ARCHIVED REPORTS_XR0006389 - Laserfiche WebLink

Home Browse Search

Mr Jim Barton ' May 16, 2006 Page 3 of 4 0 06 feet per foot Recently the predominant flow direction has been towards the east-southeast, as depicted on the groundwater flow direction rose diagram presented as Attachment 2 ' Sample Analytical Results ' A concentration map for PCE is presented as Figure 2 Analytical results for the quarterly groundwater monitoring event are presented in Tables 1 through 4 of the G-R monitoring report (Attachment 1) Maximum and minimum concentrations of the constituents detected in the groundwater samples are ' presented in the table below Number of Detections Minimum Maximum California Constituents above the MDL of the Concentration in,ug/L Concentration in Ng/L Primary 9 Samples (Well ID) (Well ID) (MCL) Benzene 1 NA 0 5 (MW-5) 1 TCE 8 2 (MW-13) 18 (MW-3 & MW-6) 5 PCE 9 120 (MW-14) 7,400 (MW-3) 5 Notes MDL = Method Detection Limit Ng/L = Microgram per Liter, equivalent to parts per billion (ppb) NA = Not Applicable MCL = Maximum Contaminant Level These concentration ranges are generally consistent with the concentrations detected during the fourth ' quarter of 2005, as summarized in Tables 1 through 4 Petroleum hydrocarbon constituents (i e , TPH, BTEX and MTBE) were not detected above the MDLs in groundwater samples collected from the nine monitoring wells, with the exception of one detection of benzene Benzene was detected in one ' monitoring well (MW-5) during this quarterly monitoring event at the reported MDL (0 5 tig/L), below the California Primary MCL for benzene (i e , 1 jig/L) TCE was detected in eight of the nine wells sampled and PCE was detected in all nine wells sampled during the first quarter of 2006 As discussed in the fourth quarter 2005 GMR for the site, the on-site TCE/PCE contamination is associated with the upgradient Lincoln Village Shopping Center chlorinated cleaning solvent plume Summary and Conclusions • During this quarter, groundwater flowed to the east-southeast at a horizontal hydraulic gradient ranging from 0 01 to 0 06 ft/ft • Analytical results for the first quarter of 2006 are generally consistent with the results of the fourth quarter of 2005, with the exception of a slight detection of benzene in monitoring well MW-5 at a concentration below the California Primary MCL • TCE and PCE were detected in groundwater samples collected from on-site monitoring wells The on-site TCE/PCE contamination is associated with the upgradient Lincoln Village Shopping Center chlorinated cleaning solvent plume 11462822 doe BLASLAND, BOUCK& LEE, INC engineers,scientists,economists