3721 OAKES AVE EVERETT MEMORIAL STADIUM 2018-12-21

PI engineering p c CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN (SWPPP) The preliminary SWPPP narrative for this project can be found in Appendix C and is based on the requirements of Volume II of the Everett SWMM.An NPDES permit from the Washington State Department of Ecology will not be required for the project,since the project does not discharge to a surface water of the state,but instead to the sanitary sewer system. This design will include the following TESC measures: • Temporary Stabilized Construction Entrance,per BMP C105 • Interceptor Dike and Swale,per BMP C200 • Catch Basin Filters,per BMP C220 • Silt Fence,per BMP C233 • Temporary Sediment Settling Tank The TESC plan includes a temporary sediment settling tank.The volume for an equivalent sediment trap was calculated per section 3.3.17,Volume 2 of Everett SWMM. The 10-year peak flow was used for sizing due to anticipated winter construction.The minimum sediment tank volume is shown on the TESC plan,attached in Appendix A.A copy of the Sediment Tank Sizing Calculations worksheet and associated WWHM output are included in Appendix B. The TESC elements shown are intended to be the minimum allowable. During construction,the contractor is responsible for upgrading these facilities as necessary. The implementation of the TESC plan and construction maintenance,replacement and upgrading of the TESC facilities are the responsibility of the contractor per the contract documents. The TESC facilities will be constructed prior to and in conjunction with all clearing and grading activity and in a manner in which sediment or sediment laden water does not leave the project site,enter the drainage system,or violate applicable water quality standards. LPD Engineering, PLLC Page 9 Everett Memorial Stadium Baseball Field Replacement Storm Drainage Report, September 15, 2017