ARCHIVED REPORTS_XR0011508 - Laserfiche WebLink

Home Browse Search

v ATC A S S O C I A T E S I N C activities and analytical results were detailed in ATC's Summary Report of Additional Subsurface Investigation, dated January 8, 1999 In December 1999, ATC personnel supervised the advancement of soil boirngs MW2, MW3, and MW4 at the site to depths of approximately 65 feet bgs to evaluate groundwater for the presence of petroleum hydrocarbons and determine the gradient direction and magnitude The borings were completed as monitoring wells Analytical data indicated that soil samples from boring MW2 contained detectable concentrations of petroleum hydrocarbons Petroleum hydrocarbons were also detected in the groundwater from well MW2 Well MW3 contained very low concentrations of only a few constituents and well MW4 was nondetect Field activities and analytical results were detailed in ATC's Summary Report of Additional Subsurface Investigation, dated February 24, 2000 In December 2001, soil-boring VEW 1 was advanced to approximately 35 feet bgs, and borings VEW2 and VEW3 were advanced to approximately 45 feet bgs Borings MW5, MW6, and MW7 were advanced to approximately 65 feet bgs Soil borings VEW1, VEW2, and VEW3 were completed as 2-inch diameter vapor extraction wells and soil borings MW5, MW6, and MW7 were completed as 2-inch diameter groundwater monitoring wells Boring CPTl was advanced to approximately 100 feet bgs utilizing a truck-mounted CPT rig A soil vapor extraction pilot test was conducted which yielded a ROI of approximately 30 feet Approximately 2 64 pounds of TPHg and BTEX were removed during the vapor extraction pilot tests Soil vapor extraction appeared to be a viable method for remediating TPHg and BTEX impacted soil at the site Field activities and analytical results were detailed in ATC's Remedial Investigation/Feasibility Study, dated October 21, 2002 GROUNDWATER ELEVATION Water level measurements were collected from wells MW 1 through MW7 on October 25, 2002 Water elevations ranged from a high of —31 89 to a low of —32 10 representing an average decrease in water table elevation of 3 20 feet since December 2001 The water level data were used to develop the groundwater elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed generally towards the south The average hydraulic gradient on October 25, 2002 was calculated to be 0 0006 ft/ft or approximately 3 ft/mile A summary of groundwater monitoring data is presented in Table 1 SAMPLING ACTIVITIES On October 25, 2002, groundwater samples were collected by ATC personnel from monitoring wells MW 1 through MW7 The locations of the monitoring wells are shown on Figure 2 Prior to collection of the groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in each monitoring well and recorded A minimum of three well casing volumes was purged from each well prior to sampling The wells were allowed to recover w lwordpro%257714QR-2002 doc 2