20210947 Ver 1_Pre-Filing Meeting Information_20210511

Thu 9f3I2l 20 9:53 AM
• Bailey, David E r USARMY CESAW( A) David.E.Bai1ey a u ace.army.mil>
Accepted: [lion-DoD Source] City of Greensboro streambank stabilization pre -application meeting
Whin Thursday, September 3, 'u 1;DD P r1-? Ci4 ftltC-o5; j Eastern Time (US & Canada.
Loratton Microsoft Teams Meeting
i The meeting was updated after the attendee sent this response_
13ailey, David E CEY LISAPMY CESAW (U5A) has accepted this meeting,

Contact Name: Benjamin Cogdell
Contact Email Address: [e-mail]
Project Owner: City of Greensboro
Project Name: Woodcroft Circle Streambank Stabilization
Project County: Guilford
Owner Address:
2a. Name(s.i on recorded deed:"
David and Kathleen Lambeth
2b. Deed book and page no.:
PB 51, PG81
2c. Responsible party:
.:For Corparaliunx:
2d. Address'
Sv eet Mdresc
4902 Woodcroft Circle
&dr-Ls Ln,•
City
Greensboro
Zip Cxl�
27407
2e. Telephone Number:"
i�lx�u �u.x
stale; Prarin[e! Region
NC
Ccunlry
United States
[phone]
2f. Fax Number:
2g. Email Address:"
[e-mail]

2a. Name(s) on recorded deed:'
Sheila Norwood
2b. Deed book and page no.:
PE51.PG81
2c. Responsible party:
{For Corpurabuesl
2d. Address"
Sire. Address
4900 Woodcroft Circle
Address L'ne
Cary
Greensboro
• Zip C::.:..
27407
2e. Telephone Number:"
AJAX
slate; Province r Region
NC
Country
United States
[phone]
21. Fax Number:
{xrxl� xxcc
2g. Email Address:*
Johnnie. [e-mail]
2a. Name(s) on recorded deed:'
Koury Ventures Limited Partnership
26. Deed book and page no.:
N/A; Parcel Number is 7831755627
2c. Responsible party:
Richard Vanore
2d. Address*
StreetAddrese
2275 Vanstory Street
Address L'ne
Suite 200
cry
Greensboro
Rcslal ! Zip Ccdc
27403
2e. Telephone Number:"
Slab 7 Province /Region
NC
Cour ry
United States
[phone]
21. Fax Number:
2g. Email Address:*
[e-mail]
Is this a transportation project?: No

Type(s) of approval sought from the DWR: "401 Water Quality Certification —Regular"
Does this project have an existing project ID#?: Yes (SAW-2020-01942)
Do you know the name of the staff member you would like to request a meeting with?: Sue
Homewood
Please give a brief project description below and include location information:
The purpose of this project is to construct stream bank stabilization measures along portions of Reddicks
Creek. Stabilization will occur along the existing stream generally paralleling Trailwood Road from
approximately 144 linear feet north of Woodcroft Circle to approximately 267 linear feet north of
Woodcroft Circle.
The site has vegetative cover of grassland and woods with the stream serving as the principal
drainageway for the site. The slopes are generally 4-6% around the stream. The existing stream channel
slopes are generally 100-200%. There is evidence of significant erosion along the existing stream.
Land use in the vicinity of the site is residential. Reddicks creek runs offsite and serves as the outlet for
runoff discharge. Approximately 3,200 acres of area contributes runoff to the construction area.
Please attach the documentation you would like to have the meeting about.
See attached documentation presented during the meeting held September 3, 2020.

ATKINS
Member of the SNC-Lavalin Group
Greensboro Woodcroft Circle
Streambank Stabilization
Alternatives Analysis Report
City of Greensboro
July 9, 2020

ATKINS
Memhp- cf the SnC i_avahn Croup
Notice
This document and its contents have been prepared and are intended solely as information for City of Greensboro
and use in relation to Streambank Stabilization Options. Atkins, NA Inc. assumes no responsibility to any other
party in respect of or arising out of or in connection with this document and/or its contents.
This document has 17 pages including the cover.
Document history
Document title: Alternatives Analysis Report
Document reference: Streambank Restoration
Revision
Purpose description
Originated
Checked
Reviewed
Authorized
Date
Rev 1.0
Streambank stability
JW
KH
AS
AS
4/20/2020
Rev 2.0
SCOURLOK and
Pyrawall Alternatives
JW
KH
AS
AS
5/14/2020
Rev 3.0
GEOWEB Alternative
JW
KH
AS
AS
7/9/2020
Client signoff
Client
City of Greensboro
Project
Greensboro Woodcroft Circle Streambank Stabilization Stream Stabilization
Job number
100068937
Client
signature/date
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 2 of 17

