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Appendix A Decentralized CSO Analysis: Framework Matrix for Policy Options and Criteria Options Primary Criteria Sub-Criteria Green Roofs Landscape swales Rain Barrels Rain Cisterns Porous Pavement 2-year storm: 11.76% 2-year storm: 5.50% 2-year storm: 7.04% 2-year storm: 29.33% 2-year storm: 13.50% Peak Flow Reduction In-system 25-year storm: 5.88% 25-year storm: 1.75% 25-year storm: 1.60% 25-year storm: 6.67% 25-year storm: 3.0% Flow Reduction1 Average Annual 1.47% 21.75% 1.44% 6.00% 14.25% Volume Reduction Ideal roof has 5-20* Minimum size slope2 requirements: 1% of impervious area + Suitable for new Load reserves 15lbs/ between 0.5% - 2% grade Implementation easy construction and retrofit sq ft > snow load + 3:1 side slope3 Majority of Fremont pilot projects; good for almost requirements needed 2 Survey shows 2/3 Widespread focus group participants any setting6 Landowners may lose a public support4 Implementation reacted positively to Non-uniform roof portion of yard 4 cisterns Installation can be designs present Successful voluntary disruptive to landowner implementation Yards are various shapes program in place5 which may limit appeal challenges and sizes; may present design and installation Installation is disruptive complications City of Seattle has Drainage Swale not considered adding LEED officially recognized for requirements to building stormwater control in code for private sector7 Seattle Code; City would May violate state water May violate state water May help meet Legality have to develop code or rights laws rights laws drainage codes9 Some homes may have evaluate permit building code issues applicants on a case-by- for bearing loads of case basis8 green roofs Feasibility Interest of City Council Interest of City Council Interest of City Council Interest of City Council for other projects11: Interest of City Council for other projects10: for other projects11: for other projects7: for other projects7: Political SEA Street Initiative Feasibility City Hall SEA Street Initiative Fremont Rainharvesting funded since 2001 Seattle Rain Barrel funded since 2001 pilot project program Ballard Library Northgate Mall Parking Lot pilot project Low/Niche appeal; some Moderate/High appeal; Moderate/High appeal; Moderate appeal; large High appeal; may depend Aesthetics 12 may find landscaping the depends on yard size, relatively low cistern may be obtrusive, on porous roof appealing. shape, and design obtrusiveness depending on lot layout material used 13 Total Per-Property Cost $33,810.00 $816.67 $153.02 $1,392.00 $7,978.13 *See next page for Appendix A notes Appendix A Notes 1 For a detailed description of the methodology used in these calculations, refer to Appendix C. 2 Sholz-Barth, Katrin. "Green Roofs: Stormwater Management from the Top Down." Environmental Design & Construction Magazine Jan-Feb. 2001:1-11. 3 EPA's Stormwater Technology Fact Sheet for Vegetated Swales: http://www.epa.gov/owm/mtb/vegswale.pdf 4 Rainwater Harvest Pilot Project Business Case FINAL 2003, pg.9 5 City of Seattle website, SPU Services, Rain Barrel Program: http://www.ci.seattle.wa.us/util/Services/Yard/Natural_Lawn_&_Garden_Care/Rain_Barrels/index.asp 6 Whole Building Design Guide Website, Design Guidance, Low Impact Development Technologies: http://www.wbdg.org/design/lidtech.php 7 Greenroofs.com website, "Sky Gardens- Travel in Landscape Architecture in Seattle, WA" by Linda Velazques, August/September 2004: http://www.greenroofs.com/archives/sg_aug-sep04.htm Constructive Criticism: LEED green-building program confronts critics and growing pains by Ted S. Bowen, 10/26/05 in Grist Magazine: http://www.grist.org/news/maindish/2005/10/26/leed/ 8 City of Seattle website, "Sustainable Sites Prerequisite: Comparison of Seattle and [LEED] Reference Standard", Drainage Swales p 3: http://www.cityofseattle.net/sustainablebuilding/Leeds/docs/Site_Prereq.pdf 9 Seattle Department of Planning and Development Client Assistance Memo 515, Seattle Permits, Green Parking Lots: http://www.ci.seattle.wa.us/dclu/Publications/cam/CAM515.pdf 10 Puget Sound Action Team website, Green Building Programs: http://www.psat.wa.gov/Publications/LID_studies/green_building.htm 11 City of Seattle website, SEA Streets Project: http://www.ci.seattle.wa.us/util/About_SPU/Drainage_&_Sewer_System/Natural_Drainage_Systems/Street_Edge_Alt ernatives/index.asp City of Seattle website, Northgate Mall Pilot Project: http://www.ci.seattle.wa.us/dpd/stellent/groups/public/@dpd/@plan/@proj/@northgate/documents/dpd_informational/ cos_004274.pdf 12 Extensive searching yielded no information for aesthetics, so the analysis is based on subjective opinion. 13 For the detailed analysis and cost breakdown, refer to Appendix B.
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