NC0085812_Fact Sheet_20220512

Fact Sheet
NPDES Permit No. NC0085812
Permit Writer/Email Contact: Derek Denard/[e-mail]
Date: 12May2022
Division/Branch: NC Division of Water Resources/Water Quality Permitting Section
Compliance & Expediated Permitting Branch
Fact Sheet Template: Version 28Mar2019
Permitting Action:
❑ Renewal
❑ Renewal with Expansion
❑ New Discharge
Modification (Fact Sheet should be tailored to mod request)
See Permit Application Attachment A NC0085812 Modification Request_20210511_142p
Complete applicable sections below. If not applicable, enter NA.
1. Basic Facility Information
Facility Information
Applicant/Facility Name:
Union County Public Works / Grassy Branch WWTP
Applicant Address:
500 N Main St, Ste 918, Monroe, NC 28112
Facility Address:
1629 Old Fish Road (offNCSR 1610), Monroe, NC 28110
Permitted Flow:
modification to from 0.050 MGD to 0.120 MGD
Facility Type/Waste:
Municipal Wastewater Discharge, < 1MGD, 100% domestic
Facility Class:
Grade II Biological WPCS
Treatment Units:
See below
Pretreatment Program (Y/N)
No
County:
Union
Region
Mooresville
Treatment Units: An existing 0.05 MGD wastewater treatment facility that includes the following
wastewater treatment components:
• an influent pump station
• a manual bar screen
• two (2) flow equalization basins
• two (2) aeration basins
• two (2) secondary clarifiers
Page 1 of 11

• aerated sludge digester
• two (2) tertiary filters
• ultraviolet disinfection
• backup chlorination/dechlorination
• continuous flow measurement
• standby power
After receipt of an Authorization to Construct and submittal of an Engineers Certification for expansion
to 0.120 MGD, operate wastewater treatment plant consisting of the following components:
• an influent pump station
• two (2) manual bar screens
• three (3) flow equalization basins
• three (3) aeration basins
• three (3) secondary clarifiers
• three (3) aerated sludge digesters
• three (3) tertiary filters
• a disc filter
• ultraviolet disinfection
• backup chlorination/dechlorination
• continuous flow measurement
• standby power
Briefly describe the proposed permitting action and facility background: Union County has applied for a
modification to increase the permitted flow from 0.050 MGD to 0.120 MGD.
2. Receiving Waterbodv Information:
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
Outfall 001 / Crooked Creek
Stream Segment:
13-17-20
Stream Classification:
C
Drainage Area (mi2):
43.9
Summer 7Q10 (cfs)
0
Winter 7Q10 (cfs):
0.4
30Q2 (cfs):
---
Average Flow (cfs):
0.6
IWC (% effluent):
100
303(d) listed/parameter:
No. See Attachment B NC_2020_INTEGRATED _REPORT 1293
Subject to TMDL/parameter:
No
Basin/Sub-basin/HUC:
Yadkin -Pee Dee / 03-07-12 / 030401050702
USGS Topo Quad:
Stanfield, NC
Page 2of11

3. Effluent Data Summary
Effluent data for Outfall 001 is summarized below for the period of Nov2018 through Oct2021.
Table. Effluent Data Summary Outfall 001 (Compete table below or insert Excel Pivot Table.)
Limits
Parameter
L-J00010 - Temperature,
Water Deg_ Centigrade
H 00300 - Oxygen, Dissolved
(DO)
Location L
Effluent
Effluent
a 00340 - Oxygen Demand,
Chem. (Figh Level) (COD)
Effluent
Influent
e 00400 - • Effluent
A 00410 - Akalinity, Total (as Effluent
CaCO3)
Influent
0 31616 - Coliform, Fecal MF, Effluent
MFC Broth, 44.5 C
El 50050 - Flaw, in conduit or
thru treatment plant
Effluent
J C0530 - Solids, Total
Suspended- Concentration
Effluent
Influent
Data
Max !An
27.5 6.8
24.7 6.3
Awrag
18.0
9.4
Count
315
313
280 15
43.0
16
MA WA DM UoM
deg C
Daily Average >_ 6.0 mg/L
1300 120
9.97 6.3
514.4
18
314
118 13.4
55.4
300 125
221.0
12500 1 243.r/
0.374 0.009 0.048
177 2.5 6.1
11
mgn
mgn
mgn
>_ 6.0 and <9.0 standaunits) su
rd mgn
11 mg/l
166 200 400 #/100ml
1096 0.05* mgd
161 30.01 45.0 mg/l
1270, 34.1 300.4 161 mgll
MA = Monthly Average Limit, WA = Weekly Average Limit, DM = Daily Maximum Limit, UoM = Unit of Measure
* = Flow expansion from 0.050 to 0.120
+ = Changed from 5 to 6 per 15A NCAC 02B _0206_ Note the 3 year minimum is 6.3 mg/1.
Page 3 of 11

Parameter ' Locati
J CO310 - BOD, 5-Day (20
Deg. C) - Concentration
Data
Month Max Min Average
1
2
23.3
10
2
2.2
5.1
5.6
54.5 2 8.3
193 2 15.2
5 2 2.8
2.6 2 2.1
7.3 2 2.5
3.31 2 2.2
2.1 2 2.0
3.1 _ 2 2.2
7.1 2 3.0
Count
13
12
14
18
Limits
MA IWA
10.0 15.0
10.0 15.0
UoM
nun
10.0 15.0 mgil
5.0 7.5 mgil
7.5 mgil
7.5 mgil
5.0 7.5 mgil
7.5 mgll
7.5 mgil
7.5 mgil
15.0 mgil
10.0 15.0 mgil
12 5.0
14 5.0
13i
14
12
5.0
5.0
13
12
5.0
10.0
16.1 2 4.4 14
193 2 5.0 161
11 nfluent
3
4
5
6
J CO610 - Nitrogen,
Ammonia Total (as N) -
Concentration
1
7
8
9
J Influent
Influent Total
166 53.5 108.0 13
253 57 119.3 12
229
359
225
912
64.2 141.9 14
65.7 163.1 18
101 161.1 12
79 260.3 14
906 143 386.2 12
254 77.3 145.9 14
832 113 264.3 12
282 93 157.5 13
486 33.5 141.4 12
454 48.7 141.8 14
3.3
0.22
0.84
0.92
0.1
180.7 160
0.6
13
0.1 0.9 12
0.1 0.7 14
0.1 1.2 18
0.1 0.6 12
0.1 0.1 14
0.1
0.1
0.1
0.78 0.1
0.1
0.1
0.1
0.2
0.4
0.2
0.3
1.5
11 23.1
13 33.5
47 15 30.2
51 27 38.9
40 21 29.6
31 19.94 26.9
46.14 7.84 28.1
45.58 10 31.0
45.36 17 32.3
40 14 25.3
12 23.3
51, 7.84 28.6
13
14
12
4
12
4 12
4 12
2 6
2 6 mgil
2 6 mgil
nun
nun
nun
mgn
nun
nnsil
nun
nun
nun
nun
nun
nngn
nun
2
2
2
13 2
12 4
14
161
13
6
6
6
6
12
4 12
12
12
14
8
9
9
14
12
13
12 mgil
14 ng/
142 mgil
nun
nun
nun
nun
nun
nun
nUn
nngil
nign
Page 4 of 11

4. Instream Data Summary
Instream monitoring may be required in certain situations, for example: 1) to verify model predictions
when model results for instream DO are within 1 mg/1 of instream standard at full permitted flow; 2) to
verify model predictions for outfall diffuser; 3) to provide data for future TMDL; 4) based on other
instream concerns. Instream monitoring may be conducted by the Permittee, and there are also
Monitoring Coalitions established in several basins that conduct instream sampling for the Permittee (in
which case instream monitoring is waived in the permit as long as coalition membership is maintained).
If applicable, summarize any instream data and what instream monitoring will be proposed for this
permit action: Monitoring Coalition maintains data.
Is this facility a member of a Monitoring Coalition with waived instream monitoring (Y/N): Yes.
Name of Monitoring Coalition: Yadkin Pee Dee River Basin Association.
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): There are numerous violations
and enforcements for BOD, Fecal Coliform, Flow, Ammonia, and TSS. [See Attachment C and D].
Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): Aquatic toxicity monitoring is not required.
Summarize the results from the most recent compliance inspection: See the Attachment E for the April 3,
2019 Compliance Evaluation Inspection and Attachment F for the July 7, 2020 Reconnaissance
Inspection.
6. Water Quality -Based Effluent Limitations (WQBELs)
Dilution and Mixing Zones
In accordance with 15A NCAC 2B.0206, the following streamflows are used for dilution considerations
for development of WQBELs: 1Q10 streamflow (acute Aquatic Life); 7Q10 streamflow (chronic Aquatic
Life; non -carcinogen HH); 30Q2 streamflow (aesthetics); annual average flow (carcinogen, HH).
If applicable, describe any other dilution factors considered (e.g., based on CORMIX model results): A
QUAL2K model (04Dec2019) for Crooked Creek was provided by Tetra Tech. See Attachment A.
Drainage Area (mi2):
43.9 was indicated in the 08Ju11998 WLA. See Attachment G. (the QUAL2K
model discussed —50)
Summer 7Q10 (cfs)
Effectively 0. The QUAL2K model gives 0.050.
Winter 7Q10 (cfs):
0.503 (model); previously 0.4 in the 08Ju11998 WLA.
30Q2 (cfs):
---
Average Flow (cfs):
0.6 (08Ju11998 WLA)
IWC (% effluent):
100
If applicable, describe any mixing zones established in accordance with 15A NCAC 2B. 0204(b): NA.
Page 5 of 11

Oxygen -Consuming Waste Limitations
Limitations for oxygen -consuming waste (e.g., BOD) are generally based on water quality modeling to
ensure protection of the instream dissolved oxygen (DO) water quality standard. Secondary TBEL limits
(e.g., BOD= 30 mg/1 for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
If permit limits are more stringent than TBELs, describe how limits were developed: QUAL2K Model
[Attachment A] and flow design criteria for new and expanding discharges to zero flow streams (7Q10 =
0 and 30Q2 > 0) [15A NCAC 02B .0206].
Ammonia and Total Residual Chlorine Limitations
Limitations for ammonia are based on protection of aquatic life utilizing an ammonia chronic criterion of
1.0 mg/1 (summer) and 1.8 mg/1 (winter). Acute ammonia limits are derived from chronic criteria,
utilizing a multiplication factor of 3 for Municipals and a multiplication factor of 5 for Non -Municipals.
Limitations for Total Residual Chlorine (TRC) are based on the NC water quality standard for protection
of aquatic life (17 ug/1) and capped at 28 ug/1 (acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/1 are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: No changes for
Ammonia or TRC for this modification.
Reasonable Potential Analysis (RPA) for Toxicants
Not applicable.
Toxicity Testing Limitations
Permit limits and monitoring requirements for Whole Effluent Toxicity (WET) have been established in
accordance with Division guidance (per WET Memo, 8/2/1999). Per WET guidance, all NPDES permits
issued to Major facilities or any facility discharging "complex" wastewater (contains anything other than
domestic waste) will contain appropriate WET limits and monitoring requirements, with several
exceptions. The State has received prior EPA approval to use an Alternative WET Test Procedure in
NPDES permits, using single concentration screening tests, with multiple dilution follow-up upon a test
failure.
Describe proposed toxicity test requirement: Not required.
Mercury Statewide TMDL Evaluation
There is a statewide TMDL for mercury approved by EPA in 2012. The TMDL target was to comply with
EPA's mercury fish tissue criteria (0.3 mg/kg) for human health protection. The TMDL established a
wasteload allocation for point sources of 37 kg/year (81 lb/year), and is applicable to municipals and
industrial facilities with known mercury discharges. Given the small contribution of mercury from point
sources (-2% of total load), the TMDL emphasizes mercury minimization plans (M1VIPs) for point source
control. Municipal facilities > 2 MGD and discharging quantifiable levels of mercury (>1 ng/1) will
Page 6 of 11

receive an MMP requirement. Industrials are evaluated on a case -by -case basis, depending if mercury is a
pollutant of concern. Effluent limits may also be added if annual average effluent concentrations exceed
the WQBEL value (based on the NC WQS of 12 ng/1) and/or if any individual value exceeds a TBEL
value of 47 ng/1.
Describe proposed permit actions based on mercury evaluation: Not evaluated for this permit
modification.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit: NA.
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: NA.
If applicable, describe any special actions (HQW or ORW) this receiving stream and classification shall
comply with in order to protect the designated waterbody: NA.
If applicable, describe any compliance schedules proposed for this permit renewal in accordance with
15A NCAC 2H.0107(c) (2) (B), 40CFR 122.47, and EPA May 2007 Memo: NA.
If applicable, describe any water quality standards variances proposed in accordance with NCGS 143-
215.3(e) and 15A NCAC 2B. 0226 for this permit renewal: NA.
7. Technology -Based Effluent Limitations (TBELs)
Municipals (if not applicable, delete and skip to Industrials)
Are concentration limits in the permit at least as stringent as secondary treatment requirements (30 mg/l
BOD5/TSS for Monthly Average, and 45 mg/l for BOD5/TSS for Weekly Average). Yes.
If NO, provide a justification for alternative limitations (e.g., waste stabilization pond). NA.
Are 85% removal requirements for BOD5/TSS included in the permit? Yes.
If NO, provide a justification (e.g., waste stabilization pond). NA.
8. Antidegradation Review (New/Expanding Discharge):
The objective of an antidegradation review is to ensure that a new or increased pollutant loading will not
degrade water quality. Permitting actions for new or expanding discharges require an antidegradation
review in accordance with 15A NCAC 2B.0201. Each applicant for a new/expanding NPDES permit must
document an effort to consider non -discharge alternatives per 15A NCAC 2H.0105( c)(2). In all cases,
existing instream water uses and the level of water quality necessary to protect the existing use is
maintained and protected.
If applicable, describe the results of the antidegradation review, including the Engineering Alternatives
Analysis (EAA) and any water quality modeling results: An EAA review was conducted on 04Jan2022.
The alternatives that were considered included the following: no action, infiltration and inflow (I&I)
Page 7 of 11

reduction, connection to other POTWs, land application ($7,720,000), non -conjunctive reuse
($8,550,0000, and expansion of the Grassy Branch WRF ($5,140,000). The alternatives were either cost
prohibitive and/or technically infeasible.
9. Antibacksliding Review:
Sections 402(o)(2) and 303(d)(4) of the CWA and federal regulations at 40 CFR 122.44(1) prohibit
backsliding of effluent limitations in NPDES permits. These provisions require effluent limitations in a
reissued permit to be as stringent as those in the previous permit, with some exceptions where limitations
may be relaxed (e.g., based on new information, increases in production may warrant less stringent TBEL
limits, or WQBELs may be less stringent based on updated RPA or dilution).
Are any effluent limitations less stringent than previous permit (YES/NO): The permitted flow will be
increased from 0.050 MGD to 0.120 MGD.
If YES, confirm that antibacksliding provisions are not violated: Expansion for flow was based on a
QUAL2K model.
10. Monitoring Requirements
Monitoring frequencies for NPDES permitting are established in accordance with the following
regulations and guidance: 1) State Regulation for Surface Water Monitoring, 15A NCAC 2B.0500; 2)
NPDES Guidance, Monitoring Frequency for Toxic Substances (7/15/2010 Memo); 3) NPDES Guidance,
Reduced Monitoring Frequencies for Facilities with Superior Compliance (10/22/2012 Memo); 4) Best
Professional Judgement (BPJ). Per US EPA (Interim Guidance, 1996), monitoring requirements are not
considered effluent limitations under Section 402(o) of the Clean Water Act, and therefore anti -
backsliding prohibitions would not be triggered by reductions in monitoring frequencies.
For instream monitoring, refer to Section 4.
11. Electronic Reporting Requirements
The US EPA NPDES Electronic Reporting Rule was finalized on December 21, 2015. Effective
December 21, 2016, NPDES regulated facilities are required to submit Discharge Monitoring Reports
(DMRs) electronically. Effective December 21, 2020, NPDES regulated facilities will be required to
submit additional NPDES reports electronically. This permit contains the requirements for electronic
reporting, consistent with Federal requirements.
Page 8 of 11

12. Summary of Proposed Permitting Actions:
A. Table. Current Permit Conditions and Proposed Changes — Outfall 001 with 0.050 MGD Permitted Flow
Parameter
Current Permit
Proposed
Change
Basis for Condition/Change
Flow
MA 0.050 MGD
Expansion to
0.120 MGD
15A NCAC 2B .0505
BOD5
Summer:
No change
WQBEL. Based on protection of DO standard. 15A
NCAC 2B.0200
BOD5 = 5 mg/1. Flow design criteria for new and
expanding discharges to zero flow streams (7Q10 = 0
and 30Q2 > 0) [15A NCAC 02B .0206]
MA 5.0 mg/1
WA 7.5 mg/1
Winter:
MA 10.0 mg/1
WA 15.0 mg/1
NH3-N
Summer:
No change
WQBEL. Based on protection of State WQ criteria.
15A NCAC 2B.0200.
NH3-N = 2 mg/1. Flow design criteria for new and
expanding discharges to zero flow streams (7Q10 = 0
and 30Q2 > 0) [15A NCAC 02B .0206]
MA 2.0 mg/1
WA 6.0 mg/1
Winter:
MA 4.0 mg/1
WA 12.0 mg/1
TSS
MA 30 mg/1
WA 45 mg/1
No change
TBEL. Secondary treatment standards/40 CFR 133 /
15A NCAC 2B .0406
Fecal coliform
MA 200 /100m1
WA 400 /100m1
No change
WQBEL. State WQ standard, 15A NCAC 2B .0200
DO
? 5 mg/1
> 6 mg/1
WQBEL. State WQ standard, 15A NCAC 2B .0200
The original WLA gave a DO limit of 6.0. mg/1. See
Attachment G.
DO = 6 mg/1. Flow design criteria for new and
expanding discharges to zero flow streams (7Q10 = 0
and 30Q2 > 0) [15A NCAC 02B .0206]
pH
> 6.0 and < 9.0
SU
No change
WQBEL. State WQ standard, 15A NCAC 2B .0200
Temperature
Monitor &
Report
No change
WQBEL. State WQ standard, 15A NCAC 2B .0200
Total Residual
Chlorine (TRC)
Monitor &
Report
No change
WQBEL. State WQ standard, 15A NCAC 2B .0200
Electronic
Reporting
Included
Electronic
Reporting
Special
Condition
Updated
Electronic
Reporting
Special
Condition
In accordance with EPA Electronic Reporting Rule
2015.
MGD — Million gallons per day, MA — Monthly Average, WA — Weekly Average, DM — Daily Max
Page 9 of 11

The draft permit includes the following significant changes from the existing permit:
• The permit was modified for flow expansion from 0.050 MGD to 0.120 MGD. A second effluent
table is included for the flow modification. See Condition A. (2.).
• The limit for dissolved oxygen is changed to Daily Average > 6.0 mg/L. See Conditions A. (1.)
and (2.). This change is in accordance with flow design criteria for new and expanding discharges
to zero flow streams (7Q10 = 0 and 30Q2 > 0) [15A NCAC 02B .0206]. The original wasteload
allocation in 1996 indicated this limitation as well.
• The electronic reporting permit special condition A. (4.) was updated.
• The permit map was updated.
13. Public Notice Schedule:
Permit to Public Notice: January 15, 2022 [See Attachment H]
Per 15A NCAC 2H .0109 & .0111, The Division will receive comments for a period of 30 days following
the publication date of the public notice. Any request for a public hearing shall be submitted to the
Director within the 30 days comment period indicating the interest of the party filing such request and the
reasons why a hearing is warranted.
14. Fact Sheet Addendum (if applicable):
Were there any changes made since the Draft Permit was public noticed (Yes/No): Yes.
If Yes, list changes and their basis below:
This final permit includes the following changes from the draft permit previously sent to
you on January 11, 2022:
• Based on comments received from the permittee, the facility description on the
supplement to permit cover sheet was updated for the following:
a. The existing 0.05 MGD wastewater treatment facility description was corrected to
indicate "a flow equalization basin" instead of "two (2) equalization basins".
b. The expansion to 0.0120 wastewater treatment facility description was corrected by
indicating "two (2) flow equalization basins" instead of "three (3)" and by removing
the "three (3) tertiary filters". Also, this description has been updated to indicate "a
disc filter system" instead of "a disc filter'.
• The map was updated for the location of Outfall 001:
Latitude 35° 07' 52" and Longitude -80° 29' 39".
Page 10 of 11

15. Fact Sheet Attachments (list in order of reference):
A. NC0085812_Modification Request _20210511_142p
B. NC 2020 INTEGRATED REPORT 1293
C. NC0085812_Monitoring Report Violations _Nov2016_Oct2021_5p
D. NC0085812_Permit Enforcement History By Permit_2p
E. NC0085812_NPDES Inspection With Categories _20190403_7p
F. NC0085812_NPDES Inspection With Categories _20200707_3p
G. NC0085812_Wasteload Allocation_19980708_6p
H. NC0085812_Affidavit _20220204_lp
I. Peer Review 20220111lp
J. Permittee Comments_ Electronic Receipt _20220113_3p
K. Permittee Comments_NC0085812 MOD DRAFT 20220111_Markup_12p
L. L_Permittee Receipt _20220405_2p
Page 11 of 11

April 26, 2021
Mr. Mike Montebello
Water Quality Permitting Section — NPDES
Division of Water Resources
North Carolina Department of Environmental Quality
1617 Mail Service Center
Raleigh, NC, 27699-1617
RE: Union County Public Works
Grassy Branch Water Reclamation Facility
NPDES Permit Renewal, Permit No. NC0085812
Dear Mr. Montebello:
RECEIVED
MAY 11 2021
NCDEQ/DWR/NPDES
The Union County Public Works Division is permitted to discharge 0.05 million gallons per day (mgd) of
treated effluent from the Grassy Branch Water Reclamation Facility (WRF) to Crooked Creek via North
Carolina National Pollutant Discharge Elimination System (NPDES) Permit NC0085812. The County has
received Notice of Violations (NOVs) for flow, five-day biochemical oxygen demand (BOD5), ammonia
(NH3-N), fecal coliform, total suspended solids (TSS), and pH for the Grassy Branch WRF over the last
several years. The County has attributed the majority of the NOVs to record rainfall events in the region;
however, over -allocation of sewer connections to the Grassy Branch WRF has contributed to and
intensified the compliance issues. The Grassy Branch WRF flow and recorded rainfall data demonstrates
that the design flow capacity is exceeded during rain events. Influent flow peaks have exceeded a ratio of
7 to 1 (e.g., peaking factors greater than 7) compared to the design capacity of the Grassy Branch WRF.
To address the on -going violations at Grassy Branch, Union County has executed and submitted the
application form and required attachments to the Department of Environmental Quality (DEQ) Division
of Water Resources (DWR) for a Special Order by Consent (SOC). The Grassy Branch SOC package
requested an increase in design capacity from 0.05 to 0.12 mgd to address the over -allocation of sewer
connections. In response, DWR staff requested that the County's SOC application be amended to include
a National Pollutant Discharge Elimination System (NPDES) permit major modification to support the
County's request for a capacity increase.
The enclosed application is for the major modification of the Grassy Branch WRF NPDES permit. In
accordance with the requirements of federal (40 CFR 122) and state (15A NCAC 2H .0105(3))
regulations, we are submitting three signed copies of the completed application package and associated
attachments and figures. The application package includes the following information:
• NPDES Permit Application — EPA Form 2A (Sections 1 to 6, Table A, and Table B)
• EPA Form 2A Additional Information (Topographic Map, Process Flow Diagram, and Process
Narrative)

• Engineering Alternatives Analysis Technical Memorandum, with associated attachments.
If you have any questions regarding any of the NPDES permit major modification application materials,
please contact Andrew Neff, Water & Wastewater Division Director at [phone] or
[e-mail].
Sincerely
i
Hyong
Public Works Admin .tor
Attachments
cc:
Andrew Neff, P.E., Water & Wastewater Division Director
Bart Farmer, Union County Public Works, Water Reclamation Facilities Superintendent
Alex Latham, Union County Public Works, WRF Supervisor
Mary Sadler, PE, Hazen and Sawyer
Jim Struve, PE, Hazen and Sawyer

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No. 2040-0004
Form
2A
NPDES
:.EPA
U.S. Environmental Protection Agency
Application for NPDES Permit to Discharge Wastewater
NEW AND EXISTING PUBLICLY OWNED TREATMENT WORKS
SECTION
1. BASIC
APPLICATION INFORMATION
FOR ALL APPLICANTS (40 CFR 122.21(j)(1) and (9))
Facility Information
1.1
Facility name
Grassy Branch WRF
Mailing address (street or P.O. box)
4600 Goldmine Road
City or town
Monroe
State
NC
ZIP code
28112
Contact name (first and last)
Andrew Neff, P.E.
Title
Water and Wastewater Division Director
Phone number
[phone]
Email address
[e-mail]
Location address (street, route number, or other specific identifier) ❑ Same as mailing address
1629 Old Fish Road (Off NCSR 1610)
City or town
Monroe
State
NC
ZIP code
28110
1.2
Is this application for a facility that has yet to commence
❑ Yes 4 See instructions on data submission
requirements for new dischargers.
discharge?
✓ No
Applicant Information
1.3
Is applicant different from entity listed under Item
❑ Yes
1.1 above?
Item 1.4.
✓ No 4 SKIP to
Applicant name
Applicant address (street or P.O. box)
City or town
State
ZIP code
Contact name (first and last)
Title
Phone number
Email address
1.4
Is the applicant the facility's owner, operator, or both? (Check only one response.)
❑ Owner ❑ Operator
Both
✓
1.5
To which entity should the NPDES permitting
❑ Facility
authority
send correspondence? (Check only one response.)
Applicant ❑ Facility and applicant
(they are one and the same)
✓
Existing Environmental Permits
1.6
Indicate below any existing environmental permits. (Check all that apply and print or type the corresponding permit
number for each.)
Existing Environmental Permits
✓ NPDES
(discharges to surface
❑ RCRA (hazardous waste)
❑ UIC (underground injection
control)
water)
NC0085812
❑ PSD (air emissions)
❑ Nonattainment program (CAA)
❑ NESHAPs (CAA)
❑ Ocean dumping (MPRSA)
❑ Dredge or fill (CWA Section
404)
❑ Other (specify)
EPA Form 3510-2A (Revised 3-19)
Page 1

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No. 2040-0004
Collection System and Population Served
1.7
Provide the collection system information requested below for the treatment works.
Municipality
Served
Population
Served
Collection System Type
(indicate percentage)
Ownership Status
100 % separate sanitary sewer
0 Own 0 Maintain
Union County
129 Homes and
3 Schools
0 % combined storm and sanitary sewer
0 Own 0 Maintain
❑ Unknown
0 Own 0 Maintain
% separate sanitary sewer
0 Own 0 Maintain
% combined storm and sanitary sewer
0 Own 0 Maintain
0 Unknown
0 Own 0 Maintain
% separate sanitary sewer
0 Own 0 Maintain
% combined storm and sanitary sewer
❑ Own 0 Maintain
❑ Unknown
❑ Own 0 Maintain
% separate sanitary sewer
❑ Own 0 Maintain
% combined storm and sanitary sewer
0 Own 0 Maintain
❑ Unknown
0 Own ❑ Maintain
Total
Population
Served
129 Homes and
3 Schools
Separate Sanitary Sewer System
Combined Storm and
Sanitary Sewer
Total percentage of each type of
sewer line (in miles)
o
100 /o
o
o /o
Indian Country
1.8
Is the treatment works located in Indian
❑ Yes
Country?
✓
No
1.9
Does the facility discharge to a receiving
❑ Yes
water that flows through
✓
Indian Country?
No
Design and Actual
Flow Rates
1.10
Provide design and actual flow rates
in the designated spaces.
Design Flow Rate
0.05 mgd
Annual Average How Rates (Actual)
Two Years Ago
Last Year
This Year
0.06 mgd
0.04 mgd
0.05 mgd
Maximum Daily Flow Rates (Actual)
Two Years Ago
Last Year
This Year
0.37 mgd
0.30 mgd
0.19 mgd
Discharge Points
by Type
1.11
Provide the total number of effluent discharge points to waters of the United States by type.
Total Number of Effluent Discharge Points by Type
Treated Effluent
Untreated Effluent
Combined Sewer
Overflows
Bypasses
Constructed
Emergency
Overflows
1
0
0
0
0
EPA Form 3510-2A (Revised 3-19)
Page 2

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No. 2040-0004
Outfalls and Other Discharge or Disposal Methods
Outfalls Other Than to Waters of the United States
1.12
Does the POTW discharge wastewater to basins, ponds,
discharge to waters of the United States?
❑ Yes
or other
surface impoundments that do not have outlets for
4 SKIP to Item 1.14.
✓ No
1.13
Provide the location of each surface impoundment and associated discharge information in the table below.
Surface Impoundment Location and Discharge Data
Location
Average Daily Volume
Discharged to Surface
Impoundment
Continuous or Intermittent
(check one)
gpd
❑ Continuous
❑ Intermittent
gpd
0 Continuous
❑ Intermittent
gpd
0 Continuous
❑ Intermittent
1.14
Is wastewater applied to land?
❑ Yes
4 SKIP to Item 1.16.
✓ No
1.15
Provide the land application site and discharge data requested below.
Land Application Site and Discharge Data
Location
Size
Average Daily Volume
Applied
Continuous or
Intermittent
(check one)
acres
gp d
❑ Continuous
❑ Intermittent
acres
gp d
0 Continuous
❑ Intermittent
acres
gp d
0 Continuous
❑ Intermittent
1.16
Is effluent transported to another facility for treatment
❑ Yes
prior to discharge?
4 SKIP to Item 1.21.
✓ No
1.17
Describe the means by which the effluent is transported (e.g., tank truck, pipe).
1.18
Is the effluent transported by a party other
❑ Yes
than the applicant?
4 SKIP to Item 1.20.
✓ No
1.19
Provide information on the transporter below.
Transporter Data
Entity name
Mailing address (street or P.O. box)
City or town
State
ZIP code
Contact name (first and last)
Title
Phone number
Email address
EPA Form 3510-2A (Revised 3-19)
Page 3

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No. 2040-0004
Outfalls and Other Discharge or Disposal Methods Continued
1.20
In the table below, indicate the name, address, contact information, NPDES number, and average daily flow rate of the
receiving facility.
Receiving Facility Data
Facility name
Mailing address (street or P.O. box)
City or town
State
ZIP code
Contact name (first and last)
Title
Phone number
Email address
NPDES number of receiving facility (if any) 0 None
Average daily flow rate mgd
1.21
Is the wastewater disposed of in a manner other than
have outlets to waters of the United States (e.g., underground
❑ Yes
i
those already mentioned in Items 1.14 through 1.21 that do not
percolation, underground injection)?
No 4 SKIP to Item 1.23.
1.22
Provide information in the table below on these other disposal methods.
Information on Other Disposal Methods
Disposal
Method
Description
Location of
Disposal Site
p
Size of
Disposal Site
p
Annual Average
Daily Discharge
Volume
Continuous or Intermittent
(check one)
acres
gpd
0 Continuous
❑ Intermittent
acres
gpd
❑ Continuous
❑ Intermittent
acres
gpd
❑ Continuous
0 Intermittent
Variance
Requests
1.23
Do
Consult
❑
you intend to request or renew one or more of the variances authorized at 40 CFR 122.21(n)? (Check all that apply.
with your NPDES permitting authority to determine what information needs to be submitted and when.)
Discharges into marine waters (CWA ❑ Water quality related effluent limitation (CWA Section
Section 301(h)) 302(b)(2))
Not applicable
Contractor Information
1.24
Are any operational or maintenance aspects (related to
the responsibility of a contractor?
❑ Yes ✓
wastewater treatment and effluent quality) of the treatment works
No +SKIP to Section 2.
1.25
Provide location and contact information for each contractor in addition to a description of the contractor's operational
and maintenance responsibilities.
Contractor Information
Contractor 1
Contractor 2
Contractor 3
Contractor name
(company name)
Mailing address
(street or P.O. box)
City, state, and ZIP
code
Contact name (first and
last)
Phone number
Email address
Operational and
maintenance
responsibilities of
contractor
EPA Form 3510-2A Revised 3-19)
Page 4

EPA Identification Number
110009720506
SECTION 2. ADDITIONAL INFORMATION
NPDES Permit Number Facility Name
NC0085812 Grassy Branch WRF
(40 CFR 122.21(j)(1) and (2))
Form Approved 03/05/19
OMB No. 2040-0004
o
Outfalts to Waters of the United States
•�'
a,
0
2.1
Does
✓
the treatment works have a design flow greater than or equal to 0.1 mgd?
Note: Major mod request to
Yes expand from 0.05 to 0.12 mgd ❑ No 4 SKIP to Section 3.
Inflow and Infiltration
2.2
Provide the treatment works' current average daily volume of inflow
Average Daily Volume of Inflow and Infiltration
and infiltration.
Not quantifiable, Max day PF 7:1 gpd
Indicate the steps the facility is taking to minimize inflow and infiltration.
The County has actively been involved in the reduction of infiltration and inflow (MI) in the collection system. A Phase 1 I&I study was commissioned in
2016 to broadly determine problem areas. A Phase 2 study in 2017 focused on repair efforts readily identified in the Phase 1 study. The Phase 2 study also
included wet weather monitoring. In 2018, Phase 3 efforts included confirming the effectiveness of previous repair efforts, extensive closed-circuit
television (CCTV) review of the entire collection system, and the continuation of repair efforts. Phase 4 of the I&I reduction effort was initiated in January
2019. This phase consists of a review of dry and wet weather data and patterns and on -going inspection of the collection system. +
Topographic
Map
2.3
Have
specific
✓
you attached a topographic map to this application that contains all the required information? (See instructions for
requirements.)
Yes ❑ No
Flow
Diagram
2.4
Have
(See
✓
you attached a process flow diagram or schematic to this application that contains all the required information?
instructions for specific requirements.)
Yes ❑ No
Scheduled Improvements and Schedules of Implementation
2.5
Are
1
improvements to the facility scheduled?
Yes ❑ No 4 SKIP to Section 3.
Briefly list and describe the scheduled improvements.
1 Scheduled improvements for an expansion from 0.05 mgd to 0.12 mgd include larger influent pumps, retrofit of the
existing aeration basin. one additional package secondary treatment train, and new positive displacement blowers.
2 Improvements also include an additional secondary clarifier, a new cloth disk filter, new UV disinfection system and
aerobic digestion improvements.
3.
4.
2.6
Provide scheduled or actual dates of completion for improvements.
Scheduled or Actual Dates of Completion for Improvements
Scheduled
Improvement
(from above)
Affected
Outfalls
(list outfall
number)
Begin
Construction
(MM/DD/YYYY)
End
Construction
(MM/DD/YYYY)
Begin
Discharge
(MM/DD/YYYY)
Attainment of
Operational
Level
(MM/DD/YYYY)
1.
001
10/01/2023
10/01/2025
03/01/2026
03/01/2026
2.
001
10/01/2023
10/01/2025
03/01/2026
03/01/2026
3.
4.
2.7
Have appropriate permits/clearances
response.
❑ Yes
concerning other federal/state requirements been obtained? Briefly explain your
✓ No ❑ None required or applicable
Explanation:
Permits will be obtained prior to construction for the expansion of the facility from 0.05 to 0.12 mgd.
EPA Form 3510-2A (Revised 3-19)
Page 5

EPA Identification Number NPDES Permit Number Facility Name
110009720506 NC0085812 Grassy Branch WRF
Form Approved 03/05/19
OMB No. 2040-0004
Description of Outfalls
I
I 1 ' 1 . 1 1)(
Provide the following information for each outfall. (Attach additional
to ( ))
sheets if you have more than three outfalls.)
Outfall Number all
Outfall Number
Outfall Number
State
NC
County
Union County
City or town
Monroe
Distance from shore
111ft*
ft.
ft.
Depth below surface
NA ft.
ft.
ft.
Average daily flow rate
0.05 mgd
mgd
mgd
Latitude
35° 07' 50" N
° "
°
Longitude
so° 29' 40" W
°
Seasonal or Periodic Discharge Data
3.2
Do any of the outfalls described
❑ Yes
under Item 3.1 have seasonal or
periodic
✓
discharges?
No 4 SKIP to Item 3.4.
3.3
If so, provide the following information
for each applicable outfall.
Outfall Number
Outfall Number
Outfall Number
Number of times per year
discharge occurs
Average duration of each
discharge (specify units)
Average flow of each
discharge
mgd
mgd
mgd
Months in which discharge
occurs
Diffuser Type
3.4
Are
•
any of the outfalls listed under Item 3.1 equipped with a diffuser?
Yes
ID
No 4 SKIP to Item 3.6.
3.5
Briefly describe the diffuser type at each applicable outfall.
Outfall Number
Outfall Number
Outfall Number
Waters of
the U.S.
3.6
Does
discharge
✓
the treatment works discharge or plan to discharge wastewater to waters of the United States from one or more
points?
Yes ❑ No 4SKIP to Section 6.
EPA Form 3510-2A (Revised 3-19)
Page 6

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No. 2040-0004
Receiving Water Description
3.7
Provide the receiving water and related information (if known) for each outfall.
Outfall Number 001
Outfall Number
Outfall Number
Receiving water name
Crooked Creek
Name of watershed, river,
or stream system
Crooked Creek River Basin
U.S. Soil Conservation
Service 14-digit watershed
code
030401050702
Name of state
management/river basin
Yadkin Pee Dee
U.S. Geological Survey
8-digit hydrologic
cataloging unit code
03040105
Critical low flow (acute)
NA cfs
cfs
cfs
Critical low flow (chronic)
70.10 (Summer) =
0.004 cfs cfs
cfs
cfs
Total hardness at critical
low flow
mg/L of
NA CaCO3
mg/L of
CaCO3
mg/L of
CaCO3
Treatment Description
3.8
Provide the following information describing the treatment provided for discharges from each outfall.
Outfall Number 001 Outfall Number
Outfall Number
Highest Level of
Treatment (check all that
apply per outfall)
0 Primary
0 Equivalent to
secondary
0 Secondary
❑ Advanced
❑ Other (specify)
0 Primary
0 Equivalent to
secondary
0 Secondary
0 Advanced
0 Other (specify)
0 Primary
0 Equivalent to
secondary
0 Secondary
0 Advanced
0 Other (specify)
Design Removal Rates by
Outfall
001
BOD5 or CBOD5
96
TSS
97
Phosphorus
0 Not applicable
%
® Not applicable
® Not applicable
Nitrogen
10 Not applicable
%
® Not applicable
%
® Not applicable
%
Other (specify)
NH3-N
0 Not applicable
96 %
® Not applicable
® Not applicable
EPA Form 3510-2A (Revised 3-19)
Page 7

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No. 2040-0004
Treatment Description Continued
3.9
Describe the type of disinfection used for the effluent from each outfall in the table below. If disinfection varies by
season, describe below.
The Grassy Branch WRF relies on Ultraviolet disinfection at outfall 001.
Outfall Number
o01
0utfall Number
0utfall Number
Disinfection type
UV
Seasons used
Summer and Winter
Dechlorination used?
✓
Not applicable
❑ Not applicable
❑ Not applicable
❑ Yes
❑ Yes
❑ Yes
❑ No
❑ No
❑ No
Effluent Testing Data
3.10
Have you completed monitoring for all Table A parameters and attached the results to the app ication package?
✓ Yes ❑ No
3.11
Have you conducted any WET tests during the 4.5 years prior to the date of the application on any of the facility's
discharges or on any receiving water near the discharge points?
❑ Yes
✓ No 4 SKIP to Item 3.13.
3.12
Indicate the number of acute and chronic WET tests conducted since the last permit reissuance of the facility's
discharges by outfall number or of the receiving water near the discharge points.
0utfall Number
Outfall Number
0utfall Number
Acute
Chronic
Acute
Chronic
Acute
Chronic
Number of tests of discharge
water
Number of tests of receiving
water
3.13
Does the treatment works have a design flow greater than or equal to 0.1 mgd?
Note: Major mod request to
✓ Yes expand from 0.05 to 0.12 mgd ❑ No SKIP to Item 3.16.
3.14
Does the POTW use chlorine for disinfection, use chlorine elsewhere in the treatment process, or otherwise have
reasonable potential to discharge chlorine in its effluent?
❑ Yes 4 Complete Table B, including chlorine.
✓ No 4 Complete Table B, omitting chlorine.
3.15
Have you completed monitoring for all applicable Table B pollutants and attached the results to this application
package?
✓ Yes ❑ No
3.16
Does one or more of the following conditions apply?
• The facility has a design flow greater than or equal to 1 mgd.
• The POTW has an approved pretreatment program or is required to develop such a program.
• The NPDES permitting authority has informed the POTW that it must sample for the parameters in Table C, must
sample other additional parameters (Table D), or submit the results of WET tests for acute or chronic toxicity for
each of its discharge outfalls (Table E).
❑ Yes 4 Complete Tables C, D, and E as
applicable.
SKIP to Section 4.
✓ No 4
3.17
Have you completed monitoring for all applicable Table C pollutants and attached the results to this application
package?
❑ Yes ❑ No
3.18
Have you completed monitoring for all applicable Table D pollutants required by your NPDES permitting authority and
attached the results to this application package?
❑ Yes ❑ No additional sampling required by NPDES
permitting authority.
EPA Form 3510-2A Revised 3-19)
Page 8

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No. 2040-0004
Effluent Testing Data Continued
3.19
Has the POTW conducted either (1) minimum of four quarterly WET tests for one year preceding this permit application
or (2) at least four annual WET tests in the past 4.5 years?
❑ Yes ❑ No 4 Complete tests and Table E and SKIP to
Item 3.26.
3.20
Have you previously submitted the results of the above tests to your NPDES permitting authority?
❑ Yes ❑ No 4 Provide results in Table E and SKIP to
Item 3.26.
3.21
Indicate the dates the data were submitted to your NPDES permitting authority and provide a summary of the results.
Date(s) Submitted
(MM/DD/YYYY)
Summary of Results
3.22
Regardless of how you provided your WET testing data to the NPDES permitting authority, did any of the tests result in
toxicity?
❑ Yes ❑ No 4 SKIP to Item 3.26.
3.23
Describe the cause(s) of the toxicity:
3.24
Has the treatment works conducted a toxicity reduction evaluation?
❑ Yes ❑ No 4 SKIP to Item 3.26.
3.25
Provide details of any toxicity reduction evaluations conducted.
3.26
Have you completed Table E for all applicable outfalls and attached the results to the application package?
❑ Yes ❑ Not applicable because previously submitted
information to the NPDES •ermittin• authorit .
SECTION
4. INDUSTRIAL
DISCHARGES AND HAZARDOUS WASTES
(40 CFR
122.21(j)(6) and (7))
4.7.
Industrial Discharges and Hazardous Wastes
4.1
Does the POTW receive discharges from Sills or NSCIUs?
❑ Yes
✓ No 4 SKIP to Item
4.2
Indicate the number of SlUs and NSCIUs that discharge to the POTW.
Number of SIUs
Number of NSCIUs
4.3
Does the POTW have an approved pretreatment program?
❑ Yes ❑ No
4.4
Have you submitted either of the following to the NPDES permitting authority that contains information substantially
identical to that required in Table F: (1) a pretreatment program annual report submitted within one year of the
application or (2) a pretreatment program?
❑ Yes ❑ No 4 SKIP to Item 4.6.
4.5
Identify the title and date of the annual report or pretreatment program referenced in Item 4.4. SKIP to Item 4.7.
4.6
Have you completed and attached Table F to this application package?
❑ Yes ❑ No
EPA Form 3510-2A (Revised 3-19)
Page 9

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No.2040-0004
CSO Map and Diagram i Industrial Discharges and Hazardous Wastes Continued
4.7
Does the POTW receive, or has it been notified tha
regulated as RCRA hazardous wastes pursuant to
❑ Yes
it will receive, by truck, rail, or dedicated
40 CFR 261?
pipe, any wastes that are
4.9.
✓ No 4 SKIP to Item
4.8
If yes, provide the following information:
Hazardous Waste
Number
Waste Transport Method
(check all that apply)
Annual
Amount of
Waste
Received
Units
❑ Truck
❑ Dedicated pipe
❑ Rail
❑ Other (specify)
❑ Truck
❑ Dedicated pipe
❑ Rail
❑ Other (specify)
❑ Truck
❑ Dedicated pipe
❑ Rail
❑ Other (specify)
4.9
Does the POTW receive, or has it been notified that
including those undertaken pursuant to CERCLA and
❑ Yes
it will receive, wastewaters that originate
Sections 3004(7) or 3008(h) of RCRA?
from remedial activities,
5.
✓ No 4 SKIP to Section
4.10
Does the POTW receive (or expect to receive) less than 15 kilograms per month of non -acute hazardous wastes as
specified in 40 CFR 261.30(d) and 261.33(e)?
❑ Yes 4 SKIP to Section 5. ❑ No
4.11
Have you reported the following information in an attachment to this application: identification and description of the
site(s) or facility(ies) at which the wastewater originates; the identities of the wastewater's hazardous constituents; and
the extent of treatment, if any, the wastewater receives or will receive before entering the POTW?
❑ Yes ❑ No
N 5. COMBINED
SEWER OVERFLOWS (40 CFR 122.21(j)(8))
5.1
Does the treatment works have a combined sewer
❑ Yes
system?
6.
✓ No 4SKIP to Section
5.2
Have you attached a CSO system map to this application? (See instructions for map requirements.)
❑ Yes ❑ No
5.3
Have you attached a CSO system diagram to this application? (See instructions for diagram requirements.)
❑ Yes ❑ No
EPA Form 3510-2A (Revised 3-19)
Page 10

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No.2040-0004
CSO Outfall Description
5.4
For each CSO outfall, provide the following information. (Attach additional sheets as necessary.)
CSO Outfall Number
CSO Outfall Number
CSO Outfall Number
City or town
State and ZIP code
County
Latitude
"
0 Il
0
LongitudeIP
°
Distance from shore
ft.
ft.
ft.
Depth below surface
ft.
ft.
ft.
CSO Events in Past Year CSO Monitoring
5.5
Did the POTW monitor any of the following items in the past year for its CSO outfalls?
CSO Outfall Number
CSO Outfall Number
CSO Outfall Number
Rainfall
• Yes • No
• Yes • No
• Yes
• No
CSO flow volume
• Yes • No
• Yes • No
• Yes
• No
CSO pollutant
concentrations
• Yes • No
■ Yes • No
■ Yes
• No
Receiving water quality
• Yes • No
■ Yes • No
■ Yes
• No
CSO frequency
• Yes • No
• Yes ■ No
• Yes
■ No
Number of storm events
• Yes • No
• Yes ■ No
• Yes
■ No
5.6
Provide the following information for each of your CSO outfalls.
CSO Outfall Number
CSO Outfall Number
CSO Outfall Number
Number of CSO events in
the past year
events
events
events
Average duration per
event
hours
0 Actual or ❑ Estimated
hours
0 Actual or 0 Estimated
hours
0 Actual or 0 Estimated
Average volume per event
million gallons
❑ Actual or 0 Estimated
million gallons
0 Actual or 0 Estimated
million gallons
0 Actual or 0 Estimated
Minimum rainfall causing
a CSO event in last year
inches of rainfall
0 Actual or 0 Estimated
inches of rainfall
0 Actual or 0 Estimated
inches of rainfall
0 Actual or 0 Estimated
EPA Fomi 3510-2A (Revised 3-19)
Page 11

EPA Identification Number
110009720506
NPDES Permit Number
NC0O85812
Facility Name
Grassy Branch WRF
Form Approved 03/05/19
OMB No.2040-0004
Checklist and Certification Statement M. CSO Receiving Waters
5.7
Provide the information in the table below for each of your CSO outfalls.
CSO Outfall Number
CSO Outfall Number
CSO Outfall Number
Receiving water name
Name of watershed/
stream system
U.S. Soil Conservation
Service 14-digit
watershed code
(if known)
0 Unknown
0 Unknown
0 Unknown
Name of state
management/river basin
U.S. Geological Survey
8-Digit Hydrologic Unit
Code (if known)
0 Unknown
0 Unknown
0 Unknown
Description of known
water quality impacts on
receiving stream by CSO
(see instructions for
examples
xy:Q��r/a1�U
In Column 1 below, mark the
each section, specify in Column
all applicants are required to
•1r:
sections of Form 2A that you
2 any attachments that you
provide attachments.
T611
have completed and are submitting
are enclosing to alert the permitting
with your application. For
authority. Note that not
Column 1
Column 2
Section
1: Basic Application
for All Applicants
❑ w/ variance request(s) ❑ w/ additional attachments
✓
Information
Section
2: Additional
✓ w/ topographic
map
attachments
✓
w/ process flow diagram
❑ w/ additional
Information
Section
3: Information on
Discharges
✓ w/ Table
A ❑ w/ Table D
B ❑ w/ Table E
C ❑ w/ additional attachments
✓ w/ Table
Effluent
❑ w/ Table
Section 4: Industrial
❑ Discharges and Hazardous
Wastes
■ w/ SIU
and NSCIU attachments
attachments
•
w/ Table F
❑ w/ additional
❑ Section 5: Combined Sewer
Overflows
❑ w/ CSO map ❑ w/ additional attachments
❑ w/ CSO system diagram
Section
6: Checklist and
Statement
❑ w/attachments
✓
Certification
Certification Statement
I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in
accordance with a system designed to assure that qualified personnel properly gather and evaluate the information
submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible
for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and
complete. / am aware that there are significant penalties for submitting false information, including the possibility of fine
and imprisonment for knowing violations.
Name (print or type first and last name)
Andrew Neff, P.E.
Official title
Water and Wastewater Division
Director El
Signaate.....r
XI, t - 11-4/Cu cf
Date signed
q /-t. z_/-4, ,...../
EPA Form 3510-2A (Revised 3-19)
Page 12

EPA Identification Number
NPDES Permit Number
Facility Name
0utfall Number
110009720506
NC0085812
Grassy Branch WRF
001
Form Approved 03/05/19
OMB No. 2040-0004
TABLE A. EFFLUENT PARAMETERS FOR ALL POTWS
Discharge
Average Daily Discharge
Analytical
Method
ML or MDL
(include units)
Pollutant
Maximum Daily
Value
Units
Value
Units
Number of
Sam • Ies
Biochemical oxygen demand
o BODs or ❑ CBOD5
resort one
193
mg/L
5.47
mg/L
161
SM 5210B
0 ML
< 2 2 MDL
Fecal coliform
12,500
MPN/100mL
339
MPN/100mL
174
SM 9222D
0 ML
< 1 p MDL
Design flow rate
0.05
mgd
0.05
mgd
N/A
pH (minimum)
pH (maximum)
Temperature (winter)
6.20
8.95
20.80
su
su
C
12.69
C
98
Temperature (summer)
27.50
C
20.77
C
151
Total suspended solids (TSS)
177
mg/L
6.29
mg/L
156
CI ML
SM 2540D < 2.6 O MDL
1 Sampling shall be conducted according to sufficiently sensitive test procedures (i.e., methods) approved under 40 CFR 136 for the analysis of pollutants or pollutant parameters or
required under 40 CFR chapter I, subchapter N or 0. See instructions and 40 CFR 122.21(e)(3).
EPA Form 3510-2A (Revised 3-19)
Page 13

This page intentionally left blank.

