NC0026051_Authorization to Construct_19910829

State of North Carolina
Department of Environment, Health and Natural Resources
Division of Environmental Management
512 North Salisbury Street • Raleigh, North Carolina 27611
James G. Martin, Govemor George T. Everett, Ph.D
William W. Cobey, Jr., Secretary Director
August 29, 1991
Mr. Tom R. Frisher, Project Engineer
Triangle Wastewater Treatment Plant
County of Durham
120 E. Parrish Street
Law Building
Suite 100
Durham, NC 27701
Subject: Permit No. NC0026051
Authorization to Construct
Triangle Wastewater Treatment Plant
Durham County
Dear Mr. Frisher:
A letter of request for an Authorization to Construct was received April 15, 1991 by the 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 partitions in the 12 million gallon polishing lagoon,
the raising of the walls of the final clarifiers, the relocation of the point of application of the chlorine
solution to the plant effluent, and all associated piping, valves and appurtenances with discharge of treated
wastewater into Northeast Creek which is classified Class C-NSW waters in the Cape Fear River Basin.
This Authorization to Construct is issued in accordance with Part III paragraph C of NPDES
Permit No. NC0026051 issued July 20, 1990, and shall be subject to revocation unless the wastewater
treatment facilities are constructed in accordance with the conditions and limitations specified in Permit No.
NC0026051.
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 Environmental Management.
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.
Regional Offices
Asheville Fayetteville Mooresville Raleigh Washington Wilmington Winston-Salem
704/251-6208 919/486-1541 704/663-1699 919/733-2314 919/946-6481 919/395-3900 919/896-7007
Pollution Prevention Pays
P.O. Box 29535, Raleigh, North Carolina 27626-0535 Telephone [phone]
An Equal Opportunity Affirmative Action Employer

The Raleigh Regional Office, phone no. 919/733-2314, 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 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 Permits and Engineering Unit, P.O. Box 29535, Raleigh, NC
27626-0535.
Upon classification of the facility by the Certification Commission, the Permittee shall employ a
certified wastewater treatment plant operator to be in responsible charge of the wastewater treatment
facilities. The operator must hold a certificate of the type and grade at least equivalent to the classification
assigned to the wastewater treatment facilities by the Certification Commission.
A copy of the approved plans and specifications shall be maintained on file by the Permittee for the
life of the facility.
Failure to abide by the requirements contained in this Authorization to Construct may subject the
Permittee to an enforcement action by the Division of Environmental Management in accordance with
North Carolina General Statute 143-215.6.
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.
The permittee shall provide a final sludge disposal plan within thirty (30) days of receiving this
Authorization to construct.
The permittee shall submit a request for an Authorization to Construct for the earthen berm around
the influent pump station within sixty (60) days of receiving this Authorization to Construct.
GROUNDWATER REQUIREMENTS
1. Within 90 days of permit issuance, three (3) monitor wells, one (1) upgradient and two (2)
downgradient, shall be installed to monitor groundwater quality. The well(s) shall be
constructed such that the water level in the well is never above or below the screened
(open) portion of the well at any time during the year. However, the exact location and
construction details for these wells shall be approved by the Raleigh Regional Office,
from which a well construction permit must be obtained.
2. The monitoring wells shall be sampled initially after construction and thereafter every
February, June, and October for the following parameters:
NO3 (10.0)
TDS (500.0)
pH (6.5 - 8.5 Standard Units)
Chloride (250.0)
Total Suspended Solids
Volatile Organic Compounds - In October only (by Method 1 or Method 2 below).
Method 1: Method 6230D (Capillary - Column), "Standard Methods For The
Examination of Water and Wastewater", 17th ed., 1989.
Ammonia Nitrogen
TOC
Water Level
Fecal Coliforms (1/100m1)
Method 2: Method 502.2 "Methods For The Determination of Organic Compounds
in Drinking Water", U.S. EPA - 600/4-88/039.

The measurement of water level must be made prior to sampling for the remaining
parameters.
The measuring points (top of well casing) of all monitoring wells shall be surveyed to
provide relative elevations of the measuring point for each of the monitoring wells. The
depth of water in each well shall be measured from the surveyed point on the top of the
casing.
The numbers in parentheses represent the maximum allowable concentrations in
groundwater for the various analytical parameters, as specified in 15 NCAC 2L
[Groundwater Classifications and Standards]. Unless otherwise specified, the units for
these concentrations are expressed as milligrams per liter.
If TOC concentrations greater than 10 mg/1 are detected in any downgradient monitoring
well, additional sampling and analysis must be conducted to identify the individual
constituents comprising this TOC concentration. If the TOC concentration as measured in
the background monitor well exceeds 10 mg/1, this concentration will be taken to represent
the naturally occurring TOC concentration. Any exceedances of this naturally occurring
TOC concentration in the downgradient wells shall be subject to the additional sampling
and analysis as described above.
If any volatile organic compounds are detected by method 6230D, or the equivalent method
502.2, then EPA methods 604 and 611 must also be run to detect other organic compounds
which may be present. The results of all analyses specified in the monitoring requirements,
including 604 and 611 if required, must be submitted simultaneously.
The results of the sampling and analysis shall be sent to the N.C. Division of
Environmental Management on Form GW-59 (Compliance Monitoring Report Form) every
March, July, and November.
3. The Compliance Boundary delineated on the attached site map for the disposal system is
specified by regulations in 15A NCAC 2L, Groundwater Classifications and Standards.
An exceedance of Groundwater Quality Standards beyond the Compliance Boundary is
subject to the penalty provisions applicable under General Statute143-215.6(1)a. The sale
of property, by the Permittee, which is within or contiguous to the disposal site, may alter
the location of the Compliance Boundary.
For facilities permitted on or after December 30, 1983, the Compliance Boundary is
established at the lesser of 250 feet from the lagoons, or 50 feet within the property
boundary.
If the title to any property which may affect the location of the Compliance Boundary is
changed, the Permittee shall notify the DEM Director within 14 days. The Director shall
then establish a modified Compliance Boundary which will be done as a modification to the
Permit.
The REVIEW BOUNDARY delineated on the attached site map for the disposal system is
specified by regulations in 15 NCAC 2L, Groundwater Classifications and Standards. A
REVIEW BOUNDARY is established around disposal systems midway between the
Compliance Boundary and the perimeter of the waste disposal area. When the
concentration of any substance equals or exceeds the maximum allowable concentration of
that substance at the REVIEW BOUNDARY, as determined by monitoring, the permittee
shall either (i) demonstrate, through predictive calculations or modeling, that natural site
conditions, facility design and operational controls will prevent a violation of standards at
the Compliance Boundary; or, (ii) submit a plan for the alteration of existing site
conditions, facility design or operational controls that will prevent a violation of standards
at the Compliance Boundary, and implement that plan upon its approval by the Director.

4. The lagoon shall have a liner of natural material at least one foot in thickness at all locations
with a hydraulic conductivity of no greater than 1 x 10 -6 centimeters per second when
compacted. Following installation and inspection of the lagoon liner, and prior to waste
disposal operations, verification of the liner's compliance with hydraulic conductivity and
thickness specifications must be provided to the Division of Environmental Management,
Groundwater Section, by the project engineer.
5. Any additional groundwater quality monitoring, as deemed necessary by the Division, shall
be provided.
One (1) set of approved plans and specifications is being forwarded to you. If you have any
questions or need additional information, please contact Mr. Lindsay L. Mize telephone number 919/733-
5083.
cc: Durham County Health Department
Raleigh Regional Office
Training and Certification Unit
Wilson Engineering Associates, Inc.