Laserfiche WebLink
Stormwater Technical Memorandum <br />Summary <br />Perteet <br />2707 Colby Avenue, Suite 900, Everett, WA 98201 1 P 425.252.7700 I F 425.339.6018 <br />The proposed project will have little stormwater impact. With the incorporation of roof drain flow dispersion, <br />there will be no new effective impervious area and no need for additional BMPs. Table 2 below summarizes <br />how the project will comply with each of the nine minimum requirements include in the Stormwater <br />Management Manual. <br />Table 2. Summary of Project <br />Requirements <br />Approach to Compliance with Minimum <br />Requirement <br />Project Conformance/Method of Compliance <br />1. <br />Stormwater Site Plan <br />This memorandum, in conjunction with the architectural <br />Prepartion <br />plans, will serve as the project stormwater site plan. <br />2. <br />Construction <br />As described herein, the project has a very low risk of <br />Stormwater Pollution <br />erosion during construction and will not require <br />Prevention <br />temporary BMPs. <br />3. <br />Source Control of <br />The project will not generate pollutants which require <br />Pollution <br />source control. <br />4. <br />Preservation of Natural <br />Discharge will be via splash blocks which will mimic <br />Drainage Systems and <br />existing drainage patterns. <br />Outfalls <br />S. <br />On -Site Stormwater <br />On -site infiltration will be used to retain runoff onsite. <br />Management <br />6. <br />Runoff Treatment <br />Not required as there is no new pollution generating <br />surfaces being added. <br />7. <br />Flow Control <br />As described herein, gravel zones will be included below <br />the portables. These zones are sized to infiltrate all runoff <br />from portable roofs. <br />8. <br />Wetland Protection <br />There are no identified wetlands within or near to the <br />work area. <br />9. <br />Operations and <br />Everett Public Schools will incorporate maintenance of <br />Maintenance <br />the portable structures and downspouts into their <br />existing site maintenance plan. <br />Attachments: <br />Attachment I — 2012 WWHM Project Report <br />Attachment 2 — Targeted Drainage Report Silver Lake Elementary Parking Lot Expansion, January 2003 <br />Attachment 3 — Silver Lake Elementary Additions -Schematic Design Narrative, Water, Sewer, Drainage <br />October 2006 <br />Attachment 4 — Excerpts from Subsurface Exploration, Geological Hazard and Geotechnical Report- Silver Lake <br />Elementary School Building Additions, Service Drive, and Water Line Installation, November 2006 <br />Page 3 <br />File location: x:\Everett Public SchoolslProjects\20150040 - Silver Lake Elementary Portables Oesign\Drainage\Silver Lake Elementary Drainage <br />Memorandum - Everetr.docx <br />