20201125 Ver 1_More Info Received_20201026

Yankura, Kaylie
From: Jon Swaim <[e-mail]>
Sent: Monday, October 26, 2020 9:04 AM
To: Yankura, Kaylie; Kyle Seaman
Cc: Brown, David W CIV USARMY CESAW (USA); Leslie, Andrea J; Moore, Andrew W
Subject: [External] RE: Request for Additional Information — Horsepasture River WWTP and
Collection System Improvements; DWR# 20201125
Attachments: DWR#20201125-Impact Table & Map -REV 102020.pdf, Cashiers WWTP - Qualitative
Indirect and Cumulative Impact Analysis.pdf, 15.00391- C - Details-C-217 sealed.pdf,
15.00391- C - Storm-C-210 Storm Profiles sealed.pdf, 15.00391- C - Storm-C-209 Final
Storm sealed.pdf
Wm
ternal email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to
q)nc. ,
Kaylie, Please find the attached documents and our responses to your questions below in red.
Please let me know if you need further clarification on any of our plan sheets or responses.
Thank you,
AFA
r 111smutag
n
Jon Swaim
Project Manager
McGill Associates, P.A.
1013 State Farm Road, Boone, NC 28607
T 828.386.1920
C 828.434.0951
[e-mail]
mcgillassociates.com
From: Yankura, Kaylie <[e-mail]>
Sent: Friday, September 25, 2020 4:23 PM
To: Jon Swaim <[e-mail]>; Kyle Seaman <[e-mail]>
Cc: Brown, David W CIV USARMY CESAW (USA) <[e-mail]>; Leslie, Andrea J
<[e-mail]>; Moore, Andrew W <[e-mail]>
Subject: Request for Additional Information — Horsepasture River WWTP and Collection System Improvements; DWR#
20201125
Mr. Swaim,
On August 31, 2020, the Division of Water Resources (Division) received your application requesting a 401 Water Quality
Certification from the Division for the subject project. The Division has determined that your application is incomplete
and cannot be processed. The application is on hold until the following items are addressed:

1. The PCN states that the 30" culvert associated with impact S2 will be buried 6 inches into the streambed. Please
provide cross section details showing the provisions for aquatic life passage for permanent culvert
installation. This information should be shown on the construction drawings for contractor reference. [15A NCAC
02H .0506(b)(1)]. Please see attached revised plan sheet C-209 and Details-C-217.
2. Per General Condition 11.9 of GC 4135, all work must be done "in the dry". Therefore, dewatering methods will be
necessary to temporarily dewater the stream channel during pipe installation. The application states that work
will occur in the dry, but does not specifically address how this will be accomplished. Please provide a construction
sequence that details the method of dewatering to be utilized at the site and the sequence of construction events
to be followed to ensure compliance with this condition. In addition, please ensure that the location of temporary
impacts associated with the proposed dewatering/pump around method are shown on the construction drawings
and that associated temporary impacts are clearly indicated in the PCN impact table (e.g. temporary fill for coffer
dams, jersey barriers, etc.). [15A NCAC 02H .0506 (b)(2)]. Please see attached temporary bypass (pump around)
detail with construction sequence notes. Located on Sheet Details-C-217. An additional 23 linear feet of temporary
impacts was added to the Impact Map and impacts table. See attached.
3. Please confirm if the culvert alignment associated with the proposed 72 linear feet of temporary stream impact
S1 has been appropriately designed to form a perpendicular stream crossing. I am concerned that the outlets of
the proposed alignment will disproportionately direct stream flow and cause downstream channel instability.
