19970330 Ver 1_Mitigation Plans_20010712 (4)

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DETAILED WETLAND MITIGATION PLAN
JUL 1 2 2001
RANDLEMAN RESERVOIR WATER SUPPLY
BOB BRANCH MITIGATION SITE
RANDOLPH COUNTY, NORTH CAROLINA
Prepared for:
PIEDMONT TRIAD REGIONAL WATER AUTHORITY
Prepared by:
EcoScience
EcoScience Corporation
1101 Haynes Street, Suite 101
Raleigh, North Carolina 27604
July 2001
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TABLE OF CONTENTS
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LIST OF FIGURES ................................................. iii
LIST OF TABLES .................................................. iv
1.0 INTRODUCTION ...............................................1
1.1 PURPOSE ..............................................1
1.2 OBJECTIVES OF WETLAND RESTORATION ...................... 1
1.3 PRIMARY METHODS FOR WETLAND RESTORATION ............... 3
1.4 MITIGATION SITE SELECTION ................................ 4
2.0 METHODS ..................................................8
3.0 EXISTING CONDITIONS ........................................ 11
3.1 PHYSIOGRAPHY, TOPOGRAPHY, AND LAND USE ................ 11
3.2 SOILS ................................................13
3.3 PLANT COMMUNITIES .................................... 15
3.4 HYDROLOGY ..........................................17
3.5 WATER QUALITY .......................................18
3.6 JURISDICTIONAL AREAS .................................. 19
4.0 WETLAND RESTORATION STUDIES ............................... 21
4.1 RESTORATION ALTERNATIVES ANALYSES ..................... 21
4.2 SURFACE WATER ANALYSES ............................... 23
4.3 GROUNDWATER MODELING ................................ 27
4.4 REFERENCE GREENTREE IMPOUNDMENTS ...................... 30
4.5 REFERENCE PLANT COMMUNITIES ........................... 34
5.0 WETLAND RESTORATION PLAN .................................. 41
5.1 IMPOUNDMENT / WEIR CONSTRUCTION ....................... 43
5.2 STEP-POOL GRADE CONTROL STRUCTURE ..................... 43
5.3 WOODY DEBRIS DEPOSITION ............................... 45
5.4 WETLAND COMMUNITY RESTORATION ....................... 45
6.0 MONITORING PLAN ........................................... 50
6.1 HYDROLOGY ..........................................50
6.2 HYDROLOGY SUCCESS CRITERIA ............................ 50
6.3 SOIL ...................................50
6.4 SOIL SUCCESS CRITERIA .................................. 52
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6.5 VEGETATION ..........................................52
6.6 VEGETATION SUCCESS CRITERIA ........................... 53
6.7 REPORT SUBMITTAL ..................................... 54
7.0 IMPLEMENTATION SCHEDULE ................................... 55
8.0 MANAGEMENT PROGRAM ......................................56
9.0 DISPENSATION OF PROPERTY ...................................58
10.0 WETLAND FUNCTIONAL EVALUATIONS ............................ 59
10.1 EXISTING CONDITIONS ................................... 59
10.2 PROJECTED, POST-RESTORATION CONDITIONS ................. 59
11.0 REFERENCES ................................................60
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LIST OF FIGURES
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Figure 1: Mitigation Site Locations: Randleman Reservoir .................... 2
Figure 2: Site Location: Bob Branch Mitigation Site ........................ 6
Figure 3: Aerial Photograph (1999) ................................... 9
Figure 4: Physiography, Topography, and Land Use ....................... 12
Figure 5: Soil Map Units .......................................... 14
Figure 6: Plant Communities ....................................... 16
Figure 7: Jurisdictional Wetlands .................................... 20
Figure 8: Flood Frequency Analysis .................................. 26
Figure 9: Site Location: Falls Lake Greentree Impoundment ................. 31
Figure 10: Site Location: Country Line Creek Greentree Impoundment ........... 32
Figure 11: Site Location: Jordan Lake Greentree Impoundments ............... 33
Figure 12: Conceptual Impoundment Design ............................. 35
Figure 13: Reference Greentree Impoundment ........................... 36
Figure 14: Reference Plan View and Cross Sections ....................... 37
Figure 15: Hydrology Restoration Plan ................................. 42
Figure 16: Conceptual Design: Step-Pool Grade Control ..................... 44
Figure 17: Planting Plan ........................................... 49
Figure 18: Monitoring Plan / Mitigation Design Units ....................... 51
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LIST OF TABLES
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Table 1: Estimated Acreage of Mitigation Design Units Based on
Preliminary Studies for 10 Potential Mitigation Sites Associated
with the Randleman Reservoir ................................ 5
Table 2: Water Surface Elevation Estimates for Various Flood Frequencies ...... 24
Table 3: Modeled Groundwater Discharge Zone of Influence
on Wetland Hydroperiods: Congaree Soils ....................... 29
Table 4: Reference Forest Ecosystem Plot Summary ..................... 39
Table 5: Reference Forest Ecosystem Plot Summary ...................... 40
Table 6: Planting Plan ........................................... 47
iv
DETAILED WETLAND MITIGATION PLAN
RANDLEMAN RESERVOIR WATER SUPPLY
BOB BRANCH MITIGATION SITE
RANDOLPH COUNTY, NORTH CAROLINA
1.0 INTRODUCTION
1.1 PURPOSE
The Piedmont Triad Regional Water Authority (PTRWA) proposes development of the
Randleman Reservoir in Randolph and Guilford Counties, North Carolina (Figure 1). The
purpose of this project is to develop a safe and dependable water supply source for North
Carolina's Piedmont Triad region that will satisfy the projected water demand for a period of
50 years. The proposed 3000-acre reservoir will unavoidably impact approximately 121 acres
of wetlands through impoundment and establishment of an open water system. These
jurisdictional wetlands are subject to regulation under Section 404 of the Clean Water Act
(CWA) (33 U.S.C. § 1344).
For unavoidable wetland impacts, compensatory mitigation is required to facilitate no net loss
of wetland functions in the region. Compensatory mitigation is typically performed to replace
similar wetland types and wetland functions as those impacted (for example, forested, stream-
side wetlands). Wetland restoration, creation, enhancement, and preservation are typical
methods designed to offset wetland impacts. The North Carolina Division of Water Quality
(DWQ) has instituted a policy that prefers a minimum of 1 acre of wetland be restored or
created for every acre of wetland impacted. Subsequently, remaining wetland functional
replacement needs may be off-set through wetland enhancement and/or preservation.
The purpose of this study is to evaluate wetland restoration/creation potential at Bob Branch,
a proposed mitigation site located approximately 1300 feet upstream of proposed reservoir
pool elevations. The project boundary encompasses 25.4 acres. Wetland mitigation is
projected to involve approximately 14.7 acres of created/restored wetlands and open waters
and approximately 0.7 acres of preserved/enhanced wetlands. Other sites will be evaluated
in separate documents to address the 121-acre mitigation needs of Randleman Reservoir.
1.2 OBJECTIVES OF WETLAND RESTORATION
The primary objectives for wetland restoration include the following.
1) Restore or create 121 acres of wetlands as required under regulatory guidance.
0 2) Assist in protecting the drinking water supply from pollutants discharged from
the developing upstream watersheds. Excess nutrients, fecal coliform bacteria,
In sediments, and chemical contaminants (metals, etc.) represent the primary
water quality concerns for the reservoir.
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3) Maximize benefits to water quality through establishment of functioning
wetlands above the reservoir pool.
4) Replace habitat for wetland-dependent wildlife displaced by establishment of
open water.
5) Maximize the acreage of wetland restoration or creation achieved at the Bob
Branch mitigation site.
Goals 1-4 will be accomplished at multiple sites, including Bob Branch.
Water quality benefits are maximized by reducing the capacity for sediment to reach open
water within the reservoir pool. Entrenched streams in the region have abandoned adjacent
floodplains and tend to discharge large quantities of sediment into water supply reservoirs
(Simmons 1976). Within reservoir pools downstream of entrenched streams, sediment from
the watershed is deposited directly into the water supply, in a permanently inundated, reducing
environment. Without periodic oxidation processes, pollutants generally dissolve within the
water column and consequently reduce drinking water quality.
Therefore, wetland restoration for water quality should be designed to reduce entrenchment,
erosion, and sediment transport within streams and to entrap sediment within vegetated
wetland surfaces. Sediment would be deposited on floodplain surfaces that periodically dry
out in areas outside of the reservoir pool. Wetland vegetation would be established on the
alluvial deposition to stabilize the sediment and provide for pollutant recycling through
oxidation (drying) and reduction (wetting) processes. Wetland vegetation would serve to
provide nutrient uptake and recycling functions within deposited sediment. Using this
rationale, entrenched stream and terrace systems would be converted into alluvial wetland
fans or greentree impoundments. A highly sinuous (E) to braided (D) stream system would-be
developed within the alluvial deposition area (Rosgen 1996).
1.3 PRIMARY METHODS FOR WETLAND RESTORATION
Two primary methods for wetland restoration have been proposed to extend the sediment
wedge into design wetlands above the reservoir pool, restore 121 acres of riverine wetlands,
and provide suitable habitat for wetland dependent wildlife. Primary methods include: 1) in-
stream structures designed to reduce sediment transport capacity, and 2) greentree
impoundments designed to allow management of water levels and sediment deposition
patterns.
In-Stream Structures
In-stream structures are proposed primarily along dredged or entrenched stream corridors on
relatively low-slope valley floors (<0.009 rise/run) supporting forest vegetation and broad
floodplains (greater than 500 feet in width). Adjacent floodplains have been abandoned by the
incised stream and converted to elevated terraces not regularly exposed to overbank flooding
or wetland hydrodynamics. Properly designed in-stream structures are expected to reduce the
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the channel, increase overbank flooding from the channel onto the floodplain, reduce sediment
p transport capacity, and provide greater sediment deposition within vegetated wetlands.
Greentree Impoundments
Greentree impoundments are typically proposed on more steeply sloped, narrow floodplains
and stream terraces (>0.008 rise/run) or where relatively severe stream channel degradation
and steepening has occurred above the reservoir pool. Greentree impoundments have also
been considered in instances where water levels may need to be controlled for wetland
10 development in rapidly urbanizing areas. The greentree impoundment option is the preferred
alternative for wetland restoration/creation at Bob Branch.
In general, a greentree impoundment consists of a floodplain levee and controllable outlet
structure that is modified periodically to promote the development of forested wetlands.
Functioning greentree impoundments above the lake reservoir are expected to provide for
significant nutrient uptake, recycling, and management benefits, including increased habitat
for wetland-dependent wildlife species.
The elevation of the outlet is typically raised during winter months to promote ponding,
sediment deposition, and waterfowl habitat. The elevation of the outlet is lowered in early
spring to allow for vegetation growth, nutrient uptake, and seedling establishment. Regular
monitoring and maintenance of the wetland system is critical, including periodic vegetation
sampling, periodic replanting, structural repair, and precise hydrologic control on a semi-annual
basis.
1.4 MITIGATION SITE SELECTION
During the environmental impact assessment, project planners identified and evaluated a total
of 25 potential mitigation sites within stream corridors extending above the reservoir pool. A
description of mitigation potential for each of these sites was prepared in previous documents
(ESC 1998a, ESC 1998b, ESC 1999).
Of these 25 sites, 10 sites were determined to support wetland restoration / creation potential
on up to 121 acres of floodplain. Table 1 and Figure 1 depict the location of each site and
projected areas potentially available for wetland restoration use.
This document details restoration and enhancement procedures for riverine wetland restoration
and creation along Bob Branch, one of the 10 mitigation sites (Figure 2). The Bob Branch
mitigation site (Site) consists of approximately 32 acres that encompass the stream and
adjacent floodplain. The stream drains a watershed of approximately 2.95 square miles (1885
acres). A series of greentree impoundments is proposed within the stream channel and
adjacent floodplain to reduce the rate of groundwater discharge from the floodplain into the
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Site Location ^ i
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Reservoir
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Source: USGS 7.5 Minute Topo Maps (- -
(Glenola / Randleman, N.C.) l? r ! o ^ f.' f
Dwn. by:
RANDLEMAN RESERVOIR MITIGATION PROJECT MAF FIGURE
EcoScience PHASE 11 Ckd by: ES
Corporation BOB BRANCH SITE Date: JUL 2001
Raleigh, North Carolina Randolph County, North Carolina Project:
of-ors

a channel, increase overbank flooding from the channel onto the floodPlain and increase
deposition of sediment on vegetated wetland surfaces above the Randleman Reservoir.
This document includes the following: 1) descriptions of existing conditions, 2) surface and
groundwater hydraulic analyses, 3) reference greentree impoundment studies, and 4) reference
soil and forest ecosystem investigations. Detailed plans are provided for wetland
restoration/creation, vegetation planting, site monitoring, and success criteria.
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2.0 METHODS
Natural resource information for the Site was obtained from available sources, including U.S.
Geological Survey (USGS) topographic mapping (USGS Randleman and Glenola 7.5 minute
quadrangles), U.S. Fish and Wildlife Service (USFWS) National Wetlands Inventory (NWI)
mapping, and Natural Resource Conservation Service (NRCS) soil surveys for Randolph County
(USDA, unpublished). These resources were utilized for base mapping and evaluation of
existing landscape and soil information prior to on-site inspection. Current (1999) aerial
photography was obtained and utilized to map relevant environmental features (Figure 3).
Characteristic and target natural community patterns were classified according to constructs
outlined in Schaf ale and Weakley's Classification of the Natural Communities of North Carolina
(1990). North Carolina Natural Heritage Program (NCNHP) databases were evaluated for the
presence of protected species and designated natural areas which may serve as reference
(relatively undisturbed) wetlands for restoration design.
Regional reference (relatively undisturbed) stream and wetland sites were selected to orient
restoration design and to provide baseline information on target (post-restoration) wetland
conditions. A regional vegetation reference database and on-site inventory were used to
characterize target, post-restoration species composition. Topographic maps of the basin floor
were also prepared to determine valley slope characteristics and to establish target (post-
project) water surface elevations within wetland restoration/creation areas. A reference flood
and sedimentation study provided information on sedimentation and wetland development
associated with existing greentree impoundments in the region. Topographic data were
overlaid on wetland restoration areas to establish methods for construction and restoration of
wetland communities within the Site.
Detailed topographic mapping to 1-foot contour intervals was developed by ground survey
paneling and aerial photogrammetric methods. Additional land surveys were performed to
establish channel cross-sections and measure reference wetland surface topography.
Field investigations were performed in the Spring of 2001 including soil surveys, on-site
resource mapping, land surveys, and landscape ecosystem classifications. Existing plant
communities and jurisdictional wetlands were described and mapped according to landscape
position, structure, composition, and groundwater analyses.
Wetland boundaries were obtained from a delineation performed on May 4, 2001, and verified
by the U.S. Army Corps of Engineers (USACE). NRCS soil map units were ground truthed by
licenced soil scientists to verify units and to map inclusions and taxadjunct areas. The revised
soils maps were used as additional evidence for predicting natural community patterns and
wetland limits prior to human disturbances.
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Groundwater conditions were modeled using DRAINMOD, a computer model for simulating
withdrawal rates for shallow soils with high water tables. The model was utilized to
characterize historic hydroperiods, the extent of wetland degradation due to channel
entrenchment, and the potential for wetland restoration through stream modification.
Surface water analyses for the Site were completed using standard study methods of the U.S.
Army Corps of Engineers (USACE) and NRCS. Flood events of a magnitude which are
expected to be equaled or exceeded once on average every 5-, 10-, 25-, 50-, or 100-year
period were selected for use. These analyses reflect either existing or proposed conditions at
the Site. The projected frequency and extent of overbank flooding were used to determine
potential for riverine wetland restoration in floodplain portions of the Site. In addition, potential
for impacts to adjacent roads and bridges was evaluated for pre-project and projected, post-
project conditions.
This Site has been selected for wetland restoration use to promote a reduction in sediment,
nutrients, and pollutants flowing into Randleman Reservoir. Mitigation activities are intended
to provide sediment deposition, and pollutant recycling from surface waters within created and
restored wetland areas. Recycling functions are designed to reduce elevated nitrogen and
phosphorus loads from the watershed towards background (forest) levels, prior to discharge
into the reservoir.
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3.0 EXISTING CONDITIONS
10 3.1 PHYSIOGRAPHY, TOPOGRAPHY, AND LAND USE
The Site is located in the Piedmont Physiographic Province of North Carolina. Physiography
is characterized by moderately hilly terrain with interstream divides intermixed with steeper
slopes along well-defined drainage ways. The Site is situated in the Bob Branch floodplain
within the Cape Fear River Basin (Hydrologic Unit #03030003 (USGS 19741, DWQ Sub-Basin
03-06-08). The Site is located approximately 12 miles southeast of High Point and
approximately 16 miles south of Greensboro. Annual precipitation in the region averages 42
inches per year with June and August representing the months that support the highest
average rainfall (4.21 inches and 4.36 inches, respectively) (USDA 1977).
The project boundary for the Site is defined by the 5-year, post-project flood elevation. The
Site contains an approximately 3500-foot reach of Bob Branch (Figure 4). The on-site section
of Bob Branch supports a primary watershed of approximately 2.02 square miles and flows
into Muddy Creek 0.8 miles downstream. Muddy Creek empties into the Deep River 1.2 miles
downstream of its confluence with Bob Branch. After construction of the Randleman
Reservoir, the downstream portion of the Site will reside approximately 2000 feet upstream
of the reservoir's conservation pool, at 682 feet above mean sea level. On-site floodplain
elevations range from 695 feet to approximately 710 feet.
'10 The Site consists of bottomland hardwood forest corridors forming a buffer along the stream
channel and in a few larger patches. Active agricultural and pasture land occupies both sides
of the floodplain and adjacent terraces. Outfall from a plant nursery supply pond flows into
Bob Branch at the downstream end of the Site. No roads adjoin or intersect the Site. The
nearest road is SR 1944 (Branson Davis Road), which crosses Bob Branch approximately 1
mile downstream of the Site.
Land areas immediately adjacent to the Site consist of agricultural and pasture land and
second-growth forest. A plant nursery operation, with associated greenhouses and water
supply pond, is situated above the floodplain. Another existing pond, within the channel of
Bob Branch, is located at the downstream end of the Site. Ponds and structures are expected
- to remain unaffected by project activities.
An elevated stream terrace forms the primary physiographic landscape area for restoration
planning purposes. The primary variables utilized to segregate landscape units include land
slope, overbank flood frequencies (Section 4.2), and the rate and direction of groundwater
flow (Section 4.3).
The elevated stream terrace physiographic area encompasses approximately 18 acres located
along both sides of the stream channel and open waters of Bob Branch (Figure 4). This
elevated terrace historically supported frequent overbank flooding (estimated at an
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approximate, 1-year return interval) and was periodically re-worked by alluvial processes and
periodic, long term inundation/saturation. Dredging along the stream has reduced the
frequency of overbank flooding within the primary floodplain from an estimated 1-year return
interval to a 2- to 10-year return interval that overtops the constructed levee (Section 4.2).
Therefore, associated riverine wetland functions (sediment retention, nutrient cycling, energy
dissipation, etc.) have been effectively eliminated from the physiographic area by stream
alterations. Accelerated drainage is evident throughout the stream terrace physiographic area
due to dredging activities and secondary stream diversions.
During dredging and clearing programs along Bob Branch, portions of the stream terrace appear
to have been converted for agricultural use. However, some of these agricultural tracts have
been abandoned over the last several decades, allowing re-development of disturbance
adapted, successional communities. Under historic conditions, natural communities are
expected to include Piedmont bottomland hardwood forest and oval to linear pockets of
riverine swamp forest in low-lying areas (Schafale and Weakley 1990).
3.2 SOILS
Surficial soils have been mapped by NRCS (USDA, unpublished). Soils were verified in the
spring of 2001 by licensed soil scientists to refine soil map units and locate inclusions and
taxadjunct areas. Systematic transects were established and sampled to ensure proper
coverage. Refined soil mapping is depicted in Figure 5. Primary soil types include the
Chewacla series and Wehadkee series.
Chewacla (F/uvaquentic Dystrochrepts) soils encompass 23.4 acres of the 25.4-acre Site.
Chewacla soils are somewhat poorly drained, nonhydric soils which have been formed on
floodplains primarily by fluvial activity. Chewacla soils generally exhibit broad, inter-layered
variability in texture and permeability dependent upon energy dissipation and sediment
deposition patterns associated with each stream overbank flood event. Soil texture generally
ranges from coarse sandy loam to silt loam of moderate to moderately rapid infiltration.
Important factors in the formation and maintenance of wetland systems as hydric inclusions
in the Chewacla map units include 1) microtopography and variability in fluvial deposition
across the landscape, 2) groundwater and surface water movement from adjacent uplands
along the outer edge of the floodplain, and 3) groundwater discharge rates from the interior
floodplain into the stream channel. These soils are subject to frequent flooding. The seasonal
high water table is within 0.5 to 1.5 feet. Stream dredging and conversion to agricultural
lands has likely increased the extent of Chewacla (nonhydric) soils and concurrently decreased
the extent of Wehadkee (hydric) map units in the Site.
Hydric soils are defined as "soils that are saturated, flooded, or ponded long enough during the
growing season to develop anaerobic conditions in the upper soil layer" (USDA 1987). Hydric
soils comprise the Wehadkee series (F/uvaquentic Endoaquepts), located primarily within relict
13

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backwater sloughs, depressions, ephemeral channels, and swales which remain within the
secondary floodplain. These soils are very deep and poorly to very poorly drained. Under
existing conditions, the Wehadkee series comprises approximately 1.3 acres (5 percent) of the
Site.
3.3 PLANT COMMUNITIES
Plant communities are influenced by logging, grazing and past conversion to agricultural lands.
Two primary communities have been identified for descriptive purposes: 1) basic mesic forest,
and 2) crop land / pasture (Figure 6).
Basic Mesic Forest
Basic mesic forest accounts for approximately 23 acres (74 percent) of the project area. This
community occurs along the stream channel of Bob Branch and tributary drainages. A large,
contiguous section exists at the downstream (eastern) end of the Site, adjacent to an existing
pond. The basic mesic forest assemblage has experienced limited degradation from past
logging, and exists in a relatively intact second-growth state. The forest canopy includes
sweetgum (Liquidambar styraciflua), red maple (Ater rubrum), sugar maple (A. barbatum),
sycamore (Platanus occidental/s), green ash (Fraxinus pennsylvanica), tulip poplar (Liriodendron
tulipifera), American elm (Ulmus americana), black willow (Salix nigra), hackberry (Celtis
laevigata), and, in drier areas, eastern red cedar Vuniperus virginiana) and hickory (Carya sp.).
Under-story and shrub layer species distribution is variable along hydrologic gradients and
sunlight regimes, and includes horse sugar (Symplocos tinctoria), ironwood (Carpinus
caroliniana), hop-hornbeam (Ostrya virginiana), elderberry (Sambucus canadensis), multiflora
rose (Rosa multiflora), American hazelnut (Corylus americana), and Chinese privet (Ligustrum
sinense). Vines include muscadine grape (Vitis rotundifolia) and Japanese honeysuckle
(Lonicera japonica), which becomes invasive in sunnier areas. The herb layer includes
speedwell (Veronica persica) forming a thick carpet in some areas, and species diagnostic for
this community such as spring beauty (Claytonia virginica), common blue violet (Viola
papilionacea), and jewelweed (Impatiens capensis). Other herbs are bedstraw (Galium sp.),
chickweed (Stellaria media), dock (Rumex sp.), Indian strawberry (Duchesnea indica), bitter
cress (Cardamine parviflora), and cranefly orchid (Tipularia discolor).
Crop Land I Pasture Land
Approximately 8.2 acres of the project area remains as active crop land and maintained
pasture land. These areas are mainly on slopes and terraces along the northern and southern
edges of the Site. Pasture land is dominated by a variety of grasses and herbs. The
predominant species is fescue (Festuca spp.). Other characteristic, volunteer species occurring
in fields and pastures include asters (Aster spp.), goldenrods (Solidago spp.), dock, buttercup
(Ranunculus sp.), wild radish (Raphanus raphanistrum), chickweed, violets (Viola spp.), bitter
cress, winter cress (Barbarea verra), clover (Trifolium spp.), and crabgrass (Digitaria spp.).
15

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IH 3.4 HYDROLOGY
The Site is located within the Piedmont hydrophysiographic province, which encompasses the
IH entire drainage basin for the East and West Forks of the Deep River. The region is
characterized by moderately hilly terrain with interstream divides exhibiting dendritic drainage
all patterns and moderately steep slopes along valley floors (0.005-0.015 rise/run).
The region is characterized by moderate rainfall. In Randolph County, precipitation averages
42 inches per year with precipitation evenly distributed throughout the year (USDA 1977).
Large floods (20-100 year return interval) typically correspond to large thunderstorms and
tropical events in the region.
Bed-load material supplied by the region consists primarily of silts, sands, and weathered
bedrock (very coarse sand and small gravel). Bedrock outcrops are common within incised
streams in more steeply sloped valleys. Suspended load consists primarily of easily eroded
clays and silts, which transport attached nutrients into downstream waters. Erosion and
suspended sediment loads have been linked to nutrification problems within the Piedmont
hydrophysiographic province, including the Randleman Reservoir region (DWQ 2000).
Surface Water
O The Site encompasses a 3930-foot reach of Bob Branch supporting a drainage area of 2.02
square miles. The valley slope measures approximately 0.003 rise/run, suggesting the
presence of a relatively flat valley floor relative to typical conditions in the Piedmont Province.
The lower valley slope may be due to the presence of geologic controls and a change in valley
type downstream from the Site. The floodplain ranges from 350 feet to 400 feet in width
along the length of the Site.
Surface water runoff within the stream terrace would be relatively sluggish in wooded areas.
Surface detention and ponding on the rough soil surface, and interception by dense forest
vegetation, would occur in this area immediately after significant rainfall events with delayed
return flow into the main-stem channel. Cross-valley and down-valley flow would be more
rapid from steep side slopes planted in pasture grasses or crops.
10 Two upstream ponds may be partly responsible for incision of the stream channel. The
average existing bankfull depth of the channel is 2.8 feet, compared with 1.9 feet calculated
from the regional curves based on drainage area. In addition, the average existing cross-
sectional area of the Bob Branch channel measures approximately 62 square feet. According
to regional curves, a stable Bob Branch channel is projected to support cross-sections of
approximately 32 square feet (assumes rural conditions) (Harman et a/. 1999, Rosgen 1996).
The incised channel supports a sinuosity (channel length/valley length) of 1.09. Substrate
within the channel is composed of unconsolidated sand, small gravel, and bedrock outcrops
exposed by incision and localized bank erosion. The channel is classified as an E4c (gravel
dominated channel) based on fluvial geomorphic features (Rosgen 1996).

17

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Stream discharge and flood elevations under existing conditions have been predicted based on
hydraulic models (Section 4.2). Model predictions for the 5- and 100-year storm suggest that
the stream overtops its banks during the 5-year storm. However, entrenchment has likely
confined the 1- year flows within the eroding channel banks, effectively bypassing floodplain
functions associated with pollutant removal and maintenance of wildlife habitat for overbank
flood dependent species.
Groundwater
Surface water hydrodynamics, such as periodic overbank floods, fluvial sediment deposition,
and hydraulic energy dissipation, represent important attributes of floodplains and bottomland
hardwood forest in the region. However, streams in the region typically function as
groundwater withdrawal features throughout most of the year. Therefore, groundwater inputs
from auxiliary watersheds and upland slopes abutting the floodplain represent the primary
hydrologic input resulting in the development and maintenance of riverine wetlands at this Site.
Groundwater gradients in May 2000 and after rainfall events in August 2000 indicate that the
groundwater table typically resides from 1 foot to 6 feet below the land surface. The
groundwater gradient typically remained more than 2 feet below the surface throughout the
stream terrace with a relatively steep gradient induced by the dredged stream channel.
Based on observed groundwater gradients, the Site is expected to support limited groundwater
storage potential typically associated with maintenance of wetland surfaces. Although
adjacent escarpments supply riparian inflow of groundwater, this flow appears steeply inclined
with relatively rapid discharge towards the stream channel. Entrenchment of Bob Branch has
accelerated groundwater discharge to depths of greater than 5 feet below the surface near the
stream channel. Restoration of a shallower (less incised) stream network will generate a flatter
groundwater gradient. However, groundwater models (Section 4.3) suggest that groundwater
tables will continue to remain more than 1 foot below the surface. Therefore, restoration of
wetlands within this Site will require establishment of backwater (surface water induced)
wetlands behind a greentree impoundment.
3.5 WATER QUALITY
Bob Branch, from its source to a point 0.5 mile upstream of its mouth, maintains a State best
usage classification of WS-IV * (Stream Index No. 17-9.6-(1) (DWQ 1998). Class WS-IV
waters are protected as water supplies which are in moderately to highly developed
watersheds. Point source discharges are generally required to meet stringent pre-treatment
standards, to maintain pre-treatment failure (spill prevention) plans, and to perform point
source monitoring for toxic substances. Local programs to control nonpoint source and
stormwater discharge of pollution are also required. The symbol * signifies waters that are
within a designated Critical Supply watershed and are subject to a special management
strategy specified in 15A NCAC 2B .0248. In this case, the watershed areas is within 0.5
mile of a water supply intake for the reservoir.
18
10
The Site consists primarily of existing and former agricultural land, second-growth forest
10 adjacent to the stream channel, and a nursery business with supply ponds. Fertilizers,
pesticides, and nutrients associated with land uses may currently influence water quality in
the vicinity. Restoration of wetland hydrology and diversion of area runoff onto restored
r wetland surfaces will provide local water quality benefits, including important functions such
0 as particulate retention, removal of elements and compounds, and nutrient cycling.
Historically, the floodplain provided water quality benefits to the watershed associated with
Bob Branch. However, runoff from cleared land area effectively bypasses wetland floodplains
and flows directly to the channel and through the Site. Restoration of wetland hydrology and
diversion of watersheds onto restored wetland surfaces will provide for restoration of overbank
flooding and associated water quality benefits above the Randleman Reservoir.
3.6 JURISDICTIONAL AREAS
Jurisdictional areas are defined using the criteria set forth in the U.S. Army Corps of Engineers
Wetlands Delineation Manual (DOA 1987). Approximately 0.7 acre of jurisdictional wetlands
and 0.7 acre of open waters (in-stream habitat) were delineated on-site by ECS, Ltd. and
confirmed by the USACE. Figure 7 depicts the boundary location of existing jurisdictional
systems. Wetland extent was most likely more extensive prior to stream dredging on the Site.
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4.0 WETLAND RESTORATION STUDIES
This section summarizes studies performed to orient restoration design. Studies include the
following:
1) Restoration Alternatives Analyses: Alternatives for wetland restoration relative
to stream, floodplain, and reservoir functions were assessed.
2) Surface Water Analyses: Overbank flooding frequency and extent was evaluated
for wetland restoration alternatives to assess potential for impacts to adjacent
roads and structures.
3) Groundwater Modeling: The effect of drainage features on groundwater wetland
hydroperiods was modeled.
4) Reference Plant Communities: Reference wetland communities were sampled
to predict the target distribution of vegetation to be established in restoration
areas.
5) Reference Physiography and Surface Topography: Reference wetland surfaces
were measured within an existing greentree impoundment to characterize long
term, projected Site conditions.
4.1 RESTORATION ALTERNATIVES ANALYSES
The objectives of this project include the following:
1) Assist in protecting the drinking water supply from pollutants discharged from
the developing watersheds. Pollutants attached to sediment represent the
primary water quality concern for this project.
2) Maximize benefits to water quality through establishment of functioning
wetlands above the reservoir pool.
3) Replace habitat for wetland-dependent wildlife displaced by establishment of
open water.
4) Maximize the area of wetland restoration achieved by the project.
Restoration alternatives suggested by project participants are briefly described below.
Stable Channel Construction
Reconstruction of a potentially stable stream system was assessed as a replacement for the
existing, dredged and incised channel. The new channel would be designed to mimic
referenced, stable attributes including the geomorphic dimension, pattern, and profile needed
to transport water and sediment produced by the watershed. The restored channel would
reduce the rate of groundwater withdrawal from adjacent floodplains, potentially resulting in
wetland hydrology restoration in certain areas.
Stream restoration through natural channel design represents a viable option for this Site. If
applied, approximately 1700 linear feet of channel may be relocated into a sinuous channel
21
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that reduces bank erosion and increases in-stream aquatic habitat. Based on groundwater
models, this option is expected to provide for less than 1 acre of wetland restoration on the
relatively narrow floodplain floor. Because the wetland restoration area is inadequate, the
stable channel construction option was discarded.
Alluvial Wetland Fan Development
This option is designed to elevate water tables and reduce sediment transport within the
floodplain and stream corridor. Alluvial fan development entails placement of fixed, in-stream
weirs within the dredged channel. The in-stream modifications are expected to reduce the
degree of channel incision, increase overbank flooding, reduce stream sediment transport
capacity, and provide greater sediment deposition within vegetated wetlands. The system
would progress toward an alluvial wetland fan where the channel actively migrates across
fluvial material. During the interim period, in-stream structures will sustain significant energy
during flood events; therefore, the potential exists for development of channel by-passes
(shoot cut-offs) around the structures. As such, risk of wetland restoration failure exists. The
structures must be designed to avoid short-circuiting and provide for sediment deposition in
the incised channel.
Over a relatively long period of time, the shallower channel would inevitably abandon the
structures and begin to actively migrate across the restored floodplain. At this point, the
system would need to be monitored for evidence of head-cutting from the downstream reach.
A step-pool channel would need to be established due to the significant change in elevation
immediately above and below the alluvial wetland fan. Because the potential for future head-
cutting is considered significant, this option was discarded. Sites located immediately above
the Randleman Reservoir conservation pool elevation (682 feet above mean sea level) will not
be threatened by future head-cuts because the conservation pool is expected to serve as a
grade control structure. The Bob Branch Site is located above a private pond in the stream
channel. Proposed in-stream structures would be designed to avoid impacts to this pond,
including its use as a grade-control structure.
Greentree Impoundments
This alternative is similar to alluvial fan development described above. However, greentree
impoundments include a floodplain levee and controllable outlet structure that is modified
periodically throughout the year to induce backwater flooding and promote the development
of forested, shrub-scrub, and emergent wetlands. Greentree impoundments have been
constructed above other water supply reservoirs in the region for wetland, wildlife, and
sediment retention functions. These structures can be controlled to regulate the depth and
frequency of inundation based upon objectives of the system. In this case, the structures
would be used to establish vegetated wetlands and limit transport of pollutants into the
reservoir.
In general, the levee system is constructed to provide for less than 2 to 3 feet of inundation
during winter months, to prevent over-topping, and to allow for survival of tree seedlings. The
22
10
winter depth is generally dependent upon the height of seedlings. The raising and lowering of
outlet structures requires regular monitoring and maintenance by qualified personnel to
facilitate the growth of tree species. The actual date that the outlet is modified may vary
Ll annually and is dependent upon localized conditions within the watershed. Seedling mortality
is tracked on an annual basis and the date of spring lowering is modified to maximize the rate
of forest regeneration. Tree species selected for planting may also be modified based upon
collected data. Greentree impoundments designed for forested wetland restoration have failed
in the past, due primarily to lack of resources for long-term monitoring, management, and
manipulation.
Based on alternatives analyses, construction of a greentree impoundment across the Bob
Branch floodplain represents the preferred option for this Site. The capacity to manage,
regulate flows, and regulate sediment transport/deposition rates at the Site outfall will reduce
potential for head-cut migration into an alluvial wetland fan as described above. In addition,
the structures would allow pro-active control of wetland development and function behind
each impoundment.
4.2 SURFACE WATER ANALYSES
Surface drainage on the Site and surrounding area was analyzed to predict the effects of
diverting existing surface drainage into wetland restoration areas along the primary and
secondary floodplains. Several alternatives were evaluated to determine surface water
modifications that minimize potential for impacts to adjacent properties and maximize wetland
acreage.
Hydrologic and hydraulic analyses were completed using standard study methods of USACE
and NRCS. Flood events of a magnitude which are expected to be equaled or exceeded once
on average every 5-, 10-, 25-, 50-, or 100-year period were selected to characterize existing
and proposed conditions at the Site.
Hydrologic Analyses
Hydrologic analyses were carried out using the USACE HEC-1 model to establish the peak
stream discharge for the 5-, 10-, 25-, 50-, or 100-year flood events. The analyses reflect
existing and proposed conditions at the proposed wetland sites.
Input forthe HEC-1 model consisted of synthetic storm precipitation data, drainage area, NRCS
curve numbers, and drainage basin lag time. Table 2 summarizes the total, 24-hour
precipitation event for each storm that was analyzed. Post-project flood elevations reflect
winter (raised) weir heights. Precipitation data was obtained from U.S. National Weather
Service documents (NOAA TP-40 and Hydro-35). The drainage area was delineated on 7.5-
minute USGS topographic maps and then subdivided into sub-basins based on land use or
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location of tributaries. The drainage area for each sub-basin was estimated using a planimeter.
The NRCS curve numbers were estimated using methods described in NRCS TR-55. Sub-basin
lag times were estimated using Snyder's method.
Because there were no on-site gage data, the HEC-1 computer models could not be calibrated.
The models were validated by comparing the 100-year peak discharges estimated from the
HEC-1 models with peak discharges estimated by regional formulas for the Piedmont region
of North Carolina in the USGS Water-Resources Investigations Report 87-4096. NRCS curve
numbers for the HEC-1 models were adjusted until the HEC-1 peak discharges were within 25
- 30 percent of the regional formula values. Table 2 summarizes peak discharges estimated
by the validated HEC-1 model and the regional equations.
Hydraulic Analyses
10 Water-surface elevations of the 5-, 10-, 25-, 50-, or 100-year floods of Bob Branch were
estimated using the USACE HEC-2 computer program. Channel cross sections for the hydraulic
10 analyses were obtained from digital orthophoto maps prepared by Geodata Corporation with
a contour interval of 1 foot. Aerial photography was taken in April 1999.
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Roughness coefficients (Manning's "n") in the channels and on the overbank areas were
obtained from FEMA studies previously conducted in the area and verified with field
inspections of the sites. Roughness coefficients were 0.06 in the main channel and 0.12 for
overbank areas.
Starting water surface elevations and energy slope for existing conditions were estimated
using data from the HEC-1 analysis and digital orthophoto maps. A water surface elevation
computed by the HEC-1 model was used to estimate the water surface at the beginning cross-
section.
Model Results: Existing Conditions
Table 2 summarizes the water surface elevations for existing conditions. Figure 8 depicts
modeled flood elevations for the 5- and 100-year, 24-hour storm event. The model suggests
that Bob Branch overtops its banks on a 5-year interval. Frequent overbank flood events (1-
year return interval) have likely been effectively eliminated along the entrenched channel under
existing conditions. Evidence of minor overbank flooding has been observed only in small,
isolated areas at the Site during field surveys.
Model Results: Proiected Post Restoration Conditions
Several restoration alternatives were evaluated in the hydraulic model to determine the change
in flood elevations for the 5-, 10-, 25-, and 100-year storm events. Modeled alternatives
include in-stream weirs located at systematic intervals within the entrenched channel. Eight
structural arrangements were modeled, including cross-vane weirs spaced at up to 150-foot
intervals within the channel. Channel cross-sectional areas were subsequently reduced along
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with profiles above and below each structure. The structural arrangement was also modified
to establish a pool to pool spacing characteristic of natural channel design.
The selected alternative minimizes potential for impact and maximizes wetland restoration /
creation area associated with the design. In summary, a series of four greentree
impoundments is proposed beginning approximately 700 feet upstream from the existing in-
stream pond. The impoundment weirs will be designed to allow unrestricted channel flows
during periods of increased probability for large (tropical) storms. The weirs were modeled
with top elevations of 698 to 706 feet.
The results of the projected post-restoration model are depicted in Table 2 and Figure 8.
Based on the model, the flood elevation for the 100-year storm is elevated by average of 1.1
feet (Table 2).
Restoration methods are designed to reduce the channel from 5 feet in depth below the
floodplain to saturated / inundated conditions at the floodplain surface during the winter and
early portions of the growing season. The weir and associated water levels would be lowered
during the remaining portions of the year. The model assumes that the weirs have been left
in place during large storm events in the winter months. However, maintenance planning
recommends that weirs be lowered prior to large storms, if possible, to prevent damage to the
structures.
4.3 GROUNDWATER MODELING
Groundwater modeling was performed to characterize water table elevations under historic
(reference), existing, and post-restoration conditions. The groundwater modeling software
selected for simulating shallow subsurface conditions and groundwater behavior at the Site
is DRAINMOD. This model was developed by R.W. Skaggs, Ph.D., P.E., of North Carolina
State University (NCSU), to simulate the performance of water table management systems.
Model Description
DRAINMOD was originally developed to simulate the performance of agricultural drainage
networks on sites with shallow water table conditions. DRAINMOD predicts water balances
in the soil-water regime at the midpoint between two drains of equal elevation. The model is
capable of calculating hourly values for water table depth, surface runoff, subsurface drainage,
infiltration, and actual evapotranspiration over long periods referenced to climatological data.
The reliability of DRAINMOD has been tested for a wide range of soil, crop, and climatological
conditions. Results of tests in North Carolina (Skaggs, 1982), Ohio (Skaggs et a/. 1981),
Louisiana (Gayle et a/. 1985; Fouss et a/. 1987), Florida (Rogers 1985), Michigan (Belcher and
Merva 1987), and Belgium (Susanto et a/. 1987) indicate that the model can be used to
reliably predict water table elevations and drain flow rates. DRAINMOD has also been used
to evaluate wetland hydrology by Skaggs eta/. (1993). Methods for evaluating water balance
equations and equation variables are discussed in detail in Skaggs et a/. (1993).
27
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DRAINMOD has been modified for application to wetland studies by adding a counter that
accumulates the number of events wherein the water table rises above a specified depth and
remains above that threshold depth for a given duration during the growing season. Wetland
hydrology is defined as groundwater within 12 inches of the surface for 28 consecutive days
(12.5 percent of the growing season), and 11 consecutive days (5 percent of the growing
season). Wetland hydrology is achieved in the model if target hydroperiods are met for more
than one-half of the number of years modeled (i.e., 16 out of 31). Groundwater drainage
contours are established on available mapping for various durations of saturation within 1 foot
of the soil surface (i.e. saturation contour for 0-5 percent, 5-12.5 percent, and 12.5-20
percent of the growing season).
Model inputs for DRAINMOD simulations were obtained as follows: the United States
Department of Agriculture (USDA) soil texture classification, number of days in the growing
season (defined as March 26 - November 6), and hydraulic conductivity data were obtained
from the NRCS soil survey for Randolph County and Guilford County (USDA unpublished,
USDA 1977). Inputs for soil parameters such as the water table depth/volume, drained/upflux
relationship, Green-Ampt parameters, and water content/matric suction relationship were
obtained utilizing the MUUF computer software developed by NRCS. Precipitation and
temperature files were obtained for the years 1930 through 1980 for Charlotte, North Carolina.
DRAINMOD simulations were designed to predict the transition zone from Chewacla soils to
Wehadkee soils based on groundwater drainage conditions within a relatively flat floodplain
surface. Chewacla soils represent a non-hydric (non-wetland), somewhat poorly drained soil
that is common on primary floodplains immediately adjacent to streams. The Wehadkee series
comprises hydric (typically wetland), poorly drained soils that are typical in backwater
floodplain areas situated further from drainageways.
Forested conditions (evapotranspiration rates) and published hydraulic conductivity values were
assumed for Chewacla soils. The simulations were run for six channel inverts (0, 1, 2, 3, 4,
6, and 8 feet) and at various target hydroperiods during the growing season. Table 3 provides
a depiction of the groundwater discharge zone of influence by invert depth (elevation below
floodplain). For example, a stream channel invert 6 feet below the floodplain elevation is
modeled as reducing surface hydroperiods below 5 percent of the growing season at a
distance of 215 feet from the channel. A former floodplain surface 6 feet in elevation above
the channel invert and greater than 215 feet from the channel is projected to support
wetlands.
The preliminary groundwater drainage model was interpreted based upon field verification of
NRCS soil map units, channel depth (based on measured cross-sections), and floodplain
elevation (based on topographic maps). Model parameters were set to predict the average
annual duration in which groundwater remains within 1 foot of the soil surface at assigned
28
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Table 3
Modeled Groundwater Discharge Zone of Influence on Wetland Hydroperiod
Chewacla / Wehadkee Soil
Floodplain Groundwater Number of Groundwater
Surface Discharge Zone Years Discharge Zone
Elevation Above of Influence` Wetland of Influence
Channel Invert / (feet) Criteria (feet)
Weir Height' (Surface Met (Surface

