NC0081621_More Information Received_20180716

ix W1ii15
ENGINEERS
July 16, 2018 1968.019(34)
Mr. Qais Banihani
North Carolina Division of Environmental Quality
NPDES Complex Permitting Unit
Archdale Building-9th Floor RECEIVEDIDENRIDWR
512 North Salisbury Street
Raleigh, North Carolina 27604 JUL 17 2018
Subject: Request for Additional Information WaterResources
Permittingect on
Permitting
NPDES Application NC0081621
Muddy Creek WWTP
Dear Mr. Banihani:
This letter is in response to your Request for Additional Information (Request) for the Muddy
Creek WWTP NPDES Application NC0081621, dated June 4, 2018. Responses to each of your
comments are in the order presented in your Request. A copy of your Request is attached for
reference.
1. In our opinion,the tributary population cannot be accurately predicted using North Carolina
Census data. The contributors to the Muddy Creek WWTP include portions of Midland as
well as several nearby unincorporated areas.The WSACC Master Plan Report issued by GHD,
LandDesign, and Willis Engineers that was included as part of our Engineering Alternatives
Analysis is an in-depth analysis of the service area and how it will change over time. The
Report presents statistical and economic models to determine the growth in the entire
WSACC Muddy Creek service area through 2040,which far exceed the projections from the
North Carolina Census Linear Extrapolation Method. The projected flows and population
from this Report are 1.12 MGD and 8,238 people, respectively.
To illustrate the shortcomings of the Linear Extrapolation Projection presented in the
Engineering Alternatives Analysis Guidance Documents, a detailed calculation of the 2040
flow and population using this methodology are shown in the Population Projection
Attachment. Using this approach, the 2040 projected population and flow tributary to
Muddy Creek was calculated to be much lower than what is expected by the WSACC Master
Plan.
2. A letter was not included in the original submittal because WSACC owns both the Muddy
Creek WWTP and the Rocky River Regional WWTP. The pumping of wastewater would not
be a cost-effective solution and WSACC anticipates both facilities will be required to treat
10700 Sikes Place,Suite 115
Charlotte, North Carolina 28277
704.377.9844/NC License F-0114

Mr.Qais Banihani
July 16, 2018
Page 2 of 2
the projected flows in their respective collection areas through 2040. Nonetheless, WSACC
has issued the attached letter confirming its rejection of that option.
3. The requested NPDES Permit capacity in this application is 1.0 MGD. Projections indicate
the 2040 flows to the Muddy Creek Plant will be approximately 1.0 MGD. The proposed
facilities will be designed in such a way that would allow expansion through additional
construction to 1.5 MGD if needed. A new NPDES Permit Limit for 1.5 MGD would be
requested if this situation were to arise. Once the new WWTP is completed, the existing
0.30 MGD Muddy Creek WWTP will be taken offline.
4. The new WWTP will not have the same outfall location as the existing WWTP. The exact
location of the new outfall is not yet known because the facilities have not yet been
designed. The general location of the proposed outfall will in the area near 35°12'26.38"N ,
80°29'32.70"W.
5. The updated winter 7Q10 value is 83 cfs. Our correspondence with the USGS is attached.
6. The proposed 1.0 MGD WWTP will have tertiary filtration.This is stated several times within
the Engineering Alternatives Analysis, included in the Flow Schematic, and included in the
Alternative D Cost Estimate.
Please let us know if there is anything we can do to further clarify any of the information in the
Request for Additional Information.
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Yours very truly, .t b ' o•r
WILLIS if.INE/r S /
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as
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Attachments �'�: �� s�e��j�� ��
cc: Water and Sewer Authority of Cabarrus County

