HYDRO22356 - Laserfiche WebLink

Home Browse Search

COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT. Water Quality Control Division Rationale -Page 9, Permit No. CO-0000221 Table V/-4 - Ejjluent Lirtitatians Jor Outjal! 008 • Discharge limitations Maximum Concentrations Parameter 30-Day Avg. Daily Max. Rationale Flow, MGD Report Report Design Capacity TSS, mg/P* 35 70 Federal Effluent Guidelines Total Recoverable Iran, mg/P 1.0 Report Water Quality Standards Settleable Solids, mP/P* Report 0.5 Federal Effluent Guidelines Oi[ and Grease, mg/P Reparl IO State Effluent RegulaNanr pH, s.u. (minimum-maximum) N/A 6.5-9.0 Water Quality Standards WET, Chronic Lethality N/A No Statistical Stare Effluent Regulations Difference Table VI-5 - Ejjluent Limitations jot Outfa[l 009 Discharge limitations Maximum Concentrations Parameter 30-Day Avg. Daily Mas. Rationale Flow, MGD Report Report Design Capacity TSS, mg/P* 35 70 Federal Effluent Guidelines Total Iron, mg/P* 3.0 6.0 Federal Effluent Guidelines Settleable Solids, mP/P* Report 0.5 Federal Effluent Guidelines Oil and Grease, mg/P Report 10 State Effluem Regulation pH, s.u. (minimum-maximum) N/A 6.5-9.0 Water Quality Standards * Total Suspended Solids and Total Iron limitations are Primary Limitations, and Settleable Solids limitations are Alternate.I.imitarions. Exemption from these limitations due to storm evems is subject to burden of proof requirements -see section VI.A.3.b). 2. Total Maximum Daily Load (/MDLI Analysis (Water pualin~ Based Effuent Limitations): Water qua[iry standard (WQS) based fora! recoverable iron limitations apply to outfalls 004 and 008. In order ro calculate WQS based limitations, a Total Maximum Daily Load (IMDL) analysis was performed. In most situations, a mass balance equation is used to determine the effluent concentrations Char would not violate the allowable insrream concentrations defined by the water qualin~ standards (except in the case of pH, where the limitations are set directli from stream standards or effluent regulations ~vithour using a mass balance approach). The mass balance equation is: ~ MtQr - MtQr Mr = Q: Where: Q, = Upstream low flow (/E3 or 30E3) Jrom Table 1/!-2. Qt = 30-day average combined effluent flow for N004 and 008 (highest month from Table VI-8) Q~ = Combined downstream Jlow (Qr + Qr) Mr = Upstream background pollutant concemration from section lII.B.I. Mr = Unknown; Maximum allowable effluent pollutant concentration calculated using mass balance equation Mt = Maximum downstream allowable pallutanr concentration (stream standard)