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r ' 1 • Page 3 3.1 Site Location and Description The site is located in an essentially flat area of the Sacramento Valley The surrounding parcels are principally devoted to commercial uses 4.0 MONITOR WELL SAMPLING r 1 4.1 Sampling Procedures Monitor well samples were obtained on April 18, 1996 Upon arrival at the site, all wells were opened and allowed to equalize with atmospheric pressure Approximately thirty minutes after opening, a Solinst water level meter was used to measure the depth to groundwater in each of the wells After water levels were obtained, wells TT-1, 2, and 3 were purged of 11 to 13 gallons of water using a portable pump During the purging process the recovered water was tested with a Corning pH, Temperature and Conductivity instrument at 2-5 gallon intervals Purging continued until pH and Conductivity had stabilized (Appendix A) Domestic well DMA was purged of 30 gallons Purged water was placed into a sealed and labeled 30 gallon drum and stored on site Following each well,the purge pump was cleaned with TSP/water solution and rinsed After purging, the wells were allowed to recharge prior to sample collection Samples were collected using new disposable bailers for each well Samples were collected from the upper thirty (30) inches of the water column and were poured in sterilized bottles, labeled and placed in a pre-cooled ice chest The samples were subsequently transported via chain-of- custody hain-ofcustody to Excelchem Environmental Labs 4.2 Depth to Groundwater Depth-to-groundwater measurements, calculated groundwater elevations, and physical j observations for monitor wells TT-1, 2, 3 and DM-1 are presented in Table 1 and Appendix A Water levels have risen slightly more then one foot since February 20, 1996 The average depth is nearly 54 feet below surface grade 4.3 Groundwater Gradient Figure 3 illustrates the present direction of groundwater flow in general the direction of groundwater flow is to the east at 0 00095 feet per foot (1 14 mch/100 feet) The direction of flow is consistent with the direction previously reported However, there is a slight flexure in the flpw direction caused by a slightly higher groundwater measurement obtained at DM-1 Itis possible the slight variation may be attributable to measurement error The measurement obtained from DM-1 may not be accurate as the condition of the casing of DM-1 was rough and m4y not have been obtained from the same location as was measured on February 20 4.4 Analytical Results Groundwater samples from monitor wells TT-1, 2, 3 and DM-1 were analyzed for TPH-gasoline and TPH-diesel (EPA method 8015) and volatile aromatic hydrocarbons (EPA method 602) The results from these laboratory analyses are summarized in Table 2 The laboratory report is presented in Appendix B Analytical results from previous sampling events are included in Table 2 for comparison purposes