ARCHIVED REPORTS XR0000805 - Laserfiche WebLink

Home Browse Search

1 Date August 3,2004 A Quarter 2nd Quarter,2004 Based on the review of the analytical and hardcopy data (chain-of-custody records, blanks, dilutions, holding times, LCS/LCSD results,MS/MSD results, and surrogate recoveries),the data are acceptable as reported by the laboratory with the following limitations • The reported results for gasoline range organics (GRO) in samples MW-4, VW-1B,and VW-2B are due to a discrete peak at C5 (probably MtBE) J • The reported results for benzene in sample MWA may be biased high due to a high average percent recovery reported in the associated MS/MSD analysis • Elevated reporting limits were the result of dilutions performed by the laboratory in order to quantitate a target analyte DISCUSSION: GRO,benzene, toluene, ethylbenzene,total xylenes (BTEX),methyl tert-butyl ether (MtBE),and 1,2-dichloroethane (1,2-DCA)were reported above method detection limits in groundwater samples collected from site monitoring wells this quarter GRO and BTEX concentrations in MW-1 increased relative to the previous quarter but are generally consistent with results reported during fourth quarter 2003 with the slight exceptions of an increase in GRO and a decrease in concentration of toluene In MW-4, MtBE concentrations increased to 10,000 micrograms per liter (µg/L), the second highest concentration reported historically Total xylenes were reported above method detection limits (0 59 tig/L) in MW-6 for the first time historically GRO and MtBE concentrations in VW-1B decreased relative to the previous quarter In VW-2B, MtBE and 1,2-DCA concentrations increased relative to the previous quarter but are consistent with concentrations reported during and before fourth quarter 2003 In VW-3B, 1,2-DCA was reported above method detection limits at a concentration (15 tiglL) within historical data ranges Other analyte concentrations were generally consistent with historic data Methanol was added to the analyte list this quarter "MW-4, located approximately 40 ft northwest of the northwest corner of the tank pad, is the only monitoring well that reported methanol above method detection limits (590 tig/L) A new monitoring well (MW-8) and a vapor extraction well (VW-4) were installed during this quarter and added to the groundwater monitoring and sampling schedule VW-4 was unable to be sampled_ or monitored_due_ to insufficient water MtBE was the only analyte reported above method detection limits (1 3 jig/L) in the groundwater , sample cow ll ted from MW-8 during this sampling event Groundwater elevations in wells across the site generally decreased relative to the previous quarter The inferred groundwater flow direction was toward the southeast at an average hydraulic gradient of 0 04 feet/foot This report is based on data, site conditions, and other information that are generally applicable as of the date of the report,and the conclusions and recommendations herein are therefore applicable only to that time frame TABLES Table 1 Groundwater Elevation and Analytical Data Table 2 Fuel Oxygenates Analytical Data Table 3 Groundwater Gradient Data FIGURES Figure I Groundwater Elevation Contours Figure 2 Groundwater Analytical Summary K 1WpFO aW5 BP ARC0102186VQuaner1yl2 QTR 0412186 GWMR 2Q04 do Page 2