Materials Safe for Sewer

What Can Be Sewered?

Waste disposal would be greatly simplified if all liquid waste could be poured down the drain. However, common sense tells us that some things shouldn't end up in Green Bay. What can or cannot be poured down the drain is regulated by the Green Bay Metropolitan Sewerage District. The METRO Sewerage System must comply with the Clean Water Act and other State and Federal Regulations which limit discharge. Regulations concerning sewer use are found in the Green Bay Metro Sewer Use Ordinance, adopted May, 1993. The material below covers the main points of the ordinance which may apply to campus employees. If you want a copy of the complete ordinance please contact Scott Piontek, ext. 2273.

It is easier to describe what should not be disposed of via the sanitary sewer rather than what is allowed. It is important that a distinction is made between a sanitary sewer and a storm sewer. Storm sewer run-off typically goes directly into the river/bay, therefore it is very important that liquids are not disposed of via a storm sewer. Sanitary sewerage is pre-treated before being discharged into the river/bay. The most current Sewer Use Ordinance specifically prohibits the following from being disposed of via a sanitary sewer:

1. Very hot (> 150o F) or very cold ( < 32o F) liquids. Generally benchtop quantities of very hot or very cold liquids used in academic laboratories can be poured down the drain since all campus liquids wastes are mixed together and liquid temperatures will moderate before leaving the campus.
2. Waste which creates a fire hazard (flash point < 140 oF) - check the MSDS or label for this information. Flammable solids and gases should also be excluded from sewerage.
3. Volatile substances such as gasoline, kerosene, naptha, benzene, toluene, xylene, ethers, alcohols, ketones, aldehydes and peroxides. Benzene concentrations shall not exceed 0.5 mg/L.
4. Solid or viscous material which is likely to cause obstruction to sewer flow e.g. mud, straw, plastics, wax, wood, animal guts
5. Liquids with a pH < 5 or > 9. Campus personnel can neutralize acids and bases and then pour down the drain. See comments below on neutralization.
6. Radioactive wastes which do not comply with the National Pollutant Discharge Elimination System
7. Petroleum oil, nonbiodegradable cutting oil, or products of mineral origin
8. Strongly colored solutions
9. Certain heavy metals as listed below with restrictions on concentration and quantity. If both concentration and quantity amounts are exceeded, liquid waste cannot be sewered:

Take special note of the low concentration limits for arsenic, lead and mercury and the fact that the concentration of the metal in solution is the only criteria for mercury disposal.

Academic institutions tend to discharge small quantities of a variety of substances as opposed to the industrial discharge of large quantities of a limited number of substances. It is possible that small quantities of one of the above prohibited items may be safely sewered. However, before you do this, contact the UWGB University Safety Manager, Scott Piontek, ext. 2273, who will seek permission from the METRO Sewerage District.

If you accidentally discharge one of the prohibited substances in a sanitary sewer, the campus must notify the METRO Sewerage District. Please contact Scott Piontek, ext. 2273, if this occurs.

Material Which May Be Safely Sewered

1. alcohols (methyl-, ethyl-, propyl-, isopropyl-, "reagent" alcohol) acetone, and glycerine - If the concentration is less than 24% alcohol by volume benchtop quantities may be flushed down the drain of a chemical sink with 20 volumes of water. However, it is not allowable to dilute alcohol for the purpose of rendering it non-hazardous.
2. dilute, < 20%, aqueous solutions of potassium chlorate or sodium chlorate
3. dilute, < 20%, aqueous solutions of the following chemicals