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Report-Pilot Remedial System Test Page 10 <br /> Former Manna Pro Site <br /> Project No 207 3 <br /> July 31,2000 <br /> 3.3.3 Air Monitoring Well Construction <br />' These two observation wells, designated OB-4 and 013-5, are located 13 and 27 feet <br /> down-gradient from the vapor extraction well as shown on the site map The following <br /> table describes the construction of the combination air monitoring/shallow air recharge <br />' well <br /> Casing 2" Schedule 40 PVC <br /> L Screen 0 010 Slotted Schedule 40 AVC <br /> Screened Interval 20-30 feet below ground surface(bgs) <br /> Filter Pack 18-30 feet bgs <br /> Filter Pack Material 43 Monterey sand <br /> Bentonite Transition Seal 15-18 feet bgs <br /> Annular Seal 0-15 feet bgs <br /> 3.3.4 ORC Slurry Installation <br /> This boring, designated ORC-1, is located down gradient of the air monitoring wells and <br /> about 20 feet up-gradient of monitoring well MW-6 This boring was drilled with 8 inch <br /> augers to a total depth of 50 feet It was back-filled with a 50% slurry of ORC with sand <br /> filler and water from 50 feet to 30 feet bgs The remainder of the boring was back-filled <br /> with neat cement A total of 300 pounds of ORC were used in the back-fill material <br /> 3.4 Well Development <br /> Although the new wells VEW-1, ASW-1 will not be used for routine groundwater <br /> g � ) <br /> sampling, they were developed after the well sealing materials were allowed to set for at <br /> least 48 hours On April 27, 2000 Del-Tech Geotechnical Services of Oakdale, CA <br /> mobilized to the site to develop the wells Each well was opened and the water level <br />' allowed to equilibrate As each well was opened, and prior to taking the depth to <br /> groundwater measurement, a PID organic vapor meter was used to screen for VOC's in <br /> the head space of the well The depth to groundwater was measured by lowering an <br />' electronically actuated air 1 water interface detector suspended from a polyethylene <br /> measuring tape calibrated to the nearest 0 01 foot A careful notation was made of the <br /> depth to groundwater as measured by the device <br /> Each well was developed by inserting a submersible pump into the well and lowing it to <br /> bottom Well water was pumped into 55 gallon DOT approved polyethylene drums, <br /> t properly labeled, and temporarily stored on-site The rate of well purging was monitored, <br /> and each well was purged of at least ten casing volumes or until the groundwater <br /> parameters (temperature, conductivity, and pH) had stabilized indicating that water <br />' representative of actual aquifer conditions was entering the well Groundwater parameter <br /> stabilization was characterized by three successive readings within 10 percent <br /> 2937 Veneman Ave,#13240 Geo-Phase Environmental Inc Phone(209)569-0293 <br /> Modesto, CA 95356 Fax(209)569-0295 <br /> 1 <br />