CORRESPONDENCE_2003-2004 - Laserfiche WebLink

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* if Foothill Sanitary Landfill San Joaquin County The Report mentions MTBE and 1,4-Dichlorobenzene in MW-1 and MW-3. No resampling was performed because the County states they are in evaluation monitoring. Resampling should have been pursued since MW-1 is an upgradient well. The County should consider adding a new upgradient monitoring well if MW-1 is proven to be contaminated with VOCs. The following table shows the discrepancies in the report based on laboratory sheets: Constituent (gg/L) MW-1 MW-2 MW-3 Continent (upgradient) MTBE 1.4 BL* ND Not noted correctly in table, text, and/or _graphs 5.3 Seq** ND Correct 1,4-Dichlorobenzene 0.8 BL ND Not noted correctly in table, text, and/or a hs 1,1,2-Trichloro-1,2,2- 0.9 BL 0.8 BL Not noted in table, text, and/or graph Trifluoroethane Dichloromethane 17.7 BL 12.7 BL Not noted in table, text, and/or graph__ Chloroform 1.9 BL 1.4 BL Not noted in table, text, and/or graph *BL =Basic Laboratory **Seq=Sequoia Laboratory As above, the Annual report states that only two VOCs were detected at MW-3 during 2002. This is an incorrect statement based on the laboratory sheets. Please review the laboratory sheets for 2002 and update the specific Tables in the monitoring report, Historical Tabulated Summary, and Time Series Graphs. We request the County submit corrected text, tables and graphs in a revised addendum to the 2002 Annual Report by 15 October 2003. 4. The Annual report shows the 360 mg/L TDS result at MW-1 (upgradient well) was deleted as a statistical outlier. Statistical outliers must not be deleted from the Time Series Graphs or tabulated summaries unless there is a full explanation for deleting them from the record. Note that TDS at 360 mg/L in MW-1 was plotted in the 3rd Quarter 2002 report, but taken out of the 4th Quarter/Annual Time Series graphs. There is no discussion in the text that supports the deletion of the 360 mg/L TDS result for MW-1. It must be proven that it is an outlier by resampling, but this was not done. Please provide an explanation for the deletion of this value. Note: An EC of 250 was field measured during this sampling event; however, this value does not correlate with a TDS of 360 mg/L. The common conversion of EC to TDS is a multiplier of 0.6. An EC of 250 would equate to a TDS of 150 mg/L in this regard. Please provide an explanation for this discrepancy. In the future, the County should resample immediately upon discovering such high values in COCl from the upgradient well in order to validate the result. 5. The 4' Quarter sampling event detected VOCs in groundwater, as shown in the above table. MW- 1, MW-2 and MW-3 laboratory sheets from Basic Laboratory.and Sequoia Laboratory depict these detections. The County states that a descrete retest was not performed because they are already in Evaluation Monitoring. This is an incorrect assumption based on the minimum requirements in Title 27,which state, " (e) Ongoing Monitoring—In conjunction with the assessment conducted