NC0020354_Speculative limits_20040913

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Michael F. Easley, Governor
State of North Carolina
William G. Ross, Jr., Secretary
Department of Environment and Natural Resources
�Q .0 Alan W. Klimek, P.E., Director
Division of Water Quality
September 13, 2004
Mr. David B. Hughes, P.E.
Town Manager
Town of Pittsboro
1617 Mail Service Center
Pittsboro, North Carolina 27699
Subject: Speculative Limits
Potential Discharge to Haw River
Ref. NPDES Permit�1 C0020354�
Towns of Pittsboro
Chatham County
Dear Mr. Hughes:
This letter is in response to a request for speculative effluent limits for the potential
expansion and relocation of the Pittsboro wastewater treatment plant. Based on the meeting held
between the Town of Pittsboro and various state agencies July 14, 2004, it is the NPDES Unit's
understanding that Pittsboro will review all three locations described in Melba McGee's letter
dated May 27, 2004. This letter will provide Pittsboro with speculative limits for all three
locations. The Town will need to work with the various state and federal agencies, as well as
interested parties, to determine the best location for a point source discharge.
These speculative limits are based on our understanding of the proposal and of present
environmental conditions. The Division of Water Quality (DWQ) cannot guarantee that it will
issue the Town an NPDES permit to expand its discharge of treated wastewater into waters of the
State. Nor can we guarantee that the effluent limitations and other requirements included in any
permit will be exactly as presented here. Final decisions on these matters will be made only after
the Division evaluates a formal permit application for the discharge and notices the proposal for
public comment.
Environmental Assessments of New Projects and Expansions
Any entity proposing to construct new or expanded wastewater treatment facilities using
public funds or public (state) lands must first prepare an environmental assessment (EA) when
wastewater expansions equal or exceed 0.5 MGD. Please contact the Division's State
Environmental Policy Act (SEPA) coordinator, currently Alex Marks, at (919) 733 - 5083, ext. 555
for further information on EA requirements. DWQ will not accept a permit application for a
project requiring an environmental assessment until the Division has approved the EA and sent a
Finding of No Significant Impact (FONSI) to the state Clearinghouse for review and comment. Due
to the public interest in the area, the Town may also wish to investigate the possibility of
proceeding directly to an Environmental Impact Statement (EIS), in lieu of an EA. Again, the
Town may wish to contact Mr. Marks about this possibility (or Ms. Melba McGee, Environmental
Coordinator for DENR, 715-4194).
Engineering Alternatives Analysis MAN
In accordance with the North Carolina General Statutes, the most practicable wastewater
treatment and disposal alternative with the least adverse impact on the environment is required to
be implemented with any expansion. Therefore, a, detailed engineering alternatives analysis (EAA)
must be prepared. The NPDES Unit requires the EAA as part of the Environmental Assessment or
Environmental Impact Statement The EAA must justify requested flows and provide an analysis of
potential wastewater treatment alternatives. -'Alternatives to a surface water discharge, such as a
spray/drip irrigation, wastewater reuse, or inflow/infiltration reduction, are considered to be
environmentally preferable.
North Carolina Division of Water Quality [phone]
1617 Mail Service Center FAX [phone]
Raleigh, North Carolina 27699-1617 On the Internet at http://h2o.enr.state.nc.us/

