Delta College
OP-23: Stormwater Management

Part 1: It is the policy of Delta College to include bid specifications for all construction projects to mitigate the impact of stormwater runoff. The college is guided by the State of MI Department of Management & Budget Major Project Design Manual (DMB-494, R 10/08). The manual considers sustainable site work such as hazardous waste removal, sedimentation and erosion control, green building construction, and permeable paving. Sewage and drainage is addressed to ensure the building ground floor is placed at an elevation that will permit positive surface drainage away from the structure and so no possibility exists for storm water to enter doors or other large openings in case of catch basin or drain stoppage. Sustainable landscaping calls for utilizing tree and shrub stock native or adaptive to site, avoidance of exotic species, monocultures, and invasives, and strategies and designs to reduce reliance on irrigation. Part 2: Delta College is guided by a Campus Master Plan which incorporates strategies that mitigate the runoff impacts of ongoing campus operations. The overall plan reflects the character of the surrounding campus landscape and is designed to take advantage of environmentally friendly concepts to manage storm water drainage. Mimicking a natural hydrologic process, rainwater is conveyed from parking lot bioswale islands into detention ponds. From there, it eventually flows into wet meadows before discharge into the regional drainage system.

A project study showed the clay soil was not porous enough to support this type paving It was determined the cost would not provide sufficient benefit and that is was more advantageous to collect runnoff into the bioswales.

Stormwater detention basins and an adjacent meadow wetland will catch the runoff from the bioswales. Detention basins will eventually flow to the drain system. Native wetland plantings adjacent to the low flow channel on the wetland terraces are designed to be flooded regularly during the growing season to support emergent and wet meadow wetlands. All rainwater will be surface conveyed into parking lot islands and eventually into the detention area. The intention is to slow down and slowly released into the drain overtime. Strategically placed detention systems allow the campus to maintain and improve the level of runoff currently being discharged into the regional drainage system. The design reflects the surrounding landscape character and became integrated as part of the trail system and general campus experience.

Runoff collection begins at the parking lot with bioswales incorporated into the design of the parking areas. Bioswales are a combination of stone and vegetation. They consist of a gently sloped drainage course filled with vegetation designed to remove silt and pollution from surface runoff water. When applied around parking lots where substantial automotive pollution is collected, the bioswale treats the runoff before releasing it to the detention ponds. Rather than flowing from Delta’s parking lots through underground pipes directly into the drain, rainwater is deflected and held in bioswales built into the two south lots and in a large wet meadow between the two lots. They are planted with deep-rooted native vegetation and upland grasses that serve as filters and require little or no mowing. Beds of sand and gravel in the bioswales hold the water, allowing it to percolate instead of rushing into the drain.

Runoff collection begins at the parking lot with bioswales incorporated into the design of the parking areas. Bioswales are a combination of stone and vegetation. They consist of a gently sloped drainage course filled with vegetation designed to remove silt and pollution from surface runoff water. When applied around parking lots where substantial automotive pollution is collected, the bioswale treats the runoff before releasing it to the detention ponds. Rather than flowing from Delta’s parking lots through underground pipes directly into the drain, rainwater is deflected and held in bioswales built into the two south lots and in a large wet meadow between the two lots. They are planted with deep-rooted native vegetation and upland grasses that serve as filters and require little or no mowing. Beds of sand and gravel in the bioswales hold the water, allowing it to percolate instead of rushing into the drain.