Operations & Maintenance
Starting October 23, 2017, Ronald Wastewater District began contracting with the City of Shoreline to provide wastewater services under the terms of a wastewater utility operating services agreement. The District's primary function is to maintain, repair and replace as needed the wastewater collection system within its service area which includes the City of Shoreline and the Point Wells portion of unincorporated Snohomish County. The District maintains approximately 190 miles of pipeline, 17 pump stations, 22 grinder pumps, and approximately 16,352 side sewer connections for a population of 53,000 residents. To ensure a constant efficient flow of wastewater throughout our collection system, our crews use special equipment and vehicles to clean, repair, and inspect our sewer lines. They clean and inspect an average of about 75 miles of pipeline each year.
Every year, Ronald plans to clean 264,000 feet (or 50 miles) of our nearly 190 miles of sewer mains. This scheduled cleaning reflects about 50 miles per year or about 4 miles of pipe per month! In this photograph, you are seeing 2 crew members setting up the jet nozzle, which is attached to the hose reel. The hose reel end is connected to a 975 gallon tank at the rear of the Vactor truck.
The jet nozzle and hose are lowered into a manhole and launched in the upstream direction (against the flow). Water pressure of about 1,000 to 1,500 psi will pull the hose up the line to the next manhole. The water pressure is then steadied to about 1,200 psi and the nozzle and hose are slowly (5 feet per second) pulled back, scouring the inside of the sewer main as it returns to the downstream manhole.
This high pressure scouring removes debris such as grit, gravel, most grease, some tree roots, or objects that have made it into the system inappropriately (from resident’s houses) such as things small children flush down the toilet! These objects frequently cause sewer backups.
Every year, Ronald schedules about 78,000 feet of closed-circuit television (CCTV) inspections of our sewer mains. This represents about 15 miles of pipe inspection per year or about 1.2 miles per months. In this photograph, you are seeing the inside of the camera truck. The camera unit has interchangeable wheels for different types of sewer main pipe (concrete, PVC, ductile iron or HDPE). The camera itself is at the front of the unit and can swivel in all directions so our crew can see different views of the pipe. Our crews are looking for pipe deficiencies, such as leaks, low spots in the line, FOG and/or tree roots. The also record where these deficiencies are located so follow up work can be scheduled. We also note where connections are made to the sewer main.
The camera is connected to a steel cable which has copper control wires embedded internally within the cable. The cable is 1,000 feet long and is connected to a winch unit inside of the TV truck (see photograph). The camera unit is launched in the downstream direction (going with the flow of water), which is opposite the direction of pipeline cleaning. The camera goes with the flow of water to prevent splashing on the lense, which makes viewing and recording of this work nearly impossible.
Unlike the pipeline cleaning where we clean from manhole to manhole, we can TV lines until the cable runs out. As line are viewed and recorded, we document the footages where connections are made to our customers buildings, where problem areas are located, or where more frequent inspections, cleaning and/or repairs may be needed as a result of the problem area.
Fat, Oil and Grease (FOG) is the most challenging problem our crews deal with on a daily basis. Annually, we inspect about 400 different sites for FOG. FOG is a result of these items being poured down the drains of homes, apartments, businesses and/or restaurants - while they are hot liquids - and then slowly hardening against the inside of the sewer pipes. For new structures or when we know of remodel work occurring that will include a high-likelihood of FOG, Ronald requires the installation of grease traps. Grease traps can be installed inside of a structure when flows of water are lower, or outside when water flows are higher. The grease trap in this photograph serves a deli and kitchen. An outside grease trap is a large underground concrete vault where the liquid enter and goes through separate chambers to cool and solidify. The grease stays on top of the water because grease is lighter than water, and the water slowly drains away beneath the layer of grease.
In this photograph, our staff is performing a sight glass test and a visual inspection of the chambers of the trap to ensure the draining water does not contain FOG. In this test, a clear plastic tube is lowered into the vault in the last, downstream chamber (where there should be no FOG) and a sample of the water is viewed to ensure the absence of FOG. If FOG is detected in this last chamber, our staff will contact the property owner and inform them of the problem and to require maintenance of the vault.
Annually, Ronald inspects 3,000 of the nearly 4,800 manholes in our sanitary sewer system. In a normal month, we inspect about 250 manholes. We look at the frame and cover to ensure there are no deficiencies and to check for the fit of the cover within the frame (we don’t want them to rattle when a vehicle drives across them) and to ensure they are flush with the road or surface where they are located.
Below the manhole frame is the barrel of the manhole. This concrete cylinder is visually inspected for cracks, leaks, root intrusion or water that may be leaking into the structure. The manhole channel is where the sewer flows. The channel gets inspected for debris or deficiencies. Water entering into our system in any manner other than the pipes inside of our houses or businesses is called Inflow and Infiltration.
Ronald owns, operates and maintains 16 lift stations in our sanitary sewer system and performs 780 inspections per year or about 65 per month. We inspect the lift stations every week. Lift stations are needed to collect the gravity sewer flows in areas where there are low spots. The low spots or areas can have as few as 10 residences or as many as hundreds. The lift station in this photo is in Richmond Beach and was significantly upgraded in 2018. Elevators take our staff below ground about 30 feet to the wet well and dry well (the dry well contains the pumps which lift the sewer to a higher elevation).
Sewer flows are collected in a lift stations wet well. When the water level reached a certain point inside the wet well, a pump automatically turns on and pumps (or “lifts”) the sewer to a higher elevation in our system where it can the flow via gravity to its ultimate destination – the sewer treatment plant.
Where your sewer flows
Sewer flow info coming soon.