The Clyde Hill 465 Reservoir, located in the City of Clyde Hill, is showing signs of aging, corrosion, and deterioration that require repairs to ensure that it can remain in service. Constructed in 1958 and standing at over 100 feet tall, this 0.7 million gallon steel structure supports the City water supply utility system. The Bellevue Utilities Department will empty the water tank temporarily so that the interior can be recoated and make other miscellaneous improvements that can extend the life of the structure.
Why is this project needed?
Each of the major components of the project is designed to protect and enhance the quality of the water coming through the structure.
- Interior coatings – The typical life expectancy for water tank coatings is between 20 and 30 years. The interior on this reservoir was last recoated in 1996, making it due for a replacement of the interior coating. The coating will continue to deteriorate if it’s not replaced, which compromises water quality and is a public health risk.
- Corrosion control – The reservoir does not have provisions for active corrosion control in the form of cathodic protection, which is a current City standard. Installing a new cathodic protection system will help extend the life of the interior coating.
- Vent repairs – A recent survey of the vents found gaps around the screens, no hood over the screens, and some screen holes that were plugged with paint. Each one of these poses a risk to water quality. Repairing the vents to the highest standards will keep this water safe for the community.
Anticipated project impacts
- A generator will be needed 24 hours a day during construction. The contractor will follow the Clyde Hill noise ordinances to ensure the noise does not exceed approved levels.
- Once construction begins, construction vehicles may be seen in the area throughout the day during approved working hours. Roads will not be blocked or closed.
- Trail access may be blocked during some portions of construction during approved working hours.
Timeline
- Sept. 2023 - Design and Permitting
- Sept. 2023 - Bid advertisement
- Nov. 2023 - May 2024 - Project construction