City of Bonney Lake

The Bonney Lake sewer collection system is primarily a gravity-flow system. That is, sewage goes into a sewer main and flows downhill by the pull of gravity.

Therefore, a sewer main must maintain a downhill grade for gravity flow to occur. The longer the sewer main, the deeper the main must be to maintain a downhill grade. A sewer main can only go so deep before construction and maintenance costs rise dramatically.

At predetermined sewer main depths,  sewer lift stations are installed. The lift stations have pumps that “lift” the wastewater to the next sewer main.  This prevents the sewer main from being installed too deep. The sewer main installed after a lift station is called a force main because it is under pressure from the pumps in the lift station.  This force main may transport wastewater directly to the WWTP, or it may pump to other lift stations.

A lift station has submersible pumps that are designed to operate while submerged beneath the wastewater, which muffles the sound. A lift station typically has multiple pumps installed to handle the varying loads of wastewater that enter the lift station and to also provide redundancy should a pump fail. Once a lift station is constructed, there is rarely an impact to adjacent areas. In fact, after landscaping, most will not know they are there.

Each is designed to connect to a portable generator in the event of an extended power outage. Typically, power outages are not a problem since the pumps only operate as needed. On rare occasions, a sewer vactor truck may be used to pump out wastewater from a lift station if emergency generators are not available.

The City of Bonney Lake currently has 26 lift stations located throughout the sewer service area.

What is a grinder pump?

A grinder pump is a wastewater conveyance device. Waste from water-using household appliances (toilets, bathtubs, washing machines, etc.) flow through the homes pipes into the grinder pump's holding tank. Once the wastewater inside the tank reaches a specific level, the pump will turn on, grind the waste into a slurry, and pump it to the central sewer system. City owned grinder pumps are installed outside and have an audible alarm and an indicator light if the pump malfunctions and should alert the homeowner if there is an issue with the pump. If you experience a problem with a city owned grinder pump, please contact us immediately at 253-447-4319 or 253-862-8602.

How to prevent grinder pump issues.

Homeowners are not usually limited to what they can or cannot pour down their drain because their home has a grinder pump. However, there are companies that claim their products can be flushed down the toilet. These wipes clog household plumbing and cause problems with grinder pumps, lift stations, and sewage treatment plants.  Just remember Wipes Clog Pipes.

What is a FOG Program?

Fats, Oils, and Grease (FOG) come from meats, butters, lard, food scraps, sauces, salad dressings, dairy products and cooking oil. When FOG goes down the drain, it hardens and causes sewer pipes to clog. This can lead to a Sanitary Sewer Overflow (SSO) where raw sewage actually backs up into your home, lawn, neighborhood and streets. Not only does this nasty mess cause health issues, it also can run into a nearby stream or river.

If your pipes become clogged from putting FOG down the drain, it can be a very expensive problem to fix. To avoid household or environmental damage, as well as a costly bill, NEVER put FOG down the drain.

How is the City involved?

The City of Bonney Lake has a FOG ordinance to reduce blockages and maintenance in the sewer system. Any commercial establishment that serves or prepares food, within the city limits, where FOG may be introduced to the sanitary sewer system, shall abide by the Bonney Lake Municipal Code (BLMC) 13.12.320 FOG Prevention Requirements.

In conjunction with the ordinance, the establishments also are urged to implement and maintain best management practices (BMPs), as well as the need to submit and adhere to a FOG control program. The purpose of this program is to reduce SSO's and obstructions caused by FOG entering the sewer system, and also to educate the public and food service establishments on how to reduce FOG to maintain compliance with the ordinance.

Inspections

The City of Bonney Lake conducts inspections of grease interceptors and grease traps on both a scheduled and unscheduled basis to determine whether the requirements set forth are being met. These inspections may happen anytime during business hours. A typical inspection includes:

• If an interceptor is present and in a public area, cone off to ensure employee and public safety.
• Removal of interceptor lids, checking influent and effluent baffles and recording findings. This is done using a Sludge Judge (SJ), a device which measures the amounts of scum (grease), clear layer and sludge (solid) levels.
• This measuring process is completed three times in different locations within the compartment to establish an average.
• To be in compliance with the BLMC 13.12.320, the combination of sludge and scum must be less than 25% of the volume of the last compartment in the interceptor or grease trap.

What can I do as a resident to prevent FOG?

Fats, oil and grease don't belong in your home's plumbing either. These products can cause bigger problems if they get into the City system. FOG gets into sewer pipes from dishwashers, garbage disposals, washing pots and pans and from being poured directly down the sink.

Rinsing fats down the drain with hot water and detergent doesn't really work. The grease just moves a little farther down the pipe where it cools and coats the inside of your plumbing resulting in clogged sinks or blockage of your line to the main.

You can avoid expensive plumbing mistakes by disposing of FOG the proper way:

• Remove fats, oils and grease from dishes and pans by wiping with a paper towel into the garbage before washing with water.
• Let grease and cooking oil cool, then pour into a sealable container and place in the garbage. (Hint:  freezing will make it mostly solid).
• Use the garbage disposal as little as possible.  Instead, place a strainer over the sink drain to catch solids and empty into the trash as needed.
• Avoid flushing wipes, wrappers and other garbage items into toilets.  These products do not dissolve and combine with grease in the sewers to clog pipes.
• If your plans include using a hot oil poultry fryer, the grease needs to be disposed of after cooking. 

Pierce County residents can dispose of used cooking oil, free of charge.  Click here for information.

Occasionally special testing with smoke generating devices are used to locate cross-connections between stormwater and wastewater systems. Dye testing is another method used to evaluate infiltration, inflow and exfiltration and to confirm wastewater flow direction.