NC0085359_Authorization to Construct_20200226

NPDES DOCUMENT SCANNIN`t COVER SHEET
NPDES Permit:
NC0085839
Twelve Mile Creek WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC))
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
February 26, 2020
Thine document is printed ari reuae paper - ignore any
content cm. the resrersce slide

:on ..'ounty Public Works Department
Miie ,'reek WWTP
.o Construct No. 085359A07
.tied Match 31, 2016
Engineer's Certification
RECEIVED
FEB 2 6 2020
NCDEQ/DWR/NPDES
'1 �- ii-n t Cr'L
I, �'a "`' "';`'�•, :v '�' , as a duly registered Professional Engineer in
Mate of North Carolina, having been authorized to observe (periodically/weekly/full time)
:he construction of the modifications and improvements to the Twelve Mile Creek Wastewater
catment Plant, located in Union County, hereby state that, to the best of my abilities, due care
and diligence was used in the observation of the following construction:
Installation of two (2) new 12 MGD peak flow mechanical rake screens with wash and
],Tess compactor systems replacing the mechanical screen system, piping, and controls;
installation of new 48 in gravity main between screening basin and effluent pump station;
installation of new 30 in force main from influent pump station to treatment facility;
demolition of grit removal system and FAO distribution box; installation of new grit
removal system consisting of two (2) 20 MGD peak flow vortex grit collectors with grit
rumps, grit wash systems, grit conveyors, sump pumps, odor control system, piping, and
::; nirols; installation of new aeration basins distribution structure with two (2) vertical
,= :ers. piping, and controls; installation of new fine bubble diffuser array in aeration tanks
1 : i acing the mechanical aeration system, piping, and control; installation of three (3) new
...ration System blowers, two (2) 6,067 CFM and one (1) 9,050 CFM, piping, and controls;
•;..inc,iition of UV disinfection system and cascade aerator; installation of new UV
•cction system consisting of dual channels with each channel containing 3 banks (2
i.y, 1 redundant) and with each channel rated disinfection capacity at peak flow 22.5
•G), piping, and controls; installation of one (1) new 200 GPM at 200 ft TDH EFW
•'c;mp, piping, and controls; installation of one (1) inline pressure UV disinfection system
aged for 400 GPM, piping, and controls; installation of new 11,320 gallon post cascade
aeraion basin, piping, and controls; installation of new jet -mix systems using existing air
,uppiy. and circulation flow replacing coarse bubble mix system in digesters 3 & 4, piping,
LiAd controls; installation of four (4) new 9,000 GPM at 24 fl TDH jet circulation pumps,
; Pirig, and controls; demolition of gravity belt thickener system; installation of two (2)
new gravity belt thickener systems each system consisting of a grinder, polymer
injection/mixing, 633.3 dry lb/hr gravity belt thickener with VFD, 150 GPM at 138.6 ft
DJ-1 t:,iLir.ened sludge pump with VFD, wash water booster pump, piping, and controls;
(1 of two (2) new sludge dewatering belt press systems each consisting of a
200 GPM at 138.6 fi TDII belt filter press .feed pump with VFD, polymer
'mixing, 429.2 dry lb/hr dewatering belt filter press with VFD, wash water booster
piping, and controls; filter belt press solids load out conveyor; installation of
tbic ken'�r polymer storage and feed system in solidshandling building 'storage containment
area tons?sting ; �F :1) closed top 2,550 .gallon storage tank, one (1) 10 GPM at 69.3 ft
TDI ! nixing pun;t;. , \vo (2) 3 GPH GPM at 100 psig TDH feed pumps, piping, and
Clr.Ii?10 S: i nstallation ; dewatering polymer storage and feed system in solids handling
build..tg, Stoiage containment area consisting of one (1) closed. top 2,550 gallon storage
tank, ,r : ()) .! 0 GPM at 69.3 fi TDH mixing pump, two (2) 10 GPH at 100 psig TDH feed
prl,r�� and controls; installation of one (1) 1,000 KW, 480 VAC, 3 PH standby

