Bolted tank helps city meet growing potable water demand
Problem: The city of Dickinson, North Dakota, faced difficulty with its reservoir water system. As the community grew, low water pressure threatened to impair fire protection and became an issue in the developing areas.
Solution: The city needed more water storage. Factors considered were the appearance of the tank, tank maintenance and cost-effectiveness, the tank’s ability to function with the existing reservoirs, and the tank location. A stainless steel standpipe reservoir tank was the solution. American Structures erected a 520,000-gallon-capacity bolted stainless steel tank that requires little maintenance, handles fluctuating flows and functions well with the existing infrastructure. The city added a solar-operated mixer to protect water quality and save energy.
Result: The issues of reservoir capacity, low water pressure and fire protection capability were rectified. 715/235-4225; www.ameristruc.com.
Fabric building provides efficient sludge bed cover
Problem: In the past 10 years, the village of Huntley, Illinois, has grown from 6,000 to more than 23,000 residents. The village’s two activated sludge wastewater treatment plants needed covered storage for biosolids. “We get charged by the cubic yard,” says Steve Zonta, utilities superintendent. “When stored without cover, it would get rained on and grow in mass.”
Solution: The team chose a Hercules Truss Arch Building. “I saw a ClearSpan catalog, spoke to a truss arch sales specialist, and realized that a fabric structure would be a cost-effective way to solve our problem,” says Adrian Pino, chief wastewater operator. “We already had a wood structure with a metal roof at the East Wastewater Treatment Plant, and the structure we chose came in at less than a third of what the other structure cost.”
Result: With a 77- by 96-foot building, the village can store up to 13,000 cubic yards of material under cover. “The warranty and the fact that the building could be engineered to specific snow and wind loads were important,” says Pino. “It proved that this wasn’t going to be just a temporary solution.” 866/643-1010; www.clearspan.com.
Company evaluates, repairs 40-year-old tank
Problem: The Lewisville (Texas) Water Treatment Plant needed to rehabilitate a 40-year-old, 1-million-gallon conventionally reinforced clearwell tank. An underwater inspection confirmed leakage through cracks and joints in the floor and wall, along with structural deficiencies at various column bases and pipe penetrations. The concrete exterior was weathered, and the access hatches were inoperable.
Solution: DN Tanks – Concrete Tank Services (CTS) evaluated the tank and failed previous repairs, and developed a plan that included applying an elastomeric waterproofing material on the interior floor, floor joints and column bases, along with structural repair to the inlet pipe. CTS also cleaned and restored the deteriorated concrete, applied a high-performance decorative coating, designed new hatch curbs and installed two new aluminum roof access hatches.
Result: The city now enjoys a refurbished tank that will have an extended life and comply with Texas Commission on Environmental Quality requirements. 800/662-8486; www.dntankscts.com.
Turnkey solution eliminates downtime and improves performance
Problem: The Grass Valley (California) Wastewater Treatment Plant serving 12,000 residents had chain and scraper systems approaching end of life, burdening the operations and maintenance. When the collector system in two of the tanks became inoperable due to a breakdown of the shaft drive system, only one tank remained operational, threatening shutdown of the entire system.
Solution: The city commissioned an upgrade to Envirex Chain and Scraper collections systems from Evoqua Water Technologies. The system uses nonmetallic chain with a lightweight design for easy installation and maintenance. The existing triple-output drive system was replaced with three individual drives to provide operational flexibility, simplify maintenance and reduce costs.
Result: The turnkey solution was provided under a tight timeline. Downtime and maintenance issues were eliminated, and the systems increased solids removal efficiency. 800/524-6324; www.evoqua.com.
Grit tanks covered to help address odor concerns
Problem: The Georgetown (Ontario) Wastewater Treatment Plant was built in 1960 in a remote area, but in the mid-1990s, houses were built less than 110 yards from the property line. Although plant management introduced several odor control technologies, including oxidizers, vaporizers, misters, ozone and carbon systems, the neighbors still complained. The staff identified its grit tanks as a significant source of odors.
Solution: Geomembrane Technologies designed and fabricated two structurally supported covers for the 8- by 33-foot grit tanks. The retractable covers consist of a high-strength, UV-protected, coated fabric tensioned over a low-profile aluminum arched frame. Foul air from below the covers and inside the grit building is withdrawn and treated in a carbon system.
