City of Cassville considering $5.4 million sewer project

Wednesday, October 21, 2015

Coupled with water system plan, proposal would require bond issue in early 2016

The city of Cassville has long had an issue with inflow and infiltration into its sewer system, and a study done by the engineering firm Olsson and Associates has given the city council an idea of what it would take to tamper down on the issue and avoid fines from the Department of Natural Resources.

Olsson has proposed to the city a five-year, $5.4 million plan to fix the ailing system and bring the city into full compliance, mainly by reducing the total amount of water being processed by the city's wastewater plant.

In 2011, Cassville entered a voluntary compliance agreement with DNR, as the state said the city could no longer release untreated water from its lagoon into Flat Creek. The agreement gave the city one year to form a plan to stop the problem, then four years to execute the plan.

After receiving an extension on the agreement, the city contracted with Olsson, with the help of a $40,000 grant, an 80-20 match with the city paying 20 percent, to perform a collection system study, which showed many areas of Cassville have old and failing sewer pipes that need replaced, not just rehabilitated.

The city has a 1.1 million gallon-per-day wastewater treatment plant, with an 18-acre lagoon to catch overflow, which is suppose to be sent back through the plant later when the capacity is available. Because of inflow and infiltration issues, mainly created by rainwater and groundwater getting into sewer pipes, the plant is processing about double what the water system is putting out.

In 2005, a study determined more than 200 pipe deficiencies, mostly in the downtown area, in the lower-lying parts of the city. This is also where the oldest pipes are located, and where the majority of ground saturation occurs.

To head off the problem, Olsson proposed improvements that include pipe and joint pressure testing and grouting, lateral connection pressure testing and grouting, manhole rehabilitation and pipe machine testing, where joints could be sealed. Work would include some open-cut projects, cleaning and CCTV use inside the pipes, butting protruding tape and gaskets, curing pipes and private inflow and infiltration abatement. Projected costs are as follows:

* $2.7 million on open-cut and trenchless repairs (trenchless repairs include grouting and other approaches that avoid digging to any pipes)

* $150,000 on cleaning and CCTV use

* $1.5 million on private inflow and infiltration abatement

* $1.05 million on non-construction and contingency costs

The trenchless repairs, which garner most of the $2.7 million projection, would have a 50-year design life. Work would also result in some savings at the treatment plant, as it would be pumping less, therefore, using less electricity.

The city has 93,000 linear feet of pipes that need attention, which accounts for about 52 percent of the city's 180,000-linear-foot total.

There are 18 open-cut areas, which would include the excavation of certain areas and total replacement of pipes. Most of these areas are in downtown Cassville.

Olsson proposed a schedule for the project if Cassville wishes to proceed, saying the rest of this year would be used to finalize plans and come up with a rate analysis. In spring 2016, the city would request a water-sewer bond issue, tying the sewer project to a water project that has been on hold after a study was completed by Schultz Surveying and Engineering of Branson.

That project, which comes with a $4.89 million price tag, aims to replace half of the city's 43 miles of water pipes.

If a bond issue is passed and plans are submitted to DNR, Public Works Director Steve Walensky believes that would show enough effort for the city to get another five-year extension on the voluntary compliance agreement.

Design for the sewer project would continue through 2017, and repairs themselves wold take place from 2017-2020. After all the work is completed, the private inflow and infiltration abatement would come in, which would give the city a clearer understanding of where any remaining issues occur or where a new issue arises.

While the proposal is not cure-all, Walensky said the bond issue money would allow the city to save on its maintenance budget, which it could use to solve other issues outside of the scope of the project.

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