1502 WALL ST IMAGINE CHILDRENS MUSEUM 2022-08-25

Element 4: Install Sediment Controls (2.1.4) Describe how you will minimize sediment discharges from the site. Construct sediment control BMPs as one of the first steps of grading. These BMPs must be functional before other land disturbing activities — especially grading and filling — take place. Describe the BMPs identified to filter sediment prior to it being discharged to an infiltration system or leaving the construction site. Describe how you will direct stormwater for maximum infiltration where feasible. Describe how you will not interfere with the movement of juvenile Salmonids attempting to enter off-channel areas or drainages. Describe how you will respond if sediment controls are ineffective and turbid water is observed discharging from the site. Consider the amount, frequency, intensity and duration of precipitation, soil characteristics, and site characteristics when selecting sediment control BMPs. In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The specific BMPs for flow control that may be used on this project include: BMP C240: Sediment Trap Alternate sediment control BMPs are included in Appendix B as a quick reference tool for the on-site 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. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in runoff. Whenever possible, sediment laden water shall be discharged into on-site, relatively level, vegetated areas. In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention ponds) can be used during the construction phase. When permanent stormwater BMPs will be