← Back to the list of projects

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

2.94 -C- What would the estimated flow rate be, to the Storm Sewer system, during PEAK FLOW periods, for one Target Neighborhood, such as Orchard Hills, if ALL of the homes were equipped with water siphon back up systems?

Posted by Lori Byron on 22 Dec, 2013
Category: Category 2 - about potential recommendations

Frank Burdick’s Log Number: 70
Submitted by: Burdick log
Category (1,2,3): 2
Status: Closed
Estimated date to address: N/A

Q. The domestic water siphon "back up" system for sump pumps is more reliable than a 12 volt battery back-up system.  The City's website states the following: (This system)"Uses about 2 gallons of pressurized fresh water to pump out 1 gallon of sump water. Water usage will show up on the water bill."  What would the estimated flow rate be, to the Storm Sewer system, during PEAK FLOW periods, for one Target Neighborhood, such as Orchard Hills, if ALL of the  ("99% of homes in this Target Area are equipped with FDDs per OHM") WERE equipped with water siphon back up systems?  What would be impact to the Peak Flow rates to the Storm Sewer systems to the Morehead and Churchill areas?  Can the City justify the "sustainability" impact of using this quantity of domestic water for the purposes of satisfying the goals of the FDD program? 
 
[OHM Advisors, emails between Frank Burdick and Robert Czachorski] A. The 2 to 1 computation is a relatively easy computation to make, but that condition only occurs in the rare condition of the failure of the sump pump. I can think of two primary failure modes of a sump pump: 1) when the pump itself burns out, and 2) power failure. Presumably in condition 1 - sump pump failure, the impacts on the storm system would be negligible, as it is not likely that very many would occur simultaneously. In condition 2 - power failure, the impact on the storm system would depend on the extent and frequency of power failures. It is this piece that is not so easy to quantify with our current information in hand. Perhaps the survey might help us understand this piece, by examining the answers to the questions about water in basement. I would suggest that we wait for those results before commenting further.

There are no comments.