Our Tunnel Hill tanks rehabilitation project has saved the residents and businesses we serve $6.3 million and is earning accolades from professional engineers throughout the San Diego region. On Thursday, the San Diego section of the Structural Engineers Association of California will honor Helix with a Material Project of the Year Award.
This will be the third engineering award for the project. On May 11, the San Diego & Imperial Counties Chapter of the American Public Works Association recognized the project with an Honor Award.
On June 16, the San Diego section of the American Society of Civil Engineers selected the project for their Outstanding Seismic Retrofit Project Award.
Why did these two tanks, located in the Winter Gardens area of Lakeside, attract this much attention? Because rehabilitating the tanks, rather than replacing them, reduced the cost of this project by 60%.
If you’ve renovated a home, added rooms or a second story, then you know that it can be more challenging to renovate than to build brand new. The issues hidden away in the walls of an old house can bring delays and increase costs. This is less of a concern for Helix engineers because we continuously inspect and maintain our 25 water storage tanks, located on hilltops throughout our 50-square-mile service area.
Our engineers have a few of these tank rehabilitations under their belt – five to be exact and one more that will happen within the next 10 years. We choose to rehabilitate, rather than replace tanks whenever it is the more cost-effective option.
The large tank at our Tunnel Hills site was built in 1956 and holds two million gallons of water. We upgraded the tank in 1994 to meet new seismic standards and recoated the interior in 1996 and exterior in 2006.
New building and seismic standards also prompted this upgrade. To comply with the new standards, we added 5 feet of height to the large tank and replumbed both tanks with flexible fittings to prevent breaks and keep the tanks connected during an earthquake. Additional improvements added another 50 to 60 years to the useful life of both tanks:
We installed a new aluminum roof on the large tank that will minimize overall corrosion and reduce long-term maintenance costs.
We stripped the exterior of the smaller, reinforced concrete tank. The new, natural concrete finish does not require paint and will reduce long-term maintenance costs.
We recoated the interior of both tanks and the exterior of the large tank.
“This is how we do it,” said Helix Board President Kathleen Hedberg. “Every tank, pump and valve is on a cycle: first, we do decades of maintenance to extend the useful life of each asset, then our engineers replace the asset or rehabilitate it. This is how we ensure reliable water service.”