NCS000338_WW SPECULATIVE LIMITS INFO_20131101

-------STORMWATER-DIVISION-"CODING SHEET--
PERMIT NO.
DOC TYPE
❑ FINAL PERMIT
❑ MONITORING INFO
IX APPLICATION
❑ COMPLIANCE
❑ OTHER
DOC DATE
❑ M i �_01- - --
YYYYM M DD

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NCDENR
North Carolina Department of Environment and. Natural Resources
Division of Water Resources
Pat McCrory Thomas Reeder John E. Skvaria, III
Governor Director Secretary
November 1, 2013
Mr. Jonathan Russell, Town Manager
Town of Elm City
P. O. Box 717
Ehn City, North Carolina 27822
Subject: Speculative Effluent Limits
Proposed Elm City W WTP
Wilson County
Tar Pamlico River Basin
Dear Mr. Russell:
This letter provides speculative effluent Iimits for a 0.150 MGD discharge from a proposed new
wastewater treatment plant for the Town of Elm City. The Division received the speculative
limits request in a letter dated -April 27, 2012: The Town subsequently submitted additional
streamflow information on May 1, 2013, which was required to complete the speculative limit
request. Although the Division is providing speculative limits for wastewater planning
purposes, the Town must recognize that there are several issues that would need to be
addressed if the Town were to pursue an NPDES discharge permit. These issues include the
following:
The NPDES permit application process will require submittal of an engineering
alternatives analysis (EAA). The EAA requires a justification of flow requested, as well
as a thorough evaluation of wastewater discharge alternatives and costs. The Town
currently treats its wastewater via a non -discharge spray irrigation system
(WQ0003405), which is a preferred alternative to an NPDES direct discharge system,
The Town would also need to investigate possible connection to existing wastewater
treatment plants (e.g., Rocky Mount, City of Wilson). A copy of the Division's EAA
Guidance is attached to this letter.
The NPDES application would need to detail the anticipated operations of its
wastewater treatment system, and how the Town would propose to operate a spray
irrigation treatment system in conjunction with a direct discharge treatment system.
Per 15A NCAC 2B.0229(c), Nutrient Offset Payments for non -Tar -Pamlico Basin
Association Members, new wastewater dischargers with permitted flows greater than or
equal to 0.05 MGD, who are not members of the Tar -Pamlico Basin Association, shall be
1617 Mali Senrlce Center, Raleigh, North Cerollne 27699-1617
Location: 512 K Salisbury St, Raleigh, North Carolina 27604
Phone: 91UO7.63001 FAX:919807�6492
Internet M.nL,naterouall�oM
An Equal Opportunly 4 AMrmative Acbn Employer
Aaurally
eCarolina

Mr. Jonathan Russell
November 1, 2013
Page 2 of 4
required to offset their nutrient loads by funding nonpoint source control programs
approved by the Division prior to issuance of their NPDES permit and at each renewal.
Based on the offset cost equation for a new 0.15 MGD discharge, the calculated offset
payment would be $46,357.08 annually. For a new NPDES permit application with a 5-
year permit duration, the full 5-year offset payment of $231,785.40 would need to be
included with the application.
Please recognize that speculative limits may change based on future water quality initiatives,
and it is highly recommended that the applicant verify the speculative limits with the Division's
NPDES Unit prior to any engineering design work,
Receiving Stream. The proposed discharge is to Town Creek, located within the Tar -
Pamlico River Basin. Town Creek has a stream classification of C, with a supplemental
classification of Nutrient Sensitive Waters (NSW). Waters with this classification have a best
usage for. aquatic life propagation and maintenance of biological integrity, wildlife,
secondary recreation and agriculture.
Based on USGS streamflow estimates, the following streamflow statistics for Town Creek
near the proposed discharge location were provided: (1) Annual 7Q10 flow- average 0.05
cfs, but rounded down to zero flow due to multiple instances of zero -flow discharge
measurements at two USGS partial record sites; (2) Winter 7Q10 flow- average 0.1 cfs; (3)
Annual 30Q2 flow- average 0.2 cfs; (4) Average Annual flow- 7.0 cfs. These streamflow
characteristics do not reflect the occurrence of recent droughts, but based on a nearby
continuous -record strearngage, it is likely that 30Q2 flow remains positive.
Town Creek is not listed on the 2012 303(d) list of impaired waterbodies. Based upon a
review of information available from the North Carolina Natural Heritage Program Online
Map Viewer, there are not any Federally Listed threatened or endangered aquatic species
identified within a 5 mile radius of the proposed discharge location.
Speculative Effluent Limits. Based on Division review of receiving stream requirements for
Class C waters (tier 15A NCAC 2B.0211), waters with zero 7Q10 flow but positive 30Q2 flow
(per 15A NCAC 2B.0206), and waters subject to Tar Pamlico Nutrient Sensitive Waters
Management Strategy- (per 15A NCAC 2B.0229), the speculative limits fora proposed 0.15
MGD discharge are presented in Table x. A complete evaluation of these limits and
monitoring requirements for metals and other toxicants, as well as potential instrearn
monitoring requirements, will be addressed upon receipt of a formal NPDES permit
application.
Some features of the speculative limits development include the following:
BOD/DO Limits. Based on zero 7Q10 flow and positive 30Q2 streamflow,
speculative limits are set at BOD = 5 mg/L and DO = 6 mg/L for oxygen -consuming
waste. The resultant limits are considered technologically -feasible.
NH3 Limit.

