MONMOUTH -- City officials plan to start construction later this year on a water treatment facility to reduce high nitrate levels in Monmouth's potable water supply.
Keeping nitrate concentrations at a non-threatening level, and more importantly, protecting the town's ability to meet water demand during peak use months, are the primary reasons for the system, said Public Works Director Craig Johns.
The $1 million project -- included as an item in Monmouth's 2005-06 capital improvements budget -- will be located at the city's well field on 4th Street.
"The goal is to have it finished by summer of next year," Johns said, "that's when the (nitrate) issue normally looms."
Nitrates are chemicals found in manure, fertilizers and waste discharge from septic tanks. They can be carried through the soil into groundwater.
Consumption of nitrates can reduce the ability of the body's red blood cells to carry oxygen, and can result in a potentially life-threatening condition in infants called "blue baby syndrome."
Monmouth gets the majority of its potable water from its "Marion County well" located across the Willamette River from Independence. Periodic nitrate concentration has been an issue with the well since it was activated in 1978.
The EPA sets nitrate standards in drinking water at a maximum 10 milligrams per liter (mg/l).
The Marion County well averages under 5.5 mg/l, but have risen as high as 11 mg/l during the winter, which may coincide with the application of fertilizer on nearby farmland during the summer and fall.
When nitrate levels spike, the city blends water taken from the Marion wells with water from two wells on a site in Independence before its delivered to the Monmouth consumers.
The main problem is having to tap those alternate wells during the summer months, when household usage is at its highest and the wells are at their lowest. That decreases the amount of water the city can produce to meet demand, Johns said.
The treatment plant would use a filter and sodium chloride -- salt -- to remove the negatively charged ions found in nitrate. The salt water would then be backwashed and deposited into the city's waste water system.
Johns said the cost to operate the treatment facility would be minimal -- the plant would only be open three to five weeks a year, mainly during times when the nitrate level has crept upward.
Edward Butts, an engineer and water consultant to the city, said that having the plant would help Monmouth protect its current water supply.
Permitting and engineering issues will prevent the city from adding surface water to the municipal water system for more than five years, Butts said.
The facility could aid in the search for future water sources. With a means of treatment, the city could consider tapping existing groundwater sources with elevated nitrate levels, he said.
Related story: OSU offers free well water testing. See Page 9A.