20170175 Ver 1_Appendix C_Clear Run Final EA_20201029

Clear Run Stream
Restoration and Flooding
Management Project
Draft Environmental
Assessment
Presented to:
City of Wilmington
September 23, 2020
Version 3.1
Prepared by:
hdhq
rnoffati & nichol

Clear Run Stream Restoration and Flooding Management Project
nrnft Fnvirnnmantal Accaccmant
Table of Contents
1. Introduction.................................................................................................................................................. 1
2. Alternatives................................................................................................................................................... 5
3. Environmental Setting and Potential Impacts............................................................................................. 9
4. Cumulative Impacts................................................................................................................................... 27
5. Compliance with Environmental Requirements......................................................................................... 27
6. Agency and Public Involvement.................................................................................................................. 27
7. Point of Contact......................................................................................................................................... 28
8. Draft Finding of No Significant Impact........................................................................................................ 28
9. Bibliography................................................................................................................................................ 28
10. Appendices............................................................................................................................................... 29
Moffatt & Nichol TOC

Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
1. Introduction
1.1. Purpose and Need
The project's overall purpose and need is to design and install a stable stream channel that can safely
accommodate high flows from upstream development and alleviate flooding along the channel. The project
intends to address a number of factors through implementation. First, the stream channel is very unstable
and actively eroding. This both contributes sediment to downstream reaches of Bradley Creek and threatens
adjacent property and existing structures. The actively erodding and unstable stream channel has been the
subject of numerous complains from adjacent landowners. Second, flooding is common at locations in the
upper watershed, notably along College Avenue and New Center Drive. A planned subsequent project will
enlarge the stormwater pipes in this area to carry more stormwater to alleviate the flooding, but the channel
in this reach will need to be designed to accommodate these higher flows. Third, hydrologic and hydraulic
modeling analysies indicate that road flooding is likley to occur at College Acres Drive and Mallard Drive
during large storms. Some anedotal accounts of such flooding has been reported in the course of the
community outreach process for the project. This project will address this flooding by providing larger
culverts under these roads. Proposed improvements from this project include installation of a more stable
stream channel with a restored floodplain to accommodate high storm flows and improved road crossings at
College Acres Drive and Mallard Drive.
1.2. Project History
This project largely originated from citizen/landowner complaints coming from residents in the 5000 block of
Clear Run Drive, at the upstream end of the proposed project near the intersection with College Acres Drive,
where increasing channel erosion and instability is resulting in rapid lateral migration of the existing channel.
In this vicinity, where the width of the riparian corridor is constrained by numerous anthropogenic
structures, channel migration had begun to immediately threaten the integrity of swimming pools and out-
buildings. The project vicinity, location, and extent are illustarted in Figure 1 (following page).
At the project outset, a detailed geomorphic assessment was performed (discussed below in section 1.3) that
confirmed that the stream was badly incised with rapidly eroding stream banks. Anecdotal accounts from
long-term residents living along the unstable upstream portion of Clear Run (Keir, personal communication,
2014) (Seidel, personal communication, 2014) have indicated that a low -head dam had been present in Clear
Run near the property of Dan Keir at 5114 Clear Run Drive. The accounts indicated that the dam was
removed, but the specific timeframe for removal was unknown. As discussed below, the geomorphic
assessment data confirmed the presence of a transition zone in the vicinity of the potential historic dam
location where the stream changed from an incised and unstable channel to one with much lower bank
heights, improved floodplain connectivity, and lateral stability. The current geomorphic conditions in upper
Clear Run are consistent with those of a stream that may have experienced a vertical disturbance of the
stream bed, such as dam removal, which subsequently resulted in a head cut migrating up through the
headwater section, resulting in sudden incision and active stream erosion.
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Clear Run Stream Restoration and Flooding Management Project
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
Driven by chronic flooding problems in the upper portion of the watershed in the vicinity of College Road and
New Center Drive, and the resident complaints in regard to the instability of Clear Run Branch near College
Acres Drive, the City of Wilmington engaged Moffatt & Nichol in 2011 to perform a study of hydrologic and
hydraulic conditions within the watershed and develop a watershed plan to address the issues. The resulting
report (Moffatt & Nichol, 2012) identified the need to increase the hydraulic capacity of the predominantly
closed -pipe drainage system in numerous locations in the upper portion of the watershed and the need to
perform stream stabilization and restoration in the open -channel portion of Clear Run Branch downstream of
College Acres Drive. The study gave rise to the current project.
1.3. Design Objectives
As much or more than any other priority, the primary design objective for Clear Run Branch is to address and
alleviate drainage problems within the watershed. The design is intended to result in channel and floodplain
dimensions that will accommodate not just the existing storm flows, but the future storm flows that will
result from the drainage improvements planned for the portion for the watershed upstream. Wherever
possible, the design should also seek to alleviate existing problems with nuisance flooding along stream
reaches directly impacted by the project, as proposed. These objectives are being achieved with no increase
in current predicted flood elevations or exacerbation of any existing flooding problems.
Over and above addressing drainage issues in the watershed, the project objectives include design and
implementation of a stable channel that will effectively transport the sediment load supplied by its
watershed while maintaining its pattern and profile, and neither aggrading or degrading. Given the intensity
of the flows that will continue to emanate from upstream during storm events, and the physically
constrained nature of the stream corridor, and to maintain stability, the channel design presented herein
relies on the use of some bio-engineered structures, and even more intensively engineered approaches in
the immediate project headwater area. Further down from College Acres Drive, in the lower portions of the
upper reach, more emphasis has been placed on the use of woody materials for instream structures where
they are necessary. To the extent possible, the design relies on performance criteria set forth by natural
channel design principles to maintain stability.
Habitat and water quality improvement are also project goals. Habitat and water quality will be significantly
improved through the simple act of giving the channel stability and reducing the load of fine sediment
moving through the system. Introduction of woody structures and variable channel bed form will also
improve physical habitat. Opportunities for riparian habitat improvement will also be realized though the
replanting of disturbed sections of the buffer and through removal of invasive plant species throughout the
corridor. A planting plan for the restoration reach is included as Appendix C.
Significant downstream water quality improvement will be realized through the reduction of the large
sediment loads that have been historically transported down to Bradley Creek from active channel erosion in
Clear Run Branch. Citizen complaints from prior to project initiation and comments received in the first
community meeting held for the project have highlighted the problem of sediment being delivered
downstream.
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
1.4. Site Description
The H&H modeling performed and geomorphic assessment data collected thus far have clearly illustrated
that there are four distinct reaches of Clear Run Branch, each of which warrant different treatment in terms
of the engineering and restoration approach utilized. For purposes of this document, four reaches are
discussed to make the very headwater portion of the project distinct, in light of the intensive constrains and
design challenges in that reach. The distinct reaches and the associated recommendations described below
and illustrated in Figure 2.
1.4.1. Headwater Reach
The Headwater Reach consists of the 200 feet of stream above College Acres Drive and the 200 to 300 feet of
stream immediately below it. This reach is characterized by high flows from the commercial area across
College Drive as well as the constraints from existing development. A narrow wooded buffer is present along
most of this section. As described below, this reach has overall low quality (NC SAM) with impaired stream
chemistry and impaired stream biology.
1.4.2. Upper Reach
The Upper Reach consists of approximately 1,500 to 2,000 feet of stream from the Headwater Reach to just
upstream of Myna Circle. This is the severely incised, actively unstable reach of Clear Run Branch discussed in
the previous sections. However, it does have an intact wooded buffer although normal overbank flooding is
restricted by the incised banks. As described below, this reach also has overall low quality (NC SAM) with
impaired stream chemistry and impaired stream biology with high levels of bank erosion (Figure 2, following
page).
1.4.3. Middle Reach
The Middle Reach consists of the next 1,000 to 1,500 feet of stream from just upstream of Myna Circle to just
below it. This is the stream reach where, under existing conditions, Clear Run Branch begins to become
reconnected to its floodplain. This reach is characterized by reduced stream bed slopes and lower velocities
than the upper reach. This reach has improved water quality (as noted below), higher NC SAM ratings, and
moderate bank erosion indices (Figure 2).
1.4.4. Lower Reach
The Lower Reach consists of the remaining 3,000 to 3,500 feet of stream from just downstream of Myna
Circle to the footbridge at Teal Street, the downstream terminus of the project area. In this reach stream
slopes are very low (0.2% or less) and banks are consistently in the range of two feet or less in height. Clear
Run Branch is also well connected to an expansive floodplain within this reach, and the channel appears to be
stable with low to moderate bank erosion indices (Figure 2).
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
2. Alternatives
2.1. Upper Watershed Detention Alternative
Given that restoration and floodplain expansion along upper Clear Run results in significant impacts to the
adjacent landowners, the potential alternative was examined to create enough stormwater detention in the
upper watershed to reduce the flows to a point that would render downstream floodplain expansion
unnecessary. In order to investigate the detention alternative, a flow analysis was performed with the
SWMM model developed for the Clear Run project. The analysis showed that reducing the peak flow from a
25-year storm event by 25% (from 500 cfs to 375 cfs) would require 30 acre-feet of pond storage upstream in
the watershed. Assuming this hypothetical pond (or ponds) has an average vertical storage capacity of 4 feet,
the pond(s) would be 7.5 acres in size. In reality, the actual vertical storage capacity for ponds in this vicinity
is likely closer to 3 feet or less.
All of the 15 existing wet ponds and dry detention/infiltration basins currently existing in the upstream
watershed have a total surface area of 4.5 acres. Given that the 4 detention basins would have lesser vertical
capacity, reducing the 25-year peak flow by 25% would require an approximate doubling of the sizes of all
the existing stormwater BMPs within the built out and highly impervious upper watershed.
Without exception, all of the existing BMPs are surrounded by high -value commercial and high -density,
multi -family housing (apartments and condos). The 15 properties that include stormwater BMPs have a
combined acreage of 122 acres, with a total appraised land value of $27.3M or approximately $224,000/acre
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
(not including buildings). Evaluation of the map of the upper watershed shows clearly that expansion of half
or more of the existing BMPs would require the acquisition and removal of numerous privately -owned
buildings on these properties. With buildings included, the appraised value of the 15 properties in question
approaches $90M. While expansion of the BMPs would not require acquisition of the entire properties (or
removal of all the buildings), it is not difficult to understand that the costs of property acquisition alone for
this endeavor would be in the millions of dollars, before we even consider the cost of design and
construction associated with the expansion of the existing BMPs.
