CORRESPONDENCE_2011 - Laserfiche WebLink

Home Browse Search

r 3.2 Well Development As a result of the presence of measurable concentrations of VOCs in samples from all three temporary wells, no permanent wells were constructed. Consequently, well development was not required. 3.3 Well Survey The ground surface elevations adjacent to the temporary wells were surveyed by San Joaquin County survey staff prior to drilling. Since permanent wells were not constructed as part of this first phase of the EMP, no other surveying was conducted. 4.0 PRELIMINARY FINDINGS The following sections describe the preliminary findings concerning groundwater flow and contaminant distribution that were developed using field measurements and analytical results from the temporary monitoring wells and existing on-site monitoring well data. 4.1 Groundwater Flow Conditions After installation of the casing and filter pack materials, the depth -to -water was measured with a decontaminated electronic water level sounder. The field geologist observed increasing water levels between October 10 and 13, 2011. As a result, the temporary wells were left to equilibrate for one week before "static" water levels were measured on October 19, 2011. Groundwater monitoring information summarized on the following table: Groundwater equipotential contours were developed using October 2011 data combined with the third quarter (Summer) 2011 monitoring data from wells SB -1, MW - 4, MW -5, and MW -8. As shown on Figure 1 (attached), the equipotential data suggest the presence of a groundwater flow divide along the northern edge of the landfill. Groundwater to the south of the divide flows in a southerly direction at a gradient of 0.05 foot per foot, which is consistent with the historical interpretation of groundwater movement in the shallow aquifer. To the north of the flow divide, data from the temporary wells suggest that groundwater flows to the northeast with an apparent slight convergence along the centerline of Corral Hollow Road. Well Completion ReportGeo® 1C Page ■ 3 Corral Hollow Sanitary Landfill ASSOCIATES December 15, 2011 �230.52 MW -9 88.6 66.4 MW-10 75 66.7 219.63 MW -11 69.5 67.2 216.07 Groundwater equipotential contours were developed using October 2011 data combined with the third quarter (Summer) 2011 monitoring data from wells SB -1, MW - 4, MW -5, and MW -8. As shown on Figure 1 (attached), the equipotential data suggest the presence of a groundwater flow divide along the northern edge of the landfill. Groundwater to the south of the divide flows in a southerly direction at a gradient of 0.05 foot per foot, which is consistent with the historical interpretation of groundwater movement in the shallow aquifer. To the north of the flow divide, data from the temporary wells suggest that groundwater flows to the northeast with an apparent slight convergence along the centerline of Corral Hollow Road. Well Completion ReportGeo® 1C Page ■ 3 Corral Hollow Sanitary Landfill ASSOCIATES December 15, 2011