Laserfiche WebLink
1 <br /> 1 <br />' collected on February 3, 1992 from the sidewalls of the excavation, <br /> confirming the successful removal of contaminated soil (Table 1) . <br /> Monitoring wells were installed in May 1992 , and groundwater <br />' samples were collected in June, September, and December 1992 (Table <br /> 2) . Concentrations of dissolved hydrocarbons have declined over <br /> this period. <br /> 3. 0 PROCEDURES <br /> 3.1 Purge Procedures <br /> The forth monitoring event was conducted on March 18, 1993 . A <br />' Solinist water level meter was used to measure the depth to water <br /> in the three monitoring wells. The standing water was purged using <br /> a three stage purge pump. Water samples were collected after 12 to <br />' 14 gallons (approximately three well volumes) of water had been <br /> removed and temperature, pH and conductivity of the ground water <br /> had stabilized (Table 3) . These parameters were measured at two <br /> gallon intervals using a Hydac water analyzer. The water was <br />' stored on-site in a DOT approved drum. <br /> 3.2 Sample Collection <br /> Water samples were collected using a disposable plastic bailer. <br /> Three 40 ml EPA vials and two 1-later amber bottles of water were <br /> collected from each well and transported in a chilled container to <br />' WEST Laboratories in Davis. Each sample was analyzed for total <br /> petroleum hydrocarbons (TPH as gasoline, diesel, and motor oil) and <br /> purgeable aromatics (BTE&X) in accordance with EPA methods 8015m <br /> and 602 . <br />' 4. 0 FINDINGB <br /> 4. 1 Groundwater Elevation <br /> The relative groundwater elevations for the monitoring wells were <br /> calculated by subtracting the water depth from the casing elevation <br /> (Table 4) . Comparison of the December and March measurements <br /> indicates that water levels have risen approximately 1 foot in all <br /> wells, continuing the rise that began in September. This <br /> continuous rise in water levels over a period of several months is <br />' not consistent with tidal fluctuations and is probably due to <br /> groundwater recharge since the onset of the rainy season. Tide <br /> data are included in Table 5. <br /> As in the previous sampling events, the water level is highest in <br /> MW-3 and lowest in MW-1, confirming that flow is generally to the <br /> south, away from the ship channel. In December, the hydraulic <br />' gradient was 0. 0096 ft/ft to S 330E; present data yield very <br /> similar results: 0. 0093 ft/ft to S 380E (Figure 2) . <br /> 2 <br />