As an example of what this would change downstream, in the lower portion of the section targeted for full
restoration the base width of the proposed floodplain is 75 feet. If one assumes that the 25% reduction in
peak flow, and the resulting reduction in the necessary cross -sectional area of the stream could be realized
solely as a reduction of that base width from north to south, it would reduce the stream cross section and
width of the easement requested from the landowners on the north side of the stream corridor in that
vicinity by a maximum of 19 feet. To put that reduction in perspective, with side cuts to get up to the existing
grade and the 5 feet of buffer space built in, the distance of the easement request for Mr. Kerr would be
approximately 70 to 75 feet from his back property line under the currently proposed condition. In reality,
the 25% flow reduction would not be realized soley as a reduction of the north boundary of the easement. In
the real -world outcome of stable stream geometry, modeling predictions, and engineering, the potential
cross section reduction would not likely be distributed completely along that one side. It is more likely that
some of the reduction in the necessary cross section area would be used to raise the bed of the stream
slightly to accommodate structures in the channel, or it may be necessary to reduce the width of the
floodplain on the south side for sake of stability. Determining the exact reduction in the easement request on
the north side would require a full rework of the grading plan, and in the end it is far more likely to be in the
range of a 12-15 feet reduction on the north side
Even if this amount of storage or more could be realized in the upper watershed portion, the reduction of the
peak flow alone would not be sufficient to address the current channel instability that is a driving factor
behind the project, nor would spot -wise channel repair and armoring (which would only serve to shift the
location of the most unstable and erosive stream reaches further downstream into what are currently more
stable reaches). The only way to truly address the current problem of stream instability is with the
comprehensive adjustment of the floodplain and stream channel geomorphology currently proposed. The
core source of the problem is that the upper watershed, taken in total, is approximately 70 to 80%
impervious. There is no way to accommodate the storm flows from that intensity of imperviousness without
significantly enlarging the floodplain and realigning the base -flow channel to a stable form.
2.2. Spot -Wise Stabilization Alternative
Given that the initial primary driver for this project was the active erosion and instability of the
upper reach of Clear Run, which was actively eroding surrounding properties and threatening
several anthropogenic structures, another alternative that was considered was that of
implementing the minimum measures necessary to render the channel stable in the most
problematic areas. This approach would consist of simply regrading steep and actively eroding
stream banks, to lay them back to much gentler slopes (2:1 or 3:1, where possible), which would be
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
far less subject to erosion. When lateral space permits, bank regrading of this nature will
occasionally allow for re-establishment of intermittently occupied floodplain benches that can
increase channel storage and dissipate erosive stream energy.
However, an initial analysis of this approach revealed that this method could not effectively
dissipate stream energies and streambanks would still be exposed to damaging velocities. The
extent of floodplain that is needed to provide long-term stability cannot be created with a minimal
approach. Even in locations where some lateral expansion could be achieved, a minimal approach
would require armoring regraded banks at the toe of the slope, typically with gabions or rip -rap. In
laterally confined areas, more extensive armoring, potentially to the full height of the bank, would
be required to withstand the adverse impacts of hydraulic energy. Our analysis indicated that
without sufficient floodplain connection, due to the current severely incised condition of the upper
reach, high stream energies would simply propagate downstream, transferring the highly erosive
channel conditions from upstream to new, currently more stable reaches.
In addition, spot repairs of this type would require complex grading transitions that would be
difficult to stabilize. The limitations of this approach are further magnified when combined with the
potential future conditions for this watershed. The measures that will be required to address
chronic flooding problems upstream in the watershed will only increase pressures on the project
reach. While the spot -wise stabilization alternative would alleviate the short-term problems
presenting by the actively eroding and unstable channel, it would do little to prepare the channel
and floodplain for the increase in future stormflows.
Overall, this alternative was viewed unfavorably as a long-term solution in a complex watershed.
The potential adverse stream and riparian habitat impacts resulting from the necessary armoring
and the permitting challenges for those measures also contributed to this conclusion. The
alternative was also viewed unfavorably as such approaches often tend to be more temporary in
nature, often requiring significant maintenance, even reconstruction of some elements, after large
storm events.
2.3. No Action Alternative
The no action alternative would be to not conduct the stream restoration and flooding management project
on this reach of Clear Run. This would not alleviate the periodic flooding at College Acres Drive and Mallard
Drive crossings and not address the unstable and eroding streambanks along the reach. Therefore, periodic
flooding across these roads would continue and the streambank would continue to erode, threatening
adjacent property and structures as well as continuing to supply excessive sediment to downstream waters.
In addition, when the stormwater management project in the upstream developed area is installed,
additional flow would enter the channel and result in more flooding and streambank erosion. Therefore,
without the stream restoration and flooding management project, the existing channel will experience
additional degradation.
Clear Run drains to Bradley Creek proper below the Lower Reach. Bradley Creek is classified as a Primary
Nursery Area (PNA). The sediment that enters Bradley Creek from streambank erosion in the Clear Run
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
watershed has a negative environmental effect on the functioning of this PNA. Stabliization of the banks of
Clear Run will improve the functioning of the downstream Bradley Creek PNA.
2.4. Preferred Alternative - Stream Restoration and Floodplain Modification
Headwater Reach — This reach is above College Acres Drive to about 200 feet below the road. The design
requirements in this section are driven by the need to receive storm flows coming from the upper watershed
to the stormwater outfall at the project area's headwater end. The stream must be designed to withstand
the high energy of those flows and is challenged by significant lateral constraints imposed by residential
structures on either side of the stream, as well as the large sanitary sewer line located to the immediate right
of the stream. The design in this area will also be driven by the replacement of the culvert under College
Acres Drive and the introduction of improved stormwater conveyances along College Acres Drive from both
sides of the stream project. Given the very narrow corridor available for the stream between the residential
structures and the sewer line in this reach, and the active threat that the unstable channel presents to that
infrastructure, it is likely that it will be necessary to extend the length of the culvert downstream to enclose
the channel for the 200 feet segment upstream of College Acres Drive and for the first 210 feet downstream
of College Acres Drive. The culvert will transition to a heavily confined channel utilizing block wall or gabion
structures to contain the high energy flows leaving the enclosed structure, which could be followed by a
series of boulder step -pools that would reduce erosive stream power.
Upper Reach — This reach is about 1,500 to 2,000 feet long from the lower end of the headwater section to
just upstream of Myna Circle. Given the peak flows and high energy gradients coming from upstream, the
first 300-500 feet of this reach may require implementation of step -pool sequencing using substantial rock
structures. The step -pools will allow for energy dissipation and the more rapid descent of the stream bed
elevation that will be necessary in this section of the stream. In this section, the design will transition as
quickly as possible from step -pools of gradually decreasing frequency to a stream with new dimension,
pattern, and profile, as well as an active floodplain at or near the existing stream grade (Priority 2
Restoration). Once the transition to an active floodplain system occurs and stream bed slopes lessen, the
next 1,000 to 1,200 feet will rely less on rock vanes and more on woody structures to control hydraulic
energy and maintain a stable channel. Implementation of an active floodplain throughout this reach will
directly impact adjacent landowners and require numerous easements. A planting plan is included as
Appendix C.
Middle Reach — This section is the next 1,000 to 1,500 feet of stream, which starts to become connected to
the adjacent floodplain/wetland since it is less deeply incised. In this reach, full channel restoration to
achieve a new dimension, pattern, and profile is unwarranted. However, within this reach, many remnant
spoil piles deposited along the riparian corridor act to restrict the stream access to portions of the floodplain
and reduce floodplain storage. Within this reach, design recommendations include removal of the spoil piles
and construction of a new floodplain bench along portions of the stream to increase floodplain connectivity
and storage capacity. Recommendations also include localized bank stabilization where necessary and
removal of invasive plant species. All areas disturbed as a result of these improvements would be
revegetated with targeted native plant species.
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Clear Run Stream Restoration and Flooding Management Project
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Lower Reach —This section is the lower 3,000 to 3,500 feet of the reach where the channel is less incised,
more stable, and well connected to the adjacent wetlands. Within this reach, the most significant design
change planned is the replacement of the aging culvert at Mallard Drive. Increasing the culvert capacity will
reduce tailwater impacts within this reach, which should reduce the flood risk to surrounding structures. We
also recommend removing invasive species and replanting the riparian buffers with targeted native species in
disturbed areas.
Clear Run drains to Bradley Creek proper below the Lower Reach. Bradley Creek is classified as a Primary
Nursery Area (PNA). The sediment that enters Bradley Creek from streambank erosion in the Clear Run
watershed has a negative environmental effect on the functioning of this PNA. Stabliization of the banks of
Clear Run will improve the functioning of the downstream Bradley Creek PNA.
3. Environmental Setting and Potential Impacts
3.1. Geomorphology, Sediment, and Erosion
3.1.1. Regional Curve Data Comparison
Stream channel dimensions for Clear Run Branch were compared to the regional curves developed by the
NCSU Stream Restoration Program (Doll, et al 2002). The curves provide stream flow and geometry
information from a database of many NC streams. While the curves were generated primarily for rural
streams, and urban streams typically have larger cross sections, these numbers can provide a meaningful
baseline for depicting the degree to which the channel dimensions within the project reach might be a
departure from a more natural condition. From the curve data, the bank -full flow rate of a coastal plain
stream with a drainage area of 2 to 3 square miles, similar to Clear Run Branch, would be between 30 to 40
cfs. This is the flow rate where natural flooding would begin to occur.
Based on the regional curve data, the depth of a natural Coastal Plain stream would range from 1 to 2 feet,
and the width from 15-20 feet. Based on that reference data, some sections of the stream, particularly in the
upper reach are incised far deeper than a natural stream would be with a less disturbed watershed. When
compared to the entire database of data collected for the curve study, only a few streams had depths greater
than 3 feet or slopes greater than 0.3%. This comparison is an indicator of the departure throughout much of
the project length from a natural system. The dimensions and capacity found currently are much closer to
rural piedmont streams than coastal stream sites, which points to the need to manage channel capacities and
provide suitable floodplain areas to restore stability to this system.
3.1.2. Cross Section Analysis
A more detailed analysis of individual cross sections along the project reach has also been completed. A total
of 20 cross sections were set up and surveyed to determine dimensions and geomorphic properties. The
measurements made from these cross sections provide additional detail to guide design decisions. The data
provides depths and widths of features such as point bars, inner berms, and bank -full indicators that help
inform design dimensions. Table 1 shows a summary of the initial cross section results.
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
Table 1: Geomorphic Survey Summary
Top of Bank Top of Bank Bank -full XS
Depth (feet) Width (feet) Area (square feet)
Bank -full Bank -full Depth
Width (feet) (feet)
MIAMI'
noted in the original observations, the depth to the top of bank in the upper project reach is substantial.
The depth ranges from 9.4 feet leaving the culvert and lowers to 5.6 feet near the middle reach. The depth
drops rapidly until it levels out around 2 feet in depth in the lowest reach. A corresponding decrease in the
top of bank width is also seen from the project's upstream to downstream portions. Upper reaches with
unstable banks are sloughing and widening to widths of 26 feet and up to 43 feet. Channel dimensions in the
lower project reaches tighten up as bank heights decrease and floodplain access increases. Lower reaches
also have consistently vertical banks that are held stable by dense vegetation.
