(A) Flow. No user may discharge or cause to be discharged either directly or indirectly more than 0.0249 Million Gallons Per Day (MGD) of wastewater into the municipal sewage system. Any single user wastewater flow that routinely averages 0.025 MGD or greater will constitute a Significant Industrial User and require the City to develop an Industrial Pretreatment Program in accordance with EPA regulations.
(B) Standard Discharge Limitations. To further protect the City's WWTP processes and discharge requirements from general and non-significant industrial users, the City adopts the following technically-based limits. The Acute Toxicity limitation listed in the following table means that an LC50 of less than 100% shall be considered toxic by the City. No user may discharge or cause to be discharged into the City's wastewater collection system, either directly or indirectly, any wastewater containing concentrations of pollutants in excess of the following:
PARAMETER | LIMIT |
PARAMETER | LIMIT |
Acute Toxicity with Ceriodaphnia dubia | LC50 of 100% |
Arsenic | 0.552 mg/L |
Cadmium | 0.320 mg/L |
Chromium, Total | 0.400 mg/L |
Chromium, IV | 0.400 mg/L |
Copper | 0.038 mg/L |
Lead | 0.648 mg/L |
PARAMETER | LIMIT |
PARAMETER | LIMIT |
Mercury | 0.002 mg/L |
Nickel | 0.592 mg/L |
Selenium | 0.200 mg/L |
Silver | 0.015 mg/L |
Zinc | 0.720 mg/L |
Salinity | 1000 mg/L |
Cyanide | 0.008 mg/L |
Total Aromatic Hydrocarbons | 0.100 mg/L |
Total Aqueous Hydrocarbons | 0.150 mg/L |
Petroleum Hydrocarbons, Oils, and Grease | No floating oil, film, or sheen |
Total PCBs | 0.300 mg/L |
BOD | 500 mg/L |
TSS | 500 mg/L |
(C) Surcharges. Any users that are found in violation of these discharge limits may be subject to surcharges. The following is an example of a surcharge formula and calculation:
Example Surcharge Formula and Calculation:
Monthly Surcharge Rate = bo Bl + so Sl
V1 = Volume of waste water from industrial users, Gallons per month.
bo = Average unit cost of treatment, chargeable to BOD, dollar/pound.
B1 = Weight of BOD (amount above 500 mg/L limit) from industrial users, lbs/month.
so = Average unit cost of treatment, chargeable to SS, dollar/pound.
S1 = Weight of TSS (amount above 500 mg/L limit) from industrial users, pound/month.
Industrial User's Flow = 0.025 MGD
Industrial User's BOD = 600 mg/L
Industrial User's TSS = 800 mg/L
WWTP Annual Budget = $2,000,000
WWTP Average BOD = 215 mg/L
WWTP Average TSS = 250 mg/L
WWTP = 0.600 MGD
V1 = 0.025 x (365 / 12) x 1,000,000
V1 = 760,417 Gallons/Month
Cost per pound to treat BOD (bo) =
bo = ($2,000,000 / 12) / [365 x (215 x 8.34 x 0.600)]
bo = $0.42 / Lb of BOD per Month
B1 = (600 - 500) x 8.34 x (V1 / 1,000,000) B1 = 634 lbs/month
Cost per pound to treat TSS (so) =
so = ($2,000,000 / 12) / [365 x (250 x 8.34 x 0.600)]
so = $0.37 / Lb of TSS per Month
S1 = (600 - 500) x 8.34 x (V1 / 1,000,000) S1 = 1903 lbs/month
Monthly Surcharge Rate = ($0.42 x 634) + ($0.37 x 1903) = $970.39
(D) Exceptions. Any user that wishes to discharge wastes in excess of the limits of this section shall obtain written and signed approval by the Director, and shall maintain a signed copy of this written permission at their main business premises. The Director may allow exceptions only for a limited time and only where technically based calculations determine that the City's WWTP processes will not be adversely affected and where the WWTP discharge will not violate any parameter in their NPDES permit nor violate any water quality standard. Surcharges may also apply.
(E) Pretreatment. The City may require the installation and proper maintenance of filters, grease traps, or other devices determined by the City to be necessary to ensure compliance with this division (A).
(F) Industrial Pretreatment Program. According to federal regulations, the City will be required to develop an Industrial Pretreatment Program for Significant Industrial Users (SIU) whenever it is determined that any single user discharge averages 0.025 MGD or greater, or 5% or more of the WWTP Dry Weather Hydraulic or Organic Loading. The City will also be required to develop user specific technically based discharge limits for each SIU in accordance with EPA requirements and obtain approval of the user specific limits from EPA.
(Ord. No. 2005-18, passed 10-5-05)