Tapping a Reliable Water Supply in Drought-Stricken Southwest

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(Free-Press-Release.com) August 19, 2011 -- It was during a period of severe drought in 2001 that the city and county of Santa Fe initiated planning of the $216 million Buckman Direct Diversion (BDD) Project, which was designed to provide a reliable, sustainable water supply for the 100,000 city and county water customers. Prior to construction of the BDD, the city and county had relied on groundwater wells and underground aquifers for its water supply. Studies had determined that groundwater sources were not being replenished due to over pumping.

The BDD includes a sediment removal facility to return sand to the Rio Grande River, 11 miles of buried raw water pipeline 20 to 30 inches in diameter to carry the water to a lifting station with booster pumps to move the water uphill, a treatment plant with capacity to filter 15 million gallons of water per day, and two new booster stations to deliver treated water to customers. “It is one of the largest, most complex non-federal infrastructure projects ever built in Santa Fe County,” according to CH2M HILL, which teamed with Western Summit Constructors on the design-build joint venture.

The Buckman Regional Water Treatment Plant (BRWTP), which was designed in the New Mexico Territorial style of architecture with its flat-roof profile, uses both conventional and advanced water treatment processes. The BDD website explained, “The conventional processes remove the vast majority of contaminants. The advanced processes provide additional treatment and polishing of the finished drinking water. Conventional treatment processes include coagulation, flocculation, sedimentation and disinfection. Raw water ozonation improves the effectiveness of conventional treatment. Advanced treatment is provided by membrane filters, ozone and granular activated carbon contactors. Disinfection is accomplished with lower amounts of chlorine because the high-quality water does not need as much chlorine.”

Fiberglass-reinforced lining systems from Tnemec were specified for two secondary containment areas for bulk storage tanks used to hold chemicals necessary to treat the water, according to Tnemec coating consultant Lane Salvato of The Barry Group, LLC. “Due to the severity of the service conditions, the engineer on the project required detailed case histories and performance criteria for all of the coating products proposed for concrete secondary containment,” Salvato explained. “Tnemec provided case histories from across the country, as well as extensive performance testing. Each of these projects specified Series 239SC ChemBloc, a highly chemical-resistant, fiberglass mat reinforced mortar novolac epoxy lining formulated for use in secondary containment systems.”

On one secondary containment system for bulk tanks containing high concentrations of sulfuric acid, sodium hydroxide, ferric chloride, sodium hypochlorite, zinc orthophosphate, hydrofluorosilicic acid, and calcium thiosulfate, Series 239SC ChemBloc was applied as a mortar over Series 201 Epoxoprime, a two-component polyamine epoxy primer. While the basecoat was still wet, a fiberglass mat was laid into the surface and saturated with additional coating until the mat was wet out and translucent. A topcoat of Series 282 Tneme-Glaze, a chemical- and solvent-resistant glaze coating, was applied to provide the concrete for additional chemical protection.

A second containment system with lower chemical concentrations specified a prime coat of Series 201 and a topcoat of Series 436 Perma-Shield FR, a fiber-reinforced, 100 percent solids modified polyamine epoxy. This lining system is resistant to sodium hypochlorite, sulfuric acid, and sodium hydroxide. Both secondary containment lining systems were installed by Brogan Brothers Painting of Albuquerque.

Tnemec coatings were also used on two aboveground water storage tanks fabricated by D&R Tank Inc., which was looking for long-term corrosion protection on interior steel and ultraviolet (UV) protection for exterior steel. Both interior and exterior steel on the 350,000-gallon and 250,000-gallon tanks were primed with Series 91 H2O Hydro-Zinc, a zinc-rich urethane that provides outstanding long-term corrosion resistance. “D&R has standardized Series 91-H20 as their shop primer,” Salvato noted. “They use Hydro-Zinc because it allows for faster shop throughput and less touch-up in the field. D&R does not have to sweep blast the entire plate in the field with abrasive media.”

Interior steel received two spray-applied coats of Series N140 Pota-Pox Plus, a polyamidoamine epoxy, which is certified in accordance with NSF/ANSI Std. 61 for use in potable water. Exterior steel received an airless spray-applied intermediate coat of Series N140 and a finish coat of Series 1074 Endura-Shield II, a high-gloss, aliphatic acrylic polyurethane, which is highly resistant to abrasion, wet conditions and exterior weathering. “D&R worked closely with Tnemec and the on-site construction team to select colors that allowed the tanks to blend in with the rugged environment in the Rio Grande basin,” Salvato noted.

“The Buckman Direct Diversion Project allows the two underground aquifers that have traditionally provided the region with its drinking water to recharge by using water diverted from the Rio Grande River,” Salvato explained. “During times of severe drought, these sources have been stretched to their limits, so a renewable source of safe drinking water was needed.”

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