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'I <br /> monitoring gradient data is included in Table 3. The PHS/EHD further stated that after <br /> gradient confirmation "additional monitoring wells may have to be installed to ensure that <br /> a down gradient well is provided. Currently MW-3 is up gradient of the tank pit and is the <br /> well with the highest contamination in the groundwater."However, subsequent groundwater <br /> flow direction calculations have shown MW-3 to be down gradient of the former USTs. <br /> 3.0 PROCEDURES <br /> 3.1 Monitoring Well Purging <br /> On August 31, September 27 and October 28, 1994, the water levels in each well were <br /> 1 measured relative to the top of the casing using a Solinst water level meter (Table 3). No <br /> free hydrocarbon product was observed in any of the wells. <br /> ' After water Ievels were measured on September 27, a bailer was used to remove standing <br /> water from each well to stabilize temperature, pH and conductivity (Appendix A). <br /> Groundwater parameters were measured at one-galIon intervals using an ICM water <br /> ' analyzer. The purge water was stored in 55-gallon drums on-site. <br /> Five gallons of water were removed from MW-2. However, MW-1 was bailed dry after <br /> removing only two gallons of water. Less than one gallon of water was removed from MW-3 <br /> before it went dry. <br /> 3.2 Sample Collection and Analysis <br /> After purging, water samples were collected using disposable plastic bailers. Samples from <br /> MW-1 and MW-2 were collected on September 27, 1993; because of poor recharge, MW-3 <br /> was sampled on September 28, 1994. <br /> ' Each sample was collected in three 40-m1 EPA vials. The samples were then placed in a <br /> chilled container and transported under chain-of-custody procedure to Alpha Analytical <br /> ' Laboratories in Ukiah, California. Each sample was analyzed for TPH as stoddard solvent <br /> and BTE&X in accordance with EPA methods GCFID/5030 and 602, respectively. <br /> ' 4.0 FINDINGS <br /> 4.1 Groundwater Elevation and Gradient <br /> The elevation of groundwater in each well was calculated by subtracting the groundwater <br /> depth from the surveyed casing elevation (Table 3). The average depth to groundwater at <br /> the site in August, September and October 1994 was 42.82 feet, 43.10 feet and 42.93 feet, <br /> respectively. This represents approximately a one-quarter foot drop and then rise in <br /> ' v.,bpal A.&Sery^I— C <br /> tom.-a6.:oR3no-susn 6 <br /> l,` <br />