Average channel dimensions across all reaches of the project area show cross sectional areas of 23 to 27
square feet, bank -full widths of 17 feet, and bank -full depths of 1.25 to 2.3 feet. These numbers compare
very well to the coastal regional curves (mentioned previously). Using the database and a drainage area of 2
to 3 square miles, cross sectional area is between 20 to 30 square feet, widths are between 15 to 20 feet, and
depths are 1 to 2 feet. Based on the results of this portion of the geomorphic survey, there is substantial
evidence that the unstable portions of Clear Run Branch are attempting to evolve towards dimensions that
are commonly found in coastal plain streams. One goal of the final restoration plan will be to speed up this
process of evolution by re -designing stretches that need the most change to mimic a more natural and stable
form.
3.1.3. Bank Erosion Hazard Index Assessments
To fully evaluate the change in bank erosion conditions across the project area, 27 sites were assessed
utilizing the Bank Erosion Hazard Index (BEHI) method (Rosgen, 2001). The results of the BEHI assessment are
shown geographically in Figure 3 (following page). The BEHI scores remained consistent with the findings of
the other analyses utilized in the initial assessment of Clear Run Branch. BEHI ratings in the upper reach were
all in the High to Very High range, primarily due to the stream not being able to access its floodplain and
dissipate erosive stream energy in this reach. In the middle reach, almost all BEHI sites yielded Moderate
ratings and in the lowest reach rating were a mix of Moderate to Low risk for stream erosion. As mentioned
previously, the low erosion risk levels in the bottom reach can be attributed to the combined factors of low
stream banks, dense bank vegetation, and reduced stream velocities.
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
3.2. Water Resources
3.2.1. Hydrology
The project consists of the reach of Clear Run from just above College Acres Drive, under College Acres Drive,
and downstream to Mallard Drive. The upper section of the channel is much steeper than natural coastal
plain streams. The slope in this reach is over 3 times as steep as the lower, more stable reaches. Slopes
transition from 0.007 ft/ft in the upper reach to 0.003 ft/ft in the middle reach to 0.002 ft/ft at the lower end.
The flattening slope improves connections with existing floodplains. The floodplain in this gentler slope along
the channel's middle reach is broader and characterized by Bottomland Hardwood Forest wetlands. There
are 0.16 acres of remnant upland spoil piles in this wetland from past dredging. The lower reach of the
channel below Mallard Drive shows little sign of disturbance from past dredging and is bordered by more
extensive Riverine Swamp Forest wetlands.
Channel and floodplain improvements are planned mostly for the middle section of the channel. As described
in the preferred alternative above, the uppermost reach (above College Acres Drive) is planned to be
culverted to alleviate local residential and street flooding in the neighborhood.
3.2.2. Water Quality
Water quality data were collected on August 8, 2016 using a YSI 556 MPS multi -parameter probe (YSI. 2016).
Measurements were taken at the same four sites where aquatic insect samples were taken (Table 2,
following page). In general, there was a clear trend of increasing water quality downstream, especially with
respect to Dissolved Oxygen, where the upper three sites all were not in compliance with the Dissolved
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
Oxygen water quality standard since they were all less than 5 ppm. Conductivity levels were also generally
high, as is typical in urban streams.
Table 2: Water Quality and Aquatic Insect Data (aquatic insects sampled on August 3, 2016; Water quality
sampled on August 9 2016)
µs/c m
(temp.
°C
corrected)
Plat
Ppm
1
27.74
174
0.08
3.39
43.2
6.91
8
1
1
6.52
Poor
2
28.56
174
0.08
4.01
52.0
6.90
6
1
5
7.87
Poor
3
23.61
184
0.09
5.76
68.9
6.89
8
1
22
6.86
Poor
4
23.07
180
0.08
6.21
72.4
6.92
13
2
17
6.14
Poor
Water
Less
n/a
n/a
6.0
n/a
6.0 to
Quality
than
9.0
Standard
32
Note: Italics indicate value less than standard
EPT = Ephemeroptera, Trichoptera, and Plecoptera taxa
Clear Run has been sampled at College Acres Drive by researchers from UNC-Wilmington (Mallin, et al. 2014-
2011) for a variety of parameters. Some of these data are summarized below. The most common problem at
this location has been coliform bacteria, but dissolved oxygen levels and turbidity levels are routinely low
(Table 3). No samples were taken from the middle stream restoration reach by the UNC-W researchers.
Table 3: UNC-W Sam fin at College Acres Drive Road
2014
�•Turbidity
6.9
4
Fecal Coliform
4004 Mallin, et.al. 2014
4.8-8.0
0-14
240-60,000
2013
6.8
3
1,397
Mallin, et.al. 2013
5.3-8.6
0-9
154-13,000
2012
5.8
6
3,746
Mallin, et.al. 2012
4.6-7.3
1-11
440-66,000
2011
6.5
2
1,477
Mallin, et.al. 2011
4.0-8.0
1-3
172-5,300
2010
7.6
3
507
Mallin, et.al. 2010
7.2-7.9
1-7
136-1,637
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Clear Run Stream Restoration and Flooding Management Project
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In addition, in 2012 researchers determined that the level of polyaromatic hydrocarbons in sediment at the
College Acres Drive crossing were very high while sediment levels of metals were below detection (except for
zinc at 16.3 mg/kg and mercury at 0.003 mg/kg). These data reinforce the water chemistry data and the
aquatic insect data (described below) that Clear Run is an urban stream that exhibits all the characteristics of
a typical urban stream in terms of degraded water quality and streambank instability.
Bradley Creek is part of the City of Wilmington's "Heal Our Watersheds" Program and "Grey to Blue
Stormwater Planning Initiative" adopted by City Council in 2012 (Carey, 2013). A comprehensive watershed
management plan was prepared for Bradley Creek in 2011 using Section 319 funding. The City and other
stakeholders have worked and continue to work to implement various parts of this plan since it was adopted.
The work to restore the floodplain and stream channel on Clear Run is part of this larger effort and the
provision of additional floodplain along Clear Run is viewed favorably in the Bradley Creek restoration plan
3.2.3. Flooding
In the course of the project's design effort thus far, two community meetings have been held to make the
surrounding landowners aware of the project and to give them opportunity to comment on the emerging
design. One of the additional purposes of the first meeting was to obtain anecdotal accounts of flooding in
and around the project area to use in the verification of the hydrologic and hydraulic models used to support
the design. Anecdotal accounts indicated that the only time that Mallard Drive, toward the downstream end
of the project, ever overtopped was during Hurricane Fran, and that flooding incidence was driven by the
tidal surge from Bradley Creek downstream. It should be noted that the HEC-RAS modeling analysis
perfomred for the project indicates that the Mallard Drive culvert will overtop during a 25-year storm as a
result of excessive flows from upstream.
Anecdotal accounts from landowners along the stream indicated that in the middle and lower reach, the
stream occasionally rises up out of its banks and inundates portions of the floodplain, but no property
damage has been reported as there are few to no anthropogenic structures in the active floodplain in those
reaches. Surrounding landowners also reported that since the stream became noticeably incised, it no longer
comes out onto the floodplain in the upper reach. While the project modeling analysis indicated that the
College Acres Drive crossing would overtop during the 25-year and 100-year storm event, there has not been
any anecdotal account of it ever having done so.
As previously noted however, this project is, in part, driven by the need to address flooding in the watershed
upstream of the immediate project area presented herein. Flooding along New Centre Drive from the vicinity
of the intersection with South College Road to where it crosses Racine Drive is a fairly regular occurrence.
Print and television news stories detailing damage to automobiles and the surrounding structures, many of
which are large apartment complexes, are numerous. Examples of such news accounts can be found here:
htto://www.wect.com/storv/13227164/racine-and-new-centre-flooding
htto://www.wwavtv3.com/2015/10/04/caught-on-camera-driver-learns-hard-lesson-about-high-water/
http://www.starnewsonline.com/news/20160903/hermines-rains-cause-part-of-14th-street-to-collapse
http://www.starnewsonIine.com/news/20110812/fridays-flooding-closed-roads-in-wiImington
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http://www.starnewsonIine.com/news/20110630/wednesdays-storms-wreaked-havoc-on-power-and-traffic
The previous drainage study performed on the Clear Run watershed by Moffatt & Nichol (M&N, 2012) that
lead to this project included the following assessment of flooding in the upper watershed under existing
conditions based on an EPA SWMM modeling analysis:
"For the Clear Run drainage system, the existing model demonstrates multiple areas with
surcharged pipes and flooded storm junctions under the 10- and 25- and 50-yr return events.
Most of the critical issues are along New Centre Drive, South College Road, and Racine Drive.
A run of undersized piping along New Centre Drive (west of College Road) and along South
College Road (north of main line junction) appears to be the cause of flooding at the most
upstream points in the network. This undersized run of pipe is causing flooding along the
aforementioned section of New Centre Dr. and at inlets along the West side of College Road.
High tailwater in the dual pipes crossing South College Road (at a point on South College
Road, approximately 1500 feet southwest of the intersection with New Centre Drive) appears
to worsen the flooding adjacent to this area of the network. High tailwater in the dual pipes
crossing South College Road also appears to be a cause for flooding and pipe surcharging
along College Road in areas immediately north and south of the crossing. Undersized piping
along College Road at the southwest corner of the network appears to be causing flooding,
and is heightened by the high tailwater at the aforementioned dual pipe crossing."
The drainage study went further to add:
"In the interest of assessing the accuracy of the model, a simulation was performed for an
actual storm event for which anecdotal accounts of the magnitude of flooding in the study
area exist. On July 6, 2009 NOAA rainfall records from the Wilmington Airport show a storm
with 6.51 inches of rain in the event, and the Wilmington Star reported that as much as 10
inches of rain fell in the vicinity of Racine and New Centre Drive. City Stormwater staff were
at that intersection immediately following the rainfall event and reported ponding at that
location to depths of 3-4 feet (Personal Communication, Dave Mayes).
"The XPSWMM model of the Clear Run watershed was run with 10 inches of rain to simulate
the July 6 event and the model resulted in ponded depths of up to 2 feet at the intersection
of Racine and New Centre Drive. While the model did not project the same depths reflected
in the anecdotal account, it is important to note that this model does not project the extents
or boundaries of flooding/ponding on a physical surface, but rather, relies on the
hypothetical uniform surface generated by XPSWMM in the absence of actual surface data.
In addition, overland flow was not simulated in this model, so real -world ponding at the
actual trough of the valley is slightly underestimated. More importantly, the results did show
the intersection to be one of the worst surcharging and ponding nodes in the model."
Based on the drainage study results, the City's overall plan for the watershed is to begin with restoration and
improvement of the lower open -stream segment of Clear Run (the project represented in this document as
the headwater and upper reaches) in Phase I, and then to replace the undersized storm drains in the upper
watershed in Phase II. As mentioned in the Purpose and Need section above, the restoration and stabilization
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of Clear Run, along with the enlargement of the floodplain, is required to prepare the stream for the
increased stormflows that will result from the necessary upstream improvements.
It should be noted that a formal Letter of Map Revision (LOMR) will be filed with FEMA in conjunction with
this project. The LOMR is required because the HEC-RAS/HEC-HMS model analysis indicates that the project
is predicted to lower water surface elevation during all storm events under the proposed condition relative
to existing conditions.
3.2.4. Stream Condition
Five NC SAM forms were completed on separate reaches of the channel with different conditions (Table 4,
Figure 4). The three uppermost reaches were all rated as Overall Low quality reflecting the relatively straight,
incised channel with degraded buffers in the upper two reaches and riprap that has been installed in the
middle reach. The lower reaches of the channel rate as Overall High quality, which reflects the less incised
channel and adjacent wetlands. The Overall High quality channel (site 5) will not be impacted. The uppermost
Low quality reach (down to College Acres Road — site 1) will be culverted, as will the middle Low quality reach
(site 2) (which is currently riprapped) while the lowermost Low quality reach (site 3) will be relocated into a
more natural pattern with an adjacent graded floodplain. In the reach represented by site 4, the channel will
not be affected but relict spoil piles will be removed from the floodplain.
Table 4: NC SAM and NC WAM Evaluations of Stream and Wetland Quality
Method/Site
HydrologyNumber Quality Habitat Overall
NC SAM
Site 1
Low
Medium
Low
Low
Site 2
Low
Medium
Low
Low
Site 3
Low
Low
Medium
Low
Site 4
Medium
High
High
High
Site 5
High
High
High
High
NC WAM
Site 1
High
Medium
Low
Medium
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Figure 4: NC SAM and NC WAM Evaluations of Stream and Wetland Quality
3.3. Air Quality and Noise
Based on EPA's Air Quality Index (AQI) data from the past 3 years, Wilmington generally experiences AQI
values in the "Good" range with a smaller percentage of days in the "Moderate" range (ranging from 5% to
34% of the year since 2013). The surrounding land use is primarily suburban, with a large area of commercial
development (retail business) to the west of the Clear Run restoration reach along College Drive and the
UNC-W campus to the south. Air quality and noise issues in the area surrounding the Clear Run restoration
reach are driven by nearby traffic, parking lot use, and activities on the campus of UNC-W and are typical of a
moderate to densely developed suburban area. The Clear Run restoration is anticipated to have a minimal
effect on both air quality and noise, and will only have a negligible effect during temporary construction
activities associated with the project.
3.4. Aquatic Resources
A site visit was made on August 3, 2016 to conduct a Qual 4 investigation (NC Division of Water Resources.
2013) of the stream in order to characterize the aquatic insect community and observe any fish present on
the site. During the sampling, a kick net sample was taken at each site, along with multiple sweeps with a "D"
net, examination of several leaf packs, and visual examination of rocks, logs, sticks, and roots in the channel.
Results are summarized on Table 2 above. Appendix A lists all the aquatic insects found during this
investigation. Four sites were sampled as shown in the table. In general, there is a clear trend of improving
water quality from the uppermost location (above College Acres Road) to the lower reach, although all four
sites have a probable bioclassification of Poor, which reflects the highly impervious surface in the uppermost
watershed. The restoration reach is represented by Site 2. Site 3 had the best aquatic insect community with
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2 (two) taxa of EPT1 and the highest taxa richness with 13 taxa. As described before, no channel work will be
done in this section while the relict spoil piles will be removed from the floodplain. Sites 1 and 2 had lower
taxa richness and fewer EPA taxa. These data coincide with the NC SAM evaluations and the BEHI evaluations
discussed earlier.
Fish were noted throughout the reach. Mosquito fish (Gambusia) were common and various small
Centrachids (such as bream) were also noted throughout the reach. One small eel (Anguilla rostrata) was
captured in the uppermost reach. What was probably a small redfin, grass, or chain pickerel (Esox
americanus) was observed in the lowermost reach. In general, fish taxa observed are typical of small, urban
streams in the coastal plain. A review of the NOAA Essential Fish Habitat Mapper on February 3, 2017
indicated that there are no EFH issues identified by NOAA within the Clear Run Study Area.
3.5. Terrestrial Resources
The project lies in North Carolina's coastal plain physiographic region. Topography is comprised of nearly
level and gently sloping land that drains to Bradley Creek and eventually to the Atlantic Intracoastal
Waterway (ICW). The Bradley Creek watershed is approximately 4,631 acres in size and includes most of the
UNC-Wilmington campus. Elevations in the Clear Run restoration area range from 7 to 32 feet above sea
level. Surrounding land use consists primarily of commercial development, residential development, college
campus, and small areas of forestland, mostly along stream and wetland corridors.
The New Hanover County Soil Survey identifies six soil types adjacent to the Clear Run floodplain within the
project area (Table 5).
Table 5: Soils Found in the Clear Run Project
Series
Baymeade fine sand, 1-6% slopes
MappingSoil
�
Be
Well Drained
Hydric
Johnston soils
Jo
Very Poorly Drained
Hydric
Kureb sand, 1-8% slopes
Kr
Very Well Drained
Hydric
Lynn Haven fine sand
Ly
Poorly Drained
Hydric
Murville fine sand
Mu
Very Poorly Drained
Hydric
Rimini sand, 1-6% slopes
Rm
Very Well Drained
Hydric
Terrestrial communities adjacent to the Clear Run restoration reach are comprised of both natural and
disturbed habitats that may support a diversity of wildlife species (those species actually observed are
indicated with *). Mammal species that commonly exploit forested habitats and stream corridors include
species such as the eastern cottontail, raccoon*, Virginia opossum, fox squirrel*, and white-tailed deer. Birds
that commonly use forest and forest edge habitats include the American crow*, blue jay*, tufted titmouse*,
yellow-rumped warbler, and Carolina wren*. Birds that may use the open habitat or water bodies within the
Clear Run restoration reach include American kestrel, eastern bluebird, green heron, and turkey vulture*.
1 EPT = Ephemoptera, Plecoptera, and Tricoptera, which generally represent the most sensitive aquatic insects to pollution.
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Reptile and amphibian species that may use terrestrial communities adjacent to the Clear Run restoration
reach include the corn snake, eastern box turtle*, eastern fence lizard, and southeastern five -lined skink.
Four terrestrial communities were identified adjacent to the Clear Run restoration reach: maintained/
disturbed, coastal plain stream, small stream swamp, blackwater bottomland hardwoods (low subtype), and
mesic pine savanna (coastal plain subtype). Two species from the NCDOT Invasive Exotic Plant List for North
Carolina were found to occur adjacent to the Clear Run restoration reach. The species identified were
Chinese privet (Threat) and golden bamboo (Moderate Threat). Scientific names are included in Appendix B.
3.5.1. Maintained/Disturbed
Maintained/disturbed areas are scattered throughout the project area in places where the vegetation is
periodically mowed, such as roadside shoulders, areas of commercial development, and residential lawns.
The vegetation in this community is comprised of low growing grasses and herbs, including fescue, clover,
wild onion, and broomsedge.
3.5.2. Coastal Plain Small Stream Swamp
This community is located in the Clear Run floodplain primarily in the lower reach of the site where the
adjacent wetlands are more indicative of a riverine swamp system. The community is distinguished from the
Blackwater Bottomland Hardwoods (High Subtype) based on species more tolerant of wetter conditions, an
increased hydroperiod, and a broadening of the floodplain. Dominant vegetation within this community
includes swamp tupelo, water ash, laurel oak, sweetgum, and ironwood. This community corresponds to the
NCWAM Riverine Swamp Forest wetland type.
3.5.3. Blackwater Bottomland Hardwoods (Low Subtype)
This community is located within the mostly narrow floodplain in the upper reaches of the Clear Run
restoration reach and is generally drier and with a greater slope than the lower reach of Clear Run. This
community also includes non -wetland areas. Dominant vegetation in this community includes red maple,
sweetgum, water oak, laurel oak, and American holly. This community corresponds to the NCWAM
Bottomland Hardwood Forest wetland type.
3.5.4. Mesic Pine Savanna (Coastal Plain Subtype)
This community is located outside of the Clear Run floodplain and consist of upland pine -dominated habitat.
The pine savanna to the south of the Clear Run floodplain is managed to limit undergrowth vegetation and is
dominated by longleaf pine and loblolly pine. Understory species are generally sparse and include saplings
such as post oak, southern red oak, and water oak.
3.6. Wetlands and Floodplains
The uppermost section of the reach is characterized by a fairly deeply incised channel and no adjacent
wetlands and only a very narrow floodplain. However, around the beginning of Section 4 (Figure 3), the
channel (although still unstable) is not as incised and the adjacent floodplain and the site is characterized on
both sides by Bottomland Hardwood Forest. There are a few locations where spoil piles have been placed in
the wetland from past dredging which has created high ground. This wetland was evaluated using Version 5.1
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of NC WAM (NC Wetland Assessment Method), which resulted in an Overall score of Medium for the site
(Table 4) with Hydrology being rated as High, Water Quality as Medium, and Habitat as Low.
3.7. Threatened and Endangered Species
As of April 2, 2015, there are no Endangered Species Act Candidate Species listed by the USFWS in New
Hanover County. The United States Fish and Wildlife (USFWS) and the National Oceanic and Atmospheric
Administration (NOAA) Fisheries lists 15 federally -protected species for New Hanover County (Table 6). A
brief description of each species' habitat requirements follows, along with the Biological Conclusion rendered
based on survey results in the project area. Habitat requirements for each species are based on the current
best available information from referenced literature and/or USFWS.
Table 6: Federally Protected Species Listed for New Hanover County
Haliaeetus leucocephalus
Bald eagle
BGPA
No
No Effect
Glyptemys muhlenbergii
American alligator
T(S/A)
No
Not Required
Chelonia mydas
Green sea turtle
E
No
No Effect
Eretmochelys imbricate
Hawksbill sea turtle
E
No
No Effect
Lepidochelys kempii
Kemp's ridley sea turtle
E
No
No Effect
Dermochelys coriacea
Leatherback sea turtle
E
No
No Effect
Caretta caretta
Loggerhead sea turtle
E
No
No Effect
Myotis septentrionalis
Northern long-eared bat
T
No
No Effect
Charadrius melodus
Piping plover
T
No
No Effect
Picoides borealis
Red -cockaded woodpecker
E
No
No Effect
Calidris canutus rufa
Red knot
T
No
No Effect
Trichechus manatus
West Indian manatee
E
No
No Effect
Thalictrum cooleyi
Cooley's meadowrue
E
Yes
No Effect
Carex lutea
Golden sedge
E
Yes
No Effect
Lysimachia asperulaefolia
Rough -leaf loosestrife
E
Yes
No Effect
Amaranthus pumilus
Seabeach amaranth
T
No
No Effect
E - Endangered
T - Threatened
T(S/A) - Threatened due to similarity of appearance
MA-NLAA — May Affect -Not Likely to Adversely Affect
3.7.1. Bald Eagle and Golden Eagle Protection Act
Habitat for the bald eagle primarily consists of mature forest in proximity to large bodies of open water for
foraging. Large dominant trees are utilized for nesting sites, typically within one mile of open water. A
desktop-GIS assessment of the Clear Run restoration project area, as well as the area within a 1.13 mile
radius (1.0 mile plus 660 feet) of the project limits, was performed on August 25, 2016 using 2014 and 2015
color aerials. Bradley Creek opens up into a large area of open water and surrounding marsh in the southeast
corner of the 1.13-mile radius. This area is potential foraging habitat, so a survey of the Clear Run restoration
area and the area within 660 feet of the project limits was conducted. A review of the NCNHP database,
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updated June 2016 revealed no known occurrences of this species within one mile of the project area. Due to
the lack of habitat within the immediate vicinity of the Clear Run restoration reach, known occurrences, and
minimal impact anticipated for this project, it has been determined that this project will not affect this
species.
