20081317 Ver 1_More Info Received_20090724

PotashCorp Jul 4 2SCQ
Helping Nature Provide
DENR - WATER QUALITY
JyETL4':0S AND 5T ORNAl,';IrEft BRANCH
July 21, 2009
Mr. Doug Huggett
Major Permits Coordinator
NC Division of Coastal Management
400 Commerce Avenue
Morehead City, NC 28557-3421
Re: PCS Phosphate Revised Hell Swamp Mitigation Plan
Dear Mr. Huggett:
On July 15, a meeting was held with representatives from the Corps of Engineers, NC
Division of Coastal Management, NC Division of Water Quality and PCS, to review the
mitigation plan for the PCS Phosphate Hell Swamp mitigation site in Beaufort County.
This plan is Attachment D located within the larger notebook containing the complete
application for a CAMA Major permit for the Hell Swamp project, which was submitted
to DCM in early May. Several edits and modifications were made to the text of the
mitigation plan during the meeting. No figures or construction plans were changed.
Enclosed please find two (2) copies of the revised Attachment D, dated July 2009, for
your use in completing the permit action. Note that copies are being sent directly to the
Raleigh and Washington DWQ offices and the Washington DCM office.
If you have any questions, please call me at [phone], or e-mail me at
[e-mail].
Sincerely, l J frey C. Furness
Senior Scientist
Enclosure
pc: D. Moye, DCM-Wash. w/encl.
K. Barnes, DWQ-Wash. w/encl.
T. Hill/E. Kulz, DWQ-Raleigh w/encl.
T. Wheeler, Corps-Wash. w/o encl.
S. Cooper, CZR w/encl.
J. Hudgens, CZR w/encl.
J. Ricketts w/encl.
K. Tweedy, Baker w/encl.
File: 23-11-019 w/encl.
1530 NC Hwy 306 South, Aurora, NC USA 27806 T [phone]
PCS Phosphate I www.potashcorp.com
. COMPENSATORY MITIGATION PLAN
FOR RESTORATION OF THE
HELL SWAMP/SCOTT CREEK WATERSHED
•
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JUL 2 4 2jC9
DENR - WATER QUALITY
WETLAUDS AND STORii WATER BRANCH
PANTEGO TOWNSHIP
BEAUFORT COUNTY, NORTH CAROLINA
1% . 'qq
------ ------
Prepared for:
PCS PHOSPHATE COMPANY, INC.
Environmental Affairs Department
Aurora, North Carolina
Prepared by:
CZR INCORPORATED
Wilmington, North Carolina
and
Michael Baker Engineering, Inc.
Cary, North Carolina
and
Jonathan T. Ricketts, Inc.
Palm Beach Gardens, FL
4) July 2009
• TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY ................................................................................................ 1
1.0 INTRODUCTION .................................................................................................... 1
2.0 LOCATION, HISTORY, AND PRE-RESTORATION DESCRIPTION ...................... 1
2.1 Location .............................................................................................................1
2.2 History ............................................................................................................. ..2
2.3 Pre-Restoration Description ............................................................................. .. 2
2.3.1 Soils ........................................................................................................ ..2
2.3.2 Pre-restoration Drainage and Section 404 Jurisdictional Status ............... .. 3
2.3.3 Woodland Areas ...................................................................................... .. 3
2.3.4 Vegetated Non-forested Areas ................................................................ .. 3
2.3.5 Cleared Areas .......................................................................................... .. 4
2.3.6 Agricultural Fields .................................................................................... .. 4
2.3.7 Protected Species ................................................................................... .. 4
2.3.8 Cultural Resources .................................................................................. .. 4
3.0 SITE SELECTION FACTORS AND JUSTIFICATION .......................................... .. 4
3.1 Logistics .......................................................................................................... .. 4
3.2 Cost and Technology ........................................................................................ .. 5
3.3 Justification ...................................................................................................... ..5
3.3.1 Jurisdictional Status of Woodland and Cleared Areas .............................. .. 5
4.0 SPECIFIC GOALS, TARGET FUNCTIONS
AND METHODS ................
. 5
,
.
...........
4.1 Goals.... .................................................................................................. ..
..5
4.2 Target Functions .............................................................................................. .. 6
4.3. Methods ........................................................................................................... ..8
4.3.1 Agricultural Areas .................................................................................... .. 8
4.3.2 Woodland Areas ...................................................................................... .. 8
4.3.3 Vegetated Unforested Areas .................................................................... .. 8
4.3.4 Cleared Areas .......................................................................................... .. 9
5.0 WORK PLAN METHODOLOGY ........................................................................... .. 9
5.1 Hardwood Flats ................................................................................................ 10
5.1.1 Hydrologic Model ..................................................................................... 10
5.1.2 Water Budget .......................................................................................... 10
5.1.2.1 Meteorology-Climatic Inputs and Evapotranspiration ........................ 10
5.1.2.2 Water Budget Outputs ...................................................................... 10
5.1.3 Proposed Restoration of Surface Contours .............................................. 11
5.2 Streams and Riparian Headwater Systems ...................................................... 11
5.2.1 Historic Aerials ......................................................................................... 11
5.2.2 Topographic Data .................................................................................... 12
5.2.3 Identified Project Reaches ....................................................................... 12
5.2.4 Coastal Plain Riparian Headwater Systems Reference Site Analyses..... 13
5.2.5 Design Approach and Techniques ........................................................... 19
6.0 PLANTING DESIGN ............................................................................................ 22
7.0 DATA COLLECTION FOR MONITORING AND SUCCESS CRITERIA ............... 23
7.1 Riparian Headwater Systems (Zero to First Order Stream Systems) ............... 23
7.2 Vegetation Monitoring Plots ................................................................. 24
............
7.2.1 Volunteer Woody Vegetation Sampling .................................................... 24
PCS Compensatory Mitigation Plan i Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
7.2.2 Vegetation Ecological Performance Standards ........................................ 25
7.3 Hydrology Monitoring .................................... 25
7.3.1 Wetland Hydrological Ecological Performance Standard and Growing
Season .................................................................................................... 27
7.4 Hydrogeomorphic Monitoring of Streams and Valleys ...................................... 27
7.4.1 Hydrogeomorphic Stability ....................................................................... 27
7.5 Reference Forest Wetland ............................................................................... 27
7.6 Reference Stream Reach and Reference Riparian Headwater System ........... 28
7.7 Areas Mapped as Upland on the Beaufort County Soil Survey ........................ 28
7.8 Summary of Performance Criteria .................................................................... 28
8.0 ADAPTIVE MANAGEMENT STRATEGIES .......................................................... 31
8.1 Adaptive Management ..................................................................................... 31
8.2 Long Term Management .................................................................................. 32
9.0 FINAL DISPOSITION OF SITE ............................................................................ 32
REFERENCES ............................................................................................................. 34
Cover: View of eastern half of Hell Swamp; towards Pungo Creek with Pungo River in
distance.
LIST OF CHARTS
Chart 1 Headwater reference reach data relating channel formation to drainage
area and slope .............................................................................17
LIST OF TABLES
Table 1 General functions of Coastal Plain headwater systems .........................18
Table 2 Summary of reach/segment characteristics, lengths, and design channel
forms for project stream reaches ......................................................21
Table 3 Restored wetland or stream functions and measurement
methods ......................................................................................24
Table 4 List of appropriate colonizing woody species within the Hell Swamp
mitigation site (in addition to any volunteers of planted species) ..............25
Table 5 Performance criteria and methods summary ....................................29
LIST OF FIGURES
Figure 1 Hell Swamp Vicinity Map
Figure 2 Site Map 1998 Infrared Aerial
Figure 3 Site Map 2006 Aerial
Figure 4a Soils
Figure 4b Soils as Shown in the Beaufort County Soil Survey
Figure 5 LIDAR Hell Swamp
PCS Compensatory Mitigation Plan ii Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
Figure 6
Figure 7
Figure 8a
Figure 8b
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Jurisdictional Wetlands, Waters, and Streams on Hell Swamp Mitigation
Site
Site Plan with Phase 1 Limits of Disturbance and Access Roads
Cross Section Map
Cross Sections of Lower Scott Creek and UT4- Existing Conditions
Stream Mitigation Plan Map Hell Swamp Site
Stream Reference Site Map Hell Swamp Site
Planting Plan
Monitoring Well Location Map
Hell Swamp and Scott Creek Watershed Wetland, Stream, and Riparian
Buffer Mitigation Site
SUPPORTING DOCUMENTS
A Beaufort County Parcel Information
B Selected Site Photographs Including Historic Aerials
C Agency Correspondence:
1 - Soil Fertility Report
2 - Schafale Report on Wet Hardwood Forest Preservation Parcel and
Potential Reference Forest
3 - NRCS Letter on PC Status
4 - USDOI/USFWS Letter
5 - NCNHP Letter
6 - NCSHPO Letter
7 - Limits of CAMA Jurisdiction
D Hell Swamp Site Existing Condition Stream Cross Sections
E Hell Swamp Site Work Plans and Baker Technical Memorandum
F Hell Swamp Hydrologic Model Analysis Summary
•
PCS Compensatory Mitigation Plan Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
0 EXECUTIVE SUMMARY
The Hell Swamp Scott Creek Watershed mitigation site will provide a broad
range of wetland and stream mitigation opportunities. The five tracts that make up this
property (1,297 acres) were purchased by PCS Phosphate Company Inc. in 2006, 2007,
and 2008. Since the site encompasses almost the complete Scott Creek watershed and
a portion of the watershed of Smith Creek, it should be resilient to external and upstream
perturbations that can sometimes jeopardize mitigation projects.
Most of the site consists of hydric mineral soils, with some notable examples of
low-lying, albeit non-hydric soil areas. The site drains through channelized stream
remnants and into the disturbed and channelized Scott Creek. Scott Creek, portions of
which are tidal on the Hell Swamp site, empties into Pungo Creek, a Special Secondary
Nursery Area. Approximately 19,783 linear feet (LF) of stream will be restored or
enhanced, including the restoration of several riparian headwater systems.
Approximately 21 acres of Tar-Pamlico riparian buffer will be restored or enhanced, with
additional potential buffer opportunity of 21 acres if suitable stream segments form in the
riparian headwater systems. Riparian forested hardwood wetland will be restored on
about 58 acres with some additional enhancement potential. Non-riparian forested
wetland will be restored on 808 acres, with the balance of the site included as
preservation of existing forested wetland (40 acres) and the planting of 200 acres of
upland to mixed hardwood for a more diverse habitat. Areas underlain by hydric soils
which may be effectively drained by perimeter ditches and which will remain open post-
construction total 103 acres. Approximately 34 acres at the head of the watershed is
mature non-riverine wet hardwood forest, and will be preserved to help mitigate for
impacts to the Bonnerton non-riverine wet hardwood area.
A CAMA major regulatory permit application was submitted in May 2009 for all
work proposed to occur in CAMA, Corps, or NCDWQ jurisdictional areas, including
buffers. This project is expected to be constructed in 2009 and planted in early 2010.
1.0 INTRODUCTION
The 1,297-acre Hell Swamp site is proposed to be part of the compensatory
mitigation for future unavoidable impacts to wetlands and waters as evaluated in the
Final Environmental Impact Statement for PCS Phosphate Mine Continuation (US Army
Corps of Engineers 2008) and as described in the Compensatory Section 404/401
Mitigation Plan: Comprehensive Approach In Support of the PCS Phosphate Company,
Inc. L Alternative Mine Continuation (First 15 Years NCPC and Bonnerton Tracts) (PCS
Phosphate Company Inc. 2008, Volume III, Appendix 1). This document describes the
Hell Swamp site and proposed restoration activities (a more detailed version of the draft
plan contained in Attachment 8 of Appendix I, Volume III of the 2008 PCS FEIS).
2.0 LOCATION, HISTORY, AND PRE-RESTORATION DESCRIPTION
• 2.1 Location. The Hell Swamp site is located on the southwest side of Seed
Tick Neck Road (SR 1714) south of NC Highway 264 in Beaufort County. There are two
PCS Compensatory Mitigation Plan 1 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
entrances to the site located approximately 1.7 and 2 miles south of Highway 264 on
Seed Tick Neck Road. The site is located approximately 2 miles east-southeast of the
town of Yeatesville, Pantego Township, North Carolina (straight-line distance) and can
be found on the USGS Pantego quadrangle (Figure 1). The approximate center of the
site is located at +35.522856 latitude and -76.680750 longitude (35°31'22.28"N and
76°40'59.70"W). The site is located within the Pamlico Hydrologic Unit 03020104 of the
Tar-Pamlico river basin within the Pungo Creek subbasin and is drained by Scott Creek
and Smith Creek.
2.2 History. The five tracts that make up this property were purchased in 2006,
2007, and 2008 (refer to Supporting Document A). The majority of this site has been in
agricultural production for several decades. Historic aerial photographs indicate that,
except for a small field in the northern part of the property, the site was forested until
Scott Creek was dredged and relocated in the 1960s and 1970s. An extensive network
of ditches and canals was added in subsequent years, rendering the majority of the site
suitable for agriculture. A northern portion of the site remained forested until the 1990s.
This portion of the property was in the process of being cleared and drained when it was
obtained by PCS Phosphate, Inc. In the southeastern corner of the site there are also
some wooded areas associated with Scott and Smith Creek that have been logged, but
never put into agricultural production.
2.3 Pre-Restoration Description. Farm access roads cross the site at various
angles creating a mosaic of fields, which are further divided by canals and ditches
(Figure 2). Scott Creek and Smith Creek carry water southeast from this site, under NC
Highway 99 and Pungo Creek Road (SR 1715), respectively, and into Pungo Creek.
Portions of Scott Creek are ditched and/or devoid of riparian buffer (Figure 3). The
major portion of this site (approximately 1,002 acres) has been in active cultivation since
the 1970's. Approximately 157 additional acres were cleared and ditched within the past
15 years, and approximately 148 acres are covered by timber and/or shrub-scrub
habitat. Crop rotations in the active agricultural fields have included cotton, soybeans,
corn, and winter wheat (refer to photographs in Supporting Document B).
2.3.1 Soils. Most of the site is underlain by hydric mineral soils and low-
lying non-hydric soils. Approximately 85 percent of soils on the site are hydric (1,105
acres). According to the NRCS soil survey for Beaufort County, the major soil series
mapped on the site are comprised of loams and sandy loams in the Arapahoe- Ponzer-
Dare and Augusta-Altavista-Tomotley soil units (Kirby, 1995). Approximate acreages of
the following soils series are on the site: Arapahoe fine sandy loam (419 acres),
Portsmouth loam (196 acres), Dragston fine sandy loam (185 acres), Tomotley fine
sandy loam (184 acres), Cape Fear fine sandy loam (200 acres), Roanoke fine sandy
loam (84 acres), Muckalee loam (15 acres), Augusta fine sandy loam (14 acres), and
Seabrook loamy sand (0.49 acre) (Figures 4a and 4b).
The soils of the site were sampled in March of 2007 and sent to the North
Carolina Department of Agriculture (NCDA) state laboratory for fertility analyses.
Results indicate that soils ranged from a high of 7.7 percent humic matter to a low of
0.92 percent and the average of the 20 samples collected was 3.96 percent. Eight of the
samples were considered to be in the mineral soil class, six were in the organic class,
and the remaining six were considered to be in the mineral-organic class. Soil
amendment recommendations were made by the NCDA for a hardwood crop. Results
PCS Compensatory Mitigation Plan 2 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
of the analyses and a map showing sample locations are provided in Supporting
Document C1.
2.3.2 Pre-restoration Drainage and Section 404 Jurisdictional Status. The
Hell Swamp site encompasses almost the entire Scott Creek watershed and portions of
the Smith Creek watershed. Scott Creek drains the majority of the Hell Swamp site;
however, a small portion of the southern corner of this site drains to Smith Creek (Figure
5). A network of ditches and canals carry water off of the agricultural fields and into two
branches of Scott Creek. The main prong of Scott Creek extends north across two-
thirds of the property (approximately 1 mile), and the northern prong extends
approximately 0.25 mile north from the main prong. The site drains into Pungo Creek,
a Special Secondary Nursery Area designated by the NC Division of Marine Fisheries.
Pungo Creek drains to the Pungo River, which is one of the main tributaries of the
Pamlico River. Most of the Hell Swamp site acreage has been previously drained and
is non-jurisdictional. Remaining Section 404 jurisdictional areas include some
agricultural ditches up to the Ordinary High Water Mark, most of the wooded land
adjacent to Scott Creek and along the western parcel boundary, and some wetlands
along the northern border of the site, and total approximately 87 acres (Figure 6).
Jurisdictional status of the last two last parcels purchased by PCS (forested parcel along
both sides of Scott Creek just upstream of NC99 and the 34-acre forest along the
western parcel boundary) were confirmed by the Corps in May of 2008 and results of the
determination are included in Figure 6 (updated since publication of the PCS FEIS).
2.3.3 Woodland Areas. The dichotomous key II.B.ii.2.b of the North
Carolina Wetland Assessment Method (NCWAM) was used to describe which of the 16
• wetland types exist on the Hell Swamp site. A mature bottomland hardwood forest
comprised of bald cypress (Taxodium distichum), red maple (Acer rubrum), green ash
(Fraxinus pennsylvanica) and sweet gum (Liquidambar styraciflua) covers approximately
43 acres along the main body of Scott Creek, primarily on the south side. About one
quarter of the distance along Scott Creek is bottomland on both sides and about one
quarter is forested on only the south side. Subcanopy and herbaceous species include
swamp red bay (Persea palustris), wax myrtle (Morelia cerifera), greenbriar (Smilax
spp.), yellow jessamine (Gelsemium sempervirens), and rush species (Juncus spp.).
There is a sparse strip of common reed (Phragmites australis), wax myrtle, black willow
(Salix nigra), green ash and sweet gum along a portion of the north side of the main
body (approximately 4 acres). Approximately 7 acres on both sides of the northern
prong (UT6) is a highly disturbed community made up of common reed, wax myrtle, and
scattered young pine and hardwoods. In addition, there are approximately 34 acres of
mature hardwood flat along the western boundary and a 14-acre linear strip of hardwood
flat containing some pines which separates the northernmost one-third of the site from
the southern portion. The 34-acre hardwood flat was determined by Michael Schafale of
the NC Natural Heritage Program to be an "excellent" representative of a non-riverine
wet hardwood forest. Depending on the fate of similar communities in the state, he also
determined this forest to be of state or regional significance (Supporting Document C2).
2.3.4 Vegetated Non-forested Areas. Existing areas of unforested
vegetation occur along some ditch banks, along previous interior parcel boundaries,
and along the north prong of Scott Creek. The narrow strips of vegetation which occur
along previous parcel boundaries also contain some scattered mature trees (e.g.,
loblolly pines, sweet gum, and swamp chestnut oak (Q. lyrata).
PCS Compensatory Mitigation Plan 3 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
2.3.5 Cleared Areas. The northern one-third of the site includes 157
acres of cleared and ditched areas which never went into agricultural production prior to
purchase by PCS. These areas are covered with dog fennel (Eupatorium capillifolium),
panic grass species (Dicanthelium spp.), and saplings of red maple, loblolly pine (Pinus
taeda), and sweet gum.
2.3.6 Agricultural Fields. The majority of the southern and eastern
portion of the site (approximately 965 acres) is made up of a mosaic of agricultural fields.
There is also a 37-acre agricultural field in the northern portion of the site which has
been farmed for more than 100 years. The total land that has been in active agricultural
production is approximately 1,002 acres. According to the records of both the Beaufort
and Hyde County Farm Service Agencies, these acres have prior-converted status
(Supporting Document C6).
2.3.7 Protected Species. At the suggestion of USFWS (refer to letter in
Supporting Document C3), the site was surveyed in October of 2007 for the presence of
sensitive joint vetch (Aeschynomene virginica), the only protected species with the likely
potential to occur on the site. No individuals were found during the survey and the
results of the survey and report was submitted to the United States Fish and Wildlife
Service (USFWS). The NC Natural Heritage Program had no records of any protected
species from this site (refer to letter in Supporting Document C4).
2.3.8 Cultural Resources. The NC State Historic Preservation Office
(SHPO) was contacted to confirm presence or absence of any known historic or
prehistoric cultural resources on the Hell Swamp site. There are no records within the
SHPO database for this site (refer to letter in Supporting Document C5). A single grave
located on the site will be properly relocated in coordination with NC SHPO and in
compliance with all applicable state statutes.
3.0 SITE SELECTION FACTORS AND JUSTIFICATION
3.1 Logistics. Site selection is of primary importance in any wetland restoration
project since that which was previously a wetland will have a higher likelihood of
feasibility, sustainability, and success if properly restored. The crop fields of the Hell
Swamp site have prior-converted status as determined by NRCS. Also important in site
selection is adjacency to existing wetlands in a similar landscape position whose
presence indicates appropriate hydrological conditions for hydric soil and consequent
vegetation communities. Adjacent wetlands are also able to serve as seed banks,
refugia for mobile animals while the restoration site matures, and reference sites that
may be used to assess restoration success. Remnants of the Scott Creek riparian
corridor are present downstream of the site, and a relatively undisturbed wetland (a
potential reference forest) is present on the western side of the site. Pungo Creek is
designated as a Special Secondary Nursery Area by the North Carolina Division of
Marine Fisheries (NCDMF). The Hell Swamp mitigation site and Scott Creek are in a
similar landscape position to several streams on the NCPC Tract which drain to South
Creek, also a Special Secondary Nursery Area. State-designated nursery areas are
also considered Essential Fish Habitat by the South Atlantic Fisheries Management
Council. Therefore, restoration of the Scott Creek watershed, restoration of portions of
PCS Compensatory Mitigation Plan 4 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
Scott Creek itself, and restoration and enhancement of its associated riparian buffer may
benefit freshwater fishes, estuarine species, and coastal migratory pelagic species.
3.2 Cost and Technology. Restoration of the site will require no special
technology or complex engineering since only ordinary surficial low ground pressure
equipment is necessary to prepare the site. All removal of field crowns, filling of interior
ditches or canals, and contouring will be based on LiDAR (light detection and ranging)
and/or 0.5-foot topographical survey data and informed by preparation of a water budget
and model predictions of soil behavior (based on permeability, texture, and stratigraphy)
by a registered professional engineer. There is no identified source of pollutants other
than what might be present from normal agricultural practices, so pollutant remediation
is not required to restore the site.
3.3 Justification. The agricultural acres of the Hell Swamp restoration site are
documented as prior-converted cropland by NRCS. Based on customary procedures
and field evaluations according to the 1987 Corps of Engineers Wetland Delineation
Manual, the Corps of Engineers determined the majority of the site, including those
acres prepared for agricultural use but not yet put into production, was non-jurisdictional
and therefore suitable for mitigation.
3.3.1 Jurisdictional Status of Woodland and Cleared Areas. The majority
of woodland areas on the site are jurisdictional wetland (87 acres). Jurisdictional status
of creeks and waters extends upstream into the agricultural fields or along perimeter
canals in several channelized portions of the streams (ditches) (8,299 linear feet of
stream and 18,110 linear feet of OHW). The cleared areas of the site underlain by
hydric soils that are not currently in agricultural production are assumed to have been
jurisdictional wetlands prior to the removal of wetland hydrology due to ditching (Figure
6). The most upstream area subject to CAMA jurisdiction was determined to be Scott
Creek where it is culverted beneath the existing farm access road (refer to Supporting
Document C7 and Figure 6).
4.0 SPECIFIC GOALS, TARGET FUNCTIONS, AND METHODS
4.1 Goals. The ultimate purpose of mitigation activities of the Hell Swamp site
is to successfully reestablish 808 acres of non-riverine hardwood flats, 58 acres of
riparian forest (headwater forest, bottomland hardwood forest, and riverine swamp
forest), 19,783 LF of zero and 1St order stream channel (2 acres of open water) and
preserve or rehabilitate 40 acres of non-riverine hardwood flat including a 34-acre "state
or regionally significant" mature hardwood flat, 28 acres of riverine swamp
forest/bottomland hardwood forest, 18 acres of non-riverine hardwood flat, and preserve
200 acres of areas mapped as uplands on the county soil survey. An additional 103
acres underlain by hydric soils are included as "potential non-wetland" areas due to
drainage effects from perimeter ditches that must remain open. Wetland
reestablishment will include non-riverine hardwood flats, headwater forests, riverine
swamp forests, and bottomland hardwood forests. Stream mitigation activities will result
in restoration or enhancement of approximately 21 acres of riparian buffer, and up to 21
acres of headwater riparian buffer under the flexible buffer mitigation approach (these
acres are included in the above tally). The entire 1,297-acre site will be put in a
PCS Compensatory Mitigation Plan 5 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
perpetual conservation easement. The goals will be achieved on a multi-spatial scale
with these specific objectives:
¦ To capture and store rainfall which for the past three to 10 decades has been
carried off the site by a system of ditches and canals (site)
¦ To establish a diverse community of vegetation which reflect differences in
soil character, topography, and hydroperiods (site)
¦ To improve water quality and provide watershed protection (site, watershed,
and region)
¦ To provide wildlife habitat (site, watershed, and region)
4.2 Target Functions. Functions of wetlands and waters are the physical,
chemical, and biological processes and attributes of a wetland that in conjunction
operate as guarantors of water quality and are important components of food webs and
habitat. The 1990 Memorandum of Agreement between the Corps and the
Environmental Protection Agency (EPA) on the Determination of Mitigation Under the
Clean Water Act Section 404(b)(1) Guidelines, and RGL 02-2, require the replacement
of aquatic functions which are unavoidably lost or adversely affected by an authorized
permitted activity (US Army Corps of Engineers, 2002). Many wetlands and waters have
multiple functions, and while accurate assessment of these functions is a dynamic field,
scientists do agree that all wetlands and waters either increase or decrease a specific
component of the hydrologic cycle.
Replacement and/or uplift of any aquatic functions are driven by proper mitigation
site selection and a design that maximizes what the natural conditions of the site will
support. The specific functions which are targeted for the Hell Swamp site are:
NUTRIENT REMOVAL/TRANSFORMATION- Transformation and removal of
nitrogen and phosphorus will be enhanced with a low gradient and abundant
vegetation of the replanted fields of Hell Swamp and the deceleration of water
removal via Scott Creek with the reconnection of flow to the adjacent
floodplains. Experience at the PCS Parker Farm mitigation site indicates that
volunteer herbaceous wetland vegetation will probably cover the Hell Swamp
site within one year. The planted trees, volunteer herbs and forbs, and the
slope of the site that averages less than 0.2 percent, will enable this function.
Restoration and conversion of agricultural lands to wetlands and forested
systems will remove and/or greatly reduce the source of some potential
nutrients to Scott Creek, Pungo Creek, Pungo River, Pamlico River, and
Albemarle Pamlico Estuary.
¦ ORGANIC MATTER PRODUCTION AND EXPORT- The onsite restored
streams and proximity to Pungo Creek guarantees multiple hydrologic links
for downstream transport of organic nutrients produced on the restored Hell
Swamp site. Productivity of the site will increase and change through time as
the vegetation matures and goes through various stages of succession. The
complex range of elevations and network of natural drainages through the
site provide numerous opportunities for the production and export of organic
material to areas downstream, including Scott Creek, Pungo Creek, Pungo
River, and the Pamlico River/Sound estuary.
PCS Compensatory Mitigation Plan 6 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
¦ FLOODFLOW ATTENUATION AND SURFACE WATER STORAGE-
Portions of the Hell Swamp Site occur within the FEMA 100-year floodplain
and based on elevation alone, would attenuate floods only during an extreme
event. However, restoration of Hell Swamp to functional wetlands will
decelerate the current rapid delivery downstream of stormwater via
agricultural ditches and canals and increase and prolong surface and
subsurface storage capacity on site, relieving downstream flooding that may
currently occur on a more frequent basis. Restoration of Scott Creek
segments and associated riparian headwater systems will provide
topographic diversity, restore and maintain stream evolution processes, and
restore and maintain baseflow.
¦ CAPTURE AND RETENTION OF SEDIMENT AND OTHER POLLUTANTS-
Restoration of the Hell Swamp Site will reduce the aerial suspension of
topsoil that occurs with seasonal agricultural practices and will decrease
erosive velocity within main canals and ditches. A restored wetland will
increase storage capacity and deliver cleaner water downstream with a
decreased sediment load. Depending on crop planted and choice of
chemical, estimated amounts of herbicide, pesticides, and fertilizers applied
yearly to the approximate 1,000 acres under agricultural production at Hell
Swamp range from 1 to 750 gallons of herbicides, 23 to 39 gallons of
insecticides, and 61 to 159 tons of fertilizer (NC Agricultural Chemical Manual
2008). Cessation of agricultural practices on the site will remove these
chemicals from being transported downstream and improve water quality
within the basin. After site restoration of streams and headwaters, less
sediment will be transported downstream due to more topographic diversity
which will cause the sediment load to be deposited before it reaches the
more sensitive estuarine and nursery waters downstream.
¦ GROUNDWATER DISCHARGE AND RECHARGE- Post-restoration,
freshwater runoff will be intercepted and discharged slowly over time at Hell
Swamp. Shallower and longer hydroperiods in areas adjacent to streams
and riparian headwater systems will increase base flow of Scott Creek, its
associated tributaries, and its riparian headwater systems.
WILDLIFE HABITAT-The wetlands (and uplands) at Hell Swamp will provide
more diverse food and cover for a variety of birds, mammals, reptiles, and
amphibians. The large size of the site will have positive effects on water
quality in the Scott Creek watershed and will increase the connectivity
between the existing natural areas of Scott Creek downstream of the site.
Mitigation of large-scale watershed and corridor areas, like Hell Swamp, will
support important habitat to species that are sensitive to community "edges"
and those species requiring contiguous areas of unbroken habitat. The
conversion of agricultural landscapes to forested habitats will serve to benefit
local terrestrial and aquatic wildlife as well as aquatic resources downstream
of these sites.
¦ AQUATIC DIVERSITY- Mitigation design at Hell Swamp will include a
diversity of stream habitats to provide support to a high diversity of
organisms. Habitats will include shallow areas, deeper pools, topographic
PCS Compensatory Mitigation Plan 7 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
differences that alter site velocities and hydroperiods, and multiple
connections to permanent water. Removal of agricultural practices and
attenuation of storm water will contribute to improved water quality in
downstream habitats, including Pungo Creek, a Special Secondary Nursery
Area. Pre-restoration fish and benthos collections occurred in 2007 and 2008
prior to restoration activities.
4.3. Methods. Restorative work is focused on removal of the manmade
drainage features and reestablishment of variable hydrological conditions of a duration
and frequency typical of interstream wet flats and riparian wetlands (including riparian
headwater systems) of coastal North Carolina. The site will then be planted with an
appropriate mix of wetland trees and shrubs commonly found in similar reference sites
or known to historically exist on similar sites.
4.3.1 Agricultural Areas. The field areas between interior ditches have
been graded for optimum drainage and agricultural production. The crowns within the
individual fields will be removed with the fill being placed in the adjacent ditches. After
the removal of the crowns, the field surface will be roughened using tillage equipment to
break up any plow pan and loosen compaction that may have occurred during the first
phase of restoration and to increase surface storage.
4.3.2 Woodland Areas. Any areas of mature or regenerating wetland
forest on the Hell Swamp site will be preserved or enhanced. Filling of the perimeter
canal around the "wetland tongue" in the northwest portion of the site at the headwaters
of the Scott Creek restoration segment and relocating the ditch which surrounds the
small wetland polygon along the western boundary to the perimeter of the site will
rehydrate these areas to a more natural hydroperiod. Removal of nuisance species (red
maple, loblolly pine, and sweet gum) and replanting these areas with more desired wet
hardwood species will enhance the habitat function. Discontinuous areas of disturbed
forest near the northern side of the main prong of Scott Creek will be augmented with
planting of additional riparian tree species. Disturbance to any existing large trees along
the north side of Scott Creek will be avoided and no work is expected to occur within the
majority of the existing forested floodplain on the south side of Scott Creek. However,
the restoration of UT4 and incorporation of an existing drainage ditch that conveys water
from the agricultural field east of the project boundary and south of Scott Creek will
require access for equipment and some manipulation in these narrow segments of the
forested floodplain. These two areas have been included in the major CAMA permit
application as wetland impacts and are shown on Exhibit 2 (Item E- Soil
disposal/regrading that impacts wetlands) and Exhibit 3B of the application. Thin rows of
trees (mostly nuisance species) along the boundaries between the various parcels will
be removed and suitable logs will be utilized where appropriate as large woody debris
within restored stream/valley reaches. Other areas with nuisance species will also be
cleared and replanted with more desirable species of hardwood trees and shrubs.
Disturbed riparian areas (primarily inhabited by common reed) associated with the north
prong of Scott Creek (UT6) will be cleared and replanted with native vegetation. The
common reed will be aggressively controlled as needed.
4.3.3 Vegetated Unforested Areas. The vegetated area associated with
the north prong of Scott Creek is shown as a blue line on Figure 1 (visible on Figures 2,
3, and 4), and occurs within the lower portion of UT6. The upstream half of this
vegetated area is comprised of predominantly forbs and grasses, including common
PCS Compensatory Mitigation Plan 8 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
reed, shrubs, and scattered pine; the downstream half transitions into pine forest. All
vegetation in the area associated with the restoration of UT6 will be removed.
Two primary methods to reduce common reed will be utilized prior to
planting. For areas where only common reed is growing, imazapyr (Habitat@) is
suggested to be used in June. For areas where common reed is growing among other
desired species, a treatment with either glyphosate (Rodeo@) alone or a mixture of
imazapyr and glyphosate in July is the recommended treatment. Where access is not
limited, a tracked vehicle such as a marsh buggy (e.g., ARGO) equipped with a nozzle
sprayer will be deployed. For areas where access is problematic for the ARGO,
backpack sprayers will be deployed. All manufacturers' instructions for application will
be followed, crews will be previously trained and experienced, and the operation will be
supervised by a certified applicator. Both imazapyr and glyphosate have been
developed and approved for weed control in aquatic environments.
Annual treatments for common reed are also recommended after the site is
planted. These treatments will be accomplished with spot treatments and back pack
sprayers in July. It is recognized that eradication of common reed is unlikely, but these
reduction measures are designed to lower the competition pressure and allow the
planted trees time to provide more shade in their first 5 years of growth. Common reed
prefers open sunlight and it has been the experience of PCS in other areas, that once
the canopy closes, the common reed becomes much less of a problem species.
4.3.4 Cleared Areas. The non-agricultural cleared areas between interior
ditches were in the process of being graded for optimum drainage and agricultural
production prior to purchase by PCS. Spoil piles and crowns within the individual fields
will be removed with the fill being placed in the adjacent ditches. After the removal of
the crowns, the fields will be roughened using tillage equipment to increase surface
storage.
5.0 WORK PLAN METHODOLOGY
The concept of the restoration work is to remove the field crowns and drainage
ditches and restore the site's natural topography into a self-sustaining watershed and
wetland/stream complex where any surface flow moves through vegetated wetlands
before reaching any streams. Prior to work plan development, a surveyor prepared a
half-foot contour topographical map of the entire site and UDAR maps were also
obtained to assist with areas outside of the boundaries of the property. Field testing of
the soil groups was performed using compact constant head permeameters which
measure the lateral conductivities of the soils.
Existing at present are three road entrances into the site from Seed Tick Neck
Road. As part of restoration work activities, the eastern most main entrance road (the
"farm road") from Seed Tick Neck Road will be moved 1,700 feet further east to the
parcel boundary, the minor middle entrance road will be removed, and the other
entrance will remain at its present location (about 5,000 feet from the intersection of
Seed Tick Neck Road with NC99); two additional entrances will be added, one just south
of Scott Creek along NC99 (- 3,000 feet from Seed Tick Neck Road intersection with
NC99) and the second along the southern site boundary off of Creek Road (SR1715)
PCS Compensatory Mitigation Plan 9 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
just west of Smith Creek. These additional entrances and several access roads will be
located on the perimeter of the site, often within the area expected to be effectively
drained by perimeter ditches that must remain open (shown on Figure 7). The access
roads and the interior paths/trails shown on Figure 7 will be used during monitoring and
post-monitoring by the conservation easement holder and others authorized by the
holder.
5.1 Hardwood Flats. The majority of the work on Hell Swamp will occur in
areas that will be reestablished as hardwood flats (interstream wet mineral flats) and will
be planted with species appropriate for this community, landscape position, and soils.
5.1.1 Hvdrolooic Model. The DRAINMOD program was used to predict
the long term water table elevations and potential hydroperiods. This program was
created by Dr. R. Wayne Skaggs in 1978 at North Carolina State University. It is a
computer simulation model developed for soils with shallow water tables. The model is
based on a water balance in the soil profile and uses approximate methods to quantify
the various hydrologic components such as infiltration, surface roughness, surface
runoff, deep and lateral seepage and evapotranspiration. It has been tested and found
to be reliable for a wide range of soil and climatological conditions (Skaggs et al 1981;
Gayle et al., 1985; Fouss et al. 1987; Rogers 1985; McMahon et al. 1987; and Susanto
et al. 1987).
5.1.2 Water Budget A water budget is the amount or rate of change in
water stored in a given area or the rate at which water flows into or out of the given area.
The objective of the water budget is to predict whether the existing soils and selected
plants will produce a minimum water table elevation (water stored) during the time period
required to meet the wetland conditions after restoration. The water stored during a
specified time during the year (the growing season) is known as the hydroperiod. The
water budget is used to predict how the seasonal pattern of water budget components
(inflow, outflow, storage) may affect the hydrograph (hydroperiod) at a given site. Basic
components required to evaluate a water budget for a wetland site are the input
