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• e. The Permittee may discontinue sampling at discharge points in areas of the <br />project where the Permittee no longer has operational control of the construction <br />activity. <br />4. Sampling and Analysis Methods <br />a. The Permittee performs turbidity analysis with a calibrated turbidity meter <br />(turbidimeter) either on site or at an accredited lab. The Permittee must record <br />the results in the site log book in nephelometric turbidity units (NTUs). <br />b. The Permittee performs transparency analysis on site with a 13/4-inch-diameter, <br />60-centimeter (cm) -long transparency tube. The Permittee will record the results <br />in the site log book in centimeters (cm). <br />Table 4: Monitoring and Reporting Requirements <br />Parameter <br />Unit <br />Analytical Method <br />Sampling <br />Benchmark <br />Phone <br />Frequency <br />Value <br />Reporting <br />Trigger Value <br />Turbidity <br />NTU <br />SM2130 <br />Weekly, if <br />25 NTUs <br />250 NTUs <br />discharging <br />Transparency <br />cm <br />Manufacturer <br />Weekly, if <br />33 cm <br />6 cm <br />instructions, or <br />discharging <br />Ecology guidance <br />• 5. Turbidity/Transparency Benchmark Values and Reporting Triggers <br />The benchmark value for turbidity is 25 NTUs or less. The benchmark value for <br />transparency is 33 centimeters (cm). Note: Benchmark values do not apply to <br />discharges to segments of water bodies on Washington State's 303(d) list <br />(Category 5) for turbidity, fine sediment, or phosphorus; these discharges are <br />subject to a numeric effluent limit for turbidity. Refer to Special Condition S8 for <br />more information. <br />a. Turbidity 26 — 249 NTUs, or Transparency 32 — 7 cm: <br />If the discharge turbidity is 26 to 249 NTUs; or if discharge transparency is <br />less than 33 cm, but equal to or greater than 6 cm, the Permittee must: <br />i. Review the SWPPP for compliance with Special Condition S9 and make <br />appropriate revisions within 7 days of the date the discharge exceeded the <br />benchmark. <br />ii. Immediately begin the process to fully implement and maintain <br />appropriate source control and/or treatment BMPs as soon as possible, <br />addressing the problems within 10 days of the date the discharge <br />exceeded the benchmark. If installation of necessary treatment BMPs is <br />not feasible within 10 days, Ecology may approve additional time when <br />the Permittee requests an extension within the initial 10-day response <br />period. <br />Construction Storrnwoter General I'errnit <br />Page 17 <br />