NC0055786_Authorization to Construct_20050628

NPDES DOCIMENT :MCANNIN` COVER SHEET
NPDES Permit:
NC0055786
Lexington Regional 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:
June 28, 2005
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Adak
City of Lexington
Lexington Regional WWTP
Permit No. NC0055786
ENGINEER'S CERTIFICATION
FOR
CONSTRUCTION OF WASTEWATER TREATMENT FACILITIES
1, Aft -on ke/M 44.5t.
, am a duly registered Professional Engineer
(please print)
in the State of North Carolina and have been authorized to observe (circle one: full-time, weekly,
periodically) the construction of the subject project for the Permittee:
Project No.: 055786A01
Project: WWTP Upgrade
Location: Lexington Regional WWTP
South of Lexington
Davidson County, North Carolina
The project consists of:
• alterations of the existing activated sludge treatment system to provide biological nutrient removal
(A2/O Process with Secondary Anoxic Zone), including:
• creation of separate anaerobic, anoxic, and aerobic treatment zones;
• addition of internal recirculation pumps and piping;
• addition of variable -frequency drives for recirculation and RAS pumps;
• upgrades of blower and blower piping;
• conversion of aeration systems to fine -bubble aeration; and
• addition of new re -aeration tanks; and
• construction and installation of:
• a new influent screening facility, including mechanical bar screen and Parshall flume;
• a post -aeration facility;
• chemical storage and feed facilities (including those necessary for phosphorus removal);
• a dissolved air floatation (DAF) sludge thickening system;
• a solids contact reactor;
• control/pump building;
• a sludge filtrate pumping facility; and
• all related structures, equipment, piping, controls, and other appurtenances, as presented in the
proposed plans and specifications; and
• abandonment of the existing roughing filters, the filter recirculation pump station, and related
piping and other appurtenances;
as presented in the approved plans and specifications.
I hereby certify that I did regularly observe this project with due care and diligence and that the
construction was completed in substantial conformance with the Authorization to Construct and with the
approved plans and specifications.
Signature
Date 6 G Registration No.
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Upon completion of construction and prior to operation of the modified' cif: /,,'liiePermittee shall provide the Division with a
certification from a professional engineer certifying that the permitted facility has been installed in accordance with the NPDES
Permit, this Authorization to Construct, and the approved plans and specifications.
The Certification should be submitted to:
NCDENR/DWQ, NPDES Unit, 1617 Mail Service Center, Raleigh, North Carolina 27699-1617

State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
Michael F. Easley, Governor
William G. Ross, Jr., Secretary
Alan W. Klimek, P.E., Director
Mr. Roger Spach
City of Lexington
28 West Center Street
Lexington, North Carolina 27292
AVA
NCDENR
June 18, 2003 CON
Subject: Authorization to Construct
ATC No. 055786A01
NPDES Permit No. NC0055786
Lexington Regional WWTP
Davidson County
Dear Mr. Spach:
The Division of Water Quality's NPDES Unit has reviewed the City of Lexington's request for an
Authorization to Construct improvements to provide nutrient removal capabilities at the Lexington
Regional WWTP; and supplemental information provided by Pease & Associates. The Division finds
the proposed improvements and design to be satisfactory and hereby grants authorization for the
following:
• alterations of the existing activated sludge treatment system to provide biological nutrient
removal (A2/O Process with Secondary Anoxic Zone), including:
• creation of separate anaerobic, anoxic, and aerobic treatment zones;
• addition of internal recirculation pumps and piping;
• addition of variable -frequency drives for recirculation and RAS pumps;
• upgrades of blower and blower piping;
• conversion of aeration systems to fine -bubble aeration; and
• addition of new re -aeration tanks; and
• construction and installation of:
• a new influent screening facility, including mechanical bar screen and Parshall flume;
• a post -aeration facility;
• chemical storage and feed facilities (including those necessary for phosphorus removal);
• a dissolved air floatation (DAF) sludge thickening system;
• a solids contact reactor;
• control/pump building;
• a sludge filtrate pumping facility; and
• all related structures, equipment, piping, controls, and other appurtenances; and
• abandonment of the existing roughing filters, the filter recirculation pump station, and
related piping and other appurtenances;
as presented in the proposed plans and specifications.
1617 Mail Service Center, Raleigh, North Carolina 27699-1617 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer On the Internet at http://h2o.enr.state.nc.us/NPDES

