Laserfiche WebLink
1 <br /> Executive Summary <br /> On behalf of the Division of the State Architect (DSA), IT Corporation (IT)has completed an <br /> environmental site investigation to define the vertical extent of soil impacted by Total Petroleum <br /> ' Hydrocarbons (TPH)-as diesel and to determine of groundwater has been impacted by TPH-as <br /> diesel near a former underground storage tank(UST) area containing five USTs at the Stockton <br /> Developmental Center This investigation included obtaining soil samples from four Geoprobe <br /> locations in the two remaining Areas of Concern (AOCs) at the former UST area <br /> ' Observations and chemical data collected dunng tlus investigation indicate that diesel <br /> hydrocarbons have not impacted the soil in the vicinity of the former location of the USTs Field <br /> observations and the absence of impacted soil also support the assumption that groundwater has <br /> not been impacted by a release from the former UST area Geoprobe soil samples were collected <br /> ' from the two remaining ADCs which previously exhibited elevated concentrations of TPH-as <br /> diesel the northern end of the western-most UST which exhibited a soil concentration of 180 <br /> ' ppm TPH-as diesel at 14 feet below grade, and the northern end of the fourth.UST (second from <br /> the east) which contained 7600 ppm TPH-as diesel at 16 feet below grade Samples were <br /> collected at five foot intervals at these locations and were analyzed for TPH-as diesel and BTEX <br /> None of the samples collected to a depth of 25 feet at either location exhibited concentrations of <br /> either parameter above the method reporting limit <br /> Previous work performed by IT at a site approximately 1500 feet north of the subject site <br /> ' indicated that the depth to groundwater an the area is expected to be between 45 and 50 feet <br /> below ground surface (bgs) This depth to groundwater was also confirmed by the onsite <br /> regulator Based on soil sampling results which indicate non detectable levels of TPH-as diesel <br /> and BTEX to a depth of 25 feet bgs in the two remaining AOCs, a groundwater depth of 45 to 50 <br /> ' feet bgs, and guidance from the onsite regulator, it was determined that it would not be necessary <br /> to obtain groundwater samples as part of this investigation It as recommended that a specific site <br /> closure be approved for this former UST area <br /> ' SAC/08-29-97/ENG/771744 1 <br />