Result: The covers have helped the plant make progress against odors and improve relations with neighbors. The covers control odors and easily retract, meeting access requirements. One person can open the covers for routine inspections. “Covering the grit tanks was one of the most effective things we could do to further reduce the potential for odors,” says Wendy Derjugin, plant operations supervisor. 506/449-0993; www.gticovers.com.
Covered digester system helps eliminate odor problems
Problem: The city of Madison (South Dakota) Wastewater Treatment Plant operated an anaerobic digestion system. Odors from excessive ammonia accumulation and foaming were prevalent. The system also had operation and maintenance issues dealing with methane, and gas vents froze during winter.
Solution: The city hired Banner & Associates to design a new aerobic digestion system. The company retrofitted the two anaerobic digestion tanks with an Ovivo USA Airbeam Cover Aerobic Digestion System to minimize odors and operating and capital costs.
Result: Biosolids enter the digesters at 2.5 to 4 percent solids; material exits at 1.5 to 2 percent solids. Solids reduction is achieved by maintaining temperature control, aeration and mixing. Solids reduction ranges from 40 to 60 percent. Ammonia concentrations are consistently below 2 mg/L in each digester. 512/834-6000; www.ovivowater.com.
Skimmer effective in removing surface scum at chemical plant
Problem: A specialty chemical manufacturer in Deer Park, Texas, was having issues with a circular clarifier. The unit uses a simplistic scum skimmer that was inefficient and ineffective. The scum buildup created operations and maintenance problems.
Solution: The manufacturer installed a custom-designed surface skimmer system from Kusters Water/Hi-Tech. The system was adapted to fit the clarifiers and included two full-radius collection arms with pivoting skimmer heads.
Result: The new design is much more efficient and effective. 800/264-7005; www.kusterswater.com.
Berm cracking issues at tank terminal site solved using geosynthetic cementitious composite mats
Problem: Asphalt emulsion had been used for years as hard armor berm protection for a secondary containment system at a tank terminal site in the state of Washington. However, frequent cracking of the berm led to high maintenance and repair costs and operation disturbances from recoating every five to seven years.
Solution: In late 2014, the asset owner selected Milliken Infrastructure Solutions’ Concrete Cloth GCCM, a flexible, concrete-impregnated fabric that hardens on hydration to form a durable, waterproof and fire-resistant concrete layer. It helps reduce installation time and the maintenance associated with slope erosion, vegetation growth and animal burrowing. Sandbags were first used to elevate the berm height to meet requirements. Bulk rolls of the cloth were then spooled down to cover the berm and fixed to the concrete infrastructure. The cloth was placed into an anchor trench and backfilled with a compacted asphalt road base on the inside and outside of the berm. Finally, the solution was hydrated using a high-volume hose attached to a water hydrant.
Result: The new surface minimized daily operation disturbances and upgraded the secondary containment berm to allow for possible expansions. It was installed in seven days using minimal personnel. It has drastically reduced maintenance costs and safety concerns while improving impermeability and aesthetics. 864/503-2020; www.milliken.com.
Insulated cover makes oxidation oval more efficient
Problem: A municipality in northern Illinois relied on an oxidation oval for wastewater treatment. However, cold weather created problems; the city needed to improve system efficiency during winter.
Solution: The facility upgraded with insulated covers from Industrial & Environmental Concepts (IEC). The plant team chose a floating insulated cover on the oxidation oval.
Result: Insulating the water surface reduced heat loss and improved anaerobic and aerobic processes, enabling reliable year-round treatment. The system performs successfully all year. 952/829-0731; www.ieccovers.com.
Seamless, chemical-resistant lining repairs city pool’s overflow basin
Problem: The city of Houston, Texas, operates 37 outdoor public pools. After years of contact with pool water and chemicals, one pool’s 20-foot-long by 15-foot-wide by 18-foot-deep concrete overflow basin was leaking and had to be shut down to avoid further damage.
