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COLORADO DEPARTMENT OF HEALTH <br />Water Quality Comrol Division <br />WQCD-PE-B2 <br />4300 Cherry Creek Drive South <br />Denver, Colorado 80222-1530 <br />ADDENDUM TO RATIONALE <br />SAND AND GRAVEL PRODUC77ON OPER.177ONS <br />(AND OTHER NONMETALLIC MINERALS EXCEPT FUEL) <br />GENERAL PEIUf/T IN COLORADO <br />COLORADO DISCHARGE PERMIT NUMBER COG500000 <br />PURPOSE OF AMENDMENT <br />The renewal permit did not include the specific numeric limits for process water discharges from the industrial sand category, <br />which is covered by the Federal Effluem Guidelines (40 CFR 436, Subpart DJ. Therefore, the permit has been mod~ed to <br />include the appropriate limits for this category. The industrial sand category was previously included in the fist ojjaciliry types <br />in paragraph a, below. Under the new category (paragraph c, below), the 30day average TSS limit is slightly stricter, and a <br />daily masimum limit is included, as opposed to a 7-dav acrrage limit. the other limits are the same. <br />The Federal Effluent Guidelines alto cover process-generated wastewaer from facilities employing HF (HydroJluoricJ flotation. <br />However, this permit does not include the Federal numeric limits for this type ojjariliry. Thisv a general permit, designed to <br />rover the widest possible range of jaci(itiu with similnr K•usrex~atcr charactmstics. In effectively achining this broad cos~erage, <br />the permit must also 6e relatit+ely simple. Therefore, some ojthe more individualistic or romplez effluent limitations, such as for <br />process-generated wastewater from industrial sand facilities employing IIF flotation, are not included in this permit. <br />Industrial sand facilities employing HFJIataian are not allowed ro discharge process water under this permit. Ijan applicant <br />x~isJres to discharge process water from this type of facility, they must apply for an individual perntit. However, this type of <br />facility may discharge slormwaftr under this permit, as allox~ed under Pan I.C ojthe permit. <br />Numeric Limiraionc: Numeric limits x•ill 6e npplied for some of the industrial categories rovered by this permit. <br />These limits are from the EPA Federal Guidelines for the applicable polo source category, as follows: <br />a. Mineral mining and processing point source category - 40 CFR 436 - subpart B (crushed stone), C <br />(construction sand and gravel), R (phosphate rock) -and all other industrial facilities rovered under SIC Cade <br />14, escept those spec~cally listed in paragraphs b and c below, and roncrere batch planes located at any facility <br />otherwise covered by this general permit.• <br />Table 1 - Ejpuent Limits <br />Parameter <br />Limit Rationale <br />Flow, MGD Report a/ NA <br />7SS, mg/l 30/45 6/ State Ejj7uent Regulations <br />pN, s. u. 6.5-9.0 c/ Wan Quality Standards <br />Oil and Grease, mg/I 10 a/ Srae EQluenr Regulations <br />Total Dissolved Solids, mg/l Report a/ Sa/miry Regulations <br />(Co[a. River Basin only) <br />Total Phosphorus (as PJ, mg/l Report a/d/ Best Professional Judgmea <br />Footnotes on following page. <br />