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03/07/95 09:45 12503 224 7820 WOODWARD -CLYDE <br /> the performance of tanks/vaults will improve if facilities are sized to capture and <br /> detain the entire water quality design storm runoff volume. In general, other controls, <br /> such as wet ponds and filtration devices, have proven better for controlling the levels <br /> oToifrpresentIn typical stormwater runoff <br /> For guidance on selection, design, installation and maintenance of oil/water separators <br /> and detention vaults/tanks, we recommend use of the Stormwater Management Manual <br /> for the Puget Sound Basin (1992) - Chapters III -7 and III -4.5, respectively . Similar <br /> information on trapped catchbasins and sedimentation manholes is contained in the <br /> new Portland document Stormwater Quality Facilities Design Guidance Manual <br /> (March 1995)- Chapter 6. For information on costs and effectiveness of trapped <br /> catchbasins and oil/water separators, EPA's Cruidance for Specifying Management <br /> Measures for Sources of Nonpoint Pollution in the Coastal Zone (1993) - Chapter 4 -I1, <br /> Table 4 -7 should be utilized. As discussed previously, there is no proven effectiveness <br /> data for sedimentation manholes and tanks/vaults. <br /> Erosion Control <br /> Several guidance documents are available on erosion control practices. The most <br /> recent publications (in chronological order) include the King County Surface Water <br /> Design Manual (1990), the City of Portland/Unified Sewerage Agency Erosion Control <br /> Technical Manual (1991), the Stormwater Management Manual for the Puget Sound <br /> Basin - Chapter 11 -5 (1992) and EPA's Guidance for Specifying Management Measures <br /> for Sources of Nonpoint Pollution in the Coastal Zone - Chapter 4, 111 -A (1993). <br /> For design and installation guidance, we recommend the Puget Sound document, <br /> which incorporates all of the information contained in the King County Manual. The <br /> City of Portland's document is a user-friendly manual which incorporates design <br /> criteria for various erosion control measures based on the King County 1990 Manual. <br /> Since all of the information is already in the Puget Sound document, the Portland <br /> manual is not required; except for a handy erosion control matrix (Table 3 -1) which <br /> may need to be adapted for Eugene conditions. Both the Puget Sound Manual and the <br /> Portland Technical Guidance Manual contain procedures for preparation and submittal <br /> of an erosion control plan which could be used as guidance by Eugene. EPA's <br /> Coastal Zone document is the only reference found that includes information on <br /> effectiveness and estimated costs for erosion control measures. <br /> Another good reference, and one of the first of its kind, is King County's Guidelines <br /> for Bank Stabilization Projects (June 1993). Published in a user- friendly, notebook- <br /> style, the manual describes the role and use of vegetation (Chapter 6), design <br /> guidelines (Chapter 7), construction procedures (Chapter 8) and long -term site <br /> S\945O42na \taskO2OO\onsite controls\techmcm.ek 14 <br />