Dozens of Modale residents joined Mayor James Cox, several City Council members, and Engineer Joe Rueschenberg at the American Legion Hall on Tuesday, Jan. 7, to discuss the Modale sewer lagoon.
Rueschenberg began by explaining the failure of the current lagoons. He dispersed an aerial photo showing the two-cell system and proposed changes.
“The Department of Natural Resources requires at least two foot of separation between the highest groundwater levels and the bottom of the lagoons,” he said. “If it’s less than that, you are supposed to use a synthetic liner.”
Soil borings were taken before the current, failing lagoons were built. At that time, he said, the water table was down, but the coloration of the soil demonstrated a water level higher than the bottom of the lagoon.
“We have come to the conclusion that the problem with those liners failing is that the water table comes up and gets behind the liners, and the soil underneath is sliding in towards the center of the lagoons,” Rueschenberg said.
Previously, the city received a letter from the DNR stating that a fine would be issued for every day the failure goes unaddressed.
“The DNR is going to work with the town as long as they see some progress,” Rueschenberg added.
Modale City Council has considered three options to fix the failing lagoons. One was to reconstruct the lagoons in a new spot, the second was to pump sewage to Missouri Valley, and the last was to raise the current lagoons above the highest water levels, which was the most economical measure.
Still, the project is expected to cost approximately $1.3 million. The city council plans to finance 60 percent of the project through loans and 40 percent with grants.
Depending on the amount of grants, expected from SWIPCO’s Community Development Block Grants and the USDA’s rural development grants, costs would likely increase about $27 a month for each property owner.
If the lagoons were raised four feet, the community would not have to replace the synthetic liner. Instead, an earthen liner could be used to save money, last longer, and preclude future issues, such as the current one.
“As long as there is clay material in the soil, or we could add bentonite clay to the soil to make it less permeable, the DNR allows a certain amount of percolation through the soil,” Rueschenberg added.
The city is currently receiving soil from the Interstate 29 project, though it is mostly sand, according to Rueschenberg.
“We can work with some of that sand to build it up with sand, as long as we cap it off with at least two foot of clay material, it will work,” he said.
Further, the DNR requires that any new lagoons or any improved lagoon system consist of three cells. Modale’s system has two cells.
To address this new requirement, Rueschenberg plans to split the larger cell into two to make the system three-celled.