Please provide information supporting the proposed design and indicate how downstream degradation will be
avoided. Please also indicate what design alternatives have been considered for the crossing (e.g. the use of less,
larger diameter culverts, etc.). [15A NCAC 02H .0506 (b)]. The temporary culverts have been placed to be parallel
to flow within the existing channel banks, and discharge directly downstream. If the crossing design is rotated to
flow away from the downstream right bank then large amounts of excavation will be required on the left bank to
create a channel. The culvert sizes were selected to provide the maximum cross sectional area available within
the channel while also providing appropriate roadway surface elevations for the stream crossing. The vertical
curvature of the roadway must accommodate large trucks and trailers, therefore, requiring the top of the crossing
to be approximately at the height of the top of bank. If this elevation is increased then grading for the side slopes
of the road to tie into existing grade will be increased and impacts to the floodplain and wetlands will be increased.
The culverts are stepped vertically along the channel to follow the natural slope of the channel. This forces the
water in normal flow conditions through the lowest culvert (left side facing downstream). The highest culvert
(right side facing downstream) has the lowest amount of head and flow. As the water surface increases the water
will incrementally flow through the higher culverts to the right side. The culvert that receives the greatest quantity
and most frequent flow (left side facing downstream) is the furthest from the outside stream bank. The temporary
crossing is designed with the minimum cover required to support heavy construction traffic over the culverts. This
allows the temporary crossing to be overtopped in an excessively large storm event without developing large
amounts of head at the upstream side of the crossing. A temporary bridge option has been considered, however,
it is not feasible to construct the temporary bridge due to lack of access to the other side of the stream. Due to
the topographic constraints and surrounding property ownership, a construction easement from adjacent
properties is not feasible. The upstream side of the permanent bridge was selected as the location for the
temporary crossing to minimize the disturbance to the existing wetlands that is much larger on the downstream
side of the permanent bridge.
4. Please indicate if riprap dissipater pads are a component of the culvert installation associated with temporary
stream impact S1. If so, please include the use of riprap dissipater pads on the submitted plans. [15A NCAC 02H
.0506 (b)(1)] No riprap dissipator pads are proposed to be installed in jurisdictional features.
5. Please evaluate the proposed use of #57 washed stone/surge stone associated with stream impact S1, per the
details included on Sheet C-217. The use of larger stone as backfill may be more effective at preventing stone
washout and transport downstream. [15A NCAC 02H .0506 (b)(3)]. This stone size is selected to provide adequate
bedding on the haunches of the pipe since they are placed close together. The close placement of the pipes
prevents adequate compaction with larger stone sizes. Also this crossing design traps the stone within the crossing

as the stone size incrementally increases to the outside of the crossing. Furthermore the stone sections are
wrapped in fabric and grouted on the outermost stone section. An underdrain is provided to relieve water that
may intrude to the inside of the crossing. This design has been used by us successfully on similar and larger
temporary stream crossings.
6. The permit application indicates that concrete will be used to reinforce riprap installed on the streambank
associated with temporary stream impact S1 and on the temporary roadbed. Please indicate what best
management practices will be utilized to ensure that concrete does not impact surface waters during preparation
and application. [15A NCAC 02H .0502 (c)] [15A NCAC 02H .0506(b)(2) and (3)]. Measures will be taken to prevent
live or fresh concrete, including bags of uncured concrete, from coming into contact with waters of the state until
the concrete has hardened. The temporary impervious dikes will be left in place long enough to allow the concrete
to cure, no less than 24 hours. Fresh concrete will be contained in wood or plastic forms and work areas will be
kept clean so that no seepage occurs into the adjacent water body, especially with the pouring of foundation
work. Concrete equipment and storage containers will be washed out in an upland location that will not drain to
jurisdictional areas. During concrete removal, special care will be taken not to excessively break cured concrete
restricting rubble and excess dust from entering surface waters.
7. Temporary stream crossings are intended for short-term use. Please indicate the proposed timeline regarding use
of the temporary stream crossing associated with impact S1. [15A NCAC 02H .0502 (c)]. 6 to 8 months.
