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:._ <br />E <br /> <br />~. ~~iiiiliii~~iii~i-i~ <br />999 <br />N~ ~ ~ r ~~C ~ ~~~ - RECEIVED <br />I/ ~ ~ ' JUL 2 6 1999 <br />July 12, 1999 <br />TO: Mr. D. Edwin Hogle, Mail Code 8P-W-GW <br />U. S. Environmental Protection Agency <br />Region VIII <br />999 18'" Street, Suite 500 <br />Denver, Colorado 80202-2466 <br />FROM: Robert L. Tobin ~ .~ ~ 0°-'u"--~ <br />Division of Minerals 8 Geology <br />Member, Rio Blanco County Planning Commission <br />Water Quality Hydrologist (USGS), Ret. <br />P.O. Box 1065 <br />Meeker, Colorado 81641 <br />SUBJECT: Comments on the Draft Statement of Basis, Yankee Gulch Project <br />Class III Solution Mining Wells, Rio Blanco County, Colorado, EPA <br />Area Permit number: CO3858-00000-To be issued to American <br />Soda, L.L.P. <br />Listed below for your consideration are several comments/concerns on the <br />subject document. Other minor comments are shown in the margins of selected <br />pages from the Statement of Basis (SOB) (attachment 3). <br />Concentrations and ranges of concentrations of dissolved solids as <br />presented in the SOB and used to characterize the water quality of the <br />upper and lower aquifers contain anomalously large values when <br />compared with the large amounts of published and unpublished data of <br />the U. S. Geological Survey (USGS) (Ficke and others, 1974; Weeks and <br />Welder, 1974; Dale and Weeks, 1978; and Welder and Saulnier, 1978). It <br />is generaNy recognized that large concentrations of dissolved solids <br />(greater than 10,000 mgll) usually occur only near the dissolution surface, <br />along fractures and faults that expose salt deposits to groundwater, and in <br />association with improperly completed wells (Saulnier, 1978). <br />Furthermore, caution must be used in accepting, at face value, reported <br />large concentration of dissolved solids sampled from wells that contain <br />inbore solution activities {Robson and Saulnier, 1981; and Saulnier, 1978). <br />After extensive review, Saulnier, (1978), found that much of the early <br />descriptions of the basin were greatly exaggerated. A review of the data <br />will show that dissolved solid concentrations in both the upper and for <br />most of the lower aquifer generally are less that 5000 mg/I throughout <br />most of the basin (attachments 1 and 2). Concentrations of dissolved <br />solids have been shown to exceed 10,000 mg/I mostly from wells in the <br />extreme northern parts of the basin along a fauk zone approximately 10 <br />