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City of Gardner, MA
Worcester County
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Table of Contents
Table of Contents
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 waste streams with a closed-cup flash point of less than 140° F. (60° C.) using the test methods specified in 40 CFR 261.21;
(2) 
Wastewater having a pH less than five 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, but in no case solids greater than 1/2 inch or 1.27 centimeters in any dimension;
(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° F. (65° 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° F. (40° C.);
(6) 
Petroleum oil, nonbiodegradable cutting oil, or products of mineral oil origin, in amounts that will cause interference or pass-through;
(7) 
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;
(8) 
Trucked or hauled pollutants, except at discharge points designated by the Director in accordance with § 553-26 of this chapter;
(9) 
Noxious or malodorous liquids, gases, solids, or other wastewater which, either singly or by interaction with other wastes, is sufficient to create a public nuisance or a hazard to life or to prevent entry into the sewers for maintenance or repair;
(10) 
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;
(11) 
Wastewater containing any radioactive wastes or isotopes, except in compliance with applicable state or federal regulations;
(12) 
Stormwater, surface water, groundwater, artisan well water, roof runoff, subsurface drainage, swimming pool drainage, condensate, deionized water, noncontact cooling water, and unpolluted wastewater, unless specifically authorized in writing by the Director prior to any discharge;
(13) 
Sludges, screenings, or other residues from the pretreatment of industrial wastes;
(14) 
Medical wastes, except as specifically authorized by the Director in a wastewater discharge permit;
(15) 
Wastewater causing, alone or in conjunction with other sources, the treatment plant's effluent to fail a toxicity test;
(16) 
Detergents, surface-active agents, or other substances which may cause excessive foaming in the POTW; or
(17) 
Fats, oils, or greases containing substances which may solidify or become viscous at temperatures between 0° C. (32° F.) and 65° C. (150° F.).
C. 
Grease traps.
[Added 5-6-2002 by Ord. No. 1364]
(1) 
Grease traps shall be provided for kitchen flows at restaurants, nursing homes, schools, hospitals, cafeterias, and other facilities at which quantities of grease can be expected to be discharged into the sewer system. This will apply to all newly constructed establishments, major renovated establishments, existing establishments that are undergoing renovations that require a building permit, or an establishment that has two or more sewer backups.
[Amended 7-1-2002 by Ord. No. 1371]
(2) 
Grease traps shall be installed on a separate building sewer serving kitchen flows into which the grease will be discharged. The discharge from the grease trap must flow to a building sewer prior to discharge into the sanitary sewer.
(3) 
Grease traps shall have a minimum liquid depth of four feet, minimum capacity of 1,500 gallons or 200% of the design kitchen flow, whichever is greater, and sufficient capacity to provide at least a twenty-four-hour detention period for kitchen flow.
(a) 
Multi-compartments are preferred. The first compartment should be 2/3 the total volume.
(b) 
Kitchen flows shall be calculated in accordance with 310 CMR 15.203.
(c) 
If garbage grinders are used for disposal of waste, grease trap volume shall be increased by 25%.
(d) 
The invert elevation of the inlet of the grease trap shall be at least two inches above the invert elevation of the outlet. The inlet and outlet shall be located at the center line of the tank and at least 12 inches above the maximum groundwater elevation.
(e) 
The inlet tee shall extend from approximately three inches below the top of the grease trap to a minimum of 24 inches below the surface of the liquid level or to the midpoint of the liquid level, whichever is lower.
(f) 
The outlet tee shall extend from approximately three inches below the top of the grease trap to 12 inches above the bottom of the grease trap.
(g) 
Tees shall be cast iron or Schedule 40 PVC and properly supported by a hanger, strap, or other device.
(h) 
Grease traps shall be provided with a minimum twenty-inch diameter manhole frame and cover to grade over the inlet and outlet tees. Manholes shall be watertight and constructed of durable material.
(i) 
All piping shall be a minimum of Schedule 20 PVC in areas not subject to automobile or heavy equipment traffic. In areas where such traffic exists or is anticipated, Schedule 40 PVC or equal shall be used.
(4) 
Grease traps shall be watertight and constructed of materials with the following specifications:
(a) 
Grease traps shall be constructed of sound and durable watertight materials not subject to excessive corrosion, decay, frost damage, cracking, or buckling due to settlement or backfilling.
(b) 
Metal grease traps are prohibited. Grease traps shall be constructed of:
[1] 
Poured-in-place concrete.
[2] 
Precast reinforced concrete.
[3] 
Fiberglass.
[4] 
Polyethylene.
(c) 
Grease trap construction materials shall meet the following minimum specifications:
[1] 
Concrete.
[a] 
Concrete strength f'c 4,000 psi at 28 days; density 140 PCF.
[b] 
Cement, Portland Type I or III, per ASTM C150-81.
[c] 
Admixtures per ASTM C233-82.
[d] 
Reinforcing per ASTM A615 for wire fabric, grade 40/60 R'd or equivalent.
[e] 
Design loading H-20.
[f] 
Minimum wall thickness: four inches, three with reinforcing.
[2] 
Synthetic.
