GRAND JUNCTION, Iowa – When Grand Junction, Iowa had problems with low chlorine residuals and odor complaints with their water treatment facility, the Iowa Rural Water Association made multiple assistance visits to help correct the problem.
The Iowa Department of Natural Resources first contacted IRWA in April, to request rural water’s assistance. Dale Barrie, an IRWA Training and Technical Assistance Specialist visited the system and started examining the utility’s reports and testing results.
“At the time, the community felt the system was treating at close to ideal conditions,” Barrie said.
However, Barrie noticed that the Grand Junction lab did not have the appropriate equipment to test for certain residual chemicals, like monochloramine and free ammonia. The first recommendation was to acquire appropriate equipment to perform more thorough testing.
“I recommended that the chlorine feed be increased slightly to see if the breakpoint could be achieved,” Barrie said.
The breakpoint is the amount of chlorine required to satisfy all chlorine demand and completely treat the water. When utilities receive odor complaints, a common response is to reduce the chlorine feed, but the proper response is to increase the chlorine levels.
Barrie visited the system again after a sanitary survey found the presence of ammonia, a sign of possible nitrification. He recommended moving taps and ports in the system to better chlorinate the water and test the impact of changes made to the treatment process.
“We discussed moving the injection point to a more suitable point and adding a sample tap just before the water entered the distribution system,” Barrie said.
In July, the system’s chlorine pump failed and was offline for roughly 36 hours and Barrie visited again to assist. While the pump outage was a serious problem, it forced the utility to increase the chlorine feed. That increase helped reduce problems with chlorine residual and odor.
“The time without the pump caused the utility to increase the chlorine feed,” Barrie said. “This actually pushed the levels to the break point.”
The current feed pump was operating at close to maximum, but Barrie recommended that a different tube could be installed to increase the capacity. He also recommended overflowing the storage tanks to assist in turning over water. Once the recommendations were in place, the utility was able to keep the chlorine levels stable without odor complaints.
“Things went well at that point,” Barrie said.