SITE INFORMATION AND CORRESPONDENCE

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Mr. Troung Mai Arcady Dump Site Holt, California - 3 - 1 December 2000 8. Page 3-3 During 1998, ERM inspected All wells MWS, MW6, MW7 and MW8 Section 3.2 six existing monitoring wells must be located and abandoned pursuant to (MW-3 through MW-8) on the San Joaquin County's well abandonment southern parcel. Only two of requirements. In addition, the proposed these wells (MW-3 and MW-4) wells MW 13 and MW 11 will replace MW8 are usable. and MW5, respectively. No wells have been proposed to replace MW6 and MW7. Two additional wells must be installed at those locations. To prevent the burial of wells in the future, the new wells should be completed as above ground completions, protected by bollards, whenever possible. 9. Page 3-4 Placement of one Background The placement of a background well Section 3.2 well downgradient of the site is not appropriate. 10 Page 3-5 Lithologic descriptions Drill cuttings will not provide the detail Section 3.2.1 recorded by the geologist will needed for identifying the contacts of the be based on visual inspection units, the physical components of the units of the drill cuttings. or the any internal structures within these units. Therefore, all new monitoring wells should be logged in detail from the surface to the total depth of the borehole. 11 Page 3-5 The well screen will consist of The selection of the well screen size and Section 3.2.1 threaded,flush joint pipe with filter pack cannot be determined until the 0.010-inch slot size. Each intended screen interval is encountered, monitoring well will be described and sieved. Include with your screened from the top of the boring logs a copy of the sieve analysis plot piezometric surface to total for each new well. For this procedure refer depth, with allowance for to ASTM D5092-90 (1995)el Standard seasonal fluctuations of up to S Practice for Design and Installation of feet. The annual space Ground Water Monitoring Wells in between the well screen and the Aquifers. borehole wall will be backfilled with clean, washed, well- Furthermore, the location of this site may graded, 10/20 silica sand to 2 cause difficulty during the well installation, feet above the screened due to the possible artesian conditions that interval. may exist. An explanation must be provided that explains how your rig geologist will identify and document this situation and how the well will be screened if this occurs.