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Town developing sewer master plan, updates, expansions

ms consultants, inc.

July 15, 2020

The Nashville Town Council plans to review a sanitary sewer master plan this Thursday that explains where service may be provided where it isn’t now, and what systems need to be expanded to keep up with current demands and future growth.

 

The wastewater treatment plant already needed to make some changes according to mandates issued last fall from the Indiana Department of Environmental Management.

 

Plant operators also have been aware for years of inflow and infiltration problems at the plant, where rainwater is flowing into the system to be treated when it isn’t wastewater, or untreated wastewater is flowing out of manholes or pipes because of overflows or cracks.

 

This draft master plan is a short- and long-term outlook at what engineering firm MS Consultants believes needs to be done with Nashville’s sanitary sewer system.

 

A first draft of the plan was given to the council around the start of the coronavirus pandemic, so it’s possible that the costs and recommended priorities for future work may need to shift.

 

The council could decide to vote on the plan at the July 16 meeting, which will take place virtually, or may hold off until in-person meetings resume.

 

Dax Norton, strategic direction adviser for the town, said he planned to have maps of the possible projects available in some way during the virtual meeting.

 

Improving infrastructure

 

The council voted on April 29 to sign a $787,000 agreement with MS Consultants to design a “sanitary sewer collection system and WWTP improvements project” for the town. The commitment was $75,000 upfront.

 

The town’s sewer system was built in 1961 and was expanded in 1968, 1981 and 2010, the master plan document says.

 

The wastewater treatment plant, which sits on the southern edge of Nashville near State Road 46 and Town Hill Road, is averaging about 65 percent capacity, Norton said in March. If the infiltration problem was fixed and maintenance was kept up, he believes it would be running at more like 40 percent capacity.

 

Currently, the plant serves “nearly 800” full-time residents, plus “hundreds more” who visit as tourists, according to a separate sewer evaluation which MS Consultants did earlier this year.

 

Pipes feed wastewater into the system by gravity into three lift stations — on Washington Street, in the Parkview neighborhood and at the Brown County Inn, the master plan draft says.

 

Most of the town’s sewer customers are homes, but three large commercial users “have the ability to significantly impact the strength of waste and volume” to the plant. In 2019, the three largest users were Brown County State Park, Brown County Health & Living Community and the Brown County Inn. The park by itself accounts for about 25 percent of the annual flow through the town’s wastewater treatment plant, the draft report says.

 

With the April 29 vote, the town council has committed to making some changes to the system.

 

The “statement of work” signed with MS Consultants in April includes preparing plans and specifications for the system to reduce inflow and infiltration; installing new aerobic digester tanks and blowers; and constructing a “sludge dewatering building” and a new chemical building, among other improvements. The consultants also would handle the bidding of the construction and installation work, and act as the town’s representative during construction.

 

The council OK’d MS Consultants being paid $75,000 with an additional $712,000 to be paid later, after funding for the project is secured. The council and consultants talked about seeking low-interest loans and grants from USDA Rural Development and the State Revolving Loan Fund.

 

MS Consulting also wrote the master plan for the sewer system, which includes guidance on things that should be fixed in the collection system itself.

 

The firm constructed a model of the current sewer system using GIS data and hydraulic information, and found three areas that are “reaching their design capacity.” Those are the 8-inch mains from Washington Street north on the left side, at Washington Street and Johnson Street, and upstream of the Brown County Inn lift station.

 

MS Consulting wrote that these problems are probably because of “excessive inflow and infiltration into the line.”

 

The report recommends that the town “rehabilitate” the collection system in four phases, lining the existing pipes to seal cracks or holes. This can be done without trenching, the report says. Manholes also should be inspected, it says.

 

The estimated cost of all four phases of the collection system plan is $3,165,000. The report estimates that each phase would take two to three years to complete, with work wrapping up in 2028.

 

Expanding service

 

In addition to examining the current sanitary sewer system, the draft master plan looks longer term at what other areas outside town limits could receive sewer service, and at what cost.

 

Currently, most sewer hookups are in town limits. However, a few out-of-town customers in Washington Township receive service too, such as the KOA campground, part of Brown County State Park, and the Brown County Music Center.

 

In 2013, by order of the county commissioners, all properties in Brown County that did not already have sewer service from another provider at that time became “customers” of the Brown County Regional Sewer District (then called the Bean Blossom Regional Sewer District). However, that sewer district has no way to treat wastewater yet. So, in 2018, the Brown County RSD vacated about a mile-and-a-half radius around town limits — basically, to the tops of the hills that surround major roads into town — in case the town ever wanted to extend sewer to those properties.

 

This draft sewer master plan includes several neighborhoods in that mile-and-a-half buffer zone as well as others, and prioritizes them, in the engineers’ opinion, according to how quickly the town should or could bring them sewer:

  1. Annandale Estates, 84 EDUs (equivalent dwelling units), estimated by 2022, approximate cost $2,900,000;
  2. Green Valley Church/Kelp Grove/Sam’s Hill/Hilltop Lane/Town Hill Road, 92 EDUs, estimated by 2024, approximate cost $5,950,000;
  3. Greenbriar Lake, 210 EDUs, estimated by 2028, (assuming treatment plant capacity is at 90 percent by this time and a plant expansion is under design), approximate cost $5,000,000;
  4. Bean Blossom area/Greasy Creek, 336 EDUs, estimated by 2030 (assuming that a plant expansion is complete), approximate cost $6,300,000;
  5. Gnaw Bone, 40 EDUs, estimated by 2036;
  6. Brown County State Park, 32 EDUs, estimated by 2040 (assuming another plant expansion is done around this time).

 

The priority rankings took into account technical and government limitations, financial and environmental impact and public support, the report said.

 

Two other potential expansion projects were evaluated, but did not score high enough to get a spot on the priority list. Those were about 22 homes in the Jackson Branch area and about 50 homes in the Belmont area, which was considered to be roughly between Kelley Hill and the county line.

 

“While all of these extensions are possible, there are a number of them which are not feasible for the town to commit to,” the report says.

 

Currently, Gnaw Bone has its own wastewater treatment plant and a board that governs it.

 

The Brown County Regional Sewer District Board has been trying to build a plant to serve Bean Blossom.

 

For the town to take on those two areas as customers, the report says, it’s assumed that the Gnaw Bone plant would close due to increased pressure for regionalization; and that the Brown County RSD would choose to send its wastewater not to a new plant it’s planning in Bean Blossom, but to Nashville.

 

If the Bean Blossom-area sewage was routed to town, this line would run down Greasy Creek Road and pick up about 60 EDUs there, the report says. It also says that this option would be the cheapest of any the BCRSD has studied recently.

 

The town taking on more Brown County State Park wastewater would be a state-led decision and at the state’s cost, the report says. The park does have one wastewater treatment permit and plant, but the town currently processes the vast majority of the park’s wastewater.

 

Everything in this report is preliminary until the council votes on it, and is not guaranteed to happen until the town is able to find funding to do any of these projects.

 

The July 16 meeting starts at 6:30 p.m. The Zoom link and meeting agenda will be posted at townofnashville.org under the “town council” tab and on the Brown County Democrat’s Facebook page the night of the meeting.

 

Originally posted: The Times Post