NC0031836_Flow Reduction Request_20230712

CITY of \1 Y Assistant City Manager/City Engineer 704 878-3551
Public Works Director 704 878-3552
Public Utilities Director 704 761-2383
4A PUBLIC UTILITIES Office Manager 704878-3567
P. O. Box 1111, Statesville, NC 28687-1111
28 March 2023 R E C E I V E
North Carolina Department of Environmental Quality
Division of Water Resources
Attn: Charlie Miller, PE
1617 Mail Service Center
Raleigh NC 27699-1617
Subject: Flow Reduction Request
APR 03 2023
NDDEQ/DWR/NPDES
References: (a) 15A NCAC 02T .0114(f)
(b) Division of Water resources Guidance Regarding Flow Reduction Requests 15A
NCAC 02T .0114(f) dtd 29 Aug 22
(b) Email NCDENR(Miller)/COS (Vaughan), Subj: Wastewater Flow Reduction,
DTG 310858R Aug 23
Enclosures: Calculations (Attachments A — B)
Dear Mr. Miller:
The City of Statesville has performed a flow reduction request analysis in accordance with
references (a) and (b) for the City sewer collection system (WQCS 00030). Having two
wastewater treatment facilties required a contributory residence analysis based on watershed.
The City requests consideration of a flow reduction for the 4th Creek watershed. The attached
exhibits provide the subject calculations. The requested flow adjustments follow:
Fourth Creek WWTP (NC 0031836)
3 Highest Days
Flow (MGD)
16th
3.34
3rd
3.17
22nd
3.03
3-highest Days Average (GPD):
3180000
Monthly Average Flow (GPD):
2762300
Wtr GPDA e/Dwelling (Jun 2022)
266
W Factor:
1.15
Flow reduction (GPD/dwelling):
306
Flow reduction/BR (GPD) ('):
102
(1) Asumes 3 BR/dwelling unit.

Point of contact is the undersigned at phone [phone], email
[e-mail].
Sincerely,
William E. Vaughan, PE
Public Utilities Director
Cc: Scott Harrell, PE, Assistant City Manager

Attachment A
City of Statesville Purchased Water Summary
Total Sum of
Billed Total Sum of
3rd Creek 4th Creek Consumption Dwelling Units
Sum of Sum of
Month
Sum of Billed
Dwelling
Sum of Billed
Dwelling
Consumption
Units
Consumption
Units
_2022
37,214,964.04
42,517.00
93,644,846.94
101,363.00
130,859,810.99
143,880.00
1
2,692,222.34
3,392.00
6,643,643.08
8,137.00
9,335,865.42
11,529.00
10
2,990,254.09
3,630.00
7,939,026.87
8,577.00
10,929,280.96
12,207.00
11
2,867,211.30
3,649.00
7,878,320.31
8,597.00
10,745,531.60
12,246.00
12
2,973,940.37
3,661.00
7,837,533.51
8,648.00
10,811,473.88
12,309.00
2
2,722,674.06
3,410.00
6,663,214.82
8,210.00
9,385,888.88
11,620.00
3
2,673,552.53
3,441.00
6,597,742.02
8,345.00
9,271,294.55
11,786.00
4
2,909,331.02
3,501.00
7,309,853.13
8,402.00
10,219,184.15
11,903.00
5
3,026,095.86
3,503.00
7,716,161.86
8,409.00
10,742,257.72
11,912.00
6
3,587,343.47
3,529.00
9,033,777.43
8,465.00
12,621,120.91
11,994.00
7
3,695,556.61
3,578.00
8,869,028.04
8,504.00
12,564,584.65
12,082.00
8
3,370,159.38
3,608.00
8,913,237.12
8,517.00
12,283,396.50
12,125.00
9
3,706,623.02
3,615.00
8,243,308.75
8,552.00
11,949,931.77
12,167.00
Grand Total
37,214,964.04
42,517.00
93,644,846.94
101,363.00
130,859,810.99
143,880.00
Notes:
1. Billed consumption in cubic feet.
2. All dwellings for subsequent calculations are assumed to be three bedrooms.
3. Sum of monthly billed consumption devided by sum of dwelling units gives the highest
average gallons per day per dwelling.

Attachment B
Fourth Creek WWTP Calculation
4th Crk WWTP Basin: Billed Domestic Water By Month
Month
FT3 Billed
Days in Month
Qave (GPD)
Dwelling Units
GPDAVe/Dwelling
Jan-22
6,643,643
31
1603047
8,137
197
Feb-22
6,663,215
28
1780030
8,210
217
Mar-22
6,597,742
31
1591971
8,345
191
Apr-22
7,309,853
30
1822590
8,402
217
May-22
7,716,162
31
1861835
8,409
221
Jun-22
9,033,777
30
2252422
8,465
266
Jul-22
8,869,028
31
2140011
8,504
252
Aug-22
8,913,237
31
2150678
8,517
253
Sep-22
8,243,309
30
2055332
8,552
240
Oct-22
7,939,027
31
1915610
8,577
223
Nov-22
7,878,320
30
1964328
8,597
228
Dec-22
7,837,534
31
1891121
8,648
219
4th Crk WWTP: DMR Reported Flow, Jun 2022
Day
Flow (MGD)
1
2.62
2
3.05
3
3.17
4
2.73
5
2.87
6
2.81
7
2.70
8
2.72
9
2.75
10
2.67
11
2.48
12
2.63
13
2.60
14
2.97
15
2.46
16
3.34
17
2.97
18
2.76
19
2.55
20
2.79
21
2.72
22
3.03
23
2.31
24
2.74
25
2.55
26
2.73
27
2.74
28
2.88
29
2.72
30
2.79
Average:
2.76
Highest month
RECEIVED
AiPi� 03 �j�3
NCDEQ/DWR/NPDES

Attachment B
Fourth Creek WWTP Calculation (cont.)
3 Highest Days
Flow (MGD)
16th
3.34
3rd
3.17
22nd
3.03
3-highest Days Average (GPD):
3180000
Monthly A\terage Flow (GPD):
2762300
I&I Factor:
1.15
Flow reduction (GPD/dwelling):
306
Flow reduction/BR (GPn) (1)
102
(1) Asumes 3 BR/dwelling unit.

Division of Water Resources Guidance
Regarding Flow Reduction Requests 15A NCAC 02T .0114(f)
August 29, 2022
Background: 15A NCAC 02T .0114 sets forth the default wastewater design flow rates for non -discharge
wastewater systems permitted by the North Carolina Department of Environmental Quality (NCDEQ),
Division of Water Resources (DWR). 15A NCAC 02T .0114(f) provides a process by which the requesting
party may obtain an adjusted daily sewage flow design rate (Flow Reduction) that is different than the
default design flow rate set by rule. If the Flow Reduction request meets the requirements in 15A NCAC
02T .0114(f) and DWR issues a Flow Reduction, then the applicant may use the Flow Reduction in sewer
extension applications for permitted but not yet tributary and future connections to the system (forms
SSEA 04-16, ASEA 04-16, FTA 06-21 and local delegated program applications).
Purpose: The purpose of this guidance document is to provide nonbinding guidance to assist the
regulated community in preparing and submitting complete Flow Reduction requests that DWR can
efficiently process, to assist the regulated community in complying with the requirements set forth in
15A NCAC 02T .0114, and to provide reasonable scientific and engineering standards, consistent with
the intent of the rule and 15A NCAC 02T .0114(f)(2) where the data required by the rule is unavailable.
General guidance regarding Flow Reduction requests:
• Please fully and carefully read 15A NCAC 02T .0114(a-f) before submitting a Flow Reduction
request.
• Flow Reduction requests that contain all the necessary information in the format presented in
the "Example Flow Reduction Spreadsheet" (Attached) can be processed by DWR more quickly.
• All Flow Reduction requests must be submitted to the current Collection Systems Adjusted Daily
Sewage Flow Design Rates primary contact (Reviewing Engineer) found here:
https://deg.nc.gov/about/divisions/water-resources/water-quality-permitting/municipal-npdes-
pretreatment-and-collection-system/collection-systems. If the Reviewing Engineer is
unavailable, please contact the supervisor of the DWR Municipal Permitting Unit located in
Raleigh, North Carolina.
• A DWR issued Flow Reduction approval letter must be included in a sewer extension application
for the Flow Reduction to be considered in the permit for the project.
• There is no standardized form for Flow Reduction requests; however, all Flow Reduction
requests must satisfy the requirements in 15A NCAC 02T .0114(f)(1)(A-H). Please note that no
fee is necessary for a Flow Reduction request review at this time. Please see the item by item
guidance for 15A NCAC 02T .0114(f)(1)(A-H) below.
• Flow Reduction requests must include the information and data required by 15A NCAC 02T
.0114(f). If, after good faith efforts, it is not possible to obtain monthly and/or daily wastewater
flow data specific to the representative facility, the requesting party can submit billed water
data in the Flow Reduction request in accordance with 15A NCAC 02T .0114(f)(2) in lieu of
wastewater flow data. Please see the Guidance Regarding the Use of Billed Water Data for a
Flow Reduction Requests below for detailed procedures on how to submit this data.

• The Flow Reduction request process set forth in 15A NCAC 18A .1949(c) does not apply to non -
discharge wastewater permits issued by DWR. 15A NCAC 18A .1949(c) applies to sub -surface
septic systems that are under the jurisdiction of the Department of Health and Human Services.

North Carolina Administrative Code for Flow Reduction Requests [15A NCAC 02T .0114(f)(1)(A-H)]:
(f) An adjusted daily sewage flow design rate shall be granted for permitted but not yet
tributary connections and future connections tributary to the system upon showing that
the capacity of a sewage system is adequate to meet actual daily wastewater flows from
a facility included in Paragraph (b) or (c) of this Rule without causing flow violations at
the receiving wastewater treatment plant or capacity -related sanitary sewer overflows
within the collection system as follows:
Guidance: Please provide the permit number of the receiving wastewater treatment plant or facility if
applicable (usually NC00##### or WQ00#####) so that downstream capacity can be verified. A Flow
Reduction only applies to permitted but not yet tributary connections and future connections tributary
to the system. This means that if the sewer system is already built and conveys actual flow, the Flow
Reduction cannot apply to it retroactively. If the system is permitted and even constructed, but does
not convey actual flow yet, a Flow Reduction could apply to it if a sewer extension permit modification
application is submitted to DWR that includes the Flow Reduction and the sewer extension permit
modification is issued.
(f)(1) Documented, representative data from that facility or a comparable facility shall
be submitted by an authorized signing official in accordance with Rule .0106 of this
Section to the Division for all flow reduction requests, as follows:
Guidance: Separate data from a representative facility must be submitted for each facility category. For
example, if the request is for a Flow Reduction for single- and multi -family residences, separate
representative data must be submitted for each of these categories before an approval letter can be
issued. This would also apply to facilities with multiple uses, such as a church with an attached
warehouse.
(f)(1)(A) dates of flow meter calibrations during the time frame evaluated and indication
if any adjustments were necessary;
Guidance: Documentation must be provided that confirms the most recent of the following events;
when flow meters were initially installed, replaced or calibrated. Typically, a conservative adjustment
will not be applied to the Flow Reduction if the most recent date is within 15 years.
(f)(1)(8) a breakdown of the type of connections (e.g. two bedroom units, three bedroom
units) and number of customers for each month of submitted data as applicable.
Identification of any non-residential connections including subdivision clubhouses and
pools, restaurants, schools, churches and businesses. For each non-residential
connection, information identified in Paragraph (c) of this Rule (e.g. 200 seat church, 40
seat restaurant, 35 person pool bathhouse);

Guidance: All Flow Reductions must be standardized to the applicable facility category in 15A NCAC 02T
.0114(a-d). As such, the appropriate number of units must be given to determine the Flow Reduction.
For example, if a Flow Reduction request is made for single-family residences, then the total number of
bedrooms in the development must be given or alternatively, the average number of bedrooms per
residence and total number of residences. If the request is for a general business and office facility,
then the total number of employees per shift must be given. If the request is for public access
restrooms, then the total number of plumbing fixtures must be given, etc.
(f)(1)(C) a letter of agreement from the owner or an official, meeting the criteria of Rule
.0106 of this Section, of the receiving collection system or treatment works accepting the
wastewater and agreeing with the adjusted design rate;
Guidance: A letter must be provided from the owner of the downstream wastewater treatment facility
that specifically accepts the requested Flow Reduction for the specific facility or facilities. This letter
must be signed by an authorized signatory according to 15A NCAC 02T .0106. Attachment 1 contains an
example of an acceptable letter of agreement.
(f)(1)(D) age of the collection system;
Guidance: This is typically a range of years beginning with the construction of the initial system and any
subsequent additions to the system and/or rehabilitations of the system.
(f)(1)(E) analysis of inflow and infiltration within the collection system or receiving
treatment plant, as applicable;
Guidance: This is typically included within the daily wastewater flow data required below, however,
conservative adjustments may need to be incorporated into the calculation in certain circumstances
such as when the facility is located a large distance away from the wastewater treatment plant or there
are excessive inflow and infiltration issues in the downstream collection system.
(f)(1)(F) if a dedicated wastewater treatment plant serves the specific area and is
representative of the residential wastewater usage, at least the 12 most recent
consecutive monthly average wastewater flow readings and the daily total wastewater
flow readings for the highest average wastewater flow month per customers, as
reported to the Division,
Guidance: All wastewater treatment plants/facilities must provide daily flow data through their
submitted Daily Monitoring Reports, however, the wastewater treatment plant typically serves many
customers in addition to the representative facility, making it difficult to obtain the data needed for the
Flow Reduction request. If the data for customers not associated with the representative facility can be
extracted out easily with calculations justifying the reduction, then DWR would accept this method of
calculation. "Most recent consecutive" means a 12-month period with the last month no more than 3-
months in the past from the date of submittal. For example, if the Flow Reduction request was
submitted in June of 2023, then data would need to be submitted from March 2022 to February 2023 or
a more recent 12-month period. For the month during this 12-month period with the highest monthly
average flow, submit the daily average flows for each day within that month.

(fJ(1)(G) if daily data from a wastewater treatment plant cannot be used or is not
representative of the project area: 12-months' worth of monthly average wastewater
flows from the receiving treatment plant shall be evaluated to determine the peak
sewage month. Daily wastewater flows shall then be taken from a flow meter installed
at the most downstream point of the collection area for the peak month selected that is
representative of the project area. Justification for the selected placement of the flow
meter shall also be provided, and
Guidance: When it is not possible to use daily wastewater treatment plant/facility flow data or it is not
available, the requestor may use a combination of monthly average flows to determine the greatest
flow month and daily flows from a flow meter downstream of the representative facility that only serves
that facility for the month with the highest wastewater flow. If a complicated situation exists, please
contact the current Reviewing Engineer for more information.
(f)(1)(H) an estimated design daily sewage flow rate shall be determined by calculating
the numerical average of the top three daily readings for the highest average flow
month. The calculations shall also account for seasonal variations, excessive inflow and
infiltration, age and suspected meter reading and recording errors.
Guidance: This calculation determines the tentative flow reduction value however, this value may be
modified conservatively for the factors mentioned in the rule above. In instances where there are
clearly excessive flow measurements due to extreme weather events such as hurricanes or other
unusual circumstances, these high flow days can be eliminated from the data set if properly justified. A
particularly rainy day is not considered a justification for data removal. If there are anomalies in the
data set such as when multiple days of flow monitoring are missing or clearly inaccurate measurements
exist, the data may be determined to be unrepresentative and new data must be provided. This
calculation is to be used for both 15A NCAC 02T .0114(f)(1)(F) & (G).
Additional Guidance Regarding Flow Reduction Requests:
• Based on historical data from previous flow reduction reviews, the minimum Flow Reduction
that will be approved is half of the 15A NCAC 02T .0114(a-e) rates. For example, 60 gallons per
day (GPD) per bedroom for single-family or multi -family residences, 12.5 GPD per employee per
shift for general business and office facilities or 7.5 GPD per student for schools with cafeteria,
gym and shower facilities, etc.
• According to 15A NCAC 02T .0114(b), one- and two -bedroom residences will have a minimum of
120 gallons per day per bedroom. This means that the minimum number of bedrooms per
residence is effectively two.
• The Flow Reduction approval letter will include language that requires new data be submitted
by a certain date (roughly 8-years in the future to coincide with System Wide Collection System
permit renewal cycles) to confirm that the Flow Reduction is still valid, otherwise the Flow
Reduction approval letter will become null and void. This does not rescind sewer extension
permits with previously applied Flow Reductions, but the applicant would not be able to use the
Flow Reduction for new sewer extension applications after the date of expiration unless the
applicant requests and is issued a new Flow Reduction approval letter by DWR.

