NC0081621_Report_20180723

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ENGINEERS
July 23, 2018 1968.019(34)
Ms.Julie Grzyb
NC DEQ/Division of Water Resources
NPDES Complex Permitting Unit
1617 Mail Service Center
Raleigh, NC 27699-1617 RECEIVED/DENRIDWR
Subject: Justification for 1.0 MGD Flow Request JUL 26 2018
NPDES Application NC0081621 Water Resources
Water and Sewer Authority of Cabarrus County Permitting Section
Muddy Creek WWTP
Dear Ms. Grzyb:
As you know, the Water and Sewer Authority of Cabarrus County (WSACC) has recently
submitted a request for additional flow at its Muddy Creek Wastewater Treatment Plant. The
Plant is currently permitted at 0.3 million gallons per day (MGD) and the WSACC Application
requests an increase to 1.0 MGD. This request is supported by the WSACC Master Plan,excerpts
of which were submitted with the NPDES Application.
We received a Request for Additional Information dated June 4, 2018 from Mr. Qais Banihani,
requesting that the flow projections be supported using the methodology outlined in the
Engineering Alternative Analysis (EAA) Guidance Documents. On July 16 we replied to that
Request utilizing population data for the Town of Midland but indicated in our calculation .
narrative that the past 10 years of growth within the Midland area would not be a good
representation of future growth.The population statistical area is too small and growth trends
over the past decade do not reflect the anticipated growth demand resulting from Midland's
proximity to the Charlotte Metropolitan Area. On July 18 I had an opportunity to meet briefly
with Mr. Banihani at which time he advised our response was not sufficient. He suggested I
contact you and provide further justification.
In 2014, WSACC commissioned a Master Plan which contained an extensive analysis of the
growth and flow projections expected in the service area through 2040. In short, this area is
expected to grow more rapidly in the coming years than in the past decade. The anticipated
flow is approximately 1.12 MGD in 2040. WSACC therefore decided to make a request for an
NPDES Permit of 1.0 MGD and to design facilities appropriate for future expansion based on
these projections.
10700 Sikes Place,Suite 115
Charlotte, North Carolina 28277
704.377.9844/NC License F-0114

WIIIISENGINEERS
Ms.Julie Grzyb
July 23, 2018
Page 2 of 2
On behalf of the Water and Sewer Authority of Cabarrus County, we are requesting your
acceptance of the WSACC Master Plan flow projection in lieu of the population-based linear
extrapolation methodology suggested in the EAA Guidance Document. For your reference, I
have attached the first two chapters of the WSACC Master Plan which document the growth
model and flow projection calculations. Upon review, I am sure you will agree this methodology
is far more accurate than a linear extrapolation of census populations.
Please let me know if this is acceptable or if you have additional questions. Thank you for your
consideration.
Yours very truly,
WILLIS ENGINEERS
Charles A. Willis,Jr., P.E., BCEE
Attachments
cc: Water and Sewer Authority of Cabarrus County