components: precipitation, the storage components of the soil: surface storage or
roughness and porosity, and the output components: evapotranspiration - which
includes direct evaporation and plant transpirations, surface runoff, and subsurface flow.
5.1.2.1 Meteorologv- Climatic Inputs and Evapotranspiration.
Detailed, long-term records including hourly precipitation and evapotranspiration are
required for use in DRAINMOD. The nearest NOAA weather station is located in
Belhaven, NC approximately 3 miles east of Hell Swamp (NOAA Station Belhaven 3E,
located at 35°34' North, 76°35 West). Rainfall and temperature data in the WETS data
set contain the years 1970 to 2002. Soil samples were collected in the field and were
tested at North Carolina State University to determine the key soil characteristics used in
DRAINMOD, such as drainable porosity and permeability.
5.1.2.2 Water Budget Outputs. Long term water budgets were
calculated using the yearly summary from DRAINMOD. The water budget shows the
total rainfall for a given year (input) and then shows the quantity infiltrated, the quantity
lost to runoff (surface flow), the quantity lost to evapotranspiration, and the quantity lost
to subsurface flow. The difference in the water input and the water output equals the
change in storage (water table elevation). Since the site is bounded mostly by perimeter
ditches that maintain the historic drainage rights of others, the offsite flow into the
PCS Compensatory Mitigation Plan 10 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• system is zero. The volume infiltrated is the volume used to lengthen the hydroperiod of
the site. The site has been designed to increase the surface roughness to -1.5 inches
which will mimic the pre-agricultural conditions and detain rainfall long enough for
infiltration to occur. In years with minimal rainfall the volume infiltrated, as a percentage
of rainfall, is high. Conversely, in years of significant rainfall, the volume infiltrated, as a
percentage of rainfall, is low. The basic relationships between the categories are as
follows:
P= F+RO+ET+Ds
Input to system=Precipitation (P)
Rainfall volume captured by the surface roughness and
local storage = infiltration (F)
Volume in excess of the volume infiltrated = runoff
(surface runoff) (RO)
Two losses can occur to the volume infiltrated: they are
either lost through evapotranspiration (ET), or
subsurface drainage (Ds)
5.1.3 Proposed Restoration of Surface Contours. The intent of the
proposed surface work on the interstream flat portions of Hell Swamp site is to restore
as closely as possible, without over-engineering, the natural contours that existed on the
• property prior to ditching and/or farming. The methodology used to develop the plan
involved taking a series of cross-sections through the existing fields and calculating the
amount of fill required to be removed from the center, or crown, of each field such that
the ditches on either side of the field would be filled. The resultant elevations of the
fields and ditches after the removal of the agricultural drainage should return the ground
surface to its original topographic contour. Alignment of contours will be highly irregular,
as would be typical of an undisturbed site. After crown removal and ditch filling, the
ground surface will be roughened to reintroduce the varied surfaces of its former natural
state. A large chisel plow will be used to break up any remaining soil compacted from
the agricultural use as well as the compaction from crown removal and filling of ditches.
Once the soil has been loosened, additional tillage equipment will be used to provide a
roughened soil surface. Refer to Supporting Document E for specifics regarding
design/work plan sheets. Supporting Document F contains a summary of the hydrologic
model analysis used to verify that the historic contours, proposed surface roughness,
and soil characteristics would yield wetland conditions at the site.
5.2 Streams and Riparian Headwater Systems. Due to the extensive
drainage network, altered topography, and headwater nature of the Hell Swamp Scott
Creek ecosystem, it is difficult to determine the historic drainage pattern based on
current conditions. However, several methods were employed to identify historic
headwater valleys and develop initial design approaches. These included the use of
historic aerial photographs, LiDAR data, topographic ground surveys, soil profiles within
the valleys, and reference site analysis.
5.2.1 Historic Aerials. Historic aerial photographs for the site were
obtained from the Beaufort County Natural Resources Conservation Service (NRCS) for
PCS Compensatory Mitigation Plan 11 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• 1938, 1948, 1955, 1964, and 1970. These aerials were examined to determine the land
use history of the site, and to search for signs of potential stream features. Review of
the historic aerials indicates that most of the project site was wooded into the 1970's,
with the exception of a field area in the northern portion of the project area that has been
in agricultural production since at least 1938. In the early 1960's, a series of roads were
constructed through the site to allow access for subsequent drainage and conversion of
the land to agriculture. The lower portion of Scott Creek was channelized sometime
between 1964 and 1970, as the dredged channel is clearly visible on the 1970 aerial.
The photos also indicate that the lower portion of Scott Creek was channelized along the
northern edge of the historic bottomland wetland system, and the historic alignment of
the reach was altered (1964 and 1970 aerials are included in Supporting Document B).
Clear evidence of distinct stream channels is not evident from the historic
aerial photos; however, the photos do indicate the presence of valleys with apparent
wetland features along the larger tributaries and Scott Creek. The aerials for 1964 had
faint blue pen marks that had been sketched along the major drainages of the site.
When asked what these pen marks indicated, NRCS staff said that these were typically
marks that the field agent would have made on the aerials to indicate the location of
streams on the site during field assessments for soil mapping. The timeline of the site
supports this, since roads were constructed through the site between 1955 and 1964,
indicating that further drainage of the site was being planned and the landowner(s)
would have likely consulted with the NRCS regarding drainage practices and soil
conditions.
5.2.2 Topographic Data. Light Detection and Ranging (LiDAR) data
and data from on-site ground surveys were used to detect the presence of historic
headwater valleys across the project site. The LiDAR data were used primarily at the
onset of the project, prior to actual ground surveys. A topographic ground survey was
conducted to develop a digital terrain model (DTM) for the site. The DTM forms the
base mapping for the design plan sheets, and illustrates the existing drainage ditch
network within the property. Four cross-sections were surveyed on the site, three on the
lower half of Scott Creek and one on a jurisdictional lateral channel that flows into Scott
Creek (UT4) (Figures 8a and 8b). Fluvial stream features such as bankfull indicators
and pool, riffle, run sequences were not observed during field assessments due to past
channel manipulations and backwater conditions. Therefore, the cross-section data
were collected to document the incised condition of the channels, and show that the
channels function more as drainage canals than natural stream systems. Cross-
sections are provided in Supporting Document D.
5.2.3 Identified Proiect Reaches. Information gathered from the historic
aerials was used in combination with detailed topographic data to predict the locations of
historic stream features on the site. The main channel that flows through the site is
labeled as Scott Creek from its headwaters to the downstream extent of the property at
NC Route 99, where the creek flows through a road culvert and eventually discharges to
Pungo Creek, a tributary to the Pungo River. At its headwaters, the historic drainage
area of Scott Creek was approximately 90 acres, increasing to 800 acres at the
downstream end of the project. Based on regulatory guidance provided in Information
Regarding Stream Restoration with Emphasis on the Coastal Plain (USAGE and
NCDWQ 2007), the upper portions of Scott Creek would have been considered a
riparian headwater system that transitioned to a low energy single thread stream in the
PCS Compensatory Mitigation Plan 12 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• middle portion of the site and a braided swamp system downstream of the existing farm
access road from Seed Tick Neck Road. Several headwater tributaries were identified
that would have historically drained to Scott Creek (Figure 9), and each is described
below.
Unnamed tributary 1 (UT1) begins at the base of a slight escarpment
feature that runs north to south along the western side of the project site. UT1 was
identified by a prominent topographic valley signature that currently collects excess
surface water and indications of a valley on historic aerials of the site. The historic
drainage area at the downstream end of the reach was approximately 250 acres, and
the system would have been considered a riparian headwater or low energy stream
system.
The UT2, UT3, UT4, and UT5 drainages are small features that flow into
Scott Creek near the middle portion of the project site, where the historic floodplain
valley of Scott Creek begins to widen and becomes well defined. Historic drainage
areas of the four reaches were estimated at 35, 29, 25, and 25 acres, respectively.
Each of the drainages appears as distinct topographic valleys which also collects excess
water on the surface. The drainage feature at UT4 was visible on historic aerials of the
site and a blueline stream is depicted in the vicinity on the USGS Pantego topoquad.
Portions of the drainage ditches and canals that currently drain the locations of UT2,
UT3, UT4, and UT5 were considered jurisdictional by the USACE and NCDWQ.
Historically, each of these drainages would have been considered riparian headwater
systems.
• The drainages at UT6 and UT7 were identified based on distinct
topographic valley signatures which collect surface water and historic aerial
photographs. The lower portion of UT6 is also identified as a stream feature on the
Beaufort County Soil Survey. The two tributaries comprise a larger, distinct tributary
system that flows into the lower portion of Scott Creek. The main stem of the system is
labeled UT6, and the smaller tributary that drains into UT6 from the north is labeled UT7.
The drainage areas for UT6 and UT7 are 206 and 39 acres, respectively. The upstream
portion of UT6 and the entire length of UT7 would have historically been considered
riparian headwater systems. It is likely that the downstream portions of UT6 would have
transitioned into a low energy stream system.
The feature at UT8 is the only tributary on the project site that did not
historically drain to Scott Creek. Historic aerials, the blue line on the USGS Pantego
topoquad, and topographic valley signatures indicate that the tributary historically
drained to Smith Creek, another tributary to Pungo Creek to the south of Scott Creek.
The tributary system would have historically drained the entire southern portion of the
project area, and historic drainage area is estimated to have been 240 acres. The
upstream portion of UT8 would have historically been considered a riparian headwater
system, transitioning to a low energy stream further downstream.
5.2.4 Coastal Plain Riparian Headwater Systems Reference Site
Analyses. Since few restoration projects have been implemented to date that make use
of the US Army Corps of Engineers (USAGE) and the NC Division of Water Quality
(NCDWQ) publication Draft Information Regarding Stream Restoration with Emphasis on
the Coastal Plain (2007), technical design information for these systems is very limited.
PCS Compensatory Mitigation Plan 13 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• Therefore, to provide additional design data, a study of Coastal Plain headwater
reference sites was initiated with the following goals:
1) Identify reference systems that represent intact, functional systems
2) Describe the formation of channel features in headwater stream systems
3) Define the general functions that these systems provide
Each of these goals and the methods used are described below:
Goal 1: Identification of Reference Sites
Because headwater sites in the Coastal Plain are small and easily manipulated, it
is difficult to locate systems that have not been altered or impacted by human activities.
Searches were aimed at identifying small catchments (< 300 acres in size) with a mature
wooded canopy and no apparent artificial drainage affecting the reference areas.
Assessments would then be conducted at the most upstream point that showed a
defined valley with periodic surface flow, and continuing downstream until a perennial
flow feature was reached. Data collected from these assessments could then used to
determine the points at which headwater valleys form channel and fluvial features.
An extensive search was conducted of the area surrounding the project site in an
attempt to locate reference stream systems. Many potential sites were identified;
however, the majority of these sites had been drained for agricultural purposes or local
topography had been modified through forestry practices at some point in the past.
Ultimately, four reference reaches along two headwater drainages were identified in
close proximity to Aurora, NC. To provide additional data, eight reference reaches were
identified along three headwater drainages within the Croatan National Forest, south of
New Bern, NC. Locations of the reference sites are shown in Figure 10, and each is
described in the sections below:
UT to Bailey Creek: Two reference reaches were surveyed on an unnamed
tributary to Bailey Creek. Drainage areas for the upstream and downstream reaches
were 88 and 94 acres, respectively. The upstream reach (UTBA-1A) exhibits wrack
lines, scour features, and a somewhat braided flow pattern. In some locations, flow is
confined but the channel is not well defined. Further downstream, the valley slope
increases and the stream flow becomes confined to a single thread, meandering
channel. This area was surveyed as the downstream reference reach (UTBA-1 B).
Channel dimension is relatively consistent, with riffle and pools formed by both channel
meanders and woody debris.
UT to South Creek: Two reference reaches were surveyed on an unnamed
tributary to South Creek. Drainage areas for the upstream and downstream reaches
were 215 and 250 acres, respectively. The upstream reach (UTSC-1 A) was surveyed
approximately 600 feet downstream of NC Route 306. Along this upstream reach, flow
patterns are diffuse and braided, with a considerable amount of subsurface flow during
field surveys. Further downstream, the valley slope increases and the stream flow
becomes confined to a single thread, meandering channel. This area was surveyed as
the downstream reference reach (UTSC-1 B), and is located approximately 400 feet
downstream from UTSC-1 A, and 400 feet upstream of a powerline transmission corridor.
Channel dimension along this downstream reach is relatively consistent, with riffle and
pools formed by both channel meanders and woody debris.
PCS Compensatory Mitigation Plan 14 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• UTs to Brice Creek: Eight reference reach sites were identified along three
separate headwater tributaries to Brice Creek in the Croatan National Forest, south of
New Bern. These sites were identified as potential references through the help of
NCDWQ staff who have reviewed the sites in the past. The three tributary drainages
were labeled Sites 1, 2, and 3, with Site 1 being the northernmost site and Site 3 being
the southernmost site.
Three reference reaches were identified and surveyed along Site 1.
Drainage areas for the three reaches from upstream to downstream (UTBR-1A, UTBR-
1 B, and UTBR-1 C) are 96, 160, and 230 acres, respectively. UTBR-1 A is the most
upstream reach and exhibits diffuse flow patterns across a wetland floodplain, with few
distinct channel features. UTBR-1 B is the middle reach within the drainage and exhibits
a more braided flow pattern with some sections of defined channel bed and banks.
UTBR-1 C is the further reach downstream and was located in an area where overall
valley slope increases. The reach exists as a single thread, meandering stream channel
with well defined bed and banks and a relatively constant channel dimension.
Three reference reaches were also identified along Site 2. Drainage areas
were smaller than those identified for Site 1. Drainage areas for the three reaches from
upstream to downstream (UTBR-2A, UTBR-26, and UTBR-2C) are 25, 42, and 61
acres, respectively. The flow characteristics for each reach were similar to Site 1, with
the most upstream reach (UTBR-2A) exhibiting diffuse flow with poorly defined channel
features, the middle reach (UTBR-213) exhibiting braided flows, and the downstream
reach (UTBR-2C) exhibiting a single thread, meandering channel form.
• Two reference reaches were identified along Site 3, which is a separate
drainage just to the south of Site 2. Drainage areas for the two reaches from upstream
to downstream (UTBR-3A and UTBR-36) are 45 and 58 acres, respectively. The most
upstream reach (UTBR-3A) exhibiting braided and diffuse flow with some channel
features that were not consistent and were not well defined along the reach length. The
downstream reach (UTBR-3B) exhibiting a single thread, meandering channel form with
well defined bed and banks.
Goal 2: Determine the Factors Affecting Channel Formation
Most stream restoration projects that have been completed in the Coastal Plain
have involved the construction of a single-thread, meandering stream channel. As
discussed in Information Regarding Stream Restoration with Emphasis on the Coastal
Plain (2007), restoration of a single-thread channel is likely not appropriate for many
headwater systems. In some situations, formation of a wetland valley with braided,
diffuse flow will be more appropriate. By performing assessments on a range of
reference sites (i.e. varying drainage areas, valley slopes, and channel definition), our
goal was to determine the conditions under which different channel features (or no
channel features at all) are formed. Understanding these channel forming conditions
would then form the basis for the restoration approach for a given site.
As discussed previously, several reference sites were identified that began as
defined valleys with indications of periodic surface flows, and developed into more
defined stream systems down valley as drainage area increased. Once these drainages
were identified, specific reference reaches were delineated along the fall of the valley
PCS Compensatory Mitigation Plan 15 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• and surveys were conducted to document channel form (or lack of channel form).
Reference reaches were divided into three categories based on channel form:
Poorly Defined Channel- These systems are areas that exhibit a defined
valley and evidence of periodic surface flow, but lack defined channel
features. Channel bed and bank features cannot be identified, or if they
can be identified, are poorly defined and only evident for short distances
before their definition is lost. These reaches were commonly found at the
upper most portions of the headwater drainage where flow events are not
frequent and do not have sufficient energy to form channel features.
Moderately Defined Channel- These systems exhibit relatively constant
bed and bank features, but the channel dimensions (cross-sectional area
and shape) are highly variable. Flows are confined to one variable size
channel in some areas, and multiple thread channels in other areas.
Channel form appears to be defined mostly through localized scour, small
debris jams, and vegetation.
Well Defined Channel - These systems can be considered typical, single-
thread reference reach quality channels. Channel banks are obvious and
constant, and sandy bed material is common. Channel dimension is
relatively constant, with alternating riffle and pool areas. Some pools are
formed by stream meanders while others are formed by scour from
woody debris. Channel form is defined primarily through fluvial
processes.
• Each identified reference reach was surveyed along approximately 200 feet of its
length. Cross-sections were surveyed at representative locations to document the
dimension of any channel features, the width of the valley, and the general topography
of the valley bottom. A longitudinal profile was also surveyed along the apparent center
of the flow pathway, to determine overall slope, depth of a pools and riffles (if present),
and variations in topography. Along reference reaches that exhibited well defined
channels, survey methods followed those used for traditional reference reach stream
surveys that document channel dimension, pattern, and profile.
In simplest terms, the energy of flowing water is determined by its velocity and
depth. Formation of a defined stream channel begins when flowing water has sufficient
energy to begin the processes of scour, headcutting, and sediment transport. Valley
slope was used as a surrogate for flow velocity: the higher the valley slope, the higher
the velocity of flowing water in the stream system during storm events. Drainage area
was used as a surrogate for flow depth and quantity: the higher the drainage area, the
higher the volume of water (and depth of flowing water) for a given storm event. Each
surveyed reference reach was classified as either a poorly defined, moderately defined,
or well defined channel, based on visual observations during field surveys. Valley slope
and drainage area data for each surveyed reference reach are provided in Chart 1
below.
0
PCS Compensatory Mitigation Plan 16 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
0 Chart 1. Headwater reference reach data relating channel formation to
drainage area and slope.
0.016
• Poorly Defined '
0.014 - - 8 Moderately Defined -
• Well Defined
0.012

