NC0039331_Wasteload Allocation_19910415

NPDES WASTE LOAD ALLOCATION
PERMIT NO.: NCO039331
PERMITTEE NAME: Chatham County Board of Education / Bonlee
Facility Status: Existing
Permit Status: Renewal
Major
Pipe No.: 001
Design Capacity:
Minor
0.007 MGD
Domestic (% of Flow):
Industrial (% of Flow):
Comments:
100 %
Refer: Basinwide / Streamline WLA File
Completed By Permits & Engineering
At Front Of Subbasin
RECEIVING STREAM: an unnamed tributary to Bear Creek
Class: C
Sub -Basin:
03-06-12
Reference USGS Quad: E21NW
(please attach)
County: Chatham
Regional Office: Raleigh Regional Office
Previous Exp. Date: 7/31/91 Treatment Plant Class: 1
Classification Chan es within three miles•
Modeler
Date Rec.
#
2 ,
Drainage Area (mi ) , I Avg. Streamflow (cfs): d . 0 °l
7Q10 (cfs) 0 Winter 7Q10 (cfs)(Z 30Q2 (cfs) n
Toxicity Limits: IWC
Instream Monitoring:
% Acute/Chronic
Parameters'l)(0, -TemO
Upstream ✓ Location u,ps{r am. 0ur• �60
Downstream -� Location
Effluent
Characteristics
/ 3 "o ices
R 3 y ea• s
&OU. kr
BOD5 (m )
I
/ 8
is
/ 0
NH3-N (mg/1)
D.O. (mg/1)
G
TSS (mg/1)
'50
3b
30
30
F. Col. (/100 MI)
400
a00
d ce>
,ZDo
pH (SU)
6-7
6 -1
g
No change within three miles. ZERO FLOW POLICY: Recommend removal. Facility must submit an engineering
report within 12 months evaluating alternatives to discharge. If there are
no alternatives, limits will change after 3 years to 5(10) & l(1.8) for
BOD5 & NH3-N for summer (winter). Instream monitoring may be dropped when
PLO D the facility agrees, in writing, to a schedule for removal.
Facility will receive letter addressing chlorine toxicity.
Requested by: Mack Wiggins Date: 3/5/91 ------- -------------------- --------------------- --------------------
Prepared by: Date: d ql I I I I
Comments: w eL boa - un a mwil-r' pedsec•�e- r Ys "-
Reviewed by: sait, Date: f {�,; ►fin ,14 s o ''{s ava�ia{ic 1�-Ey.

go
-1- MAR 111991
FACT SHEET FOR WASTELOAD ALLOCATIONS RALEIGH REGIONAL OFFICE
Request # 6110
Facility Name :Bonlee Elementary School/Chatham County
NPDES No. :N00039331 z, ' �'
Type of Waste :Domestic RECEIVED
YJ
ED
Facility Status :Existing
Permit Status :Renewal APR 1 1991
Receiving Stream :UT to Bear Creek
Stream Classification:C PERMITS &
ENGIN
Subbasin
:03-06-12
EERinU
County
:Chatham
Stream
Charactristics:
Regional Office
:Raleigh
USGS # estiamte
Date
Requestor
:Mack Wiggins
Drainage
Area:
0.1
sq.mi.
Date of Request
:3/5/91
Summer
7Q10:
0
cfs
Topo Quad
:E21NW
Winter
7Q10:
0
cfs
Average
Flow:
0.09
cfs
30Q2:
0
cfs
Wasteload Allocation Summary
(approach taken, correspondence with region, EPA, etc.)
School has difficulty meeting BOD5, NH3-N, and DO limits. The chlorine
levels are too high. Allowable chlorine for the stream is 17 ug/l. No
instream data. Discharge is to zero flow stream. Recommend removal.
Facility must submit an engineering report within 12 months evaluating
alternatives to discharge. If there are no feasible alternatives, the
limits will change after 3 years to 5&1 (10&1.8) for BOD5 & NH3-N for
summer (winter). Instream monitoring requirement may be removed when the
facility agrees, in writing, to a schedule for removal. 9i
d0( _ Fes' /•ty /Ca S rf
Special Scheduled Requirements and additional comments from Reviewers:
Recommended by: Date:
Reviewed by
Instream Assessment:_ �� SGOiMM Date: 3(7(qt
Jj Regional Supervisor: Date: Za 9
Permits & Engineering: I �, Date: Z ti
RETURN TO TECHNICAL SERVICES BY: APR 0.5 1991

.
a
Existina Limits
-2 -
CONVENTIONAL PARAMETERS
Monthly Average
Summer/Winter
Wasteflow (MGD):
0.007
BOD5 (mg/1):
15/18
NH3N (mg/1):
4/6
DO (mg/1):
6
TSS (mg/1):
30
Fecal Coliform (/100 ml):
1000
PH (SU):
6-9
TP (mg/1) :
TN (mg/1):
Toxicity:
none
Recommended Limits
A
Monthly Average
Summer/Winter
Wasteflow (MGD): .007
BOD5 (mg/1): 15/18
NH3N (mg/1): 4/6
DO (mg/1): 6
TSS (mg/1): 30
Fecal Coliform (/100 ml): 200
PH (SU): 6-9
Toxicity: none
Chlorine(mg/1): monitor
INSTREAM MONITORING REQUIRMENTS:
Upstream: Y Location: upstream when flow
Donwstream: Y Location: SR 1141
Daily Maximum
60
B
Monthly Average
Summer/Winter
.007
5/10
1/1.8
6
30
200
6-9
none
0.017
Limits Chancres Due To: Parameter(s) Affected
Instream Data
Ammonia Toxicity NH3-N
Chlorine Cl
Nutrient Sensitive Waters
HQW
New 7Q10 flow data
Special Modeling Studies
New facility information
ZERO FLOW POLICY BOD5, NH3-N

IV-0 -
R OL k'---coq PA(r")-
IM

State 'of North Carolina
Department of Environment, Health, and Natural Resources
Division of Environmental Management
512 North Salisbury Street • Raleigh, North Carolina 27611
James G. Martin, Governor George T. Everett, Ph.D.
William W. Cobey, Jr., Secretary March 11, 1991 Director
Perry W. Harrison
Bonlee Elementary School
P.O. Box 128
Pittsboro, NC 27213
Subject: Chlorine Toxicity
NDPES Permit No. NCO039331
Chatham County
Dear Mr. Harrison:
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/l (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 may be toxic to aquatic
life in the receiving stream under low flow conditions, i.e., the amount of chlorine discharged causes
an exceedance of the instream action level for chlorine (17 ug/l for chronic effects and 28 ug/l for
acute effects) under 7QJ0 conditions (the lowest average daily 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 instream waste concentration of 100%, an acceptable
level of chlorine in your effluent is 17 ug/l or 0.017 mg/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.
Pollution Prevention Pays
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer

4
1
-2-
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 facilities with chlorine
problems. If the chlorine levels in your facility's effluent remain unchanged, a chlorine limit or
whole effluent toxicity requirement may be added to your permit limitations.
Please feel free to call Tim Donnelly of the Division's Regional Office at [phone] if you
have any questions or comments regarding this issue.
Sincerely,
Steve W. Tedder
Water Quality Section Chief
SWT/eaj .
cc: Raleigh Regional Office
Central Files
Pollution Prevention Pays
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer