Laserfiche WebLink
DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866 -3567 <br />FAX: (303) 832 -8106 <br />November 27, 2012 <br />STATE OF COLORADO <br />COLORADO <br />p IV] 5 I ON OF <br />RECLAMATION <br />MINING <br />SAFETY <br />John W. Hickenlooper <br />Governor <br />Mike King <br />Executive Director <br />Joe Lamanna <br />Loretta E. Pineda <br />Holcim (US), Inc. Director <br />3500 Highway 120 <br />Florence, CO 81226 <br />Re: Portland Limestone Quarry, Permit No. M- 1977 -344, Revised Groundwater <br />Monitoring Plan <br />Mr. Lamanna: <br />The Division of Reclamation, Mining and Safety (DRMS) has reviewed your proposed standards <br />for MW -13 (reference Holcim letter to DRMS dated July 7, 2010). The data collected from MW -13 <br />is intended to supplement data collected from MW -7. The DRMS approved numeric protection <br />levels (NPLs) for MW -7 on February 24, 2009. <br />The DRMS determines NPLs based on the five quarters of monitoring data initially collected from a <br />proposed monitoring well, not from nearby or upgradient wells. The selected NPL is typically the <br />larger of two values: 110 percent of the maximum concentration of a constituent of interest <br />observed during the five quarters of monitoring; or the mean observed concentration of the <br />constituent plus two standard deviations. Based on the five quarters of data provided by Holcim for <br />MW -13, the DRMS has determined the following NPLs are appropriate; <br />Parameter <br />NPL for MW -13 <br />Previously Approved NPL for MW -7 <br />Total Dissolved Solids (TDS) <br />4,026 mg/f <br />* <br />3,918 mg/f <br />Sulfate (SO4) <br />2,200 mg/f <br />* <br />2,080 mg/f <br />Potassium (K) <br />13 mg/f <br />*t <br />17 mg/f <br />Sodium (Na) <br />274 mg/f <br />* <br />226 mg/f <br />Iron (Fe — dissolved) <br />0.13 mg/f <br />$ <br />4.5 mg/f <br />Manganese (Mn - dissolved <br />0.30 mg/f <br />$ <br />0.88 mg/f <br />* 110% of maximum observed value <br />$ Mean observed value plus 2 standard deviations <br />Holcim will continue to monitor MW -12 (background) and MW -7 (west compliance well), and <br />provide results for the above parameters on an annual basis. When observed parameters in MW -7 <br />and/or MW -13 (east compliance well) exceed the NPL by more than 10 percent, Holcim will <br />increase the monitoring frequency to semi - annually. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines <br />