EPA Identification Number
110009720506
NPDES Permit Number
NC0085812
Facility Name
Grassy Branch WRF
Outfall Number
001
Form Approved 03/05/19
OMB No. 2040-0004
TABLE B. EFFLUENT PARAMETERS
FOR ALL POTWS
WITH A FLOW EQUAL
Discharge
TO OR GREATER THAN 0.1 MGD
Average Daily Discharge
Analytical
Methods
ML or MDL
(include
( units)
Pollutant
Maximum Daily
Value
Units
Value
Units
Number of
Samples
Ammonia (as N)
17.0
mg/L
0.81
mg/L
159
SM 4500NH3
0 ML
0.10 0 MDL
Chlorine
(total residual, TRC)2
NA
mg/L
NA
mg/L
NA
NA
❑ ML
NA
❑ MDL
Dissolved oxygen
13.20
mg/L
8.94
mg/L
279
SM 45000G
0 ML
0.10 MDL
Nitrate/nitrite
NA
mg/L
NA
mg/L
NA
NA
0 ML
NA 0 MDL
Kjeldahl nitrogen
NA
mg/L
NA
mg/L
NA
NA
0 ML
NA ❑ MDL
Oil and grease
NA
mg/L
NA
mg/L
NA
NA
0 ML
NA ❑ MDL
Phosphorus
NA
mg/L
NA
mg/L
NA
NA
0 ML
NA 0 MDL
Total dissolved solids
NA
mg/L
NA
mg/L
NA
NA
ML
NA 0 MDL
Sampling shall be conducted according to sufficiently sensitive test procedures (i.e., methods) approved under 40 CFR 136 for the analysis of pollutants or pollutant parameters or
required under 40 CFR chapter I, subchapter N or 0. See instructions and 40 CFR 122.21(e)(3).
2 Facilities that do not use chlorine for disinfection, do not use chlorine elsewhere in the treatment process, and have no reasonable potential to discharge chlorine in their effluent are not
required to report data for chlorine.
EPA Form 3510-2A (Revised 3-19)
Page 15

This page intentionally left blank.

Lead and Copper Rule Revisions Summary
The final draft revisions to the Lead and Copper Rule have been distributed to public water systems. There
have been extensive changes to the rules and compliance is expected to start in January 2024. There have
been some delays at the federal level that may push the compliance starting period to September 2024.
We identified the need for assistance to ensure we comply with the new rules, as some of the changes are
very complex and subjective.
• With that in mind, operations has budgeted for consultation in our FY22 operating budget to help
guide us through the steps and processes that will need to be implemented to ensure compliance
with the rule before it begins in 2024. We will look for the consultant to help us form the best plan
for system service line inventory, service line replacement program, and a "find and fix" policy.
Below is a summary of the most critical changes to the rule and what it will mean for us. It does not include
a complete plan to address each requirement. I believe we would task the consultant with structuring a plan
in the order of importance and the best way to implement it once the consultant has been selected.
Tap Sampling Guidance
Significant changes have been made to lead and copper tap sampling procedures with the LCRR. The EPA
has revised the sample pool tier structure. Any system with enough lead service lines in their system to fill
the sample pool will be required to sample all lead service lines.
• Our sample pool will be adjusted to include any "known lead service line" customers that are
identified during our work before the rule is implemented.
There have also been some sampling changes. Rather than sampling the 1st liter for both lead and copper
at the selected sample pool sites, utilities are now required to sample the 1st liter for copper and the 5th
liter for lead at locations with lead service lines. Additional changes, such as using only wide mouth bottles
and no pre -flushing, are also included in the new rule.
• We will review our monitoring SOP and make changes as needed for the collection of lead samples
per the new rule.
Lead Service Line - Revised Definition
Lead Service Lines
A pipe is considered a lead service line (LSL) if a portion is made of lead, which connects the water main
to the building inlet. An LSL can be owned by the water system, the property owner, or both.
If the only lead on a service line is a lead gooseneck, pigtail or connector, it is not considered an LSL.
Galvanized Service Lines
A galvanized service line is now considered an LSL if it is currently or was formerly downstream of an LSL
or a service line of unknown material due to the tendency of galvanized to capture lead from upstream
sources and release it back into the water if the pipes are disturbed or if the water quality changes. This is
being called a "galvanized requiring replacement". For sampling tier selection, a galvanized service line is
a Tier 3 sampling site and not an LSL (Tier 1 and Tier 2).
Based on clarification from the EPA, galvanized requiring replacement (Tier 3 sites) should be sampled at
the 1st liter for lead rather than the 5th liter although the text is ambiguous on this. Further clarification has
been requested from the EPA and this section will be updated once received.

Lead and Copper Rule Revisions Summary
• We will need to monitor this change and adjust our sampling SOP based on the final rule. I
believe we will write a new SOP, only for lead and copper sampling to address new sampling
protocols and the requirements for monitoring any sites that exceed the action level as noted in
this document below.
Clarification was provided by the EPA that a galvanized service line downstream of a lead gooseneck is
not considered an LSL. If a system encounters a lead gooseneck, it must replace it (or offer to replace it if
the gooseneck is privately owned). A system does not need to replace utility -owned galvanized service
lines nor offer to replace privately -owned galvanized service lines downstream of lead goosenecks when
the goosenecks are removed. However, a system does need to offer to replace a galvanized service line
if it is currently, or was formerly, downstream of an LSL.
• We do not believe, nor have we ever found a lead service line in our system. If that remains the
case, after a full system inspection, this will greatly limit our exposure for a line replacement
program.
Unknown Service Lines
A service line of unknown material, or lead status unknown service line, means a service line that has not
been verified as non -lead. It is not necessary to physically verify all materials. Other means of verification
will be approved by the states (e.g. records indicating installation after a local, state or federal lead ban).
Until the service line can be verified as non -lead, it will count towards the total number of LSLs in the
service line material inventory.
• Note: All service line materials will need to be identified regardless if they have been ruled non -
lead by dating or other means.
After dating and records search, a plan will be needed to identify material for remainder
service lines. Some data is already available from information collected by meter
services. Additional data can be collected by staff as they interact with our water
connections.
Important note on disturbance!
If a system causes a disturbance to an LSL, galvanized requiring replacement or lead status unknown
service line, it must provide a point -of -use filter that is certified to NSF 53 standards with a 6-month supply
of replacement cartridges along with information about elevated lead levels and flushing instructions to
the customer. A disturbance includes a full LSL replacement, a partial LSL replacement, removal of a
gooseneck, a meter replacement or anything else requiring the service to be shut down or bypassed
temporarily.
• If needed, the average cost for lead filtering water pitcher is about $40. This would include the
water pitcher with filter and one replacement filter.
Water Quality Parameter (WQP) Monitoring
Collect one sample every 2 weeks at all entry points to the system and collect two samples per monitoring
period at all WQP sampling sites at the standard number of sampling sites (See CFR 141.87(a)(ii)(2)).
Monitoring period shall be every 6 months until the state designates optimal corrosion control treatment.
Although WQP sampling data can be grandfathered in, the lead tap samples during the same period would
need to be collected per the new provisions in the LCRR for the data to count.
If CCT is modified, continue sampling every 6 months until your state specifies new WQP values for optimal
corrosion control.

Lead and Copper Rule Revisions Summary
Parameters to sample shall include pH and alkalinity. If a corrosion inhibitor is used for corrosion control,
sampling is also required for the inhibitor residual (i.e. orthophosphate or silica). Confirm with your state if
any other parameters are required for your system.
Additional WQP sites may need to be added under the Find and Fix provisions. WQP sites are added near
any individual tap water samples above 15 pg/L up to a maximum of double the standard WQP sites.
Systems with 90 th Percentile Lead Below 10 pg/L
The first year once the LCRR is effective (January 2024), all systems with LSLs will be required to sample
every 6 months at the standard number of sites for lead and copper. As of now, it is unclear if systems
without LSLs will be required to go on 6-month monitoring or continue with their current monitoring
frequency. This will likely be determined by each state and will depend on if your system's previous tap
sampling can be said to have met the new sampling site selection, procedures and requirements in the
LCRR.
• Union County is presently on a reduced monitoring program that requires sampling every three
years. These samples are taken from June to September, but this will change with the new rule.
We are required to take 50 samples every three years but would have to take 100 samples
should we return to normal monitoring. If we cannot rule out lead service lines in the system, we
will need to take 100 samples every six months beginning with the new rule.
If our system does not exceed the lead trigger level of 10 pg/L and the copper action level of 1.3 mg/L
with the new sampling requirements for two consecutive 6-month monitoring periods, our system may
reduce monitoring frequency to annual monitoring at the standard number of sites for lead and the
reduced number of sites for copper. Systems must maintain water quality within the optimal water quality
parameters (OWQPs) during this same period and receive a written determination from the state
approving annual monitoring based on the state's review of monitoring, treatment and other relevant
information.
To qualify for triennial monitoring (every three years) as a large system, our system's 90th percentile for
lead must be at or below 5 pg/L and 90th percentile for copper at or below 0.65 mg/L for two consecutive
6-month monitoring periods with the new sampling requirements. Systems must maintain water quality
within the OWQPs during this same period and receive a written determination from the state approving
triennial monitoring based on the state's review of monitoring, treatment and other relevant information.
If at any point in the future our system adds a new source or long-term change in treatment, our system
will be required to go back to 6-month monitoring at the standard number of sites for lead and copper
unless the state determines the addition of the new source or treatment does not have an impact on
corrosion control treatment (New Yadkin Plant).
• We will most likely be on the standard monitoring schedule when the Yadkin Plant goes online.
We can work towards a reduced monitoring plan once we have an inventory of our system
completed.
• Below are the results of our last two cycles of lead testing.
2019 Lead Results
LEAD SAMPLES
90th Percentile Level = ND
No. Location3 Tier/Target Lead mg/I No. Location4 Tier/Target Lead mg/I

Lead and Copper Rule Revisions Summary
ND
ND
ND
ND
0
Z
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0
Z
ND
0.0036
0.0083
-
CO
o
0
0.0328
r
to
CO
0
0
e1
e-1
l-1
r-I
e-1
e1
e1
e 1
e 1
e'1
c-I
e-i
a -'I
e l
l-'I
e-1
e-I
1-1
ei
ei
ei
ei
e-1
e-1
e-I
l0D
J
L92
L38
L65
L23
113
a-ILfl
e-1
125
a>
J
L48
v-I
J
L75
L87
L54
L63
114
CTall c-I
e-i
N
e--I
COJ
L17
L59
L25
L62
0)
J
CO
J
1.0
N
I-
N
00
N
O)
N
0
m
ei
M
N
M
Cr)
M
st
M
tf)
M
l0
M
h
M
CO
M
0i
m
0
Cr
e1
Cr
N
Ct
Cr
Cr
V
u')
ct
lD
f's
Cr
CO
d'
01
0
ul
ND
ND
(IN
ON
ND
ND
0
Z
ND
0
Z
ND
0
Z
ND
ND
0
Z
ND
ND
ND
ND
ND
0
Z
ND
ND
ND
ND
0
Z
e•-I
c-1
e-1
ei
ei
eI
e-1
e-i
e-I
e-I
e-I
e1
ei
%-1
e-I
e•-I
c-I
e-1
e-1
e1
ei
ei
ei
e1
ei
L86
CO
00
L94
L57
L98
L64
L84
L89
CO
J
L77
L93
0
J
c-I
O0
L04
L67
L31
L72
L33
0
J
0
N1
0)
NI
118
a
01
102
111
CI-
c-1
N
Cr)
a'
u)
l0
I's
CO
Ol
, 4
e-I
e-1
e-1
e-1
e-I
LD
c^-1
CO
01
O
N
N
N
N
N
LEAD SAMPLES
90th Percentile Level = 0.006
Z0I
ro
1-
L
0
0
ra
u
0
-J
Z0I
ND
ND
ND
ND
ND
e1
r-I
e1
e1
r-1
L63
CO
J
L71
lD
J
L65
l.0
N
N
N
00
N
01
N
O
Cr)
ND
0
Z
0
Z
ND
ND
e-1
e-1
e-1
e-1
e-1
c-I
OJ
c-I
CA
L75
L80
L52
c-I
N
M
Cr
Lf)

Lead and Copper Rule Revisions Summary
6
L99
1
ND
31
L43
1
ND
7
L73
1
ND
32
L76
1
ND
8
L69
1
ND
33
L95
1
ND
9
L101
1
ND
34
L04
1
ND
10
L90
1
ND
35
L96
1
ND
11
L79
1
ND
36
L67
1
ND
12
L88
1
ND
37
L93
1
ND
13
L45
1
ND
38
L55
1
ND
14
L23
1
ND
39
L57
1
ND
15
L17
1
ND
40
L49
1
ND
16
L38
1
ND
41
L87
1
0.0038
17
L22
1
ND
42
L54
1
0.0042
18
L89
1
ND
43
L20
1
0.0046
19
L64
1
ND
44
L51
1
0.0054
20
131
1
ND
45
L66
1
0.0064
21
L94
1
ND
46
L85
1
0.0064
22
L78
1
ND
47
L59
1
0.013
23
L40
1
ND
48
L58
1
0.017
24
L50
1
ND
49
L74
1
0.42
25
L81
1
ND
50
L24
1
0.44
Corrosion Control Treatment (CCT)
Monitoring has shown that we have done a great job with our system's corrosion control! It is unclear at
this time if our system's status will carry over with the LCRR. We suspect that if our tap sampling site
selection and procedures do not exactly align with the new requirements for sampling, our system will be
required to go on 6-month monitoring.
If we are not confident that our system's 90th percentile will consistently be below 5 pg/L with the new
sampling requirements, we may want to consider conducting a corrosion control treatment (CCT) study.
Currently we believe the system can maintain this level but additional testing will need to be performed
based on the new sampling techniques.
• We will need to work with our treatment superintendent and the CRWTP manager to better
understand if improvements can be made to CCT.
Inventory Requirements and Lead Service Line Replacement for All Systems
• Service Material Inventory
All systems are required to compile a service line material inventory (including both utility -owned
and privately -owned sides of the service line) by January 2024 or demonstrate absence of LSLs.
Any galvanized service lines that are, or were formerly, downstream of an LSL, or "galvanized
requiring replacement," are required to be included in the overall count of LSLs for eventual
replacement. Services with unknown materials that may be lead will be classified as "lead status
unknown service lines" and will also count towards the total number of LSLs in the system until
they are verified. Update inventory annually or triennially, based on sampling frequency, with any
replacements and/or verifications. If your system supplies over 50,000 people, you are required to

Lead and Copper Rule Revisions Summary
publish the inventory online. If your system supplies less than 50,000 people, it is not required to
be online but it must be available to the public on request.
All systems must notify customers who have service lines categorized as lead, galvanized
requiring replacement, or lead status unknown within 30 days of completing the inventory and
then on an annual basis. The EPA has specific guidelines in the rule for what information needs
to be included in the notification.
• To begin our service line inventory, we will immediately start working with our GIS team
to identify homes and businesses that were built before 1978. This will automatically label
those connections as ""Lead Status Unknown." We can then determine the best
approach on how to identify them individually. All services newer than 1978 will still need
to be identified as plastic or copper. Most of these can be determined by records and
county specifications over the years.
• Schools — We will partner with our school system to lay out a plan for monitoring both the
supply side of their service as well as within the schools. Once we have a plan, we will
begin performing non-compliance sampling to build a data base that will be needed for
the new rule This should help both us and the school system to be prepared for future
requirements
• Daycares — We will need to compile a list of daycares for monitoring, which can be
furnished by environmental health. We will then begin sampling these sites and
conducting an inventory of their service lines in advance of the new lead rule.
• LSL Replacement Program Plan
If you find that your system has LSLs based on your inventory, all systems with LSLs must also
prepare a Lead Service Line Replacement Program by January 2024. The plan must include:
o A strategy for determining "lead status unknown" service lines
o Procedures to conduct full LSL replacements
o Communication strategies
o A recommended LSL replacement goal rate in the event of a lead trigger level
exceedance (for systems over 10,000 persons)
o Flushing procedures
o LSL prioritization strategies
o Funding strategies including ways to accommodate customers that are unable to pay for
the replacement of their portion on their own
o If our inventory yields any LSL's, we will need to create the replacement plan. If needed, I
believe this task would go to our consultant for development.
Find and Fix
When an individual sample exceeds the lead action level, customers must be notified within 3 days of
receiving the results. A utility must perform a "Find and Fix" for all individual samples exceeding 15 pg/L
of lead by conducting the following:
1. Corrosion Control Treatment Assessment — Within 5 days of receiving the results, conduct
additional WQP monitoring at a sample site on the same size water main and within a half mile of

•
Lead and Copper Rule Revisions Summary
the residence with the sample exceeding 15 pg/L. If a new WQP location is added, it should be
incorporated into future WQP monitoring. The number of WQP sites may continue to increase
with individual samples exceeding 15 pg/L until your system's number of WQP sites is double the
standard number of sites for your size. Small systems without corrosion control treatment may
have 14 days to collect the sample.
2. Site Assessment — Within 30 days of receiving results, collect a follow-up sample at the location
exceeding 15 pg/L.
o For a lead service line, a different sample volume or sample collection procedures may
be used to assess the source of elevated lead levels.
o For a service line that is not lead, collect 1 liter first draw sample after 6+ hours of
stagnation.
o Results must be submitted to the state but will not be used for the 90th percentile
calculation.
o If access is denied for resampling, document customer refusal or nonresponse after two
attempts to obtain the follow-up sample.
3. Investigate the high lead value and determine needed corrective action.
o Determine if either localized or centralized adjustment of corrosion control treatment are
needed or if other distribution system actions are necessary (such as flushing to reduce
water age).
Since our system does not yet have optimal corrosion control treatment, treatment reoptimization
recommendations to the state are not required to be provided.

I
Union County Public Works
Grassy Branch WRF
NPDES Permit No. NC0085812
Outfall 001
Form 2A Additional Information
B.2 Topographic Map
Refer to Figure 1 for the topographic map.
B.3 Process Flow Schematic or Diagram
Refer to Figures 2-1 and Figure 2-2 for process flow schematics at 0.05 and 0.12 mgd,
respectively.
Overview
The Grassy Branch Water Reclamation Facility (Grassy Branch WRF) is an extended aeration
package treatment plant (PTP) constructed by Hydro -Aerobics Package Wastewater Treatment
Systems in 1997. The facility design flow is 50,000 gallons per day (gpd).
Influent Pumping & Headworks
The existing influent pump station consist of two pumps rated at 130,000 gpd each at 15 feet of
total dynamic head (TDH). The pumps operate in a duty/standby service. The influent screening
is comprised of a manual coarse bar screen designed for 150,000 gpd (2.5 times the maximum
month design flow of 50,000 gpd). The existing equalization basins have a combined volume of
15,400 gallons. Coarse bubble diffusers and two, 2-horsepower (HP) rotary lobe positive
displacement (PD) blowers provide aeration and mixing in the equalization basins.
The proposed expansion to 0.12 mgd will include an additional manual coarse bar screen and
equalization basin to provide for additional treatment capacity at the Grassy Branch WRF.
Secondary Treatment Process
The existing secondary treatment process consists of two, 25,000-gallon extended aeration
basins with coarse bubble diffusers. Air is supplied by two, 7.5-HP rotary lobe PD blowers. The
blowers are controlled via variable frequency drives (VFD). The aeration system is a single run of
coarse bubble diffusers located along the entire length of one wall in each aeration basin. The
location of the diffusers provides a spiral roll flow pattern for complete mixing within the basin.
Lime slurry (30%) provides supplemental alkalinity. RAS flow is estimated at 100% of the plant
flow, which is corroborated by the Hydro -Aerobics Package Wastewater Treatment Systems
Operations and Maintenance (O&M) manual. WAS is stored in a 9,000-gallon aerated holding
tank. The holding tank has coarse bubble diffusers connected to the secondary treatment
aeration system PD blowers. Solids are pumped out and transported to the Crooked Creek WRF
for stabilization and ultimate disposal. The flow from each aeration basin combines in the MLSS

♦
Union County Public Works
Grassy Branch WRF
NPDES Permit No. NC0085812
Outfall 001
distribution box prior to entering the secondary clarifiers. The Grassy Branch WRF has two, 10-
foot diameter secondary clarifiers.
The proposed expansion to 0.12 mgd will include an additional aeration basin and secondary
clarifier to provide for additional capacity at the treatment facility.
Filtration and Disinfection
The Grassy Branch WRF has two mixed media (anthracite/sand) tertiary filters with a surface
area of 18.75 square feet (SF) each (37.5 SF total). Prior to discharge into Crooked Creek,
secondary effluent is disinfected via UV disinfection technology. The UV system was installed in
the original chlorine contact chamber as a retrofit.
The proposed expansion of the Grassy Branch WRF includes the addition of a new cloth media
disk -type filter. The existing sand filters will be utilized as a standby, redundant unit.
Additionally, a new UV disinfection system is proposed which would allow for one duty and one
standby unit to meet peak daily flows.

Facility Location
Not to Scale
State Grid/Quad:
Receiving Stream:
Stream Class:
Drainage Basin:
Sub -basin:
Latitude:
Longitude:
Stanfield
G 17 NW
Crooked Creek
C
Yadkin Pee Dee
03-07-12
35° 07' 50" N
80° 29' 40" W
Hazen
Copyrit:4 2013 National Geryr,phicFSaciet used'
Figure 1: Topographic Map
Union County Public Works
Grassy Branch WRF
NPDES Permit NC0085812
Union County, NC

Q = 0.05
mgd
Influent Pump
Station (2 pumps)
Crooked Creek
Manual Coarse
Bar Screen (1)
UV Disinfection
EQ Basins (2)
30% Lime Slurry
Aeration Basins (2)
Anthracite/Sand
Tertiary Filters (2)
Transported to Crooked
Creek WRF for Stabilization
Secondary
Clarifiers (2)
RAS/WAS PTP
WAS
Q = 0.002 mgd
Aerated Holding
Tank (1)
Figure 2-1:
Process Flow Diagram
Grassy Branch WRF
Existing: 0.05 mgd
NPDES Permit NC0085812

30% Lime Slurry
Q [''\�\ ►`� r Q mgd
mgd ,
4.
Influent Pump
Station (2 pumps)
Crooked Creek
Manual Coarse
Bar Screen (2)
UV Disinfection
EQ Basin (3)
Aeration Basins (3)
Q = 0.12 mgd
Secondary
Clarifiers (3)
RAS
Disc Filter (1)
Transported to Crooked
Creek WRF for Stabilization
4
RAS/WAS PTP
Q = 0.12 mgd
WAS
Q = 0.004 mgd
Aerated Holding
Tank (3)
Figure 2-2:
Process Flow Diagram
Grassy Branch WRF
Expansion: 0.12 mgd
NPDES Permit NC0085812

Hazen
Hazen and Sawyer
4011 WestChase Blvd, Suite 500
Raleigh, NC 27607 • 919.833.7152
Firm License No. C-0381
TECHNICAL MEMORANDUM
To: Copies:
Andrew Neff, PE Jim Struve, PE
Water and Wastewater Division Director
Union County Public Works
From:
Mary Sadler, PE
Anthony Young, El
Date:
April 2021
Subject:
Engineering Alternatives Analysis to Support Major NPDES Modification Request
Grassy Branch WRF Expansion from 0.05 mgd to 0.120 mgd
Special Order by Consent Application
RECEIVED
MAY 11 2021
NCDEQ/DWR/NPDES
1. Introduction
Union County is located on the border of South Carolina approximately 15 miles southeast of Charlotte
and is home to fourteen municipalities. Union County Public Works (UCPW) is responsible for the
management, operation and maintenance of the wastewater collection and treatment system for
unincorporated Union County and all County municipalities except for the City of Monroe and the Town of
Marshville. The County's wastewater system is comprised of five conventional activated sludge
wastewater reclamation facilities (WRF) with a combined rated treatment capacity of 9.65 million gallons
per day (mgd).
The Grassy Branch WRF is one of the five treatment facilities that Union County owns and operates. The
WRF was constructed in 1997 by a developer and since acquired by Union County. The Grassy Branch
WRF is permitted to discharge 0.05 mgd of treated effluent into Crooked Creek via NPDES permit
NC0085812. The Grassy Branch collection system consists of approximately 31,000 feet of gravity sewer,
123 manholes, and two wastewater pump stations. The Loxdale Pump Station has a capacity of
21,400 gpd and the Unionville Pump Station has a capacity of 10,245 gpd. The Grassy Branch WRF
serves three schools, two residential subdivisions, and several private parcels.
The County has received Notice of Violations (NOVs) for flow, five-day biochemical oxygen demand
(BOD5), ammonia (NH3-N), fecal coliform, total suspended solids (TSS), and pH for the Grassy Branch
WRF over the last several years. The County has attributed the majority of the NOVs to record rainfall
events in the region; however, over -allocation of sewer connections to the Grassy Branch WRF has
contributed to and intensified the compliance issues. Grassy Branch WRF flow and recorded rainfall data
demonstrates that the design flow capacity is exceeded during rain events. Influent flow peaks have
exceeded a ratio of 7 to 1 (e.g., peaking factors greater than 7) compared to the design capacity of the
WRF.
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To address the on -going violations at Grassy Branch, Union County has executed and submitted the
application form and required attachments to the Department of Environmental Quality (DEQ) Division of
Water Resources (DWR) for a Special Order by Consent (SOC). The Grassy Branch SOC package
requested an increase in design capacity from 0.05 to 0.12 mgd to address the over -allocation of sewer
connections. In response, DWR staff requested that the County's SOC application be amended to include
a National Pollutant Discharge Elimination System (NPDES) permit major modification to support the
County's request for a capacity increase. Per DWR Guidance, this Technical Memorandum provides the
Engineering Alternative Analysis (EAA) to support the capacity increase request at the Grassy Branch
WRF.
2. Need for Project
Historical data indicates that influent flows greater than the permitted design capacity of the Grassy
Branch WRF have resulted in final effluent permit violations for flow, conventional pollutants, and bacterial
pollutants. The County has attributed many of the NOVs to record rainfall events in the region. The County
also acknowledges that more sewer connections have been allocated to the Grassy Branch WRF than
available capacity. The Grassy Branch WRF receives domestic wastewater from a defined service area.
The WRF serves three schools, two residential subdivisions, and private parcels, summarized as follows:
• Piedmont High School (1,363 students)
• Piedmont Middle School (1,018 students)
• Unionville Elementary School (701 students)
• Loxdale Subdivision (52 lots)
• Smithfield Subdivision (70 lots, five of which are vacant)
• Private parcels (12 homes)
A permanent increase in the design maximum month flow from 0.05 mgd to 0.120 mgd is required at the
Grassy Branch WRF. This flow increase is associated with the existing domestic flow discharging to the
WRF, the maximum student capacity of the three schools, new connections in the Smithfield subdivision to
fulfill contractual obligations (five lots), and private parcel connections along the main sewer line to the
WRF. The Loxdale subdivision has reached the maximum dwelling units for the subdivision. The
anticipated planned flow was established using the average day wastewater flow rates published in 15A
NCAC 02T .0114 (Wastewater Design Flow Rates). The anticipated planned flow was added to the annual
average flow to the WRF.
A maximum month peaking factor of 1.7 was applied to the annual average flow, which results in a
maximum month design flow of 0.120 mgd. The peaking factor of 1.7 is the median peaking factor of the
2014 through August 2019 data set. The maximum month peaking factors at the Grassy Branch WRF are
significantly higher than what is typical for larger treatment facilities. Table 2-1 summarizes the proposed
design annual average and maximum month flow.
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Table 2-1: Summary of Methods Used to Calculate Proposed Maximum Month Design Flow
Current
Dwelling Unit / School Flow, gpd
Anticipated
Planned Flow, gpd
Total Flow, Peaking
gpd Factor 9
Piedmont High School
----
1,953 1, 2, 3
----
----
(1,363 students)
Piedmont Middle School
----
0 4
----
----
(1,018 students)
Unionville Elementary School
----
0 4
----
----
(701 students)
Loxdale Subdivision (52 lots)
----
0 5
---- ----
Smithfield Subdivision (70 lots)
----
1,800I'6
----
----
Private parcels
----
11,520 1,7
----
----
Annual average flow
53,360
15,270
68,630
----
Maximum month flow 8
----
----
120,000
1.7
Maximum week (7-day) flow
----
----
201,000 3.0
Maximum day flow
----
----
469,000 7.0
Per 15A NCAC 02T .0114 — Wastewater Design Flow Rates.
2 15 gpd /student for average day school flow rate converted to an annual average flow (e.g., school in session
180 days per year).
3 High school is currently 84% enrolled. Maximum capacity is 1,600 students per Union County Public Schools.
4 The middle and elementary schools are at maximum enrollment.
5 The Loxdale subdivision is built out to a maximum of 52 homes.
6 The Smithfield subdivision currently contains five vacant lots. Vacant lots were counted as three bedrooms for
planning purposes.
Private parcels currently contain 12 dwelling units. Approximately 32 vacant lots are available and were
counted as three bedrooms for planning purposes.
8 Rounded to the nearest 10,000 gallons.
9 The maximum month peaking factor is based on the median peaking factor of the January 2014 through
August 2019 data set.
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3. Alternatives Analysis
Six wastewater capacity alternatives were evaluated to address the Grassy Branch WRF expansion from
0.05 mgd to 0.12 mgd. This alternatives analysis addresses the additional 0.07 mgd of capacity that will be
required to meet the needs of the Grassy Branch service area. The alternatives that were considered in
this analysis include the following:
• No action
• Infiltration and inflow (I&I) reduction
• Connection to other publicly -owned treatment works (POTWs)
• Land application
• Non -conjunctive reuse
• Expand the Grassy Branch WRF and surface water discharge to Crooked Creek
Opinion of probable project costs were prepared for the applicable alternatives. Cost opinions were
prepared in accordance with the guidelines of the Association for the Advancement of Cost Engineering
(AACE) International for a Class 4 level of estimation. A Class 4 estimate is prepared based on
information developed during a feasibility phase. The expected accuracy range for a Class 4 level of
estimation is +50 percent to —30 percent. Cost opinions include contingency, mobilization, bonds and
insurance, and general conditions. For the total present worth evaluation, a time period of 20 years was
used and a discount rate of 2.3 percent per EPA 2020 Discount Rates Circular A-94. Piping, electrical, and
structural infrastructure was assumed to have a life of 40 years. Mechanical equipment was assumed to
have a life of 20 years.
3.1 No Action
The no -action alternative consists of the County not constructing the necessary wastewater treatment
capacity to address the over -allocation of flow in the Grassy Branch service area. Based on historical data
from the County, influent flows that exceed the permitted design capacity of the Grassy Branch WRF will
continue to result in final effluent permit violations for flow, conventional pollutants, and bacterial
pollutants. The Grassy Branch WRF does not have the capacity to treat the increase in flow without an
increase in infrastructure capacity. Therefore, this alternative was eliminated from further consideration.
3.2 Infiltration and Inflow Reduction
The County has actively been involved in the reduction of infiltration and inflow (I&I) in the collection
system. A Phase 1 I&I study was commissioned in 2016 to broadly determine problem areas. A Phase 2
study in 2017 focused on repair efforts readily identified in the Phase 1 study. The Phase 2 study also
included wet weather monitoring. In 2018, Phase 3 efforts included confirming the effectiveness of
previous repair efforts, extensive closed-circuit television (CCTV) review of the entire collection system,
and the continuation of repair efforts. Phase 4 of the I&I reduction effort was initiated in January 2019. This
phase consists of a review of dry and wet weather data and patterns and on -going inspection of the
collection system.
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As of January 2019, the entire Grassy Branch collection system has been surveyed by CCTV. Table 3-1
provides a summary of the maintenance data for the I&I reduction effort from 2014 to present, including
investigative man hours and quantity of repaired infrastructure (e.g., manholes, laterals, etc.).
Table 3-1: Summary of I&I Effort Maintenance Data
2014 2015 2016 2017 2018 2019
Man Hours 960 1080 960 480 1512 1152
Investigating
Man Hours Repairing 360 48 0 72 1152 192
Footage Cleaned 0 0 10,181 425 10,146
CCTV Footage 160 40 10,181 160 16,273 14,627
Hours Smoke Testing 24 20 36 36 37 32
Smoke Test Footage 14,745 7,283 4,235 4,570 15,308 8,368
Manholes Repaired 3 0 0 0 42 3
Lateral Repaired 6 4 0 4 25 8
Cleanouts Repaired 6 4 0 4 17 8
Inflow Dishes Installed 0 0 0 0 53 0
The County is not able to quantify a specific reduction in influent flow as a result of the on -going I&I
reduction efforts. However, the County's I&I reduction efforts have resulted in a slight decrease in the
peaking factors at the Grassy Branch WRF. Table 3-2 summarizes the annual average, maximum month,
maximum 7-day, and maximum day peaking factors (PF) from 2015 through 2018. In 2018, the maximum
day peaking factor was 6.72 compared to 7.76 in 2015 prior to I&I reduction efforts.
The County has committed to the continuation of I&I efforts in the Grassy Branch WRF collection system.
The additional 0.07 mgd of capacity needed to address growth in the planning area cannot be accounted
for in I&I reduction efforts. Therefore, the I/1 reduction alternative has been eliminated from further
consideration as a stand-alone alternative to the proposed capacity increase.
Table 3-2: Summary of Historical Influent Peaking Factors
Parameter 2015 2016 2017 2018
Maximum month peaking factor 1.94 1.65 1.74 1.91
Maximum week (7-day) peaking factor 2.98 3.44 2.70 2.72
Maximum day peaking factor 7.76 7.00 6.74 6.72
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3.3 Connection to Other Publicly -Owned Treatment Works
Connection to other publicly -owned treatment works (POTWs) was evaluated as an alternative to an
expansion of the Grassy Branch WRF. Wastewater treatment facilities in the proximity of a five -mile radius
of the Grassy Branch WRF include the Old Sycamore WRF, the Tallwood WRF, and the Crooked Creek
WRF. All three treatment facilities are owned and operated by Union County. Union County's Twelve Mile
Creek Water Reclamation Facility is approximately 20 miles from the Grassy Branch WRF. A fifth
treatment facility in the proximity of the Grassy Branch WRF is the City of Monroe WWTP. The Monroe
WWTP has a permitted capacity of 10.4 mgd and is approximately 10 miles from the Grassy Branch WRF.
Figure 3-1 illustrates the location of the five wastewater treatment facilities in Union County relative to the
Grassy Branch service area.
Table 3-3 summarizes the treatment facility, permitted discharge, average day flow, percent of capacity
remaining, and the estimated distance from the Grassy Branch WRF for the five identified wastewater
treatment facilities. The closest treatment facility within a five -mile radius of the Grassy Branch WRF is the
Tallwood WRF, which is owned and operated by Union County. Similar to the Grassy Branch WRF, the
Tallwood WRF has a defined service area (e.g., a residential community). The Tallwood WRF does not
have capacity to accommodate the additional Grassy Branch flow. The remaining treatment facilities are
outside the five -mile radius of the Grassy Branch sewershed. Furthermore, the City of Monroe is currently
in the initial planning phase for an expansion of the Monroe WWTP. The City has requested speculative
limits from DWR to initiate the expansion process. Flows to the Monroe WWTP are approaching
70 percent of the permitted capacity.
Table 3-3: Summary of Publicly Owned Treatment Works in Proximity to the Grassy Branch WRF
Municipality /
Wastewater
Service
Provider
Union County
Union County
Union County
Union County
City of Monroe
Treatment
Facility
Old Sycamore
WRF1
Tallwood WRF
Crooked
Creek WRF
Twelve Mile
Creek WRF
Monroe
WWTP
NPDES
Permitted
Discharge I
0.15 mgd
0.05 mgd
1.9 mgd
7.5 mgd
10.4 mgd
Average Day
(Maximum Day)
Flow 2
0.046 mgd
0.038 mgd
(0.17 mgd)
1.132 mgd
(3.3 mgd)
5.4 mgd
(10.94 mgd)
6.94 mgd
(16.6 mgd)
Percent of
Capacity with
0.07 mgd
Grassy
Branch WRF
77%
> 100%
60%
73%
67%
Estimated
Distance
from Grassy
Branch WRF
6.6 miles
5.1 miles
9.0 miles
19.9 miles
9.5 miles
1 Old Sycamore Creek WRF is permitted as a land application system via non -discharge permit WQ0011928.
2 Data from 2019 and 2020 Local Water Supply Plans.
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Connection to neighboring POTWs has been removed from consideration as a viable alternative to an
expansion of the Grassy Branch WRF. The majority of the identified wastewater treatment facilities are
outside of a five -mile radius from the Grassy Branch WRF. This alternative would require extensive
conveyance infrastructure, resulting in elevated capital and operation and maintenance (O&M) costs. The
most proximate treatment facility to the Grassy Branch WRF does not have available treatment capacity
for the Grassy Branch sewershed.
3.4 Land Application
Land application of wastewater effluent was evaluated as a discharge alternative to an expansion of the
Grassy Branch WRF. Land application systems include individual or community onsite subsurface
systems, drip irrigation, and spray irrigation. Land application systems generally do not require advanced
secondary treatment processes prior to irrigation per North Carolina Administrative Code (NCAC)
15A 02T, Waste Not Discharged to Surface Water. Typically, only preliminary treatment is used. Land
application systems also do not facilitate other options for effluent disposal, such as reuse or high -rate
infiltration. Secondary effluent limits for land application include BOD5 and total suspended solids (TSS)
less than 30 mg/L, ammonia less than 15 mg/L, and fecal coliform Tess than 200 colonies/100 ml. Influent
pumping, screening, and equalization for the additional 0.07 mgd to be land applied would be located on
the treatment plant site.
Suitable property for disposal of land application effluent must be acquired to dispose of the additional
0.07 mgd. A conservative land application rate of 1 inch per acre per week was selected based on similar
systems in North Carolina and published criteria (EPA, 2006). Including land for a storage pond, wetlands,
buffers, and access roads, Union County would need to acquire a minimum of 32 acres of land for effluent
disposal of 0.07 mgd. Figure 3-2 illustrates the properties evaluated based on size, zoning classification,
and proximity to the treatment plant. The closest suitable land application site with sufficient available land
was approximately 1 mile from the Grassy Branch WRF. The identified plot is approximately 52 acres with
a zoning designation of RA 40. Detailed investigations were not performed to determine the suitability of
the land for application or the availability of the property.
Research suggests that land application of secondary treated effluent may reduce the porosity of soil
(i.e., clogging) and the infiltration rate over time (Clanton and Slack 1987). Therefore, more land may be
required to dispose of the same quantity of effluent as the system ages. Additionally, land application
systems do not maximize the value and service of the property due in part to the large buffer areas that
are required.
Table 3-4 summarizes the total present worth for the land application disposal alternative. Costs include
land acquisition, spray field infrastructure, effluent pumping, conveyance, and preliminary treatment at the
Grassy Branch WRF. The total present worth for this alternative is approximately $7,720,000. Attachment
A provides the design, capital cost, and O&M cost calculations for the land application alternative.
The land application alternative has been removed from consideration for several reasons. This alternative
is not as economically feasible as the selected alternative. The total present worth cost is approximately
$2 million higher than the selected alternative. Additionally, Union County would be responsible for
operating two separate wastewater treatment systems, which is an increase in annual O&M cost.
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Furthermore, the County would anticipate negative public perception of siting a land application system in
primarily residential areas. Site security will also pose a concern.
Table 3-4: Present Worth Analysis for Land Application
Capital Annual Useful Life, Salvage
Cost 1 2 O&M Cost 3' 4 years 5' 6 Amount'
Land application capital cost:
Land acquisition
Spray field infrastructure
Access roads
Storage pond
Storage pond liner
Pump station at WRF
Pump station at land
application site
Effluent force main
Monitoring wells
Fencing
Capital cost for Grassy
Branch WRF expansion
Engineering / Legal /
Construction
$394,000
$525,000
$581, 000
$221,000
$69,000
$238,000
$164,500
$187,000
$150,000
$138,000
$720,000
$1,500,000
$56,700
$168,000
$394,000
20 $0
20 $0
40 $110,500
20 $0
40 $119,000
40 $82,250
40 $93,500
40 $75,000
20 $0
33.2 $286,000
Total
$4,888,000 $224,700 $1,160,000
Total Present Worth of O&M $3,570,000
Total Present Worth of Salvage $736,000
Total Present Worth $7,720,000
All costs in 2021 dollars.
2 Construction subtotal includes contingency, contractor's general conditions, bonds, insurance, overhead, and
profit (25% + 20%).
3 Time period of 20 years with an interest rate of 2.3% (EPA 2020 Discount Rates Circular A-94).
4 Grassy Branch WRF O&M cost based on annual Grassy Branch Operating Budget.
5 Grassy Branch WRF salvage amount calculated assuming 66% structural life and 34% mechanical life.
6 Useful life assumes a piping, electrical, and structural life of 40 years and a mechanical life of 20 years.
' Land assumed to have a 100% salvage value.
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3.5 Non -Conjunctive Reuse
In addition to land application, a non -conjunctive reuse system was evaluated as a discharge alternative
for the expansion of the Grassy Branch WRF. Reuse is the beneficial reuse of tertiary treated wastewater
effluent. DWR defines non -conjunctive reuse as a wastewater treatment system that relies on reclaimed
water uses to account for all the generated wastewater (i.e., zero direct discharge to surface water).
Design criteria for reclaimed water systems in which an irrigation system is required to meet the needs of
the facility are more stringent than for land application systems. Per NCAC 15A 02T, Waste Not
Discharged to Surface Waters, effluent criteria for reclaimed water systems include BOD5 Tess than
10 mg/L, TSS less than 5 mg/L, ammonia less than 4 mg/L, fecal coliform less than 14 colonies/100 ml,
and a maximum turbidity of 10 NTU.
This alternative involves the development of a non -conjunctive reuse system to land apply the 0.07 mgd of
expanded treated effluent from the Grassy Branch WRF onto suitable land within a 5-mile radius of the
treatment plant. This alternative would require the expansion of the Grassy Branch WRF as well as
additional disinfection to meet reclaimed water standards. Treated effluent would be pumped from the
Grassy Branch WRF to a storage pond at the reuse application site. Refer to Figure 3-2 for a general
location of a potential dedicated spray irrigation site. In addition to treatment design criteria, NCAC 15A
02T provides design criteria for distribution lines and reclaimed water utilization. Setback requirements for
irrigation and utilization areas are less stringent than for land application systems. The required setbacks
for treatment and storage facilities in reclaimed water systems are identical to those for land application
systems.
Production of reuse quality effluent allows a greater range of options for land application other than a
dedicated land application site. These effluent disposal options include golf courses, residential lawns,
parks and school grounds, athletic fields (e.g., soccer, baseball, football), irrigation of crops, and industrial
uses (such as cooling and wash down water). Additionally, beneficial reuse is considered by many
communities as a supplement to the NPDES discharge, particularly to offset potable water demand in the
hot summer months. Water reuse systems in North Carolina are generally landscape irrigation -based
systems that experience high demands during the hot, dry summer season and little to no demands during
the cool, wet winter season.
A cost-effective reduction of a surface water discharge requires commercial and industrial users on a year-
round basis. Ideally, reuse options could help to offset high potable water demands during the spring and
summer seasons when residential irrigation and other demands peak. However, potential reuse demand
within a 2-mile radius of the plant is low, with limited reuse water applications near the plant.
• No potential irrigation sites (golf courses, residential lawns, etc.) were identified within a
2-mile radius of the plant.
• No significant industrial users (Sills) or agricultural reuse opportunities exist near the
treatment plant.
• Plant effluent quality will generally meet reuse requirements for monthly average and
daily maximum BOD5, TSS, and ammonia limits. Additional disinfection would be required
to meet reclaimed water fecal coliform standards.
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Table 3-5 summarizes the total present worth for the non -conjunctive reuse disposal alternative. Costs
include land acquisition, spray field infrastructure, effluent pumping and force main, sitework and
expansion of the Grassy Branch WRF. The total present worth for this effluent disposal option is
approximately $8,550,000. The capital and total present worth costs are 166% higher than the cost of the
selected alternative. Attachment B provides the design, capital cost, and O&M cost calculations for the
non -conjunctive reuse alternative.
The non -conjunctive reuse water was removed from consideration as a viable alternative. The extreme
seasonal variation in non -potable water demand requires a dedicated property(s) for spray irrigation. Site
security, additional operation and maintenance costs associated with a second treatment system, and high
capital costs are inherent to this alternative. Similar to the land application alternative, the County would
anticipate opposition from the public regarding a use of land inconsistent with the surrounding residential
area.
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Table 3-5: Present Worth Analysis for Non -Conjunctive Reuse System
Land application capital cost:
Land acquisition
Spray field infrastructure
Access roads
Storage pond
Storage pond liner
Pump station at WRF
Pump station at land
application site
Effluent force main
Monitoring wells
Fencing
Chlorine disinfection at WRF
Capital cost for Grassy
Branch WRF expansion
Engineering / Legal /
Construction
Capital Annual Useful Life, Salvage
Cost', 2 O&M Costa 4 years 5' 6 Amount'
$394,000
$525,000
$581,000
$47, 000
$17,000
$238,000
$164,500
$187,000
$150,000
$138,000
$130,000
$2,100, 000
$1,500,000
$57,700
$168,000
$394,000
20 $0
40 $290,500
40 $23,500
20 $0
40 $119,000
40 $82,250
40 $93,500
40 $75,000
20 $0
20 $0
33.2 $834,940
Total $6,172,000 $225,700 $1,913,000
Total Present Worth of O&M $3,590,000
Total Present Worth of Salvage $1,214,000
Total Present Worth $8,550,000
' All costs in 2021 dollars.
2 Construction subtotal includes contingency, contractor's general conditions, bonds, insurance, overhead, and
profit (25% + 20%).
3 Time period of 20 years with an interest rate of 2.3% (EPA 2020 Discount Rates Circular A-94).
' Grassy Branch WRF O&M cost based on annual Grassy Branch Operating Budget.
5 Grassy Branch WRF salvage amount calculated assuming 66% structural life and 34% mechanical life.
6 Useful life assumes a piping, electrical, and structural life of 40 years and a mechanical life of 20 years.
' Land assumed to have a 100% salvage value.
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3.6 Expand the Grassy Branch WRF and Surface Water Discharge to Crooked Creek
(Selected Alternative)
The expansion of Union County's Grassy Branch WRF from 0.05 mgd to 0.12 mgd was identified as the
most favorable project alternative to accommodate the flows in the Grassy Branch service area. No
additional land will be required for this project alternative as all modifications will be restricted to plant
property. This alternative has been selected by Union County to be the most technically feasible, the most
economical, and the most protective of water quality in the receiving stream.
An expansion of the Grassy Branch WRF requires infrastructure improvements necessary to achieve a
rated plant capacity of 0.12 mgd and meet the speculative effluent limits. The facility consists of a
conventional activated sludge process for CBOD5 removal, nitrification, and phosphorus removal. The
facility consists of screening, flow equalization, aeration basins, secondary clarification, tertiary filtration,
UV disinfection, and post aeration. BioWin° process modeling indicates that modifying the existing plant
processes will be successful in achieving permitted effluent limits. The improvements required to meet the
speculative permit limits are summarized as follows:
• Larger influent pumps.
• A retrofit of the existing aeration basin coarse bubble diffusers to fine bubble diffuser
equipment.
• One additional package secondary treatment train to include volume for flow equalization.
• New positive displacement blowers serving the existing and new aeration basins.
• An additional secondary clarifier.
• A new cloth disk filter.
• A new UV disinfection system.
• Additional volume for aerobic digestion.
It is not anticipated that post aeration equipment will be needed for the plant expansion based on the
current plant performance. Plant hydraulics would be evaluated during detailed design. Existing unit
processes will remain in service during construction. It is not anticipated that construction activity will affect
the current facility performance.
The expansion of the Grassy Branch WRF and a surface water discharge to Crooked Creek was identified
to be the most technically feasible, the most economical, and the most protective of water quality in
Crooked Creek. Table 3-6 summarizes the total present worth for this selected alternative. The net present
worth for the selected alternative is approximately $5,140,000. This alternative allows the County to
leverage the existing assets on the Grassy Branch WRF site.
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Table 3-6: Present Worth Analysis for Expanding Union County's Grassy Branch WRF
Capital Annual Useful Life, Salvage
Cost 1,2 O&M Cost 3, 4 years 5, 6 Amount'
Capital Cost for Grassy Branch $2,100,000 $168,000 33.2 $834,940
WRF Expansion
Engineering / Legal / $900,000
Construction
Total $3,000,000 $168,000 $835,000
Total Present Worth of O&M $2,670,000
Total Present Worth of Salvage $530,000
Total Present Worth $5,140,000
All costs in 2021 dollars.
2 Construction subtotal includes contingency, contractor's general conditions, bonds, insurance, overhead, and
profit (25% + 20%).
3 Time period of 20 years with an interest rate of 2.3% (EPA 2020 Discount Rates Circular A-94).
4 Grassy Branch WRF O&M cost based on annual Grassy Branch Operating Budget.
5 Grassy Branch WRF salvage amount calculated assuming 66% structural life and 34% mechanical life.
6 Useful life assumes a piping, electrical, and structural life of 40 years and a mechanical life of 20 years.
' Land assumed to have a 100% salvage value.
3.6.1 Water Quality Modeling to Support Expanded Surface Water Discharge
Speculative limits were informally discussed with the Division of Water Resources (DWR) for the upgraded
and expanded Grassy Branch WRF during the process of preparing the SOC application package. DWR
responded that a receiving stream model was necessary to assess water quality impacts of the expanded
flow. The County conducted a site -specific QUAL2K model of the Crooked Creek receiving stream in 2016
and 2017 as part of a broader master planning process. A Final Study Plan was approved by DWR in
July 2016. Site -specific sampling was conducted in August 2016. A draft mod& report was submitted to
the County in 2017.
The QUAL2K model was updated in late summer 2019 to serve as a baseline wasteload model of existing
conditions in the Crooked Creek receiving stream. The model was submitted to DWR staff for review in
August 2019. A meeting was held with DWR staff on October 1, 2019 to discuss the model calibration,
verification, and performance results. Attachment C provides the Crooked Creek QUAL2K Model
Development Report (Tetra Tech, October 2019). The model demonstrated strong performance results
and captured key dissolved oxygen trends.
The calibrated QUAL2K model was then used to assess the impact of the Grassy Branch WRF expansion
flow for both the interim and final proposed effluent limits. The Crooked Creek Model Application Report
for the Grassy Branch VVWTP (Tetra Tech, October 2019) is located in Attachment D. The model
demonstrates that there is assimilative capacity for the final effluent permit limits. Table 3-7 provides a
summary of the anticipated final effluent permit limits. The instream dissolved oxygen standard of 5 mg/L
Page 13/17

Hazen
was met in all conditions. The model results also demonstrated that ammonia toxicity will not be
exceeded.
Table 3-7: Anticipated Final Effluent Permit Limits for the Upgraded and Expanded WRF
Parameter Monthly Average Weekly Average
Flow, mgd 0.120
BOD5, mg/L (April 1 through October 31) 5 7.5
BOD5, mg/L (November 1 through March 31) 10 15
TSS, mg/L 30 45
Ammonia, mg/L (April 1 through October 31) 1 2
Ammonia, mg/L (November 1 through March 31) 2 6
Fecal coliform, geometric mean / 100 mL 200 400
Dissolved oxygen, mg/L > 6
One of the issues raised by DWR staff during the October 1, 2019 meeting was the impact of the Grassy
Branch WRF expansion on downstream turbidity impairment in the Rocky River. Significant sources of
turbidity in the Rocky River watershed have been associated with stormwater run-off and sediment erosion
during rain events. The steady state QUAL2K model does simulate output for TSS. Tetra Tech conducted
a statistical analysis of the relationship between TSS and turbidity at four downstream ambient water
quality sampling sites. Tetra Tech concluded that an expansion of the Grassy Branch WRF is unlikely to
contribute to the downstream turbidity impairment. The impact of the Grassy Branch WRF low effluent flow
compared to turbidity contribution from precipitation events is negligible.
4. Summary
An expansion of the surface water discharge to Crooked Creek was selected as the preferred alternative.
A surface water discharge results in the least economic impact to the County. This alternative also
leverages the existing assets on the Grassy Branch WRF site. The water quality modeling results indicate
that assimilative capacity is available in Crooked Creek for the increased discharge.
Page 14/17

Hazen
5. References
Association for the Advancement of Cost Engineering (AACE) International. 2005. Cost Estimate
Classification System — As Applied in Engineering, Procurement, and Construction for the Process
Industries, TCM Framework: 7.3 — Cost Estimating and Budgeting. (Recommended Practice No. 18R-97).
Black & Veatch. December 2011. Final Comprehensive Water & Wastewater Master Plan; Population,
Water Demand, & Wastewater Flow Projections for Union County, NC.
Clanton, C.J. and Slack, D.C. 1987. Hydraulic Properties of Soils as Affected by Surface Application of
Wastewater. Transactions of the ASAE — American Society of Agricultural Engineers. V. 30(3) p. 683-687.
May/June 1987.
Hazen and Sawyer. 2019. Engineer's Certification, Grassy Branch Wastewater Treatment Plant Special
Order by Consent Application Package. Prepared for Union County Public Works.
Hazen and Sawyer. 2018. Technical Memorandums for Facility Process Improvements for Twelve Mile
Creek Water Reclamation Facility, Crooked Creek Wastewater Treatment Plant, Old Sycamore Creek
Wastewater Treatment Plant, and Tallwood Wastewater Treatment Plant. Prepared for Union County
Public Works.
Monroe, City of. 2019. Local Water Supply Plan. Submitted to Division of Water Resources.
Union County. October 2013. National Pollutant Discharge Elimination System Permit for the Grassy
Branch Wastewater Treatment Plant, NC0085812. Issued by the North Carolina Department of North
Carolina Department of Environmental Quality Division of Water Resources.
North Carolina Department of Environment and Natural Resources (DENR). September 2006. North
Carolina Administrative Code, Title 15A, Waste Not Discharged to Surface Waters. Division of Water
Quality, Environmental Management Commission Raleigh, NC.
Tetra Tech. October 2019. Crooked Creek QUAL2K Model Development Report. Prepared for Union
County Public Works Department and Hazen and Sawyer.
Tetra Tech. October 2019. Crooked Creek Model Application Report for the Grassy Branch WWTP.
Prepared for Union County Public Works Department and Hazen and Sawyer.
Union County. January 2020. Grassy Branch Wastewater Treatment Plant Special Order by Consent
Application Package.
Union County Public Works. 2020. Local Water Supply Plan. Submitted to Division of Water Resources.
United States Environmental Protection Agency (EPA). September 2006. Process Design Manual — Land
Treatment of Municipal Wastewater Effluents. EPA/625/R-06/016. Office of Research and Development,
Cincinnati, Ohio.
Page 15/17

Tallwood Estates WRF
(0.05mgd)
(Olde Sycamore WRF
(0.15 mgd)_
Crooked Creek WRF
(1.9`mgd)
rTwelvemile Creek WRF
(7.5 mgd)
Legend
Q Existing Water Reclamation Facility Property
Sanitary Sewer Pipe
C ) 5-Mile Radius of Grassy Branch
MI Grassy Branch Parcel
In Grassy Branch WRF Sewershed
() Union County Boundary
Primary Road
" Major Waterway
.°. Major Waterbody
Grassy Branch WRF
(Existing 0.05 mgd; Proposed 0.12 mgd)
City of Monroe WWTP
(10.4 mgd)
1 inch equals 5 miles
Miles
0 2.5 5 10
Figure 3-1: UCPW Existing Facilities Service Area
Grassy Branch WRF Major NPDES Modification
Union County, NC
Hazen

Mecklenburg
County
Union
County /
1
•
•
•
•
/
o ,V
Q s
p4evi
Legend
® Selected Parcel
r� Parcels - 40+ acres with no structure
MI Grassy Branch WRF
111. Grassy Branch WRF Sewershed
5-Mile Radius of Grassy Branch
Major Waterway
County Boundary
♦
♦
•
•
000
♦
,
Stanly County
/
1 inch equals 1 mile
immi Miles
0 0.5 1 2
Figure 3-2: Location of Potential Land Application Sites
Grassy Branch WRF Major NPDES Modification
Union County, NC
Hazen

Hazen
Attachment A: Design, Capital Cost, and
Operation and Maintenance Cost Calculations for
Land Application Alternative

Land Application Calculations for 0.07 mgd Plant Flow
DESIGN FLOWRATE:
LAND REQUIRED:
Area for Avenge Daily Flow (A,) (Land Application)
Loading Rate:
Loading Rate:
Land Required (Equation)'
0.070
mgd Note: Proposed Grassy Branch design maximum month flow from 0.05 mgd to 0.12 mgd
52.0 in/ac-yr
n/ac-week
Flow(mgd) • 365 days/vr
1.00
Loadingrate in/ac• r • 27,154 gal/ac•in
Land Required: acres
Offsite Storage Pond Area Required (Asp) (Treated Water)
Storage Capacity:
Storage Volume Required:
Assume Depth for Pond:
Precipitation Allowance:
Freeboard:
Water Depth:
Storage Pond Area:
Land Required for Application + Land required for Storage
Allowance for Buffer Yards and Access Roads
30
280,729
8
-1
-2
5
days
ft"3
feet
feet
feet
feet
acres
19 acres
Allowance for Circumventing Wetlands and Unusable Land Due to Topo
Percentage of Wetted Area: 25%
4.8
Total Land Required:
Estimate
Design Flow(mgd) • Storage Capacity(days) / 7.48 gal/ft"3
Storage Volume / (Water Depth • 43560 ft"2/ac)
Percentage of Wetted Area: 35% Based on past projects, actual parcels unknown
6.8 acres
Based on past projects, actual parcels unknown
Parcel Acreage Available 52.0 'acres Based on GIS
acres
CAPITAL COST CALCULATIONS
Capital Cost for Land:
Total Land Required:
Estimated Land Cost:
Capital Cost for Land:
52
Capital Cost of Land Application System (Spray Irrigation Infrastructure):
Land required for application: 18
Estimated Cost for Spray Field:
ENR Index 2000:
ENR Index 2020:
Estimated Cost for Spray Field:
Cost for Spray Field:
Cost of Access Roads:
Cost of Storage Pond:
Cost of Pond Liner
Road Width =
Gravel Thickness =
Road Length =
Road Length =
Road surface area =
Prepare sub -base =
3/4" Stone Base - 3" thick =
Total Cost =
Cost of Roads =
Pond Depth =
Pond Area =
Clear & Grub Area =
Excavation Volume =
Compaction Volume =
Clear & Grub Unit Cost =
Excavation Unit Cost =
Compaction Unit Cost =
Total Earthwork Cost =
$15,500
6221
11466
$29,000
9
3
5
26,400
26.400
15
7
22.00
acres ATOTAL
$/acre Average land value found using GIS
Total Land Requirement • Estimated Land Cost
acres
AWETTED
Original Value
Includes pipe manifolds and valves, clearing, site lighting, etc.
feet
inches
miles
feet
yd"2 Width • Length / 9 ft"2/yd"2
$/yd"2 Estimate
$/yd"2 Estimate
$/yd"2
Road Surface Area • Total Cost
8 feet Earthwork Volumes: Assume 1/2 depth is excavated and this material is used to create bens.
1.3 acres
1.3 acres Entire Pond Area
8,318 yd"3 1/2 Total Depth • Pond Area • 43560 ft^2/ac / 27 ft"3/yd"3
8,318 yd"3 1/2 Total Depth • Pond Area • 43560 ft"2/ac / 27 ft"3/yd"3)
$10,000
$12,889
$18
$149,722
$7.00
$58,225
$/acre Hazen estimate
$/yd"3 Hazen estimate
$/yd"3 Hazen estimate
Storage pond volume = 280,729 ft"3
Storage pond area = 35,091 ft"2
Required Liner for Pond Width and Depth = 49,303 ft"2
Cost of pond liner = $1.40 $/ft"2
Total Liner Cost =
Cost of Pump Station at WWTP (to Pump Land App Site)
Flow =
Add twice the depth and extra 2 feet for edges to both the length and the width
From pond liner provider websites (Firestone Pond Guard) with labor for installation, shipping, etc.
0.175 mgd 0.70 gpd x 2.5 PF
Sitework, subgrade, concrete = $30,000 Includes labor and installation
Mechanical = $110,000 Includes labor and installation
Electrical = $33,000 Includes labor and installation
Materials and Labor Escalation = $15,000
Contractor O&P, contingency, bonds, etc. = $50,000
New Pump Station at WWTP=
Cost of Pump Station at Land App Site
Page 1

Cost of Force Main:
Sitewofk, subgrade, concrete = $25,000 Includes labor and installation
Mechanical = $75,000 Includes labor and installation
Electrical = $22,500 Includes labor and installation
Materials and Labor Escalation = $12,000
Contractor O&P, contingency, bonds, etc. = $30,000
New pump station at land application she =
Flow =
Diameter =
Length =
Length =
Hazen -Williams C =
Velocity =
headloss =
Static Head
Total Head Loss
Total Length of Pipe =
Cost of DIP =
Total Cost of Force Main =
0.175
4
0.74
3,900
110
3.1
58
30
(
Determine Pipeline Size & headloss (Using Hazen -Williams Eq.):
mgd 0.07 mgd x 2.5 peak = 0.175 mgd
inch One Force Main to Land Application Site
miles
feet
ft/s
feet
feet
88 feet
3,900 feet
48 1
$/fit ($1211n-diameter foot)
Cost of Monitoring Wells:
Assume: - Need one(1) upgradient and three(3) downgradient wells at each spray field
and lagoon/storage pond site I 3 I sprayfields
- Depth of well to be 20 feet
Cost of Fencing:
No. of wells =
Cost per well =
Total Monitoring system cost =
Unit Cost of Fencing =
Length of Fence =
Cost of Fence =
15
$10,000
23
6,000
$138,000
$/LF installed
feet
at 6 acres per sprayfield
Estimate based o n acres
ANNUAL O&M COSTS:
Spray Head Replacement
Control Valve Replacement
Anor
Radius of Spray =
Area of Spray =
# of heads =
Percent per year replacement =
Replacement per year =
Cost per spray head =
Annual Replacement cost =
Control Valves per acre =
Unit cost for control valve =
Control valve replacement interval =
Annual Replacement cost =
Spray Head and Control Valve Labor Costs
Lawn Mowing
Pump Station at WWTP
Labor per hour =
Labor per year =
Annual Labor =
Labor =
Labor per hour =
Cost per acre mowing =
No. of times mowed per year =
Mowing Cost =
Peak Flow =
Pipe Diameter =
Force Main Length =
Hazen-Willams C =
Velocity =
Headloss =
Static head =
Total Headloss =
Midpoint Flow =
Total Dynaminc Head =
Pump Efficiency =
Pump Motor Power =
Electrical Cost =
Annual Power =
Power Cost
788,209
25
1963
410
10%
(t�
feet
ft�
spray heads
41 spray heads
2
500
0.2
1111111111111
1.5
32
48
Based on past projects
Based on past projects
valves/acre Based on past projects
$/valve Based on past projects
years Based on past projects
$/hr
hours
$/year
hrs/acre
$/hr
$/acre
times/yr
$/yr
0.175 mgd
4 inches
3,900 feet
110
3.10 Wsec
57.83 feet
30 feet
87.83 feet
60.8 gpm
88 feet
65%
2.1
$0.070
13,521
HP
$/kw-h
kwh/year
$/year
Based on past projects
Based on past projects; 52 hour for 3x the heads
Once per week warm months, twice monthly colder months
Assume equalization, peaking factor of 2.5
Power costs based on mid -point of design flow.
Total operating horsepower
Page 2

Pond and Pump Station Maintenance
$/gal =
Total =
TOTAL ANNUAL O&M COSTS
r r
SUMMARY - CAPITAL COSTS:
Land Acquisition
Spray Field Infrastructure
Access Roads
Storage Pond
Storage Pond Liner
Pump Station at WWTP
Pump Station at Land Application Site
Effluent Distribution Force Main
Monitoring Wells
Fencing
Total Cost
$394,000
$525,000
$581,000
$221,000
$69,000
$238,000
$164,500
$187,000
$150,000
$138,000
$/1,000 gal / day Power (site pump station, lights, etc.), pond inspection and
maintenance (e.g., algae control, etc.)
SUMMARY - ANNUAL O&M COSTS:
Spray Head Replacement $1,000
Control Valve Replacement $3,620
Spray Head and Control Valve Labor Costs $400
Lawn Mowing $38,000
Pump Station at WWTP $900
Pond and Pump Station Maintenance $12,800
Total Cost
Page 3

Hazen
Attachment B: Design, Capital Cost, and
Operation and Maintenance Cost Calculations for
Non -Conjunctive Reuse Alternative

Reuse Calculations for 0.07 mgd Plant Flow
'Closest Golf Course is Charlotte National Golf Club. 7.5 miles away
DESIGN FLOWRATE:
LAND REQUIRED:
Area for Average Daily Flow (Ajwr) (Reuse)
0.070
mgd Note: Proposed Grassy Branch design maximum month flow from 0.05 mgd to 0.12 mgd
Loading Rate: 52.0 in/ac-yr
Loading Rate: I 1.00 tin/ac-week
Land Required (Equation): Flow(mgd) ' 365 tlays/yr
Loadin rate in/ac' r • 27,154 gal/ac'in
Land Required: acres
Offsite Storage Pond Area Required (Aw) (Treated Water)
Storage Capacity:
Storage Volume Required:
Assume Depth for Pond:
Precipitation Allowance:
Freeboard:
Water Depth:
Storage Pond Area:
Land Required for Application + Land required for Storage
46,952
6
-2
3
days
ft"3
feet
feet
feet
feet
acres
18 acres
Allowance for Buffer Yards and Access Roads
Percentage of Wetted Area: 15%
2.8 acres
25% of design flow plus 5-day reject storage
Design Flow(mgd) • Storage Capacity(days) / 7.48 gal/ft^3
Storage Volume / (Water Depth • 43560 ft"2/ac)
Based on past projects, actual parcels unknown
Allowance for Circumventing Wetlands and Unusable Land Due to Topo
Percentage of Wetted Area: 20% Based on past projects, actual parcels unknown
3.7 acres
Total Land Required: acres
Parcel Acreage Available ( 52.0 'acres Based on GIS
CAPITAL COST CALCULATIONS
Cost for Land:
Total Land Required:
Estimated Land Cost:
Caphal Cost for Land:
Cost of Land Application System (Spray Irrigation Infrastructure):
Land required for application:
Estimated Cost for Spray Field:
ENR Index 2000
ENR Index 2020
Estimated Cost for Spray Field
Cost for Spray Field:
Cost of Access Roads:
Cost of Storage Pond
Cost of Pond Liner
Road Width =
Gravel Thickness =
Road Length =
Road Length =
Road surface area =
Prepare sub -base =
3/4" Stone Base - 3" thick =
Total Cost =
Cost of Roads =
52.0 acres
$/acre
18 acres
$15,500
6221
11466
$29,000
9
3
5
feet
inches
miles
26,400 feet
26,400 yd^2 Width • Length / 9 ft"2/yd^2
$/yd^2 Estimate
$/yd"2 Estimate
22.00 $/yd^2
Aroru
Average land value found using GIS
Total Land Requirement • Estimated Land Cost
AwErrEo
Original Value
Includes pipe manifolds and valves, clearing, she lighting, etc.
7
Road Surface Area • Total Cost
Pond Depth = 6 feet Earthwork Volumes: Assume 1/2 depth is excavated and this material is used to create berm .
Pond Area = 0.4 acres
Clear 8 Grub Area = 0.4 acres Entire Pond Area
Excavation Volume = 1,739 yd"3 1/2 Total Depth • Pond Area • 43,560 ft^2/ac / 27 ft^3/yd^3
Compaction Volume = 1,739 yd^3 1/2 Total Depth • Pond Area • 43,560 fP2/ac / 27 ft"3/yd"3
Clear 8 Grub Unit Cost = I $10,000 lb/acre Hazen estimate
$3,593
Excavation Unit Cost = I $18 1$/yd^3 Hazen estimate
$31.301
Compaction Unit Cost = l $7.00 1$4d"3 Hazen estimate
Total Earthwork Cost =
Storage pond volume =
Storage pond area =
Required Liner for Pond Width and Depth =
Cost of pond liner =
Total Liner Cost =
Cost of Pump Station at WWTP to Pump Land App Site
Flow =
$12,173
46,952 ft"3
7,625 ft^2
11,938 ft^2
$1.40 $/ft^2
0.175 mgd
Shework, subgrade, concrete = $30,000
Mechanical = $110,000
Electrical = $33,000
Materials and Labor Escalation = $15,000
Contractor O8P, contingency, bonds, etc. = 550,000
New Pump Station at WWTP =
Added 20% contingency in area to account for unknown site issues.
From pond liner provider webshes (Firestone Pond Guard) with labor for installation, shipping, etc.
0.70 gpd x2.5 PF
Includes labor and installation
Includes labor and installation
Includes labor and installation
Page 1

Cost of Pump Station at Land App Site
Sitework, subgrade, concrete =
Mechanical =
Electrical =
Materials and Labor Escalation =
Contractor O8P, contingency. bonds, etc. =
Cost of Force Main:
New pump station at land application site =
Flow =
Diameter =
Length =
Length =
Hazen -Williams C =
Velocity =
headloss =
Asumed Static Head
Total Head Loss
Total Length of Pipe =
Cost of DIP =
Total Cost of Force Main =
$25,000
$75,000
$22,500
$12,000
$30,000
0.175
4
0.74
3.900
110
3.1
58
30
88
3,900
48
mgd
nch
miles
feet
ft/s
feet
feet
feet
Includes labor and installation
Includes labor and installation
Includes labor and installation
Determine Pipeline Size 8 headloss (Using Hazen -Williams Eq.):
(0.07 mgd x 2.5 peak = 0.175 mgd)
One Force Main to Land Application Site
feet
$/ft ($12/in-diameter foot)
Cost of Monitoring Wells
Assume: - Need one(1) upgradient and three(3) downgradient wells at each Tay field
and lagoon/storage pond site I 3 �sprayfields
- Depth of well to be 20'
No. of wells =
Cost per well =
Total Monitoring system cost =
Cost of Chlorine Disinfection at WWTP
Liquid C12 Feed Pump Quantity =
Unit Cost =
Total liquid feed pump cost =
Cost of Fencing:
Storage Tank - NaOCI =
Unit Cost '-
Storage Tank Cost =
Misc. Valves / Instruments Quantity =
Unit Cost =
Misc. Valves / Instruments cost =
Total Chlorination System Cost =
Unit Cost of Fencing =
Length of Fence =
Cost of Fence =
15
$10,000
2
$30,000
$60,000
$50,000
$50,000
$20,000
$20,000
23
6,000
$138,000
Lump sum
$/LF installed
feet
at 6 acres per sprayfe d
Duty, spare pumps
With installation and pump enclosure
Installed cost (concrete pad, containment, etc.)
Installed cost
Estimate based o n acres
ANNUAL O&M COSTS:
Spray Head Replacement
Control Valve Replacement
A=
Radius of Spray =
Area of Spray =
# of heads =
Percent per year replacement =
Replacement per year =
Cost per spray head =
Annual Replacement cost =
Control Valves per acre =
Unit cost for control valve =
Control valve replacement interval =
Annual Replacement cost =
Spray Head and Control Valve Labor Costs
Lawn Mowing
Pump Station at WWTP Site
Labor per hour =
Labor per year =
Annual Labor =
Labor =
Labor per hour =
Cost per acre mowing =
No. of times mowed per year =
Mowing Cost =
Peak Flow =
Pipe Diameter =
Force Main Length =
Hazen-Willams C =
Velocity =
Headloss =
Static head =
Total Headloss =
Midpoint Flow =
Total Dynaminc Head =
Pump Efficiency =
Pump Motor Power =
Electrical Cost =
Annual Power =
Power Cost =
788,209
1963
410
1
131
41
500
0.2
1.5
32
48
0.175
3,900
110
3.1
58
30
87.83
60.8
88
65%
2.08
SO 070
13,521
ft�
feet
ft°
spray heads
spray heads
valves/acre
bivalve
years
$/hr
hours
$/year
hrs/acre
$/hr
$/acre
times/yr
$/yr
mgd
inches
feet
8/sec
feet
feet
feet
gpm
feet
HP
$/kw-h
kwh/year
$/year
Based on past projects
Based on past projects
Based on past projects
Based on past projects
Based on past projects
Based on past projects
Based on past projects; 52 hour for 3x the heads
Once per week warm months, twice monthly colder months
Assume equalization, peaking factor of 2.5
Power costs based on mid -point of design flow.
Total operating horsepower
Page 2

Pond and Pump Station Maintenance
$/gal =
Total =
O8M Cost for Chlorine Feed
Cl2 Dose=
Required lb/day C12=
Delivered Concentration=
Density of NaOCI at Selected Conc.=
Required gal/day as Delivered CIz =
Volume Delivered at Selected Conc. =
Concentration at End Use =
Required gal/day as Actual CIz =
Days Storage =
TOTAL ANNUAL O&M COSTS
SUMMARY - CAPITAL COSTS:
Total Storage Vol. Req'd =
Total Storage Vol. Req'd =
Number of Tanks =
Volume per Tank =
Tank Height =
Tank Diameter =
$/gal =
Required gal/day =
Cost per Year of Hypochlorite =
$0.500
6
8,76
5.000
1.040
8
4,000
5
8
(
30
253
4,000
4,000
10
7
$0.65
8
253
3,031
$2,000
S/1.000 gal / day power (site pump station, lights, etc.), pond inspection and
maintenance (e.g., algae control, etc.)
ppm Max dose
lb/day CI With 2.5 peak
lb CUgal
gal Cl/day
gal
gal CIz/day
days
gallons
gallons Based on delivery volume
gallons
feet
feet
gal
gal Clz/day
gal/month
gal/year
$/year
Total Chlorination O8M Cost = Divided by two to take the mid -point value for O8M cost (use 0.035 mgd instead of 0.07 mgd)
Land Acquisition $394,000
Spray Field Infrastructure $525,000
Access Roads $581,000
Storage Pond $47,000
Storage Pond Liner $17,000
Pump Station at WWTP $238,000
Pump Station at Land Application Site $164,500
Effluent Distribution Force Main $187,000
Monitoring Wells $150,000
Chlorine Disinfection $130,000
Fencin! $138 000
SUMMARY- ANNUAL OBM COSTS:
Spray Head Replacement $1,000
Control Valve Replacement $3,620
Spray Head and Control Valve Labor Costs $400
Lawn Mowing $38,000
Pump Station at VVWTP Site $900
Pond and Pump Station Maintenance $12,800
Chlorine Disinfection $1,000
Annual OBM Cost
Page 3

Hazen
Attachment C: Crooked Creek QUAL2K Model
Development, Tetra Tech, October 15, 2019

Crooked Creek QUAL2K Model
Development
Union County, North Carolina
October 15, 2019
PREPARED FOR
Union County Public Works
500 North Main Street, Suite 500
Monroe, NC 28112
PREPARED BY
Tetra Tech
One Park Drive, Suite 200
PO Box 14409
Research Triangle Park, NC 27709
Pictured: North Fork Crooked Creek (Tetra Tech, 2016)
[ib
TETRA TECH

(This page was intentionally left blank.)

Crooked Creek QUAL2K Model
October 15, 2019
EXECUTIVE SUMMARY
The Crooked Creek watershed in Union County, North Carolina supports three existing wastewater
treatment plants (WWTPs): Hemby Acres, Crooked Creek #2, and Grassy Branch. These WWTPs
discharge treated effluent directly into Crooked Creek. There are a number of tributaries across the
watershed including the North Fork and South Fork of Crooked Creek, and Grassy Branch which is the
most downstream before the confluence with the Rocky River (Figure 1).
North Carolina
OTETRA TECH
North Fork
Crooked Creek
Hemby Acres
wwTP
Crooked Creek
Grassy Branch
VVWTP
Crooked Creek #2
WWTP
Crooked Creek Watershed
WWTP Outfalls
imv naac.e mai.m+o w v..r.
South Fork
Crooked Creek
N 0051 2
A vw,ometers
0 05 1 2
Miles
Rocky River
Stanly
County
Grassy Branch
Legend
Existing WWTP Outfall
— River/Stream
Highway
Watershed Boundary
County Boundary
Figure 1. Crooked Creek watershed map
A QUAL2K river water quality model was developed to evaluate the existing conditions along Crooked
Creek. The baseline model of existing conditions along Crooked Creek was built, calibrated, and
corroborated using monitoring data collected during the summer of 2016. Monitoring results and other
criteria were used to break the modeled receiving stream into six model stream reaches (Figure 2).
Z{.I TETRA TECH
ES-1

Crooked Creek QUAL2K Model
October 15, 2019
Grassy Branch WWTP
Hemby Acres WWTP
Crooked Creek WWTP #2
fh1
TETRA TECH
Crooked Creek Watershed
QUAL2K Model Segmentation
RAO 100 SURP.* Rath Cat.. FIRS uoo Teel
Rao Raeaua e6-07.2616 ri ra,.a
N 0 05 1 2
A ...Kilometers
0 05 1 2
Aides
Rocky River
Legend
WWTP Discharge
. - Large Beaver Dam
----- River/Stream
OWatershed Boundary
Model Reach
*mamma Reach 1
emmaraa Reach 2
Reach 3
Roacha
ee� Roach 5
Reach 6
Figure 2. Crooked Creek QUAL2K model reach segmentation
A strong model calibration result was achieved for DO (Figure 3). The model simulation of daily average
DO concentration captured key trends along the stream longitudinally, particularly in accounting for
diurnal variation. A model corroboration simulation also demonstrated a similarly strong model
performance (Figure 4). Sensitivity analyses revealed that the model was most sensitive to assumptions
for sediment oxygen demand and reaeration, but results were relatively robust given strong assumptions
based on good monitoring data.
QTETRA TECH
ES-2

Crooked Creek QUAL2K Model
October 15, 2019
I_1-1 2 I 3 _ I- _I- 5 I 6 1HVV12
Hemby CC#2 • SFCC Grassy WWTP,
WWTP WWTP confluence 601 601 Grassy Branch confluence
Beaver
IDams
1 t.
• 8
8
•
•
r
` i r
• O •
O
•
20
• Or)
• 0 6 —
• YPDRBA Point Data
o Obs Long Data (AM) Trip 2
- - - - Simulated Min/Max
DO Saturation
O •
`,O
•
•
• •
•
.-er- • m0 o • ••• •
•
•
15 10 5 0
Distance from outlet (miles)
O Obs Long Data (AM) Trip 1 • Obg Long Data (PM) Trip 1
• Obs Long Data (PM) Trip 2 Simulated Mean
Observed Sonde Data WQS: 5.0 mg/l
Figure 3. Simulated and observed DO along Crooked Creek (calibration)
I-1--1_ _2�_--1
Hemby CC#2
WWTP WWTP
r ri
r `
r
r __ -r
r
I A•
r`�
• `
•
20
• YPDRBA Point Data
—Simulated Mean
WQS: 5.0 mg/I
3 I 4 I 5 1 6
SFCC HWY Grassy WWTP,
•
confluence 601 Grassy Branch confluence
Beaver
Dams
------- •-lb
10
6
4
2
112
_• • •.
%
r r
r r
r r
r .r
sO •
---------r
•
15 10 5 0
Distance from outlet (miles)
0 Obs Long Data (AM) • Obs Long Data (PM)
- - - - Simulated Min/Max Observed Sonde Data
--- DO Saturation
Figure 4. Simulated and observed DO along Crooked Creek (corroboration)
10
Dissolved Oxygen (mg/I)
nTETRA TECH
ES-3

Crooked Creek QUAL2K Model October 15, 2019
TABLE OF CONTENTS
1.0 INTRODUCTION 1
2.0 SUMMARY OF AVAILABLE DATA 3
2.1 Goose and Crooked Creeks LWP 3
2.2 Permitted Point Source Monitoring 3
2.3 YPDRBA (Coalition) Instream Sampling 5
2.4 Tetra Tech Sampling 5
2.5 HEC-RAS Modeling Efforts 6
2.6 Goose and Crooked Creek LSPC Model 6
3.0 QUAL2K MODEL SETUP 8
3.1 Model Documentation 8
3.2 Model Date Selection 8
3.3 Model Segmentation 8
3.4 Reach Hydraulics 10
3.5 Meteorological Inputs, Light and Heat 12
3.5.1 Hourly Inputs 12
3.5.2 Light and Heat Inputs 14
3.6 Carbonaceous Biochemical Oxygen Demand Simulation 15
3.7 Boundary Conditions 15
3.7.1 Headwaters 15
3.7.2 Point Source Flows and Water Quality 19
3.7.3 Tributary Flows and Water Quality 22
3.8 Reach Water Quality Parameters 23
4.0 MODEL CALIBRATION AND CORROBORATION 26
4.1 Hydrology Calibration 26
4.2 Water Temperature Calibration 27
4.3 Water Quality Calibration 28
4.4 Model Corroboration Results 29
4.4.1 Water Temperature Corroboration 29
4.4.2 Water Quality Corroboration 30
5.0 MODEL SENSITIVITY 31
6.0 REFERENCES 34
® TETRA TECH
1

Crooked Creek QUAL2K Model
October 15, 2019
C.1 Stream Hydrology Measurements 43
C.2 Nutrient Sampling 44
C.3 Longitudinal Dissolved Oxygen 48
C.4 Diurnal Dissolved Oxygen 60
LIST OF TABLES
Table 1. Existing permit limits for the wastewater treatment plants located along Crooked Creek. 5
Table 2. Reach segmentation for Crooked Creek QUAL2K model 9
Table 3. Reach hydraulic model setup inputs 11
Table 4. Meteorological inputs data source summary 12
Table 5. Hourly inputs for air temperature, dew point temperature, and cloud cover 13
Table 6. Light and heat model setup inputs 14
Table 7. USGS flow conditions in adjacent Goose Creek watershed (flows in cfs) 16
Table 8. Headwater water quality initial model inputs (calibration model) 18
Table 9. Headwater water quality initial model inputs (corroboration model) 19
Table 10. Point source flow and water quality inputs (calibration period) 20
Table 11. Point source flow and water quality inputs (corroboration period) 21
Table 12. Tributary flow and water quality inputs (calibration model) 22
Table 13. Tributary flow and water quality inputs (corroboration model) 23
Table 14. Model inputs for bottom algae coverage 24
Table 15. Crooked Creek QUAL2K model sensitivity test runs 31
Table 16. Crooked Creek QUAL2K model sensitivity test run results 33
LIST OF FIGURES
Figure 1. Crooked Creek watershed map 1
Figure 2. Crooked Creek QUAL2K model reach segmentation 2
Figure 3. Simulated and observed DO along Crooked Creek (calibration) 3
Figure 4. Simulated and observed DO along Crooked Creek (corroboration) 3
Figure 5. Crooked Creek watershed location map 2
Figure 6. Crooked Creek watershed elevation and reach map 2
Figure 7. Crooked Creek point source discharge locations and YPDRBA water quality sampling sites 4
® TETRA TECH
2

Crooked Creek QUAL2K Model October 15, 2019
Figure 8. LSPC model extent and subbasins for the Goose and Crooked Creek watersheds 7
Figure 9. Crooked Creek QUAL2K model reach segmentation 9
Figure 10. Crooked Creek summer 2016 cross sectional surveys by Tetra Tech 10
Figure 11. Crooked Creek channel bottom width measured from summer 2016 cross sections 11
Figure 12. Crooked Creek stream discharge estimates 16
Figure 13. Simulated and site -estimated flows for Crooked Creek model extent (calibration) 27
Figure 14. Simulated and observed water temperature along Crooked Creek (calibration) 28
Figure 15. Simulated and observed DO along Crooked Creek (calibration) 29
Figure 16. Simulated and observed water temperature along Crooked Creek (corroboration) 30
Figure 17. Simulated and observed DO along Crooked Creek (corroboration) 30
Figure 18. Sensitivity test results (runs 1 and 2): bottom algae coverage and SOD rate 32
Figure 19. Sensitivity test results (runs 3, 4, and 5): Manning's n, shade, and headwater flow 32
Figure 20. Sensitivity test results (run 6): reaeration model selection 33
® TETRA TECH
3

1.0 INTRODUCTION
Crooked Creek is a Class C waterway, with the South Fork, North Fork, and Crooked Creek downstream
of the confluence all listed as Category 5 impaired waterways for turbidity and ecological/biological
integrity (NC DENR, 2016). The Crooked Creek watershed is located largely in Union County, North
Carolina with a small fraction of land in the headwaters located in Mecklenburg County. The watershed is
on the southeastern extent of the Charlotte metropolitan area, immediately east of the City of Matthews.
The North Fork and South Forks of Crooked Creek join north of the City of Monroe, then flow eastward as
Crooked Creek until the confluence with Rocky River in the Yadkin Pee Dee River Basin (Figure 5). The
Crooked Creek drainage area is about 50 square miles, and the mainstem of the creek currently receives
effluent from three permitted wastewater treatment plants (WWTPs): Hemby Acres, Crooked Creek #2,
and Grassy Branch.
Elevation across the watershed ranges from 406 — 794 feet (124 — 242 meters) (Figure 6). The North
Fork Crooked Creek is approximately 11.6 miles long, South Fork Crooked Creek is 13.9 miles long,
Crooked Creek south of the confluence is 12.2 miles long, and the Grassy Branch tributary is 3.0 miles
long. There are also several small unnamed tributaries within the watershed.
In order to simulate existing conditions along Crooked Creek, a QUAL2K model was set up, calibrated
and corroborated based on data collected in 2016. QUAL2K is a one-dimensional steady-state river water
quality model frequently used for simulating DO (Chapra et al., 2012). QUAL2K assumes a well -mixed
stream channel (both vertically and laterally), and employs a diel, or 24-hour period, heat budget which
can be used to model DO on an hourly basis. Model calibration and corroboration used data collected
during August and September 2016, along with supplemental data from other sources. This report details
data sources, QUAL2K model setup, calibration, corroboration, and sensitivity analyses.
nTETRA TECH
1

Crooked Creek QUAL2K Model
October 15, 2019
TRA TECH
TETRA TECH
Crooked Creek Watershed
South Fork
Crooked Creek
NA 0 075_Kilometers
0 075 15
Miles
Rocky River
Staniy
County
Grassy Branch
Legend
Stream/River
- Highway
---- Interstate
OWatershed Boundary
County Boundary
State Boundary
Figure 5. Crooked Creek watershed location map
Crooked Creek Watershed
Olgltal Elevation Model
South Fork Crooked Creek
N 0 os 1 2
Av�u�ele.,
o e7=
111111
Legend
River/Stream
nWatershed Boundary
County Boundary
Elevation (feet)
High 794
Low 406
Figure 6. Crooked Creek watershed elevation and reach map
TETRA TECH
2

Crooked Creek QUAL2K Model
October 15, 2019
2.0 SUMMARY OF AVAILABLE DATA
The available data related to flow and water quality in the Crooked Creek watershed prior to the summer
of 2016 was relatively limited, therefore field work was conducted by Tetra Tech to provide directly
applicable data required for QUAL2K model setup, calibration, and corroboration. Note that there are no
USGS or other flow gaging stations present within the Crooked Creek watershed. Available data for
Crooked Creek which is relevant to QUAL2K model development is provided below.
2.1 GOOSE AND CROOKED CREEKS LWP
In 2008, the North Carolina Ecosystem Enhancement Program (NCEEP, now referred to as DMS which
stands for Division of Mitigation Services) began development of a local watershed plan (LWP) for the
Goose and Crooked Creek watersheds. The LWP involved preliminary characterization of the watersheds
starting in 2008 and a more detailed watershed assessment starting in 2010. The LWP (Tetra Tech,
2012a) focused on:
• Determining the functional status of aquatic systems in the watershed.
• Identifying key stressors and their sources impacting water quality, habitat, and hydrology.
• Determining where management to address sources and stressors is most needed.
• Identifying potential management opportunities and key assets of the watershed.
Data collection and analysis associated with the LWP were used to inform channel characterization. For
example, there was extensive documentation associated with the channel bed materials, presence of
snags and logs in the streambed, and anecdotal evidence informs decision making in the model such as
the high instream Manning's n roughness values.
2.2 PERMITTED POINT SOURCE MONITORING
There are three point sources present within the Crooked Creek watershed which are permitted through
the National Pollutant Discharge Elimination System (NPDES). Hemby Acres WWTP (NPDES ID:
NC0035041, permitted discharge 0.3 MGD) and Grassy Branch WWTP (NPDES ID: NC0085812,
permitted discharge 0.05 MGD) are minor point sources, whereas Crooked Creek #2 WWTP (NPDES ID:
NC0069841, permitted discharge 1.9 MGD) is classified as a major point source (Figure 7). Effluent
discharge and instream monitoring data collected for these facilities was used to support model setup and
calibration is presented in Appendix A.
Carolina Water Service Inc., which owns and operates the Hemby Acres WWTP located on the North
Fork of Crooked Creek, conducts instream water quality sampling immediately upstream and downstream
of the effluent discharge location. Sampling at these locations approximately 200 feet upstream and 200
feet downstream of the outfall has been collected on a weekly basis since 2014 and consists of
temperature, DO, and fecal coliform bacteria. Carolina Water Service, Inc. also reports treated effluent
flow and water quality data associated with their permitted discharge: flow reported daily, while water
temperature, pH, five-day biochemical oxygen demand (BOD5), ammonia (NH3), DO, and total suspended
solids (TSS) are reported weekly.
® TETRA TECH
3

Crooked Creek QUAL2K Model
October 15, 2019
North Fork
Crooked Creek
Hemby Acres WWTP
(NC0035041)
Q8386000
@ SR 1520
Grassy Branch
WWTP(NC0085812)
Crooked Creek
WWTP 42
(NC0069841)
Q8386200
@ SR 1514
South Fork
Crooked Creek
Rocky River
Stanly
County
Crooked Creek
Q8388900
@ SR 1601
it]
TETRA TECH
Crooked Creek Watershed
Coalition Water Quality Sampling
LW *4,6 '11e's n %KN .
N 0051 2
A OKs,ometers
0 05 1 2
Maes
Q8388000
@NC218
Grassy Branch
Legend
WWTP Discharge Site
Coalition Chemistry Station
- River/Stream
Watershed Boundary
County Boundary
INN
Figure 7. Crooked Creek point source discharge locations and YPDRBA water quality sampling sites
Union County owns and operates the other two NPDES-permitted dischargers located along Crooked
Creek: major discharger Crooked Creek #2 WWTP and minor discharger Grassy Branch WWTP. Treated
effluent flow is reported daily for both dischargers. Water temperature and pH are reported daily for
weekdays only at both sites. BOD5, NH3, DO, and TSS are reported weekly for Grassy Branch and daily
on weekdays for Crooked Creek #2. Chemical oxygen demand (COD) is reported monthly for both sites,
and total nitrogen (TN), total phosphorus (TP), and hardness are reported monthly for Crooked Creek #2.
Note that effluent sampling for Crooked Creek #2 occurs prior to entering a pipe that carries the effluent
from the plant to the discharge location. The distance between the plant sampling point and the pipe
outfall is approximately 2.5 miles, which raised concerns that DO depletion could occur during transit
through the closed system. Tetra Tech's sampling of the effluent, however, showed that DO
concentrations in the effluent leaving the pipe were similar to those recorded at the entrance to the pipe.
The NPDES permit limits for the existing outfalls within the Crooked Creek watershed are detailed in
Table 1.
TE
TETRA TECH
4

Crooked Creek QUAL2K Model
October 15, 2019
Table 1. Existing permit limits for the wastewater treatment plants located along Crooked Creek.
NPDES ID
NC0035041
NC0069841
NC0085812
Facility Name
Hemby Acres
Crooked
Creek #2
Grassy Branch
Permitted Allowable Flows and Concentrations (Summer)
Flow (MGD)
0.3
1.9
0.05
BOD5 (mg/I)
9.0
5.0
5.0
NH3-N (mg/I)
3.0
2.0
2.0
DO (mg/I)
>_ 5.0
6.0
>_ 5.0
TSS (mg/l)
30.0
30.0
30.0
There is one additional permitted discharge located in the watershed, Radiator Specialty Company
(NPDES ID NC0088838) which discharges near the headwaters of the South Fork Crooked Creek. This
permit is associated with groundwater remediation and has a maximum allowable discharge of 0.09
MGD. This discharge is not simulated directly in the Crooked Creek QUAL2K model, however it is
captured indirectly through the model inputs associated with the downstream end of the South Fork
Crooked Creek.
2.3 YPDRBA (COALITION) INSTREAM SAMPLING
There are four Coalition water quality sampling sites in the Crooked Creek watershed which are
monitored by the Yadkin Pee Dee River Basin Association (YPDRBA). Of these four sites, two are located
on the North Fork Crooked Creek (Q8386000, Q8386200), one is located on Crooked Creek below the
confluence of the North and South Forks (Q8388900), and one is located below the confluence of Grassy
Branch (Q8388000) (Figure 7). All four sites monitor temperature (temp), pH, DO, and total nitrogen (TN)
approximately monthly, and Site Q8388000 also measures other nutrient data on a monthly basis since
2013 including nitrate and nitrite (NOX), ammonia (NH3), and total Kjeldahl nitrogen (TKN). These
Coalition sites also monitor turbidity, fecal coliform bacteria, conductivity, and total suspended solids
(TSS) on a monthly basis. These data were used to support model calibration to instream conditions
along Crooked Creek and are presented in Appendix B. Note that sampling at site Q8388900 was
discontinued during 2013.
2.4 TETRA TECH SAMPLING
During the late summer of 2016, hydraulic and water quality sampling was performed by Tetra Tech on
three separate field trips: August 15-19, August 31-September 2, and September 13-16. Sampling efforts
included surveying 20 cross sections along Crooked Creek, estimating flow velocity and discharge, and
generating a log of hydraulic information related to the creek. Water quality sampling on all three trips
involved longitudinal DO sampling by probe, deployment of multi -day sondes for diurnal DO and water
temperature fluctuation measurements, and grab sampling for water quality analyses for oxygen -related
and nutrient -related constituents. The longitudinal samples included direct sampling of the effluent
discharges, and a few small tributaries. The 2016 summer sampling results provided key data for model
parameterization and calibration (Appendix C).
® TETRA TECH
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Crooked Creek QUAL2K Model October 15, 2019
2.5 HEC-RAS MODELING EFFORTS
Two flow models have been created for the Crooked Creek watershed using the Hydrologic Engineering
Center River Analysis System (HEC-RAS) model developed by the US Army Corps of Engineers
(USACE, 2016). HEC-RAS models are used by hydraulic engineers for channel flow and stage analysis
for floodplain determination, typically using design storm events. The combined HEC-RAS models cover
the full extent of Crooked Creek, Grassy Branch, and the North and South Forks. Although HEC-RAS
models are largely developed and applied for high -flow flood condition modeling, certain components of
the models may be useful for low flow steady-state analysis, such as calibration of reach hydraulic
parameters and constraining hydraulic parameterization.
The HEC models in the Crooked Creek watershed covered all of the mainstem and major tributaries.
Most of the HEC-RAS models were obtained from the NC Floodplain Mapping Program — Geospatial and
Technology Management Dept. Several HEC-RAS models for portions of the Crooked Creek mainstem
were provided by Union County. The HEC-RAS models comprise both "Limited Detail Study" and
"Detailed Study" flood models. The "limited detail" models predict flood delineations for the 100-year
storm event using cross section geometry developed from LIDAR data. The "detailed" models are much
more rigorous than "limited detail" studies because they determine specific channel profiles, bridge and
culvert opening geometry, and floodplain characteristics using traditional field surveys. The "detailed
study" model also includes flood profiles for the 10-, 25-, and 50-year storm events.
2.6 GOOSE AND CROOKED CREEK LSPC MODEL
A model was developed to simulate hydrology and water quality in the Goose and Crooked Creek
watersheds in support of watershed planning conducted by NCEEP, Centralina Council of Governments
and North Carolina Division of Water Quality (Tetra Tech, 2012b). This effort involved simulating these
two adjacent drainages using the Loading Simulation Program C++ (LSPC) watershed model to represent
existing conditions (Tetra Tech, 2009a). The LSPC model, a continuous watershed model with a 1-D
stream channel representation, was parameterized based on hydrologic soil groups, land slope
characteristics, and land use/land cover across the two basins. Hydrology was calibrated to observed
streamflow at multiple locations within the Goose Creek watershed. Although there are no flow monitoring
stations within the Crooked Creek basin (and no direct hydrology calibration), the geology and soils of
Crooked Creek are similar to Goose Creek. As a result, model hydrology predictions are likely reasonable
across a range of flows. Water quality calibration was performed for both creeks by comparing simulated
pollutant concentrations and loads to observed values.
® TETRA TECH
6

Crooked Creek QUAL2K Model
October 15, 2019
®TIThA 1104
Crooked Creek Watershed
LSPC Model Extent
A0 OOKAomakis
0 OS
0 8e
Legend
LSPC Model Reach
LSPC Model Subbasm
Crooked Creek Watershed
IIIIGoose Creek Watershed
County Boundary
Figure 8. LSPC model extent and subbasins for the Goose and Crooked Creek watersheds
® TETRA TECH
7

Crooked Creek QUAL2K Model
October 15, 2019
3.0 QUAL2K MODEL SETUP
3.1 MODEL DOCUMENTATION
The most recent version of the QUAL2K model available at the time of this report was used for modeling
Crooked Creek: QUAL2K version 2.12b1. QUAL2K is a river and stream water quality model that is
intended to represent a modernized version of the QUAL2E model (Brown and Barnwell, 1987). QUAL2K
was developed at Tufts University and has been funded partly by the United States Environmental
Protection Agency (Chapra et al., 2012).
3.2 MODEL DATE SELECTION
The QUAL2K model is set up to run for a specific date, and information about latitude, longitude, and time
zone are used to inform solar energy forcing. Based on the summer 2016 sampling, the QUAL2K model
for Crooked Creek was setup and calibrated to a date in August which best represented the first two
sampling trips. The model was corroborated as well by comparing the simulated and observed results
associated with the third sampling trip in September. The first and second trips to the Crooked Creek area
for data collection were August 15 — 19, and August 31 — September 2. Grab samples were taken on
those sampling efforts for the most part on August 16 and August 31 respectively. A date chosen
approximately halfway between those two dates was identified to use as the model calibration date
(August 24, 2016). The model corroboration date was chosen as the grab sampling date of September
14, 2016 during the third sampling field trip which was September 13 — September 16.
There is reasonable justification for combining the first and second field trips into a single calibration
period based on known flow and atmospheric conditions. An analysis of flow gages in the adjacent
watershed of Goose Creek, as well as an analysis of local air temperatures suggest that conditions on the
August 16 and 31 were sufficiently alike to support combining data associated with those two trips for a
single steady state model calibration run. Average air temperature on 8/16 and 8/31 were 84.6 °F (29.2
°C) and 79.4 °F (26.3 °C) respectively. The two USGS flow gages along Goose Creek (0212467451 and
0212467595) both observed streamflow conditions between 0.4 and 0.9 cfs on August 16th and 31st.
Flows at these gages experienced average annual flows in 2016 on the order of 7.0 and 4.4 cfs
respectively, so conditions were considered sufficiently similar and relatively low during the two August
dates compared to the annual statistics.
3.3 MODEL SEGMENTATION
The extent of the Crooked Creek QUAL2K model is defined as upstream of the Hemby Bridge VWVTP on
the North Fork, running 21.0 miles (33.8 kilometers) to the outlet at Rocky River. The total modeled
distance is subdivided into "reaches" which themselves are made up of 0.1-kilometer computational
"elements". In general reach divisions represent areas of approximately similar hydraulic conditions. For
Crooked Creek, the 6 segmented reaches largely reflect key points of interest in the watershed such as
VVWTP discharges or tributary inflows. The reach located downstream from the South Fork Crooked
Creek (SFCC) confluence is segmented at a large beaver dam above Highway 601 because this stretch
is particularly obstructed and sluggish due a series of large beaver/debris dams. This reach between
SFCC and the end of the beaver dams above Highway 601 has significant hydrologic differences than
downstream of the dams, reflected in channel geometry, flow velocity, and observed DO concentrations.
f'-.) TETRA TECH
8

Crooked Creek QUAL2K Model
October 15, 2019
Hydraulic parameterization for each model reach was based on GIS-based spatial analyses of
NHDPIusV2 flowlines, a 3-meter resolution digital elevation model (DEM) obtained from the USDA Data
Gateway, and field data from surveys conducted in August and September 2016. Table 2 and Figure 6
summarize the reach segmentation for the Crooked Creek QUAL2K model which were used for model
setup and did not vary between calibration and corroboration model setups.
Table 2. Reach segmentation for Crooked Creek QUAL2K model
Reach
Description
Reach
Length,
mi (km)
Upstream
Elevation,
ft (m)
Downstream
Elevation,
ft (m)
1
Headwaters to Hemby Bridge WWTP
0.88 (1.42)
623
(190)
617
(188)
2
Hemby Bridge WWTP to Crooked Creek #2
WWTP
2.80 (4.50)
617
(188)
587
(179)
3
Crooked Creek #2 WWTP to South Fork
Crooked Creek (SFCC) confluence
3.75 (6.03)
587
(179)
558
(170)
4
South Fork Crooked Creek (SFCC) to end of
two large beaver dams
1.61 (2.59)
558
(170)
551
(168)
5
End of beaver dams, crossing Highway 601, to
Grassy Branch WWTP
5.21 (8.39)
551
(168)
502
(153)
6
Grassy Branch WWTP to Rocky River
6.72 (10.82)
502
(153)
410
(125)
Hemby Acres WWTP
North Fork Crooked Creek,
Crooked Creek WWTP #2
Crooked Creek
Grassy Branch WWTP
South Fork Crooked Creek
® TETRA TECH
Crooked Creek Watershed
QUAL2K Model Segmentation
MIt .aa! Susw Naw cww• Fl.eS..L D r^
wo e.00a.e 11031717 w..iver
N 0051 2
AOI(dometen
0 05 1 2
OMiiea
,Rocky River
Grassy Branch
Legend
• WWTP Discharge
A Large Beaver Dam
•-• River: Stream
QWatershed Boundary
Model Reach
Raab
Rea.2
Figure 9. Crooked Creek QUAL2K model reach segmentation
® TETRA TECH
9

Crooked Creek QUAL2K Model October 15, 2019
3.4 REACH HYDRAULICS
Stream hydraulics were simulated using the Manning's Formula method within QUAL2K. Model inputs
related to Manning's Formula may vary for each reach and are represented as average conditions based
on the 2016 field survey cross sectional data (Figure 10). There were 20 locations surveyed during
summer 2016, and channel geometry characteristics are used to approximate average conditions for
each model reach. There is a strong relationship between increasing channel bottom width and distance
from the headwaters, reflecting the corresponding increase in drainage area and flow; therefore, the
average distance of each reach from the headwaters was used to approximate channel bottom width
(Figure 11). Surface and bottom channel widths were used to estimate average channel side slopes for
each reach by assuming trapezoidal area.
North Fork Crooked Creek,
Crooked Creek
South Fork Crooked Creek
frb
TETRA TECH
Crooked Creek Watershed
2016 Survey Cross Sections
N 0 os 1 2
A OK,Io,rxters
0 05 1 2
Miles
Rocky River
Grassy Branch
Legend
Cross Section Site
River/Strearn
OWatershed Boundary
Model Reach
Reach 1
Reach 2
Reach
Reath a
Reach 5
Reach 6
Figure 10. Crooked Creek summer 2016 cross sectional surveys by Tetra Tech
TETRA TECH
10

Crooked Creek QUAL2K Model
October 15, 2019
30
w 25
v
20
o 15
Y
m
a 10
c
s 5
U
•
•
•
•
•
y = 0.9833x + 1.764
R2 = 0.7034
•
• • Reach 1(no data)
• Reach 2 (5 sites)
• • Reach 3 (3 sites)
•
• Reach 4 (No Data)
• Reach 5 (6 sites)
• Reach 6 (6 sites)
0 5 10 15
Distance from headwaters (miles)
20
Figure 11. Crooked Creek channel bottom width measured from summer 2016 cross sections
For reach hydraulics, bottom channel widths were estimated based on the regression presented in Figure
11. Channel side slopes were estimated using surface and bottom channel widths and an average depth
of 1 foot (0.32 meters). Bottom widths were generally small, and since water depths were shallow along
the entire Crooked Creek, side slopes are high.
Channel bed slope is calculated as the difference in upstream and downstream elevation divided by the
reach length (refer to Table 1 for raw data). Manning's n (roughness coefficient) can range from about
0.025 - 0.150 for natural streams (Chow, 1959). Manning's n may be subject to alteration during model
calibration because channel roughness is heavily influenced by pool -riffle structures, debris, and
obstructions (Beven et al., 1979). Manning's n was initialized for all reaches as 0.1 which indicates
"mountain streams with boulders" since there is significant data suggesting high debris content and
irregular channel bottoms along the entire stream (Chow, 1959). Manning's n was the only reach
hydraulic parameter adjusted during model calibration.
Table 3. Reach hydraulic model setup inputs
Reach
Location Shorthand
Channel
Bed Slope
Manning's
n
Bottom Width,
ft (m)
Side
Slopes
1
HW to Hemby WWTP
0.0014
0.1
2.17 (0.66)
4.37
2
Hemby WWTP to CC#2 WWTP
0.0010
0.1
4.00 (1.22)
4.71
3
CC#2 WWTP to SFCC
0.0015
0.1
7.43 (2.26)
5.35
4
SFCC to Beaver Dams
0.0006
0.1
10.50 (3.20)
5.93
5
Beaver Dams to Grassy WWTP
0.0014
0.1
13.58 (4.14)
6.51
6
Grassy WWTP to outlet
0.0020
0.1
19.11 (5.83)
7.55
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Crooked Creek QUAL2K Model
October 15, 2019
3.5 METEOROLOGICAL INPUTS, LIGHT AND HEAT
3.5.1 Hourly Inputs
Metrological inputs to the QUAL2K model include air temperature, dew point temperature, wind speed,
cloud cover percentage, and percent of solar radiation blocked by stream shade. Hourly meteorological
data are available through the Weather Underground (www.wunderground.com) for sites near Crooked
Creek. The "Campobello Drive" site in Unionville, North Carolina (KNCUNION2) is located near Crooked
Creek and was identified as the best source of hourly meteorological inputs for the QUAL2K model. For
development of each meteorological input, see Table 4. Average air temperature as developed for model
calibration was 83.1 °F (28.4 °C) with a daily range between minimum and maximum air temperatures of
15.95 °F (8.86 °C). Average air temperature as developed for model corroboration was 86.0 °F (24.6 °C)
with a daily range between minimum and maximum air temperatures of 18.0 °F (10.0 °C).
Table 4. Meteorological inputs data source summary
Parameter
Air
Temperature
Processing Note
Hourly air temperatures (dry bulb temperatures) were calculated as hourly averages of
data from the KNCUNION2 site on 8/16/2016 and 8/31/2016 for the calibration model.
Hourly air temperature from the same station was used from 9/14/2016 for the
corroboration model. Inputs did not vary by reach.
Dew Point
Temperature
Hourly dew point temperatures were calculated as hourly averages of data from the
KNCUNION2 site on 8/16/2016 and 8/31/2016 for the calibration model. Hourly dew
point temperatures from the same station was used from 9/14/2016 for the
corroboration model. Inputs did not vary by reach.
Wind Speed
Hourly wind speed was available from the KNCUNION2 site, however the riparian
vegetation and channel incision shelters the stream so significantly (as observed
during field trips) that wind was assumed to be negligible to the stream for both
calibration and corroboration models. Inputs were set to zero for all hours at all
reaches.
Cloud Cover
Hourly cloud cover were calculated as hourly averages of data on 8/16/2016 and
8/31/2016 from the closest regional airport (Monroe Airport, station ID: KEQY). Hourly
cloud cover from the same station was used from 9/14/2016 for the corroboration
model. Inputs did not vary by reach.
Shade
A single shade percentage of 70% is applied to all hours and all reaches as an
average daily approximation for both calibration and corroboration models. Note that
Crooked Creek is highly shaded, with much of the stream completely sheltered by
vegetation such that the channel cannot be identified through aerial imagery.
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Crooked Creek QUAL2K Model
October 15, 2019
Table 5. Hourly inputs for air temperature, dew point temperature, and cloud cover
Hour
Calibration
Air Temp
(°F)
78.75
Model
Cloud
Cover (%)
0.00%
Corroboration
Model
Dew Point
Temp (°F)
Air Temp
(°F)
Dew Point
Temp (°F)
Cloud
Cover (%)
1
68.42
72.67
66.00
0.00%
2
77.75
67.90
0.00%
71.33
65.00
0.00%
3
76.81
68.13
0.00%
70.17
64.17
0.00%
4
76.20
68.00
0.00%
69.33
64.00
41.67%
5
75.56
68.00
0.00%
69.00
63.50
45.83%
6
74.90
68.00
0.00%
68.00
63.00
50.00%
7
74.30
67.50
0.00%
68.00
63.00
93.75%
8
77.60
70.80
0.00%
68.17
63.33
100.00%
9
81.55
72.25
0.00%
70.00
65.50
100.00%
10
85.50
73.70
31.25%
72.67
68.33
100.00%
11
86.00
74.40
37.50%
75.83
71.33
91.67%
12
88.10
75.80
62.50%
78.00
72.67
25.00%
13
89.60
76.00
50.00%
79.83
73.00
0.00%
14
90.00
75.62
62.50%
81.60
72.40
0.00%
15
89.67
74.80
50.00%
84.00
70.83
0.00%
16
90.25
74.25
0.00%
85.50
70.00
0.00%
17
89.83
74.33
12.50%
86.00
70.00
0.00%
18
89.67
74.33
0.00%
86.00
68.00
50.00%
19
89.38
73.88
0.00%
84.40
69.00
0.00%
20
87.60
72.40
0.00%
82.20
68.20
0.00%
21
84.58
70.90
0.00%
79.33
67.00
0.00%
22
82.20
69.90
0.00%
77.25
67.00
0.00%
23
80.46
69.16
0.00%
75.60
67.00
0.00%
24
79.13
69.00
0.00%
74.60
66.40
0.00%
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Crooked Creek QUAL2K Model October 15, 2019
3.5.2 Light and Heat Inputs
Several parameters related to light and heat functions can be adjusted for a given QUAL2K model. For
model setup, solar inputs are calculated within the model based on latitude, time zone, and Julian day.
Based on these inputs for Crooked Creek on 8/24/2016, sunrise and sunset were calculated within the
model to be at 6:48 AM and 7:58 PM, which were externally verified through the North Carolina Wildlife
Resources Commission, which publicly documents sunrise and sunset times across North Carolina
(www.NCWildLife.org). Sunrise and sunset times for the corroboration model on 9/14/2016 were
calculated in the model as 7:04 AM and 7:29 PM respectively.
Most light and heat parameters were estimated based on suggested values from the QUAL2K manual.
There are a number of options for modeling atmospheric attenuation of solar energy, atmospheric
longwave emissivity, and wind speed function for evaporation and air convection/conduction, and
sediment heat parameters (Table 6).
Table 6. Light and heat model setup inputs
Parameter (units) Model Input Note
Light Parameters
Photosynthetically Available Radiation
0.47
Light parameters initialized based on
QUAL2K example file.
Background light extinction (/m)
0.2
Linear chlorophyll light extinction (/m)
0.0088
Nonlinear chlorophyll light extinction (/m)
0.054
ISS light extinction (/m)
0.052
Detritus light extinction (/m)
0.174
Model Parameters
Atmospheric attenuation model for solar
Bras
Default atmospheric formula for QUAL2K
Atmospheric turbidity coefficient
2
Default value suggested by QUAL2K
Manual
Atmospheric longwave emissivity model
Brutsaert
This equation tends to allow for warmer
water temperatures to be achieved
Wind speed function for evaporation and
air convention
Brady-
Graves -Geyer
Default wind speed function for QUAL2K
Sediment Heat Parameters
Sediment thermal thickness (cm)
20
Model default suggestions from QUAL2K
manual. Default suggestion for sediment
thermal thickness of 10 cm was modified
to 20 cm given the observed presence of
thicker sediment along the channel.
Sediment thermal diffusivity (cm2/s)
0.005
Sediment density (g/cm3)
1.6
Sediment heat capacity (cal/g °C)
0.4
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Crooked Creek QUAL2K Model
October 15, 2019
3.6 CARBONACEOUS BIOCHEMICAL OXYGEN DEMAND SIMULATION
The QUAL2K model simulates instream chemical biological oxygen demand (CBOD) as two different
pools: fast CBOD which is rapidly oxidized and labile in nature, and slow CBOD which is slowly oxidized
and refractory in nature. For the QUAL2K model of Crooked Creek, fast CBOD was used to simulate the
presence of oxygen -demanding substances in WWTP effluent, while slow CBOD was used to simulate
the presence of instream background decay of organic matter such as leaf litter. The QUAL2K manual
suggests that when modeling slow and fast CBOD separately, to keep the distinct pools apart by setting
the CBOD hydrolysis rate to zero, so that choice was made for the Crooked Creek model.
Incubation time for BOD or CBOD measurements in laboratories is typically short-term for five days,
reporting the results as BOD5 or CBOD5 respectively. These five-day concentrations of BOD and CBOD
must be converted to the ultimate concentration of CBOD (CBODultimate) for simulation in QUAL2K in order
to approximate the slow or fast CBOD concentration after some fifty days of decomposition. For slow
CBODultimate simulation in the model the Phelps equation below may be employed, as detailed in the
QUAL2K manual (Chapra et al., 2012):
CBOD5
slow CBODuitimate = 1 — e(klx5)
Note that for the equation above, ki is the rate of oxidation for CBOD which the QUAL2K manual
suggests can range from 0.05 — 0.3 /d. For slow CBODuitimate in the model, 0.05 /d will be used, and for
fast CBODultimate, 0.3 /d will be used in the model environment.
As mentioned above, WWTP effluent was modeled as fast CBODuitimate, which was based on Discharge
Monitoring Report (DMR) data reported as BOD5 concentrations. The original QUAL-II model (NCASI,
1985) internally converted 5-day BOD to ultimate CBOD using a ratio of 1.46 and was not user -specified
(EPA, 1985). Studies have shown that rates can vary significantly from low ratios for domestic wastewater
to very high ratios (e.g., 30) for pulp and paper waste (EPA, 1985). Leo, et al. (1984) summarized the
results for numerous facilities that showed the ratios for secondary to advanced secondary averages from
slightly below to slightly above 2. In the absence of specific lab studies on the existing County plant
effluent BOD5 to CBODultimate ratio, a factor of 2 was assumed:
fast CBODuitimate = 2 x BOD5
In summary, boundary conditions for headwaters and tributaries were simulated as slow CBOD pools
estimated based on in -stream CBOD5 sampling and Phelps first -order reaction equation, while boundary
conditions for effluent point sources were simulated as fast CBOD pools estimated based on DMR BOD5
sampling and a ratio of 2:1 for BOD5:CBODultimate.
3.7 BOUNDARY CONDITIONS
3.7.1 Headwaters
3.7.1.1 Headwater Flows
Of the twenty stream cross -sections surveyed during summer 2016, ten were paired with velocity
measurements to estimate instantaneous streamflow. Stream velocity during each of three separate
sampling trips was so low that a propeller -driven Global Water FP111 Flow Probe velocity meter with a
lower measurement limit 0.3 ft/s (0.1 m/s) was not able to provide an estimate (i.e., velocity was too low to
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Crooked Creek QUAL2K Model October 15, 2019
move the propeller to measure velocity). Therefore, at these ten sites, an orange was timed to float a
specific distance a crude but reasonable way to estimate average channel velocity. Stream discharge
was subsequently approximated at these ten sites by multiplying the estimated flow velocity by cross -
sectional area (Figure 12). This estimation was conducted using a linear regression of eight of the sites,
as two were deemed to be probable outliers and may reflect error in methodology.
7
Vf
u 5
m 4
'a 3
E
2
w
1
0
•
•
y=0.1713x+1.2151
Rz = 0.8221
• Reach 1(No Data)
• . • Reach 2 (2 sites)
� • Reach 3 (2 sites)
• Reach 4 (No Data)
• • Reach 5 (3 sites)
• Reach 6 (1 site)
• Outliers (Reach 3, 6)
•
5 10 15 20
Distance from headwaters (miles)
Figure 12. Crooked Creek stream discharge estimates
Although there are no flow gages located along Crooked Creek, flow gages in the adjacent Goose Creek
watershed during the summer 2016 sampling period revealed that reasonably similar low -flow conditions
were present during all three sampling trips. Streamflow conditions at USGS gages 0212467451 (Goose
Creek at SR1524 near Indian Trail) and 0212467595 (Goose Creek at SR1525 near Indian Trail) were
reported to be similarly low during all summer sampling trips in Crooked Creek (Table 7). Based on the
limited flow data in -hand and the low -flow conditions in the adjacent Goose Creek, it is assumed that flow
conditions were reasonably similar across all three sampling trips to use the same flow boundary
conditions during calibration and corroboration model periods.
Table 7. USGS flow conditions in adjacent Goose Creek watershed (flows in cfs)
USGS gage
0212467451
0212467595
Minimum
Flow, 2016
0.38
0.62
Maximum Average
Flow, 2016 Flow, 2016
98.44
158.78
4.46
7.01
Flow on
8/16/2016
0.61
0.94
Flow on
8/31/2016
0.38
0.78
Flow on
8/14/2016
0.48
0.79
It is possible to use the relationship between discharge and distance from the headwaters to approximate
flows at the headwaters. As seen in Figure 12 and using the linear regression, the best estimate of
headwater flow conditions during the entire summer sampling period of 2016 is 1.215 cfs (0.034 cms).
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Crooked Creek QUAL2K Model October 15, 2019
3.7.1.2 Headwater Water Quality
Water quality conditions at the headwaters to be assumed for model calibration and corroboration periods
were developed from the sampling sites located upstream of the Hemby Acres WWTP. Water
temperature and DO were observed by Carolina Water Services Inc. upstream of the WWTP on a weekly
basis. For the calibration period, the average of conditions from the weeks of the associated trips 1 and 2
were used to generate average headwater conditions for water temperature and DO, while grab sample
site #1 results were averaged for trip 1 and trip 2 for all other applicable constituents. For the
corroboration period, average conditions used during field trip 3 as sampled upstream of Hemby Acres
WWTP were used in tandem with grab sampling at site #1. Headwater water quality inputs for model
initialization for the calibration period and corroboration period are detailed in Table 8 and Table 9
respectively. Headwater boundary conditions specified for the calibration and corroboration periods are
not subject to change although they vary between the two periods based on instream data. Within the
model, the downstream extent was not a prescribed boundary.
For the simulation of CBODuitimate at the headwaters, the entire pool was estimated to be slow CBOD
because upstream of this point does not include any effluent sources. Modeled slow CBOD is
approximated as a function of observed CBOD5 at WQ Grab Site #1 and the slow decay rate detailed in
Section 3.6 of 0.05 /d. Measurements of CBOD5 at Site #1 on field trips 1, 2, and 3 were all non -detects
(detection limit of 2 mg/I), therefore estimates of instream CBOD5 were set to half the detection limit for
the calculation of ultimate slow CBOD to use for model input for both calibration and corroboration:
CBODuitimate =
1 — e('kix5)
mg
mg
slow CBOD at headwaters = 1 — e(_005/d)x5) = 4.52 l
CBODS
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Crooked Creek QUAL2K Model
October 15, 2019
Table 8. Headwater water quality initial model inputs (calibration model)
Parameter
Model Input
Data Source
Water Temperature (°F)
74.8
Average of upstream of Hemby WWTP samples on
8/18/16 (76.3 °F) and 8/30/16 (73.4 °F)
Conductivity (pmhos)
252
Unknown at headwaters, set to average result of all
downstream sondes from Trip 2 (no data from Trip 1)
Inorganic Solids (mg/L)
0
Unknown at headwaters, assume zero
Dissolved Oxygen (mg/L)
4.38
Average of upstream of Hemby WWTP samples on
8/18/16 (4.43 mg/I) and 8/30/16 (4.32 mg/I)
Slow CBOD (mg/L)
4.52
Refractory pool of CBOD calculated based on instream
CBOD5 measurements from WQ Grab Site #1 on Trips
1 and 2
Fast CBOD (mg/L)
0
Organic Nitrogen (pg/L)
508
Calculated as the difference between Trip 1 and Trip 2
observed TKN and NH3 for WQ Grab Site #1; non -
detects set to half of the detection limit.
NH4-Nitrogen (pg/L)
25
Ammonia was not detected in the headwaters from WQ
Grab Site #1 from Trips 1 and 2, therefore the
headwaters were set to half of the detection limit.
NO3-Nitrogen (pg/L)
280
Average of observed NOX at WQ Grab Site #1, Trips 1
and 2.
Inorganic Phosphorus (pg/L)
95
Observed PO4 from WQ Grab Site #1 was used from
Trip 2. The observation from Trip 1 was not used as it
was flagged for quality control exceedances.
Organic Phosphorus (pg/L)
16
Difference between Trip 1 and Trip 2 observed TP and
PO4 for WQ Grab Site #1, excluding flagged PO4
sample.
Alkalinity (mg/L)
100
Unknown at headwaters, use model default
Phytoplankton (mg/L)
0
Unknown at headwaters, assume zero
pH
7
Unknown at headwaters, use model default
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Crooked Creek QUAL2K Model
October 15, 2019
Table 9. Headwater water quality initial model inputs (corroboration model)
Parameter
Water Temperature (°F)
Model Input
71.8
Data Source
Observed upstream of Hemby WWTP samples on
9/12/16
Conductivity (pmhos)
311
Unknown at headwaters, set to average result of all
downstream sondes from Trip 3
Inorganic Solids (mg/L)
0
Unknown at headwaters, assume zero
Dissolved Oxygen (mg/L)
3.63
Observed upstream of Hemby WWTP samples on
9/12/16
Slow CBOD (mg/L)
4.52
Refractory pool of CBOD calculated based on instream
CBOD5 measurements from WQ Grab Site #1 on Trip 3
Fast CBOD (mg/L)
0
Organic Nitrogen (pg/L)
680
Calculated as the difference between Trip 3 observed
TKN and NH3 for WQ Grab Site #1; non -detects set to
half of the detection limit.
NH4-Nitrogen (pg/L)
50
Ammonia was not detected in the headwaters from WQ
Grab Site #1 from Trip 3, therefore the headwaters were
set to half of the detection limit.
NO3-Nitrogen (pg/L)
77
Observed NOX at WQ Grab Site #1 from Trip 3
Inorganic Phosphorus (pg/L)
51
Observed PO4 from WQ Grab Site #1 from Trip 3
Organic Phosphorus (pg/L)
69
Difference between Trip 3 observed TP and PO4 for WQ
Grab Site #1
Alkalinity (mg/L)
100
Unknown at headwaters, use model default
Phytoplankton (mg/L)
0
Unknown at headwaters, assume zero
pH
7
Unknown at headwaters, use model default
3.7.2 Point Source Flows and Water Quality
The three permitted wastewater treatment plant effluent dischargers along Crooked Creek were modeled
explicitly: Hemby Acres WWTP which is operated by Carolina Water Services Inc., and Crooked Creek #2
WWTP and Grassy Branch WWTP which are both operated by Union County.
For the most part, point source model inputs for flow and water quality were based on average conditions
for August (calibration model) and average conditions for September (corroboration model) based on
Discharge Monitoring Report (DMR) data. For parameters not available through DMR monitoring,
concentrations were estimated based on grab samples from the discharge pipe outfalls from trips 1, 2,
and 3 (Table 10, Table 11). DMR reports show that discharge flows and water quality did not vary widely
across August and September.
As detailed in Section 3.6, effluent fast CBOD pools estimated based on DMR BOD5 sampling and a ratio
of 2:1 for BOD5:CBODu!tmate. When DMR-reported concentrations for any given parameter were listed as
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Crooked Creek QUAL2K Model
October 15, 2019
below detection limit, the concentration was assumed to be half of the detection limit for the purposes of
calculating average effluent concentrations.
Table 10. Point source flow and water quality inputs (calibration period)
Parameter Hemby Acres Crooked Creek Grassy Branch
WWTP #2 WWTP' WWTP
Discharge Information
NPDES Permit ID
NC0035041
NC0069841
NC0085812
Permit Class
Minor
Major
Minor
NPDES Permitted Flow (MGD)
0.3
1.9
0.05
Model Inputs based on DMR data (August 2016 Averages)
Location (km), distance from outlet
32.48
27.81
10.82
Inflow (m3/s), [MGD]
0.0039 [0.09]
0.0364 [0.83]
0.0018 [0.04]
Water Temperature (°F)
78.1
79.9
78.3
Dissolved Oxygen (mg/L)
6.5
7.6
7.7
Slow CBOD (mg/L)
0
0
0
Fast CBOD2 (mg/L)
8.36
2.38
3.60
Inorganic Suspended Solids (mg/L)
1.25
1.56
2.46
Ammonia Nitrogen (pgN/L)
50
940
640
pH
7.5
7.3
7.3
Model Inputs based on summer grab sampling data (Trips 1 and 2 Averages)
Corresponding Grab Sample ID
#2
#4
#12
Organic Nitrogen (pgN/L)3
565
1,100
825
Nitrate+ Nitrite Nitrogen (pgN/L)
38,000
28,450
39,000
Organic Phosphorus (pgP/L)4
800
2,000
1,150
Inorganic Phosphorus (pgP/L)
3,300
2,700
1,850
Specific Conductance (pmhos)6
641
628
837
Phytoplankton (ug/L)
No Data, assume 0
Alkalinity (mg/L)
86.05
73.4
98.6
'Measurements were observed at the entrance of the pipe. DO measurements at the end of the pipe suggest that water quality does
not change significantly through the pipe.
2Measured and reported BOD5 was converted to fast CBODultimate as described in the text with 1:2 ratio.
'Organic nitrogen was not measured directly, but calculated as the difference between measured TKN and NH3
`Organic phosphorus was not measured directly, but calculated as the difference between measured TP and POa
'Alkalinity was not measured at Hemby Acres, so it was approximated as the average the other two dischargers
'Conductance measured from Trip 3 (used for calibration and corroboration models)
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Crooked Creek QUAL2K Model
October 15, 2019
Table 11. Point source flow and water quality inputs (corroboration period)
Parameter
Hemby Acres Crooked Creek Grassy Branch
WWTP #2 WWTP1 WWTP
DMR Data (September 2016 Averages)
Model Inputs based on
Location (km), distance from outlet
32.48
27.81
10.82
Inflow (m3/s), [MGD]
0.0039 [0.09]
0.0381 [0.87]
0.0018 [0.04]
Water Temperature (°F)
75.6
75.6
76.3
Dissolved Oxygen (mg/L)
6.8
8.0
7.6
Slow CBOD (mg/L)
0
0
0
Fast CBOD2 (mg/L)
11.80
4.08
2.00
Inorganic Suspended Solids
(mg/L)
1.25
4.71
1.27
Ammonia Nitrogen (pgN/L)
50.00
57.06
255.56
pH
7.3
7.1
7.1
Model Inputs based on summer grab sampling data (Trip 3)
Corresponding Grab Sample ID
#2
#4
#12
Organic Nitrogen (pgN/L)3
1075
1875
100
Nitrate+ Nitrite Nitrogen (pgN/L)
25100
33900
53300
Organic Phosphorus (pgP/L)4
1600
1300
200
Inorganic Phosphorus (pgP/L)
4000
4800
4500
Specific Conductance (pmhos)
641
628
837
Phytoplankton (ug/L)
No Data, assume 0
Alkalinity (mg/L)
64.65
37.7
91.4
'Measurements were observed at the entrance of the pipe. DO measurements at the end of the pipe suggest that water quality does
not change significantly through the pipe.
2Measured and reported BOD5 was converted to fast CBODultimate as described in the text with 1:2 ratio.
'Organic nitrogen was not measured directly, but calculated as the difference between measured TKN and NH3
"Organic phosphorus was not measured directly, but calculated as the difference between measured TP and PO4
5Alkalinity was not measured at Hemby Acres, so it was approximated as the average the other two dischargers
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Crooked Creek QUAL2K Model October 15, 2019
3.7.3 Tributary Flows and Water Quality
Model inputs for flow and water quality for the South Fork Crooked Creek and Grassy Branch tributaries
contributing to the Crooked Creek mainstem were developed based on a combination of observed data,
water balance calculations, and best professional judgement. Streamflow was estimated at several points
along Crooked Creek based on cross-section surveys paired with velocity measurements. By combining
the observed streamflow information with the reported point source discharge data, the relative
contributions of each modeled tributary can be estimated using a water balance assuming no other losses
due to evaporation and groundwater seepage. For tributary inflows, CBOD is modeled as slow
CBODuitimate and estimated the same way as the headwaters.
Table 12. Tributary flow and water quality inputs (calibration model)
Parameter
SFCC
Grassy
Branch
Data Source Information
Inflow, ft3/s (m3/s)
1.06
(0.03)
0.32
(0.009)
Estimated by water balance as the difference between
instream flow estimates which are not accounted for by point
source flows.
Water Temperature, (°F)
81.86
74.48
Water temperature is based on probe sampling conducted
on Trip 1 for SFCC and Grassy Branch. Note that Grassy
Branch is cooler because it is largely groundwater -fed.
Conductivity (pmhos)
252
252
No available data, assumed same as headwaters
ISS (mg/L)
0
0
No available data, assumed zero
Dissolved Oxygen
(mg/L)
2.47
2.67
DO estimates are based on probe sampling conducted on
Trip 1 for SFCC and Grassy Branch.
Alkalinity (mg/I)
100
100
No available data, assume model default
Phytoplankton (ug/I)
0
0
No available data, assumed zero
pH
7.35
6.23
pH estimates are based on probe sampling conducted on
Trip 1 for SFCC and Grassy Branch.
Slow CBOD (mg/L)
4.52
23.73
Average measured CBOD5 from Trips 1 and 2 was used to
approximate slow CBOD as described in the text. Observed
CBOD5 along Grassy Branch was noticeably high.
Fast CBOD (mg/L)
0
0
Ammonia N (pgN/L)
478
25
NH3 and NOX data are averages of observed data from
Trips 1 and 2 at WQ Site #9 (SFCC) and WQ Site #13
(Grassy Branch). Organic N was calculated as the
difference between observed TKN and NH3 data.
Organic N (pgN/L)
1,073
435
Nitrate+Nitrite N (pgN/L)
2,865
1,600
Organic P (pgP/L)
380
98
Organic P was calculated as the difference between
observed TP and PO4 during Trips 1 and 2 for SFCC (WQ
Site #9). Model inputs for Grassy Branch are from Trip 3
only because of a lab issue with P-species data from Trips 1
and 2 (WQ Site #13).
Inorganic P (pgP/L)
245
72
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Crooked Creek QUAL2K Model
October 15, 2019
Table 13. Tributary flow and water quality inputs (corroboration model)
Parameter
SFCC
Grassy
Branch
Data Source Information
Inflow, ft3/s (m3/s)
1.06
(0.03)
0.32
(0.009)
Estimated to be the same as during the calibration period.
Water Temperature (°F)
71.6
76.8
Water temperature is based on probe sampling conducted
on Trip 3 for SFCC and Grassy Branch.
Conductivity (pmhos)
102
263
Estimates are based on probe sampling conducted
for SFCC and Grassy Branch.
on Trip 3
ISS (mg/L)
0
0
No available data, assumed zero
Dissolved Oxygen
(mg/L)
2.47
2.67
DO estimates are based on probe sampling conducted on
Trip 1 for SFCC and Grassy Branch.
Alkalinity (mg/I)
100
100
No available data, assume model default
Phytoplankton (ug/I)
0
0
No available data, assumed zero
pH
5.95
7.51
pH estimates are based on probe sampling conducted on
Trip 3 for SFCC and Grassy Branch.
Slow CBOD (mg/L)
9.49
4.52
Measured CBOD5 from Trip 3 was used to approximate slow
CBOD as described in the text.
Fast CBOD (mg/L)
0
0
Ammonia N (pgN/L)
110
25
NH3 and NOX data are observed data from Trip 3 at WQ
Site #9 (SFCC) and WQ Site #13 (Grassy Branch). Organic
N was calculated as the difference between observed TKN
and NH3 data.
Organic N (pgN/L)
630
705
Nitrate+Nitrite N (pgN/L)
5
610
Organic P (pgP/L)
98
98
Organic P was calculated as the difference between
observed TP and PO4 from Trip 3.
Inorganic P (pgP/L)
92
72
3.8 REACH WATER QUALITY PARAMETERS
Modeled water quality parameters that can vary by reach include sediment oxygen demand (SOD) rates;
prescribed nutrient flux rates from sediment; channel reaeration rates; nutrient hydrolysis and settling
rates; phytoplankton growth, respiration, and death rates; and bottom algae coverage, growth, respiration,
and death rates. If not otherwise specified for a given reach, water quality parameterization was tabulated
using default values and suggested ranges of model inputs.
Model inputs related to reaeration, SOD, bottom algae, and phytoplankton can have large influence on
average DO and the diurnal range of DO. The DO sondes were used to identify the diurnal variation in
DO observed at specific points along Crooked Creek. DO sondes were used to identify the relative impact
of bottom algae (surrogate for macrophyte growth) along Crooked Creek based on observed diel DO
variation. During the first field sampling trip, DO sondes were placed upstream and downstream of the
Crooked Creek #2 discharge and near the crossing of Highway 601. During the second trip, DO sondes
Nil TETRA TECH
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Crooked Creek QUAL2K Model October 15, 2019
were placed at the Highway 601 crossing, at the Brief Road crossing, and at the State Road 1601
crossing. All six sondes experienced a diurnal DO variation between 1.18 and 2.53 mg/I. Diurnal DO
fluctuations are due to photosynthetic processes of biota which are light and temperature dependent. The
relatively low diurnal fluctuations in DO observed along Crooked Creek suggest that algae play a
relatively minor role in the system. Bed coverage of algae was parameterized for the calibration and
corroboration models as a forcing function, such that inputs varied between the two models based on
observed algal conditions and diel DO variation between the two simulation periods (Table 14). The
magnitude of daily minimum and maximum DO are controlled by the streambed coverage of bottom algae
as an aggregate term for all macrophyte growth exerting photosynthetic processes within the water
column. For the calibration model, reach 1 was parameterized with 25% bottom algae coverage, while all
other reaches were set to 50% coverage. Between the field sampling work in August and September,
there was additional algal growth observed, such that reach parameterization for bottom algae coverage
was increased for the corroboration model run. For this model run, reach 1 was parameterized with 50%
bottom algae coverage, while reaches 2, 3, 4, and 6 were set to 75% coverage. Reach 5 was increased
further to 95% bottom algae coverage due to the presence of increased algae and multiple DO
observation points measured at supersaturation in this reach.
Table 14. Model inputs for bottom algae coverage
Reach
Bottom Algae
Coverage
Corroboration
50%
Calibration
1
25%
2
50%
75%
3
50%
75%
4
50%
75%
5
50%
95%
6
50%
75%
Average instream DO concentrations are sensitive to SOD, which is the consumption of DO at the soil -
water interface. SOD is simulated in QUAL2K as both a rate of oxygen consumption as well as a percent
coverage of the channel bottom. SOD was not measured along Crooked Creek, so the model was
initialized based on the observed range measured in another North Carolina Piedmont -area stream: Rich
Fork Creek near High Point (Tetra Tech, 2009b). SOD estimates associated with Rich Fork Creek were
also used in the modeling effort associated with Twelve Mile Creek in Union County (Tetra Tech, 2009c).
SOD was measured with in situ chambers at a number of locations along Rich Fork Creek, both upstream
and downstream of an existing WWTP. The observed range of SOD along Rich Fork Creek was 0.067 —
0.213 g/ft2/d (0.721 — 2.293 g/m2/d), with the lowest values generally being recorded upstream of the
WWTP discharge. The Crooked Creek model was initialized with instream SOD coverage set to 100% at
a rate of 0.067 g/ft2/d (0.721 g/m2/d) for all reaches. This SOD rate was adjusted during calibration adjust
simulated DO concentrations to mimic longitudinal profiles. Note that the North Carolina Division of Water
Quality has measured SOD across the state periodically and the observed range for the Upper Cape Fear
River watershed was approximately 0.4 — 2.5 g/m2/d, which provided a constraining range during model
calibration.
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Crooked Creek QUAL2K Model October 15, 2019
Channel reaeration is the natural input of oxygen to a waterbody through the transfer of atmospheric
oxygen into the water column at the air -water interface. Rates of reaeration are typically higher for
shallow, fast moving streams, and lower for slow, deep streams. Although reaeration was not measured
directly in Crooked Creek, anecdotal evidence and observed reaeration from the Rich Fork Creek project
was used to confine and inform the Crooked Creek model setup. Rich Fork Creek had observed
reaeration rates of 0.32/d in low -velocity pooled areas of the stream, and 1.85 /d in free -flowing sections
of the stream with observed flows on the order of 27 cfs. The Tsivoglou-Neal reaeration formula was
identified as likely appropriate for Crooked Creek as it computes reaeration based on mean water velocity
and channel slope and is appropriate for low flow streams where flow ranges 1 — 15 cfs, and the average
field -estimated flow along Crooked Creek is about 2.5 cfs (Tsivoglou and Neal, 1976).
For model setup, initial assumptions for reach parameters related to nutrient processing, settling rates,
and decay were held at model default values and were adjusted during calibration as -needed.
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Crooked Creek QUAL2K Model
October 15, 2019
4.0 MODEL CALIBRATION AND CORROBORATION
Model calibration involves comparing how well model simulations match observed data. Model calibration
is designed to ensure that the model is adequately and appropriately representing the system in order to
answer the study questions. The model must be able to provide credible representations of the movement
of water, and the DO and BOD interactions within the stream representing steady state conditions.
Corroboration is applied using a different time period to confirm that model calibration is robust, provide
additional evaluation of model performance, and to guard against over -fitting to the calibration data.
The QUAL2K model for Crooked Creek will be calibrated to an average of data collected during the first
two sampling trips in August 2016. The corroboration period for the model will be focused on the middle
of September during the third and final summer sampling trip. Physical properties related to stream flow
and atmospheric inputs may be subject to change during the model corroboration period. The model will
be set up for these conditions using available data and calibrated to reproduce observed DO.
4.1 HYDROLOGY CALIBRATION
Reach hydraulics were calibrated in order to approximate observed and estimated conditions of flow,
depth, and velocity along Crooked Creek during the summer sampling trips. Manning's n was the key
calibration parameter that was adjusted to capture site -estimated flow dynamics since the measured
cross -sections were considered reasonable enough to approximate channel shapes. The calibrated reach
hydraulic inputs were to alter Manning's n to 0.3 for all reaches except Reach 4 (sluggish, pooled beaver
dam reach) which had a roughness coefficient of 0.6.
Travel time for the full extent of Crooked Creek was estimated by the model to be just over six days, and
model results of flow along the mainstem compared to observations may be seen in Figure 13. Along the
entire reach, simulated stream velocity ranged from 0.07 — 0.16 ft/s (0.02 — 0.05 m/s) (observed range
was 0.13 — 0.39 ft/s [0.04 — 0.12 m/s]), and simulated water depth ranged from 0.89 — 2.13 ft (0.27 — 0.65
m) (observed range was 0.49 — 2.10 ft [0.15 — 0.64 m]). Upstream and downstream streamflow along
Crooked Creek were simulated to be 1.06 and 4.24 cfs (0.03 and 0.12 cms) respectively.
111
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Crooked Creek QUAL2K Model
October 15, 2019
Hemby
WWTP
i
•
SFCC
confluence
CC#2
WWTP
•
•
HWY
601
•
4.5
4.0
3.5
3.0
Grassy WWTP, ;n
• Grassy Branch confluence 2.5 17,
2.0 o
LL.
1.5
1.0
0.5
0.0
20 15 10 5 0
Distance from outlet (miles)
• Field -Estimated Flow -Simulated Flow. Calibration Model
Figure 13. Simulated and site -estimated flows for Crooked Creek model extent (calibration)
4.2 WATER TEMPERATURE CALIBRATION
In general, the parameters which control water temperature are channel geometry, meteorological inputs,
stream shading, atmospheric heat models, and sediment heat parameters. Initialized parameterization
related to sediment thermal properties, stream shading, and heat models captured the observed water
temperature data reasonably well.
The simulated minimum, maximum, and average water temperature are shown in Figure 14 in
comparison with observed water temperature from the YPDRBA in August, longitudinal sampling along
the entire extent from sampling trips 1 and 2, and the range of temperatures observed at the sonde
locations from trips 1 and 2 as well (Figure 14). Moving from upstream to downstream, it is possible to
see that the majority of morning sampling (open circles) fall below the mean simulated water temperature
line, while the majority of afternoon sampling (closed circles) fall above the mean simulated water
temperature line. The spread of observed temperature data is largely captured by the diel range
simulated by the model as seen in the dashed lines below. In general the sonde data which represents
the observed range of data over several days at a given point (red vertical lines) are skewed low relative
to the longitudinal sampling (points) due to the fact that these sondes were submerged along the stream
bed which is anticipated to be cooler and more well -insulated to daily fluctuations than the water closer to
the surface.
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Crooked Creek QUAL2K Model October 15, 2019
I-1--I-----2— -I 3 1 4 1
•
i
I i ft.-1—J
Beaver HWY
Dams 601
Hemby CC#2 SFCC
WWTP WWTP confluence
20
Simulated Mean Temp
• YPDRBA Pant Data
O Obs long data (AM): trip 2
15 10
Distance from outlet (miles)
- - - - Simulated Min/Max Temp
O Obs Long Data (AM) Trip 1
• Obs long data (PM) trip 2
i
Grassy WWTP.
Grassy Branch confluence
s
Observed Sonde Data
• Obs Long Data (PM) Trip 1
90
70
60 a
d
50
40 E
30
o.
20
10
0
0
Figure 14. Simulated and observed water temperature along Crooked Creek (calibration)
4.3 WATER QUALITY CALIBRATION
The primary focus of water quality calibration was related to DO concentrations along Crooked Creek.
The key parameters which control average DO concentrations were identified to be SOD rate and
channel reaeration. The magnitude of diel DO variation is controlled by the streambed coverage of bottom
algae. Reaeration rates were simulated using the Tsivoglou-Neal model, and were estimated as 0.4 — 3.3
/d, with an average reaeration rate of 2.3 /d. The lowest reaeration rate occurred in the model along the
sluggish beaver -dammed Reach 4.
SOD rates were used as a calibration parameter, constrained by the range of observed SOD in the Upper
Cape Fear River basin from NC DWQ of 0.4 — 2.5 g/m2/d. Calibrated SOD rates ranged from 1.0 — 2.2
g/m2/d in the calibrated model, such that reach 1 was assigned 1.0 g/m2/d, while all other reaches were
assigned 2.2 g/m2/d to best approximate average instream DO conditions.
The simulated minimum, maximum, and average DO are shown in Figure 15 in comparison with observed
DO from the YPDRBA in August, longitudinal sampling along the entire extent from sampling trips 1 and
2, and the range of DO observed at the sonde locations from trips 1 and 2 as well. Annotations on the plot
below reveal key features along the mainstem such as point source and tributary inflows which may have
significant impacts on in -stream DO concentration. From upstream to downstream, it is possible to the
see the increase in DO due to the Hemby WWTP discharge, then a decline in DO downstream due to the
BOD decay from the effluent. The DO spike at the end of Reach 2 is due to the CC#2 outfall, and the DO
decline downstream is smaller downstream relative to downstream of Hemby because of the difference in
BOD loading to the stream. The SFCC tributary has low DO, and the DO along the sluggish and dammed
Reach 4 causes a precipitous drop in oxygen along that reach. The recovery in DO downstream of the
beaver dams and Highway 601 is due to the combined impacts of higher slopes, less in -stream BOD, and
the impact of the Grassy Branch WWTP is relatively small as Crooked Creek flows down to Rocky River.
The range of daily DO concentrations observed along Crooked Creek is captured reasonably well by the
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Crooked Creek QUAL2K Model
October 15, 2019
calibration model, with DO at the downstream end estimated to be about 6 mg/I at the Rocky River
confluence.
1-1--1-----2 I 3 I 4 I 5 I 6
Hemby CC#2 • SFCC HWY Grassy WWTP.
WWTP WWTP confluence 601 Grassy Branch confluence
_ ----
Q� co • • ow
. • se 69
+
ss
20
• YPDRBA Pant Data
o Obs tong Data (AM) Trip 2
- - - - Simulated Min/Max
D0 Saturation
O
15
Beaver
Dams
1
12
10
---- _•-- _ • 8 E
---- r'o-• • ••
•
.-or""; 0 0 • •• • • m
•
6
I • •• e o • • G
10
Distance from outlet (miles)
O Obs Long Data (AM) Trip 1
• Obs Long Data (PM) Trip 2
Observed Sonde Data
5
• Obg Long Data (PM) Trip 1
Simulated Mean
---- We : 5.0 mg/I
Figure 15. Simulated and observed DO along Crooked Creek (calibration)
4.4 MODEL CORROBORATION RESULTS
0
0
Model corroboration is conducted in order to verify the simulation and parameterization achieved during
model calibration reasonably approximates stream conditions during different stream conditions. Although
overall stream hydrology is held constant between the calibration and corroboration periods, significant
model changes were made for the corroboration regarding the following parameters: model run date,
meteorological inputs (air temperature, dew point temperature, and cloud coverage), tributary and
headwater chemistry, and point source flow and water chemistry. All other model parameters related to
channel geometry, flows, shading, SOD, and reaeration were held constant for the corroboration model
run.
4.4.1 Water Temperature Corroboration
In general, the water temperature was reasonably well simulated during the model corroboration period.
The downstream water temperature from near the end of Reach 5 and into Reach 6 was observed much
warmer than the model predicted, but the water temperatures are reasonably well approximated for
Reaches 1 through most of Reach 5.
The simulated minimum, maximum, and average water temperature are shown in Figure 16 in
comparison with observed water temperature from the YPDRBA in September, longitudinal sampling
along the entire extent from sampling trip 3, and the range of temperatures observed at the sonde
locations from trips 3 as well.
STETRA TECH
29

