Mount Vernon residents learn alternatives, costs for cattle dam repairs

“Cost will be a factor,” he said. “There are costs of construction, and there are costs of annual operating costs. My goal is to get a consensus; I don't expect it to be unanimous.

“I think it's important for the residents to have significant input. I am not going to kick the can down the road. I want to move things along toward a resolution.”

Initially built for agricultural purposes, the dam, over time, has become a key element in managing storm water from surrounding development.

In 2008, due to what Stantec consultant Nick Mueller called “hazard creep,” the Ohio Department of Natural Resources reclassified the dam as a Class 1 dam because of the risk associated with a potential failure stemming from development around the dam.

ODNR inspections in 2008, 2010, 2015, and 2020 document multiple safety violations. Mueller, senior project engineer with Stantec Consulting Services, said that under ODNR standards, the dam must pass 100% for a probable maximum flood.

“As it stands today, it can only pass about 12% of that,” he said. “That means if there is a high flood, the dam likely will fail.”

In 2020 and 2021, the City of Mount Vernon performed interim risk reduction measures (IRRMs) and made some repairs. The remaining deficiencies include a spillway pipe that is too small, a lack of lake drain to control drawdown of the reservoir, and significant maintenance issues.

It also lacks an Emergency Action Plan and dam failure inundation study, neither of which was ever done. Additionally, sediment buildup has reduced the reservoir's storage capacity by about 15%, according to Stantec's report.

After reviewing existing studies and performing additional modeling, Stantec Consulting Services presented four alternatives to the residents:

• #1 Repair and rehabilitate the dam.

• #2 Remove the dam.

• #3A and #3B Lower the height of the dam and incorporate a variety of flood-control measures.

Alternative 1: Construction cost $2.56 million, $36,500 annual maintenance cost, 6-9 months construction period

Alternative 1 corrects the dam's deficiencies and restores it to ODNR Class 1 standards. The lake remains its current size. Highlights of the repairs include:

• Constructing a labyrinth spillway that discharges into a riprap-lined channel downstream, placing a concrete slab downstream of the spillway for energy dissipation, and transitioning the outlet channel to riprap.

• Installing riprap in downstream receiving channel.

• Replacing existing principal spillway pipe with low-level outlet pipe and sluice gate for controlled drainage and regrade existing emergency spillway.

• Investigating, monitoring, and repairing seepage areas; filling low areas and rodent burrows along the dam crest and embankment; removing trees and brush around the principal spillway outlet pipe and cattails in the emergency spillway channel.

This alternative requires regular maintenance and inspections, an operation, maintenance, inspection manual, and an Emergency Action Plan.

Alternative 2: Construction cost $1.39 million, $38,500 annual maintenance cost, 4-6 months construction period

Alternative 2 removes the dam entirely and eliminates ODNR dam safety requirements. Highlights include draining the water, removing the embankment, restoring the stream through the former dam footprint, and constructing new stormwater basins. If residents desire a water feature, there would be space to create these features.

Two dry, in-line stormwater basins would be created upstream for flood storage. These basins will remain dry except during storm events.

Alternative 3A: Construction cost $2.12 million, $34,200 annual maintenance costs, 4-6 months construction period

Alternative 3A involves lowering the dam to less than 6 feet, which removes the dam from ODNR jurisdiction. Highlights include excavating a new, smaller pond to replace the existing lake and constructing two upstream dry, in-line storage basins.

Alternative 3B: Construction cost $1.61 million, $35,700 annual maintenance cost, 4-6 months construction period

Alternative 3B also involves lowering the dam to less than 6 feet. It replaces the existing reservoir with a single dry storage basin and retains the existing small pond upstream.

Alternatives 3A and 3B change the ODNR classification from Class 1 to Class IV. Class IV exempts the dam from ODNR dam safety rules. However, Stantec's report noted that the impoundment would still have the potential to cause damage to downstream structures should an overtopping event occur, with the dam owner potentially liable for those damages.

Mueller noted that the estimated costs are current pricing. Costs might change as plans become more specific and actual construction begins.

The Board of Knox County Commissioners committed $1 million in ARPA (American Rescue Plan Act) money toward whatever dam solution residents choose. Of that $1 million, about $70,000 went toward the cost of the IRRMs the city performed.

Following the presentations, residents asked questions ranging from stormwater management to how building permits were issued. Several residents said they did not know the dam was private property or there was a homeowners association involvement.

Although ownership of the dam and who will ultimately pay for the alternative chosen was not the focus of the meetings, several residents said it was hard to choose an alternative without knowing who would be responsible.

“If you are named a party in the case, you are probably going to be found an owner of the lake and dam. If you have any deed restrictions about maintenance of the lake, that's a good indication you are going to have obligation in the maintenance of the dam,” Wetzel said.

Declining to delve further into ownership or responsibility issues, Wetzel referenced a Jan. 29, 2021, journal entry on the case docket in which he describes ownership, deed restrictions, and ODNR regulations. He also referenced a Jan. 27, 2021, entry that describes the IRRMs.

Comments from several residents who said financial responsibility should be spread among all city residents drew applause. One man said the lake and dam are private property and should be maintained by The Landings subdivision. He said he sees no value in the pond, and it should be maintained only for stormwater management.

The next step is for residents to tell their attorneys which alternative they prefer. Wetzel will schedule an attorney conference in the upcoming weeks for further comment.

To get a copy of the executive summary from Stantec Consulting Services, click here. Scroll down to the bottom of the screen.

To access court records, click here. The case number is 20IN06-0149.