IQ Spring 2012: The Conference Issue - (Page 15)

city’s projected growth and concurrent needs. In addition, MWH’s size, with the number of available personnel, indicated that it would be able to take on such a large project and manage the subcontractors who would also be working on it. The city’s entire water program involved more than 75 projects valued at a total of $873 million. The Southwest Water Reclamation Facility itself was a large-scale, 15.1 MGD plant expansion, budgeted at $130.8 million. It was completed in five task orders over a period of 55 months, encompassing everything from site clearing to modifications to existing systems to new construction. The large scope of the project was complicated by a number of factors, not the least of which was keeping the facility operational during the entire process. up for the chaLLeNge MWH faced several challenges. The water-treatment facility needed to comply with local building codes, including resistance to the hurricanes that sweep through Florida most years. But being located in a residential area and near a school, it had to fit in with the surrounding buildings. And the facility had to be able to capture and filter the fine, silty sand common in the area. In addition, the extreme heat dictated that concrete pours— which could take up to 10 hours—could only be done when the temperature would allow the concrete to be poured and cure. MWH was aware of these obstacles but, as work began, other challenges emerged. An unanticipated field condition prevented pouring the odor-control slab until an existing pipeline could be demolished. But that could not be done until new plant components were completed. Meanwhile, the existing operations building had to be condemned and rebuilt while the water continued to f low. MWH overcame many of these hurdles by working together with the City of Cape Coral. Because they reviewed their work regularly with the city, MWH and its subcontractors could be sure they were working within the city’s desired goals and keeping to their deadlines. Daily quality-assurance checks meant that any issues were resolved that same day. The city was impressed with the collaborative working relationship, deeming MWH as an extension of its staff. MWH used value engineering to build the clarifier tank with prestressed concrete walls in lieu of poured-in-place walls. returN oN INvestMeNt The MWH team scheduled all work to provide the most efficient and cost-effective means to complete the project. The team was constantly alert for ways to improve the final plant’s efficiency, keep operating costs down and ensure future maintenance was easy and less expensive. For example, MWH reclaimed two water-storage tanks—reusing the old tanks will give the facility more storage capacity during the rainy season and help avoid shortages during the dry season. It also made extensive changes to the activated sludge basin that increased efficiency and cut costs. The rehabilitated sand filters produce better quality effluent, as well as being more reliable. By diverting processed activated sludge from an existing facility to the new Southwest WRF, the older facility could remain in operation without requiring an upgrade. The addition of a grit-removal system meant that downstream equipment would be subject to less wear and tear, prolonging its usable life. Converting old oxidation ditches to sludge-storage tanks significantly increased capacity and may provide the city more flexibility in the facility’s operations. At one point piping was connected at 3:00 a.m., the lowest period of demand, in order to keep water flowing during construction. A temporary control room trailer was set up with all connections for control wires installed so they could easily be connected to the new permanent control room. Other innovations, both in systems and materials, reduced short-term dbia.org spring//2012 15 photo courtesy of Brent asay http://www.dbia.org

Table of Contents for the Digital Edition of IQ Spring 2012: The Conference Issue

IQ Spring 2012: The Conference Issue