819 N BROADWAY WASHINGTON STATE UNIVERSITY 2018-05-11

Stormwater Pollution Prevention Plan Demolition: • Dust released from demolished sidewalks, buildings, or structures will be controlled using Dust Control measures (BMP C 140). • Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet Protection(BMP C220 as described above for Element 7). • Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering any downstream waters by implementing Sawcutting and Surfacing Pollution Prevention measures (BMP C 152). Concrete and grout: • Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C151). The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal regulations of the Clean Water Act(CWA). 3.1.10 Element#10—Control Dewatering Per the geotechnical report prepared by Hart Crowser on March 4, 2015, groundwater was not encountered during subsurface investigation. Dewatering of groundwater is not anticipated as part of the project. All sediment-laden construction stormwater from trenching will be directed into a controlled conveyance system consisting of an interceptor ditch (BMP C200) and check dams (BMP C207) placed as shown in the TESCP site plan in Appendix A. Stormwater runoff from the interceptor ditch will be directed into the onsite detention pond (per Sheet C 100 of the TESCP in Appendix A)prior to being discharged in accordance with the NPDES permit. Other BMPs to be used for sediment trapping and turbidity reduction include the following: • Interceptor Dike and Swale (BMP C200) • Silt Fence (BMP C233) or Straw Wattles (BMP C235) • Geotextile filter fabric socks/bags/cells • Portable Water Storage Tanks (e.g. Baker Tank) for Sedimentation Highly turbid dewatering water form soils known or suspected to be contaminated, or from use of construction equipment, will require additional monitoring and treatment or off-site disposal as required for the contaminants of concern. Monitoring is the responsibility of the contractor as described in Section 6.2. 11