ARCHIVED REPORTS XR0009113 - Laserfiche WebLink

Home Browse Search

10 August 2005 AGE-NC Project No. 97-0301 Page 5 of 6 (, • Generally,a steep downward vertical gradient was observed from wells W'1,MW-9,and IMW-12 and between the Second Water Zone, Third Water Zone, and Fourth Water Zone; near neutral vertical gradients were observed between the First Water Zone and the Second Water Zone in the southern portion of the site (Figure 3). • Analysis of ground water samples collected from MW-2 and MW-7 suggest the dissolved plume is comprised of TPH-g, BTEX, and 1,2-DCA. The core of the First Water Zone dissolved gasoline plume appears to be currently distributed near the location of well MW-7 and extending towards wells MW-4 and MW-9A; and contained within network of wells yS consisting of MW-2, MW-3, MW-6,.MW-10A, MW-11A, and MW-12A (Figure 5). (MvJ_ 6`@-,V Substantial concentrations of dissolved TPH-d and TPH-k have previously been detected in • .water samples collected from wells MW-1 and MW-7, indicating a limited distribution of ' TPH-d and TPH-k in the area assessed. However, for the seventh consecutive quarterly monitoring event, TPH-d, TPH-k, and TPH-mo were not detected from any of the twenty- two water samples analyzed. ' BTEX concentrations in ground water samples MW-4,MW-7,and MW-9A were above the Maximum Contaminant Levels in drinking water. iVery low concentrations of M ,TAM , and have been detected at wells Mv�;114W-�, MW-3;1V1W-4;MW � W-7, indicating that there is only a minor impact of these components. • 1,2 DCA was detected for the first time since sampling began in wells MW-10A,MW-10B, MW-10C and MW-12C. 1,2-DCA-impacted ground water extends to 95-100 feet bsg in the I area of wells MW-10 and MW-12. However,dissolved 1,2-DCA does not appear to extend vertically beyond 100 feet bsg. ~' I • 1,2-DCA concentrations in ground water samples MW-7, MW-9A, MW-IOA, MW-IOB, MW-l OC and MW-12C were detected above the Maximum Contaminant Levels in drinking water. 5.0, RECOMMENDATIONS Based upon data collected during the I'Quarter 2005, AGE recommends: ! Continued ground water monitoring utilizing wells MW-1 through MW-12; the second quarter 2005 ground water monitoring event was performed on 13 June 2005. • If applicable,conduct future groundwater monitoring events concurrently with the Cal-Tank Lines site (3105 South El Dorado Street). ' Advanced GeoEnvironmentai,Inc.