NC0040011_Wasteload Allocation_19870807

NPDES DOCUWENT SCANNING COVER SHEET
NC0040011
Yanceyville WWTP
NPDES Permit:
Document Type:
Permit Issuance
:`
Wasteload Allocation
M
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
August 7, 1987
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Brief of WLA Analysis
Previous WLA's
1977: Recieved limits of 20 and 6 fora flow of 0.125 mgd. Discharge to Jail House Branch; a tributary to Country Line
Creek.
1981: In -stream assessment based on influent / effluent efficiency and flow increase to 0.2 mgd. Modeling analysis of
the Jail House Branch outfall indicated instream DO problems. New modeling analysis performed with correction
in flow statistics from the 1977 model. Final WLA for flow increse recommended limits of 18 (21) and 7 (12)
summer (winter) limits. A time of travel study accompanies this analysis; it addresses 'an enormous amount of
algae' below the outfall of the oxidation pond. A second WLA was finalized in 1981 which included a proposal for
the outfall to reloacte to Country Line Creek. Limits recommended for Jail House Br were 12 (16) and 2 (5), and
those recommended for Country Line Creek were 30 / 30.
1982: Facility must have been struggling to meet SOC requirments, therefore numerous instream assessments took
place with small incremental flow increases. Their discharge point to Jail House Branch created many
documented DO problems, but no strong evidence of relocation existed to date in the WLA files.
1984: Facility relocated to Country Line Creek and with a discharge of 0.200 mgd the facility recieved 30 / 30 limits.
1986: Relocation of plant not yet complete. Various SOC's and instream assessments took place.

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TABLE 1.
Summary of SOC Wasteflows for Yanceyville WWTP
Pre-SOC
Previously Approved SOC
Current SOC Request
Flow (MGD)
0.10000 .
0.02467
0.00565
TOTAL 0.13032
TABLE 2.
Model Results Reflecting Discharge to Jailhouse Branch
Design Wasteflow BOD5 D.O. Min. (mg/I) D.O. Min. (mg/1)
(MGD) (mg/1) Jailhouse Branch Country Line Cr.
Pre-SOC 0.1000 140 0.0 4.3
SOC 0.1303 140 0.0 3.3
Pre-SOC 0.1000 100 0.0 5.0
SOC 0.1303 100 0.0 4.2
TABLE 3.
Model Results Reflecting Discharge to Country Line Creek
Design Wasteflow BODE D.O. Min. (mg/I)
(MGD) (mg/1) Country Line Cr.
Pre-SOC 0.1000 140 3.9
SOC 0.1303 140 2.8
Pre-SOC 0.1000 100 4.7
SOC 0.1303 100 3.8

'
.
Appendix A
t
;NEX78/MY _ . 08/07/E.
COMPLIANCE EVALUATION ANALYSIS REPORT
PERMIT--NC0040011 PIPE~-001 REPORT PERIOD: 8507 ~8606 LOC---E
7ACILITY~~YANCEYV%LLE SAN. DISTRICT WWTP DESIGN FLOW-- °2000 CLASS--
-OCAT%ON--YAMCEYV%LLE REGION/(*t'OUNTY-~04 CASWELL
50050 00310 00530 00610 31818 50060 00300
40NTH Q/MGD BOD RESITSS NH3+NH4- FEC COLI CHLORINE DO
' '35/07 "1366 62^00 108.5F 3^96 17.9 .165 4.79
]5/08 .1372 41.00 88.5 4.45 6.3 .i22 6.98
35/09 .1190 54.00 5i.5 8.4i 3i.9 .i68 6.93
35/10 .1083 49.00 47.0 12-7.26 2.0 .234 6.4O
35/11 .1173 50.00 57.0 12.66 2.O .200 7.37
^ 35/12 .1865 38.50F 34.OF 7.65F 2.0 ^255 8.i2
36/01 .i102 94.50F 49.O21.�9F i54.9 .2i9 5.9 F 5
-3 6 02 .1087 78.00F 33.OF 28^2iF 16.5 .18M 4.22
�6/03 .1i05 94.00F 53.0F 25.31F 2.O .195 3.9O
36/84 ^1195 92.00F 142.8F 16^20F 2.0 .177 7.24
]605 .1O73 55.50F 64.5F 8.48F 2.0 .205 7.69
]6/06 .i055 67.50F 80.oF 9.59F 2.0 .i92 6.67
\VERACE .ii55 64.66 67^3 i3.O� 2O.i .i92 6.35
IAXIMUM .i800 117.00 18O.0 26.62 12O0111),.1) .4O0 9.00
1INIMUM .i0OO 29.00 26.O 1.91 2.O TRACE 2.O0
IT M�D M�/L M�/L M�/L �/iO0ML MC
|N

flow. a minimum 0.0. of 0.0 mg/I is predicted to occur in Jailhouse Branch and a
secondary sag of 4.3 mg/I is predicted to occur in Country Line Creek. With the
total SOC flow added, the secondary sag in Country Line Creek is expected to drop
to 3.3 mg/I.
Given the predicted impacts. 1 have trouble justifying the need for a BODE
limit of 140 mg/I when self -monitoring data for the last year show no monthly
average exceeding 95 mg/1 (see Appendix A). A second set of model runs were
completed using waste concentrations of 100 mg/I of B0D6 (see Table 2). The
results show a substantial improvement in the secondary sag. However, the pre-
dicted impact to D.O. from the total SOC flow is still greater than the criterion
for no significant impact.
Results for the model runs reflecting a direct discharge to Country Line
Creek are shown in Table 3. This change should eliminate the occurrence of an
anaerobic zone below the outfalt. However, the D.O. sag in Country Line creek is
expected to reach slightly lower levels than with the outfalt on Jailhouse
Branch. The predicted change in the D.O. minimum from the total SOC flow is 1.1
mg/1, which is substantially higher than the 0.5 mg/I criterion. Lowering the
allowable B0D6 concentration to 100 mg/1 reduces the predicted net change to 0.9
mg/1 and increases the minimum expected D.O. by 1.0 mg/l.
cc: 1. Page Benton
Kent Wiggins
Gray Hauser