Crooked Creek QUAL2K Model October 15, 2019
I —1-- I --------2----- I 3 I 4 I 5
6
I
90
Beaver
Dams
Hemby CC#2 SFCC
WWTP WWTP confluence
1
HWY
601
20 15 10
Distance from outlet (miles)
Simulated Mean Temp - - - - Simulated Min/Max Temp
• YPDRBA Point Data 0 Obs Long data (AM)
Grassy WWTP,
Grassy Branch confluence
5
- Observed Sonde Data
• Obs long data (PM)
0
Figure 16. Simulated and observed water temperature along Crooked Creek (corroboration)
80
70
60 at
50
40 E
30
20
10
0
4.4.2 Water Quality Corroboration
The simulated minimum, maximum, and average DO during the corroboration period are shown in Figure
17 to reasonably approximate observed DO relative to DO from the YPDRBA in September, longitudinal
sampling from sampling trip 3, and the range of DO observed at the sonde locations from trip 3.
I-1—I-------2 I 3 I 4 I 5 I— ----- —6 —— -- I
Hemby CC#2 SFCC HWY Grassy WWTP,
WWTP WWTP confluence 601 Grassy Branch confluence
t
•.
•
1`.
•
20
•
1
--r
• YPDRBA Point Data
Simulated Mean
WQS: 5.0 mg/1
B r O•
•• r
(
•
` O
Beaver
Dams
_�
•
• _ 0
r O
r
15 10
Distance from outlet (miles)
O Obs Long Data (AM)
- - - - Simulated Min/Max
---- DO Saturation
• Obs Long Data (PM)
Observed Sonde Data
5
Figure 17. Simulated and observed DO along Crooked Creek (corroboration)
12
10
8
4
0
0
Dissolved Oxygen (rng/I)
® TETRA TECH
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Crooked Creek QUAL2K Model
October 15, 2019
5.0 MODEL SENSITIVITY
A series of sensitivity analyses were conducted in order to provide an increased understanding of
uncertainty associated with key model parameters. The relative impact of several model parameters were
gauged in order to test the model sensitivity to changes in: bottom algae coverage, SOD rate, Manning's
n, percent shade, headwater flow rate, and the selected reaeration model (Table 15). Each parameter
was tweaked by +25% and -25% with the exception of the reaeration model, for which other formulas
were selected in each successive run.
Table 15. Crooked Creek QUAL2K model sensitivity test runs
Model Run
Calibration
Details
Representative summer conditions for setting up sensitivity analyses
Sensitivity 1
Bottom Algae +/- 25%
Sensitivity 2
SOD Rate +/- 25%
Sensitivity 3
Manning's n +/- 25%
Sensitivity 4
Shade +/- 25%
Sensitivity 5
Headwater Flow +/- 25%
Sensitivity 6
Reaeration Models: O'Connor -Dobbins, Churchill, Owens -Gibbs, Thackston-Dawson
The results from the six sensitivity tests reveal the relative impact each of the tested parameters has on
the simulated mean dissolved oxygen concentrations along the extent of the Crooked Creek QUAL2K
model. Sensitivity tests 1 and 2 involve a 25% change in bottom algae coverage and SOD rate
respectively. These scenarios reveal that the model is more sensitive to SOD rate than bottom algae
coverage by impacting mean DO on the order of 16% and 5% respectively (Figure 18). Sensitivity tests 3,
4, and 5 involve a 25% change in Manning's n, shade, and headwater flow respectively. These scenarios
reveal the impact to mean DO to be relatively small, on the order of 4-5% for these three tests (Figure
19). Sensitivity test 6 involved testing model sensitivity to reaeration model selection (Figure 20). Of the
four reaeration models selected, the impact on mean DO was as follows, from greatest to least: Owens -
Gibbs (35%), O'Connor -Dobbins (31%), Churchill (19%), and Thackston-Dawson (11%). Both Owens -
Gibbs and O'Connor -Dobbins reaeration models predicted a positive impact on mean DO, while Churchill
and Thackston-Dawson reaeration models predicted a negative impact on mean DO relative to the
calibration model which used the reaeration model of Tsivoglou-Neal. In general, both Churchill and
O'Connor -Dobbins models are only appropriate for streams with depths greater than 1.6 feet (0.5 meters)
which is greater than the observed depths in Crooked Creek. The Owens -Gibbs formula overestimates
reaeration significantly (similar to O'Connor -Dobbins), likely because Owens -Gibbs assumes high
reaeration with low depth, even when velocities are small, but as seen visually along Crooked Creek, low
velocities can lead to pooling and stagnation with limited reaeration occurring. The Thackston-Dawson
formula responds similarly to the selected model of Tsivoglou-Neal, however it consistently underpredicts
instream DO by about 0.5 mg/I. The Tsivoglou-Neal formula remains the best fit to the observed data
during both the calibration and corroboration periods (Thackston and Dawson, 2001). The overall results
are summarized in Table 16.
® TETRA TECH
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Crooked Creek QUAL2K Model
October 15, 2019
111
Hemby
WWTP
•
20
2 I 3 I 4-1 5
CC#2
Tap
•
• `
•
•
SFCC
confluence Beaver
Dams
HWY
601
fi --
i
Grassy W WTP.
Grassy Branch confluence 7
6
-- 5
4
6 18
15 10
Distance from outlet (miles)
5 0
Calibrated Model - - - - Sensitivity 1: Bottom Algae - - - - Sensitivity 2: SOD Rate
3
2
1
0
Mean Dissolved Oxygen (mg/I)
Figure 18. Sensitivity test results (runs 1 and 2): bottom algae coverage and SOD rate
I11 2 1
Hemby CC#2
WWT♦ P rP
AtN...................
:� ���.�..
` ;;rrs•nrfS
20
3 —1-4-1
SFCC
confluence Beaver
1 Darns
15
Calibrated Model
- - - - Sensitivity 4: Shade
HWY
601
5 1 6 18
Grassy WWTP.
Grassy Branch confluence
10
4
5 0
Distance from outlet (miles)
- - - - Sensitivity 3: Manning's n
Sensitivity 5: Headwater Flow
0
Figure 19. Sensitivity test results (runs 3, 4, and 5): Manning's n, shade, and headwater flow
TETRA TECH
32

Crooked Creek QUAL2K Model
October 15, 2019
1 1 1 2 I 3 I-4—I 5
Hemby CC#2 SFCC HWY GrassyWWTP.
WWTP rTP confluence ��^�
\ _ Beaver gp}
r�`` ♦� _ : - -� assx
Dams
•
\
\
20 15 10
Distance from outlet (miles)
Calibrated Model (Tsivoglou-Neal) - - - - Sensitivity 6a: O'Connor Dobbins
- - - - Sensitivity 6b: Churchill - - - - Sensitivity 6c: Owens Gibbs
- - - - Sensitivity 6d: Thackson-Dawson
5
Figure 20. Sensitivity test results (run 6): reaeration model selection
Table 16. Crooked Creek QUAL2K model sensitivity test run results
0
8
7 -
E
6 E
ar
5
O
4 -0
3 2
CA
2 3
1 a,
2
0
Model Run
Details
Average Absolute
Difference in Mean DO
(mg/I)
Average Absolute
Relative Percent
Difference on Mean DO
Calibration
Baseline
N/A
N/A
Sensitivity 1
Bottom Algae +/- 25%
0.2
5%
Sensitivity 2
SOD Rate +/- 25%
0.8
16%
Sensitivity 3
Manning's n +/- 25%
0.2
4%
Sensitivity 4
Shade +/- 25%
0.2
5%
Sensitivity 5
Headwater Flow +/- 25%
0.2
4%
Sensitivity 6
Reaeration Model Variations
1.1
24%
The selection of the reaeration formula can result in the largest single absolute error, however there is
reasonably good knowledge that the selected model of Tsivoglou-Neal is the most appropriate choice.
The next parameter which the model is quite sensitive to is SOD, which had an average absolute relative
percent difference on mean DO of 16%. Since neither reaeration nor SOD were measured directly along
Crooked Creek, the interaction between those two parameters are likely the greatest source of
uncertainty within the model environment, although estimates for both were established based on
reasonable approximations.
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Crooked Creek QUAL2K Model
October 15, 2019
Beven, K.J., Gilman, K., and Newson, M. 1979. Flow and flow routing in upland channel networks. Hydrol.
Sci. Bull. 24:43-69.
Brown, L. C. and T. O. Barnwell, Jr., 1987. The enhanced stream water quality models QUAL2E and
QUAL2E-UNCAS: Documentation and User Manual. Tufts University and US EPA, Athens, Georgia.
Chapra, S.C., G.J. Pelletier, H. Tao. 2012. QUAL2K: A Modeling Framework for Simulating River and
Stream Water Quality, Version 2.12: Documentation and User's Manual. Civil and Environmental
Engineering Dept., Tufts University, Medford, MA.
Chow, V.T. 1959. Open -channel hydraulics: New York, McGraw-Hill, 680 p.
EPA. 1985. Rates, Constants, and Kinetics Formulations in Surface Water Quality Modeling (Second
Edition). EPA/600/3-85/040.
Leo, WM, RV Thomann, TW Gallaher. 1984. Before and after case studies: comparisons of water quality
following municipal treatment plant improvements. EPA 430/9-007. Office of Water, Program Operations,
U.S. Environmental Protection Agency, Washington, DC.
National Service Center for Environmental Publications (NCASI). 1985. Computer program
documentation for the enhanced stream water quality model QUAL2E. EPA/600/3-85.
North Carolina Department of Natural Resources (NC DENR). 2016. 2016 303(d) Listing Methodology.
Tetra Tech. 2009a. Loading Simulation Program in C++ (LSPC) Version 3.1 User's Manual. Fairfax, VA.
Tetra Tech. 2009b. Hydrology and Hydraulic Modeling Report for Rich Fork Creek, NC. Prepared for City
of High Point and Hazen & Sawyer. Prepared by Tetra Tech.
Tetra Tech. 2012a. Goose and Crooked Creek Local Watershed Plan (LWP). Prepared for North Carolina
Ecosystem Enhancement Program (NCEEP). Prepared by Tetra Tech.
Tetra Tech. 2012b. Goose Creek and Crooked Creek Watersheds: Model Development and Calibration
(LSPC Model). Prepared for Centralina Council of Governments and North Carolina Division of Water
Quality. Prepared by Tetra Tech.
Tetra Tech. 2012c. QUAL2 Model Update for Twelve Mile Creek below the Union County WWTP.
Prepared for Union County Public Works Department and Hazen & Sawyer. Prepared by Tetra Tech.
Thackston, E.L., and J.W. Dawson. 2001. Recalibration of a reaeration equation. Journal of
Environmental Engineering, ASCE, 127(4), 317-321.
Tsivoglou, E. C., L.A. Neal. 1976. Tracer Measurement of Reaeration. III. Predicting the Reaeration
Capacity of Inland Streams. Journal of the Water Pollution Control Federation, 48(12):2669-2689.
United States Army Corps of Engineers (USACE). 2016. HEC-RAS River Analysis System User's
Manual. Davis, California.
Weaver, J.C., and J.M. Fine. 2003. Low -Flow Characteristics and Profiles for the Rocky River in the
Yadkin -Pee Dee River Basin, North Carolina, through 2002. USGS Water -Resources Investigations
Report 03-4147.
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Crooked Creek QUAL2K Model
October 15, 2019
APPENDIX A: PERMITTED POINT SOURCE DATA
Included here are the treated effluent flow and water quality data associated with the permitted point
sources in the Crooked Creek watershed for August and September 2016 (Table A-1, Table A-2, and
Table A-3). Note that parameters such as chemical oxygen demand (COD), TN, TP, and hardness were
measured only once per month at some sites. Also reported by Carolina Water Services, Inc. are
instream water quality conditions immediately upstream and downstream of the Hemby Acres WWTP
which were used for headwater condition parameterization and instream calibration (Table A-4).
Table A-1. DMR data from August and September 2016: Crooked Creek #2 WWTP (NC0069841)
Date
8/1/16
Flow
(MGD)
0.71
Temp
(°F)
80.4
pH
7.5
BOD5
(mg/I)
<2
NH3
(mg/I)
<.1
TSS
(mgll)
<2.5
DO
(mg/I)
7.8
COD
(mg/I)
TN
(mg/I)
TP
(mg/I)
Hardness
(mg/I)
Alkalinity
(mg/I)
8/2/16
0.86
78.8
7.3
<2
0.91
<2.5
7.8
8/3/16
0.85
78.8
7.4
<2
0.92
<2.5
7.6
88
8/4/16
0.79
78.8
7.4
<2
1.0
<2.5
7.7
8/5/16
0.80
77.4
7.3
<2
0.87
<2.6
5.5
8/6/16
0.92
8/7/16
0.81
8/8/16
0.89
79.7
7.3
<2
3.3
<2.5
7.6
8/9/16
0.95
79.3
7.3
<2
4.7
<2.5
7.6
8/10/16
0.91
80.2
7.2
<2
3.5
<2.6
7.4
33
6.4
3.3
74
91
8/11/16
1.11
80.2
7.4
2.2
7.6
8/12/16
0.87
82.4
7.2
6.8
8/13/16
0.26
8/14/16
0.75
8/15/16
0.79
82.0
7.5
2.9
<.1
2.5
7.7
8/16/16
0.82
81.5
7.6
<2
<.1
<2.5
7.9
8/17/16
0.80
81.1
7.5
<2
<.1
<2.5
8.0
85
8/18/16
0.85
80.8
7.3
7.8
8/19/16
0.95
80.6
7.0
7.4
8/20/16
0.89
8/21/16
0.84
8/22/16
0.80
80.6
7.3
<2
<.1
<2.5
7.9
8/23/16
0.82
78.8
7.3
<2
<.1
<2.5
7.9
8/24/16
0.76
77.9
7.3
<2
<.1
<2.5
8.0
65
8/25/16
0.77
77.5
7.3
<2
<.1
<2.5
8.1
8/26/16
0.81
80.6
6.7
<2.5
7.2
TETRA TECH
35

Crooked Creek QUAL2K Model
October 15, 2019
Date
8/27/16
Flow
(MGD)
0.81
Temp
(°F)
p H
BOD5
(mg/I)
NH3
(mg/I)
TSS
(mg/I)
DO
(mg/I)
COD
(mg/I)
TN
(mg/I)
TP
(mg/I)
Hardness
(mg/I)
Alkalinity
(mg/I)
8/28/16
0.94
8/29/16
0.90
79.0
7.1
2.5
<.1
4.3
80
8/30/16
0.81
78.8
7.1
<2
<.1
2.7
8.0
8/31/16
0.77
80.1
7.1
<2
<.1
<2.6
7.9
38
9/1/16
0.78
78.4
7.2
<2
<.1
<2.5
8.0
9/2/16
0.86
80.6
6.8
7.8
9/3/16
1.85
9/4/16
0.91
9/5/16
0.75
77.0
6.9
7.3
9/6/16
0.79
76.1
7.3
<2
<.1
<2.5
8.2
9/7/16
0.89
76.6
7.2
<2
<.1
3.9
8.0
9/8/16
0.81
77.4
7.2
2.7
<.1
6.5
7.9
27
30.35
4.8
150
52
9/9/16
0.78
77.7
7.2
5.2
<.1
10.4
8.0
9/10/16
0.78
9/11/16
0.78
9/12/16
0.80
77.7
7.1
6.8
0.11
19
8.0
9/13/16
0.89
76.8
7.1
2.4
<.1
8.4
8.1
9/14/16
0.79
77.5
7.0
2.0
<.1
7.6
7.9
34
9/15/16
0.79
77.5
7.0
8.0
9/16/16
0.78
78.8
6.4
2.6
<.1
6.6
7.9
9/17/16
0.76
9/18/16
0.80
9/19/16
0.81
78.6
6.4
<2
0.11
4.6
7.9
9/20/16
0.81
77.5
6.8
<2
<.1
3.0
8.0
9/21/16
0.82
75.4
7.2
<2
<.1
<2.6
8.2
27
9/22/16
0.88
75.2
7.2
<2
<.1
<2.6
8.3
9/23/16
1.07
75.9
6.4
7.9
9/24/16
0.89
9/25/16
0.86
9/26/16
0.96
76.6
7.4
<2
<.1
<2.6
8.2
9/27/16
0.89
75.9
7.6
8.3
9/28/16
0.95
76.8
7.3
3
<.1
<2.5
8.1
9/29/16
0.84
76.1
7.3
<2
<.1
<2.5
8.2
9/30/16
0.87
77.0
7.3
<2
<.1
<2.5
7.7
® TETRA TECH
36

Crooked Creek QUAL2K Model
October 15, 2019
Table A-2. DMR data from August and September 2016: Grassy Branch WWTP (NC0085812)
Date
8/1/16
Flow
(MGD)
0.01
Temp
(°F)
80.6
pH
7.1
BOD5
(mg/I)
NH3
(mg/I)
TSS
(mg/I)
DO
(mg/I)
COD
(mg/I)
Alkalinity
(mg/I)
8/2/16
0.05
75.2
7.3
2.4
0.32
2.7
7.75
30
59
8/3/16
0.03
75.2
7.1
8/4/16
0.03
77.0
7.5
8/5/16
0.02
77.0
7.5
8/6/16
0.32
8/7/16
0.02
8/8/16
0.07
77.0
7.8
8/9/16
0.11
77.0
7.8
8/10/16
0.04
78.8
7.8
8/11/16
0.03
78.8
7.2
<2
<.1
<2.6
7.95
87
8/12/16
0.03
78.8
7.7
8/13/16
0.18
8/14/16
0.02
8/15/16
0.02
82.4
7.7
8/16/16
0.02
80.6
7.6
<2
<.1
<2.6
7.04
96
8/17/16
0.02
80.6
7.2
8/18/16
0.02
82.4
7.3
8/19/16
0.04
78.8
7.5
8/20/16
0.03
8/21/16
0.02
8/22/16
0.02
78.8
7.2
8/23/16
0.02
77.0
7.0
<2
<.1
2.6
8.25
131
8/24/16
0.02
77.0
7.0
8/25/16
0.03
77.0
7.0
2
<.1
<2.5
7.3
120
8/26/16
0.03
78.8
7.3
8/27/16
0.02
8/28/16
0.03
8/29/16
0.03
78.8
7.0
® TETRA TECH
37

Crooked Creek QUAL2K Model
October 15, 2019
Date
Flow
(MGD)
Temp
(°F)
p H
BOD5
(mg/I)
NH3
(mg/I)
TSS
(mg/I)
DO
(mg/I)
COD
(mg/I)
Alkalinity
(mg/I)
8/30/16
0.03
77.0
6.9
3.4
3.3
5.6
7.88
8/31/16
0.03
77.0
6.6
9/1/16
0.04
78.8
6.9
<2
1.2
<2.5
7.52
59
9/2/16
0.03
78.8
7.1
9/3/16
0.10
9/4/16
0.03
9/5/16
0.02
77.0
7.4
9/6/16
0.04
78.8
7.4
9/7/16
0.03
77.0
6.8
<2
<.1
<2.6
7.98
74
9/8/16
0.04
75.2
6.7
<2
<.1
<2.5
7.38
67
9/9/16
0.03
77.0
6.9
9/10/16
0.03
9/11/16
0.02
9/12/16
0.02
78.8
7.0
9/13/16
0.03
77.0
6.3
<2
0.34
<2.5
7.19
19
38
9/14/16
0.03
77.0
6.6
<2
0.46
<2.5
7.16
62
9/15/16
0.04
75.2
6.8
9/16/16
0.04
77.0
7.3
9/17/16
0.03
9/18/16
0.02
9/19/16
0.02
77.0
7.7
9/20/16
0.04
75.2
7.6
9/21/16
0.03
73.4
7.1
<2
<.1
<2.5
8.35
164
9/22/16
0.04
73.4
7.1
<2
<.1
<2.6
7.49
176
9/23/16
0.05
75.2
7.0
9/24/16
0.05
9/25/16
0.02
9/26/16
0.04
77.0
7.7
9/27/16
0.05
73.4
6.7
9/28/16
0.10
77.5
7.8
® TETRA TECH
38

Crooked Creek QUAL2K Model
October 15, 2019
Date
9/29/16
9/30/16
Flow Temp BOD5 NH3 TSS DO
(MGD) (°F) pH (mg/I) (mg/I) (mg/I) (mg/I)
0.03
0.04
74.5
74.5
7.2
7.3
<2
<2
<.1
<.1
<2.5
<2.6
8.34
7.35
COD
(mg/I)
Alkalinity
(mg/I)
Table A-3. DMR data from August and September 2016: Hemby Acres WWTP (NC0035041)
Date
8/1/16
Flow
(MGD)
0.06
Temp
(°F)
80.4
p
7.0
BOD5
(mg/I)
NH3
(mg/I)
TSS
(mg/I)
DO
(mg/I)
6.72
8/2/16
0.08
8/3/16
0.09
79.0
7.3
2.3
<0.1
<2.5
7.38
8/4/16
0.09
8/5/16
0.08
8/6/16
0.13
8/7/16
0.08
8/8/16
0.07
8/9/16
0.10
8/10/16
0.10
79.5
8.0
8/11/16
0.10
78.6
7.6
4.6
<0.1
<2.5
6.73
8/12/16
0.09
8/13/16
0.10
8/14/16
0.10
8/15/16
0.06
8/16/16
0.09
76.8
6.8
5.84
8/17/16
0.09
8/18/16
0.08
80.2
7.7
<2
<0.1
<2.5
6.5
8/19/16
0.10
8/20/16
0.08
8/21/16
0.09
8/22/16
0.12
8/23/16
0.07
76.3
7.8
5.31
8/24/16
0.09
TETRA TECH
39

Crooked Creek QUAL2K Model
October 15, 2019
Date
Flow
(MGD)
Temp
(°F)
pH
BOD5
(mg/I)
NH3
(mg/I)
TSS
(mg/I)
DO
(mg/I)
8/25/16
0.07
75.6
7.3
<2
<0.1
<2.5
6.65
8/26/16
0.09
8/27/16
0.14
8/28/16
0.06
8/29/16
0.09
8/30/16
0.09
75.6
8.1
12
<0.1
<2.5
6.62
8/31/16
0.11
9/1/16
0.07
76.8
7.6
6.2
9/2/16
0.10
9/3/16
0.18
9/4/16
0.08
9/5/16
0.09
9/6/16
0.06
73.9
7.0
6.55
9/7/16
0.09
9/8/16
0.08
74.5
7.0
11
<0.1
<2.5
6.1
9/9/16
0.08
9/10/16
0.11
9/11/16
0.08
75.2
7.2
7.01
9/12/16
0.07
76.1
8.2
4.9
<0.1
<2.5
7.21
9/13/16
0.09
9/14/16
0.10
9/15/16
0.07
9/16/16
0.09
9/17/16
0.09
9/18/16
0.08
9/19/16
0.11
9/20/16
0.09
75.9
7.4
6.61
9/21/16
0.08
9/22/16
0.10
76.6
7.3
3.2
<0.1
<2.5
6.87
9/23/16
0.10
® TETRA TECH
40

Crooked Creek QUAL2K Model
October 15, 2019
Date
9/24/16
Flow
(MGD)
0.08
Temp
(°F)
pH
BOD5
(mg/I)
NH3
(mg/I)
TSS
(mg/I)
DO
(mg/I)
9/25/16
0.08
9/26/16
0.08
9/27/16
0.04
75.7
7.1
7.33
9/28/16
0.20
75.4
7.2
4.5
<0.1
<2.5
7.12
9/29/16
0.07
9/30/16
0.09
Table A-4. Instream DMR water quality data upstream and downstream of Hemby Acres WWTP, August
and September 2016
Date
8/3/16
Temperature
Upstream
74.8
(°F)
Downstream
75.4
Dissolved
Upstream
4.72
Oxygen (mg/I)
Downstream
5.03
8/11/16
73.8
75.2
4.57
5.03
8/18/16
76.3
76.8
4.43
4.96
8/25/16
73.6
75.0
3.33
4.01
8/30/16
73.4
75.0
4.32
4.91
9/8/16
71.6
73.2
4.01
4.59
9/12/16
71.8
73.2
3.63
4.97
9/22/16
73.9
76.3
3.65
4.01
9/28/16
68.2
69.8
4.22
4.98
® TETRA TECH
41

Crooked Creek QUAL2K Model
October 15, 2019
APPENDIX B: YPDRBA COALITION DATA
Water quality sampling conducted by the Yadkin Pee Dee River Basin Association (Coalition) during
August and September of 2016 may be relevant to use for model calibration and corroboration (Table B-1).
Table B-1. Coalition water quality data of -interest from August and September 2016
Parameter
Date*
Q8386000 (NFCC
at SR 1520)
Sampling Site
Q8386200 (NFCC
at SR1514)
Q8388000 (CC
at NC 218)
Water Temperature (°F)
8/9/2016
77.2
77.2
78.8
8/30/2016
76.6
76.8
76.5
9/13/2016
73.6
73.8
74.8
Dissolved Oxygen (mg/I)
8/9/2016
5.8
5.8
6.3
8/30/2016
5.7
5.8
6.4
9/13/2016
5.5
5.7
6.5
pH (s.u.)
8/9/2016
6.6
6.6
6.8
8/30/2016
6.6
6.6
6.9
9/13/2016
6.6
6.6
6.8
Conductivity (umhos/cm)
8/9/2016
263
289
162
8/30/2016
393
372
219
9/13/2016
248
229
179
Fecal Coliform (#/100m1)
8/9/2016
310
270
166
9/13/2016
300
250
162
Suspended Residue (mg/I)
8/9/2016
No Data
No Data
9.1
9/13/2016
No Data
No Data
20
Turbidity (NTU)
8/9/2016
16
20
16
9/13/2016
21
11
11
Ammonia as N (mg/I)
8/9/2016
No Data
No Data
0.1
9/13/2016
No Data
No Data
0.08
TKN as N (mg/I)
9/13/2016
No Data
No Data
0.8
NOX as N (mg/I)
8/9/2016
No Data
No Data
1.74
9/13/2016
No Data
No Data
2.49
TP (mg/I)
9/13/2016
No Data
No Data
0.76
*Note: some samples were taken 1 day before or after the reported date listed in this table
TETRA TECH
42

Crooked Creek QUAL2K Model
October 15, 2019
APPENDIX C: TETRA TECH 2016 SAMPLING DATA
C.1 STREAM HYDROLOGY MEASUREMENTS
Twenty cross -sections were measured during the 2016 summer sampling effort (Table C-1).
Table C-1. Measured reach properties, summer 2016
Distance from
Headwaters (km)
Sample Point
ID
8
Width (ft)
16
Velocity
(ft/s)
No Data
Maximum
Depth (ft)
1.1
Site -Estimated
Flow (cfs)
No Data
2.21
2.92
13
13
0.30
0.5
1.54
5.15
26
18
0.15
0.9
1.63
5.58
33
10
No Data
0.6
No Data
5.93
3
No Data
No Data
No Data
No Data
6.20
35
19
0.22
2.1
6.25
10.43
61
14
0.26
1.1
2.23
12.45
75
17
0.30
0.8
2.83
14.63
87
23
0.40
0.5
3.29
15.68
1
27
No Data
0.2
No Data
18.71
252
16.5
0.28
0.8
2.42
21.26
117
41.5
No Data
0.6
No Data
22.09
138
24
0.33
1.0
3.61
22.90
118
40.6
No Data
1.6
No Data
23.33
119
38
No Data
1.1
No Data
25.28
160
38.5
0.18
1.0
4.11
26.34
120
28.5
No Data
1.1
No Data
27.59
121
26.5
No Data
1.2
No Data
27.79
122
30
No Data
1.8
No Data
29.23
182
35
0.03
1.1
0.84
® TETRA TECH
43

Crooked Creek QUAL2K Model October 15, 2019
C.2 NUTRIENT SAMPLING
Grab samples were analyzed for water quality constituents along Crooked Creek during each sampling
effort. Fifteen samples were taken from the main stem, tributaries, and wastewater treatment plant
discharge sites during each sampling trip (Figure C-1). Water quality analyses were conducted by Pace
Analytical laboratory for the following parameters: 5-day biochemical oxygen demand (BOD5), 5-day
carbonaceous biochemical oxygen demand (CBOD5), ammonia (NH3), nitrate and nitrite (NO2+NO3),
phosphate (PO4), total Kjeldahl nitrogen (TKN), total nitrogen (TN), and total phosphorus (TP).
For a number of laboratory samples, the measured parameter was found to be below the level of
detection (LOD). The laboratory equipment did produce a numerical result below the LOD which has
been included and flagged as such. Although these results are below the LOD, the numbers seem
reasonable and may be relevant to include in modeling efforts with an increased level of uncertainty
associated with the exact concentrations. The results from all grab samples have been compiled by
sampling location, parameter, and trip (Table C-1, Table C-2, and Table C-3).
® TETRA TECH
Crooked Creek Watershed
Water Quality Grab Samples
•<D 10ES SWYLw NVA Core.. FlPS YNC
IYp(POdig.a gotho E wwancw
10
N 00.5 1 2
Av Kilometers
0 0.5 1 2
v Mde.
13
12
11 elf)
'Note: Site 9 was sampled further upstream
on South Fork Crooked Creek during the
second and third samping efforts
Legend
• Grab Sample Site
• WWTP Discharge
NHD HiRes Flowline
Watershed Boundary
Figure C-1. Water quality grab sample locations
® TETRA TECH
44

Crooked Creek QUAL2K Model
October 15, 2019
Table C-2. BOD/CBOD results (units mg/I)
ID
Location Note
1
1.40*
BOD5
2
1.20*
3
4.10
1
1.10*
CBOD5
2
1.20*
3
0.60*
1
US of Hemby discharge
2
Hemby WWTP discharge
0.70*
2.60
1.40*
0.70*
3.20
2.10
3
Indian Trail Fairview Rd
1.30*
2.00*
1.50*
0.80*
1.60*
1.60*
4
Crooked Creek #2 discharge
1.50*
0.70*
2.20
0.80*
0.50*
1.50*
5
US of CC#2 WWTP discharge
1.50*
1.30*
1.40*
1.00*
1.20*
1.90*
6
Old Farm Bridge crossing
1.60*
1.00*
0.90*
1.40*
0.60*
0.30*
7
DS of Rocky River Rd
1.50*
0.50*
1.20*
1.00*
0.95*
0.50*
8
Ridge Road crossing
1.50*
0.60*
3.50
0.80*
0.90*
0.90*
9
SF Crooked Creek
1.40*
2.00
0.80*
0.90*
1.20*
2.10
10
DS of debris dams
1.40*
0.70*
0.90*
1.10*
0.90*
0.30*
11
Brief Rd crossing
1.40*
1.30*
0.70*
0.90*
1.20*
0.50*
12
Grassy Branch WWTP discharge
0.70*
1.10*
1.70*
0.20*
1.10*
0.10*
13
Grassy Branch Tributary
9.00
8.10
0.90*
3.00
7.50
1.10*
14
Hwy 218 crossing
1.10*
0.60*
0.90*
0.00*
0.80*
0.60*
15
US of Brief Rd
1.00*
0.70*
1.10*
0.50*
0.70*
0.40*
*reflects the numerical result reported from lab analysis although result is below reporting limit.
Report limit for BOD5: 2.0 mg/I, CBOD5: 2.0 mg/I
r1 TETRA TECH
45

Crooked Creek QUAL2K Model
October 15, 2019
Table C-3. Nitrogen species results (units mg/I)
ID
1
Location
Note
1
0.08*
NH3-N
2
0.03*
3
0.02*
1
0.34
NO2+NO3-N
2
0.22
3
0.08
TKN
TN
1
0.46*
2
0.94
3
0.73
1
0.81
2
1.20
3
0.80
US of
Hemby
discharge
2
Hemby
VWVfP
discharge
0.02*
0.05*
0.02*
33.70
42.30
25.10
0.98
0.00*
1.10
34.70
42.30
26.30
3
Indian Trail
Fairview Rd
0.00*
0.07*
0.08*
6.50
3.20
5.40
0.79
0.54
0.98
7.30
3.70
6.30
4
Crooked
Creek #2
discharge
0.00*
0.02*
0.00*
24.00
32.90
33.90
1.20
1.10
1.90
25.10
33.90
35.80
5
US of CC#2
VVWTP
discharge
0.09*
0.08*
0.15
2.30
0.51
0.70
0.53
0.69
1.40
2.80
1.20
2.10
6
Old Farm
Bridge
crossing
0.12
0.05*
0.04*
10.80
20.50
28.90
1.00
1.30
1.50
11.80
21.80
30.50
7
DS of Rocky
River Rd
0.02*
0.05*
0.04*
11.70
23.30
24.10
1.20
0.63
1.50
12.90
23.90
25.50
8
Ridge Road
crossing
0.03*
0.05*
0.03*
10.30
16.40
33.20
1.20
1.10
1.10
11.40
17.40
34.30
9
SF Crooked
Creek
0.07*
0.93
0.11
5.60
0.13
0.00*
1.50
1.60
0.74
7.10
1.70
0.74
10
DS of debris
dams
0.08*
0.07*
0.13
0.46
1.50
8.40
0.92
0.56
1.20
1.40
2.00
9.60
11
Brief Rd
crossing
0.00*
0.02*
0.01*
0.34
2.90
0.67
0.67
0.73
0.75
1.00
3.70
1.40
12
Grassy
Branch
VWVTP
discharge
0.01*
0.44
0.03*
34.00
44.00
53.30
1.30
0.84
0.00*
35.30
44.80
53.30
13
Grassy
Branch
Tributary
0.00*
0.02*
0.02*
1.50
1.70
0.61
0.79
0.25*
0.73
2.30
1.90
1.30
14
Hwy 218
crossing
0.02*
0.07*
0.02*
1.20
3.80
2.50
0.44*
0.70
0.56
1.60
4.50
3.10
15
US of Brief
Rd
0.01*
0.03*
0.00*
0.55
13.80
0.89
0.47*
0.72
0.46*
1.00
14.50
1.30
reflects non -detect, numerical result reported
Reporting limit for NH3-N: 0.10 mg/I, NO2+NO3-N: 0.020 mg/I, TKN: 0.50 mg/I, TN: 0.12 mg/I.
® TETRA TECH
46

Crooked Creek QUAL2K Model
October 15, 2019
Table C-4. Phosphorus species results (units mg/I)
ID Location Note
PO4-P
1
0.06
TP
2
0.16
3
0.12
1
0.13
2
0.10
3
0.05
1
US of Hemby discharge
2
Hemby WWTP discharge
1.80
4.80
4.00
3.20
5.00
5.60
3
Indian Trail Fairview Rd
0.54
2.10
0.50
0.47
0.47
0.57
4
Crooked Creek #2 discharge
2.90
4.60
4.80
2.50
4.80
6.10
5
US of CC#2 WWTP discharge
0.31
1.10
0.16
0.24
0.23
0.36
6
Old Farm Bridge crossing
1.20
2.90
4.10
1.20
2.70
4.50
7
DS of Rocky River Rd
1.30
3.30
3.60
1.20
3.00
3.90
8
Ridge Road crossing
0.32
2.40
3.60
1.10
2.20
4.00
9
SF Crooked Creek
0.34
0.15
0.09
1.10
0.15
0.19
10
DS of debris dams
0.23
2.10
1.10
0.84
0.53
1.10
11
Brief Rd crossing
0.86
2.70
0.43
0.72
0.66
0.65
12
Grassy Branch WWTP discharge
0.30
3.40
4.50
2.70
3.30
4.70
13
Grassy Branch Tributary
0.20
0.26
0.07
0.19
0.12
0.17
14
Hwy 218 crossing
0.16
1.00
0.74
0.75
0.86
0.80
15
US of Brief Rd
0.14
1.90
0.75
0.66
1.60
0.61
Reporting limit for PO4-P: 0.050 mg/I, TP: 0.050 mg/I.
® TETRA TECH
47

Crooked Creek QUAL2K Model
October 15, 2019
C.3 LONGITUDINAL DISSOLVED OXYGEN
Dissolved Oxygen was monitored using a hand-held probe every several hundred meters along the
extent of Crooked Creek on each sampling effort to some degree. The results of the raw DO readings at
each location sampled from each trip are seen below (Figure C-2, Figure C-3, Figure C-4, Table C-5,
Table C-6, Table C-7). Note that these results have not been temperature -corrected. Frequently sampled
alongside dissolved oxygen concentration were: pH, dissolved oxygen saturation, water temperature,
turbidity, and specific conductivity.
lManviNs
TETRA TECH
Crooked Creek Watershed
Longitudinal DO Sampling (8/15-8/19)
L.Pav .e 09.13401e. 14k.w:.
N 0 05 1 2
A...Kilometers
0 0.5 1 2
Miles
Legend
WWT'P Discharge
Large Beaver Dam
NHD HiRes Flowline
QWatershed Boundary
DO (mg/L)
• <4.0
c 4.0 - 5.0
• >5.0
No Data
Figure C-2. Instream longitudinal dissolved oxygen measurements (8/15/16-8/19/16)
® TETRA TECH
48

Crooked Creek QUAL2K Model
October 15, 2019
TETRA TECH
Crooked Creek Watershed
Longitudinal DO Sampling (8/31-9/2)
ws ronr.n u.iisara, wi�i:.
N 0051 2
AOKilometers
0 05 1 2
O Miles
Legend
WWTP Discharge
Large Beaver Dam
NHD HiRes Flowline
QWatershed Boundary
DO (mg/L)
• <4.0
4.0 - 5.0
• >5.0
No Data
Figure C-3. Instream longitudinal dissolved oxygen measurements (8/31/16-9/2/16)
(h)
TETRA TECH
49

Crooked Creek QUAL2K Model
October 15, 2019
f.' TETRA TECH
Crooked Creek Watershed
Longitudinal DO Sampling (9/13-9/16)
N 0 05 1 2
A -Kilometers
0 05 1 2
Miles
Legend
WWTP Discharge
Large Beaver Dam
NHD HiRes Flowline
QWatershed Boundary
DO (mg/L)
• <4.0
4.0 - 5.0
• >5.0
No Data
Figure C-4. lnstream longitudinal dissolved oxygen measurements (9/13/16-9/16/16)
[1]
TETRA TECH
50

Crooked Creek QUAL2K Model
October 15, 2019
Table C-5. Longitudinal data from trip 1 (August 15-19, 2016)
ID
1
Latitude (N)
Longitude (W)
Date
Time
pH
6.29
DO (mg/I)
DO (%Sat)
Temp (°F)
35.1074
80.63715
8/15
17:48
No Data
58.9
79.2
2
35.10429
80.63447
8/15
18:18
6.84
No Data
68.8
80.1
4
35.10346
80.62941
8/15
18:30
6.91
No Data
62
79.5
5
35.10547
80.62941
8/16
8:02
6.95
3.18
39.2
78.3
6
35.10545
80.62855
8/16
8:22
6.99
4.13
51.2
79.0
8
35.10617
80.6272
8/16
8:40
7.14
4.03
49.1
78.3
10
35.10659
80.62418
8/16
9:14
7.13
5.07
61.6
77.5
13
35.10786
80.62229
8/16
9:34
7.1
4.67
55.9
77.4
15
35.10893
80.62077
8/16
10:06
7.18
4.79
58.3
77.4
18
35.109
80.61813
8/16
10:40
7.21
4.68
57.5
77.7
19
35.1076
80.61507
8/16
11:01
7.04
2.97
36.3
78.1
20
35.10626
80.6144
8/16
11:13
7.12
3.65
44.7
78.1
21
35.1044
80.61324
8/16
11:27
7.22
3.15
38.8
78.1
22
35.10303
80.61198
8/16
11:41
7.09
4.5
55.1
78.1
24
35.10164
80.61172
8/16
11:51
7.12
4.53
55.3
77.9
25
35.10003
80.6083
8/16
12:11
7.09
4.78
58.4
77.9
26
35.09868
80.60705
8/16
12:25
7.17
4.43
54.2
77.9
28
35.0975
80.60536
8/16
12:58
7.12
3.13
38.4
78.3
30
35.09652
80.60519
8/16
13:05
7.1
3.24
39.9
78.8
31
35.09602
80.60497
8/16
1:13
6.81
2.29
29.4
80.8
32
35.0961
80.60487
8/16
1:19
7.24
5.22
64.5
79.3
33
35.09645
80.6043
8/16
13:32
7.09
5.11
63.4
79.5
34
35.09502
80.60084
8/16
14:02
7.02
2.62
32.3
79.2
35
35.09652
80.59822
8/16
14:38
7.38
5.2
66.2
81.5
® TETRA TECH
51

Crooked Creek QUAL2K Model
October 15, 2019
ID
36
Latitude (N)
Longitude (W)
80.59677
Date
8/16
Time
15:16
pH
7.31
DO (mg/I)
DO (%Sat)
Temp (°F)
81.7
35.09743
5.13
64.9
38
35.09833
80.59464
8/16
15:33
7.37
3.89
49.1
81.1
39
35.0989
80.59364
8/16
15:47
7.28
3.25
39.9
80.8
41
35.09908
80.59235
8/16
16:00
7.27
3.57
44.9
80.8
43
35.10103
80.58817
8/16
16:22
8.66
11.64
152.3
85.3
45
35.10244
80.58469
8/16
16:48
7.93
7.2
90.4
83.3
46
35.10362
80.58096
8/17
8:28
7.29
3.85
48.2
79.9
48
35.10303
80.57883
8/17
8:43
7.48
5.53
69.8
80.2
50
35.10158
80.57745
8/17
9:00
7.47
4.48
56.8
80.1
52
35.10235
80.57418
8/17
9:14
7.44
4.42
55.1
79.7
53
35.10264
80.57316
8/17
9:32
7.38
4.34
54.3
79.5
54
35.10268
80.57128
8/17
9:53
7.28
4.44
55.3
79.7
56
35.10316
80.56911
8/17
10:15
7.31
2.39
29.9
79.7
58
35.10502
80.56769
8/17
10:36
7.31
4.64
58.5
80.8
60
35.10611
80.56563
8/17
10:54
7.38
3.77
46.1
79.9
61
35.10641
80.56356
8/17
11:32
7.33
3.91
48.8
79.9
62
35.1075
80.56329
8/17
11:48
7.4
4.01
50.2
79.7
63
35.10954
80.56135
8/17
12:13
7.28
5.28
65
78.6
64
35.11013
80.55966
8/17
12:28
7.41
5.13
64.4
80.4
65
35.1108
80.55741
8/17
12:42
7.77
8.08
102.9
82.6
66
35.11146
80.55566
8/17
12:55
7.63
5.03
63
80.4
67
35.11067
80.55408
8/17
13:10
7.4
4.46
56.8
81.7
69
35.11141
80.55309
8/17
13:27
7.36
2.99
37.8
81.1
71
35.11172
80.5519
8/17
13:41
7.33
3
38
81.3
72
35.11196
80.55107
8/17
13:56
7.34
3.21
40.3
80.8
® TETRA TECH
52

Crooked Creek QUAL2K Model
October 15, 2019
ID
74
Latitude (N)
Longitude (W)
Date
8/17
Time
pH
DO (mg/I)
DO (%Sat)
Temp (°F)
35.11223
80.54912
14:23
7.34
3.52
45
81.5
76
35.11278
80.54745
8/17
14:57
7.33
3.9
49.5
81.7
77
35.11274
80.54661
8/17
15:08
7.35
2.47
31.5
81.9
78
35.11441
80.54568
8/17
15:35
7.16
1.22
15.1
79.5
79
35.11661
80.54506
8/17
15:55
7.14
1.1
13.7
79.7
80
35.11855
80.54276
8/17
16:16
7.11
1.9
23.3
80.8
82
35.14477
80.4716
8/18
8:34
7.15
4.27
51.9
77.4
83
35.1331
80.48961
8/18
8:49
7.26
5.3
54.7
77.9
84
35.13116
80.49425
8/18
9:07
7.34
3.7
44.8
76.6
85
35.13099
80.49411
8/18
9:14
6.68
2.78
32.9
74.5
86
35.12245
80.54194
8/18
10:59
6.95
0.82
10.2
78.4
87
35.12229
80.54069
8/18
11:21
7.04
4.43
54.5
79.0
90
35.12278
80.53825
8/18
11:38
7.12
3.64
43.2
78.1
92
35.12492
80.53868
8/18
11:57
7.07
2.78
34
77.7
94
35.12695
80.53902
8/18
12:13
7.06
3.13
38.7
78.3
95
35.12815
80.53928
8/18
12:23
7.02
2.87
35.2
78.1
96
35.12911
80.53567
8/18
12:38
7.05
3.02
37.3
78.6
97
35.12745
80.53224
8/18
13:02
7.05
2.69
32.9
78.8
99
35.12849
80.53107
8/18
13:14
7.2
5.12
63.7
79.7
101
35.12836
80.52878
8/18
13:48
7.3
4.86
60.3
79.5
102
35.12998
80.5269
8/18
14:00
7.35
6.7
83.9
80.4
105
35.13273
80.52562
8/18
14:21
7.48
5.1
63.7
79.9
106
35.1348
80.5248
8/18
14:42
7.29
4.51
56.6
80.2
108
35.13543
80.51939
8/18
15:06
7.62
5.9
76
81.9
109
35.13492
80.51781
8/18
15:37
7.45
6.58
82.5
80.4
® TETRA TECH
53

Crooked Creek QUAL2K Model
October 15, 2019
ID
Latitude (N)
Longitude (W)
Date
Time
pH
DO (mg/I)
DO (%Sat)
Temp (°F)
110
35.13382
80.51204
8/18
15:58
7.49
4.65
59
81.5
111
35.13643
80.5126
8/18
16:12
7.69
4.56
58
81.7
112
35.13899
80.51417
8/18
16:24
7.55
4.09
51.7
81.3
113
35.13919
80.51332
8/18
16:34
7.45
5.07
65.2
81.1
114
35.13871
80.51076
8/18
16:42
7.61
5.52
69.8
81.7
115
35.13842
80.50713
8/18
16:50
7.68
5.81
73.4
81.3
116
35.13825
80.50588
8/18
16:56
7.35
5.3
66.5
79.3
Table C-6. Longitudinal data from trip 2 (August 31-September 2, 2016)
ID
Latitude (N)
Longitude (W)
Date
Time
pH
DO (mg/I)
DO (%Sat)
Temp (°F)
120
35.14462
80.47173
8/31
15:02
7.57
6.33
77.4
77.7
121
35.13301
80.4896
8/31
15:26
7.5
7.37
89.1
76.6
122
35.13091
80.49409
8/31
15:49
6.78
7.87
95
76.6
123
35.13112
80.49418
8/31
16:06
7.28
7.29
87.9
76.5
124
35.13121
80.49426
8/31
16:12
7.79
5.03
61.2
77.7
125
35.13803
80.50548
8/31
17:14
7.46
5.17
61.8
76.3
126
35.12832
80.53928
8/31
17:39
6.9
4.26
51.1
76.1
127
no data
no data
8/31
18:00
6.62
0.82
9.7
74.3
128
35.10136
80.57244
8/31
18:19
7.07
5.47
66.7
77.7
129
35.10238
80.5838
8/31
18:32
7.18
7.17
88.7
79.2
130
35.09903
80.59232
8/31
18:50
6.98
4.52
54.8
77.2
131
35.0961
80.59836
8/31
19:10
7.27
7.67
95.4
79.2
132
35.09506
80.60077
8/31
19:26
6.78
1.87
22.2
74.8
133
35.10788
80.61561
8/31
19:46
6.8
3
35.9
75.9
134
no data
no data
8/31
20:10
7.63
8
98
78.1
135
no data
no data
8/31
20:13
7.55
5.9
70.2
75.4
jj J TETRA TECH
54

Crooked Creek QUAL2K Model
October 15, 2019
ID
136
Latitude (N)
Longitude (W)
Date
9/1
Time
8:13
pH
7.29
DO (mg/I)
DO (%Sat)
Temp (°F)
35.13803
80.50533
4.66
55
74.1
137
35.13571
80.5023
9/1
8:30
7.42
5.59
65.4
73.9
138
35.13332
80.50132
9/1
8:42
7.33
5.79
67.8
73.6
139
35.13187
80.49962
9/1
9:15
7.45
5.9
68.3
73.6
140
35.13139
80.49867
9/1
9:23
7.39
6.51
76.1
73.4
141
35.13094
80.49665
9/1
9:41
7.47
6.45
75.5
73.8
142
35.13089
80.49506
9/1
9:50
7.43
6.81
79.7
73.6
143
35.13116
80.49414
9/1
9:57
7.31
7.35
87.5
75.2
144
35.13094
80.49404
9/1
10:01
6.23
2.67
30.7
71.1
145
35.13134
80.49369
9/1
10:05
7.34
5.87
68.7
73.8
146
35.13165
80.49204
9/1
10:14
7.28
4.65
54.6
73.9
148
35.13233
80.4902
9/1
10:26
7.34
4.96
58.7
74.3
149
35.13306
80.48958
9/1
10:35
7.38
6
70.8
74.7
150
35.1341
80.48951
9/1
10:41
7.47
6.12
72.3
74.7
151
35.13606
80.48993
9/1
10:50
7.35
6.02
70.9
74.3
152
35.13813
80.49062
9/1
11:00
7.45
5.52
65.3
74.7
154
35.13709
80.48772
9/1
11:20
7.63
7.24
86.2
75.4
156
35.13804
80.4855
9/1
11:36
7.6
6.72
79.5
74.7
158
35.14062
80.48538
9/1
12:00
7.54
7.43
87.6
74.5
159
35.14259
80.48672
9/1
12:09
7.44
4.66
54.8
74.1
160
35.14266
80.48602
9/1
12:18
7.42
5.99
71.3
75.2
161
35.14226
80.48444
9/1
12:49
7.23
5.01
60.1
75.9
163
35.14281
80.4832
9/1
13:20
7.26
6.56
79.3
76.8
165
35.1444
80.48367
9/1
13:39
7.47
7.42
91.7
78.6
167
35.14518
80.48033
9/1
13:50
7.24
5.8
69.7
76.3
® TETRA TECH
55

Crooked Creek QUAL2K Model
October 15, 2019
ID
Latitude (N)
Longitude (W)
Date
Time
pH
DO (mg/I)
DO (%Sat)
Temp (°F)
168
35.14437
80.47944
9/1
14:00
7.4
6.17
75.5
78.1
169
35.14214
80.47688
9/1
14:12
7.3
4.67
56.3
77.4
171
35.14138
80.47367
9/1
14:30
7.57
8.05
99.7
79.2
172
35.14304
80.47221
9/1
14:37
7.71
7.87
97.5
79.2
173
35.14477
80.47175
9/1
14:50
7.71
6.54
81.3
79.5
174
35.14561
80.4708
9/1
16:04
7.85
6.37
80.2
80.8
176
35.14824
80.46992
9/1
16:15
7.54
7.77
98.4
81.3
177
35.14809
80.46889
9/1
16:23
7.62
7.55
95.5
81.3
178
35.1466
80.46709
9/1
4:32
7.6
7.23
89.5
79.2
180
35.14716
80.46584
9/1
16:44
7.66
6.45
80.8
80.4
181
35.14845
80.46641
9/1
16:48
7.6
6.7
83
79.2
182
35.15091
80.46693
9/1
16:57
7.66
6.14
76.5
79.9
183
35.15145
80.46413
9/1
17:23
7.75
6.47
80.7
79.9
185
35.14817
80.46246
9/1
17:35
7.85
7.65
94.8
79.2
187
35.14616
80.46063
9/1
17:46
7.8
6.98
86
78.8
188
35.15005
80.45959
9/1
17:57
7.91
6.67
82
78.4
189
35.14981
80.45807
9/1
18:10
7.89
5.28
64.9
78.4
Table C-7. Longitudinal data from trip 3 (September 13-16, 2016)
ID
Latitude
(N)
Longitude
(W)
Date
Time
Turbidity
(NTU)
pH
DO
(mg/I)
DO
(%Sat)
Specific
Conductivity
(uS/cm)
Temp
(°F)
194
35.14474
80.47161
9/14
7:20
6.4
6.53
6.23
71
159
71.1
195
35.13801
80.50545
9/14
7:46
7.4
6.07
6.27
71.6
169.1
71.4
196
35.10223
80.58383
9/14
8:20
10.1
6.48
4.69
54.7
531
73.4
197
35.10636
80.54846
9/14
9:20
11.8
5.95
0.57
6.5
102.2
71.6
198
35.10777
80.548
9/14
9:26
65
6.39
0.09
1.1
103
71.8
® TETRA TECH
56

Crooked Creek QUAL2K Model
October 15, 2019
ID Latitude
(N)
Longitude
(W)
Date
Time
Turbidity
(NTU)
pH
DO
(mg/I)
oDO
(/oSat)
Specific
Conductivity
(uS/cm)
Temp
(oF)
199
35.10886
80.54678
9/14
9:40
13.3
6.61
0.28
3.3
105.1
71.2
200
35.11024
80.54744
9/14
10:02
43
6.59
0.05
0.6
136
71.6
201
35.11235
80.54677
9/14
10:19
10.3
6.79
0.29
3.4
102
71.1
203
35.11274
80.54707
9/14
10:36
12.6
7.09
5.62
65.6
498
73.4
204
35.11332
80.54606
9/14
10:50
11.7
7.16
4.99
58.3
499
73.4
205
35.11466
80.54564
9/14
11:03
15.9
7.17
4.3
50.4
489
73.8
206
35.11606
80.54512
9/14
11:20
19.9
7.07
3.44
40.4
459
73.8
207
35.11754
80.54533
9/14
11:29
33.1
7.02
2.51
29.4
420
73.8
208
35.11809
80.54537
9/14
11:38
28.2
7.02
3.25
37.9
398
73.6
209
35.11847
80.54442
9/14
11:47
14.5
7.05
3.27
38.2
406
73.4
210
35.11859
80.5431
9/14
11:58
12.7
7.05
3.07
36
402
73.8
211
35.11815
80.54212
9/14
12:13
25.4
7.03
3.25
38.6
396
74.3
212
35.11897
80.54178
9/14
12:22
17.4
7.15
3.76
44.1
391
73.8
213
35.12085
80.54262
9/14
12:56
11.2
7.09
2.95
34.3
384
73.0
214
35.12205
80.54395
9/14
13:05
12
7.01
2.98
35
379
73.8
215
35.12263
80.54272
9/14
13:10
39.9
6.98
2.07
24.3
353
73.0
216
35.1223
80.542
9/14
13:14
42.6
6.91
1.67
19.5
337
73.0
217
35.12228
80.54147
9/14
13:23
90
7.02
5.07
59.7
334
74.5
218
35.12233
80.54047
9/14
13:29
29
7.16
5.7
67.5
332
74.8
219
35.1226
80.53941
9/14
13:35
20.9
7.21
6.08
72.2
331
75.0
220
35.12211
80.5386
9/14
13:40
48
7.25
6.14
72.3
331
74.3
221
35.12314
80.5385
9/14
13:50
12.4
7.2
5.58
65.6
333
73.9
222
35.1237
80.53819
9/14
13:57
25.5
7.23
5.76
67.9
335
74.3
223
35.12588
80.53824
9/14
14:08
21.5
7.19
5.15
60.1
344
73.4
224
35.12732
80.53961
9/14
14:18
17.8
7.28
4.98
58.6
339
74.3
® TETRA TECH
57

Crooked Creek QUAL2K Model
October 15, 2019
ID
225
Latitude
(N)
35.12815
Longitude
(W)
80.53922
Date
9/14
Time
14:24
Turbidity
(NTU)
21.4
pH
DO
(mgll)
DO
(%Sat)
Specific
Conductivity
(uSlcm)
333
Temp
(F)
74.1
7.31
4.73
55.7
226
35.12886
80.53698
9/14
14:30
26.4
7.28
4.61
54.1
314
74.1
227
35.13293
80.48951
9/14
15:12
4.5
7.71
8.14
99.3
188
77.7
228
35.13092
80.49402
9/14
15:24
0.1
7.51
18.9
229
263
76.8
229
35.13119
80.49428
9/14
15:31
0.8
7.56
7.8
94.3
837
76.6
230
no data
no data
9/14
16:02
6.9
7.54
7.05
85.1
575
76.5
231
35.09909
80.59237
9/14
16:17
5.6
7.14
5.58
66.8
5.79
75.9
232
35.09612
80.59837
9/14
16:42
3
7.18
7.75
94.7
628
77.7
233
35.09518
80.60079
9/14
16:51
49
7.28
1.63
18.7
198
72.1
234
35.10787
80.61551
9/14
17:07
43.3
7.22
2.68
31.1
274
72.7
235
35.1042
80.63397
9/14
17:19
0.4
7.06
8.16
98.1
641
76.1
236
35.10434
80.63426
9/14
17:24
54.4
7.29
2.92
33.6
125
72.1
237
35.1288
80.537
9/15
7:30
14.9
7.47
4.44
51.2
330
72.1
238
35.12906
80.53555
9/15
7:38
11.6
7.29
4.31
49.6
332
72.0
239
35.12732
80.53225
9/15
7:48
12.2
7.2
3.54
41
313
72.5
240
35.12809
80.53156
9/15
7:56
8.5
7.19
3.55
40.9
299
72.1
241
35.12933
80.5312
9/15
8:04
4.5
7.33
5.86
67
294
71.4
242
35.1295
80.53051
9/15
8:09
23.4
7.37
5.89
67.2
293
71.2
243
35.12904
80.52917
9/15
8:15
16.9
7.35
5.36
61.2
291
71.4
244
35.1277
80.52801
9/15
8:24
8.5
7.35
5.09
58.6
291
72.1
245
35.12745
80.52695
9/15
8:34
8.5
7.34
5.14
59.3
279
72.5
246
35.1299
80.52703
9/15
8:48
10.1
7.41
6.18
70.6
274
71.4
247
35.13115
80.52707
9/15
8:56
5.1
7.44
6.29
71.7
271
71.1
248
35.13271
80.5256
9/15
9:03
4.8
7.43
5.71
65.6
266
71.8
249
35.13482
80.52454
9/15
9:10
10.2
7.33
4.98
57.7
238
72.9
® TETRA TECH
58

Crooked Creek QUAL2K Model
October 15, 2019
ID
250
Latitude
(N)
Longitude
(W)
Date
Time
Turbidity
(NTU)
pH
DO
(mg/I)
(at)
(%Sat)
Specific
(uS/cm)
Temp
(F)
72.7
35.13532
80.523
9/15
9:30
22.5
7.38
6.29
72.8
237
251
35.13454
80.52183
9/15
9:41
18.3
7.47
6.72
77.4
234
72.3
252
35.13451
80.52116
9/15
10:00
10.6
7.46
6.45
74.1
233
72.0
253
35.13541
80.51936
9/15
10:20
5
7.55
6.41
73.2
231
71.4
254
35.13516
80.51765
9/15
10:25
14.1
7.43
5.36
61.6
229
71.8
255
35.13304
80.51588
9/15
10:35
11.9
7.5
5.56
64.6
213
72.9
256
35.13282
80.51525
9/15
10:40
10.4
7.41
5.48
63.5
210
72.9
257
35.1327
80.51311
9/15
10:52
9.7
7.4
5.2
60.4
206
73.0
258
no data
no data
9/15
10:58
7.9
7.67
6.01
69.6
205
72.7
259
35.13502
80.51162
9/15
11:17
10.9
7.34
5.77
66.8
199
72.7
260
35.13643
80.51194
9/15
11:23
no data
7.73
6.99
80.7
198
72.5
261
35.13703
80.51332
9/15
11:31
10.2
7.48
6.62
76.2
197
72.1
262
35.13924
80.51406
9/15
11:43
10.3
7.33
4.65
54
185
73.0
263
35.13919
80.5123
9/15
11:53
8.5
7.52
6.23
72.5
185
73.2
264
no data
no data
9/15
11:55
7.4
7.45
6.45
75.1
186
73.0
265
no data
no data
9/15
11:58
14.9
7.43
6.74
78.8
183
73.6
266
35.13913
80.51331
9/15
12:02
16.8
7.29
6.03
70.7
183
73.9
267
35.13929
80.51405
9/15
12:06
43.1
7.36
5.96
70.1
184
74.1
268
35.13933
80.51427
9/15
12:09
12.5
7.3
4.92
57.4
185
73.4
269
35.13878
80.51134
9/15
12:40
10.9
7.89
6.82
79.8
183
73.8
270
35.13878
80.51134
9/15
12:45
4.8
7.28
3.12
36.3
154
72.7
271
no data
no data
9/15
12:52
4
7.57
7.05
82.2
175
73.2
272
35.13826
80.51035
9/15
12:54
5.9
7.6
7.31
86.2
183
74.3
273
35.13817
80.50831
9/15
13:06
17.2
7.63
7.65
89.2
180
73.4
274
35.13847
80.50727
9/15
13:11
6.5
7.66
7.93
92.6
180
73.6
® TETRA TECH
59

Crooked Creek QUAL2K Model
October 15, 2019
ID
Latitude
(N)
Longitude
(W)
Date
Time
Turbidity
(NTU)
pH
DO
(mg/I)
DO
(%Sat)
Specific
Conductivity
(uS/cm)
Temp
(0F)
275
no data
no data
9/15
13:22
11.9
7.52
7.1
82.4
178
72.9
276
no data
no data
9/15
13:28
7.1
7.39
5.82
68.6
174
74.3
277
35.13634
80.5026
9/15
13:39
10.7
7.82
8.13
97.4
171
76.1
278
35.13442
80.5015
9/15
13:46
13.1
7.84
8.56
102.1
169
75.7
279
35.13269
80.50138
9/15
13:57
7.1
7.88
8.94
108.3
167
77.2
280
35.13197
80.49989
9/15
14:02
6.6
7.89
8.5
101.7
166
75.9
281
35.13145
80.4984
9/15
14:10
9.3
7.7
8.1
95.6
166
74.5
282
35.1309
80.49506
9/15
14:19
8.6
7.87
8.91
107.1
164
76.3
283
35.13115
80.49435
9/15
14:23
11.9
7.58
5.73
65.8
166
72.5
284
35.13125
80.4938
9/15
14:26
16
7.72
8.82
105.4
253
75.7
285
35.13105
80.49401
9/15
14:29
0.1
7.63
16.7
197
269
74.7
286
35.13116
80.4942
9/15
14:32
1.9
7.54
7.84
94.5
790
76.3
C.4 DIURNAL DISSOLVED OXYGEN
Daily cycles of dissolved oxygen concentration can vary due to temperature, macrophyte productivity, and
changes in point sources. Diurnal DO was measured using long-term sondes for multiple days at a
number of locations along Crooked Creek at ten-minute intervals. The sampling locations for each trip are
shown in Figure C-5, with overall statistics reported in Table C-8. Timeseries results of all results for all
sites (not temperature -corrected) are seen in Figure C-6, Figure C-7, and Figure C-8.
Table C-8. Dissolved oxygen sonde result statistics (units are mg/L)
Trip
Site
Average DO
Minimum DO
Maximum DO
DO Range
1
(8/13-8/19)
DS of CC#2
4.46
3.60
5.12
1.52
HWY 601
3.15
2.54
3.72
1.18
US of CC#2
2.03
1.01
3.25
2.24
2
(8/31-9/2)
Brief Rd
4.97
4.11
6.28
2.17
SR 1601
4.52
3.30
5.83
2.53
® TETRA TECH
60

Crooked Creek QUAL2K Model
October 15, 2019
Trip
Site
Average DO
Minimum DO
Maximum DO
DO Range
HWY 601
3.47
2.82
5.01
2.19
3
(9/13-9/16)
Brief Rd
3.93
3.30
4.94
1.64
N Rocky River
Rd
4.89
3.54
6.70
3.16
SR 1601
4.67
3.33
6.33
3.00
N. TETRA TECH
\\
Crooked Creek Watershed
Dissolved Oxygen Sonde Sites
No paOUW e..201a Ne<M1m
Ao 0.5o2Kdometers
0 0.5 t
Mties
Sonde Location (8/13-8/19)
Sonde Location (8/31-9/2)
Sonde Location (9/13-9/16)
WWTP Discharge
NHD HiRes Flowline
Watershed Boundary
Figure C-5. Dissolved oxygen monitoring sonde sites (all trips)
TETRA TECH
61

Crooked Creek QUAL2K Model
October 15, 2019
8/15/16 13:00 8/16/16 1:00 8/16/16 13:00 8/17/16 1:00 8/17/16 13:00 8/18/16 1:00
• Trip 1: US of CC#2 • Trip 1: OS from CC#2 • Trip 1: HWY 601
Figure C-6. Diurnal dissolved oxygen concentrations (8/15-8/19), gray areas are night (7pm-7am)
8
7
5
0
4
3
O 3
2
1
0
8/31 16:49 8/31 21:37 9/12:25 9/17:13 9/112:01 9/116:49 9/121:37 9/2 2:25 9/2 7:13
• Trip 2: Brief Rd • Trip 2: SR 1601 • Trip 2: HWY 601
Figure C-7. Diurnal dissolved oxygen concentrations (8/31-9/2), gray areas are night (7pm-7am)
® TETRA TECH
62

Crooked Creek QUAL2K Model
October 15, 2019
0
9/14 7:00 9/14 11:48 9/14 16:36 9/14 21:24 9/15 2:12 9/15 7:00 9/15 11:48 9/15 16:36
• Trip 3: Brief Rd • Trip 3: N Rocky River Rd • Trip 3: SR 1601
Figure C-8. Diurnal dissolved oxygen concentrations (9/13-9/16), gray areas are night (7pm-7am)
® TETRA TECH
63

Hazen
Attachment D: Crooked Creek Model Application
for Grassy Branch Wastewater Treatment Plant,
Tetra Tech, October 15, 2019

Crooked Creek QUAL2K Model Application
for Grassy Branch WWTP
Union County, North Carolina
December 4, 2019
PREPARED FOR
Union County Public Works
500 North Main Street, Suite 500
Monroe, NC 28112
PREPARED BY
Tetra Tech
One Park Drive, Suite 200
PO Box 14409
Research Triangle Park, NC 27709
Pictured: North Fork Crooked Creek (Tetra Tech, 2016)
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TABLE OF CONTENTS
1.0 INTRODUCTION 1
2.0 QUAL2K MODEL APPLICATION SET-UP 3
2.1 Simulating Critical Conditions 3
2.1.1 Critical Low Flow Statistics 3
2.1.2 Modified Seasonal Inputs 4
2.1.3 Permitted Discharge Assumptions 6
3.0 MODIFIED DISCHARGE CONDITIONS SCENARIO RESULTS 8
3.1 Model Application Sensitivity Testing 9
3.2 Instream Ammonia Toxicity 9
3.3 Instream TSS and Turbidity 10
LIST OF TABLES
Table 1. Estimated 7Q10 flow tabulated for boundary conditions of Crooked Creek. 3
Table 2. Existing point source permit limits for water treatment facilities along Crooked Creek. 6
Table 3. Proposed SOC and final effluent permit limits for Grassy Branch WWTP (NC0085812) 6
Table 4. Effluent water temperature for seasonal simulations. 7
Table 5. Crooked Creek QUAL2K model scenarios results for summer and winter critical conditions. 8
Table 6. Crooked Creek QUAL2K model scenarios sensitivity testing. 9
Table 7. Crooked Creek QUAL2K model application scenario results for ammonia toxicity. 10
Table 8. Crooked Creek QUAL2K model application scenario results for instream TSS concentration11
LIST OF FIGURES
Figure 1. Crooked Creek watershed location map, model segmentation, and WWTP discharge sites. 2
Figure 2. Crooked Creek QUAL2K model 7Q10 flow balance schematic diagram 4
Figure 3. Crooked Creek QUAL2K model scenario results for summer and winter. 8
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Crooked Creek Model Application for Grassy Branch WWTP-Union County
December 4, 2019
1.0 INTRODUCTION
This technical modeling memo is intended to accompany Union County's request for receiving a Special
Order by Consent (SOC) from the North Carolina Division of Water Resources for the Grassy Branch
Wastewater Treatment Plant (WWTP). The facility (NPDES Permit No. NC0085812) discharges into
Crooked Creek approximately seven river miles upstream of the confluence with the Rocky River in the
Yadkin -Pee Dee River Basin. The Grassy Branch WWTP has exhibited periodic noncompliance with
existing effluent NPDES permit limits. The County is seeking interim limits under the SOC and this memo
summarizes our findings of a modeling assessment performed to evaluate potential impacts on the
receiving waters of the proposed interim limits.
A QUAL2K model for Crooked Creek was used for the modeling assessment. The model was calibrated
and corroborated based on data collected in 2016 (Tetra Tech, 20191). The QUAL2K model development
report and corresponding Excel files were submitted to the North Carolina Division of Water Resources
(DWR) on August 12-13, 2019 and verbal approved was received in -person from DWR staff on October
1, 2019. For this SOC modeling analysis, the calibrated QUAL2K model was setup to simulate seasonally
critical conditions and maximum permitted effluent discharges for all treatment facilities located along
Crooked Creek. This report details the QUAL2K model application and SOC scenario analysis.
1 Tetra Tech. 2019. Crooked Creek QUAL2K Model Development; Union County, North Carolina.
Prepared for Union County Public Works, Monroe, NC.
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP-Union County December 4, 2019
Hemby Acres WWTP
North Fork Crooked Creek,
Crooked Creek WWTP #2•
Crooked Creek
Grassy Branch WWTP
South Fork Crooked Creek
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Crooked Creek Watershed
QUAL2K Model Segmentation
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nwon�a.a>�ozuir Hra:new
N 0051 2
A v Kilometers
0 05 1 2
Miles
Rocky River
Grassy Branch
Legend
• WWTP Discharge
A Large Beaver Dam
River/Stream
QWatershed Boundary
Model Reach
Reach 1
i Reach 2
Reach
•� Reach
Reach 5
Figure 1. Crooked Creek watershed location map, model segmentation, and WWTP discharge sites.
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP-Union County December 4, 2019
2.0 QUAL2K MODEL APPLICATION SET-UP
North Carolina Water Quality Regulations (15A NCAC 02B .0206) specifies that water quality standards
related to oxygen -consuming wastes be protected using the minimum average flow for a period of seven
consecutive days that has an average recurrence of once in ten years (7Q10 flow). Additionally, the NC
regulations (15A NCAC 02B .0404) provide for seasonal variation for the discharge of oxygen -consuming
wastes, with the summer period defined as April through October and winter period as November through
March. Set-up of the Crooked Creek QUAL2K model for evaluating impacts under seasonal critical
conditions is documented below.
2.1 SIMULATING CRITICAL CONDITIONS
2.1.1 Critical Low Flow Statistics
There are very limited flow gage records within the Crooked Creek watershed. Curtis Weaver of USGS
provided 7Q10 estimates for the watershed based on a drainage area relationship of 0.001 cubic feet per
square mile (cfsm) derived from the nearby Richardson Creek and Crooked Creek monitoring data
(USGS, September 2019 via email correspondence). A winter 7Q10 estimate was also provided by Mr.
Weaver as one order of magnitude greater, at 0.01 cfsm. Mr. Weaver provided 7Q10 flow estimates
based on drainage area at Highway 601 and NC Highway 218 of 0.037 cfs and 0.0.044 cfs respectively
for summer, and 0.371 cfs and 0.444 cfs respectively for winter. Applying this 7Q10 relationship, flow was
calculated at the model boundary inputs for the Crooked Creek QUAL2K model (Table 1). Based on the
tributary inflows and the two instream estimates provided by Mr. Weaver, a simple flow balance equation
was used to determine the amount of flow which must enter the stream via diffuse baseflow as well
(Table 1; Figure 2).
Table 1. Estimated 7Q10 flow tabulated for boundary conditions of Crooked Creek.
Boundary Condition
Headwater
Drainage Area
s
(mi)
7.4
Summer 7Q10
Flow (cfs)
0.007
Winter 7Q10
Flow (cfs)
0.074
South Fork Crooked Creek (SF CC) tributary
18.4
0.018
0.184
Grassy Branch tributary
3.8
0.004
0.038
Diffuse Flow 1: Headwaters to Highway 601
N/A
0.011
0.113
Diffuse Flow 2: Highway 601 to NC Highway 218
N/A
0.004
0.035
Diffuse Flow 3: NC Highway 218 to Outlet
N/A
0.006
0.059
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP-Union County December 4, 2019
Headwater Inflow
Summer 7Q10: 0.007 cfs
Winter 7010: 0.074 cfs
SF CC Tributary
Summer 7Q10: 0.018 cfs
Winter 7Q10: 0.184 cfs
Highway 601 instream flow
Summer 7Q10: 0.037 cfs
Winter 7Q10: 0.371 cfs
Grassy Branch Tributary
Summer 7Q10: 0.004 cfs
Winter 7Q10:0.038 cfs
NC Highway 218 instream flow
Summer 7Q10: 0.044 cfs
Winter 7Q10: 0.444 cfs
Outlet instream flow
Summer 7Q10: 0.050 cfs
Winter 7Q10: 0.503 cfs _
}
Diffuse Inflow 1
Summer 7Q10: 0.011 cfs
Winter 7Q10: 0.113 cfs
Diffuse Inflow 2
Summer 7Q10: 0.004 cfs
Winter 7Q10: 0.035 cfs
Diffuse Inflow 3
Summer 7Q10: 0.006 cfs
Winter 7Q10: 0.059 cfs
Figure 2. Crooked Creek QUAL2K model 7Q10 flow balance schematic diagram.
2.1.2 Modified Seasonal Inputs
2.1.2.1 Summer Critical Conditions
The summer period is identified (per 15A NCAC 02B .0404) in the existing permit as April 1 to October
31. The summer critical conditions model for Crooked Creek is based primarily on the calibration model.
Key differences from the calibration model include:
• Modification of simulation date based on warmest summer month for water temperature
o Meteorological inputs modified based on new simulation date
• Modification of boundary conditions (headwaters and tributaries)
o Flows to represent critical 7Q10 conditions instream (see Table 1)
o Water temperature to represent critically warm summer conditions
o DO concentrations to represent median DO saturation observed during critically warm
summer conditions
• Diffuse inflow conditions were parameterized identically to the headwater boundary conditions
All other model inputs were held constant from the calibration model for the summer critical conditions
simulation.
The warmest summer water temperatures were found to occur in the month of July based on instream
water quality data sampling conducted by the Yadkin Pee Dee River Basin Association (YPDRBA) at four
sites along Crooked Creek. To parameterize the boundary conditions (headwater, diffuse flow, and
tributary inflow), a statistical analysis was conducted on observed instream data measured immediately
upstream of the Hemby Acres WWTP. This upstream location is the only water quality sampling site in the
basin which is not influenced by an upstream effluent discharge. The 75th percentile water temperature of
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP—Union County December 4, 2019
all measurements at this location (2014 — 2019) during the month of July was 25.0 °C. The median DO
saturation observed during all July measurements of both temperature and DO at this location was 58%.
Applying this 58% DO saturation to the water temperature of 25.0 °C results in a boundary condition DO
concentration of 4.8 mg/I applied to the headwaters, diffuse, and tributary inflows.
QUAL2K requires assignment of a simulation date to support meteorological conditions. The 75th
percentile water temperature of 25.0 °C is similar to the average water temperatures observed in July
2015, so the summer critical condition simulation date was selected as July 15, 2015. Meteorological
inputs for hourly air and dew point temperatures were pulled from this new simulation date from the same
gage as was used for the calibration and corroboration model setup (KNCUNION2 at Campobello Drive).
Average air and dew point temperatures on July 15, 2015 are 29.9 °C (85.8 °F) and 19.3 °C (66.7 °F)
respectively.
2.1.2.2 Winter Critical Conditions
The winter period is identified (per 15A NCAC 02B .0404) in the existing permit as November 1 to March
31. For the winter critical conditions simulation, the following modifications were made relative to the
baseline calibration model:
• Modification of simulation date based on warmest winter month for water temperature
o Meteorological inputs modified based on new simulation date
• Modification of boundary conditions (headwaters and tributaries)
o Flows to represent winter 7Q10 conditions instream (see Table 1)
o Water temperature to represent critically warm winter conditions
o DO concentrations to represent median DO saturation observed during critically warm
winter conditions
• Average shade conditions were decreased by half from 70% to 35% relative to summer
conditions to simulate the impact of assumed winter leaf -fall
• Diffuse inflow conditions were parameterized identically to the headwater boundary conditions
All other model inputs were held constant from the calibration model for the summer critical conditions
simulation.
Critical winter conditions for water temperature were estimated for boundary conditions using the period
of record of instream YPDRBA water quality data. On average, the warmest winter water temperatures
occur in the month of November. Water temperature inputs for boundary conditions (headwaters,
tributaries, and diffuse inflow) were developed based on the 75'h percentile of all observed water
temperature results in the POR for the instream water quality sampling site located immediately upstream
of Hemby Acres WWTP. The result of this analysis is 13.4 °C, which was applied to all winter critical
condition boundary inputs. The median DO saturation observed during all November measurements of
both temperature and DO was 67%. Applying this 67% DO saturation to the water temperature of 13.4 °C
results in a boundary condition DO concentration of 7.0 mg/I.
Based on the critical warm water temperature analysis the month of November, the simulation date was
selected to be the first of November. The simulate date was selected to be November 1, 2015 as the
summer critical condition was also chosen for the year 2015.
Meteorological inputs for hourly air and dew point temperatures were pulled from station KNCUNION2.
Average air and dew point temperatures on November 1, 2015 are 15.5 °C (59.9 °F) and 13.8 °C (56.9
°F) respectively.
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP—Union County December 4, 2019
2.1.3 Permitted Discharge Assumptions
There are three permitted point sources located along Crooked Creek modeled explicitly: Hemby Acres
WWTP which is operated by Carolina Water Services Inc., Crooked Creek #2 WWTP and Grassy Branch
WWTP which are both operated by Union County. For model application scenarios, inputs were based on
permitted effluent limitations. Calibration model inputs were held constant for non -permitted constituents
(i.e. inorganic and organic phosphorus) for these simulations.
Existing permit limits for the three outfalls along Crooked Creek vary seasonally and by facility (Table 2).
Due to noncompliance with existing permitted limits for the Grassy Branch WWTP Union County is
proposing modified limits for the facility which would reflect an interim SOC period and future final permit
limits, both for higher effluent flow conditions (Table 3). Because of the expansion of flow from the facility
from 0.05 MGD to 0.12 MGD, permit limits associated with ammonia change from existing permit limits of
2 and 4 mg/I for summer and winter to 1 and 3 mg/I respectively, while the year-round permit limit for DO
concentration must stay above 6 mg/I rather than the existing permit limit of 5 mg/I. Discharge Monitoring
Report (DMR) data for Grassy Branch WWTP from 2015 — 2019 includes 184 DO measurements, only 3
of which are below 6 mg/I (2% of samples), so meeting the final permit limit of 6 mg/I for DO should not be
an issue for the facility. On average, the WWTP performs with 96% BOD5 removal, 97% TSS removal,
and 96% NH3 removal based on DMR records.
Similar to the calibration and corroboration model setup, total suspended solids (TSS) is simulated
conservatively as inorganic suspended solids (ISS) since organic solids are captured already through the
simulation of BOD5 as CBODfast in the model.
Table 2. Existing point source permit limits for water treatment facilities along Crooked Creek.
NPDES ID
Facility
Season
Flow
(MGD)
BOD5
(mg/I)
NH3
(mg/I)
DO
(mg/l)
TSS (mg/I)
NC0035041
Hemby
Acres
Summer
0.3
9
3
5
30
Winter
15
8
NC0069841
Crooked
Creek #2
Summer
1.9
5
2
? 6
30
Winter
10
4
NC0085812
Grassy
Branch
Summer
0.05
5
2
5
30
Winter
10
4
Table 3. Proposed SOC and final effluent permit limits for Grassy Branch WWTP (NC0085812).
Permit Note Season Flow (MGD)
Interim SOC Limits
Final Limits
Summer
Winter
Summer
Winter
0.12
0.12
5
10
NH3
(mg/I)
6
20
1
2
DO
(mg/I)
5
6
TSS (mg/I)
100
30
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP-Union County December 4, 2019
For summer and winter simulation periods, the following scenarios were simulated:
1. Critical summer conditions, Grassy Branch at interim SOC limits, other outfalls at permit limits
2. Critical summer conditions, Grassy Branch at final permit limits, other outfalls at permit limits
3. Critical winter conditions, Grassy Branch at interim SOC limits, other outfalls at permit limits
4. Critical winter conditions, Grassy Branch at final permit limits, other outfalls at permit limits
For the seasonal simulations, the water temperature associated with each effluent discharge point source
was developed using the average observed July or November water temperature for 2015 (Table 4).
Table 4. Effluent water temperature for seasonal simulations.
Facility
Hemby Acres
Crooked Creek #2
Grassy Branch
Summer Water Temperature (°C), Winter Water Temperature (°C),
Average July 2015 Average November 2015
25.9
26.3
25.7
14.4
18.2
15.9
Note that there is one other permitted discharge for groundwater remediation located near the
headwaters of the South Fork Crooked Creek. This permittee (NPDES ID NC0088838) for the Radiator
Specialty Company has a maximum permitted discharge limit of 0.09 MGD and monthly water quality
limits for the effluent are associated with TSS (30 mg/I), with additional daily maximum limits for a number
of pollutants such as tetrachloroethene, vinyl chloride, and dioxane. Although this permitted discharge for
groundwater remediation is located far upstream along the South Fork Crooked Creek, the point source
was included explicitly in the model at the outlet of South Fork Crooked Creek into the mainstem as
permit limits for flow and TSS. Model parameterization for temperature and DO were set equal to those of
the South Fork Crooked Creek tributary.
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP-Union County December 4, 2019
3.0 MODIFIED DISCHARGE CONDITIONS SCENARIO RESULTS
Results for both summer and winter seasonal scenarios indicate that there is assimilative capacity for
both interim SOC and final permit limits (Table 5, Figure 3). Although DO concentration is predicted to
drop well below the standard in the upper portion of Crooked Creek under critical summer and winter
conditions due to extreme low flow and physical channel configuration, the Grassy Branch outfall is well
downstream of these locations. The minimum DO concentration downstream of the Grassy Branch
WWTP outfall simulated for both interim SOC and final permit limits is predicted to remain above the
instream WQS of 5.0 mg/I DO.
Table 5. Crooked Creek QUAL2K model scenarios results for summer and winter critical conditions.
Scenario
Scenario Description
DO minimum
downstream of Grassy
Branch WWTP (mg/I)
DO at Crooked
Creek outlet
(mg/I)
5.89
1
Critical summer conditions, Grassy
Branch at interim SOC limits, other
outfalls at permit limits
5.39
2
Critical summer conditions, Grassy
Branch at final permit limits, other outfalls
at permit limits
5.53
5.99
3
Critical winter conditions, Grassy Branch
at interim SOC limits, other outfalls at
permit limits
5.66
6.99
4
Critical winter conditions, Grassy Branch
at final permit limits, other outfalls at
permit limits
5.76
7.16
Hemby CC#2
WWTP WWTP
SFCC
Trib
Beaver
Dams
Grassy
Trib
Grassy
WWTP
10.00
9.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
- 300
1 0.00
30.00 25.00 20.00 15.00 10.00 5.00 0.00
Distance from outlet (km)
- - - - WQS - Summer -Interim SOC Limits - Summer -Final Permit Limits - Winter -interim SOC Limits - Winter -Final Permit Limits
Figure 3. Crooked Creek QUAL2K model scenario results for summer and winter.
Mean DO (mg/1)
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP-Union County December 4, 2019
3.1 MODEL APPLICATION SENSITIVITY TESTING
One area of uncertainty associated with the model application scenarios is related to the level of bottom
algae anticipated for critical summer and winter conditions. As mentioned, the model application
scenarios were run with bottom algae conditions that were simulated for the calibration model period
(bottom algae coverage of 25% for reach 1, and 50% for all other reaches). To test model sensitivity to
this parameter, the model application scenarios were run under conditions that bottom algae coverages
by reach were increased or decreased by 10% (e.g. reach 1 modified to 15% or 35% coverage, and all
other reaches modified to 40% or 60% coverage). Note that on average, this represents a 20 percent
change in parameter values (i.e., 10/50 is 0.2 or 20 percent).
The results of these sensitivity analyses reveal that even under relative model uncertainty on this
parameter, the water quality standard of 5.0 mg/I DO is still met downstream of the Grassy Branch WWTP
discharge for all seasonal and effluent conditions (Table 6).
Table 6. Crooked Creek QUAL2K model scenarios sensitivity testing.
Scenario
Scenario Description
Baseline DO minimum
DS of Grassy Branch
WWTP (mg/I)
Bottom
Algae
Coverage
DO minimum DS
of Grassy Branch
WWTP (mg/I)
1
Critical summer conditions,
Grassy Branch at interim
SOC limits, other outfalls at
permit limits
5.39
60%
5.55
40%
5.22
2
Critical summer conditions,
Grassy Branch at future
permit limits, other outfalls at
permit limits
5.53
60%
5.71
40%
5.34
3
Critical winter conditions,
Grassy Branch at interim
SOC limits, other outfalls at
permit limits
5.66
60%
5.92
40%
5.38
4
Critical winter conditions,
Grassy Branch at future
permit limits, other outfalls at
permit limits
5.76
60%
6.03
40%
5.48
3.2 INSTREAM AMMONIA TOXICITY
When effluent flows dominate instream conditions, there can be a concern about ammonia toxicity. For
low -flow streams, DWR has set forth a policy that ammonia toxicity is defined as instream concentrations
from ammonia exceeding 1.0 mg/I in summer, and 1.8 mg/I in winter. As shown below, for all model
application scenarios, ammonia toxicity is not exceeded (Table 7).
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP—Union County December 4, 2019
Table 7. Crooked Creek QUAL2K model application scenario results for ammonia toxicity.
Maximum NH3
Scenario Scenario Description downstream of Grassy
Branch WWTP (mg/I)
1
Critical summer conditions, Grassy
Branch at interim SOC limits, other
outfalls at permit limits
0.34
NH3 at Crooked
Creek outlet
(mg/I)
0.06
2
Critical summer conditions, Grassy
Branch at final permit limits, other outfalls
at permit limits
0.11
0.06
3
Critical winter conditions, Grassy Branch
at interim SOC limits, other outfalls at
permit limits
1.00
0.04
4
Critical winter conditions, Grassy Branch
at final permit limits, other outfalls at
permit limits
0.21
0.03
3.3 INSTREAM TSS AND TURBIDITY
Turbidity is a measure of water clarity or cloudiness, and the water quality standard in North Carolina for
Class C waters is a maximum of 50 Nephelometric Turbidity Units (NTU)2. Although Crooked Creek and
its tributaries are not impaired for turbidity, Crooked Creek discharges into the Rocky River which is
impaired for turbidity. Key sources of turbidity in the Rocky River watershed have been identified as
largely related to stormwater runoff and erosive land use practices which cause sediment wash -off during
precipitation events3.
Generally, high instream turbidity measurements are associated with precipitation events rather than low -
flow conditions which are simulated in this critical conditions QUAL2K model scenario. Model output for
TSS can provide some insight into the assimilation of particulate matter instream under low -flow
conditions, however the true impact of turbidity instream cannot be captured by this steady-state critical
conditions model simulation (Table 8). There are not explicit TSS water quality standards for North
Carolina Class C waterways.
2 NC DWR. 2019. NC 15A NCAC 02B Water Quality Standards for Surface Waters.
3 NC DWQ. 2008. Yadkin -Pee Dee River Basin Plan: Rocky River HUC 03040105.
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Crooked Creek QUAL2K Model Application for Grassy Branch WWTP—Union County December 4, 2019
Table 8. Crooked Creek QUAL2K model application scenario results for instream TSS concentration.
Scenario
Scenario Description
Maximum TSS
downstream of Grassy
Branch WWTP (mg/I)
TSS at Crooked
Creek outlet
(mg/I)
1
Critical summer conditions, Grassy
Branch at interim SOC limits, other
outfalls at permit limits
14.50
9.26
2
Critical summer conditions, Grassy
Branch at final permit limits, other outfalls
at permit limits
11.10
8.20
3
Critical winter conditions, Grassy Branch
at interim SOC limits, other outfalls at
permit limits
11.65
6.08
4
Critical winter conditions, Grassy Branch
at final permit limits, other outfalls at
permit limits
8.56
5.02
Turbidity has been measured along Crooked Creek at the four instream YPDRBA sampling sites since
1998. Of the total 913 turbidity measurements, 124 measurements exceed the water quality standard of
>_50 NTU, which is 14% of all samples from July 1998 through July 2019. For the period of record at each
sampling location, the median turbidity measurement ranges from 14 — 16 NTU, the average ranges from
26 — 30 NTU, and the maximum measurements range from 298 — 360 NTU.
Paired sampling data of TSS and turbidity are available at YPDRBA site Q8388000 downstream of the
Grassy Branch WWTP and tributary on Crooked Creek. The 71 paired samples at this site suggest a
generally linear relationship between TSS and turbidity concentrations when analyzed directly, however
the relationship is skewed by only 7 paired results for which turbidity results are >_ 50 NTU. When the
paired data is transformed using a natural logarithm, the R-squared value for the entire dataset is 0.4, and
when turbidity data less than 50 NTU is considered, the R-squared value drops to 0.1.
When turbidity measurements are >_ 50 NTU at site Q8388000, TSS measurements range from 15 — 224
mg/I, which suggests that turbidity violations are not observed when TSS measurements are below 15
mg/I. Although the relationship between turbidity and TSS is weak at this location, simulation results and
existing instream data suggest that there is reason to believe that the Grassy Branch WWTP interim SOC
and final permit limits will not contribute to turbidity water quality problems during low flow periods. The
impact of these permit limits on high flow events are similarly unlikely to contribute to stream turbidity
degradation due to the relatively low effluent flow associated with the Grassy Branch WWTP facility
relative to instream flows.
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Rocky
AU Name
AU ID
Description
NORTH CAROLINA 2020 INTEGRATED REPORT
Yadkin -Pee Dee River Basin
Crooked Creek
J
2248
From source to Rocky River
AU Number Classification
13-17-20
C
AU LengthArea AU Units
12.9
FW Miles
2020 Draft Water Quality Assessments
PARAMETER
IR CATEGORY CRITERIA STATUS
REASON FOR RATING
Benthos (Nar, AL, FW)
Fish Community (Nar, AL, FW)
Water Temperature (32°C, AL, LP&CP)
Dissolved Oxygen (4 mg/I, AL, FW)
pH (6 su, AL, FW)
pH (9.0, AL, FW)
Turbidity (50 NTU, AL, FW miles)
Fecal Coliform (GM 200/400, REC, FW)
e3a
1
Meeting Criteria
1
Meeting Criteria
Meeting Criteria
i_
1
Meeting Criteria
Meeting Criteria
Meeting Criteria
i
Excellent, Good, Natural, Good -Fair,
Excellent, Good, Natural, Good -Fair,
Meeting Criteria with Statistical Con
1
1
Meeting Criteria with Statistical Con
1
Meeting Criteria with Statistical Con
Meeting Criteria with Statistical Con
i
'Data Inconclusive
1
1
Meeting Criteria
'Data Assessment Inconclusive
1
1
Pathogen Indicator Meeting Criteria
North Fork Crooked Creek
2249
13-17-20-1
C
12.0
FW Miles
From source to Crooked Creek
2020 Draft Water Quality Assessments
PARAMETER
IR CATEGORY CRITERIA STATUS
REASON FOR RATING
Benthos (Nar, AL, FW)
Water Temperature (322C, AL, LP&CP)
Dissolved Oxygen (4 mg/I, AL, FW)
pH (6 su, AL, FW)
pH (9.0, AL, FW)
Turbidity (50 NTU, AL, FW miles)
Fecal Coliform (GM 200/400, REC, FW)
5
1
1
1
1
5
3a
Exceeding Criteria
Fair, Poor or Severe Bioclassificatior
Meeting Criteria
Meeting Criteria
Meeting Criteria
Meeting Criteria
Exceeding Criteria
Data Inconclusive
Meeting Criteria with Statistical Con
Meeting Criteria with Statistical Con
Meeting Criteria with Statistical Con
Meeting Criteria with Statistical Con
Exceeding Criteria with Statistical Cc
Pathogen Indicator Screening Excun
7/21/2021 NC 2020 INTEGRATED REPORT Category 5 assessments approved by EPA June 23,2021
Page 1293 of 1334

MONITORING REPORT(MR) VIOLATIONS for:
Report Date: 12/03/21
Page 1 of 5
Permit: NC0085812 MRs Betweell1 - 2016 and10 - 2021 Region: %
Facility Name: % Param Name% County: %
Major Minor: %
Violation Category:%
Subbasin:%
Program Category:
Violation Action: %
PERMIT: NC0085812
FACILITY: Union County - Grassy Branch WWTP
COUNTY: Union
REGION: Mooresville
Limit Violation
MONITORING OUTFACE
REPORT
LOCATION
PARAMETER
VIOLATION UNIT OF
DATE FREQUENCY MEASURE
LIMIT
CALCULATED
VALUE
ok
Over
VIOLATION TYPE
VIOLATION ACTION
03-2018 001
03-2018 001
03-2018 001
04-2018 001
06-2018 001
12-2018 001
01-2019 001
04-2019 001
04-2019 001
04-2019 001
03-2020 001
03-2020 001
02-2018 001
02-2018 001
03-2018 001
Effluent BOD, 5-Day (20 Deg. C) - 03/17/18 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 03/31/18 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 03/31/18 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 04/14/18 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 06/02/18 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 12/22/18 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 01/12/19 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 04/06/19 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 04/13/19 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 04/30/19 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 03/28/20 Weekly
Concentration
Effluent BOD, 5-Day (20 Deg. C) - 03/31/20 Weekly
Concentration
Effluent Coliform, Fecal MF, MFC 02/03/18 Weekly
Broth, 44.5 C
Effluent Coliform, Fecal MF, MFC 02/28/18 Weekly
Broth, 44.5 C
Effluent Coliform, Fecal MF, MFC 03/03/18 Weekly
Broth, 44.5 C
mg/I
mg/I
mg/I
mg/I
mg/I
mg/I
mg/I
mg/I
mg/I
mg/I
mg/I
mg/I
#/100m1
#/100m1
#/100m1
15 27.1 80.7 Weekly Average
Exceeded
15 20.3 35.3 Weekly Average
Exceeded
10 16.3 63 Monthly Average
Exceeded
7.5 7.6 1.3 Weekly Average
Exceeded
7.5 13.2 76 Weekly Average
Exceeded
15 16.1 7.3 Weekly Average
Exceeded
15 23.3 55.3 Weekly Average
Exceeded
7.5 193 2,473.3 Weekly Average
Exceeded
7.5 14.6 94.7 Weekly Average
Exceeded
5
15
10
24.8
54.5
14.48
396
263.3
44.8
Monthly Average
Exceeded
Weekly Average
Exceeded
Monthly Average
Exceeded
400 1,500 275 Weekly Geometric Mean
Exceeded
200 220.09 10.0 Monthly Geometric Mean
Exceeded
400 6,971.37 1,642.8 Weekly Geometric Mean
Exceeded
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to NOD
Proceed to NOV
Proceed to NOV
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to NOV
Proceed to NOV
Proceed to NOV

MONITORING REPORT(MR) VIOLATIONS for:
Report Date: 12/03/21 Page 2 of 5
Permit: NC0085812 MRs Betweell1 - 2016 and10 - 2021 Region: %
Facility Name: % Param Name% County: %
Major Minor: %
Violation Category:%
Subbasin:%
Program Category:
Violation Action: %
PERMIT: NC0085812
FACILITY: Union County - Grassy Branch WWTP
COUNTY: Union
REGION: Mooresville
Limit Violation
MONITORING OUTFACE
REPORT
LOCATION
PARAMETER
VIOLATION
UNIT OF
DATE FREQUENCY MEASURE
LIMIT
CALCULATED
VALUE
Over
VIOLATION TYPE
VIOLATION ACTION
03-2018 001
06-2018 001
09-2018 001
10-2018 001
10-2018 001
10-2018 001
11-2018 001
11-2018 001
12-2018 001
12-2018 001
12-2018 001
12-2018 001
01-2019 001
03-2019 001
04-2019 001
01-2017 001
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Coliform, Fecal MF, MFC
Broth, 44.5 C
Flow, in conduit or thru 01/31/17 Continuous mgd
treatment plant
03/31/18
06/02/18
09/30/18
10/06/18
10/13/18
10/20/18
11/10/18
11/17/18
12/15/18
12/22/18
12/29/18
12/31/18
01/05/19
03/02/19
04/06/19
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
#/100m1
200 218.82 9.4 Monthly Geometric Mean
Exceeded
400 2,949.58 637.4 Weekly Geometric Mean
Exceeded
200 243.81 21.9 Monthly Geometric Mean
Exceeded
400 440 10 Weekly Geometric Mean
Exceeded
400 570 42.5 Weekly Geometric Mean
Exceeded
400 810 102.5 Weekly Geometric Mean
Exceeded
400 1,200 200 Weekly Geometric Mean
Exceeded
400 6,000 1,400 Weekly Geometric Mean
Exceeded
400 7,200 1,700 Weekly Geometric Mean
Exceeded
400 560 40 Weekly Geometric Mean
Exceeded
400 6,000 1,400 Weekly Geometric Mean
Exceeded
200 1,448.56 624.3 Monthly Geometric Mean
Exceeded
400 737 84.3 Weekly Geometric Mean
Exceeded
400 3,900 875 Weekly Geometric Mean
Exceeded
400 6,000 1,400 Weekly Geometric Mean
Exceeded
0.05 0.073 45.4
Monthly Average
Exceeded
Proceed to NOV
Proceed to NOV
No Action, BPJ
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to
Enforcement Case
No Action, BPJ

MONITORING REPORT(MR) VIOLATIONS for:
Report Date: 12/03/21
Page 3 of 5
Permit: NC0085812 MRs Betweell1 - 2016 and10 - 2021 Region: %
Facility Name: % Param Name% County: %
Major Minor: %
Violation Category:%
Subbasin:%
Program Category:
Violation Action: %
PERMIT: NC0085812
FACILITY: Union County - Grassy Branch WWTP
COUNTY: Union
REGION: Mooresville
Limit Violation
MONITORING OUTFACE
REPORT
LOCATION
PARAMETER
VIOLATION
UNIT OF
DATE FREQUENCY MEASURE
LIMIT
CALCULATED
VALUE
Over
VIOLATION TYPE
VIOLATION ACTION
05-2017 001
01-2018 001
02-2018 001
03-2018 001
09-2018 001
10-2018 001
11-2018 001
12-2018 001
01-2019 001
02-2019 001
03-2019 001
04-2019 001
12-2019 001
01-2020 001
02-2020 001
09-2020 001
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
05/31/17 Continuous
01/31/18 Continuous
02/28/18 Continuous
03/31/18 Continuous
09/30/18 Continuous
10/31/18 Continuous
11/30/18 Continuous
12/31/18 Continuous
01/31/19 Continuous
02/28/19 Continuous
03/31/19 Continuous
04/30/19 Continuous
12/31/19 Continuous
01/31/20 Continuous
02/29/20 Continuous
09/30/20 Continuous
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
mgd
0.05 0.052 3.1 Monthly Average
Exceeded
0.05 0.058 15.2 Monthly Average
Exceeded
0.05 0.07 39.5 Monthly Average
Exceeded
0.05 0.068 35.9 Monthly Average
Exceeded
0.05 0.05 0.3 Monthly Average
Exceeded
0.05 0.056 12.8 Monthly Average
Exceeded
0.05 0.088 75.3 Monthly Average
Exceeded
0.05 0.106 112.6 Monthly Average
Exceeded
0.05
0.05
0.05
0.05
0.081
0.07
0.061
0.065
62.3
40.1
21.6
29.5
Monthly Average
Exceeded
Monthly Average
Exceeded
Monthly Average
Exceeded
Monthly Average
Exceeded
0.05 0.052 3.1 Monthly Average
Exceeded
0.05 0.058 15.2 Monthly Average
Exceeded
0.05 0.062 25.0 Monthly Average
Exceeded
0.05 0.054 8.4 Monthly Average
Exceeded
No Action, BPJ
Proceed to NOV
Proceed to NOV
Proceed to NOV
No Action, BPJ
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to NOD
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to NOD

MONITORING REPORT(MR) VIOLATIONS for:
Report Date: 12/03/21 Page 4 of 5
Permit: NC0085812 MRs Betweell1 - 2016 and10 - 2021 Region: %
Facility Name: % Param Name% County: %
Major Minor: %
Violation Category:%
Subbasin:%
Program Category:
Violation Action: %
PERMIT: NC0085812
FACILITY: Union County - Grassy Branch WWTP
COUNTY: Union
REGION: Mooresville
Limit Violation
MONITORING OUTFACE
REPORT
LOCATION
PARAMETER
VIOLATION
UNIT OF
DATE FREQUENCY MEASURE
LIMIT
CALCULATED
VALUE
Over
VIOLATION TYPE
VIOLATION ACTION
10-2020 001
11-2020 001
12-2020 001
01-2021 001
02-2021 001
03-2021 001
06-2017 001
02-2018 001
12-2018 001
12-2018 001
04-2019 001
04-2019 001
12-2018 001
04-2019 001
03-2020 001
Reporting Violation
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Flow, in conduit or thru
treatment plant
Nitrogen, Ammonia Total (as
N) - Concentration
Nitrogen, Ammonia Total (as
N) - Concentration
Nitrogen, Ammonia Total (as
N) - Concentration
Nitrogen, Ammonia Total (as
N) - Concentration
Nitrogen, Ammonia Total (as
N) - Concentration
Nitrogen, Ammonia Total (as
N) - Concentration
pH
Solids, Total Suspended -
Concentration
Solids, Total Suspended -
Concentration
10/31/20 Continuous
11/30/20 Continuous
12/31/20 Continuous
01/31/21 Continuous
02/28/21 Continuous
03/31/21 Continuous
06/10/17
02/03/18
12/29/18
12/31/18
04/13/19
04/30/19
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
12/11/18 Weekly
04/06/19 Weekly
03/28/20 Weekly
mgd
mgd
mgd
mgd
mgd
mgd
mg/I
mg/I
mg/I
mg/I
mg/I
mg/I
su
mg/I
mg/I
0.05 0.06 20.3 Monthly Average
Exceeded
0.05 0.052 3.8 Monthly Average
Exceeded
0.05 0.078 55.5 Monthly Average
Exceeded
0.05
0.05
0.05
6
12
0.09
79.1
0.104 107.2
0.055
12
23
10.8
100
91.7
Monthly Average
Exceeded
Monthly Average
Exceeded
Monthly Average
Exceeded
Weekly Average
Exceeded
Weekly Average
Exceeded
12 17 41.7 Weekly Average
Exceeded
4 4.86 21.6 Monthly Average
Exceeded
6 6.05 0.8 Weekly Average
Exceeded
2 2.05 2.3 Monthly Average
Exceeded
9 9.97 10.8 Daily Maximum
Exceeded
45 177 293.3 Weekly Average
Exceeded
45 98.8 119.6 Weekly Average
Exceeded
Proceed to
Enforcement Case
Proceed to NOD
Proceed to
Enforcement Case
Proceed to NOV
Proceed to NOV
Proceed to NOD
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to NOV
Proceed to
Enforcement Case
Proceed to
Enforcement Case
Proceed to NOV
Proceed to
Enforcement Case
Proceed to
Enforcement Case

MONITORING REPORT(MR) VIOLATIONS for:
Report Date: 12/03/21 Page 5 of 5
Permit: NC0085812 MRs Betweell1 - 2016 and10 - 2021 Region: %
Facility Name: % Param Name% County: %
Major Minor: %
Violation Category:%
Subbasin:%
Program Category:
Violation Action: %
PERMIT: NC0085812
FACILITY: Union County - Grassy Branch WWTP
COUNTY: Union
REGION: Mooresville
MONITORING OUTFACE
REPORT
LOCATION
PARAMETER
VIOLATION UNIT OF
DATE FREQUENCY MEASURE
LIMIT
CALCULATED
VALUE
Over
VIOLATION TYPE VIOLATION ACTION
09-2020 001
09-2020 001
06-2021 001
06-2021 001
07-2021 001
07-2021 001
08-2021 001
08-2021 001
09-2021 001
09-2021 001
Upstream
Downstream
Downstream
Upstream
Downstream
Upstream
Downstream
Upstream
Downstream
Upstream
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
Temperature, Water Deg.
Centigrade
09/30/20 3 X week
09/30/20 3 X week
06/30/21 3 X week
06/30/21 3 X week
07/31/21 3 X week
07/31/21 3 X week
08/31/21 3 X week
08/31/21 3 X week
09/30/21 3 X week
09/30/21 3 X week
deg c
deg c
deg c
deg c
deg c
deg c
deg c
deg c
deg c
deg c
Sampling Location
Missing
Sampling Location
Missing
Sampling Location
Missing
Sampling Location
Missing
Sampling Location
Missing
Sampling Location
Missing
Sampling Location
Missing
Sampling Location
Missing
Sampling Location
Missing
Sampling Location
Missing
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error
No Action, Facility
Reporting Error

Permit Enforcement History by Permit
Case
Permit: NC0085812
Region: Mooresville
Facility: Grassy Branch VWVfP
County: Union
Owner: Union County
Penalty Remission Enforcement EMC Collection Has
Assessment Penalty Enforcement Request Conference Hearing Memo Sent Payment Case
Approved Amount Costs Damages Received Held Held To AGO Total Paid Balance Due Plan Closed
LM-1999-0006 01/22/99 $3,800.00 $78.14 02/18/99 03/31/99
$3,078.14
$0.00 No 06/24/99
LV-1999-0068 02/12/99 $2,500.00 $68.56 03/16/99 05/26/99
$2,568.56
$0.00 No 06/24/99
LV-1999-0106 03/19/99 $2,000.00 $69.07 04/14/99 05/26/99
$2,069.07
$0.00 No 06/24/99
LV-1999-0195 05/14/99 $1,250.00 $68.56
$1,318.56
$0.00 No 06/24/99
LV-1999-0198 05/21/99 $1,000.00 $68.56
$1,068.56
$0.00 No 06/24/99
LV-1999-0356 09/10/99 $3,125.00 $73.50
$3,198.50
$0.00 No 10/13/99
LV-2004-0543 10/27/04 $100.00 $85.04
$185.04
$0.00 No 11/23/04
LV-2004-0556 11/08/04 $100.00 $85.04
$185.04
$0.00 No 11/29/04
LV-2008-0345 09/09/08 $100.00
$90.40 $190.40 $0.00 No 10/02/08
LV-2009-0302 08/25/09 $100.00 $85.30
$185.30
$0.00 No 09/22/09
LV-2014-0021 02/27/14 $100.00
$149.22 $249.22 $0.00 No 04/07/14
LV-2015-0208 09/18/15 $450.00 $146.97
$596.97
$0.00 No 10/20/15
LV-2016-0049 02/02/16 $350.00 $100.53 03/23/16 05/03/16
$450.53
$0.00 No 07/05/16
LV-2016-0083 04/05/16 $200.00 $100.53 04/25/16 06/07/16
$300.53
$0.00 No 07/26/16
LV-2016-0114 06/24/16 $800.00 $100.33
$900.33
$0.00 No 07/26/16
LV-2016-0157 08/03/16 $200.00 $100.53
$300.53
$0.00 No 09/13/16
LV-2016-0213 10/26/16 $125.00
$101.34 03/01/17 $226.34 $0.00 No 08/02/17
LV-2019-0074 04/10/19 $450.00 $115.76
$558.75
$0.00 No
LV-2020-0100 03/04/20 $250.00 $115.76
$115.76
$0.00 No 11/17/21

Case
Penalty Remission Enforcement EMC Collection Has
Assessment Penalty Enforcement Request Conference Hearing Memo Sent Payment Case
Approved Amount Costs Damages Received Held Held To AGO Total Paid Balance Due Plan Closed
LV-2 02 0- 0101 03/04/20
$350.00 $115.76
$115.76
$0.00 No 11/17/21
LV-2020-0102 03/04/20
$900.00 $115.76
$115.76
$0.00 No 11/17/21
LV-2021-0088 04/01/21
$250.00 $120.32
$120.32
$0.00 No 11/17/21
LV-2021-0089 04/01/21
$250.00 $120.32
$120.32
$0.00 No 11/17/21
LV-2021-0091 04/01/21
$250.00 $120.32
$120.32
$0.00 No 11/17/21
LV-2021-0092 04/01/21
$450.00 $120.32
$120.32
$0.00 No 11/17/21
LV-2021-0090 04/13/21
$250.00 $120.32
$120.32
$0.00 No 11/17/21
Total Cases: 26 $19,700.00 $2,636.26
Total Penalties: $22,336.26
Total Penalties after
$18,579.25 $0.00
$18,579.25

United States Environmental Protection Agency
E PA Washington, D.C. 20460
Water Compliance Inspection Report
Form Approved.
OMB No. 2040-0057
Approval expires 8-31-98
Section A: National Data System Coding (i.e., PCS)
Transaction Code NPDES yr/mo/day Inspection
1 IN 2 I5 �-I 3 I NC0085812 111 121 19/04/03 117
Type
18 [ i
i i i l l
Inspector Fac Type
19 i G I 201
2111111 1i i l l lil i i i I I i i i l l l i i l i l i
iii
i i i i i 166
Inspection Work Days Facility Self -Monitoring Evaluation Rating B1 QA Reserved
671I 70I2 I 711I 72 I N I 73I I 174
L� 1 751
I I I I I I 180
Section B: Facility Data
Name and Location of Facility Inspected (For Industrial Users discharging to POTW, also include
POTW name and NPDES permit Number)
Grassy Branch WWTP
Old Fish Rd
Monroe NC 28111
Entry Time/Date
11:51AM 19/04/03
Permit Effective Date
18/11/01
Exit Time/Date
12:39PM 19/04/03
Permit Expiration Date
23/10/31
Name(s) of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s)
///
Danny L Smith/ORC//
Other Facility Data
Name, Address of Responsible Official/Title/Phone and Fax Number
Contacted
Bart Farmer,4600 Goldmine Rd Monroe NC 28110//704-296-4227/7042897395
No
Section C: Areas Evaluated During Inspection (Check only those areas evaluated)
Permit Flow Measurement Operations & Maintenar Records/Reports
Self -Monitoring Progran Sludge Handling Dispos Facility Site Review Effluent/Receiving Wate
Laboratory
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
(See attachment summary)
Name(s) and Signature(s) of Inspector(s) Agency/Office/Phone and Fax Numbers Date
Roberto Scheller DWR/MRO WQ/707-235-2204/
Signature of Management Q A Reviewer Agency/Office/Phone and Fax Numbers Date
W. Corey Basinger DWR/Division of Water Quality/704-235-2194/
EPA Form 3560-3 (Rev 9-94) Previous editions are obsolete.
Page# 1

31
NPDES
NC0085812
yr/mo/day
I11 121 19/04/03
117
Inspection Type
18 [j
(Cont.)
1
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
Review of compliance history was conducted for the review period of February 2018 through January
2019.
During the compliance review the following violations were issued:
02/2018 N OV-2018-LV-0519
03/2018 NOV-2018-LV-0604
04/2018 N OV-2018-LV-0105
06/2018 NOV-2018-LV-0668
10/2018 NOV-2018-LV-0857
11/2018 NOV-2018-LV-0022
12/2018 N OV-2019-LV-0104
01/2019 NOV-2019-LV-0184
During the review period 6 Monthly Average Flow limit violations were issued. Review of Flow history
indicates that approximately 66% of Monthly Average Flows, during review period, were greater than
or equal to 80% of Permitted Monthly Average Flow. Review of reported limits violations indicate an
issue with I&I that is affecting proper treatment of wastewater.
Please be advised that in accordance with your NPDES Permit (NC0085812) Part II, Section C, (2.)
"The Permittee shall at all times properly operate and maintain all facilities and systems of treatment
and control (and related appurtenances) which are installed or used by the Permittee to achieve
compliance with conditions of this permit." Also in accordance with Part II, Section B, (1.) Duty to
Comply, "The Permittee must comply with all conditions of this permit. Any permit noncompliance
constitutes a violation of the CWA and is grounds for enforcement actions;"
Page# 2

Permit: NC0085812
Inspection Date: 04/03/2019
Owner - Facility: Grassy Branch VVVVTP
Inspection Type: Compliance Evaluation
Permit Yes No NA NE
(If the present permit expires in 6 months or less). Has the permittee submitted a new ❑ ❑ • ❑
application?
Is the facility as described in the permit? • ❑ ❑ ❑
# Are there any special conditions for the permit? • ❑ ❑ ❑
Is access to the plant site restricted to the general public? • ❑ ❑ ❑
Is the inspector granted access to all areas for inspection? • ❑ ❑ ❑
Comment: The current permit was issued on November 1, 2018 and expires on October 31, 2023
Record Keeping
Are records kept and maintained as required by the permit?
Is all required information readily available, complete and current?
Are all records maintained for 3 years (lab. reg. required 5 years)?
Are analytical results consistent with data reported on DMRs?
Is the chain -of -custody complete?
Dates, times and location of sampling
Name of individual performing the sampling
Results of analysis and calibration
Dates of analysis
Name of person performing analyses
Transported COCs
Are DMRs complete: do they include all permit parameters?
Has the facility submitted its annual compliance report to users and DWQ?
(If the facility is = or > 5 MGD permitted flow) Do they operate 24/7 with a certified
operator on each shift?
Is the ORC visitation log available and current?
Is the ORC certified at grade equal to or higher than the facility classification?
Is the backup operator certified at one grade less or greater than the facility
classification?
Is a copy of the current NPDES permit available on site?
Facility has copy of previous year's Annual Report on file for review?
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
•
•
•
• ❑ ❑ ❑
• ❑ ❑ ❑
❑ ❑ • ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ •
Comment: Records reviewed are kept at Crooked Creek WWTP and were readily available for
inspection..
Operations & Maintenance Yes No NA NE
Page# 3

Permit: NC0085812
Inspection Date: 04/03/2019
Owner - Facility: Grassy Branch VVVVTP
Inspection Type: Compliance Evaluation
Operations & Maintenance Yes No NA NE
Is the plant generally clean with acceptable housekeeping? • ❑ ❑ ❑
Does the facility analyze process control parameters, for ex: MLSS, MCRT, Settleable • ❑ ❑ ❑
Solids, pH, DO, Sludge Judge, and other that are applicable?
Comment: At time of inspection treatment facility appeared to be well maintained and operated.
Bar Screens
Type of bar screen
a.Manual
b.Mechanical
Are the bars adequately screening debris?
Is the screen free of excessive debris?
Is disposal of screening in compliance?
Is the unit in good condition?
Comment: Debris is disposed of in dumpster at Crooked Creek WWTP.
Chemical Feed
Is containment adequate?
Is storage adequate?
Are backup pumps available?
Is the site free of excessive leaking?
Comment: Liquid lime is added for supplemental alkalinity.
Equalization Basins
Is the basin aerated?
Is the basin free of bypass lines or structures to the natural environment?
Is the basin free of excessive grease?
Are all pumps present?
Are all pumps operable?
Are float controls operable?
Are audible and visual alarms operable?
# Is basin size/volume adequate?
Yes No NA NE
•
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
❑ ❑ • ❑
❑ ❑ ❑ •
Page# 4

Permit: NC0085812
Inspection Date: 04/03/2019
Owner - Facility: Grassy Branch VVVVTP
Inspection Type: Compliance Evaluation
Equalization Basins
Comment:
Yes No NA NE
Review of DMR's for 12 month period February 2018 through January 2019 recorded 6
Monthly Average Flow violations. It was noted that aproximately 66% of Monthly
Average Flows, during review period, were equal to or greater that 80% of permitted
flow of 0.050 MGD.
Influent Sampling
# Is composite sampling flow proportional?
Is sample collected above side streams?
Is proper volume collected?
Is the tubing clean?
# Is proper temperature set for sample storage (kept at less than or equal to 6.0
degrees Celsius)?
Is sampling performed according to the permit?
Comment:
Aerobic Digester
Is the capacity adequate?
Is the mixing adequate?
Is the site free of excessive foaming in the tank?
# Is the odor acceptable?
# Is tankage available for properly waste sludge?
Comment: Sludge is thickened and removed for disposal at Crooked Creek WWTP.
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ •
• ❑ ❑ ❑
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
Aeration Basins Yes No NA NE
Mode of operation Ext. Air
Type of aeration system Diffused
Is the basin free of dead spots? • ❑ ❑ ❑
Are surface aerators and mixers operational? ❑ ❑ • ❑
Are the diffusers operational? • ❑ ❑ ❑
Is the foam the proper color for the treatment process? • ❑ ❑ ❑
Does the foam cover less than 25% of the basin's surface? • ❑ ❑ ❑
Is the DO level acceptable? ❑ ❑ ❑ •
Is the DO level acceptable?(1.0 to 3.0 mg/I) ❑ ❑ ❑ •
Comment: Aeration basin appeared to be well mixed and had good color.
Page# 5

Permit: NC0085812
Inspection Date: 04/03/2019
Owner - Facility: Grassy Branch VVVVTP
Inspection Type: Compliance Evaluation
Secondary Clarifier
Is the clarifier free of black and odorous wastewater?
Is the site free of excessive buildup of solids in center well of circular clarifier?
Are weirs level?
Is the site free of weir blockage?
Is the site free of evidence of short-circuiting?
Is scum removal adequate?
Is the site free of excessive floating sludge?
Is the drive unit operational?
Is the return rate acceptable (low turbulence)?
Is the overflow clear of excessive solids/pin floc?
Is the sludge blanket level acceptable? (Approximately'/4 of the sidewall depth)
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
❑ ❑ ❑ •
Comment. At time of inspection secondary effluent was clear with no visible suspended solids.
Filtration (High Rate Tertiary)
Type of operation:
Is the filter media present?
Is the filter surface free of clogging?
Is the filter free of growth?
Is the air scour operational?
Is the scouring acceptable?
Is the clear well free of excessive solids and filter media?
Comment: At time of inspection filters were not in use.
Disinfection - UV
Are extra UV bulbs available on site?
Are UV bulbs clean?
Is UV intensity adequate?
Is transmittance at or above designed level?
Is there a backup system on site?
Is effluent clear and free of solids?
Yes No NA NE
Down flow
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
❑ ❑ ❑ •
❑ ❑ ❑ •
• ❑ ❑ ❑
Yes No NA NE
• ❑ ❑ ❑
❑ ❑ ❑ •
❑ ❑ ❑ •
❑ ❑ ❑ •
• ❑ ❑ ❑
• ❑ ❑ ❑
Comment:
Flow Measurement - Effluent Yes No NA NE
Page# 6

