Oakland MI, where I’m running for Water Commissioner, was flooded in August 2014. Cars were sunk in sewage on the highways, and basements were filled with 1 1/2 feet of this same toxic mix. The current commissioner claims this was a 300 year event caused by “global warming,” but the flooding has returned and again on since; most recently September 29th of this year. Even without the basement and road flooding, we flush near raw-sewage into Lake St. Clair every other week, whenever there is more than 1″ or so of rain. While global warming may play a role, I’d suggest a more direct cause: Oakland is the fastest growing county in Michigan. We’ve more and more asphalt surface and no good drain commissioner to know how to handle it. With more asphalt and no change in operation, the same amount of rain sends more water down the small pipes that were appropriate for a more rural Oakland.
Floods are bad enough, but much of Oakland county has a mixed sewer system. When you flush the toilet, your flush goes into the same pipe as the rain water and the industrial waste. As a result, when it rains hard, the pipes overflow with a mix of rainwater, toilet flush, and industrial waste. This all comes up from your toilet and basement drain, and on the roads. The pipe to the Detroit treatment plant is overwhelmed every other week, and while this mix doesn’t reach your basement more than once a year, the mixture flows into the rivers far more often (see here for more details). For the homeowner, I’d suggest two things: elect me drain commissioner, and buy one-way valves to keep the sewage out of your basement (available at Walmart). The valves aren’t a total solution. In any flood likely to send more than 4 inches or so into your basement the product is designed to fail — otherwise your basement floor would cave up. When the valve fails, your basement will be full of mixed sewage. Thus, it would not have helped most people in 2014, but would have helped in 2011 or 2008.
So, what would I do as drain commissioner? One thing I’d like to do is add pumping. It’s not much of a solution but it’s easy to do. Another, longer term solution is to start separating the sewers: sanitary (toilet, etc.) from storm. This can be done somewhat cheaply by diverting the rain water-storm water into small wetlands near our roads, or to French drains beneath parking lots and bicycle lanes. A wetland is different from a dead swamp because there is a flow out and because t’s designed to have oxygen and some wild-life. Designed right, above ground versions would be home to frogs, fish, and turtles. In some locations we would use below-ground versions, French drains or mulch-filled “bio-swales.” Basically, these options are wetlands or ditches filled with stuff (rock, mulch…), often placed beneath a parking lot or rain garden. In my preferred designs, there would be a grate for rain water entry and a perforated pipe distributor below with an outlet to a river. This grate would connect to the pipe to insure that the ditch fills quickly in a rain, and the pipe and outlet would be sized so it would drain slowly — in a day or two.
Drains and swales would be surrounded by barriers to keep carts and cars out. They could be covered with asphalt (parking, walks, or bicycle lanes), or planted with trees and grass (a rain garden). If the drainage inflow were done right all these solutions would protect our homes from floods at low initial cost, while looking really nice. Separating the sewers saves money long-term because we pay for every gallon sent to Detroit’s, poorly run facility. French drain overflow would go to our combined sewers, but this would happen less often than now, and with less-bad consequences. And things would improve as more and more wetlands, swales, and French drains are built.