Laserfiche WebLink
4.0 RESULTS <br /> Subsurface Conditions - Soil <br /> During the advancement of the borings, the following soil types were encountered. In the <br /> �- vadose zone, from 0 feet to approximately 8 feet bgs, generally silty clay was encountered. <br /> Clayey sand was encountered in boring SB4 at 4 feet to 5.5 feet bgs. The silty clay was moist <br /> with low to medium plasticity. In the capillary fringe, from approximately 8 feet to 11 feet <br /> bgs, generally silty to sandy clay was encountered. Soil in the capillary fringe was moist to <br /> I LM wet. From the capillary fringe to the total depth explored (I1 feet to 15 feet bgs), generally, <br /> clayey sand to sandy clay and sand was encountered. This coincided with the soil types <br /> encountered during the previous investigation. <br /> 16m <br /> • 4.2 Substi4ace Conditions - Groundwater <br /> �. Groundwater in the uppermost water bearing zone appears to be confined to semi-confined <br /> with the static water table rising during this investigation to generally 7.5 feet bgs after being <br /> ` initially encountered at depths ranging from approximately 8 to 10 feet bgs during drilling <br /> activities. However, groundwater was encountered in several borings as deep as 13 to 14.5 <br /> w feet bgs. <br /> Depth to water measurements were collected from monitoring wells MW-1 through MW-3 on <br /> `' September 25, 1996. The depth to water ranged from 7.03 to 8.50 feet below top of well <br /> casing elevation. Groundwater elevations have increased an average of 0.23 feet since April <br /> L. 22, 1996. Groundwater flow beneath the site is generally northwest with a magnitude of <br /> 0.003 ft/ft, or approximately 16 ft/mile. A groundwater gradient map for the September 25, <br /> 1996 monitoring event is depicted on Figure 3. The data indicates a groundwater gradient that <br /> is consistent with the previous monitoring event. A summary of groundwater monitoring data <br /> is presented in Table 4. Groundwater elevations are referenced to feet mean sea level. <br /> 4.3 Analy ical Results - Soil Samples <br /> Of the nine soil borings (borings SB4 and SB4A will be considered as one boring) advanced at <br /> the site during this additional investigation, TPHg and BTEX were detected in three of the <br /> L. borings including SB2, SB4A and SB7. Benzene, however, was not detected in the soil <br /> sample from boring SB4A. The highest concentrations of these petroleum constituents were <br /> detected in borings SB4A and SB7. Although floating product was observed on the <br /> t groundwater in boring SB2, only moderate concentrations of TPHg and BTEX were detected <br /> w:1951221Plumerpt . 6 <br /> L <br /> • <br /> SMTN <br />