The City of Redmond Wastewater Maintenance Division maintains and operates the wastewater (sewer) system to meet the needs of existing and future customers. The wastewater system serves a residential population of 69,900 (2020) within the City limits and approximately 3,500 residential households in the Novelty Hill area.
City staff maintain the wastewater system in a manner that protects the public investment, protects the environment and human health, ensures compliance with state and federal mandates, and ensures that reliable service is available to all customers of the City utility system.
Wastewater staff provide information to commercial customers and residents about the treatment and reduction of grease and industrial discharges to the wastewater system to ensure compliance with pre-treatment standards. Wastewater Division staff also collaborate with Utility Engineering staff on long-range system development and comprehensive planning, the capital facility program, and feasibility studies.
What: Replace or rehabilitate ten wastewater lift stations in six years. At the start of the program, the Sewer Utility owned and operated 23 lift stations throughout its service area (see map for locations; stations identified for replacement are numbered). With the completion of the Lift Station 14 abandonment project, there are now 22 wastewater lift stations.
Why: If a lift station fails there is a risk that raw sewage will back up into homes or businesses, or overflow into Lake Sammamish and other natural waterways. Ten wastewater lift stations are at, or past, their useful life. Mechanical and electrical equipment in lift stations usually lasts 20-30 years. Some of the lift stations are over 30 years old, some are failing now, and some have equipment for which replacement parts are no longer available.
How: The sewer lift stations will be replaced using sewer rates, development connection charges, and bonded debt so that the stations are in good working order by 2025.
Progress: In 2019, Lift Station 2 was replaced and Lift Station 14 was abandoned and a new sewer line installed. Lift Station 3 was replaced in 2020 and work on Lift Station 13 started.
The Wastewater Division is responsible for maintenance and repair of over 230 miles of pipe ranging from 8 to 36 inches in diameter, 15 miles of easements, 7,336 manholes, and 22 pump stations.
Maintenance activities include but are not limited to:
- Closed-circuit television (CCTV) inspection
- High-pressure hydro-cleaning
- Easement and pump station maintenance
- Daily monitoring of the SCADA (Supervisory Control and Data Acquisition) system
- Activities related to providing excellent customer service
Wastewater Division staff repair lift stations, pipe, and manholes. Lift station repair involves complex electrical circuits, pumps, and equipment. Manhole repairs range from frame and cover replacement to entire channel and bench restoration. Pipeline repairs range from open trench pipe replacement to slip lining damaged sections of pipe.
You may be surprised to know that, in many ways, the City of Redmond Wastewater Maintenance Division is a front-runner when it comes to the use of existing and emerging technologies. On a daily basis, Wastewater staff use a wide variety of hardware and software to efficiently operate and maintain City infrastructure. Listed below are just a few of those technologies.
SCADA is an acronym which stands for Supervisory Control and Data Acquisition. Quickly defined, SCADA is a computerized system which monitors (and in some applications, controls) infrastructure.
Redmond's Wastewater Division makes use of this technology to monitor 22 lift stations remotely. One advantage of using a SCADA system is the transfer of information to and from various sources is near instantaneous. This allows staff to monitor lift stations in real time and, with the knowledge delivered by SCADA, operators can make quick decisions in a number of circumstances.
With data constantly being digitally recorded, it also provides staff an opportunity to look at trends from a historical perspective. This information becomes an invaluable asset when planning preventative maintenance and corrective actions.
GIS is an acronym which stands for Geographic Information System. GIS is a system which integrates hardware, software, and data for capturing, displaying, managing, and analyzing all forms of geographically-referenced information.
The City of Redmond GIS allows Wastewater Division staff to visualize, question, interpret, and understand data, allowing us to efficiently plan for growth while continuing to maintain our existing infrastructure.
GraniteNet software allows city staff to complete digital video inspections of underground wastewater pipe through the use of a computer on the Wastewater Division’s Closed Circuit Television (CCTV) truck. These inspections allow staff to determine what maintenance procedures are necessary for each segment of the wastewater pipe.
What is a lift station?
Due to hills and valleys in the landscape, sewer systems include locations where sewage needs to be pumped from low points to higher elevations, from which it will ultimately flow via gravity to a King County treatment plant. Once sewage arrives at the treatment plant it is treated and discharged to Puget Sound.