Etobicoke Exfiltration System: Monitoring and Evaluation. Tim Van Seters Ryerson University July 24, 2015

Transcription

1 Etobicoke Exfiltration System: Monitoring and Evaluation Tim Van Seters Ryerson University July 24, 2015

2 Presentation Outline Summary of Candaras Associates study Summary of SWAMP Study Follow up monitoring in 2013 and 2014 Other exfiltration system designs

3 Performance Assessments Exfiltration system Princess Margaret Blvd Exfiltration system Queen Mary Drive Filtration System on Braecrest Avenue

4

5 Exfiltration and Filtration Systems Exfiltration System Filtration System

6 Etobicoke Exfiltration System

7 Princess Margaret Blvd Site MH 1 MH 2 ISLINGTON AVE. MH 3 MH 4A MH 4 KIPLING AVE. Princess Margaret Blvd. MH 68 MH 6 MH 5 Princess Ann Cres. MH 7 MH 69 MH 70 MH 8 THE KINGSWAY MH 71 MH 72 MH 73 Exfiltration sewer system Conventional storm sewer

8 Princess Margaret Blvd Site Characteristics and System Design 30.5 ha low density residential Clay to clay silt till over silty sand No groundwater interference Design storm was 15 mm, 1 hour AES storm, which was thought to be equivalent to the 90 th percentile event Peak rainfall intensity = 56 mm/h or 4.7 mm/5 minutes

9 Candaras Associates Study Princess Margaret Blvd 2 CATCHBASINS CONNECTED TO MH 1 2 CATCHBASINS CONNECTED TO SEWER PIPE 4 SEALED CATCHBASINS ROAD NATIVE BACKFILL MH 1 COMPACTED TO MH 2 100% SPD TEMPORARY PLUG STORM SEWER 16 mm CLEAR STONE PLUG V-NOTCH WEIR NATIVE BACKFILL COMPACTED TO 100% SPD STORM SEWER 16 mm CLEAR STONE PLUG MH 3 V-NOTCH WEIR NATIVE SOIL DATA LOGGER PERFORATED PVC PIPE (12 mm PERFORATIONS) WRAPPED WITH EXTERNAL 270R OR EQUIVALENT PRESSURE TRANSDUCER SCALE: N.T.S. SOURCE: A.M. CANDARAS ASSOCIATES INC. 1997

10 Candaras Associates Study Princess Margaret Results Date Event Size Peak Inflow Peak Outflow Trench Peak Water Level Upstream Trench Peak Water Level Downstream Water Level at which overflow occurs May 26, mm over 22.5 hours 9.7 L/s 0.3 L/s 0 mm 65 mm 650 mm May 31, mm over 0.5 hours 8.1 L/s 1.5 L/s 0 mm 5 mm 650 mm June 24, mm over 24 hours 2.2 L/s 0.1 L/s 0 mm 3 mm 650 mm Oct 5-6, mm over 18 hours 10 L/s 3.3 L/s 380 mm 500 mm 650 mm

11 SWAMP Study Princess Margaret Monitoring Lay-out AUTOMATIC SAMPLER MH 73 CATCHBASIN CATCHBASIN LEAD MH 72 MH 71 CONVENTIONAL SEWER TO KIPLING AVE. SAMPLER INTAKE V-NOTCH WEIR AREA-VELOCITY PROBE AND DEPTH SENSOR DEPTH SENSOR ACTUATOR GRAVEL TRENCH MAIN SEWER PIPE PERFORATED EXFILTRATION PIPE SCALE: N.T.S.

12 SWAMP Study Princess Margaret Results: No overflows in rain events above 15 mm No overflows in rain events above 15 mm 3 events caused overflow in 1998, no overflow from 2 events > 15 mm 20.2 mm followed by 3.6 mm two days later 14.9 mm followed by 11.9 mm the same day (26.8 mm total) 15.3 mm, high intensity (9.7 mm in 5 minutes) 98% of rainfall runoff infiltrated Mean TSS concentrations in sewer were 164 mg/l and 81 mg/l in summer and winter, respectively

