NC0026441_Correspondence_19950308

NPDES DOCUWEXT SCANNING COVER SHEET
NPDES Permit:
NCO026441
Siler City WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Tr�cr;nearinor Alternatives Ana.lyS1S
lllls 111 lJi 1a1� a
201 Facilities Plan
Instream Assessment (SOC)
--Correspondence
-re: NH3-limits
Permit History
Date Range:
Document Date:
March 8, 1995
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State of North Carolina
Department of Environment,
Health and Natural Resources
Division of Environmental Management
James B. Hunt, Jr., Governor
Jonathan B. Howes, Secretary
A. Preston Howard, Jr., P.E., Director
March 8, 1995
Joel J. Brower
Interim Town Manager
P.O. Box 769
Siler City, NC 27344-0769
Subject: Effluent Ammonia Limits
Town of Siler City WWTP
NPDES Permit No. NCO026441
Chatham County
Dear Mr. Brower:
Reference is made to your request for a relaxation of the ammonia limit in the NPDES v
permit for the Siler City W1:111P from the current (summer) level of 1.0 mg/l to 2.0 mg/i.
We have evaluated your request and would like to provide the following response:
As a matter of procedure, the Division does not generally apply srrnnier ammonia
limits more stringent than 2.0 mg/l, when such limits are warranted to ensure protection
against ammonia toxicity instream. However, the ammonia limit in theSiler City permit
was assigned in order to protect the 5.0 mg/1 state standard for dissolved okygen instream,
as defined in 15A NCAC 2B .0211 (b)(3)(B).
As part of the 1991 wasteload allocation process for the expansion of the Siler City
WWTP to 4.0 MGD, DEM developed a field calibrated QUAL2E model to evaluate the
impact of the effluent on instreann dissolved oxygen concentrations in Loves Creek and the
Rocky River. The _model determined that summer NPDES limits of BOD5 = 5.0 mg/1 and
NH3-N =1.0 mg/1 would be necessary to protect the dissolved -oxygen -standard.
Dissolved oxygen profiles from the modeling analysis showed that the affected area of the
Rocky River is particularly sensitive to oxygen demand caused by loadings of ammonia
and organic nitrogen. Therefore, any relaxation of the Siler City WWTP ammonia limits
would constitute a compromise of water quality standards, and may not be permitted.
If you have any questions please contact Jason -Doll of my staff at [phone].
Sincerely
ve W. Tedder, Chief
Water Quality Section
Raleigh Regional Office
David Goodrich - NPDES Permits Group
Central Files
P.O. Box 29535, Raleigh, North Carolina 27626-0535. Telephone [phone] FAX [phone]
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LEONARDO. BAREFOOT
TOWN MANAGER
J. SAMUEL WILLIAMS
TOWN ATTORNEY
Tafxxn of '$iler Tit-q
POST OFFICE BOX 769 EARL B. FITTS
311 NORTH SECOND AVENUE MAYOR
SILER CITY, NORTH CAROLINA 27344-0769
CHARLES L. TURNER
PHONE: [phone] PROTEM
FAX: [phone]
COMMISSIONERS
HELEN M. BUCKNER
February 1, 1995 WILLIAM F. COLLINS
ALEXANDER GRAVES, JR.
PEMBERTON W. HOBBS
("'1A� Ip V r AM SMITH
R DTHOBERT R
Mr. Preston Howard, P.E.
Director of the Division of Environmental Management
NCDEHNR
Post Office Box 29535
Raleigh, North Carolina 27626-0535
RE: Siler City Ammonia Limit Relaxation
HUA No. SC9205
Dear Mr. Howard:
II6 I� t I 6iv
11�:. 09S
DIV CF RWRONMENTAL ! rit
is,it v i Uf QFRCC
In a recent site inspection by Mr. Ted Cashion of the Raleigh Regional Office of the Division of
Environmental Management, Mr. Cashion explained that the State of North Carolina has a new
policy in which the lowest limit for ammonia that can be given out is 2 mg/L.
As you are aware, the Town of Sffer City has been operating under a 1 mg/L limitation on NH3-
N. The Town of Sffer City is hereby requesting this limitation be raised to the State's lowest
lunit of 2 mg/L. The Town of Sffer City has effectively been meeting its ammonia nitrogen
limitation over the past year. However, we feel it appropriate that our limit be relaxed to meet
the standards of other municipalities.
-Upon receipt and review, -if you should have -questions, please do not hesitate to contact either
Mr. Curtis Brown our Wastewater Treatment Plant Superintendent, or myself..
Sincerely,
TOWN OF SILER CITY
jy0LjL 12wo T
Interim Town Manager
JJB:th J
168 6 1995
Copy: Mayor & Board of Commissioners {
Curtis Brown, WWTPSuperintendent-,F.,..,,,, :,, ,.,WAT; (-R •'­UTY
Steve Cavanaugh, HUA, Winston Salem, NC
WEB 7 19915