SITE INFORMATION AND CORRESPONDENCE

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Rainwater Car Wash - 2 - 18 September 2013 420 W. Yosemite Ave., Manteca San Joaquin County monitoring well will be located in a separate boring (3 depth discrete borings per location) and constructed of 2" diameter polyvinyl chloride casing with 0.020" perforated screen set from 10' to 30' bgs (A zone), 70' to 85' bgs (B zone), and 130' to 155' bgs (C zone). Fluids and soil cuttings generated during the wells installation will be captured and properly disposed offsite. AAAI stated the new wells installation will be completed and a report submitted by mid-December 2013, with the schedule contingent upon no major changes required by the permitting agency, the San Joaquin County Environmental Health Department (SJCEHD). Comments: 1. On 11 September 2013, 1 discussed the proposed CMT wells destruction with Adrienne Ellsaesser, at San Joaquin County Environmental Health Department (SJCEHD). SJCEHD recently witnessed problems with another consultant attempting to over-drill CMT wells where the drill bit became so severely entangled in the casing that the entire 70' of hollow stem auger drill string locked up and was abandoned in the boring without properly destroying the CMT well. SJCEHD stated that CMT wells must be destroyed first by explosives and later over-drilling the boring. You must also contract with a licensed well demolition company (Table 1, a list of experienced explosive companies licensed in the Stockton area) to use explosives to physically destroy the wells prior to over-drilling. The line charge explosive will be placed down the unused central chamber (G) of the CMT well (Figure 3) to total depth without grouting any of the CMT well chambers before destruction. The destroyed CMT well casing will then be over-drilled as described in the Workplan slowly so as to not entangle the drill bit that is 4" larger in diameter than the original boring (e.g., 12" bit for 8" boring) and the open boring (not through the augers) will be filled from bottom to surface through a trime tube under 25 psi with a 30% bentonite mix of grout or free fall through a large trimie tube with coated or slow hydrating 30% bentonite chips to at least 3 feet below surface grade. The Workplan is approved with the SJCEHD modifications and any further changes as necessary to ensure compliance with SJCEHD well permitting requirements. 2. 1 concur the work outlined in the Workplan Addendum is necessary and appropriate to determine the vertical and lateral extend of the groundwater impacts. Drilling with a hollow stem auger will be attempted at the first well location. If the auger rig is unsuccessful in reaching the total depth needed to complete the investigation, then a mud rotary rig will be used for those zone(s). 3. The B zone and C zone well screens must be reduced to 10' in length (e.g, 70' to 80' bgs and 130' to 140' bgs) and located within the higher permeable portion of the zone based on the lithology recorded by the geologist or engineer in the field. 4. Please provide an email with the cost comparison for HSA, MR and Sonic drilling methods, based on local driller's costs, by 75 October 2013 in the first monthly email progress report, and continue submitting monthly email progress reports on the 15th of each subsequent month until the two well reports listed below are received by this office. 5. The two well reports, the well destruction and the new well installation reports, are both due 30 January 2014 to allow additional time to contract for the modifications described above.