ARCHIVED REPORTS XR0000196 - Laserfiche WebLink

Home Browse Search

California Department of Transportation Revised September 23 1994 P P P Project No. 102818-01 Five additional groundwater monitoring wells were installed at the site in 1990, with another three installed in 1992 The groundwater level reportedly dropped more than 20 feet from 1987 to 1992. In 1992, groundwater samples could only be collected from five of the twelve existing monitoring wells In 1993, an additional eleven soil borings were drilled at the facility and six of the borings were converted into monitoring wells, for a total of 18 existing wells GROUNDWATER MONITORING WELL SAMPLING On May 24, 1994, a representative of Ninyo&Moore measured the depth to the static water ' level in groundwater monitoring wells located at the site (Figure 2) Groundwater monitoring wells MW-1 through MW-6 were dry The monitoring wells were first checked ifor the presence of immiscible layers using a product-sensing interface probe No product was detected The depth to the static water level was then measured relative to the reference marking on the top of the well casing The water level measuring instrument was decontaminated after each use by washing the probe and lead line with a solution of potable water and trisodium phosphate, followed by a potable water rinse, and a deionized water rinse Groundwater at the site is present at an approximate depth of 65 feet below ground surface (bgs) and generally flows to the north at an approximate gradient of 0 0033 feet per foot. A groundwater gradient map is presented as Figure 3 The groundwater elevation measurements are summarized in Table 1 it should be noted that the groundwater elevations measured may be influenced by irrigation wells located to the east on the San Joaquin County Fairgrounds The literal interpretation of the field data collected may not reflect actual subsurface conditions The groundwater gradient map shown on Figure 3 is unreahstic but reflects observed conditions The resulting gradient map likely represents inaccurate survey data; well construction that is not screened through the water table, pumping of nearby wells, or other factors 2