Green Infrastructure to Reduce CSOs in Portland, OR 2011 Low Impact Development Symposium Philadelphia, PA September 26 2011
Tim Kurtz, PE City of Portland, Oregon Bureau of Environmental Services Sustainable Stormwater Management Program Portland’s Combined Sewer System
• built 1880s – 1960s • 44 square miles – 35% of city area – serves ~60% of residents • 55 outfalls – 13 Columbia Slough – 42 Willamette River • 1,000+ miles of pipe Portland’s CSO Program
• 1991: Stipulated Final Order, CSO Program begins • 1994: Amended Stipulated Final Order – control Columbia Slough by December 2000 – control Willamette River by December 2011
Winter Summer CSO Volume CSO Discharge (Nov – Apr) (May – Oct) Reduction Columbia Slough 5-yr 10-yr 99.5% Willamette River 4 per year 3-yr 94%
Average # of CSO Volume Year CSOs / Year (billion gallons) 1990 50. 6.0 2011 4.33 0.3
CSO Program 6
5 Westside Eastside CSO Tunnel CSO Tunnel 14-ft diameter, 22-ft diameter, 3.5 miles 5.7 miles 4
3
Cornerstone Columbia 2 Projects Slough cost-effective Tunnel stormwater 6 to 12-ft 1 inflow reduction diameter, projects 3.5 miles Annual CSO Volume (billions of gallons)
0 1990 1995 2000 2005 2010 2015 Year CSO Program
Estimated Costs Cornerstone Projects $145M Columbia Slough $160M West Side CSO Program $410M East Side CSO Program $640M Total $1.4B Cornerstone Projects
• Sewer Separation (1993 – 1996) – separate storm sewer installed – northern basins sent to ponds for water quality treatment
Ramsey Lake Wetlands WPCL Pond Cornerstone Projects
• Tanner Creek Separation (2000 – 2006) – westside stream piped in 1917 – creek flow and treated runoff diverted to a storm only pipe – remaining combined flow sent to Westside CSO Tunnel – removes ~ 165 MG annually Cornerstone Projects
• Residential Street Sumps (1993 – 2001) – 20-30 ft deep drywells – sediment manhole for pretreatment – ~3,000 in residential streets Cornerstone Projects
• Downspout Disconnection Program (1993 – 2011) – 1993: pilot testing in sumped residential neighborhoods (sewer separation areas) – 1995: Program formally adopted by City Council – 2004: Program expands to include small multifamily and commercial sites Cornerstone Projects
• Downspout Disconnection Program (1993 – 2011)
Estimated Annual # of Downspouts Acres of roof Volume Managed Program Disconnected managed (billion gallons) Cost 56,000 1,130 1.2 $13M
CSO Program
CSO Program Cost Gallons Managed
10% 35% Grey Green 65% 90% Green Momentum
• foundation for:
• experience and confidence • public involvement Green Policies, Programs, and Politics
• Stormwater Management Manual (1999) – development & re-development – on-site stormwater management, using vegetated surface facilities first
• City Green Building Policy (2005)
• Clean River Rewards (2006) – private property green stormwater projects – up to 35% discount on stormwater fees – 34,000+ registrants Green Policies, Programs, and Politics
• Grey to Green Initiative (2008) – City Council approved $50M over 5 years • 40 new acres of green roofs • 200 green streets • 80,000 private & public trees • 400 acres of property acquisition • invasive species control • Ecoroof Incentive Program (2008) – $5 per sq ft – funded through 2013 Portland’s Green CSO Future
• 20 Year LTCP complete as of December 1, 2011
• Post-2011 CSO Facilities Plan – 2011 – 2050 – manage runoff from 600 acres of impervious area, all green • downspout disconnection • combined sewer capacity projects (Tabor to the River)