What can a Tempe business not put down the sewer? City Code 27-10

Subsection (a) bars any pollutant or wastewater that causes "pass through or interference" at the treatment system. It applies whether or not a categorical federal standard covers the user. Subsection (b) lists specific prohibitions. The ones a building owner is most likely to meet:

• Grease, wipes and rags. (b)(3), the quote above. The test is amount and size: enough to obstruct flow.
• Water that is too hot. (b)(5) bars wastewater above 150 degrees Fahrenheit (66 degrees Celsius), or heat that inhibits biological activity at the plant, and in no case wastewater that makes the temperature at the plant's introduction point exceed 104 degrees Fahrenheit (40 degrees Celsius).
• Water that is too acidic or too alkaline. (b)(2) bars pH below 5.0 or above 10.5, or anything causing corrosive structural damage.
• Fire and explosion hazards. (b)(1) and (b)(18), including a flashpoint under 140 degrees Fahrenheit.
• Petroleum and mineral oil. (b)(6), in amounts that may cause interference or pass through or form persistent oil emulsions.
• Foaming agents. (b)(16), detergents or surface-active agents that may cause excessive foaming.
• Hauled loads. (b)(8), trucked or hauled pollutants except at discharge points the Public Works Director designates.
• Clean water that is not waste. (b)(12) lists storm water, surface water, ground water, roof runoff, subsurface drainage, "condensate, deionized water, noncontact cooling water, and unpolluted wastewater," unless the Public Works Director specifically authorizes it.
• Residues from cleaning. (b)(13) and (b)(14) bar sludges, screenings and other residues from pretreatment of industrial wastes, and "sludges, screenings, debris, silt or other nonliquid residues from the cleaning of the sanitary sewer collection system."

Subsection (c) adds the permit rule: "Direct or indirect discharge from a nondomestic source to the City's sanitary sewer system is prohibited without a permit issued by the Public Works Department." Section 27-32 explains how Tempe's wastewater discharge permits and notices of intent work; see that page.

• POTW. The publicly owned treatment works, which 27-4 says includes systems that collect and convey wastewater to the treatment plant.
• Nondomestic source. Section 27-4 defines it as discharges "of any substances other than human excrement and household gray water derived from the ordinary living process of residential family homes." A restaurant, shop or office floor drain is therefore a nondomestic source. That is how the code reads, not a separate Tempe label for businesses.
• FOG. Section 27-4 defines it as any substance, "including but not limited to vegetable or animal product," used in or a byproduct of cooking, food preparation or cleaning that can cause corrosion, blockages, reduced flow or interference.
• Interference and pass through. Defined in 27-4 by their effect on the treatment system and its permits.

Every person discharging to Tempe's sewer system, and the strongest effect is on nondomestic sources. It does not turn on being a restaurant: a mechanic's floor drain, a salon and an office are under the same text.

It does not cover discharge somewhere else. Tempe's list governs Tempe's sewer. A property served by a different city's sewer follows that city's code, which can differ, as the comparison above shows.

A taqueria with a clogged lateral. The line backs up at a floor drain. The cause is grease and wipes from kitchen cleaning. Under (b)(3) the owner is on the wrong side of the rule once the amount obstructs flow, even if each wipe was a small thing.

A shop adds a split system. The condensate line is tied into the sanitary drain. Section 27-10(b)(12) lists condensate and says it is barred unless the Public Works Director specifically authorizes it. The code does not define "condensate" there, so a reading is that it includes equipment condensate. Mesa's wording is narrower (condensate that may constitute inflow), which is why one city's plan review answer cannot be pasted onto another.

A plumber jets a restaurant lateral. Jetting loosens grease and solids. Item (b)(14) bars residues from cleaning "the sanitary sewer collection system." The code does not say whether a private building sewer counts as part of that system, so a cautious reading is to pull the debris out rather than flush it toward the main.

The edge case: 150 degrees. A dish machine drain reads 155 degrees Fahrenheit and the owner assumes the plant will absorb it. The text in (b)(5) is "Wastewater having a temperature greater than 150°F (66°C)," so the number on the wastewater is the test.

1. 1Walk the drains: kitchen, mop sink, floor drains, equipment drains, restroom. Note anything that is not water, human waste or domestic gray water.
2. 2Pull the grease and food solids out dry before cleaning, and keep wipes and rags in the trash.
3. 3Check discharge temperatures on dish and equipment drains against the 150 degree limit.
4. 4Ask Public Works in writing before piping condensate, deionized water or cooling water to the sanitary sewer, since (b)(12) turns on specific authorization.
5. 5Read 27-22 for the grease trap or interceptor Tempe requires of a food service user.
6. 6Tempe's Environmental Services section takes inspection questions at 480-350-2678, a number printed on the city's backflow program page.

• Treating wipes as safe because the label says flushable. Section 27-10 names wipes and rags directly and the test is obstruction, not the label.
• Assuming only restaurants are covered. The definition of nondomestic source reaches any discharge other than human excrement and household gray water from residential family homes.
• Using one city's temperature limit everywhere. Tempe and Mesa say 150 degrees Fahrenheit. Avondale says 140.
• Treating condensate as harmless. The list places it under water that is barred unless authorized.

The city's code text governs; this page explains it.