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

1.33 -C-Have you considered measuring flow directly on the curb line to determine the flows from FDDs?

Posted by Lori Byron on 20 Dec, 2013
Category: Category 1 - SSWWEP Questions and Presentations

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

Q. Have you considered measuring flow directly on the curb line to determine the flows from FDDs? (the “curb line” is the small PVC pipe that is installed to collect the FDD flow from several houses and connect it to a storm inlet)

A. Subsequent to this comment, we contacted Martin Control Services (MCS), the City’s flow metering contractor, to inquire about metering these connections. The best way to meter the flow from a pipe like this is a direct measurement with a bucket and stop watch during a rain event, because the flow and pipe size are too small for traditional continuous metering. MCS mobilized on the morning of October 31, 2013 during a moderate rainfall event (approximately 1-inch of rain over 12 hours) to make a direct measurement of the flow in a sample curb line in the Orchard Hills subdivision. The curb line they metered collects sump pump flow from 5 houses. MCS also made a measurement of the flow in the 10-inch pipe that was metered during the flow-metering program.  These measurements, and subsequent analysis, show that approximately 66% of the total flow generated (i.e. the total of the flow in the 10-inch sanitary pipe and the footing drain flow in the curb line) is from footing drains.  Additional information on this measurement will be presented at the next CAC.

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