f Hydroperiods <5 Hydroperiods <
(
eet) f h 12 5 f h
Number of
Years
Wetland
Criteria
Met
percent o t e
growing season) . percent o t e
growing season)'
Forested Conditions
(relatively high surface water storage and rooting functions)
0 ----- 29/31 ----- 27/31
1 253 20/31 145 16/31
2 85 16/31 225 16/31
3 125 16/32 275 17/31
4 160 16/31 315 16/31
6 215 16/31 380 16/31
8 245 16/31 405 16/31
1: "Weir Height" is assumed to represent the effective depth (invert) of the drainage feature.
2: Soil hydraulic conductivities and drainage rates have been generalized based upon NRCS data and regional
averages.
3: Discharge Zone of Influence is equal to %: of the modeled ditch spacing
4: Based on field observations, soil types projected to support wetland hydroperiods for greater than 5 percent
to 12.5 percent of the growing season are expected to exhibit characteristics more indicative of the
Wehadkee series, a poorly drained soil. Based on the model, these areas may occur on floodplains within 25
feet to 200 feet of streams potentially lacking significant effluent (groundwater withdrawal) character, such
as very shallow channels. Conversely, the model suggests that the transition from Chewacla soils (somewhat
poorly drained) to Wehadkee soils (poorly drained) may be achieved adjacent to larger (dredged) effluent
channels at distances ranging from 300 feet to 400 feet from the drainage structure (assuming a relatively
flat floodplain surface).
29
10
elevations above a channel invert or in-stream structure. The floodplain elevations outside of
the groundwater drainage contour and at the modeled channel depth were judged to have a
hydroperiod greater than 5 percent.
Post-Restoration Model Applications and Results
For groundwater wetland restoration, the primary objectives of this project include 1) a
reduction of channel incision along Bob Branch and associated tributaries, 2) an elevation of
the groundwater gradient into the rooting zone for developing vegetation, and 3) establishment
IRA
0 of minimum wetland hydroperiods encompassing 5 percent of the growing season, which are
typical for riverine wetlands in the Piedmont hydrophysiographic province. Therefore, the
effective post-project depths of the Bob Branch channel will be reduced from an average of
5 feet under existing conditions to gradients between 1 to 3 feet below the floodplain.
DRAINMOD simulations modeled the zone of influence of the post project channel on wetland
hydroperiods within the primary floodplain. The maximum zone of influence may be used to
predict the area of groundwater wetland hydrological influence that may result due the
elevation of stream flow within the channel. In addition, the model provides an estimate of
the area that may continue to be affected in perpetuity by the stream channel at a depth of
1 to 3 feet below the floodplain elevation.
Based on these simulations, the post-restoration channel is expected to continue to effectively
drain groundwater from the Chewacla soils within the map unit. Model simulations indicate
that a series of in-stream weirs placed to within 1 foot of the adjacent floodplain elevation may
not restore significant areas of wetlands in Chewacla soils. A channel invert 2 feet below the
adjacent stream terrace continues to effectively drain an area 85 feet adjacent to the drainage
feature. Gradual slopes in remaining portions of the outer floodplain are projected to continue
draining towards the modified stream channel. Therefore, in-stream weirs do not provide a
viable option for wetland restoration based on the groundwater model. To create wetlands,
greentree impoundments will be required to elevate the groundwater surface above the
floodplain elevation (immediately adjacent to the channel) periodically throughout the year.
4.4 REFERENCE GREENTREE IMPOUNDMENTS
Established greentree impoundments within the Piedmont of North Carolina were visited to
measure wetland attributes, review various structural designs, and to discern management
strategies employed. Reference systems include the Rocky Branch impoundment above Falls
Lake in Wake County, the Country Line Creek impoundments in Caswell County, the Beaver
Creek greentree impoundment above Jordan Lake in Wake County, and the Little Creek
impoundment above Jordan Lake in Durham County (Figures 9-11). These impoundments have
typically been located above water supply reservoirs in the region to replace wetland habitat
inundated by the reservoir, provide waterfowl habitat, and control sedimentation.
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IN Controllable weirs range from concrete dams and electronic sluice gates
on larger tributaries
to corrugated metal pipe using flash-board risers on smaller systems. The associated dams
' typically consist of an earthen causeway with rip-rapped emergency spillways and erosion
control areas. Dams likely to be overtopped within watersheds greater than 10 square miles
have often been reinforced with concrete materials placed on the earthen dam.
Figure 12 provides a conceptual depiction of a typical weir and dam for greentree
impoundments within watersheds ranging in size from 2 to 7 square miles. The weir consists
of two 4-foot wide slots with wooden flash-board risers used to control the water surface
elevation. For this application, the flash boards could be completely removed to provide for
existing channel flows during summer months, planting periods, or for other management
purposes. Subsequently, the boards may be installed during the winter and/or early part of the
growing season to establish wetland hydrology behind the impoundment. The type or size of
the weir used at the Bob Branch Site may be modified during the engineering design phase to
reduce flood potential, increase potential for stability, and/or other management concerns.
A profile of the Country Line Creek impoundment in Caswell County was measured to evaluate
wetland development relative to the dam height, typical winter weir height, summer weir
height, and valley slope. Figure 13 provides a depiction of the reference greentree
impoundment characteristics, including vegetation development patterns relative to water
surface elevations. Within the reference greentree impoundments, stream channels have been
obscured due to alluvial sediment deposition and vegetation development patterns. The stream
channel has been altered to the extent that wetland characteristics typically occupy the entire
impoundment land area, up to the water surface elevation established during winter months
(Figure 14).
4.5 REFERENCE PLANT COMMUNITIES
In order to establish a forested wetland system for mitigation purposes, a reference community
must be established. According to Mitigation Site Classification (MIST) guidelines (EPA 1990),
the area of proposed restoration should attempt to emulate a Reference Forest Ecosystem
(RFE) in terms of soils, hydrology, and vegetation. In this case, the target RFEs were
composed of steady-state woodlands in the region that have sustained loading of fluvial
sediments on floodplains in the past. Forest canopies have developed on these reference sites
which support soil, landform, and hydrological characteristics that restoration will attempt to
emulate.
All of the RFEs have been impacted by sediment deposition, selective cutting or high-grading,
channel migration/disturbances, and relatively high energy flood events. Therefore, the species
composition of these plots should be considered as a guide only. Reference forest data used
in restoration was modified to emulate steady-state community structure as described in the
Classification of the Natural Communities of North Carolina (Schafale and Weakley 1990).
h
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Two RFEs were selected within floodp lains along the Rocky River in Cabarrus County, North
Carolina. Floodplains associated with this river system have aggraded over the past century,
inducing braided channel configurations and accelerated sediment deposition within reference
feeder tributaries. Sixteen plots have been placed within relatively mature, bottomland
hardwood/swamp forests that have developed on accreted sediment.
The reference vegetation samples are designed to characterize the plant communities proposed
for restoration. Circular, 0.1-acre plot sampling was utilized to establish base-line vegetation
composition and structure in reference areas. Species were recorded along with individual tree
diameters, canopy class, and dominance. From collected field data, importance values (Brower
et al. 1990) of dominant canopy and mid-story trees were calculated (Table 4 and Table 5).
The composition of shrub/sapling and herb strata were recorded and identified to species.
At Site 1 (Table 4), the forest canopy is dominated by green ash, (Importance value [IV] 28
percent), sweetgum (L/qu/dambarstyraciflua) (IV 19 percent), American elm (Ulmusamericana)
(IV 11 percent), box elder (IV 8 percent) and red maple (IV 7 percent). Canopy species with
lesser importance include black willow, slippery elm (Ulmus alata), river birch, tulip poplar, and
water oak (Quercus nigra). Understory trees include flowering dogwood, ironwood, and
sugarberry (Celt/s laev/gata). A developed shrub layer is not generally present. Herbs include
Nepal microstegium, violets (Viola spp.), asters (Aster sp.), and river oats (Chasmanthium
la tifolium).
-0 At Site 2 (Table 5), the forest canopy is dominated by green ash, (IV 39 percent), box elder
(IV 22 percent), American elm (IV 12 percent), and swamp chestnut oak (IV 6 percent).
Portions of the canopy at RFE locations were also dominated by ironwood, overcup oak
(Quercus lyrata), sugarberry, sweet gum, red maple, black willow, slippery elm, water oak, and
river birch. The shrub/sapling layer is characterized by the non-native Chinese privet
(Ligustrum chinensis), paw-paw (Asimina triloba), and shade tolerant canopy species.
Herbaceous species include Japanese honeysuckle (Lonicera japonica), blackberry, muscadine,
common greenbriar, sedges (Carex spp.), and poison ivy.
Piedmont swamp forests are communities located in depressional areas, along toe slopes, and
at the confluence of alluvial valleys, where lateral flow is restricted. These sites are
hydrologically influenced by upland seeps and drainages, and by occasional riverine flooding.
Overstory species are dominated by flood-tolerant bottomland elements such as sweetgum,
American elm, willow oak (Quercus phellos), swamp chestnut oak, green ash,'overcup oak,
and swamp cottonwood (Populus heterophylla). Wetter sites may provide a broken to open
canopy providing enough light for development of a dense herbaceous/shrub layer. Species
found on these sites may include button-bush (Cephalanthus occidentalis), elderberry
(Sambucus canadensis), silky dogwood, false nettle (Boehmeria cylindrica), sedges (Carex
spp), rushes (Juncus spp.), and lizard's tail (Saururus cernuus). Giant cane (Arundinaria
gigantea) is prevalent in places.
38
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5.0 WETLAND RESTORATION PLAN
This restoration plan has been designed to establish wetlands within watersheds situated
immediately upstream of the Randleman Reservoir. A greentree impoundment is proposed to
establish contiguous wetland presence within 15.4 acres of the Bob Branch floodplain at
elevations ranging from 695 feet to 708 feet above mean sea level (Figure 15).
Wetland restoration or creation comprises approximately 13.0 acres of the total wetland
presence. This area is composed of actively inundated land surfaces, and passively formed,
saturated wetlands within 1.0 foot in elevation above the impounded water surface. Based
on reference studies, the one foot delineation of passively formed wetlands constitutes a
conservative estimate of the extent of wetland formation expected. (See ESC 2000a and ESC
2000b for a description of the passive formation of wetlands).
An additional 1.7 acres of the mitigation total is composed of open waters. The shorelines of
these areas are expected to accrete as sediment deposition within the impoundments
progresses. Submerged, emergent, and shrub/scrub aquatic vegetation is projected to colonize
these areas.
Finally, approximately 0.7 acres of the mitigation area is comprised of pre-existing wetlands.
These areas will be preserved or enhanced during impoundment construction. Enhancement
activities will include hydroperiod regulation and improvements in buffer vegetation.
The green tree impoundment comprises an embankment (floodplain levee) and weir
(controllable outlet structure). The elevation of the outlet is typically raised during the winter
months, while trees are dormant, to promote ponding, sediment deposition, and wetland
habitat. The elevation of the outlet is lowered in early spring to allow for vegetation growth,
nutrient uptake, and seedling establishment. For this project, the outlet may only be raised
during a brief portion (5 percent to 12.5 percent) of the growing season until wetland
communities and associated habitat are successfully restored. Subsequently, the period that
the outlet is raised may be incrementally increased during the winter months each year to
increase inundated wetland habitat for water fowl and other species adapted to use of
greentree impoundments during winter months. The long-term objective of wetland
restoration/creation by greentree impoundments is to maintain forested wetland communities
to the maximum extent feasible. Therefore, long-term management will be required.
A management plan has been prepared (Section 8.0) for long term maintenance of the
impoundment over the life of the Randleman Reservoir. Management techniques for greentree
impoundments surrounding the reservoir will be managed according to constructs outlined in
the Greentree Reservoir Management Handbook (Fredrickson and Batema 1996).
Components of this plan have been established based on reference wetland studies described
in Section 4.0. This effort will be performed by 1) installing a series of four controllable weirs
41
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and dams, 2) installing a step-pool grade control structure above the existing pond, 3) woody
debris deposition, and 4) planting of target wetland tree species in the area. Monitoring of
wetland development will be performed to track successional characteristics of the Site and
to verify wetland restoration success.
5.1 IMPOUNDMENT / WEIR CONSTRUCTION
A series of greentree impoundment structures consisting of four embankments will be
constructed within the Site, as depicted in Figure 15. The impoundment series begins
' approximately 700 feet upstream of the existing in-stream pond.
Construction of impoundment and weir structures may be subject to restrictions under the
North Carolina Dam Safety Law of 1967 (GS 143-215.23). Detailed construction plans will
be described in the design engineering phase of the project.
Embankment
The embankment series will be constructed with crest elevations ranging from 702 to 710 feet
' above mean sea level. The embankment elevations may be modified during the engineering
design phase to provide increased capacity for transporting floodplain flows across or around
the structure. As proposed, the embankment surfaces will reside up to 7 feet in elevation
' above the existing floodplain surface.
' Embankment
The embankment series will be constructed with crest elevations ranging from 702 to 710 feet
above mean sea level. The embankment elevations may be modified during the engineering
design phase to provide increased capacity for transporting floodplain flows across or around
the structure. As proposed, the embankment surfaces will reside up to 7 feet in elevation
above the existing floodplain surface.
Weir
The weirs (outlet structures) will be designed to allow for open channel flow
at base levels of
* the original stream channel elevation. The weir design will allow raising of the water surface
up to 3 feet during impoundment periods. Figure 12 provides a conceptual depiction of the
proposed impoundment structure including target elevations for the winter water surface and
f embankment height. The design or placement of these impoundments may be modified during
the engineering design phase based on potential stability, constructability, cost, or other
constraints.
5.2 STEP-POOL GRADE CONTROL STRUCTURE
I The outfall from the downstream weir will discharge over a relatively steep incline into the
existing channel immediately below the Site. The transition will extend from a maximum of
698 feet at the structure to 695 feet within the existing channel bed. This transition will be
extended over an adequate distance (60-80 feet) to reduce the water surface slope towards
stable conditions characteristic of a step-pool (A-type) stream channel underlain by a boulder
43
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substrate. The structure will attenuate flow velocities so that down-cutting into the channel
bed will be avoided immediately below the greentree impoundment. Figure 16 provides a
s conceptual depiction of a step-pool grade control channel.
The step-pool channel will be constructed over a distance of 60 to 80 feet within the Site
boundary. This distance will provide a bankfull water surface slope of approximately 0.05
rise/run (5 percent slope). In-fill and available boulder material will be arranged in the channel
to provide a step-pool geometry conducive to in-stream habitat, as depicted in Figure 16. The
series of steps and pools will promote capacity for continued fish migration above and below
the greentree impoundment structure.
5.3 WOODY DEBRIS DEPOSITION
Woody debris, including downed trees, tip mounds, snags, and decomposing material,
represents important habitat elements for wetland dependent wildlife. Therefore, woody
material generated from embankment construction or other Site activities will be distributed
across future wetland surfaces to the extent feasible. The material may be lifted or pushed
from adjacent windrows or forest areas as well.
5.4 WETLAND COMMUNITY RESTORATION
Restoration of wetland forested communities provides habitat for area wildlife and allows for
development and expansion of characteristic wetland-dependent species across the landscape.
Ecotonal changes between communities contribute to diversity and provide secondary benefits
such as enhanced feeding and nesting opportunities for mammals, birds, amphibians, and other
wildlife.
RFE data, on-site observations, and ecosystem classification has been used to develop the
species associations promoted during community restoration activities. Target plant
community associations include 1) bottomland hardwood / swamp forest and 2) scrub-shrub
/ swamp forest. Scrub-shrub elements will be targeted toward areas immediately behind the
impoundment within the construction limits and along the stream channel banks (Figure 17).
Planting Plan
The planting plan consists of 1) acquisition of available wetland species, 2) implementation of
proposed surface topography improvements, and 3) planting of selected species on the Site.
A total of 14.5 acres of the Site will be planted, corresponding to restored/created and
preserved/enhanced wetland areas, and excluding open water areas. Seedlings will be planted
in a random distribution, utilizing the species listed below.
Bottomland Hardwood / Swamp Forest
1. Cherrybark Oak (Quercus pagoda)
2. Overcup Oak (Quercus lyrata)
3. Willow Oak (Quercus phellos)
4. Swamp Chestnut Oak (Quercus mlchaux/i)
45

5. Swamp Cottonwood (Populus heterophylla)
6. Shagbark Hickory (Carya ovata)
7.
8. Bitternut Hickory (Carya cordiformis)
Green Ash (Fraxinus pennsylvanica)
9 American Elm (Ulmus americana)
10 Winged Elm (Ulmus alata)
11. Tulip Poplar (Liriodendron tulipifera)
Scrub-Shrub / Swamp Forest
1. Possum-haw (flex decidua)
2. Carolina holly (flex ambigua)
3 River Birch (Betula nigra)
4. American Sycamore (Platanus occidentalis)
5. Green Ash (Fraxinus pennsylvanica)
6. American Elm (Ulmus americana)
7. Swamp Cottonwood (Populus heterophylla)
8. Overcup Oak (Quercus lyrata)
9. Swamp Chestnut Oak (Quercus mlchauxii)
10. Silky Dogwood (Cornus amomum)
11. Button-bush (Cephalanthus occidentalis)
12. Elderberry (Sambucus canadensis)
Species selected for planting will be dependent upon availability of local seedling sources.
Advanced notification to nurseries (1 year) may facilitate availability of various non-commercial
species. In full planting areas (existing agricultural land), the soil surface will be scarified.
Disking or ripping may be employed to create a rough surface for the detention of runoff and
sediment, and to provide a more hospitable planting bed for tree seedlings. Then, bare-root
seedlings of selected species will be planted within specified areas at a density of 680 trees
per acre (8-foot centers). In existing forested areas, a supplemental planting will consist of
170 stems per acre (16-foot centers). Supplemental plantings will retain existing Site canopy
tree species, while introducing a greater component of wetland-dependent species. The total
number of stems and species distribution are depicted in Table 6.
Planting will be performed between December 1 and March 15 to allow plants to stabilize
during the dormant period and set root during the following spring season. Opportunistic
species, which typically dominate early- to mid-successional forests have been excluded from
initial plantings on interior floodplains. Opportunistic species such as sweetgum, red maple,
and loblolly pine may become established naturally. However, to the degree that long-term
species diversity is not jeopardized, these species should be considered important components
of steady-state forest communities. Planting of opportunistic species such as black willow will
be targeted as stabilization elements in erosion control areas immediately adjacent to the
creek.
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46
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4
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TABLE 6
Planting Plan

Vegetation
Association
(Planting area)
Shrub-Scrub/

Swamp Forest Bottomland
Hardwood/

Swamp Forest
(full planting) Bottomland
Hardwood/
Swamp Forest
(supplemental
planting)
TOTAL
STEMS
PLANTED
Stem Target (trees/ac) 680 680 170 -----
Area (acres) 1.0 10.0 3.5 14.5

SPECIES # planted
M total) # planted
total) # planted
M total) # planted
M total)
River Birch 70(10) 70
Silky Dogwood 7000) 70
Button-bush 7000) 70
Elderberry 70(10) 70
Black Willow 35 (5) 35
Possum-haw 35 (5) 35
Carolina Holly 35 (5) 35
American Sycamore 35 (5) 35
Swamp Cottonwood 70(10) 70000) 6000) 830
American Elm 35 (5) 350 (5) 30(5) 415
Green Ash 7000) 350 (5) 30(5) 450
Swamp Chestnut Oak 35 (5) 70000) 60 (10) 795
Overcup Oak 7000) 700 0 0) 60 (10) 830
Cherrybark Oak 700 (10) 60 (10) 760
Willow Oak 70000) 60(10) 760
Shagbark Hickory 700 (10) 60 (10) 760
Bitternut Hickory 700 (10) 60 (10) 760
Winged Elm 70000) 6000) 760
Tulip Poplar 700 (10) 60 (10) 760
TOTAL 700 7000 600 8300
47

10 The planting plan is the blueprint for community restoration (Figure 17). The anticipated
results stated in the regulatory success criteria (Section 6.0) may reflect vegetative conditions
achieved after steady-state forests are established over many years. However, the natural
progression through early successional stages of floodplain forest development will prevail
regardless of human interventions over a 5-year monitoring period. In total, approximately
8300 seedlings will be planted during wetland community restoration efforts.
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IN 6.0 MONITORING PLAN
The Monitoring Plan will entail analysis of the restoration area according to jurisdictional
wetland criteria (DOA 1987). Monitoring will include the observation and evaluation of three
primary parameters including hydrology, soil, and vegetation. Monitoring of restoration efforts
will be performed for 5 years or until success criteria are fulfilled.
6.1 HYDROLOGY
After hydrological modifications are performed, surficial groundwater monitoring gauges will
be designed and placed in accordance with specifications in USACE's Installing Monitoring
We//s/Piezometers in Wet/ands (WRP Technical Note HY-IA-3.1, August 1993). Monitoring
gauges will be set to a depth of up to 24 inches below the soil surface to track water surface
elevations in the impoundment relative to the weir height. All screened portions of the gauge
will be buried in a sand screen, filter fabric, and/or a bentonite cap to prevent siltation during
floods. Recording devices (if used) will be placed five feet above the ground elevation.
Placement of recording devices at this height should guard against over topping for a projected
50-year flood elevation. The gauge will be stabilized from flood shear by reinforcing steel bar
(re-bar).
Five groundwater monitoring gauges will be installed in restoration areas to provide
representative coverage throughout the Site. Approximate gauge locations are depicted in
Figure 18. Hydrological sampling will be performed during the growing season (March 26 to
November 6) at intervals necessary to satisfy the hydrologic success criteria. In general, the
gauges will be sampled weekly through the spring and early summer and intermittently through
the remainder of the growing season, if needed to verify success.
W 6.2 HYDROLOGY SUCCESS CRITERIA
Target hydrological characteristics have been evaluated using regulatory wetland hydrology
criteria. The regulatory wetland hydrology criterion requires saturation (free water) within one
foot of the soil surface for 5 percent of the growing season under normal climatic conditions.
® Success Criteria
Under normal climatic conditions, hydrology success criteria comprises saturation (free water)
within 1 foot of the soil surface for a minimum of 5 percent of the growing season. This
hydroperiod translates to saturation for a minimum, 1 1-day (5 percent) consecutive period
during the growing season, which extends from March 26 through November 6 (USDA 1977).
If wetland parameters are marginal as indicated by vegetation and hydrology monitoring, a
jurisdictional determination will be performed in the questionable areas.
6.3 SOIL
Mitigation activities are expected to increase the deposition and transport of stream sediments
during overbank flood events. As a result, soils (Fluvaquents) are continuously reworked by
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fluvial processes. Because iron reduction rates (gleying) are not spatially or temporally uniform
on recent alluvial deposits, soil color or other visual, hydric soil properties are not considered
suitable for quantitative wetland soil monitoring/success criteria on active floodplains.
Soil monitoring will entail measurement of sediment accretion/reduction (aggradation/
degradation) at the location of each monitoring gauge and other hydraulically active areas as
identified by Site managers. Mitigation activities are designed to provide for flood and
sediment storage from the watershed. Therefore, hydraulic and energy dissipation patterns
should be distributed throughout as much of the Site as possible. However, an area of
particularly accelerated sediment deposition may raise land surfaces above the elevation of the
primary wetland floodplain over a relatively short period of time. Conversely, deep scour holes
or head-cuts may form in locations where flow velocity or sediment deficits exceed a "normal
distribution." Soil monitoring is designed to provide a cursory review to predict the need for
additional site modifications if accelerated deposition or scour potentially jeopardizes wetland
restoration efforts.
The re-bar used to support monitoring gauges will be marked upon installation and in each
monitoring year at the elevation of the existing ground surface. In addition, the height of silt
lines will be recorded to predict the depth of inundation during the flood period. Additional re-
bar will be placed and measured in high energy areas identified by Site managers, as needed.
The change in elevation of the alluvial surface and deposition/scour patterns relative to flood
elevations will be recorded and compared to previous years.
6.4 SOIL SUCCESS CRITERIA
Success criteria require that the deposition/scour rate not exceed over 1 foot change in surface
elevations in any given year. Any areas affected by this excessive deposition/scour will be
mapped in the field. The area will be reviewed to determine modifications to drainage patterns
that should be implemented, if any. Changes in surface elevations of less than 1 foot per year
will meet regulatory success criteria; however, modifications to deposition / scour patterns
may also be considered in certain circumstances.
6.5 VEGETATION
Restoration monitoring procedures for vegetation are designed in accordance with EPA
guidelines presented in MiST documentation (EPA 1990) and Compensatory Hardwood
Mitigation Guidelines (DOA 1993). The following presents a general discussion of the
monitoring program.
Vegetation will receive cursory visual evaluation during periodic reading of monitoring wells
to ascertain the general conditions and degree of competition or overtopping of planted
elements. Subsequently, quantitative sampling of vegetation will be performed once annually
during the fall (September/November) for 5 years or until vegetation success criteria are
achieved. Sampling dates may be modified to accommodate flood events and plot inundation,
as needed.
52
RD
During the first sample event, a visual survey will be performed in the reference wetlands to
identify all canopy tree species represented within target communities. These reference tree
species will be utilized to define "character tree species" as termed in the success criteria.
Permanent (on each gauge head) or nonpermanent, randomly placed plots will be established
at representative locations in the restoration areas. Each plot will consist of two 300-foot
transects extending at a randomly selected compass bearing from a central origin. The plot
width along the transect will extend 4 feet on each side of the tape, providing a 0.1 1-acre plot
sample at the location (600 feet x 8 feet / 43,560 square feet/acre). Eight plots will be
established to provide an 8 percent sample and a depiction of tree species available for current
and future seed sources within the restoration area. In each plot, tree species and number of
stems will be recorded and seedling/sapling/tree height measured. Tree data from all plots will
be combined into one database to calculate an average density, by species, represented in
restoration areas of the Site.
In each plot, presence/absence of shrub and herbaceous species will be recorded. A wetland
data form (DOA 1987) will be completed to document the classification and description of
vegetation, soil, and hydrology.
90 6.6 VEGETATION SUCCESS CRITERIA
Success criteria include the verification, per the wetland data form, that each plot supports a
species composition sufficient for a jurisdictional determination. Additional success criteria
are dependent upon density and growth of "Character Tree Species." "Character Tree
Species" are identified through visual inventory of reference wetland communities used to
orient the restoration project design. All canopy tree species identified in the reference
wetland will be utilized to define "Character Tree Species" as termed in the success criteria
(Character Tree Species are generally listed in Section 4.5 and Section 5.6).
An average density of 320 stems per acre of Character Tree Species must be surviving in the
first three monitoring years. Subsequently, 290 stems per acre of character tree species must
be surviving in year 4, and 260 stems per acre of Character Tree Species in year 5. Each
individual species is limited to representing up to 20 percent of the 320 stem per acre total.
Additional stems of a particular species above the 20 percent threshold are discarded from the
statistical analysis. In essence, a minimum of five different character tree species must be
present with each species representing up to 20 percent of the 320 stem per acre total.
If vegetation success criteria are not achieved based on average density calculations from
combined plots over the entire restoration area, those individual plots that do not support the
stem per acre requirement and the representative area will be identified. Supplemental planting
will be performed in the identified area as needed until vegetation success criteria are
achieved.
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No quantitative sampling requirements are proposed for herb assemblages. Development of
a forest canopy over several decades and restoration of wetland hydrology will dictate success
W-9 in migration and establishment of desired wetland understory and groundcover populations.
6.7 REPORT SUBMITTAL
An Annual Wetland Monitoring Report (AWMR) will be prepared at the end of each monitoring
year (growing season). The AWMR will depict the sample plot and quadrant locations and
include photographs which illustrate site conditions. Data compilations and analyses will be
presented as described in Sections 6.1 through 6.6 including graphic and tabular format, where
practicable. Raw data in paper or computer (EXCEL) file format will be prepared and submitted
as an appendix or attachment to the AWMR.
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IN 7.0 IMPLEMENTATION SCHEDULE
Project implementation will include performance of restoration work in four primary stages
no including 1) impoundment / weir construction, 2) tree and shrub planting, 3) monitoring plan
implementation, and 4) management program implementation. This mitigation plan or
implementation schedule may be modified based upon civil design specifications, permit
conditions, or contractor limitations.
Stage 1: Impoundment / Weir Construction
Stage 1 will be performed concurrent with or subsequent to filling of the reservoir. The
greentree impoundment will be installed at the designated location. This work will be
performed during late spring and/or early summer months to reduce erosion hazards associated
with saturated soil or large August storms. Site preparation, including debris removal, woody
debris deposition, and scarification (if needed) will be performed during the same summer
period, prior to tree planting.
Stage 2: Tree Planting
Tree and shrub planting will be performed the first winter after Stage 1 is complete. The
seedlings will be planted during the winter dormant period, prior to March 1.
Stage 3: Monitoring Plan Implementation
Groundwater monitoring gauges and permanent vegetation plots will be established
immediately after construction and planting activities are completed (prior to March 26, the
start of the growing season). The Site will be visited regularly to read monitoring gauges and
to evaluate wetland development during the first growing season. Vegetation sampling and
hydrology monitoring will be completed by November 6 (the end of the growing season). The
first year of monitoring would be completed upon submittal of the Annual Wetland Monitoring
Report and fulfillment of success criteria. The monitoring sequence will be repeated as
described for four additional years or until success criteria are achieved.
Stage 4 Management Program Implementation
Green tree impoundments require active management throughout the life of the wetland facility
and water supply reservoir. Therefore, long-term management programs will be required to
ensure that wetland development is established and maintained. The management program
will be implemented concurrent with the monitoring plan as described above. Constructs of
the management program are described in the next Section.

