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rart I <br />Page No. 8 <br />Permit No.. CO-0043648 <br />Whole Effluent Toxicity - <br />Chronic Lethali[y Limitation for Point OOIA <br />Beginning on September 1, 1998 for point OOIA, [here shall be no statistically significant difference in lethality (at the <br />9J% confidence level) between the control and any effluent concentration less than or equal to 100% effluent. Such <br />limitation shall apply as a daily maximum. <br />In addition to the limits listed in the above tables, there shall be no discharge of floating solids. <br />See Part I.C. for Definitions. <br />2. Best ManaEement Practices <br />The permiltee shall take all reasonable precautions to prevent any point source discharge into surface waters of the State <br />except as authorized through the terms and conditions that have been assigned to specific discharge points that have been <br />identified in the permit. <br />Any cyanide contaminated waters that must be removed from the leach facility liner leak detection collection points, must <br />be disposed of in a manner that will avoid any possible entry into surface waters, either directly, or through a hydraulic <br />connection to groundwater. <br />The permi[tee shall insure that the excavation, movement and placement of any mine tailings or other materials that might <br />be contaminated with cyanide or other environmental pollutants is tamed out in a manner which will avoid any discharge <br />of pollutants to surface waters of the State. <br />3. Compliance Schedules <br />a. Ammonia Studv - For the four year period between March 1, 1997 and February 28, 2001, the permittee must <br />perform weekly pH and temperature monitoring of the effluem and of Arequa Gulch. <br />All data shall be submitted to [he Division by March 31, 2001, with the renewal application. The Division will <br />determine if ammonia limitations and necessary ammonia removal facilities aze required at [hat time. <br />The pem»ttee shall submit a preliminary report prior to beginning the monitoring study. The report shall be <br />submitted by December 3 L, 1996. This report shall specify the exact instream locations where the perntittee intends <br />to perform the monitoring and what equipment will be utilized N the study. <br />The monitoring program shall utilize the following procedures: <br />(i) Weekly pH and temperature monitoring shall be done in the receiving stream immediately below the point of <br />discharge (there is no stream above the point of discharge). Instream samples shall be taken from the main <br />current. Avoid sampling in slack water or eddies. At the e111uent, collect and analyze for ammonia on a <br />monthly basis and also determine temperature and pH on a weekly basis. <br />(ii) Instream samples should normally be taken between 9:00 a.m. and 11:00 a.m. Twice per year (during summer <br />and winter low flow periods), diurnal variability shall be determined by sampling at 6:00 a.m., 10:00 a.m., <br />2:00 p.m., and 6:00 p.m. on the same day. Downstream samples for pH shall also be collected a[ half-mile <br />intervals between one half and [•vo miles below the discharge on these days. <br />(iii) Maintain consistent and uniform procedures for pH observations. For example, if samples are stirred, then stir <br />all samples. Calibrate a battery operated, hand held pH meter with the same range buffers. I[ is suggested that <br />the range be between pH 7 and pH 9. Remember to make the slope correction for temperature. Allow the <br />same amount of time for the pH meter to stabilize each lime. Record [he time of measurement. Also, flush the <br />electrode with deionized water after each pH and temperature determination. <br />