ARCHIVED REPORTS XR0004111 - Laserfiche WebLink

Home Browse Search

�> Mr. Harlin Knoll San Joaquin County Environmental Health Department October 26,2005 • Page 2 of 3 Groundwater Sampling and Analytical Results Groundwater monitoring wells MW-1 through MW-3 were sampled on May 9, 2005. The methods used to collect the samples are presented in Attachment A. Samples from these wells were analyzed for total petroleum hydrocarbons in the gasoline range (TPHg), benzene, toluene, ethylbenzene, xylenes (BTEX), methyl tertiary butyl ether (MTBE), tertiary amyl methyl ether (TAME), tertiary butyl alcohol (TBA), di-isopropyl ether (DIPE), and ethyl tertiary butyl ether (ETBE) by using EPA Method 8260B. Kiff Analytical Labs, Inc. (Kiff Analytical) of Davis, California, a California state-certified laboratory, performed the chemical analyses. The analytical laboratory report, including chain-of-custody documentation, is included as Enclosure C. Laboratory analytical results for the second quarter 2005 sampling event are presented in Table 2 and concentrations of MTBE, benzene and TPHg are shown on Figure 3. Conclusions ■ Concentrations of TPHg decreased in MW-1 and MW-2 to below the laboratory reporting limit of 50 micrograms per liter (µg/Q. ■ Concentrations of MTBE in groundwater samples collected from MW-1 remain at a decreased concentration (lI pg/L) after having decreased by an order of magnitude during the fourth quarter 2004. ■ The groundwater flow direction trend continues to be in a southerly direction (Figure 2). • Future Work The next groundwater monitoring event is scheduled for July 2005. A down-gradient, off-site groundwater monitoring well has been proposed and will be installed if Delta is successful at obtaining a right-of-entry agreement with the owner of the adjacent shopping center. Remarks The recommendations contained in this report represent Delta's professional opinions based upon the currently available information and are arrived at in accordance with currently acceptable professional standards. This report is based upon a specific scope of work requested by the client. The contract between Delta and its client outlines the scope of work, and only those tasks specifically authorized by the contract or outlined in this report were performed. This report is intended only for the use of Delta's client and anyone else specifically listed on this report. Delta will not and cannot be liable for unauthorized reliance by any other third party. Other than as contained in this paragraph, Delta makes no express or limited warranty as to the contents of this report.