ATKINS
Member of the SNC.Lavahn Group
Contents
Chapter Page
1. Project Description 4
2. Design Considerations 4
3. Potential Erosion Countermeasures 6
4. Stream Stabilization Alternatives 10
5. Recommended Alternative 13
Appendix A: Cost Estimates 15
Tables
Table 3-1 Erosion Countermeasure Options 10
Table 5-1 Stream Stabilization Options 14
Figures
Figure 1-1 Location Map 4
Figure 1-2 Project Area Map 4
Figure 2-1 Looking downstream from the Powerline Easement 5
Figure 2-2 Reddicks Creek behind 4902 Woodcroft Circle 5
Figure 2-3 Looking upstream from 4902 Woodcroft Circle 5
Figure 3-1 Articulated Concrete Block 6
Figure 3-2 Articulated Concrete Block Wet Bottom 7
Figure 3-3 Gabon Basket Wall 7
Figure 3-4 Reno Mattress 8
Figure 3-5 GEOSYSTEMS — GEOWEB 9
Figure 3-6 GEOSYSTEMS — GEOWEB Cross Section 9
Figure 4-1 Reddicks Creek Topographic Survey 11
Figure 4-2 Alternative 1: Gabion Armored Cross Section 11
Figure 4-3 Alternative 2: Channel Reshaping and Flexamat Armored Cross Section 12
Figure 4-4 Alternative 3: PYRAWALL and Rip Rap Cross Section 13
Figure 4-5 Alternative 4: GEOWEB and Rip Rap Cross Section 13
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 3 of 17

ATKINS
Member of the SNGLavalin Gmop
1. Project Description
The City of Greensboro tasked Atkins, NA with the evaluation and design of streambank restoration
options for the property at 4902 Woodcroft Circle along Reddicks Creek. The creek behind 4902
Woodcroft Circle has experienced the erosion of the streambank and trees have fallen into the creek.
This section of creek is mapped by FEMA/NCFMP as 'Zone AE with Floodway', which indicates that any
work performed within the floodway shall be accomplished without raising the regulatory floodplain
elevation. General project location map as well as zoomed in project area map are presented as
Figures 1-1 and 1-2 respectively. As seen in the figures, Reddicks Creek crosses a golf course and
powerline easement before making a 90 degree turn behind 4902 Woodcroft Circle. The creek bends
through the private residence and continues behind homes to and across Grandover Parkway.
Figure 1-1 Location Map
2. Design Considerations
Figure 1-2 Project Area Map
As seen in Figures 2-1 through 2-3, the stream erosion begins as the creek crosses the powerline
easement and makes a sharp 90-degree bend and goes behind 4902 Woodcroft Circle. As seen in the
figures, the side bank is not stable enough to contain the energy of the creek as it makes the 90-degree
bend and continues to meander behind property at '4902 Woodcroft Circle'. This has led to trees falling
in the creek and erosion that will continue to progress as the stream seeks to find a stable configuration
to handle the creeks flow.
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 4 of 17

ATKINS
Memhp- cf the SrC i_avahn Croup
Figure 2-1 Looking downstream from the Powerline Easement
Figure 2-2 Reddicks Creek behind 4902 Woodcroft Circle
Figure 2-3 Looking upstream from 4902 Woodcroft Circle
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 5 of 17

ATKINS
Member of the SNGLavalin Gmop
3. Potential Erosion Countermeasures
Based upon the field visits to the site and analysis of the effective model hydraulic model and project
survey conditions, it was determined that leaving the side bank in its current condition will lead to
continual erosion. As such, design alternatives were considered that served to hard armor the bend in
Reddicks Creek and behind 4902 Woodcroft Circle. These included articulated concrete block mat
(ACBM) and PYRAWALL. Each of these selected countermeasures can withstand the 100-year design
storm velocity in the stream of 6 fps.
The following is a discussion of each measure. Sheet Pile wall was not considered here as the site
conditions of the creek are far enough from structures that installation of less expensive alternatives that
maintain the existing shape of the channel were preferred.
Articulated Concrete Block Mat
Articulated Concrete Block Mat (ACBM) consists of concrete blocks tied together with metal cables,
pictured in Figure 3-1. ACB designs come in a variety of block sizes and use either open or closed cell
blocks. Open cell blocks can be filled with gravel (to prevent vegetation) or soil and vegetated. They
can be designed to withstand a variety of velocities, all within the limits of this project. The slope on
which the product is installed must be stable, as the product does not create slope stability, but provides
armoring to prevent erosion. Typically, 1:2 slopes provide sufficient stability, but installations on 1.5:1
slope have been accomplished, depending on site conditions or with the use of soil anchors. Featured
below are two different types of ACBM's one is a larger thicker mat and the other utilizes smaller blocks.
(source: http://www.conteches.com/)
(source: http://www.flexamat.com)
Figure 3-1 Articulated Concrete Block
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709
Page 6 of 17

