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6.2.1 Turbidity Sampling <br /> Monitoring requirements for the proposed project will include either turbidity or water transparency <br /> sampling to monitor site discharges for water compliance with the 2005 Construction Stormwater <br /> General Permit(Appendix D). Sampling will be conducted at all discharge points at least once per <br /> calendar week. <br /> Turbidity or transparency monitoring will follow the analytical methodologies described in Section S4 of <br /> the 2005 Construction Stormwater General Permit(Appendix D).The key benchmark values that require <br /> action are 25 NTU for turbidity(equivalent to 32 cm transparency) and 250 NTU for turbidity(equivalent <br /> to 6 cm transparency). If the 25 NTU benchmark for turbidity is exceeded,the following steps will be <br /> conducted: <br /> 1. Ensure all BMPs specified in this C-SWPPP are installed and functioning as intended. <br /> 2. Assess whither additional BMPs should be implemented, and document revisions to the C- <br /> SWPPP as necessary. <br /> 3. Sample discharge location daily until the analysis results are less than 25 NTU (turbidity). <br /> If turbidity is greater than 25 NTU (or transparency is less than 32 cm) but less than 250 NTU <br /> (transparency greater than 6 cm)for more than 3 days, additional treatment BMPs will be implemented <br /> within 24 hours of the third consecutive sample that exceeded the benchmark value.Additional <br /> treatment BMPs to be considered will include, but are not limited to,off-site treatment, infiltration and <br /> chemical treatment. <br /> If the 250 NTU benchmark for turbidity (or less than 6 cm transparency) is exceeded at any time,the <br /> following steps will be conducted: <br /> 1. Notify Ecology by phone within 24 hours of analysis(see Section 5.0 of this C-SWPPP for contact <br /> information). <br /> 2. Continue daily sampling until the turbidity is less than 25 NTU (or transparency is greater than <br /> 32 cm). <br /> 3. Initiate additional treatment BMPs such as off-site treatment, infiltration and chemical <br /> treatment within 24 hours of the first 250 NTU exceedance. <br /> 4. Implement additional treatment BMPs as soon as possible, but within 7 days of the first 250 <br /> NTU exceedance. <br /> 19 <br />