Robust power to the rescue
Lewis & Clark Regional Water System (LCRWS) of Sioux Falls, S.D., is a consortium of 20 members: 15 cities and 5 rural water districts in southeastern South Dakota, northwestern Iowa, and southwestern Minnesota. Members will receive treated water from a network of well fields located near the Missouri River. The ambitious, $550-million program has been in the making for 20 years, and construction is well underway.
LCRWS is scheduled to begin operations in March 2012. When completed, the 337-mile project will serve more than 300,000 people and either replace or supplement their current water sources. One member of the system is the City of Sioux Falls, which will receive a needed secondary source of water from LCRWS. The city will be able to buy up to 28 million gal of water per day (MGD) once it has been connected to the operational system.
As would be the case with any project of this scale, LCRWS is faced with challenges from every quarter. However, the focus of this particular study is standby power generation—both at the Vermillion Treatment Plant and eventually for all of the pump stations in the system. The treatment plant, storage facilities, and connecting network of pump stations each need a 100% reliable source of power and systems redundancy to provide an uninterrupted water supply to customers. Overall engineering project manager Dave Odens, of LCRWS-contracted engineering firm Banner Assocs., explained, “The main problem we wanted to address here is the need for standby power in the event of a complete utility power failure. We have to provide reliable standby power at the well sites that is basically capable of operating the system at near full capacity. Likewise, standby power generation is necessary at the water treatment plant that provides us with the capability to operate the plant essentially at full capacity.”
Furthermore, and significantly impacting the reliable operation of the equipment itself, was the need to ensure maximum protection of all standby power generation equipment via custom designed, robust, walk-in enclosures—required to provide an uncompromising level of protection from adverse convective weather conditions, as well as the occasionally hostile seasonal temperatures that exist in the north central United States.
Design and specifications called for total standby power capacity of 6,000 kW in three generator sets (gensets)—diesel engines mated to generators and power controls and placed within weatherproof steel enclosures equipped with integral fuel tanks for storage of No. 2 diesel fuel oil, to power the generators.
Butler Machinery Co. of Sioux Falls was selected to supply Caterpillar equipment for standby power generation for LCRWS. The supplied gensets are CAT Model 3516C-HD TA diesel engines, rated at 2,000 kW; 2,500 kVA; 60 Hz at 1,800 rpm; and 12,500 V. Lectrus’ South Dakota Operation (formerly D.T.S., Inc. of Tea, S.D.) was approached to design and build the modular steel enclosures for the gensets, completing the standby power supply packages.
Lectrus sound-attenuated generator enclosures are extremely robust, freestanding buildings. The units built for LCRWS each contain four full-height, hinged, lockable doors with NFPA crash hardware and bolt-on steps. Venting and motorized intake and exhaust louvers/dampers are also an integral part of each building.
The generator enclosure dimensions are 12-ft wide x 32.6-ft long x 14.3-ft high. The structures are certified to meet IBC standards including wind and snow loading. The outer wall of each enclosure is constructed using a 14-gauge, 4-in deep steel welded and bolted design. All fabricated steel parts conform to ASTM 569, specification C-1018, and all structural steel meets ASTM A36 requirements. The inner wall consists of fiberglass insulation and a perforated, galvanized steel liner. Every enclosure is painted with durable, long-lasting weather-resistant coatings.
The genset enclosures’ integral, low-profile 3500-gal sub-base fuel tanks are made from structural steel, baffled and interior coated with durable rustproof coating to create a leak-proof, long-lasting reserve. As shown in photos accompanying this article, the tanks present a compact footprint. They are also UL 142-listed and designed to meet UL 2085 fire requirements.
“We also experience ice storms,” Odens added. “Two years ago we had one that knocked out power for about four weeks—not at Vermillion, but 30 miles west of there. We work with a lot of utilities that were without power in parts of their system for four weeks, so a standby generator becomes pretty important. And having one in a Lectrus enclosure is even more critically important because you can operate and maintain that generator in adverse weather conditions.”
“We’ve used Lectrus enclosures in quite a few projects over the years. It’s more or less a standard of how we design and operate standby power systems.”
Water and power are crucial needs in every area. LCRWS is addressing both in tangible, efficient ways. Jim Auen underscored the significance of the program. “It’s a unique approach that Lewis & Clark has taken and it’s a regional approach. We’re going to be providing water to parts of three states, which has never been done before to our knowledge. We’re addressing critical water needs for our members: each system presently has unique challenges with its current water sources—they either aren’t adequate or they are of such low quality that it’s difficult for them to fully utilize that source without expensive treatment options. We will be producing high quality, reasonable cost water that in some cases will be the sole source of supply for some of our members. And we’re doing it in a manner that would’ve been financially impossible for the members to undertake on their own.”
Whether or not a similar level of criticality exists in every other industry, a main issue remains: if power is interrupted, process safety, life safety, deliverability of products/services, and business viability all suffer. The risk for that eventuality can be completely mitigated with reliable standby power systems placed within robust, weatherproof enclosures.
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