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0 • 21 July 2006 AGE-NC Project No. 04-1045 Page 2 of 3 REVISED SCOPE OF WORK All reporting procedures and field procedures for installation, development, survey, and sampling/monitoring of ground water monitoring wells as presented in the Additional Site Assessment Work Plan -Monitoring Well Installation, dated 23 December 2005 will apply to this revised scope of work unless otherwise noted in this addendum. AGE proposes to advance a total of five pilot soil borings at the site for installation of ground water monitoring wells,using a truck-mounted,hollow-stem drill rig equipped with 8.25-inch hollow-stem augers.Four pilot soil borings will be advanced to approximately 35 feet bsg,and the fifth pilot soil boring will be advanced to a depth of approximately 65 feet bsg at the former underground storage tank (UST) location; the total depth of each well boring may vary according to hydrogeologic/geologic conditions encountered during drilling. • Pilot boring MW-4 will be advanced (as previously proposed) approximately 85 feet southwest of the former UST location, and approximately 55 feet west of existing well MW-3, at the southern edge of the property down-gradient of the known hydrocarbon release; p • Pilot boring MW-5 will be advanced approximately 5yfeet southeast of the former UST location, directly down gradient of the known hydrocarbon release at the southeastern corner of the fenced enclosure to monitor possible offsite migration; • Pilot boring MW-6 will be advanced approximately 85 feet east of the former UST location, cross-gradient from highest known concentrations of dissolved hydrocarbons (Figure 2). • Pilot boring MW-7 (not previously proposed) will be advanced approximately 55 feet directly north of the former UST location, between the building and northern fenced boundary of the property; • Proposed pilot boring MW-8 (not previously proposed)will be advanced in the immediate vicinity of existing well MW-I and the former UST location. Soil samples will be collected from each pilot boring at five-foot intervals using a California split- spoon sampler and brass sleeves. Selected soil samples will be a lyzed by a State of California m¢u H DHS-certified laboratory as proposed in the previous work plan a�Q s d X28 cQ ST£�G mG� ;i Z T&09 The pilot borings will be completed as single-level ground water monitoring wells; wells MW-4 ax o,S through MW-7 will be screened from 15 to 35 feet bsg, and MW-8 will be screened from 55 to 65 feet bsg. Figure 3 depicts the proposed well construction specifications for MW-8. Following installation,each well will be developed to maximize water flow and minimize the amount of fine- grained sediment drawn into the well during pumping or bailing, and the top of each existing and newly installed well casing (well head), and one existing well head at the adjacent 1607 Turnpike o fc Road site,will be surveyed to determine its elevation relative to mean sea level. The survey of one Advanced GeoEnvironmental,Inc.