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rr Monitoring Well Installation Report Speedy Mart,8200 N Highway 99 • Page 6 of 8 Product odors were generally noted only in the capillary fringe and the saturated zone in each boring No product odors or positive FID reading were noted in the vadose zone Moderate product odors and FID readings of approximately 2000 parts per million (ppm) were noted in boring MW 1 from 70 feet bgs (the depth where continuous sampling began) to approximately 76 feet bgs Odors and FID ieadings declined with depth until no odors were noted in sample collected from approximately 95 feet bgs Soil boring locations are presented on Figure 3 Well completion details and soil boring logs are included in Attachment A Groundwater beneath the site was initially encountered at depths between 61 and 70 feet bgs, and generally recovered to a depth of approximately 60 feet bgs The depth to groundwater was measured in each well prior to well development on October 12, 1999 to determine elevation and gradient of groundwater beneath the site The depth to water ranged from 29 05 to 29 38 feet below mean sea level with a gradient of approximately 0 003 to the northeast Groundwater levels were measured again after well development on October 13, 1999 The post well development groundwater elevation ranged from 29 02 to 29 33 feet below mean sea level with a hydraulic gradient 0 0035 and flowed generally northeast Potentiometric surface maps generated using the October 12 and 13, 1999 monitoring data are shown on Figure 4 and 5, respectively Groundwater elevation data are summarized in Table 6 Soil and Groundwater Analytical Results Based upon field observations and analytical results soil in the vadose zone is generally not contaminated by residual petroleum hydrocarbons, except for in the immediate vicinity of the former USTs However, soil samples collected from the capillary fringe zone in each of the soil bonngs/momtonng wells, with the exception of well MW4, contained low levels of residual gasoline constituents No residual contanunation was detected in any soil sample collected from well MW4 The maximum TPHg concentration of 42 ppm was detected in the sample collected from MW 1 at 70 feet bgs, the maximum benzene concentration of 14 ppm was detected in the sample collected from MW3 at 60 feet bgs, and the maximum MTBE concentration of 3 8 ppm detected was detected in the sample collected from MW3 at 60 feet bgs Residual contaminants in the soil tended to decrease with depth from the highest levels in the capillary fringe zone No TPHg or benzene were detected in the bottom sample collected from borings MW2, MW3,MW4, or SB5 However, the bottom sample collected from well MW1 (94 feet bgs) contained TPHg, benzene, and MTBE at 3 7, 0 25, and 0 35 ppm, respectively The sample collected from 85 feet bgs in well MW 1 was non-detect for all analytes MTBE was also detected in the bottom samples collected from borings MW3, SB4, and SBS Soil analytical results are summarized in Tables 2 and 3 Laboratory reports and chain of custody documentation are included in Attachment E Hydropunch groundwater samples collected from borings SB4 and SB5 contained moderate levels of gasoline constituents, including benzene and MTBE The discrete groundwater sample collected from well MW1 at a depth of 95 feet bgs contained elevated levels of gasoline constituents Most notably, TPHg, benzene, and MTBE were detected at 100,000 parts per billion (ppb), 5,600 ppb, and 7,600 groundzeltuleburglweltrpt doc