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Stormwater Pollution Prevention Plan <br /> 1 <br /> 6.2 Stormwater Quality Monitoring <br /> 6.2.1 Turbidity Sampling <br /> ' Monitoring requirements for the proposed project will include either turbidity or water <br /> transparency sampling to monitor site discharges for water quality compliance with the 2005 <br /> Construction Stormwater General Permit (Appendix D). Sampling will be conducted at all <br /> discharge points at least once per calendar week. <br /> Turbidity or transparency monitoring will follow the analytical methodologies described in <br /> Section S4 of the 2005 Construction Stormwater General Permit (Appendix D). The key <br /> benchmark values that require action are 25 NTU for turbidity(equivalent to 32 cm <br /> transparency) and 250 NTU for turbidity (equivalent to 6 cm transparency). If the 25 NTU <br /> ' benchmark for turbidity (equivalent to 32 cm transparency) is exceeded, the following steps will <br /> be conducted: <br /> 1. Ensure all BMPs specified in this SWPPP are installed and functioning as <br /> intended. <br /> ' 2. Assess whether additional BMPs should be implemented, and document <br /> revisions to the SWPPP as necessary. <br /> 3. Sample discharge location daily until the analysis results are less than <br /> 25 NTU (turbidity) or greater than 32 cm (transparency). <br /> If the turbidity is greater than 25 NTU (or transparency is less than 32 cm) but less than <br /> i250 NTU (transparency greater than 6 cm)for more than 3 days, additional treatment BMPs will <br /> be implemented within 24 hours of the third consecutive sample that exceeded the benchmark. <br /> If the 250 NTU benchmark for turbidity (or less than 6 cm transparency) is exceeded at any <br /> time, the following steps will be conducted: <br /> 1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of <br /> this SWPPP for contact information). <br /> ' 2. Continue daily sampling until the turbidity is less than 25 NTU (or <br /> transparency is greater than 32 cm). <br /> ' 3. Initiate additional treatment BMPs such as off-site treatment, infiltration, <br /> filtration and chemical treatment within 24 hours of the first 250 NTU <br /> exceedance. <br /> ' 4. Implement additional treatment BMPs as soon as possible, but within <br /> 7 days of the first 250 NTU exceedance. <br /> ' 5. Describe inspection results and remedial actions taken in the site log <br /> book and in monthly discharge monitoring reports as described in Section <br /> 7.0 of this SWPPP. <br /> 24 16580.006.doc <br />