ARCHIVED REPORTS_XR0004447 - Laserfiche WebLink

Home Browse Search

Fourth Quarter 2003 Groundwater Monitoring Report Boyett Petroleum,419 S.Main,Manteca,CA Page 3 . TABLE 1: Laboratory Analytical Results for MTBE and Groundwater Elevation Data (October 31, 2003) iV[onitoring MTBE t Depth to Groundwater Well Sample I.D. TOC Elevation Z !L Groundwater Elevation MW-2 NS NS 35.97 DRY NM MW-3 NS NS 36.18 22.42 13.76 MW-4R NS NS 35.21 NM NM MW-6 NS NS 36.07 DRY NM MW-7 NS NS 36.42 DRY NM MW-8 NS NS 36.43 23,35 13.08 MW-9 3761-MW9-10/31/03 1.4 3595 25.02 10.93 MW-10 NS NS 36.09 NM NM MW-11 NS NS 36.15 NM NM EW-1 NS NS 36.23 NM NM `TOC Elevation:Elevations are referenced to NAD83 datum,NCS Benchmark HS 4486. Groundwater Elevation:Elevations are measured from the top of the well casings and are referenced to the benchmark indicated above, Monitoring wells MW-1,MW-4,and MW-5 were destroyed October 29,2003 Monitoring wells MW-4R,MW-10,and MW-1 1,and extraction well EW-1 were installed October 30,2003;these wells had not been developed prior to the October 31,2003 monitoring event Monitoring wells MW-3 and MW-8 had insufficient water column to purge and sample Unit Conversions: uglL:parts per billion(ppb) NM =Not Measured Alt measurements are in feet. Analytical: MTBE=methyl tertiary-butyl ether NS=Not Sampled NOVEMBER 26 2003 MONTHLY MONITORING EVENT . On November 26, 2003, a Condor representative was on site to measure water levels and collect groundwater samples for MTBE laboratory analysis from monitoring wells MW-2, MW-3, MW-4R, MW-6 through MW-11, and extraction well EW-1. Monitoring well MW-6 was dry, and MW-2 and MW- 7 contained an insufficient water column for sampling. Monitoring wells MW-3, MW-4R, and MW-10' purged dry and were allowed to recover prior to sampling. Due to an error by the field technician, MW-8 was not measured or sampled during the November 2003 monitoring event. Field observations included water level measurement, appearance of samples (color, clarity, and presence of petroleum product sheen or phase in samples), and collection of water quality field parameters. No floating product, sheen, or odors associated with petroleum hydrocarbons were observed in the groundwater inspection samples from the monitoring wells during the November 26, 2003 groundwater monitoring event. Depth to water measurements indicated that the average groundwater elevation was 12.44 feet on November 26, 2003. Groundwater elevation data for the November 2003 monitoring event are presented in Table 2, on the following page, and Figure 5, attached. The extremely low groundwater levels in the monitoring wells prompted concerns regarding the reliability of water level measurements; the water level in MW-2 and MW-7 may be residual groundwater ponded in the "cap" at the base of the well casing. Consequently, groundwater elevation contours were not estimated; however, an estimated groundwater gradient of 0.0315 ft/ft towards the southwest was calculated using water level data from monitor wells - MW-4R, and MW-10. The Groundwater samnles were analvzed for MTRP i,i, PPA MPrhnA R)rOP 61, Ar"nn r ohnrnhn analytical results indicate that MTBE was detected in the groundwater samples collected from MW-4R, • MW-9, MW-10, MW-11, and EW-1. The laboratory analytical results for the November 2003 monitoring 1 �� CONDOR