WORK PLANS - Laserfiche WebLink

Home Browse Search

Workplan for Additional Assessment 49 South Wilson Way May 4, 1998 Page 3 December 1997, Follow-up Phase II Subsurface Investigation Building Analytics completed a Follow-up Phase II Subsurface Investigation in September and October 1997, which included the installation of one additional monitoring well, and the sampling of the new monitoring wells and three previously installed monitoring wells. The following is a summary of the findings from the expanded investigation: • The groundwater flow direction was measured to be to the northeast with a hydraulic gradient of 0.0055; • TPH-g up to 75 ppm were reported in the soil samples collected from Boring B4 at depths between 35 and 45 feet bgs; • Benzene up to 0.057 ppm was reported in the soil samples collected from Boring B4 at depths between 35 and 45 feet bgs; • TPH-g and BTEX were not reported in groundwater samples collected from monitoring wells MW-1 or MW-3; • TPH-g was reported in the groundwater samples collected from MW-2 and MW- 4 at concentrations of up to 3.4 ppm; • TPH (Carbon Range C8-C44+) was also reported in the groundwater sample collected from MW-2 at a concentration of 2.3 ppm; • Benzene was reported in the groundwater samples collected from MW-2 and MW-4 at concentrations of 1.2 ppm and 11 ppm,respectively; and • MTBE was not reported in the soil or groundwater samples collected. The report was submitted to PHS/EHD, and Building Analytics received the following comments/directives in a letter date stamped January 20, 1998: - "PHS/EHD has obtained historical photos of the above referenced site dated approximately 1950 which clearly indicate the facility and fuel dispensers near the South Eastern corner of the parcel. The location(s) of the tank(s) are currently unknown. A photo copy of the enlarged and cropped print from the upper left hand comer of the original negative -is enclosed with a record identification reference sheet. Copies may be obtained from the Bank of Stockton Archives Office,the contact person is Leslie Crow at (209) 941-1575. This photo should be evaluated against Sanborn Fire Insurance Maps and other available data to better evaluate the site which we understand your consultant has in their possession. This data comparison may allow all parties involved to better predict contaminant source locations and resolve site characterization problems more efficiently thereby allowing the site to achieve case closure more rapidly. "Additional boreholes shall be distributed at this site. Groundwater flow direction is reported as North/North-East. Given the documented groundwater contamination at this site in the South-Eastem are of this parcel, additional 3 198075-WFB Stockton.Workplan