NC0030139_correspondence_19900601

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State of North Carolina
Department of Environment, Health, and Natural Resources
Division of Environmental Management
512 North Salisbury Street e Raleigh, North Carolina 27611
James G. Martin, Govemor George T. Everett, Ph.D.
WH!am W. CObey, Jr" Secretary June 1, 1990 Director
Brenda Price
Rutherford County Convalescent Center
Route 2, Box 39-A, Airport Road
Rutherfordton, NC 28139
Subject: Chlorine Toxicity
NPDES Permit No. NCO030139
Rutherford County
Dear Ms. Price:
Chlorine, a widely used wastewater disinfectant for the
treatment of coliform organisms, often remains instream in residual
amounts that may prove to be toxic under critical low stream flow
conditions. In the last decade, EPA assessed the potential adverse
effects of chlorine to the aquatic environment and has taken steps to
reduce the impacts through the development of federal criteria. In
1986, EPA recommended that all states have a chlorine standard by
their next triennial review of water quality standards.
In revising its water quality standards in 1989, North Carolina
developed an action level for chlorine of 17 ug/1 (freshwater classes
only). In addition, the fecal coliform limit was reduced from 1000
colonies/100 ml to 200 colonies/ 100 ml. Under a new DEM procedure,
dechlorination and chlorine limits are now recommended for all new or
expanding dischargers proposing the use of chlorine for effluent
disinfection. The Division is reviewing chlorine levels from all
existing dischargers as part of their NPDES permit renewal process.
Our records indicate that chlorine from your facility's effluent
discharge is considered toxic to the receiving stream under low flow,
conditions, i.e., the amount of chlorine discharged causes a
violation of the instream action level for chlorine (17 ug/1) under
7Q10 conditions (the average flow for seven (7) consecutive days
during a ten (10) year period). Action should be taken to reduce the
effluent concentration of chlorine to an acceptable level. Based on
your facility's instream waste concentration of 4.5% an acceptable
level of chlorine in your effluent is 382 ug/l. If this level is not
feasible, you should consider dechlorination or alternate methods of
disinfection for your facility to ensure that both chlorine and
bacterial limits are met. In addition, if your facility plans to
undertake any phase of construction, dechlorination or alternate
disinfection should be included. However, please note that an
authorization to construct must be obtained from this Division prior
to any alteration to your treatment plant.
Mudon Prevendcm Pays
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
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The Division is currently reviewing its water quality
regulations pertaining to chlorine. In the future, effluent limits
and/or dechlorination may be required of existing facility's with
chlorine problems. If the chlorine levels in your facility's
effluent remain unchanged, a chlorine limit or a whole effluent
toxicity testing requirement may be added to your permit limitations.
Please feel free to call Forrest Westall of the Division's
Regional Office at [phone], if you have any questions or
comments regarding this issue.
Sincerely,
CAA�Z,") �e�zm ---,
Steve Tedder
Water Quality Section Chief
cc: Asheville Regional Office
Central Files
WLA File