ATKINS
Member of the SNGLavalin Gmop
As pictured in Figure 3-2, in predominantly wet channel bottom conditions, the channel bottom can
either be left bare, or lined with rip rap.
Figure 3-2 Articulated Concrete Block Wet Bottom
Gabion Wall
Gabions and Reno mattresses are streambank stability options that present hard armoring of a channel
bed or side slope against erosion. They consist of rocks filled in baskets linked together to form a wall or
side slope lining. Seen in Figure 3-3 below, the gabions contour the side slope and form a protective
wall along the stream and are an effective when the slope is steep (1.5:1 or steeper). In contrast to Reno
Mattresses, seen in Figure 3-4, which are not stacked in blocks but rather laid along the bottom or side
bank of a channel are effective where slopes are 1.5:1 or shallower.
Figure 3-3 Gabon Basket Wall
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 7 of 17

ATKINS
Figure 3-4 Reno Mattress
PYRAWALL
Member of the SNGLavalin Gmop
PYRAWALL is a vegetated stability option that includes a high-performance turf mat with an internal
brace to create a stabilized wall made from consecutive lifts of the soil wrapped PYRAWALL. This
stackable vegetated configuration crates a permanent structural barrier against channel erosion. It differs
from the Gabion products in that PYRAWALL encourages vegetation growth as an element to the
structural stability of the overall system and has a more natural final appearance. Seen in Figure 3-
5 below, the PYRAWALL product cells contour the side slope and form a protective wall along the
stream and are effective when the slope is steep.
Figure 3-5 PYRAWALL — Vegetated Soil Wrap
GEOWEB
GEOWEB is a soil or aggregate filled geocell system that provides slope stability and promotes
vegetation growth. Comprised of High -Density Polyethylene (HDPE) and installed on slopes as steep as
2:1 to create an environmentally friendly and sustainable side slope reinforcement. Seen in Figure 3-6
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 8 of 17

ATKI N S
Memher sf the SNC Lavalln Croup
and Figure 3-7 below, the GEOWEB cells contour the side slope and form a protective wall where
vegetation can take hold. To hold the wall in place on 2:1 slopes a combination of Tendon connectors
and dead man anchors are integrated into the design to ensure GEOWEBs are evenly spaced and retain
their configuration.
Figure 3-5 GEOSYSTEMS — GEOWEB
Tendon
Geomembrane
ATRA= tendon clip
Figure 3-6 GEOSYSTEMS — GEOWEB Cross Section
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 9 of 17

ATKINS
Member of the SNGLavalin Gmop
Table 3-1 summarizes their pros and cons of each measure.
Table 3-1 Erosion Countermeasure Options
Alternative /
Comparison
Articulated
Concrete Block
Mat (ACBM)
PYRAWALL
GEOWEB
Gabions
Benefits
• Hard armor
• Self -healing
• 50-year +design
service life
• Rough surface
reduces velocities
• Flexible armor
• Can closely mimic
steep bank slopes
• Provide space for
vegetative growth
• Can closely
mimic steep
bank slopes
• Promotes
vegetation
growth
• Hard armor
• Can closely
mimic steep
bank slopes
• Provide space
for vegetative
growth
Risks / Issue
• Manufacture
recommends 2:1
or flatter slopes
• Anchors typically
required on slope
steeper than 2:1
• Requires channel
regrading to
achieve stable
slope.
• Requires stable
foundation
• Installation
requires
dewatering and
excavation
• Manufacture
recommends
2:1 or flatter
slopes
• Anchors and
connecting
tendons
required for
2:1 slope
installation
• Requires
channel
regrading to
achieve stable
slope
• Snags can
occur
• Stability of
structure if
foundation is
undermined
• Installation
requires
dewatering
and excavation
• Aesthetics
Cost
• $ $$
• $$
• $
• $$$
4. Stream Stabilization Alternatives
Based on our review of the site, field survey, hydraulic model, and potential erosion control
countermeasures which could be utilized at this site, three design alternatives were considered to hard
armor the stream bank behind 4902 Woodcroft Circle. Site survey with contours and referenced cross
section locations is shown in Figure 4-1 and a representative cross section of the alternatives are listed
below are shown in Figures 4-2 through 4-5 and include:
1. Lining the existing channel with Gabions Walls on the steep side slopes and Reno Mattresses to
stabilize the channel bottom. A modification to the concept may be to use Reno Mattress on the
side slopes where it is 1.5:1 or milder in lieu of Gabion Wall.
2. Re -grading the channel center line to have a milder bend and extending the cross section to
enable a 2:1 or milder slope, provides a hydraulic section similar to the existing condition in cross
sectional area, but with a more stable configuration. Armoring the stable slope with Flexamat or
similar will maintain the channel configuration during high and low flows. As part of the final
design consideration, the channel bottom could be lined with rip rap or left bare.
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 10 of 17

ATKINS
Member of the SNC.Lavahn Group
3. To maintain a vegetated condition within the banks of the channel, this alternative regrades the
channel banks to have a milder 2:1 configuration reinforced with PYRAWALL to secure the
channel configuration against erosion and Rip Rap to stabilize the bottom of the channel.
4. UPDATE 7/1/2020 — Similar to the PYRAWALL option, to maintain a natural section this
alternative uses, GEOWEB cells filled with natural soil for cells above the water line and
aggregate below the waterline. Within the project footprint, behind 4902 Woodcroft Circle, the
creek will be reconfigured to smooth out the bend and limit the stream side slopes to a maximum
of 2:1. For added stability Rip Rap will line the channel bottom.
NOTE: FULL SURVEY NEEDS TO EXTEND AROUND THE BEND IN THE CREEK TO THE POWER
LINE EASEMENT
Figure 4-1 Reddicks Creek Topographic Survey
Figure 4-2 Alternative 1: Gabion Armored Cross Section
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 11 of 17

ATKINS
Member of the SNC.Lavahn Group
750
740
730
I /20
Section: 400 linear feet
EXIST.
GROUND
ipm•
iota
Wail
K.TAIFrir
ii
j
�•ri
- GASION
rIYr�«.
I±rT�j
,,,
...,...�grope�
�J=s
I�
MATTRESS
GAB ION
-40 -30 -20 -10 0 10 20 30 40 50 60
Figure 4-3 Alternative 2: Channel Reshaping and Flexamat Armored Cross Section
f50
750
740
730
720
Section: 400 linear feet
FLEXAMAT
EXIST_
GROUND
—
r
I
—20 —10 0 10 20 30 40 50 60
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 12 of 17

ATKINS
Figure 4-4 Alternative 3: PYRAWALL and Rip Rap Cross Section
74J
720
Section: 400 linear feet
EXIST_
GROUND
e?�
1:,
PyraMat
Rip
Rap
-50 -40 - i --20 -10
0 10 20 30 40 50 60
Figure 4-5 Alternative 4: GEOWEB and Rip Rap Cross Section
/60
i20
Memher cf the SnC i_avahn Croup
Typical Section: 230 linear feet
EXIST.
GROUND
GEOWEB
-'
`�
•''.
•.
i
Rip
Rap
-50 -40 -30 -20 -10
5. Recommended Alternative
0 10 20 30 40 50 60
To generate the most stable slope in the most cost-effective manner, re -grading the slope to a 2:1 and
armouring with ACBM (Flexamat) is the recommended alternative. Without reshaping the channel, the
use of SCOURLOK to armor the site is a viable option as it provides a permanent solution and contours
the slope of the existing channel to minimize impacts to floodway elevations, while providing a natural
vegetated condition within the project corridor. Notes and approximate costs are compared in Table 5-1
and cost details are presented in Appendix A.
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 13 of 17

ATKINS
Memher sf the SNC Lavalln Croup
UPDATE 7/1/2020 — Based upon discussions with the City, alternative 4 was added that combine a
natural appearance and promoting vegetation growth and is the recommended alternative for this site.
This alternative limits the project footprint to the property within the City's jurisdiction, behind 4902
Woodcroft Circle reducing the project length from 400 ft to 230 ft.
Table 5-1 Stream Stabilization Options
Stabilization Option
Cost
Notes
Alternative 1
(Gabions and Mattresses)
$855 k
No Restrictions.
Alternative 2
(Flexamat)
$149 k
Requires Stream regrading
Alternative 3
(PYRAWALL)
$246 k
Promotes vegetation growth. Requires
Stream regrading.
Alternative 4
(GEOWEB)
$121 k
Promotes vegetation growth. Requires
Stream regrading and tree removal.
Note: Estimated costs are rounded and do not include excavation, embankment or dewatering. They are
for rough estimation purposes only.
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 14 of 17

