Although no system can guarantee 100% effectiveness against a large wildfire, maintaining water tanks and rehabilitating them when needed is vital to ensure they are ready in an emergency.

There are few direct water sources in the San Diego region. Other than rainfall and saltwater desalination, water must be imported. Regional water districts store water for daily use and irrigation for their customers. They also store water in reservoirs and tanks to aid in emergency outages and fire protection.

The Vallecitos Water District (District) recently completed the rehabilitation of its Coronado Hills Tank in San Marcos. Originally constructed in 1984, the 40-year-old tank showed signs of age and wear.

Time and Weather Affect Tank Aging Process

Mike Preston, a construction inspector for the district, explained why the tank needed the upgrade. “Like everything else, they get old. The interior steel structure and coating start to deteriorate over time, as well as the exterior coatings from the weather,” explained Preston.

Before any tank is taken out of service to be upgraded, a diver enters the tank with an underwater camera to conduct a visual inspection and assess the interior steel structure. Exterior visual inspections complete the assessment.

A specialized contractor undertakes the rehabilitation process, sandblasting both the interior and exterior surfaces of the tank to bare steel. This allows a thorough structural inspection of the steel tank. Structural integrity improvements were made to rafters, beams, and stands.

The District also upgrades technology and updates safety standards. The Coronado Tank’s access portals were made larger to allow safer access for annual cleaning, and a new climbing system provides access for water quality testing.

Get a behind-the-scenes look at the project in this video.

 

Coronado Hills Tank Gets a New Look

When repairs were completed, the tank received a new interior coating specially approved for drinking water and new exterior surface epoxy coatings to safely extend its lifespan. Traditionally, water tanks have been painted dark green to blend in with their natural surroundings.

However, the dark color creates warmer water temperatures inside the tank, which makes it more difficult to maintain water quality standards.

As part of the rehabilitation project, the tank’s color was changed to beige to improve its light-reflectance value (LRV) from 11% when painted dark green to 67%. This means the tank surface now reflects 67% of the light hitting it rather than absorbing it.

Preston says the district is looking into changing the color of its other tanks, pending further monitoring to determine the long-term benefits.

“I already have had confirmation from one of our operators that when they were out sampling tanks. Already they’ve noticed a temperature change at this particular tank, which is a good sign. But only time is going to tell, over time, the main effect and how it’s really going to help us,” said Preston.

Water Tanks Play Vital Role in Fire Protection

Water tanks are placed on hills at elevation above populated areas to reduce pumping costs and ensure adequate water pressure for firefighters in the event of wildfire.

“Our Vallecitos Water District rehabilitations are necessary to provide constant, safe, potable drinking water for our customers, as well as a reliable source of fire protection by keeping these tanks in service for a very long time to come,” said Preston.

Preston says he’s thankful the Vallecitos Water District makes time to listen to employee input with suggestions on ways to improve district operations, “not only for just our customers, but also our employees as well.”