MUSCATINE, Iowa – A suspected leak in the force main pipe that was repaired over the winter was found not to be coming from the new pipe but from the abandoned 30-inch force main.
“The good news is that the pipe is fine, there is no leak,” Jon Koch, Water Pollution Control Plant (WPCP) Director, said.
The WPCP located a suspected force main sewer line leak just 500 feet east of the plant at 1202 Musser Street early Tuesday (Apr. 24) and that led to an excavation of the area around the suspected leak Tuesday afternoon.
“What we found about 7 p.m. last night after we got the area excavated was that the now abandoned 30-inch line had been filling up with water,” Koch said.
Koch noted that there are eight incoming pipes from all over Muscatine that point up and overflow next to each other as they enter the plant. The old 30-inch pipe and the newly installed 24-inch pipe sit next to each other. As the waste water splashes up from the eight incoming pipes, some of that splashing made its way into the presumably empty 30-inch pipe.
“That was enough to fill the 500 feet or so to where we cut the 30-inch pipe last fall to slip in the 24-inch line,” Koch said.
Grout was poured around the end of the abandoned 30-inch pipe as the repair work concluded last February, and it is suspected that the grout shifted with the thaw allowing the water to find a way out.
“It was in the area where a welded seam was so we thought that was the source,” Koch said.
The Papoose Creek Lift Station on the Muscatine riverfront was shut down at 4 p.m. Tuesday in case the new line had to be drained. The lift station was put back on line at 7 p.m. to verify the condition of the exposed pipe and no water came out.
“This is good news as it means the pipe is intact,” Koch said.
After chiseling out the grout, the remainder of the old 30-inch main was drained. The City is now looking at how to best cover the 30-inch line so it does not take in water.
The old 30-inch force main was lined with a 26-inch pipe over the winter after a break was discovered in the pipe near in the intersection of Day, Birch, and Nebraska Streets. Most of the 30-inch pipe from Musser Park to WPCP had a fused 26-inch pipe inserted in January and February this year.
The old force main was cut out in three places during the repair work to allow the new pipe to be inserted and fed through the rest of the old 30-inch main.
No other problems have been reported since the new line was placed into use on February 12, 2018.
The leak in the old force main was discovered on October 30, 2017, with repair work beginning in November. The Papoose Creek lift station was shut down over the winter as repairs were completed and returned to service on Feb. 12.
The Iowa Department of Natural Resources was informed of the potential leak and the three-hour shutdown of the Papoose Creek Lift Station. No problems were expected from the short duration and minimal amount of overflow into the Mississippi River during the time the lift station was not in operation.
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