55
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8.0 MANAGEMENT PROGRAM
Greentree impoundments require modification of water surface elevations on a regular basis.
Typically, the elevation of outlets is raised and lowered at variable times each year to provide
for development of target wetland vegetation. Wetland vegetation is typically harvested
and/or planted periodically to establish target vegetation patterns for waterfowl or other
wetland dependent wildlife. Invasive species such as Kudzu (Pueraria iobata) may require
systematic removal as well. For this project, outlet controls and vegetation maintenance must
also be manipulated to promote forested wetland development within the 14.5-acre Site.
Target hydrological goals include soil saturation or inundation for a minimum of 5 percent of
the growing season (March 26 to November 6). The 5 percent criterion must be achieved in
50 percent of the years over the life of the Randleman Reservoir.
The Piedmont Triad Regional Water Authority (PTRWA) will provide the fiscal and
administrative resources necessary to maintain and manage the greentree impoundments over
the life of the water supply reservoir. PTRWA will make provisions for establishment of an
Environmental Compliance Officer (Officer) to serve as the primary administrator and authority
over the greentree impoundments. The Officer will be under control of PTRWA while PTRWA
continues to manage the property. If the property is deeded to a resource agency as described
in Section 9.0, the resource agency will provide resources necessary for establishment and
maintenance of the Officer.
10 The Officer will be tasked to supervise, coordinate, monitor, and manipulate the greentree
impoundments throughout the life of the water supply reservoir. The Officer will coordinate
and implement, in consultation with qualified wildlife biologists, the following greentree
impoundment management components as described in the Greentree Reservoir Management
go Handbook (Fredrickson, L.H. and D.L. Batema 1996, Mitchell and Newlin9 1986).
1) The Officer will be responsible for raising and lowering the controllable weirs at
a frequency and duration needed to establish wetland hydrology and maximize
development of wetland vegetation. Target vegetation patterns include
establishment of tree species to the maximum extent feasible.
2) The Officer will periodically visit the Site to visually assess waste debris
dumping, erosion problems, debris jams on structures, vegetation patterns, and
other aspects of wetland development. The Officer will repair identified
problems to ensure continued functioning of the wetland.
3) The Officer will provide for periodic quantitative sampling of vegetation to
90 ensure that target vegetation species are developing and being replaced within
the impoundments. The results of vegetation samples will be used by the
B M Officer to adjust the frequency and/or duration that the controllable weirs are
raised or lowered and to order and plant vegetation elements as needed.
10 56
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4) The Officer will submit an annual report to the responsible resource agency
summarizing the dates of weir modification, the current vegetation sample,
trends in vegetation patterns, and recommendations for weir modifications over
the next monitoring weir. The report will also include recommendations for
structural modifications or additional plantings, as needed. These reports will
be prepared and submitted on annual basis over the life of the Randleman
Reservoir Water Supply.
57
0
9.0 DISPENSATION OF PROPERTY
PTRWA will maintain ownership of the property until all mitigation activities are completed and
the site is determined to be successful. Although no plan for dispensation of the Site has been
developed, PTRWA may continue to manage the property or may deed the property to a
resource agency (public or private) capable of managing the greentree impoundments over the
life of the reservoir. The resource agency will be approved by the appropriate regulatory
agencies. Covenants and/or restrictions on the deed will be included along with adequate
n fiscal resources to ensure adequate management and protection of the Site throughout the life
-1 of the reservoir.
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10.0 WETLAND FUNCTIONAL EVALUATIONS
Mitigation activities at the Bob Branch Mitigation Site should be determined based on wetland
functions generated and a comparison of restored functions to potentially impacted wetland
resources. Therefore, an evaluation of mitigation wetlands by physiographic area is provided
to evaluate site utility for mitigation in the region.
10.1 EXISTING CONDITIONS
Under existing conditions, hydrodynamic functions have been degraded or effectively
eliminated due to stream entrenchment, bed/bank erosion and removal of characteristic
vegetation. Features which depict performance of hydrodynamic wetland functions such as
surface microtopography, seasonal ponding, meandering stream channels, and characteristic
wetland vegetation have been effectively eliminated on the abandoned floodplains. Reduction
or elimination of wetland hydrology has also negated nutrient cycling and biological functions
within the complex. These former wetlands do not support natural communities adapted to
wetlands or the wetland dependent wildlife characteristic in the region.
10.2 PROJECTED, POST-RESTORATION CONDITIONS
The Site will be used to establish wetland communities capable of providing wildlife habitat
and water quality benefits. The greentree impoundment is projected to provide for restoration
of regular overbank flood events and filling of the entrenched channel with sediment over time.
As a result, the floodplain areas are expected to support an array of emergent, shrub-scrub,
and forested wetland communities, providing replacement of habitat for wetland dependent
species displaced by the reservoir. Water quality benefits are projected to include sediment
retention and pollutant processing of waters generated by the 2.02-square mile watershed.
Pro-active mitigation within the greentree impoundments is projected to provide approximately
14.7 acres of wetland restoration / creation and open waters with accreting shorelines. An
additional 0.7 acres of preserved or enhanced wetlands will be included in the Site (15.4 acres
total) (Figure 18).
59
90
1
In 1.0 REFERENCES
Baumer, 0. and J. Rice. 1988. Methods to predict soil input data for DRAINMOD ASAE Paper
No. 88-2564. ASAE, St. Joseph, MI 49085.
Belcher, H.W. and G.E. Merva. 1987. Results of DRAINMOD verification study for Zeigenfuss
soil and Michigan climate. ASAE Paper No. 87-2554. ASAE, St. Joseph, MI 49085.
Brinson M.M., F.R. Hauer, L.C. Lee, W.L. Nutter, R.D. Smith, D. Whigham. 1995. Guidebook
for Application of Hydrogeomorphic Assessments to Riverine Wetlands. U.S. Army Corps of
Engineers Waterways Experiment Station. Vicksburg, MS.
Brinson, M.M. 1993a. Changes in the functioning of wetlands along environmental gradients.
Wetlands 13(2): 65-74, Special Issue, June 1993. The Society of Wetland Scientists.
Brinson M.M. 1993b. A Hydrogeomorphic Classification for Wetlands. Wetlands Research
Program Technical Report WRP-DE-4. U.S. Army Corps of Engineers Waterways Experiment
Station. Vicksburg, MS.
Brower, J.E., J.H. Zar, and C.N. von Ende. 1990. Field and Laboratory Methods for General
Ecology. William C. Brown Publishers, Debuque, IA.
Chang, Howard H. 1988. Fluvial Processes in River Engineering. John Wiley & Sons.
Department of the Army (DOA). 1993. Corps of Engineers Wilmington District.
Compensatory Hardwood Mitigation Guidelines (12/8/93).
Department of the Army (DOA). 1987. Corps of Engineers Wetlands Delineation Manual.
Tech. Rpt. Y-87-1. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.
Division of Water Quality (DWQ). 1998. Classifications and Water Quality Standards
Assigned to the Waters of the Cape Fear River Basin, N.C. Department of Environment and
Natural Resources, Raleigh, N.C.
Division of Water Quality (DWQ). 2000 (draft). Cape Fear River Basinwide Water Quality
Plan. North Carolina Department of Environment and Natural Resources. Raleigh, N.C.
Dunne D. and L.B. Leopold. 1978. Water in Environmental Planning. W.H. Freeman and
Company, N.Y.
EcoScience Corporation (ESC). 1998a (unpublished). Preliminary Groundwater Drainage
Model: Randleman Reservoir Mitigation Sites, Guilford County, North Carolina. Raleigh, N.C.
on
60
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00
ao
90
B?
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ao
00
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ao
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00
00
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EcoScience Corporation (ESC). 1998b (unpublished). Preliminary Wetland Mitigation
Assessment: Randleman Reservoir, Guilford and Randolph Counties, North Carolina. Raleigh,
N.C.
EcoScience Corporation (ESC). 1999 (unpublished). Wetland Mitigation Plan: Randleman
Reservoir, Guilford and Randolph Counties, North Carolina. Raleigh, N.C.
EcoScience Corporation (ESC). 2000a (unpublished). Detailed Wetland Mitigation Plan:
Randleman Reservoir Water Supply, Richland Creek Mitigation Site, Guilford Countiey, North
Carolina. Raleigh, N.C.
EcoScience Corporation (ESC). 2000b (unpublished). Detailed Wetland Mitigation Plan:
Randleman Reservoir Water Supply, Reddicks Creek Mitigation Site, Guilford Countiey, North
Carolina. Raleigh, N.C.
Environmental Protection Agency (EPA). 1990. Mitigation Site Classification (MiST) A
Methodology to Classify Pre-Project Mitigation Sites and Develop Performance Standards for
Construction and Restoration of Forested Wetlands. USEPA Workshop, August 13-15, 1989.
USEPA Region IV and Hardwood Research Cooperative, North Carolina State University,
Raleigh, N.C.
Fouss, J.L., R.L. Bengtson, and C.E. Carter. 1987. Simulating subsurface drainage in the
lower Mississippi Valley with DRAINMOD. Transactions of the ASAE 30 (6).(1679 -1688).
Fredrickson, L.H. and D.L. Batema. 1996. Greentree Reservoir Management Handbook.
Gaylord Memorial Laboratory Wetland Management Series. The School of Natural Resources.
University of Missouri-Columbia. Puxico, MO 63960.
Gayle, G., R.W. Skaggs, and C.E. Carter. 1985. Evaluation of a water management model
for a Louisiana sugar cane field. J. of Am. Soc. of Sugar Cane Technologists, 4: 18 - 28.
Graham County Historical Society, 1992. Graham County Heritage. Robbinsville, NC.
Harman, W.A., G.D. Jennings, J.M. Patterson, D.R. Clinton, L.A. O'Hara, A. Jessup, and R.
Everhart. 1999. Bankfull Hydraulic Geometry Relationships for North Carolina Streams. N.C.
State University, Raleigh, North Carolina.
Hvorslev, M.J. 1951. Time lag and soil permeability in groundwater observations. U.S. Army
Corps of Engineers Waterways Experimental Station Bulletin 36, Vicksburg, MS.
Mitchell, W.A., and C.J. Newling. 1986. Greentree Reservoir Management Manual. U.S.
Army Corps of Engineers Waterways Experiment Station.
61

Nunnally, N.R., and E. Keller. 1979. Use of Fluvial Processes to Minimize Adverse Effects of
Stream Channelization. Water Resources Research Institute of the University of North
p, Carolina. Report No. 144.
Rogers, J.S. 1985. Water management model evaluation for shallow sandy soils.
Transactions of the ASAE 28 (3): 785-790.
Rosgen, D. 1996. Applied River Morphology. Wildland Hydrology (Publisher). Pagosa
Springs, Colorado.
Schafale, M. P., and A.S. Weakley. 1990. Classification of the Natural Communities of North
Carolina: Third Approximation, NC Natural Heritage Program, Division of Parks and Recreation,
NC DEM, Raleigh NC.
Simmons, C.E. 1976. Sediment Characteristics of Streams in the Eastern Piedmont and
Western Coastal Plain Regions of North Carolina. U.S. Geological Survey Water Supply Paper,
W 1798-0,p. 01-032. Reston VA.
Skaggs, R.W. 1982. Field Evaluation of a Water Management Simulation Model. Transactions
of the ASAE 25 (3):666-674.
Skaggs, R.W., N.R. Fausey, and B.H. Nolte. 1981. Water Management Evaluation for North
Central Ohio. Transactions of the ASAE 24 (4):922-928.
Skaggs, R.W., et a/. 1993. Methods for Evaluating Wetland Hydrology. ASAE Meeting
Presentation Paper No. 921590. 21 pp.
Smith, R.D., A. Ammann, C. Bartoldus, and M.M. Brinson. 1995 (unpublished). An Approach
for Assessing Wetland Functions Using Hydrogeomorphic Classification, Reference Wetlands,
and Functional Indices. Wetlands Research Program Technical Report WRP DE-_. US Army
Engineer Waterways Experiment Station, Vicksburg, MS.
Strahler, A.N. 1964. Geology. Part II. Quantitative geomorphology of drainage basins and
channel networks. (in) Handbook of Applied Hydrology. (ed. V.T. Chow), pp. 4-39 to 4-76,
McGraw Hill, New York.
Susanto, R.H., J. Feyen, W. Dierickx, and G. Wyseure. 1987. The Use of Simulation Models
to Evaluate the Performance of Subsurface Drainage Systems. Proc. of the Third International
Drainage Workshop, Ohio State University, OH. pp. A67 - A76.
U.S. Department of Agriculture (USDA). 1977. Soil Survey of Guilford County, North
Carolina. Natural Resources Conservation Service.
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U.S. Department of Agriculture (USDA). 1987. Hydric Soils of the United States. In
Cooperation with the National Technical Committee for Hydric Soils. Natural Resources
Conservation Service.
U.S. Department of Agriculture (USDA). Unpublished. Soil Survey of Randolph County, North
Carolina. Natural Resources Conservation Service.
U.S. Geological Survey (USGS). 1974. Hydrologic Cataloging Unit Map for the State of North
Carolina.
Yoakum, J., W.P. Dasmann, H.R. Sanderson, C.M. Nixon, and H.S. Crawford. 1980. Habitat
Improvement Techniques. Pp. 329-403 in S.D. Schemnitz (Editor). Wildlife Management
Techniques Manual, 4th ed., rev. The Wildlife Society, Washington, D.C. 686 pp.
63
DETAILED WETLAND MITIGATION PLAN
i
RANDLEMAN RESERVOIR WATER SUPPLY
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p/
HICKORY CREEK MITIGATION SITE
GUILFORD COUNTY, NORTH CAROLINA

Prepared for:
PIEDMONT TRIAD REGIONAL WATER AUTHORITY
Prepared by:
EcoScience
EcoScience Corporation
612 Wade Avenue, Suite 200
Raleigh, North Carolina 27605

November 2000
0
a
TABLE OF CONTENTS
Paqe
LIST OF FIGURES ................................................ iii
LIST OF TABLES ................................................ iv
j
? 1.0 INTRODUCTION ............................................ 1
f 1.1 Purpose ............................................. 1
1.2 Objectives of Wetland Restoration .....
.. 1
1.3 ..
.................
Primary Methods for Wetland Restoration 3
1.4 Mitigation Site Selection ................................. 4
2.0 METHODS ................................................ 8
3.0 EXISTING CONDITIONS ...................................... 11
3.1 Physiography, Topography, and Land Use ..................... 11
3.2 Soils ...............................................13
3.3 Plant Communities ..................................... 15
3.4 Hydrology ...........................................17
3.5 Water Quality ......................................... 21
3.6 Jurisdictional Wetlands .................................. 21
a
4.0 WETLAND RESTORATION STUDIES .............................. 24
4.1 Restoration Alternatives Analyses ........................... 24
4.2 Reservoir Pool Level and Sedimentation Analysis ................ 26
4.3 Surface Water Analyses ................................. 33
4.4 Groundwater Modeling .................................. 36
4.5 Reference Greentree Impoundments ......................... 39
4.6 Reference Plant Communities .............................. 40
4.7 Reference Physiography and Surface Topography ................ 47
5.0 WETLAND RESTORATION PLAN ................................ 49
5.1 Passive Saturation / Inundation from the Reservoir Pool ........... 49
5.2 Sediment Control Check Dams ............................. 50
5.3 Impoundment / Weir Construction .......................... 50
5.4 Surface Scarification / Waste Debris Removal .................. 52
5.5 Woody Debris Deposition ................................ 52
5.6 Wetland Community Restoration ........................... 52
7
6.0 MONITORING PLAN ......................................... 57
6.1 Hydrology ...........................................57
6.2 Hydrology Success Criteria ............................... 57
6.3 Soil ................................................59
6.4 Soil Success Criteria .................................... 59
6.5 Vegetation ........................................... 59
6.6 Vegetation Success Criteria ............................... 60
6.7 Report Submittal ...................................... 61
7.0 IMPLEMENTATION SCHEDULE ................................. 62
8.0 MANAGEMENTPROGRAM ....................................63
9.0 DISPENSATION OF PROPERTY ................................. 65
10.0 WETLAND FUNCTIONAL EVALUATION ........................... 66
10.1 Existing Conditions ..................................... 66
10.2 Projected Post-Restoration Conditions ........................ 66
11.0 REFERENCES ..............................................67
LIST OF FIGURES
Paqe
Figure 1 : Site Location: Randleman Reservoir ......................... 2
Figure 2: Site Location: Hickory Creek Mitigation Site .................... 7
Figure 3: Aerial Photograph (1999) ................................. 9
Figure 4: Physiography, Topography, and Land Use ..................... 12
Figure 5 Soil Map Units ........................................ 14
Figure 6: Plant Communities ..................................... 16
Figure 7: Flood Frequency Analyses ................................ 20
Figure 8: Jurisdictional Wetlands .................................. 22
Figure 9: Pool Level and Sedimentation: Reference Site 1 ................. 29
Figure 10 Pool Level and Sedimentation: Reference Site 2 ................. 30
Figure 11 Lake Pool and Sedimentation: On-Site Lake Pool ................. 32
Figure 12: Conceptual Impoundment Design ........................... 41
Figure 13: Reference Lake Shoreline ................................. 42
Figure 14: Reference Greentree Impoundment .......................... 43
Figure 15: Reference Site: Plan View and Cross-Sections .................. 48
Figure 16: Hydrology Restoration ................................... 51
Figure 17: Planting Plan ......................................... 53
Figure 18: Monitoring Plan / Mitigation Design Units ..................... 58
LIST OF TABLES
Paqe
Table 1: Estimated Acreage of Mitigation Design Units Based on Preliminary Studies
for 10 Potential Mitigation Sites Associated with the Randleman Reservoir
.................................................. 5
Table 2: Water Surface Elevation Estimates for Various Flood Frequencies ..... 34
Table 3: Modeled Groundwater Discharge Zone of Influence
on Wetland Hydroperiods: Congaree Soils ..................... 38
Table 4: Reference Forest Ecosystem Plot Summary .................... 45
Table 5: Reference Forest Ecosystem Plot Summary .................... 46
Table 6: Planting Plan ......................................... 55
iv

DETAILED WETLAND MITIGATION PLAN
RANDLEMAN RESERVOIR WATER SUPPLY
HICKORY CREEK MITIGATION SITE
GUILFORD COUNTY, NORTH CAROLINA
1.0 INTRODUCTION
1.1 PURPOSE
The Piedmont Triad Regional Water Authority (PTRWA) proposes development of the
Randleman Reservoir in Randolph and Guilford Counties, North Carolina (Figure 1). The
purpose of this project is to develop a safe and dependable water supply source for North
Carolina's Piedmont Triad region that will satisfy the projected water demand for a period
of 50 years. The proposed 3,000-acre reservoir will unavoidably impact approximately 121
acres of wetlands through impoundment and establishment of an open water system.
These jurisdictional wetlands are subject to regulation under Section 404 of the Clean
Water Act (CWA) (33 U.S.C. § 1344).
For unavoidable wetland impacts, compensatory mitigation is required to facilitate no net
loss of wetland functions in the region. Compensatory mitigation is typically performed
to replace similar wetland types and wetland functions as those impacted (ex: forested,
stream-side wetlands). Wetland restoration, creation, enhancement, or preservation
represent typical methods designed to offset wetland impacts. The North Carolina
Division of Water Quality (DWQ) has instituted a policy that prefers a minimum of 1 acre
of wetland be restored or created for every acre of wetland impacted. Subsequently,
remaining wetland functional replacement needs may then be off-set through wetland
enhancement and/or preservation.
1.2 OBJECTIVES OF WETLAND RESTORATION
The primary objectives for wetland restoration include:
1) Restore or create 121 acres of wetlands as required under regulatory
guidance.
2) Assist in protecting the drinking water supply from pollutants discharged
from the developing watersheds. Excess nutrients, fecal coliform,
a sediments, and chemical contaminants (metals, etc.) represent the primary
water quality concerns for the reservoir.
3) Maximize benefits to water quality through establishment of functioning
wetlands above the reservoir pool.
4) Replace habitat for wetland dependent wildlife displaced by establishment
of open water.
5) Maximize the acreage of wetland restoration or creation achieved at the
Hickory Creek mitigation site.
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Water quality benefits are maximized by reducing the capacity for sediment to reach open
water within the reservoir pool. Entrenched streams in the region have abandoned
adjacent floodplains and tend to discharge large quantities of sediment within water
supply reservoirs (Section 4.2). Therefore, wetland restoration for water quality should
be designed to reduce sediment transport capacity of streams immediately above the
reservoir and to entrap sediment within vegetated wetland surfaces. As a result, sediment
would be deposited on floodplain surfaces that periodically dry out in areas outside of the
reservoir pool. Wetland vegetation would serve to provide nutrient uptake and recycling
functions within deposited sediment. Using this rationale, entrenched stream and terrace
systems would be converted into alluvial wetland fans or greentree impoundments. A
highly sinuous (E) to braided (D) stream system would be developed within the alluvial
deposition area (Rosgen 1996). Wetland vegetation would be established on the alluvial
deposition to stabilize the sediment and provide for pollutant recycling through oxidation
(drying) and reduction (wetting) processes. Within reservoir pools immediately
downstream of entrenched streams, sediment from the watershed is deposited directly
into the water supply, in a permanently inundated, reducing environment. Without
periodic oxidation processes, pollutants generally dissolve within the water column and
consequently reduce drinking water quality.
Establishment of the reservoir will effectively stop sediment transport capacity within each
tributary that flows into the lake. The primary objective of mitigation is to extend the
sediment deposition wedge in the upstream direction of each valley, prior to confluence
with the lake. The reservoir will passively develop wetlands within a certain area in each
valley, immediately above the reservoir pool. This project is intended to assist that
process through active measures, including extension of wetlands in the up-valley
direction and establishment of wetland vegetation on active alluvial surfaces.
1.3 PRIMARY METHODS FOR WETLAND RESTORATION
Two primary methods for wetland restoration have been proposed to extend the sediment
wedge into design wetlands above the reservoir pool, restore 121 acres of riverine
wetlands, and to provide suitable habitat for wetland dependent wildlife. Primary
methods include: 1) in-stream structures designed to reduce sediment transport capacity;
and 2) greentree impoundments designed to allow management of water levels and
sediment deposition patterns.
In-Stream Structures
In-stream structures are proposed primarily along dredged or entrenched stream corridors
on relatively low-slope valley floors (<0.009 rise/run) supporting forest vegetation.
Adjacent floodplains have been abandoned by the incised stream and converted to
elevated terraces not regularly exposed to overbank flooding or wetland hydrodynamics.
Properly designed in-stream structures are expected to reduce the degree of channel
C
incision, reduce the rate of groundwater discharge from the floodplain into the channel
,
3
0

increase overbank flooding from the channel onto the floodplain, reduce sediment
transport capacity, and provide greater sediment deposition within vegetated wetlands.
Greentree Impoundments
Greentree impoundments are proposed on more steeply sloped floodplains and stream
terraces (>0.008 rise/run) or pastured sites where relatively severe stream channel
degradation and steepening has occurred above the reservoir pool. In general, a greentree
impoundment comprises a floodplain levee and controllable outlet structure that is
modified periodically to promote the development of forested wetlands. Functioning
greentree impoundments above the lake reservoir are expected to provide for significant
nutrient uptake, recycling, and management benefits.
The elevation of the outlet is typically raised during winter months to promote ponding,
sediment deposition, and waterfowl habitat. Subsequently, the elevation of the outlet
is lowered in early spring to allow for vegetation growth, nutrient uptake, and seedling
establishment. Levee systems are typically constructed to provide for less than 2 to 3 feet
of inundation during winter months, to prevent over-topping, and to allow for survival of
tree seedlings. The winter depth is generally dependent upon the height of seedlings.
The raising and lowering of outlet structures requires regular monitoring and maintenance
by qualified personnel to facilitate the growth and survival of tree species. The time for
outlet adjustment may vary annually and is dependent upon localized conditions within
the watershed. Seedling mortality is typically tracked on an annual basis, and the date
of spring lowering of water levels is modified periodically to maximize the rate of forest
regeneration. Tree or shrub species selected for planting will vary based on expected
hydrologic regimes and other site-specific conditions. In general, sites lacking substantial
forest vegetation and primarily used as pasture land were targeted for this mitigation
option.
1.4 MITIGATION SITE SELECTION
During the environmental impact assessment, project planners identified and evaluated a
total of 25 potential mitigation sites within stream corridors extending above the reservoir
pool. A description of mitigation potential for each of these sites was prepared in
previous documents (ESC 1998a, ESC 1998b, ESC 1999).
Of these 25 sites, 10 sites were determined to support wetland restoration potential on
floodplains encompassing up to 121 acres of restorable land area. Table 1 and Figure 1
depict the location of each site and projected acreages potentially available for wetland
restoration use.
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This document details restoration and enhancement procedures for riverine and lake
shoreline wetland restoration and creation along Hickory Creek, one of the 10 mitigation
sites (Figure 2). The Hickory Creek mitigation site (Site) includes 29.4 acres that
encompass the stream and adjacent floodplain servicing a watershed of approximately 8.7
square miles immediately above the reservoir. In-stream structures are proposed within
extensively dredged stream channels at or immediately below the reservoir pool elevation
to reduce sediment transport capacity into the water supply. A greentree impoundment
is also proposed immediately above the reservoir pool to extend the sediment deposition
wedge and wetland extent in the up-valley direction. Modifications along the dredged
and entrenched Hickory Creek corridor are designed to reduce the rate of groundwater
discharge from the floodplain into the channel, increase overbank flooding from the
channel onto the floodplain, and increase deposition of sediment on vegetated wetland
surfaces above the reservoir pool.
13 This summary document includes the following: 1) descriptions of existing conditions; 2)
surface and groundwater hydraulic analyses; 3) reference lake shoreline and greentree
impoundment studies; and 4) reference soil and forest ecosystem investigations.
Subsequently, detailed plans are provided for in-stream structures, wetland
restoration/creation, vegetation planting, site monitoring, and success criteria. Remaining
mitigation sites that follow the format of this mitigation plan will be attached as appendix
documents to this summary mitigation plan.
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RANDLEMAN RESERVOIR MITIGATION PROJECT
HICKORY CREEK SITE C)wn try-
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Guilford Count
North Carolina Nov 2000 2
Ralegh,North Carolina y,
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2.0 METHODS
Natural resource information for the Site was obtained from available sources, including
U. S. Geological Survey (USGS) topographic mapping (USGS High Point East and High
Point West 7.5 minute quadrangles), U. S. Fish and Wildlife Service (USFWS) National
Wetlands Inventory (NWI) mapping, and Natural Resource Conservation Service INKS)
soil survey (USDA 1977). These resources were utilized for base mapping and evaluation
of existing landscape and soil information prior to on-site inspection. Current (1999) aerial
photography was obtained and utilized to map relevant environmental features (Figure 3).
Characteristic and target natural community patterns were classified according to
constructs outlined in Schafale and Weakley's, Classification of the Natural Communities
of North Carolina (1990). North Carolina Natural Heritage Program (NCNHP) data bases
were evaluated for the presence of protected species and designated natural areas which
may serve as reference (relatively undisturbed) wetlands for restoration design.
On-site reference (relatively undisturbed) stream and wetland sites were selected to orient
restoration design and to provide baseline information on target (post-restoration) wetland
conditions. A regional vegetation reference data base and on-site inventory were used to
characterize target, post-restoration species composition. Topographic maps of the basin
floor were also prepared to show the gradation from permanently to semi-permanently
inundated conditions throughout the lower half of the Site. A concurrent pool elevation
and sedimentation study provided information on sedimentation and wetland development
around the point of stream inflow and conservation pool levels. Topographic data were
0 overlaid on wetland restoration areas to establish methods for construction and restoration
of wetland communities within the Site.
Detailed topographic mapping to 1-foot contour intervals was developed by ground survey
paneling and aerial photogrametric methods. Additional land surveys were performed to
establish channel cross-sections and measure reference wetland surface topography.
Field investigations were performed in the Summer of 2000 including soil surveys, on-site
resource mapping, land surveys, and landscape ecosystem classifications. Existing plant
communities and jurisdictional wetlands were described and mapped according to
landscape position, structure, composition, and groundwater analyses.
Wetland boundaries were obtained from a delineation performed in 1998. NRCS soil map
units were ground truthed by licenced soil scientists to verify units and to map inclusions
and taxadjunct areas. The revised soils maps were used as additional evidence for
predicting natural community patterns and wetland limits prior to human disturbances.
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Groundwater conditions were modeled using DRAINMOD, a computer model for
simulating withdrawal rates for shallow soils with high water tables. The model was
utilized to predict historic hydroperiods, the extent of wetland degradation due to channel
entrenchment, and the potential for wetland restoration through stream modification.
Surface water analyses for the Hickory Creek site were completed using standard study
methods of the U.S. Army Corps of Engineers (USACE) and NRCS. Flood events of a
magnitude which are expected to be equaled or exceeded once on average every 1-, 2-,
5-, 10-, or 100-year period were selected for use. These flood events are commonly called
the 2-, 5-, 10-, and 100-year floods. Floods with a return frequency of less than 2 years
are usually not studied in engineering applications. These analyses reflect either existing
or proposed conditions at the Site. The projected frequency and extent of overbank
flooding were used to determine potential for riverine wetland restoration in floodplain
portions of the Site.
This Site has been selected for wetland restoration use to promote a reduction in
sediment, nutrients, and pollutants flowing into Randleman Reservoir. Mitigation
activities are intended to provide sediment deposition, and pollutant and nutrient cycling
from surface waters within created and restored wetland areas. Recycling functions are
designed to reduce elevated nitrogen and phosphorus loads from the watershed towards
background (forest) levels, prior to discharge into the reservoir.

J
10
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3.0 EXISTING CONDITIONS
3.1 PHYSIOGRAPHY, TOPOGRAPHY, AND LAND USE
The Site is located in the Piedmont Physiographic Province of North Carolina.
Physiography is characterized by moderately hilly terrain with interstream divides
intermixed with steeper slopes along well-defined drainage ways. The Site is situated in
the Hickory Creek floodplain within the Cape Fear River Basin (Hydrologic Unit #03030003
[USGS 19741, DWQ Sub-Basin 03-06-08). The Site is located approximately 7.5 miles
southeast of High Point and approximately 10.5 mi southwest of Greensboro. Annual
precipitation in the region averages 42 inches per year with June and August representing
the months that support the highest average rainfall (4.21 inches and 4.36 inches
respectively) (USDA 1977).
The Site contains an approximately 3400-foot reach of Hickory Creek (Figure 4). Hickory
Creek supports a primary watershed of approximately 8.7 square miles and flows into the
Deep River 1.8 miles downstream. Three auxiliary tributaries flow into lower reaches of
the Site within a relatively broad floodplain area located immediately north of SR 1132
(Figure 4). Above the confluence with these tributaries, the Hickory Creek valley steepens
and the floodplain narrows as the main-stem channel is enclosed by moderate to steeply
sloped escarpments along adjacent uplands.
The Hickory Creek watershed supports a mixture of forest, agricultural, residential,
commercial, and infrastructural uses. The headwater region extends into urban areas
associated with the City of Greensboro, including the Interstate 85 (1-85) highway
corridor. Lower portions of the watershed, south of 1-85, primarily support residential
communities, pasture land, forest, and limited commercial development. Land use within
the watershed surrounding the Site includes recently timbered tracts, nearby residential
homes, and abandoned and active agricultural lands situated within the creek floodplain
(Figure 4).
The Site encompasses one primary physiographic landscape area for restoration planning
purposes; elevated stream terrace (Figure 4). The primary variables utilized to segregate
wetland landscape units include land slope, overbank flood frequencies (Section 4.3), and
the rate and direction of groundwater flow (Section 4.4).
The stream terrace encompasses 29.4 acres along both sides of the stream channel. The
main channel averages approximately 30 feet in width and 6 feet in depth through the
area. The main-stem channel and auxiliary tributaries were dredged and straightened
during conversion of the floodplain to agricultural land. Construction of stream-side
levees during dredging activities and down-cutting into the channel bed have effectively
eliminated the presence of an active floodplain within the Site. Under historic conditions,
the stream terrace is expected to have included active floodplains and a low stream terrace
supporting natural communities such as Piedmont bottomland hardwood forest and mixed
mesophytic hardwood forest (Schafale and Weakley 1990).
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Down-cutting in the stream has reduced the frequency of overbank flooding within the
primary floodplain from an estimated 1-year return interval to a 2- to 10-year return
1 interval under existing conditions. Due to extensive dredging, the constructed canals have
also induced a relatively steep groundwater gradient across the floodplain and relatively
rapid groundwater discharge into the stream channel. As a result, wetland functions
(sediment retention, nutrient cycling, energy dissipation, etc.) have been effectively
eliminated from the physiographic area by stream alterations.
3.2 SOILS
Surficial soils have been mapped by NRCS (USDA 1977). Soils were verified in the
summer of 2000 by licenced soil scientists to refine soil map units and locate inclusions
and taxadjunct areas. Systematic transects were established and sampled to ensure
proper coverage. Refined soil mapping is depicted in Figure 5. Primary soil types include
the Chewacla series, Wehadkee series, and Congaree series.
Chewacla soils (Fiuvaquentic Dystrochrepts) encompass approximately 13.8 acres (47%)
of the 29.4-acre Site. Chewacla soils are somewhat poorly drained, nonhydric soils which
have been formed primarily by fluvial activity. Chewacla soils, located in the broad,
relatively flat valley floor, contain numerous inclusions of hydric soils (i.e. Wehadkee
[Typic Fiuvaquents]) in depressions, ephemeral channels, and swales which are more likely
to support wetland hydrology. Chewacla soils generally exhibit broad, inter-layered
variability in texture and permeability dependent upon energy dissipation and sediment
deposition patterns associated with each stream overbank flood event. Soil texture
generally ranges from coarse sandy loam to silt loam of moderate to moderately rapid
infiltration. Important factors in the formation and maintenance of wetland systems as
hydric inclusions in the Chewacla map units include: 1) microtopography and variability
in fluvial deposition across the landscape; 2) groundwater and surface water movement
from adjacent uplands along the outer edge of the floodplain; and 3) groundwater
discharge rates from the interior floodplain into the stream channel. Stream dredging,
straightening, and conversion to agricultural lands has likely increased the extent of
Chewacla (nonhydric) soils and concurrently decreased the extent of Wehadkee (hydric)
map units in the Site.
Hydric soils are defined as "soils that are saturated, flooded, or ponded long enough
during the growing season to develop anaerobic conditions in the upper soil layer" (USDA
1987). Hydric soils comprise the Wehadkee series (Typic Fiuvaquents), located primarily
within relict backwater sloughs, depressions, ephemeral channels, and swales which
remain within the secondary floodplain. Under existing conditions, the Wehadkee series
comprises approximately 2.9 acres (10%) of the Site.
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developed in loamy alluvium. The soil is located primarily along relatively narrow
floodplains and the more steeply sloped valley comprising 1 1.5 acres in upper reaches of
the Site. The seasonal high water table ranging from 2 to 4 feet below the surface.
Congaree soil map units are not expected to have supported wetlands historically with the
exception of minor inclusions of the Wehadkee series (Typic Fluvaquents) in depressional
sloughs.
3.3 PLANT COMMUNITIES
Plant communities are influenced by logging, dredging activities and Site conversion to
agricultural lands. Five communities have been identified for descriptive purposes,
including: 1) bottomland hardwood forest; 2) Piedmont swamp forest; 3) agricultural land;
4) levee/stream-side forest; and 5) early successional / cut areas (Figure 6).
1 Bottomland Hardwood Forest
Bottomland forest accounts for approximately 13.9 acres in central reaches of the Site.
The bottomland forest assemblage has experienced prolonged degradation from past
logging, watershed diversion, agricultural usage, and ditch networks. The forest canopy
includes box elder (Acer negundo), sycamore (Platanus occidentalis), green ash (Fraxinus
pennsylvanica), tulip poplar (Liriodendron tulipifera), American elm (Ulmus americana), and
black willow (Salix nigra). Under-story species distribution is variable along hydrologic
gradients and includes muscadine grape (Vitis rotundifolia), beggar's ticks (Desmodium
sp.), Japanese honeysuckle (Lonicera japonica), poison ivy (Toxicodendron radicans),
jewel-weed (Impatiens capensis), Chinese privet (Ligustrum sinense), Virginia creeper
(Parthenocissus quinquefolia), and blackberry (Rubus sp.).
Piedmont Swamp Forest
Swamp forests persist within isolated, relict backwater areas along the eastern Site
boundary. This community, covering approximately 2.8 acres, appears to have been
affected by reductions in drainage area, loss of surface hydrodynamics, reductions in
hydroperiod, and past conversion to crop land. The canopy includes species listed in
bottomland hardwood forest, with inclusion and increasing frequency of swamp chestnut
oak (Quercus michauxii), ironwood (Carpinus caroliniana), swamp cottonwood (Populus
heterophyllus), and sweetgum (Liquidambar styraciflua). The understory is dense to
sparse, depending on the openness of the overstory. Under open canopies, the understory
is dominated by a dense layer of graminoids and forbs, including sedges (Carex spp.),
rushes (Juncus spp.), lizard tail (Saururus cernuus), false nettle (Boehmeria cylindrica),
seedbox (Ludwegia spp.), and jewel-weed.
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Levee / Stream-Side Forest
Approximately 3.1 acres of levee forest are found in a narrow fringe, on the elevated
deposits (natural and man-made) along Hickory Creek. These moderately well drained
areas support plant species characteristic of levee forest communities (Schafale and
Weakley 1990). Canopy species include box elder, sycamore, river birch (Betula nigra),
green ash, black walnut (Juglans nigra), sweetgum, ironwood, and red maple. The mid-
story is dominated by eastern cedar (Juniperus virginiana), black cherry (Prunus serotina),
Chinese privet, and honey locust (Gleditsia triacanthos). Understory species include virgin
bower (Clematis virginiana), Japanese honeysuckle, muscadine grape, mouse ear
chickweed (Cerastium glomeratum), common greenbrier (Smilax rotundifolia), and poison
ivy.
Agricultural Land
1 Approximately 7.1 acres of pasture land is located primarily in upper reaches of the Site.
Hay was last harvested in June of 2000. Pasture land is dominated by a variety of grasses
and herbs. The predominant species is fescue (Festuca spp.). Other characteristic species
include asters (Aster spp.), goldenrods (Solidago spp.), horseweed (Erigeron canadensis),
pigweed (Chenopodium album), ragweed (Ambrosia artemis/ifolia), common morning glory
1 (lpomoea purpurea), clover (Trifolium spp.), crabgrass (Digitaria spp.), and love grass
(Erogrostis sp.).
Adjacent border and forest edge communities support young sweetgum, black cherry, box
elder, and red maple (Acer rubrum). Thickets containing blackberry, winged sumac,
Canada elder (Sambucus canadensis), switch cane (Arundinaria gigantea), muscadine
grape, and common greenbrier are also present.
Early Successional / Cut Areas
Approximately 1.6 acres consists of recently clear-cut forest land along the eastern
property boundary. This community is characterized by disturbance adapted species such
as sapling elements of eastern red cedar (Juniperus virginiana), box elder (Acer negundo),
and red maple (Acer rubrum). Understory species include a dense thicket of common
greenbrier (Smilax rotundifolia.), poison ivy (Toxicodendron radicans), Japanese
honeysuckle (Lonicera japonica), blackberry (Rubus sp.), and common ragweed (Ambrosia
artemislifolia).
3.4 HYDROLOGY
The Site is located within the Piedmont hydrophysiographic province, which encompasses
the entire drainage basin for the East and West Forks of the Deep River. The region is
characterized by moderately hilly terrain with interstream divides exhibiting dendritic
drainage patterns and moderately steep slopes along valley floors (0.005-0.015 rise/run).
The region is characterized by moderate rainfall. In Guilford County, precipitation averages
42 inches per year with precipitation evenly distributed throughout the year (USDA 1977).
17

I
Large floods (20-100 year return interval) typically correspond to large thunderstorms and
tropical events in the region.
Bed load material supplied by the region consist primarily of silts, sands, and weathered
bedrock (very coarse sand and small gravel). Bedrock outcrops are considered common
within incised streams in more steeply sloped valleys. Suspended load consists primarily
of easily eroded clays and silts, which transport attached nutrients into downstream
waters. Erosion and suspended sediment loads have been linked to nutrification problems
within the Piedmont hydrophysiographic province, including the Randleman Reservoir
region (DWQ 2000).
Surface Water
The Site encompasses two valley types in association with the 3400-foot reach of Hickory
Creek and the confluence with three unnamed tributaries (Drainage Area = 8.7 square
miles). The lower half of the Site consists of a relatively broad, abandoned floodplains
extending along a 1400-foot reach of Hickory Creek. In this section, the valley slope
measures approximately 0.004 rise/run, suggesting the presence of a relatively flat valley
floor relative to typical conditions in the Piedmont Province. The floodplain ranges from
500 feet to 900 feet in width. A majority of this floodplain area typically resides between
680 feet to 684 feet above mean sea level and will be directly affected by the established
reservoir pool (to 682 feet above mean sea level). Capacity for surface water runoff in this
area is reduced due to the relative lack of land slope and broad width of the floodplain
floor. Ponded conditions have been observed along the outer floodplain fringe for more
than 1 week after significant rainfall events in August 2000.
In upper reaches of the Site, the valley floor narrows and steepens along an approximately
2000-linear foot reach. The floodplain slope steepens to an average, 0.007 rise/run
including floodplain widths of less than 200 feet in most areas. The elevation of these
floodplains typically ranges from 685 feet to 687 feet above mean sea level and outside
the influence of the reservoir pool. Surface water runoff within this floodplain appears
relatively rapid in both the down-valley and across-floodplain direction. Ponding was
absent in this area immediately after significant rainfall events with rapid return flow
observed into the main-stem channel.
The main-stem and auxiliary channels were dredged and straightened in the last several
decades with low-lying levees constructed adjacent to agricultural areas. Due to past
dredging and/or active down-cutting, the cross-sectional area of within the Hickory Creek
channel measures approximately 180 square feet. However, according to regional curves,
a stable Hickory Creek channel is projected to support cross-sections of approximately 90
square feet (Harman et a/. 1999, Rosgen 1996). The incised channel supports a sinuosity
(channel length/valley length) of 1.1. Substrate within the channel is composed of
unconsolidated sand, small gravel, and bedrock outcrops exposed by incision and localized
tl
18

bank erosion. The channel is classified as a G4 (gravel dominated gully) based on fluvial
geomorphic features (Rosgen 1996).
Stream discharge and flood elevations under existing conditions have been predicted
based on hydraulic models (Section 4.2). Figure 7 provides model predictions for the 1-
(projected bankfull), 2-, 5-, and 100-year storm (Section 4.3). The study suggests that
entrenchment has confined the 1- to 2-year flows within the eroding channel banks,
effectively bypassing floodplain functions associated with pollutant removal and
maintenance of wildlife habitat for overbank flood dependent species.
Groundwater
Surface water hydrodynamics, such as periodic overbank floods, fluvial sediment
deposition, and hydraulic energy dissipation, represent important attributes of floodplains
and bottomland hardwood forest in the region. However, streams in the region typically
function as groundwater withdrawal features throughout most of the year. Therefore,
groundwater inputs from auxiliary watersheds and upland slopes abutting the floodplain
represent the primary hydrologic input resulting in the development and maintenance of
riverine wetlands at this Site.
Groundwater gradients in June 1998 and May 2000 indicate that the groundwater table
typically resides from surface saturation to 6 feet below the land surface. In lower reaches
of the Site, the groundwater gradient is relatively flat along the outer floodplain and
steepens within distances of 200 to 300 feet from the dredged stream channels. In upper
reaches of the Site, the groundwater gradient remained more than 2 feet below the
surface throughout the relatively narrow floodplain with a relatively steep gradient
induced by the stream channel.
A majority of the Site outside of the proposed reservoir pool is expected to support limited
groundwater storage potential typically associated with maintenance of wetland surfaces.
Although adjacent escarpments supply riparian inflow of groundwater, this flow appears
steeply inclined with relatively rapid discharge towards the stream channel. Entrenchment
of Hickory Creek has further accelerated groundwater discharge to depths of greater than
6 feet below the surface near the stream channel. Restoration of a shallower (less incised)
stream network will generate a flatter groundwater gradient. However, groundwater
models (Section 4.4) suggest that groundwater tables will continue to remain more than
1 foot below the surface. Therefore, restoration of wetlands within upper reaches of this
Site may require establishment of a backwater (surface water induced) wetland
immediately above the reservoir. Backwater wetland conditions may be induced by
establishment of a greentree impoundment across the valley floor.
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3.5 WATER QUALITY
Hickory Creek maintains a State best usage classification of WS-IV CA ((Stream Index No.
17-8) (DWQ 2000). Class WS-IV waters are protected as water supplies which are in
moderate to highly developed watersheds. Point source discharges are generally required
to meet stringent pre-treatment standards, to maintain pre-treatment failure (spill
prevention) plans, and to perform point source monitoring for toxic substances. Local
programs to control nonpoint source and stormwater discharge of pollution are also
required. CA signifies a Critical Area designation for watershed areas within 0.5 miles of
a water supply intake for the reservoir.
The Site consists primarily of existing and former agricultural land adjacent to the stream
channel. Fertilizers, pesticides, and nutrients associated with land uses may have
influenced water quality in the vicinity. Restoration of wetland hydrology and diversion
of area runoff onto restored wetland surfaces will provide local water quality benefits,
including important functions such as particulate retention, removal of elements and
compounds, and nutrient cycling.
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Historically, the floodplain provided water quality benefits to the 8.7 square mile
watershed associated with Hickory Creek. However, runoff from this land area effectively
bypasses wetland floodplains as the entrenched channel transports flow directly through
the Site. Restoration of wetland hydrology and diversion of watersheds onto restored
wetland surfaces will provide for restoration of overbank flooding and associated water
quality benefits above the Randleman Reservoir.
Because the Site is located at the elevation of the reservoir conservation pool, sediment
transport capacity of the stream system will be generally stopped at elevations of 681 feet
above MSL. A sediment wedge will develop within the reservoir pool and incrementally
extend further into the open water area. Research suggests that up to 300,000 cubic feet
(0.7 acre-feet) of sediment will be deposited annually within the reducing aquatic
environment (Simmons 1976). Associated pollutants will not generally be degraded,
assimilated, or recycled through periodic wetting (reduction) and drying (oxidation).
Therefore, wetland restoration has been designed to reduce sediment transport capacity
within the 3,400-foot reach of Hickory Creek. As a result, the sediment wedge will be
extended in the upstream direction outside of the reservoir pool (above elevation 682),
where wetland functions will potentially provide for greater pollutant processing.
3.6 JURISDICTIONAL WETLANDS
Jurisdictional areas are defined using the criteria set forth in the U.S. Army Corps of
Engineers, Wetlands Delineation Manual (DOA 1987). Approximately 2.9 acres of
jurisdictional wetlands were delineated on-site and confirmed by the U.S. Army Corps of
Engineers. Figure 8 depicts the boundary location of existing jurisdictional wetland
systems.
21
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stream oxbow in lower reaches of the Site. Discharge from adjacent groundwater slopes
and the relatively flat valley floor provide for periodic surface water expression during early
portions of the growing season. Wetland extent was most likely more extensive prior to
stream dredging and Site conversion to agricultural lands. Approximately 0.4 acres of
these jurisdictional wetlands will be inundated by the reservoir conservation pool (2.5 net
acres of jurisdictional wetlands will remain after filling of the reservoir).

23

u
4.0 WETLAND RESTORATION STUDIES
This section summarizes studies performed to orient restoration design. Studies include:
1) Restoration Alternatives Analyses: Alternatives for wetland restoration
relative to stream, floodplain, and reservoir functions were assessed.
2) Reservoir Pool Sedimentation and Wetland Vegetation Study: Sedimentation
patterns and extent of wetlands were assessed on existing reservoirs in the
region.
3) Surface Water Analyses: Overbank flooding frequency and extent was
estimated based on the selected wetland restoration method.
4) Groundwater Modeling: The effect of drainage features on groundwater
wetland hydroperiods was modeled.
5) Reference Plant Communities: Reference wetland communities were
sampled to predict the target distribution of vegetation to be established in
restoration areas.
6) Reference Physiography and Surface Topography: Reference wetland
surfaces were measured within an existing greentree impoundment to
characterize long term, projected conditions at the Site.
4.1 RESTORATION ALTERNATIVES ANALYSES
The objectives of this project include:
1) Assist in protecting the drinking water supply from pollutants discharged
from the developing watersheds. Pollutants attached to sediment
represents the primary water quality concern for this project.
2) Maximize benefits to water quality through establishment of functioning
wetlands above the reservoir pool.
3) Replace habitat for wetland dependent wildlife displaced by establishment
of open water.
4) Maximize the area of wetland restoration achieved by the project.
Restoration alternatives suggested by project participants are briefly described below.
Stable Channel Construction
Reconstruction of a potentially stable stream system was assessed as a replacement for
the existing, dredged and incised channel. The new channel would be designed to mimic
referenced, stable'attributes including the geomorphic dimension, pattern, and profile
needed to transport water and sediment produced by the watershed. The restored
channel would reduce the rate of groundwater withdrawal from adjacent floodplains,
potentially resulting in wetland hydrology restoration in certain areas.

24

This alternative would facilitate transport of sediment generated by the watershed into
the Randleman Reservoir. Within the lower half of the Site, this capacity to transport
sediment would be unavoidably stopped by the conservation pool associated with the
reservoir. In addition, facilitating transport of sediment and pollutants into water supply
waters is considered contrary to project objectives. Therefore, this option was discarded.
Alluvial Wetland Fan Development
This option is designed to elevate water tables and reduce sediment transport into the
reservoir. Alluvial fan development entails placement of fixed, in-stream weirs within the
dredged channel. The in-stream modifications are expected to reduce the degree of
channel incision, increase overbank flooding, reduce stream sediment transport capacity,
and provide greater sediment deposition within vegetated wetlands. The system would
progress towards an alluvial wetland fan where the channel actively migrates across fluvial
material. During the interim period, in-stream structures will sustain significant energy
during flood events; therefore, the potential exists for development of channel by-passes
(shoot cut-offs) around the structures. As such, risk of wetland restoration failure exists.
The structures must be designed to avoid short-circuiting and provide for sediment
deposition in the incised channel. Over a relatively long period of time, the shallower
channel would invariably abandon the structures and begin to actively migrate across the
restored floodplain. At this point, the system would need to be monitored for evidence
of head-cutting immediately above the reservoir or migration back into the abandoned,
dredged channel. Additional structural modifications may be required in the future, after
the migrating stream abandons the existing dredged channel.
Within lower reaches of the Site, passive development of an alluvial fan immediately
above the reservoir represents a viable option for this Site. This option will reduce initial
disturbance in the floodplain associated with greentree impoundments, reduce
implementation cost relative to greentree impoundments, and will require less need for
seasonal management of the structures. Based on alternatives analyses, placement of in-
stream structures and alluvial wetland development has been selected as the preferred
mitigation alternative within the lower valley and Chewacla soil map units depicted in
Figure 5.
Based on groundwater models (Section 4.4) passive development of an alluvial wetland
fan within upper reaches of the Site (Congaree soil map units, Figure 5) does not
represent a viable option for this Site. Due to soil characteristics, across terrace slope,
and down-valley slope, the groundwater model suggests that groundwater migration will
continue into the low-lying channel corridor, with development of shoot cut-offs
considered likely during storm events. In essence, the floodplain floor is not wide enough
or flat enough to induce adequate groundwater retention or to provide adequate energy
dissipation functions in the vicinity of the in-stream weirs. Therefore, this option was
discarded in favor of greentree impoundments.
a
25

0
Greentree Impoundments
This alternative is similar to alluvial fan development described above. However,
Greentree impoundments include a series of floodplain levees and controllable outlet
structures that are modified periodically throughout the year to induce backwater flooding
and promote the development of forested, shrub-scrub, and emergent wetlands.
Greentree impoundments have been constructed above other water supply reservoirs in
the region for wetland, wildlife, and sediment retention functions. These structures can
be controlled to regulate the depth and frequency of inundation based upon objectives
of the system. In this case, the structures would be used to establish vegetated wetlands
and limit transport of pollutants into the reservoir.
In general, the levee system is constructed to provide for less than 2 to 3 feet of
inundation during winter months, to prevent over-topping, and to allow for survival of tree
seedlings. The winter depth is generally dependent upon the height of seedlings. The
raising and lowering of outlet structures requires regular monitoring and maintenance by
qualified personnel to facilitate the growth of tree species. The actual date that the
outlet is modified may vary annually and is dependent upon localized conditions within
the watershed. Seedling mortality is tracked on an annual basis and the date of spring
lowering is modified to maximize the rate of forest regeneration. Tree species selected for
planting may also be modified based upon collected data. Greentree impoundments
designed for forested wetland restoration have failed in the past, due primarily to lack of
resources for long term monitoring, management, and manipulation.
Based on alternatives analyses, Construction of a greentree impoundment across the
Hickory Creek floodplain represents the preferred option in upper reaches of the Site.
Construction activities would occur primarily within maintained pasture areas. Impacts
to existing forest stands will be limited. In- addition, the structures would allow pro-active
control of wetland development and function behind each impoundment.
4.2 RESERVOIR POOL LEVEL AND SEDIMENTATION ANALYSIS
Reservoir sediment quality is an important environmental concern because sediment may
act as both a sink and a source of water-quality constituents to the overlying water
column and biota. Sedimentation rates are dependent on existing land use, land use
modifications, soils, and basin topography. Alternatives for sediment reduction potentially
include up-stream land management techniques, sluicing of sediment through the
reservoir, or interception of the sediment prior to entry into the reservoir. Even with strict
land management techniques in an urbanizing watershed, a certain amount of
"background" sediment will continually be moved by erosion processes. In a stable river
bed, erosion, sediment transport and deposition are in equilibrium. Dam construction
disrupts this balance, raising the base level of streams above the reservoir, and
encouraging the deposition through reduction of the gradient. As a result, the stream
1 01 deposits sediment as a delta at the confluence with the conservation pool. The
deposition process, otherwise known as warping or shoaling, advances at varying rates
r_n
26

o
p dependent on the site and rate of sediment supply. Slope angles and extension patterns
on the delta are dependent on the particle size of the prevailing sediment deposited, with
courser sediment associated with higher angle slopes.
The Hickory Creek wetland restoration project resides immediately above the normal pool
elevation (i.e. conservation pool) for the Randleman reservoir (Elevation = 682 feet above
10
MSL). Currently, the stream channel is incised to depths which induce a groundwater
withdrawal gradient (rate) that does not allow for wetland presence on the adjacent
primary floodplain. After the reservoir is constructed, sediment accretion is likely to occur
within the Site, immediately upstream and downstream of the conservation pool. This
accretion will form a "sediment wedge" within the floodplain, stream channel, and delta
area inducing passive wetland conditions for an unknown distance (or elevation) in both
the upstream and downstream direction.
Obiectives
The objective of this study is to collect the following information on existing reservoirs
in the region:
1) Determine the elevation range above the conservation pool that supports
relatively contiguous wetlands apparently resulting from the conservation
pool, groundwater mounding, and/or sediment accretion. The data reported
will include the elevation of the conservation pool, the average period that
the reservoir water surface resides at the conservation pool elevation, the
elevation range for relatively contiguous, forested wetland formation, and
elevation range for emergent wetland formation.
2) Determine the elevation range of the stream bed above the conservation
pool that has sustained sediment accretion to the extent that the channel
supports an average depth of 1 foot or less.
3) Determine the range of channel depths present in the wetland elevation
range.
4) Prepare a profile and plan view that depicts typical conditions relative to the
conservation pool.
Methods
Field reconnaissance of several reservoirs and impoundments in the central Piedmont was
conducted in order to establish baseline information on sedimentation and wetland
development around the point of stream inflow and conservation pool levels. Two sites
were chosen that best exhibited long term sedimentation processes (> 10 years) for large
and small watersheds. One site is located at the point of inflow of Little Briar Creek into
Crabtree Lake, Wake County. Little Briar Creek services a watershed of approximately
13.5 square miles. Land use for this sub-basin is predominantly forested, but is part of

27

n
a a rapidly developing Research Triangle Park, including the Raleigh-Durham International
Airport. The second site is located at the inflow of an unnamed tributary of Horse Creek
into Falls Lake, Wake County. The tributary services a watershed of approximately 0.3
square miles. Land use for this watershed is predominantly forested, though residential
development is encroaching upon the upper reaches of the area.
Topographic maps of the alluvial wetland fans were prepared to 0.5-foot contour intervals
by laser level and Global Positioning System (GPS) measurements. Embankments,
shorelines, and wetland boundaries were measured and surveyed relative to the reservoir
water surface elevations. For Falls Lake, conservation pool and daily water surface
elevations were obtained for a 16-year period from USACE (1984-1999). Pool elevation
for Crabtree Lake was obtained from the elevation of the low-flow spillway crest tied to
a local USGS benchmark. Cross-sections and profiles were generated for the local stream
reach and floodplain area. Sediment borings were sited at various points along the
boundary of wetlands to determine depth of groundwater table relative to reservoir pool
elevations.
Results
Figures 9 and 10 provide a plan view and cross section for the sites at Crabtree Lake and
Falls Lake, including the groundwater elevations along the wetland fringe. Within the
conservation pool, a majority of the sediment deposition area resides under approximately
0.5 feet of water. Sediment deposition is greatest below the pool elevation contour with
inundated sediment bars generally extending into the lake over time. As the deposition
wedge elevates within central reaches of the inundated floodplain, the channel tends to
migrate towards the toe of adjacent slopes, incrementally filling the inundated valley floor.
On average, emergent wetland vegetation is present on accreted sediment to within 1 foot
below the normal pool. Forested and shrub-scrub wetland vegetation is typically present
to 2 feet above the normal pool in the upstream direction. These wetlands appear be
induced by an up-welling in the down-valley migration of groundwater, prior to inflow
with the conservation pool.
A review of lake level data for these reservoirs suggests that the water surface that
induces these wetlands resides within 0.5 feet of the conservation pool elevation, on
average, for 66% of the year. In Falls Lake, data indicate that the sediment wedge is
generated by water surfaces within 2 feet of the conservation pool elevation for 82% of
the time over the 15-year monitoring period'.
1 For Falls Lake, the conservation pool elevation has been held fixed at 250.1 feet above MSL
over the 15-year monitoring period.
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The study suggests that sediment deposition is concentrated within inundated areas at
or just below the conservation pool elevation. As the sediment surface approaches the
® elevation of the conservation pool, the wedge begins to extend further into the reservoir.
® This accreting surface passively develops emergent wetland vegetation on surfaces within
1 foot of the conservation pool. This accreting wetland surface will continue to enlarge
® over the life of the reservoir.
Based on the two reference sites studied, forested and shrub-scrub-wetlands typically
develop passively on floodplain surfaces that reside up to 2 feet above the conservation
pool. The area sustains sediment deposition in the active channel, including channel
migration across the developing delta over time.
Application
For this application, the water surface within the filled, Randleman Reservoir is assumed
to remain within 0.5 feet of the conservation pool (682 feet above MSL) for a minimum
of 66% of the year and within 2.0 feet of the conservation pool for a minimum 82% of
the time over a 15-year period. Figure 11 depicts mapping of resulting passive wetland
development projected to occur on the Site as a result of the Randleman Reservoir.
The Site includes approximately 5.3 acres of open water (below 681 elevation) that are
projected to support future accretion and development of emergent wetlands. The 5.3-
acre area includes backwater conditions from the reservoir that will extend up a majority
of the on-site reach of the Hickory Creek channel under existing conditions.
Between elevations of 681 and 682 feet above MSL, emergent and submerged aquatic
vegetation is projected to develop. This area will be semi-permanently saturated or
inundated up to 1 foot in depth immediately after filling the reservoir. Based on reference
t studies, the area is expected to support 3.5 acres of wetlands upon project completion.
In upper reaches of the lake effect area, shrub-scrub and forested wetland systems are
expected to be passively restored, encompassing approximately 1 1.0 acres on lands from
682 to 684 feet above MSL.
In total, approximately 14.5 acres are expected to support wetlands as a result of
hydrological modifications associated with the reservoir. Active wetland restoration
measures will include placement of sediment control structures (check dams) within
entrenched channels along the immediate periphery of the reservoir pool and construction
of a green tree impoundment in areas above the reservoir pool. Additional active
restoration measures will include preparation of pastured surfaces and planting of wetland
adapted vegetation designed to laterally extend the sediment wedge and wetland extent
I in the up-valley direction.
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4.3 SURFACE WATER ANALYSES
Surface drainage on the Site and surrounding area was analyzed to predict the effects of
diverting existing surface drainage into wetland restoration areas along the primary and
secondary floodplains. Several alternatives were evaluated to determine surface water
modifications that maximize wetland acreage and water quality benefits, while providing
for increased wetland habitat for dependent species.
Hydrologic and hydraulic analyses were completed using standard study methods of
USACE and NRCS. Flood events of a magnitude which are expected to be equaled or
exceeded once on average every 1-, 2-, 5-, 10-, or 100-year period were selected to
characterize existing and proposed conditions at the Site.
Hydrologic Analyses
Hydrologic analyses were carried out using the USACE HEC-1 model to establish the peak
stream discharge for the 1-, 2-, 5-, 10-, and 100-year flood events.
Input for the HEC-1 model consisted of synthetic storm precipitation data, drainage area,
NRCS curve numbers, and drainage basin lag time. Table 2 summarizes the total, 24-hour
precipitation event for each storm that was analyzed. Precipitation data was obtained
from U.S. National Weather Service documents (NOAA TP-40 and Hydro-35). The
drainage area was delineated on 7.5-minute USGS topographic maps and then subdivided
into subbasins based on land use or location of tributaries. The drainage area for each
subbasin was estimated using a planimeter. The NRCS curve numbers were estimated
using methods described in NRCS TR-55. The subbasin lag times were estimated using
Snyder's method.
Because there were no onsite gage data, the HEC-1 computer models could not be
calibrated. The models were validated by comparing the 100-year peak discharges
estimated from the HEC-1 models with peak discharges estimated by regional formulas for
the Piedmont region of North Carolina in the USGS Water-Resources Investigations Report
87-4096. NRCS curve numbers for the HEC-1 models were adjusted until the HEC-1 peak
discharges were within 25 - 30% of the regional formula values. Table 2 summarizes peak
discharges estimated by the validated HEC-1 model and the regional equations.
Hvdraulic Analvses
Water-surface elevations of the 1-, 2-, 5-, 10-, and 100-year floods of Hickory Creek were
estimated using the USACE HEC-2 computer program. Channel cross sections for the
hydraulic analyses were obtained from the most currently available HEC-2 computer runs
completed for Federal Emergency Management Agency (FEMA) Flood Insurance Studies
(FIS). Additional cross-sections that were needed to model proposed structures were
taken from digital orthophoto maps with a contour interval of 1 foot.
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Roughness coefficients (Manning's "n") in the channels and on the overbank areas were
taken from the HEC-2 computer runs previously mentioned and verified with field
inspections of the sites. Roughness coefficients in the main channel were 0.06 and 0.12
for overbank areas.
Starting water surface elevations and energy slope for existing conditions were estimated
from the published flood insurance studies for Guilford County. The slope-area option
provided by the HEC-2 model was used to estimate the true value of the water surface
elevation at the beginning cross-section. For future conditions, the starting water surface
elevation at the first cross-section was 688.21 feet (100-year reservoir pool elevation) for
the 100-year flood and 682 feet for the 1-, 2-, 5-, and 10-year floods (normal reservoir
pool elevation).
Tables 2 summarizes the water surface elevations for existing and proposed conditions.
Figure 7 (Section 3.0) depicts modeled flood elevations for the 1-, 2-, 5-, 10- and 100-
year, 24-hour storm event. The model indicates that overbank flooding has been
effectively eliminated until the 2-year storm along the entrenched channel under existing
conditions.
Restoration methods are designed to reduce the channel from 6 feet in depth below the
floodplain to saturated / inundated conditions in the vicinity of the reservoir pool. In
addition, a greentree impoundment is proposed immediately above the reservoir with
water surface elevations fluctuating seasonally between 682 feet and 685 feet above
mean sea level, representing surface saturated / inundated within a majority of the former.
dredged channel.
Establishment of the reservoir pool and greentree impoundment will elevate flood levels
fl to elevations conducive to wetland restoration. Therefore, post-project conditions were
modeled to evaluate the potential increase in flood levels if the greentree impoundment
controllable weirs were lowered to the maximum extent feasible. Water surface elevations
range from 2.9 feet (1-year storm) to 9.1 feet (100-year storm) feet higher for proposed
conditions in downstream reaches of the Site, due primary to the reservoir pool. As the
cross-sections progress upstream away from the reservoir, the difference between
proposed and existing conditions decreases with the 100-year flood elevation increasing
by an average of approximately 1.8 feet (starting upstream of cross-section 1376).
P1 Potential impacts to above ground structures were not observed during field reviews
within the post-project 100-year floodplain area. However, immediately below the Site,
SR 1 132 appears to reside under the projected 100-year flood elevation induced by the
reservoir pool (688.2 feet above mean sea level).

35

i
4.4 GROUNDWATER MODELING
Groundwater modeling was performed to characterize water table elevations under historic
(reference), existing, and post-restoration conditions. The groundwater modeling software
selected for simulating shallow subsurface conditions and groundwater behavior at the
Site is DRAINMOD. This model was developed by R.W. Skaggs, Ph.D., P.E., of North
Carolina State University (NCSU) to simulate the performance of water table management
systems.
Model Description
DRAINMOD was originally developed to simulate the performance of agricultural drainage
networks on sites with shallow water table conditions. DRAINMOD predicts water
balances in the soil-water regime at the midpoint between two drains of equal elevation.
The model is capable of calculating hourly values for water table depth, surface runoff,
subsurface drainage, infiltration, and actual evapotranspiration over long periods
referenced to climatological data. The reliability of DRAINMOD has been tested for a wide
range of soil, crop, and climatological conditions. Results of tests in North Carolina
(Skaggs, 1982), Ohio (Skaggs et al. 1981), Louisiana (Gayle et al. 1985; Fouss et a/.
1987), Florida (Rogers 1985), Michigan (Belcher and Merva 1987), and Belgium (Susanto
et aL 1987) indicate that the model can be used to reliably predict water table elevations
and drain flow rates. DRAINMOD has also been used to evaluate wetland hydrology by
Skaggs et al. (1993). Methods for evaluating water balance equations and equation
variables are discussed in detail in Skaggs et al. (1993).
DRAINMOD has been modified for application to wetland studies by adding a counter that
accumulates the number of events wherein the water table rises above a specified depth
and remains above that threshold depth for a given duration during the growing season.
Wetland hydrology is defined as groundwater within 12 inches of the surface for 28
consecutive days (12.5% of the growing season), and 11 consecutive days (5% of the
growing season). Wetland hydrology is achieved in the model if target hydroperiods are
met for more than one-half of the number of years modeled (i.e., 16 out of 31).
Groundwater drainage contours are established on available mapping for various durations
of saturation within 1-foot of the soil surface (i.e. saturation contour for 0-5%, 5-12.5%,
and 12.5-20% of the growing season).
Model inputs for DRAINMOD simulations were obtained as follows: the United States
Department of Agriculture (USDA) soil texture classification, number of days in the
growing season (defined as March 26 - November 6), and hydraulic conductivity data
were obtained from the NRCS soil survey for Guilford County (USDA 1977). Inputs for
soil parameters such as the water table depth/volume, drained/upflux relationship, Green-
Ampt parameters, and water content/matric suction relationship were obtained utilizing

36

1 J1
the MUUF computer software developed by NRCS. Precipitation and temperature files
were obtained for the years 1930 through 1980 for Charlotte, North Carolina.
DRAINMOD simulations were run for Congaree soils, the dominant series within upper
reaches of the Site. Because Chewacla and Wehadkee map units are inundated by the
reservoir in lower reaches of the Site, DRAINMOD simulations were not considered
applicable within these future surface water driven wetlands.
Forested and maintained pasture conditions (evapotranspiration rates) were modeled. The
simulations were run for six channel inverts (0, 1, 2, 4, 6, and 8 feet) and at various target
hydroperiods during the growing season. Table 3 provides a depiction of the groundwater
discharge zone of influence by invert depth (elevation below floodplain). For example, a
stream channel invert 4 feet below the forested floodplain elevation is modeled as
reducing surface hydroperiods below 5% of the growing season at a distance of 145 feet
from the channel in a Congaree soil. A forested floodplain surface 6 feet in elevation
above the channel invert and greater than 195 feet from the channel is projected to
13
support wetlands.
ESC interpreted the groundwater drainage model based upon channel depth (based on
measured cross-sections), and floodplain elevation (based on topographic maps). Model
parameters were set to predict the average annual duration in which groundwater remains
within 1-foot of the soil surface at assigned elevations above a channel invert or in-stream
structure. The floodplain elevations outside of the groundwater drainage contour and at
the modeled channel depth were judged to be wetlands. Draft mapping of areas
potentially supporting wetlands was prepared based on available topographic mapping.
DRAINMOD simulations were designed to predict the transition zone from Congaree soils
to Wehadkee soils based on groundwater drainage conditions within a relatively flat
floodplain surface. Congaree soils represent a nonhydric (nonwetland), well drained soil
that is common on stream terraces immediately adjacent to streams. The Wehadkee series
comprises hydric (typically wetland), poorly drained soils that are typical in backwater
floodplain areas situated further from drainageways.
Post-Restoration Model Applications and Results
For groundwater wetland restoration, the primary objectives of this project include: 1)
reduce channel incision along Hickory Creek and associated tributaries; 2) elevate the
groundwater gradient into the rooting zone for developing vegetation; and 3) establish
minimum wetland hydroperiods encompassing 5% of the growing season, which are
typical for riverine wetlands in the Piedmont hydrophysiographic province. Therefore, the
effective post-project depths of the Hickory Creek channel will be reduced from an
average of 6 feet under existing conditions to gradients between 1 to 3 feet below the
floodplain.
P11
37

r
, lir.

u
TABLE 3
Modeled Groundwater Discharge Zone of Influence on Wetland Hydroperiod
Congaree Soil
Floodplain Groundwater Number of Groundwater Number of
Elevation Above Discharge Zone of Years Discharge Zone of Years
Channel Invert / Influence2 Wetland Influence Wetland
Weir Height' (feet) Criteria Met (feet) Criteria Met
(feet) (Surface (Surface
Hydroperiods Hydroperiods <
<5% of the 12.5% of the
growing season) growing season)
Forested Conditions
(relatively high surface water storage and rooting functions)
0 ----- 27/31 ----- 19/31
1 55 16/31 UA3 14/31
2 90 17/31 UA 14/31
4 145 16/31 UA 14/31
6 195 16/31 UA 12/31
8 215 16/31 UA 12/31
Fallow Field/Pasture Conditions
(relatively low surface water storage and rooting functions)
0 ----- 25/31 UA 6/31
1 120 16/31 UA 3/31
2 165 17/31 UA 3/31
4 240 16/31 UA 2/31
6 280 16/31 UA 2/31
8 305 16/31 UA 2/31
t: "Weir Height" is assumed to represent the effective depth (invert) of the drainage feature.
2: Discharge Zone of Influence is equal to %: of the modeled drainage spacing
3: UA = wetland criteria unachievable
u
7
19
DRAINMOD simulations modeled the zone of influence of the post project channel on
wetland hydroperiods within the primary floodplain. The maximum zone of influence may
be used to predict the area of groundwater wetland hydrological influence that may result
due the elevation of stream flow within the channel. In addition, the model provides an
estimate of the area that may continue to be affected in perpetuity by the stream channel
at a depth of 1 to 3 feet below the floodplain elevation.
Based on these simulations, the post-restoration channel is expected to continue to
effectively drain groundwater from the Congaree soil map unit which encompasses the
entire Site. Model simulations indicate that a series of in-stream weirs placed to within
1 foot of the adjacent floodplain elevation will not restore significant areas of wetlands.
Based on NRCS-MUUF parameters, Congaree soils exhibit relatively low vertical hydraulic
conductivity and rapid lateral flow within the upper soil profile. A channel invert 1 foot
below the adjacent stream terrace continues to effectively drain an area 120 feet adjacent
to the drainage feature. Gradual slopes in remaining portions of the outer floodplain are
projected to continue draining towards the modified stream channel. Therefore, in-stream
weirs do not provide a viable option for wetland restoration use based on the groundwater
model. To create wetlands within upper reaches of the Site, greentree impoundments will
be required to elevate the groundwater surface above the floodplain elevation
(immediately adjacent to the channel) periodically throughout the year.
4.5 REFERENCE GREENTREE IMPOUNDMENTS
Established greentree impoundments within the Piedmont of North Carolina were visited
to measure wetland attributes, review various structural designs, and to discern
management strategies employed. Reference systems include the Beaver Creek greentree
impoundment above Jordan Lake in Wake and Chatham Counties, the Little Creek
impoundment to Jordan Lake in Durham County, the Rocky Branch impoundment above
Falls Lake in Wake County, and the Country Line Creek impoundments in Caswell County.
These impoundments have typically been located above water supply reservoirs in the
region primarily to replace wetland habitat inundated by the reservoir, provide waterfowl
habitat, and to control sedimentation.
Controllable weirs range from concrete dams and electronic sluice gates on larger
tributaries to corrugated metal pipe using flash-board risers on smaller systems. The
associated dams typically consist of an earthen causeway with rip-rapped emergency
spillways and erosion control areas. Dams likely to be overtopped within watersheds
greater than 10 square miles have often been reinforced with concrete materials placed
on the earthen dam.
0
39

A
Figure 12 provides a conceptual depiction of a typical weir and dam for greentree
impoundments within watersheds ranging from 2 to 7 square miles. The weir consists of
two, 4-foot wide slots with wooden flash-board risers used to control the water surface
elevation. For this application, the flash boards could be completely removed to provide
13
for existing channel flows during summer months, planting periods, or for other
management purposes. Subsequently, the boards may be installed during the winter
and/or early part of the growing season to establish wetland hydrology behind the
impoundment. The type or size of the weir used at the Hickory Creek Site may be
modified during the engineering design phase based upon watershed size, projected
discharge/velocities on the structure, potential for stability, cost, constructability, and/or
management concerns.
A profile of the Country Line Creek impoundment in Caswell County was measured to
evaluate wetland development relative to the dam height, typical winter weir height,
summer weir height, and valley slope. Figures 13 and 14 provide a depiction of the
greentree impoundment and lake shoreline reference characteristics, including vegetation
development patterns relative to water surface elevations. Within the reference greentree
impoundments, stream channels have been obscured due to alluvial sediment deposition
and vegetation development patterns. The stream channel has been altered to the extent
that wetland characteristics typically occupy the entire impoundment land area, up to the
water surface elevation established during winter months.
4.6 REFERENCE PLANT COMMUNITIES
In order to establish a forested wetland system for mitigation purposes, a reference
community needs to be established. According to Mitigation Site Classification (MiST)
guidelines (EPA 1990), the area of proposed restoration should attempt to emulate a
Reference Forest Ecosystem (RFE) in terms of soils, hydrology, and vegetation. In this
case, the target RFEs were composed of steady-state woodlands in the region that have
sustained loading of fluvial sediments on floodplains in the past. However, forest
canopies have developed on these reference sites which support soil, landform, and
hydrological characteristics that restoration will attempt to emulate.
All of the RFE sites have been impacted by sediment deposition, selective cutting or high-
grading, channel migration/disturbances, and relatively high energy flood events.
Therefore, the species composition of these plots should be considered as a guide only.
Reference forest data used in restoration was modified to emulate steady state community
structure as described in the Classification of the Natural Communities of North Carolina
(Schafale and Weakley 1990).
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Two regional reference sites were selected within floodplains along the Rocky River in
Cabarrus County, North Carolina. Floodplains associated with this river system have
aggraded over the past century, inducing braided channel configurations and accelerated
sediment deposition within reference feeder tributaries. However, the 16 plots have been
placed within relatively mature bottomland hardwood/swamp forests that have developed
on accreted sediment.
The reference vegetation samples are designed to characterize the plant communities
proposed for restoration. Circular, 0.1-acre plot sampling was utilized to establish base-line
vegetation composition and structure in reference areas. Species were recorded along
with individual tree diameters, canopy class, and dominance. From collected field data,
importance values (Brower et al. 1990) of dominant canopy and mid-story trees were
calculated. The composition of shrub/sapling and herb strata were recorded and identified
® to species (Table 4 and Table 5).
At Site 1 (Table 4), the forest canopy is dominated by green ash, (Importance value [IV]
28%), sweetgum (IV 19%), American elm (Ulmus americans) (IV 11 %), box elder (IV 8%)
and red maple (IV 7%). Canopy species with lesser importance include black willow,
slippery elm (Ulmus alata), river birch, tulip poplar, and water oak (Quercus nigra).
Understory trees include flowering dogwood, ironwood, and sugarberry (Celtis laevigata).
A developed shrub layer is not generally present. Herbs include Nepal microstegium,
violets (Viola spp.), asters (Aster sp.), and river oats (Chasmanthium latifolium).
At Site 2 (Table 5), the forest canopy is dominated by green ash, (IV 39%), box elder (IV
22%), American elm (IV 12%), and swamp chestnut oak (IV 6%). Portions of the canopy
at RFE locations were also dominated by ironwood, overcup oak (Quercus lyrata),
sugarberry, sweet gum, red maple, black willow, slippery elm, water oak, and river birch.
The shrub/sapling layer is characterized by the non-native Chinese privet (Ligustrum
chinensis), paw-paw (Asimina triloba), and shade tolerant canopy species. Herbaceous
species include Japanese honeysuckle (Lonicera japonica), blackberry, muscadine, common
greenbriar, sedges (Carex spp.), and poison ivy.
Piedmont swamp forests are communities located in depressional areas, along toe slopes,
and at the confluence of alluvial valleys, where lateral flow is restricted. These sites are
hydrologically influenced by upland seeps and drainages, and by occasional riverine
flooding. Overstory species are dominated by flood-tolerant bottomland elements such
as sweetgum, American elm, willow oak (Quercus phe/%s), swamp chestnut oak, green
ash, overcup oak, and swamp cottonwood (Populus heterophylla). Wetter sites may
provide a broken to open canopy providing enough light for development of a dense
herbaceous/shrub layer. Species found on these sites may include button-bush
(Cephalanthus occidentalis), elderberry (Sambucus canadensis), silky dogwood, false
nettle (Boehmeria cylindrica), sedges (Carex spp), rushes (Juncus spp.), and lizard's tail
(Saururus cernuus). Giant cane (Arundinaria gigantea) is prevalent in places.
44
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4.7 REFERENCE PHYSIOGRAPHY AND SURFACE TOPOGRAPHY
Surface features were mapped within reference Piedmont swamp/bottomland hardwood
forest in order to establish base-line topographic conditions for restoration planning use.
This community lies within a seasonally to semi-permanently inundated area that has
supported sediment accretion in the past with inundation from stream flows occurring on
a frequent basis. The channel is actively migrating across aggrading floodplain, similar to
conditions that may be induced in a greentree impoundment over time.
Topographic maps of the accretion area were prepared to 0.5-foot contour intervals by
laser level and tape measure. Abandoned stream channels were mapped along with
approximate jurisdictional wetland extent relative to the water surface within stream
channels. A plan view, cross-sections, and profiles were generated for the channel and
adjacent alluvial surface. The channel dimension, rate of channel migration, and slope of
the floodplain floor represent the primary features extrapolated for use in restoration
planning. The objective of restoration is to reduce the effective size of the Hickory
channel to induce sediment deposition, channel migration, braiding, ponding, and/or
anastomosed stream types above the water supply reservoir.
Figure 15 depicts a plan view and cross-sections of the alluvial fan, including locations of
abandoned channels that have developed over the last several years. The channel exhibits
active migration across the valley floor as aggradation processes elevate isolated portions
of the floodplain. The active channel is classified as an E5 (highly sinuous) stream type
in upper reaches of the reference site. Subsequently, the channel transitions into an
anastomosed (DA5-6) channel and subsequent braided (D6) channel immediately prior to
the confluence with a near-permanently inundated section of the reference reach. This
braided reach and near-permanently inundated area represents projected conditions within
the transition zone into the reservoir conservation pool. The floodplain throughout this
reference reach continues to support forest vegetation, including shrub-scrub dominated
communities within the potentially inundated areas.