-
0.01
- ----- - - -

0 0
008 Well Defined
(
. Channels
T
W
m Moderately Defined
> 0.006 - Channels ---
0.004 - ;-_-? - --- - -
0.002 -'-- -----Poor) Defined
Channels
10 100 1000
Drainage Area (acres)
The collected data indicate that channel form can be predicted by measurements
• of valley slope and drainage area. As valley slope and drainage area increase, the
energy of flowing water also increases and tends to form more defined stream channels.
While boundaries have been placed on the graph to illustrate approximate ranges for
each channel type, these boundaries should not be considered as distinct thresholds
that trigger a change from one channel form to another. The data should be used to
indicate ranges in which a particular channel form is likely to develop. In fact, reference
sites that fell near the boundary of two channel forms were often difficult to classify
distinctly as one of the three defined channel forms based on visual observations. For
example, a reference site that plots near the boundary between a well defined and a
moderately defined channel will usually display some characteristics of both.
Other results that were derived from this analysis are summarized below:
• Drainage area alone is not a good predictor of channel form. For example,
at a drainage area of approximately 100 acres, all three defined channel
forms were identified on reference sites.
• The guidance document Information Regarding Stream Restoration with
Emphasis on the Coastal Plain (2007) states that "... According to data
being assembled by NCDWQ (Periann Russell, DWQ, personal
communication) watersheds less than 25 acres in size will not support a
headwater system". Our data agree with this assessment. All identified
reference sites were based on the presence of a defined valley and
upstream drainage area, and evidence of periodic surface flow. The
smallest drainage area of our evaluated reference sites was approximately
25 acres.
PCS Compensatory Mitigation Plan 17 Hell Swamp/Scott Creek Watershed
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July 2009
• The guidance document Information Regarding Stream Restoration with
Emphasis on the Coastal Plain (2007) also states that "... Typically, sites
with watersheds less than 100 acres would not support a stream with
defined bed and bank." Our data do not support this assessment. We
identified two separate reference sites with drainage areas of 57 and 61
acres that displayed consistent bed and bank features, and well as fluvial
bedform features. These sites were located within relatively steep valleys,
where the small headwater valley transitioned into a deeper valley of a
larger stream system.
Goal 3: Describe the General Functions of Coastal Plain Headwater Stream
Systems
While research regarding the functions of headwater systems in Piedmont and
Mountain physiographic regions has been published, very little information could be
found regarding the functions of headwater systems in the Coastal Plain. By attempting
to describe the general functions that these systems provide, based on observations and
data collected, this goal was aimed at determining important aspects that need to be
incorporated into a restoration design. In addition to design consideration, the
monitoring aspect of these projects requires that functions are identified that are specific,
measurable, attainable, reasonable, and trackable (Mitigation Plan Development
www.saw.usace.armv.mil/wetlands/Mitigation/mitplan.htm l).
During reference site assessments, observations were made regarding the
functions that Coastal Plain headwater stream systems provide. These systems are
unique since they provide functions associated with both wetlands and streams. We
conducted a review of pertinent literature and based our functional assessments
primarily on stream and wetland functions that have been defined in these works:
NC Wetlands Assessment Methodology (NC Division of Water Quality, NC
Division of Coastal Management, US Army Corps of Engineers and US
Environmental Protection Agency)
• Functional Objectives for Stream Restoration (C. Fischenich - US Army
Corps of Engineers)

Using these sources as a guide, the functions that Coastal Plain headwater
systems provide were evaluated and four general classes of functions were developed:
hydrology, water quality, habitat, and geomorphic. Benefits that each of these functions
provides are listed in Table 1, along with field indicators.
Table 1. General functions of Coastal Plain headwater systems.
I
Hydrology • Runoff reduction Microtopography
• Flow velocity reduction Floodplain vegetation
• Energy dissipation Wrack and debris lines
• Reduced erosion and sedimentation Overbank flooding
• Maintenance of baseflow Soil moisture
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18 Hell Swamp/Scott Creek Watershed
•
•
E appropriate channel form was to determine the area and slope of each stream valley.

• Prolonged soil saturation
• Groundwater recharge and discharge
Water Quality • Sediment retention and reductions Vegetative cover
• Nutrient reductions Distance from potential
• Carbon export sources
• Toxicant reductions Increased retention time
• Temperature moderation Sediment deposition
Saturated soil conditions
Habitat • Increased area of terrestrial and System size/area/extent
aquatic habitats Connectivity with other
• Increased fringe habitat between natural areas
upland and lowland habitats Vegetative cover
• Connectivity corridors between Woody debris
different wetland and upland habitats Microtopography
• Increased diversity Specialized native
• Uniqueness species
• Water source for fauna
Geomorphic • Provide topographic diversity and Valley topography
valley corridors Valley slope
e Maintains stream evolution processes
• Maintains valley formation processes
• Variable temperature and moisture
regimes
The functions listed and described above in Table 1 are not meant to necessarily
represent a complete or exhaustive list, but to provide a general description of the
functions that Coastal Plain riparian headwater systems provide. The information
indicates how these systems provide the functions of both wetlands and streams. This
functional list is also intended to provide a guide for developing functional uplift goals for
headwater system restoration projects.
5.2.5 Design Approach and Techniques. After identifying historic valley
and stream features across the Hell Swamp site, assessments were performed to
evaluate the appropriate design approach for each stream reach. The reference site
analyses were used to guide the selection of design approaches. Design approaches
and reach lengths for each stream are summarized in Table 2 (project reach/segments
can be found in the work plan sheets in Supporting Document E). A narrative
description of the work plan for various segments and additional cross sections are
contained in the Baker Technical Memorandum also in Supporting Document E.
One fundamental design question was to determine the channel form (i.e.,
single, braided, diffuse, etc.) that was appropriate for a given reach. The data collected
as part of the reference site study indicated that channel form could be predicted by
estimating valley slope and drainage area. Therefore, the first step in designing the
Topographic information for the site was studied to estimate historic ground elevations,
PCS Compensatory Mitigation Plan
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19 Hell Swamp/Scott Creek Watershed
prior to manipulation of the land for agricultural conversion. Through this exercise,
design contours for the historic stream valleys were developed, forming the basis for the
site grading plan. The grading plan for areas away from the stream valleys focused on
restoring the historic drainage patterns of the site.
Once general grades were developed for each stream valley, valley slope
and drainage area were compared to the data collected during the reference site study.
In this manner, the appropriate channel form was estimated for each stream reach,
based on the form classes that were determined as part of the reference reach study
(poorly defined, moderately defined, and well defined channels). Along some streams,
the channel form varies along the reach based on changes in valley slope and drainage
area. For example, the headwater regions of Scott Creek were predicted to function as
poorly defined channel segments, while the lower portions were predicted to function as
moderately defined channels. Approximately 1,300 feet of channel in the middle portion
of Scott Creek (Reach d) will be designed as a single thread channel, based on a
relatively steep slope in that region. In this area, the streambed elevation must be raised
several feet in order to restore adjacent wetland hydrology and connectivity with
upstream and downstream restored stream reaches. Over the 1,300-foot reach, the
slope of the channel (approx. 0.003 ft/ft) and the drainage area (350 acres) indicate that
erosive forces would be sufficient to promote scour and channel formation; therefore, a
single-thread channel design is warranted.
At the downstream end of the Scott Creek Reach d where the valley slope
flattens and erosive forces are reduced, the design will transition back to a moderately
defined channel form with braided flow patterns. This transition will occur at the upper
limit of CAMA jurisdiction near the existing farm road and flow will be diverted into the
floodplain on the south side of existing channelized Scott Creek. The farm road and
culvert will be removed and the existing channel of Scott Creek will be restored to its
pre-channelized condition for its entire length from the transition area downstream to just
below the area where UT6 joins the main stem (--3,500-4000 feet). As described in
Section 5.2.1 and shown in historic aerials contained in Supporting Document B, the
portion of Scott Creek to be filled was excavated for agricultural drainage between 1964
and 1970 at the edge of the bottomland and does not represent the historic location,
size, or aquatic functions of Scott Creek. Fill of the channelized section of Scott Creek
below the transition will use the existing remnant spoil materials deposited on the north
bank of Scott Creek, small remnant spoil piles as available on the south side, and other
suitable fill material from onsite. Reach a in Table 2 describes the braided section
through the floodplain on the south side of Scott Creek.
Filling of the valley of this channelized portion of Scott Creek is necessary
to allow surface and subsurface flow from the north side to form braided flow patterns
throughout the floodplain of Reach e, as the system functioned historically. If Scott
Creek was plugged or only partially filled through this section, the resulting swales or
impoundments would intercept this flow from the northern side of Scott Creek and short-
circuit flow across the floodplain, reducing the aquatic function restoration of Reach e.
It is recognized that filling this segment of Scott Creek will likely move the
upper limit of CAMA jurisdiction on Scott Creek downstream to the vicinity of the existing
coastal marsh (this coastal marsh is downstream from the limits of construction but
above the SR99 bridge). It is also recognized that the existing habitat for fish and
benthos in this section of Scott Creek (a channelized, often turbid, 3- to 4-foot deep
PCS Compensatory Mitigation Plan 20 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
perennial stream almost completely unbuffered on one side) will be replaced with a
shallower (-6 inches to 1-foot deep) braided perennial stream through a mature
bottomland or swamp forest. Restoration of Scott Creek into a well forested and well
buffered shallow stream system will increase shading and contribution of detritus,
increase potential spawning, nursery and foraging areas, and increase the diversity of
refugia for juvenile fish. Restoration will decrease the sediment input and limit the use of
the system by large individuals of piscivorous species to only those floodplain inundation
events resulting from some wind tides or large rainfall events. Over time, the restored
shallow stream system could potentially attract a few spawning individuals of herring or
striped bass. Therefore, restoration and rehabilitation of the historic stream and
floodplain functions of Scott Creek is an overall beneficial change in aquatic function and
is a suitable offset for some of the impacted reaches of NCPC and Bonnerton streams
proposed with continuation of the PCS mine operation in Aurora.
•
Table 2. Summary of reach/segment characteristics, lengths, and design channel forms
for project stream reaches.
I
i
i
Scott Creek a 90 0.0009 590 Poor
Scott Creek b 130 0.004 850 Moderate
Scott Creek c 290 0.0006 1,860 Poor
Scott Creek d 350 0.0027 1,300 Well
Scott Creek e 800 0.0003 - 0.0008 3,717 Moderate
UT1 251 0.0012 1,283 Moderate
UT2 35 0.0036 609 Poor
UT3 29 0.0014 - 0.0030 1,079 Poor
UT4 25 0.0014 - 0.0043 1,063 Poor
UT5 21 0.0032 845 Poor
UT6 a 96 0.0018 1,211 Poor
UT6 b 206 0.0008 1,555 Poor
UT7 39 0.0012 - 0.0027 1,120 Poor
UT8 a 118 0.0005 1,164 Poor
UT8 b 240 0.003 1,537 Moderate
Construction of poorly defined channel reaches will consist primarily of
grading the valley to design contours, and then the field surface will be roughened using
tillage equipment to break up any plow pan and loosen compaction that may have
occurred during the first phase of restoration and to increase surface storage. Woody
debris will be scattered sparsely across the floodplain to improve habitat diversity
(Supporting Document E). Reaches a and c of Scott Creek, UT2, UT3, UT4, UT5, UT6,
UT7, and reach a of UT8 will be constructed as poorly defined channels.
Construction of moderately defined channel reaches will follow similar
techniques as described for poorly defined channel reaches. The valley will be first
graded to design contours. The floodplain will be roughened utilizing tillage equipment,
but to a greater degree than poorly defined channel segments. Along reference sites
that were evaluated, microtopographic variability was greater along moderately defined
PCS Compensatory Mitigation Plan 21 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
channels as compared to poorly defined channels. This is presumably due to more
scour and deposition as a result of greater energy during flow events. It is also likely
that toppled trees are more prevalent along the floodplains of moderately defined
channels, due to greater surface saturation for longer periods of the year, lending to
more irregular topography. Woody debris was also observed to be a major component
to the function of moderately defined channels, providing grade control, dispersion of
flow into multiple channels, localized scour pools, and increased micro-habitats
(Supporting Document E). Reaches b and e of Scott Creek, UT1, and reach b of UT8
will be constructed as moderately defined channels.
Construction of the well defined channel reach of Scott Creek (reach d) will
follow more traditional stream restoration techniques for restoration of single thread,
meandering channels. The design channel form is based on similar reference reaches,
as well as past project experience under similar drainage area, soils, and slope
conditions. Wood structures will be incorporated into the channel design, to provide
stability and to promote scour in pool areas and improve habitat diversity (Supporting
Document E). Wood for structures will come from trees that must be cleared in order to
fill drainage ditches and canals.
6.0 PLANTING DESIGN
Vegetative restoration of Hell Swamp has been designed to reflect soil
characteristics, elevations, field observations, expected hydrology, and suitable species
found in Beaufort County obtainable from local or regional nurseries. To accommodate
varying hydrologic regimes, planting zones have been designated based on design
topography and soils. In addition to hardwood trees, some small polygons of shrubs
have been incorporated into the plan to promote a diverse suite of habitat, food, and
cover options in the landscape. Restored areas will be planted with bare-root seedlings
and some tublings of native tree and shrub species that are known to have occurred
historically in the area and/or observed on similar or reference sites.
Planting will occur in early spring of 2010. Figure 11 depicts the planting plan
designed for Hell Swamp and is the basis for the "reserve" orders placed with various
nurseries in summer 2009 or earlier. Tables on Figure 11 list the species to be planted
within each zone and the percent of the total represented by each species in each zone.
Trees in the hardwood flats will be planted on a 9 x 12 spacing (density of 403 trees per
acre) and shrubs will be planted on a 9 x 9 spacing (538 shrubs per acre). Areas
mapped as upland on the Beaufort County soil survey will be planted with mesic native
hardwood species. Riparian buffer restoration vegetation planting along the main
segment of Scott Creek will occur in accordance with 15 A NCAC 02B.0260 to ensure
that an adequate riparian buffer is installed at the site. Planting within the 100-foot
riparian buffer along Scott Creek restoration reaches and all riparian headwater systems
will be on 9 x 9 spacing and contain at least two species of hardwood. The low slope
does not warrant planting of live stakes.

