ARCHIVED REPORTS_XR0007098 - Laserfiche WebLink

Home Browse Search

feet bgs during this investigation. The groundwater flow direction at the site is directed toward the {' southwest with a hydraulic gradient of approximately 0.03 ft./ft. A summary of data regarding groundwater levels measured through August 1, 1996, is presented in Table 1. Copies of field _.j observations documenting work performed at the site is presented in Appendix C. Prior to purging each groundwater monitor well, a water sample was taken and subjective analyses performed. The subjective analyses consisted of checking for floating product or a hydrocarbon sheen by lowering a clean teflon bailer down the well and collecting a sample at the groundwater-air interface. Wells not containing floating product were purged of approximately 2 to 4 casing volumes of water or until groundwater parameters of pH, temperature, and conductivity stabilized as measured by portable meters calibrated to a standard buffer and conductivity standard. If the well was slow to recover or purged dry,the water level in the monitor well was allowed to recover to at least 80 percent of its static level before sampling. The groundwater samples were then collected by lowering a clean disposable bailer into the well and collecting a representative sample. The groundwater samples were slowly transferred to laboratory-cleaned sample containers, sealed with teflon caps, labelled with the sample number, sample time and date, and immediately placed on ice in an insulated container. Each sample was logged onto a Chain-of-Custody Record for subsequent delivery to Excelchem Environmental labs located in Roseville, California. Groundwater samples were analyzed for TPHg and BTEX, using modified EPA Method 8015, and EPA Method 602 respectively. 3.7 Drill Cuttings and Pur eg water During drilling and sampling operations, all augers, sampling tools, and down hole equipment were =`==' steam cleaned prior to use. All soil cuttings generated during the drilling operations was stored on and covered with plastic sheeting pending the evaluation of disposal options. Four composite.soil samples were collected from the stockpile and analyzed for TPHg and BTEX. Analytical results are j presented in Appendix D. The purge and rinsate water generated during cleaning,development, and sampling operations, is stored on-site in DOT-approved 55-gallon drums pending evaluation of disposal options. 4.0 RESULTS 3 4.1 Soil Soil samples collected from the borings during this investigation consisted predominantly of sands Clays, and gravels. In general, a well graded sand exists from near ground surface to approximately - 70 feet bgs. This interval has occasional, lateral discontinuous clay layers from 4 to 14 feet in thickness interbedded with the sand. Gravels with varying amounts of sand and clay are generally encountered between 70 feet bgs to the total depth of the boreholes. The amount of gravel in this interval tends to decrease as the clay content increases with depth. Soil boring logs containing = detailed descriptions of soil conditions encountered in each boring are included in Appendix A. Out of eighteen soil samples that were submitted for laboratory analysis,only one sample(MW8-75) had detectable hydrocarbon concentrations; consisting of benzene (0.064 ppm), toluene (0.005 .�i _..j lob No.)0710-001-01 ,1 SECOR LOCKFFORD TNV `t October 9,1996