Moving from Pilots to a Program: Seattle s Green Infrastructure Program: September 20, 2012
Overview Brief History: Getting Started to Now GSI Program: What s Working? GSI Program: What needs Improvement? GSI Program: What s new?
The Beginning SEA Streets, Seattle Portland
Porous Pavement High Point
Growing the Program: Building GSI Experience and Knowledge Project SEA Street #1 Carkeek Cascade Broadview Natural Drainage System Pinehurst Natural Drainage System High Point Thornton Creek Water Quality Project Ballard Roadside Rain Gardens Swale on Yale Project Drainage Area 2 acres 28 acres 32 acres 49 acres 129 acres 660 acres 3 acres 435 acres
GSI is a viable tool in the retrofit toolbox for multiple various business areas
Creek Goals
CSO Reduction Goals
Water Quality Improvement Goals
GSI Projects Primary Driver Project Water Quality Flow SEA Street #1 Carkeek Cascade @ 110th Broadview NDS Pinehurst NDS High Point Thornton Creek Water Quality Project (primary biofiltration) Ballard Roadside Rain Gardens (2-year) maximize (1-2 year) (1-2 year) Delay (6-month storm) (1 year) Swale on Yale (primary biofiltration) For systems designed for Flow control, you still get WQ treatment
Cost Effectiveness(NPV) based on TSS Removal
What s Working?
Seattle s Stormwater Code Requires GSI
Modeling and pre-sizing 35% 30% 25% 20% 15% 10% 5% 26 sf 50 sf 74 sf Native soil Infiltration rate (in /hr) 0.25" 1" 0% 25-year LOS creek protection (2-yr to pasture). 98.6% volume infiltration CSO reduction. 95% volume infiltration water quality. 91% volume infiltration water quality (w/ underdrain)
Pre-approved approaches
Voluntary Installations - RainWise SPU RainWise Program Voluntary Incentive/rebate system on Private Property $3.5/sf Mitigated 2 Practices: Residential Rain Gardens Cisterns Overflow to street or side sewer (next adding trees & greenroofs)
RainWise 2012 Incentives 12,000 residences Eligible Feasibility analysis estimated participation (due to technical and interest): 12% What we are finding: Higher % of roof area captured on a given sites roof than anticipated
RainWise Basins, Planned
RainWise www.rainwise.seattle.gov
Regulatory and NGO support
What s Needs Improvement?
Ballard Roadside Rain Gardens Pilot Lessons Learned
Reevaluate safety standards
GSI O&M Procedures and cost Efficiencies Frequency Year 1 Year 2 and 3 Year 4-100 Site Maintenance Weekly Every 2 weeks Every 2 weeks Watering Weekly Weekly None Cost/sq.ft. of landscape area $2.86-$3.98 $2.74-$3.07 $0.60-$1.40 Typical Block $6K-$9K $6K-$7K $1K-$3K Per acre of landscaped area Seattle s footprint of GSI for CSO (8 acres) $125K-$174K $119K-$134K $26K-$61K $1.2K-$1.4M $944K-$1.3M $207K-$603K
Policy Support: Is natural hydrology a supportive objective?
Natural Hydrology performance target =?
Need to move project planning beyond the silo and Integrating Multiple benefits Spot flooding SSOs Sidewalks Transportation Action Agenda Climate Action Plan 2020 agenda
Integrating Multiple objectives
Quantifying the Value of GSI Many benefits beyond better water quality New small-business opportunities; Flexible responses to adapt to climate change; Groundwater recharge; Improved neighborhood streetscapes Opportunity for residents and businesses to help through actions
Green Infrastructure Benefits go beyond the primary project goal 1.5 MG CV reduction 7.6 Acres of Rain Gardens 40+ MG stormwater prevented from entering our treatment plants, system and pumps
Green Infrastructure has potential to add Resiliency Against Impacts of Climate Change Potential Climate Change Represented by 6% increase in precipitation Climate Change Model 135 conduits completely surcharged 24% increase over Existing Conditions 105.83 hours cumulative surcharge 61% increase over Existing Conditions Climate Change Model with GSI 65% and 69% decrease in potential impacts of climate change in extent and duration of surcharging, respectively Surcharged Pipes in Climate Change Model
How to compare Value not just Cost
Green Infrastructure Valuation
6 5 4 Design smarter more work to optimize effectiveness of GSI for CSO Reduction Infrequent/Short Duration Overflows 0.26 MG Overflow w/o GSI 0.004 MG Overflow w/ 30% Impervious Mitigated ==> 0.32 gal/sf mitigated 3 2 Frequent/Long Duration Overflows 0.82 MG Overflow w/o GSI 0.32 MG Overflow w/ 30% Impervious Mitigated ==> 0.63 gal/sf mitigated Flow 1 30% Reduction Close to Compliance Capacity Far From Compliance Capacity 0 0.00 10.00 20.00 30.00 40.00 50.00 60.00
GI Effectiveness (gal CV removed/sf to practice) Basin Scale Optimization: Practice Specific Performance 1.4 1.2 1.0 0.8 0.6 0.4 Basin 150 Basin 152 0.2 0.0 Cisterns Alleys Raingardens Total
NPV ($M) CSO: Cost Premium for GSI in Right-of-Way (NPV) $100.0 $90.0 $88.8 $92.7 $84.0 $80.0 $70.0 $71.6 $60.0 $53.6 $56.5 $50.0 Gray Cost Gray + Green $40.0 $30.0 $20.0 $10.0 $5.4 $5.0 $0.0 North Union Bay (NUB) Montlake Delridge Ballard
If we value all the silos collectively, GSI anticipated to be highly cost effective
Whats New?
What is our approach to solutions? Fix It, First Sewer System Improvements Keep Stormwater Out Natural Drainage Solutions Store What s Left Underground Storage
CSO reduction goals - Areas considered for GSI
Seven GSI Projects planned
GSI Program Resources! GSI Program Management RFP GSI Project Implementation RFP (Proposals Due 10/2/12) https://www.ebidexchange.com
Questions? Tracy Tackett GSI Program Manager www.seattle.gov/util/greeninfrastructure City of Seattle Seattle Public Utilities Ray Hoffman, Director
Green Infrastructure Siting & Informed Concent
Project Timeline for Ballard & Delridge projects in initial contract(s)