Integrated. Management

Transcription

1 Integrated Rainwater Management

2 Fort Langley: Birthplace of Sustainability?

3 Fort Langley: Birthplace of Sustainability? Water supply from a local well On-site wastewater treatment Nearly 100 per cent infiltration Amenities within walking distance Vibrant downtown Mix of housing types

4 Integrated Rainwater Management in the Township The Vision: To maintain the natural hydrologic balance while protecting public safety and property.

5 Rainwater Management: Context Growing population Currently 100,000 residents Could reach 150, by 2020 Strong agricultural base Heavily reliant on groundwater for our water supply

6 Rainwater Management: Context Langley is home to over 1400 Langley is home to over 1400 kilometers of watercourses!

7 A Brief History of Local Rainwater Management 1980 s detention ponds constructed in Walnut Grove Early 90 s Township hired its first drainage engineer Late 90 s detention ponds evolved to include water quality treatment

8 A Brief History of Local Rainwater Management

9 A Brief History of Local Rainwater Early 2000 s: Management East Clayton Development eop e GVRD s Integrated Stormwater Management Plan Template First watercourse classification map complete

10 Routley: A First Step Towards Water Balance

11 Routley: A First Step Towards Water Balance Neighbourhood h servicing plan completed in 2000 Fisheries concerns! Yellow-coded ditches Needed compensation

12 Routley: A First Step Towards Water Balance Key features of drainage system: Infiltration chambers Top soil depth of 300 mm Greenway swales Greenway swales with gravel beds

13 Routley Monitoring Program Initiated in 2005 Objective was to monitor the performance of on-lot infiltration galleries, greenway swales, and baseflow diversions

14 Routley: Early Results City of Surre ey 68 Ave Routley Langley Meadows 200 St Monitoring in 2005 showed that runoff from Routley was on average half of that from Langley Meadows

15 Routley Monitoring Routley Monitoring Results Normalized Runoff Volume (m3/ha a) Routley Langley Meadows Mar-05 Apr-05 May-05 Jun-05 Jul-05 Aug-05 Sep-05 Oct-05

16 Moving Forward on Rainwater Management By 2003: Completed Water Resources Management Strategy 20 year action plan for both groundwater and surface water Completed Yorkson Creek Water Resources Plan

17 Yorkson Creek Water Resources Plan

18 Yorkson Lowlands

19 Infiltration Challenges Clayey soils to a depth of ~ 30m Very low infiltration rate < 1mm/hr Compact lot development

20 Infiltration Challenges Shallow infiltration was first considered 15 m 2 infiltration facility would still not achieve predevelopment target!

21 Infiltration Challenges Two test t wells were drilled d to depths of 40 m and 47 m Recharge rate was 40 L/s Several orders of magnitude greater infiltration than shallow soils

22 Next Step: Modelling 37 years of data were used for continuous simulation The goal: maintain the total predevelopment runoff volume The use of a single deep well met the target

23 Identifying and Addressing Concerns Impact to groundwater quality was the primary concern Legislation in BC Water Act Drinking Water Act Waste Management Act Literature review of N. American usage of deep infiltration Waterloo, ON Washington State

24 Identifying and Addressing Concerns

25 Identifying and Addressing Concerns Two-year travel time was mapped Private wells were identified Recharge limited to roofs and perimeter drains Multi-barrier approach

26 The Yorkson Infiltration System 300 mm top soil blanket Inert roof material Roof drains to a sand filter Roofs and perimeter drains collected into a third pipe

27 Yorkson Infiltration System Third pipes connects to a central sand filter Overflow from wells goes to pond UV filter may be required

28 Yorkson Monitoring Monitoring throughout third pipe Quantity and quality

29 Yorkson Monitoring

30 Northeast Gordon Estates: Green Streets

31 Northeast Gordon Estates: Green Streets Poor infiltration ti again! Significant fisheries value in some of the roadside ditches Downstream erosion issues

32 Northeast Gordon Estates: Green Streets Plan was to distribute infiltration across the neighbourhood: 450 mm top soil blanket soil moisture reservoir equivalent to 65 mm, or a 2 year 24 hour storm Green Streetst Flat concrete curb Vegetated swale with permeable substrate Overflow to storm sewer

33 Routley: A First Step Towards Water Balance

34 Northeast Gordon Estates: Green Streets Neighbourhood is serviced by wet detention ti ponds for the 2, 5 and 100 years flows

35 Lessons Learned Top soil blanket appears to be very effective Sediment control is critical Homeowner education and buy-in is key to long-term success

36 Where Do We Go Next? Yorkson Neighbourhood is being replanned Stormwater planning based on continuous simulation water balance approach Subdivision development criteria currently being updated Bertrand Creek ISMP