ARCHIVED REPORTS_XR0005209 - Laserfiche WebLink

Home Browse Search

WELL CONSTRUCTION REPORT USA STATION#110- STOCKTON DECEMBER, 1995 Monitoring well MW-5-P was completed with 4-inch, flush threaded, schedule 40 PVC slotted ' casing from 55-feet to 85-feet and blank casing from 55-feet to the top of casing (TOC) MW-4-P and MW-6-P were completed with 2-inch, flush threaded, schedule 40 PVC slotted casing from 85-feet to 55-feet and 84-feet to 54-feet bgs, respectively Blank casings in MW-4 and MW-6 were placed from 55-feet to TOC and 54-feet to TOC, respectively The bottom of the casing was sealed with a threaded end cap The screened PVC casing consisted of 0.02-inch machine-cut slots Number 2 sand (or equivalent) was poured down the augers, while removing approximately 2-feet of auger at a time The filter pack was placed to 2-feet above the screened interval Bentonite pellets were then poured through the augers to form an approximately 3-feet thick annular seal immediately above the sand pack A cement mixture was then used to fill the annular space to 1-foot below grade Traffic-rated,flush-mounted well boxes were installed at a height of approximately 1-inch above grade to minimize the potential for surface runoff entering the well Well construction details are shown on the boring logs in Appendix B. 3.5 Well Development Each groundwater monitoring well was developed using a surge block for a least 20 minutes, and then purged of at least three well volumes of groundwater During purging, values of pH, conductivity and temperature were monitored and recorded The data from well development is presented in Table 1 The wells were allowed to stand for a sufficient period of time for the groundwater to equilibrate within 80 percent of the initial static groundwater level prior to sampling r3.5 Groundwater Measurements Prior to purging and sample collection, the depth to groundwater was measured in each of the three (3) new wells Water levels were measured using an electronic water level indicator Measurements were taken from a marked location on top of the well casings The depth to water in the new wells vaned from 7155 to 71.72 feet bgs The elevation ranged from 46 14 to 46 95 feet below mean sea level As part of the quarterly monitoring, the water levels of the new well and the existing wells were used to evaluate the average groundwater gradient across the site 1 Comparison of the water levels indicates that the direction of groundwater flow ranges from N44E to N50E with a slope between 0 0025 and 0 003 ft/ft A graphical presentation of the groundwater gradient is included in the"Third Quarter 1995-Project Status and Monitoring 1 Report" 4 s