8. Condition 11.11. of 401 General Water Quality Certification 4135 requires that "Installation of culverts in wetlands
shall ensure continuity of water movement and be designed to adequately accommodate high water or flood
conditions. When roadways, causeways, or other fill projects are constructed across FEMA-designated floodways
or wetlands, openings such as culverts or bridges shall be provided to maintain the natural hydrology of the system
as well as prevent constriction of the floodway that may result in destabilization of streams or wetlands." Sheet
C-209 submitted with the PCN appears to depict a stormwater pipe connecting the western portion of Wetland C
to the eastern portion of Wetland C. However, it is difficult to determine from the details on Sheet C-210 whether
the pipe will be installed at an elevation that ensures continuity of water movement. It appears the invert of the
pipe is proposed to be set at an elevation above existing ground. Please provide additional details regarding how
the referenced condition will be met including proposed elevation of existing ground and pipe invert elevation.
[15A NCAC 02H .0506 (b)(2)]. The profile Storm Line on Sheet C-210 has been revised. Please see attached.
9. Please provide a qualitative indirect and cumulative impact analysis for the project. [15A NCAC 02H .0506(b)(3)]
Please see the Division's policy for guidance on our website at:
https://files.nc.gov/ncdeg/Water%20Quality/Surface%20Water%20Protection/401/Policies Guides Manuals/C
umulativelmpactPolicy.pdf. Note that the Division is in receipt of the TWSA-WWTP— Water Resources Cumulative
Impact Analysis provided with the PCN. However, the provided document does not complete the analysis as
required by the Division's policy. Please see attached.
Pursuant to Title 15A NCAC 02H .0502(c), the applicant shall furnish all of the above requested information for the proper
consideration of the application. If all of the requested information is not received, the Division will be unable to approve
the application and it will be returned.
Please contact me if you have any questions. You may provide your response via email or mail to the address below.
Thank you,
Kaylie Yankura
Environmental Specialist —Asheville Regional Office
Water Quality Regional Operations Section
NCDEQ — Division of Water Resources
2090 U.S. Hwy. 70
Swannanoa, N.C. 28711
91

828 296 4685 office
828 231 9634 mobile
kavlie.vankura(a)ncdenr.aov
r �-' d ah—C
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties
Based on the current guidance to minimize the spread of COVID-19, the Department of Environmental Quality has
adjusted operations to protect the health and safety of the staff and public. Many employees are working remotely or are
on staggered shifts. To accommodate these staffing changes, all DEQ office locations are limiting public access to
appointments only. Please check with the appropriate staff before visiting our offices, as we may be able to handle your
requests by phone or email. We appreciate your patience as we continue to serve the public during this challenging time.

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mcgdl
October 26, 2020
Tuckaseigee Water and Sewer Authority
Horsepasture River WWTP and Collection System Improvements
Qualitative Indirect and Cumulative Impact Analysis
Jackson County, North Carolina
Shaping
Communities
Together
Growth is likely to be induced within the Horsepasture River watershed by the
proposed Horsepasture River Wastewater Treatment Plant (WWTP) and Collection
System Improvements project. The purpose of the proposed project is to provide
additional wastewater treatment capacity in the Cashiers, NC area. Future growth
in the surrounding area is expected to follow the existing pattern of primarily
commercial and both low and high density residential. Existing development,
planning regulations, and proposed projects were considered in sizing future
wastewater collection and treatment facilities to meet the needs of the growing
community.
No cumulative effects are anticipated for groundwater resources as a result of the
proposed project. Reduction of the public water supply is not anticipated from future
domestic consumption and commercial usage. Cumulative impacts to surface
waters within the watershed may include sedimentation and run off from land
clearing activities and stream and wetland crossings associated with new
development, however, these impacts should be mitigated by utilizing best
management practices and limiting ground disturbance to the minimum practical.
