NC0024911_Authorization to Construct_20160531

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Metropolitan Sewerage District
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Mr.Ron Berry,Engineer May 31, 2016
Division of Water Resources/Complex Permitting
North Carolina Department of Environmental Quality
512 N.Salisbury Street
1617 Mail Service Center RECEIVEMCDEQIDW
Raleigh,NC 27699-1617 JUN 0 2 2016
Water Quality
Re: Authorization to Construct Application Permitting Section
Metropolitan Sewerage District of Buncombe County
NCO024911
Mr.Berry,
This letter is in response to your May 27,2016 email to Ms.Bailey regarding the above-referenced
application. The Metropolitan Sewerage District of Buncombe County(MSD)takes this matter very
seriously,and believes that you have inappropriately applied peaking factors,by applying a dry
weather peaking factor to the wettest year on record(over 100 years).Under those conditions,
system dynamics are very different,as the maximum hour is 2.0 times the maximum month not 3.0.
In dry weather the peaking factor is higher because the vast collection system is relatively empty and
allows more rainwater in at a greater rate than when it is already half full or more as it was in July of
2013-the wettest month ever on record. To take the flow of one condition and the peaking factor of
another condition is not appropriate engineering judgment,and will have a drastic impact on MSD's
abilities to treat wastewater effectively. This is over and above the fact that the collection system,
cannot hydraulically convey anywhere near that amount of water.Requiring this new screening and
grit facility to handle a firm flow of 120 MGD would drastically increase the size and cost of the
project for entirely inflated and imaginary future flows.
While the current design does meet your additional requirement of providing firm capacity with one
grit treatment unit out of service at 80 MGD,firm capacity for grit treatment is not required by the
NCDEQ,and would not be good engineering judgment for this facility at a higher design flow basis.
Some of the reasons why this should not be required and is not recommended are discussed in the
Basis of Design Report submitted with the Authorization to Construct documentation.Again,this
would drastically increase the size and cost of the project for entirely inflated and imaginary future
flows,while at the same time reducing the performance and effectiveness of treatment at the actual
plant flows.
MSD respectfully requests a meeting with you and your supervisor,our Engineer of Record and
representatives of HDR Engineering as soon as possible,as this project is critical. Please respond
with some dates and times that you may be available to speak on these matters.
-Protecting Our Natural Resources-
2028 Riverside Drive,Asheville,North Carolina 28804 Telephone:[phone] Website:w .msdbc.org

Sincerely,
G.
Thomas E.Hartye,P.E.,GeIIMnager
Cc: Tom Belnick,NCDENR
Jeff Poupart,NCDENR
Jay Zimmerman,NCDENR
Landon Davidson,NCDENR Supervisor Regional Operations
Forrest Westall,McGill Associates
Erika Bailey,HDR Engineering
Brian Thorsvold,HDR Engineering
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