At a total treatment capacity of 22 MGD, the Virgin Valley project is one of the largest arsenic treatment projects in the nation, and one of the first of its kind to utilize conventional filtration treatment for arsenic removal.  Based upon the treatment alternatives study results, the recommended conventional filtration treatment system design resulted in substantial life cycle cost savings to VVWD over other proprietary technologies.  The project included construction of five separate treatment plants designed to remove arsenic from eight groundwater wells using a coagulation/filtration process with chemical addition.  The filtration takes place in steel vertical pressure filters with dual media filter beds.  The estimated project construction cost was $26,000,000. 

Key project tasks performed by the Bowen Collins & Associates team include: evaluation of current arsenic treatment process technologies and recommendation of the most economical and effective process; preliminary design and layout for the recommended treatment system; provided on-site pilot treatment system and supervise its operation.  The pilot study included evaluation and optimization of media depth, filter loading rates, chemical addition, and backwash process.  Final process recommendations were summarized in a pilot study report; assisted in the permitting process and coordinated with state and federal regulating agencies; and assisted the owner in qualifying for and obtaining state and federal funding for the project.

The final project design included the following elements: five separate plant buildings with a total of 27 vertical steel pressure filters, each with separate chemical room, mechanical room, filter room, and associated piping; backwash system, including air blowers, booster pumps, automatic flow/pressure control valves, piping and valving, system controls, and backwash disposal systems; instrumentation, process controls, SCADA, and power and electrical systems; building architectural and structural design, civil site plans, and landscaping plans; chemical storage, metering, and delivery systems, with a total chemical storage capacity of over 28,000 gallons, with a metering system capable of delivering over 1,200 gallons of chemical per day at the five plants; design of eight booster pump stations and four PRV valve vaults; hydraulic integration of the five plants into the District’s water distribution system; and full set of technical specifications and contract documents.

Quick Project Facts:

• Five separate treatment facilities – with a  total of 22 MGD
• $26,000,000 construction cost
• Bowen Collins & Associates completed the pilot study, preliminary design, final design and construction management
• Bowen Collins & Associates provided full instrumentation and control programming services.