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Ouray Silver Mines, Inc. <br /> 1900 Main St. Unit 1 <br /> PO Box 564 <br /> Ouray, CO 81427 <br /> CkJRAY SoILVER M1%E <br /> To: Colorado Division of Reclamation, Mining& Safety IRCEIE® <br /> 1313 Sherman Street, Rm 215 <br /> Denver, CO 80203 MAR 2 5 2Q21 <br /> From: Brian K. Briggs, P.E.,Chief Executive Officer <br /> Date: March 22,2021 ' 91»l6ti,1y <br /> Subject: PAR Response Extension Request; Revenue Mine, Technical Revision No4�2'to*_A <br /> I I2(d) Mining Permit# M2012-032 <br /> Dear Mr. West, <br /> Ouray Silver Mines Inc. (OSMI) received the preliminary adequacy review(PAR)regarding the <br /> application for Technical Revision 12 to Permit M2012-032 for the Revenue Mine(also known as the <br /> Revenue-Virginius Mine). While OSMI has made progress towards understanding the nature of organic <br /> materials found in GW-4, an additional 45 days is requested thereby extending the PAR response to May <br /> 13, 2021. Our current knowledge and understanding are discussed below, along with the newly available <br /> oil and grease results, followed by our intended path forward during the extension. <br /> As presented in the TR12 request,organic material was noted in GW-4 during the development of the <br /> well. Initially this material was thought to be a small amount of drilling-related fluid from the drill rig. <br /> However repeated attempts to clean the well were not effective,leading OSMI to contact DRMS. DRMS <br /> requested analysis for DRO,GRO, MTBE, BTEX,and Oil and Grease. At the time of TR12 oil and <br /> grease results had not yet been received. Table 2,attached,contains the results for all the requested <br /> constituents. Lab reports are also attached. DRO(C 10-C28)was detected in G W-4 at 8.4 mg/L and S W- <br /> 22 at 0.3 mg/L(an estimated value below the practical quantification limit). Oil and Grease was detected <br /> in GW-4 at 6.6 mg/L and was not detected at SW-22. The detection of DRO at SW-22 was reported to <br /> the CDPHE spill hotline even though no groundwater(Regulation 41), nor surface water(Regulation 61), <br /> standard exists for DRO and that no sheen or sludge had triggered mandated reporting(40 CFR 110).No <br /> surface water sheen has been observed. A review of the site Archeological Report(sent to DRMS under <br /> confidential cover with the TR12 request)revealed that GW-4 is located downgradient and proximal to a <br /> mill machine shop that burned down in 1916, suggesting that the material is historic and,therefore, <br /> ambient groundwater quality (Rule 1.1(6)). <br /> OSMI has engaged third party consultant Geosyntec of Denver,to create a short list of analytes from the <br /> more than 100 organic constituents in Table A of Regulation 41 that might be reasonably expected in <br /> historic machine shop waste or modern drilling fluid. OSMI will sample GW-4 for these constituents and <br /> report the results to DRMS in the PAR Response. OSMI also proposes to continue monthly sampling <br /> SW-22 for DRO on a visually contingent basis. A grab sample will be taken from the bridge station SW- <br /> 22,the sample will be visually inspected for oil sheen. If an oil sheen is visible, a sample will be sent to <br /> ACZ for DRO analysis. OSMI will send a letter with visual contingent and laboratory results(where <br /> applicable)with 15 days. If constituents from the Table A short list are found in GW-4,then SW-22 will <br /> be analyzed for the same constituents seen in GW-4. <br /> Phone: (970)325-9830 ♦ Fax: (970)325-9824 <br />