Cost to restore Lake Alice: $5MPublished 10:57am Wednesday, January 23, 2013
The restoration of Lake Alice to its natural state, and keep it that way, would cost up to $5 million, based on a report given to Fergus Falls City Council members Tuesday.
A reduction in the goose population, the report said, also wouldn’t hurt.
The funds would be required to drain the lake, remove the sediment that contains the phosphorus — the chemical causing the lake’s bright-green color — refilling the lake with good-quality water, reconstructing the storm sewer system around the lake, and creating a method of filtering the sediment out of the storm water, according to Chris McConn, speaking on behalf of Interstate Engineering, the city’s consultant for the project,
The council hired Interstate Engineering to study Lake Alice, located three blocks north of downtown Fergus Falls that is a popular site with local residents, based on concerns from residents over the lake’s soupy, green color.
The removal of existing sediment, essentially by draining the lake and excavating the “sludge” on the bottom, is estimated to make up about $1.6 million of the overall cost, McConn said. The sediment that would be removed would be transferred to a different site and “entombed” underground permanently.
“If it was deposited by pumping and dredging, it would basically be entombed like a landfill, which would perpetually be there forever.” McConn said. “It’s not a harmful material in that it leaks out and hurts somebody. That sediment is basically what comes off people’s lawns; we’d be putting it back into the soil.”
Before the sediment is removed, however, the storm sewers around the lake, which currently empty into the lake, would be rediverted. Where, however, would depend on which option the council would take, McConn said.
Minnesota Pollution Control Agency officials, McConn said, would not likely approve a plan that would allow storm sewer water containing phosphorus to drain directly into the Otter Tail River. The plan offered two options. The first would be to make the north section of Lake Alice a wetland by building a dike across the lake itself, and then diverting storm water into it.
The plan estimated the cost of creating such a wetland at $300,000. However, physically changing a part of a lake into a wetland would require Legislative approval, which isn’t a guarantee, said Pat Reisnour of Interstate Engineering.
“The argument you can make for filling in a lake is that it can improve the quality of Lake Alice and Otter Tail River,” Reisnour said. “Is that a compelling argument? We don’t know.”
The second option would be to divert the storm sewers to the Otter Tail River, likely to the levee (near the community arena), and then construct concrete grit traps to remove the sediment. The report estimated the cost at about $800,000.
In addition to rediverting storm water, McConn also recommended the city create a program to reduce the waterfowl population around the lake, since his study showed geese contribute up to 30 percent of the phosphorus in Lake Alice, which was significantly more than a previous report that showed waterfowl contributed only minimal amounts of phosphorus.
“Could you explain the significant difference from the previous report, where you stated the impact from the water fowl was minimal, but now it’s 30 percent?” Council member Randy Synstelien asked.
McConn said the newest study used the widely published method of calculation for phosphorus content from geese, and could not speak to the other report. “You can only imagine what that activity is and multiply by how many geese and how long they are there,” he said.
Council member Ben Schierer wondered if the project was something required of the city, or if it is simply optional.
City Engineer Dan Edwards emphasized that Interstate Engineering’s study and proposed plan, paid for by a state grant, provides the council with options should they decide to proceed.
“This was really a voluntary effort…just to find out with the current technology and current understanding what really are the options,” Edwards said. “So when the residents ask ‘what can you do for Lake Alice?’ or ‘why aren’t you doing something?’ the staff will be able to provide the council with the factual information to go back and say…why we are doing this or that.
“This is an informational gathering phase to see if there is a feasible project that can be done.”
Interstate Engineering’s full report can be found on the city’s web site Friday.