NC0028916_Authorization to Construct_20000321

State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor
Bill Holman, Secretary
Kerr T. Stevens, Director
Mr. E. Gray Walls, P.E.
Public Services Director
Town of Troy '
444 North Main Street
Troy, North Carolina 27371
Dear Mr. Walls:
1 � •
NCDENR
NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
March 21, 2000
Subject: Authorization to Construct Permit
Disinfection Units
NPDES Permit NCO028916
Troy WWTP
Montgomery County
A letter of request for an Authorization to Construct (ATC) was received October 18, 1999 by the
Division and final plans and specifications for this project have been reviewed and found to be satisfactory.
Authorization is hereby granted for the addition of new treatment units at the Troy wastewater treatment
plant that discharges into Densons Creek in the Yadkin River Basin. Specifically, this ATC allows the
installation of.
• flow splitter box,
• a new - 4800 ft3 baffled chlorine contact chamber (with drains to existing equalization lagoon),
• a complete ultraviolet disinfection unit with dual modules (designed for a peak flow of 2.5 MGD with
drains to existing equalization lagoon),
• sulfur dioxide feed system for dechlorination (if the chlorine is used for disinfection),
• flow metering structure, and
• all additional piping, valves, control equipment and appurtenances.
The permittee must comply, even during the construction phase, with all limits required by the
NPDES permit. Once construction under this ATC has been completed and an Engineer's Certificate has
been submitted, the permittee is authorized to operate the new treatment units. Although these units are
sized to accommodate a design flow of 1.2 MGD, the current permit allows only a design flow of 0.84 MGD.
An Environmental Assessment must be submitted and a Finding of No Significant Impact (FONSI) issued
before a permit application for 1.2 MGD can be accepted by the Division of Water Quality. Please contact
Gloria Putnam at (919) 733 - 5083, ext. 567 should you have further questions regarding the
Environmental Assessment.
1617 Mail Service Center, Raleigh, North Carolina 27699-1617 919 733-5083, extension 510 (fax) 919 733-0719
An Equal Opportunity Affirmative Action Employer [e-mail]

Mr. Gray Walls, P.E.
Town of Troy
Page 2
As you are aware, ultraviolet (UV) disinfection may sometimes be inhibited by elevated suspended
solids levels, as well as colored wastewater, that interferes with UV light penetration. The Town's
installation of the chlori nation/ dechlorination as a back-up method should provide a means to prevent
fecal coliform limit violations should the aforementioned situations occur.
This Authorization to Construct is issued in accordance with Part III, Paragraph A of NPDES Permit
No. NCO028916 issued March 28, 1994, and shall be subject to revocation unless the wastewater -
treatment facilities are constructed in accordance with the conditions and limitations specified in the
permit.
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 North Carolina Division of Water Quality.
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.
The Fayetteville Regional Office, telephone number (910) 486 - 1541, shall be notified 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 from 8:00
a.m. until 5:00 p.m. on Monday through Friday, excluding State Holidays.
Upon classification of the facility by the Certification Commission, the Permittee shall employ a
certified water pollution control treatment system operator to be in responsible charge (ORC) of the water
pollution control treatment system. The operator must hold a certificate of the type and grade at least
equivalent to or greater than the classification assigned to the water pollution control treatment system 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, .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, and must pr` operly manage and document daily operation and
maintenance of the facility and must comply with .all other conditions outlined in Title 15A, Chapter 8G,
.0204. Once the facility is classified, the Permittee must submit a letter to the Certification Commission
which designates the operator in responsible charge within: (A) Sixty calendar days prior to wastewater
being introduced into a new system or (B) within 120 calendar days of the following, (i) after receiving
notification of a change in the classification of the system requiring the designation of a new ORC and
back-up ORC or (ii) a vacancy in the position of ORC or back-up ORC.
A copy of the approved plans and specifications shall be maintained on file by the Permittee for the
life of the facility.
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.E 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 143-2.15.6A 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.
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 approved plans and
specifications. Mail the Certification to the NPDES Unit, Division of Water Quality, 1617 Mail Service
Center, Raleigh, NC 27699-1617.

