1502 WALL ST IMAGINE CHILDRENS MUSEUM 2022-08-25

Element 6: Protect Slopes (2.1.6) West of the Cascade Mountains Crest Describe how slopes will be designed, constructed, and protected to minimize erosion. Temporary pipe slope drains must handle the peak 10-minute flow rate from a Type 1A, 10- year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate predicted by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model (WWHM) to predict flows, bare soil areas should be modeled as "landscaped area". Describe how you will reduce scouring within constructed channels that are cut down a slope. Will steep sloe- be present at the site during construction? Yes No BMP C200: Interceptor Dike and Swale Alternate slope protection BMPs are included in Appendix B as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix E). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix E), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix B after the first sign that existing BMPs are ineffective or failing. Installation Schedules: [Insert text here] Inspection and Maintenance plan: [Insert text here] Responsible Staff: [Insert text here]