3.7.2. American Alligator
USFWS Optimal Survey Window: Year-round (only warm days in winter)
Habitat Description: In North Carolina, alligators have been recorded in nearly every coastal county,
and many inland counties to the fall line. The alligator is found in rivers, streams, canals, lakes,
swamps, and coastal marshes.
Biological Conclusion: Not required since alligators are listed as threatened due to similarity of
appearance (T S/A). A taxon that is threatened due to similarity of appearance with another listed
species and is listed for its protection. Taxa listed as T(S/A) are not biologically endangered or
threatened and are not subject to Section 7 consultation
3.7.3. Green Sea Turtle
USFWS Optimal Survey Window: April — August
Habitat Description: The green sea turtle is found in temperate and tropical oceans and seas. Nesting
in North America is limited to small communities on the east coast of Florida requiring beaches with
minimal disturbances and a sloping platform for nesting (they do not nest in North Carolina). The
green sea turtle can be found in shallow waters. They are attracted to lagoons, reefs, bays, mangrove
swamps, and inlets where an abundance of marine grasses can be found, as this is the principle food
source for the green turtle.
Biological Conclusion: No Effect. The waters within the project area do not provide suitable habitat
for the green sea turtle as they are located approximately 3.5 miles from the nearest shoreline.
3.7.4. Hawksbill Sea Turtle
USFWS Optimal Survey Window: April — August
Habitat Description: Hawksbill sea turtles are found in tropical and subtropical oceans. Sightings
have been reported on the east coast of the U.S. as far north as Massachusetts, although rarely north
of Florida. Sightings have been recorded from a handful of counties in North Carolina, but the turtle
is not known to breed here. Adult hawksbills are found in coastal waters, especially around coral
reefs, rocky outcrops, shoals, mangrove bays, and estuaries. Juveniles are often seen offshore, in
floating mats of seaweed. This species nests on a wide range of beach types and substrates, using
both low- and high-energy beaches on islands and mainland sites. The nest is typically placed near or
under some vegetation.
Biological Conclusion: No Effect. The waters within the project area do not provide suitable habitat
for the Hawksbill sea turtle as they are located approximately 3.5 miles from the nearest shoreline.
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3.7.5. Kemp's Ridley Sea Turtle
USFWS Optimal Survey Window: April — August
Habitat Description: Kemp's ridley sea turtle is the smallest of the sea turtles that visit North
Carolina's coast, and has been sighted in most coastal counties. While the majority of this sea turtle's
nesting occurs in Mexico, the species is known to nest on North Carolina beaches infrequently.
Sightings of the species exist for most coastal counties. Kemp's ridley sea turtle can lay eggs as many
as three times during the April to June breeding season. Kemp's ridley sea turtles prefer beach
sections that are backed up by extensive swamps or large bodies of open water having seasonal
narrow ocean connections and a well-defined elevated dune area. The species prefers neritic areas
with sandy or muddy bottoms.
Biological Conclusion: No Effect. The waters within the project area do not provide suitable habitat
for the Kemp's ridley sea turtle as they are located approximately 3.5 miles from the nearest
shoreline.
3.7.6. Leatherback Sea Turtle
USFWS Optimal Survey Window: April — August
Habitat Description: Leatherbacks are distributed worldwide in tropical waters of the Atlantic,
Pacific, and Indian Oceans. They are generally an open ocean species, and may be common off the
North Carolina coast during certain times of the year. However, in northern waters leatherbacks are
reported to enter into bays, estuaries, and other inland bodies of water. Major nesting areas occur
mainly in tropical regions. In the United States, primary nesting areas are in Florida, however nests
are known from Georgia, South Carolina, and North Carolina as well. Nesting occurs from April to
August. Leatherbacks need sandy beaches backed with vegetation in the proximity of deep water and
generally with rough seas. Beaches with a relatively steep slope are usually preferred.
Biological Conclusion: No Effect. The waters within the project area do not provide suitable habitat
for the leatherback sea turtle as they are located approximately 3.5 miles from the nearest shoreline.
3.7.7. Loggerhead Sea Turtle
USFWS Optimal Survey Window: April — August
Habitat Description: The loggerhead is widely distributed within its range, and is found in three
distinct habitats during their lives. These turtles may be found hundreds of miles out in the open
ocean, in neritic areas, or on coastal beaches. In North Carolina, this species has been observed in
every coastal county. Loggerheads occasionally nest on North Carolina beaches, and are the most
common of all the sea turtles that visit the North Carolina coast. They nest nocturnally, at two to
three year intervals, between May and September, on isolated beaches that are characterized by
fine-grained sediments. In nearshore areas, loggerheads have been observed in bays, lagoons, salt
marshes, creeks, ship channels, and the mouths of large rivers. Coral reefs, rocky places, and
shipwrecks are often used as foraging areas.
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Biological Conclusion: No Effect. The waters within the project area do not provide suitable habitat
for the Loggerhead sea turtle as they are located approximately 15 miles from the nearest shoreline.
3.7.8. Northern Long-eared Bat
USFWS Optimal Survey Window: June 1— August 15
Habitat Description: In North Carolina, the Northern long-eared bat (NLEB) occurs in the mountains
with scattered records in the Piedmont and coastal plain. In eastern North Carolina, caves and
subterranean mines are extremely rare, so it is uncertain whether or not NLEB hibernate in this area.
During the summer, NLEB roost singly or in colonies underneath bark, in cavities, or in crevices of
both live and dead trees (typically >_3 inches dbh). Males and non -reproductive females may also
roost in cooler places, like caves and mines. This bat also has been rarely found roosting in structures
like barns, in bridges, and in bat houses. Foraging occurs on forested hillsides and ridges, and
occasionally over forest clearings, over water, and along tree -lined corridors. Mature forests may be
an important habitat type for foraging.
Biological Conclusion: No Effect. The forested habitats within the project area do not provide
suitable habitat for the NLEB and the project will not impact any possible roosting structures, such as
bridges or barns.
3.7.9. Piping Plover
USFWS Optimal Survey Window: July 15 — May 1
Habitat Description: Primary constituent elements of wintering piping plover habitat include sand
and/or mud flats with no or very sparse emergent vegetation. In some cases, these flats may be
covered or partially covered by a mat of blue-green algae. Adjacent unvegetated or sparsely
vegetated sand, mud, or algal flats above high tide are also essential, especially for roosting piping
plovers. Such sites may have debris, detritus (decaying organic matter), or micro -topographic relief
(less than 20 inches above substrate surface) offering refuge from high winds and cold weather.
Essential components of the beach/dune ecosystem include surf -cast algae for feeding of prey,
sparsely vegetated back beach (beach area above mean high tide seaward of the dune line, or in
cases where no dunes exist, seaward of a delineating feature such as a vegetation line, structure, or
road) for roosting and refuge during storms, spits (a small point of land, especially sand, running into
water) for feeding and roosting, salterns (bare sand flats in the center of mangrove ecosystems that
are found above mean high water and are only irregularly flushed with sea water) and washover
areas for feeding and roosting. Washover areas are broad, unvegetated zones with little or no
topographic relief that are formed and maintained by the action of hurricanes, storm surge, or other
extreme wave action. Several of these components (sparse vegetation, little or no topographic relief)
are mimicked in artificial habitat types used less commonly by piping plovers, but that are considered
critical habitat (e.g., dredge spoil sites).
Biological Conclusion: No Effect. The project area does not provide suitable habitat for the piping
plover, since it is located inland and approximately 3.5 miles from the beach.
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3.7.10. Red -cockaded Woodpecker
USFWS Optimal Survey Window: Year round; November — Early March (optimal)
Habitat Description: The red -cockaded woodpecker (RCW) typically occupies open, mature stands of
southern pines, particularly longleaf pine (Pinus palustris), for foraging and nesting/roosting habitat.
The RCW excavates cavities for nesting and roosting in living pine trees, aged 60 years or older, which
are contiguous with pine stands at least 30 years of age to provide foraging habitat. The foraging
range of the RCW is normally no more than 0.5 miles.
Biological Conclusion: No Effect. Suitable foraging habitat for the red -cockaded woodpecker does
exist within the project area. A section of forest south of the Clear Run restoration reach is pine
savanna, but the forest is composed of relatively young trees. A half -mile survey was conducted on
several dates late winter and early spring 2016. No individuals or evidence of RCWs were observed.
The project is anticipated to have a minimal impact on this forested area. A review of NCNHP
records, updated June 2016, indicates no known RCW occurrence within 1.0 mile of the project area.
3.7.11. Red Knot
USFWS Optimal Survey Window: To Be Determined
Habitat Description: The rufa red knot is one of the six recognized subspecies of red knots, and is the
only subspecies that routinely travels along the Atlantic coast of the United States during spring and
fall migrations. It is known to winter in North Carolina and to stop over during migration. Habitats
used by red knots in migration and wintering areas are similar in character: coastal marine and
estuarine habitats with large areas of exposed intertidal sediments. In North America, red knots are
commonly found along sandy, gravel, or cobble beaches, tidal mudflats, salt marshes, shallow coastal
impoundments and lagoons, and peat banks. Ephemeral features such as sand spits, islets, shoals,
and sandbars, often associated with inlets can be important habitat for roosting.
Biological Conclusion: No Effect. The project area does not provide suitable habitat for the red knot
as it is located inland and approximately 3.5 miles from the nearest shoreline and there is generally a
lack of exposed sediments within the project area.
3.7.12. West Indian Manatee
USFWS Optimal Survey Window: May 15 — October 15
Habitat Description: Manatees have been observed in all the North Carolina coastal counties.
Manatees are found in canals, sluggish rivers, estuarine habitats, salt water bays, and as far off shore
as 3.7 miles. They utilize freshwater and marine habitats at shallow depths of 5 to 20 feet. In the
winter, between October and April, manatees concentrate in areas with warm water. During other
times of the year, habitats appropriate for the manatee are those with sufficient water depth, an
adequate food supply, and in proximity to freshwater. Manatees require a source of freshwater to
drink. Manatees are primarily herbivorous, feeding on any aquatic vegetation present, but they may
occasionally feed on fish.
