20200941 Ver 2_13_ACC Preliminary Stream and Riparian Area Restoration Plan_REV_20210120

Preliminary Stream and Riparian Area Restoration Plan
Albemarle Corporate Center
Albemarle, North Carolina
Introduction
The City of Albemarle ("City') is proposing to construct the Albemarle Corporate Center in Albemarle, North Carolina. The
proposed development is a business park including up to 16 separate buildings totaling up to 1,688,750 square feet of
enclosed building space. As part of the site proposal, a road network will also be constructed that connects the corporate
centerto US 52 Business, Leonard Avenue, and Henson Street. Utilities such as gravity sewer, water, and electricity are also
proposed for the site.
As part of the Albemarle Corporate Center project, the drainage of two existing in -line jurisdictional ponds along Poplin
Branch (Ponds PE and PF) is proposed, restoring Poplin Branch to a natural free -flow state (Site 15 in the Pre -Construction
Notification [PCN]). The ponds currently constitute 1.13 acres of open water (0.60 ac. for Pond PE, 0.53 ac. for Pond PF); by
draining them, a significant portion of Poplin Branch will be effectively daylighted, allowing forthe reformation of up to 733
linear feet of 2d order stream, along with abutting riparian floodplain, riparian buffer, and potential floodplain wetlands.
Below is the Preliminary Stream and Riparian Area Restoration Plan developed for the project. Since the ponds have not yet
been drained, the site conditions of the pond beds and former channel are currently unknown. It is, therefore, not possible
to develop a Final Restoration Plan for the site at this point in time. The approach for this project is to drain the ponds
following the Pond Drainage Plan, with the expectation that all or part of the following Restoration Plan can be followed.
However, a site visit will be requested with City, U.S. Army Corps of Engineers (USACE) and N.C. Division of Water Resources
(NCDWR) officials and Chambers Engineering, PA (Chambers) and Three Oaks Engineering, Inc (Three Oaks) staff to review
the site post -drainage. This will allow regulatory agencies to view the site conditions after the ponds are drained, offer input
on the Preliminary Restoration Plan, and assist in the development of the Final Stream and Riparian Area Restoration Plan.
Restoration Goals
The restoration goals forthe Albemarle Corporate Center are to remove the existing earthen dams and drain existing Ponds
PE and PF, restoring Poplin Branch to a natural free -flow state. Additionally, removing the ponds will re -connect aquatic
habitat between the upstream and downstream reaches of Poplin Branch, allowing riverine aquatic species to again have
unobstructed passage throughout the stream reach. It will also provide additional wildlife habitat within the newly restored
riparian areas.
The ponds will be drained following the included Pond Drainage Plan, which has been developed to safely and slowly drain
both ponds, while avoiding/minimizing the release and migration of accreted sediment within the ponds downstream of
the drainage sites. Prior to draining the ponds, it is difficult to know the status of the former channel or the extent of
sediment and debris accumulation. Therefore, the initial approach will be, after the ponds are drained and any large depos-
its of unconsolidated sediments that are prone to erosion removed, to breach the earthen dam downstream of Pond PE
and allow Poplin Branch to begin to naturally reform and re-channelize, establishing a natural stream flow pattern through
the drained areas. This approach will allow the stream to follow as a similar flow pattern as prior to being dammed. Where
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and when needed, the stream channel and banks will be stabilized, with methods such as coir fiber matting, rip rap bank
stabilization, and live staking. Substrate composition within the thalweg will be monitored to determine if active natural
substrate sorting is occurring along the stream reach and if any additional measures are required to assist the streambed's
reestablishment.
After the ponds have been drained and Poplin Branch has begun to naturally find its path and hydrological function (includ-
ing dynamic channel processes) has started to be restored, any additional accumulated "unnatural" sediment will be re-
moved from the exposed areas outside of the streambanks and the area will be graded to an appropriate elevation and
contour to match the upstream and downstream reaches surrounding the formerly ponded areas. The final grading ap-
proach will not be determined until after the ponds have been drained and the agency site visit has occurred.
