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1:1.1101:141-11•. • • • The following •• _ work plan forthe installation of ground • • • wells at the Forward Landfill in Stockton, Three additional wells are proposed for the Forward Landfill for additional ground water monitoring downgradient of WMU-A. These wells will be installed as replacement monitoring points for the three lysimeters which were originally planned to be installed under the four trenches of WMU-A. The installation of these wells will satisfy the monitoring requirements of the Department of Health Services for Waste Management Unit A. T he construction of the new wells, MW -13, MW -14 and MW -15 will be similar to the construction of the previous wells on the site. The holes will be drilled using a 10 inch hollow stem auger, adequately large to allow placement of the 4" well casing. The boreholes will be continuously cored and geologically logged by a staff geologist and the cores will be preserved in air tight plastic for future use. Four inch schedule 40 PVC casing will be installed with a .01 inch Howard Smith wire wrap screen rather than a Johnson wire wrap screen which had been previously used. The filter pack will be #30 mesh Monterey sand, sized using the DOHS decision tree. It is expected the wells will be screened from a depth of approximately 55 to 75 feet, however the exact depths will be determined in the field. Quarter inch bentonite pellets will be tremied down the annulus and placed at a depth of approximately 2 feet above the top of the screened section. Potable or formation water will be used for hydration of the bentonite and mixing of the cement. A cement grout, made up of approximately 3% bentonite, will fill the annulus of the well to within 5 feet of the ground surface. Concrete will be filled to within approximately 6 inches of the ground surface and a locking box will be placed in the cement at the top of the casing. A locking Christy box with a metal cap will be installed about 3 inches above the surrounding ground surface to prevent water ponding in the area. The monitoring well will be protected with a 3 foot high concrete manhole protector. All three wells will be installed and developed during the first three days of drilling. The forth day will be reserved for cementing and completing. Development will involve bailing approximately five well volumes from the wells using a four inch bailer. It is not expected to encounter contaminated water so the purged water will be discharged on the ground. The wells will be sufficiently developed to allow clean, sediment free samples to be withdrawn. All equipment and materials used will be thoroughly steam cleaned before use and between wells. The tentative dates for the installation of these wells is April 17 through 20. Sampling of the wells for the second quarter will take place approximately two weeks after installation and will be in accordance with the Forward Sampling and Analysis Plan, previously submitted by EBA.