All future impacts to surface waters and stormwater for construction of potential
projects should be permitted through proper State and Federal Agencies. Any
increased stream sedimentation and soil erosion from increased land clearing for
future development should also be regulated through State and Federal permitting
processes. Changes in hydrological regimes of streams and rivers within the
watershed is not anticipated. The treatment process for the new wastewater
treatment plant will be an advanced tertiary treatment process intended to meet the
stringent effluent limitations of the National Pollutant Discharge Elimination System
(NPDES) permit. WWTP discharges to the Horsepasture River will be closely
monitored and abide by State and Federal water quality parameters and are not
anticipated to impact downstream water quality.
The Horsepasture River along the proposed project area is classified by the North
Carolina Department of Environmental Quality (NCDEQ) as C;Tr:+. Class C waters
are protected for uses such as secondary recreation, fishing, wildlife, fish
consumption, aquatic life including propagation, survival and maintenance of
biological integrity, and agriculture. Secondary recreation includes wading, boating,
and other uses involving human body contact with water where such activities take
place in an infrequent, unorganized, or incidental manner. Trout Waters (Tr) is a
supplemental classification intended to protect freshwaters which have conditions
which shall sustain and allow for trout propagation and survival of stocked trout on
a year-round basis. This classification is not the same as the NC Wildlife Resources
Commission's Designated Public Mountain Trout Waters designation. The + symbol
MCGILL ASSOCIATES 1013 STATE FARM ROAD, BOONE, NC 28607 / 828.386.1920 / MCGILLASSOCIATES.COM

Horsepasture River WWTP and Collection System Improvements
Qualitative Indirect and Cumulative Impact Analysis
Page 2 of 2
identifies waters that are subject to a special management strategy specified in 15A
NCAC 2B .0225 the Outstanding Resource Waters (ORW) rule. All outstanding
resource waters are a subset of High Quality Waters. This supplemental
classification is intended to protect unique and special waters having excellent water
quality and being of exceptional state or national ecological or recreational
significance. Per the ORW rule, water quality conditions shall be maintained to
protect the outstanding resource values of all undesignated waterbodies that are
located within the Horsepasture River watershed. No new discharges or expansions
of existing discharges shall be permitted, and stormwater controls for all new
development activities requiring an Erosion and Sedimentation Control Plan in
accordance with rules established by the NC Sedimentation Control Commission
shall comply with the stormwater provisions set forth in 15A NCAC 02H .1000,
including the specific stormwater management requirements for freshwater ORW
areas set forth in 15A NCAC 02H .1019 and .1021. However, new domestic
wastewater discharges and expansions of existing wastewater discharges shall be
allowed provided that: (A) Oxygen Consuming Wastes: Effluent limitations shall be
as follows: BOD shall not exceed 5 mg1I and NH3-N shall not exceed 2 mg/I; (B)
Total Suspended Solids: Discharges of total suspended solids (TSS) shall be limited
to effluent concentrations of 10 mg11 for trout waters and to 20 mg1I for all other
waters except for mining operations, which shall be held to their respective NPDES
TSS permit limits. (C) Nutrients: If nutrient overenrichment is projected to be a
concern, effluent limitations shall be set for phosphorus, nitrogen, or both; and (D)
Volume: The total volume of treated wastewater for all discharges combined shall
not exceed 25 percent of the total instream flow in the designated ORW under 7Q10
conditions.
The NPDES limitations, existing ORW rules, and the required Erosion and
Sedimentation Control Plan in accordance with rules established by the NC
Sedimentation Control Commission should reduce or eliminate the need for
additional regulatory measures. Strict adherence to these regulatory programs
should result in the protection of the watershed during growth in the surrounding
area.
Please provide any comments regarding concerns or other issues of significance
that may affect this project. We look forward to your comments on this matter. If you
have any questions, feel free to contact me at our office phone number of (828)
386-1920 or my email address ion.swaim(a�mcgillassociates.com.
MCGILL ASSOCIATES 1013 STATE FARM ROAD, BOONE, NC 28607 / 828.386.1920 / MCGILLASSOCIATES.COM

3a. Reason for impact*(?)