ATC No. 055786A01
Lexington Regional WWTP
This Authorization to Construct (ATC) is issued in accordance with Part III, Paragraph A of NPDES
Permit No. NC0055786, issued January 30, 2002, and shall be subject to revocation unless the
wastewater treatment facilities are constructed in accordance with the conditions and limitations
specified in that permit.
Upon completion of construction and submittal of an acceptable Engineer's Certification (see below),
the approved design capacity of the facility will remain at 5.5 MGD, the maximum presently
allowed under the City's NPDES permit.
Proposed Expansion
This Authorization to Construct pertains to the nutrient removal and other process changes
proposed by the City to meet upcoming permit limits. The Division is aware that the City also seeks
to expand the plant's treatment capacity to 6.5 MGD and that it recently received a Finding of No
Significant Impact (FONSI) for the expansion.
The improvements approved in this ATC are already designed to accommodate the increased flows.
The Division considered that in the course of its review, but we cannot approve a design capacity
greater than what the permit authorizes. Thus, this ATC does not grant or imply such an approval.
The Division anticipates that, with the issuance of the FONSI, the City will apply for modification of
its NPDES permit to authorize the planned expansion. Once it drafts that modification, the Division
can consider a request to re -rate the plant's design capacity.
Special Provisions
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 this Division, such as the construction of additional or replacement wastewater treatment or
disposal facilities.
Notification Requirements
The Permittee shall notify the Winston-Salem Regional Office, telephone number [phone], at
least forty-eight (48) hours in advance of operation of the installed facilities, so that an in -place
inspection can be made. Such notification to the regional supervisor shall be made during the
normal office hours of 8:00 a.m. until 5:00 p.m. on Monday through Friday, excluding State
Holidays.
Engineering Certification
Upon completion of construction and prior to operation of the modified facility, the Permittee shall
provide the Division with a certification from a professional engineer registered in North Carolina
certifying that the permitted facility has been installed in accordance with the NPDES Permit, this
Authorization to Construct, and the approved plans and specifications. The certification should be
mailed to the NPDES Unit, 1617 Mail Service Center, Raleigh, North Carolina 27699-1617.
ORC Requirements
The Permittee must continue to employ a certified wastewater treatment plant operator 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 Title
15A, Chapter 8G, .0200. The ORC of the facility must visit each Class I facility at least weekly and

ATC No. 055786A01
Lexington Regional WWTP
each Class II, III, and IV facility at least daily, excluding weekends and holidays; and must properly
manage and document daily operation and maintenance of the facility and comply with all other
conditions of Title 15A, Chapter 8G, .0200.
Additional Conditions
The Operational Agreement between the Permittee and the Environmental Management
Commission is incorporated herein by reference and is a condition of this Permit. Noncompliance
with the terms of the Operational Agreement shall subject the Permittee to all sanctions provided by
G. S. 143-215.6 for violation of or failure to act in accordance with the terms and conditions of this
Permit.
Failure to abide by the requirements contained in this Authorization to Construct may subject the
Permittee to an enforcement action by the Division of Water Quality in accordance with North
Carolina General Statute 143-215.6A to 143-215.6C.
The issuance of this Authorization to Construct does not relieve the Permittee from its responsibility
to comply with any and all statutes, rules, regulations, or ordinances that may be imposed by other
government agencies (local, state, and federal) which have jurisdiction.
The Permittee shall maintain a copy of the approved plans and specifications on file for the life of
the facility.
If you have any questions about this Authorization to Construct, please contact Mike Templeton, at
[phone], extension 541.
Sincerely,
Original Signed by Mike Templeton for
Alan W. Klimek, P.E.
Director
Enclosures: Engineer's Certification Form
Copies: Mr. Steven C. Young (w/ enclosure) - J.N. Pease Associates
P.O. Box 18725
Charlotte, NC 28218
Winston-Salem Regional Office, Water Quality
Technical Assistance and Certification Unit
Central Files
NPDES Unit Files

ATC SUMMARY
City of Lexington
Lexington Regional WWTP
ATC No. 055786A01
Abbotts Creek, Class WS-V and B
Yadkin -Pee Dee River Basin
Davidson County
SCOPE
The City of Lexington proposes to modify its existing 5.5 MGD Lexington Regional WWTP to provide
biological phosphorus removal capability. The improvements are necessary for the City to meet its
phosphorus limit, which becomes effective in April, 2004.
The City is also pursing separate approval to increase the design capacity of the plant to 6.5 MGD. A
FONSI for the expansion was approved by the State Clearinghouse on May 21, 2003. The City can now
apply for modification of its NPDES permit to include the expansion. It will also request re -rating of the
plant to 6.5 MGD.
RECOMMENDATIONS
1. Approve the ATC request, received February 6, 2003.
2. Note in the letter that, while the improvements are designed to also increase the
capacity of the plant to 6.5 MGD, this approval does not authorize an increase in
discharge above the 5.5 MGD currently permitted.
PROTECT DESCRIPTION
The scope of the project includes the following:
• alterations of the existing activated sludge treatment system to provide biological nutrient
removal (A2/O Process with Secondary Anoxic Zone), including:
• creation of separate anaerobic, anoxic, and aerobic treatment zones;
• addition of internal recirculation pumps and piping;
• addition of variable -frequency drives for recirculation and RAS pumps;
• upgrades of blower and blower piping;
• conversion of aeration systems to fine -bubble aeration; and
• addition of new re -aeration tanks; and
• construction and installation of:
• a new influent screening facility, including mechanical bar screen and Parshall flume;
• a post -aeration facility;
• chemical storage and feed facilities (including those necessary for phosphorus removal);
• a dissolved air floatation (DAF) sludge thickening system;
• a solids contact reactor;
• control/pump building;
• a sludge filtrate pumping facility; and
• all related structures, equipment, piping, controls, and other appurtenances; and
• abandonment of the existing roughing filters, the filter recirculation pump station, and related
piping and other appurtenances.
1

ATC Summary (cont.)
City of Lexington
Lexington Regional WWTP
ATC No. 055786A01
The main purpose of the project is to install phosphorus removal capability in order to meet upcoming
permit limits. Changes include an upgrade from coarse -bubble to fine -bubble aeration to improve
aeration efficiency, hence, treatment capacity. The City is also planning to expand the plant to 6.5 MGD
and determined in an earlier study that, with a few exceptions, the existing treatment units and the
plant as a whole already have the necessary capacity. The present ATC proposal includes
improvements to bring the plant up to 6.5 MGD but the City is not requesting re -rating at this time.
- end of summary -
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