ARCHIVED REPORTS XR0000259 - Laserfiche WebLink

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Cahforma Department of Transportation Revised September 23, 1994 Project No 102818A-01 iproduct-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 tnsodium phosphate, followed by a potable water rinse and a deionized water rinse. Groundwater at the site is present at an a ate depth of 65 feet below ground surface (b s) and flows to the north at an approximate gradient of 0 0013 feet per foot The groundwater elevation measurements are summarized in Table 1. A groundwater gradient map is presented as Figure 3 The three groundwater wells,designated MW-A(MW-1),MW-B(MW-2),and MW-C(MW-3), were also sampled On June 1, 1994,_the wells were purged using a 2-inch diameter submersible pump The submersible pump and associated hoses were decontaminated after each use with a solution of potable water and tnsodium phosphate, followed by a potable water rinse and a deionized water rinse The interior and exterior of the pump and hoses were washed by submersing the equipment in the solutions and drawing wash and rinse water through the pump system A minimum of three casing volumes were purged from each of the monitoring wells prior to collection of a water sample Temperature, pH, and specific conductance measurements were made in the field for the purpose of establishing when a representative groundwater sample could be taken Purging continued in each well until pH, temperature, and conductivity did not vary by more than 10 percent The_ morutonna well purge water was placed in labelled 55-gallon,DOT-approved drums and left on site in the-stp-wardship of Caltrans Field measurements and general observations for each well were recorded on the well sampling records presented in Appendix A After purging, the water in each well was allowed to recover to at least 80 percent of its original elevation Water samples were then collected using a disposable, Teflon, bottom- discharging bailer, transferred to an appropriate sample container, labelled, and placed in a ' cooler containing ice at 4 degrees Celsius under chain-of-custody protocol Water samples were collected on June 1, 1994 Samples were secured in a cooler containing ice at 4 degrees rCelsius and transferred by truck to San Diego on June 3, 1994, and then temporarily stored • in refrigeration at the San Diego office of Ninyo &Moore Samples were then delivered to