47
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5.0 WETLAND RESTORATION PLAN
This restoration plan has been designed to establish wetlands along the periphery of the
reservoir pool through planting of lake effect wetland areas and through construction of
a greentree impoundment immediately above the reservoir pool. The lake effect wetlands
are projected to reside between floodplain elevations of 681 feet to 684 feet above mean
sea level.
Immediately above the lake effect wetlands, a greentree impoundment is proposed to
extend contiguous wetland presence to floodplain elevations ranging from 684 feet to 687
feet above mean sea level. The greentree impoundment is expected to facilitate the
establishment of emergent, shrub, and forested wetlands. In general, a green tree
impoundment comprises a floodplain levee and controllable outlet structure. The
elevation of the outlet is raised during winter months to promote ponding, sediment
deposition, and wetland habitat. Subsequently, the elevation of the outlet is lowered in
early spring to allow for vegetation growth, nutrient uptake, and seedling establishment.
A management plan has been prepared (Section 8.0) for long term maintenance of these
systems over the life of the Randleman Reservoir. Management techniques for greentree
impoundments surrounding the reservoir will be managed according to constructs outlined
in the U.S. Army Corp of Engineer's, Greentree Reservoir Management Handbook (Mitchell
and Newling 1986).
Components of this plan have been established based on reference wetland studies
described in Section 4.0. This effort will be performed by: 1) passively
saturating/inundating surfaces associated with the reservoir conservation pool; 2)
installing sediment control check dams within dredged channels at the reservoir pool
elevation; 3) installing a controllable weir and dam; 4) scarifying pastured surfaces for
reforestation; 5) distributing woody debris into formerly cleared and pastured areas; and
6) planting of target wetland tree species in the area. Monitoring of wetland development
will be performed to track successional characteristics of the Site and to verify wetland
restoration success.
5.1 PASSIVE SATURATION / INUNDATION FROM THE RESERVOIR POOL
Based on reference studies within existing water supply reservoirs in the region, wetlands
are projected to develop on surface elevations ranging from a minimum of 1 foot below,
to 2 feet above the conservation pool (681-684 feet above MSL). As depicted in Figure
1 1, shrub/scrub and submerged aquatic vegetation is projected to develop on surfaces
t ranging between 681 and 682 feet above MSL, encompassing approximately 3.5 acres of
land area. This land area is expected to expand into open water portions of the Site over
time as sediment accretion occurs within the reservoir pool (below existing elevations of
681 feet above MSL). However, restoration plans are designed to delay this accretion in
favor of alluvial deposition within a greentree impoundment.
7
49
4
n4d
Based on reference studies, elevations between 682 and 684 feet above MSL will passively
develop shrub-scrub, bottomland hardwood, and bottomland swamp forest wetlands.
This area encompasses approximately 11 acres within central to lower portions of the Site
(Figure 11). These areas will be planted with tree species likely to replace existing
elements as wetland hydrology begins to dominate the area (Section 5.6). Active wetland
restoration will be initiated immediately above wetlands passively restored by the
conservation pool. Because restoration design is dependent upon initial establishment of
backwater conditions in Hickory Creek, construction activities associated with controllable
weirs and dams should be performed concurrent with filling of the reservoir.
5.2 SEDIMENT CONTROL CHECK DAMS
Rock check dams will be installed within the dredged and straightened stream channel to
reduce sediment transport capacity and to increase sediment storage potential within the
Site. As depicted in Figure 16, four rock check dams are proposed within the lake effect
wetland area (D1 to D4) with top elevations ranging from 680 feet to 682 feet above
mean sea level. These check dams will reside at or under the reservoir pool when water
surfaces reside at the conservation pool elevation of 682 feet. However, these check
dams will reduce erosional forces and sediment transport potential when reservoir pool
levels are below 682 feet. The sediment and associated pollutants deposited within the
dredged stream system will exhibit greater potential to remain on-site during drought
® periods and low lake levels.
The check dams will be constructed of relatively large rip-rap material placed to within 1-
foot of the adjacent floodplain elevation. The dam will span the 10-foot to 30-foot width
of the dredged channels with a minimum 2:1 side slopes in the upstream and downstream
direction. The check dams will be installed after forest clearing activities have been
completed within the reservoir conservation pool and immediately prior to filling of the
reservoir.
5.3 IMPOUNDMENT / WEIR CONSTRUCTION
One greentree impoundment structure will be constructed within the Site, as depicted in
Figure 16. The impoundment has been placed within a confined location on the valley
floor at the 684-foot contour depicted on topographic mapping. A more accurate
placement of this structure can be achieved by observing actual water surface elevations
in the channel resulting from the established conservation pool. Subsequently, the weir
would be accurately placed 2 feet above the conservation pool water surface.
Figure 12 provides a conceptual depiction of the proposed impoundment structure
including target elevations for the winter water surface and embankment height. The
design or placement of these impoundments may be modified during the engineering
design phase based on potential stability, constructability, cost, or other constraints.
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5.4 SURFACE SCARIFICATION
Before wetland community restoration is implemented, pasture lands will be scarified
(Figure 16). The scarification will be performed as linear bands directed perpendicular to
land slope (surface water flows). After scarification, the soil surface will exhibit complex
microtopography ranging to 0.5 feet in vertical asymmetry across local reaches of the
landscape. Restored microtopographic relief is considered critical to short term hydrology
restoration efforts. Therefore, multiple passes along each band are recommended to
ensure adequate surface roughing and surface water storage potential across the Site.
Subsequently, community restoration will be initiated on scarified wetland surfaces.
5.5 WOODY DEBRIS DEPOSITION
Re-introduction of woody debris represents an important component of wetland
restoration on pastoral lands. Woody debris, including downed trees, tip mounds, snags,
and decomposing material represents important habitat elements for wetland dependent
wildlife. However, the restoration areas on pasture land will not be capable of providing
coarse, woody habitat elements for up to 50 years after re-planting. Therefore, woody
material generated from embankment construction or other activities on the property will
be distributed across future wetland surfaces to the extent feasible. The material may be
lifted or pushed from adjacent windrows or forest areas as well.
5.6 WETLAND COMMUNITY RESTORATION
Restoration of wetland forested communities provides habitat for area wildlife and allows
for development and expansion of characteristic wetland dependent species across the
landscape. Ecotonal changes between community types contribute to diversity and
provide secondary benefits such as enhanced feeding and nesting opportunities for
mammals, birds, amphibians, and other wildlife.
RFE data, on-site observations, and ecosystem classification has been used to develop the
species associations promoted during community restoration activities. Target plant
1 community associations include: 1) bottomland hardwood / swamp forest and 2) scrub-
shrub / swamp forest.

n
f
Planting Plan
The planting plan consists of: 1) acquisition of available wetland species; 2)
implementation of proposed surface topography improvements; and 3) planting of
selected species on-site. Figure 17 depicts the locations targeted for planting,
encompassing 18.6 acres of land area. Planted species names by community are listed
below.
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1. Cherrybark Oak (Quercus pagoda)
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3. Overcup Oak (Quercus lyrata)
Willow Oak (Quercus phellos)
4. Swamp Chestnut Oak (Quercus michauxii)
5. Swamp Cottonwood (Populus heterophy/la)
6. Shagbark Hickory (Carya ovata)
7. Bitternut Hickory (Carya cordiformis)
8. Green Ash (Fraxinus pennsylvanica)
9 American Elm (Ulmus americana)
10
11. Winged Elm (Ulmus alata)
Tulip Poplar (Liriodendron tulipifera)

Scrub-Shrub / Swamp Forest
1 . Black Willow (Salix nigra)
2. Possum-haw (flex decidua)
3. Carolina holly (flex ambigua)
4. River Birch (Betula nigra)
5. American Sycamore (Platanus occidentalis)
6. Green Ash (Fraxinus pennsylvanica)
7. American Elm (Ulmus americana)
8.
9. Swamp Cottonwood (Populus heterophylla)
Overcup Oak (Quercus lyrata)
10. Swamp Chestnut Oak (Quercus michauxir)
11. Silky Dogwood (Corpus amomum)
12. Button-bush (Cephalanthus occidentalis)
13. Elderberry (Sambucus canadensis)
14. Tag Alder (Alnus serrulata)
Species selected for planting will be dependent upon availability of local seedling sources.
Advanced notification to nurseries (1 year) may facilitate availability of various non-
commercial species. In full planting areas (existing agricultural land), bare-root seedlings
of tree species will be planted within specified areas at a density of 680 stems per acre
(8-foot centers). Existing forest areas will receive supplemental planting to re-introduce
diagnostic tree elements at a density of 170 stems per acre (16-foot centers). The total
number of stems and species distribution within each planting area are depicted in Table
6.
is
54
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[I
hill TABLE 6

Planting Plan

Vegetation Association
(Planting area)
Shrub-Scrub/
Swamp Forest Qottomland
Hardwood/
Swamp Forest
(full planting) Qottomland
Hardwood/ Swamp Forest

(supplemental
planting)
TOTAL STEMS
PLANTED
Stem Target (trees/ac) 680 680 170 -----
Area (acres) 5.8 4.2 8.6 18.6
SPECIES # planted
(% total) # planted
(°,'o total) # planted
(% total) # planted
(% total)
River Birch 400(10) 400
Silky Dogwood 400(10) 400
Button-bush 400(10) 400
Elderberry 400(10) 400
Tag Alder 400(10) 400
Black Willow 200(5) 200
Possum-haw 200(5) 200
Carolina Holly 200(5) 200
American Sycamore 200 (5) 200
Swamp Cottonwood 400(10) 300(10) 150(10) 850
American Elm 200(5) 150 (5) 100(5) 450
Green Ash 200(5) 150 (5) 100(5) 450
Swamp Chestnut Oak 200(5) 300(10) 15000) 650
Overcup Oak 200 (5) 30000) 150 (10) 650
Cherrybark Oak 300 (10) 150 (10) 450
Willow Oak 300(10) 150(10) 450
Shagbark Hickory 300 (10) 150 (10) 450
Bitternut Hickory 300 (10) 150 (10) 450
Winged Elm 30000) 15000) 450
Tulip Poplar 300 (10) 150 (10) 450
TOTAL 4000 3000 1550 8550
Some non-commercial elements may not be locally available at the time of planting.
The stem count for unavailable species should be distributed among other target
elements based on the percent (%) distribution. One year of advance notice to forest
nurseries will promote availability of some non-commercial elements. However,
reproductive failure in the nursery may occur.
2: Scientific names for each species, required for nursery inventory, are listed in the
mitigation plan.
U2J

Planting will be performed between December 1 and March 15 to allow plants to stabilize
during the dormant period and set root during the following spring season. Opportunistic
species, which typically dominate early- to mid-successional forests have been excluded
from initial plantings on interior floodplains. Opportunistic species such as sweetgum, red
maple, and loblolly pine may become established. However, to the degree that long term
species diversity is not jeopardized, these species should be considered important
components of steady-state forest communities. Planting of opportunistic species such
as black willow will be targeted as stabilization elements in erosion control areas
immediately adjacent to the creek.
The planting plan is the blueprint for community restoration. The anticipated results
stated in the regulatory success criteria (Section 6.0) may reflect vegetative conditions
achieved after steady-state forests are established over many years. However, the natural
progression through early successional stages of floodplain forest development will prevail
regardless of human interventions over a 5-year monitoring period. In total, approximately
8,550 seedlings will be planted during wetland community restoration efforts.

56
V a?
{

6.0 MONITORING PLAN
The Monitoring Plan will entail analysis of the restoration area according to jurisdictional
wetland criteria (DOA 1987). Monitoring will include the observation and evaluation of
three primary parameters including hydrology, soil, and vegetation. Monitoring of
restoration efforts will be performed for 5 years or until success criteria are fulfilled.
6.1 HYDROLOGY
After hydrological modifications are performed, surficial monitoring wells will be designed
and placed in accordance with specifications in U.S. Corps of Engineers', Installing
Monitoring Wells/Piezometers in Wetlands (WRP Technical Note HY-IA-3.1, August 1993).
Monitoring wells will be set to a depth of up to 24 inches below the soil surface to track
water surface elevations in the impoundment relative to the weir height. All screened
portions of the well will be buried in a sand screen, filter fabric, and/or a bentonite cap
to prevent siltation during floods. Recording devices (if used) will be placed five feet
above the ground elevation. Placement of recording devices at this height should guard
against over topping for a projected 50-year flood elevation. The well will be stabilized
from flood shear by reinforcing steel bar (re-bar).
Six monitoring wells will be installed in restoration areas to provide representative
coverage throughout the Site. Approximate well locations are depicted in Figure 18.
Hydrological sampling will be performed during the growing season (March 26 to
November 6) at intervals necessary to satisfy the hydrologic success criteria. In general,
the wells will be sampled weekly through the spring and early summer and intermittently
through the remainder of the growing season, if needed to verify success.
6.2 HYDROLOGY SUCCESS CRITERIA
Target hydrological characteristics have been evaluated using regulatory wetland
hydrology criteria. The regulatory wetland hydrology criterion requires saturation (free
water) within one foot of the soil surface for 5% of the growing season under normal
climatic conditions.
Success Criteria
Under normal climatic conditions, hydrology success criteria comprises saturation (free
water) within 1 foot of the soil surface for a minimum of 5% of the growing season. This
hydroperiod translates to saturation for a minimum, 1 1-day (5 %) consecutive period during
the growing season, which extends from March 26 through November 6 (USDA 1977).
If wetland parameters are marginal as indicated by vegetation and hydrology monitoring,
a jurisdictional determination will be performed in the questionable areas.
0
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6.3 SOIL
Mitigation activities are expected to increase the deposition and transport of stream
sediments during overbank flood events. As a result, soils (Fluvaquents) are continuously
reworked by fluvial processes. Because iron reduction rates (gleying) a e not spatially or
temporally uniform on recent alluvial deposits, soil color or other v sual, hydric soil
properties are not considered suitable for quantitative wetland soil m nitoring/success
criteria on active floodplains.
Soil monitoring will entail measurement of sediment accretion/reduction (aggradation/
degradation) at the location of each monitoring well and other hydraulically active areas
as identified by Site managers. Mitigation activities are designed to provide for flood and
sediment storage from the watershed. Therefore, hydraulic and energy dissipation
patterns should be distributed throughout as much of the Site as possible. However, an
area of particularly accelerated sediment deposition may raise land surfaces above the
elevation of the primary wetland floodplain over a relatively short period of time.
Conversely, deep scour holes or head-cuts may form in locations where flow velocity or
sediment deficits exceed a "normal distribution." Soil monitoring is designed to provide
a cursory review to predict the need for additional site modifications if accelerated
deposition or scour potentially jeopardizes wetland restoration efforts.
The re-bar used to support monitoring wells will be marked upon installation and in each
monitoring year at the elevation of the existing ground surface. In addition, the height
of silt lines will be recorded to predict the depth of inundation during the flood period.
Additional re-bar will be placed and measured in high energy areas identified by Site
managers, as needed. The change in elevation of the alluvial surface and deposition/scour
patterns relative to flood elevations will be recorded and compared to previous years.
6.4 SOIL SUCCESS CRITERIA
Success criteria require that the deposition/scour rate not exceed over 1 foot change in
surface elevations in any given year. Any areas affected by this excessive deposition/scour
will be mapped in the field. The area will be reviewed to determine modifications to
drainage patterns that should be implemented, if any. Changes in surface elevations of
less than 1 foot per year will meet regulatory success criteria; however, modifications to
deposition / scour patterns may also be considered in certain circumstances.
6.5 VEGETATION
Restoration monitoring procedures for vegetation are designed in accordance with EPA
guidelines presented in MiST documentation (EPA 1990) and Compensatory Hardwood
Mitigation Guidelines (DOA 1993). The following presents a general discussion of the
monitoring program.
59
rill
41
L??
Vegetation will receive cursory, visual evaluation during periodic reading of monitoring
wells to ascertain the general conditions and degree of competition or overtopping of
planted elements. Subsequently, quantitative sampling of vegetation will be performed
once annually during the fall (September/November) for 5 years or until vegetation success
criteria are achieved. Sampling dates may be modified to accommodate flood events and
plot inundation, as needed.
During the first sample event, a visual survey will be performed in the reference wetlands
to identify all canopy tree species represented within target communities. These reference
tree species will be utilized to define "character tree species" as termed in the success
criteria.
Permanent (on each well head) or nonpermanent, randomly placed plots will be
established at representative locations in the restoration areas. Each plot will consist of
two, 300-foot transects extending at a randomly selected compass bearing from a central
origin. The plot width along the transect will extend 4 feet on each side of the tape,
providing a 0.11-acre plot sample at the location (600 feet x 8 feet / 43,560 square
feet/acre). Ten plots will be established to provide a 4% sample and a depiction of tree
species available for current and future seed sources within the restoration area. In each
plot, tree species and number of stems will be recorded and seedling/sapling/tree height
measured. Tree data from all plots will be combined into one database to calculate an
average density, by species, represented in restoration areas of the Site.
In each plot, presence/absence of shrub and herbaceous species will be recorded. A
n wetland data form (DOA 1987) will be completed to document the classification and
description of vegetation, soil, and hydrology.
6.6 VEGETATION SUCCESS CRITERIA
Success criteria include the verification, per the wetland data form, that each plot
Q supports a species composition sufficient for a jurisdictional determination. Additional
{ success criteria are dependent upon density and growth of "Character Tree Species."
"Character Tree Species" are identified through visual inventory of reference wetland
communities used to orient the restoration project design. All canopy tree species
identified in the reference wetland will be utilized to define "Character Tree Species" as
termed in the success criteria (Character Tree Species are generally listed in Section 4.6
and Section 5.5).
An average density of 320 stems per acre of Character Tree Species must be surviving in
the first three monitoring years. Subsequently, 290 stems per acre of character tree
species must be surviving in year 4, and 260 stems per acre of Character Tree Species in
year 5. Each individual species is limited to representing up to 20% of the 320 stem per
i
60
0
a
acre total. Additional stems of a particular species above the 20% threshold are discarded
{ from the statistical analysis. In essence, a minimum of five different character tree species
must be present with each species representing up to 20% of the 320 stem per acre total.
If vegetation success criteria are not achieved based on average density calculations from
combined plots over the entire restoration area, those individual plots that do not support
the stem per acre requirement and the representative area will be identified. Supplemental
planting will be performed in the identified area as needed until vegetation success criteria
are achieved.
No quantitative sampling requirements are proposed for herb assemblages. Development
of a forest canopy over several decades and restoration of wetland hydrology will dictate
success in migration and establishment of desired wetland understory and groundcover
populations.
6.7 REPORT SUBMITTAL
An Annual Wetland Monitoring Report (AWMR) will be prepared at the end of each
monitoring year (growing season). The AWMR will depict the sample plot and quadrant
locations and include photographs which illustrate site conditions. Data compilations and
analyses will be presented as described in Sections 6.1 through 6.6 including graphic and
tabular format, where practicable. Raw data in paper or computer (EXCEL) file format will
be prepared and submitted as an appendix or attachment to the AWMR.
a
61

0
0 7.0 IMPLEMENTATION SCHEDULE
Project implementation will include performance of restoration work in three primary
stages including: 1) impoundment /weir construction and site preparation; 2) tree and
shrub planting; 3) monitoring plan implementation; and 4) management program
M implementation. This mitigation plan or implementation schedule may be modified based
upon civil design specifications, permit conditions, or contractor limitations.
Stage 1: Impoundment / Weir Construction and Site Preparation
Stage 1 will be performed concurrent with or subsequent to filling of the reservoir. Rock
check dams and the greentree impoundment will be installed at the designated locations.
This work will be performed during late spring and/or early summer months to reduce
erosion hazards associated with saturated soil or large August storms. Site preparation,
including debris removal, woody debris deposition, and scarification will be performed
during the same summer period, prior to tree planting.
Stage 2: Tree Planting
Tree and shrub planting will be performed the first winter after Stage 1 is complete. The
seedlings will be planted during the winter dormant period, prior to March 1.
Stage 3: Monitoring Plan Implementation
Monitoring wells and permanent vegetation plots will be established immediately after
construction and planting activities are completed (prior to March 26, the start of the
growing season). The Site will be visited frequently to read monitoring wells and to
evaluate wetland development during the first growing season. Vegetation sampling and
hydrology monitoring will be completed by November 6 (the end of the growing season).
The first year of monitoring would be completed upon submittal of the Annual Wetland
Monitoring Report and fulfillment of success criteria. The monitoring sequence will be
repeated as described for four additional years or until success criteria are achieved.
Stage 4 Management Program Implementation
Green tree impoundments require active management throughout the life of the wetland
facility and water supply reservoir. Therefore, long-term management programs will be
required to ensure that wetland development is established and maintained. The
management program will be implemented concurrent with the monitoring plan as
described above. Constructs of the management program are described in the next
Section.
0
62
0
0
8.0 MANAGEMENT PROGRAM
Greentree impoundments require modification of water surface elevations on a regular
basis. Typically, the elevation of outlets is raised and lowered at variable times each year
to provide for development of target wetland vegetation. Wetland vegetation is typically
harvested and/or planted periodically to establish target vegetation patterns for waterfowl
or other wetland dependent wildlife. Invasive species such as Kudzu (Pueraria iobata) may
require systematic removal as well. For this project, outlet controls and vegetation
a maintenance must also be manipulated to promote forested wetland development within
the 29.4-acre Site. Target hydrological goals include soil saturation or inundation for a
minimum of 5% of the growing season (March 26 to November 6). The 5% criterion must
be achieved in 50% of the years over the life of the Randleman Reservoir.
The Piedmont Triad Regional Water Authority (PTRWA) will provide the fiscal and
administrative resources necessary to maintain and manage the greentree impoundments
over the life of the water supply reservoir. PTRWA will make provisions for establishment
r"I
t" I of an Environmental Compliance Officer (Officer) to serve as the primary administrator and
authority over the greentree impoundments. The Officer will be under control of PTRWA
while PTRWA continues to manage the property. If the property is deeded to a resource
agency as described in Section 9.0, the resource agency will provide resources necessary
for establishment and maintenance of the Officer.
The Officer will be tasked to supervise, coordinate, monitor, and manipulate the greentree
impoundments throughout the life of the water supply reservoir. The Officer will
coordinate and implement, in consultation with qualified wildlife biologists, the following
greentree impoundment management components as described in the U.S. Army Corps
of Engineer's, Greentree Reservoir Management Manual (Mitchell and Newling 1986).
1) The Officer will be responsible for raising and lowering the controllable weirs
at a frequency and duration needed to establish wetland hydrology and
maximize development of wetland vegetation. Target vegetation patterns
include establishment of tree species to the maximum extent feasible.
2) The Officer will periodically visit the Site to visually assess waste debris
dumping, erosion problems, debris jams on structures, vegetation patterns,
and other aspects of wetland development. The Officer will repair identified
problems to ensure continued functioning of the wetland.
3) The Officer will provide for periodic quantitative sampling of vegetation to
ensure that target vegetation species are developing and being replaced
within the impoundments. The results of vegetation samples will be used
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by the Officer to adjust the frequency and/or duration that the controllable
weirs are raised or lowered and to order and plant vegetation elements as
needed.
4) The Officer will submit an annual report to the responsible resource agency
summarizing the dates of weir modification, the current vegetation sample,
trends in vegetation patterns, and recommendations for weir modifications
over the next monitoring weir. The report will also include
recommendations for structural modifications or additional plantings, as
needed. These reports will be prepared and submitted on annual basis over
the life of the Randleman Reservoir Water Supply.
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9.0 DISPENSATION OF PROPERTY
PTRWA will maintain ownership of the property until all mitigation activities are
completed and the site is determined to be successful. Although no plan for dispensation
of the Site has been developed, PTRWA may continue to manage the property or may
deed the property to a resource agency (public or private) capable of managing the
greentree impoundments over the life of the reservoir. The resource agency will be
approved by the appropriate regulatory agencies. Covenants and/or restrictions on the
deed will be included along with adequate fiscal resources to ensure adequate
management and protection of the Site throughout the life of the reservoir.

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a 10.0 WETLAND FUNCTIONAL EVALUATIONS
Mitigation activities at the Hickory Creek Mitigation Site should be determined based on
wetland functions generated and a comparison of restored functions to potentially
impacted wetland resources. Therefore, an evaluation of mitigation wetlands by
physiographic area is provided to evaluate site utility for mitigation in the region.
10.1 EXISTING CONDITIONS
Under existing conditions, hydrodynamic functions have been degraded or effectively
eliminated due to stream entrenchment, bed/bank erosion, soil leveling/compaction in
pasture areas, and removal of characteristic vegetation. Features which depict
performance of hydrodynamic wetland functions such as surface microtopography,
seasonal ponding, meandering stream channels, and characteristic wetland vegetation
have been effectively eliminated by alternative land uses on the stream terrace. Reduction
or elimination of wetland hydrology has also negated nutrient cycling and biological
functions within the complex. These former wetlands do not support natural communities
adapted to wetlands or the wetland dependent wildlife characteristic in the region.
10.2 PROJECTED, POST-RESTORATION CONDITIONS
Lake Effect Wetlands
Wetland restoration objectives have been adapted for this project due to location of the
Site relative to the Randleman Reservoir. The lower half of the Site will be directly
influenced by the reservoir conservation pool, including sediment deposition within stream
channels, development of accreting sediment bars, and establishment of wetlands on
saturated/inundated surfaces. Based on reference studies, these lake effect wetlands are
projected to support a mosaic of emergent, shrub-scrub, and forested wetland
communities on land surfaces from 1 foot below to 2 feet above the conservation pool.
This land area, comprising approximately 14.5 acres (Figure 11), will provide wetland
functions such as increased habitat for wetland dependent wildlife, sediment retention
above the water supply, and pollutant processing on vegetated wetland surfaces. Open
water is also projected to encompass approximately 4.4 acres within the lake effect
wetland that will provide for sediment storage and accreting wetland shorelines (Figure
18).
Q Monitoring and management of these lake effect wetlands will assist in ensuring that land
surfaces exposed to long-term sedimentation are not elevated above the water table, with
capacity to support wetland functions subsequently reduced or diminished over time. In
addition, efforts to maintain vegetation within rapid sedimentation or inundated areas will
also be employed during the monitoring period.
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Greentree Impoundments
The upper half of the Site will be used to extend the sediment deposition wedge
associated with the reservoir and to establish wetland communities capable of providing
wildlife habitat and water quality benefits. The greentree impoundment is projected to
provide for restoration of regular overbank flood events and filling of the entrenched
channel with sediment over time. As a result, the floodplain areas are expected to support
an array of emergent, shrub-scrub, and forested wetland communities, providing
replacement of habitat for wetland dependent species displaced by the reservoir. Water
quality benefits are projected to include sediment retention and pollutant processing of
waters generated by the 8.7-square mile, urbanizing watershed.
Pro-active mitigation within the greentree impoundments is projected to provide
approximately 8.0 acres of wetland restoration / creation above the lake effect, wetland
restoration / creation area (an additional 14.5 acres). Therefore, 22.5 acres of wetland
restoration / creation, 2.5 acres of wetland preservation / enhancement, and 4.4 acres of
open water are potentially provided by the 29.4-acre Site (Figure 18).
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0
0 11.0 REFERENCES
Baumer, 0. and J. Rice. 1988. Methods to predict soil input data for DRAINMOD ASAE
Paper No. 88-2564. ASAE, St. Joseph, MI 49085.
Beets, C.P. 1992. The relation between the area of open water in bog remnants and
storage capacity with resulting guidelines for bog restoration. (in) Peatland Ecosystems
and Man: An Impact Assessment. (ed.) 0. M. Bragg, P. D. Hulme, H. A. P. Ingram, and
R.A. Robertson. International Peat Society. University of Dundee, Dundee, Scotland.
Belcher, H.W. and G.E. Merva. 1987. Results of DRAINMOD verification study for
Zeigenfuss soil and Michigan climate. ASAE Paper No. 87-2554. ASAE, St. Joseph, MI
49085.
Brinson M.M., F.R. Hauer, L.C. Lee, W.L. Nutter, R.D. Smith, D. Whigham. 1995.
Guidebook for Application of Hydrogeomorphic Assessments to Riverine Wetlands. U.S.
Army Corps of Engineers Waterways Experiment Station. Vicksburg, MS.
Brinson, M.M. 1993a. Changes in the functioning of wetlands along environmental
gradients. Wetlands 13(2): 65-74, Special Issue, June 1993. The Society of Wetland
Scientists.
Brinson M.M. 1993b. A Hydrogeomorphic Classification for Wetlands. Wetlands
Research Program Technical Report WRP-DE-4. U.S. Army Corps of Engineers Waterways
Experiment Station. Vicksburg, MS.
Brinson M., B. Swift, R. Plantico, J. Barclay. 1981 . Riparian Ecosystems: Their ecology
and status. U.S. Fish and Wildlife Service FWS/OBS 81 /17
Brower, J.E., J.H. Zar, C.N. von Ende. 1990. Field and Laboratory Methods for General
Ecology. William C. Brown Publishers, Debuque, IA.
Brown, Philip M., et al. 1985. Geologic Map of North Carolina, North Carolina
Department of Natural Resources and Community Development, 1-.500,000 scale.
Chang, Howard H. 1988. Fluvial Processes in River Engineering. John Wiley & Sons.
Department of the Army (DOA). 1993 (unpublished). Corps of Engineers Wilmington
District. Compensatory Hardwood Mitigation Guidelines (12/8/93).
0
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Department of the Army (DOA). 1987. Corps of Engineers Wetlands Delineation Manual.
Tech. Rpt. Y-87-1. US Army Engineer Waterways Experiment Station, Vicksburg, MS.
Division of Water Quality (DWQ). 1998. Classifications and Water Quality Standards
Assigned to the Waters of the Cape Fear River Basin, N.C. Department of Environment and
Natural Resources, Raleigh, N.C.
Division of Water Quality (DWQ). 2000 (draft). Cape Fear River Basinwide Water Quality
Plan. North Carolina Department of Environment and Natural Resources. Raleigh, N.C.
Division of Water Quality (DWQ). 1996. Water Quality Certification Administrative Code
Section: 15A NCAC 2H.0500 as amended October 1, 1996. North Carolina Department
of Environment and Natural Resources.
Dunne D. and L.B. Leopold. 1978. Water in Environmental Planning. W.H. Freeman and
Company, N.Y.
EcoScience Corporation (ESC). 1998a (unpublished). Preliminary Groundwater Drainage
Model: Randleman Reservoir Mitigation Sites, Guilford County, North Carolina. Raleigh,
N. C.
EcoScience Corporation (ESC). 1998b (unpublished). Preliminary Wetland Mitigation
Assessment: Randleman Reservoir, Guilford and Randolph Counties, North Carolina.
Raleigh, N.C.
EcoScience Corporation (ESC). 1999 (unpublished). Wetland Mitigation Plan: Randleman
Reservoir, Guilford and Randolph Counties, North Carolina. Raleigh, N.C.
Environmental Protection Agency (EPA). 1990. Mitigation Site Classification (MIST) A
Methodology to Classify Pre-Project Mitigation Sites and Develop Performance Standards
for Construction and Restoration of Forested Wetlands. USEPA Workshop, August 13-15,
1989. USEPA Region IV and Hardwood Research Cooperative, North Carolina State
University, Raleigh, NC.
Fouss, J.L., R.L. Bengtson and C.E. Carter. 1987. Simulating subsurface drainage in the
lower Mississippi Valley with DRAINMOD. Transactions of the ASAE 30 (6).(1679 -1688).
Gayle, G., R.W. Skaggs and C.E. Carter. 1985. Evaluation of a water management model
for a Louisiana sugar cane field. J. of Am. Soc. of Sugar Cane Technologists, 4: 18 - 28.
Graham County Historical Society, 1992. Graham County Heritage. Robbinsville, NC.
0
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0
Harman, W.A., G.D. Jennings, J.M. Patterson, D.R. Clinton, L.A. O'Hara, A. Jessup, R.
Everhart. 1999. Bankfull Hydraulic Geometry Relationships for North Carolina Streams.
N.C. State University, Raleigh, North Carolina.
Hvorslev, M.J. 1951. Time lag and soil permeability in groundwater observations. U.S.
Army Corps of Engineers Waterways Experimental Station Bulletin 36, Vicksburg, MS.
Keller, M.E., C.S. Chandler, J.S. Hatfield. 1993. Avian Communities in Riparian Forests
of Different Widths in Maryland and Delaware. Wetlands 13(2):137-144, Special Issue,
June 1993. The Society of Wetland Scientists.
Mitchell, W.A., and C.J. Newling. 1986. Greentree Reservoir Management Manual. U.S.
Army Corps of Engineers Waterways Experiment Station.
North Carolina Department of Transportation (NCDOT). 1994a; unpublished.
Determination of applicable mitigation credit For restoration of wetland buffers and
wetland/upland ecotones: US 64 wetland restoration and conservation management plan,
US 64 relocation, Martin and Edgecombe Counties, North Carolina. N.C. Department of
Transportation. Raleigh, N.C.
Nunnally, N.R.,E. Keller. 1979. Use of Fluvial Processes to Minimize Adverse Effects of
Stream Channelization. Water Resources Research Institute of the University of North
Carolina. Report No. 144.
Page, R.W. and L.S. Wilcher. 1990. Memorandum of Agreement Between the EPA and
the DOE Concerning the Determination of Mitigation Under the Clean Water Act, Section
404(b)(1) Guidelines. Washington, DC.
Rohde, F. C., R. G. Arndt, D. G. Lindquist, and J. F. Parnell. 1994. Freshwater Fishes of
the Carolinas, Virginia, Maryland, and Delaware. The University of North Carolina Press,
Chapel Hill, NC. 222 pp.
Rogers, J.S. 1985. Water management model evaluation for shallow sandy soils.
Transactions of the ASAE 28 (3): 785-790.
Rosgen, D. 1996. Applied River Morphology. Wildland Hydrology (Publisher). Pagosa
Springs, Colorado.
Schafale, M. P., A.S. Weakley. 1990. Classification of the Natural Communities of North
Carolina: Third Approximation, NC Natural Heritage Program, Division of Parks and
Recreation, NC DEM, Raleigh NC.
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Schouwenaars, J.M. 1995. The selection of internal and external water management
options for bog restoration. (in) Restoration of Temperate Wetlands. (ed.) B. D. Wheeler,
S. C. Shaw, W. J. Fojt, and R. A. Robertson. John Wiley & Sons, Ltd. West Sussex,
England.
Simmons, C.E. 1976. Sediment Characteristics of Streams in the Eastern Piedmont and
Western Coastal Plain Regions of North Carolina. U.S. Geological Survey Water Supply
Paper, W 1798-0,p. 01-032. Reston Va.
Skaggs, R.W. 1982. Field Evaluation of a Water Management Simulation Model.
Transactions of the ASAE 25 (3), pp 666-674.
Skaggs, R.W., N.R. Fausey, B.H. Nolte. 1981. Water Management Evaluation for North
Central Ohio. Transactions of the ASAE 24 (4), pp 922-928.
Skaggs, R.W., J.W. Gilliam, R.O. Evans. 1991. A Computer Simulation Study of Pocosin
Hydrology. Wetlands (11), pp 399-416.
Skaggs, R.W., et al. 1993. Methods for Evaluating Wetland Hydrology. ASAE Meeting
Presentation Paper No. 921590. 21 p.
Smith, R.D., A. Ammann, C. Bartoldus, M.M. Brinson. 1995 (unpublished). An Approach
for Assessing Wetland Functions Using Hydrogeomorphic Classification, Reference
Wetlands, and Functional Indices. Wetlands Research Program Technical Report WRP DE-
US Army Engineer Waterways Experiment Station, Vicksburg, MS
Strahler, A.N. 1964. Geology. Part II. Quantitative geomorphology of drainage basins
and channel networks. (in) Handbook of Applied Hydrology. (ed. V.T. Chow), pp. 4-39
to 4-76, McGraw Hill, New York.
Susanto, R.H., J. Feyen, W. Dierickx, G. Wyseure. 1987. The Use of Simulation Models
to Evaluate the Performance of Subsurface Drainage Systems. Proc. of the Third
International Drainage Workshop, Ohio State University, OH. pp. A67 - A76.
U.S. Department of Agriculture (USDA). 1987. Hydric Soils of the United States. In
cooperation with the National Technical Committee for Hydric Soils, USDA Natural
Resource Conservation Service.
U.S. Department of Agriculture (USDA). 1977. Soil Survey of Guilford County, North
Carolina. Natural Resource Conservation Service.
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U.S. Department of Agriculture (USDA). 1970. Soil Survey of Wake County, North
Carolina. Natural Resource Conservation Service
U.S. Fish and Wildlife Service. 1994. Schweinitz's Sunflower Recovery Plan. Atlanta,
GA. 28 pp.
U.S. Fish and Wildlife Service (USFWS). 1988. Cape Fear Shiner Recovery Plan. U.S.
Fish and Wildlife Service, Atlanta, GA. 18 pp.
U.S. Geological Survey (USGS). 1974. Hydrologic Cataloging Unit Map for the State of
North Carolina.
U.S. Geological Survey (USGS). 1982. 7.5 minute, High Point East 1:24000 Quadrangle.
Yoakum, J., W.P. Dasmann, H.R. Sanderson, C.M. Nixon, and H.S. Crawford. 1980.
Habitat Improvement Techniques. Pp 329-403 in S.D. Schemnitz (Editor). Wildlife
Management Techniques Manual, 4th ed., rev. The Wildlife Society, Washington, DC
686 pp.
DETAILED WETLAND MITIGATION PLAN
RANDLEMAN RESERVOIR WATER SUPPLY
J
RICHLAND CREEK MITIGATION SITE
GUILFORD COUNTY, NORTH CAROLINA
Prepared for:
PIEDMONT TRIAD REGIONAL WATER AUTHORITY
Prepared by:
EcoScience
EcoScience Corporation
612 Wade Avenue, Suite 200
Raleigh, North Carolina 27605
October 2000
kii

