Laserfiche WebLink
q ~h <br />- iiiiiiiiiiiiiiuiii <br />999 <br />STATE OF COLORADO <br />MINED LAND RECLAMATION DIVISION <br />Department of Natural Resources <br />1313 Sherman Sl.. Room 215 <br />Denver, CO 80203 <br />303 6663567 <br />FA%:303 832-8106 <br />OF C~Cp <br />i+~,...~.~.;-; O <br />~e ~ ~~ <br />3 /606 ~'~/~f///, <br />Roy Romer, <br />MEMO Gavemor <br />Fred R Rania. <br />Date: Februazy 16, 1991 Dwision Director <br />To: Carl Mounts n <br />From: Randy ,1 <br />RE: Somerset Mine (File# C-81-022), Sanborn Creek PR <br />Per your request I have reviewed Somerset Mine's response to the Division's <br />adequacy concerns #8 and #9 which relate to ground-water issues. I <br />incorporated the applicants responses into the application and re-reviewed <br />the ground-water sections. During my review other concerns were raised which <br />follow. <br />The submittal dated January 16, 1991 from Jim Stover contained analysis of <br />the water samples taken from drill holes SC-1, SC-2, SC-3. The analysis is <br />titled "Somerset Mining Company, Ground Water Monitoring -Sanborn Creek <br />Mine" The results of the analysis showed poor quality water in wells SC-1 and <br />SC-2. The analysis was hard to interpret because sufficient information was <br />not supplied. The holes may be un-cased therefore the analysis may not <br />represent any one particular aquifer. Also I am concerned by the high <br />concentration of sodium and hydroxide and by the alkaline pH of 12.4 in well <br />SC-2 (Na=2395 mg/1, Hydroxide as CaC03= 3600mg/1) . It is possible that these <br />wells were never cased, screened, developed or bailed and the odd analysis is <br />probably due to drilling mud left down in the hole. Conductivity was 10,400 <br />and 23,400 umhos/cm for these two holes respectively; this is 15 and 33 times <br />above the Divisions material damage suspect level 700 umhos/cm. Because the <br />samples were analyzed for turbidity and total dissolved solids may indicate <br />that the samples were not properly filtered and preserved as needed for <br />ground-water sampling.These holes were probably not pump tested so formation <br />permeability still needs to be determined. In order to use these wells to be <br />used as monitoring wells they need to be cased and screened at the sampling <br />interval. <br />I would like the following: <br />1. The well logs should be displayed graphically showing the cased interval <br />and the screened interval. <br />2. Wells should be constructed using current state-of the art, ground-water <br />monitoring well designs. This includes casing, screening at the appropriate <br />interval, gravel packing azound the screen with a suitable material, <br />sealing the annulus and construction of a suitable collar. These designs <br />should be submitted for inclusion into the permit application document and <br />implemented. <br />3. The water analysis should contain the information required in Rule <br />2.03.3(5) which includes the methodology used to collect and analyze the <br />data. <br />1 <br />