Engineer's Certification
A to C No. 085359A07
Page 2 of 2
diesel generator (new aeration blowers); in conformity with the project plans,
specifications, and other supporting data subsequently filed and approved by the
Department of Environmental Quality.
This authorization results in an approved increase in design and permitted capacity to 7.5
MGD provided A to C No. 085359A06 has also been completed.
I certify that the construction of the above referenced project was observed to be built within
substantial compliance, intent and in conformity with all applicable regulations and statutes and
the project plans, specifications, and other supporting documentation comprising the
Authorization to Construct Permit Application package.
Signature/f\
Date 2/2f/7..4.7i. Q
Mail this Certification to:.
Registration No. 6 7-3 1 3
Attn: Ron Berry
Complex Permitting Unit
DEQ/DWRIWater Quality Programs
1617 Mail Service Center
Raleigh, NC 27699-1617

Water Resources
ENVIRONMENTAL QUALITY
j° ors pi/
klcou c)
March 31, 2016
Mr. Scott Huneycutt, P.E.
Engineering Division Director
Union County Public Works Department
500 North Main Street, Suite 500
Monroe, North Carolina 28112-4730
Dear Mr. Huneycutt:
PAT MCCRORY
Governor
DONALD R. VAN DER VAART
Secretary
S. JAY ZIMMERMAN
SUBJECT: Authorization to Construct
A to C No. 085359A07
Union County Public Works Department
Twelve Mile Creek WWTP
Director
A letter of request for an Authorization to Construct was received February 11, 2016, by
the Division of Water Resources (Division), and final plans and specifications for the subject
project have been reviewed and found to be satisfactory. Authorization is hereby granted for the
construction of modifications to the existing 6.0 MGD Twelve Mile Creek WWTP, with discharge
of treated wastewater into the Twelve Mile Creek in the Catawba River Basin.
This authorization results in an increase in design and permitted capacity to 7.5 MGD
provided A to C No. 085359A06 was also completed, and is awarded for the construction of the
following specific modifications:
Installation of two (2) new 12 MGD peak flow mechanical rake screens with wash and
press compactor systems replacing the mechanical screen system, piping, and
controls; installation of new 48 in gravity main between screening basin and effluent
pump station; installation of new 30 in force main from influent pump station to
treatment facility; demolition of grit removal system and FAO distribution box;
installation of new grit removal system consisting of two (2) 20 MGD peak flow
vortex grit collectors with grit pumps, grit wash systems, grit conveyors, sump pumps,
odor control system, piping, and controls; installation of new aeration basins
distribution structure with two (2) vertical mixers, piping, and controls; installation of
new fine bubble diffuser array in aeration tanks replacing the mechanical aeration
system, piping, and control; installation of three (3) new aeration system blowers,
two (2) 6,067 CFM and one (1) 9,050 CFM, piping, and controls; demolition of UV
disinfection system and cascade aerator; installation of new UV disinfection system
consisting of dual channels with each channel containing 3 banks (2 duty, 1 redundant)
and with each channel rated disinfection capacity at peak flow 22.5 MGD, piping, and
controls; installation of one (1) new 200 GPM at 200 ft TDH EFW pump, piping, and
controls; installation of one (1) inline pressure UV disinfection system rated for 400
GPM, piping, and controls; installation of new 11,320 gallon post cascade aeration
State of North Carolina I Environmental Quality I Water Resources
1617 Mail service Center I Raleigh, North Carolina 27699-1617
Location: 512 N. Salisbury St. Raleigh, North Carolina 27604, Archdale Building 9th Floor
Phone: [phone] / Fax: [phone]

