ARCHIVED REPORTS XR0002719 - Laserfiche WebLink

Home Browse Search

pp hydrocarbon concentrations in impacted soil off-site are much greater than concentrations of the remaining impacted soil on-site. 5.2 Petroleum Hydrocarbon Impacted Groundwater ' No petroleum hydrocarbon impacted groundwater was detected in any wells on-site prior to September 1993. The hydrocarbons detected in samples from MW(jkTPH as gasoline: 140 ppb; TPH as diesel: 80 ppb) and MW-5 (TPH as diesel: 150 ppb) on September 13, ' 1993, were not confirmed during the next sampling on Janu ry 31, 1994. However, in January TPH as diesel was detected in the sample from M'�90 ppb)/17 During the most recent sampling event,April 13, 1994, TPH as diesel was detected in MW-4 (84 ppb). No other hydrocarbons were detected in any of the monitoring wells. Several factors should be noted when considering a potential source of impacted groundwater: 14 ' petroleum hydrocarbpAs have not been detected or confirmed in any well for two consecutive quarte - istoricaI information does not indicate that diesel fuel was stored or sold at the site; 3 petroleum hydrocarbons have only been detected intermittently ' ' monitoring wells along the north portion of property, adjacent to Harding Way; an 4) groundwater flow direction has remained consistent (northeast) at the site for at least the ' past year. These factors all make it likely that there is a source of diesel (or other heavier hydrocarbon compounds) beneath Harding Way, or possibly west of the site, that intermittently impacts i groundwater at the site. Since groundwater flow direction is northeast, this source is likely located equigradient (beneath Harding Way) or up-gradient (west of the site) to MW-1 and MW-4. The concentrations of diesel detected.in the groundwater samples are very close to the detection limit of 50 ppb. We do not believe that the groundwater beneath the site has been significantly impacted as a result of the former operation of UST's at the site. We believe that hydrocarbons detected intermittently in groundwater along the north edge of the property are the result of a ' shallow petroleum hydrocarbon source beneath Harding Way (or elsewhere) and therefore, it is not the reuhtWe do not recommend any further groundwater investigation at the site. ' 5.3 Drum and Stockpile Soil Sampling P P g ' lNo petroleum hydrocarbons were detected in composite soil sample Y-1, Y-2 and Y-3. Therefore, ordinary disposal procedures are appropriate. ' No petroleum hydrocarbons were detected in composite water sample D-1, D-2 and D-13. Therefore, we recommend that the water contained in these drums be discharged on-site ' and the empty drums removed. C�b&W A.&S-M� 13 47YSRRb4VYeLw Subvrriae