ATKINS
Appendix A: Cost Estimates
Alternative 1 Gabions and Mattresses
Pay Item #
Descript on
Unit
Quoddy
Unit
Amount
Gabions
CY
1557
5 400.00
$ 62,800.00
Gabion Mattress
CY
119
5 400.00
5 47,600.00
Clearing and Grubbing
SY
1917
$ 2.00
$ 3,833.33
Performance Turf, Sod
SY
1022
$ 3.00
$ 3L066,67
Sub -Total
677,300.00
Mobilization
LS
1
-
$ 20,000.00
Maintenance of Traffic {MDT}
LS
_ 1
-
$ 5,000.00
Erosion Control
LS
1
$ 10,000.00
Sub -Total
35,000.00
Continoencv (20%)
Grand Total
Sul -Total $ 712,300.00
$ 142,460.00
$ 854,760.00
Note: Does not include excavation or embankment quantities or dewatering, for rough
estimation purposes only
Alternative 2 Flexam3t
Pay item #
Deeaiptine
Unit
auartUty
Unit $
Amount
Flexamat
SY
997
5 80.00
$ 79,733.33
Clearing and Grubbing
SY
?,333
5 2.00
$ 6,665_67
Performance Turf, Sod
SY
1 022
5 3.00
$ 3,065,67
Sub -Total
$ 89,4.66.67
Mobilization
LS
1
-
20,000,00
Maintenance ofTraffic (MOT)
LS
1
-
5 5,000.00
Erosion Control
LS
1
5 10,000,00
Sub -Total
$ 35,000.00
Contingency (20%)
Grand Total
Sub -Total $ 124,466,67
24,893.33
$ 149,360.00
Note: Does not include excavation or embankment quantities or dewatering, for rough
estimation purposes only
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 15 of 17

ATKINS
Member of the SNC.Lavahn Group
Alternative 3 l'YRAW A.I 1
Pay Item #
Description di
Unit
Quantity
Unit
Amount $
PyraWall
SF
5520
$ 25.00
$ 138,000.00
RipRap
CY
85
•
$ 300.00
$ 25,50000
Clearing and Grubbing
SY
1917
$ 2.00
$ 3,833.33
PerformanceTiurf,Sod
SY
1022
$ 3.00
$ 3,066.67
Sub -Total
$ 170,400,00
Mobilization
LS
1
-
$ 20,000.00
Maintenance ofTraffic (MOT)
LS
1
-
$ 5,000.00
Erosion Control
LS
1
$ 10,000.00
Sub -Total
$ 35,000.00
Continency (20%)
Grand Total
Sub -Total 205,400.00
$ 41,080.00
$ 246,480.00
Rote: Does not include excavation or embankment quantifies or dewatering, for rough
estimation purposes only
+litern.3tra 4 GEOWEB
Pay Item #
Description
Unit
Quantity
Unit $
Amount $
GEOWEB
SF
5520
S 5.00
$ 27.500.00
RipRap
CY
85
$ 300.00
$ 25.500.00
Clearing and Grubbing
SY
1.917
$ 5.00
$ 9,583.33
Performance Turf, Sod
SY
1022
$ 3.00
$ 3.066.67
Sub -Total
$ 65,750.00
Mobilization
LS
1
-
$ 20.000.00
Maintenance of Traffic 0.1OT)
LS
1
-
$ 5,000.00
Erosion Control
LS
1
$ 10,000.00
Sub -Total
S 35,000.00
Ccntingencv (20%]
Grand Total
Sub -Total $ 100.750.00
$ 20.150.00
S 120,900.00
Note: Does not include excavation or embankment quantities or dewatering, for rough
estimation purposes only
Streambank Restoration 11.0 I July 9, 2020
Atkins I Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 16 of 17

ATKINS
Memhp- cf the SnC i_avahn Croup
Atkins, North America Inc.
1616 East Millbrook Road,
Suite 160
Raleigh, NC 27609-4968
©Atkins, NA Inc. except where stated otherwise
Streambank Restoration 1 1.0 1 July 9, 2020
Atkins 1 Rev -Greensboro Woodcroft Cir Alternatives Analysis-20200709 Page 17 of 17