PCS Compensatory Mitigation Plan 22 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• 7.0 DATA COLLECTION FOR MONITORING AND SUCCESS CRITERIA
While any given mitigation site may actually restore many aquatic functions,
some of these functions are more difficult to quantify within the timeframe of the
monitoring period and therefore are not suggested for use in determination of success
criteria. However, periodic monitoring is necessary to ensure that the restored streams
and wetlands are functioning as intended and to document success criteria for chosen
functions. These monitoring efforts will include installation and data collection of a
continuous rain gauge and semi-continuous water level monitoring wells, stream flow
monitoring, periodic photographic documentation, planted vegetation monitoring, and
stream and riparian headwater valley profile evaluations. Monitoring efforts will last a
minimum of five years, and beyond if necessary, until success criteria have been
successfully documented. Photographs will be taken periodically throughout the
monitoring year to visually document hydrologic conditions, flow events, stability,
vegetation growth, and the establishment of wetland and headwater stream processes at
the mitigation site. Permanent photo point locations will be established and marked to
facilitate a record at the same location each year monitoring takes place.
The performance of the site will be summarized in yearly monitoring reports
submitted by 1 May of each monitoring year. Reports will include a summary of the data
collected during the monitoring year (text, tables, and graphs), comparison to data from
past years and reference locations, and assessments of whether the site is on trajectory
for meeting defined success criteria. Monitoring reports will be in general compliance
with Corps' Regulatory Guidance Letter (RGL) 08-03.
• 7.1 Riparian Headwater Systems (Zero to First Order Stream Systems).
Greater than 70 percent of the total stream miles in most watersheds consist of
headwater streams, which underscore their importance to overall watershed health.
Collectively, small headwater streams and their associated wetlands contribute largely to
the mediation of runoff and sediment, assimilation of pollutants, and carbon production
and delivery for downstream areas (Rheinhardt et al 1999). However, determining
specific, measurable, attainable, reasonable, and trackable success criteria to the
restored functions can be difficult, especially when working with headwater systems in
the Coastal Plain. Because of their small size and location in the watershed, they are
very susceptible to seasonal changes and the effects of drought. Furthermore, while
headwater systems are important for overall watershed health, their functions in the
landscape are variable and baseline data on unaltered headwater streams in the
southeastern Coastal Plain is not currently available.
This project proposes to restore lost headwater aquatic functions as well as
riparian and non-riparian wetland functions (refer to Section 4.2 and Table 1 above).
Headwater streams are similar to and often part of a wetland system. For that reason
these systems share some similar measurable functions and monitoring techniques.
Table 3 below lists the restored functions that are proposed to be tied to success at Hell
Swamp and how those functions will be monitored and measured. These functions were
based on information provided in Functional Objectives for Stream Restoration
(Fishenich 2006).
PCS Compensatory Mitigation Plan 23 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
•

Table 3. Restored wetland or stream functions and measurement methods.

Headwater stream processes Upstream/downstream . Valley cross-sections
• Visual documentation
Riparian succession Temporal . Ve etation lots
Surface water storage Vertical and horizontal • Hydrologic monitoring
wells semi-continuous
Subsurface water storage Vertical . Hydrologic monitoring
wells semi-continuous
Landscape pathway for plant
and animal migration Temporal . Vegetation plots
7.2 Vegetation Monitoring Plots. Vegetation monitoring plots will be
established over --2 percent of the planted restoration area. Individual plots will be 43
feet x 203 feet in size (-y0.2 acre). Plots will be located to represent a range of
conditions within the planting zones across the restoration site, and the corner of each
plot will be anchored at a semi-continuous monitoring well. The plots will be oriented
from the well corner using a random table of azimuths; however, azimuths may be
slightly adjusted if necessary to avoid obstructions, avoid crossing of Scott Creek, and/or
remain within the parcel boundaries or within a specific zone, etc. Immediately after
planting has occurred, planted stems within vegetation plots will be marked with poles
and when leaf out has occurred, each tree/shrub will be tagged, identified, and counted.
The planting plan includes small polygons of shrubs scattered across the site to increase
the ecological attributes of the site. While the shrub zones will be monitored with
individual plots, the planted shrub stems will not be counted toward the success criterion
and will be quantified separately.
Each monitoring year prior to leaf fall in autumn, planted trees within the plots will
be sampled for survival. General observations will be made during sampling to describe
the survivability of stems outside the vegetation monitoring plots, and other vegetation
planted across the site (live stakes, transplants, permanent seeding, etc.). Riparian
buffer restoration vegetation monitoring along the main segment of Scott Creek will
occur in accordance with 15 A NCAC 026.0260.
7.2.1 Volunteer Woody Vegetation Sampling. To further describe composition
of the vegetative community on the site and to assist in the assessment of colonization
by other species (including noxious species), at the fifth year, all living stems of woody
vegetation within each tree and shrub plot will be identified and counted, including
planted stems and volunteer colonizing species. Non-planted individuals of
characteristic wetland species are an important component to the reestablished wetland
as they serve as additional indicators of appropriate hydrologic regimes and vegetative
success and provide increased diversity, density, and cover type. Colonizing volunteers
will be tracked separately from the planted trees and shrubs and not counted toward the
success criterion. Table 4 contains a list of acceptable volunteer species in the
reestablished wetlands at the Hell Swamp site by habitat type.
PCS Compensatory Mitigation Plan
Revised per agency request
July 2009
24 Hell Swamp/Scott Creek Watershed
.7
•
•
Table 4. List of appropriate colonizing woody species within the Hell Swamp mitigation
site (in addition to any volunteers of planted species).

American elm Ulmus americana BLH
American holly flex opaca HF
Box elder Acer negundo BLH
Fetterbush Lyonia lucida NRSF
Gallberry flex coriacea RSF
Inkberry flex glabra RSF, NRSF
High bush blueberry Vaccinium corymbosum NRSF, RSF
Coastal doghobble Leucothoe axillaris RSF
Pond pine Pinus serotina HWF, NRSF
Red bay Persea palustris NRSF
Southern bayberry Morella caroliniensis NRSF
Sweetbay Magnolia virginiana NRSF
Sweet pepperbush Clethra alnifolia NRSF
Tulip poplar Liriodendron tulipifera NRSF, RSF, HWF
Wax myrtle Morella cerifera NRSF, RSF, HWF
Habitat types: NRSF=-non-riverine swamp forest; RSF=riverine swamp forest; BLH=bottomland hardwood
forest; HF=hardwood flat; HWF=headwater forest
7.2.2 Vegetation Ecological Performance Standards. Restoration of the
wetland vegetation will be deemed successful if at least 260 planted trees per acre
(using the total acreage planted in trees) are alive after five years, or after performance
criteria have been met, whichever is longest. Riparian buffer restoration will be deemed
successful if at least 320 trees per acre are alive after five years.
7.3 Hydrology Monitoring. Nearly one year of pre-restoration hydrology data
and on-site rainfall (2007-2008) has been collected at Hell. Monitoring wells (e.g., semi-
continuous Ecotones and WLs from Remote Data Systems, Inc. [RDS]) were located
within all major soil series on the site as well as in the existing narrow wetland "tongue"
at the very top of the watershed and the mature section of forest on the Windley tract
(which serves as a reference forest for hardwood flats on the higher elevations of the
site). The wells in the Windley tract, the wetland tongue, and the rain gauge were also
monitored through 2008.
The automated rain gauge will be removed during restoration activities and
reinstalled after completion. The gauge is/will be installed in an open area, a minimum of
100 feet from any tall tree or buildings. On-site rainfall data will be used to correlate
water table response to precipitation events and rainfall data from the NOAA WETS
station Belhaven NC 0674 will be used to determine normal rainfall during the monitoring
PCS Compensatory Mitigation Plan
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July 2009
25 Hell Swamp/Scott Creek Watershed
period and will be compared with the onsite data to verify the accuracy of the onsite data
(Sprecher and Warne 2000).
Semi-continuous water level monitoring wells (e.g., RDS WM20s) will be installed
across the project site (-- 1well/10 acres for the hardwood flats) to document post-
restoration water table (Figure 12). Data from these wells will be downloaded monthly.
These data will determine if the water table at the project site has been elevated
sufficiently to reestablish targeted wetland hydroperiods. Actual well locations and
numbers of wells may differ from what is depicted in Figure 12 because of site conditions
post-restoration or other factors such as agency guidance. Final locations will be shown
in the As Built Report, within 90 days of completion of planting.
In the riparian headwater system valleys, semi-continuous monitoring wells will
also be installed in perpendicular arrays across the valley to assist in identification of the
three types of riparian wetlands (headwater forest, bottomland hardwood, and riverine
swamp forest) and to increase density of data points for analysis of hydrographs up and
across the valley. Arrays will be approximately 500 feet apart (along the long axis) for
each valley (at least 3 arrays per 1,000-foot reach; upstream, center, downstream). The
center well in each array will be in the lowest part of the valley and the number of wells
in the array will be dependent upon width and slope of the valley; the density and
number of arrays will be determined by the perceived length and footprint of each valley.
Documentation of flow in the riparian headwater systems for the success criterion
is not limited to the growing season. Qualitative data will be collected during the on-site
investigations to document surface water flow. This shall be accomplished using
photographic evidence of observed flow coupled with a preponderance of field indicators
of recent flow events in the form of a natural line impressed on the bank; shelving;
changes in soil characteristics; destruction of terrestrial vegetation; presence of litter and
debris; wracking; vegetation matted down, bent or absent; sediment sorting; leaf litter
disturbed or washed away; scour; deposition; bed and bank formation; water staining; or
change in plant community. All field indicators present will be documented in each
monitoring report. Quantitative flow data may also be collected by portable or stationary
flow equipment. All quantitative and qualitative data will be used to document the
upstream limit of flow, which will provide the basis for length of successful zero order
stream restoration (i.e., valley length). Observed events or effects from events will be
used to calibrate, correlate, and infer flow of unobserved events in monitoring well
hydrographs. Success will be achieved if two flow events occur per year in three years
out of five during normal rainfall conditions.
Annual maintenance and calibration tests will be conducted in accordance with
the Corps' ERDC TN-WRAP-05-2 guidance and any well manufacturer's specifications
(US Army Corps of Engineers, 2005). Maintenance checks per TN-05-2 will consist of
manual measurements and comparisons of well casings and unlined boreholes to
determine the impact (if any) of deposition within the well casing. As this unintended
clogging may produce artificially high water table readings, an unlined borehole will be
dug in the vicinity of the test well for comparison. Calibration and maintenance will be
conducted in 33 percent of the wells prior to each growing season of each year of the
monitoring period. The calibrated wells will be representative of each of the major soil
units occurring on the property. Each year maintenance checks will be performed on a
different set of wells. The check will involve bailing out the well, digging an unlined
borehole nearby, and then checking to see if the infill rate of the well and the borehole
PCS Compensatory Mitigation Plan 26 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
are comparable. If not, then the well and casing will be pulled and cleaned. In the event
that several wells are experiencing problems in a particular soil type, then all wells in that
soil type will be pulled, cleaned, and redeployed.
7.3.1 Wetland Hydrological Ecological Performance Standard and
Growing Season. Under the 2008 regional guidance from the Corps of Engineers for
wetland hydroperiods, the growing season for Beaufort County is 28 February to 6
December or 282 days (WETS table for Beaufort County first/last freeze date 28
degrees F 50 percent probability) (US Army Corps of Engineers 2007). At the
suggestion of Corps' Washington regulatory field office, monitoring wells will be installed
no later than 1 February, but the data collected between 1 February and 28 February will
not be part of the hydroperiod calculation for success; however, February data will
provide important information related to analyses of site hydrology during the early
growing season.
Mineral hardwood flats at Hell Swamp will be considered successful with
a minimum of six (6) percent hydroperiods (calculated from consecutive days with water
level no deeper than -12 inches from the soil surface) during the growing season under
normal rainfall conditions. Riparian wetlands adjacent to streams or within riparian
headwater systems will be considered successful with hydroperiods of 12.5 to 25
percent and will be contained within the valley, as determined by LiDAR, as-built survey
data, and agency concurrence. (Equivalent NCWAM communities and appropriate
hydroperiods at Hell Swamp include headwater forests = 12.5 to 25 percent; bottomland
hardwood forests = >12.5 to 75 percent; riverine swamp forests = >75 percent).
Hydroperiods will be evaluated using three-month rolling totals and normal rainfall
conditions will be determined from the WETS tables for Belhaven. Rainfall will be
collected monthly at an electronic rain gauge onsite (records every 0.01 inch of
precipitation).
7.4 Hydrogeomorphic Monitoring of Streams and Valleys. Longitudinal
profiles will be established for each of the riparian headwater system valleys and for the
restored Scott Creek segments during the as-built survey. There will also be three cross
sections established per 1,000-foot reach of stream/valley restoration. For the riparian
headwater systems, these cross sections will be measured for the as-built report and at
years 3 and 5 if channel features form. For the Scott Creek single thread channel
stream restoration segments, the cross sections will be measured for the as-built report
and annually during the monitoring period.
7.4.1 Hydrogeomorphic Stability. Valleys have been designed to
remain stable with minimum changes through the monitoring period; however, these
cross-sections may show minor changes in flow patterns as the headwater riparian
valley systems develop. Contingencies will be addressed pursuant to Section 8.0 of this
plan.
7.5 Reference Forest Wetland. A mature --34-acre forested portion of the Hell
Swamp site, located almost at the top of the interstream divide, provides a reference
forest for the upper portions of Hell Swamp vegetation and hydrology. Two years worth
of hydrology data will have been collected for this site by the time restoration monitoring
is anticipated to begin, although 2007 was a severe drought year. Michael P. Schafale,
biologist with the NC Natural Heritage Program, has identified this site as potentially one
of the best remaining examples of the non-riverine wet hardwood forests depending on
PCS Compensatory Mitigation Plan 27 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
fate of other comparable sites. Although "fairly small", this forest is in "excellent
condition". Supporting Document C2 contains Schafale's site report prepared after his
visit to this forest. A second potential reference forest exists to the northeast of the Hell
Swamp site off of Plum Pit Road, a mixed hardwood forest on similar soils (Arapahoe)
and at similar elevations to much of the downstream portion of the mitigation site. At
present, PCS is in dialogue with the owner about leasing this additional area as a
second reference forest.
Data collected from reference forests (vegetation and hydrology) will be used as
a guide to infer and compare behavior of applicable portions of the mitigation site (similar
soils and landscape position). Because of differences in maturity and disturbance
characteristics of the mitigation site, these data will not be used for strict success or
performance parameters.
7.6 Reference Stream Reach and Reference Riparian Headwater System.
The reference reach analysis performed on coastal headwater systems in NC (refer to
Section 5.0) was used to develop an appropriate design approach for the riparian
headwater valleys on the Hell Swamp site. These reaches vary in slope, watershed
size, landscape location, riparian maturity, and soils, and therefore may not be directly
comparable to the conditions on the newly constructed Hell Swamp site. A well array
will be installed on the poorly and moderately defined valley segments on the UT to
Bailey Creek and UT to South Creek reference sites, due to their close proximity and
similar landscape position. This well data will be used to document surface water and
flow events during the monitoring period.
10 Data collected from stream reference sites will be used as a guide to infer and
compare flow events of the mitigation site. Because of differences in maturity and
disturbance characteristics of the mitigation site, these data will not be used for strict
success or performance parameters.
7.7 Areas Mapped as Upland on the Beaufort County Soil Survey. There are
approximately 200 acres of non-hydric soils (mostly Dragston and Augusta) shown on
the Beaufort County soil survey within the project (Figure 4). These areas are primarily
located adjacent to and at the upper end of proposed restored stream segments. As
part of the watershed approach to compensatory mitigation as described in CFR
332.3(c)(2), these non-wetland riparian areas and uplands will "contribute to or improve
the overall ecological functioning of aquatic resources in the watershed." These areas
will provide some similar functions to the restored wetlands e.g., groundwater recharge,
nutrient filtration and uptake, and surface runoff attenuation. As these acres will be
planted with a mix of upland and mesic wetland flat hardwood species, they will also
increase habitat variety.
7.8 Summary of Performance Criteria. Based on specific, measurable,
attainable, reasonable and trackable parameters the ecological performance standards
or success criteria required for the types of mitigation provided at Hell Swamp are shown
in Table 5 below.
•
PCS Compensatory Mitigation Plan 28 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
•
•
Table 5. Performance criteria and methods summary.

Riparian wetland >_12.5 to 25 and Semi-continuous 28 February - 6
restoration >12.5 to 75 percent monitoring wells December;
(headwater forest hydroperiod within (arrays); onsite rain Belhaven NOAA
and bottomland the topographic gauge; as built WETS data for
hardwood) valley cross sections normal rainfall;
valley dimensions
as indicated by
LiDAR, cross
sections, and
agency concurrence
Survival of 260 Vegetation plots on Annual monitoring
planted trees per 2 percent of the site
acre (using acreage
planted in trees) of
5 year old planted
wood stems

Riparian wetland Increase in wetland Semi-continuous 28 February - 6
enhancement hydroperiod from monitoring wells; December;
pre-restoration onsite rain gauge Belhaven NOAA
conditions WETS data for
normal rainfall

Non-riparian >_6 percent Semi-continuous 28 February - 6
wetland restoration hydroperiod for monitoring wells (1 December;
(hardwood flats) hydric mineral soils well/10 acres); Belhaven NOAA
onsite rain gauge WETS data for
normal rainfall
Survival of 260 Vegetation plots on Annual monitoring
planted trees per 2 percent of the site
acre (using acreage
planted in trees) of
5 year old planted
wood stems

Non-riparian Increase in wetland Semi-continuous 28 February - 6
wetland hydroperiod from monitoring wells; December;
enhancement pre-restoration onsite rain gauge Belhaven NOAA
(hardwood flats) conditions WETS data for
normal rainfall

Zero to first order Linear feet of credit Photographs of flow Corps and DWQ
stream restoration based on most conditions 2 (e.g., April 2007
within riparian upstream location of sediment deposits, Information;
headwater system flow documented at debris flows, wrack Calendar year;
least twice per year lines, sinuosity, Belhaven NOAA
PCS Compensatory Mitigation Plan
Revised per agency request
July 2009
29 Hell Swamp/Scott Creek Watershed
•
•
•
F
in 3 years out of 5 braided features, WETS data for
channel features); normal rainfall; flow
semi-continuous confined to times of
monitoring well normal rainfall
arrays; GPS; open
channel flow
monitoring
equipment.

First or second Two bankfull events Photos winter and Stream Mitigation
order stream in separate years summer; channel Guidelines April
restoration during 5 years of stability analysis 2003
monitoring
80 percent survival Established Stream Mitigation
of planted species vegetation plots; Guidelines April
within 50 feet of plant survival 2003
stream on each side analysis
after 5 years (or 320
trees per acre- per
buffer criteria

Riparian buffer 50 feet one or both Monitoring for 15A NCAC
restoration sides of stream planted tree survival 02B.0260 Tar-
feature shown on within established Pamlico River Basin
USGS or county soil plots at years 1, 3, Mitigation Program
survey or zero order and 5. for Riparian Buffers;
stream segment DWQ 25 January
with 320 trees per 2008 Clarification
acre at maturity (5 #2008-017; for zero
years) order streams,
flexible buffer
mitigation if
approved by EMC
as stated in 401
certification dated
15 January 2009
DWQ#2008-0868
With elevations ranging from 9 feet above MSL to less than 1 foot, the non-riparian mineral flats at Hell Swamp will have
a range of hydroperiods increasing downslope into the riparian wetlands.
z Documentation may be for active or past flow conditions; may include other agency- approved structural elements or use
of technical equipment not on list.
The estimated potential mitigation yield for the Hell Swamp site is shown in Figure 13.
PCS Compensatory Mitigation Plan
Revised per agency request
July 2009
30 Hell Swamp/Scott Creek Watershed
8.0 ADAPTIVE MANAGEMENT STRATEGIES
Principles of adaptive management have become increasingly used as a tool to
elevate the likelihood of success of wetland mitigation projects throughout the United
States. The dynamics of ecosystem behavior and natural disturbances cannot always
be accurately predicted nor can human mistakes always be identified in advance.
However, adaptive management provides a somewhat formalized process for the
iterative and interactive approach to analysis of monitoring results to identify and rectify
potential problems at wetland mitigation projects. It is an attempt to identify those
changes that are likely to occur and to acknowledge that there are changes which may
occur which are unforeseen. In light of these changes, adaptive management identifies
the measures that will be taken to achieve performance and to satisfy the objectives of
the project during the monitoring period.
8.1 Adaptive Management. Certain expected natural hazards which might
affect successful restoration are fire, flood, erosion, invasive species, and herbivory.
Construction deviations could also affect performance and function of the restored area.
Strategies to minimize effects from natural hazards and human mistakes include:
¦ Beaver activity will be noted during the monitoring period and beavers will
be removed by trapper(s) if significant damage (flooding, herbivory, etc.)
appears to be caused by beavers.
• Sections affected by wildfire during the monitoring period will be assessed
for degree of damage and replanted at a spacing calculated to restore
specified tree density.
Herbivory on seedlings by rabbits, rice and cotton rats, and field mice will
be reduced by the foxes, feral dogs and cats, hawks and owls resident in
nearby natural areas. Reductions in rodent herbivory will be achieved by
the erection of simple PVC perches at interior locations on the site to
encourage raptor use. If monitoring indicates herbivory by deer is
jeopardizing tree survival, discussions with appropriate agencies will be
initiated to determine an appropriate course of action.
Deviation from construction plans will be identified early in the mitigation
process with an as-built report which contains spot elevations and
topographic data derived from aerial survey. If it appears as though there
are errors which may jeopardize the integrity of the project, then
appropriate remedial action(s) will be identified and submitted to the
Corps for concurrence prior to implementation.
¦ Planting errors in spacing density or diversity will be avoided by diligent
monitoring of and coordination with planting crews to ensure fidelity to the
planting plan. An accounting of planted stems will be provided in the as-
built report and tree plot and monitoring well numbers and locations will
be included in the annual reports.
•
PCS Compensatory Mitigation Plan 31 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• If monitoring or observation indicates an unanticipated or undesired
outcome (i.e., excessive standing water), remediation options will be
explored with permitting agencies.
Parker Farm monitoring wells were subject to frequent disturbance and
occasional destruction by black bears, despite efforts to armor the wells
against them. It is expected that bear problems will be most pronounced
in the first year or two of monitoring when the animals are becoming
accustomed to the lack of crops on the site. Barbed wire fences will be
constructed around the semi-continuous monitoring wells.
Common reed management will be necessary for the base of UT6 for
several years until the planted species create enough shade. This
species could also appear elsewhere on the site. During the regular
monitoring tasks, biologists will be tasked to be observant of common
reed and any invasive species and notify the project manager of same.
¦ It is expected that the perimeter of the site adjacent to pine plantations
(primarily the western boundary) will have a higher likelihood of volunteer
loblolly pine colonization. Red maples and sweet gum can also become
problematic at some mitigation sites. In the event that red maple, loblolly
pine and/or sweetgum alone or in aggregation exceeds 20 percent of the
total plant composition on the site at monitoring years two and three (2
and 3), a remedial action plan shall be submitted to the Corps for review
and approval prior to implementation. During monitoring years four and
five (4 and 5), none of these three species alone or in aggregation
comprising over 20 percent of the total plant composition on the site may
be more than twice the height of the planted trees. If this occurs, control
measures will be undertaken pursuant to the approved remediation plan.
8.2 Long Term Management. Long term management will be undertaken by
the land stewardship entity identified as best able and best suited to hold a conservation
easement in perpetuity and to ensure sustainability of the resource. Long term
management issues at Hell Swamp include maintenance of four controlled access gates,
access road maintenance depending on level of use, easement enforcement if
necessary, and annual inspection. There are no active engineering features (e.g.,
pumps or Geo-web reinforced stream crossings) at Hell Swamp, but there are perimeter
berms along the boundary of the site parallel to Seed Tick Neck Road and along a
portion of the southeastern boundary which could be considered as passive engineering
features and would need annual inspections. The 34-acre Windley parcel has a deed
restriction that prevents hunting, but there are no other deed restrictions on any of the
other parcels comprising the Hell Swamp mitigation site.
9.0 FINAL DISPOSITION OF SITE
The North Carolina Agricultural Foundation has expressed serious interest in
holding the perpetual conservation easement for Hell Swamp through their Landscapes
of Opportunity program (both entities are within NC State University). If an agreement
cannot be reached with them, other potential easement holders include the North
PCS Compensatory Mitigation Plan 32 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
0 Carolina Wildlife Resources Commission, the North Carolina Ecosystem Enhancement
Program, and/or the Coastal Land Trust. At this time, no formal discussions have been
held with the other potential holders. Permitting agencies will be consulted during the
decision and negotiation of final disposition.
PCS Compensatory Mitigation Plan 33 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• REFERENCES
Fischenich, J. Craig. 2006. Functional objectives for stream restoration. ERDC TN-
EMRRP SR-52. Ecosystem Management and Restoration Research Program,
US Army Corps of Engineers, Vicksburg, MS.
Fouss, J. L., R. L. Bengston , and C. E. Carter. 1987. Simulating subsurface drainage
in the lower Mississippi valley with DRAINMOD. Transactions of the ASAE
30:1679-1688.
Gayle, G., R. W. Skaggs, and C. E. Carter. 1985. Evaluation of a water management
model for a Louisiana sugar cane field. Journal of the American Society of Sugar
Cane Technologists. 4:18-28.
Kirby, Robert M. 1995. Soil survey of Beaufort County, North Carolina. US Department
of Agriculture, Natural Resources Conservation Service.
McMahon, P. C., S. Mostaghimi, and F. S. Wright. 1988. Simulation of corn yield by a
water management model for a coastal plains soil. Transactions of the American
Society of Agricultural Engineers 31:734-742.
North Carolina Agricultural Chemical Manual. 2008. College of Agriculture and Life
Sciences, North Carolina State University, Raleigh, NC.
i Rheinhardt, R. R., Rheinhardt, M.C., Brinson M.M. and Faser, K.E. 1999. Application of
reference data for assessing and restoring headwater ecosystems. Ecological
Restoration 7, 241-251.
Rogers, J. S. 1985. Water management model evaluation for shallow sandy soils.
Transactions of the American Society of Agricultural Engineers 28:785-790.
Skaggs, R. W., N. R. Fausey, and B. H. Nolte. 1981. Water management evaluation for
north central Ohio. Transactions of the American Society of Agricultural Engineers
24:922-928.
Sprecher, Steven W., and Warne, Andrew G. 2000. Accessing and using meterological
data to evaluate wetland hydrology. ERDC/EL TR-WRAP-00-1. US Army
Engineer Research and Development Center, Vicksburg, MS.
Susanto, R. H., J. Feyen, W. Diercloc, and G. Wyseuse. 1987. The use of simulation
models to evaluated the performance of subsurface drainage systems.
Proceedings of the Third International Drainage Workshop, Ohio State University,
Columbus, Ohio, USA. Pp. A67-A76.
US Army Corps of Engineers. 2002. Regulatory guidance letter (RGL) 02-02.
Guidance on Compensatory mitigation projects for aquatic resource impacts under
the Corps regulatory program pursuant to Section 404 of the Clean Water Act and
• Section 10 of the Rivers and Harbors Act.
PCS Compensatory Mitigation Plan 34 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
• US Army Corps of Engineers. 2005. Technical standard for water-table monitoring of
potential wetland sites, ERDC TN-WRAP-05-2, US Army Research and
Development Center, Vicksburg, MS.
US Army Corps of Engineers and NC Division of Water Quality. 2007. Draft information
on stream restoration with emphasis on the coastal plain. 4 April.
US Army Corps of Engineers. 2008. Interim regional supplement to the Corps of
Engineers wetland delineation manual: Atlantic and Gulf coastal plain region. Eds.
J.S. Wakeley, R.W. Lichvar, and C.V. Noble. ERDC/EL TR- . Vicksburg, MS. US
Army Engineer Research and Development Center.
US Army Corps of Engineers. 2008. Regulatory Guidance Letter (RGL) 08-03.
Minimum monitoring requirements for compensatory mitigation projects involving
the restoration, establishment, and/or enhancement of aquatic resources.
E
•
PCS Compensatory Mitigation Plan 35 Hell Swamp/Scott Creek Watershed
Revised per agency request
July 2009
•
•
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HELL SWAMP PROJECT BOUNDARY SCALE: AS SHOWN APPROVED BY: DRAWN BY: BFG/TLJ
DATE: 03/18/09 FILE: HELLSWAMP-LOC-MIT
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SOURCE: AERIAL IMAGE PROVIDED BY: NORTH CAROLINA DEPARTMENT SUITE 2
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SOILS
SYMBOL SOIL NAME
Ap ARAPAHOE (MINERAL)(418.54 ACRES) SCALE IN FEET
At AUGUSTA (14.41 ACRES)
Cf CAPE FEAR FINE SANDY LOAM- (200.41 ACRES)
Ds DRAGSTON 184.84 ACRES) O I LS
Me MUCKALEE (MINERAL) 14.86 ACRES)
Pt PORTSMOUTH (MINERAL (196.04 ACRES)
RO ROANOKE (MINERAL)(83.65 ACRES)
Sb SEABROOK LOAMY SAND (0.49 ACRES) HELL SWAMP
TO TOMOTLEY (MINERAL)(183.63 ACRES)
SITE TOTAL: 1,296.87 ACRES PCS PHOSPHATE COMPANY, INC.
Q HYDRIC SOILS
® NON-HYDRIC SOILS SCALE: AS SHOWN APPROVED BY: DRAWN BY: BFG/TLJ
NOTE: ONLY HYDRIC SOILS ARE DESIGNATED
SOURCE: MINERAL OR ORGANIC DATE: 03/27/09 FILE: HELLSWP_SOILS-MIT-NRCS
SOILS DATA: NATURAL RESOURCES CONSERVATION SERVICE, BEAUFORT COUNTY,
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Project Site
Reference
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f
Jones -
UT to Brice Creek
Site 3
1 IV
res I'
f..I----------------- --------------------
�-----�--
rr ~
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--. Hell Swamp��
jton Restoration Site Hyde
- V Upper Back Creek
~ Restoration Site
N
UT to Porter Creek `I-
Site 1 ^-- UT to Porter Creek
'�-==--- .' Site 2
UT to Bailey Creek
UT to South Creek �,1 _ `�
UT to Brice Creek
Site 1
UT to Brice Creek
Site 2
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. , Cary NegehCaro11na21518 Reference Sites Map
P. 919 083 5488 Miles Fax: [phone] Hell Swamp Site

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HELL SWAMP PROJECT BOUNDARY
STREAMS
RIPARIAN PRESERVATION/ENHANCEMENT
PROPOSED WELL LOCATIONS
STREAM VALLEY PROPOSED WELL LOCATIONS
(STREAM ARRAY WELL LOCATIONS MAY BE MORE
DENSE AND MORE NUMEROUS DEPENDING ON
CONDITIONS POST-CONSTRUCTION)
REFERENCE WELL LOCATIONS
VALLEY 1
VALLEY 2
PRESERVATION
APPROVED BY:
4709 COLLEGE ACRES
S
WILMINGTON, NORTH CAROLINA
TEL 910/392
FAX 910/392
FIGURE 12

0 1.500 3.000
SCALE IN FEET
MONITORING WELL LOCATION
HELL SWAMP
PCS PHOSPHATE COMPANY
DRAWN BY: TLJ
FILE' HLSWMP_PLANTING_
PLAN MIT.DWG
CP# 1745.59.66
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SUPPORTING DOCUMENT A
BEAUFORT COUNTY PARCEL INFORMATION
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Page 1 of 1
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http:,";'www?.emdersvs.conv`scriptsaectaw%usiwebhpd.dll/usi?formic=ptmap& ?Tausek=22... 5116,'2008
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PCS Compensatory Mitigation Plan A-1 Hell Swamp/Scott Creek Watershed
Supporting Document A
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bttp:';www2.uncfersys.comiscriptsltcstadvlusiwcbhpd.dlliusi?forinis=ptiiiap&z louseX=27... 5,116/2008
PCS Compensatory Mitigation Plan A-2 Hell Swamp/Scott Creek Watershed
Supporting Document A

