20200016 Ver 1_UT3 Approach Memo_20200804

Strickland, Bev
From: Jeff Keaton <[e-mail]>
Sent: Tuesday, August 4, 2020 1:59 PM
To: Tugwell, Todd J CIV USARMY CESAW (US); Kim Browning; Davis, Erin B; Haywood,
Casey M CIV USARMY CESAW (USA); Wiesner, Paul; Phillips, Kelly D
Cc: Shawn Wilkerson; Abigail Vieira
Subject: [External] Cross Creek Ranch UT3 Approach Memo
Attachments: Cross Creek - UT3 Approach -Tech Memo.pdf
Follow Up Flag: Follow up
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All — One of the outcomes of the Cross Creek Ranch post -contract site visit was a request by members of the IRT that the
treatments and crediting for the different sections of UT3 be planned and discussed in a memo to be sent out to the
IRT. Here is the comment from the post contract meeting summary:
UT3 was walked from upstream to downstream, and it was noted by the IRT that the reach is in varying condition which
will require fluctuating levels of treatment and design. Wildlands will provide a follow-up memo including a map and
table that outline lengths, approaches, and associated crediting ratios for UT3 and provide it to NCDMS and the IRT for
approval prior to major design efforts.
The follow-up memo is attached. We look forward to your feedback on this memo and specifically if you agree with our
proposed approach and crediting for the stream. Please let us know if we can move forward with the 2.5:1 credit ratio
for the entire UT3 stream and the treatments we have proposed for that stream. Please feel free to contact me if we
need to discuss. Thanks.
Jeff Keaton, PE I Senior Water Resources Engineer
0:919.851.9986 x103 M: 919.302.6919
Wildlands Engineering, Inc.
312 West Millbrook Road, Suite 225
Raleigh, NC 27609

wo.*
WILDLANDS
ENGINEERING
Technical Memorandum
Prepared for: Interagency Review Team
Project Title: Cross Creek Ranch Mitigation Site
Project No: NCDMS Project No. 100138
USACE ID: SAW-2020-00051
NCDEQ Contract No. 7879-01
Subject: UT3 Approach and Crediting
Date: July 30, 2020
Todd Tugwell, USACE
Kim Browning, USACE
Erin Davis, NCDEQ
To: Paul Wiesner, NCDMS
Kirsten Ullman, NCDMS
Kelly Phillips, NCDMS
Casey Haywood, USACE
Abigail Vieira, Project Engineer
From: Jeff Keaton, Project Manager
INTRODUCTION
The purpose of the Technical Memorandum is to describe the recommended approaches and crediting for UT3
at the Cross Creek Ranch Mitigation Site (Site). On January 13, 2020, the Interagency Review Team (IRT) and
Wildlands Engineering (Wildlands) walked the site and noted that there were varying conditions along UT3 that
require different levels of treatment and design approaches. The IRT requested a follow-up memo to outline
lengths, approaches, and associated credits for UT3 prior to beginning design efforts. This memo includes a
narrative and figure describing the recommended treatment approach and two options for mitigation credits.
OBSERVATIONS
Wildlands walked UT3 on June 3 and July 7, 2020 to assess the stream and map the beginning and end points of
different treatment approaches. Sections in need of restoration and enhancement II measures were identified
along with two areas of preservation. In total, 7 approach breaks were identified (Figure 1). Each section is
described in detail below.
For the purposes of this memo, each section of stream with a different proposed approach is referred to as a
reach. However, the final design reaches will be established during design and discussed in the mitigation plan.
The existing conditions and proposed approach of each reach are described below:
WCross Creek Ranch Mitigation Site
Technical Memorandum

