The city of Columbia Heights is home to Silver Lake, located in the Silver Lake TMDL. The state of Minnesota listed the lake as an impaired body of water due to water quality issues. As a result, the city hoped to make significant improvement to the site by redesigning the water quality features and the sanitary lift station, and creating new entrance drives, parking areas and boat launch.
Plans for new stormwater management facilities on the site improve the water quality by cleaning out sediment that has collected in the lake near a stormwater outlet and installing a stormceptor that prevents additional sediment from entering the lake here. Additionally, the dated sanitary lift station and associated generator building on the site were removed and replaced with a new lift station.
We determined that the best water quality treatment plan was a wet pond to provide pre-treatment and an iron-enhanced sand biofiltration basin. The old pond was fenced and overgrown. By incorporating a safety bench, the old fence could be permanently removed, significantly improving the areas aesthetics. We removed several trees infected with emerald ash borer, added native plant species in and around the filtration basin, and added bee houses.
In order to improve the logistics of the current boat launch area, the existing drive and boat launch were removed and replaced with a revised drive alignment, parking lot, and boat ramp with a loading dock to improve safety and the flow of traffic and trailers. The existing situation caused vehicles with trailers difficulties while maneuvering the drive and boat ramp, making accessing the boat launch difficult and unsafe. The new design improves the alignment of the drive and boat ramp by creating more space with use of a retaining wall. The retaining wall will allow for 1 ADA boat trailer stall, 1 ADA vehicle stall, two boat trailer and installs standard parking stalls at the top of the drive.