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City of Ann Arbor SSWWEP - Citizens Advisory Committee Coordination — City of Ann Arbor

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If Nothing Stood in the Way

Posted by Michelle Lovasz on 22 Feb, 2014
Category: No category

I propose the fantastic.  Just to break off any fences of thinking.  Imagine there were no budgetary constraints (the City of Ann Arbor just won the PowerBall, and dedicated winnings to water management), no irritations or any friction whatsoever to any recommendation (Washtenaw Dairy would not experience any loss of business during any construction).  Imagine everybody is happy with whatever we recommend -- we just have to come up with the best recommendation for future management of Sanitary Sewer.  This fantastical solution is only RIGHT NOW, in this window of opportunity.  In other words, budgetary constraints and other friction would begin again AFTER our recommendation is implemented.

Comments

Michelle Lovasz on 22 Feb, 2014:

I would recommend to separate Sanitary and Storm completely.  The one isolated entirely from the other.  That Storm take care of itself, and Sanitary be sufficient for itself. 

I would recommend that a footing drain disconnect from the sanitary sewers be implemented for each building.  That footing drains be connected - using gravity as much as possible - to a storm water drain-off that flows to the river.  When gravity is not possible, some intermediary pump, hopefully one powered by solar.  Even better, some sort of water wheel, so that the pressure of the volume of the flow "fuels" the pump (will you please invent that Joe C?  I see a business opportunity..)

That each property conform with impervious surface runoff management standards or be fined.  Clay appears to be, in some areas, tending toward impervious surface behavior.  Haven't thought that through yet.  Although, that does seem to be in Troy's Stormwater CAC's concern.

Michelle Lovasz on 26 Feb, 2014:

Robert,
1.  IF all sanitary and storm conduits were completely disconnected, what would likely happen with basement backups?

2.  IF all sanitary and storm conduits were completely disconnected, what would likely happen with sanitary overflows into the river?

3.  Are you aware of ANY municipalities that have a complete separation of of the two?

4.  Outside of single home footing drain disconnects, are you aware of any municipalities that have in any other way reduced the connections between the sanitary and storm conduit-sharing?

Thanks.

Robert Czachorski on 27 Feb, 2014:

Interesting thread of thoughts Michelle.  I think that brainstorming in this manner is great.

One thing I want to clarify is that the City of Ann Arbor currently has separate storm and sanitary sewer systems.  It is a two pipe system, and there are no known cross connections between the two systems.  It such a cross connection is found, it would be removed.  

That being said, even though there are separated systems, it is common for rain water and ground water to leak its way into a separate sanitary system. This is not done intentionally, but it is inevitable that a system of pipes, manholes and service leads from houses buried in the group will form cracks over time and allow water to leak in. City's have operational and maintenance strategies to deal with this, as well as the structural integrity of the pipes and manholes, much like you and I have a processes for maintain our cars and houses.  Obviously, for homes before the building codes changes in the early 80's footing drains were also intentionally connected to the sanitary sewer, which, produces another source of rainwater and groundwater to make its way into the sanitary sewer system.

Many systems around the Country and in Michigan have what we would call "separate sanitary sewers" in this manner, like Ann Arbor, and all of them have some extent of leakage of rainwater and groundwater.  I am aware of several that have aggressive programs of removal of these wet weather flow sources, and for some systems, this is an effective approach for addressing wet weather flow issues.  In the "examples from other communities" package, the manhole rehabilitation performed by Scio Township was quite effective.  Naperville, Il also has a very robust program.  Each system is different and unique in what drives their wet weather flow and what is effective at addressing them. 

So when you say "if all sanitary and storm conduits were completely disconnected" - my first response would be that they are already disconnected.  However, please allow me to rephrase the question:  "If all sources of extraneous rainwater and groundwater were completely removed from the sanitary system, what would happen with basement backups and sewer overflows?"  In that case, by definition in the question, all basement backups of sanitary sewers from wet weather flows would stop, as would all sewer overflows from wet weather flow.  That, however, does not mean that there would never be a backup of sanitary sewage in basements or an overflow ever again.  There are other things that can cause these things, such as a grease ball blockage in the sanitary sewer, a root ball blockage in the sanitary sewer, or a failure of a private house service lead.

I hope this helps!

Take care,
Robert