NC0021474_Other Correspondence_20180411

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April 11,2018 �er�iAPRltti��g
NCDENR/DWR/NPDES Programs
ATTN: Jordan Lake Watershed Coordinator
'1617 Mail Service Center
Raleigh,NC 27699-1617
RE: NPDES Permit No.NC0021474-Mebane WWTP
Facility Class IV
Alamance County
The City of Mebane's NPDES Permit No.NC0021474 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 fourth annual milestone— "Submit a
nutrient removal optimization report to DWR for the Mebane WWTP "
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 pemntted flow of 2 5MGD,the annual mass loadmg 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
DELIVERED TO LAKE
END OF PIPE *Based on 56%Transport Factor
Total Flow TN TN %Below TN* %Below TN
YEAR (NIG/year) (average mg/1) (lbs/year) TN Target _ (lbs/year) Target
2017 488 50 3 55 14,638 63 6 8,197 63 6
2016 487 92 3 33 13,708 65 9 7,675 65 9
2015 478 91 3 93 15,810 60 7 8,853 60 7
2014 458 82 3 77 14,183 64 7 7,942 64 7
2013 467 64 6 49 24,967 37 9 13,982 37.9
2012 407 91 6 38 21,600 46 3 12,096 46 3
2011 398 77 9 20 29,272 27 2 16,392 27 2
2010 398.09 9 01 29,756 26 0 16,663 26 0
2009 408 79 9 77 33,309 17 2 18,653 17 2
CITY OF MEBANE 106 E Washington St I Mebane NC 27302 0 919 563 6141 ("11-'') 919 563 6144 e- www cdvnfinehane corn
www, CITYOFMEBANE. com

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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 mtrogen optimization plan
has resulted in the WWTP discharging TN at an average monthly concentration of 3.78 mg/L at an
average monthly flow of 1 31 MGD(May 2013—March 31,2018), 71%of the aforementioned 5.30
mg/L equivalent average total nitrogen allocation concentration and 52% of the facility's permitted flow,
respectively. Within the most recent 24 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 2018 the facility has discharged
TN at an average monthly concentration of 3 53 mg/L at an average monthly flow of 1 33 MGD, 67%of
the equivalent average total nitrogen allocation concentration and 53%of the facility's permitted flow,
respectively
The City is currently evaluating the WWTP and is working with an engineenng firm 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 m 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 major 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
peinut the individual Association dischargers are subject to aggregate phosphorus limits in lieu of nutnent
limits in our individual NPDES permits. This initial Association permit does not address the discharge of
total mtrogen. 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.
Sincere:/
De ,'is ' •,t€±e
Water Re •urces 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 Varinoski,WWTP Compliance Manager
CITY OF MEBANE 106 F Washineton St I Mebane NC 27302 0 919 561 6141 C,I.fi 919 563 6144 www envofinebane corn
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www. CITYOFMEBANE. com
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