NC0024333_Speculative Limits_20210304

City of onro e monroenc.org • 704-282-4601 • PO Box 69, Monroe, NC 281 1 1
Water Resources
February 26 2021 RECP
Mr. Mike Montebello is i `D
Supervisor, NPDES and Pretreatment Units MAR 4 2021
North Carolina Division of Water Resources NCDEQ
1617 Mail Service Center VVR/NPDES
Raleigh, NC 27699-1617
Re: Request for Speculative Limits
City of Monroe WWTP, NPDES Permit No. NC0024333
Dear Mr. Montebello:
The City of Monroe has retained Hazen and Sawyer to assist in an initial planning phase for the City's
Wastewater Treatment Plant (WWTP) expansion. The City is currently permitted to discharge
10.4 million gallons per day (MGD) per National Pollutant Discharge Elimination System (NPDES) permit
NC0024333. The City's proposed capacity expansion will involve an initial expansion to 15.4 MGD, with
a future build-out capacity of 25 MGD. This requires an increase in the permitted capacity of the
NPDES discharge to Richardson Creek.
As part of our planning efforts, we respectfully request an opinion from the Division of Water
Resources (DWR) NPDES Unit regarding effluent limits for the capacity expansions noted above. We
request that DWR provide tiered speculative flow limits for a discharge of 15.4 mgd and a discharge of
25.0 MGD. As discussed during our telephone conversation, the 15.4 MGD limits will replace the 12.5
MGD component of our current permit. I have attached a previous speculative limits letter issues by
NCDEQ. Our flow projections have been refined in working with our regional partner, Union County
Public Works, to result in a lower ultimate WWTP capacity.
We recognize that the proposed effluent limits developed by DWR will be speculative in nature. We
appreciate the time and consideration of DWR regarding this request. Please do not hesitate to contact
me at 704-282-4624 if you should have any questions or need more information.
Sincerely,
Russell Colbath, PE
City of Monroe
Director of Water Resources
cc: James Struve, Hazen and Sawyer

NIA7Z:- Michael F.Easley,Governor
C7 -^ �' State of North Carolina
0/ \C:- Wiliam G.Ross,Jr.,Secretary
Department:of Environment and Natural Resources
01 -1 4- 8 A i 1 :2 U fz( V 0 Coleen Sullins,Director
d�" Division of Water Quality
January 7,2008
Mr.Russell Colbath,P.F.
Director of Water Resources
•
P.U. Box 69
Monroe,North Carolina 28111-0069
Subject: Speculative Effluent Limits
City of Monroe WWTP
NC0024333
Union County
Dear Mr.Colbath: •
This letter is in response to your request for speculative effluent limits for proposed discharges of 28 and
44 MGD for the Monroe WWTP.
•
Receiving Stream. This facility proposes to continue discharge to Richardson Creek,a class C waterbody •
in the Yadkin Pee Dee River Basin. This segment of Richardson Creek is listed on the 2006 303(d)list as
impaired for aquatic life based on'biological integrity',and on the draft 2008 Integrated Report as
impaired for both'biological integrity'and'turbidity'. The sources of these impairments are
undetermined,however non-point sources are typically a significant contributing factor for biological
impairment. Although the impairment does not preclude an expansion at this time,the Division strongly
recommends that the Town of Monroe take steps to mitigate non-point impacts to Richardson Creek in •
order to maintain its viability as a resource. The health of the receiving stream is an important criterion
that DWQ will evaluate when determining whether to allow an increased discharge. During the •
development of these speculative limits,Division staff reviewed several years of instream dissolved.
oxygen data. Historically the values were above 5 nlg/I.,(aquatic life standard) and all values since late
2003 were above 6 mg/I... The Division will continue to review available instream data and,if an
expansion is granted,will likely require extensive additional instream monitoring to verify model
predictions.
S eculative Liimits. Based on available information,speculative effluent limits for the proposed
discharges to Richardson Creek are presented in Table 1. A complete evaluation of these limits and
monitoring requirements fur metals and other toxicants will be addressed upon receipt of a formal
NPDES permit modification request.
TABLE 1. Speculative Limits for the Monroe WWTP(28 MGD and 44 MGD)
'�F fltt ntCliarxtori;tt
I I fflu fluent:Limitations, s ; :
N ort lhiy .AV c r,iae Weekly 1 vt age >.M;
BC)I)5(summer) 5.0 m 'L 7,5 mg/I.
BOD5(winter) 10.0 mgzeL 15.0 mg/L._...___._...._....
NH,3 as N(summer) 1.0 leg/t, 3.0 m /L
NI-13 as N(winter) 2.0 mg/i., 6.0 mg/l.,
( Dissolved Oxygen ._._..._..:>6.(l m /L
Total Residual Chlorine 17-pg/L
( Fecal Coliform 200/100 mt.. ! 400/100 mt........................
Mail Service Center,Raleigh, North Carolina 27699 1617 Telephone[phone] FAX[phone] IsZhCarulina
511 N.Salisbury Street,Raleigh,North Carolina 27604 On the Internet at http://h2o.enr.state.nc.ust ,,'drrturrr/!y
An Equal opportunity,'AHirmative Action Employer

