Having spent much of our lives in close contact with the Detroit River, We have to confess that the notion of blending currently under discussion sounds a little strange. Most of the time, the waters of the Detroit River have good clarity, smell good, and provide an excellent recreational experience for swimmers, boaters, and fishers. However, even moderate rain events can rapidly change our pleasant appearing river into a turbid, grease coated, condom conveyor. It seems like blending is already here!
Ironically, a spokesman for Detroit Water and Sewerage Department appearing at the State of the Straits conference in Windsor, this past December, told the audience that DWSD was able to handle all of its storm water and didn't need to bypass anything into surface waters. We must be imagining it all! But there is more—nearly all of Detroit’s industrial effluents are permitted, after pretreatment, to be discharged into the sanitary sewers. These materials, along with domestic sewage, are routed into surface waters when the system is over capacity and would comprise a significant part of the blend. This raises concerns—who is monitoring the pretreatment? Large quantities of oil have a habit of appearing at some of the Rouge River combined sewer overflows after a rainfall; oil that may not have been detected had it gone through the normal sewage treatment. Would this oil be there if pretreatment had been properly carried out? Even if pretreatment is properly carried out, how will these industrial wastes impact the Detroit River and Great Lakes following blending? The disease organisms, parasites, and nutrient loading of domestic sewage are frightening enough without being accompanied by the myriad of chemicals comprising industrial wastes. We have yet to see anything in the discussions of blending that addresses industrial wastes.
Some sewage plants, including Wayne County, a Detroit River discharger, disinfect their effluents with UV light. How effective is UV light on wastewater that has no or partial primary treatment? Others facilities in the past have used strong doses of chlorine in an attempt to kill the biological components of this effluent overflow before it is dumped into the river, creating large dead zones around these discharges. Will blending increase this problem?
There are many important unanswered questions that the EPA need consider before they give an across the board approval to such a plan. Such a broad reaching policy might have minimal impact in one area, while creating disastrous results in another.
John A. Covert
Friends of the Detroit River