NC0074705_Permit Modification_19890112

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, Governor January 12, 1989 R. Paul Wilms
William W. Cobey, Jr., Secretary Director
Mr. L. G. Hubbard
3500 Parkway Lane, Suite 41.0
Norcross, GA 30092
Subject: Request for Modification or Waiver
of Monitoring Requirements
NPDES Permit No. NC0074705
Conoco, Incorporated
Mecklenburg County
Dear Mr. Hubbard:
In accordance with your request for Permit Modification received December 1,
1988, we are forwarding herewith modification to the subject permit. These
modifications are issued to change the flow monitoring from continuous recording or
weekly flow totalizer to weekly instantaneous. Please find attached a new Effluent
Limitations and Monitoring Requirements page which should be inserted into your
permit. The old page should be discarded. All other terms and conditions contained
in the original. permit remain unchanged and in full effect. These modifications are
issued pursuant to the requirements of North Carolina General Statute 143-215.1 and
the Memorandum of Agreement between North Carolina and the U.S. Environmental
Protection Agency dated December 6, 1983. This permit modification becomes effective
immediately.
If this decision is unacceptable to you, you have the right to an adjudicatory
hearing upon written request within thirty (30) days following receipt of this
letter. This request must be in the form of a written petition, conforming to Chapter
150B of the North Carolina General Stautes, and filed with the Office of
Administrative Hearings, Post- Office Drawer. 11666, Raleigh, North Carolina 27604.
Unless such a demand is made, this decision shall be final and binding.
If you have any questions concerning this permit, please contact Mr. Arthur
Mouberry, at telephone number 919/733-5083.
Sincerely,
� lf
Paul Wilms
cc: Permits and Engineering
Mooresville Regional Supervisor
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer

i
DIVISION OF ENVIRONMENTAL MANAGEMENT
December 14, 1988
MEMORANDUM TO: Arthur Mouberry
FROM: D. Rex Gleason �_6
SUBJECT: Request for Permit Modification
Conoco, Inc.
NPDES Permit No. NC 0074705
Mecklenburg County, North Carolina
This Office has reviewed the subject request and recommends
that it be denied. Regarding the method of flow measurement and
frequency, it is our understanding that the Permit reflects
current.policy for facilities of this size and nature. Further,
this Office would not support the deletion of any parameters
from the Permit based upon the results of one analysis.
If you have questions, please advise.
RGP:se

DIVISION OF ENVIRONMENTAL MANAGEMENT
December 5, 1988
MEMORANDUM
TO: Arthur Mouber
THROUGH: Steve Tedder VOWS & ENbuV�ttc(PiG
FROM: Trevor Clement
SUBJECT: Comments regarding Conoco Permit Objections
NPDES No. NC0074705, Mecklenburg County
I have reviewed the letter from Conoco requesting modification of several
proposed permit requirements. Technical Support did not perform a wasteload
allocation analysis for this discharge. Per our recent conversation, I would
prefer that all "Oil & Petroleum Tank Farm" wasteload allocations be routed
through Technical Services. This will allow for flexibility in assigning toxics
requirements for components such as lead and napthalene, and will allow us to
track whole -effluent toxicity requirements.
With regard to Conoco's comments:
1) Flow measurement: Recommend permit contain requirement such that all Vol-
umes of wastewater leaving the facility are monitored. If continuous monitoring
is not feasible, then discharger should record the approximate times that the
discharge began and ended for all discrete events, along with the instantaneous
flow at the time of effluent sampling.
I think that Conoco has the right idea with their flow estimating technique.
However, since storm -induced flow is likely to be lognormally distributed, sim-
ply averaging two discrete instantaneous flows is likely to result in a biased
estimate. It is recommended that, if estimation is to be used, the facility
collect 3 discrete flows spread throughout the discharge period (e.g. beginning,
middle, near the anticipated end). These 3 flows should be log -transformed
(base 10) and used in a regression analysis. The regression equation can be
used to predict hourly flows which, in turn, can be summed to estimate total
volume discharged. Note that toxics, solids, and turbidity sampling should be
performed during the first flow measurement, and that flow should be reported
with the results for these parameters.
2) Per Division procedure, require sampling for first 5 discre =events and an
annual screen thereafter.
,.4,..`
Please let me know if further clarification
JTC
cc: Rex Gleason
Ken Eagleson
Central File
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