Stormwater and LEED Vancouver LEED User s Group May 27, 2005 Craig Kipkie, M.Sc., P.Eng, LEED AP
Outline Sustainable Sites 2 Stormwater credits SSc6.1 SSc6.2 Synergies with other Credits Case Study How it relates to current guidelines Summary and Questions
Sustainable Site Credits - Intent SSc6.1 Rate and Quantity Limit disruption and pollution of natural water flows by managing stormwater runoff SSc6.2 Treatment Limit disruption of natural water flows by eliminating stormwater runoff, increasing on-site infiltration and eliminating contaminates
Sustainable Site Credits - Intent
Sustainable Site Credits - Intent
Natural Conditions Courtesy May, U of W
Developed Conditions Courtesy May, U of W
SSc6.1 Rate and Quantity Requirements If existing imperviousness is less than or equal to 50%, implement a stormwater management plan that prevents the post-development 1.5 year, 24-hour hour peak discharge rate and quantity from exceeding the predevelopment 1.5 year, 24-hour peak discharge rate and quantity.
OR, SSc6.1 Rate and Quantity If existing imperviousness is greater than 50%, implement a stormwater management plan that results in a 25% decrease in the rate and quantity of stormwater runoff
SSc6.1 Potential Technologies and Strategies Rain Gardens Absorbent Soils Pervious Paving Infiltration Swale Intensive/Extensive Green Roofs Infiltration Trenches and Soakaways
SSc6.1 Potential Technologies and Strategies
SSc6.1 Potential Technologies and Strategies
SSc6.1 Potential Technologies and Strategies
SSc6.1 Potential Technologies and Strategies
SSc6.1 Potential Technologies and Strategies
SSc6.1 Potential Technologies and Strategies Resources: http://www.lowimpactdevelopment.org http://www.gvrd gvrd.bc.ca/sewerage/stormwater_reports..ca/sewerage/stormwater_reports.htm
SSc6.1 Calculations Option1 Specified by runoff coefficients for various generic surface types Result: too simplistic Option 2 Stormwater management plan Better Solution: use water balance modelling ling to calculate volumetric reductions on a yearly or multi year basis
SSc6.1 Calculations Water Balance Model (waterbalance( waterbalance.ca) Continuous Hydrological Modelling Must use a method that accurately simulates evaporation and infiltration over an entire year to ensure that the volumetric objectives are being met.
SSc6.1 Calculations Stormwater Volume Reduction 6000 0 5000 5 Cumulative Volume (m 3 ) 4000 3000 2000 75% Impervious Volume = 2851 m 3 100% Impervious Volume = 3802 m 3 10 15 Hourly Rain (mm) 1000 20 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 25 Typical Year Existing Site (100% Impervious) Proposed Building (4520 sf Green Roof) Rain
SSc6.1 Challenges Poor soils Municipal Standards Leaky Condo worries Maintenance/Removal worries Irrigation
5000 LEED 6.1 Credit Analysis - Stormwater Volume Reduction SSc6.1 Challenges 0 4500 4000 5 Cumulative Volume (m 3 ) 3500 3000 2500 2000 1500 75% 100% 10 68% 15 0% Hourly Rain (mm) 1000 20 500 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Typical Year Existing Site (100% Impervious) Proposed Building Natural Conditions Proposed Building with Irrigation (May to Aug) Rain 25
SSc6.2 Treatment Requirements Construct site stormwater treatment systems designed to remove 80% of the average annual post-development TSS and 40% of the average annual post-development total phosphorus based on average annual loadings for all storms less than or equal to the 2-2 year, 24-hour storm.