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Biological Conclusion: No Effect. The project area does not provide suitable habitat for the West
Indian manatee. The study area is approximately 3.5 miles from the nearest shoreline and bays and is
generally too shallow for the West Indian manatee. A review of NCNHP records, updated June 2016,
indicates no known occurrences within one mile of the project area. Cooley's Meadowrue
3.7.13 Cooley's Meadowrue
USFWS Optimal Survey Window: Mid -June — Early -July
Habitat Description: Cooley's meadowrue, documented in the Pine Savanna natural community,
occurs in circumneutral soils in sunny, moist to wet grass -sedge bogs, wet -pine savannas over
calcareous clays, and savannah -like areas, often at the ecotones of intermittent drainages or non-
riverine swamp forests. This rhizomatous perennial herb is also found along plowed firebreaks,
roadside ditches and rights -of -way, forest clearings dominated by grass or sedge, and power line or
utility rights -of -way. The species requires some type of disturbance (e.g., mowing, clearing, periodic
fire) to maintain its open habitat. The plant typically occurs on slightly acidic (pH 5.8-6.6) soils that
are loamy fine sand, sandy loam, or fine sandy loam; at least seasonally moist or saturated; and
mapped as Foreston, Grifton, Muckalee, Torhunta, or Woodington series.
Biological Conclusion: No Effect. Suitable habitat for Cooley's meadowrue is present adjacent to the
Clear Run restoration reach along utility easements and clearings. Surveys for Cooley's meadowrue
were conducted during the appropriate survey window in June of 2015. Surveys were conducted
using overlapping transects across suitable habitat adjacent to the Clear Run restoration reach. No
individuals of Cooley's meadowrue were observed adjacent to the project area. A review of NCNHP
records, updated June 2016, indicates no known occurrences within 1.0 mile of the project area.
3.7.13. Golden Sedge
USFWS Optimal Survey Window: Mid -April — Mid -June
Habitat Description: Golden sedge, a very rare endemic of the Atlantic Coastal Plain, grows in sandy
soils overlying calcareous deposits of coquina limestone, where the soil pH, typically between 5.5 and
7.2, is unusually high for this region. This perennial prefers the ecotone between the pine savanna
and adjacent wet hardwood or hardwood/conifer forest. Most plants occur in the partially shaded
savanna/swamp where occasional to frequent fires favor an herbaceous ground layer and suppress
shrub dominance. Soils supporting the species are very wet to periodically shallowly inundated.
Other occurrences may occur on disturbed areas such as roadside and drainage ditches or power line
rights -of -way, where mowing and/or very wet conditions suppress woody plants. Poorly viable
occurrences may occur in significantly disturbed areas where ditching activities that lower the water
table and/or some evidence of fire suppression threatens the species.
Biological Conclusion: No Effect. Suitable habitat for Golden Sedge is present adjacent to the Clear
Run restoration reach along utility easements and clearings. Surveys for Golden sedge were
conducted during the appropriate survey window in June of 2015. Surveys were conducted using
overlapping transects across suitable habitat adjacent to the Clear Run restoration reach. No
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Clear Run Stream Restoration and Flooding Management Project
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individuals of Golden sedge were observed adjacent to the project area. A review of NCNHP records,
updated June 2016, indicates no known occurrences within 1.0 mile of the project area.
3.7.14. Rough -leaf Loosestrife
USFWS Optimal Survey Window: Mid -May — Mid -June
Habitat Description: Rough -leaved loosestrife, endemic to the Coastal Plain and Sandhills of North
and South Carolina, generally occurs in the ecotones or edges between longleaf pine uplands and
pond pine pocosins in dense shrub and vine growth on moist to seasonally saturated sands and on
shallow organic soils overlaying sand (spodosolic soils). Occurrences are found in such disturbed
habitats as roadside depressions, maintained power and utility line rights -of -way, firebreaks, and
trails. The species prefers full sunlight, is shade intolerant, and requires areas of disturbance (e.g.,
clearing, mowing, periodic burning) where the overstory is minimal. It can, however, persist
vegetatively for many years in overgrown, fire -suppressed areas. Blaney, Gilead, Johnston, Kalmia,
Leon, Mandarin, Murville, Torhunta, and Vaucluse are some of the soil series that the plant prefers.
Biological Conclusion: No Effect. Suitable habitat for rough -leaf loosestrife is present adjacent to the
Clear Run restoration reach along utility easements and clearings. Surveys for rough -leaf loosestrife
were conducted during the appropriate survey window in June 2015. Surveys were conducted using
overlapping transects across suitable habitat adjacent to the Clear Run restoration reach. No
individuals of Rough -leaf loosestrife were observed adjacent to the project area. A review of NCNHP
records, updated June 2016, indicates no known occurrences within 1.0 mile of the project area.
3.7.15. Seabeach Amaranth
USFWS Optimal Survey Window: July - October
Habitat Description: Seabeach amaranth occurs on barrier island beaches where its primary habitat
consists of overwash flats at accreting ends of islands, lower foredunes, and upper strands of
noneroding beaches (landward of the wrack line). In rare situations, this annual is found on sand spits
160 feet or more from the base of the nearest foredune. It occasionally establishes small temporary
populations in other habitats, including sound -side beaches, blowouts in foredunes, interdunal areas,
and on sand and shell material deposited for beach replenishment or as dredge spoil. The plant's
habitat is sparsely vegetated with annual herbs (forbs) and, less commonly, perennial herbs (mostly
grasses) and scattered shrubs. It is, however, intolerant of vegetative competition and does not occur
on well -vegetated sites. The species usually is found growing on a nearly pure silica sand substrate,
occasionally with shell fragments mixed in. Seabeach amaranth appears to require extensive areas of
barrier island beaches and inlets that function in a relatively natural and dynamic manner. These
characteristics allow it to move around in the landscape, occupying suitable habitat as it becomes
available.
Biological Conclusion: No Effect. The project area does not provide suitable habitat for seabeach
amaranth. The project area is approximately 3.5 miles from the nearest shoreline and does not
contain the proper beach and dune habitat.
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Clear Run Stream Restoration and Flooding Management Project
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3.8. Cultural Resources
A review of the North Carolina State Historic Preservation Office (NCHPO) GIS Service Online Mapper
(Accessed August 25, 2016) indicated that there are no resources adjacent to the Clear Run restoration reach
that could be impacted by this project.
3.9. Socio-Economic Resources
The residential neighborhood adjacent to Clear Run is a mix of single family homes (some owner occupied
and some rental for UNC-Wilmington students) and apartment/townhome complexes for both students and
professionals who work in the Wilmington area. Most of the single family homes were built in the 1950s and
1960s with the apartment/townhome complexes built more recently. In addition, UNC-Wilmington has a
large tract of undeveloped land adjacent to the stream to the south mostly below the restoration reach. The
headwaters of Clear Run (above College Drive) is mainly commercial development and is entirely built out.
From above College Acres Road, the watershed is reported as 50.52% impervious, while from Mallard Street
it is reported as 31.72% impervious (United States Geological Survey. 2016). This analysis probably
underestimates the actual percent impervious cover in the upper watershed above College Road. The lower
percent impervious cover at Mallard Street reflects the large undeveloped UNC-Wilmington tract along the
south side of the creek in the study reach.
The floodplain and stream restoration project will reduce periodic flooding on College Acres Drive and
Mallard Drive and thereby benefit the local community. In addition, numerous lots are experiencing severe
streambank erosion and threats to existing structures which will also be alleviated by this project. Therefore,
in general this project will provide positive socio-economic benefits to the local community.
3.10. Safety Including Flooding
While anecdotal accounts reported only rare overtopping of the roadways at either end of the immediate
project (College Acres Drive and Mallard Road), flooding in the upper portion of the watershed along New
Centre Drive from the vicinity of the intersection with South College Road to where it crosses Racine Drive is
a fairly regular occurrence. Print and television news stories detailing damage to automobiles and the
surrounding structures, many of which are large apartment complexes are numerous, and several examples
are provided in Section 3.2.3. Beyond the damage to private property, these flooding events are highly
detrimental to public safety, as they typically result in rerouting of traffic and emergency vehicle in particular.
The rerouting of traffic is of signifcant concern to saftey as both College Road and New Centre Drive are
major urban thoroughfares, such that heavy traffice volumes are rerouted to neighborhood level streets with
limited capacity. Additionally, South College Road is a primary emergency route to the New Hanover Regional
Medical Center southwest of the project area. In addition, localized flooding in response to severe
thunderstorms in July of 2009, flooded several bottom floors of several apartment complexes which then
restricted access to those apartments by their renters.
3.11. Summary of Environmental Impacts of Alternatives
Table 7 summarizes the environmental impacts of the four alternatives that were discussed —1) Upper
watershed detention, 2) Selected stabilization and road culvert replacement, 3) No action, and 4) Stream and
Floodplain Restoration (Applicant preferred). Overall, the applicant preferred alternative (stream and
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
floodplain restoration) has the least negative and most positive environmental impacts since it addresses
holistically the existing condition of the channel as well as accommodates future flows from anticipated
upstream drainage improvements. In general, the cost of the four alternatives can be ranked as follows:
Upper Watershed Detention > Stream and Floodplain Restoration > Selected Stabilization and Culvert
Replacement> No Action.
Table 7: Comparison of Environmental Impacts of Alternatives — Clear Run Project
T
O
H C ^
c d
E
N L V
Gl O r_
L a C
'O E 'L
Alternative Q ~
C
R +.
> C
O C.
L -O
C. O
`�
-o
h 41
Gl
L W
V L
M1.
tw
En.
O = w
O c0
w s 3 a
y u O CA
a+ w f0
E E
N GJ W > N W >
V O d O
3 7 E L
M C. -O N C.
O
�- '^ Q 3
StabilizationSelected •...
Culvert Replacement
Stream and Floodplain Restoration
(Applicant Preferred)
SOMEONE=
4. Cumulative Impacts
This project will not result in additional development since the FEMA floodplain regulations and 404
permitting program will continue to prevent impacts to the stream channel or floodplain. Therefore,
cumulative impacts are not a concern with this project except that downstream water quality in Bradley
Creek should be improved due to the reduced streambank erosion and greater floodplain access (and
resulting reduction in transport that will be achieved by this project.
S. Compliance with Environmental Requirements
This project will require an Individual Permit from the US Army Corps of Engineers and an accompanying
Individual Certification from the NC Division of Water Resources. A Coastal Zone Consistency determination
will be required from the NC Division of Coastal Management to accompany the 404 Permit. This
Environmental Assessment is intended to address the need for an environmental document by the US Army
Corps of Engineers and the NC Clearinghouse for the 404/401 Permit. The applicant intends to apply for the
404 Permit once the Corps of Engineers completes their review of this draft Environmental Assessment.
6. Agency and Public Involvement
6.1. Agency and Public Coordination
Section to be completed by the US Army Corps of Engineers.
