NC0043257_Technical Correction_20061212

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NCDENR
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Michael F. Easley, Governor William G. Ross, Jr., Secretary
December 12, 2006 Alan W. Klimek, P.E., Director
Matthew Raynor
Nature Trails Associates
10006 Hammock Bend Road
Chapel Hill, NC 27517
Subject: Letter of Correction
NPDES Permit NCO043257
Nature Trails MHP WWTP
Chatham County
Dear Mr. Raynor:
Staff in the NPDES Program reviewed your permit recently and noticed an error regarding the
effective date of your Total Residual Chlorine (TRC) permit limit. Within the permit's transmittal
letter dated April 3, 2006, it states, "This permit includes a TRC limit that will take effect on
November 1, 2007." Please note this is incorrect. The NPDES permit, through permit condition
A.(5.), correctly implements TRC limits "effective upon the installation of a disinfection
system but no later than June 1, 2006." This letter serves to correct the discrepancy caused by
the April 3, 2006, transmittal letter, and we apologize for any confusion and inconvenience this
error may have caused. No changes to the permit have been made.
If you have not already begun the process to acquire a dechlorination system, you should
immediately do so. Attached for your convenience is information regarding installation of a
dechlorination system and the fast -track dechlorination application form.
If you have any questions concerning the above information, please contact Vanessa Manuel of
the Eastern NPDES Program at [phone], extension 532.
Sincerely,el%
/ vc. v�
.E' r-. Alan W. Klimek, P.E.
Attachments
cc: DWQ/SWP Central Files
DWQ/SWP Raleigh Regional Office / Shannon E. Langley
w1r11 -
1617 Mail Service Center, Raleigh, North Carolina 27699.1617
512 N. Salisbury St., Raleigh, North Carolina 27604 1��One
Phone: [phone] / FAX [phone] / Internet: www ncwatercuaii � NOrthCar011na
An Equal Opportunity/Affirmative Action Employer —50% Recycled/10% Post Consumer Paper Natmfii4

State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
FAST -TRACK APPLICATION
for DECHLORINA TION FACILITIES A UTHORIZA TION TO
CONSTRUCT
THIS FORM MA Y BE PHOTOCOPIED FOR USE AS AN ORIGINAL
INSTRUCTIONS: Indicate that you have included the following list of required application package items by
signing your initials in the space provided next to each item. Failure to submit all required items will lead to return
of the permit application.
A. Application Form - Submit one original and one copy of the completed and appropriately
executed application form. Any changes to this form will result in the application being returned.
The Division of Water Quality (the Division) will only accept application packages that have been
fully completed with all applicable items addressed. You DO NOT need to submit detailed lans ands ecifications at this time. Plans and s ecifications shall be maintained on -site.
B. Certification Form - Submit the completed engineers certification form signed and sealed by a
professional engineer registered in the state of North Carolina.
C. Designated Representative - If the application is being filed by a party other than the owner, a
letter from the owner designating the applicant as his/her authorized representative must be
included.
D. Read, understood, and followed the Dechlorination System Minimum Design Criteria
(adopted 4/18/03 and as subsequently amended).
THE COMPLETED APPLICATION PACKAGE SHOULD BE SENT TO THE FOLLOWING
ADDRESS:
NORTH CAROLINA DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
CONSTRUCTION GRANTS & LOANS SECTION
By U.S. Postal Service: By Courier/Special Delivery:
1633 Mail Service Center 2728 Capital Blvd., Rm.1F-140
Raleigh, North Carolina 27699-1633 Raleigh, North Carolina 27604
Telephone Number: [phone]
For more information, visit our web site at httP://www.nccgl.neV
FORM: DCL 4/2003

Certification
Fast -Track Authorization to Construct for Dechlorination Facilities
Professional Engineer's Certification:
attest that this application for
has been reviewed by me and is accurate,
complete and consistent with. the information in the engineering plans, calculations, and all other supporting
documentation. I further attest that the proposed design has been prepared in accordance with all applicable
regulations and Minimum Design Criteria for Dechlorination Facilities, adopted April 18, 2003. Although certain
portions of this submittal package may have been prepared by other professionals, inclusion of these materials under
my signature and seal signifies that I have reviewed this material and have judged it to be consistent with the
proposed design.
NOTE: In accordance with NC General Statutes 143-215.6A and 143-215.6B, any person who knowingly makes
any false statement, representation, or certification in any application shall be guilty of a Class 2 misdemeanor
which may include a fine not to exceed $10,000 as well as civil penalties up to $25,000 per violation. Furthermore,
failure to design the above referenced facilities in accordance with Minimum Design Criteria for Dechlorination
Facilities and good engineering practice could subject you to disciplinary action by the North Carolina Board for
Professional Engineers and Land Surveyors.
North Carolina Professional Engineer's seal, signature, and date:
Applicant's Certification:
attest that this application for
has been reviewed by me and is accurate
and complete to the best of my knowledge. By signing this certification I, certify that facilities have been designed
in accordance with the Division's Dechlorination System Minimum Design Criteria, and commit to insure
construction proceeds in accordance with said criteria. NOTE: In accordance with NC General Statutes 143-215.6A
and 143-215.6B, any person who knowingly makes any false statement, representation, or certification in any
application shall be guilty of a Class 2 misdemeanor which may include a fine not to exceed $10,000 as well as civil
penalties up to $25,000 per violation.
Signature:
FORM: DCLC 4/2003
Date:

