SECTION 201 - GENERAL SEWER USE REQUIREMENTS


201.1 - Prohibited discharge standards.

A.

General Prohibitions. No User shall introduce or cause to be introduced into the POTW any pollutant or wastewater which causes Pass Through or Interference. These general prohibitions apply to all Users of the POTW whether or not they are subject to categorical Pretreatment Standards or any other National, State, or local Pretreatment Standards or Requirements.

B.

Specific Prohibitions. No User shall introduce or cause to be introduced into the POTW the following pollutants, substances, or wastewater:

(1)

Pollutants which create a fire or explosive hazard in the POTW, including, but not limited to, wastestreams with a closed-cup flashpoint of less than 140 degrees F (60 degrees C) using the test methods specified in 40 CFR 261.21;

(2)

Wastewater having a pH less than 5.0 or more than 9.0, or otherwise causing corrosive structural damage to the POTW or equipment;

(3)

Solid or viscous substances in amounts which will cause obstruction of the flow in the POTW resulting in Interference including but not limited to:

Ashes, Cinders, Sand, Mud, Straw, Shavings, Metal, Glass, Rags, Paper products, either whole or ground by garbage grinders, Whole blood, Paunch manure, Hair fleshing, Entrails, Feathers, Bones, Slops, Chemical residues, Paint residues, Bulk solids;

(4)

Pollutants, including oxygen-demanding pollutants (BOD, etc.), released in a discharge at a flow rate and/or pollutant concentration which, either singly or by interaction with other pollutants, will cause Interference with the POTW;

(5)

Wastewater having a temperature greater than 150 degrees F (65.56 degrees C), or which will inhibit biological activity in the treatment plant resulting in Interference, but in no case wastewater which causes the temperature at the introduction into the treatment plant to exceed 104 degrees F (40 degrees C);

(6)

Petroleum oil, nonbiodegradable cutting oil, or products of mineral oil origin in excess of 100 mg/L or in amounts that will cause Interference or Pass Through;

(7)

Any water or wastes that contain more than 10 mg/L of hydrogen sulfides;

(8)

Pollutants which result in the presence of toxic gases, vapors, or fumes within the POTW in a quantity that may cause acute worker health and safety problems;

(9)

Trucked or hauled pollutants, except at discharge points designated by the Commissioner in accordance with Section 202.4 of this ordinance;

(10)

Noxious or malodorous liquids, gases, solids, or other wastewater which, either singly or by interaction with other wastes, are sufficient to create a public nuisance or a hazard to life, or to prevent entry into the sewers for maintenance or repair;

(11)

Wastewater which imparts color which cannot be removed by the treatment process, such as, but not limited to, dye wastes and vegetable tanning solutions, which consequently imparts color to the treatment plant's effluent, thereby violating the City's NPDES permit;

(12)

Wastewater containing any radioactive wastes or isotopes except in compliance with applicable State or Federal regulations;

(13)

Sludges, screenings, or other residues from the pretreatment of industrial wastes;

(14)

Wastewater causing, alone or in conjunction with other sources, the treatment plant's effluent to fail toxicity test;

(15)

Detergents, surface-active agents, or other substances which that might cause excessive foaming in the POTW;

(16)

Fats, oils, or greases of animal or vegetable origin in concentrations greater than 300 mg/l or in amounts that will cause Interference or Pass Through;

(17)

Wastewater causing two readings on an explosion hazard meter at the point of discharge into the POTW, or at any point in the POTW, of more than 5 percent (5%) or any single reading over 10 percent (10%) of the Lower Explosive Limit of the meter.

Pollutants, substances, or wastewater prohibited by this Section shall not be processed or stored in such a manner that they could be discharged to the POTW.

201.2 - National Categorical Pretreatment Standards.

Users must comply with the Categorical Pretreatment Standards found at 40 CFR Chapter I, Subchapter N, Parts 405—471 which are incorporated by reference herein.

A.

Where a categorical Pretreatment Standard is expressed only in terms of the concentration of a pollutant in wastewater, the Commissioner may impose equivalent mass limits in accordance with Section 201.2D.

B.

When the limits in a categorical Pretreatment Standard are expressed only in terms of mass of pollutant per unit of production, the Commissioner may convert the limits to equivalent limitations expressed either as mass of pollutant discharged per day or effluent concentration for purposes of calculating effluent limitations applicable to individual Industrial Users.

C.

When wastewater subject to a categorical Pretreatment Standard is mixed with wastewater not regulated by the same Standard, the Commissioner shall impose an alternate limit in accordance with 40 CFR 403.6(e).

D.

When a categorical Pretreatment Standard is expressed only in terms of pollutant concentrations, an Industrial User may request that the City convert the limits to equivalent mass limits. However, in accordance with 40 CFR 403.6(c)(5)(iv), mass based limits may not be may not be granted for pollutants such as pH, temperature, radiation, or any other pollutants for which mass limits are not appropriate. The determination to convert concentration limits to mass limits is within the discretion of the Commissioner. The City may establish equivalent mass limits only if the Industrial User meets all the conditions set forth in Sections 201.2D(1)(a) through 201.2D(1)(e) below.