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littpalwww2.unders}, .cormscripis/testadvhisiwehhpd.dlI usi?dorm is=ptilia p&,%touseX=51... 5116/2001
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PCS Compensatory Mitigation Plan A-3 Hell Swamp/Scott Creek Watershed
Supporting Document A
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Page I of 1
Details:
PHOSPHATE COMPANY

O BOX 425
R 1714
Z
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h i'? ?#"'" F c;oe F

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SUB DESC iSTAMPS 1344
SALE PRICE -l 172000 ZONE
LAND_USE ? DISTRICT 09
PROP DESC 43.58 AC DANIEL F `rVOOLARD TRACT MBL 669500125
EXMPT PROP EXMPT AMT 0
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a maps
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PCS Compensatory Mitigation Plan A-4 Hell Swamp/Scott Creek Watershed
Supporting Document E
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PCS Compensatory Mitigation Plan A-5 Hell Swamp/Scott Creek Watershed
Supporting Document A
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PCS Compensatory Mitigation Plan A-6 Hell Swamp/Scott Creek Watershed
Supporting Document A
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SUPPORTING DOCUMENT B
SELECTED SITE PHOTOGRAPHS INCLUDING HISTORIC AERIALS
(Note: 1964 and 1970 aerials depict an earlier project boundary)
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0 500 1..000 2,000 3.OGO Hell Swamp
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PCS Compensatory Mitigation Plan B-1 Hell Swamp/Scott Creek Watershed
Supporting Document B
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PCS Compensatory Mitigation Plan B-2 Hell Swamp/Scott Creek Watershed
Supporting Document B
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PCS Compensatory Mitigation Plan B-3 Hell Swamp/Scott Creek Watershed
Supporting Document B
FIhoto 1: View NW (upstream) of Scott Creek flooding into field at farm entrance road
crossing.
rnoto c: view 5t (aownstream) of Scott Creek at farm entrance road crossing.
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Supporting Document B
rnuto a: view soutn along upper U 17 towards UT6 (main tributary to Scott Creek).
r1lutu +. view 5uutn along ooraer of Woolard and Smith Tracts.
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Photo 5: View north east along main ditch entering Scott Creek at road crossing.
PCS Compensatory Mitigation Plan B-5 Hell Swamp/Scott Creek Watershed
Supporting Document B
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SUPPORTING DOCUMENT C
AGENCY CORRESPONDENCE AND ADDITIONAL INFORMATION:
1 - SOIL FERTILITY REPORT
2 - NATURAL HERITAGE REPORT ON REFERENCE FOREST
3 - USDOI/USFWS LETTER
4 - NC NHP LETTER
5 - NC SHPO LETTER
6 - NRCS PC STATUS LETTER
7 - LIMITS OF CAMA JURISDICTION
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PCS Compensatory Mitigation Plan C-5 Hell Swamp/Scott Creek Watershed
Supporting Document C
E
•
•
PCS Compensatory Mitigation Plan C-6
Supporting Document C
Hell Swamp/Scott Creek Watershed

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• SAMPLE LOCATION
NOTES:
-SAMPLES TAKEN BY CZR INCORPORATED. 23 MARCH 2008 0 11300 3.000
-EACH SAMPLE CONSISTS OF 3(THREE) SUB-SAMPLES
SC LE IN FEET
PLE TAKEN WITH WIND AUGER AT AN 81
-
NC DRAFT
I
H DE PTH
S MBOL SOIL NAME SOIL-SAMPLE LOCATIONS FOR FERTILITY ANALYSIS
AP ARAPAHOE (MINERAL) HELL SWAMP
At AUGUSTA
D o?STO FEAR FINE SANDY LOAM
PCS PHOSPHATE COM
PANY, INC.
Me MUCKALEE (MINERAL)
PORTSMOUTH (MINERA
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SCALE: AS SHOWN
APPROVED BY:
DRAWN BY: BFG/TU
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DATE: 06/09/0's
FILE: HELLSWP-SOIL-FERf-MIT
Q WDRIC SOILS CP#1745.55.66
® NON-HYDRIC SOILS 4708 OK EGE AGRE9 ORM
NOTE. ONLY HYDRIC SOILS ARE DESIGNATED WIWMCT01i RoRTH cARat?rol?2uos
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•
PCS Compensatory Mitigation Plan
Supporting Document C
C-7 Hell Swamp/Scott Creek Watershed
-2-
SITE SURVEY REPORT FORM
0 NC Natural Heritage Program
SITE NAME: Hell Swamp Hardwood Forest
DATES VISITED: March 26, 2007
INVESTIGATORS: Mike Schafale, Julia Berger (CZR), Lorrie Laliberte CZR)
REPORT AUTHOR: Mike Schafale
OWNER: The Windley family owns the most significant portion. PCS Phosphate owns 900 acres
adjacent to the east, including part of the Scott Creek headwaters.
OWNER CONTACT: Contact through Julia Berger
COUNTY: Beaufort QUAD: Pantego
SIZE: primary 44.24 acres, secondary 26.12
HOW DETERMINED: GIS.
LOCATION: Located in far eastern Beaufort County, north of Pungo Creek, northwest of the community
of Smithtown and southwest of Pantego. It lies midway between US 264, Seed Tick Neck Road (SR
1714), NC 92, and Creek Road (SR 1715), near the headwaters of Scott Creek.
PROVINCE: Coastal Plain WATERSHED: Pungo River
GENERAL DESCRIPTION: This site is a remnant of the extensive nonriverine wetland known as Hell
Swamp. It is a patch of Nonriverine Wet Hardwood Forest in very good condition. The community
remnant is fairly small, but is in excellent condition.
SIGNIFICANCE OF SITE: Regional or State, depending on the fate of other comparable sites. Examples
of Nonriverine Wet Hardwood Forest sites continue to be lost or reduced at a rate of several per year. If
this site is not one of the few best examples in the state at present, it may be in the future.
PHYSICAL DESCRIPTION
ASPECT: Flat.
SLOPE: Essentially flat.
ELEVATION:
TOPOGRAPHY: Essentially flat, but with a very gentle slough oriented north-south through the middle.
The highest part of the Windley tract is the far northern end.
HYDROLOGY AND MOISTURE: Seasonally saturated in most.
• GEOLOGY: Yorktown Formation - unconsolidated sediments
PCS Compensatory Mitigation Plan C-8 Hell Swamp/Scott Creek Watershed
Supporting Document C
SOIL (from USSCS soil map): Cape Fear (Fine, mixed, semiactive, thermic Typic Umbraquults)
COMMENTS ON PHYSICAL DESCRIPTION:
0 NATURAL COMMUNITY DESCRIPTION
Nonriverine Wet Hardwood Forest: Occurs near the north end of the triangular forest remnant on the
Windley tract. Most of the community is the Oak Flat Subtype, with a canopy dominated by Quercus
michauxii, Quercus pagoda, Quercus laurifolia, Liquidambar styraciflua, and Acer rubrum. Pinus taeda
and Quercus nigra are present in some parts. The understory is dominated by Ilex opaca, with Persea
palustris common in parts. Carpinus caroliniana is absent. The shrub layer is patchy, with Arundinaria
tecta and Leucothoe axillaris dominating. Herbs are sparse - mainly scattered Woodwardia areolata.
The canopy is very mature in the best portion, with trees averaging 14" dbh or more and large trees
frequent. Several oaks were measured at 90 cm dbh and more. This very mature portion has a scattering
of recent canopy gaps and a scattering of old tip-up mounds, suggesting little past cutting and old-growth
or near old-growth condition. This portion is just south of the northern end of the tract. Farther south, as
well as at the north end, the forest is of successional composition, with large Pinus taeda dominating.
Another hardwood patch present farther south shows evidence of more recent logging. Canopy trees
average 10-12" dbh, but Quercus nigra is dominant and the more characteristic oaks are scarce. There are
visible skidder ruts, and the shrub and understory are less diverse.
A small area of the Oak-Gum Slough Subtype is present, in a wet swale in the middle of the forest. There
is extensive shallow standing water in this section, in contrast to the other subtype. The canopy in this
subtype is dominated by Liquidambar styraciflua, and has more Quercus laurifolia and a little Nyssa
biflora. Quercus michauxii and . pagoda are absent or scarce in this subtype. The understory and shrub
layer are sparse. Herbs are scarce, at least those that would be visible this early. Saururus cemuus was
seen in one slough.
Swamp at the head of Scott Creek: This is a community of uncertain interpretation. It occurs in a gentle
swale that connects to the head of the more obvious course of upper Scott Creek. It shows up as a
somewhat discontinuous line of hardwoods in a matrix of pine stands. The ground in this band is wetter
that the area surrounding it. There is no defined channel, and disjunct deeper pools are scattered along it.
The deepest pool has only a sparse canopy consisting of sprout clumps of Acer rubrum and Nyssa biflora,
and the water looks like it might be 2 feet deep. Julia Berger reports that the Lidar-based topography
shows this band to be a lower swale running upstream from Scott Creek, but that there appears to be a
divide just west of the deepest pool. I would guess the natural community would be Nonriverine Swamp
Forest, but it might be the Oak-Gum Slough subtype of Nonriverine Wet Hardwood Forest. It is an
incipient drainage, however.
OTHER NATURAL COMMUNITIES PRESENT:
Young successional area in a recent clearcut in Nonriverine Wet Hardwood Forest: Some Liquidambar
and Pinus saplings are establishing. The Leucothoe and Arundinaria shrub layer appears to have survived
and occurs at about the same density as in the forest. There is a fairly dense tall herb layer that includes
Saccharum sp., Andropogon sp., and Eupatorium capillifolium.
r ?
LJ
PCS Compensatory Mitigation Plan C-9 Hell Swamp/Scott Creek Watershed
Supporting Document C
ANIMAL HABITAT FACTORS
HABITAT HETEROGENEITY: Artificially high. Fields and recent clearcuts contrast with the small
forest and presumably create edge effect.
AMPHIBIAN BREEDING SITES: Abundant seasonally puddles.
DENNING SITES: Large old trees.
BIG TREES/LARGE CAVITIES: Trees up to near a meter in diameter, with buttresses even larger, are
present.
SNAGS AND LOGS: Moderate numbers, probably near natural abundance.
MAST PRODUCING SPECIES: Abundant. Oaks are dominant. Soft mast may be scarce.
NECTAR SOURCES: Leucothoe.
PRESENCE OF WATER: Abundant at this time, but may become scarce later in the season, except for
ditches.
AQUATIC HABITAT FACTORS
HYDROLOGY (order, flow rate, persistence): No real stream present in this area. The secondary area
has a faint drainage which must flow at times of high water. It has a ponded area along it which appears
to sit at the drainage divide, with slope going east and west out of it.
SPECIAL STATUS SPECIES PRESENT: Julia Berger says that the Windleys report Crotalus horridus is
present.
Listera australis (W 1) is present both in the Nonriverine Wet Hardwood Forest and in the swamp.
POTENTIAL FOR OTHER SPECIAL STATUS SPECIES: Low for most. Black-throated green
warbler is a possibility.
OTHER NOTEWORTHY SPECIES OR FEATURES PRESENT:
SITE ECOSYSTEM INTEGRITY: Moderate. The community is in excellent condition, but the intact
patch is small and is subject to edge effect. It is connected to an area of mature successional pine forest,
but most of the surrounding landscape is pine plantation and fields.
AVERAGE DBH OF CANOPY TREES: 14-16" in the most mature Nonriverine Wet Hardwood Forest.
MAXIMUM DBH OF CANOPY TREES: 36"+.
DISTURBANCE-SENSITIVE SPECIES: Rattlesnakes.
0 FIRE REGIME: A little charring on one stump, probably caused by lightning. Forest fire is unlikely.
PCS Compensatory Mitigation Plan C-10 Hell Swamp/Scott Creek Watershed
Supporting Document C
OTHER DISTURBANCES OR IMPACTS
LOGGING: Most of the surrounding landscape has been altered by logging. The pine-dominated
. successional forests presumably represent the result of past logging, long ago. The younger hardwood
forest was clearly logged several decades ago.
FARMING: A large field is adjacent.
DITCHES: Ditches border the most significant community patch on both sides. Ditches also line both
sides of the timber road that runs up into the Windley tract from the south.
ROADS: One well-built timber road on the Windley tract.
ALTERED FLOOD REGIME: Altered by ditches and regional drainage to some degree. It is difficult to
tell how much.
EXOTIC/WEEDY SPECIES: None noted in the intact communities. Weedy species are common in the
more disturbed areas. No serious invasive species were seen.
UNDERSTORY CLEARING: No.
DIRECT HUMAN INTRUSION: Some hunting occurs. Deer stands are present.
LANDSCAPE FACTORS
0 BOUNDARY INTEGRITY/SHAPE: The natural part of the site is small and subject to edge effect.
ADJACENT LAND USE/OFFSITE STRESSES: A cultivated field bordering the site on the east side is
planned for restoration. A young pine plantation borders on the west side. Older successional pine stands
border to the south and north, and a recent clearcut is nearby.
RELATION/CONNECTION TO OTHER SITES:
DEGREE OF THREAT/POTENTIAL FOR CHANGE:
BOUNDARY JUSTIFICATION: The primary boundary encompasses the remaining intact Nonriverine
Wet Hardwood Forest. It is marked by fields, young pine plantation, and old loblolly pine stands. The
boundary with the older pine is somewhat indistinct.
A secondary boundary is drawn to encompass the drainage system north of the primary area, with its
distinctive ponded area. This area is of scientific interest but is not in good enough condition to be
considered primary area. A connection of this drainage to the primary area is also included in the
secondary boundary.
RECOMMENDATIONS FOR PROTECTION: This site would be worthy of acquisition for
conservation, or protection by conservation easement.
•
PCS Compensatory Mitigation Plan C-11 Hell Swamp/Scott Creek Watershed
Supporting Document C
MANAGEMENT RECOMMENDATIONS: No specific management needs are known. The site is
presumably affected by drainage in the adjacent fields, as well as by edge effect. Study of these effects or
measures to mitigate them would be appropriate. Restoration of the adjacent field for wetland mitigation
• is being considered.
NEED FOR FURTHER STUDY: Low.
PLANT SPECIES OBSERVED
Thoroughness of list: Moderate (mostly winter aspect)
W = Nonriverine Wet Hardwood Forest
S = swamp at head of Scott Creek
c = recently clearcut area
canopy
Acer rubrum W, S c
Liquidambar styraciflua W c
Liriodendron tulipifera W c
Nyssa biflora W, S c
Pinus taeda W c
Quercus falcata (W) c
Quercus laurifolia W c
Quercus michauxii W c
Quercus nigra W c
Quercus pagoda W c
understory
Acer rubrum W u
Cyrilla racemiflora W u
Ilex opaca W U
Magnolia virginiana W u
Persea palustris W U
•
PCS Compensatory Mitigation Plan C-12 Hell Swamp/Scott Creek Watershed
Supporting Document C
shrub layer
Arundinaria tecta W, c s
• Clethra
l
if
li
a
n
o
a c s
Leucothoe axillaris W, c s
Symplocos tinctoria W s
Vaccinium formosum? W s
vines
Berchemia scandens W v
Smilax (rotundifolia?) W v
herb layer
Andropogon glomeratus c h
Andropogon sp. C h
Carex spp (at least 4 spp.) W h
Chasmanthium laxum W h
Eupatorium capillifolium c h
Listera australis W, S h
Mitchella repens W h
Rhexia alifanus c h
Saccharum sp. c h
Saururuscernuus W h
Sphagnum spp. W h
Thelypteris palustris? W h
Woodwardia areolata W h
ANIMAL SPECIES OBSERVED
Thoroughness of list: Casual
White-tail deer (numerous tracks)
Black bear (likely claw marks on tree)
PCS Compensatory Mitigation Plan C-13 Hell Swamp/Scott Creek Watershed
Supporting Document C
Wild turkey
• Pileated woodpecker
Common crow
Carolina chickadee
Tufted titmouse
Pine warbler
Yellow-throated warbler
Crayfish
•
n
PCS Compensatory Mitigation Plan C-14 Hell Swamp/Scott Creek Watershed
Supporting Document C
•
-3-
l iys S?? 9
United States Department of the Interior
°
H o FISFI AND WILDLIFE SERVICE
? a
Raleigh Field Office
e Post Office Box 33726
M4H°H 9 Raleigh. North Carolina 27636-3776
October 18, 2007
Julia Berger'
CZR Incorporated f l J
4709 College Acres Drive, Suite 2 L
Wilmington, NC 28403-1725 CZR Incoroore ed
warrir,R??n, r,C
Hi Julia,
•
Thank you for your October 2, 2007 letter regarding the Bay City Farm and Hell Swamp
Mitigation Sites in Beaufort County. I compared your site maps with our N.C. Natural Heritage
Program (NCNHP) data and, to the best of my knowledge, no federal or state listed species have
been observed on or near these properties. I would, however, encourage you to conduct surveys
on these properties for the federally threatened sensitive jointvetch (Aeschynomene virginica).
There are several historic records for this species in Beaufort and Hyde counties. While sensitive
jointvetch is typically found in brackish marshes around the Chesapeake Bay, many of the N.C.
populations were found in moist roadside ditches and along the edges of farm fields. Based on
the aerial photography that you provided, it looks like your sites might have this type of suitable
habitat.
Given the limited work that I've done with this species, it seems to be late to germinate so I
wouldn't do surveys before late July; however, you should be able to conduct surveys through
the first hard frost. After looking at a bunch of Aeschynomene specimens in herbaria and the
field, I believe that there is considerable overlap in some of the key characteristics, especially
leaflet size and flower color. The best character that I've been able to use to distinguish A.
virginica from A. indica is stipe length. The stipes of mature fiuits on A. virginica tend to be
greater than 10 mm and for A. indica, less than 10 mm.
Good luck with your surveys and please let us know what you find. In August of this year,
Misty Franklin and I revisited most of the NCNHP sites for sensitive jointvetch and we didn't
find any plants at any of the historic locations. We would be happy to work with you and PCS
Phosphate to protect any sensitive jointvetch that you may find while allowing you to meet your
wetland mitigation goals.
Please contact me at [phone] extension 18 or Dale Suiter(cifws.uov if you have any
questions regarding sensitive j ointvetch.
C C= J Q? (?I,t ?v?c s s
Vi`w S??eEI'?E?,(
Regards
YDaelier
Endangered Species Biologist
I* I I
PCS Compensatory Mitigation Plan C-15 Hell Swamp/Scott Creek Watershed
Supporting Document C
•
-4-
?v F I f,
NCDENR
North Carolina Department of Environment and Natural Resources
Michael F. Easley, Governor
William G. Ross Jr., Secretary
November 7, 2007
Julia Kirkland Berger
CZR Incorporated
4709 College Acres Drive, Suite 2
Wilmington, NC 28403-1725
Dear Ms. Berger:
•
1 have checked the Natural Heritage Program records for the Bay City Farm and Hell Swamp
mitigation sites. We have no records of any rare species from these specific sites. The red wolf
(Canis rufus) is a wide-ranging animal that occurs in Beaufort County, and could potentially use
the sites. The pygmy rattlesnake (Sistrurus miliaris) is known within a couple of miles of the
Hell Swamp site and could also potentially be present there. In addition, a remnant of the very
rare Nonriverine Wet Hardwood Forest community type is present in the Hell Swamp area, and is
a significant feature of that site.
Sincerely,
Michael P. Schafale
Natural Heritage Program
?fNOV 1 2 ?Od7 11
J
by
NC
1601 Mail Service Center, Raleigh, North Carolina 27699-1601
Phone: [phone] FAX: [phone] l Internet: www.enr.state.nc.us/ENR
An Equal Opportunity 1 Affirmative Action Employer - 50% Recycled 110% Post Consumer Paper
•
PCS Compensatory Mitigation Plan C-16 Hell Swamp/Scott Creek Watershed
Supporting Document C
• s

