,536 -61.86 -37,858 41,678

18 95.64 74.7 80,696 -61.86 -40,085 40,611 *Notes: This calculation is used for determining

19 91.47 71.5 81,465 -61.86 -42,312 39,153 the critical storm duration at the location

20 87.30 68.2 81,844 -61.86 -44,539 37,305 shown on the main calculation sheet for the

25 77.80 60.8 91,172 -61.86 -55,674 35,498 case where the maximum outflow rate from

30 68.30 53.4 96,047 -61.86 -66,809 29,238 the tank orifice is as shown in the table.

35 64.32 50.2 105,520 -61.86 -77,944 27,576

40 60.33 47.1 113,125 -61.86 -89,078 24,047 The Net Storage Volume values shown in

45 56.35 44.0 118,863 -61.86 -100,213 18,650 this table are approximate. The design

50 52.37 40.9 122,734 -61.86 -111,348 11,386 uses results obtained from calculations

55 48.38 37.8 124,738 -61.86 -122,483 2,255 where the effects of the change in head

60 44.40 34.7 124,875 -61.86 -133,618 8,743- in the storage tank and the Time of

75 40.53 31.7 142,471 -61.86 -167,022 24,551- Concentration have been included.

90 36.65 28.6 154,617 -61.86 -200,426 45,809-

The critical storm results are shown

highlighted in bold italics.



1606005_MAJOR.xlsm

Checked By: ...........................

Checked Date: ....../......./.........

stormwater management report · 2016-09-19 · tmk consulting engineers 1606005_smr/c 15th august...

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