TABLE OF CONTENTS
Page
G
LIST OF FIGURES ................................................ iii
LIST OF TABLES ................................................ iv
1.0 INTRODUCTION ............................................ 1
1.1 Purpose ............................................. 1
1.2 Objectives of Wetland Restoration .......................... 1
1.3 Primary Methods for Wetland Restoration ..................... 3
1.4 Mitigation Site Selection ................................. 4
2.0 METHODS ................................................ 8
3.0 EXISTING CONDITIONS ...................................... 11
3.1 Physiography, Topography, and Land Use ..................... 11
3.2 Soils ...............................................15
3.3 Plant Communities ..................................... 17
3.4 Hydrology ...........................................19
3.5 Water Quality ......................................... 23
3.6 Wildlife .............................................24
3.7 Unique Natural Areas and Protected Species ................... 25
3.8 Jurisdictional Wetlands .................................. 26
4.0 WETLAND RESTORATION STUDIES .............................. 29
4.1 Restoration Alternatives Analyses ........................... 29
4.2 Reservoir Pool Level and Sedimentation Analysis ................ 31
4.3 Surface Water Analyses ................................. 36
4.4 Groundwater Modeling .................................. 41
4.5 Reference Plant Communities .............................. 45
4.6 Reference Physiography and Surface Topography ................ 49
5.0 WETLAND RESTORATION PLAN ................................ 51
5.1 Passive Saturation / Inundation from the Reservoir Pool ........... 51
5.2 Constructed Levee Removal ............................... 51
5.3 In-Stream Weir Construction .............................. 53
5.4 Surface Scarification .................................... 55
5.5 Woody Debris Deposition ................................ 55
5.6 Wetland Community Restoration ........................... 55

6.0 MONITORING PLAN ......................................... 62
6.1 Hydrology ...........................................62
6.2 Hydrology Success Criteria ............................... 62
6.3 Soil ................................................64
6.4 Soil Success Criteria .................................... 64
6.5 Vegetation ........................................... 64
6.6 Vegetation Success Criteria ................................ 65
6.7 Report Submittal ...................................... 66
7.0 IMPLEMENTATION SCHEDULE ................................. 67
8.0 DISPENSATION OF PROPERTY ................................. 68
9.0 WETLAND FUNCTIONAL EVALUATION ........................... 69
9.1 Existing Conditions ..................................... 69
9.2 Projected Post-Restoration Conditions ........................ 69
10.0 REFERENCES ..............................................71
LIST OF FIGURES
Page
Figure 1: Site Location: Randleman Reservoir ......................... 2
Figure 2: Site Location: Richland Creek Mitigation Site ................... 7
Figure 3: Aerial Photograph (1999) ................................. 9
Figure 4: Physiography, Topography, and Land Use ..................... 12
Figure 5: Soil Map Units: Hydric / Non-Hydric Soil Boundaries .............. 16
Figure 6: Plant Communities ..................................... 18
Figure 7: Flood Frequency Analyses ................................ 21
Figure 8: Jurisdictional Wetlands .................................. 27
Figure 9: Pool Level and Sedimentation: Reference Site 1 ................. 34
Figure 10: Pool Level and Sedimentation: Reference Site 2 ................. 35
Figure 11: Pool Level and Sedimentation: Randleman Reservoir .............. 37
Figure 12: DRAINMOD Estimates: Post Project Conditions ................. 44
Figure 13: Reference Site: Plan View and Cross Sections .................. 50
Figure 14: Hydrology Restoration ................................... 52
Figure 15: Conceptual Channel Profile: Post-Project Conditions .............. 54
Figure 16: Target Landscape Ecosystems: Richland Creek Mitigation Site ....... 56
Figure 17: Target Landscape Ecosystems: Richland Creek Mitigation Site ...... 57
Figure 18: Planting Plan ......................................... 59
Figure 19: Monitoring Plan / Mitigation Design Units ..................... 63
LIST OF TABLES
Paqe
Table 1: Estimated Acreage of Mitigation Design Units Based on Preliminary Studies
for 10 Potential Mitigation Sites Associated with the Randleman Reservoir
.................................................. 5
Table 2: Water Surface Elevation Estimates for Various Flood Frequencies ..... 39
Table 3: Modeled Groundwater Discharge Zone of Influence
on Wetland Hydroperiods: Chewacla / Wehadkee Soils ............ 43
Table 4: Reference Forest Ecosystem Plot Summary .................... 47
Table 5: Reference Forest Ecosystem Plot Summary .................... 48
Table 6: Planting Plan ......................................... 60
iv
L
DETAILED WETLAND MITIGATION PLAN
RANDLEMAN WATER SUPPLY RESERVOIR
RICHLAND CREEK MITIGATION SITE
GUILFORD COUNTY, NORTH CAROLINA
1.0 INTRODUCTION
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1.1 PURPOSE
The Piedmont Triad Regional Water Authority (PTRWA) proposes development of the
Randleman Reservoir in Randolph and Guilford Counties, North Carolina (Figure 1). The
purpose of this project is to develop a safe and dependable water supply source for North
Carolina's Piedmont Triad region that will satisfy the projected water demand for a period
of 50 years. The proposed 3,000-acre reservoir will unavoidably impact approximately 121
acres of wetlands through impoundment and establishment of an open water system.
These jurisdictional wetlands are subject to regulation under Section 404 of the Clean
Water Act (CWA) (33 U.S.C. § 1344).
For unavoidable wetland impacts, compensatory mitigation is required to facilitate no net
loss of wetland functions in the region. Compensatory mitigation is typically performed
to replace similar wetland types and wetland functions as those impacted (ex: forested,
stream-side wetlands). Wetland restoration, creation, enhancement, or preservation
represent typical methods designed to offset wetland impacts. The North Carolina
Division of Water Quality (DWQ) has instituted a policy that prefers a minimum of 1 acre
of wetland be restored or created for every acre of wetland impacted. Subsequently,
remaining wetland functional replacement needs may then be off-set through wetland
enhancement and/or preservation.
1.2 OBJECTIVES OF WETLAND RESTORATION
The primary objectives for wetland restoration include:
1) Restore or create 121 acres of wetlands as required under regulatory
guidance.
2) Assist in protecting the drinking water supply from pollutants discharged
from the developing watersheds. Excess nutrients, fecal coliform,
sediments, and chemical contaminants (metals, etc.) represent the primary
water quality concerns for the reservoir.
3) Maximize benefits to water quality through establishment of functioning
wetlands above the reservoir pool.
4) Replace habitat for wetland dependent wildlife displaced by establishment
n? of open water.
5)/ Maximize the acreage of wetland restoration or creation achieved at the
Richland Creek mitigation site.
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Water quality benefits are maximized by reducing the capacity for sediment to reach open
water within the reservoir pool. Entrenched streams in the region have abandoned
adjacent floodplains and tend to discharge large quantities of sediment within water
supply reservoirs (Section 4.3). Therefore, wetland restoration for water quality should
be designed to reduce sediment transport capacity of streams immediately above the
reservoir and to entrap sediment within vegetated wetland surfaces. As a result, sediment
would be deposited on floodplain surfaces that periodically dry out in areas outside of the
reservoir pool. Wetland vegetation would serve to provide nutrient uptake and recycling
functions within deposited sediment. Using this rationale, entrenched stream and terrace
systems would be converted into alluvial wetland fans. A highly sinuous (E) to braided
?U (D) stream system would be developed within the alluvial deposition area (Rosgen 1996).
Wetland vegetation would be established on the alluvial deposition to stabilize the
sediment and provide for pollutant recycling through oxidation (drying) and reduction
/? (wetting) processes. Within the reservoir immediately downstream of entrenched streams,
sediment from the watershed is deposited directly into the water supply, in a permanently
inundated, reducing environment. Without periodic oxidation processes, pollutants
generally dissolve within the water column and consequently reduce drinking water
quality.
Establishment of the reservoir will effectively stop sediment transport capacity within each
tributary that flows into the lake. The primary objective of mitigation is to extend the
sediment deposition wedge in the upstream direction of each valley, prior to confluence
with the lake. The reservoir will passively develop wetlands within a certain area in each
valley, immediately above the reservoir pool. This project is intended to assist that
process through active measures, including extension of wetlands in the up-valley
direction and establishment of wetland vegetation on active alluvial surfaces.
1.3 PRIMARY METHODS FOR WETLAND RESTORATION
Two primary methods for wetland restoration have been proposed to extend the sediment
wedge into design wetlands above the reservoir, restore 121 acres of riverine wetlands,
and to provide suitable habitat for wetland dependent wildlife. Primary methods include:
1) in-stream structures designed to reduce sediment transport capacity; and 2) greentree
impoundments designed to allow management of water levels and sediment deposition
patterns.
In-Stream Structures
In-stream structures are proposed primarily along dredged or entrenched stream corridors
on relatively low-slope valley floors (<0.009 rise/run) supporting forest vegetation.
Adjacent floodplains have been abandoned by the incised stream and converted to
elevated terraces not regularly exposed to overbank flooding or wetland hydrodynamics.
Properly designed in-stream structures are expected to reduce the degree of channel
incision, reduce the rate of groundwater discharge from the floodplain into the channel,
3

increase overbank flooding from the channel onto the floodplain, reduce sediment
transport capacity, and provide greater sediment deposition within vegetated wetlands.
Greentree Impoundments
Greentree impoundments are proposed on more steeply sloped floodplains and stream
terraces (>0.008 rise/run) or pastured sites where relatively severe stream channel
degradation and steepening has occurred above the reservoir pool. In general, a greentree
impoundment comprises a floodplain levee and controllable outlet structure that is
modified periodically to promote the development of forested wetlands. Functioning
greentree impoundments above the lake reservoir are expected to provide for significant
nutrient uptake, recycling, and management benefits.
The elevation of the outlet is typically raised during winter months to promote ponding,
sediment deposition, and waterfowl habitat. Subsequently, the elevation of the outlet
is lowered in early spring to allow for vegetation growth, nutrient uptake, and seedling
establishment. Levee systems are typically constructed to provide for less than 2 to 3 feet
of inundation during winter months, to prevent over-topping, and to allow for survival of
tree seedlings. The winter depth is generally dependent upon the height of seedlings.
The raising and lowering of outlet structures requires regular monitoring and maintenance
by qualified personnel to facilitate the growth and survival of tree species. The time for
outlet adjustment may vary annually and is dependent upon localized conditions within
the watershed. Seedling mortality should be tracked on an annual basis, and the date of
spring lowering of water levels is modified to maximize the rate of forest regeneration.
Tree or shrub species selected for planting will vary based on expected hydrologic regimes
and other site-specific conditions. In general, sites lacking substantial forest vegetation
and primarily used as pasture land were targeted for this mitigation option.
1.4 MITIGATION SITE SELECTION
During the environmental impact assessment, project planners identified and evaluated a
total of 25 potential mitigation sites within stream corridors extending above the reservoir
pool. A description of mitigation potential for each of these sites was prepared in
previous documents (ESC 1998a, ESC 1998b, ESC 1999).
Of these 25 sites, 10 sites were determined to support wetland restoration potential on
floodplains encompassing up to 121 acres of restorable land area. Table 1 and Figure 1
depict the location of each site and projected acreages potentially available for wetland
restoration use.

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This document details restoration and enhancement procedures for riverine and lake
shoreline wetland restoration and creation along Richland Creek, one of the 10 mitigation
sites (Figure 2). The Richland Creek mitigation site (Site) includes 70.5 acres that
encompass the stream and adjacent floodplain servicing a watershed of approximately
14.5 square miles immediately above the reservoir. In-stream structures are proposed
along the dredged and entrenched Richland Creek corridor to reduce the rate of
groundwater discharge from the floodplain into the channel, increase overbank flooding
from the channel onto the floodplain, and increase deposition of sediment on vegetated
wetland surfaces above the reservoir pool.
This summary document includes the following: 1) descriptions of existing conditions; 2)
surface and groundwater hydraulic analyses; 3) reference lake shoreline line studies; and
4) reference soil and forest ecosystem investigations. Subsequently, detailed plans are
provided for in-stream structures, wetland restoration/creation, vegetation planting, site
monitoring, and success criteria. Remaining mitigation sites that follow the format of this
mitigation plan (utilizing in-stream structures above the reservoir pool) will be attached as
appendix documents to this summary mitigation plan.
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Corpo iti(

C.(tr?orati(?n

RANDLEMAN RESERVOIR MITIGATION PROJECT

RICHLAND CREEK SITE wn. by:
MAF FIGURE
Ckdby:
JWN
Date:
OCT 2000
I R,,agh,North Carol" Guilford County, North Carolina Projece
00.010

0 2.0 METHODS
Natural resource information for he Site was obtained from available sources, including
U. S. Geological Survey (USGS) topographic mapping (USGS High Point East and High
Point West 7.5 minute quadrang es), U. S. Fish and Wildlife Service (USFWS) National
Wetlands Inventory (NWI) mapping, and Natural Resource Conservation Service (NRCS)
soil survey (USDA 1977). These esources were utilized for base mapping and evaluation
of existing landscape and soil information prior to on-site inspection. Current (1999) aerial
photography was obtained and utilized to map relevant environmental features (Figure 3).
Characteristic and target natural community patterns were classified according to
constructs outlined in Schafale and Weakley's, Classification of the Natural Communities
of North Carolina (1990). North Carolina Natural Heritage Program (NCNHP) data bases
were evaluated for the presence of protected species and designated natural areas which
may serve as reference (relatively undisturbed) wetlands for restoration design.
On-site reference (relatively undisturbed) stream and wetland sites were selected to orient
restoration design and to provide baseline information on target (post-restoration) wetland
conditions. A regional vegetation reference data base and on-site inventory were used to
characterize target, post-restoration species composition. Topographic maps of the basin
floor were also prepared to show the gradation from permanently to semi-permanently
inundated conditions throughout the lower half of the site. A concurrent pool elevation
and sedimentation study provided information on sedimentation and wetland development
around the point of stream inflow and conservation pool levels. Topographic data were
overlaid on wetland restoration areas to establish methods for construction and restoration
of wetland communities within the Site.
Detailed topographic mapping to 1-foot contour intervals was developed by ground survey
paneling and aerial photogrametric methods. Additional land surveys were performed to
establish channel cross-sections and measure reference wetland surface topography.
Field investigations were performed in the spring of 2000 including soil surveys, on-site
resource mapping, land surveys, and landscape ecosystem classifications. Existing plant
communities and jurisdictional wetlands were described and mapped according to
landscape position, structure, composition, and groundwater analyses.
------------ -------
Wetland boundaries were obtained from a delineation performed in 1998. NRCS soil map
units were ground truthed by licenced soil scientists to verify units and to map inclusions
and taxadjunct areas. The revised soils maps were used as additional evidence for
predicting natural community patterns and wetland limits prior to human disturbances.

8
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Groundwater conditions were modeled using DRAINMOD, a computer model for
simulating withdrawal rates for shallow soils with high water tables. The model was
utilized to predict historic hydroperiods, the extent of wetland degradation due to
dredging and ditching, and the potential for wetland restoration through stream
modification.
Surface water analyses for the Richland Creek site were completed using standard study
methods of the U.S. Army Corps of Engineers (USACE) and NRCS. Flood events of a
magnitude which are expected to be equaled or exceeded once on average every 1-, 2-,
5-, 10-, or 100-year period were selected for use. These flood events are commonly called
the 2-, 5-, 10-, and 100-year floods. Floods with a return frequency of less than 2 years
are usually not studied in engineering applications. These analyses reflect either existing
or proposed conditions at the Site. The projected frequency and extent of overbank
flooding were used to determine potential for riverine wetland restoration in floodplain
portions of the Site.
This Site has been selected for wetland restoration use to promote a reduction in
sediment, nutrients, and pollutants flowing into Randleman Reservoir. Mitigation
activities are intended to provide sediment deposition, and pollutant and nutrient cycling
from surface waters within created and restored wetland areas. Recycling functions are
designed to reduce elevated nitrogen and phosphorus loads from the watershed towards
background (forest) levels, prior to discharge into the reservoir.
G1

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10
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3.0 EXISTING CONDITIONS
3.1 PHYSIOGRAPHY, TOPOGRAPHY, AND LAND USE
The Site is located in the Piedmont Physiographic Province of North Carolina within the
Cape Fear River Basin. Physiography is characterized by moderately hilly terrain with
interstream divides intermixed with steeper slopes along well-defined drainage ways. The
Site is situated in the Richland Creek floodplain within the Cape Fear River Basin
(Hydrologic Unit #03030003 [USGS 19741). The Site is located approximately 3.5 miles
southeast of High Point and approximately-5 miles southwest of Greensboro. Annual
precipitation in the region averages 42 inches per year with June and August representing
the months that support the highest average rainfall (4.21 inches and 4.36 inches
respectively) (USDA 1977).
The Site contains an approximately 5450-foot reach of Richland Creek (Figure 4).
Richland Creek supports a primary watershed of approximately 14.5 square miles and
flows into the Deep River 0.8 miles downstream. The Site is also dissected by five
unnamed tributaries from auxiliary watersheds flowing directly into the project reach of
Richland Creek (Figure 4, labeled site infalls).

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The primary watershed associated with Richland Creek extends primarily through suburban
and urban areas associated with the City of High Point, the Interstate 85 (1-85) business
corridor, and developments associated with Melbourne Heights, Bakertown, and
Springfield. Land use within headwaters is dominated by commercial, industrial, and
infrastructural development with relatively high density residential development and
abandoned pastures in many remaining areas. Changes in water quality and runoff
characteristics due to development has been further altered by systematic dredging and
straightening of the channel within major sections of the 6 mile reach of Richland Creek.
Land uses in the auxiliary watersheds and within the Site are dominated by rural and
transitional suburban uses including forest, agriculture, horse and cattle farms, residential
homes, and state roads with limited commercial development occurring in the vicinity of
crossroad communities in the area. Increased industrial and commercial development is
occurring within the auxiliary watersheds with population expansion anticipated in the
next several decades. Therefore, the area surrounding the Site is expected to undergo
land use changes to more urban, residential, infrastructural, and commercial conditions.
The Site encompasses approximately 70.5 acres, including 62 acres of disturbed
bottomland forest and 4.5 acres of pastoral land. A power line utility easement extends
along the eastern Site boundary. An elevated sewer line extends north of the Site
boundary before reaching the High Point Sewage Disposal Plant located along the
northwestern portion of the Site (Figure 4).
11
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The acreage has been subdivided into three primary physiographic units for restoration
planning purposes: 1) stream levee; 2) primary floodplain; and 3) secondary floodplain
(backwater slough) (Figure 4). The primary variables utilized to segregate wetland
landscape units include land slope, river flood elevations from Richland Creek (Section
4.3), and the rate and direction of groundwater flow (Section 4.4).
Stream Levee
Stream levees are represented by an approximately 5-acre, linear margin along the banks
of Richland Creek. The physiographic area currently extends approximately 3200 linear
feet along both sides of Richland Creek, averaging approximately 35 feet in width. Under
historic conditions, the river levee represented slightly elevated, upland habitat influenced
by the frequent deposition of coarse, sandy alluvium during river floods. Groundwater
flow is characterized by relatively rapid, lateral to radial interflow towards the river
channel, inducing well drained conditions throughout a large majority of the yew Based
on reference stream reaches natural stream levees are elevated approximately 1 to 2 fee
above the adjacent floodplain, with intermittent openings residing at ower elevations.
To allow for agricultural use of the stream floodPlain, approximately 2800 linear feet of
Richland Creek was dredged, straightened, and the low-lying levees buried under spoil
material. The elevated levees constructed along the banks of the river typically range from
12 to 6 fe t above the floodplain, providing additional confinement of stream flows in
these areas. River dredging, levee construction, and subsequent channel degradation have
lowered the channel bottom up to 12 feet below the top of the constructed levee. Under
historic conditions, the stream levee is expected to have supported Piedmont levee forest
communities (Schafale and Weakley 1990). Currently, the constructed levee primarily
supports an access road to adjacent agricultural lands in the primary floodplain.
Primary Floodplain
The primary river floodplain encompasses approximately 43 acres located along both sides
of the stream channel outside of the stream levee. (Figure 4). The floodplain historically
supported frequent overbank flooding (estimated at an approximate, 1.15-year return
interval for hydraulic models) and was periodically re-worked by alluvial processes and
periodic, long term inundation/saturation. Groundwater flow is dominated by semi-radial
to radial discharge towards the stream channel with episodic lateral discharge and surficial
expression of groundwater occurring within seepage areas. The physiographic area
continues to support isolated, low lying areas and undulating terrain where stained,
undecomposed organic matter remains on the soil surface, suggesting that long term
water storage functions were historically provided by the system.
During dredging programs along Richland Creek, a majority of the primary floodplain was
® converted for agricultural use. However, a number of these agricultural tracts have been
?L abandoned over the last 2 decades, allowing re-development of disturbance adapted,
13
'?J

successional communities. Under historic conditions, natural communities are expected
to include Piedmont bottomland hardwood forest and oval to linear pockets of riverine
swamp forest in the vicinity of low lying areas (Schafale and Weakley 1990).
Dredging along the stream has reduced the frequency of overbank flooding within the
1 primary floodplain from an estimated 1-year return interval to a 10- to 25-year return
interval that overtops the constructed levee. (Section 4.3). Therefore, the primary
floodplain and associated riverine wetland functions (sediment retention, nutrient cycling,
energy dissipation, etc.) have been effectively eliminated from the physiographic area by
stream alterations. Accelerated drainage is evident throughout the primary floodplain
physiographic area due to dredging activities and secondary stream diversions.
Secondary Floodplain
The secondary floodplain, encompassing approximately 23 acres, represents relatively flat
to gently-sloping areas situated along the toe of adjacent valley walls and braided (alluvial
fan), backwater, or anastomosed features at the confluence of the small tributaries with
the larger Richland Creek floodplain. Land slopes in this area vary significantly across
localized portions of the landscape but typically remain less than .005 rise/run. The area
includes numerous seeps, convex hummocks, and relatively long term ponding within
depressional backwater sloughs. Groundwater flow is expected to range from vertical
recharge in sloughs to lateral discharge along convex slopes adjacent to the primary
floodplain. Discharge from adjacent groundwater slopes into the floodplain floor provides
sustained surface water expression throughout the year, potentially supporting various
intermittent and perennial channels and ponded areas. Under historic conditions, the area
was likely dominated by riverine swamp forest and shrub-marsh communities.
The secondary floodplain is dissected by numerous unnamed tributaries and historically
supported auxiliary overbank flow. However, several of these tributaries have been
diverted around current and former agriculture fields and have degraded to equilibrate with
incised bed elevations in the Richland Creek channel. The ditches were diverted and
deepened to facilitate agricultural production and to convey drainage from upslope areas
through the Site. This constructed drainage network provides direct connectivity of
surface waters to Richland Creek, effectively bypassing land surfaces and potential
floodplain functions on the Site.
Upland groundwater slopes are not included within the Site boundary. However,
groundwater slopes are found immediately adjacent to the secondary floodplain on
relatively steep upland slopes. The physiographic area includes escarpments that rise 30
to 80 feet above the floodplain floor. These groundwater slopes constitute an important
component in support of wetland hydrodynamics within backwater areas of the Site.
These slopes are expected to exhibit unidirectional overland flow and accelerated radial
to lateral flow, providing for groundwater recharge along the outer floodplain periphery.
Mesic hardwood to dry oak-hickory forests persist within the physiographic area in
portions of the slopes not converted to crop land.
14

3.2 SOILS
Surficial soils have been mapped by NRCS (USDA 1977). Soils were verified in the
summer of 1999 by licenced soil scientists to refine soil map units and locate inclusions
and taxadjunct areas. Systematic transects were established and sampled to ensure
proper coverage. Refined soil mapping is depicted in Figure 5. Primary soil types include
the Chewacla series, Udorthents series, and Wehadkee series.
The floodplains and stream terraces primarily support alluvial, Chewacla soils (Fluvaquentic
Dystrochrepts), encompassing approximately 50.5 acres (72%) of the 70.5-acre Site.
Chewacla soils are somewhat poorly drained, nonhydric soils which have been formed
primarily by fluvial activity. Chewacla soils, located in the broad, relatively flat valley
floor, contain numerous inclusions of hydric soils (i.e. Wehadkee [Typic Fluvaquents]) in
depressions, ephemeral channels, and swales which are more likely to support wetland .
hydrology. Chewacla soils generally exhibit broad, inter-layered variability in texture and
permeability dependent upon energy dissipation and sediment deposition patterns
associated with each stream overbank flood event. Soil texture generally ranges from
coarse sandy loam to silt loam of moderate to moderately rapid infiltration. Important
factors in the formation and maintenance of wetland systems as hydric inclusions in the
Chewacla map units include: 1) microtopography and variability in fluvial deposition
across the landscape; 2) groundwater and surface water movement from adjacent uplands
along the outer edge of the floodplain; and 3) groundwater discharge rates from the
interior floodplain into the stream channel. Stream dredging, straightening, and
conversion to agricultural lands has likely increased the extent of Chewacla (nonhydric)
soils and concurrently decreased the extent of Wehadkee (hydric) map units in the Site.
Hydric soils are defined as "soils that are saturated, flooded, or ponded long enough
during the growing season to develop anaerobic conditions in the upper soil layer" (USDA
1987). Hydric soils comprise the Wehadkee series (Typic Fluvaquents), located primarily
within relict backwater sloughs, depressions, ephemeral channels, and swales which
remain within the secondary floodplain. Under existing conditions, the Wehadkee series
comprises approximately 13.5 acres (19%) of the Site.
The Udorthents series represent earthen spoil deposition areas that occur intermittently
throughout the Site. Material excavated from dredged stream channels was used to
construct flood control levees, build roads adjacent to canals, and to fill swales and
depressions within agricultural use areas. Udorthents map units occupy approximately 2.5
acres (4%) of the Site.

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3.3 PLANT COMMUNITIES
Plant communities along Richland Creek are influenced, in part, by past land use practices.
Drainage, site preparation, agricultural conversion, and logging over the years have
substantially altered the natural communities. Four communities have been identified for
descriptive purposes, including: 1) bottomland forest, 2) swamp forest, 3) pasture, and
' 4) levee forest (Figure 6).
Bottomland Forest
Bottomland forest accounts for approximately 44.5 acres of the 70.5-acre Site. The
bottomland forest assemblage has experienced prolonged degradation from past logging,
watershed diversion, agricultural usage, and ditch networks. The forest canopy includes
box elder (Acer negundo), sycamore (Platanus occidentalis), green ash (Fraxinus'
pennsylvanica), tulip poplar (Liriodendron tulipifera), American elm (Ulmus americana), and
' black willow (Salix nigra). Under-story species distribution is variable along hydrologic
gradients and includes muscadine grape (Vitis rotundifolia), beggar's ticks (Desmodium
sp.), Japanese honeysuckle (Lonicera japonica), poison ivy (Toxicodendron radicans),
jewel-weed (Impatiens capensis), Chinese privet (Ligustrum sinense), Virginia creeper
(Parthenocissus quinquefolia), and blackberry (Rubus sp.).
I Swamp Forest
Swamp forests persist within isolated, relict backwater areas found in depressional areas.
This community, covering approximately 12 acres, appears to have been affected by
reductions in drainage area, loss of surface hydrodynamics, reductions in hydroperiod, and
periodic timber harvest. The canopy includes species listed in bottomland hardwood
forest, with inclusion and increasing frequency of swamp chestnut oak (Quercus
michauxiil, ironwood (Carpinus caroliniana), swamp cottonwood (Populus heterophyllus),
' and sweetgum (Liquidambar styraciflua). The understory is dense to sparse, depending
on the openness of the overstory. Under open canopies, the understory is dominated by
a dense layer of graminoids and forbs, including sedges (Carex spp.), rushes (Juncus spp.),
lizard tail (Saururus cernuus), false nettle (Boehmeria cylindrica), seedbox (Ludwegia spp.),
and jewel-weed.
Levee Forest
Approximately 5 acres of levee forest are found in a narrow fringe, on the elevated
deposits (natural and man-made) along Richland Creek. These moderately well drained
areas support plant species characteristic of levee forest communities (Schafale and
Weakley 1990). Canopy species include box elder, sycamore, river birch (Betula nigra),
green ash, black walnut (Juglans nigra), sweetgum, ironwood, and red maple. The mid-
story is dominated by eastern cedar (Juniperus virginiana), black cherry (Prunus serotina),
Chinese privet, and honey locust (Gleditsia triacanthos). Understory species include virgin
1 bower (Clematis virginiana), Japanese honeysuckle, muscadine grape, mouse ear
chickweed (Cerastium glomeratum), common greenbrier (Smilax rotundifolia), and poison
1 ivy.
17

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Pasture Land
Approximately 4.5 acres of pasture land is located in the central portion of the Site. Hay
was last harvested in June of 2000. Pasture land is dominated by a variety of grasses and
herbs. The predominant species is fescue (Festuca spp.). Other characteristic species
include asters (Aster spp.), goldenrods (Soiidago spp.), horseweed (Erigeron canadensis),
pigweed (Chenopodium album), ragweed (Ambrosia artemisiifoiia), common morning glory
(ipomoea purourea), clover (Trifoiium spp.), crabgrass (Digitaria spp.), and love grass
s. (Erogrostis sp.).
Adjacent border and forest edge communities support young sweetgum, black cherry, box
elder, and red maple (Acer rubrum). Thickets containing blackberry, winged sumac,
Canada elder (Sambucus canadensis), switch cane (Arundinaria gigantea), muscadine
grape, and common greenbrier are also present.
3.4 HYDROLOGY
The Site is located within the Piedmont hydrophysiographic province, which encompasses
the entire drainage basin for the East and West Forks of the Deep River. The region is
characterized by moderately hilly terrain with interstream divides exhibiting dendritic
drainage patterns and moderately steep slopes along valley floors (0.005-0.015 rise/run).
The region is characterized by moderate rainfall. In Guilford County, precipitation
averages 42 inches per year with precipitation evenly distributed throughout the year
(USDA 1977). Large floods (20-100 year return interval) typically correspond to large
thunderstorms and tropical events in the region.
Bed load material supplied by the region consists primarily of silts, sands, and weathered
bedrock (very coarse sand and small gravel). Bedrock outcrops are considered common
within incised streams in more steeply sloped valleys. Suspended load consists primarily
of easily eroded clays and silts, which transport attached nutrients into downstream
waters. Erosion and suspended sediment loads have been linked to nutrification problems
within the Piedmont hydrophysiographic province, including the Randleman Reservoir
region (DWQ 2000).
The Site encompasses broad floodplains associated with a 5450-foot reach of Richland
Creek. At site outfall, the system supports a watershed of approximately 14.5 miles
(Figure 4). The floodplain ranges from approximately 1000 feet in width within upper
reaches of the Site to 400 feet in width at Site outfall immediately upstream of the
Interstate 85 corridor. The annual sediment load supplied by the watershed is estimated
at 44,000 cubic feet (1.0 acre-feet) (Simmons 1976).
U J
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19
I
0
The watershed is characterized by a mixture of rural, urban, and suburban land uses
associated with the City of High Point, the Interstate 85 business corridor, and
surrounding towns. The main-stem of Richland Creek extends for approximately 6 miles
with headwaters extending towards downtown High Point. The watershed includes over
17 miles of perennial tributaries in the watershed (USGS 1982). Land use cover includes
forest (58.4%), pasture (25.4%), as well as metropolitan areas 0 3.0%) which includes the
City of High Point and portions of Greensboro and Randleman (DWQ 2000). Commercial,
industrial, and residential development is expected to expand in the watershed over the
next several decades due to proximity to the greater Greensboro-High Point metropolitan
region (Section 3.1).
Surface Water
Topographic mapping and historic (1977) aerial photography indicate that Richland Creek
once meandered across former and present agricultural fields and within backwater areas
along the southern edge of the Richland Creek floodplain. Relict stream fragments have
been identified in several areas of the Site, demarcated by discontinuous, meandering
depressions. After 1977, Richland Creek was dredged, straightened, and corralled by
stream-side dikes. Where dredging and dike construction begins, the abandoned
floodplain resides at approximately 685.5 feet above MSL while constructed dikes extend,
on average, to 689 feet above MSL. As a result, river dredging, levee construction, and
subsequent channel degradation have lowered the channel bottom up to 12 feet below
the top of the constructed levee. The loss of meander geometry and steepening of the
water surface has induced further bed incision, resulting in area-wide stream-bank failure
and erosion.
Relative to the floodplain elevation, the dredged channel supports an average bank to
bank width of 30 feet, and average depth of 7.5 feet, and a cross-sectional area of
approximately 225 square feet (max depth 7.9 feet). The channel cross-section is
effectively enlarged to 330 square feet by the constructed dikes. Conversely, the historic
channel is projected to support a cross-sectional area of approximately 120 square feet
(Harman et. a/. 1999). The dredged channel supports a sinuosity (channel length/valley
length) of 1.0. Substrate within the channel is composed of unconsolidated sand and silt
sediments originating, in part, from localized bank erosion. The channel is classified as
a G5 (sand dominated gully) based on fluvial geomorphic features (Rosgen 1996).
Stream discharge and flood elevations under existing conditions have been predicted
based on hydraulic models (Section 4.2). Figure 7 provide model predictions for the 1-
(projected bankfull), 2-, and 100-year storm (Section 4.3). In diked areas, the study
indicates that dredging and dike construction have effectively eliminated the influence of
overbank flooding until events approaching the 10-year to 25-year storm. If constructed
dikes were lowered to the elevation of the adjacent floodplain, flooding from the river
would approach a 2-year return interval in support of riverine wetland formation.
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The flood elevation model suggests that, under historic (pre-dredged) conditions, the Site
exhibited potential to provide approximately 2,400,00 cubic feet (56 acre-feet) of flood
storage and sediment retention capacity. Based on flood frequency analysis, it appears
that restoring a 1-year return interval, flooding at an average depth of 1 foot, will provide
similar storage capacity within the Site (immediately above the water supply reservoir).
Under existing conditions, the incised and corralled channel has eliminated these
important flood and sediment recycling functions within the watershed.
Five unnamed tributaries dissect the Site and flow into the Richland Creek channel. These
tributaries support auxiliary watersheds encompassing approximately 3 square miles of
land area. Within the primary floodplain physiographic area (Figure 4), these channels
represent intermittent and perennial streams that have been largely diverted around current
and former agriculture fields. The ditches were diverted and deepened to facilitate
agricultural production and to convey drainage from upslope areas through the Site. As
a result, the channels have incised to equilibrate with bed elevations induced along
Richland Creek. The constructed drainage network provides direct connectivity of surface
waters to Richland Creek, effectively bypassing land surfaces and potential floodplain
functions on the Site.
Within the secondary floodplain (backwater areas), several of these unnamed tributaries
exhibit braided (alluvial fan), backwater, or anastomosed features at the confluence with
the larger stream floodplain. These sites exhibit high ground water tables, regular
overbank flooding, high deposition rates, and consequent development of open canopy
swamp forest and emergent communities.
Groundwater
Surface water hydrodynamics, such as periodic overbank floods, fluvial sediment
1 deposition, and hydraulic energy dissipation, represent important attributes of floodplains
and bottomland hardwood forest in the region. However, streams in the region typically
function as groundwater withdrawal features throughout most of the year. Therefore,
groundwater inputs from auxiliary watersheds and upland slopes abutting the floodplain
represent the primary hydrologic input resulting in the development and maintenance of
riverine wetlands at this Site.
Groundwater gradients in May 2000 include intermittent surface expression along the
outer floodplain periphery, immediately adjacent to upland buffers (groundwater recharge
features). The groundwater gradient deepens to more than 6 feet below the surface in
proximity to Richland Creek and several unnamed tributaries (groundwater discharge
features). Dredging of Richland Creek and the concurrent degradation of adjacent
unnamed tributaries has significantly lowered the groundwater table and steepened the
groundwater discharge gradient throughout pastoral and forested portions of the Site.
Restoration of a shallower (less incised) stream network will generate a flatter
11
22
H.
0
groundwater gradient, increase surf icial expression of groundwater, and potentially extend
wetland conditions into primary floodplains within the Site.
3.5 WATER QUALITY
Richland Creek maintains a State best usage classification of WS-IV CA (Stream Index No.
17-22) (DWQ 2000). Class WS-IV waters are protected as water supplies which are in
moderate to highly developed watersheds. Point source discharges are generally required
to meet stringent pre-treatment standards, to maintain pre-treatment failure (spill
prevention) plans, and to perform point source monitoring for toxic substances. Local
programs to control nonpoint source and stormwater discharge of pollution are also
required. CA signifies a Critical Area designation for watershed areas within 0.5 miles of
a water supply intake for the reservoir.
The Site consists of bottomland hardwood forest and open pasture land adjacent to the
stream channel. Run-off from adjacent farmland, residential areas, and the sludge disposal
fields from the waste treatment plant enter the drainage network through sheet flow and
on-site collection points (i.e. ponds, drainage swales and ditches). Stream channels
connecting adjacent farm ponds and storm channels have direct connectivity with
Richland Creek and may have deleterious effects on water quality.
Restoration of wetland hydrology and diversion of auxiliary watersheds onto restored
wetland surfaces will provide local water quality benefits, including important functions
such as sediment deposition, removal of elements and compounds, and nutrient cycling.
Historically, the floodplain provided water quality benefits to the 14.5 square mile
watershed associated with Richland Creek. However, runoff from this land area
effectively bypasses wetland floodplains as the dredged canals transport flow directly
through the Site. Restoration of wetland hydrology and diversion of watersheds onto
restored wetland surfaces will provide for restoration of overbank flooding and associated
water quality benefits above the Randleman Reservoir.
Because the Site is located at the elevation of the reservoir conservation pool, sediment
transport capacity of the stream system will be generally stopped at elevations of 681 feet
above MSL. A sediment wedge will develop within the reservoir pool and incrementally
extend farther into the open water area. Research suggests that up to 440,000 cubic feet
0.0 acre-foot) of sediment will be deposited annually within the reducing aquatic
environment (Simmons 1976). Associated pollutants will not generally be degraded,
assimilated, or recycled through periodic wetting (reduction) and drying (oxidation).
Therefore, wetland restoration has been designed to reduce sediment transport capacity
within the 5,450-foot reach of Richland Creek. As a result, the sediment wedge will be
extended in the upstream direction outside of the reservoir pool (above elevation 682),
where wetland functions will potentially provide for greater pollutant processing.