Mr. Jonathan Russell
November 1, 2013
Page 3 of 4
Ammonia limits are based on protection of ammonia toxicity, using 1 mg/l NH3-N
freshwater aquatic life criteria and zero 7Q10 dilution.
Nutrient Linxuts/Offset Pa):ments. The Tar -Pamlico nutrient management strategy is
based on BAT limits of TN = 6.0 mg/L and TP =1.0 mg/L for domestic dischargers.
The Tar -Pamlico nutrient reduction strategy was implemented in lieu of a TMDL.
As a non-member of the Tar -Pamlico Basin Association, an annual nutrient offset
payment to fund nonpoint source projects is required for discharges > 0.05 MGD
based on the following formula:
Annual Offset Payment = PF x (TN +TP) x 1384 x (BMP, x 1.1) where:
PF = Permitted Flow, MGD
TN = 6 mg/L for domestic facility
TP =1 mg/L for domestic facility
1384 = conversion. factor
BMPc = Best Management Practice cost-effectiveness rate of
$29/kg, per 15A NCAC 2B .0237
1.1 =110% of the cost of nonpoint source controls
Annual Payment = 0.15 x (7) x 1384 x ($29 x 1.1) = $46,357.08
5-Year Payment= $46,357.08 x 5 = $231,785.40
TABLE 1. Speculative Limits for Elm City WWTP
1
h S
„Effluent LlmltatlonS , S '
�'' }iffluent Characte`ristrc " `
Monthly
">
N.
Avera a...
Aver a e
Maicrmum
Flow
0.15 MGD
BODs
5.0 m /L
7.5 m L
NHsasN
1.0m L
3.0m L
Dissolved Oxygen
Not less than 6.0 mg/ L, daily average
TSS
30 m / L
1 45 m / L
H
Not greater than 9.0 S.U. nor less than 6.0 S.U.
TRC
17 u / 1
Fecal coliform
200/100 ml
400/100 ml
(geometric mean
Total Phos horus
1.0 m /L
Total Nitrogen
6.0 m /L
Chronic Toxicity Pass/Fail
90%
(Quarterly test
Engineering Alternatives Analysis (EAA). Please note that the Division cannot guarantee
that an NPDES permit for a new discharge will be issued with these speculative limits.
Final decisions can only be made after the Division receives and evaluates a formal permit
application for the proposed discharge. In accordance with the North Carolina General
Statutes, the practicable wastewater treatment and disposal alternative with the Ieast

Mr. Jonathan Russell
November 1, 2013
Page 4 of 4
adverse impact on the environment is required to be implemented. Therefore, as a
component of all NPDES permit applications for new or expanding flow, a detailed
engineering alternatives analysis (EAA) must be prepared. The EAA must justify requested
flows and provide an analysis of potential wastewater treatment alternatives. A copy of
Division guidance for preparing EAA documents is attached.
Sate Environmental Policy Act (SEPA) EA/EIS Requirements. A SEPA EA/EIS document
must be prepared for all projects that: 1) need a permit, 2) use public money or affect public
lands; and 3) might have a potential to significantly impact the environment. A significant
impact is defined as a new flow or expansion of flow > 500,000 gpd. Since Elm City is not
proposing a flow > 500,000 gpd, this project would not trigger SEPA review.
Should you have any questions about these speculative limits or NPDES permitting
requirements, please feel free to contact Tom Belnick at [phone].
Res o�e��cttfully,
VYY`
Tom Belnick
Supervisor, NPDES Complex Permitting Unit
Attachment: EAA Guidance Document
Hardcopy:
Central Files/NPDES/Wilson County
Electronic Copy:
NC WRC, InIand Fisheries, shannon.deaton®ncwildlife.org
US Fish and Wildlife Service, [e-mail]
DWR/WQP Raleigh Regional Office- Danny Smith
DWR/Basin Planning Brach- Ian McMillan
Mike Myers, Envirohnk
NPDES Speculative Server File

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