City to present plan for minimizing arsenic in its water supply
Appeal Staff Writer
Carson City officials have obtained a three-year exemption from the state that allows them to violate the new standard for arsenic in drinking water while definitive measures to improve the situation are put in place.
The Public Works Department has until January 2009 to comply with federal arsenic rules. Their plan will be presented during Thursday’s board of supervisors meeting.
The city just ended its warm-weather restrictions on water use this weekend, and the change of season brings with it “better news than we’ve had” for a while about the arsenic situation, said Andrew Burnham, the city’s development services director.
Summer came and went without the city going above the federal standard of 10 parts per billion. Warm months are when the standard is most likely to be violated because overall water demand substantially rises and the city’s water system operated at its capacity.
Residents consume 24 million to 27 million gallons during a typical summer day. They use 5 million to 6 million gallons on a winter day.
“It was a relatively mild summer,” Burnham emphasized. “Only two or three weeks were real warm.”
Ways the city plans to better guarantee compliance include monthly monitoring of the water system at various points and testing for water quality in and around the wells where the arsenic levels were highest.
When the city tested wells in 1999, before the new national standard was adopted, six weren’t within the 10 ppb limit. Seven of the wells weren’t within the standard last year.
Water from two wells will be subject to coagulation filtration and two others improved by an absorption system and blending. Well water from a fifth site will be blended with water from low-level wells. The last two should be within the standard by limiting the amount of water released for them, according to public works.
Cost to fix the problem has dropped substantially since the problem was first discovered. While officials thought the price tag would reach $10 million a few years ago, it now will only be a price tag of $2 million, Burnham said.
Arsenic is classified is considered a contaminant by the U.S. Environmental Protection Agency. The standard maximum amount of the semi-metal changed this year, a move that had been planned by the EPA since 2001, when it was dropped from 50 ppb to 10 ppb.
Supervisors aren’t expected to take any action, but they may want additional information or even seek to modify the plan. They approved asking for the exemption in December 2004.
Tests earlier this year indicated that uranium was too high in two other city-operated wells. This problem has been alleviated by mixing water from the wells with higher levels with water from other wells to create a source that doesn’t exceed 30 ppb, the federal standard for uranium.
There are 30 wells used to store water around Carson City. Once water reaches a home, it is a blend from three or four of the wells.
• Contact reporter Terri Harber at tharber @nevadaappeal.com or 882-2111, ext. 215.
If you go
What: Carson City Board of Supervisors meeting
When: 8:30 a.m. Thursday
Where: Sierra Room, Community Center, 851 E. William St.