r
Mr. Gray Walls, P.E.
Town of Troy
Page 3
One (1) set of approved plans and specifications is being forwarded to you. If you have any
questions or need additional information, please contact Ms. Susan A, Wilson, telephone number (919)
733-5083, extension 510.
cc: Central Files
NPDES Unit, Permit File
Fayetteville Regional Office, Water Quality
Technical Assistance and Certification
Sincerely,
Vz'
rz—
Kerr T. Stevens

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Post-Ir brand fax transmittal memo 7671

Troy, NC UV4000 Budget Quote
6/17199
Quote No.: E1655D
Project Location: Troy, NC
Project Consultant: Central Carolina Engineering
srojan Representat!ve: PETE DUTY & ASSOCIATES,
8720 Fox Chase Lane
Charlotte, NC 28269
USA
Contact Person. Charlie Sims
EFFLUENT STANDARDS GOING INTO THE UV SYSTEM
Peak Design Flow 2 5 US MGD (Fxpandable to 3 US MGD�)
Total Suspended Solids 30 mg/I (30 day average, grab sample)
UV Transmission: 65 %
DISINFECTION GUARANTEED BY UV EQUIPMENT
Page 2
Less than 20C fecal coliform per 1CC ml, based on a 30 day Geometric Klean of consecutive daily
grab samples calcVation basis, for the effluent standards as specified above.
EFFLUENT CHANNEL REQUIREMENTS
1. This proposal is for a UV4000 System to be installed in 1 effuent channel(s), (with 1 reactors per
channel), each channel measuring:
Minimum length required for flow equalization - 31 ft
Width based on number of UV modules - 37 in (tolerance +/-1/8 in (4mm))
Maximum depth required for UV Module access - 72 In
Consult Trojan Engineering Department for overall system layout for multiple channel
systems in order to ensure proper flow distribution for each channel.
2. Effluent wil! be maintained at a minimum depth of 24 in
Consult factory representative for maximum water depths and head requirements.
Dimensions are given for reference only. See submittal drawings for detailed design
purposes.
3. Dimensions as labeled on Drawing No. 4M0028. enclosed:
D =72in
CW = 37 in
L = 31 ft
Dimensions are given for reference only. See submittal drawings for detailed design
purposes.
Copyright @1994 by Trojan Technologies Inc., London, Ontario, Canada. All rights reserved. No part of
this quotation may be reproduced, stored in a retrieval system, or transmitted in any form or by any means
without written permission of Trojan Technologies Inc_

t
Troy, NC UV4000 Budget Quote Page 3
6/17199
EQUIPMENT DESCRIPTIONS
UV REACTORS AND MODULES
Each UV reactor is designed to fit into the specified channel dimensions and to house the UV
Modules. A total of 1 UV reactors are included. The UV Modules are provided complete with UV
lamps, quartz sleeves and self-contained cleaning system. Ali wetted materials are 316 stainless
steel.
SYSTEM CONTROLS
Complete system monitoring and control, including monitoring of lamp current, module status and
flowpacing control. Control enclosures are NEMA 3 equivalent
DETECTION SYSTEM
UV monitor to measure the average UV intensity from a representative UV lamp in each bank of
lamps.
AUTOMATIC LEVEL CONTROLLER
Designed to maintain a minimum water level in each channel to guarantee lamp submergence
through a wide range of flows. All wetted parts are 304 stainless steel and suitable plastics with
counter balance weights.
MODULE REMOVAL MECHANISM
To facilitate removal of the UV Modules from the Reactor Chamber. The Module Removal
Mechanism provides a lifting hoist with module bracket and guide rails for removal of the UV
Modules.
STANDARD SPARE PARTS
UV Lamp Assembly
Quartz Sleeves
OPERATING COST REQUIREMENTS
O & M Costs are based on system flow pacing using a 4-20 mA signal from a flow meter (supplied by
others). These costs are also based on the following assumed values:
- power costs (per kWh): $0.05
disinfection season: 12 months
Estimated Annual O i M Costs: $2423
The above costs include projected annual lamp replacement cost
and annual power costs.
NOTES
1. The preceding information is to be used for budget estimates only, and is valid for one year
from the date shown on page 1.
2. This budget quote excludes any taxes that may be applicable.
Copyright @1994 by Trojan Technologies Inc., London, Ontario, Canada. All rights reserved. No part of
this quotation may be reproduced, stored in a retrieval system, or transmitted in any form or by any means
without written permission of Trojan Technologies Inc.