Mr. Scott Huneycutt, P.E., Engineer Division Director
March 31, 2016
Page 2 of 4
basin, piping, and controls; installation of new jet -mix systems using existing air
supply and circulation flow replacing coarse bubble mix system in digesters 3 & 4,
piping, and controls; installation of four (4) new 9,000 GPM at 24 ft TDH jet
circulation pumps, piping, and controls; demolition of gravity belt thickener system;
installation of two (2) new gravity belt thickener systems each system consisting of a
grinder, polymer injection/mixing, 633.3 dry lb/hr gravity belt thickener with VFD,
150 GPM at 138.6 ft TDH thickened sludge pump with VFD, wash water booster
pump, piping, and controls; installation of two (2) new sludge dewatering belt press
systems each consisting of a grinder, 200 GPM at 138.6 ft TDH belt filter press feed
pump with VFD, polymer injection/mixing, 429.2 dry lb/hr dewatering belt filter press
with VFD, wash water booster pump, piping, and controls; filter belt press solids load
out conveyor; installation of thickener polymer storage and feed system in solids
handling building storage containment area consisting of one (1) closed top 2,550
gallon storage tank, one (1) 10 GPM at 69.3 ft TDH mixing pump, two (2) 3 GPH at
100 psig TDH feed pumps, piping, and controls; installation of dewatering polymer
storage and feed system in solids handling building storage containment area
consisting of one (1) closed top 2,550 gallon storage tank, one (1) 10 GPM at 69.3 ft
TDH mixing pump, two (2) 10 GPH at 100 psig TDH feed pumps, piping, and
controls; installation of one (1) 1,000 KW, 480 VAC, 3 PH standby diesel generator
(new aeration blowers); in conformity with the project plans, specifications, and other
supporting data subsequently filed and approved by the Department of Environmental
Quality.
This Authorization to Construct is issued in accordance with Part III, Paragraph A of
NPDES Permit No. NC0085359 issued effective January 1, 2015, and shall be subject to
revocation unless the wastewater treatment facilities are constructed in accordance with the
conditions and limitations specified in Permit No. NC0085359.
The sludge generated from these treatment facilities must be disposed of in accordance
with G.S. 143-215.1 and in a manner approved by the Division.
In the event that the facilities fail to perform satisfactorily, including the creation of
nuisance conditions, the Permittee shall take immediate corrective action, including those as may
be required by the Division, such as the construction of additional or replacement wastewater
treatment or disposal facilities.
The Mooresville Regional Office, telephone number (704) 663 - 1699, shall be notified at
least forty-eight (48) hours in advance of operation of the installed facilities so that an on site
inspection can be made. Such notification to the regional supervisor shall be made during the
normal office hours from 8:00 a.m. until 5:00 p.m. on Monday through Friday, excluding State
Holidays.
Upon completion of construction and prior to operation of this permitted facility, a
certification must be received from a professional engineer certifying that the permitted facility
has been installed in accordance with the NPDES Permit, this Authorization to Construct and the

t.
Mr: Scott Huneycutt, P.E., Engineer Division Director
March 31, 2016
Page 3 of 4
approved plans and specifications. Mail the Certification to: Division of Water Resources, WQ
Permitting Section — NPDES, 1617 Mail Service Center, Raleigh, NC 27699-1617.
Upon classification of the facility by the Certification Commission, the Permittee shall
employ a certified wastewater treatment plant operator to be in responsible charge (ORC) of the
wastewater treatment facilities. The operator must hold a certificate of the type and grade at least
equivalent to or greater than the classification assigned to the wastewater treatment facilities by
the Certification Commission.
The Permittee must also employ a certified back-up operator of the appropriate type and
grade to comply with the conditions of T15A:8G.0202. The ORC of the facility must visit each
Class I facility at least weekly and each Class II, III and IV . facility at least daily, excluding
weekends and holidays, must properly manage the facility, must document daily operation and
maintenance of the facility, and must comply with all other conditions of T15A:8G.0202.
A copy of the approved plans and specifications shall be maintained on file by the Permittee
for the life of the facility.
During the construction of the proposed additions/modifications, the permittee shall continue to
properly maintain and operate the existing wastewater treatment facilities at all times, and in such
a manner, as necessary to comply with the effluent limits specified in the NPDES Permit.
You are reminded that it is mandatory for the project to be constructed in accordance with
the North Carolina Sedimentation Pollution Control Act, and when applicable, the North Carolina
Dam Safety Act. In addition, the specifications must clearly state what the contractor's
responsibilities shall be in complying with these Acts.
Prior to entering into any contract(s) for construction, the recipient must have obtained all
applicable permits from the State.
Failure to abide by the requirements contained in this Authorization to Construct may
subject the Permittee to an enforcement action by the Division in accordance with North Carolina
General Statute 143-215.6A to 143-215.6C.
The issuance of this Authorization to Construct does not preclude the Permittee from
complying with any and all statutes, rules, regulations, or ordinances which may be imposed by
other government agencies (local, state, and federal) which have jurisdiction.

Mr. Scott Huneycutt, P.E., Engineer Division Director
March 31, 2016
Page 4 of 4
If you have any questions or need additional information, please contact Ron Berry at
telephone number [phone].
Sincere
ai#40,6t--
S. Jay ZMimerman
Director, Division of Water Resources
cc: Michael Parker, P.E.
Hazen and Sawyer
4944 Parkway Plaza Blvd
Suite 375
Charlotte, NC 28217
DWR/Mooresville Regional Office, Water Quality Programs
Central Files
NPDES File
Without Engineer's Certificate attached:
Union County Health Department