The Ak-Chin Indian Community, located 35 miles south of Phoenix, Arizona, knew they needed an independent water source. The community’s water treatment plant treats water from the Central Arizona Project (CAP) system, which was the sole source of water for community residents. When the CAP notified all their users they were shutting down a portion of the canal for maintenance, the Ak-Chin community knew they needed another central water source quickly. To make the most of the few months available between the delivery of the equipment and the deadline, the project team rehabilitated wells that were already on-site and connected them to the existing distribution framework. By using temporary or rented pipe, we could start up and test the system earlier. Once the system was tested, we then replaced the temporary material progressively with permanent piping.
The Ak-Chin Community had at first hired PCL to test a well site and provide a design for a new pump and discharge line to the existing storage tank. The testing is a critical part of any water treatment project, but found contaminants in the water exceeded levels permitted by the Environmental Protection Agency.
PCL installed and commissioned a new type of skid-mounted reverse-osmosis equipment as part of a more comprehensive water solution. Reverse osmosis is an appealing water-treatment solution, and the latest technology makes it even more attractive. A typical reverse-osmosis system has a recovery rate of 75%, meaning that for every 100 gallons of raw water, 75 gallons of finished water are recovered, leaving 25 gallons for disposal. However, the solution our team proposed has a higher recovery rate of 85-87% and has lower capital and maintenance costs.
This is the first installation of this next-generation equipment in Arizona and one of only a handful in the United States. By investigating and implementing the skid-mounted system, the Ak-Chin community has a more complete project with permanent piping, pumps, pads and buildings, all in an operator-friendly, automated package. An additional benefit is that, with the CAP canal back online, the group can alternate between both wastewater treatment plants and now has an alternative source of potable water.