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
Water Resources LINDA CULPEPPER
Environmental Quality Interim Director
June 4,2018
Certified Mail#7016 2140 0000 4371 0745
Return Receipt Request
Mr. Charles A.Willis,P.E.
Willis Engineers
10700 Sikes Place
Charlotte,NC 28277
Subject: Request for Additional Information
NPDES Application NC0081621
Muddy Creek WWTP
Dear Mr.Willis:
The Division received two permit applications for the Muddy Creek WWTP.One for renewal of the existing
facility and the other one is for a new permit for the future facility. It appears that both facilities will serve
the Town of Midland residents.After reviewing your permit applications and the Engineering Alternative
Analysis (EAA), both applications will be considered as one (a renewal/expansion). The permit for both
facilities would include three flow tiers;the current 0.15,0.3 and if the expansion is approved,an additional
tier of 1.0 MGD will be added as the ultimate capacity.
To enable us to complete our review in accordance with N.C.G.S. 143-215.1 and 15A NCAC 2H.0105,
please provide additional or revised information to address the following comments:
EAA:
1. What is the current and projected population within the service area by the year 2040 (data from
NC Census)?Based on the projected population,please estimate the projected flow in accordance
with the EAA Guideline Document. The EAA Guidance Document is attached for your reference
and please see page 3 of 8 on how to determine Municipal Flow Projections.
2. Please provide an acceptance or rejection letter from Rocky River WWTP in regard to alternative
A-Connection to existing Wastewater Treatment Facility in your EAA.
3. The EAA states that the ultimate capacity of the proposed facility is 1.5 MGD(page 7)-please
confirm the ultimate capacity will be 1 MGD as discussed over the phone with Julie Grzyb. In
addition,please confirm that the existing facility will be taken off-line after the new facility
becomes operational. Note that the Municipal Flow Projection must justify the ultimate capacity
being requested.
4. Both applications give the same longitude and latitude for the Outfall location. Is this correct(i.e.
will the new plant discharge through the existing outfall)? Will the outfall have to be resized? If
the new facility will not discharge through the existing Outfall,please explain and provide details
on the proposed location.
State of North Carolina I Environmental Quality
1611 Mail Service Center I Raleigh,North Carolina 27699-1611
919-707-9000

Permit Application:
5. Your speculative limits request dated back on November 2, 2015 had an updated USGS summer
7Q10 value but missing the updated winter 7Q10 value.Please provide the updated USGS winter
7Q10 value for the receiving stream.
BioWin Results:
In the results and discussion section of the BioWin, it is obvious that the facility without the tertiary
filtration will not meet the speculative limit of 5 mg/L for BOD5, which is different than the conclusion
drawn in the EAA.Based on the BioWin results; with tertiary treatment the effluent BOD5 is 4.8 mg/L vs
5.3 mg/L without tertiary treatment;therefore,any proposed facility should have tertiary treatment in order
to meet the speculative limits for BOD5.Please review this conclusion and reassess plant costs with tertiary
treatment if needed to meet a BOD5 limitation of 5 mg/L. Provide an explanation on your conclusion if
tertiary treatment is not added.
If no response is received August 1,2018 [per 15A NCAC 2H.0107(b)],the project will be deactivated and
withdrawn from our review process and the documents will be recycled.If you have any questions,please
contact me at 919-807-6396 or email at [e-mail].
Sincerely,
Qais Banihani,Environmental Engineer
NPDES Complex Unit
• Division of Water Resources/NCDENR
cc: Mr. John W. Ritchie, Wastewater Operations Manager, WSACC
Mr. Timothy R. Kiser, P.E., Engineering Director, WSACC
Mr. T. Mark Fowler, Facilities Director,WSACC
Pane 2 of 2

