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Discharge Prohibitions and Local Limits

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The City Municipal Code Chapters 14.08.310 prohibits the discharge of certain pollutants that can cause harm to the sanitary sewer or treatment plant, endanger the public, worker health & safety or the environment.

The Code also limits the discharge of other pollutants under Chapter 14.08.312 to 14.08.314. The City may also charge a surcharge fee for pollutant loads high in BOD, TSS or TKN.

General Prohibitions (Code Chapter 14.08.310)

No discharger shall contribute or cause to be discharged, directly or indirectly, any of the following described substances to the POTW. Any discharge in violation of these prohibitions shall be reported to the city by the discharger in accordance with the procedures in Section 14.08.316 unless other procedures are specified in a discharge permit assigned to the discharger.

A. Any liquids, solids or gases which by reason of their nature or quantity are, or may be, sufficient either alone or by interaction to cause fire or explosion or be injurious in any other way to the operation of the POTW or the integrity of the sewer system or cause a danger to the public health or safety. This prohibition includes but is not limited to wastestreams with a closed cup flash point of less than one hundred forty degrees Fahrenheit or sixty degrees Centigrade using the test methods specified in federal regulations, 40 CFR 261.21;

B. Any solid or viscous substances which will or may cause obstruction to the flow in a sewer or other interference with the operation of the wastewater system;

C. Any wastewater having a pH less than 5.0 or having any other corrosive property capable of causing damage or hazard to structures, equipment, or personnel of the system, or interference with the operation of the wastewater treatment plant;

D. Any wastewater containing hazardous substances, toxic, conventional, or nonconventional pollutants in sufficient quantity, either singly or by interaction, which could injure or interfere with any wastewater treatment process, constitute a health or safety hazard to humans or animals, or exceed the limitations set forth in Section 14.08.312 or 14.08.313 of this chapter or the categorical pretreatment standards appropriate for the specific industrial user. Hazardous substances, toxic, conventional or nonconventional pollutants shall include, but not be limited to, any pollutant identified in 40 CFR 122 Appendix D (NPDES Permit Application Testing Requirements) Tables II, III, IV, AND V, or substances alone or in combination with other constituents that are determined to be toxic by the toxicity test as defined in 40 CFR Part 136 for wastewater or the toxicity characteristic leaching procedure (TCLP) test as defined in 40 CFR Part 261 for biosolids;

E. Any pollutant which results in the presence of toxic gases, vapors, or fumes within the POTW in a quantity that may cause a public nuisance or acute worker health and safety problems;

F. Any substance which may cause the POTW's effluent or treatment residues, biosolids or scums to be unsuitable for reclamation and reuse or which may interfere with such reclamation and reuse process. In no case shall a substance discharged to the POTW cause the POTW to be in noncompliance with biosolids use or disposal criteria, guidelines or regulations developed under Section 405 of the Clean Water Act, any criteria, guidelines or regulations affecting biosolids use or disposal developed pursuant to the Solid Waste Disposal Act, the Clean Air Act, the Toxic Substances Control Act or state or local standards applicable to the biosolids management method adopted by the city. A user may not introduce into the POTW any pollutants which cause pass through or interference;

G. Any substances which will inhibit the operation or performance of the POTW or pass through the system and cause the POTW to violate any requirements of any discharge permit issued by the state or federal governments;

H. Any substance with objectionable color not removed in the treatment process, such as, but not limited to, dye wastes and vegetable tanning solutions;

I. Any wastewater having a temperature which will inhibit biological activity in the POTW treatment plant resulting in interference; but in no case, wastewater with a temperature at the introduction into the POTW Treatment Plant which exceeds forty degrees Celsius (one hundred four degrees Fahrenheit);

J. Any slugload, which shall mean any pollutant, including oxygen demanding pollutants (BOD, etc.), released in a single extraordinary discharge episode of such volume or strength as to cause interference to the POTW;

K. Any clean water as described in Section 14.08.270;

L. Any wastewater containing any radioactive wastes or isotopes of such half-life or concentration as to exceed limits established by state and federal regulations;

M. Any wastewater which causes the POTW effluent to exhibit toxicity to test organisms in a standard biological toxicity test as defined by city, state or federal requirements, or which the city determines would be toxic to or impede the treatment capabilities of the biological processes in the wastewater treatment plant;

N. Any petroleum oil, nonbiodegradable cutting oil or products of mineral oil origin that will cause interference or pass through the wastewater treatment plant;

O. Any wastewaters, wastes or pollutants that are delivered to the POTW by truck or other means of surface transport, except at discharge points as are designated by the city. Any discharge at designated points shall be subject to the requirements of this chapter, including but not limited to, the provisions in Sections 14.08.312, 14.08.314, 14.08.319 and 14.08.410.

P. Any emulsifying agents, solvents or enzymes that causes fats, oils or grease to pass through an interceptor causing blockages of or the requirements for excessive maintenance of the sanitary sewer.

Local Limits (Code Chapter 14.08.312)

A. No significant industrial user of the POTW may discharge wastes or wastewaters containing concentrations of pollutants higher than those listed below unless a mass limit is allowed in accordance with Section 14.08.313. The director may prohibit discharge or require the discharge to meet lower limitations than those listed if the discharge is reasonably found to have the potential to cause interference with the treatment capabilities or operation of the POTW. (Effective 4/2/2013.)


Allowable Concentration (mg/L)

Daily Maximum

 Ammonia as N
 Arsenic  0.02
Chromium, T
 Chromium VI
 Copper  3.31
 Cyanide, T
 Lead 0.69 
 Mercury  0.010
 Molybdenum  1.67
 Nickel  3.49
 Silver  0.43

B. No user of the POTW shall discharge wastewater containing greater than 100 mg/L concentration of oil and grease.

C. No user of the POTW discharging from groundwater clean up or underground storage tank cleanup shall discharge wastewater containing greater than 0.05 mg/L concentration of benzene or 0.75 mg/L concentration of total BTEX (benzene, toluene, ethylbenzene and xylenes)

Conventional Pollutants

Certain pollutants which are compatible with the POTW treatment processes may be accepted for treatment subject to a surcharge to cover the costs of such treatment. Regulations governing conventional pollutant surcharges are found in Section 14.08.650. Contact the Industrial Pretreatment Program for permission to discharge at (303) 651-8667.

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