2/18/2007 4:00:00 AM Prescott takes steps to meet
deadline on arsenic
standards
By CINDY BARKS The Daily Courier
PRESCOTT The deadline for the City of Prescott's compliance with new arsenic standards for drinking water now looms less than a year away.
By Dec. 31, 2007, the city must conform to federal standards on arsenic levels that went into effect in January 2006, reducing the acceptable arsenic levels from the previous 50 parts per billion to 10 parts per billion.
In preparation for that, a number of steps currently are under way in Prescott, according to city officials.
The biggest is a move to install wellhead treatment systems on each of the city's six production wells in Chino Valley.
Public Works Director Craig McConnell reported Friday that the city conducted a pre-bid meeting on Thursday with firms interested in bidding on the project. Representatives from 11 contractors attended the meeting, but McConnell pointed out that some of those companies may be interested in working as
sub-contractors for the project.
The city will open the bid proposals on Thursday, McConnell said, and the earliest the matter could go to the City Council for consideration is March 6.
At this point, McConnell said the cost of the project is still uncertain.
The wellhead treatment idea came up this past year in the wake of the city's initial proposal to build a $23.5 million central arsenic treatment plant. City Council members balked at the expense in part because of uncertainties about the arsenic levels in the water that the city plans to import from the Big Chino Basin.
At the same time, members of the public maintained that the wellhead treatment option would be less expensive than the central treatment plant, prompting the city to call for an independent analysis to determine the best treatment method.
With arsenic levels in the majority of the city's wells right at the brink of compliance, McConnell said the city is taking the approach that it will have to install individual treatment systems on all six of its wells.
About a year ago, the city released results from arsenic testing that showed that four of its wells were in the six-to-eight-parts-per-billion range, while two others had arsenic levels well more than 10 parts per billion.
In the meantime, the city has worked to bring down the arsenic levels in those two wells. McConnell pointed out that a recent cement grouting of the "lower alluvial stratum" of the city's well No. 1 served to bring down the arsenic levels from about 40 parts per billion to about eight-to-14-parts-per-billion.
City Manager Steve
Norwood pointed out that a similar procedure is in line for the other high-arsenic well, well No. 6. The Prescott City Council will consider a $46,000 contract on Tuesday for a cement-grouting process at the lower level of that well.
Norwood was hopeful that the procedure will bring the city closer to the federal standards. "We're much more optimistic than we were 12 months ago," he said. "It still could go either way, but if this modification brings it down, I think this would buy us some time."
Even so, both McConnell and Norwood stressed that arsenic levels tend to fluctuate. To be on the safe side, McConnell said, the city needs to aim for a level below the 10-parts-per-billion standard. "We need to provide some margin of safety," he said, adding that the city has "consistently chosen eight parts per billion" as its goal.