WSACC Population Projection
Muddy Creek WWTP
Referring to the Population and Flow Projections of the WSACC Master Plan that was submitted as part
of the NPDES Permit Application Submittal,the 2040 flow and population at the Muddy Creek WWTP
are projected to be 1.12 MGD and 8,238 people, respectively.
The calculations below project the 2040 flow and population from the North Carolina Census Data
using the Linear Extrapolation Method outlined in the Engineering Alternatives Analysis Guidance
Documents. The results of the calculations are much lower than what is projected by the WSACC
Master Plan. There are many factors present within this service area that will result in faster growth.
These factors are outlined in the Population and Flow Projections Section of the NPDES Engineering
Alternatives Analysis that was previously submitted.
According to the WSACC Master Plan, there are plans to expand the collection system of the Muddy
Creek WWTP to capture more of the Midland area by 2040. For the Census calculations below, the
initial population served by Muddy Creek will be equivalent to what is served now (as noted in
Application 2A). The 2040 population served will be equal to the projected population in Midland in
2040 due to the expanding collection system over Midland.
Engineering Alternatives Analysis Linear Extrapolation Method—Census Data
Assumptions:
Current Flow:' 0.1189 MGD(2A Application)
Current Population Served by MCWWP: 1,463 (2A Application)
2010 Midland Population: 3,073 (2010 Census)
2017 Midland Population: 3,760 (2017 Census)
Future Residential Flow Per Capita: 70 gal/capita (EAA)
Future Commercial Flow Per Capita: 15 gal/capita (EAA)
Future Industrial Flow: 25,000 gallons(Estimate)
Calculations:
Annual Population Increase:
3,760-3,073
= 98 people/year
7 years �Y
Population Increase by 2040:
98 people x (2040 — 2018) = 2156 additional people
year
Willis Engineers
1968.019 1 July 2018

WSACC Population Projection
Muddy Creek WWTP
Flows from Population Increase through 2040:
Residential: 2156 capita x 70 gal = 150,920 gallons
capita
Commercial: 2156 capita x 15gal = 32,340 gallons
capita
Flows from Expanding Service Area through 2040:
Additional Residents: 3,760 + 98 — 1,463 = 2,395 people
Residential: 2,395 capita x 70 gal = 167,650 gallons
capita
Commercial: 2,395 capita x 159a1 = 35,925 gallons
capita
Total Daily Flows 2040:
118,900 + 25,000 + 150,920 + 32,340 + 167,650 + 35,925 = 530,735 gallons
In our opinion, the Linear Extrapolation Method outlined in the Engineering Alternatives Analysis
Guidance Document does not adequately predict the growth in the Muddy Creek Service Area. The
method does not take socio-economic factors in to account, nor does it account for the proximity of
Muddy Creek to the Charlotte Metropolitan Area, which are all factors that will result in faster growth in
the area.
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Willis Engineers
1968.019 2 July 2018

W S j c C WATER&SEWER AUTHORITY
OF CABARRUS COUNTY
Office: 232 Davidson Hwy.
Concord,NC 28027
704.786.1783 • 704.795.1564 Fax
www.wsacc.org
ISO 14001:2004•NC Star Public Sector•0850518001:2001
North Carolina Division of Environmental Quality
NPDES Complex Permitting Unit
Archdale Building - 9th Floor
512 North Salisbury Street
Raleigh, North Carolina 27604
Attn: Qais Banihani
Subject: Request for Additional Information
NPDES Application NC0081621
Muddy Creek WWTP
Gentlemen:
The Water and Sewer Authority of Cabarrus County has evaluated several alternatives to meet
our wastewater treatment needs. These alternatives are presented in the Engineering Alternatives
Analysis Report submitted by Willis Engineers for the Muddy Creek Wastewater Treatment
Plant (WWTP)NPDES Application. This letter is to confirm that WSACC has rejected the
alternative of pumping wastewater from Muddy Creek WWTP to Rocky River Regional WWTP
(Alternative A). We believe that both of our treatment facilities will be required to meet our
long-term needs.
Yours very truly,
Water and Sewer Authority of Cabarrus County
Timothy R. ser, P.E.
Engineering Director

