ARCHIVED REPORTS_XR0003876 - Laserfiche WebLink

Home Browse Search

' to coal reclaucslnc Page 6 � g g Groundwater Momtonng Report Project No 770 2 June 15,2004 ' • Diesel range petroleum hydrocarbons were detected in three of the site's eleven monitoring wells ' • Well MW-5 contained 2280 gg/1 diesel and remains the most severely impacted well The reversal in groundwater direction discussed above may be the reason that the core ' plume is displaced from the location of the former UST a Gasoline range petroleum hydrocarbons (TPH-G) were not detected in any of the wells for this event Several wells have had at least one event in which TPH-G was detected ' * Minor BTEX constituents are present at levels ranging from 0 4— 1 7 µg/l in wells MW- 4, MW-5, MW-6 and MW-7 0 Motor oil range petroleum hydrocarbons were not present in any of the groundwater samples at concentrations above the laboratory reporting limits • Deep wells MW-104, MW-105 and MW-106 did not contain contaminant ' concentrations above the laboratory reporting limits Well MW-105 intermittently contains diesel contamination • The lateral extent of the diesel groundwater plume is currently undefined to the south ' • The vertical extent of the plume is intermittently defined by MW-104, 105, & 106 ? a Oxidation-Reduction Potential (ORP)measurements show that several monitoring wells are within the reaction depleted water caused by biodegradation of the contamination plume Wells MW-1, MW-2, MW-3, MW-4, MW-5, MW-7 and MW-105 exhibited negative ORP values and all of the wells' ORP data are included in Table 5 of Appendix A The other wells have varying positive values suggesting that the water around these wells is outside of or on the outer fringe of the halo of impacted groundwater ' An examination of the contaminant distribution and groundwater flow direction data doesn't reveal any obvious trends A consistent factor previously noted in the investigation was the increase in diesel concentrations in well MW-5, see Figure 6- MW-5 TPH-D vs ' Groundwater Elevation The concentrations had previously demonstrated an increasing trend until June 2002 when wide fluctuations began The plot in Figure 6 suggests that a previously direct relationship between groundwater elevation and contaminant ' concentrations has reversed since June 2002 Well MW-4 lies adjacent to the former UST field Figure 7- MW-4 TPH-D vs ' Groundwater Elevation suggests that a predominantly inverse relationship exists between groundwater elevation and contaminant concentrations ' Well MW-5 continues to contain the highest concentrations of detected contaminants (see Figure 8) It has not been down gradient of the former UST location for the monitoring events completed by GTI to date The reason for this anomaly is not known, but could be related to geologic units that slope to the west None of the deep wells contained laboratory contaminants concentrations above the laboratory reporting limits and therefore a contour was not developed r