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COLORADO DEPARTMENT OF HEALTH <br />Watn Quality Coturo! Division <br />WQCD-PE-B2 <br />4300 Cherry Creek Drive South <br />Denvn, Colorado 80222-1530 <br />• <br />ADDENDUM TO RATIONALE <br />SAND AND GRAVEL PRODUCI70N OPERATIONS <br />(AND OTIiER NONMETALLIC MINERALS ESCEPT FiIFl) <br />GENERAL PERMIT IN COLORADO <br />COLORADO DISCHARGE PERMIT NUMBER COG500000 <br />PURPOSE OF AMENDMENT <br />The renewal permit did not include the specific numeric limiu for proous water disdtargu from the industrial sand category, <br />which is rovered by the Federal Efjlttenr Guidelines (40 CFR 436, Subpart DJ. Tharforc, the permit has been mod~ed to <br />include the appropriate limits for this category. the industrial sand rotegory was previously included in the list of facility types <br />in paragraph a, below. Under the new category (paragraph e, below), the 30day average TSS limit is slightly strider, and a <br />daily maximum limit it included, as opposed to a 7.day avnage limit. the other limns are the same. <br />the Federal E,jjluem Guidelines also rover proses-generated wasttwaterfrom facilitiu employing HF (FlydrofluoricJJloration. <br />However, this pmrtit does nor include the Federal mtmeric limit/ for this type of fariliry. Thv is a general permit, designed to <br />rover the widut possible range of faciluiu with similar wastewatn diamderisties. In effedi~ely achieving this broad rnvcrage, <br />t ermit must also be relatively simple. Therefore, some of the more individualistic or romplec eflTuem limitatioru, such as for <br />s-generated wastewater from industrial sand facilities employing !iF flotation, arc not included in this permit. <br />Industrial sand facilities employing IIF flotation arc not allowed to dischmge process water under this permit. If an applicant <br />wishes to discharge process water from this type of facility, thry must apply for an individual pnmit. However, this type of <br />facility may discharge stormwater under this permit, as allowed under Part I. C of the pernrit. <br />1. Numeric Limitations: Numeric limiu will be applied for some of the industrial tategories rovered by rhir permit. <br />Thue limits are from the EPA Federal Guidelines for the applicable point sourtx category, as follows: <br />a. Mints! mining and processing point soum category - 40 CFR 436 - subpart B (meshed stone), C <br />(ronstrudion sand and gravel), R (phosphate rock) -and aU other industrial fadlities rovered uruler SIC Code <br />I4, except those specifically listed in paragraphs b and c below, and ronaete batdt plants boated at any facility <br />otherwise ro~rred by this genera! permit: <br />Table 1 - Ejflucat Limits <br />Parametn Limit Rationale <br />Flaw, MGD Report a/ NA <br />7SS, mg/1 30/45 b/ State Effluent Regulations <br />pH, s. u. 6.5-9.0 e/ Water Quality Standards <br />Oil and Grease, mgR 10 a/ State EfjIuem Regulations <br />Total Dissolved Solids, mg/1 Report a/ Salinity Regulations <br />(Colo. River Basin only) <br />To~Phosphorus (as PJ, mg/l Report a/d/ Best Professional Judgment <br />on following page. <br />