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Clear Run Stream Restoration and Flooding Management Project
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6.2. Sections 404 and 401 of the Clean Water Act and Coastal Zone Consistency
The applicant intends to apply for the 404 Permit, 401 Certification, and Coastal Zone Consistency
determination once the Corps of Engineers and the agencies complete their review of this draft
Environmental Assessment.
7. Point of Contact
Applicant — Sterling Cheatham, City Manager, City of Wilmington, 102 N. 3rd Street, Wilmington, NC 28401;
P.O. Box 1810; Wilmington, NC 28402.
Registered Agent —Jason Doll, Moffatt & Nichol, 4700 Falls of Neuse Road, Suite 300, Raleigh, NC 27609
8. Draft Finding of No Significant Impact
Section to be completed by the US Army Corps of Engineers.
9. Bibliography
Carey, E. 2013. Heal Our Waterways — Restoring Bradley and Hewletts Creek through Community
Partnerships and Voluntary Participation. Presentation at NC American Public Works Association Meeting.
Available at:
http://northcarolina.apwa.net/content/chapters/northcarolina.apwa.net/file/Divisions/Stormwater-
Management-Division/Conference/2013/20-Carey-Heal-Our-Waterways.pdf. Accessed on August 9, 2016.
Doll, B.A. et al. 2002. Hydraulic Geometry Relationships for Urban Streams Throughout the Piedmont of
North Carolina. J. American Water Resources Association. Vol.38, No. 3. Pp. 641-651.
Mallin, et al. 2014. Environmental quality of Wilmington and New Hanover County watersheds, 2014. CMS
Report 15-01. Center for Marine Science University of North Carolina Wilmington. 92 pgs. Wilmington, N.C.
28409. Available at: http://www.wilmingtonnc.gov/home/showdocument?ld=2240. Accessed on August 9,
2016.
Mallin, et al. 2013. Environmental quality of Wilmington and New Hanover County watersheds, 2013. CMS
Report 14-01. Center for Marine Science. University of North Carolina Wilmington. Wilmington, N.C. 28409.
78 pgs. Available at: http://www.wilmingtonnc.gov/home/showdocument?ld=2238. Accessed on August 9,
2016.
Mallin, et al. 2012. Environmental quality of Wilmington and New Hanover County watersheds, 2012. 85 pgs.
CMS Report 13-01. Center for Marine Science. University of North Carolina Wilmington, Wilmington, N.C.
28409. Available at: http://www.wilmingtonnc.gov/home/showdocument?ld=2236. Accessed on August 9,
2016.
Mallin, et al. 2011. Environmental quality of Wilmington and New Hanover County watersheds, 2011. 84 pgs.
CMS Report 12-01. Center for Marine Science. University of North Carolina Wilmington. Wilmington, N.C.
28409. Available at: http://www.wilmingtonnc.gov/home/showdocument?id=2236. Accessed on August 9,
2016.
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
Mallin, et al. 2010. Environmental quality of Wilmington and New Hanover County watersheds, 2010. 81 pgs.
CMS Report 11-01. Center for Marine Science. University of North Carolina Wilmington. Wilmington, N.C.
28409. Available at: http://www.wilmingtonnc.gov/home/showdocument?ld=2232. Accessed on August 9,
2016.
NC Division of Water Resources. 2013. Standard Operating Procedures for Collection and Analysis of Benthic
Macroinvertebrates , Version 4.0. Chapter on the Qual 4 sampling method, page 7. Raleigh, NC.
N.C. Stream Functional Assessment Team. 2015. N.C. Stream Assessment Method (NC SAM) User Manual,
Version 2.1. Raleigh, NC.
N.C. Wetland Functional Assessment Team. 2016. N.C. Wetland Assessment Method (NC WAM) User
Manual. Version 5 (Calculator version 5.1). Raleigh, NC.
Rosgen, D. L. 2001. A Stream Channel Assessment Methodology. Proceedings of 7th Federal Interagency
Sedimentation Conference. Rosgen, D. L. 2001 Mar 25-29, Reno, NV, 26 (2001).
United States Geological Survey. 2016. StreamStats website. Beta Version 4. Available at:
http://water.usgs.gov/osw/streamstats/siteStatusProd/index.htm?viewerStart=true. Accessed on August 10,
2016.
YSI, Inc. 2016. 556 Handheld Multi Parameter Instrument. 2016 Available at: https://www.ysi.com/556.
Accessed August 9, 2016.
10. Appendices
Appendix A - Aquatic Macroinvertebrates collected at Clear Run
Date
Clear Run
8/3/2016 8/3/2016 8/3/2016 8/3/2016
Taxa Name (Biotic Index value)
Trichoptera
Family Hydropsychidae
Cheumatopsyche spp (6.6)
1
5
22
16
Family Leptoceridae
Nyctiophylax spp (5.9)
1
Diptera: Miscellaneous families
Family Simuliidae
Simulium spp (4.9)
1
Family Tipulidae
Pseudolimnophilia spp (6.2)
1
Tipula spp (7.5)
1
1
Chironomidae
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Polypedilum illinoense (8.7)
1
Rheocricotopus spp (4.7)
1
2
Rheotanytarsus spp (6.5)
1
1
Coleoptera
Family Haliplidae
Haliplus spp (8.7)
4
Odonata
Family Aeshnidae
Boyeria vinosa (5.8)
2
1
Family Calopterygidae
Calopteryx spp (7.5)
6
8
Family Coenagrionidae
Enallagma spp (8.5)
2
1
Ischnura spp (9.5)
2
Oligochaeta
Family Cambarinicolidae (6.0)
28
Family Tubificidae
Immature tubificidae w/o capriliform setae (7.1)
1
Crustacea
Family Cambaridae (7.5)
2
Family Gammaridae
Crangonyx spp (7.2)
2
1
Family Talitridae
Hyalella spp (7.2)
6
2
1
3
Mollusca
Family Physidae
Physella spp (8.7)
1
1
Othertaxa
Family Erpobdellidae
Erpobdella/Mooreobdella spp (8.6)
5
Family Glossiphoniidae
Placobdella multilineata (na)
1
Total Taxa Richness
8
6
8
13
EPT Taxa Richness
1
1
1
2
EPT Abundance
1
5
22
17
Biotic Index
6.52
7.87
6.86
6.14
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Clear Run Stream Restoration and Flooding Management Project
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-nendix B - Scientific Names of Species Identified in Report
WME
Plants
American holly
Ilex opaca
Broomsedge
Andropogon virginicus
Chinese privet
Ligustrum sinense
Clover
Trifolium sp.
Fescue
Festuca sp.
Golden bamboo
Phyllostachys aurea
Ironwood
Carpinus caroliniana
Laurel oak
Quercus laurifolia
Loblolly pine
Pinus taeda
Longleaf pine
Pinus palustris
Post oak
Quercus stellata
Red maple
Acer rubrum
Southern red oak
Quercus falcata
Swamp tupelo
Nysso biflora
Sweetgum
Liquidambar styrociflua
Water ash
Froxinus caroliniana
Water oak
Quercus nigra
Wild onion
Allium sp.
American holly
Ilex opaca
"UN. MR
Animals
American crow
Corvus brachyrhynchos
American kestrel
Falco sparverius
Blue jay
Cyanocitto cristata
Carolina wren
Thryothorus ludovicianus
Corn snake
Elaphe guttata
Eastern bluebird
Sialia sialis
Eastern box turtle
Terrapene carolina
Eastern cottontail
Sylvilogus floridonus
Eastern fence lizard
Sceloporus undulatus
Fox squirrel
Sciurus niger
Green heron
Butorides virescens
Raccoon
Procyon lotor
Southeastern five -lined skink
Eumeces anthracinus
Tufted titmouse
Baeolophus bicolor
Turkey vulture
Cathartes aura
Virginia opossum
Didelphis virginiana
White-tailed deer
Odocoileus virginianus
Yellow-rumped warbler
Dendroica coronata
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Clear Run Stream Restoration and Flooding Management Project
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Appendix C - Planting Plan
The goal of this planting plan is to establish stable wooded ecosystems in appropriate locations along the
reconstructed stream channel. Since the project does not propose wetland impacts, the plan does not seek
compensatory wetland credit except for the area (0.16 acres) of the existing relict spoil piles that will be
removed as described below. The site planting will consist of four basic zones as shown on Figure 6 below
which depicts a typical site cross-section. The break between the riverine swamp forest and bottomland
hardwood forest is shown as a plan view on Figure 7 and is based on differences in soil as well as relative
relief with the riverine swamp forest being flatter and wetter than the bottomland hardwood forest. Species
selected for planting reflect those listed in the Classification of the Natural Communities of North Carolina,
Fourth Approximation from the NC Natural Heritage Program (Schafale 2012). Trees should be planted on 8-
foot centers, which will yield about 680 trees per acre, which then should readily meet the 5-year
requirement of survival of 260 stems/acre. It is expected that natural regeneration will supplement the
planted species, especially in the relatively undisturbed riverine swamp forest. With respect to planting
timing, it is suggested that later winter or early spring would be the best planting time, followed by the fall.
Summer planting should be avoided due to lower survival of planted trees as well as the possibility of
thunderstorms/tropical storms that could cause severe erosion on the recently -graded landscape.
Figure 6: Typical Planting Section
� s
3 I
2
UPLAND RIVERINE RIVE RINE UPLAND
SLOPE SWAMP FOREST SWAMP FOREST SLOPE
FOREST FOREST
10' 10,
STREAIASIDE--, STREAMSIDE
CORRIDOR CORRIDOR
STREAM
CHANNEL
TYPICAL PLANTING SECTION
1dg11
m ffaft & n1ch.1 FIGURE 1
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Clear Run Stream Restoration and Flooding Management Project
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Figure 7: Federally Protected Species Listed for New Hanover County
1. Riverine Swamp Forest — This community will be on the lower end of the site (below station 1+81)
where the landscape is flatter. It is expected that this community will eventually replicate the
Cypress -Black Gum Swamp (Blackwater subtype) as described by Schafale (2012). A mix of
herbaceous grasses and forbs will also be used to encourage rapid vegetation cover. Most of this
area will be undisturbed. A total of 7,000 square feet (0.16 acres) of existing spoil mounds are
present in the riverine swamp forest that will be removed and replanted as riverine swamp forest.
2. Bottomland Hardwood Forest —This non -wetland community makes up the majority of the site to be
graded and is located on the higher elevations of the site from station 1+56 to station 1 + 81, beyond
which the landscape naturally begins to flatten out. A total of 3.16 acres of presently non -wetland
will be graded and then planted as bottomland hardwood forest. Some of this area may become
wetlands and some will probably remain non -wetland (depending on local water table elevation). It
is expected that this community will eventually replicate the Blackwater Bottomland Hardwood
Forest (Low Subtype) (Schafale 2012). A mix of herbaceous grasses and forbs will be used to
encourage rapid vegetation cover.