13 SWAMP Study PM Large Event Summary Date Duration 1 Total Depth Maximum Maximum Overflow 5-minute hour MH 72 (min) (mm) (mm) (mm) Oct. 18, ' n/a 14.0 N Nov. 7-8, ' n/a 5.9 N Aug. 15, ' n/a 11.0 N Aug , '97 1, n/a 5.6 N Sep. 10, ' n/a 3.6 N Nov. 1, ' n/a 5.0 N May 10-11, '98 2, N June 11-13, ' N June 13, ' Y June 30, ' Y Sept. 6, ' Y

14 Queen Mary s Drive Site Characteristics and System Design 13.3 ha low density residential Sand and silty sand native soils Roof and foundation drains directly connected to sewer Groundwater at 1.2 m from surface

15 Queen Mary s Drive Site

16 Candaras Associates Study Queen Mary s Drive Study 5 CATCHBASINS CONNECTED TO MH 12 4 CATCHBASINS CONNECTED TO MAIN SEWER ROAD ROAD MH 12 NATIVE BACKFILL COMPACTED TO 100% SPD MH 14 NATIVE BACKFILL COMPACTED TO 100% SPD MH 15 TEMPORARY PLUG STORM SEWER 16 mm CLEAR STONE PLUG V-NOTCH WEIR STORM SEWER PLUG V-NOTCH WEIR 16 mm CLEAR STONE NATIVE SOIL PERFORATED PVC PIPE (12 mm PERFORATIONS) WRAPPED WITH EXTERNAL 270R OR EQUIVALENT DATA LOGGER PRESSURE TRANSDUCER SCALE: N.T.S. SOURCE: A.M. CANDARAS ASSOCIATES INC. 1997

17 Candaras Associates Study Queen Mary s Drive Study Results Date Event Size Peak Inflow Sept 25, mm over 6 hours Peak Outflow Trench Peak Water Level Upstream Trench Peak Water Level Downstream Water Level at which overflow occurs 52 L/s 6.5 L/s 220 mm 180 mm 650 mm Oct. 5-6, mm over 18 hours 17.5 L/s 10 L/s 150 mm 550 mm 650 mm

18 Inconclusive Results of SWAMP EES monitoring Queen Mary s Drive

19 Follow up Monitoring in

20 Princess Margaret Blvd Sewer Inspection

21 Limited maintenance Still infiltrating well after 14 years PM Water Level Drawdown Rate in 1998 and 2013 (MH 72) Water Level (mm) September 6, 1998 July 7, Time after peak (minutes) Storm sewer invert Perforated pipe invert

22 Princess Margaret Blvd Large Event Summary Date Duration 1 Total Depth Maximum 5-minute Overflow MH 72 Overflow MH 71 (hh:mm) (mm) (mm) June 12, : Y Y June 17, : Y Y June 25, : Y Y July 7, : N N July 8, : N N July : N Y August 12, : N Y Sept 2, : N Y Sept 5, : N Y Sept 10, : Y Y Sept 21, : N Y Oct 3, : N Y Nov 24, : N N

23 Queen Mary

24 Queen Mary Sewer Inspection

25 Queen Mary Clean Out

26 Queen Mary Water Level Drawdown Before and After Maintenance Average water level drawdown rate roughly doubled after maintenance Water Level (mm) Before After Time from end of rain (minutes)

27 Queen Mary Large Event Summary 2014 Date Duration 1 Total Depth Maximum 5-minute Overflow (hh:mm) (mm) (mm) June 12, : Y June 17, : Y June 25, : Y July 7, : Y July 8, : Y July : Y August 12, : Y Sept 2, : Y Sept 5, : Y Sept 10, : Y Sept 21, : Y Oct 3, : N Nov 24, : Y

28 General Conclusions PM exfiltration system continues to meet design target Overflows often occurred due to limited through put capacity rather than inadequate trench storage availability Higher density of perforations and/or larger pipes to facilitate rapid conveyance of runoff into trench Improved pre-treatment within the catchbasin or manhole would help reduce clogging of perforated pipes Trench dams preventing flow between trench sections may need further consideration Maintenance frequency variable depending on design and catchment characteristics inspections required every 5 years

29 Other Exfiltration System Designs

30 Exfiltration system, North York

31 Exfiltration system, North York

32 Curbless system with pretreatment through a grass swale Exfiltration Systems, Ottawa After 20 years, and limited maintenance, the system continued to function very well J.F. Sabourin & Associates, 2008

33 Edwards Gardens Before Biofilter system Courtesy: Schollen & Co. Inc.

34 Thank You Tim Van Seters Phone: STEP website: