NC0051322_Wasteload Allocation_19910607

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WLA Notes
SRB
6/7/91
Carolina Water Service Inc. of NC / Ashley Hills Subdivision
NCO051322
Ashley Hills has applied for a permit modification to
increase flow from 0.15 to 0.25 MGD. Over the past two years
the facility has been in compliance. Flow has remained well
below the permitted level.
The discharge is to Poplar Creek which is classified as
C-NSW. Expanding facilities in the Neuse River basin are
required to meet 2 mg/l TP.
- Updated flow estimates from USGS indicate that flow is
less than previously thought. This has been taken into
account with a new level-b model of Poplar Creek.
- The permit was last renewed in August of 1990. 'At that
time new NH3 and Fecal Coliform limits were assigned. Since
that time, a model of -Poplar Creek was developed that
predicts that high levels of BOD and NH3 are reaching the
Neuse River approx. 2 miles downstream. One permit was
denied on Poplar Creek, and an upstream facility received 5
and 2 limits upon modification (Cottonwood, NC0065706).
To prevent excessive BOD from reaching the Neuse, the
effluent concentration should be limited to 5 mg/l. The NH3
toxicity limit of 2.4 mg/l will protect both Poplar Creek
and prevent excessive NH3 from reaching the Neuse.
Loading to Neuse from Poplar Creek:
Existing conditions: 8.6 mg/l BOD, 3.8 mg/1 NH3.
As recommended: 5.7 mg/l BOD, 3.6 mg/l NH3.
(Most NH3 results from another discharge, permitted
before ammonia toxicity limits.)
- Limits have been recommended that keep the facility from
contribution to BOD loading of the Neuse.
Poplar Creek is still predicted to discharge above 5 'and 2
to the Neuse, but this is primarily due to one facility
which still has secondary limits.
- Chlorine levels in the effluent have been high, up to 0.5
m g / 1 . dcn-f v.4,
9 2 02,01944• l000 �'GP IAQ gk /Vrcp� � A P)A a 6 W 10 �O QZ

*Cottonwood Subdivision recieved 10 and 4 limits! The end values of the model were above the required background, but
that was due to the over -allocated BOD limits applied to Kings Grant. DO does recover after the Cottonwood Subdivision,
thus the 10 and 4 limits. 14 July, 1993
1991 permit renewal has an excellent history write-up for this facility, please refer to it.
Model run and re -allocated 1991 as part of Neuse Basin Management Strategy. It was permitted for 0.026 mgd and an
expansion to 0.115 mgd. At 0.115 mgd this facility received limits of 5 mg/I BOD and 2 mg/I NH3N. These limits were due
in large part to an equitable distribution of limits with in that area.
This facility is in a clustered stream segment containing discharges from Ashley Hills Sbdvn [CWS] NC0051322, (also on
Poplar Creek) and Kings Grant Sbdvn [CWS] NC0062219, [on an unnamed tributary to Poplar Creek]. Kings Grant had
previously been permitted at 26 / 30 mg/I BOD and 20 mg/I / monitor NH3N. It was Kings Grant that was, by modeling,
taking up all the assimilative capacity on Poplar Creek. To remedy that, the "New and Existing" rules were enforced, and
Kings Grant became re -permitted for their actual flow (0.07 mgd) and received 5 mg/I BOD and 2 mg/I NH3N for their
previous permit limit of 0.21 mgd.
Ashley Hills had already received limits of 5 mg/I BOD and 2.4 mg/I NH3N for their planned expansion.
The problem now is that Cottonwood has requested permit limits for 0.0575 mgd; a flow which is in between their previous
0.026 mgd and their requested expansion of 0.115 mgd. To remedy this and retain consistency in not the only the basin -
management, but also for this clustered stream segment, Cottonwood Sbdvn will receive limits based on the loading at 5
and 2 for 0.115 mgd. These will be run in the model for verification.
Limits based on loading of 5 and 2 at flow of 0.115 mgd - will not be used!
BOD
summer: 5.0 mg/I BOD * 8.34 * 0.115 mgd = 4.7955 #/d --> 4.7955 #/d / (8.34 * 0.0575 mgd) = 10 ma/I BOD
winter: 10.0 mg/I BOD * 8.34 * 0.115 mgd = 9.591 #/d --> 9.591 #/d / (8.34 * 0.0575 mgd) = 20 mq I/ BOD
NH3N
summer: 2.0 mg/I NH3N * 8.34 * 0.115 mgd = 1.9182 #/d --> 1.9182 #/d / (8.34 * 0.0575 mgd) = 4.0 mg/I NH; N
winter: 4.0 mg/I NH3N * 8.34 * 0.115 mgd = 3.8364 #/d --> 3.8364 #/d / (8.34 * 0.0575 mgd) = 8 mq/I NH N
**The Neuse Basin strategy of dischargers on the tributaries calls for the confluence meeting background conditions of at
least 5 mg/I BOD and 2 mg/I NH3N. After running this discharger with loading based limits in a model, this requirement
was not met. The model consisted of the other interacting dischargers being set at their previous limits and flows, (i.e., at
their smaller, not expanded flows, but with their greater, [i.e. not 5 and 2] limits). The confluence requirements were met
for ammonia, but not for BOD. The first model run, with limits based on equal loading, (refer formula's above) yielded
confluence numbers of 6.2 mg/I BOD and 1.9 mg/I NH3N. The final run, [with limits of 5 mg/I BOD and 4 mg/I NH3N]
yielded confluence numbers of 5.95 mg/1 BOD and 1.9 mg/I NH3N. These model run limits will be applied as the basin -
management report language caps BOD limits at 5 mg/l.
The Fact Sheet language will be as follows:
Facilities discharging to the XXX Creek tributary to the Neuse River are required to minimize BODS
and NH3N loading at the mouth of the tributary before entering the River mainstem, (i.e.
concentrations in the receiving stream should be 5 mg/I BOD5 and 2 mg/I NH3N). This facility
needs to achieve levels of treatment that will reflect limits of XXX mg/I BOD5 and XXX mg/I NH3N
to maintain these instream concentrations. An engineering report evaluating the cost feasibility of
meeting these limits should be submitted by June 1, 1996. If these limits cannot be achieved, the
analysis should include an evaluation of alternatives to the discharge.
*note: The alternatives analysis requirement will be deleted due to the mutual agreement between DEM and this facility
to expand and meet these stricter limits, obviously no alternative is available and their limits will virtually be 5 and 2.