23

k.,
3.6 WILDLIFE
Although forested tracts in the region have been impacted, isolated natural areas provide
necessary food, water, and cover for various species of wildlife. Forested floodplains
along lower reaches of the Site support wildlife species adapted to riparian forest habitat.
In addition, ephemeral drainageways and ponding within isolated wetland areas provide
interaction among riparian and non-riparian wildlife guilds in the region. Wetland/upland
ecotones provide additional habitat diversity near the Site. These ecotones are among the
most diverse and productive environments for wildlife (Brinson et al. 1981).
During field investigations, tracks or observations of the following primarily terrestrial
mammals were documented: Virginia opossum (Didelphis virginiana), raccoon (Procyon
lotor), and white-tailed deer (Odocoileus virginianus). Other mammals expected to occur
within the project area include: southeastern shrew (Sorex longirostris), gray squirrel
(Sciurus carolinensis), eastern chipmunk (Tamias striatus), eastern cottontail (Sylvilagus
floridanus), beaver (Castor canadensis), striped skunk (Mephitis mephitis), meadow vole
(Microtus pennsylvanicus), and gray fox (Urocyon cinereoargenteus).
Due to the presence of various habitat located within the Site, a high diversity of bird
species is expected. Species sighted during field studies are typically found in both
forested communities as well as associated creek-side communities. Bird species identified
in wooded portions of the Site include: blue jay (Cyanocitta cristata), Carolina wren
(Thryothorus /udovicianus), yellow-throated warbler (Dendroica dominica), Carolina
chickadee (Parus carolinensis), and northern cardinal (Cardinalis cardinalis). Bird species
identified in open areas include: northern bobwhite (Colinus virginianus), mourning dove
(Zenaida macroura), eastern kingbird (Tyrannus tyrannus), American crow (Corvus
brachyrhynchos), American robin (Turdus migratorius), northern mockingbird (Mimus
polyglottos), song sparrow (Melospiza melodia), and eastern bluebird (Sialia sialis).
Characteristic bird species that can be expected to utilize wetlands in the region include
great blue heron (Ardea herodias), black-crowned night heron (Nycticorax nycticorax),
mallard (Anas platyrhynchos), wood duck (Aix sponsa), and barred owl (Strix varia). In
addition, a high number of passerine birds, both permanent and summer resident species,
nest in bottomland hardwood forest. Among these are several neotropical migrants such
as Swainson's warbler (Limnothlypis swainsonii) and prothonotary warbler (Protonotaria
citrea), and other forest interior species such as the wood thrush (Hylocichla mustelina)
and Acadian flycatcher (Empidonax virescens) that require large tracts of contiguous forest
for survival (Keller et al. 1993).
Isolated areas of standing water, ditches, and canals in the area provide marginal
conditions for species of fish, reptiles, and amphibians. Characteristic species include red-
bellied water snake (Nerodia erythrogaster), yellow-bellied turtle (Trachemys scripta),
spotted turtle (Clemmys guttata), southern leopard frog (Rana utricularia), and marbled
n
24
1-1
i
salamander (Ambystoma opacum). However, due to dredging, straightening, and diversion
of streams into linear ditches that lack riparian cover, functional in-stream habitat is
considered significantly reduced within Richland Creek and the unnamed tributaries
(Figure 4). Riffles, pools, and diagnostic in-stream habitats are generally lacking within
the on-site, linear dredged channels.
3.7 UNIQUE NATURAL AREAS AND PROTECTED SPECIES
No significant natural areas are expected to be impacted by mitigation activities at the
Site. On-site forest corridors have connectivity with forested communities primarily along
stream corridors both above and below the site. Proposed mitigation is expected to
enhance these natural areas. No North Carolina Natural Heritage Program (NCNHP)-
designated Significant Natural Heritage Area (SNHA) exists within the project corridor.
A SNHA designation is given to an area due to the presence of rare species, rare or high
quality natural communities, or geologic features. This designation does not confer
protection or regulatory status. The nearest SNHA is the Jamestown Meander Scar which
is located approximately 2.1 miles to the northwest. The proposed mitigation as well as
the associated construction activities will be limited to the margins of the project
boundaries; therefore, no impacts are anticipated to any rare and unique natural areas.
Species with Federal classifications of Endangered (E) or Threatened (T) are protected
under the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.). The
status of "Endangered" refers to "any species which is in danger of extinction throughout
all or a significant portion of its range", and the status of "Threatened" refers to "any
species which is likely to become an endangered species within the foreseeable future
throughout all or a significant portion of its range" (16 U.S.C. 1532). The US Fish and
Wildlife Service (FWS) has revised the list of Federal-protected species as of June 16,
2000 to include the following protected species for Guilford (G) and Randolph (R)
Counties.
Vertebrates Status County
Bald eagle (Haliaeetus leucocephalus) T G
Cape Fear shiner (Notropis mekistocholas) E R
Vascular Plants
Schweinitz's sunflower (Rhus michauxii) E R
L
P
The status of these species is described below. Based on NCNHP files, no documented
occurrences of Federally "Threatened" or "Endangered" species in the vicinity of the Site.
Bald Eagle (Haliaeetus leucocephalus) - The bald eagle occurs throughout North America,
primarily in association with large lakes and coastal bays and sounds where food is
plentiful. Eagles are opportunistic hunters and scavengers, feeding on a wide variety of
aquatic-dependent organisms including fish, snakes, small mammals, and large water
25

birds. Nest sites occur close to feeding grounds in large trees (predominately pine or
cypress), either living or dead.
The Randleman Reservoir is expected to provide increased habitat potential for bald eagles
in the region. Mitigation activities would be expected to increase the distribution of
aquatic-dependent organisms in the Site, a food source for the raptor.
Cape Fear shiner (Notropis mekistocho/as) - The Cape Fear shiner is a small (to 2 inches),
moderately stocky minnow. Food items probably include bottom detritus, diatoms, and
other periphytes (USFWS 1988). Habitat of the Cape Fear shiner is generally clean streams
with pools, riffles, and shallow runs over gravel, cobble, and boulder substrate (Rohde et.
ai. 1994). Little is known about the Cape Fear shiner's life history. Present distribution
(November 1988) includes portions of Randolph, Chatham, Lee, Moore, and Harnett
Counties (USFWS 1988). As of 20 December 2000, the N.C. Wildlife Resources
Commission has designated Critical Habitat for this species in the Deep River in portions
of Randolph and Moore Counties, approximately 30 miles below the Site. Because
Richland Creek has been dredged and substrate is dominated by unconsolidated sediment,
habitat for this species is not expected on the Site.
Schweinitz's Sunflower (Heiianthus schweinitziil - Schweinitz's sunflower is an erect,
unbranched, rhizomatous, perennial herb that grows to approximately 6 feet in height.
The current range of this species is within 60 miles of Charlotte, North Carolina, occurring
on upland interstream flats or gentle slopes, in soils that are thin or clayey in texture. The
species needs open areas protected from shade or excessive competition, reminiscent of
Piedmont prairies. Disturbances such as fire maintenance or regular mowing help sustain
preferred habitat (USFWS 1994). Bottomland forest communities on the Site are not
considered suitable habitat for this species.
Plant and animal species which are on the North Carolina state list as Endangered (E),
Threatened (T), or Special Concern (SC) receive limited protection under the North
Carolina Endangered Species Act (G.S. 113-331 et seq.) and the North Carolina Plant
Protection Act of 1979 (G.S. 106-202 et seq.). NCNHP records indicate no documented
occurrence of state listed species in the vicinity of the project.
3.8 JURISDICTIONAL WETLANDS
Jurisdictional areas are defined using the criteria set forth in the U.S. Army Corps of
Engineers, Wetlands Delineation Manual (DOA 1987). Approximately 13.6 acres of
jurisdictional wetlands were delineated on-site and confirmed by the U.S. Army Corps of
Engineers. Figure 8 depicts the boundary location of existing jurisdictional wetland
systems.
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26
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Jurisdictional wetlands are most prevalent at the mouth of the numerous small tributaries
entering the Site. Discharge from adjacent groundwater slopes and braided channel
streams into the floodplain floor provide sustained surface water expression throughout
much of the year. Additional wetland systems are found in association with abandoned
meander channels located primarily along the south central property boundary.
Approximately 1.9 acres of these jurisdictional wetlands will be inundated by the reservoir
conservation pool (11.7 net acres of jurisdictional wetlands will remain after filling of the
reservoir).

28

fl'.
4.0 WETLAND RESTORATION STUDIES
This section summarizes studies performed to orient restoration design. Studies include:
1) Restoration Alternatives Analyses: Alternatives for wetland restoration
relative to stream, floodplain, and reservoir functions were assessed.
2) Reservoir Pool Sedimentation and Wetland Vegetation Study: Sedimentation
patterns and extent of wetlands were assessed on existing reservoirs in the
region.
3) Surface Water Analyses: Overbank flooding frequency and extent was
estimated based on the selected wetland restoration method.
4) Groundwater Modeling: The effect of drainage features on groundwater
wetland hydroperiods was modeled.
5) Reference Plant Communities: Reference wetland communities were
sampled to predict the target distribution of vegetation to be established in
restoration areas.
6) Reference Physiography and Surface Topography: Reference wetland
surfaces were measured within an existing alluvial fan and stream to
characterize long term, projected conditions at the Site.
4.1 RESTORATION ALTERNATIVES ANALYSES
The objectives of this project include:
1) Assist in protecting the drinking water supply from pollutants discharged
from the developing watersheds. Pollutants attached to sediment
represents the primary water quality concern for this project.
2) Maximize benefits to water quality through establishment of functioning
wetlands above the reservoir pool.
3) Replace habitat for wetland dependent wildlife displaced by establishment
of open water.
4) Maximize the area of wetland restoration achieved by the project.
Restoration alternatives suggested by project participants are briefly described below.
Stable Channel Construction
Reconstruction of a potentially stable stream system was assessed as a replacement for
the existing, dredged and incised channel. The new channel would be designed to mimic
referenced, stable attributes including the geomorphic dimension, pattern, and profile
needed to transport water and sediment produced by the watershed. The restored
channel would reduce the rate of groundwater withdrawal from adjacent floodplains,
potentially resulting in wetland hydrology restoration in certain areas.

29

[?I
This alternative would facilitate transport of sediment generated by the watershed into
the Randleman Reservoir. Within the lower half of the Site, this capacity to transport
sediment would be unavoidably stopped by the conservation pool associated with the
reservoir. In addition, facilitating transport of sediment and pollutants into water supply
waters is considered contrary to water quality related, project objectives. Therefore, this
option was discarded.
Greentree Impoundments
Greentree impoundments comprise a series of floodplain levees and controllable outlet
structures that are modified periodically throughout the year to promote the development
02 of forested, shrub-scrub, and emergent wetlands. Greentree impoundments have been
constructed above other water supply reservoirs in the region for wetland, wildlife, and
sediment retention functions. These structures can be controlled to regulate the depth
and frequency of inundation based upon objectives of the system. In this case, the
structures would be used to establish vegetated wetlands and limit transport of pollutants
into the reservoir.
In general, the levee system is constructed to provide for less than 2 to 3 feet of
inundation during winter months, to prevent over-topping, and to allow for survival of tree
seedlings. The winter depth is generally dependent upon the height of seedlings. The
raising and lowering of outlet structures requires regular monitoring and maintenance by
qualified personnel to facilitate the growth of tree species. The actual date that the
outlet is modified may vary annually and is dependent upon localized conditions within
the watershed. Seedling mortality is tracked on an annual basis and the date of spring
lowering is modified to maximize the rate of forest regeneration. Tree species selected for
planting may also be modified based upon collected data. Greentree impoundments
designed for forested wetland restoration have failed in the past, due primarily to lack of
resources for monitoring, management, and manipulation.
Based on alternatives analyses, construction of greentree impoundments across the
Richland Creek floodplain represents a viable option for this project. Although
construction activities would induce disturbances within the existing forest, the structures
would allow pro-active control of wetland development and function behind each
impoundment. An option that reduces both controllability and disturbance to the existing
landscape involves passive development of an alluvial fan as described below.
Alluvial Wetland Fan Development
This alternative is similar to greentree impoundments as described above. Both options
are designed to elevate water tables and reduce sediment transport into the reservoir.
However, with this scenario, levees are not constructed across the floodplain. Alluvial fan
development entails placement of fixed, in-stream weirs within the dredged channel. The
in-stream modifications are expected to reduce the degree of channel incision, increase
overbank flooding, reduce stream sediment transport capacity, and provide greater
30
0
a sediment deposition within vegetated wetlands. The system would progress towards an
alluvial wetland fan where the channel actively migrates across fluvial material. During
the interim period, in-stream structures will sustain significant energy during flood events;
therefore, the potential exists for development of channel by-passes (shoot cut-offs)
around the structures. As such, risk of wetland restoration failure exists. The structures
must be designed to avoid short-circuiting and provide for sediment deposition in the
incised channel. Over a relatively long period of time, the shallower channel would
invariably abandon the structures and begin to actively migrate across the restored
floodplain. At this point, the system would need to be monitored for evidence of head-
cutting immediately above the reservoir or migration bank into the abandoned, dredged
channel. Additional structural modifications may be required in the future, after the
migrating stream abandons the existing dredged channel.
Passive development of an alluvial fan immediately above the reservoir represents a viable
option for this Site. This option will reduce initial disturbance in the floodplain associated
with greentree impoundments, reduce implementation cost relative to greentree
impoundments, and will require less need for seasonal management of the structures.
Based on alternatives analyses, placement of in-stream structures and alluvial wetland
development has been selected as the preferred mitigation alternative.
4.2 RESERVOIR POOL LEVEL AND SEDIMENTATION ANALYSIS
Reservoir sediment quality is an important environmental concern because sediment may
act as both a sink and a source of water-quality constituents to the overlying water
column and biota. Sedimentation rates are dependant on existing land use, land use
modifications, soils, and basin topography. Alternatives for sedimentation reduction
potentially include up-stream land management techniques, sluicing of sediment through
the reservoir, or interception of the sediment prior to entry into the reservoir. Even with
strict land management techniques in an urbanizing watershed, a certain amount of
"background" sediment will continually be moved by erosion processes. In a stable river
bed, erosion, sediment transport and deposition are in equilibrium. Dam construction
disrupts this balance, raising the base level of streams above the reservoir, and
encouraging the deposition through reduction of the gradient. As a result, the stream
deposits sediment as a delta at the confluence with the conservation pool. The
deposition process, otherwise known as warping or shoaling, advances at varying rates
dependent on the site and rate of sediment supply. Slope angles and extension patterns
on the delta are dependent on the particle size of the prevailing sediment deposited, with
courser sediment associated with higher angle slopes.
Fil The Richland Creek wetland restoration project resides immediately above the normal pool
elevation (i.e. conservation pool) for the Randleman reservoir (Elevation = 682 feet above
MSL). Currently, the stream channel is incised to depths which induce a groundwater
withdrawal gradient (rate) that does not allow for wetland presence on the adjacent
primary floodplain. After the reservoir is constructed, sediment accretion is likely to occur
31
I
k W
within the Site, immediately upstream and downstream of the conservation pool. This
accretion will forma sediment wedges within the floodplain, stream channel, and delta
area inducing passive wetland conditions for an unknown distance (or elevation) in both
the upstream and downstream direction.
Obiectives
The objective of this study is to collect the following information on existing reservoirs
in the region:
1) Determine the elevation range above the conservation pool that supports
relatively contiguous wetlands apparently resulting from the conservation
pool, groundwater mounding, and/or sediment accretion. The data reported
will include the elevation of the conservation pool, the average period that
the reservoir water surface resides at the conservation pool elevation, the
elevation range for relatively contiguous, forested wetland formation, and
elevation range for emergent wetland formation.
2) Determine the elevation range of the stream bed above the conservation
pool that has sustained sediment accretion to the extent that the channel
supports an average depth of 1 foot or less.
3) Determine the range of channel depths present in the wetland elevation
range.
4) Prepare a profile and plan view that depicts typical conditions relative to the
conservation pool.
Methods
Field reconnaissance of several reservoirs and impoundments in the central Piedmont was
conducted in order to establish baseline information on sedimentation and wetland
development around the point of stream inflow and conservation pool levels. Two sites
were chosen that best exhibited long term (> 10 years) sedimentation processes for large
and small watersheds. One site is located at the point of inflow of Little Briar Creek into
Crabtree Lake, Wake County. Little Briar Creek services a watershed of approximately
13.5 square miles. Land use for this sub-basin is predominantly forested, but is part of
a rapidly developing part of Research Triangle Park, including the Raleigh-Durham
International Airport. The second site is located at the inflow of an unnamed tributary
of Horse Creek into Falls Lake, Wake County. The tributary services a watershed of
approximately 0.3 square miles. Land use for this watershed is predominantly forested,
though residential development is encroaching upon the upper reaches of the area.
Soils are mapped as the Chewacla series throughout the Crabtree Lake site, similar to
conditions on the mitigation site (USDA 1970). On the Falls Lake site, soils are mapped
as the Wake soils, 10-25% slopes (Lithic Udipsamments).

32
0
0
Topographic maps of the alluvial wetland fans were prepared to 0.5-foot contour intervals
by laser level and Global Positioning System (GPS) measurements. Embankments,
shorelines, and wetland boundaries were measured and surveyed relative to the reservoir
water surface elevations. For Falls Lake, conservation pool and daily water surface
elevations were obtained for a 16-year period from USACE (1984-1999). Pool elevation
for Crabtree Lake was obtained from the elevation of the low-flow spillway crest tied to
a local USGS benchmark. Cross-sections and profiles were generated for the local stream
reach and floodplain area. Sediment borings were sited at various points along the
boundary of wetlands to determine depth of groundwater table relative to reservoir
elevations.
Results
Figures 9 and 10 provide a plan view and cross section for the sites at Crabtree Lake and
Falls Lake, including the groundwater elevations along the wetland fringe. Within the
conservation pool, a majority of the sediment deposition area resides under approximately
0.5 feet of water. Sediment deposition is greatest below the pool elevation contour with
inundated sediment bars generally extending into the lake over time. As the deposition
wedge elevates within central reaches of the inundated floodplain, the channel tends to
migrate towards the toe of adjacent slopes, incrementally filling the inundated valley floor.
On average, emergent wetland vegetation is present on accreted sediment to within 1 foot
below the normal pool. Forested and shrub-scrub wetland vegetation is typically present
to 2 feet above the normal pool in the upstream direction. These wetlands appear be
induced by an up-welling in the down-valley migration of groundwater, prior to inflow
with the conservation pool.
A review of lake level data for these reservoirs suggests that the water surface that
induces these wetlands resides within 0.5 feet of the conservation pool elevation, on
average, for 66% of the year. In Falls Lake, data indicate that the sediment wedge is
generated by water surfaces within 2 feet of the conservation pool elevation for 82% of
the time over the 15-year monitoring period'.
The study suggests that sediment deposition is concentrated within inundated areas at
or just below the conservation pool elevation. As the sediment surface approaches the
elevation of the conservation pool, the wedge begins to extend further into the reservoir.
This accreting surface passively develops emergent wetland vegetation on surfaces within
1 foot of the conservation pool. This accreting wetland surface will continue to enlarge
over the life of the reservoir.
1 For Falls Lake, the conservation pool elevation has been held fixed at 250.1 feet above MSL
over the 15-year monitoring period.
9
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Based on the two reference sites studied, forested and shrub-scrub-wetlands typically
develop passively on floodplain surfaces that reside up to 2 feet above the conservation
pool. The area sustains sediment deposition in the active channel, including channel
migration. across the developing delta over time.
Application
For this application, the water surface within the filled, Randleman Reservoir is assumed
to remain within 0.5 feet of the conservation pool (682 feet above MSL) for a minimum
of 66% of the year and within 2.0 feet of the conservation pool for a minimum 82% of
the time over a 15-year period. Figure 11 depicts mapping of resulting passive wetland
I development projected to occur on the Site as a result of the Randleman Reservoir.
The Site includes approximately 13.0 acres of open water (below 681 elevation) that are
projected to support future accretion and development of emergent wetlands. The 13.0-
acre area includes backwater conditions from the reservoir that will extend up the entire
on-site reach of the Richland Creek channel.
Between elevations of 681 and 682 feet above
MSL, emergent and submerged aquatic
vegetation is projected to develop. This area will be semi-permanently saturated or
inundated up to 1 foot in depth immediately after filling the reservoir. Based on reference
studies, the area is expected to support 7.0 acres of wetlands upon project completion.
In upper reaches of the lake effect area, shrub-scrub and forested wetland systems are
expected to be passively restored, encompassing approximately 9.0 acres on lands from
682 to 684 feet above MSL.
In total, approximately 24.0 acres are expected to support wetlands as a result of
hydrological modifications associated with the reservoir. Active wetland restoration
measures will include removal of dikes within the restoration area, planting of wetland
adapted vegetation, and placement of in-stream weirs designed to laterally extend the
sediment wedge and wetland extent in the up-valley direction.

e

4.3 SURFACE WATER ANALYSES
Surface drainage on the Site and surrounding area was analyzed to predict the effects of
diverting existing surface drainage into wetland restoration areas along the primary and
secondary floodplains. Several alternatives were evaluated to determine surface water
modifications that maximize wetland acreage and water quality benefits, while providing
for increased wetland habitat for dependent species.
36

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Hydrologic and hydraulic analyses were completed using standard study methods of
USACE and NRCS. Flood events of a magnitude which are expected to be equaled or
exceeded once on average every 1-, 2-, 5-, 10-, or 100-year period were selected to
characterize existing and proposed conditions at the Site.
Hydrologic Analyses
Hydrologic analyses were carried out using the USACE HEC-1 model to establish the peak
stream discharge for the 1-, 2-, 5-, 10-, and 100-year flood events.
Input for the HEC-1 model consisted of synthetic storm precipitation data, drainage area,
NRCS curve numbers, and drainage basin lag time. Table 2 summarizes the total, 24-hour
precipitation event for each storm that was analyzed. Precipitation data was obtained
from U.S. National Weather Service documents (NOAA TP-40 and Hydro-35). The
drainage area was delineated on 7.5-minute USGS topographic maps and then subdivided
into subbasins based on land use or location of tributaries. The drainage area for each
subbasin was estimated using a planimeter. The NRCS curve numbers were estimated
using methods described in the TR-55 model. The subbasin lag times were estimated
using Snyder's method.
Because there were no onsite gage data, the HEC-1 computer models could not be
calibrated. The models were validated by comparing the 100-year peak discharges
estimated from the HEC-1 models with peak discharges estimated by regional formulas for
the Piedmont region of North Carolina in the USGS Water-Resources Investigations Report
87-4096. NRCS curve numbers for the HEC-1 models were adjusted until the HEC-1 peak
discharges were within 25 - 30% of the regional formula values. Table 2 summarizes peak
discharges estimated by the validated HEC-1 model and the regional equations.
Hydraulic Analyses
Water-surface elevations of the 1-, 2-, 5-, 10-, and 100-year floods of Richland Creek were
estimated using the USACE HEC-2 computer program. Channel cross sections for the
hydraulic analyses were obtained from the most currently available HEC-2 computer runs
completed for Federal Emergency Management Agency (FEMA) Flood Insurance Studies
(FIS). Additional cross-sections that were needed to model proposed structures were
taken from digital orthophoto maps with a contour interval of 1 foot.
38

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Roughness coefficients (Manning's "n") in the channels and on the overbank areas were
taken from the HEC-2 computer runs previously mentioned and verified with field
inspections of the sites. Roughness coefficients in the main channel were 0.06 and 0.12
for overbank areas.
Starting water surface elevations and energy slope for existing conditions were estimated
from the published flood insurance studies for Guilford County. The slope-area option
provided by the HEC-2 model was used to estimate the true value of the water surface
elevation at the beginning cross-section. For future conditions, the starting water surface
elevation at the first cross-section was 688.21 feet (100-year reservoir pool elevation) for
the 100-year flood and 682 feet for the 1-, 2-, 5-, and 10-year floods (normal reservoir
pool elevation).
Tables 2 summarizes the water surface elevations for existing and proposed conditions.
Water surface elevation are approximately 2.6 - 3.2 feet higher for proposed conditions
in downstream reaches of the Site, which is the closest cross-section to the reservoir pool.
As the cross-sections progress upstream away from the reservoir, the difference between
proposed and existing conditions decreases.
Figure 7 (Section 3.0) depicts modeled flood elevations for the 1-, 2-, and 100-year, 24-
hour storm event. The model indicates that overbank flooding has been effectively
eliminated until the 10-year storm along diked sections of the Creek. For the more
frequent storm events in un-diked areas 0-year to 5-year return interval), the efficacy of
the model has been questioned based upon observations in the field. The model suggests
that overbank flooding occurs annually under existing conditions.
Contact with former land managers suggest that overbank flood events have not been
recalled since the early 1990s. This period includes 24-hour rainfall events of 2.95 inches
and 4 inches (City of Greensboro rainfall on 16 February 1998 and 9 September 1996
respectively). Visual observations of erosion, scour, and wrack lines indicate that the
water surface resided several feet below the bankfull channel during the period after a
2.97- inch and 2.98-inch, 24-hour event (19 March 1998 and 8 May 1998 respectively).
One overbank event was recalled by operators of the nearby sewage treatment plant in or
around 1990, possibly due, in part, to a 5.55-inch rain event in January 1990. If so, these
observations suggest that overbank flooding under existing conditions may not occur until
events approximated by the 10-year to 100-year return interval, contrary to the HEC2
estimates.
Restoration methods are designed to reduce the channel from 7.5 feet in depth below the
floodplain to 1-3 feet below the floodplain after restoration. The channel cross-sectional
area will decrease from an average of approximately 237 square feet under existing
conditions to 65 square feet after modifications (73% reduction in cross-sectional area).
Based on available information, the reduction in channel cross-sectional area is intended
40
f

to restore overbank flooding from the 10-year to 25-year return interval to the 1-year
return interval or less for riverine wetland restoration purposes. The flood waters and
suspended sediment would migrate as sheet flow or groundwater migration in the down-
valley direction, across restored forested floodplains within the Site.
4.4- GROUNDWATER MODELING
Groundwater modeling was performed to characterize water table elevations under historic
(reference), existing, and post-restoration conditions. The groundwater modeling software
selected for simulating shallow subsurface conditions and groundwater behavior at the
Site is DRAINMOD. This model was developed by R.W. Skaggs, Ph.D., P.E., of North
Carolina State University (NCSU) to simulate the performance of water table management
systems.
Model Description
DRAINMOD was originally developed to simulate the performance of agricultural drainage
networks on sites with shallow water table conditions. DRAINMOD predicts water
balances in the soil-water regime at the midpoint between two drains of equal elevation.
The model is capable of calculating hourly values for water table depth, surface runoff,
subsurface drainage, infiltration, and actual _ evapotranspiration over long periods
referenced to climatological data. The reliability of DRAINMOD has been tested for a wide
range of soil, crop, and climatological conditions. Results of tests in North Carolina
(Skaggs, 1982), Ohio (Skaggs et a/. 1981), Louisiana (Gayle et A 1985; Fouss et a/.
1987), Florida (Rogers 1985), Michigan (Belcher and Merva 1987), and Belgium (Susanto
et a/. 1987) indicate that the model can be used to reliably predict water table elevations
and drain flow rates. DRAINMOD has also been used to evaluate wetland hydrology by
Skaggs et a/. (1993). Methods for evaluating water balance equations and equation
variables are discussed in Skaggs et a/. (1993).
t
DRAINMOD has been modified for application to wetland studies by adding a counter that
accumulates the number of events wherein the water table rises above specified depth
and remains above that threshold depth for a given duration during the growing season.
Wetland hydrology is defined as groundwater within 12 inches of the surface for 28
consecutive days (12.5 % of the growing season), and 11 consecutive days (5 % of the
growing season). Wetland hydrology is achieved in the model if target hydroperiods are
met for more than one-half of the number of years modeled (i.e., 16 out of 31).
Groundwater drainage contours are established on available mapping for various durations
of saturation within 1-foot of the soil surface (i. e. saturation contour for 0-5%, 5-12.5%,
and 12.5-20% of the growing season).
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41
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Model inputs for DRAINMOD simulations were obtained as follows: the United States
Department of Agriculture (USDA) soil texture classification, number of days in the
growing season (defined as March 26 - November 6), and hydraulic conductivity data
were obtained from the NRCS soil survey for Guilford County (USDA ?1977 . Inputs for
soil parameters such as the water table depth/volume, drained/upflux relationship, Green- p )
Ampt parameters, and water content/matric suction relationship were obtained utilizing
the MUUF computer software developed by NRCS. Precipitation and temperature files
were obtained for the years 1930 through 1980 for Charlotte, North Carolina.
DRAINMOD simulations were designed to predict the transition zone from Chewacla soils
to Wehadkee soils based on groundwater drainage conditions within a relatively flat
floodplain surface. Chewacla soils represent a nonhydric (nonwetland), somewhat poorly
drained soil that is common on primary floodplains immediately adjacent to streams. The
Wehadkee series comprises hydric (typically wetland), poorly drained soils that are typical
in backwater floodplain areas situated further from drainageways.
Forested conditions (evapotranspiration rates) and published hydraulic conductivity values
were assumed for Chewacla soils. The simulations were run for six channel inverts (0, 1,
2, 4, 6, and 8 feet) and at various target hydroperiods during the growing season. 156le
3 provides a depiction of the groundwater discharge zone of influence by invert depth
(elevation below floodplain). For example, a stream channel invert 6 feet below the
floodplain elevation is modeled as reducing surface hydroperiods below 5% of the
growing season at a distance of 215 feet from the channel. A former floodplain surface
6 feet in elevation above the channel invert and greater than 215 feet from the channel
is projected to support wetlands.
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The preliminary groundwater drainage model was interpreted based upon field verification
of NRCS soil map units, channel depth (based on measured cross-sections), and floodplain
elevation (based on topographic maps). Model parameters were set to predict the average
annual duration in which groundwater remains within 1-foot of the soil surface at
assigned elevations above a channel invert or in-stream structure. The floodplain
elevations outside of the groundwater drainage contour and at the modeled channel depth
were judged to have a hydroperiod greater than 5 percent. Mapping of areas potentially
supporting wetland hydrology was prepared based on available topographic mapping
(Figure 12).
Post-Restoration Model Applications and Results
For groundwater wetland restoration, the primary objectives of this project include: 1)
reduce channel incision along Richland Creek and associated tributaries; 2) elevate the
groundwater gradient into the rooting zone for developing vegetation; and 3) establish
minimum wetland hydroperiods encompassing 5% of the growing season, which are
typical for riverine wetlands in the Piedmont hydrophysiographic province. Therefore, the
effective post-project depths of the Richland Creek channel will be reduced from an
average of 7.5 feet under existing conditions to gradients between 1 to 3 feet below the
floodplain.
42
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Table 3
Modeled Groundwater Discharge Zone of Influence on Wetland Hydroperiod
Chewacla / Wehadkee Soil
Floodplain Surface Groundwater Number of Groundwater Number of
Elevation Above Discharge Zone of Years Discharge Zone of Years
Channel Invert / Influence` Wetland Influence Wetland
Weir Height' (feet) Criteria Met (feat) Criteria Met
(feet) (Surface (Surface
Hydroperiods
<5% of the
growing season) Hydroperiods <
12.5% of the
growing season)"
Forested Conditions
(relatively high surface water storage and rooting functions)
0 ----- 29/31 ----- 27/31
1 253 20/31 145 16/31
2 85 16/31 225 16/31
3 125 16/32 275 17/31
4 160 16/31 315 16/31
6 215 16/31 380 16/31
8 245 16/31 405 16/31
1: "Weir Height" is assumed to represent the effective depth (invert) of the drainage feature.
2: Soil hydraulic conductivities and drainage rates have been generalized based upon NRCS data and regional
averages.
3: Discharge Zone of Influence is equal to '/: of the modeled ditch spacing
4: Based on field observations, soil types projected to support wetland hydroperiods for greater than 5% to
12.5% of the growing season are expected to exhibit characteristics more indicative of the Wehadkee
series, a poorly drained soil. Based on the model, these areas may occur on floodplains within 25 feet
to 200 feet of streams potentially lacking significant effluent (groundwater withdrawal) character, such
as very shallow channels. Conversely, the model suggests that the transition from Chewacla soils
(somewhat poorly drained) to Wehadkee soils (poorly drained) may be achieved adjacent to larger
(dredged) effluent channels at distances ranging from 300 feet to 400 feet from the drainage structure
(assuming a relatively flat floodplain surface).
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DRAINMOD simulations modeled the zone of influence of the post project channel on
wetland hydroperiods within the primary floodplain. The maximum zone of influence may
be used to predict the area of groundwater wetland hydrological influence that may result
due the elevation of stream flow within the channel. In addition, the model provides an
estimate of the area that may continue to be affected in perpetuity by the stream channel
at a depth of 1 to 3 feet below the floodplain elevation.
Based on these simulations, the post-restoration channel is expected to continue to
effectively drain groundwater from adjacent areas to a distance of approximately 25 feet
to 125 feet from the channel, dependent upon the effective channel depth (base-flow
water surface elevation). Based on the model, approximately 6.4 acres immediately
adjacent to the post-restoration channel will not support groundwater wetland
hydroperiods (< 5% of the growing season) (Figure 12). In order to establish wetlands
in these stream-side areas, overbank flooding (surface water inputs) need to be restored
to a 1-year (annual) return interval with surface and vegetation roughness preventing
return flow to the channel for a minimum of 5% (11 days) of the growing season.
4.5 REFERENCE PLANT COMMUNITIES
In order to establish a forested wetland system for mitigation purposes, a reference
community needs to be established. According to Mitigation Site Classification (MIST)
guidelines (EPA 1990), the area of proposed restoration should attempt to emulate a
Reference Forest Ecosystem (RFE) in terms of soils, hydrology, and vegetation. In this
case, the target RFEs were composed of steady-state woodlands in the region that have
sustained loading of fluvial sediments on floodplains in the past. However, forest
canopies have developed on these reference sites which support soil, landform, and
hydrological characteristics that restoration will attempt to emulate.
All of the RFE sites have been impacted by sediment deposition, selective cutting or hi' gh-
ggrradingg channel migration/disturbances, and relatively high energy flood events.
Theeore, the species composition of these plots should be considered as a guide only.
Reference forest data used in restoration was modified to emulate steady state community
structure as described in the Classification of the Natural Communities of North Carolina
(Schafale and Weakley 1990).
Two regional reference sites were selected within floodplains along the Rocky River in
Cabarrus County, North Carolina. Floodplains associated with this river system have
aggraded over the past century, inducing braided channel configurations and accelerated
sediment deposition within reference feeder tributaries. However, the 16 plots have been
placed within relatively--mature bottomland hardwood/swamp forests that have developed
on accreted sediment.
a_
45
l
e
The reference vegetation samples are designed to characterize the plant communities
proposed for restoration. Circular, 0.1-acre plot sampling was utilized to establish base-line
vegetation composition and structure in reference areas. Species were recorded along
with individual tree diameters, canopy class, and dominance. From collected field data,
importance values (Brower et al. 1990) of dominant canopy and mid-story trees were
calculated. The composition of shrub/sapling and herb strata were recorded and identified
to species (Table 4 and Table 5).
At Site 1 (Table 4), the forest canopy is dominated by green ash, (Importance value [IV]
28%), sweetgum (IV 19%), American elm (U/mus americana) (IV 11 %), box elder (IV 8%)
and red maple (IV 7%). Canopy species with lesser importance include black willow,
slippery elm (U/mus alata), river birch, tulip poplar, and water oak (Quercus nigra).
Understory trees include flowering dogwood, ironwood, and sugarberry (Celtis laevigata).
A developed shrub layer is not generally present. Herbs include Nepal microstegium,
violets (Viola spp.), asters (Aster sp.), and river oats (Chasmanthium latifolium).
At Site 2 (Table 5), the forest canopy is dominated by green ash, (IV 39%), box elder (IV
22%), American elm (IV 12%), and swamp chestnut oak (IV 6%). Portions of the canopy
at RFE locations were also dominated by ironwood, overcup oak (Quercus lyrata),
sugarberry, sweet gum, red maple, black willow, slippery elm, water oak, and river birch.
The shrub/sapling layer is characterized by the non-native Chinese privet (Ligustrum
chinensis), paw-paw (Asimina triloba), and shade tolerant canopy species. Herbaceous
species include Japanese honeysuckle (Lonicera japonica), blackberry, muscadine, common
greenbriar, sedges (Carex spp.), and poison ivy.
Piedmont swamp forests are communities located in depressional areas, along toe slopes,
and at the confluence of alluvial valleys, where lateral flow is restricted. These sites are
hydrologically influenced by upland seeps and drainages, and by occasional riverine
flooding. Overstory species are dominated by flood-tolerant bottomland elements such
as sweetgum, American elm, willow oak (Quercus phellos), swamp chestnut oak, green
ash, overcup oak, and swamp cottonwood (Populus heterophylla). Wetter sites may
provide a broken to open canopy providing enough light for development of a dense
herbaceous/shrub layer. Species found on these sites may include button-bush
(Cephalanthus occidentalis), elderberry (Sambucus canadensis), silky dogwood, false
nettle (Boehmeria cylindrica), sedges (Carex spp), rushes (Juncus spp.), and lizard's tail
(Saururus cernuus). Giant cane (Arundinaria gigantea) is prevalent in places.