[a] 
Ultimate tensile strength: minimum 12,000 psi when tested in accordance with ASTM D 638-89, Standard Method of Test for Tensile Properties of Plastics.
[b] 
Flexural strength: minimum 19,000 psi when tested in accordance with ASTM D 790-86, Standard Method of Test for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials.
[c] 
Flexural modulus of elasticity: minimum 800,000 psi when tested in accordance with ASTM D 790-86, Standard Method of Test for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials.
(d) 
Grease traps shall be watertight through manufacturer's specification and warranty or grease traps shall be made watertight by the manufacturer, equipment supplier, or installer using asphalt or synthetic polymer sealer specified by the concrete or synthetic material manufacturer.
(e) 
Grease traps shall be constructed or set level and true to grade on a level stable base which has been mechanically compacted. If the component is placed in fill, proper compaction is required to ensure stability and to prevent settling; native ground with a six-inch base is otherwise adequate.
(f) 
All system components shall be constructed of corrosion-resistant materials.
(g) 
All pressurized pipes shall be designed and installed to meet the following requirements:
[1] 
To prevent freezing by being installed below the frost line, by being adequately insulated if installed above the frost line, or be self-draining;
[2] 
To specify appropriate class or schedule of pipe to withstand maximum pressure and/or anticipated vehicular loads; and
[3] 
To specify appropriate thrust blocking at all angles, bends, branches, plugs, and wherever else necessary to prevent disruption of proper functioning of the line.
(h) 
The top of the grease trap shall be installed not more than 36 inches below finished grade. Where site restrictions prevent compliance with this provision, written permission from the Department of Public Works must be obtained prior to approval.
(i) 
Where any portion of the grease trap is placed at or below the groundwater table, the grease trap shall be designed with counterweights, anchors, or ballast, and a buoyancy calculation for the entire volume of grease trap, when empty, shall be performed and submitted to the Department of Public Works with plans and specifications of the system.
(5) 
Grease traps shall be installed on a level stable base that has been mechanically compacted and onto which six inches of crushed stone has been placed to minimize uneven settling.
(6) 
Grease traps shall be accessible for inspection and maintenance. No structures shall be constructed directly upon or above the grease trap access locations.
(7) 
Backfill around the grease trap shall be placed in such a manner as to prevent damage to the tank.
(8) 
Grease traps shall be maintained in accordance with the following:
(a) 
Grease traps shall be inspected monthly and shall be cleaned by a licensed septage hauler whenever the level of grease is 25% of the effective depth of the trap or at least every three months, whichever is sooner.
(b) 
A log of inspection and maintenance shall be kept by the owner for review by the Sewer Department.
(9) 
Grease removal by other devices located within the building as part of the internal plumbing are not within the jurisdiction of this chapter and shall not be considered for compliance with this chapter except with prior written approval of the Department of Public Works.
(10) 
If site restrictions exist, a written request for an alternative method(s) of treatment must be submitted to the Director of Public Works for review. No alternatives are acceptable without written approval from the Director of Public Works.
[Added 7-1-2002 by Ord. No. 1371]
(11) 
If an applicant is aggrieved by the decision of the Director of Public Works, a written request for a hearing must be presented to the Board of Health within 10 days. The Board will schedule a hearing for relief at the next available meeting.
[Added 7-1-2002 by Ord. No. 1371]
D. 
Pollutants, substances, or wastewater prohibited by this section shall not be processed or stored in such a manner that it could be discharged to the POTW.
The national categorical pretreatment standards found at 40 CFR Chapter I, Subchapter N, Parts 405 to 471, are hereby incorporated.
A. 
Where a categorical pretreatment standard is expressed only in terms of either the mass or the concentration of a pollutant in wastewater, the Director may impose equivalent concentration or mass limits in accordance with 40 CFR 403.6(c).
B. 
When wastewater subject to a categorical pretreatment standard is mixed prior to treatment with wastewater not regulated by the same standard, the Director shall impose an alternate limit using the combined waste stream formula in 40 CFR 403.6(e).
C. 
A user may obtain a variance from a categorical pretreatment standard if the user can prove to the satisfaction of the Director and the approval authority, pursuant to the procedural and substantive provisions in 40 CFR 403.13, that factors relating to its discharge are fundamentally different from the factors considered by the EPA when developing the categorical pretreatment standard.
D. 
A user may obtain a net gross adjustment to a categorical standard in accordance with 40 CFR 403.15.
The following pollutant limits are established to protect against pass-through and interference. No person shall, unless otherwise approved by the EPA, discharge wastewater containing concentrations in excess of the following:
Parameter
Limit
(mg/l)
Aluminum
11.323
Arsenic
3.084
Cadmium
0.028
Copper
0.300
Cyanide
1.046
Lead
0.020
Mercury
0.002
Nickel
3.278
Silver
0.026
Zinc
0.553
The City reserves the right to establish, by ordinance or in wastewater discharge permits, more stringent standards or requirements on discharges to the POTW.
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 Director may impose mass limitations on users which are using dilution to meet applicable pretreatment standards or requirements or in other cases when the imposition of mass limitations is appropriate.