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v � 0 • A S S O C I A T E S I N C hydrocarbon constituents have not been detected in groundwater samples collected from monitoring well MW-4R In January and February 1996, SECOR advanced ten soil borings at the site Soil samples and grab groundwater samples were collected from the borings Only one soil sample contained detectable concentrations of petroleum hydrocarbons at low levels Groundwater samples collected from borings SB2 and SB26 contained elevated concentrations of petroleum hydrocarbons and trace amounts of free product In July and August 1999, ATC Associates Inc advanced ten soil borings (Figure 2) to evaluate the extent of petroleum hydrocarbons and trace amounts of free product detected by SECOR Soil borings advanced along the levee, southwest of the location of the former USTs and the current AST location contained elevated concentrations of total petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), and methyl tertiary butyl ether (MTBE) The extent of impacted soil was defined and generally extended along the backside of the levee, west of the store The areal extent was approximately 200 feet in length and 65 feet in width and was limited to depths between 5 and 15 feet bgs Additionally, MTBE impacted soil extended eastward, between the store and office building • The groundwater plume generally extended along the backside of the levee, west of the store, and was approximately 225 feet long and 70 feet wide Concentrations were highest in the boring adjacent to the former and current product lines The extent of TPHg in groundwater was not fully defined to the west and south but samples indicated that the borings in those directions were near the edge of the plume Additionally, TPHd and MTBE have migrated eastward SCOPE OF WORK Planning and Permits ATC has completed the PHS/EHD soil boring permit application for the proposed subsurface investigation The permit application and associated fees (check no 374) are attached to this workplan ATC will also schedule field personnel and equipment, notify Underground Services Alert to locate underground utilities as required, and perform any other necessary field preparation and job start-up activities Installation of Monitoring Well One soli boring will be advanced at location shown on Figure 2 to monitor petroleum hydrocarbon impacted groundwater The boring will be advanced to approximately 30 feet bgs and completed as a 2-inch diameter monitoring well Drilling will be conducted by �Wp) Drilling utilizing 8-inch O D hollow stem augers w 1625144eporb\wkp do-.- 3