WLA Notes
SRB
2/1/93
Carolina Water Service, Inc. - Kings Grant Subdivision
NC0062219
- Kings Grant has applied for a permit renewal for its 0.21 MGD facility. Over the past
three years, the facility has been in compliance. No DO problems have been reported at
the upstream or downstream sampling sites over the past three years.
- Kings grant began whole effluent toxicity testing in 1991. Since then they have passed 7
of 9 reported tests: Toxicity may be due to residual chlorine, which has been as high as
1.0 mg/1.
- The facility discharges to a UT of Poplar Creek, C-NSW. The UT joins Poplar Creek
0.89 miles above the Neuse River. The UT has a zero 7Q10 and a 30Q2 of 0.08 cfs.
- A Level-b model developed for Poplar Creek predicts that Kings Grant, at its present
permit limits, results in BOD and NH3 concentrations at the bottom of Poplar Creek of
8.2 mg/1 BOD5 and 3.8 mg/1 NH3 (See model results). These concentrations are above
the concentrations recommended in the Neuse Basinwide Plan and the NH3 concentration
is above the instream target. To meet the instream targets Kings Grant at 0.21 MGD
would have to meet summer limits of 5.4 mg/1 BOD5 and 3.1 mg/1 NH3.
- The existing facility is at 0.07 MGD. It is recommended that the permit be renewed with
two sets of limits, at '0.07 and 0.21 MGD. Existing permit limits are recommended for he
0.07 MGD flow. These limits are predicted to result in BOD5 and NH3 concentrations at
the mouth of Poplar Creek of 5.8 and 1.8 mg/l respectively. These predicted loadings to
the Neuse River are lower than under the existing permit limits. The 0.21 MGD flow will
be treated as new and so will receive limits consistent with the zero flow policy and the
Neuse River Basinwide Plan. The expanded facility is predicted to result in BOD5 and
NH3 concentrations at the mouth of Poplar Creek of 4.5 and 0.8 mg/l respectively. These
concentrations are consistent with the Neuse River Basinwide Plan.

0 uV1 P1 L• A
ASHLEY HILLS AT 0.15 MGD
WITH INTERACTING FACILITIES.
------ MODEL RESULTS ----------
;charger : ASHLEY HILLS NCO051322
ceiving Stream : POPLAR CREEK
-------------------------------------------------- ------------------
• End D.O. is 5.18 mg/l.
e End CBOD is 12.84 mg/1. /y�
e End NBOD is 17.08 mg/1.
------------------------------------------------------------ -
WLA
WLA
WLA
DO Min CBOD
NBOD
DO
Waste Flow
(mg/1) Milepoint Reach # (mg/1)
---------------------- ----
(mg/1)
(mg/1)
(mgd)
gment
1
5.18 2.74 5
----
--
----------
each
1
7.50
9.00
6.00
0.11500
each
2
0.00
0.00
0.00
0.00000
each
3
0.00
0.00
0.00
0.00000
each
4
45.00
14.85
0.00
0.15000
each
5
39.00
90.00
6.00
0.21000