3b.lmpact type *
3c. Type of impact*
3d. S. name*
3e. Stream Type *
3f. Type of
3g. S. width*
3h. Impact
(?)
Jurisdiction*
length*
S1
Temporary Crossing
Temporary
Workpad/Causeway
Horsepasture River
Perennial
Both
25
95
Avaage (fee[)
(linear feet)
S2
Road Crossing
9
Permanent
Culvert
UT Horse asture River
P
Intermittent
Both
2
52
(Stream 2)
Average (feet)
(linear feet)
S3
Road Crossing
Temporary
Workpad/Causeway
UT Horsepasture River
Intermittent
Both
2
20
(Stream 2)
Average (feet)
(linear feet)
S4
Concrete Headwall 7
Permanent
Culvert
Horse asture River
P
Perennial
Both
25
8
Average (feet)
(linear feet)
S5
Concrete Headwall 7
Temporary
Workpad/Causeway —]
Horsepasture River
Perennial
Both
25
10
Average (feet)
(linear feet)
** All Perennial or Intermittent streams must be verified by DWR or delegated local government.
3i. Total jurisdictional ditch impact in square feet:
3i. Total permanent stream impacts:
60
3i. Total temporary stream impacts:
125
3i. Total stream and ditch impacts:
185
3j. Comments:
Impact S1 associated with flow diversion/pump around and temporary construction access across Horsepasture River for construction of bridge and access road to WWTP
Impacts S2 and S3 associated with flow diversion/pump around and construction of access road and placement of approx. 521f culvert in stream.
Impacts S4 and S5 associated with discharge pipe/outfall structure from WWTP and concrete headwall construction.
E. Impact Justification and Mitigation
1. Avoidance and Minimization
la. Specifically describe measures taken to avoid or minimize the proposed impacts in designing the project:*
WWTP site was chosen to avoid stream, wetland, trout buffer, and floodplain impacts. Afree spanning bridge design was chosen to avoid permanent
impacts to the Horsepasture River. WWTP discharge structure was designed to limit permanent impacts to the bank of the Horsepasture River and
avoid bed impacts or erosion potential. Multiple access road designs were considered in an attempt to avoid permanent stream and wetland impacts.
This route was ultimately chosen as it provides access from Hwy 64 that meets NCDOT standards, allows for a bridge crossing of the Horsepasture
River, and allows for proper road sizing, turning radius, and gradient up to the WWTP site.
1 b. Specifically describe measures taken to avoid or minimize the proposed impacts through construction techniques:*
A pump around or other approved flow diversion will be used to ensure that all in -stream work occurs in the dry. Temporarily impacted stream bed and
banks will be returned to original conditions using original excavated material, and stabilized with fully biodegradable matting, native NC riparian seed
mix, and native live stakes. No live concrete will come in contact with surface water and will be allowed to cure for 24 hours before natural flow is
returned.
2. Compensatory Mitigation for Impacts to Waters of the U.S. or Waters of the State
2a. Does the project require Compensatory Mitigation for impacts to Waters of the U.S. or Waters of the State?
C Yes F No
2b. If this project DOES NOT require Compensatory Mitigation, explain why:
Impacts to wetland and streams were limited to below mitigation thresholds for Nationwide 7 and 14.
NC Stream Temperature Classification Maps can be found under the Mitigation Concepts tab on the Wilmington District's RIBITS website.
F. Stormwater Management and Diffuse Flow Plan (required by DWR) V
*** Recent changes to the storrTmater rules have required updates to this section .***
1. Diffuse Flow Plan
1a. Does the project include or is it adjacent to protected riparian buffers identified within one of the NC Riparian Buffer Protection Rules?
6 Yes E No
For a list of options to meet the diffuse flow requirements, click here.
If no, explain why:
Horsepasture River does not have protected riparian buffers.
2. Stormwater Management Plan

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