Steve Gerlach
From: Weaver,John <[e-mail]>
Sent: Tuesday,June 19, 2018 2:48 PM
To: Steve Gerlach
Cc: Chuck Willis;John C Weaver
Subject: Response from USGS concerning...Re: [EXTERNAL] FW:Winter 7010 Flow for Muddy Creek WWTP
Mr. Gerlach,
In response to your inquiry about the winter 7Q10( 7 /0)iow-flow discharge for a location on the Rocky River near Midland in
southeastern Cabarrus County,the following information is provided:
FSP as neat This request is a follow-up to a previous one received for the same site on the Rocky River in latter 2015. The
location for the point of interest is identified by the lat/long coordinates (35 12 28 N, 80 29 30 W) provided by Mr. Chuck Willis
via email dated October 13, 2015. The email for the initial response is replicated at the end of this message. Please note the
response below is replicated from the same initial response sent to Mr. Willis via email dated October 29, 2015. The W7O
determination has been added in red font.
No USGS discharge records are known to exist for the point of interest.
In the absence of site-specific discharge records sufficient for a low-flow analysis, estimates of low-flow characteristics at
ungaged locations are determined by assessing a range in the low-flow yields(expressed as flow per square mile drainage area,
or cfsm) at nearby sites where estimates have been determined.
For streams in Cabarrus County, low-flow characteristics published by the USGS are provided in the following reports:
(1)The first is a basin-wide report for the Rocky River basin published in 2003. It is USGS Water-
Resources Investigations Report 03-4147, "Low-Flow Characteristics and Profiles for the Rocky River
in the Yadkin-Pee Dee River Basin, North Carolina, through 2002" (Weaver and Fine, 2003). An
online version of the report is available through http://pubs.usgs.gov/wri/wri034147/. The report
provides the low-flow characteristics (based on data through 2002) for continuous-record gaging
stations and partial-record sites within the Rocky River basin. The report also provides low-flow
discharge profiles (7Q10, 30Q2, winter 7Q10, and 7Q2) for the Rocky River from its headwaters in
Mecklenburg County to its mouth.
(2)The second is a recently published statewide report published in March 2015. It is USGS Scientific Investigations
Report 2015-5001, "Low-flow characteristics and flow-duration statistics for selected USGS continuous-record streamgaging
stations in North Carolina through 2012" (Weaver, 2015). The report is available online
at http.//pubs.usqs.qov/sir/2015/5001/. The report provides updated low-flow characteristics and flow-duration statistics for 266
active (as of 2012 water year)and discontinued streamgages across the state where a minimum of 10 climatic years discharge
records were available for flow analyses.
A basin delineation completed for the point of interest using the USGS StreamStats application for North Carolina
(http//water.usgs.gov/osw/streamstats/north carolina.html) resulted in a drainage area at 553 sqmi.
As noted above, low-flow profiles were developed for the 7Q10 and 30Q2 discharges (figures 7 and 8, respectively) in the first
report. Interpolation of the profiles allows users to estimate the low-flow statistics for ungaged locations along the Rocky
River. In the second report, only low-flow characteristics for selected continuous-record streamgages in North Carolina were
updated for publication, including the downstream streamgage on the Rocky River near Norwood (station id 02126000, drainage
area 1,372 sqmi). This is the only site on the Rocky River for which low-flow characteristics were updated as part of the recent
statewide update. Of note, the drainage area at the streamgage is almost 2.5 times the drainage area at the point of interest, .
1

