WORK PLANS - Laserfiche WebLink

Home Browse Search

that can pass through the system. Therefore, we have opted not to perform the infiltrometer tests. The deliverable for this task will be boring logs detailing the lithology of each boring and tables of the physical and chemical analyses for each sample. TASK 3—EVALUATION OF AQUIFER This task will provide the background data necessary to determine site-specific groundwater flow conditions, water quality conditions, and surface-water/groundwater interactions, which will subsequently be used to evaluate the potential impacts to the groundwater. Four groundwater-monitoring wells will be installed on levees surrounding the DPS (Figure 1). As requested by the RWQCB, one well will be placed off site on a levee north of the DPS to act as a background well. The other three will be placed along boundary roads adjacent to the lower areas of the property where the fines from the dredged materials and the water are expected to accumulate. The borings for the wells will be drilled to an estimated depth of about 20 feet below the grade of the DPS (25 to 30 feet below the top of the levees) using a hollow-stem auger rig. The wells will be cased with 2-inch polyvinyl chloride, with factory-slotted well screen(0.02-inch slots) placed from about 5 feet above the water table (estimated at 10 feet below ground surface of the DPS [bgs])to 10 feet below the water table. The filter material will consist of Lonestar Lapis Luster 43 sand or equivalent and will be placed to a depth of about 1 foot above the top of the screen. A 1-foot bentonite transition seal will be placed above the filter material, and the remainder of the annulus will be sealed with a cement bentonite grout. Each well will be finished within a flush-mount Christy box so as not to impede traffic along the levee roads. The top of the Christy box will be slightly elevated above grade to reduce the potential for drainage into the well installation. Following installation of each well (a minimum of 24 hours to allow grout to set), the well will be developed in preparation for sampling. Development will consist of surging and bailing to remove sediment from the well. Field water-quality parameters (pH, electrical conductivity [EC], temperature, and turbidity)will be monitored and development will continue until the field water-quality parameters have stabilized. 1AMARKET\PROPOSAL2000 Props\6988-POS\Amended work plan.doc 3