NC0020389_Correspondence_20201204

MAYOR
JERRY M MEDLIN
MAYOR PRO-TEM
CASANDRA P. STACK
COMMISSIONER
MAXINE HOLLEY
JAMES D. JOHNSON
DEAN MCLAMB
WILLIAM NEIGHBORS
DR. R.MAX RAYNOR
December 4, 2020
NC DEQ/DWR
Attn: NPDES Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
Dear Permitting Unit:
TOWN OF BENSON
P.O. BOX 69
303 EAST CHURCH STREET
BENSON, NC 27504
[phone]
FAX [phone]
www.townofbenson.com
Laserfiche
TOWN MANAGER
FREDERICK NELSON
ASSISTANT TOWN MANAGER
KIMBERLY PICKETT
TOWN CLERK
ANGELA THORNTON
TOWN ATTORNEY
R. ISAAC PARKER
RECEIVED
DEC 0 9 7020
NCDEQ/DWR/NPDES
Subject: NPDES Permit Renewal
Permit Renewal - Supplemental Information
Benson WWTP
NPDES Permit #NC0020389
Johnston County
The Town of Benson WWTP has received a draft permit for review for NPDES #NC0020389. We have
recently been informed that a request for reduced monitoring could be made during the renewal process.
We are submitting this additional information to be considered during the renewal process. We are
requesting that monitoring for BOD5, TSS, NH3-N and Fecal Coliform be reduced under the
"exceptionally performing facilities" criteria to two times per week.
The attached data (summarized in the following table) indicates that the WWTP effluent has greatly
exceeded the minimum criteria for reduced monitoring. The most restrictive summer limits were used
for calculating removal rates for BOD5, TSS and Fecal Coliform. For NH3-N, a weighted average was
calculated using the winter and summer limits. The data used for this 3-year analysis was for the period
of October 2020 — November 2017.
Analysis of testing results for the past three years:
- Percent of Monthly Average Limit
Parameter
Monthly Limit
3-Year Average
% of Limit
BOD5
5.0 mg/1
2.1 mg/1
42 %
TSS
30.0 mg/L
2.0 mg/L
7 %
Fecal Coliform
200/100 ml
1.4 colonies/100 ml
2%
NH3-N
1.42 mg/1 (Average)
0.5 mg/1
35.3%

- Number of Samples Over 200% of Monthly Average Limit
Parameter
200% of Monthly Limit
Number of Samples Over
BOD5
10.0 mg/1
8
TSS
60 mg/L
11
NH3-N
2.0/4.0
10
- Number of Samples Over 200% of Weekly Average Limit
Parameter
200% of Weekly Limit
Number of Samples Over
Fecal Coliform
800
0
In addition to the exceptional test results, the Benson WWTP is in compliance with all other criteria
listed in Section B Approval Criteria of the October 22, 2012 guidance document regarding reduction
of monitoring frequencies.
The Town appreciates the Division's effort to reduce the regulatory and monetary burden on systems
that strive consistently to provide exceptional wastewater treatment. We thank you for your consideration
in these matters. If you have any additional questions or comments, please contact Brian Leavitt at:
[phone] or [e-mail].
Sincerely,
1r
•
Tim Robbins, Public Utilities Director
Town of Benson

1 nree Year uata summary
T
2020 BOD Ave BOD Max
- tsenson nit- uts
TSS Ave TSS Max
ffuuLu525U
FC Ave FC Max
NH3 Ave
NH3 Max
October
0.20
2.40
0.12
2.80
18.80
66.00
0.04
0.20
September
0.50
3.90
0.00
0.00
14.30
72.00
0.09
0.30
August
1.20
4.30
0.00
0.00
13.40
48.00
0.16
1.27
July
0.70
4.50
0.00
0.00
6.10
88.00
0.04
0.26
June
1.18
4.10
0.00
0.00
11.50
76.00
0.05
0.32
May
0.60
3.20
0.00
0.00
14.00
56.00
0.09
0.55
April
1.50
6.70
1.10
18.00
6.60
70.00
0.05
0.30
March
4.20
18.00
0.00
0.00
2.30
62.20
0.20
2.60
February
3.20
6.30
0.14
2.80
2.30
74.30
0.30
1.80
January
2.15
5.80
0.00
0.00
1.40
21.60
0.48
2.45
Dec-19
2.20
7.20
0.00
0.00
1.30
5.20
0.18
1.30
November
0.57
3.30
0.00
0.00
1.30
8.50
0.10
0.32
2019
BOD Ave BOD Max
TSS Ave TSS Max
FC Ave
FC Max
NH3 Ave
NH3 Max
October
1.10
5.30 -
0.12
2.80
2.00
10.30
0.10
0.34
September
1.20
4.40
1.06
13.40
2.81
46.50
0.45
3.21
August
1.10
4.20
1.20
3.10
4.70
50.40
0.10
0.25
July
0.43
3.10
0.96
2.90
2.60
91.70
0.12
0.45
June
0.12
2.40
0.14
0.29
5.12
62.00
0.14
0.29
May
1.50
3.60
1.48
3.00
3.50
41.40
0.20
0.68
April
2.20
3.60
1.00
2.90
1.00
2.00
0.39
2.20
March
1.59
4.30
1.30
3.90
1.00
2.00
0.08
0.17
February
1.00
16.00
0.49
4.20
1.00
0.00
0.16
0.34
January
1.00
8.20
0.59
7.20
1.00
2.00
0.70
12.90
Dec-18
5.40
22.00
4.30
10.90
1.19
4.10
1.20
4.70
November •
1.86
6.60
2.50
16.00
1.60
72.30
0.68
6.74
2018
BOD Ave BOD Max
TSS Ave TSS Max
FC Ave
FC Max
NH3 Ave
NH3 Max
October
1.52
10.00
1.76
3.90
2.00
16.00
0.26
0.46
September
4.70
15.00
8.30
28.80
10.30
200.00
2.88
7.90
August
1.30
6.20
1.90
7.80
3.83
52.00
0.21
0.56
July
2.73
10.00
1.91
5.90
3.16
44.30
0.33
0.54
June
2.96
8.90
1.67
4.60
3.90
31.80
0.20
0.49
May
6.54
21.00
17.20
305.00
2.90
77.20
0.76
1.64
April
4.33
11.00
1.39
6.50
4.30
104.30
1.03
2.90
March
5.96
25.00
5.70
9.00
1.10
9.00
1.83
3.84
February
4.30
18.00
7.00
14.60
1.00
0.00
1.50
2.88
January
4.44
43.00
8.70
20.00
1.60
30.00
2.50
3.80
Dec-17
0.46
2.80
0.16
2.80
1.00
0.00
0.22
0.43
November
0.11
2.10
0.00
1.00
1.10
4.00
0.23
0.36
3-Year Arithmetic Average
2.1
2.0
0.5
Maximum Daily Result
43.00
305.00
200.00
12.90
3-Year Geometric Mean Average
4.4
Permit Limit
5.0
30.0
200
1.42 (Ave. 12 month limit)
of Limit
42%
7%
2%
35.3%