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Global Presence <br /> EWr Personal Attention <br /> ion <br /> & ASSOCIATES, INC. SEP 2 6 2008 <br /> ENVIRONMENT HEALTH <br /> San Joaquin County Public Health Services PERMIT/SERV!CES' <br /> Environmental Health Division <br /> 600 East Main Street <br /> Stockton,California 95202-3029 <br /> September 25, 2008 <br /> WORK PLAN FOR <br /> DRILLING AND MONITORING WELL INSTALLATIONS <br /> MANTECA,CALIFORNIA <br /> Dear Sir/Madam: <br /> The following is a Work Plan for drilling and installation of four (4) monitoring wells near the Austin Road <br /> Landfill, Manteca, California (Figure 1) as is required by the San Joaquin County Environmental Health <br /> Department's Application Requirements For A Permit To Drill. The proposed drilling and monitoring well <br /> installation activities are designed to provide additional groundwater quality and extent data for the lower <br /> monitored aquifers at the site per recommendations from the Regional Water Quality Control Board(RWQCB). <br /> In general, the geology of the proposed well locations is comprised of silt, silty sand, and poorly graded sand, <br /> with minor occurrences of thin silty clay zones from ground surface to a depth of approximately 190 feet. <br /> Based on geologic data collected during drilling of water supply wells at the nearby Northern California Youth <br /> Center,brown and blue clay predominates below a depth of about 190 feet bgs. <br /> Past depth to water readings describe depths of approximately 80 feet below ground surface(bgs). Previously <br /> installed monitoring well AMW-13 has a screened interval of approximately 80 to 100 feet bgs. To assist in <br /> defining the vertical component of the groundwater movement, companion well AMW-13B, will be drilled to <br /> monitor a lower saturated zone with a screen interval of 155-175 feet bgs. The pumping wells at the nearby <br /> Northern California Youth Center extract groundwater at depths ranging from approximately 135 to 200 feet <br /> bgs. The screened intervals of the four proposed monitoring wells are intended to quantify potential downward <br /> movement of groundwater along flow paths. As tabulated below, four 2-inch diameter PVC wells will be <br /> installed for the project to the approximate depths noted. <br /> Well/borehole No. Estimated Total Depth <br /> AMW-13B 175 feet <br /> AMW-21 175 feet <br /> AMW-22 175 feet <br /> AMW-23 175 feet <br /> The proposed boreholes will be drilled using mud rotary drilling techniques and soil sampling will occur <br /> every 5 feet during the drilling of each of the four monitoring well boreholes. The use of rock coring <br /> equipment is not warranted for the project. <br /> A Herst & Associates, Inc. geologist, under the direction of a California registered geologist, will log and <br /> characterize all soil samples, and collect those selected for additional analysis. Actual total depths of the <br /> boreholes will be determined by the lithologies and/or hydrologic conditions encountered. Cuttings, logged <br /> 5988 Mid Rivers Mall Drive Telephone(636)939-9111 <br /> St.Charles,Missouri 63304 Fax(636)939-9757 <br />