NC0004961_Response to Study Plan_19880715

C
State of North Carolina
Department of Natural Resources and Community Development
Division of Environmental Management
512 North Salisbury Street a Raleigh, North Carolina 27611
James G Martin, Governor July 15, 1988 R Paul Wilms
S Thomas Rhodes, Secretary Director
Mr. Ralph Roberts
Duke Power Company
P.O. Box 33189
422 South Church Street
Charlotte, NC 28242
Dear Mr. Roberts:
In response to your previous letter to Randy Dodd concerning a study
plan for assessing the water quality of Mountain Island Lake and the impact
of the Riverbend facility, the following comments are offered:
1) With regard to I.A., because of the frequency of sampling (2/year),
and the possibility of low level (below the detection limit) effects, it is
conceivable that a chemical program alone would not pick up impacts. The
priorities previously listed were based on water quality standards and data
presented in Table 12 of the report prepared by Kilkelly Envr. Associates
indicating concern with peak values.
2.) With regard to I.B.: because of the mode of operation of Cowans
Ford dam, the average dilution is about 400 to 1. However, the most
frequent flow is minimum release, with a dilution of about 10 to 1. There-
fore, sampling at anything but minimum release would not be expected to
indicate impacts, and would not be as indicative of potential impacts.
Because of limited biological activity during the winter and rapid flushing,
it is not thought that sampling in February will be as useful as sampling
during the growing season. It is therefore suggested that efforts for
physical/chemical water column sampling focus on the growing season.
3) With regard to the relative importance of water column and sediment
sampling: available guidance for performing analyses of toxicants in lakes
and reservoirs recognizes the importance of sediment/water interactions.
This is reflected in EPA's Technical Guidance Manual for Performing Waste -
load Allocations (Book IV, Lakes, Reservoirs, and Impoundments. Chapter 3,
Toxic Substance Impacts) (attached).
Pollution Pietenhon Pars
PO Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer

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4) With regard to fish tissue monitoring: it is true that obtaining a
control may be a real problem. In addition to assessing the impact of the
ash basin, an objective of this sampling could be to obtain background
information for comparison with other locations.
Please advise if questions.
Sincerely yours,
Steve W. Tedder, Assistant Chief
Technical Services Branch
SWT/gh