NC0025453_speculative limits_20050518

dF W AThy Michael F.Easley,Governor
\0. State of North Carolina
vj 7 William G.Ross,Jr.,Secretary
Department of Environment and Natural Resources
Alan W. Klimek,P.E.,Director
Division of Water Quality
May 18,2005
Mr. Steven Biggs,Manager
Town of Clayton
P.O. Box 879
Clayton,North Carolina 27520
Subject: Speculative Effluent Limits Request
Town of Clayton
NPDES Permit NCO025453
Johnston County
Dear Mr. Biggs:
This letter is in response to your request for speculative effluent limits for the proposed expansions of Clayton's
wastewater treatment plant from 2.5 MGD to 8.0 MGD. We have reviewed the request and provide the following
response.
The speculative limits presented here 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 discharge 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 receives and evaluates a formal permit application for the
Town's proposed discharge.
Environmental Assessments of New Projects
Please be aware that you will have to evaluate this project for environmental impacts before receiving a modified
permit. Anyone proposing to construct new or expanded waste treatment facilities using public funds or public
(state)lands must first prepare an environmental assessment(EA)when wastewater flows(1)equal or exceed 0.5
MGD or (2) exceed one-third of the 7Q10 flow of the receiving stream. 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.
An Environmental Assessment should contain a clear justification for the proposed project. It should provide an
analysis of potential alternatives, including a thorough evaluation of non-discharge alternatives and connection to
a regional treatment system. Nondischarge alternatives or alternatives to expansion, such as spray irrigation,
water conservation, or inflow and infiltration reduction, are considered to be environmentally preferable to a
surface water discharge. In accordance with the North Carolina General Statutes, the preferred alternative must
be the practicable waste treatment and disposal alternative with the least adverse impact on the environment. If
the EA demonstrates that the project may result in a significant adverse effect on the quality of the environment,
you must then prepare an Environmental Impact Statement.
e Carolina
NyNaturally
North Carolina Division of Water Quality 1617 Mail Service Center Raleigh,NC 27699-1617 Phone[phone] Customer Service
Internet: h2o.enr.state.nc.us 512 N.Salisbury St. Raleigh,NC 27604 FAX [phone] 1-877-623-6748
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Ms. Donald B. Rains
Town of Princeton
Page 2
S eculative Effluent Limits
Based on the available information, tentative limits for the Princeton WWTP at the expanded flow of 8.0
MGD are as follows:
SPECULATIVE LIMITS
PARAMETER Menthiy Average Weekly Average Daily Maximum
Flow(MGD) 8.0
BOD, 5-day,20°C 5.0 mg/L 7.5 mg/L
(April 1 -October 31)
BOD, 5-day,20°C 10.0 mg/L 15.0 mg/L
(November.1 -March 31)
Total Suspended Solids 30.0 mg/L 45.0 mg/L
NH3 as N 1.0 mg/L 3.0 mg/L
(April 1.—October 31)
NH3 as N
(November 1—March 31) 2.0 mg/L 6.0 mg/L
Dissolved Oxygen Minimum 6.0 mg/L
pH >6.0 and<9.0 standard units
Fecal Coliform 200/100 nil 400/100 nil
(geometric mean)
Total Residual Chlorine 28 µg/L
TN Load 21,400 (pounds/year)
Total Phosphorus 2.0 mg/L
BOD S -The limits for BOD are water quality based limits to protect the receiving stream.
N_3H -N-The limits for NH3-N are water quality based limits to protect the receiving stream.
TSS -The limits for total suspended solids are standard for secondary treatment of municipal wastewater.
D.O. -The D.O. limit is a water quality based limit to protect the receiving stream.
Fecal Coliform H - The limits for fecal coliform bacteria and pH are derived to protect water quality in the
receiving stream.
Total Residual Chlorine(TRC) Facilities that use chlorine disinfection receive a total chlorine limit to
protect against chlorine toxicity in the receiving stream.
Total Nitrogen— The nitrogen limit represents the Town's annual allocation for total nitrogen, as defined in the
proposed Neuse River Basin Strategy (T15A NCAC 2B.0234). The Strategy also gives dischargers in the basin
the option of forming a group compliance association and working collectively to meet the overall nitrogen
reduction target. The rule waives the individual nitrogen permit limits for any discharger that joins an approved
association. The association then becomes responsible for meeting the collective allocation of its members.
The Town's allocation represents a nitrogen "cap" and does not increase with increasing flows. At the 1.9 MGD
flow previously permitted, the 21,400 lb/yr allocation was equivalent to an average concentration of 3.7 mg/L
TN. The equivalent concentration will decrease to 0.87 mg/L at 8.0 MGD. The Division considers 3 mg/L as the

Ms. Donald B. Rains
Town of Princeton
Page 3
minimum technologically and economically feasible achievable treatment level. Considering that a limit of 0.87
mg/L is not feasible to achieve, the Town must evaluate other options such as pursuing water reuse or other non-
discharge options in order to reduce the amount of nitrogen discharged to the receiving stream. Furthermore, to
increase its nitrogen allocation, the Town can purchase the allocation from existing dischargers or can purchase
the allocation from the Wetlands Restoration Fund, which uses the payment to fund offsetting non-point nutrient
reductions. Payments for the purchase of allocation are set at $22/lb and must be paid for a 30-year period prior
to application for an NPDES permit modification.
Total Phosphorus —In the Neuse River Basin, facilities permitted at or above 0.5 MGD receive a TP limit. For
facilities that are not members of the compliance association the corresponding limit is 1.0 mg/L as a monthly
average.For compliance association members the limit is 2.0 mg/L as a quarterly average.
The limits presented above were based on the information presented in the speculative limits request.A complete
evaluation of these limits and monitoring frequencies in addition to monitoring requirements for metals and other
toxicants will be addressed upon receipt of a formal NPDES permit application.
I trust this response offers sufficient guidance for the Town's proposed treatment plant expansion. If you have
any additional questions about these limits,feel free to contact Teresa Rodriguez at(919) 733-5083 ext.553.
Sinc r ,
Mark McIntire
EAST NPDES Unit Supervisor
cc: Central Files
Raleigh Regional Office
Construction Grants and Loans Section
NPDES Unit
Shankar R. Mistry,Ph.D.,P.E.—The Wooten Company
120 North Boylan Avenue
Raleigh,North Carolina 27603-1423

//0
November 16, 2004 ti�7
THE
W O OT E N Mr. Mark McIntire,P.E. �� NOV 2 2 2004
COMPANY Supervisor, Eastern NPDES Permit Unit
DENR, Division of Water Quality
512 N SalisburySt. DEAR - WATER QUALITY
ROINT SOURCE 3RAN
ENGINEERING CH
Raleigh,NC 27604
P L A N N I N G
A R C H I T E C T U R E Re: Speculative Effluent Limits
Clayton Wastewater Treatment Plant Improvements
NPDES Permit#NCO025453
Johnston County,North Carolina
Dear Mr. McIntire:
The Town of Clayton is planning to expand its wastewater treatment plant
capacity to accommodate the 20 year projected residential, commercial
and industrial growth in the service area. The projected wastewater
treatment plant capacity is 8.00 mgd. Accordingly, on behalf of the Town
it is requested that your office provide Speculative Effluent Limits for 8.0
mgd plant expansion. The discharge location will remain same as included
in the current NPDES permit.
We appreciate your assistance in this matter. Should you have any
questions concerning this matter, please call me at 919-828-0531.
Sincerely
THE WOOTEN COMPANY
a.t N" P . M,b -w
Shankar R. Mistry, Ph.D., P.E
cc: Mr. R Steven Biggs, Manager, Town of Clayton
gg � g
Mr. Tim Simpson, Director of Public Works
Me James Warren, LCWRF Superintendent.
Raleigh Regional Office/Water Quality section
120 North Boylan Avenue
Raleigh NC 27603-1423
919.828.0531
fax [phone]