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V � A S S O C I A T E S I N C In December 2000, ATC personnel supervised the advancement of one cone penetrometer (CPT) boring to 140 feet bgs Also in December 2000 ATC personnel supervised the advancement of four soil borings to 80 feet bgs and one soil boring to 100 feet bgs The soil borings were converted into groundwater monitoring wells Analytical results of soil samples and groundwater samples indicated that soil and groundwater are impacted by petroleum hydrocarbons Site activities were summarized in ATC's Summary Report of Additional Subsurface Investigation, dated March 6, 2001 In September 2001, ATC supervised the advancement of four geoprobe soil borings, SBI through SB4, and eight hollow stem auger borings Soil borings SBI through SB4 were advanced first encountered groundwater, approximately 61 feet bgs, boring AS 1 was advanced to approximately 85 feet bgs, borings PZ1a and PZIb were advanced to approximately 80 feet bgs, borings VW1, VW2, and VW3 were advanced to approximately 65 5 feet bgs, and borings MW9 and MW 10 were advanced to approximately 81 feet bgs Soil boring AS 1 was completed as a 4-inch diameter air sparge well with two 2-inch diameter piezometers located in the same borehole Soil borings PZ 1 a and PZ 1 b were completed as 2-inch diameter piezometer pairs Soil borings VW1, VW2, and VW3 were completed as a 2-inch diameter vapor extraction wells and borings MW9 and MW 10 was completed as a 2-inch diameter groundwater monitoring well • On October 31 and November 1, 2001, ATC performed a short-term vapor extraction test and a long-term vapor extraction test On the first day, a short-term vapor extraction test was approximately 2 hours in length and on the second day, a long-term vapor extraction test was approximately 4 hours in length The soil vapor extraction pilot test yielded a radius of influence of approximately 50 feet Approximately 13 7 pounds of TPHg and benzene were removed during the 6-hour combined vapor extraction pilot tests In December 2001 and January 2002, ATC conducted an air sparge pilot test at the site, running for approximately 31 days Well ASI was used to evaluate the site-specific radius of influence created by a density driven convection (DDC) well at the site The air sparge test yielded a radius of influence of approximately 20 feet Approximately 0 28 pounds of TPHg and benzene were removed during one day of the air sparge pilot test and this yielded a removal of 8 68 pounds of TPHg and benzene during the 31-day pilot test The details and results of the air sparge pilot test, vapor extraction tests, and the iri allation of the air sparge wells, vapor extraction wells, and the groundwater monitoring well MW 10 are described in ATC's Remedial Investigation/Feasibility Study, Pacific Coast Recreation, 3755 Munford Avenue, Stockton, California, August 13, 2002 SAMPLING ACTIVITIES • On June 25, 2002, ATC personnel collected groundwater samples from monitoring wells MW1, MW3 through MW10, and the on-site groundwater supply well DW A groundwater sample was not collected from well MW2 because of the presence of floating free product in the well The w U63931quan1y12gr-2002 doc 2