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Monroe WWTP Speculative Limits
Engineering Alternatives Analysis(IAA). Please note that the Division cannot guarantee that an NPDES
permit 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 Town's proposed discharge. hi accordance
with the North Carolina General Statutes,the practicable wastewater treatment and disposal alternative
with the least 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(FAA)must be prepared. The EAA must justify requested flows(based on a 20-year
horizon),and provide an analysis of potential wastewater treatment alternatives. Alternatives to a
surface water discharge,such as spray/drip irrigation,wastewater reuse,or inflow/infiltration
reduction,are considered to be environmentally preferable. A copy of the EAA requirements is attached
to this letter. Permit applications for new or expanding flow will be returned as incomplete if all EAA
requirements are not adequately addressed. If you have any questions regarding these requirements,
please contact the DWQ NPDES Unit at 919-733-5083.
State Environmental Policy Act(SEPA))FA/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. For new wastewater discharges,significant
impact is defined as a proposed discharge of>=500,000 gpd. Since your facility is proposing an
expansion of greater than 500,000 gpd of wastewater,you must prepare a SEPA document that
evaluates the potential for impacting the quality of the environment. The NPDES Unit will not accept
an NPDES permit application for the proposed expansion until.the Division has approved the SEPA
document and sent a Finding of No Significant Impact(FONSI)to the State Clearinghouse for review
and comment. A SEPA Environmental Assessment(EA)should contain a clear justification for the
proposed project. if the SEPA EA demonstrates that the project may result in a significant adverse effect •
on the qualityof the environment,you must.then prepare a SEPA EIS(Environmental Impact Statement).
P p' P
Since your proposed expansion is subject to SEPA,the EAA requirements discussed above will need
to be folded into the SEPA document. The SEPA process will be delayed if all EAA requirements are
not adequately addressed. If you have any questions regarding SEPA EA/EIS requirements,please
contact Hannah Stallings with the DWQ Planning Branch at(919)733-5083,ext. 555.
Should you have any questions about these speculative limits or NPDES permitting requirements,please
feel free to contact Toya Fields at(919)733-5083,extension 551. •
Sincerely,
(410^:'
Susan A.Wilson,P.E.
Supervisor,Western NPDES Program
•
Attachment:EAA Guidance Document
cc:(with Attachment)
Mr.James A.Cramer,P.E. Hazen and Sawyer,P.E.
4011 WestChase 13lve,Ste 500
Raleigh,North Carolina 27607
cc:(without Attachment)
Mooresville Regional Office,Surface Water Protection
Central Files
NPDES Permit File
US FWS,Ecological Services,PO Box 33726, Raleigh,NC 27636-3726 Attn:Sara Myers
NC WRC,Inland Fisheries,1721 Mail Service Center,Raleigh,NC,27699-1721 Attn:Fred Harris
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