SSc6.2 Treatment 2-year, 24-hour storm White Rock Vancouver North Vancouver Abbotsford Victoria Kelowna 49 mm 50 mm 120 mm 56 mm 56 mm 23 mm
SSc6.2 Potential Technologies and Strategies Wetlands Bio-swales Vegetated Swales Pervious Pavements Implementing BMPs outlined in Chapter 4, Part 2 (Urban Runoff) of the US EPA s Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters, Jan 1993
SSc6.2 Potential Technologies Removal Efficiencies and Strategies Strategy Infiltration Trench Grass Swale Wetland Oil/Grit Separator Porous Pavement TSS % 50-100 (75) 0-100 (60) 50-100 (85) 0-90 (55) 80-95 (80) TP % 50-100 (65) 0-100 (20) 10-85 (45) 5-10 (5) 60-90 (65)
SSc6.2 Potential Technologies and Strategies
SSc6.2 Potential Technologies and Strategies
SSc6.2 Calculations TSS settling rates can be calculated or published removal efficiencies can be used. TP relies on removal efficiencies found in the literature.
SSc6.2 Challenges Site constraints Variable treatment efficiencies Depends on incoming loadings Irreducible Pollutant Concentrations
Synergies SSc7.1 Heat Island (non roof) Pervious Paving SSc7.2 Heat Island (roof) Green Roofs WEc1.1, WEc1.2, WEc2.1 WEc3.1, WEc3.2 Stormwater harvesting
Synergies SE FALSE CREEK DEVELOPMENT: SWM OPTION 2 5,000 0 4,500 20 Active Storage Volume (m 3 ) 4,000 3,500 3,000 2,500 2,000 1,500 1,000 Based on a preliminary storage tank sizing of 350 L per capita (ie. 4200 m 3 total for site) indicates that the tanks are empty and potatable water is being used 40 60 80 100 120 140 160 24-Hour Rainfall Volume (mm) 500 180 0 200 Jan 01 Jan 31 Mar 02 Apr 01 May 01 May 31 Jun 30 Jul 30 Aug 29 Sep 28 Oct 28 Nov 27 Dec 27 Date Net Storage Volume for site
Case Study Silva Building North Vancouver High-rise Residential building Redevelopment of a parking lot and commercial building (100% impervious)
Silva Building North Vancouver Developer: West Coast Projects LEED Project Manager: resource Rethinking Building Landscape Architect: Eckford and Associates
Silva Building North Vancouver SSc6.1 Rate and Quantity
Silva Building North Vancouver SSc6.1 Rate and Quantity
Silva Building North Vancouver SSc6.1 Calculations Second Floor Landscaping Area at 10"depth - 1900 sq.ft. Area at 18" depth - 1150 sq.ft. Area at 24" depth - 1250 sq.ft. Top Floor Roof tar and gravel (min 30 mm) Second Floor Patio stones on pea gravel
Silva Building North Vancouver Hydrologic Model Evapotranspiration ET Rainfall Model tracks soil moisture fluctuation Soil Saturation Field Capacity Wilting Point Runoff when soil is saturated Infiltration rate is a function of soil moisture (limited by hydraulic conductivities)
Silva Building North Vancouver
Silva Building North Vancouver
Silva Building North Vancouver
Silva Building North Vancouver
Silva Building North Vancouver
Silva Building North Vancouver SSc6.2 Treatment Site Constraints Low Contaminant Loadings
BC Stormwater Guidelines Federal Criteria (Fisheries and Oceans Canada) Capture Criteria (6-month - 24 hour) Flow Criteria (6-month, 2-year, 2 5-year 5 24 hour) Water Quality Criteria (not as strict as LEED) Provincial Criteria (Ministry of Water, Land and Air Protection) Capture Criteria (50% Mean Annual Rainfall) Detention Criteria (6-month, Mean Annual Rainfall or 2-year) 2 Flood Criteria (100-year)
Summary Use water balance/hydrologic modelling to calculate SSc6.1. SSc6.2 is more difficult to obtain and is site dependent. There are synergies with other credits. Following current Provincial and DFO will meet SSc6.1.
Summary Presentation will be posted at www.kwl.ca Email ckipkie@kwl.ca