Permit: NC0085812
Inspection Date: 04/03/2019
Owner - Facility: Grassy Branch VVVVTP
Inspection Type: Compliance Evaluation
Flow Measurement - Effluent
# Is flow meter used for reporting?
Is flow meter calibrated annually?
Is the flow meter operational?
(If units are separated) Does the chart recorder match the flow meter?
Comment: Flow meter was last calibrated on 2/27/2019.
Effluent Sampling
Is composite sampling flow proportional?
Is sample collected below all treatment units?
Is proper volume collected?
Is the tubing clean?
# Is proper temperature set for sample storage (kept at less than or equal to 6.0
degrees Celsius)?
Is the facility sampling performed as required by the permit (frequency, sampling type
representative)?
Comment: At time of inspection effluent sampler was recorded at 2.8 degrees Celsius.
Effluent Pipe
Is right of way to the outfall properly maintained?
Are the receiving water free of foam other than trace amounts and other debris?
If effluent (diffuser pipes are required) are they operating properly?
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
Comment: Effluent at point of discharge was clear with no visible suspended solids. There was no
foam or floating debris at discharge point into Crooked Creek.
Page# 7

United States Environmental Protection Agency
E PA Washington, D.C. 20460
Water Compliance Inspection Report
Form Approved.
OMB No. 2040-0057
Approval expires 8-31-98
Section A: National Data System Coding (i.e., PCS)
Transaction Code NPDES yr/mo/day Inspection
1 ICI J 2 IS I 31 NC0085812 I11 121 20/07/07 117
Type
18 [ I
I I I I I
Inspector Fac Type
19 G I 201
211 1 1 1 I I I I I I I I I I I I I I I I I I I I I I I I I
I I I
I I I 1 I 166
Inspection Work Days Facility Self -Monitoring Evaluation Rating B1 QA Reserved
671 171172 I N I 73I I 174
7° 13 1
1L� 1 751
180
111111
Section B: Facility Data
Name and Location of Facility Inspected (For Industrial Users discharging to POTW, also include
POTW name and NPDES permit Number)
Grassy Branch WWTP
Old Fish Rd
Monroe NC 28111
Entry Time/Date
10:OOAM 20/07/07
Permit Effective Date
18/11/01
Exit Time/Date
01:30PM 20/07/07
Permit Expiration Date
23/10/31
Name(s) of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s)
///
Rick Mareth/ORC/704-918-9678/
Other Facility Data
Name, Address of Responsible Official/Title/Phone and Fax Number
Contacted
Bart Farmer,4600 Goldmine Rd Monroe NC 28110//704-296-4227/7042897395
No
Section C: Areas Evaluated During Inspection (Check only those areas evaluated)
Permit Operations & Maintenar Facility Site Review Effluent/Receiving Wate
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
(See attachment summary)
Name(s) and Signature(s) of Inspector(s) Agency/Office/Phone and Fax Numbers Date
Tony Parker DWR/MRO WQ/704-663-1699/
Roberto Scheller DWR/MRO WQ/707-235-2204/
Signature of Management Q A Reviewer Agency/Office/Phone and Fax Numbers Date
EPA Form 3560-3 (Rev 9-94) Previous editions are obsolete.
Page# 1

31
NPDES yr/mo/day
NC0085812 I11 121 20/07/07
117
Inspection Type
18 [j
(Cont.)
1
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
On July 7, 2020 a reconnaissance inspection was conducted of V V TP and collection system by
Roberto Scheller and Tony Parker of the Mooresville Regional Office. At time of inspection effluent
flow was very low. Effluent was clear with no visible suspended solids. Treatment facility appeared in
good operating condition. Review of collection system found only minor issues. Randon inspection of
manholes did not find any notable entry points of I&I. Pump stations were reviewed as part of the
collection system.
The reconnaissance inspection was conducted in relations to SOC application. Currently the SOC is
in Draft form and being reviewed.
Page# 2

Permit: NC0085812
Inspection Date: 07/07/2020
Owner - Facility: Grassy Branch VVVVTP
Inspection Type: Reconnaissance
Permit Yes No NA NE
(If the present permit expires in 6 months or less). Has the permittee submitted a new ❑ ❑ • ❑
application?
Is the facility as described in the permit? • ❑ ❑ ❑
# Are there any special conditions for the permit? • ❑ ❑ ❑
Is access to the plant site restricted to the general public? • ❑ ❑ ❑
Is the inspector granted access to all areas for inspection? • ❑ ❑ ❑
Comment: Permit is for a 0.05 MGD WWTP issued on November 1, 2018 and expires on October
31, 2023.
Operations & Maintenance Yes No NA NE
Is the plant generally clean with acceptable housekeeping? • ❑ ❑ ❑
Does the facility analyze process control parameters, for ex: MLSS, MCRT, Settleable • ❑ ❑ ❑
Solids, pH, DO, Sludge Judge, and other that are applicable?
Comment: Treatment facility appeared to be in good operational condition. Tis facility has issues
with I&I.
Page# 3

NPDES WASTE LOAD ALLOCATION
PERMIT NO.: NC0085812
PERMI'ITEE NAME: Union County Public Works Department
FACILITY NAME: Grassy Branch Treatment Plant
Facility Status: Proposed
Permit Status: New
Major Minor '1
Pipe No.: 001
Design Capacity: __0 2-MMEi3— ..<2, 7. / 1 r See
Domestic (% of Flow): 1.00 % -rt `
Industrial (% of Flow):
77
Dc;t S-; > 7 / 7a .4
pec
Comments:
This is a proposed facility that will be taking the flow from three
schools and effectively eliminating the said three discharges.
RECEIVING STREAM:Crookcd Creek
Class: B
Sub -Basin: 03-07-12
Reference USGS Quad: G17NW
County: Union
Regional Office: Mooresville Regional Office
(please attach)
Previous Exp. Date: 00/00/00 Treatment Plant Class:
Classification changes within three miles:
Requested by:
Prepared by: ;
Reviewed by:
Mark McIntire
4?< /
✓i
Date: 5/10/96
Date: //// / 2
Date: ?4 // &
J`
Modeler
Date Re::.
#
Drainage Area (mi2
) j j , i Avg. Strearnflow (cfs):
7Q10 0
Q (cfs) Winter 7Q l0 (cfs) J , ‘-/ 30Q2 (cfs) 0, (,
Toxicity Limits: IWC % Acute/Chronic
Instream Monitoring:
r T ,ISTREAM MONITORING REQUIREMENTS
iq:. •: Upstream Location: 50 feet upstream of outfall
Downstream Location: NC 218 bridge approx. 0.3 mi downstream of outfall
Parameters: temp, DO, fecal, conductivity
Eff. Special instream monitc ring locations or monitoring frequencies:
Ch
Wasteflow (MG11):
BODS (mg/1):
NH3N (mg/1):
DO (mg/1):
TSS (mg/1):
Fecal Col. (/100 ml):
pH (SU):
Residual Chlorine (t .g/1):
Monthly Average
Summer Winter
0.02 0.02
5.0 10.0 -
2.0 4.0
6.0 6.0
30.0 30.0
200 200
6-9 6-9
17 17
Comments:
a

Facility Name:
NPDES No.:
Type of Waste:
Facility Status:
Permit Status:
Receiving Stream:
Stream Classification:
Subbasin:
County:
Regional Office:
Requester:
Date of Request:
Topo Quad:
FACT SHEET FOR WAS I ELOAD ALLOCATION
Grassy Branch Treatment Plant
NC0085812
Domestic - 100%
Proposed
New
Crooked Creek
B
03-07-12
Union
Mooresville
Mark McIntire
5/10/96
G17NW
Request # 8487
3k.N ;_.0 1996
Stream C iaraateristi:t;• ?.
r
USGS #
Date:
Drainage Area (mi2):
Summer 7Q10 (cfs):
V�'nttet 7Q1u (cfs).
Average Flow (cfs):
30Q2 (cfs):
IWC (%):
see,below *
43:9r
0
!1 A .."
0.6
100%
Wasteload Allocation Summary
(approach taken, correspondence with region, EPA, etc.)
* Flow estimates for Crooked Creek at the outfall are based in part on data collected at a USGS
low flow partial record station (02.1247.6600) located approximately 4.3 miles upstream of the
proposed discharge.
This WLA is for a wasteflow of 0.02 MGD.
Unionville Elementary (NC0030562), Piedmont Middle (NC0028525) and High Schools
(NC0030635) currently discharge to zero flow streams. As part of an SOC compliance schedule, a
new WWTP will be installed which will combine the flows from the three schools and relocate the
discharge to Crooked Creek. The new plant should provide significantly better treatment than the
three individual plants and enable the schools to get off the SOC. On October 30, 1995 the
consulting engineer for the county requested speculative limits for a waste flow of 0.02 MGD.
The consulting engineer provided flow data from the three schools to support the request for a
waste flow of 0.02 MGD. Union County has since applied for a permit for 0.2 MGD for the
proposed Grassy Branch Treatment Plant. When inquiring about the flow discrepancy, Mark
McIntire was told by the consulting engineers that the additional flow was needed to provide
service for the anticipated growth in the number of residential customers near the schools. In
March 1996 the County submitted a sewer system master plan to the Division for review. The plan
was reviewed for references to the County's plan for expanding the proposed Grassy Branch
WWTP beyond the 0.02 MGD capacity needed to get the schools off the SOC. Attached is a
correspondence from Andy McDaniel to Don Safrit outlining the findings of this review. In order
to encourage Union County to continue its long range planning for regional sewer service to its
customers a permit limit for 0.02 MGD is recommended.
Since the summer 7Q10 flow in Crooked Creek is estimated to be 0 cfs a modeling analysis
can not be done to quantify the instream impacts of the proposed discharge. As a result, instream
monitoring is recommended.

2
The facility should be requested to send in a copy of a 7.5 minute USGS topo map with the exact
discharge location marked. The large scale map supplied with the permit application is hard to read
and an accurate lat/long measurement for the GIS coverage would be difficult to obtain.
Special Schedule Requirements and additional comments from Reviewers:
�fjs fl�1D�+,+IT� 77I f� �E�it1i r bt nl/612 Gf�L/1 G�! 4,.hiG�T L <5/i/y'/di /%_
/ Gk'/P 1 CD,i,ory CA-rf s efv L' r A -1,opu of d • 2- /Imo l vs,/ 1.1_- 7-+c1//97 1,
i% /�� ///�% / //?�'
Recommended by: (/�,.,,, ,.,� ,�,- � ,CG,�,� � , �, Date: - , (', (,
Reviewed by
Instream Assessment: �C�1Y.6(J aGl/bL, Date: 01 %/6/
Regional Supervisor/7G- �-- '-� <.= '��"1/.1`''� Date: ‘M 0 '6j
Permits & Engineering: ?)-14;7, . (_.h —, Date: b
RETURN TO TECHNICAL SUPPORT BY: ,J U _ 0 6 1996
;1/46-(yrbg vF 0,,0)&0. G��)7z0. A/fAimlikE 2 FiiUr+z6
pi; , C44s,lo,NS VI5 - ��

3
Recommended Limits:
Wasteflow (MGD):
BOD5 (mg/1):
NH3N (mg/1):
DO (mg/1):
TSS (mg/1):
Fecal Col. (/100 mi):
pH (SU):
Residual Chlorine (14/1):
CONVENTIONAL PARAME 1'ERS
Monthly Average
Summer Winter
0.02 0.02
5.0 10.0
2.0 4.0
6.0 6.0
30.0 30.0
200 200
6-9 6-9
17 17 WQ
WQ or EL
WQ
WQ
WQ
Parameter(s) are water quality limited. For some parameters, the available load capacity of
the immediate receiving water will be consumed. This may affect future water quality based
effluent limitations for additional dischargers within this portion of the watershed.
OR
No parameters are water quality limited, but this discharge may affect future allocations.
INSTREAM MONITORING REQUIREMENTS
Upstream Location: 50 feet upstream of outfall
Downstream Location: NC 218 bridge approx. 0.3 mi downstream of outfall
Parameters: temp, DO, fecal, conductivity
Special instream monitoring locations or monitoring frequencies:
MISCELLANEOUS INFORMATION & SPECIAL CONDITIONS
Special Instructions or Conditions
Wasteload sent to EPA? (Major) (Y or N)
(If yes, then attach schematic, toxics spreadsheet, copy of model, or, if not modeled, then old
assumptions that were made, and description of how it fits into basinwide plan)
Additional Information attached? (Y or N) If yes, explain with attachments.

Page 1
Note for Andy McDanjel
From: Don Safrit
Date: Thu, Jun 6, 1996 8:43 AM
Subject: RE: Unionville and Piedmont Schools
To: Andy McDaniel
cc: Carla Sanderson; Dave Goodrich; Mark McIntire
Say no to 0.2 mgd - only 0.02 mgd to cover the schools.
Thanks, Don
From: Andy McDaniel on Wed, Jun 5, 1996 6:23 PM
Subject: Unionville and Piedmont Schools
To: Don Safrit
Cc: Carla Sanderson; Dave Goodrich; Mark McIntire
Don,
At your request I've reviewed the Union Co. master sewer plan for references to the
County's plans for expanding the proposed Grassy Branch WWTP (NC0085812) beyond
the 0.02 MGD capacity need to get the schools off an SOC. Recall that Union Co. has
applied for a permit for 0.2 MGD as opposed to a flow of 0.02 MGD which we gave
speculative limits for on January 30, 1996. Below are my findings from the master sewer
plan:
1. On p. 23 the plan recommends construction of a new regional WWTP on the Rocky
River. The plan recommends that design and construction should begin immediately "to
minimize the proliferation of small package plants...". Unionville and Piedmont Middle and
HS would be included in a future service area as outlined in Figure 4.
2. On p. 25 Table 8 outlines Piedmont HS/Unionville WWTP as an immediate priority for
improvements (presumably because the schools are currently under an SOC). A design
capacity of 0.06 MGD is listed along with 8" sewer lines.
3. The western portion of Union Co. is forceasted to have the highest population growth due
to the proximity to Charlotte. Figure 7 illustrates the proposed sewer lines for the Greater
Goose Creek basin which includes service to the Unionville area and Piedmont Middle and
High Schools. The plan recommends construction of the proposed sewer lines to begin
immediately in the western part of the basin and be phased roughly the further east you go.
A sewer line and pump station connecting Unionville and Piedmont Middle and HS to the
proposed Rocky River regional WWTP is scheduled to go into service in the year 2015.
After reviewing the sewer system master plan my recommendations for a management
strategy in this case would be to permit the proposed Grassy Branch WWTP for 0.02 MGD.
This would allow for adequate service to the three schools and improved treatment as stated
in the letter to you from Dale Stewart requesting speculative limits (Oct. 30, 1995). Mark
McIntire was told by the consulting engineer that the 0.2 MGD flow is needed as a result of
updated population growth estimates for the area. The additional flow would be used to
provide service to residential customers. I feel that updated growth estimates should be
addressed in an addendum or revision to the sewer master plan in order to encourage the

Page 2
County to continue its planning efforts. The master plan submitted for our review does not
address the use of package plants as an interim wastewater treatment solution until connection
to the proposed regional plant is available. In addition, a 0.2 MGD discharge is more likely
to have an impact to the recieving stream, Crooked Ck. However, since Crooked Ck. is
estimated to have a S7Q10=0 cfs flow I can not quality this impact using our current models.
Please let me know your thoughts on the matter so I can process this WLA.

AFFP
Public Notice North Carolina
Affidavit of Publication
STATE OF NC }
COUNTY OF } (,(nior
SS
Kimberly Cook, being duly sworn, says:
That she is Billing Clerk of the The Enquirer Journal, a
daily newspaper of general circulation, printed and
published in Monroe, County, NC; that the publication, a
copy of which is attached hereto, was published in the
said newspaper on the following dates:
January 15, 2022
That said newspaper was regularly issued and circulated
on those dates.
SIGNED:
(20„-k
Billing CI rk
Subscribed to and sworn to me this 15th day of January
2022.
Barbara M Daniels, Notary, Guilford , County, NC
My commission expires: February 01, 2022
70047122 70266897
(EJ) Wren Thedford
Division of Water Resou"r
1617 Mail Service Center,"
Eti‘ oTAR
y•
�eli e: kt1 i,4 S4
Raleigh, NC 27699
Public Notice
North Carolina
Environmental Management
CommissioniNPDES Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
Notice of Intent to Issue a
NPDES Wastewater Permit
NC0085812 Grassy Branch
WWTP
The North Carolina Environ-
mental Management Commis-
sion proposes to issue a NP-
DES wastewater discharge per-
mit to the person(s) listed be-
low. Written comments regard-
ing the proposed permit will be
accepted until 30 days after the
publish date of this notice, The
Director of the NC Division of
Water Resources (DWR) may
hold a public hearing should
there be a significant degree of
public interest, Please mail
comments and/or information
requests to DWR at the above
address. Interested persons
may visit the DWR at 512 N.
Salisbury Street, Raleigh, NC
27604 to review information on
file. Additional information on
NPDES permits and this notice
may be found on our website:
http://deq.nc.gov/about/divi-
sons./water-resources/water-re
sources-permits/wastewater-
branch/npdes-wastewater/pub,-
lic-notices,or by calling (919)
707-3601. Union County Public
Works (500 N Main St, Ste 918,
Monroe, NC 28112) has re-
quested modification of permit
NC0085812 for their Grassy
Branch WWTP in Union
County. This permitted facility
discharges treated domestic
wastewater to Crooked Creek.
class C waters in the Yadkin-
Pee Dee River Basin. Some of
the parameters in the permit
are water quality limited. This
discharge may affect future al-
locations in this segment of
Crooked Creek.
Jan. 15. 2022

3/1/22, 3:13 PM Mail - Denard, Derek - Outlook
RE: Peer Review NC0058512
Phillips, Emily <[e-mail]>
Tue 1/11/2022 9:46 AM
To: Denard, Derek <[e-mail]>
Looks good, Derek.
Hope you and your family are doing well and staying safe!
Emily
From: Denard, Derek <[e-mail]>
Sent: Monday, January 10, 2022 12:55 PM
To: Phillips, Emily <[e-mail]>
Subject: Peer Review NC0058512
Emily,
Please find the attached peer review. The factsheet was too big to email. Here is a link to the file: El4 Peer Review
Hope you are having a happy New Year!
Thanks,
Derek
Derek Denard
Environmental Specialist
N.C. Division of Water Resources
N.C. Department of Environmental Quality
919 707 3618 office
919 707 9000 main DWR
[e-mail]
1617 Mail Service Center
Raleigh, NC 27699-1617
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.
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3/1/22, 3:17 PM Mail - Denard, Derek - Outlook
Re: [External] RE: Modification - Draft NPDES Permit NC0085812 - Union County Public
Works - Grassy Branch WRF
Denard, Derek <[e-mail]>
1/13/2022 2:09 PM
To: Andy Neff <[e-mail]>
Cc: Basinger, Corey <[e-mail]>; Scheller, Roberto <[e-mail]>; Mark Watson
<[e-mail]>; Bart Farmer <[e-mail]>; Hyong Yi
<[e-mail]>; Shutak, John <[e-mail]>; 'Sadler, Mary'
<[e-mail]>; Struve, James N. <[e-mail]>; Jacob Allen
<[e-mail]>; Benjamin Isley <[e-mail]>; Alex Laytham
<[e-mail]>
Andy,
Thanks for the comments. I will make these corrections and adjustments for the final draft.
Thanks,
Derek Denard
Environmental Specialist
N.C. Division of Water Resources
N.C. Department of Environmental Quality
919 707 3618 office
919 707 9000 main DWR
[e-mail]
1617 Mail Service Center
Raleigh, NC 27699-1617
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.
From: Andy Neff <[e-mail]>
Sent: Thursday, January 13, 2022 12:42 PM
To: Denard, Derek <[e-mail]>
Cc: Basinger, Corey <[e-mail]>; Scheller, Roberto <[e-mail]>; Vander
Borgh, Mark <[e-mail]>; Kinney, Maureen <[e-mail]>; Mark Watson
<[e-mail]>; Bart Farmer <[e-mail]>; Hyong Yi
<[e-mail]>; Shutak, John <[e-mail]>; 'Sadler, Mary'
<[e-mail]>; Struve, James N. <[e-mail]>; Jacob Allen
<[e-mail]>; Benjamin Isley <[e-mail]>; Alex Laytham
<Alex. Laytham @ u nioncou ntync.gov>
https://outlook.office365.com/mail/id/AAQkADdhYTVmZDBILTESZDctNGI5MCO4ZjliLWU4MjVhZTBhMmJkMgAQAModU9z1r41 JtX3QRWusNki%3D 1/3

3/1/22, 3:17 PM Mail - Denard, Derek - Outlook
Subject: [External] RE: Modification - Draft NPDES Permit NC0085812 - Union County Public Works - Grassy
Branch WRF
CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment
to Report Spam.
Derek,
We have a couple of comments on the draft major permit modification for Grassy Branch WRF.
To be more accurate in the facility descriptions, we have made comments on the EQ basin(s) indicating there's
one (1) in place currently and two (2) will be in place when the new treatment train is added and also request the
sand filters be eliminated from the planned work for the 120,000 gpd capacity increase. The sand filters can be
deleted since the intent is to use a disc filter system (already noted). These changes are noted in the attachment.
On the last page, the outfall location in the aerial photo inset needs to be moved to the correct location. The
Outfall location on the top left picture of the map puts it in the tiny creek in the field and not in Crooked Creek.
Thanks for the opportunity to review the document.
Andy
Andrew Neff, P.E.
Water & Wastewater Division Director
T 704-296-4215
[e-mail]
www.unioncountync.gov
E-mail correspondence to and from this sender may be subject to the North Carolina
Public Records law and may be disclosed to third parties. If you are not the intended
recipient of this e-mail, please contact the sender immediately.
From: Denard, Derek [mailto:[e-mail]]
Sent: Tuesday, January 11, 2022 1:13 PM
To: Mark Watson; Andy Neff; Bart Farmer
Cc: Basinger, Corey; Scheller, Roberto; Vander Borgh, Mark; Kinney, Maureen
Subject: Modification - Draft NPDES Permit NC0085812 - Union County Public Works - Grassy Branch WRF
WARNING: This email originated from outside of Union County Government, be cautious when clicking
on links or opening attachments.
Mr. Neff,
Please find the attached draft NPDES Permit NC0085812 for Union County Public Works - Grassy Branch
WRF. The permit is being modified for flow expansion from 0.050 MGD to 0.120 MGD.
In order to provide more convenience, control, and security to our permittees and assist them in
processing their transactions, the Division of Water Resources is currently transitioning towards
electronic correspondence. This will hopefully provide more efficient service to our permittees and other
partners and will allow us to more effectively process and track documents. We are writing to ask you
https://outlook.office365.com/mail/id/AAQkADdhYTVmZDBILTE5ZDctNGI5MCO4ZjliLWU4MjVhZTBhMmJkMgAQAModU9z1r41 JtX3QRWusNki%3D 2/3

3/1/22, 3:17 PM Mail - Denard, Derek - Outlook
for your approval of the transmittal of documents related to your permitting and related activities with
the Division in an electronic format. Documents will be emailed to the appropriate contact person(s) in
your organization in a PDF format.
Please respond to me through email with verification that transmittal of your documents in an
electronic manner is acceptable to you.
Please respond to this email confirming that you received the attached document(s), were able to
open and view the document(s) and have saved/printed a copy for your records.
If you have any questions, please feel free to contact me.
Sincerely,
Derek Denard
Environmental Specialist
N.C. Division of Water Resources
N.C. Department of Environmental Quality
919 707 3618 office
919 707 9000 main DWR
[e-mail]
1617 Mail Service Center
Raleigh, NC 27699-1617
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.
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ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
S. DANIEL SMITH NORTH CAROLINA
Director Environmental Quality
January 11, 2022
Mark Watson, County Manager
Union County Public Works
500 N Main St, Ste 918
Monroe, NC 28112
Subject: Draft NPDES Permit NC0085812
Grassy Branch WRF
Grade II Biological WPCS
Union County
Dear Mr. Neff:
The Division has reviewed your request to modify the subject permit. Please review this draft carefully
to ensure a thorough understanding of the information, conditions, and requirements it contains.
The draft permit includes the following significant changes from the existing permit:
• The permit was modified for flow expansion from 0.050 MGD to 0.120 MGD. A second effluent
table is included for the flow modification. See Condition A. (2.).
• The limit for dissolved oxygen is changed to Daily Average > 6.0 mg/L. See Conditions A. (1.)
and (2.). This change is in accordance with flow design criteria for new and expanding
discharges to zero flow streams (7Q10 = 0 and 30Q2 > 0) [15A NCAC 02B .0206]. The original
wasteload allocation in 1996 indicated this limitation as well.
• The electronic reporting permit special condition A. (4.) was updated.
• The permit map was updated.
The NPDES standard conditions (Parts II, III, and IV) that are a part of the permit are not included in
this draft document (cover, map, and Part I). The conditions are the same as in your current permit
except that agency and division names have been updated. The latest version is available at
https://bit.ly/2BZ4xxx and can be viewed online or downloaded as a PDF file.
With this notification, the Division will solicit public comment on this draft permit by publishing a
notice in newspapers having circulation in the general Union County area, per EPA requirements. Please
provide your comments, if any, to me at the address below no later than 30 days after receiving
this draft permit.
Following the 30-day public comment period, the Division will review all pertinent comments and take
appropriate action prior to issuing a final permit.
NORTH CAROLINA
Department of Environmental Quality
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11617 Mail Service Center I Raleigh, North Carolina 27699-1617
919.707.9000

If you have questions concerning the draft, please contact me at 919-707-3618, or via e-mail at
[e-mail].
Sincerely,
Derek C. Denard, Environmental Specialist
Division of Water Resources, NCDEQ
ec: NPDES Files [Laserfiche]
Union County / William M. Watson[[e-mail]]; Andy Neff, P.E., [[e-mail]];
Bart Farmer[bart.farmergunioncountync.gov]
DWR/MRO Corey Basinger [[e-mail]]; Roberto Scheller [[e-mail]]

NPDES Permit NC0085812
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WATER RESOURCES
PERMIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
(NPDES)
In compliance with the provisions of North Carolina G
and regulations promulgated and adopted by
Commission, and the Federal Wa
r
tatute 143-215.1, other lawful standards
Carolina Environmental Management
ution Control Act, as amended,
Union County • lic orks
are hereby authorized to discharwastewate a facility located at the
GrasiBranch WW
1629 Old Fis oad (off NCS , onroe, NC
Union County
to receiving waters designated as Crooked Creek with e Yadkin -Pee Dee River Basin in accordance
with effluent limitations, monitoring requirements, and r conditions set forth in Parts I, II, III, and
IV hereof.
The permit sliall bjcome effecti
This permit and the authorization
Signed this day
ischarge shall expire at midnight on October 31, 2023.
S. Daniel Smith, Director
Division of Water Resources
By Authority of the Environmental Management Commission
Page 1 of 9

NPDES Permit NC0085812
SUPPLEMENT TO PERMIT COVER SHEET
All previous NPDES Permits issued to this facility, whether for operation or discharge are hereby revoked. As of
this permit issuance, any previously issued permit bearing this number is no longer effective. Therefore, the
exclusive authority to operate and discharge from this facility arises under the permit conditions, requirements,
terms, and provisions included herein.
Union County Public Works
is hereby authorized to:
1. Continue to operate an existing 0.05 MGD wastewaent that includes the following
wastewater treatment components:
• an influent pump station
• a manual bar screen
One (1) iita flow equalization basin®
• two (2) aeration basins
• two (2) secondary clarifi
• aerated sludge digester
• two (2) tertiary filters
• ultraviolet disinfection
• backup chlorination/dechlorinati
• continuous flow measurement
• standbpower
located at the Grassy WWTP (1629 Old Fish l(ad, Monroe) in Union County; and
2. after receipt ohn Authoriz ion to Construct and submittal of an Engineers Certification for expansion to
0.120 vIGD, operate tewater treatment plant consisting of the following components:
• an influent station
•, two 2 manua screens
Two (2) flow equalization basins
• three (3) aeration basins
• three (3) secondary clarifiers
• three 3) aerated slud e digesters
• \h1 e t lalxf rs
• a disc filter
• ultraviolet disinfection
• backup chlorination/dechlorination
• continuous flow measurement
• standby power
3. discharge from said treatment works, via Outfall 001, at a location specified on the attached map, into
Crooked Creek [Stream Index 13-17-20], currently Class C waters within Subbasin 03-07-12 [HUC
030401050702] of the Yadkin -Pee Dee River Basin.
Page 2 of 9

NPDES Permit NC0085812
PART I
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[15A NCAC 02B .0400 et seq., 15A NCAC 02B .0500 et seq.]
Grade II Biological Water Pollution Control System [15A NCAC 08G.0302]
During the period beginning on the effective date of this permit and lasting until expansion above 0.050 MGD or
expiration, the Permittee is authorized to discharge treated wastewater from Outfall 001. Such discharges shall be
limited and monitored) by the Permittee as specified below:
EFFLUENT CHARACTERISTICS
[PARAMETER CODES]
LIMITS
MONITORING REQUIREMENTS1
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample
Location2
Flow (MGD)50050
0.050 MGD
Continuous
RecordingInfluent
or
Effluent
BOD, 5-day, 20°C (mg/L) 3
(April 1 — October 31)
C0310
5.0 mg/L
7.5 mg/L
Weekly
Composite
Effluent,
Influent
BOD, 5-day, 20°C (mg/L) 3
(November 1—March 31)
C0310
10.0 mg/L
15.0
Weekly
omposite
Effluent,
Influent
Total Suspended Solids 3
(TSS) (mg/L)
C0530
45.0 mg/L
Weekly
Composite
Effluent,
Influent
NH3 as N (mg/L)
(April 1 — October 31)
C0610
2.0
L
Weekly
Composite
Effluent
NH3 as N (mg/L)
(November 1 —March 31)
C0610
4.0 mg
12.0 m
Weekly
Composite
Effluent
Dissolved Oxygen (DO)
0030
Daily Average > 6.0 mg/L 4
Weekly
Grab
Effluent
Fecal Coliform (#/100 ml)
(geometric mean)
31616
0/100 ml
4 0 ml
Weekly
Grab
Effluent
Temperatur
itorin eport
Weekly
Grab
Effluent
Total Chlorine
(TRC)
50060
17 µg/L5
2/Week
Grab
Effluent
pH (su)
00400
and
< 9.0 standard units
Weekly
Grab
Effluent
6
Mercury, Total (n
COMER
6
Once Per Permit Cycle
Once per
permit cycle
Grab
Effluent
Dissolved Oxygen (D L)
00300
Monitor & Report
Variable2
Grab
U, D
Temperature (°C)
00010
Monitor & Report
Variable2
Grab
U, D
Footnotes:
1. The permittee shall submit discharge monitoring reports electronically using the Division's eDMR system
[see A. (4)].
2. Sample locations: U- Upstream 50 feet above discharge point, D- Downstream at NC 218 bridge.
Upstream/downstream samples shall be collected 3/Week during June, July, August, September, and Weekly
during the remaining months of the year.
Instream monitoring requirements shall be provisionally waived so long as the permittee remains a member of
the Yadkin Pee Dee River Basin Association and the Association continues to function as approved by the
Division and Environmental Management Commission.
Page 3 of 9

NPDES Permit NC0085812
3. The monthly average effluent BOD5 and TSS concentrations shall not exceed 15% of the respective influent
value (85% removal).
4. Total Residual Chlorine monitoring is required only if chlorine is added to the effluent.
5. The Division shall consider all effluent TRC values reported below 50 gg/1 to be in compliance with the
permit. However, the Permittee shall continue to record and submit all values reported by a North Carolina
certified laboratory (including field certified), even if these values fall below 50 gg/L.
6. Compliance with this limit shall be determined in accordance with A. (3).
Conditions:
• There shall be no discharge of floating solids or visible foam in others trace amounts.
Page 4 of 9

NPDES Permit NC0085812
A. (2.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[15A NCAC 02B .0400 et seq., 15A NCAC 02B .0500 et seq.]
Grade II Biological Water Pollution Control System [15A NCAC 08G.0302]
During the period beginning upon receipt of an Engineer's Certification for completion of the 0.120 MGD expansion
and lasting until expiration, the Permittee is authorized to discharge treated wastewater from Outfall 001. Such
discharges shall be limited and monitored) by the Permittee as specified below:
EFFLUENT CHARACTERISTICS
[PARAMETER CODES]
LIMITS
MONITORING REQUIREMENTS1
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample
Location2
Flow (MGD)50050
0.120 MGD
Continuous
RecordingInfluent
or
Effluent
BOD, 5-day, 20°C (mg/L) 3
(April 1 — October 31)
C0310
5.0 mg/L
7.5 mg/L
Weekly
Composite
Effluent,
Influent
BOD, 5-day, 20°C (mg/L) 3
(November 1—March 31)
C0310
10.0 mg/L
.0 mg/L
Composite
Effluent,
Influent
Total Suspended Solids 3
(TSS) (mg/L)
C0530
30.0 mg/L
45.0 m
Week
Composite
Effluent,
Influent
NH3 as N (mg/L)
(April 1 — October 31)
C0610
L
6.0 mg/
Weekly
omposite
Effluent
NH3 as N (mg/L)
(November 1 — March 31)
C0610
4.
0 mg/L
Weekly
Composite
Effluent
Dissolved Oxygen (DO) (mg/L)
00300
► y
Aver 4 mg/L
Weekly
Grab
Effluent
Fecal Coliform (#/100 ml)
(geometric mean)
200/100 ml
400/100 m
Weekly
Grab
Effluent
Temperature (°C)
00010
'
Monitoring & Report
Weekly
Grab
Effluent
Total Residual Chlorine 4'5 141
(TRC) (µg/
50060
17 µg/L5
2/Week
Grab
Effluent
pH (su)
00400
> 6.0 standard units
Weekly
Grab
Effluent
6
Mercury, (ng/L)
OMER
6
Once Per Permit Cycle
Once per
permit cycle
Grab
Effluent
Dissolved Oxy O) (mg/L)
onitor & Report
Variable2
Grab
U, D
Temperature (°C)
000
Monitor & Report
Variable2
Grab
U, D
Footnotes:
1. The permittee shall submiu. arge monitoring reports electronically using the Division's eDMR system
[see A. (4)].
2. Sample locations: U- Upstream 50 feet above discharge point, D- Downstream at NC 218 bridge.
Upstream/downstream samples shall be collected 3/Week during June, July, August, September, and Weekly
during the remaining months of the year.
Instream monitoring requirements shall be provisionally waived so long as the permittee remains a member of
the Yadkin Pee Dee River Basin Association and the Association continues to function as approved by the
Division and Environmental Management Commission.
3. The monthly average effluent BOD5 and TSS concentrations shall not exceed 15% of the respective influent
value (85% removal).
Page 5 of 9

NPDES Permit NC0085812
4. Total Residual Chlorine monitoring is required only if chlorine is added to the effluent.
5. The Division shall consider all effluent TRC values reported below 50 µg/1 to be in compliance with the
permit. However, the Permittee shall continue to record and submit all values reported by a North Carolina
certified laboratory (including field certified), even if these values fall below 50 µg/L.
6. Compliance with this limit shall be determined in accordance with A. (3).
Conditions:
• There shall be no discharge of floating solids or visible foam in other than trace amounts.
A. (3.) EFFLUENT MERCURY ANALYSIS [G.S. 143-2
The Permittee shall provide one effluent mercury sis, using EPA Method 1631E, in conjunction
with the next permit renewal application. The analysis should be taken within 12 months prior to the
application date. Any additional mercu effluent mercury measurement conducted from the effective
date of this permit and up to the applicate shall be submitted with the renewal application.
If the result of the mercury analysis is iii i provided with the application, the application may be
returned as incomplete and the Permittee considered non -compliant.
Page 6 of 9

NPDES Permit NC0085812
A. (4.) ELECTRONIC REPORTING - DISCHARGE MONITORING REPORTS
[G.S. 143-215.1 (b)]
Federal regulations require electronic submittal of all discharge monitoring reports (DMRs) and program
reports. The final NPDES Electronic Reporting Rule was adopted and became effective on December
21, 2015.
NOTE: This special condition supplements or supersedes the following sections within Part II of this
permit (Standard Conditions for NPDES Permits):
• Section B. (11.) Signatory Requirements
• Section D. (2.) Reporting
• Section D. (6.) Records Retention
• Section E. (5.) Monitoring Reports
1. Re , ortin Re i uirements Su s ersedes Section D. 2. and Section E. 5.
The permittee shall report discharge monitoring data electronic 11y using the DWR's Electronic
Discharge Monitoring Report (eDMR) internet application.
Monitoring results obtained duringthe previous month(s) 1 be summarized for each month and
submitted electronically using eDMR. The eDMR system al s permitted facilities to enter
monitoring data and submit DMRs electronically using the internet. The eDMR system may be
accessed at: https://deq.nc.gov/about/divisions/water-resources/edmr�
If a permittee is ultble to use the eDMR system due to a demonstrated hardship or due to the facility
being physically 1 cated in an area where less than 10 percent oftfie households have broadband
access, then a temporary waiver from the NPDLS electronic reporting requirements may be granted
and discharge monitoring data may be submitted on paper DMR forms (MR 1, 1.1, 2, 3) or
alternative forms approved by the Director. Duplicate signed copies shall be submitted to the
following address:
NC D Division of Water Resources / Water Quality Permitting Section
ATTEN : Central Files
1617 Mail e Center w
Raleigh, Nort . slim 276917
See "How to Reque' om Electronic Reporting" section below.
Monitoring results obtained during the previous month(s) shall be summarized for each month and
reported via the eDMR system no later than the last calendar day of the month following the
completed reporting period. Regardless of the submission method, the first DMR is due on the last
day of the month following the issuance of the permit or in the case of a new facility, on the last day
of the month following the commencement of discharge.
Starting on December 21, 2025, the permittee must electronically report the following compliance
monitoring data and reports, when applicable:
Page 7 of 9

NPDES Permit NC0085812
• Sewer Overflow/Bypass Event Reports;
• Pretreatment Program Annual Reports; and
• Clean Water Act (CWA) Section 316(b) Annual Reports.
The permittee may seek an electronic reporting waiver from the Division (see "How to Request a
Waiver from Electronic Reporting" section below).
2. Electronic Submissions
In accordance with 40 CFR 122.41(1)(9), the permittee must identthe initial recipient at the time
of each electronic submission. The permittee should use the EPA s website resources to identify the
initial recipient for the electronic submission.
Initial recipient of electronic NPDES information from 1lPDES-regulated facilities means the entity
(EPA or the state authorized by EPA to implement the NPDES program) that is the designated entity
for receiving electronic NPDES data [see 40 CFR 127.2(b)].
EPA plans to establish a website that will also link to the appropriate electro • orting tool for
each type of electronic submission and for each state. Instructions on how to a . i d use the
appropriate electronic reporting toil will be available as well. Information on EP NPDES
Electronic Reporting Rule is found at: https://www.federilregister.gov/documents/2015/10/22/2015-
24954/nati onal-pollutant-discharge-elimination-system-npdes-electronic-reporting-rule
Electronic submissions must start by the dates listed in the "Reporting Requirements" section above.
3. How to Request a Waiver from Electronic Reporting
The permittee may seek a temporary electronic reporting waiver from the Division. To obtain an
electronic reporting waiver, a permittee must first su•mit an electronic reporting waiver request to
the Division. Requests for temporary electronic re • s g waivers must be submitted in writing to
the Division for written approval at least six d. s prior to the date the facility would be
required under this permit to begin submitting m toring data and reports. The duration of a
temporary waiver shall not exceed 5 years and shall thereupon expire. At such time, monitoring data
and repo all be submits electronically to the Division unless the permittee re -applies for and is
granted a n: porary electronic reporting waiver by the Division. Approved electronic reporting
waivers are n r . sferrable. Only permittees with an approved reporting waiver request may
submit monitorin, . and repo+ on paper to the Division for the period that the approved
reporting waiver re • s effective.
Information on eDMR an
the following web page:
e application for a temporary electronic reporting waiver are found on
http://deq.nc.gov/about/divisions/water-resources/edmr
Page 8 of 9

NPDES Permit NC0085812
4. Signatory Requirements [Supplements Section B. (11.) (b) and Supersedes Section B. (11.) (d)1
All eDMRs submitted to the permit issuing authority shall be signed by a person described in Part II,
Section B. (11.)(a) or by a duly authorized representative of that person as described in Part II,
Section B. (11.)(b). A person, and not a position, must be delegated signatory authority for eDMR
reporting purposes.
For eDMR submissions, the person signing and submitting the DMR must obtain an eDMR user
account and login credentials to access the eDMR system. For more information on North
Carolina's eDMR system, registering for eDMR and obtaining a DMR user account, please visit
the following web page:
http://deq.nc.gov/about/divisions/water-resources/edmr
Certification. Any person submitting an electroni
the following certification [40 CFR 122.22].
WILL BE ACCEPTED:
using the state's eDMR system shall make
ER STATEMENTS OF CERTIFICATION
"I certify, under penalty of law, that this document and all at
ents were prepared under my
direction or supervision in accorda ce with a systesignec'assure that qualified personnel
properly gather and evaluate the iormation submitted. Based on my inquiry of the person or
persons who manage the system, or those per s directly responsible for gathering the information,
the information submitted is, to the besmy edge and belief true, accurate, and complete. I
am aware that there are significant pen s for mitting false inf rmation, including the
possibility of fines an imprisonment for knowing violations "
5. Records Retention [Supplements Section D. (6.)1
The permittshall retain records of all Discharge M nitoring Reports, including eDMR
submissions. These records or copies shall be main ed for a period of at least 3 years from the
date of the report. This period may be extend r uest of the Director at any time [40 CFR
122.41].
Page 9 of 9

,, ft Nal
Outfall 001
1:2,000
-1,,05
T GIS U
Max
rr„LI\-i u
Union County Public Works
Grassy Branch WWTP
NPDES Permit NC0085812
1629 Old Fish Road, Monroe, NC
Receiving Stream: Crooked Creek
Stream Segment: 13-17-20
River Basin: Yadkin -Pee Dee
County: Union
Stream Class: C
Sub -Basin #: 03-07-12
HUC: 030401050702
"liI Fish Rd
�R•
SCALE
1:24,000
1:14,000,000VeSVIIII
sir-NWPAit����
Outfall 001: 35° 07' 50" N, -80° 29' 40" W
USGS Quad: Stanfield, NC

5/12/22, 9:34 PM Mail - Denard, Derek - Outlook
[External] RE: Issuance of Modification NPDES Permit NC0085812 Modification - Union
County - Grassy Branch WRF
Mark Watson <[e-mail]>
4/5/2022
To: Denard, Derek <[e-mail]>
Cc: Hennessy, John <[e-mail]>;Basinger, Corey <[e-mail]>;Scheller, Roberto
<[e-mail]>;Weaver, Charles <[e-mail]>;Andy Neff
<[e-mail]>;Bart Farmer <[e-mail]>
CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment
to Report Spam.
Mr. Denard,
Transmittal of documents in an electronic manner is acceptable. By way of this email I am confirm
receipt of the Issuance of NPDES Permit NC0085812,Grassy Branch WRF, Grade II Biological WPCS,
Union County documents. I was able to open and view the document(s) and have saved/printed a copy
for my records.
Mark Watson
County Manager
T 704.292.2625
M 980.229.0694
[e-mail]
unioncountync.gov
E-mail correspondence to and from this sender may be subject to the North Carolina
Public Records law and may be disclosed to third parties. If you are not the intended
recipient of this e-mail, please contact the sender immediately.
From: Denard, Derek [mailto:[e-mail]]
Sent: Tuesday, April 5, 2022 2:59 PM
To: Andy Neff <[e-mail]>; Mark Watson <[e-mail]>; Bart Farmer
<[e-mail]>
Cc: Hennessy, John <[e-mail]>; Basinger, Corey <[e-mail]>; Scheller,
Roberto <[e-mail]>; Weaver, Charles <[e-mail]>
Subject: Issuance of Modification NPDES Permit NC0085812 Modification - Union County - Grassy Branch WRF
WARNING: This email originated from outside of Union County Government, be cautious when clicking
on links or opening attachments.
Dear Mr. Watson:
Please find the attached issuance of the Modification of NPDES Permit NC0085812 for Union County's
Grassy Branch WRF.
In order to provide more convenience, control, and security to our permittees and assist them in
processing their transactions, the Division of Water Resources is currently transitioning towards
https://outlook.office365.com/mail/id/AAQkADdhYTVmZDBILTESZDctNG15MC04Zj1iLWU4MjVhZTBhMmJkMgAQADZp5SvMF%2FhljmbGfu7PZf4%3D 1/2

5/12/22, 9:34 PM Mail - Denard, Derek - Outlook
electronic correspondence. This will hopefully provide more efficient service to our permittees and other
partners and will allow us to more effectively process and track documents. We are writing to ask you
for your approval of the transmittal of documents related to your permitting and related activities with
the Division in an electronic format. Documents will be emailed to the appropriate contact person(s) in
your organization in a PDF format.
Please respond to me through email with verification that transmittal of your documents in an
electronic manner is acceptable to you.
Please respond to this email confirming that you received the attached document(s), were able to
open and view the document(s) and have saved/printed a copy for your records.
If you have any questions, please feel free to contact me.
Derek Denard
Environmental Specialist
N.C. Division of Water Resources
N.C. Department of Environmental Quality
919 707 3618 office
919 707 9000 main DWR
[e-mail]
1617 Mail Service Center
Raleigh, NC 27699-1617
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.
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