Comparison of the published 7Q10 discharges for the Norwood streamgage in the first and second reports indicates the 7Q10
increased from 45.8 cfs to 47.0 cfs, respectively, a percentage increase of about 2.6 percent. Comparison of the published
30Q2 discharges indicates no change in value (113 cfs) between the two reports. Because of the small percentage change in
the 7Q10 discharge values and no change for the 30Q2 discharge, it appears reasonable and appropriate to consider the low-
flow profiles in the first report as still being applicable for determining low-flow characteristics at ungaged locations along the
Rocky River.
Using interpolation between discharge values used to develop the profile, the 7Q10 and 30Q2 low-flow yields at the point of
interest are approximately 0.07 cfsm and 0.17 cfsm, respectively. Applied to the drainage area at the point of interest(553
sqmi), the 7Q10 discharge is estimated at 38.7 cfs, and the 30Q2 discharge is estimated at 94 cfs.
C;omperlsonu of the puabbished W7 x 10 dll cfrerges for the Norwood streern age in the first and second repots indicates the
W7010 increased from 77.6 cfs to 79.0 cfs, respectively, a,percentage increase of 1,8 percent. Because of the sma+lil
rperventege change 43 the Wd"1 Q10 discharge velues, 9t likewisa appears reasonable end appropriate(as noted for annual E 010,
and 3002&tscharges)to consider the low-'ow profiles in the first report as stili being applicable for determining tow-i'aw
theraeteuia`'tics at ungaged Oocattons along the Rocky River.
!Using int potation between discharge values used to develop the profile,the wiC110'gow...< yileA tetat the point of interast is
eippro iu at ly 0.15 cfsm, Applied to the drainage area at the point of interest(553 sgri), the n.�`7.10 discharge ia
tM Cb.
The flow statistics presented in the above two reports indicate the annual average discharge yields in the Rocky River basin are
more commonly in the range of 0.9 to 1.0 cfsm. When applied to the drainage area at the point of interest,the average annual
discharge is estimated between 500 and 550 cfs.
Please note the estimated flows are provided in units of cubic feet per second (cfs).
Please understand the information provided in this message is based on a preliminary assessment and considered provisional,
subject to revision pending further analyses.
Hope this information is helpful.
Thank you.
Curtis Weaver
J. Curtis Weaver, Hydrologist, PE Email:icweaverOusgs.gov
USGS South Atlantic Water Science Center Online:httns://www.usas.gov/centers/sa-water
North Carolina-South Carolina -Georgia
3916 Sunset Ridge Road
Raleigh,NC 27607
Phone: [phone] // Fax: [phone]
On Wed,Jun 13, 2018 at 10:18 AM,Steve Gerlach <[e-mail]>wrote:
Mr.Weaver-
We recently submitted an NPDES Permit application for the Water and Sewer Authority of Cabarrus County(WSACC)
for the expansion of the Muddy Creek Wastewater Treatment Plant.We received a Request for Additional Information
from the State asking that we provide them with the winter 7Q10 flow conditions for the receiving stream in our area
of interest(35 12 28N, 80 29 30W).To refresh your memory, in 2015 you provided us with the summer 7Q10 and 30Q2
conditions. I have attached our correspondence from 2015,which includes more information on the project,as well as
your methodology for finding the 7Q10 and 30Q2 values. Please let us know if there is any additional information we
can provide you with.
2

Thanks,
Steven E. Gerlach, E.I.
Willis Engineers
10700 Sikes Place,Suite 115
Charlotte, North Carolina 28277
704.377.9844 office
704.338.4661 direct
704.533.3945 cell
To find out more about Willis Engineers,
visit us online at www.WillisEnaineers.com
Forwarded message
From: Weaver,John <[e-mail]>
Date:Thu, Oct 29, 2015 at 9:40 AM
Subject: Response from USGS concerning...Re: Request for low flow characteristics
To: Chuck Willis <[e-mail]>
Cc:John Weaver<[e-mail]>
3

