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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 />£ 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. 0 <br />C on.struction .Sfori awcater General Permit <br />Page 16 <br />