3. Streamside Corridor — A corridor of approximately 10 feet wide perpendicular to the Ordinary High
Water mark of the stream channel will be planted with live stakes of dogwood and buttonbush to
encourage rapid revegetation and subsequent stabilization of this area. A wetland seed mix should
also be used in this area with potentially some plugs of herbaceous wetland species such as Juncus
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Clear Run Stream Restoration and Flooding Management Project
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and sedges to rapidly establish ground cover. This area is 10 feet wide on both sides of the channel
and covers 0.11 acres of the site immediately adjacent to the stream and therefore subject to the
potentially erosive velocities within the stream. This community is expected to eventually replicate
the Blackwater Levee/Bar Forest with the addition of sycamore that is present on the site (Schafale.
2012). A mix of herbaceous grasses and forbs will be used to encourage rapid vegetation cover. In
addition, decomposable matting (such as coconut fiber) will be installed at the bends of the restored
channel to help stabilize these locations until the vegetation is established, as well as beyond the
stream corridor as warranted. It is anticipated that this area will be maintained in a shrub -dominated
community to reduce the effects on flooding that would occur if the area was allowed to succeed
into mature forest.
4. Upland Slope Forest —These areas cover 1.71 acres of land outside the floodplain and are not
expected to become jurisdictional wetlands due to their elevation above the stream, but are
expected to eventually replicate the Mesic Pine Savanna (Coastal Plain Subtype) (Schafale. 2012).
These areas will be seeded with a mix of herbaceous grasses and forbs to stabilize the areas. The
locations adjacent to the UNC-W property is proposed to be planted with a mix of long leaf pine
(75%) and native oaks (25%) as shown on Table 1. The areas on private property are proposed to be
planted mainly with native oaks (75%) and long leaf pine (25%). However, we recommend that all of
these landowners be directly contacted with the list of potential planting species in order to allow
them to adjust the plantings on locations adjacent to their property. It is also possible that some of
the private landowners may want shrubs such as azaleas or holly to be planted to provide a screen
between the restored stream valley and their backyards.
Table 8: Planting Plan for Clear Run Project
Planting Zone
Riverine Swamp Forest
Species — Common
Name
Swamp Tupelo
Species — Scientific Name
Nyssa biflora
Planting
Mix I(%)
40%
Riverine Swamp Forest
Bald Cypress
Taxodium distichum
40%
Riverine Swamp Forest
Water Ash
Fraxinus caroliniana
20%
Blackwater Bottomland
Hardwood Forest (HF)
Laurel oak
Quercus laurifolia
35%
Blackwater Bottomland HF
Overcup Oak
Quercus lyrata
35%
Blackwater Bottomland HF
Ironwood
Carpinus caroliniana
20%
Blackwater Bottomland HF
Swamp red bay
Persea palustris
10%
Streamside Corridor
Dogwood
Cornus amomum
50%
Streamside Corridor
Buttonbush
Cephalanthus occidentalis
50%
Upland Slope Forest
Long leaf pine
Pinus palustris
75 %
Upland Slope Forest
Water oak
Quercus nigra
10 %
Upland Slope Forest
Southern red oak
Quercus falcata,
10 %
Upland Slope Forest
Post oak
Quercus stellata
5 %
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Clear Run Stream Restoration and Flooding Management Project
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Seed Mixtures for Ground Cover — Mixtures of a variety of seeds will be needed on graded areas to establish
ground cover to reduce erosion. All graded areas will be seeded and mulched with temporary erosion control
seed according to NC standard rates. A riparian seed mix shall be applied to the bottomland hardwood forest
and riverine swam forest. The mix shall meet the specifications of Ernst Seeds NC Coastal Plain Riparian Mix
and be applied at a rate of 20 pounds per acre. A wetland seed mix shall be applied to the streamside
corridor area. The mix shall meet the specification of Ernst Seeds NC Coastal Plain FACW Mix and be applied
at a rate of 20 Ibs per acre. A permanent seeding shall be applied to the upland slope forest to establish and
dense cover of grass while the surrounding forest grows. This permanent mix shall be based on current
standard for NC Erosion Control Protection.
Management of Existing Nuisance Vegetation — Privet (Ligustrum sp.) is present throughout the floodplain
and in adjacent private yards. Privet is a highly invasive nuisance shrub or small tree that can prevent or
severely inhibit the more desirable native vegetation. Therefore, we propose to cut and remove all privet on
the right-of-way and, where stumps remain, they should be cut and sprayed with RoundUp to inhibit privet
regeneration. During the annual vegetation monitoring and maintenance, any areas of dense privet that
become established should receive similar management to encourage the healthy growth of desired species.
Removal of Existing Relict Spoil Piles — There are approximately 10 existing spoil piles in the lower floodplain
of the project that have been placed in wetlands (riverine swamp forest) downstream of the portion of the
channel that will be relocated. We propose to remove these spoil piles and take the historic fill to high
ground using small, low impact equipment. These areas total 7,000 square feet (0.16 acres) and will be
planted with riverine swamp forest species. Since these areas will then be at the elevation of the surrounding
riverine swamp forest, we propose to monitor vegetation survival at two locations (see discussion of
vegetation monitoring below) in order to ensure the Corps of Engineers that restoration has been successful.
However, since these areas are small and completely surrounded by riverine swamp wetland with regular
overbank flooding, we do not propose to conduct hydrologic monitoring for these areas. If these areas meet
the vegetation success criteria of 260 stems per acre survival for planted stems after 5 years of monitoring,
then we propose that the Corps of Engineers credit the City of Wilmington for this amount of riverine swamp
forest restoration credit (0.16 acres).
Installation of Dead Trees to Serve as Perches for Birds — To accelerate the restoration of the stream and
floodplain on the site, numerous trees will need to be removed. It proposed that some of these trees be
stockpiled at the edge of the site and then erected on -site in the regraded floodplain to serve as bird perches.
It is expected that birds will then bring in seeds of native herbs, shrubs, and trees and deposited them
naturally across the site to help ensure a diverse vegetation community. It is expected that these tree snags
would be installed (and anchored appropriately) at approximately 400 foot intervals mostly at the edge of
the floodplain where overbank velocities will be less.
Soils Management — Topsoil from the site is a valuable resource that will be stripped, stockpiled nearby on -
site, and then replaced on the graded sites before planting of trees and shrubs. Based on a field investigation
done in January 2016, there are at least 6 inches of organic -rich topsoil in the relict and active floodplain on
the site. In contrast, the existing sewer easement has little to no organic soil layer. This organic layer overlies
fine or medium sandy loam soils in the floodplain. Removal and stockpiling this topsoil will be done in all
locations where soil thicker than one foot will need to be removed to restore the functioning floodplain. At
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Draft Environmental Assessment
other locations, the soil will be shallowly ripped before planting of trees and shrubs in order to reduce
compaction.
Floodplain Depressions — Small depressions (approximately 100 square feet each) will be created randomly
throughout the site during the final site grading and topsoil replacement. The purpose of these depressions is
to simulate tree tip -up mounds that provide critical wetland habitat for amphibian reproduction. It is
expected that several dozen of these depressions will be created throughout the site.
Vegetation Management Adjacent to UNC-W Property — It is not clear whether the UNC-W property is being
actively managed with fire. If so, these fires will be allowed to periodically burn the planted sloped area
adjacent to the UNC-W property. The exiting access road along the sewer line can serve as a firebreak to
prevent any fires from entering the planted floodplain.
Vegetation Monitoring —To have this project be self -mitigating, the US Army Corps of Engineers will require
annual monitoring of vegetation as well as stream stability. Representative plots will be at semi -permanent
(fixed) locations. Vegetation data will be collected using the Carolina Vegetation Survey Level 2 Protocol (Lee,
et. al. 2008) with regard to percent survival and coverage for planted stems plus volunteer woody vegetation
at permanent locations throughout the site. This protocol recommends that for project with less than 4,000
linear feet of stream work, the sample plots account for 5% of the area of the project. Since each CVS plot is
10 m by 10 m, for our planted project area (of 208,008 m2 or 5.14 acres), a total of 10.4 plots would be
needed. Proposed sample plots should be distributed according to the percent of the site to be planted in
each of the four communities and the number of plots was then adjusted to result in at least two sample
plots per vegetation type in order to capture any variability in plant survival. Therefore, we suggest a total of
13 sample plots distributed as follows which will meet the 5% sampling standard:
• Bottomland hardwood forest (6 plots)
• Riverine swamp forest (2 plots)
• Slopes (3 plots)
• Streamside area (2 plots)
Species composition, density, and survival rates will be provided on an annual basis by plot and the entire
site. Individual plot data will be provided and will include diameter, height, density, vigor, damage, and
percent survival. Planted woody stems will be marked annually as needed to facilitate location of the stems
in subsequent years. In addition, the annual vegetation survey will involve a walk through the entire site and
identification of any locations that have problems with respect to vegetation such as invasive vegetation or
plant mortality. An annual, written report will be prepared and submitted to the Corps of Engineers for five
years and any problems found during monitoring addressed promptly. The Corps requirement of 260 stems
per acre survival for planted stems will be met after five years of monitoring. Results of the annual
monitoring provides will be used as part of the adaptive management approach listed below to meet this
standard.
Wetland and Stream Credits — Based on the vegetation planting and monitoring as well as the monitoring of
the structures in addition to the increase in stream length (from the higher sinuosity), we anticipate that this
project will be sufficiently self -mitigating to adequately offset the projected stream impacts. We also propose
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Clear Run Stream Restoration and Flooding Management Project
Draft Environmental Assessment
(as described earlier), that there will be about 0.16 acres of riverine swamp forest credit that should be
available after vegetation monitoring. If the City is interested in determining the availability of other wetland
credits, a more intensive hydrologic monitoring plan will probably be required by the permitting agencies for
the portion of the site to be replanted as bottomland hardwood forest (potential of 3.16 acres of mitigation —
either restoration or creation credit).
Adaptive Management — In the event the mitigation site or a specific component of the mitigation site fails
to achieve the necessary performance standards as specified in the mitigation plan, the City of Wilmington
will notify the Corps of Engineers and work with the Corps and other interested agencies to develop
contingency plans and remedial actions.
Long-term Management —The City of Wilmington will hold the easement for the corridor where vegetation
will be planted and will be responsible for the long-term management of the site. It is expected that once
vegetation on the site has been successfully restored, annual management activities will be limited to
periodic inspections in response to complaints from local citizens for events such as removal of debris dams
from the channel. Any required management will be funded by the City of Wilmington from existing
maintenance budgets.
References:
Lee, Michael T., Peet, Robert K., Steven D., Wentworth, Thomas R. 2008. CVS-EEP Protocol for Recording
Vegetation Version 4.2. Available at: http://cvs.bio.unc.edu/protocol/cvs-eep-protocol-v4.2-lev1-2.pdf
Schafale, M.P. 2012. GUIDE TO THE NATURAL COMMUNITIES OF NORTH CAROLINA: FOURTH
APPROXIMATION. North Carolina Natural Heritage Program, Department of Environment and Natural
Resources, Raleigh, NC.
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