ARCHIVED REPORTS_XR0004892 - Laserfiche WebLink

Home Browse Search

r� n . Monitoring Well Installation Report Quik Stop No 121 Page 4 Monitoring Well Installation CCI dnlled three exploratory borings at the locations shown in Figure 2 The borings were drilled with a truck-mounted, B-61 drill rig with continuous-flight, hollow-stem auger with a 4-114-inch inside diameter The auger and other tools were steam-cleaned before drilling to minimize the possibility of cross-contamination All drill cuttings were placed in Department of Transportation (DOT) approved drums, labeled and left at the site The bonngs for each of the wells were drilled in the following manner the drill rig was positioned over the boring location, and the hollow-stem auger was used to advance the hole to the desired sampling depth A CCI geologist logged the bore- hole by collecting relatively undisturbed soil samples at 5-foot depth intervals to the bottom of the boring Samples were collected using a precleaned, modified, California split-spoon sampler with internal 2-inch diameter by 6-mch long brass liners The sampler was driven 1-112 feet ahead of the auger with a 140-pound, rig-operated hammer The sampler was then removed and disassembled into its component parts The soils encountered were characterized using the Unified Soil Classification System Boring logs for each well are included in Appendix A The soil collected for laboratory analysis were capped with Teflon sheets and plastic caps, labeled, logged on a chain-of- custody hain-ofcustody form and stored in a chilled ice chest for preservation in the field and during transport to a state-certified laboratory CCI's soil sampling protocol is attached in Appendix B Monitoring Well Construction The three groundwater monitoring wells were constructed using 2-inch diameter, schedule 40 polyvinyl chloride (PVC) well casings Ten to fifteen feet of 0 020 slotted screen was used in each well The annulus between the casing and the bore-hole was backfilled with 2112 sand to about 2 feet above the screen interval A bentonite clay spacer, 1 foot thick, was then placed above the sand pack, and cement grout was pumped from above the bentonite to the surface A watertight locking vault box caps each well Details of the monitoring well construction are included in Appendix A Well Development On April 26, 1999, the wells were developed by hydraulicly pumping the wells to (a) remove residual silts and clays left from the drilling and (b) improve the hydraulic conductivity between the wells and the natural formation After development, the wells were allowed to recharge, enabling CCI to collect a representative water sample and to measure the thickness of any floating product encountered All water collected during well development was placed in labeled drums and left on- site pending the results of the analytical testing Groundwater Sampling On April 30, 1999 CCI sampled the wells in the presence of a representative of County