The Kent County Drain Commission has requested an investigation of the redesign of three detention basins along the Silver Creek Drain. The Silver Creek Drain is a large, underground, concrete storm sewer which flows through southern portions of Grand Rapids, and eventually empties into the infamously polluted Plaster Creek. The basins are designed to detain water for an extended period of time during large storm events to control flooding. The ample space in the basins is currently underutilized for smaller storm events. The goal of the team is to make designs that will provide treatment for smaller rain events. We chose this project because all four of us are civil engineers interested in water resources and environmental improvements, and this project will allow us to exercise our interest and knowledge in these areas.
The three detention basins that were evaluated are the Calvin Basin, the Southfield Basin, and the Otsego Basin. The most upstream basin is the Calvin Basin and the existing conditions include a creek with constant base flow through the center of the basin. There are two additional inlets that contribute flow only during storm events. The group proposes creating filtering beds using sand as the filtering media. There will be berms outlining each of the beds in order to contain the water during a storm event. The next basin is the Southfield Basin which is only utilized during very large storm events. The proposed design includes a new inlet at the eastern end that will allow water to flow into a proposed earthen channel during base flow. The final basin being evaluated is the Otsego Basin. The group has determined that it will not be feasible to implement any design changes for this basin.
The Otsego Basin is currently only used as a surcharge storage for the Silver Creek Drain during large rain storm events. A challenge for the redesign of this basin is that the current inlet structure also serves as the outlet structure. The goal for this basin is to divert flows through the basin during smaller rain events, thus retaining water for an extended period of time, allowing for water treatment and utilizing the underutilized space in the basin. Due to the scope of the senior design project and the existence of more feasible redesigns of the Calvin and Southfield basins, alternatives for the redesign of this basin were outlined in the PPFS, however full designs were not constructed at this time.
Similarly to the Otsego Basin, the Southfield Basin is currently only used as a surcharge basin for Silver Creek. The main challenge to the redesign of this basin was that the Silver Creek Drain is located between 2-5 feet lower in elevation than the basin bottom, thus making it difficult to divert water into the basin during smaller rain events. In order to overcome this challenge, the team recommends constructing a new inlet at the easternmost end of the basin where the elevation differences between the basin and the creek are closer. The design also entails a weir structure being implemented inside Silver Creek which would divert baseflows through the basin at all times, thus “daylighting” the creek. A natural trapezoidal channel would be meandered through the basin which would encourage the treatment of stormwater for higher frequency rain events.
Unlike the Otsego and Southfield Basins, the Calvin Basin is an in-line basin which currently “daylights” Silver Creek for a short period through the basin. Three other contributing inlets exist in the basin from the nearby storm sewer networks as well. The challenges with this basin are the close proximity of the water table to the basin bottom and the difficulty of expanding the basin storage through both excavation and outward expansion. The team recommends a design in which a presedimentation basin and infiltration beds are constructed to trap and treat storm events greater than a 1 year storm.
The Kreiser Basin is the most upstream basin of the four basin along the Silver Creek Drain. The Kreiser Basin was recently redesigned by the Kent County Drain Commissioner. The KCDC redesigned this basin with the goal of increasing the detention volume and time thus increasing the water quality. The strategies implemented in the redesign of this basin were kept in mind as they progressed through the redesign of the other basins along the Silver Creek Drain.