ARCHIVED REPORTS XR0011348 - Laserfiche WebLink

Home Browse Search

GeoCogtcaC7ec(utus Inc - J --- - - - -- — -_ -- - - Page 5 -—-- -- — - - - - Groundwater Monitoring Report Project No 425 2 �. August 12, 1999 ' • Concentrations in MW-2 showed a significant increased from the Nov 1998 event Concentrations are within values observed in this well previously See Figure 4 for ' graph of Benzene and TPH-G versus time in MW-2 • Concentrations in MW-4 showed a decrease in BTEX and TPH-G from past monitoring events This event marks the lowest values in MW-4 observed to date 1 • MW-5 showed an increase in BTEX and TPH-G from the Nov 1998 events • MW-102 showed an increase in BTEX from the Nov 1998 events 0 MW-202 showed a slight decrease in BTEX as compared to the Nov 1998 event TPH- G is still non-detect a One of the three domestic wells (1600 Durham Ferry) associated with the site contained trace concentrations of Benzene The other two were non-detect for BTEX and TPH-G compounds 3.0 CONCLUSIONS AND RECOMMENDATIONS The following conclusions have been drawn regarding the status of the groundwater at this site and recommendations for future work Conclusions 1 The water table groundwater gradient historically flows in a northern direction at about 0 002 ft/ft However, the past year the gradient has shifted towards the east ' 2 Vertical groundwater gradients have been found to be flowing upward early spring and downward during late spring and summary 3 Petroleum hydrocarbons are present in 6 of the 12 monitoring wells and 1 of the 3 ' domestic wells 4 The shallow water table groundwater plume is laterally defined except to the west 5 Free-floating gasoline was not present in MW-2 in April 1999, but typically is present in late fall and winter months 6 Petroleum hydrocarbons in the groundwater at the site appear to have fluctuating ' concentrations with each monitoring event 7 It appears that groundwater contamination may be migrating vertically into the deeper aquifers since both MW-102 and 202 and DW-1600 D F contains BTEX contamination ' 8 Two other domestic water wells, located within about 150 feet down gradient from MW- 2, continue to be non-detect for gasoline compounds 9 With several domestic wells associated with the residence surrounding the property and ' the wells for the elementary school located a short distance northeast of this property, this groundwater plume appears to continue to pose a significant threat to public health and the environment 1 t