NC0021474_Total Nitrogen Reduction Schedule_20170426

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e6aite
April 26, 2017
NCDENR/DWR/NPDES Programs
ATTN: Jordan Lake Watershed Coordinator
1617 Mail Service Center
Raleigh, NC 27699-1617
RE: NPDES Perrmt No
Facility Class IV
Alamance County
NCO021474 - Mebane WWTP
RECENEDINCDE01DWR
MAY 02Z017
Mater Quality
permitting $KW"
The City of Mebane's NPDES Permit No NCO021474 was renewed effective July 1, 2014. Within the
permit, a Total Nitrogen Reduction Schedule was issued. The schedule contains annual milestones
outlining the steps the City of Mebane will take to comply with the Jordan Lake Wastewater Discharge
Rule (15A NCAC 02B .0270), as modified by North Carolina Session Laws 2011-394 (HB119) and
2013-395 (SB515) With this letter Mebane is submitting the third annual milestone — "Submit a nutrient
reduction plan to DWR for review and approval The plan should project and accommodate anticipated
loadings through 2027 "
Per the Jordan Lake Nutrient Management Strategy, the City of Mebane WWTP is required to comply
with an annual Total Nitrogen (TN) mass loading of 40,225 lbs/year (end of pipe) by the year 2019 (At
the facility's permitted flow of 2 5MGD, the annual mass loading is equivalent to an annual average
effluent concentration of 5.3 mg/L (end of pipe) of total nitrogen ) The City has implemented total
mtrogen-reducing operational changes at the plant and the Mebane WWTP is continually optimizing
operations for total nitrogen removal This is demonstrated in that the City has consistently met the Total
Nitrogen targets of the Jordan Lake Nutrient Management Strategy since 2009 as outlined in the table
below.
YEAR
Total Flow
G/ ear)
END OF PIPE
DELIVERED TO LAKE
*Based on 56% Transport Factor
TN
(average mg/1)
TN
lbs/ ear
% Below
TN Target
TN*
(lbs/year)
% Below TN
Target
2016
48792
3 33
13,708
659
7,675
659
2015
47891
393
15,810
607
8,853
607
2014
45882
377
14,183
647
7,942
647
2013
46764
649
24,967
379
13,982
379
2012
40791
638
21,600
463
12,096
463
2011
39877
920
29,272
27.2
16,392
272
2010
39809
901
29,756
26 0
16,663
260
2009
40879
977
33,309
17 2
----�-J
18,653
172
CITY OF MEBANE 106 E Washcneton St I Mebane NC 27302 Q 919 563 6141 ell& 919 563 6144 D www eavoflnebane coni

We acknowledge that compliance with the TN targets for CY2009-2012 can partially be attributed to
hydraulic under -loading. However, continued implementation of the City's nitrogen optimization plan
has resulted in the WWTP discharging TN at an average monthly concentration of 3 75 mg/L at an
average monthly flow of 1.30 MGD (May 2013 — March 31, 2017), 60% of the aforementioned 5.30
mg/L equivalent average total nitrogen allocation concentration and 71% of the facility's permitted flow,
respectively. Within the most recent 12 months, effluent total nitrogen and flow have trended more
closely due to further optimization of plant operations for nitrogen removal, including automated control
of aerators based on dissolved oxygen From March 2016 through March 2017 the facility has discharged
TN at an average monthly concentration of 3 19 mg/L at an average monthly flow of 1.32 MGD, 53% of
the equivalent average total nitrogen allocation concentration and 60% of the facility's permitted flow,
respectively.
The City is currently evaluating the WWTP to expand the design capacity to 3.0 MGD It is anticipated
that continued employment of optimized operational strategies will result in the facility being in
compliance with the anticipated annual total nitrogen mass loading Per the City of Mebane Long Range
Utility Plan submitted November 1, 2016 by Alley, Williams, Carmen, and King, "At 3 0 MGD, the
facility is projected to meet demand until 2028, when plans for additional expansion will need to be
initiated "
In addition to operational optimization at the WWTP, the City of Mebane and three other mayor municipal
dischargers on the Haw River arm of Jordan Lake — Graham, Greensboro, and Reidsville — have
established the Haw River Nutrient Compliance Association, a 501(c)(3) non-profit corporation. The
Association submitted application for and was issued a group permit for total phosphorus limits effective
January 1, 2017. As allowed by the Jordan Lake Watershed Rule (15A NCAC 02B .270), under this
permit the individual Association dischargers are subject to aggregate phosphorus limits in lieu of nutrient
limits in our individual NPDES permits This initial Association permit does not address the discharge of
total nitrogen However, when TN limits in members' individual permits become effective, the
Association may request modification of the permit to include TN requirements
Thank you for your consideration of this submittal. If you have any questions or should require any
additional information please feel free to contact the undersigned.
Sincerely,
Dennis J. Hodge
Water Resources Director
City of Mebane
CC Rich Gannon, DWR, Jordan Lake Watershed
Mike Templeton, DWR, Environmental Engineer
Julie Grzyb, DWR, Environmental Engineer
David Cheek, City Manager
Chris Rollins, Assistant City Manager
Franz Holt, City Engineer
Amy Varmoski, WWTP Compliance Manager
CITY OF MEBANE 106 E WaslunQton St I Mebane NC 27302 919 563 6141 04 919 563 6144 www cavofinebane coin