ARCHIVED REPORTS_MONITORING WELL INSTALLATION REPORT - SITE ASSESSMENT WORK PLAN

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1 ' 25 February 2005 AGE-NC Project No. 98-0500 ' Page 3 of 6 ' updated health and safety plan in accordance with Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities (National Institute for Occupational Safety and Health Administration, U.S. Coast Guard and U.S. Environmental Protection Agency, 1985). AGE will ' notify the CVRWQCB a minimum of 72 hours prior to commencement of any work. Prior to mobilization,the area of excavation will be clearly marked and an utility clearance obtained through Underground Service Alert. ' 2.2. MONITORING WELL INSTALLATION AND MONITORING Based on site data, AGE proposes to advance a total of five 200 foot soil pilot borings to Install ' multi-level ground water monitoring wells. The proposed set of locations for the wells are depicted in Figure 2. The wells will have the following screened intervals; the upper most water table at 60 feet bsg,possible at 75 feet to 85 feet bsg, 95 feet to 100 feet bsg, 145 feet to 150 feet bsg, 175 feet ' to 185 feet bsg and 195 feet to 200 feet bsg. The multi-level monitoring wells area proposed in the following areas: • One well south of the investigation area, forty feet west of CPT8, for the southern or cross- gradient definition of the dissolved 1,2-DCA. • One well south of CPT4, for the vertical and lateral definition of the dissolved 1,2-DCA. • One well 60 feet east of monitoring wells MW-10 and MW-19, in the interior of the investigation area, for the vertical and lateral definition of the dissolved 1,2-DCA. • One well west of the building on the site in the investigation area, south of CPT10 feet, for the western or cross-gradient definition of the dissolved 1,2-DCA. ' • One well north of the investigation area,eight feet north of CPT9,for the northern definition of the dissolved 1,2-DCA near the domestic well on the site. ' The pilot borings will be completed as multi-level ground water monitoring wells. The proposed screen intervals of the multi-level wells are based on interpretation of lithologic data collected during ' the site assessment.The proposed screen-interval depths of the multi-level ground water monitoring well are: ' • Between 50 and 65 feet bsg to assess first encountered ground water; • Possible between 75 and 85 feet bsg to assess hydrologic unit two and possible preferential ' pathways documented by wells MW-18 and MW-19; • Between 95 and 100 feet bsg to assess hydrologic unit three; Advanced GeoEnvironmental,Inc.