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c URS Mr. Robert McClellon January 31, 2007 Page 2 To address the SJCEHD requirement for controlling methane greater than 5% from leaving the site, a passive soil vapor extraction trench was installed in September 2006. During the passive soil vapor extraction trench installation activities, a tank was uncovered. FIELD ACTIVITIES The following two sections describe the monitoring activities completed during the fourth quarter of 2006 and the tank removal activities completed on November 30, 2006. Quarterly Monitoring Activities During the fourth quarter of 2006, the landfill gas concentrations were measured on a bi-weekly basis as per SJCEHD request within the probes, extraction wells, and passive vents. In addition, the quarterly groundwater monitoring activities were completed on December 15, 2006. Each gas-migration monitoring probe, each extraction well, and each passive vent was measured for methane, oxygen, and carbon dioxide using a handheld portable landfill gas monitor. These measurements were recorded in a field logbook. Groundwater samples were collected from the three monitoring wells using the following procedures: • The water level from each monitoring well was measured using an electronic water level sounder. • Prior to groundwater sample collection, each well was purged using a bailer. During purging, groundwater parameters (pH, temperature, conductivity, and turbidity) were recorded on the Moni- toring Well Sampling Log form (Attachment 1) at least once per well-casing volume. Purging was completed when the groundwater parameters had stabilized to within 10 percent. The purged water was placed in 55-gallon drums. • A groundwater sample was collected from each well, using a bailer. The groundwater samples were placed into the analytical laboratory-prepared sample containers. • The groundwater samples were labeled and placed in an ice chest with ice. The samples were shipped to EMAX Analytical Laboratory in Torrance, California, under proper chain-of-custody procedures for VOC analysis by U.S. Environmental Protection Agency (EPA) Method 8260B. For this monitoring event only, Mr. Ross Atkinson of the Regional Water Quality Control Board requested that the groundwater samples be analyzed for the following parameters: dissolved metals (CAM 17) by EPA Method 6010/6020/7470 and general minerals by EPA Method 160.1/300.0/310.1/353.3. Tank Removal Activities During the activities to install the passive soil vapor extraction trench, a steel tank was uncovered. SJCEHD was notified that a tank was found during the excavation activities. The tank measured 24-inches in diameter and 4 feet in length, and was observed to be empty. Ecology Control Industries K:\Wprocess\25532\WorldEnterprise\Quarterly Rpt\4Q06\CovLtrRpt.doc