Laserfiche WebLink
o ~ <br />COLORADO DEPARTMENT OF HEALTH <br />Water Quality Control Division <br />Rationale - Page 7 <br />Permit No. CO-0027154 <br />Outfall 005 (Continued) <br />A one-time analysis was performed prior to the permit being amended at the <br />start of the mine water discharge. At that time, the parameters of concern <br />were determined (See addendum to rationale dated February 23, 1983). Since <br />that amendment, monitoring shows that two parameters no longer present a <br />concern. These parameters, hesavaleat chromium and total mercury, are not <br />included in this renewal. <br />Outfall 007 <br />This outfall serves to discharge surface runoff and apoile spring water. <br />Federal BPT and BAT apply to the surface runoff, while state SES and WQS apply <br />to the spoils water. Table 4 shows a comparison of appropriate limitations, <br />as determined by regulations and through effluent monitoring. <br />TABLE 4 <br />Parameter SES W(~S BPT BAT <br />pH, s.u. 6.0 - 9.0 6.5 - 9.0 6.0-9.0 N/A <br />011 sad Grease, mg/1 10 N/A N/A N/A <br />Total Suspended Solids, mg/1 30/45 N/A 35/70 N/A <br />Total Recoverable Copper, mg/1 N/A 0.01 N/A N/A <br />Total Recoverable Manganese, mg/1 N/A 1.0 N/A N/A <br />Dissolved Manganese, mg/1 N/A 0.05 N/A N/A <br />Total Recoverable Zinc, mg/1 N/A 0.05 N/A N/A <br />Total Recoverable Iron, mg/1 N/A 1.0 3.5/7.0 a/ 3.5/7.0 a/ <br />Total Dissolved Solids, mg/1 N/A 5000 N/A N/A <br />Settleable Solids, ml/1 b/ N/A N/A N/A 0.5 <br />a/ BPT and BAT limitations are ex pressed as "total" <br />b/ This limitation applies to dis charges caused by precipitation less than or <br />equal to the 10-year, 24-hour event <br />The WQS-based limitations were derived in the same manner as those for outfall <br />005 described earlier. <br />The total dissolved solids limitation is not a direct water quality standard. <br />Instead, the limitation is best professional ,judgment-derived. Technical <br />publications were researched is order to determine TDS levels which are safe for <br />beneficial use, i.e. livestock and crop watering. There is not total <br />concurrence. However, the majority agree that levels ug to 5000 mg/1 on a <br />chronic basis are safe for cattle watering and most crops. Thus, 5000 mg/1 is <br />specified as a 30-day average limitation (with daily maximums allowable to 7500 <br />mg/1). These limits are consistent with eaisting permits. <br />