Project Profile: The Perfect Pair: Two Glass-Fused-To-Steel Tanks Ease the Pressure on Small-Town Growth

With a bustling population nearing 10,000, the small but fast-growing community of Rapid Valley, SD, has become an attractive alternative to bigger city living. Its low crime rate, affordable land, and impressive views of the Black Hills create the perfect backdrop for the steadily increasing collection of homes and businesses being built there.

Rapid Valley’s need for an abundant source of safe water to ensure its long-term growth and vitality has been clear from the start. Established in 1966, Rapid Valley Sanitary District (RVSD) was formed to provide water and sewer service to the small rural community developing approximately 10 miles east of Rapid City. For many years, RVSD purchased water from the City of Rapid City. Later, it became more self-sufficient in the production of water.

Glass-Fused-to-Steel Seals the Deal
Part of the move toward self-sufficiency was the construction of a 166,000-gallon steel water tank in the 1960s. In 2000, after decades of growth, RVSD installed another tank, a 256,000-gallon Aquastore glass-fused-to-steel tank from Engineering America.

That tank, due to its low-maintenance, high durability porcelain enamel (glass-fused-to-steel) coating, has performed so well over the past 14 years that it became the obvious choice when it was time to replace the aging 1960s tank in 2014.

“We needed to accommodate the area’s growth and have enough water in storage for emergency and fire protection,” says Rusty Schmidt, RVSD general manager. “Our older epoxy coated tank was experiencing structural issues and corrosion problems. Our newer Aquastore tank was showing no signs of wear on its exterior or interior coating even at 14 years old. So we decided to install a second tank just like it.”

Ted Schulz, operations manager at AE2S, the engineering firm that designed the tank, concurred, saying, “The need for additional storage was apparent as the district grew. The installation of the second Aquastore tank was part of a two-prong approach to provide more storage and replace the older tank, which was failing due to corrosion of the painted steel exterior and notable ice damage inside the tank. Several leaks had been patched over the last few years, and the steel walls were very damaged due to ice problems. We wanted to get it resolved before the area’s summer peak season.”

Cost-Effective Alternative to Epoxy Coatings
The new glass-fused-to-steel tank is 36 feet tall and 33 feet in diameter. The 257,869-gallon tank was built on a hill next to the other Aquastore tank and is exposed to the elements. The wind is quite strong at times so the district needed a tank that wouldn’t be susceptible to damage from blowing debris.

The factory-applied silica glass coating on Aquastore tanks forms a hard, inert barrier for both the interior and exterior tank surfaces guarding against weather conditions and corrosion. Glass fused to steel is impermeable to liquids and vapors, and controls undercutting caused by corrosion, which offers excellent impact and abrasion resistance.

“We did a cost comparison between a welded-and-painted tank and the Aquastore glass-fused-to-steel tank,” says Schmidt. “It was soon evident that the Aquastore tank provided a long-term value that exceeded any epoxy tank. You can recoup your initial capital costs quickly just saving maintenance costs.”

Schmidt added that epoxy coatings are expensive, time-consuming to paint and probably need repainting every 15 years over a 75-year lifespan, but remarked that in contrast, the ­Aquastore tank provides a solid, virtually ­maintenance-free exterior that doesn’t ever need to be repainted. “Unlike an epoxy coating, the Aquastore glass-fused-to-steel coating is inert and stable, does not sacrifice itself, fade, chalk, or degrade—a bonus when your water tanks are part of the landscape in such a picturesque location.”

Accommodating a Varied Terrain
Another element that featured prominently in RVSD’s decision to go with the Aquastore tank was the district’s terrain.

“The drain in this part of the valley is through undulating hills,” says Schulz. “The tank is at the top of the hill providing service and pressure to several hundred homes. The area around it now is pasture, but the community is growing quickly. Each year, 20 to 40 houses are added that will need to be served by the district. This storage tank is located in the high-pressure zone and includes a booster station that pumps to this level.”

Schmidt elaborates: “Many systems have multiple pressure zones depending on the terrain and different tank elevations. When systems expand and grow, you may need to build booster stations to pump water to the higher elevations. This can go the other direction as well. If the system expands to lower elevations, you may need pressure-reducing valves to reduce the water pressure as it goes to these lower developments. The new tanks were built at a high elevation to accommodate the area’s continuing development and need for storage, emergency, and fire flow capacity to the higher zone. With them, we can optimize our booster stations operational run times more efficiently.”

“Quality on Tap!”
The choice to work with Engineering America again was an easy one, says Schmidt.

“The slogan on our water tanks is ‘Quality on Tap!’ It means our rural water system strives to produce potable drinking water that meets or exceeds all South Dakota Department of Energy and Natural Resource requirements. It also means that quality is super important to us.”

“Engineering America has been around for 35 years and the crews are great to work with. The community is very pleased, and our board members all find it to be a well-done project. Plus, the tanks are matching now. They look great, and that’s important too because they can be seen from miles around,” he says.