REMOVAL_1988 - Laserfiche WebLink

Home Browse Search

L, .s I.H. KLEINFELDER & ASSOCIATES File: 24-2038-1/28:725 December 10, 1986 Page 4 San Joaquin Local Health District. A copy of the permit is included in Appendix B of this report. The wells were completed using two—inch inside diameter, flush—threaded joint, schedule 40 PVC pipe. Well screen sections were performed with 0.020—inch factory—cut slots. The screened section was set at a depth 20 feet below and 5 feet above the depth where ground water was first encountered. The PVC pipe was steam—cleaned prior to installation. The annular space between the pipe and the wall of the boring was backfilled with clean Lone Star Industries #2/12 Monterey sand to approximately two feet above the top of the perforated section. A three—foot bentonite plug was placed above the sand pack to provide a seal against surface water infiltration. The remaining annular space was filled with sand/cement grout to the surface. Each well was secured with a locking well cover. Construction diagrams of each well are shown on Plate Nos. 4 and 5. While installing monitoring well MW-1, construction material bridged inside the hollow stem auger and the PVC casing was pulled up eleven feet above the intended depth. Although the screen section in MW-1 was set higher than originally intended, the well was completed as a useful ground water monitoring well. 5.5 Monitoring Well Development and Sampling Procedures .. Monitoring wells MW-1 and MW-2 were developed on November 5, 1986. Each well was first sampled with a clear acrylic bailer to visually inspect the sample for a product layer or sheen. No product layer or sheen was observed on the water samples bailed from the monitoring wells. The wells were developed with a surge block/air lift tool. Surging with the tool along the screened interval of the well was performed to draw the silts and very fine sands from the formation into the well. The sediment laden water was airlifted from the well at a rate of approximately 0.75 gallons per minute (gpm) . Each well was developed until the discharge water ran relatively clear of fines. Approximately 6.25 well volumes were removed from monitoring well MW-1 and 10.75 well volumes were removed from monitoring well MW-2. Monitoring wells MW-1 and MW-2 were purged and sampled on November 14, 1986. After the depth to static water was measured, each well was purged and sampled with a submersible ISCO bladder pump. Five well volumes were removed from each well before a water sample was collected. — Water samples MW-1 and MW-2 were collected in one 1—liter bottle and three 40—mil VOA bottles. The sample bottles were immediately sealed and placed in an iced cooler. At the end of the field day, the two water samples were delivered to California Analytical Laboratories/ENSECO in West Sacramento, California. The analytical results and a completed copy of the chain—of—custody form are included in Appendix B of this report. To prevent cross—contamination, all developing and sampling equipment was steam cleaned prior to use in each monitoring well. Additionally, a warm trisodium phosphate solution and clean water were pumped through the sampling equipment prior to the collection of subsequent samples.