NC0046213_Permit Modification_19990222

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State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor
Wayne McDevitt, Secretary
A. Preston Howard, Jr., P.E., Director
February 22, 1999
Mr. C.C. Cook
Marathon Ashland Petroleum, LLC
539 S. Main Street
Findlay, Ohio 45840
Dear Mr. Cook:
NC ENR
NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
Subject: Letter to Require Effluent
Turbidity Monitoring
Permit No. NCO046213
Marathon Ashland
Petroleum
Mecklenburg County
As you are aware, the turbidity monitoring requirement was eliminated from your
permit upon renewal in August 1996. Although turbidity monitoring was eliminated, total
suspended solids (TSS) monitoring with a limit remains in the permit. It was the Division's
contention that should monitoring data indicate TSS problems, the state has the option of
enforcing the instream standard for turbidity. However, the EPA is still concerned with the
removal of the turbidity monitoring requirement from several oil terminal discharge permits.
The following paragraphs address that concern.
During the research phase required for permit development, it was noted that the 14
permits in the Paw Creek area had vastly different requirements for solids measurements.
Permits contained any combination of total suspended solids (TSS), turbidity, and settleable
solids monitoring and/or limits. In an effort to provide consistency, TSS, turbidity, and
settleable solids results from six oil terminals in the Paw Creek area were examined from
July 1994 through September 1995. Results showed that TSS and turbidity exhibited
similar trends. Both pollutants appeared to increase and decrease at the same time. In
addition, for the period examined, there were no turbidity violations, although there were a
few TSS violations. These data resulted in the Division questioning whether monitoring
was necessary for both solids parameters. Was there an added benefit to requiring turbidity
monitoring in addition to TSS monitoring? The Division concluded that turbidity was
correlated with TSS results, and thus, only TSS monitoring with a limit was required. In
addition, North Carolina has a water quality standard for turbidity. Therefore, although
turbidity monitoring is not required in the discharge permits, the State still has the authority
to enforce the instream turbidity standard.
P.O. Box 29535, Raleigh, North Carolina 27626-0535 Telephone [phone] FAX [phone]
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Mr. Cook
February 22, 1999
Page 2
Based on concerns regarding anti -backsliding, the EPA requested the Division re-
examine the basis for the elimination of turbidity monitoring for 12 of the 14 Paw Creek
oil terminals that were required to monitor for turbidity prior to the most recent permit
renewal. This second examination of the data showed that there were turbidity standard
violations since the last analysis at several of the oil terminals. The Division will
investigate the causes of these violations to determine what steps may be necessary to
control solids levels at these sites. Therefore, the Division acknowledges that its second
evaluation resulted in a different outcome from the initial investigation and agrees that
turbidity monitoring should be added to the discharge permits for several of the oil
terminals. This letter serves as the official notice that quarterly turbidity monitoring
will be required at the facility effective March 1,1999. If monitoring data show a
reasonable potential to violate water quality standards, then limits will be imposed upon
renewal.
If you have any questions concerning this change, please contact Bethany Bolt at
[phone], extension 551.
Sincere
i,t _ Preston Howard, Jr., P.E.
cc: Central Files
Mooresville Regional Office, Water Quality Section
NPDES Unit
Point Source Compliance Enforcement Unit