ARCHIVED REPORTS XR0008204 - Laserfiche WebLink

Home Browse Search

. in ground water flow directions, which is usually the case for flat gradients, with a flow direction to the north-northwest in December, 1989, a flow direction to the northeast and southeast in January, 1990, a flow direction to the northeast in May, 1990, a trough that flows from monitor well MW2 towards MW1 in June, 1990, a steep flow to the northwest, towards MW6, in August, 1990 and a flow to the southeast with a basin at monitor well MW1 in September, 1990. The basin that is found at monitor well MW1 in September, 1990 may be explained by the loss of formation water in the vadose zone to the excavation area and the capillary fringe trying to recharge this area above the ground water near monitor well MW1 and/or irrigation of planters and vegetable gardens on ad3oining properties to the west, southwest and south, recharging the ground water directly beneath. The overall ground water elevation beneath this site has showed a decline, with the exception of the month of January, 1990, which showed an increase from 0.520 at monitor well MW2 to an increase of 1.33' at monitor well MW4. Overall the decline in ground water has ranged from 7.81 at monitor well MW4 to 8.44' at monitor well MW1, see Table 3. A review of ground water maps, produced by San Joaquin County Flood Control and Water Conservation District since 1979, indicates that the ten year ground water high was in the Fall of 1983 at 40 feet below the surface. Also evident from these figures are areas of probable ground water pumping (discharge) , forming lows (basins) along the eastern areas of the City of Stockton, which should dictate a flow direction from this site to the east-southeast, see Appendix D. A review of the reports generated from the assessment of the former Cheveron Station, located at the northwest corner of Harding Way and E1 Dorado Street, was inconclusive concerning ground water conditions that may exist at the Regal Station. The existing onsite ground water monitoring wells are dry. Immediately after completion of the wells, the wells were monitored and the ground water flow direction was to the northeast. Soil and ground water contaminated with hydrocarbons does exist beneath this site. ,ZAEMICAL RESULTS-GROUND WATER SAMPLES Ground water samples were -�otained from all six on site monitor wells on August 24, 1990 (MW-1, MW-2, MW-3, MW-4, KWS, and MW6) . Prior to obtaining the ground water samples each well ras purged using a hand bailer, until the temperature, pH, and conductivity stabilized, approximately 5 gallons of water, see Appendix E. This purged water is presently being stored on site in 17E 55 gallon drums. Ground water beneath this site has gasoline range contamination. Only monitor wells MW1 and MW5 are above the detection limits for Total Petroleum Hydrocarbons (TPH) , greater than 0.05 parts per million (ppm) , with 0.1 ppm and 4.0 ppm respectively. Monitor