Laserfiche WebLink
FEB 20 '98 02~S1PM DMG DLIRRNGO FIELD OFFICE <br />- ~ i • <br />P. 2/2 <br />STATE OF C~L~RADQ <br />DIVISION OF MINERALS AND GEOLOGY <br />i Depanmen[ of Natural Resources <br />7 ~ 13 Sherman St., Room 2I5 <br />Denser, Colorado 80203 <br />Phone: (303) 868-3567 <br />Fax: (303) 832-8106 <br />February 20, 1998 <br />Mr. Alan Cox <br />Manager -Environmental Affairs <br />Homestake Mining Company <br />650 California Street <br />San Francisco, California 94108 <br />Roy Romc, <br />Governor <br />lames 5. LochFr:ad <br />Executive D~m~tor <br />Michael d. ions <br />Division Obectnr <br />RE: Bulldog Mine, File M-77-215, Technical Revision No. 7 Adequacy Review <br />Dear Mr. Cox: ~/~~b <br />The Division has completed the adequacy review of Homestake Mining Company's IHM application for <br />Technical Revision No. 7 to Permit No. M-77-215 which addresses sealing th vel adit and <br />implementing a monitoring plan to verify the seal's effectiveness at hydraulically plugging that adit. <br />i <br />i <br />The following concems were identified during the review. Please address these concerns as soon as possible, <br />so the decision due date of March 13, 1998 can be met. <br />1. HMC must provide, for Division approval, all specifications on the concrete chosen for plugging the <br />adit prior to construction of the seal. <br />2. Please provide all specifications on the water drain pipe which will be installed in the plug e.g. ~• <br />to r.,r ~ . 1 ~ ~ rt dy b d! c /, a{~ . <br />3. The plan to monitor for seeps is inadequate and would probably be inconclusive. Please propose a,.,r/ ~ . <br />plan to iraculate the adit, behind the plug, with a tracer that can be used to identify groundwater th~Y~('-oP,a~ <br />may Seep from the mine pool behirxi the plug. The monitoring plan will need to include provision or <br />testing for the tracer substance. a~ seftcf~ ro•«~~~-~-c ~(e wr. 5 raa~r;G-v'~ -P rrr^ t~ /~~ <br />y~gd aa<~ ~ ,,,:cis. mf, rr` rN, ~.6~/ G' . •-•,,,~. <br />4. The last inspection report forlthe Bulldog Mine indicated that caving, in the vicinity of daylight curve, <br />had left the adit roof approximately 30 feet high, as far as could be seen in both directions. Please Gij <br />verify how far toward the portal, this high roof extends. Indicate the ameum of cover between the <br />outermost point of this caved area, and the ground surface. Provide a demonstration that possible <br />saturation of the ground in the vicinity of the adit, at maximum proposed mine pool, will not create <br />a stability problem that could manifest itself in surface slumps or subsidence features. Also that <br />repeated saturation antl draining of this area will not contribtne to such instability problems. <br />If you have questions or need additional information, please contact me at our Durango Field Office, 484 <br />Turner Drive, Building F, Room 101, Durango, Colorado 81301, phone no. 1970) 247.5062_ <br />Sincerely, <br />Steve S. Shuey <br />Environmental Protection Specialist <br />cc: Allen Sorenson <br />