Mr. Hughes
Page 2
Permit applications for new or expanding flow will be returned as incomplete if all EAA
requirements are not adequately addressed. You may also wish to refer to the NPDES Unit
website for more information regarding requests for expansion,
http://h2o.enr.state.nc.us/NPDES/.
Speculative Effluent Limits
Based on the available information, tentative limits for the proposed discharge of 4 MGD flow to
the Haw River at three locations are outlined below. The three locations reviewed are: (1)
discharge to the Haw River upstream from the recently purchased tract of state property and
below 15-501; (2) discharge into the mainstem of Jordan Lake above Stinking Creek; (3)
discharge to the Haw River near US Highway 64. Also refer to Table 1 for an outline of the
speculative limits. Limits are the same for all three locations.
Flow Limits. The flow would be limited to 4 MGD at your request. This limit would be applied as
-a monthly average.
BODS and Mb -N. The proposed limits for a 4 MGD discharge into this proximity of Jordan Lake
would be 5 mg/1 (BODS) and 1.0 mg/1 (NH3-N) during the summer months, 10 mg/1(BOD5) and
2.0 mg/1 (NH3-N) during the winter months.
Dissolved Oxygen. A minimum daily average dissolved oxygen level of 6 mg/1 must be maintained
in the effluent.
TSS. The limits for total suspended solids are standard for secondary treatment of municipal
wastewater (30 mg/1 monthly average).
Fecal Coliform, pH. The limits for fecal coliform bacteria and pH are derived to protect water
quality in the receiving stream and will likely remain the same as in the previous permit.
Chlorine. A total residual chlorine limit of 28 ug/1(daily maximum) would be implemented in this
permit.
Chronic Toxicity Testing: For the discharge into the Haw River (proper) the 7Q 10s is estimated as
70 cfs. The toxicity testing requirement at 4 MGD will be Chronic Pass/Fail at 8.1% (this will be
applicable to location nos. 1 and 2). Should the Town of Pittsboro determine that discharge to
Lake Jordan is the most feasible option (location no. 3), the facility will be required to comply with
a 24 hour Acute Pass/Fail test using the fathead minnow species.
Toxicant Parameters: Estimation of toxicant parameters will not be given with this speculative
letter, but will be submitted as appropriate with the draft NPDES permit.
Nutrient Parameters: A nutrient model for Jordan Lake was recently developed. Meetings
between Division staff and the stakeholders for Jordan Lake are continuing to take place (with
specific allocations for each discharger not yet determined). We encourage the Town to become an
active participant in the Jordan Lake meetings. At this time, the Division of Water Quality can
provide only estimates of possible individual nutrient limits. For total nitrogen, Pittsboro would
likely receive a mass -based equivalent of 5 - 6 mg/1 TN. For total phosphorus, the Town would
likely receive a mass -based equivalent of 0.5 mg/1 TP.
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Mr. Hughes
Page 3
As stated previously, these speculative limits are appropriate for a discharge of 4 MGD to
the three locations specified previously. If you have any additional questions about these limits,
feel free to contact Ms. Wilson at [phone], extension 510.
Sincerely,
(944ej. 51 5n» 6N
David A. Goodrich, Supervisor
Point Source Branch
Surface Water Protection Section
cc: Raleigh Regional Office/ WQS
Alex Marks, SEPA Coordinator, DWQ
Michelle Woolfolk, TMDL Unit
-Melba-McGee, Environmental Coordinator, DENR
'Central Files
NPDES Unit Files
John Phillips, P.E. Diehl & Phillips, P.A.
219 East Chatham Street
Cary, NC 27511
US Fish and Wildlife Service, Ecological Services
Attn: Sara Myers
P.O. Box 33726
Raleigh, NC 27636-3726
NC WRC, Inland Fisheries Attn: Shari Bryant
1721 Mail Service Center
Raleigh, NC 27699-1721
Carmen Boyette US ACOE
Jordan Lake
2080 Jordan Dam Road
Moncure, NC 27559

Mr. Hughes
Page 4
Table 1
Speculative Limits for the Town of Pittsboro (for flow of 4 MGD)
Scenarios
Site Description
Proposed
BOD5 mg/1
NH3-N mg/l
D.O.
Instream
Flow (MGD)
(sum/win)
(sum/win)
mg/1
waste
concentration
(IWC %)
1
Haw River
upstream from
4.0
5.0/ 10
1.0/2.0
6.0
Chronic P/F at
recently purchased
8.1%
tract and below 15-
501
2
Mainstem of
Jordan Lake above
4.0
5.0/ 10
1.0/2.0
6.0
24 hr Acute
Stinking Creek
P/F
3
Haw River near
Highway 64
4.0
5.0/10
1.0/2.0
6.0
Chronic P/F at
8.1%
Stream flows:
Haw River (Location Nos. 1 and 3), Class WS IV, NSW
DA - 1200 mi2
7Q10s = 70 cfs
7Q l Ow = 140 cfs
Jordan Lake (Location No. 2), WS -IV, B, NSW, CA
7Q10s = indeterminate due to lake conditions
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