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C. Turbidity/Transparency Sampling Requirements <br /> 1. Sampling Methods <br /> a. If construction activity involves the disturbance of 5 acres or more, the <br /> Permittee must conduct turbidity sampling per Special Condition S4.C. <br /> b. If construction activity involves 1 acre or more but fewer than 5 acres of soil <br /> disturbance, the Permittee must conduct either transparency sampling or <br /> turbidity sampling per Special Condition S4.C. <br /> 2. Sampling Frequency <br /> a. The Permittee must sample all discharge points at least once every calendar <br /> week when stormwater(or authorized non-stormwater)discharges from the site <br /> or enters any on-site surface waters of the state(for example, a creek running <br /> through a site); sampling is not required on sites that disturb less than an acre. <br /> b. Samples must be representative of the flow and characteristics of the discharge. <br /> c. Sampling is not required when there is no discharge during a calendar week. <br /> d. Sampling is not required outside of normal working hours or during unsafe <br /> conditions. <br /> e. If the Permittee is unable to sample during a monitoring period,the Permittee <br /> must include a brief explanation in the monthly Discharge Monitoring Report <br /> (DMR). <br /> f. Sampling is not required before construction activity begins. <br /> g. The Permittee may reduce the sampling frequency for temporarily stabilized, <br /> inactive sites to once every calendar month. <br /> 3. Sampling Locations <br /> a. Sampling is required at all points where stormwater associated with <br /> construction activity(or authorized non-stormwater) is discharged off site, <br /> including where it enters any on-site surface waters of the state(for example, a <br /> creek running through a site). <br /> b. The Permittee may discontinue sampling at discharge points that drain areas of <br /> the project that are fully stabilized to prevent erosion. <br /> c. The Permittee must identify all sampling point(s) on the SWPPP site map and <br /> clearly mark these points in the field with a flag,tape, stake or other visible <br /> marker. <br /> d. Sampling is not required for discharge that is sent directly to sanitary or <br /> combined sewer systems. <br /> Construction Stormwater General Permit <br /> Page 16 <br />