Raarh 1
Wildlands identified the ephemeral/intermittent break of Reach 1 just
downstream of a perched culvert. Below the culvert it is severely incised and
eroding, with multiple active headcuts migrating upstream. The wide forested
buffer on the right is dominated by sweetgums and lespedeza while the
narrow, forested corridor along the left bank has localized spots of mature
Chinese Privet and multiflora rose. Restoration is proposed for Reach 1. Note
that if the jurisdictional determination includes channel upstream of the
culvert, that portion of the reach will be included in the project and treated as
enhancement II.
Reach 2
Reach 2 is moderately incised with localized areas of erosion. A headcut at the
end of the reach is keeping the channel bed stable at this time. It is likely that
the headcut will continue moving upstream through reach 2 over time if not stabilized. In the upper part of the
reach, lespedeza exists along the forested right floodplain. Chinese Privet and mature multiflora rose are found
throughout the entire reach. Enhancement II is proposed for Reach 2.
RParh
Reach 3 begins at the headcut at the end of Reach 2. The stream winds
through an old pond bed and has downcut through a failed dam. The stream is
actively headcutting and eroding through legacy pond bed sediments.
Vegetation along the reach is dominated by lespedeza and mature Chinese
privet. Restoration is proposed for Reach 3, which will include stabilizing the
headcut at the upstream end of the reach. The current plan is to remove the
entire dam and use the material to fill in the old channel along the restoration
reaches.
Reach 4
Reach 4 has moderate incision and erosion. Several headcuts exist throughout
the reach. Invasive species such as tree of heaven, Chinese privet, multiflora
rose, and Princess Tree are found along the reach. Enhancement II is proposed
for Reach 5, which will include headcut stabilization.
Reach 5
Reach 5 has mild incision in some areas and few areas of localized
erosion. Overall, the reach is stable with good pattern and substrate
and access to its floodplain. The riparian buffer along this reach is
wide and composed of Tulip Poplars and Eastern Red Cedars.
Treatment of Chinese privet and multiflora rose will be required in
localized areas of the floodplain. Preservation is proposed for Reach 5.
WCross Creek Ranch Mitigation Site
Technical Memorandum

Reaches
A headcut at the end of Reach 5 marks the beginning of Reach 6. This section
of UT3 moderately incised. Banks exhibit mild erosion but are well vegetated.
Chinese Privet and multiflora rose can be found various sections along the
reach. Enhancement II is proposed for Reach 6.
Reach 7
Reach 7 is generally stable and is well connected to its floodplain. Banks are
laid back with good vegetation. Treatment of Chinese privet and multiflora
rose will be required in localized areas of the floodplain. Preservation is
proposed for Reach 7.
PROPOSED TREATMENTS
Restoration, enhancement II and preservation approaches are all proposed
along UT3. Restoration measures include raising the stream bed to connect the stream to the historic floodplain,
realigning the stream to a more stable morphology, sizing new cross sections with appropriate dimensions,
installing grade control structures such as constructed riffles and log sills, and installing bank revetments such as
brush toes. Enhancement II measures include repairing localized bank erosion, stabilizing headcuts, and adding
habitat features to the channel. Restoration and Enhancement II approaches will include planting of native
hardwood tree species, and removal of invasive species such as Chinese privet and Japanese honeysuckle, as
well as, the removal of sweetgum stands from the riparian buffer. The preservation approach will include
removal of invasive species if needed. All three approaches will require fencing to exclude livestock.
RECOMMENDED CREDITS
The table below shows credits for UT3 based on the approaches depicted in Figure 1 and discussed above.
Table 1. Potential Mitigation Credits for UT3
Reach
Existing
Length (feet)
Approach
Proposed
Length (feet)
Ratio
Mitigation
Credits
Reach 1
752
Restoration
792
1.0
792
Reach 2
550
Enhancement II
550
3.0
183
Reach 3
272
Restoration
181
1.0
181
Reach 4
1325
Enhancement II
1,325
3.0
441
Reach 5
182
Preservation
182
10.0
18
Reach 6
214
Enhancement II
214
3.0
71
Reach 7
321
Preservation
321
10.0
32
Total
3,565
1,718
However, Wildlands proposes to do the work by reach described above but to apply a 2.5:1 credit ratio to the
entire length of UT3. Under this scenario, the entire UT3 stream will likely be considered one reach with an Ell
approach with a mitigation ratio of 2.5:1. This would result in 1,426 credits for this reach as shown in Table 2.
Applying this uniform approach to the stream crediting and reducing the number of UT3 reaches will make
monitoring and reporting more efficient. We look forward to hearing if the IRT is in favor of this proposed
crediting approach.
Table 2. Proposed Mitigation Credits for UT3
Reach
Existing
Approach
Proposed
Ratio
Mitigation
Length (feet)
Length (feet)
Credits
UT3
3,607
Enhancement II
3,565
2.5
1,426
WCross Creek Ranch Mitigation Site
Technical Memorandum

Figure 1 UT3 Concept Approach
%kW I L D LAN D S 0 200 400 Feet Cross Creek Ranch Mitigation Site
w E N G I N E E R I N G Yadkin River Basin 03040104
Montgomery County, NC