A. Generally: Local limits for specific pollutants discharged pursuant to this chapter shall be as follows:
1. Dilution: Dilution of the discharge from a pretreatment facility or from a regulated process is prohibited as a method for treatment of wastes in order to meet the limits set forth in this chapter.
2. Sample Location: Measurement of pollutant concentrations to determine compliance shall be made at the point immediately following the pretreatment facility and before mixture with other waters, unless another point is designated by the WRA Director. If necessary, the concentrations so measured shall be recomputed to exclude the effect of any dilution that is improper using the combined waste stream formula.
B. Headworks Limits; Average Mass: The average composite loading of all industrial users contributing the following specific pollutants to the POTW shall not exceed the allowable total pounds. The allocation of pollutants between industrial and nonindustrial sources may be adjusted by the Director provided that the allowable total loading for any pollutant at the headworks of the WRF is not exceeded.
Pollutant | 30-Day Average Allowable Pounds/Day | |
Total | Industrial | |
BOD | 195,600 | 135,153 |
TSS | 300,400 | 208,463 |
NH3 | 13,000 | 6,959 |
TKN | 27,760 | 16,950 |
Pollutant | Maximum Allowable Headworks Loading Pounds/Day | Maximum Allowable Industrial Loading Pounds/Day |
Pollutant | Maximum Allowable Headworks Loading Pounds/Day | Maximum Allowable Industrial Loading Pounds/Day |
Arsenic - T | 7.58 | 3.81 |
Cadmium - T | 3.65 | 2.16 |
Chromium - T | 136.35 | 120.90 |
Copper - T | 148.56 | 125.51 |
Cyanide - T | 17.08 | 8.28 |
Lead - T | 28.17 | 20.94 |
Mercury - T | 0.999 | 0.747 |
Nickel - T | 87.27 | 75.75 |
Silver - T | 23.30 | 19.77 |
Zinc - T | 360.59 | 283.53 |
C. Discharge Concentration Limits And Review Criteria: Discharge concentration limits and review criteria shall be as follows:
1. Review Of Discharges: The discharge into the POTW of any materials, water or waste having a pollutant concentration greater than the limits in subsections C3, C4, and C5 of this section or containing pollutants not listed herein shall be subject to the review and approval of the WRA Director. After review of the proposed discharges, the WRA Director may:
a. Reject the waste for reasons consistent with section 8-3-5 of this chapter.
b. Require pretreatment to an acceptable pollutant concentration for discharge to the POTW.
c. Require control of the quantities and rates of discharge of the water or waste.
d. Require payment to cover the added cost of handling and treatment of water and waste or any combination thereof.
e. Reduce the maximum or average mass loading of present and prospective individual users on any reasonable prorated basis to meet headworks loading limits at the WRF.
f. Require the user to obtain a wastewater discharge permit and be subject to any of the rules and regulations contained therein.
g. Require the user to meet local limits when local limits are more restrictive than National Categorical Pretreatment Standards, provided that headworks loading limits are met.
h. Initiate enforcement action in response to any noncompliance with this chapter using the enforcement procedures outlined in this chapter.
i. Take any combination of the steps in subsections C1a through C1g of this section, as appropriate.
2. Industrial Users: Users discharging wastewater to the POTW whose pollutant concentrations or flows are greater than the following shall be considered industrial users for purposes of sewer charges and may be regulated or permitted by the WRA Director as appropriate:
Pollutant | Daily Maximum (mg/L) |
Pollutant | Daily Maximum (mg/L) |
BOD | 200 |
TSS | 250 |
COD | 300 |
O&G - T | 100 |
TKN | 30 |
NH3-N | 15 |
An average daily flow greater than 5,000 gallons or having an unusual concentration of flow. | |
3. Pollutant Limits: Average and maximum concentration limits for users without National Categorical Pretreatment Standards for these pollutants shall be as follows:
Pollutant | Daily Maximum (mg/L) | Monthly Average (mg/L) |
Pollutant | Daily Maximum (mg/L) | Monthly Average (mg/L) |
Arsenic - T | 0.38 | 0.25 |
Cadmium - T | 0.08 | 0.05 |
Chromium - T | 6.43 | 4.29 |
Copper - T | 10.21 | 6.80 |
Cyanide - T | 0.53 | 0.36 |
Lead - T | 1.43 | 0.95 |
Mercury - T | 0.042 | 0.028 |
Nickel - T | 7.22 | 4.81 |
O&G - T | 400.0 | - |
O&G - Mineral | 100.0 | - |
Silver - T | 1.30 | 0.87 |
VPH | 10.0 | - |
Zinc - T | 19.64 | 13.09 |
pH range - not lower than 5.0 or greater than 12.0 | ||
Temperature (liquids or vapors) - not greater than 150°F at point of entry | ||
4. Daily Maximum Pollutant Limits For Hauled Waste: Wastes delivered to the WRF by truck or rail shall not exceed the following concentrations in any load or overall daily loading limits unless otherwise approved by the WRA Director:
Pollutant | Concentration (mg/L) | Loading (Pounds/Day) |
Pollutant | Concentration (mg/L) | Loading (Pounds/Day) |
COD | 100,000 | - |
O&G - T | 50,000 | - |
VPH | 10.0 | - |
Arsenic - T | - | 0.014 |
Cadmium - T | - | 0.93 |
Chromium - T | - | 24.74 |
Copper - T | - | 23.71 |
Cyanide - T | - | 0.29 |
Lead - T | - | 6.70 |
Mercury - T | - | 0.12 |
Nickel - T | - | 3.71 |
Silver - T | - | 0.26 |
Zinc - T | - | 87.62 |
pH range shall not be lower than 5.0 or greater than 12.0 | ||
5. Daily Maximum Limit For Gasoline Cleanup Projects: Discharge of wastewater from sites where gasoline is being removed from the soil or groundwater shall meet the following limits prior to discharge to the POTW:
Pollutant | (mg/L) |
Benzene | 0.050 |
BETX | 0.750 |
D. Compliance With Designated Standards: No subsection of this section shall be construed to provide lesser discharge standards than are or that may be imposed and required by U.S. Environmental Protection Agency or the Iowa Department of Natural Resources, nor to allow the average allowable total loading for any pollutant at the headworks of the WRF to be exceeded. (Ord. 1069, 3-14-2019)