Dechlorination System Minimum Design Criteria
Adopted April 18, 2003
Introduction
The Triennial Review Committee's move to adopt a fresh water standard for total residual
chlorine (TRC) is driving the implementation of TRC effluent limitations for facilities that use
chlorine or a chlorine derivative for disinfection. Such a limit may necessitate the use of a
dechlorinating agent such as sulfur dioxide or a sulfite derivative. The relatively simple nature
of dechlorination affords the Division the opportunity to develop a fast -track permitting
strategy for approval of such systems. The minimum design criteria outlined herein are meant
to provide the regulated community and their engineers the information necessary to ensure
proper system design and rapid project turn -around.
Applicability
This criteria document applies to the design of sulfur dioxide and sulfite derivative systems.
Facilities proposing to employ an alternate means for dechlorination, such as activated carbon,
are required to follow the standard authorization to construct (ATC) permitting process.
Design Criteria
1.0 Dosage Rates
The following dosage rates are to be used for the design of dechlorination systems. These
dosage rates constitute the stoichiometric requirement plus a 10% margin of safety'.
Dechlorinating Agent
Dosing Rate -
Sulfur Dioxide
1.0 m S02 er m 1 C12 removed
Sodium Bisulfite
1.6_mgfL NaHS03 er mgj, Ch removed
Sodium Metabisulfite
1.5 m /L Na2S205er m /L C12 removed
2.0 Duality Requirements
Designs shall include dual feed systems to insure compliance with residual chlorination
limitations in the event the primary (if one is designated) system fails.
' Recommended Standards for Wastewater Facilities; Great Lakes -Upper Mississippi River Board of State
and Provincial Public Health and Environmental Managers; page 100-7,1997 Edition.

Dechlorination System Minimum Design Criteria
3.0 Feed Systems
3.1 Sulfur Dioxide
Gaseous sulfur dioxide feed systems shall employ vacuum pumps and carbon steel or stainless
steel piping. For aqueous solutions, PVC, PE, CPVC, or rubber tubing are acceptable piping
alternatives.
3.2 Sulfite Derivatives
Feed systems for both sodium bisulfite and sodium metabisulfite solutions shall employ
positive displacement pumps and stainless steel piping.
4.0 Mixing
Proper turbulent mixing should be provided such that the dechlorinating agent is completely
mixed within 20 seconds of application. Designs shall provide no less than 30 seconds detention
time for mixing.2
5.0 Chemical Storage
The dechlorinating agent storage area must route solution spills or leakage to a containrnent
area. Chlorine and sulfur dioxide are to be stored separately in well -ventilated areas.
6.0 Effluent Quality
Dechlorination consumes alkalinity and exerts an oxygen demand. As such, proper
consideration must be given to effluent pH and dissolved oxygen to ensure that both
parameters are within acceptable ranges at the point of discharge.
r
2 Recommended Standards for Wastewater Facilities; Great Lakes -Upper Mississippi River Board of State
and Provincial Public Health and Environmental Managers; page 100-8,1997 Edition.
Version 4.18.2003
Page 2 of 2

Re
s&yIft2lents
North Carolina DENR
Division of Water Quality
Point Source Branch
Attn: Vanessa Manual
1617 Mail Service Center
Raleigh, NC 27699
Re: Compliance Issues for Nature Trails WWTP (Chatham County)
- Permit No. NCO043257 --- - - — - -
Dear Ms. Manual,
During the hot days of summer the plant experienced low dissolved
oxygen (D.O.) in our activated sludge basin. This condition began during the
early part of June and persisted through out July causing us to be out of
compliance in several areas of our discharge permit.
We immediately sought a solution to the problem by designing a new
aeration scheme in the treatment basins. This involved transitioning our current
aerating system from course bubble diffusion to fine bubble diffusion. We felt
the change was the best solution without a permit variance and that could be
enacted without disrupting plant operations.
We purchased USFilter "Flexiine' membrane tube diffusers and replaced
all existing course bubble diffusers. Our changes have been very effective. Our
testing in August has been in compliance of all NPDES parameters. I have
enclosed the lab results in this letter.
We apologize for the non-compliance in June and July but our quick
actions have us -back on the track —of confinu- la compliance. If -you would hike any
further detail on our actions please contact me anytime.
k6 0.-
Matthew E. Raynor
Environmental Director
Representative for Nature Trail Associates
Cc: Charles Waklid, Regional Surface Water Branch
10006 Hammock Bend • Chapel Hill, NC 27517 • [phone] • Fax [phone] • E-Mail • [e-mail]