Slater City Council receives report on smoke testing survey

Friday, September 9, 2016

The Slater City Council received a preliminary report of the smoke testing survey conducted by Civil Design INC (CDI), at the council meeting Tuesday, Sept. 6.

Project Manager Jeremy Linley and Project Engineer Stephen Thole of CDI were present to review the findings of the testing survey and give the council a snap shot of the full report, which is yet to come.

According to the two CDI representatives, the theory is that both smoke and water flow to the path of least resistance, and that any cracks or entryways in the city's water lines will be identified by smoke emanating from the damaged area. The reason these areas are a problem is because water can enter into these pipes, and due to rising water cleanliness standards, efforts to reduce the contaminating "inflow and infiltration" have been put in place. The city first had to identify the locations of major concern, which were the main topic of discussion that evening.

Thole spoke extensively about the project and the process they took throughout the whole procedure. In addition to the smoke testing CDI also performed manhole inspections last year

"During the inspections we found 61 of them that showed significant inflow and infiltration," Thole said. "They either had signs of it from staining on the walls of the man holes or their actively having ground water come in at the same time."

A report of these manholes was generated along with GPS coordinates of each that will be made available to city workers when they need to locate them, the same process was repeated for smoke testing as well.

"For smoke testing, all sewer sheds in Slater were tested that are on the city map," Thole said. "During the testing, 359 defects were located ... of (that number) 50 of them were determined to be a significant source of inflow into the sewer system."

Linley also spoke up during this section of the presentation to clarify that a shed is defined as particular portion of the city that all drains to a particular point.

"Because the system has a lot of pump stations or lift stations in the area, a lot of times we focused our efforts on a certain set of sewers that drain to that pump station," Linley said.

Thole covered the results of the testing, touching on three locations regarding the manholes, the worst of which was located next to the pump station on Watts Street, was tested by flooding the area.

"There is a ditch that runs along the north side of Watts," Thole said. "We sandbagged off the culvert going to the south and dye flooded it ... and waited for the dye to show up, and it showed up in this manhole."

As Thole explained, a video was played showing a large portion of water that had red dye, confirming a significant amount of infiltration was taking place at this location, several examples around town similar in nature were discussed to give the board and idea of the findings.

The two continued to review several locations around town, both located on private property and public, and discussed the locations that pose more of a risk for infiltration. Being as the final report will provide a more precise outline on how to tackle the project, which according to the results of the presentation will be approximately $1 million, exact details about how the city will begin work on the reduction project has yet to be developed.

"I don't think the manholes are the big problem out here," Linley said. "A lot of the manholes are in pretty good shape."

The main problem seems to be from infiltration through what Linley described as cross connections of sewer line and other areas where water is seeping into the sewers.

"So really looking at the recommended rehabilitation, we're really focusing on the pipes, (and) sewer lining, because I really think the majority of the inflow ... is coming from," Linley said. "Looking at the high priority ones, that's any sewer that had a cross connections, whether it was a ditch or large culvert, or an actual sewer there, or if it had multiple sewer defects or cross connects, or if it had one of those two and was adjacent to a creek or ditch."

The final report will contain more detailed planning suggestions on how best to prioritize the repairs and, which will be city versus private responsibility, but with the large price tag for the whole projects it was clear the planning will be spread out over years to come.

Contact Lucas Johnson at ljohnson@marshallnews.com

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