Sewage spills (sanitary sewer overflows) are caused by the clogged of pipes and/or too much flow. Clogged pipes are caused by blockages from fats, oils and grease as well as rubbish, roots and other foreign or unwanted objects in the sewer system. Too much flow is caused by infiltration and inflow i.e., groundwater and rainwater getting into the sewer system). The following sections discuss each cause in detail.
Keeping fats, oils and grease out of the sewer system
Fats, oils, and grease, and other byproducts of cooking come from meat, lard, shortening, butter, margarine, food scraps, sauces, and dairy products. They present a significant clogging problem for sewer systems. Fats, oils and grease stick to the inner walls of sewer pipes and reduce the diameter of the pipes over time. This eventually causes clogged sewer pipes and sewage spills.
Clogging is further caused by chunks of grease breaking away from the pipe walls and becoming stuck further down the line. Grease balls that form when grease combines with sand, grit, and other sewage debris can even become large and hard enough to clog sewage pumps!
Fats, oils and grease also flow down to the wastewater treatment plant where it disrupts operations and increases maintenance costs.
Regulations require restaurants and other commercial food handling facilities to install large grease separation devices to protect sewers from grease problems.
How should we properly dispose of grease and oils?
Everyone can do their share to prevent clogged sewers by following these simple do’s and don’ts
Collect oil and grease in a container filled with absorbent material (shredded newspaper, napkins, paper towels, rags, etc.) and properly dispose of it in the garbage.
Scrape grease and food scraps off cooking/serving utensils and plates into the garbage. Better yet, wipe them with used napkins and paper towels before washing.
Encourage friends and neighbors to practice similar habits of proper oil and grease disposal.
Do not pour grease or oil down the drain or toilet.
Do not dump greasy or oily food waste into the drain. (Minimize the use of your garbage disposal and better yet, compost your vegetable scraps!)
Some other points to remember:
Be sure to put your oil and grease in a suitable container or bag with absorbent material. The reason for using the absorbent material is so that your grease and oils do not leak out of garbage trucks and cause a big mess. Also, remember that solid grease can turn to liquid during the hot summer months so use absorbent material for solid or semi-solid fats too.
If you have a large amount of cooking oil, consider using a disposable automotive oil change box filled with absorbent material. For even larger quantities (several gallons or more), take your used cooking oil to a recycler or cal Environmental Utilities Solid Waste Division for information on disposal and pick up.
Keeping rubbish out of the sewer system
Your toilet and sewer system are only designed to dispose of human wastes and toilet paper (which quickly breaks down). Unfortunately, people use the toilet as a wastebasket out of convenience. It is a huge "out of sight, out of mind" problem because people often don't see the mess sewer overflows cause and the problems that sewer workers need to deal with.
Almost any type of rubbish may restrict sewage flow, clog sewers, and cause sewage overflows. Keep the following from going down your toilet and sinks:
Paper (paper towels, facial tissue (Kleenex), paper napkins, wrappers, etc.). Only toilet tissue is okay.
Food scraps (greasy items are the worst but minimize throwing down non-greasy items too. Try to even keep out smaller food items such as tea-leaves, coffee grounds or eggshells. Garbage grinders help but its even better not to use it where possible -- compost what you can and throw the rest in the trash. Place food scraps in tightly sealed bags or other containers so it does not become an odor or rodent problem.)
Toys, cans, sticks, pebbles and sand, and pretty much all other solids except for human wastes and toilet tissue.
Why is it a problem?
Rubbish and other objects often combine with hair, grease and other debris to cause clogging of the sewer system. Even something as small as a cotton tip swab with other attached debris can cause a blockage in sewer pipes. Rags and stringy material can clog sewage pumps. Malfunctioning sewage pumps, like clogged pipes, prevent sewage from flowing through the system and are a cause of spills. Any rubbish-type items that you dump in toilets and sinks at home, work, schools, shopping centers, movie theaters, or parks can contribute to sewage spills.
Do your share to keep rubbish from clogging our sewers by following these simple Do's and Don'ts.
Place and use a wastebasket in the bathroom to dispose of rubbish (including disposable diapers and personal hygiene products).
Use sink and shower drain strainers.
Scrape food scraps into sealed containers or bags and throw them out in the garbage.
Educate each other on minimizing disposal of rubbish to our sewers.
Don't use the sewer as a convenient means to dispose of food scraps or Pharmaceuticals.
Don't use the toilet as a wastebasket. What should you do if you see a sewage spill? Make sure that people are kept away from the area of the overflow, typically a manhole cover. This is especially important for children and pets that may play near the overflow area (e.g. street, Public Park, or local stream).
If liquid is coming out of a manhole cover with "Sanitary Sewer" on it, it is probably sewage. Note that sewage is not brown or yellowish in color but actually looks like dirty gray dishwater. Especially during heavy rain, take note of and report any sewer manhole covers that you see lifting up and spilling sewage.
Report the sewer overflow immediately to the City Of Roseville, Sewer Maintenance Division at the following numbers:
Sewer Maintenance Division
Quick action is required to reduce the risk of public exposure to raw sewage by stopping the overflow, monitoring its impact, and ensuring proper cleanup.