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A S S O C I A T E S I N C <br /> and groundwater are impacted by petroleum hydrocarbons Site activities were summarized in <br /> ATC's Summary Report of Subsurface Investigation, dated January 15, 1999 <br /> In December 2000, ATC personnel supervised the advancement of one cone penetrometer (CPT) <br /> boring to 140 feet bgs Also in December 2000 ATC personnel supervised the advancement of <br /> four soil borings to 80 feet bgs and one soil boring to 100 feet bgs The soil borings were <br /> converted into groundwater monitoring wells Analytical results of soil samples and <br /> groundwater samples indicated that soil and groundwater are impacted by petroleum <br /> hydrocarbons Site activities were summarized in ATC's Summary Report of Additional <br /> Subsurface Investigation, dated March 6, 2001 <br /> In September 2001, ATC supervised the advancement of four geoprobe soil borings, SBI <br /> through S134, and eight hollow stem auger borings Soil borings SB 1 through SB4 were <br /> advanced to first encountered groundwater, approximately 61 feet bgs, boring AS 1 was advanced <br /> to approximately 85 feet bgs, borings PZ 1 a and PZ 1 b were advanced to approximately 80 feet <br /> bgs, borings V W 1, V W2, and V W3 were advanced to approximately 65 5 feet bgs, and borings <br /> MW9 and MW10 were advanced to approximately 81 feet bgs Soil boring ASI was completed <br /> as a 4-inch diameter air sparge well with two 2-inch diameter piezometers located in the same <br /> borehole Soil borings PZ 1 a and PZ 1 b were completed as 2-inch diameter piezometer pairs <br /> Soil borings V W 1, V W2, and V W3 were completed as a 2-inch diameter vapor extraction wells <br /> and borings MW9 and MW 10 was completed as a 2-inch diameter groundwater monitoring well <br /> On October 31 and November 1, 2001, ATC performed a short-term vapor extraction test and a <br /> long-term vapor extraction test On the first day, a short-term vapor extraction test was <br /> approximately 2 hours in length and on the second day, a long-term vapor extraction test was <br /> approximately 4 hours in length The soil vapor extraction pilot test yielded a radius of influence <br /> of approximately 50 feet Approximately 13 7 pounds of total petroleum hydrocarbons as <br /> gasoline (TPHg) and benzene were removed during the 6-hour combined vapor extraction pilot <br /> tests <br /> In December 2001 and January 2002, ATC conducted an air sparge pilot test at the site, running <br /> for approximately 31 days Well AS 1 was used to evaluate the site-specific radius of influence <br /> created by a density driven convection (DDC) well at the site The air sparge test yielded a <br /> radius of influence of approximately 20 feet Approximately 0 28 pounds of TPHg and benzene <br /> were removed during one day of the air sparge pilot test and this yielded a removal of 8 68 <br /> pounds of TPHg and benzene during the 31-day pilot test The details and results of the air <br /> sparge pilot test, vapor extraction tests, and the installation of the air sparge wells, vapor <br /> extraction wells, and the groundwater monitoring well MW10 are described in ATC's Remedial <br /> Investigation/Feasibility Study, Pacific Coast Recreation, 3755 Munford Avenue, Stockton, <br /> California, August 13, 2002 <br /> • <br /> S lEnviromenta11163931REPORTS13gr-2003 doe 2 <br />