2017-05-11_PERMIT FILE - C1981012 (18)

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PART I Page 30 of 52 Permit No.: C00000906 Adverse weather does not exempt the permittee from having to file timely DMRs. The permittee must report any failure to monitor, including the basis for not sampling during the usual reporting period. Evidence to support this basis may include the dates that monitoring attempts were made; photographs; field notes and official weather data from a scientifically recognized organization, such as NOAA or the NWS, that establish site inaccessibility, etc. 6. Additional Stormwater-specific provisions (Outfall 010) a. Measurable Storm Events i. Rain event. The permittee must conduct all required monitoring on a storm event that results in an actual discharge from the facility ("measurable storm event'), and that follows the preceding measurable storm event by at least 72 hours (3 days), except as provided in b., below. ii. Snowmelt event. The permittee must conduct snowmelt monitoring at a time when a measurable discharge occurs from the facility, except as provided in b., below. b. Detained stormwater In the event stormwater is detained at the facility, such as in a detention pond/area, the permittee must conduct all required monitoring on discharges from such detention areas, whether the discharge results from a rain or snowmelt event or from the manual release of accumulated stormwater from the detention area. c. Storm Event Information i. Rain event. The permittee must document the information below for each monitored event. Such documentation is not required for events that do not meet the measureable storm event criteria above, or that are not monitored to meet the requirements of this permit. a) The date, time of the start of the discharge, time of sampling, duration (in hours) of the rainfall event, and magnitude (in inches) of the storm event sampled; b) The duration between the storm event sampled and the end of the most recent storm event that produced a discharge. ii. Snowmelt monitoring. The permittee must document the date of the sampling event for each monitored snowmelt event. d. Sample Type and Requirements i. Grab samples shall be used for all monitoring and shall not be combined. ii. Permittees must take a minimum of one grab sample from a discharge resulting from a measurable storm event. iii. Grab samples must be collected within the first 30 minutes of a measurable storm event (see Measureable Storm Events above). If it is not possible to collect the sample within the first 30 minutes of a measurable storm event, the sample must be collected as soon as practicable after the first 30 minutes, and documentation must be kept with the SWMP explaining why it was not possible to take samples within the first 30 minutes. iv. In the case of snowmelt, samples must be taken during a period with a measurable discharge. v. All discharge samples at a facility must be taken during the same storm event, if feasible.