Iowa Rural Water Assists Community with Water Chemistry; Reduces Nitrites and Saves Money
WELLMAN, Iowa – When the City of Wellman, Iowa started showing high levels of nitrites in their water, assistance from the Iowa Rural Water Association helped adjust the system’s water chemistry, removing the nitrites and saving money.
“When I first started working with Wellman, they had two wells and one was bad,” said Joe Finch, an IRWA Circuit Rider. Circuit Riders are roving water experts that provide training and technical assistance to communities.
The problematic well was high in ammonia and naturally-occurring bacteria.
“The well had a lot of bacteria,” Finch said. “The transmission line was becoming restricted with bio growth.”
Unfortunately, the system’s permit was for two wells with their water blended. Finch worked with the utility, their engineer, and the Department of Natural Resources to amend their permit for one well. The remaining well still produced too much ammonia, but with levels that could be managed with changes to the existing treatment process. “We are unique in that we’re still small enough to have a limited staff and a limited budget, but we still have a very complicated treatment process,” said Tim Garrett, Water Superintendent for the Wellman waterworks.
Wellman’s system was designed to pre-chlorinate the water before the iron filters. The water was then dechlorinated before passing through reverse osmosis membranes, because the membranes couldn’t be exposed to chlorine. The process was not producing the desired water quality.
“We ran into a high nitrate MCL,” Garrett said, referring to the Maximum Contaminate Level standard.
The system would produce too many nitrites and still showed high ammonia levels after the filters were backwashed.
Finch took a mobile water testing lab to Wellman and ran a series of tests throughout the system. After examining the tests, he determined that the pre-chlorination was inhibiting the growth of the nitrifying organisms used to remove the ammonia. He advised turning off the pre-chlorination and the sodium bisulfate pump used to dechlorinate before reverse osmosis.
Finch and Garrett then started a process to track the water’s chemistry as it moved through the treatment plant.
“We both knew what we wanted to do,” Garrett said. “We set up a data-tracking system that allowed us to test and track the water as it moved through the plant daily.”
Finch created a Dropbox account where Garrett could upload the results of daily tests. Then each of them could monitor the results and start making changes. As the changes affected water quality and chemistry, they could identify them and make any corrections needed.
“You don’t want to fix one problem and create another one,” Finch said.
The pair monitored reports for pH, chlorine residual, ammonia, total dissolved solids, nitrites, nitrites and Langelier index, a measure of the water’s corrosion potential. Finch was especially cautious of monitoring the water’s corrosion, to prevent any heavy metals from dissolving in the water.
“It took a while for the biological process to catch up, but eventually it worked,” Finch said.
The changes have made the Wellman plant easier to operate and more efficient. In addition to higher water quality, the community is saving on reduced chemical use and longer RO membrane life.
“Joe has been a big help,” Garrett said. “When you have a small staff it’s nice to have an extra person to reach out to.”