ARCHIVED REPORTS XR0011394 - Laserfiche WebLink

Home Browse Search

r Geologtca[Teckntrsl�cc Page 5 Groundwater Monitoring Report 16 Project No 425 2 August 6,2004 ' • MW-3, MW-6, MW-7, MW-2X, MW-102, MW-105, MW-107, MW-202 and all sampled domestic wells were non-detect above laboratory reporting linuts for all ' analyzed constituents • MW-1, MW-4, MW-101 and MW-201 showed low levels of TPH-G and BTEX ' constituents • MW-2 showed high concentrations of TPH-G and BTEX constituents during this monitoring event and also in the historical data The monitoring wells MW-2X (42- 50 ft bsg), MW-102 (55-60 ft bgs), and MW-202 (70-85 ft bgs) do not show any contamination This indicates that contamination did not move to the deeper zones of water near MW-2 (the place of highest contamination) • MW-5 showed moderate levels of TPH-G and BTEX constituents • Total Xylene (0 4 [ig/L), and TPH-G (172 µg/L) have been detected in MW-106 • During this monitoring event, MW-8 shows the contamination from TPH-G and BTEX constituents, but the historical data from MW-8 shows that there was not any contamination It is not clear if the contaminated plume reached MW-8 or the contamination is a sampling error, the next monitoring event will clarify this point 3.0 FINDINGS AND DISCUSSION The laboratory analytical data generated during the April 27, 2004 groundwater-monitoring event indicates that TPH-G and BTEX constituents have been detected in monitoring wells MW-1, MW-2, MW-4, MW-5,MW-8, MW-1.06 and MW-201 ' The results of the April 2004 event are comparable with the results from previous monitoring events The following observations are made • The horizontal groundwater gradient, calculated from the water table wells, is currently ' towards the north • The gradient calculated from the intermediate wells is to the northeast • Vertical groundwater gradients were positive in the shallow/intermediate well pairs and ' positive in the intermediate/deep well pairs • TPH-G concentrations in MW-1 continue to fluctuate within levels usually observed for the site The concentration of TPH-G in MW-1 measured during the April 2004 event ' were the lowest recorded at the site m three years See Figure 7 for a graph of Benzene and TPH-G versus time (MW-1) and Figure 8 for a contour map showing the distribution of TPH-G at the site ' • Contaminant concentrations in well MW4 exhibit a historically static trend • Contamination in monitoring well MW-5 fluctuates seasonally but exhibits an overall ' increasing trend This quarter shows the highest concentrations of TPH-G in MW-5 to date • For the fourteenth consecutive event, well MW-102 did not contain contaminant concentrations above the laboratory reporting limits