ARCHIVED REPORTS XR0010403 - Laserfiche WebLink

Home Browse Search

Hydrocarbon as gasoline (TPHG) ; Benzene, Toluene, Ethylbenzene and Xylene (BTEX) . The soil samples taken below the UST in native soil showed 4 , 300 and 540 parts per million (ppm) TPHG at 6 . 5 and 9 feet below grade. The results of these analysis were documented in a report by JPCA dated August 12 , 1996. Soil was excavated to about 10 feet and aerated. The excavation was left open for approximately one year. The excavation was back filled with clean fill in October 1997. Four Monitoring Wells were constructed in November 1997. The soil in the upper five feet had minor concentrations of hydrocarbon contamination. No detectable contamination for the Oxygenates was found in the soil samples. The groundwater had less than 1 ppm TPHG and 20 ppb Benzene contamination. One groundwater sample from MW-3 had 5.6 ppb of MTBE contamination. The remaining groundwater samples had no detectable concentrations, ie < 5 ppb, of oxygenates. San Joaquin County Public Health Services, Environmental Health Division (SJCEHD) requested quarterly sampling and a well survey within 2,000 feet of the former UST area. FIELD WORK On March 26, 1998 , John P. Cummings of JPCA purged the wells and collected groundwater samples from the 4 Monitoring Wells and the non Functioning "potable" water well as required by SJCEHD. Gradient Calculation Prior to purging and sampling the depth to groundwater was measured by an electronic probe in the four Monitoring Wells on site. The water depth was measured from a mark located on the top of the casings. The groundwater gradient data are presented in Table 1. The gradient calculated for the monitoring wells is N260W or 3340 . The groundwater gradient is depicted in Figure 3. Survey and well data are in Appendix A. TABLE 1 Groundwater Elevations (ft) - March 26, 1998 Well ID op of Casing Depth to Water Groundwater Elevation MW--1 50.81 9. 13 41.68 MW-2 50.42 8 .90 41.52 MW-3 49.19 7. 66 41.53 MW-BT1 49.65 8. 01 41.64 2 I