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STANDARD PROVISIONS AND REPORTING REQUIREMENTS, JANUARY 2012 - 18 - <br />FOR WASTE DISCHARGE REQUIREMENTS <br />FOR DISCHARGES REGULATED BY SUBTITLE D AND/OR TITLE 27 <br /> <br /> <br />15. If the laboratory suspects that, due to a change in matrix or other effects, the <br />true detection limit or quantitation limit for a particular analytical run differs <br />significantly from the laboratory-derived MDL/PQL values, the results shall be <br />flagged in the laboratory report accordingly, along with estimates of the <br />detection limit and quantitation limit actually achieved. The MDL shall always <br />be calculated such that it represents the lowest achievable concentration <br />associated with a 99% reliability of a nonzero result. The PQL shall always <br />be calculated such that it represents the lowest constituent concentration at <br />which a numerical value can be assigned with reasonable certainty that it <br />represents the constituent’s actual concentration in the sample. Normally, PQLs <br />should be set equal to the concentration of the lowest standard used to calibrate <br />the analytical procedure. <br /> <br />16. All QA/QC data shall be reported, along with the sample results to which they <br />apply, including the method, equipment, analytical detection and quantitation <br />limits, the percent recovery, an explanation for any recovery that falls outside <br />the QC limits, the results of equipment and method blanks, the results of spiked <br />and surrogate samples, the frequency of quality control analysis, and the name <br />and signature of a responsible person from the laboratory. Sample results <br />shall be reported unadjusted for blank results or spike recoveries. In <br />cases where contaminants are detected in QA/QC samples (i.e., field, trip, or lab <br />blanks), the accompanying sample results shall be appropriately flagged, but the <br />analytical results shall not be adjusted. <br /> <br />17. Unknown chromatographic peaks shall be reported, flagged, and tracked for <br />potential comparison to subsequent unknown peaks that may be observed in <br />future sampling events. Identification of unknown chromatographic peaks that <br />recur in subsequent sampling events may be required. <br /> <br />18. The sampling interval of each monitoring well shall be appropriately screened <br />and fitted with an appropriate filter pack to enable collection of representative <br />groundwater samples [Title 27, § 20415(b)(4)(B)]. Groundwater samples shall <br />not be field-filtered prior to laboratory analysis [40 C.F.R. § 258.53(b)]. <br />Groundwater samples needing filtering (e.g., samples to be analyzed for <br />dissolved metals) shall be filtered by the laboratory prior to analysis. <br /> <br />19. Groundwater elevations shall be measured in each well immediately prior to <br />purging, each time groundwater is sampled. The owner or operator shall <br />determine the rate and direction of groundwater flow each time groundwater is <br />sampled. Groundwater elevations in wells which monitor the same waste <br />management area shall be measured within a period of time short enough to <br />avoid temporal variations in groundwater flow which could preclude accurate <br />determination of groundwater flow rate and direction [40 C.F.R. § 258.53(d)]. <br /> <br />20. Monitoring wells, piezometers, and other measurement, sampling, and analytical <br />devices must be operated and maintained so that they perform to design