2009-03-06_PERMIT FILE - C1981012A (6)

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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division Rationale - Page 5, Permit No. CO-0000906 Pursuant to Section 100. 6.2 of the Water and Wastewater Facility Operator Certification Requirements, this facility will require a Class C certified operator due to the use of chemicals to enhance settling/precipitation. Note that the permit application indicates that the current operator in charge only holds a Class D license. C. Groundwater Protection Section 61.14(9)(a) of the Colorado Discharge Permit System Regulations indicates that if "seepage from the impoundment does not exceed I x 10-6 cm/sec ("Allowable Seepage') will be considered not to have a discharge to waters of the state. " However, for facilities that exceed the allowable seepage rate, the discharge to groundwater must be permitted. As previously noted, permitting exceptions are provided for discharges consisting totally of industrial wastewater. It is not definitively known if Pond 6 currently meets the allowable seepage rate of I x 10-6 cm/sec. However, based on discussions with DRMS representatives, Pond 6 is not expected to meet the allowable seepage rate. There are specific procedures that the permittee must follow to prove they are discharging less than the allowable seepage rate. These have been set forth a part of a compliance schedule discussed later in this rationale. The State's effluent limitations in Regulation 62, Regulations for Effluent Limitations, must be met prior to mixing with other waters including groundwater. Thus, at Internal Outfall 033, the limits from Regulation 62 will apply after completion of the seepage rate analysis. For other pollutants, groundwater standards can be met in the groundwater alluvium and therefore permit requirements relative to the development of a groundwater protection program have been included as a compliance schedule in the permit. Note that the development of the groundwater protection program follows the determination of the allowable seepage rate, so that conditions will not be imposed that are not necessary. Additionally, if Pond 6 does not exceed the allowable seepage rate, the State's effluent limitations in Regulation 62, Regulations for Effluent Limitations do not apply (as Pond 6 will not be considered to be a discharge to state waters); in this instance, the permittee will need to request a permit modification to eliminate internal Outfall 033 limits, as well as influent monitoring requirements at Outfall 3001.. V. PERFORMANCE HISTORY A. Monitoring Data 1. Discharge Monitoring Reports - Tables V-1 and V-2 summarize the effluent data for Outfalls 007A and 008A, respectively, reported on the monthly Discharge Monitoring Reports (DMRs) for the New Elk Mine facilityfrom June 2002 through December 2008 based on quarterly reports. Note that there was no discharge from Outfalls 001A, 004A, 009A or 033A during the life of the previous permit. Table V-1- Summary of DMR Data at Outfall 007A - #Samples Reported Average, RePorted,Maxmum . Previous Number'of or Parameter Concentrations Concentrations Avg/Max Limit Reporting Avg/MiheMaae-' Aug/Min/Max Permit Limit Excursions Periods Effluent Flow (MGD) 1 0.1210.1210.12 0.2210.2210.22 Report/Report 0 pH (su) 8.1/8/8. / * 8.218 118.2 * 6.5-9,range 0 TSS, effluent (mg11) 0 Exemption** Exemption** 35170 0 .Oil and Grease (mg11) I NA/NA/NA 31313 NA/10 0 Fe, Tot (1.10) 0 Exemption" * Exemption * * 3.517 0 _ -Settleable Solids (mis) I NA/NA/NA 1.1/I.1/I.I NA10.4 0*** * The summarized concentrations under the 30-day average are the minimum pH concentrations and un der the daily maximum are the maximum pH concentrations. * * The facility was exempt from monitoring for TSS and Fe du ring the discharge events. * * * Violations of the settleable solids lim its were not indicated and therefore it is assumed that the facility qualified for relief provisions under the permit. 0 NA means Not Applicable < means less than > means more than