Laserfiche WebLink
i <br /> ' .2 Monitoring Well Pure Procedures <br /> . 3 g g <br /> I' On December 8, 1994, a submersible pump was used to purge MW-1, MW-4 and MW-5. <br /> Approximately 100 gallons of water were removed from from MW-5; approximately 70 <br /> gallons of water were removed from MW-4 and an additional 50 gallons of water were <br /> 1 removed from MW-1.Temperature, pH and conductivity were measured at regular intervals <br /> during pumping using an ICM water analyzer. The purge water was placed in the above- <br /> ground "Baker" tank on-site. Field data sheets are included in Appendix A. <br /> 3.3 Groundwater Sample Collection <br /> ' Water samples were collected from MW-1, MW-4, and MW-5 using new disposable plastic <br /> bailers. Three 40-m1 EPA vials of water were collected from each well. One 1-liter amber <br /> bottle of water was also collected from MW-1. Samples were transported in a chilled <br /> ' container under chain-of-custody to Western Environmental Science &Technology (WEST) <br /> in Davis. Each sample was analyzed for total petroleum hydrocarbons (TPH as gasoline) and <br /> volatile aromatics (BTE&X) in accordance with EPA methods 80151n and 602, respectively. <br /> t The sample from MW-I was also analyzed for TPH as diesel. <br /> ' 4.0 FINDINGS <br /> 4.1 Groundwater Elevation <br /> The relative groundwater elevations for the monitoring wells were calculated by subtracting <br /> ' the groundwater depth from the surveyed relative casing elevation (Table 1). Comparison <br /> of the September and December 1994 measurements indicate that groundwater at the site <br /> has risen an average of 0.88 feet since the September monitoring. This rise in groundwater <br /> ' is in accordance with normal seasonal variation. <br /> 4.2 Groundwater Flow Direction and Gradient <br /> t <br /> Groundwater flow direction at the site was calculated to be northeast. The flexure in the <br /> groundwater flow direction was significantly less pronounced during the December 1994 <br /> ' monitoring (Figure 3) compared to previous monitoring events. <br /> 4.3 Groundwater Sample Results <br /> ' <br /> TPH as gasoline, diesel and benzene were detected in the water sample from monitoring <br /> well MW-1 at concentrations of 150 ppb, 170 ppb and 5.8 ppb, respectively. Benzene was <br /> ' detected in MW-4 at a concentration of 1.6 ppb. No other petroleum hydrocarbons were <br /> detected in any of the samples analyzed. The analytical results of the groundwater samples <br /> are summarized in Table 2. The laboratory report and chain of custody are included in <br /> ww..�[awvu.uv-c.Eo <br /> 1 <br />