Solution: The city applied HiChem HP 11-70, a 100 percent solids, zero-VOC polyurea-based lining, with high chemical and corrosion resistance, high tensile strength and dense, impermeable chemical structure from Rhino Linings. After the concrete surfaces were cleaned and prepped, the contractor applied Moisture Guard, a penetrating primer that creates a moisture-resistant barrier. The next day, workers roller-applied 5 mils of Primer 251, a flexible polyurethane primer and sealer that resists acids, hydrolysis and salt. After curing, 110 mils of HiChem 11-70 was sprayed in overlapping passes to ensure a monolithic seal.
Result: The entire application was completed in three days by a three-person crew. The application created a seamless, chemical-resistant, permanent seal in the 40,000-gallon overflow basin. The city plans for the same application at other pool locations. 800/422-2603; www.rhinoliningsindustrial.com.
Fiberglass buildings provide quick solution to cover existing equipment
Problem: The East Norriton-Plymouth-Whitpain (Pennsylvania) Joint Sewer Authority Wastewater Treatment Plant had two large pieces of equipment that needed to be covered.
Solution: The authority chose RM Products to design, fabricate and deliver a 12-foot-wide by 44-foot-long by 12-foot-high fiberglass building and a 20-foot-wide by 40-foot-long by 11-foot-high fiberglass building to cover the equipment.
Result: Using RM’s modular design, the buildings were erected around the equipment. RM provided a supervisor to oversee the job, which was completed in less than 10 days. 800/363-0867; www.rmfiberglass.com.
Piston pump increases biosolids loading capacity
Problem: The Alberta city of Edmonton’s Gold Bar Wastewater Treatment Plant saw cake storage and transfer to truck loading as a bottleneck. Operations included storage of mechanically dewatered biosolids in a Schwing Bioset push-floor bunker. From there it was pumped to a composting operation. Area growth led to biosolids volumes exceeding composter capacity, and a screw conveyor bypass was installed from the storage bunker to divert excess biosolids to truck loading for land application. As biosolids production grew, the bypass was no longer a viable solution. Loading each truck took 45 minutes.
Solution: Edmonton installed a piston pump in the Schwing Bioset storage bunker to transfer biosolids to two 250-
cubic-yard sliding-frame truck loading silos, which can store enough material to seamlessly support plant process flow. Each silo has three drop points to load two styles of trailers. Hanging pendant controls allow drivers to load without leaving the truck cab.
Result: The plant can now easily handle its biosolids production and can load trailers in less than 15 minutes without repositioning. 715/247-3433; www.schwingbioset.com.
Tank manufacturer supplies units for large expansion
Problem: A large-scale expansion project of the Changi water facility in Singapore required a number of bolted and reverse osmosis flush tanks.
Solution: Thirteen Tank Connection bolted, rolled, tapered panel tanks were used. These included five tanks with aluminum geodesic domes, each measuring 135 feet in diameter and 46 feet tall with 4.75 million gallons capacity. The project also included four reverse osmosis flush tanks with 26,400 gallons capacity and four reverse osmosis feed tanks holding 58,000 gallons.
Result: All 13 tanks were supplied in a timely manner in early 2016 with no issues. The contractor and end users were satisfied with the project execution. 620/423-3010; www.tankconnection.com.
Tank coating designed to withstand temperature variation
Problem: In Cortland, Illinois, a limited budget prevented the owner of a 125-million-gallon elevated municipal water storage tank from abrasive blasting a failing 20-year-old alkyd paint system on exterior steel before recoating. The project called for minimal preparation consisting of power washing steel at 6,000 psi and some mechanical hand- or power-tool cleaning to remove loose rust, scale and deteriorated coatings.
Solution: Workers applied a single-component, mastic waterborne acrylic coating for use on minimally prepared sound, rusted steel and previously coated surfaces as a rust-inhibitive spot-primer and tie-coat to the steel tank surface. In addition to strong adhesion, Series 118 Uni-Bond Mastic from Tnemec Company offers 200 percent elasticity and impact resistance. The coating expands and contracts with the substrate as the temperature varies. Two finish coats of a water-based, low volatile organic compound, high-dispersion, pure acrylic polymer were applied over the primer.
Result: After a severe winter of freeze-thaw conditions, the overcoating system maintained its color and gloss stability. 800/863-6321; www.tnemec.com.