ARCHIVED REPORTS_XR0002276 - Laserfiche WebLink

Home Browse Search

First Quarter Monitoring and Sampling Report, 1993 April 14, 1993 • Southland Site No. 20304, 455 Grant Line Rd., Tracy, CA 2 casing using an QRS Environmental Equipment INTERFACE PROBE Well Monitoring System. Attachment 2 includes Groundwater Technology's Standard Operating Procedures for groundwater monitoring. Separate-phase hydrocarbons were not detected in any of the monitoring wells. The water-table elevations calculated from the March 11, 1993, monitoring data were used to prepare a potentiometric surface map (Figure 2). Wells MW-9 and MW-10 are screened into a shallow or perched water-bearing zone. Because wells MW-9 and MW-10 have repeatedly shown groundwater elevations different from those in the surrounding wells, they were not used to calculate the potentiometric groundwater surface. Data from monitoring well MW-11 indicated an anomalous groundwater elevation and therefore was not used to calculate the potentiometric groundwater surface. The potentiometric surface elevation as measured in the groundwater monitoring wells increased an average of 0.31 foot since the December 28, 1992, monitoring event. The groundwater flow direction is toward the north-northeast with a hydraulic gradient of approximately 0.003 foot per foot (ft/ft). The historical and current water-level measurements are presented in Attachment 3, Table 1. MONITORING WELL SAMPLING AND ANALYTICAL RESULTS On March 11, 1993, groundwater samples were collected from 11 monitoring wells (MW-1 through MW-6 and MW-8 through MW-12). Monitoring well MW-13 and MW-14 are sampled on an annual (January) basis because historically the analytical results have reported concentrations below the method detection limits. Before sampling, at least 4 well-casing volumes of groundwater were removed from each of the monitoring wells unless the wells were purged dry. Field measurements of temperature, conductivity, and pH were recorded during well purging (Attachment 4). The groundwater samples were collected using a Teflon® sampler and placed in analyses-specific sample containers with analyses-specific preservatives. The samples were then sealed and labeled with the job identification number, the sample number, date, time, and type of laboratory analysis required. The samples were stored on ice and transported under chain-of custody protocol to GTEL Environmental Laboratories, Inc. in Concord, California. The groundwater samples were analyzed for BTEX, TPH-G, and TPH-D by the methods noted above. The samples from monitoring wells MW-1, MW-2, and MW-4 were also analyzed for pH, nitrate, chloride, and sulfate. The sample from MW-1 was also analyzed for total lead, pesticides, polychlorinated biphenyls, and for volatile organics. Figure 3 illustrates the distribution of benzene and TPH-G. Tables 2 and 3 summarize the analytical results of this sampling event and the historical analytical data. The laboratory analytical reports and the chain-of-custody records for the March 11, 1993, samples are included in Attachment 5. R3767A1.SCH GROUNDWATER ��.._�i_�TECHNOLOGY INC.