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ATC Associates Inc. V TATE CIN 1117 Lone Palm Avenue, Suite 201 Modesto, California 95351 209-579-2221 Fax: 209-579-2225 A S 50 C C . including indoor air quality, do not appear to be at risk. Site activities are summarized in ATC's Soil Vapor Study, dated May 7, 2008, for additional information. SCOPE OF WORK Planning and Permits ATC will obtain all necessary permits, including soil boring permits from San Joaquin County and encroachment permits from the City of Ripon, if necessary. ATC will also schedule field personnel and equipment, notify Underground Service Alert to locate underground utilities as required, and perform any other necessary field preparation and job start-up activities. Advancement of Soil Borings To further evaluate the lateral and vertical extent of impacted groundwater beneath the site and north of MW2, three vertical soil borings employing direct push technology and cone penetrometer testing (CPT) methods will be advanced to depths of approximately 100 to 150 feet bgs. Two soil borings will be advanced on-site in the vicinity of the excavation area associated with the former USTs and a third soil boring will be advanced off-site, north of MW2. Drilling will be conducted by a State- licensed C57 drilling company. A field geologist will be present to supervise drilling activities, evaluate sample depths, and collect soil and groundwater samples. Proposed boring locations are shown on Figure 2. At each of the proposed locations, a cone mounted with sensors at the tip will be advanced into the soil using direct push rods. The sensors will test the response of the soil to the force of the penetrating cone, which will allow the subsurface stratigraphy to be characterized. The borings will be advanced until a significant confining layer is encountered that appears to separate the first encountered groundwater from deeper water bearing zones. To be considered significant, the confining layer will need to be approximately five feet in thickness or greater. For estimating purposes, ATC is assuming the borings will be advanced to depths of approximately 100 to 150 feet bgs. If no significant confining layer is encountered to a depth of 150 feet bgs, the borings will be advanced further if subsurface conditions will allow. Once a significant clay layer has been discovered and the boring is advanced into an identified deeper water bearing zone, the boring will be terminated. After the subsurface materials have been characterized and evaluated, a field geologist will select sample depths for collecting discrete groundwater samples. For each discrete sample, a direct push Hydropunch® boring will be advanced adjacent to the initial CPT bearing zone. Following the collection of groundwater samples, the borings will be grouted to the surface with a neat cement S:\environmental\6205\Reports\additional subsurface investigation workplarimpd 3