Mr. Willis,
Thank you for your patience the past several weeks as my focus was directed to field activities following the storm surge and flooding that
affected both North Carolina and South Carolina.
In response to your inquiry about the low-flow characteristics for a location on the Rocky River near Midland in southeastern Cabarrus
County,the following information is provided:
A check of the low-flow files here at the USGS South Atlantic Water Science Center(Raleigh office)indicates several previous low-flow
determinations nearby the specific point of interest on the Rocky River,as identified by the lat/long coordinates(35 12 28 N,80 29 30 W)
you provided via email dated October 13,2015. No USGS discharge records are known to exist for the point of interest.
In the absence of site-specific discharge records sufficient for a low-flow analysis, estimates of low-flow characteristics at
ungaged locations are determined by assessing a range in the low-flow yields (expressed as flow per square mile drainage area,
or cfsm) at nearby sites where estimates have been determined.
For streams in Cabarrus County, low-flow characteristics published by the USGS are provided in the following reports:
(1)The,first is a basin-wide report for the Rocky River basin published in 2003. It is USGS Water-
Resources Investigations Report 03-4147, "Low-Flow Characteristics and Profiles for the Rocky River in the
Yadkin-Pee Dee River Basin, North Carolina, through 2002" (Weaver and Fine, 2003). An online version of the
report is available through http://pubs.usgs.gov/wri/wri034147/. The report provides the low-flow
characteristics (based on data through 2002) for continuous-record gaging stations and partial-record sites
within the Rocky River basin. The report also provides low-flow discharge profiles (7Q10, 30Q2, winter 7Q10,
and 7Q2) for the Rocky River from its headwaters in Mecklenburg County to its mouth.
(2)The second is a recently published statewide report published in March 2015. It is USGS Scientific Investigations
Report 2015-5001, "Low-flow characteristics and flow-duration statistics for selected USGS continuous-record streamgaging
stations in North Carolina through 2012" (Weaver, 2015). The report is available online
at http//pubs.usgs.gov/sir/2015/5001/. The report provides updated low-flow characteristics and flow-duration statistics for 266
active (as of 2012 water year) and discontinued streamgages across the state where a minimum of 10 climatic years discharge
records were available for flow analyses.
A basin delineation completed for the point of interest using the USGS StreamStats application for North Carolina
(http//water.usgs.gov/osw/streamstats/north carolina.html) resulted in a drainage area at 553 sqmi.
As noted above, low-flow profiles were developed for the 7Q10 and 30Q2 discharges (figures 7 and 8, respectively) in the first
report. Interpolation of the profiles allows users to estimate the low-flow statistics for ungaged locations along the Rocky
River. In the second report, only low-flow characteristics for selected continuous-record streamgages in North Carolina were
updated for publication, including the downstream streamgage on the Rocky River near Norwood (station id 02126000, drainage
area 1,372 sqmi). This is the only site on the Rocky River for which low-flow characteristics were updated as part of the recent
statewide update. Of note, the drainage area at the streamgage is almost 2.5 times the drainage area at the point of interest, .
Comparison of the published 7Q10 discharges for the Norwood streamgage in the first and second reports indicates the 7Q10
increased from 45.8 cfs to 47.0 cfs, respectively, a percentage increase of about 2.6 percent. Comparison of the published
30Q2 discharges indicates no change in value(113 cfs) between the two reports Because of the small percentage change in
the 7Q10 discharge values and no change for the 30Q2 discharge, it appears reasonable and appropriate to consider the low-
flow profiles in the first report as still being applicable for determining low-flow characteristics at ungaged locations along the
Rocky River.
Using interpolation between discharge values used to develop the profile, the 7Q10 and 30Q2 low-flow yields at the point of
interest are approximately 0.07 cfsm and 0.17 cfsm, respectively. Applied to the drainage area at the point of interest(553
sqmi), the 7Q10 discharge is estimated at 38.7 cfs, and the 30Q2 discharge is estimated at 94 cfs.
The flow statistics presented in the above two reports indicate the annual average discharge yields in the Rocky River basin are
more commonly in the range of 0.9 to 1.0 cfsm. When applied to the drainage area at the point of interest, the average annual
discharge is estimated between 500 and 550 cfs.
Please note the estimated flows are provided in units of cubic feet per second(cfs).
4

Please understand the information provided in this message is based on a preliminary assessment and considered provisional,subject to
revision pending further analyses.
Hope this information is helpful.
Thank you.
Curtis Weaver
3.Curtis Weaver, Hydrologist,PE Email:icweaver(dusgs.gov
USGS South Atlantic Water Science Center Online:htta://nc.water.usas.aov/
North Carolina-South Carolina-Georgia
3916 Sunset Ridge Road
Raleigh,NC 27607
Phone: [phone] // Fax: [phone]
On Tue, Oct 13, 2015 at 1:09 PM, Chuck Willis<[e-mail]>wrote:
Mr. Weaver—
We are working for the Water and Sewer Authority of Cabarrus County (WSACC) who operates a small
wastewater treatment plant on the Rocky River near Midland (35 12 28N, 80 29 30W). WSACC is considering
expansion of this plant and will be requesting speculative limits from the NC Division of Water Resources. As
part of the request DWR will want to know more about the low flow conditions of the river, specifically the
drainage area, average flow, 7Q10 and 30Q2. Can you assist in providing this information? If there is a fee
associated with this please let us know and we will remit payment promptly.
Thank you in advance for your assistance.
- Chuck
Charles A. Willis,Jr., P.E., BCEE .
Willis Engineers
10700 Sikes Place, Suite 115
Charlotte, North Carolina 28277
704.377.9844 office
704.338.4668 direct
704.641.1621 cell
To find out more about Willis Engineers,
visit us online at www.WillisEngineers.com
5