The graded areas will initially be stabilized with a native riparian plant seed mix (herbaceous species). The restoration will
also rely on the expected migration of Facultative to Obligate species present in adjacent areas (depending on the ultimate
hydrology of the exposed area) establishing themselves within the exposed pond beds and capturing the newly available
habitat. Once the streamside areas are initially stabilized, the seeded areas outside of the streambanks will then be planted
with appropriate floodplain woody species. Stem count and planting density will ultimately be determined once it is clear
how much of the area will be viable floodplain/riparian buffer. The expectation, post -planting, is to vegetate an area at least
50 feet in width perpendicular to the restored stream in both directions with woody species. Already forested areas outside
of but abutting the re -planted area will be considered in the revegetated width. Species composition has been developed
to match existing riparian conditions upstream and downstream of the site as much as possible.
Post -restoration monitoring will be performed that will primarily include stream and streambank monitoring, planting suc-
cess monitoring, and monitoring for the establishment of floodplain wetlands. Ultimately, the area to be restored will be
protected ad-infinitum via a deed restriction, easement, or other site protection instrument.
Pond Drainage Plan
Please see the attached Pond Drainage Plan for Ponds PE and PF.
Grading Plan
The grading strategy is to establish continuity between the drained area and the upstream and downstream riparian areas
and floodplains, with the goal of matching the elevation, contours, and slope with the surrounding areas. Removal of ac-
creted sediment from the drained area is also planned, to return the area to natural conditions; this will occur prior to
grading and plans for its removal and proper disposal will be included in the Final Stream and Riparian Area Restoration
Plan. If required, grubbing of old tree stumps and removal of accumulated debris will also occur. If required, streambank
grading to a more stable slope will also be considered to further stabilize the establishing banks/ portions of banks and
facilitate floodplain access. At this point in time, it is unknown what the ultimate strategy will be to accomplish these goals
due to the uncertainty of the site conditions under the filled ponds. Therefore, specific details related to the grading of the
drained areas will be developed for the Final Restoration Plan once site conditions are known.
Stabilization Plan
Due to the unknown conditions currently within the ponded areas, it is difficult to ascertain the condition of the pond beds
and the former channel. This complicates preliminarily design and implementing any natural stream design at this phase of
the project. Therefore, the project approach is to allow for Poplin Branch to begin to establish its natural channel to use as
the basis for the Final Stream and Riparian Area Restoration Plan. Channel establishment will be monitored starting with
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the draining phase of the project and continue throughout the restoration process until the stream channel is deemed
stabilized by USACE and NCDWR. Intervention techniques will be determined in the field, if necessary, and may include:
1) Sediment removal from channel
2) Armoring of portions of stream bank with rip rap
3) Stabilizing stream bank with coir fiber matting
4) Laying back the slope of portions of the stream bank to minimize erosion
5) Live staking (if required, on no closer than 3-foot centers; would be done concurrent with other woody plantings)
Any/all of the above techniques will be approved by USACE and NCDWR, if required, and incorporated into the Final Resto-
ration Plan, along with any cross sections and/or plan details related to the stabilization strategy. The goal will be to establish
successful channel stability, survival of live -staked vegetation (if required), and lack of significant bank erosion, channel
widening, or down -cutting.
Planting Plan
It will be difficult to determine the amount of area available for replanting until the area is drained and the stream has
begun to re-establish itself, therefore, the area and exact number of re -plantings cannot be determined at this point. How-
ever, a general strategy of how to replant has been developed that includes the initial re -seeding of the riparian area with
a native riparian plant seed mix (herbaceous species) to provide early stabilization, followed by planting of native riparian
woody species (rooted stock; saplings or cuttings) to provide further stability. General planting density and species to be
planted are outlined below and will include native species similar to those present in the surrounding riparian areas. The
expectation, post -planting, is to vegetate an area at least 50 feet in width perpendicular to the restored stream in both
directions with wood species. Already forested areas outside of but abutting the re -planted area will be considered in the
revegetated width. Some areas of revegetation may exceed the 50-foot width if the exposed pond bed is wider than that.
Monitoring of plantings for up to 7 years and calculating survival based on plants/acre each yearwill be the primary measure
of planting success (which will be approved by USACE and NCDWR). A secondary measure will be the amount of surrounding
native species that migrate into the drained area.
Initial re -seeding post -dam removal
Afterthe ponds have been dewatered, accreted sediment has been removed, and riparian areas have been graded to match
existing upstream and downstream contours and elevation, the new riparian areas will be initially re -seeded with a native
riparian plant seed mix comprised of native herbaceous species that are at least Facultative in growth habit. The amount of
area available for replanting will not be known until the pond areas are drained. Seeding will occur during the appropriate
window just prior to or during the growing season. Seeding technique will depend on the site conditions but may include
hand seeding, broadcast seeding, a combination of both, or another site -appropriate technique. The use of bioengineering
material, such as coir fiber matting, will depend on site conditions at the time of seeding. A pH -appropriate organic material
(i.e., mulch, compost, leaf litter, pine straw, etc.) will be overlain on the seeded areas; no fertilizers or soil enrichment such
as lime will be used so as to prevent water contamination. This seeding will provide initial vegetative stabilization while the
area is still re-establishing itself and will provide some habitat for native wildlife. If areas exhibit erosion and require addi-
tional stabilization while the herbaceous vegetation is establishing itself, those areas will be specifically addressed with
additional stabilization techniques, including bioengineering materials. Also, if re -seeding is required in any areas, it will be
done during the appropriate time of growing season. Seeding of herbaceous plants will be the effective start of plant mon-
itoring Year 1.
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Planting of woody species
Once the herbaceous vegetation has established itself and the riparian areas are stabilized, native woody rooted stock will
be planted in the form of saplings or cuttings. Species that are planted will be similar to those within the floodplain upstream
and downstream of the pond drainage, but species composition will be based on sapling/cutting availability. Species may
include, but are not limited to:
1) Red maple (Acerrubrum)
2) Sweetgum (Liquidomborstyrocifluo)
3) Tag alder (Alnus serruloto)
4) Sycamore (Plotonus occidentolis)
5) Red elm (Ulmus rubro)
6) Green ash (Froxinus pennsylvanico)
7) Tulip poplar (Liriodendron tulipifera)
8) Box elder (Acer negundo)
Saplings will be planted at approximately 6- to 10-foot centers, random spacing, averaging 8-foot centers to allow for an-
ticipated branch and canopy growth. This planting pattern equates to roughly 680 planting/acre; however, ultimate density
will be based on available riparian area post -drainage. Sapling planting techniques, such as the Dibble Planting Method, will
be determined based on site conditions at the time of planting. At minimum, the plan is to vegetate an area at least 50 feet
in width perpendicular to the restored stream in both directions with woody species. Already forested areas outside of but
abutting the re -planted area will be considered in the revegetated width. Some areas of revegetation may exceed the 50-
foot width if the exposed pond bed is wider than that.
If live staking of the stream banks is required, it will be done concurrently with the riparian area planting. Saplings/cuttings
will be placed, on average, on 3-foot centers on the banks and will include species such as black willow (Solix nigro) and silky
dogwood (Cornus omomum).
The species list for re -planting of the riparian area and stream banks will be provided to USACE and NCDWR prior to planting
for approval.
Assessment for migration of native species from adiacent areas
A general assessment of the riparian areas will occur annually for up to 7 years to determine whether native species from
adjacent areas have migrated and established themselves. This assessment will occur concurrent with any other plant mon-
itoring efforts. A species inventory will be compiled each year of monitoring to track what new species have successfully
migrated into the area.
Plant monitoring plan and success
The planted riparian areas will be monitored annually for up to 7 years (or other earlier predetermined end to the monitor-
ing plan), beginning with the seeding of herbaceous plants effectively starting Year 1. Success of woody and herbaceous
planting will be assessed annually. Success for vegetation monitoring within the riparian area will depend on agency input
and approval; based on other similar projects, an example success measure for woody species is the survival of at least 260
stems per acre of 7-year-old trees/saplings at year 7. At least 50-feet of woody riparian buffer is also anticipated.
Success of herbaceous vegetation will be assessed based on the stabilization of the area and overall coverage of herbaceous
plants compared to reference areas upstream and downstream of the restored area. A general assessment of the area to
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determine whether native species from surrounding areas have migrated into the area will also be conducted annually;
success of this component will be measured on whether these species have successfully established themselves in at least
a portion of the new area at year 7.