Guidance Regarding the Use of Billed Water Data for Flow Reduction Requests:
If, after good faith efforts, it is not possible to obtain all wastewater flow data required by 15A NCAC 02T
.0114(f)(1), the requesting party may submit to DWR monthly billed water data per 15A NCAC 02T
.0114(f)(2) as described below. Submittal of billed water data can, in the circumstances described
above, be used to satisfy missing data required by 15A NCAC 02T .0114(f)(1)(E-H) listed above. All other
information/data required, including 15A NCAC 02T .0114(f)(1)(A-D) must be submitted to DWR as
required. Attachment 2 provides an example of an acceptable billed water data spreadsheet. Please
modify the sample billed water data spreadsheet and the procedure below as necessary for other facility
categories or special circumstances.
1. Gather and submit at least the 12 most recent consecutive monthly average billed water used
for the representative facility. This is typically 12-months of water bills. "Most recent
consecutive" is defined the same as in the guidance above for 15A NCAC 02T .0114(f)(1)(F).
2. Input these 12-months of billed water data into a spreadsheet and divide them by the total
number of days in each month or billing period to get the monthly average flow in GPD.
3. Divide each month's average monthly flow by the total number of bedrooms or by the number
of residences multiplied by the average number of bedrooms per residence to normalize the
data into GPD/bedroom. Highlight the month with the highest flow/bedroom. This is the base
flow reduction value.
4. Retrieve daily flows from the daily monitoring reports for the receiving wastewater treatment
plant/facility for the month calculated in step 3 above and input these into the spreadsheet.
Highlight the three highest flow days.
5. Average the three highest flow days.
6. Average all the daily flows.
7. Calculate an inflow & infiltration (I&I) factor by dividing the number in step 5 by the number in
step 6
8. Multiply the base flow reduction in step 3 by the I&I factor in step 7. This is the tentative flow
reduction value and is the basis for the final approved Flow Reduction.
In certain cases, the billed water data will include irrigation flows which are unlikely to enter the sewer
system as wastewater. If the requestor wants irrigation flows to be removed from the calculation, the
requestor must provide DWR with a clear and reasonable estimation of these flows through an
engineering justification. Irrigation data may not be excluded from the calculation unless approved by
DWR.

Attachment 1
Example Letter of Agreement per 15A NCAC 02T .0114(f)(1)(c)
)une 30, 2022
Mr. Charlie Miller, P.E.
Engineer, Municipal Permitting unit
Division of Water Resources, Nc DEQ
1617 Mail Service Center
Raleigh, NC 27699-1617
Re: Stateside Development Flow Reduction Request
Flows Tributary to Stateside WWTP WQD035809
Wastewater Treatment PlantfFacility
and Permit No. is Indicated
Dear Mr. Miller: WastewaterTreatment PIantlFacIlity
Owner is Indicated
Old North State Water Company, LLC, is the Owner of the Stateside Wastewater
Treatment Plant, ONSWC requested Diehl & Phillips, P.A. perform an analysis of the
plants flow data and the number of tributary bedrooms, in accordance with method
described In 15A NCAC 02T .0114(f). The results of the analysis indicated an adjusted
daily design flaw (Flow reduction) for future collection system extensions would be
appropriate. The analysis indicated the reduced flow rate could be 56.1 gallons per day
per bedroom, The data also indicates the average number of bedrooms per tributary
residence is four. Flow Reduction Request
Value Indicated
Based on this analysis, Old North State Water mpany, LLC requests the Division
approve an adjusted daily design flow rate of 60 gallons per day per bedroom, or 240
gallons per day per single family residence, for future collection system extensions
tributary to the Stateside WWTP. Facility Category Indicated
Thank you for your consideration of this request.
YpuSs truly, ,
Signed by an Authorized
Signatory According to
15A NCAC 02T . 0106 Sean McMillan
Chief operating Officer
Old North State Water Co., LLC

Attachment 2
Example Method for Billed Water Data Spreadsheet
Billed Water Data by Month
Month Gallons Billed Days in Month Avg. Monthly Flow (GPD) Total Bedrooms GPD/bedroom
Feb-20
581943
29
20067
533
37.6
Mar-20
671553
31
21663
554
39.1
Apr-20
672630
30
22421
563
39.8
May-20
746418
31
24078
586
41.1
Jun-20
785250
30
26175
600
43.6
Jul-20
908393
31
29303
633
46.3 Highest Month
Aug-20
892118
31
28778
664
43.3
Sep-20
810870
30
27029
668
40.5
Oct-20
859630
31
27730
687
40.4
Nov-20
894150
30
29805
713
41.8
Dec-20
948538
31
30598
743
41.2
Jan-21
1006818
31
32478
773
42.0
lal WWTP NDMRs July 2020
Flow (GPD) Day
Flow (GPD)
3 Highest Days Flow (GPD)
1st
20650
16th
26003
3rd 32736
2nd
29743
17th
28217
12th 32557
3rd
32736
18th
22224
29th 36138
4th
29741
19th
24705
5th
30334
loth
31537
Average = 33810
6th
32081
21st
30911
7th
28411
22nd
25749
Monthly Average Flow (GPD)
8th
32396
23rd
29940
9th
31721
24th
31305
Average = 29303
loth
30177
25th
30131
llth
27918
26th
31837
1&IFactor (3 Highest/Monthly Avg)
12th
32557
27th
31320
13th
27752
29th
32137
1&1Factor=
14th
24309
29th
36138
15th
31762
30th
28047
Flow Reduction (GPD/bdrm'I&I Factor)
31st
26008
Flow Reduction =
A Flow Reduction of 60 GPD/Bedroom would be granted.