Laserfiche WebLink
M.� <br /> Quik Stop Market No. I20 (ktober 9, 1990 <br /> Project No. 349120-31 Page 3 <br /> �- wf the PVC well. The details of the well construction are presented in the Monitoring <br /> Well Detail form included in Appendix A. <br /> Well Development <br /> Following construction, the wells were; developed by manually bailing four to 10 well- <br /> casing volumes of groundwater from each to (a) remove residual silts and clays left <br /> from drilling and (b) to improve hydraulic conductivity between the well and the <br /> natural. formation. All water collected during well development was placed in drums <br /> and left on-site. After development, the groundwater was allowed to stabilize for <br /> approximately 72 hours before samples were collected. <br /> Groundwater Sampling <br /> Before sampling groundwater, Exce.ltech personnel field-checked the monitoring wells <br /> for the presence of free-floating product; none was found. The wells were then purged <br /> of three well-casing volumes of groundwater before sampling. Samples were collected <br /> with a clean teflon bailer and transferred to the appropriate laboratory-supplied <br /> containers. The samples were then stored in a chilled cooler for transportation to a <br /> state-certified laboratory. All purged groundwater was placed in Department of <br /> Transportation 17E drums and left on-site. <br /> Surveying <br /> Ron Archer, Civil Engineer of Pleasanton, California, surveyed the tops of the PVC <br /> well casings and the vault boxes to locate the monitoring wells accurately. This survey <br /> was necessary to determine the groundwater gradient, draft accurate plot plans, and <br /> determine the surface elevations of the well casings. The licensed surveyor's report is <br /> included in Appendix C. <br /> SUBSURFACE CONDITIONS <br /> The site is underlain primarily by silty and clayey sand and sandy clay. Groundwater <br /> -- was first encountered during drilling at depths of approximately 45 ro 46 feet below the <br /> ground surface in a sand, silty sand, and clayey sand aquifer. Groundwater depths <br /> measured on September 12, 1990 served as the basis for the groundwater surface <br /> contour map presented in Figure 3. The contours indicate that the apparent gradient is <br /> nearly flat(0.0029 feet per foot) and that the flow direction is generally to the eas!. <br /> LABORATORY ANALYSIS <br /> Analyses of soil and groundwater samples collected at the site were used to ascertain the <br /> extent and level of possible petroleum hydrocarbon contamination. Sequoia Analytical <br />