Monitoring Plan
Site monitoring will consist of the following phases:
1) Pond drainage monitoring
2) Monitoring of sediment removal and grading
3) Monitoring of channel stability
4) Plant monitoring
5) Monitoring of wetland development
Pond drainage monitoring
This monitoring will follow the monitoring plan outlined in the Pond Drainage Plan. The goal is to minimize the release and
migration of accreted sediment within the ponds downstream of the drainage sites. The pre -drainage conditions of the
reach of Poplin Branch downstream of the ponds will be photo -documented so that a pre- and post -drainage comparison
can be completed to determine whether the Pond Drainage Plan was successful. The drainage site and the downstream
reach will be monitored during and after pond drainage and will be photo -documented to identify any complications related
to the pond release. If at any time during the drainage an issue related to sediment release downstream or erosion related
to the release, drainage will be halted until the issue is rectified. As-builts will be provided in the Final Stream and Riparian
Area Restoration Plan once the ponds have been drained and graded. Please see the Pond Drainage Plan for more details.
Monitoring of sediment removal and grading
After the ponds have been drained, the downstream earthen dam breached, and Poplin Branch has begun to naturally find
its path and restore its hydrological function, accumulated sediment will be removed from the exposed areas outside of the
streambanks and the area will be graded to an appropriate elevation and contour to match the upstream and downstream
reaches surrounding the formerly ponded areas. The area will be photo -documented, along with the upstream and down-
stream reaches, to monitor grading success. Monitoring will consist of confirming proper disposal of removed sediment,
confirmation that no sediment is being released into the stream during either removal orgrading operations and confirming
that the contours and elevation of the site match upstream and downstream reaches via surveying before moving on to the
planting phase.
Monitoring of channel stability
Monitoring of this phase will begin at the drainage phase of the project and will continue up to 7 years afterwards, or when
the stream channel is deemed stabilized by USACE and NCDWR. The goal is to allow Poplin Branch to re-establish itself
within the drained area to re -connect to both the upstream and downstream reaches surrounding the ponds. As monitoring
begins, it is recognized that problem areas may occur. In such instances, a plan will be developed to address these areas
which may include techniques outlined in the Stabilization Plan section above.
Any/all of the above techniques will be approved by USACE and NCDWR, if required. Assessment of channel stability will be
based on successful channel stability, survival of live -staked vegetation (if required), and lack of significant bank erosion,
channel widening, or down -cutting.
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Plant monitoring
Plant monitoring will follow the Planting Plan described above, which states:
The planted riparian areas will be monitored annually for up to 7 years (or other earlier predetermined end to the monitor-
ing plan), beginning with the seeding of herbaceous plants effectively starting Year 1. Success of woody and herbaceous
planting will be assessed annually. Success for vegetation monitoring within the riparian area will depend on agency input
and approval; based on other similar projects, an example success measure for woody species is the survival of at least 260
stems per acre of 7-year-old trees at year 7.
Success of herbaceous vegetation will be assessed based on the stabilization of the area and overall coverage of herbaceous
plants compared to reference areas upstream and downstream of the re -stored area. A general assessment of the area to
determine whether native species from surrounding areas have migrated into the area will also be conducted annually;
success of this component will be measured on whether these species have successfully established themselves in at least
a portion of the new area at year 7.
Monitoring for wetland development
It is possible that jurisdictional floodplain wetlands will naturally develop along the restored portion of Poplin Branch, similar
to the existing wetlands along other portions of the creek and its tributaries. Assessment for potential wetlands will occur
annually, concurrent with plant and stream monitoring efforts, to determine whether wetland development is occur-
ring/has occurred. Methodology outlined in the USACE Regional Supplementtothe Corps of Engineers Wetland Delineation
Manual: Eastern Mountains and Piedmont Region (Version 2.0) will be followed. Areas that show outward wetland hydro-
logical and hydrophytic vegetation indicators will be further assessed to determine soil composition. If an area meets all
three wetland criteria, it will be delineated, and its boundaries located via GPS. This assessment will occur annually for up
to 7 years. Any wetlands that develop will be re -assessed each year to see if their boundaries have changed and the remain-
ing areas will be re -assessed for potential wetland development. At the end of the monitoring period, a final delineation
will occur, and proper wetland and upland forms will be completed. USACE will then be requested to visit the site and verify
any wetlands that have developed over that time frame.
