SITE INFORMATION AND CORRESPONDENCE (2)

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0 0 Evaluation of Potable Water Sources Page 3 Ranch Market Site 23569 S Santa Fe Road Riverbank CA August 18,2000 Subcontracted Test Borings and Well Installation Costs Test Boring- A single test boring will be drilled in the southeast corner of the Pantoja property (Figure 2). The boring will be drill using a mud rotary rig to a total depth of 600 feet bgs. In order to determine a specific depth where the Community Water Standards can be met, depth discrete water samples will be collected at 250 feet and 600 feet bgs using a Maxi-SimulProbe equipped with a two 2-liter sampling canisters. When the test boring has been drilled to 250 feet bgs, the SimulProbe will run into the hole on drive rods and driven into the native soil. A depth discrete soil and water sample will be collected, the sampler retrieved, and the water transferred into analyses specific containers. The boring will be deepened to 550 feet and second soil and water sample collected. The boring will be deepened to 600 feet bgs and an electric log will be run down hole to identify the depth and thickness of specific high permeability water zones from 50 to 600 feet bgs. After running the electric log, the soil boring will be grouted back to grade using neat cement and the drilling rig will leave the site. Per the SJCEHS requirement, the two water samples will be analyzed for the Title 22 Drinking Water Analytical Suite for Community Water Systems. If the water sample collected at 250 feet bgs meets the drinking water standards, a drilling company would be contracted to install a well to 250 feet bgs. If the shallow water sample does not meet the water standards and the 600 foot water sample meets the water standards, a deeper well will need to be installed. Prior to mobilizing the drilling rig, the electric log will be reviewed to identify and select the best sand zone or zones for completion. Well Installation- Per the SJCEHS requirement, an annual seal of 200 feet or more will be set above the screened interval of the water well. The shallow or deep well will be screen across a water-bearing zone, have a gravel pack, overlying bentonite seal, and be grouted from the top of the bentonite to grade. The well will be installed adjacent to the deep test boring (Figure 2). A copy of Bid Request Sheet detailing the proposed scope of work has been included in Attachment 2. Cost Comparison- Domestic Well or Future Community Supply Well In the event one or more of the three remaining active domestic water supply wells, DW-1,DW- I, or DW-4,become impacted with dissolved concentrations of MtBE or other gasoline compound, SECOR expects the SJCEHS will require the impacted well be replaced with a well capable of supplying potable water to the property. In order to be prepared for the possibility that an additional well or wells may be required,the well installed on the Pantoja property could be designed and completed to meet the demand of 1 to 5 domestic properties. The pump and pressure tank would be specified to supply one property. In the event the additional homes needed potable water, the pressure tank and pump could be upgraded to meet the demand. The only additional cost would be for trenching and installation of the lateral line to each home. Referring to Attachment 2, the drilling company Bid Request Sheets present cost estimates for the following replacement wells: File:Ranch MarkeflPotWaterSource.hr.doc