9509 19TH AVE SE 2018-01-02 MF Import

Everett LDS Parking Lot Expansion Storm Drainage Report 4. Analysis and Design of Required Erosion and Sediment Control BMPs Silt Icncing is proposed along the downstream perimeter of the disturbed area (northeast corner of the property). Inlet protection will be installed in the existing catch basins near disturbed portions oflhe site. Site management for ESC measures are not limited to the above listed best management practices (BMPs). The contractor shall provide additional BMPs as appropriate for changing site conditions. It is anticipated that there is little potential for erosion and sedimentation of onsite earthwork to adversely impact downstream properties. 5. Analysis and Design of Required Runoff Control (Treatment and Stream Bank Erosion Control) BMPs Refer to Figure 5 — basins Exhibit on the following page to aid in the following discussion. The Upstream Basin was considered in the conveyance capacity analysis as shown in Section 3. Since Upstream Basin B is tributary to the new development area, the basin was included with the onsite development area in both the detention and water quality sizing. Note that a ridgeline is created between the existing parking lot and the proposed parking lot expansion area thus separating drainage from the proposed expansion to its own system. Therefore, only the onsite areas for the new development basin will be considered in the detention and water quality analysis. P;%2006106113 Everett WE Perk ng L06reat15torm Reports%06113 Drainage Report Revised 01.10.06.d" Page 16 of 36