o1n*r— j ASHLEY. HILLS AT 0.25 MGD
WITH INTERACTING FACILITIES.
------ MODEL RESULTS----------
scharger : ASHLEY HILLS NCO051322
;ceiving Stream : POPLAR CREEK
•--------------------------------------------------------------------
te End D.O. is 5.80 mg/l.
ie End CBOD is 8.69 mg/1. Z / _a��� ���� ,e�,,t .�,{ �j���+►f,�On---
ie End NBOD is 16.12 mg/l. h�
=-------------------------------------------------------
WLA
WLA
WLA
DO Min CBOD
NBOD
DO
Waste Flow
(mg/1) Milepoint Reach # (mg/1)
---------------- ----
(mg/1)
----
(mg/1)
--
(mgd)
----------
;gme-nt
1
------
5.80 2.74 5
teach
1
7.50
9.00
6.00
0.11500
teach
2
0.00
0.00
0.00
0.00000
teach
3
0.00
0.00
0.00
0.00000
teach
4
7.50
10.80
6.00
0.25000
teach
5
39.00
90.00
6.00
0.21000

SUMMER
ASHLEY
HILLS AT 0.25 MGD
�
WITH INTERACTING FACILITIES.
2 Reach #
2
Seg Mi 2
D.O. 2
CBOD 2
NBOD 2
Flow 2
y#
1
0.00
6.78
3.86
3.70
0.53
1
1
0.01
6.80
3.84
3.67
0.53
1
1
0.02
6.83
3.82
3.64
0.53
1
1
0.03
6.86
3.80
3.61
0.54
1
1
0.04
6.89
3.78
3.58
0.54
1
1
0.05
6.91.
3.76
3.55
0.54
1
1
0.06
6'.94
3.74
3.52
0.55
1
1
0.07
6.96
3.73
3.49
0.55
1
1
0.08
6.98
3.71
3.46
0.55
1
1
0.09
7.00
3.69
3.44
0.56
1
1
0.10
7.02
3.67
3.41
0.56
1
1
0.11
7.04
3.66
3.38
0.56
1
1
0.12
7.06
3.64
3.36
0.57
1
1
0.13
7.08
3.62
3.33
0.57
1
1
0.14
7.10
3.61
3.30
0.57
1
2
0.11
7.10
3.61
3.30
0.57
1
1
2
0.16
7.18
3.53
3.18
0.59
1
2
0.21
7.25
3.46
3.07'
0.61
1
2
0.26
7.30
3.39
2.96
0.62
1
2
0.31
7 23 5
3.32
2.86
0.64
1
2
0.36
7.39
3.26
2.76
0.66
1
2
0.41
7.42
3.19
2.67
0.67
1
2
0.46
7.45
3.14
2.58
0.69
1
2
0.51
7.48
3.08
2.50
0.71
1
2
0.56
7.50
3.03
2.42
0.72
1
3
0.56
7.50
3.03
2.42
0.72
1
3
0.61
7.47
2.98
2.36
0.74
1
3
0.66
7.45
2.93
2.30
0.76
1
3
0.71.
7.43
2.89
2.24
0.77
1
3
0.76
7.41
2.84
2.19
0.79
1
3
0.81
7.40
2.80
2.14
0.81
1
3
0.86
7.38
2.76
2.09
0.82
1
3
0.91
7.38
2.72
2.04
0.84
1
3
0.96
7.37
2.69
1.99
0.85
1
3
1.01
7.36
2.65
1.9.5
0.87
1
4
0.93
6.94
4.14
4.67
1.26
1
.4
1.03
6.95
4.06
4.54
1.27
1
4
1.13
6.97
3.98
4.41
1.29
1
4
1.23
6.98
3.91
4.28
1.30
1
4
1.33
7.00
3.84
4.16
1.32
1
4
1.43
7.02
3.76
4.05
1.33
1
4
1.53
7.03
3.69
3.93
1.35
1
4
1.63
7.05
3.63
3.83
1.36
1
4
1.73
7.07
3.56
3.72
1.38
1
4
1.83
7.09
3.50
3.62
1.3.9
1.
4
1:93
7.10
3.43
3.52
1.41
1
4
2.03
7.12
3.37
3.43
1.42
1
5
1.94
6.91
10.00
19.53
1.75
1
5
2.04
6.65
9.83
19.07
1.76
1
5
2.14
6.43
9.65
18.61
1.78
1
5
2.24
6.26
.9.48
18.17
1.79
1
5
2.34
6.12
9.32
17.73
1.80
1
5
2.44
6.00
9.16
17.31
1.81
1
5
2.54
.5.92
9.00
16.90
1.83
1
5
2.64
5.85
8.84
16.51
1.84
?-
1
5
2.74
5.80
8.69
16.12
1.852
2
Seg
# 2 Reach
#
2 Seg Mi
2 D.O.
2 CBOD
2 OD
NB
2 Flow