NC0062219_Staff Comments_19901005

DIVISION OF ENVIRONMENTAL MANAGEMENT
October 5, 1990
MEMORANDUM
TO: Dale Overcash
FROM: Juan C. Mangles
THROUGH: Carla Sanderson
Ruth Swanek 11Q5
Trevor Clements .
SUBJECT: NPDES Permit Modification Request
Carolina Water Service, Inc.
Kings Grant Subdivision WWTP
NPDES Permit No. NC0062219
Wake County
The Technical Support Branch has received the attached NPDES permit modifica-
tion request dated September 20, 1990 concerning the subject facility.
15 NCAC 2B .0508 requires that fecal coliform be monitored instream 2/month
for "Class II" facilities. According to DEM's rating standards, the subject
facility has been rated as a "Class II" facility.
Also, the facility has recorded downstream monthly geometric mean values
which are higher than upstream monthly geometric mean values. Although these
downstream concentrations may have protected the stream standard for fecal coli-
form, the self -monitoring data suggest a limited impact.
In addition, a review of the self -monitoring instream data suggest that fecal
coliform instream standard violations may occur downstream from the discharge.
Downstream fecal coliform geometric mean concentrations of 215 #/ml in June, 1990,
309 #/100 ml in May, 1990 and 1,387 #/100 ml in May, 1989, based on bimonthly
samples, were reported in the DMR's. Please note that the fecal coliform instream
concentrations reported in May and June, 1990 are concomitant with upstream and
effluent fecal coliform geometric mean concentrations reported below the fecal
coliform stream standard of 200 #/100 ml.
Furthermore, the effluent self -monitoring data indicate that total residual
chlorine concentrations discharged during the last three years violate the current
action level for chlorine (17 ug/1) under S7Q10 flow conditions. The permittee has
been notified about chlorine toxicity by letter dated July 5, 1990. Therefore, the
facility should decrease the amount of chlorine currently used to disinfect the
wastewater and, at the same time, protect a fecal coliform stream standard of 200
#/100 ml. Since protection of the fecal coliform standard has been accomplished
through chlorine supersaturation of the effluent (i.e. 4/89-3/90 maximum observed
concentration = 900 ug/1; 4/89-3/90 average observed concentration = 632 ug/1), it
would be appropriate to observe the downstream fecal coliform concentrations as the
facility reduces chlorine levels due to toxicity.

In light of this, the Technical Support Branch does not consider the
requested permit modification apprropiate. Therefore, it recommended that the
instream monitoring requirement for fecal coliform be maintained in the NPDES
permit.
If you need further clarification in this matter, please contact me at ext.
510.
Attachment
Tim Donnelly
Central Files
MLA Files

CAROLINA WATER SERV!CE.INC. of N.C.
AN AFFILIATE OF
t IIIRonImEl c
Corporate Offices:
2335 Sanders Road
Northbrook, Illinois 60062
Telephone: [phone]
Regional Offices:
5701 Westpark Dr., Suite 101
P.O. Box 240705
Charlotte, NC 28224
[phone]
Fax[phone]
September 20, 1990
Mr. Dale Overcash
N.C. Dept. of Environment,
NPDES Permits Group
P.O. Box 27687
Raleigh, N.C. 27611-7687
Ref: Kings Grant WWTP
NPDES #NC00622.1.9
Wake County
Dear Mr. Overcash,
/05'AL D,4
North Carolina:
Asheville, NC
Banner Elk, NC
Charlotte, NC
Morehead City, NC
New Bern, NC
Whispering Pines, NC
•
Health & Natural Resori
PETIMIIS
20990
: 1990
I am in receipt of the above referenced draft NPDES permit
and hereby request that the upstream and downstream sampling
requirement for Fecal Coliform-be deleted from the new
permit.
If these tests are required, it will only increase our
operating costs and as long as our discharge meets the NPDES
permit limitations, I cannot see a need or a benefit in the
collection of this data.
If you have any: questions or • would ,like .to discuss this
Matter in more.detail, please don't hesitate to contact me at
this office.
Sincerely,
Carl Daniel
Vice President
CD:tmc
cc: Eddie Baldwin
[phone]
[phone]
[phone]
[phone]
[phone]
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