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Stormwater Pollution Prevention Plan <br /> 1 <br /> O Assess the effectiveness of erosion and sediment control measures used <br /> to control the quality of stormwater discharges. <br /> ■ A Certified Erosion and Sediment Control Lead shall be on-site or on-call <br /> at all times. <br /> ■ Whenever inspection and/or monitoring reveals that the BMPs identified <br /> in this SWPPP are inadequate, due to the actual discharge of or potential <br /> ' to discharge a significant amount of any pollutant, appropriate BMPs or <br /> design changes shall be implemented as soon as possible. <br /> Maintaining an Updated Construction SWPPP <br /> ■ This SWPPP shall be retained on-site or within reasonable access to the <br /> site. <br /> The SWPPP shall be modified whenever there is a change in the design, <br /> construction, operation, or maintenance at the construction site that has, <br /> ' or could have, a significant effect on the discharge of pollutants to waters <br /> of the state. <br /> 'I . The SWPPP shall be modified if, during inspections or investigations <br /> conducted by the owner/operator, or the applicable local or state <br /> regulatory authority, it is determined that the SWPPP is ineffective in <br /> ' eliminating or significantly minimizing pollutants in stormwater discharges <br /> from the site. The SWPPP shall be modified as necessary to include <br /> additional or modified BMPs designed to correct problems identified. <br /> Revisions to the SWPPP shall be completed within seven (7) days <br /> following the inspection. <br /> 3.1.13 Element#13 — Construction Stormwater Chemical <br /> Treatment <br /> Turbidity is difficult to control once fine particles are suspended in stormwater runoff from a <br /> construction site. Sedimentation ponds are effective at removing larger particulate matter by <br /> gravity settling, but are ineffective at removing smaller particulates such as clay and fine silt. <br /> Sediment ponds are typically designed to remove sediment no smaller than medium silt <br /> (0.02 mm). Chemical treatment may be used to reduce the turbidity of stormwater runoff. <br /> Chemical treatment can reliably provide exceptional reductions of turbidity and associated <br /> pollutants. Very high turbidities can be reduced to levels comparable to what is found in <br /> streams during dry weather. Traditional BMPs used to control soil erosion and sediment loss <br /> from sites under development may not be adequate to ensure compliance with the water quality <br /> standard for turbidity in the receiving water. Chemical treatment may be required to protect <br /> ' streams from the impact of turbid stormwater discharges, especially when construction is to <br /> proceed through the wet season. <br /> ' Formal written approval from Ecology and the Local Permitting Authority is required for <br /> the use of chemical treatment regardless of site size. The intention to use Chemical <br /> 12 16580.006.doc <br />