ARCHIVED REPORTS_XR0006926 - Laserfiche WebLink

Home Browse Search

, 1 I `I � F ! I I i I I I ' 15'S6tember 2003 AGE-NC Project No 97-0333 ' Page 10 of 11 • Third Zone ground water flow was inferred to be radially outward from a northwest- southeast trending ground water mound in the area of wells MW-7D; MW-11D and MW- 12D at an approximate gradient of 0 002 ft/ft or less (Figure 6) • Primary Aquifer ground water flow was inferred to be radially inward towards a northwest- southeast trending ground water trough in the area of wells MW,7F,MW-9D and MW-11 E at an approximate gradient of 0 004 ft/f1 or less (Figure 7) • Due to the low ground water gradient at the site, small variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly ' modify the inferred ground water flow direction • The highest on-site concentrations of dissolved MTBE were detected in the samples collected in the area of First Zone monitoring wells MW-2 and MW-6 at concentrations as ' high as 150,000µg/1 Lower concentrations of on-site MTBE were detected in water samples from First and Second Zone monitoring wells MW-1, MW-3; MW-4, MW-7 (A-C) and ' MW-8 (B-C), generally, significant MTBE increases were reported this quarter in most of, the on-site wells (Figures 8 and 9, Table 3) �I • Off-site MTBE was reported only in the water sample from Second Zone monitoring well ' MW-12B and Third Zone monitoring well MW-13Dat concentrations of 24µg/1 and 52µg/l, Irespectively III I „ 1 • Concentrations of PCE and/or TCE have been detected in water samples collected from all 1 ` !well locations associated with the Rainwater Car Wash investigation Minor to significant PCE and/or TCE concentrations were detected in 41 of 47 ground water monitoring wells located in First Zone, Second Zone,Third Zone and Primary Aquifer Zone Aquifers(Figure ; 10, Table 4) The highest concentrations of dissolved,PCE were detected in:the samples collected in the area of on-site wells MW-4 (First Zone) and offsite well MW-112A (First ' 1� Zone) at concentrations as high as 1,300 µg11 • PCE and TCE are chlorinated solvents often associated with dry cleaning operations Based ion a Jime 2003 PCE isoconcentration inap'm First Zone water (Figure 10), AGE interpIrets' ' I I! i ',the.kE/TCE-plume to have onginated from the dry cleaner's facility located immediately, east of the Rainwater Car Wash'I I 1 I I i I 11 5.0 RECOMMENDATIONS SII I I Based upM,data`collected from the site, AGE recommendsti I ,l' i ''I i R' • Contmued;quarterly'ground water monitoring and sampling! of monitoring wells MW-1 E I through MW-13 I i f I I I Advanced GcoEnviroamental,Inc I � I i I I i it x I i I II I 'r Illi � II I SII I I IVB I I I I I I I I I i � I i t 1 i i I