Acquisition of a Site Protection Instrument
A form of site protection instrument, such as a deed restriction or easement, will be pursued to protect the final restored
site once it is clear what the likely boundaries of the restored site will be in the future. The method of protection will be
proposed to and approved by NCDWR and USACE.
Success Criteria
The success of the project's stream and riparian area restoration effort will be measured by the following criteria:
1) Successful pond drainage
2) Re-establishment and stabilization of pond -drained portion of Poplin Branch
3) Grading of riparian areas exposed by pond drainage
4) Planting of riparian areas
5) Establishment of floodplain wetlands
6) Establishment of a site protection instrument
Several of these success measures cannot be specifically determined until after the ponds are drained. However, a general
outline of what would be considered a successful stream and riparian area restoration after pond drainage can be provided.
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Below is a description of the parameters that will be reviewed for each of the above -listed items to determine if the project
is a success.
Successful Pond Drainage
Success of pond drainage will be measured based on whether the proposed Pond Drainage Plan was followed accordingly,
and the area was successfully drained without accreted sediment release downstream of the pond sites. Any variations to
the drainage plan based on site conditions will be noted and detailed to USACE and NCDWR prior to being implemented.
Re-establishment and stabilization of pond -drained portion of Poplin Branch
The success of this component will be measured based on whether Poplin Branch re-establishes itself within the drained
area to seamlessly connect to both the upstream and downstream reaches surrounding the ponds. Due to the unknown
conditions currently within the ponded areas, it is not possible to currently ascertain the condition of the pond beds and
the former channel. This complicates preliminarily design and stringent implementation of a natural stream design at this
point of the project. Therefore, the project approach is to allow for Poplin Branch begin to establish its natural channel to
use as the basis for the Final Stream and Riparian Area Restoration Plan. Channel establishment will be monitored starting
with the draining phase of the project and continue throughout the restoration process until the stream channel is deemed
stabilized by USACE and NCDWR. Ultimately, success will be based on successful channel stability, survival of live -staked
vegetation (if required), and lack of significant bank erosion, channel widening, or down -cutting.
Grading of riparian areas exposed by pond drainage
The success of this component will be measured based on the continuity of the drained area with the upstream and down-
stream riparian areas and floodplains. Grading will aim to grade the drained areas to match the elevation, contours, and
slope of the surrounding areas. Another component of the grading plan will be to remove accreted sediment from the
drained area to return the area to natural ground; this will occur prior to grading and its removal and proper disposal will
be a factor in the success of the restoration effort. Details related to the grading of the drained areas will be developed for
the Final Stream and Riparian Area Restoration Plan once site conditions are known.
Planting of riparian areas
The success of this component will be measured based on success of plantings outlined in the Planting and Monitoring Plans
outlined above. A general strategy of how to replant has been developed that includes the initial re -seeding of the riparian
area with a native riparian plant seed mix (herbaceous) to provide early stabilization, followed by planting of native riparian
woody species (rooted stock; saplings or cuttings) to provide further stability. Monitoring of plantings for up to 7 years and
calculating survival based on plants/acre each year will be the primary measure of planting success (which will be approved
by USACE and NCDWR). A secondary measure will be the amount of surrounding native species that migrate into the drained
area.
Establishment of floodplain wetlands
Ideally, floodplain wetlands similar to those already present on other portions of Poplin Branch and tributaries to Poplin
Branch will establish themselves once the ponds have been drained. During annual site monitoring, the site will be assessed
for areas that possess characteristics of jurisdictional wetlands such as hydrological, vegetation, and soil indicators. A final
delineation will be completed at the end of year 7 monitoring to determine the extent of established wetlands in the area.
Success for this component will be the establishment of any wetlands within the de-ponded areas.
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Establishment of a site protection instrument
This request has been provided to the City, which is currently determining the best course of action forth is request. A form
of site protection instrument, such as a deed restriction or easement, will be pursued to protect the final restored site once
it is clear what the likely boundaries of it will be in the future. Success will be measured based on the ability to successfully
protect the site ad-infinitum.
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