NC0023884_Environmental Assessment_19940422

MEMORANDUM
TO: Monica Swihart
FROM: Betsy Johnson,l�
THROUGH: Steve Bevington,$
Ruth Swanek (? (5
April 22, 1994 J c-oo z38$4
SUBJECT: Salisbury Environmental Assessment
The subject EA report discusses Grants Creek and Yadkin River but makes little reference to
Town Creek. The eventual goal of this project is the removal of discharges from both Grants
and Town Creeks. Discussion of current water quality in Town Creek and removal of the
discharge should be included. This document has only one page about water quality impacts.
There is a great deal of historical water quality information available on High Rock Lake. In
addition, there is a recent High Rock Lake water quality report by Environmental Sciences.
Data on Grants Creek and Town Creek are covered as well as the lake data. There is also quite a
bit of self -monitoring data on Grants and Town Creek which should be summarized.
There should be a more complete discussion of the new wastewater treatment plant. What type
of plant is it? What kind of removal efficiencies will it have? The no -action alternative should
include a discussion of the age of the existing plant and its operational difficulties. The report
should specifically discuss the parameters of concern, i.e., oxygen -consuming wastes, toxics, and
nutrients. The pretreatment program should also be discussed. The action alternatives should
more clearly discuss how current operational difficulties will be resolved. Each of the
alternatives should address the capability for future expansion. It should be noted that the
existing limits will remain after relocation until the plant expands. Upon expansion, new limits
will be required.
Though the new plant has not yet received permit limits, there should be a discussion of
speculative limits. DEM provided a letter with speculative limits in February 1993. Speculative
limits were provided for BOD5, NH3, and DO. Dechlorination or alternate disinfection will be
required. Nutrient removal is recommended due to eutrophication in High Rock Lake.
Chemical specific limits will be based on Salisbury's pretreatment program and final diffuser
design. Modeling and design for the diffuser are currently in progress.
There should be a short discussion of mitigation of acute impacts by discharging through a jet
diffuser which will increase near field mixing. In addition, the facility will be required to
conduct quarterly toxicity testing. This will likely be a chronic test at a percentage based on
near field dilution.
If you have any questions or comments, please call me at Ext. 508.
cc: Mooresville Regional Office