46

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4.6 REFERENCE PHYSIOGRAPHY AND SURFACE TOPOGRAPHY
Surface features were mapped within reference Piedmont swam p/bottomland hardwood
forest in order to establish base-line topographic conditions for restoration planning use.
This community lies within a seasonally to semi-permanently inundated area that has
supported sediment accretion in the past with inundation from stream flows occurring on
a frequent basis. The channel is actively migrating across alluvial fans developed within
the aggrading floodplain.
Topographic maps of the accretion area were prepared to 0.5-foot contour intervals by
laser level and tape measure. Abandoned stream channels were mapped along with
approximate jurisdictional wetland extent relative to the water surface within stream
channels. A plan view, cross-sections, and profiles were generated for the channel and
adjacent alluvial surface. The channel dimension, rate of channel migration, and slope of
the floodplain floor represent the primary features extrapolated for use in restoration
planning. The objective of restoration is to reduce the effective size of the Richland
channel to induce sediment deposition, channel migration, braiding, ponding, and/or
anastomosed stream types above the water supply reservoir.
Figure 13 depicts a plan view and cross-sections of the alluvial fan, including locations of
abandoned channels that have developed over the last several years. The channel exhibits
active migration across the valley floor as aggradation processes elevate isolated portions
of the floodplain. The active channel is classified as an E5 (highly sinuous) stream type
in upper reaches of the reference Site. Subsequently, the channel transitions into an
anastomosed (DA5-6) channel and subsequent braided (D6) channel immediately prior to
the confluence with a near-permanently inundated section of the reference reach. This
braided reach and near-permanently inundated area represents projected conditions within
the transition zone into the reservoir conservation pool. The floodplain throughout this
reference reach continues to support forest vegetation, including shrub-scrub dominated
communities within the potentially inundated areas.
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5.0 WETLAND RESTORATION PLAN
This wetland restoration plan has been designed to convert the dredged channel and
adjacent abandoned terrace into an alluvial wetland complex immediately above and
_ within the Randleman Reservoir conservation pool. Components of the plan have been
established based on reference wetland studies described in Section 4.0. This effort will
be performed by: 1) passively saturating/inundating surfaces associated with the
conservation pool; 2) removing constructed stream-side levees; 3) installing in-stream
weirs; 4) scarifying pastured surfaces for reforestation; 5) distributing woody debris into
formerly cleared and pastured areas; and 6) planting of target wetland tree species in the
area. Monitoring of wetland development will be performed to track successional
characteristics of the Site and to verify wetland restoration success.
5.1 PASSIVE SATURATION / INUNDATION FROM THE RESERVOIR POOL
Based on reference studies within existing water supply reservoirs in the region, wetlands
are projected to develop on surface elevations ranging from a minimum of 1 foot below,
to 2 feet above the conservation pool (681-684 feet above MSL). As depicted in Figure
11, shrub/scrub and submerged aquatic vegetation is projected to develop on surfaces
ranging between 681 and 682 feet above MSL, encompassing approximately 7 acres of
land area. This land area is expected to expand into open water portions of the Site over
time as sediment accretion occurs within the reservoir pool (below existing elevations of
681 feet above MSL). However, restoration plans are designed to delay this accretion in
favor of alluvial wetland development outside of the open water area.
Based on reference studies, elevations between 682 and 684 feet above MSL will passively
develop shrub-scrub, bottomland hardwood, and bottomland swamp forest wetlands.
This area encompasses approximately 17 acres within central portions of the Site (Figure
11). These areas will be planted with tree species likely to replace existing elements as
wetland hydrology begins to dominate the area (Section 5.6). Active wetland restoration
will be initiated immediately above wetlands passively restored by the conservation pool.
Because restoration design is dependent upon initial establishment of backwater
conditions in Richland Creek, construction activities associated with placement of in-
stream weirs (Section 5.3) must be performed concurrent with filling of the reservoir.
5.2 CONSTRUCTED LEVEE REMOVAL
The constructed levee adjacent to Richland Creek will be lowered to adjacent floodplain
elevations as depicted in Figure 14. Spoil material will be used to the extent possible for
backfill during construction of in-stream weirs. The remaining material will be hauled to
an appropriate off-site location.
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The levee removal will extend for approximately 2800 feet on both sides of Richland Creek
(1400 feet each side of channel). Based on aerial topographic mapping, the levee
averages approximately 20 feet in width and 3 feet in height, including approximately
170,000 cubic feet (6,000 cubic yards) of excavated material. Surfaces will be stabilized
within the 1 acre area through scarification, mulching, planting of temporary erosion
control elements, and planting of shrub-tree elements as described in Section 5.6.
5.3 IN-STREAM WEIR CONSTRUCTION
In-stream weirs will be installed in the channel at the locations depicted in Figure 14. The
purpose of the weir is to: 1) elevate the base-flow water surface elevations within 1 to 2
¦ feet of the floodplain throughout a majority of the reach; 2) elevate the groundwater table
to within 1 foot of the primary floodplain during portions of the growing season; and 3)
decrease the effective channel cross-sectional area from 237 square feet to an average of
65 square feet under post-restoration conditions. The structures will further modify
energy distributions through decreases in channel slope, designed to increase overbank
flooding and induce sediment deposition onto the floodplain.
Four weirs are proposed with weirs placed at each 2-foot rise in the valley floor. The first
weir has been placed on the valley floor at the 684-foot contour depicted on topographic
mapping. A more accurate placement of this structure can be achieved by observing
actual water surface elevations in the channel resulting from the established conservation
pool. Subsequently, the weir would be accurately placed two feet above the conservation
pool water surface. Figure 15 provides a depiction of the target water surface profile
relative to the conservation pool and channel bed.
The weirs will be constructed of concrete or comparable material large enough to prevent
collapse of the structure during peak flows. The engineering design will ensure that the
weirs are not bypassed until the existing channel has been effectively filled with sediment.
If a structure is abandoned during new channel formation, modifications will be performed
to ensure that return flow does not divert directly back into the channel immediately
below the weir. In the interim period, shoot cut-offs around the weir will steepen the
water surface gradient and potentially short-circuit wetland restoration efforts. The
design or placement of these weirs may be modified during the engineering design phase
based on potential stability, constructability, cost, or other constraints

53

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5.4 SURFACE SCARIFICATION
Before wetland community restoration is implemented, pasture lands will be scarified
(Figure 14). The scarification will be performed as linear bands directed perpendicular to
land slope (surface water flows). After scarification, the soil surface will exhibit complex
microtopography ranging to 1 foot in vertical asymmetry across local reaches of the
landscape. Restored microtopographic relief is considered critical to short term hydrology
restoration efforts. Therefore, multiple passes along each band is recommended to ensure
adequate surface roughing and surface water storage potential across the Site.
Subsequently, community restoration will be initiated on scarified wetland surfaces.
5.5 WOODY DEBRIS DEPOSITION
Re-introduction of woody debris represents an important component of wetland
restoration on pastoral lands. Woody debris, including downed trees, tip mounds, snags,
and decomposing material represents important habitat elements for wetland dependent
wildlife. However, the restoration areas on pasture land will not be capable of providing
coarse, woody habitat elements for up to 50 years after re-planting. Therefore, woody
material generated from levee removal, weir construction, or other activities will be
distributed across future wetland surfaces to the extent feasible. The material may be
lifted or pushed from adjacent windrows or forest areas as well.
5.6 WETLAND COMMUNITY RESTORATION
Restoration of wetland forested communities provides habitat for area wildlife and allows
for development and expansion of characteristic wetland dependent species across the
landscape. Ecotonal changes between community types contribute to diversity and
provide secondary benefits such as enhanced feeding and nesting opportunities for
mammals, birds, amphibians, and other wildlife.

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RFE data, on-site observations, and ecosystem classification has been used to develop the
species associations promoted during community restoration activities. Target plant
community associations include: 1) Piedmont swamp/bottomland hardwood forest and
2) scrub-shrub/Piedmont swamp forest. Figure 16 provides a conceptual depiction of
potential communities projected within the influence of the conservation pool including
emergent, shrub, and forest communities. Figure 17 provides a depiction of projected
communities in upper reaches of the Site, where stream flows will continue to facilitate
establishment of more characteristic bottomland hardwood distributions.
Planting Plan
Emphasis has been focused on developing a diverse plant assemblage. This is particularly
vital due to the limited distribution of mast-producing bottomland hardwood tree species
presently existing in the vicinity, as evidenced during the RFE search. Planting a variety
of mast-producing species will provide a food source for wildlife and will facilitate habitat
diversity on the Site.
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The planting plan consists of: 1) acquisition of available wetland species; 2)
implementation of proposed surface topography improvements; and 3) planting of
selected species on-site. Figure 18 depicts the locations targeted for planting,
encompassing 42.3 acres of land area. Planted species names by community are listed
below.
PiedmontSwamp/Bottomland Hardwood Forest
1. Cherrybark Oak (Quercus pagoda)
2. Overcup Oak (Quercus lyrata)
3. Willow Oak (Quercus phellos)
4. Swamp Chestnut Oak (Quercus michauxii)
5. Swamp Cottonwood (Popu/us heterophylla)
6. Shagbark Hickory (Carya ovata)
7. Bitternut Hickory (Carya cordiformis)
8. Green Ash (Fraxinus pennsylvanica)
9 American Elm (Ulmus americana)
10 Winged Elm (Ulmus alata)
11. Tulip Poplar (Liriodendron tulipifera)
Scrub-Shrub/Piedmont Swamp Forest
1. Black Willow (Salix nigra)
2. Possum-haw (ilex decidua)
3. Carolina holly (flex ambigua)
4. River Birch (Betula nigra)
5. American Sycamore (Platanus occidentalis)
6. Green Ash (Fraxinus pennsylvanica)
7.
8. American Elm (Ulmus americana)
Swamp Cottonwood (Populus heterophylla)
9. Overcup Oak (Quercus lyrata)
10. Swamp Chestnut Oak (Quercus michauxii)
11. Silky Dogwood (Corpus amomum)
12. Button-bush (Cephalanthus occidentalis)
13. Elderberry (Sambucus canadensis)
14. Tag Alder (Alnus serrulata)
Species selected for planting will be dependent upon availability of local seedling sources.
Advanced notification to nurseries (1 year) may facilitate availability of various non-
commercial species. Bare-root seedlings of tree species will be planted within specified
areas at a density of 680 stems per acre (8-foot centers). The total number of stems and
species distribution within each planting association are depicted in Table 6.
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TABLE 6
Planting Plan

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Vegetation Association
(Planting area) Shrub-Scrub/
Swamp Forest Bottomland
Hardwood/
Swamp Forest TOTAL STEMS
PLANTED
Stem Target (trees/ac) 680 680
Area (acres) 9.5 32.8 42.3
SPECIES N planted
(% total) N planted
(% total) # planted
(% total)
River Birch 650(10) 650
Silky Dogwood 65000) 650
Button-bush 650 (10) 650
Elderberry 650 (10) 650
Tag Alder 65000) 650
Black Willow 325(5) 325
Possum-haw 325 (5) 325
Carolina Holly 325 (5) 325
American Sycamore 325 (5) 325
Swamp Cottonwood 650(10) 2250 (10) 2900
American Elm 325 (5) 1125 (5) 1450
Green Ash 325 (5) 1 125 (5) 1450
Swamp Chestnut Oak 325 (5) 2250 (10) 2575
Overcup Oak 325 (5) 2250 (10) 2575
Cherrybark Oak 2250 (10) 2250
Willow Oak 2250 (10) 2250
Shagbark Hickory 2250 (10) 2250
Bitternut Hickory 2250 (10) 2250
Winged Elm 2250 (10) 2250
Tulip Poplar 2250(10) 2250
TOTAL 6500 22300 28800
1: Some non-commercial elements may not be locally available at the time of planting.
The stem count for unavailable species should be distributed among other target
elements based on the percent (%) distribution. One year of advance notice to forest
nurseries will promote availability of some non-commercial elements. However,
reproductive failure in the nursery may occur.
2: Scientific names for each species, required for nursery inventory, are listed in the
mitigation plan.
L
Planting will be performed between December 1 and March 15 to allow plants to stabilize
during the dormant period and set root during the following spring season. Opportunistic
species, which typically dominate early- to mid-successional forests have been excluded
from initial plantings on interior floodplains. Opportunistic species such as sweet gum,
red maple, and loblolly pine may become established. However, to the degree that long
term species diversity is not jeopardized, these species should be considered important
components of steady-state forest communities. Planting of opportunistic species such
as black willow will be targeted as stabilization elements in erosion control areas
immediately adjacent to the creek.
The planting plan is the blueprint for community restoration. The anticipated results
stated in the regulatory success criteria (Section 6.0) may reflect vegetative conditions
achieved after steady-state forests are established over many years. However, the natural
progression through early successional stages of floodplain forest development will prevail
regardless of human interventions over a 5-year monitoring period. In total, approximately
28,800 seedlings will be planted during wetland community restoration efforts.
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6.0 MONITORING PLAN
The Monitoring Plan will entail analysis of the restoration area according to jurisdictional
wetland criteria (DOA 1987). Monitoring will include the observation and evaluation of
three primary parameters including hydrology, soil, and vegetation. Monitoring of
restoration efforts will be performed for 5 years or until success criteria are fulfilled.
6.1 HYDROLOGY
After hydrological modifications are performed, surficial monitoring wells will be designed
a and placed in accordance with specifications in U.S. Corps of Engineers', Installing
Monitoring Wells/Piezometers in Wetlands (WRP Technical Note HY-IA-3.1, August 1993).
Monitoring wells will be set to a maximum depth of 24 inches below the soil surface. All
screened portions of the well will be buried in a sand screen, filter fabric, and/or a
bentonite cap to prevent siltation during floods. Recording devices (if used) will be placed
five feet above the ground elevation. Placement of recording devices at this height should
guard against over topping for a projected 50-year flood elevation. The well will be
stabilized from flood shear by reinforcing steel bar (re-bar).
Eight monitoring wells will be installed in restoration areas to provide representative
coverage throughout the site. Approximate well locations are depicted in Figure 19.
Hydrological sampling will be performed during the growing season (March 26 to
November 6) at intervals necessary to satisfy the hydrologic success. In general, the wells
will be sampled weekly through the spring and early summer and intermittently through
the remainder of the growing season, if needed to verify success.
6.2 HYDROLOGY SUCCESS CRITERIA
Target hydrological characteristics have been evaluated using regulatory wetland
hydrology criteria. The regulatory wetland hydrology criterion requires saturation (free
water) within one foot of the soil surface for 5% of the growing season under normal
climatic conditions.
Success Criteria
Under normal climatic conditions, hydrology success criteria comprises saturation (free
water) within 1 foot of the soil surface for a minimum of 5% of the growing season. This
hydroperiod translates to saturation for a minimum, 1 1-day (5%) consecutive period during
the growing season, which extends from March 26 through November 6 (USDA 1977).
If wetland parameters are marginal as indicated by vegetation and hydrology monitoring,
a jurisdictional determination will be performed in the questionable areas.
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6.3 SOIL
Mitigation activities are expected to increase the deposition and transport of river and
stream sediments during overbank flood events. As a result, soils (Fluvaquents) are
continuously reworked by fluvial processes. Because iron reduction rates (gleying) are not
spatially or temporally uniform on recent alluvial deposits, soil color or other visual, hydric
soil properties are not considered suitable for quantitative wetland soil monitoring/success
criteria on active river floodplains.
Soil monitoring will entail measurement of sediment accretion/reduction (aegradation/
degradation) at the location of each monitoring well and other hydraulically active areas
as identified by Site managers. Mitigation activities are designed to provide for flood and
sediment storage from the watershed. Therefore, hydraulic and energy dissipation
patterns should be distributed throughout as much of the Site as possible. However, an
area of particularly accelerated sediment deposition may raise land surfaces above the
elevation of the primary wetland floodplain over a relatively short period of time.
Conversely, deep scour holes or head-cuts may form in locations where flow velocity or
sediment deficits exceed a "normal distribution." Soil monitoring is designed to provide
a cursory review to predict the need for additional levee openings or drainageways if
accelerated deposition or scour potentially jeopardizes wetland restoration efforts.
The re-bar used to support monitoring wells will be marked upon installation and in each
monitoring year at the elevation of the existing ground surface. In addition, the height
of silt lines will be recorded to predict the depth of inundation during the flood period.
Additional re-bar will be placed and measured in high energy areas identified by Site
managers, as needed. The change in elevation of the alluvial surface and deposition/scour
patterns relative to flood elevations will be recorded and compared to previous years.
1 6.4 SOIL SUCCESS CRITERIA
Success criteria require that the deposition/scour rate not exceed over 1 foot change in
surface elevations in any given year. Any areas affected by this excessive deposition/scour
will be mapped in the field. The area will be reviewed to determine modifications to
drainage patterns that should be implemented, if any. Changes in surface elevations of
less than 1 foot per year will meet regulatory success criteria; however, modifications to
deposition / scour patterns may also be considered in certain circumstances.
6.5 VEGETATION
Restoration monitoring procedures for vegetation are designed in accordance with EPA
guidelines presented in MiST documentation (EPA 1990) and Compensatory Hardwood
Mitigation Guidelines (DOA 1993). The following presents a general discussion of the
monitoring program.
0
64

Vegetation will receive cursory, visual evaluation during periodic reading of monitoring
wells to ascertain the general conditions and degree of competition or overtopping of
planted elements. Subsequently, quantitative sampling of vegetation will be performed
once annually during the fall (September/November) for 5 years or until vegetation success
criteria are achieved. Sampling dates may be modified to accommodate river flood events
and plot inundation, as needed.
During the first sample event, a visual survey will be performed in the reference wetlands
to identify all canopy tree species represented within target communities. These reference
tree species will be utilized to define "character tree species" as termed in the success
criteria.
Permanent (on each well head) or nonpermanent, randomly placed plots will be
established at representative locations in the restoration areas. Each plot will consist of
two, 300-foot transects extending at a randomly selected compass bearing from a central
origin. The plot width along the transect will extend 4-feet on each side of the tape,
providing a 0.11 acre plot sample at the location (600 feet x 8 feet / 43560 square
feet/acre). Sixteen plots will be established to provide a 4% sample and a depiction of
tree species available for current and future seed sources within the restoration area. In
each plot, tree species and number of stems will be recorded and seedling/sapling/tree
height measured. Tree data from all plots will be combined into one database to calculate
an average density, by species, represented in restoration areas of the Site.
In each plot, presence/absence of shrub and herbaceous species will be recorded. A
wetland data form (DOA 1987) will be completed to document the classification and
description of vegetation, soil, and hydrology.
6.6 VEGETATION SUCCESS CRITERIA
Success criteria include the verification, per the wetland data form, that each plot
supports a species composition sufficient for a jurisdictional determination. Additional
success criteria are dependent upon density and growth of "Character Tree Species."
"Character Tree Species" are identified through visual inventory of reference wetland
communities used to orient the restoration project design. All canopy tree species
identified in the reference wetland will be utilized to define "Character Tree Species" as
termed in the success criteria (Character Tree Species are generally listed in Section 4.5
and Section 5.6).
An average density of 320 stems per acre of Character Tree Species must be surviving in
the first three monitoring years. Subsequently, 290 stems per acre of character tree
species must be surviving in year 4, and 260 stems per acre of Character Tree Species in
year 5. Each individual species is limited to representing up to 20% of the 320 stem per
0
65

77

acre total. Additional stems of a particular species above the 20% threshold are discarded
from the statistical analysis. In essence, a minimum of five different character tree species
must be present with each species representing up to 20% of the 320 stem per acre total.
If vegetation success criteria are not achieved based on average density calculations from
combined plots over the entire restoration area, those individual plots that do not support
the stem per acre requirement and the representative area will be identified. Supplemental
planting will be performed in the identified area as needed until vegetation success criteria
are achieved.
No quantitative sampling requirements are proposed for herb assemblages. Development
of a forest canopy over several decades and restoration of wetland hydrology will dictate
success in migration and establishment of desired wetland understory and groundcover
populations.
6.7 REPORT SUBMITTAL
An Annual Wetland Monitoring Report (AWMR) will be prepared at the end of each
monitoring year (growing season). The AWMR will depict the sample plot and quadrant
locations and include photographs which illustrate site conditions. Data compilations and
analyses will be presented as described in Sections 6.1 through 6.6 including graphic and
tabular format, where practicable. Raw data in paper or computer (EXCEL) file format will
be prepared and submitted as an appendix or attachment to the AWMR.

66
0
7
9
0 7.0 IMPLEMENTATION SCHEDULE
Project implementation will include performance of restoration work in three primary
stages including: 1) levee removal, weir construction, and site preparation; 2) tree and
shrub planting; and 3) monitoring plan implementation. This mitigation plan or
implementation schedule may be modified based upon civil design specifications, permit
conditions, or contractor limitations.
Stage 1: Levee Removal, Weir Construction, and Site Preparation
Stage 1 will be performed concurrent with or subsequent to filling of the reservoir. Levees
will be excavated and weirs constructed along the dredged channel. This work will be
performed during late spring and/or early summer months to reduce erosion hazards
associated with saturated soil or large August storms. Site preparation will be performed
during the same summer period, prior to tree planting.
Stage 2: Tree Planting
Tree and shrub planting will be performed the first winter after stage 1 is complete. The
seedlings will be planted during the winter dormant period, prior to March 1.
Stage 3: Monitoring Plan Implementation
Monitoring wells and permanent vegetation plots will be established immediately after
construction and planting activities are completed (prior to March 26, the start of the
growing season). The Site will be visited frequently to read monitoring wells and to
evaluate wetland development during the first growing season. Vegetation sampling and
hydrology monitoring will be completed by November 6 (the end of the growing season).
The first year of monitoring would be completed upon submittal of the Annual Wetland
Monitoring Report and fulfillment of success criteria. The monitoring sequence will be
repeated as described for four additional years or until success criteria are achieved.
r-+

67

0
8.0 DISPENSATION OF PROPERTY
PTRWA will maintain ownership of the property until all mitigation activities are
completed or until the Site is determined to be successful. Although no plan for
dispensation of the Site has been developed, PTRWA may continue to manage the
property or may deed the property to a resource agency (public or private) acceptable to
the appropriate regulatory agencies. Covenants and/or restrictions on the deed will be
included that will ensure adequate management and protection of the Site in perpetuity.

68

9.0 WETLAND FUNCTIONAL EVALUATIONS
Mitigation activities at the Richland Creek Mitigation Site should be determined based on
wetland functions generated and a comparison of restored functions to potentially
impacted wetland resources. Therefore, an evaluation of mitigation wetlands, by
physiographic area (Figure 4), is provided to evaluate site utility for mitigation in the
region.
9.1 EXISTING CONDITIONS
Under existing conditions, hydrodynamic functions have been degraded or effectively
eliminated due to stream dredging, levee construction, soil leveling/compaction in pasture
areas, and removal of characteristic vegetation. Features which depict performance of
hydrodynamic wetland functions such as surface microtopography, seasonal ponding,
meandering stream channels, and characteristic wetland vegetation have been reduced or
eliminated by alternative land uses on primary floodplains. Reduction or elimination of
wetland hydrology has also negated nutrient cycling and biological functions within the
complex. These former wetlands do not support natural communities adapted to wetlands
or the wetland dependent wildlife characteristic in the region.
The 70.5-acre site supports 13.6 acres of relict wetlands within backwater areas and 4.0
acres of open water within the dredged channel (17.6 total acres). Of the existing
wetlands, approximately 1.9 acres are included as wetland impacts under the 404 Permit
Application for this project. Therefore, 11.7 acres of existing wetlands will be preserved
or enhanced during mitigation activities (Figure 20).
9.2 PROJECTED, POST-RESTORATION CONDITIONS
Lake Effect Wetlands
Wetland restoration objectives have been adapted for this project due to location of the
Site relative to the Randleman Reservoir. The lower half of the Site will be directly
influenced by the reservoir conservation pool, including sediment deposition within stream
channels, development of accreting sediment bars, and establishment of wetlands on
saturated/inundated surfaces. Based on reference studies, these lake effect wetlands are
projected to support a mosaic of emergent, shrub-scrub, and forested wetland
communities on land surfaces from 1 foot below to 2 feet above the conservation pool.
This land area, comprising approximately 24.0 acres, will provide wetland functions such
as increased habitat for wetland dependent wildlife, sediment retention above the water
supply, and pollutant processing on vegetated wetland surfaces. Open water is also
projected to encompass approximately 13.0 acres that will provide for sediment storage
and accreting wetland shorelines (Figure 20).

69

0
Monitoring and management of these lake effect wetlands will assist in ensuring that land
• surfaces exposed to long-term sedimentation are not elevated above the water table, with
capacity to support wetland functions subsequently reduced or diminished over time. In
addition, efforts to maintain vegetation within rapid sedimentation areas will also be
employed during the monitoring period.
Alluvial Wetland Complex
The upper half of the Site will be used to extend the sediment deposition wedge
associated with the reservoir and to establish wetland communities capable of providing
wildlife habitat and water quality benefits. Overbank flooding is projected to occur at a
1-year return interval through levee removal and placement of in-stream weirs. Assuming
weir stability, the dredged channel is expected to fill in with sediment over time,
facilitating passive stream restoration and migration across the developing alluvial fan.
The primary and secondary floodplain areas are expected to support an array of forested
wetland communities, providing replacement of habitat for wetland dependent species
displaced by the reservoir. Water quality benefits are projected to include sediment
retention and pollutant processing of waters generated by the 14.5-square mile, urbanizing
watershed.
Pro-active mitigation within the alluvial wetland complex is projected to provide
approximately 21.8 acres of wetland restoration above the lake effect, wetland restoration
area (an additional 24.0 acres). Therefore, 45.8 acres of wetland restoration, 11.7 acres
of wetland preservation/enhancement, and 13 acres of open water are potentially provided
by the Site.

70
0
?L*
10.0 REFERENCES
Baumer, 0. and J. Rice. 1988. Methods to predict soil input data for DRAINMOD ASAE
Paper No. 88-2564. ASAE, St. Joseph, MI 49085.
Beets, C.P. 1992. The relation between the area of open water in bog remnants and
storage capacity with resulting guidelines for bog restoration. (in) Peatland Ecosystems
and Man: An Impact Assessment. (ed.) 0. M. Bragg, P. D. Hulme, H. A. P. Ingram, and
R.A. Robertson. International Peat Society. University of Dundee, Dundee, Scotland.
Belcher, H.W. and G.E. Merva. 1987. Results of DRAINMOD verification study for
Zeigenfuss soil and Michigan climate. ASAE Paper No. 87-2554. ASAE, St. Joseph, MI
49085.
Brinson M.M., F.R. Hauer, L.C. Lee, W.L. Nutter, R.D. Smith, D. Whigham. 1995.
Guidebook for Application of Hydrogeomorphic Assessments to Riverine Wetlands. U.S.
Army Corps of Engineers Waterways Experiment Station. Vicksburg, MS.
Brinson, M.M. 1993a. Changes in the functioning of wetlands along environmental
gradients. Wetlands 13(2): 65-74, Special Issue, June 1993. The Society of Wetland
Scientists.
Brinson M.M. 1993b. A Hydrogeomorphic Classification for Wetlands. Wetlands
Research Program Technical Report WRP-DE-4. U.S. Army Corps of Engineers Waterways
Experiment Station. Vicksburg, MS.
Brinson M., B. Swift, R. Plantico, J. Barclay. 1981. Riparian Ecosystems: Their ecology
and status. U.S. Fish and Wildlife Service FWS/OBS 81 /17
Brower, J.E., J.H. Zar, C.N. von Ende. 1990. Field and Laboratory Methods for General
Ecology. William C. Brown Publishers, Debuque, IA.
Brown, Philip M., et al. 1985. Geologic Map of North Carolina, North Carolina
Department of Natural Resources and Community Development, 1-.500,000 scale.
Chang, Howard H. 1988. Fluvial Processes in River Engineering. John Wiley & Sons.
Department of the Army (DOA). 1993 (unpublished). Corps of Engineers Wilmington
District. Compensatory Hardwood Mitigation Guidelines (12/8/93).
Li?--' I" I
71
I?J?
I
Department of the Army (DOA). 1987. Corps of Engineers Wetlands Delineation Manual.
Tech. Rpt. Y-87-1. US Army Engineer Waterways Experiment Station, Vicksburg, MS.
Division of Water Quality (DWQ). 1998. Classifications and Water Quality Standards
Assigned to the Waters of the Cape Fear River Basin, N.C. Department of Environment and
Natural Resources, Raleigh, N.C.
Division of Water Quality (DWQ). 2000 (draft). Cape Fear River Basinwide Water Quality
Plan. North Carolina Department of Environment and Natural Resources. Raleigh, N.C.
rn Division of Water Quality (DWQ). 1996. Water Quality Certification Administrative Code
• Section: 15A NCAC 2H.0500 as amended October 1, 1996. North Carolina Department
of Environment and Natural Resources.
Dunne D. and L.B. Leopold. 1978. Water in Environmental Planning. W.H. Freeman and
Company, N.Y.
EcoScience Corporation (ESC). 1998a (unpublished). Preliminary Groundwater Drainage
Model: Randleman Reservoir Mitigation Sites, Guilford County, North Carolina. Raleigh,
N. C.
EcoScience Corporation (ESC). 1998b (unpublished). Preliminary Wetland Mitigation
Assessment: Randleman Reservoir, Guilford and Randolph Counties, North Carolina.
Raleigh, N.C.
EcoScience Corporation (ESC). 1999 (unpublished). Wetland Mitigation Plan: Randleman
Reservoir, Guilford and Randolph Counties, North Carolina. Raleigh, N.C.
Environmental Protection Agency (EPA). 1990. Mitigation Site Classification (MIST) A
Methodology to Classify Pre-Project Mitigation Sites and Develop Performance Standards
for Construction and Restoration of Forested Wetlands. USEPA Workshop, August 13-15,
1989. USEPA Region IV and Hardwood Research Cooperative, North Carolina State
University, Raleigh, NC.
Fouss, J.L., R.L. Bengtson and C.E. Carter. 1987. Simulating subsurface drainage in the
lower Mississippi Valley with DRAINMOD. Transactions of the ASAE 30 (6).(1679 -1688).
Gayle, G., R.W. Skaggs and C.E. Carter. 1985. Evaluation of a water management model
for a Louisiana sugar cane field. J. of Am. Soc. of Sugar Cane Technologists, 4: 18 - 28.
Graham County Historical Society, 1992. Graham County Heritage. Robbinsville, NC.
0
72

1??57-li
Harman, W.A., G.D. Jennings, J.M. Patterson, D.R. Clinton, L.A. O'Hara, A. Jessup, R.
Everhart. 1999. Bankfull Hydraulic Geometry Relationships for North Carolina Streams.
N.C. State University, Raleigh, North Carolina.
Hvorslev, M.J. 1951. Time lag and soil permeability in groundwater observations. U.S.
Army Corps of Engineers Waterways Experimental Station Bulletin 36, Vicksburg, MS.
Keller, M.E., C.S. Chandler, J.S. Hatfield. 1993. Avian Communities in Riparian Forests
of Different Widths in Maryland and Delaware. Wetlands 13(2):137-144, Special Issue,
June 1993. The Society of Wetland Scientists.
North Carolina Department of Transportation (NCDOT). 1994a; unpublished.
Determination of applicable mitigation credit For restoration of wetland buffers and
wetland/upland ecotones: US 64 wetland restoration and conservation management plan,
US 64 relocation, Martin and Edgecombe Counties, North Carolina. N.C. Department of
Transportation. Raleigh, N.C.
Nunnally, N.R.,E. Keller. 1979. Use of Fluvial Processes to Minimize Adverse Effects of
Stream Channelization. Water Resources Research Institute of the University of North
Carolina. Report No. 144.
Page, R.W. and L.S. Wilcher. 1990. Memorandum of Agreement Between the EPA and
the DOE Concerning the Determination of Mitigation Under the Clean Water Act, Section
404(b)(1) Guidelines. Washington, DC.
Rohde, F. C., R. G. Arndt, D. G. Lindquist, and J. F. Parnell. 1994. Freshwater Fishes of
the Carolinas, Virginia, Maryland, and Delaware. The University of North Carolina Press,
Chapel Hill, NC. 222 pp.
Rogers, J.S. 1985. Water management model evaluation for shallow sandy soils.
Transactions of the ASAE 28 (3): 785-790.
Rosgen, D. 1996. Applied River Morphology. Wildland Hydrology (Publisher). Pagosa
Springs, Colorado.
Schafale, M. P., A.S. Weakley. 1990. Classification of the Natural Communities of North
Carolina: Third Approximation, NC Natural Heritage Program, Division of Parks and
Recreation, NC DEM, Raleigh NC.
0
73

0
Schouwenaars, J.M. 1995. The selection of internal and external water management
options for bog restoration. (in) Restoration of Temperate Wetlands. (ed.) B. D. Wheeler,
S. C. Shaw, W. J. Fojt, and R. A. Robertson. John Wiley & Sons, Ltd. West Sussex,
England.
Simmons, C.E. 1976. Sediment Characteristics of Streams in the Eastern Piedmont and
Western Coastal Plain Regions of North Carolina. U.S. Geological Survey Water Supply
Paper, W 1798-0,p. 01-032. Reston Va.
Skaggs, R.W. 1982. Field Evaluation of a Water Management Simulation Model.
Transactions of the ASAE 25 (3), pp 666-674.
Skaggs, R.W., N.R. Fausey, B.H. Nolte. 1981. Water Management Evaluation for North
Central Ohio. Transactions of the ASAE 24 (4), pp 922-928.
Skaggs, R.W., J.W. Gilliam, R.O. Evans. 1991. A Computer Simulation Study of Pocosin
Hydrology. Wetlands (11), pp 399-416.
Skaggs, R.W., et al. 1993. Methods for Evaluating Wetland Hydrology. ASAE Meeting
Presentation Paper No. 921590. 21 p.
Smith, R.D., A. Ammann, C. Bartoldus, M.M. Brinson. 1995 (unpublished). An Approach
for Assessing Wetland Functions Using Hydrogeomorphic Classification, Reference
Wetlands, and Functional Indices. Wetlands Research Program Technical Report WRP DE-
US Army Engineer Waterways Experiment Station, Vicksburg, MS
Strahler, A.N. 1964. Geology. Part II. Quantitative geomorphology of drainage basins
and channel networks. (in) Handbook of Applied Hydrology. (ed. V.T. Chow), pp. 4-39
to 4-76, McGraw Hill, New York.
Susanto, R.H., J. Feyen, W. Dierickx, G. Wyseure. 1987. The Use of Simulation Models
to Evaluate the Performance of Subsurface Drainage Systems. Proc. of the Third
International Drainage Workshop, Ohio State University, OH. pp. A67 - A76.
U.S. Department of Agriculture (USDA). 1987. Hydric Soils of the United States. In
cooperation with the National Technical Committee for Hydric Soils, USDA Natural
Resource Conservation Service.
U.S. Department of Agriculture (USDA). 1977. Soil Survey of Guilford County, North
Carolina. Natural Resource Conservation Service.
0
74
11
U.S. Department of Agriculture (USDA). 1970. Soil Survey of Wake County, North
Carolina. Natural Resource Conservation Service
U.S. Fish and Wildlife Service. 1994. Schweinitz's Sunflower Recovery Plan. Atlanta,
GA. 28 pp.
U.S. Fish and Wildlife Service (USFWS). 1988. Cape Fear Shiner Recovery Plan. U.S.
Fish and Wildlife Service, Atlanta, GA. 18 pp.
U.S. Geological Survey. 1974. Hydrologic Cataloging Unit Map for the State of North
Carolina.
U.S. Geological Survey. 1982. 7.5 minute, High Point East 1:24000 Quadrangle.
Yoakum, J., W.P. Dasmann, H.R. Sanderson, C.M. Nixon, and H.S. Crawford. 1980.
Habitat Improvement Techniques. Pp 329-403 in S.D. Schemnitz (Editor). Wildlife
Management Techniques Manual, 4th ed., rev. The Wildlife Society, Washington, DC
686 pp.