(1)

To be eligible for equivalent mass limits, the Industrial User must:

(a)

Employ, or demonstrate that it will employ, water conservation methods and technologies that substantially reduce water use during the term of its individual wastewater discharge permit;

(b)

Currently use control and treatment technologies adequate to achieve compliance with the applicable categorical Pretreatment Standard, and not have used dilution as a substitute for treatment;

(c)

Provide sufficient information to establish the facility's actual average daily flow rate for all wastestreams, based on data from a continuous effluent flow monitoring device, as well as the facility's long-term average production rate. Both the actual average daily flow rate and the long-term average production rate must be representative of current operating conditions;

(d)

Not have daily flow rates, production levels, or pollutant levels that vary so significantly that equivalent mass limits are not appropriate to control the Discharge; and

(e)

Have consistently complied with all applicable categorical Pretreatment Standards during the period prior to the Industrial User's request for equivalent mass limits.

(2)

An Industrial User subject to equivalent mass limits must:

(a)

Maintain and effectively operate control and treatment technologies adequate to achieve compliance with the equivalent mass limits;

(b)

Continue to record the facility's flow rates through the use of a continuous effluent flow monitoring device;

(c)

Continue to record the facility's production rates and notify the Commissioner whenever production rates are expected to vary by more than 20 percent from its baseline production rates determined in paragraph 201.2D(1)(c) of this Section. Upon notification of a revised production rate, the Commissioner will reassess the equivalent mass limit and revise the limit as necessary to reflect changed conditions at the facility; and

(d)

Continue to employ the same or comparable water conservation methods and technologies as those implemented pursuant to paragraph 201.2D(1)(a) of this Section as long as it discharges under an equivalent mass limit.

(3)

When developing equivalent mass limits, the Commissioner:

(a)

Will calculate the equivalent mass limit by multiplying the actual average daily flow rate of the regulated process(es) of the Industrial User by the concentration-based Daily Maximum and Monthly Average Standard for the applicable categorical Pretreatment Standard and the appropriate unit conversion factor;

(b)

Upon notification of a revised production rate, will reassess the equivalent mass limit and recalculate the limit as necessary to reflect changed conditions at the facility; and

(c)

May retain the same equivalent mass limit in subsequent individual wastewater discharger permit terms if the Industrial User's actual average daily flow rate was reduced solely as a result of the implementation of water conservation methods and technologies, and the actual average daily flow rates used in the original calculation of the equivalent mass limit were not based on the use of dilution as a substitute for treatment pursuant to Section 201.5. The Industrial User must also be in compliance with Section 212.3 regarding the prohibition of bypass.

E.

Once included in its permit, the Industrial User must comply with the equivalent limitations developed in this Section in lieu of the promulgated categorical Standards from which the equivalent limitations were derived.

F.

Many categorical Pretreatment Standards specify one limit for calculating maximum daily discharge limitations and a second limit for calculating maximum Monthly Average, or 4-day average, limitations. Where such Standards are being applied, the same production or flow figure shall be used in calculating both the average and the maximum equivalent limitation.

G.

Any Industrial User operating under a permit incorporating equivalent mass or concentration limits calculated from a production-based Standard shall notify the Commissioner within two (2) business days after the User has a reasonable basis to know that the production level will significantly change within the next calendar month. Any User not notifying the Commissioner of such anticipated change will be required to meet the mass or concentration limits in its permit that were based on the original estimate of the long term average production rate.

201.3 - Local limits.

A.

The Commissioner is authorized to establish Local Limits pursuant to 40 CFR 403.5(c).

B.

The following pollutant limits are established to protect against Pass Through and Interference. No person shall discharge wastewater containing in excess of the following:

Contributory User 30 day Avg. mg/L Wilmington POTW Maximum Allowable Industrial Loading lbs/day
Arsenic 0.09 8.18
Cadmium 0.07 9.15
Chromium, total 4.00 177.66
Copper 0.91 108.39
Lead 1.94 175.97
Mercury 0.0057 0.42
Nickel 1.00 206.40
Selenium 0.65 67.46
Zinc 3.49 422.37
Ammonia as Nitrogen 35.00 4950
Cyanide 0.49 79.59
Phenolics, total 10.00 6780
BOD 500.00 118991
Suspended Solids 500.00 72268

 

The above limits apply at the point where the wastewater is discharged to the POTW. All concentrations for metallic substances are for total metal unless indicated otherwise.

C.

Significant Industrial Users shall, when operationally feasible, take steps to minimize wastewater discharge during periods of high flow (i.e. wet weather events such as rain or snow-melt).

D.

The Commissioner may develop Best Management Practices (BMPs), by ordinance, or by rule, or in individual wastewater discharge permits or general permits, to implement Local Limits and the requirements of Section 201.1

201.4 - City's right of revision.

The City reserves the right to establish, by ordinance or in individual wastewater discharge permits or in general permits, more stringent Standards or Requirements on discharges to the POTW consistent with the purpose of this ordinance.

201.5 - Dilution.

No User shall ever increase the use of process water, or in any way attempt to dilute a discharge, as a partial or complete substitute for adequate treatment to achieve compliance with a discharge limitation unless expressly authorized by an applicable Pretreatment Standard or Requirement. The Commissioner may impose mass limitations on Users who are using dilution to meet applicable Pretreatment Standards or Requirements, or in other cases when the imposition of mass limitations is appropriate.