mitigating stormwater pollution

Spring thunderstorms have unveiled a new problem related to the paving of White Lake Road and ultimately the 'old-fashioned' stormwater infrastructure that was designed along with it. Despite the fact that this section of the Township is elevated, hilly and geologically coarse-textured (sandy/gravelly), the road was designed in the way that it would have been if it were built in the flat lakeplain of Detroit.

Essentially all the water is collected in catch-basins along the continuously curbed edges of the road, and then piped to designated outlets located at low spots along the road where it is released completely untreated and uncontrolled. So that means that when it rains hard, it releases a lot of water. It also means that anything relatively light that happens to be laying in the road gets washed down the drain and into these "release-zones". Image below shows one of the release zones.



One possible solution to this problem would be to perforate the underground piping that carries this water to the drainage outlets. By punching small holes in the pipes, the water that is travelling through the pipes can trickle through the small perforations and into the local sandy soil, reducing the amount of rainwater that is actually released at the drainage outlets. Because our soil is composed mostly of sand and gravel, it can absorb large amounts of rainwater. This not only reduces the amount of polluted water released at the outlets, but also helps recharge our aquifer and keep invasive plant seeds from being washed into sensitive wetlands and other natural areas where they are harder to control.

There's not much that can be done about it now that the road is complete, however the release-zones can be enhanced to help maximize stormwater treatment before it reaches sensitive wetlands. Our corner lot prairie is one of only a couple release zones along White Lake Road. Prior to this spring, the drainage outlet sent stormwater on a straight path downhill to the hardwood swamp complex south of the site. The result was an unnatural looking ditch that polluted the swamp and adjacent vernal ponds with sediment and garbage. Image below shows a vernal pond that is being influenced by sedimentation pollution from excessive stormwater runoff. Vernal ponds are the primary breeding grounds for amphibians. High-quality vernal ponds (those without pollution) are few and far between.



This spring we spent time re-routing the ditch, hoping to slow the water down so that the sediment and other crap can settle out before the water reaches the swamp. The native prairie/savanna flora will help aid in trapping excessive nutrients and sediment as well. We also planted some white pines that will stabilize the soil with their strong roots and provide screening for the adjacent residence. The image below shows part of the newly re-routed ditch (drainage outlet in background). That dirty looking water is running off a paved road.