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• Ms Vicki McCartney Project No 880-040 1A/01070000 <br /> April 24, 2003 <br /> Page 2 <br /> Excavation was restricted laterally by concrete canopy footings and asphalt surfacing <br /> Due to close proximity of groundwater, the maximum excavation depth was <br /> approximately 10 feet bgs <br /> On August 15 and 16, 2000, five Geoprobe® borings (GP-1 through GP-5) were <br /> completed using a direct push rig The borings were advanced to groundwater, at which <br /> time a discrete water sample was collected Following groundwater sample collection, <br /> the bonngs were continued to a maximum depth of 30 feet bgs <br /> On September 6, 2000, three groundwater monitoring wells (MW-1 through MW-3) <br /> were installed The well locations were selected based on the Geoprobe® investigation <br /> results Well locations are shown on Figure 1 Quarterly groundwater monitoring and <br /> sampling was initiated in September 2000 <br /> • In their letter dated October 31, 2001, the San Joaquin County Environmental Health <br /> Department (SJCEHD) requested a work plan to define the vertical and lateral extent of <br /> soil and groundwater impact and determine an interim remedial alternative to control <br /> the off-site migration of methyl tert-butyl ether (MtBE) A work plan dated <br /> December 12, 2001, was prepared describing the implementation of a 5-day dual-phase <br /> extraction event, the installation of two downgradient wells, and one deep soil boring <br /> The work plan was approved by the SJCEHD on December 31, 2001 <br /> On May 22 and 23, 2002, Shaw observed the drilling of one deep soil boring and the <br /> installation of two monitoring wells (MW-4 and MW-5) <br /> GROUNDWATER MONITORING <br /> On April 3, 2003, groundwater samples and depth to water data were collected from <br /> monitoring wells MW-1 through MW-5 Groundwater samples were analyzed for the <br /> presence of Total Petroleum Hydrocarbons as gasoline (TPHg), benzene, toluene, <br /> ethylbenzene, xylenes (BTEX), and for five gasoline oxygenates (MtBE, di-isopropyl <br /> ether [DIPE], ethyl tert-butyl ether [ETBE], tert-amyl methyl ether [TAME], and <br /> Shaw Environmental,Inc <br /> N IsacDP00031Pr}188018800401A 3ab doe <br />