As one of 4,000 systems across the country with arsenic levels above the new EPA standard, the Baldy (Calif.) Mesa Water District (BMWD) is faced with finding a viable treatment process for arsenic removal that can be approved and implemented by January 2006.
There is little time to waste, as the district has less than two years to evaluate and install a treatment system at all nine of their well sites. Unlike other purveyors who may have access to blending sources or imported water, BMWD requires treatment on all nine of its well sites. Additionally, BMWD must be prepared to meet a standard for arsenic levels that has yet to be determined by the state of California and which is expected to be substantially less than the federal limit of 10 ppb.
BMWD is an independent special district, formed in 1965 to serve water to an area in the high desert of southern California. BMWD encompasses approximately 24 square miles within the Victor Valley, west of the I-15 freeway, serving the city of Victorville.
The district has approximately 5,500 service connections and is 100% dependent on local groundwater. The groundwater is pumped to the system from nine wells that produce a combined 7,724 gpm. Additionally, the district has seven storage reservoirs with a total storage capacity of 14.4 million gallons.
Because all nine wells in the system exceed the new federal EPA standard for arsenic of 10 ppb, the district has been actively involved in evaluating various technologies for arsenic removal.
When considering and evaluating potential arsenic removal technologies, the district was looking at several key factors. The most important are the following:
- Capital costs: The cost to purchase and install a treatment system is critical to evaluate the economics. BMWD estimated the capital costs to be in the neighborhood of one million dollars per site, which would have a significant impact on the capital improvement budget of the district.
- Operating costs: The actual operating costs for an arsenic removal system are often underestimated. These costs include more than just utilities, chemicals and general O&M. Other costs would include media replacement, residuals disposal, disposal of backwash water, costs related to a system pressure drop and additional sampling.
- Arsenic residuals: In California, hazardous waste resulting from a treatment process is a key consideration. Iron media and ion exchange will both produce solids that will need to be disposed of in a Class I landfill. This is a complex area, which can have a detrimental impact to the overall costs of an arsenic treatment system.
- System downtime: This is a key consideration for any water purveyor, but even more critical for a district requiring treatment at all of their wells. It is imperative that any system downtime be kept to a minimum.
- Delivery time: Important factors include a guaranteed delivery schedule by the supplier, and a technology that has been accepted by the Department of Health Services for the state in which the unit is operating.
Based on these criteria, BMWD contracted with Basin Water to supply a 1,000-gpm high efficiency treatment system for its Well #1. Basin Water structured a processing contract with the district, which minimized capital costs and provided substantially reduced operating costs as compared to alternative technologies.
The California Department of Health Services approved the turnkey approach and the system was permitted within weeks. According to the BMWD, the technology has been able to treat arsenic to non-detect levels, which puts BMWD in a position to meet the potentially lower standard anticipated in California. BMWD is also confident that the packaged system will ensure compliance with the 2006 Federal Arsenic deadline.