NC0026051_Authorization to Construct_19850814

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RC
State of North Carolina
Department of Natural Resources and Community Development
Division of Environmental Management
512 North Salisbury Street • Raleigh, North Carolina 27611
James G. Martin, Govemor August 14, 1985 R. Paul Wilms
S. Thomas Rhodes, Secretary Director
Mr. John P. Bond, III, County Manager
County of Durham
County Judicial Building
Durham, North Carolina 27701
Subject: Permit No. NC0026051
Authorization to Construct
County of Durham
Durham County Triangle Wastewater
Treatment Plant Expansion
Durham County
Dear Mr. Bond:
In accordance with your letter of July 24, 1985, our review of the
Triangle plant expansion project has been broken into two segments. The
first segment being the biological portion and the second segment being
the phosphorus removal facilities. As we have expressed to you, we feel
that this procedure is not desirable; however, rather than delay the
project we have granted your request.
Our review of the final plans and specifications for the
biological portion has been completed and found to be satisfactory.
Authorization is hereby granted for the construction of a 6.0 MGD
wastewater treatment facility consisting of the following additions and
modifications to the existing 3.0 MGD capacity plant. Please be advised
that this Authorization to Construct does not absolve Durham County of
the violation of North Carolina law for starting construction of these
facilities prior to obtaining an Authorization to Construct.
(1) Installation of a mechanically cleaned bar screen and grit
removal chamber with Parshall flume, flow recorder and
totalizer next to the existing screening and grit removal
equipment.
(2) Modification of the triplex pumps in the existing influent
pump station to increase pumping capacity of each unit to
3,150 GPM and addition of a fourth 3,150 GPM pump.
Pollution Prevention Pays
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Tckphone 919-733-7015

Mr. John P. Bond, III, County Manager
Durham
Page 2
(3) Installation of 16-inch and 20-inch ductile iron force mains
parallel with the existing force main from the influent pump
station.
(4) Construction of a 3.0 MG capacity concrete aeration basin with
four mechanical aerators next to the existing 3.0 MG aeration
basin.
(5) Construction of an 84-ft. diameter clarifier next to the
existing clarifier.
(6) Installation of pumps and piping for sludge recirculation,
sludge wasting and scum removal from the new clarifier.
(7) Construction of dual concrete -lined 12.5 ft. x 88 ft. sand
filter beds with automatic backwash to filter effluent from
the entire plant.
(8) Installation of chlorination equipment to serve the entire
plant with chlorine contact occurring within the sand filters.
_ (9) Addition of a wet well at the filter effluent equipped with a
50 GPM pump to provide washdown water and dual 12 GPM pumps to
supply water for the chlorine injector.
(10) Installation of an on -site generator to provide emergency
stand-by power for the chlorination equipment and filter
backwash pumps; and all other specified piping, valves,
fittings and appurtenances.
This Authorization to Construct is issued in accordance with Part
III paragraph C of NPDES Permit No. NC0026051 issued July 1, 1985, 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.
In the event the facilities fail to perform satisfactorily in
meeting it's NPDES permit effluent limits, the Permittee shall take such
immediate corrective action as may be required by this Division,
including the construction of additional wastewater treatment and
disposal facilities.
Please take notice that the NPDES permit requires phosphorus
removal which is not addressed in this phase of construction. The new
facilities listed herein shall not be operated until plans and
specifications for phosphorus removal are submitted and approved by the
Division and installation completed.

Mr. John P. Bond, III, County Manager
Durham
Page 3
A minimum of three (3) groundwater monitoring wells shall be
located and installed as directed by the Division's Raleigh Regional
Office to monitor the sludge lagoon and the aeration basins. The wells
shall be sampled immediately upon completion and thereafter every March,
July and November for the following parameters: nitrate, total ammonia,
total dissolved solids, total organic carbon, chloride, total coliform,
and water levels. (Note: Water levels in the wells should be measured
prior to bailing or pumping to obtain the water quality samples.)
The sand media of the filters must comply with the Division's sand
specifications and must be analyzed and approved by this Division either
by direct sampling or by acquisition of filter sand from a dealer who is
currently certified by the Division as an acceptable source.
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. Robert Teulings, telephone number 919/733-5083,
extension 121.
Sincerely yours,
R. Paul Wilms
Director
RPW/gwt
cc: Durham County Health Department
Mr, George C. Hoke, P.E.
Mr. Dennis R. Ramsey
Raleigh Regional Supervisor

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Research Triangle Park
North Carolina 27709
LEGEND
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WILSON
ENGINEERING
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Durham [phone]
Raleigh [phone]
Wilmington (9t9) 270-3016
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