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07 / 16 / 1999 14 : 04 209 - 579- 2225 MODESTO ATC PACE 05 <br /> (YA <br /> T� <br /> A 8 8 0 C I A r E i I N e <br /> supervised the advancement of a boring for groundwater monitoring well 1u1W4R to replace the <br /> abandoned groundwater monitoring well MWA. Analytical results of the soil samples collected <br /> from the boring for monitoring well MW4R indicated that petroleum hydrocarbons were detected <br /> only in the sample collected from 6.5 feet bgs. Petroleum hydrocarbon constituents have not been <br /> detected in groundwater samples collected from monitoring well MW4R. <br /> In January and February 1996, SECOR advanced ten soil borings at the site. Soil samples and <br /> grab groundwater samples were collected from the borings. Only one soil sample contained <br /> detectable concentrations of petroleum hydrocarbons at low levels. Groundwater samples <br /> collected from borings SB2 and S826 contained elevated concentrations of petroleum <br /> hydrocarbons and trace amounts of free product. <br /> SCOPE OF WORK <br /> Planning and Perntift <br /> ATC has completed the PHS/EHD soil boring permit application for the proposed subsurface <br /> investigation. The permit application and associated fees (check no. 142) are attached to this <br /> workplan. ATC will also schedule field personnel and equipment, notify Underground Services <br /> Alert to locate underground utilities as required, and perform any other necessary field <br /> preparation and job start-up activities. <br /> Advancement of Sod griM <br /> In an attempt to identify the source of impacted groundwater and define the extent of impacted <br /> groundwater at the site, up to ten soil borings will be advanced to approximately 15 feet bgs. <br /> The first four soil borings will be advanced in the area of SECOR borings SB2 and SB26. Based <br /> on field observations, up to six additional soil borings will be advanced at locations determined <br /> by ATC and PHS/EHD in the field. The anticipated groundwater flow direction is northeast. <br /> i <br /> The proposed first four boring locations are shown on Figure 2, <br /> I <br /> The borings will be advanced using truck mounted GeoprobeO narrow diameter, direct push <br /> technology. Drilling will be conducted by a State4icensed (C57) drilling company. A field <br /> geologist will be present to log all soil samples. Descriptions of soil types encountered and <br /> sample collection intervals will be recorded on boring logs. Soil samples will be collected at five <br /> foot intervals or estimated changes in lithology, field screened with a PID, and an estimated two <br /> soil samples from each of the borings will be submitted for laboratory analysis. Soil sample <br /> selection will be based on PID measurements and field observations (i.e. odor and soil <br /> discoloration). <br /> One groundwater sample will be collected from each boring at the depth groundwater is fast <br /> encountered, anticipated to be approximately 7 feet bgs. A Geoprobe® Screen Point 15 <br /> w\625144cpomlwkp.doc 3 <br />