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Post -It- brand fax transmittal memo 7671

TOWN OF TROY
INCORPORATED 1852
Public Services Dept.
444 N. Main Street
Troy, NC 27371-2799
Phone: [phone]
Fax: [phone]
W rZFR p�p�a
10/13/99
DEHNR
Division of Environmental Management
P.O. Box 29535
Raleigh N.C. 27626-0535
Att: Susan Wilson
REQUEST FOR AUTHORIZATION TO CONSTRUCT AN ULTRA -VIOLET DISINFECTION
SYSTEM AND A CHLORINE CONTACT CHAMBER AT THE EXISTING WASTEWATER
TREATMENT PLANT
NPDES PERMIT NO. NCO028916
The Town of Troy is requesting authorization to construct a new ultra -violet disinfection system and a
new back-up chlorine contact chamber (out of the flood plain) should the UV disinfection system fail to perform
per specifications. It should be noted however, that Troy pilot -tested the UV equipment for approximately four
months several years ago and the equipment did an outstanding job per our test data results. A de -chlorination
system is proposed in conjunction with the new chlorine contact chamber. The UV equipment will be installed
first on a 12- month trial basis. During that time, if the equipment fails to meet or is at all marginal in meeting
permit limits, the equipment will be removed and a new chlorine contact chamber and de -chlorination system will
be installed.
The existing chlorine contact chambers are in the flood plain of Densons Creek. However, the immediate
problem is that one of the chlorine contact chambers is a block structure approximately 30 years old. This
structure is deteriorating rapidly and should a wall cave in, a new structure or the addition of de -chlorination
equipment "within the flood plain area" would be the only two quick fix alternatives. The Town does not believe
that building new structures (chlorine contact chamber or de -chlorination building) within a documented flood
plain area to fix a problem in the short term would be a very wise use of taxpayer money.
Therefore, Troy feels that it would be very prudent to construct a new disinfection system before such a
structural failure occurs and we find ourselves out of compliance with our NPDES permit. The monies are in
place to fund this project. It is critical that Plan & Specification approval be obtained as soon as possible for the
reasons stated above.

Find below the specified operating conditions that were used to design the new UV disinfection system.
DESIGN PARAMETERS:
Plant Average Daily Influent Design Flow
Plant Peak Design Flow
Total Suspended Solids
UV Transmission
EFFLUENT PERFORMANCE CRITERIA:
= 1.20 mgd
= 2.50 mgd (Expandable to 3.0 mgd)
= 30 mg/l (30 day average, grab sample)
= 65%
< 200 fecal coliform per 100 nil, based on a 30 day Geometric Mean of consecutive daily grab samples as basis
of calculation.
One UV4000 System unit installed in one channel
Find below the specified operating conditions that were used to design the new chlorine contact chamber and de -
chlorination system.
DESIGN PARAMETERS:
Plant Average Daily Influent Design Flow = 1.20 mgd
Plant Peak Design Flow = 3.00 mgd
EFFLUENT PERFORMANCE CRITERIA:
Chlorine contact chamber contact time at 1.20 mgd = 43 minutes
Chlorine contact chamber contact time at 3.00 mgd = 17 minutes
Find enclosed calculation documentation for numbers presented above. Also find enclosed 3- sets of Plans &
Specifications for the proposed modifications.
Please advise if there are any questions or any further information that may be required at your earliest possible
convenience so that we may resolve these issues and proceed with this project.
Sincere ,
e[
E. Gray alls, P.E.
Public Services Director