North Carolina Department of Cultural Resources
State Historic Preservation Office
Peter B. Sandbeek, Adreinistntor
Michael F. Haaley, G--e, office of'Vehi- and Hi-ry
L. bech C. E--, Secretan• Division of Historical Resources
left cy 1. Crow, Deputy Seacraty Da id B-k, Di e¢or
November 1, 2007
Julia Kirkland Berger
CZR Incorporated
2151 Alternate AIA South
Suite 2000
Jupiter, FL 33477-3902
Re: Mitigation Site, Hell Swamp Wetland Restoration, West of Belhaven, Beaufort County, ER 07-2167
Dear Ms. Berger:
Thank you for your letter of October 2, 2007, concerning the above project.
We have conducted a review of the proposed undertaking and are aware of no historic resources that would be
affected by the project. Therefore, we have no comment on the undertaking as proposed.
The above comments are made pursuant to Section 106 of the National Historic Preservation Act and the
Advisory Council on Historic Preservation's Regulations for Compliance with Section 106 codified at 36 CPR
Part 800.
Thank you for your cooperation and consideration. If you have questions concerning the above comment,
contact Renee Gledhill-Earley, environmental review coordinator, at 919-807-6579. In all future
communication concerning this project, please cite the above referenced tracking number.
Sincerely,
R&F
Peter Sandbeck
?,.- - co=rcr---
Locadon: 109 F-Jonc, Street, 1leleigh NC 27601 Mailing Address: 4617, Mall Scn•icc Cenrcq Ralctgh NC 276994617 Telephone/Fax: ?9119) 307-6570/807-6599
is
PCS Compensatory Mitigation Plan C-17 Hell Swamp/Scott Creek Watershed
Supporting Document C
•
-6-
?/? United States Farm
USA Department of Service
Agriculture Agency.
July 9, 2008
Mr. Curtis H. Brown
Land Supervisor
PCS Phosphate Company Inc
Post Office Box 425
Aurora, North Carolina 27806
155 B Airport Road
Washington, North Carolina 27889
Tel: [phone], Extension 2
Fax: [phone]
Dear Mr. Brown:
:L]
With assistance from MRCS District Conservationist Rodney Woolard, I have
researched the "PC" (prior converted cropland) determinations on FSA tract numbers 1002,
3726, 3728 and 40674. We have verified that tracts 1002, 3726 and 3728 are determined
"PC:,
For tract 40674, we can not verify a "PC" determination. Mr. Woolard stated that
this property had been cleared after 1985. The majority of the property is non-wetland;
however, there are a few isolated wetlands present. Further documentation is available at
the Beaufort Soil & Wafer Office. Also, tract 40674 is no longer a valid tract number in FSA
records.
If we can be of further assistance, please feel free to contact us.
Regards,
J nie E. Setser
County Executive Director
The US Department of Agriculture (USDA) protibis discn1yulation in al its programs and actrribes on the basis of race, O*r, national origin, age, d5eb&ty, and
where app 'e, sex, madkal status, fan ial status, permdal slabs, ra4ion, sexual ofientatbn, genetic information, political beliefs, reprisal, or because all or
pail of an i nd:viduars income is derives foram any public assistance pp?gram. (Not all ptolibled bases applyy tD all programs.) Persons with dtabifibes who
"ire alternative means for omm mitatiun or program infomtatmn (9ra lie, large print, audiotgoe, etc.) shoo contact USDA's TAR£-ET Cer4er at (202) 720-
2800 (voice & TDD). To We a complaint of discrimma ion, write to USDA, Director, Office of Ciwl Ra hfs, 1400 Independence Avenue, S.W.. Washington, DC
202%94% or call [phone] (voice) or [phone] (TOO). USDA's an equal opportunity provider and employer.
L
PCS Compensatory Mitigation Plan
Supporting Document C
C-18 Hell Swamp/Scott Creek Watershed
C?

Julia Berger
From: Sam Cooper [[e-mail]]
Sent: Thursday, May 31, 2007 1:12 PM
To: [e-mail]; 'Julia Berger'; 'Jim Hudgens'; Norton Webster
Cc: 'Steve Trowell'; Jones, Scott SAW; Kyle Bames
Subject: CAMA AEC jurisdictional areas - Scott Creek
All,
l talked with Steve Trowell (Washington County rep for Division of Coastal Management) yesterday regarding CAMA AEC
jurisdictional areas associated with Scott Creek, Beaufort County. He and Terry Moore visited the site on 16 May 2007
and determined that public trust areas extend upstream to the 1" road/culvert crossing north of NC 92/99. This is the
main farm road crossing of Scott Creek in the McMullan Tract He also said they would claim some coastal marsh north
of NC 92/99. AEC shoreline would conform to a 30-foot offset of public trust areas, since this is an "inland" creek.
Samuel Cooper
CZR Incorporated
4709 College Acres Dr., Suite #2
Wilmington, NC 28403
•
910 392-9253 - phone
910 392-9139 - fax
[e-mail]
cp# 1745.59.66
No virus found in this incoming message.
Checked by AVG - www.avq.com
Version: 8.0.233 /Virus Database: 270.10.14/1918 - Release Date: 01127/09 07:26:00

PCS Compensatory Mitigation Plan C-19 Hell Swamp/Scott Creek Watershed
Supporting Document C
•
SUPPORTING DOCUMENT D
HELL SWAMP SITE EXISTING CONDITION STREAM CROSS SECTIONS
n
?J
U
•
•
Stream BKF Max BKF
Feature Type BKF Area BKF'Olidth De th De th VV/D BH Ratio ER BKF Elev TOB Elev
Drainage
Ditch F 10.1 11.72 0.86 1.18 13.58 2.7 1.2 -07
1.34
Cross-section 1- Scott Creek
4 ----- .?..,_.. 44
3
w
2
1
0
0
w 1 ....
-2
-3-
0 20 40 60 80 100 120 140
Station (ft) • . •o- - Bankfu II • • -0• Floodprone

Feature Stream
Type
BKF Area
BKF vVidth BKF
De th Max BKF
Depth
VV/D
BH Ratio
ER
BKF Elev
TOB Elev
Drainage
Ditch
F
12
2413
0.5
0.99
48.44
2.8
12
-1.3
0.5
Cross-section 2 - Scott Creek
•
4
3
$ 2
= 1
0
0
w -1
3
PCS Compensatory Mitigation Plan
Supporting Document D
Station (ft)
D-1
250 300 350 400
... 0-- BankfulI •.. 0---Floodprone
Hell Swamp/Scott Creek Watershed
0 50 100 150 200

Stream BKF klax BKF
Feature Type BKF Area BKF `"Adth Depth Depth ND BH Ratio ER BKF Elev TOB Elev'
Drainage
Ditch F 13.1 23.5 0.56 1.12 420 7 2.4 13 -0.9 0.71
Cross-section 3 - Scott Creek

4
3
2
C 1
0
R 0-
15-
-1
-3
0
50 100 150 200 250 300 350 400
Station (ft) • - -G • • • Bankfull • •. 0- - - Floodprone

Oucani nnr wiax trrtr
Feature Type BKF Area IBKFfiidth Depth Depth WiD BH Ratio ER BKF Elev TOB Elev
Drainage
Ditch F 1.9 6.64 0.28 0.52 23.46 2 1.5 -0.28 0.26
Cross-section 1- UT4

2.5
2
1.5
C 1
0
0.5-
w 0
-0.5
-1
0
PCS Compensatory Mitigation Plan D-2 Hell Swamp/Scott Creek Watershed
Supporting Document D
50 100 150 200 250 300
Station (ft) - 0 • Bankfull • • •o• -Flood prone

SUPPORTING DOCUMENT E
HELL SWAMP SITE WORK PLANS
C:

?J
Technical Memorandum
Project: Hell Swamp Restoration Site Prepared By: Baker Engineering
Subject: Narrative Regarding Construction Prepared For: PCS Phosphate
Techniques for Scott Creek Channel
Date: March 11, 2009
The purpose of this document is to provide additional information regarding the construction techniques
to be used in the restoration of the Hell Swamp site; specifically, the approach to filling and restoring
the Scott Creek canal. The overall intent of the restoration plan for the entire site is to restore the
drainage features as closely as possible to their condition prior to drainage and channelization for
agriculture. Therefore, all drainage ditches and canals within the restoration area, including the Scott
Creek canal, will be completely filled and the surrounding topography restored to pre-disturbance
elevations.
A longitudinal profile for the entire Scott Creek system is included in Figure 1, and provides a
comparison between the existing depth and elevation of the canal versus the proposed restoration
design. The example cross-sections that follow in this text are referenced in terms of the longitudinal
profile stationing shown in Figure 1.
0 At the upstream extent of the Scott Creek restoration, the design has been developed to restore the
functions of a small, braided headwater stream and wetland system. This will be accomplished by
filling the existing ditches and grading the valley bottoms such that flows will be diffuse, spreading
across the restored wetland floodplain (Figure 2). This approach will be used from longitudinal station
10+00 through 43+00, as indicated on the design plan sheets for the site.
Beginning at station 43+00 and continuing through station 55+70, the restoration design for Scott Creek
will involve the construction of a single-thread, meandering sand bed channel. This design approach is
based on analysis of erosive forces and sediment transport, as more thoroughly described in the
Mitigation Plan document for the site. Starting at station 43+00, the channel excavation will begin at a
shallow depth (0.2 - 0.3 feet) and gradually increase to a maximum depth of 1.0 - 1.5 feet for the
middle portions of the reach (Figure 3). Likewise, at the downstream end of the reach, the restored
channel depths will gradually decrease until reaching station 55+70 where the restored channel will lose
definition and will flow back into a braided, meandering stream system across the restored floodplain.
A slope of approximately 30:1 will be used at both ends of the single-thread section to gradually
connect the braided stream sections with the meandering, single-thread channel.
•
Page 1 of 6
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Page 2 of 6
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Cross-section 34+00
Headwaters Section
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5
4 - - - - - -
iK
0 3
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2
1 = - - - - Existing Ground
Proposed Design
0
0 20 40 60 80 100 120 140 160 180 200
Station (ft)
Figure 2. Example cross-section from the headwaters section (10+00 through 43+00) of
Scott Creek (looking downstream).
Cross-section 49+50
Single Thread Section of Scott Creek
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- - - - Existing Ground
Proposed Design
0 20 40 60 80 100 120 140 160 180 200
Station (ft)
Figure 3. Example cross-section from the single-thread section (43+00 through 55+70) of
Scott Creek (looking downstream).
r
Page 3 of 6
•
Oaker
From station 55+70 through station 62+00, the restoration approach will be similar to that used for the
headwaters section. The existing Scott Creek canal will be completely filled and the valley bottom
graded to approximate pre-disturbance contours and elevations (Figure 4). This design approach was
chosen due to the very low slope of the valley along this section that is more typical of braided stream
and wetland systems. Along this reach, the low point of the restored valley will be located near the
existing location of the Scott Creek canal. The restored valley bottom will be approximately 2.5 to 3.0
feet higher than the existing canal bottom, and will allow flows to transition to braided floodplain flow
prior to entering the wooded historic floodplain downstream (adjacent to the area of CAMA
jurisdiction).
Cross-section 56+50
Braided Section of Scott Creek, Upstream of CAMA Jurisdiction
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0 20 40 60 80 100 120
Station (ft)
- - - - Existing Ground
Proposed Design
140 160 180 200
Figure 4. Example cross-section from the braided section (55+70 through 62+00) of Scott
Creek, directly upstream of CAMA jurisdiction (looking downstream).
Beginning at approximate station 62+00 and continuing to station 88+00, the natural fall of the valley
lies to the south of the existing Scott Creek canal. As shown clearly in historic aerial photographs, the
Scott Creek canal along this reach was excavated sometime between 1964 and 1970. The canal was
excavated along the northern edge of the stream/wetland system and not along the topographic low
point of the valley, most likely due to extremely wet conditions in the center of the system. As a result,
much of the historic floodplain to the south of the canal is too wet for agricultural uses and has been left
wooded.
Beginning at station 64+80, an access lane through the trees follows along the northern side of the
existing Scott Creek channel. The lane has been used over the years to keep the canal clear of
blockages. This lane will be used during restoration to fill this section of the Scott Creek to pre-
disturbance contours. Spoil piles that were created during excavation of the canal will be deposited back
Page 4 of 6
•
•
•
into the canal as fill material. Once filled, water flow along the restored Scott Creek will follow the
topographic low point of the valley through the wooded area to the south (Figure 5). The flow will
follow a braided pattern through the floodplain as the system would have functioned prior to
disturbance.
Cross-section 63+50
Restored Floodplain Connection Near Upper Limits of CAMA Jurisdiction
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1
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0 50
100 150
Station (ft)
North South
- - - - Existing Ground
Proposed Design',
200 250
Figure 5. Example cross-section from the historic floodplain section (62+00 through
88+00) of Scott Creek, where flow will be directed onto the relic floodplain of Scott Creek
along its historic flow path (looking downstream).
Beginning at approximate station 92+30, the restored Scott Creek system must transition back to the
channelized canal at the downstream limit of the project. In this area, water surface elevations are
under tidal influence and due to ground elevations near 0.0, the area is most often under backwater
effect. Beginning at station 92+30, fill of the canal will be tapered down at a 10:1 slope until reaching
the existing bottom elevation of the canal (Figure 6). This fill slope will be completely submerged
under normal water conditions; therefore excessive scour or erosion of the fill material is not expected.
Page 5 of 6
•
Profile Through Channel Fill at End of Scott Creek Restoration
2
FLOW Floating Silt Curtains
(temporary)
1 /
Average Water Level I?
0
c -1 10
R
-2 Fill Material
W
-3
-4 Proposed Design.
- - - - Existing Canal
-5
9210 9220 9230 9240 9250 9260 9270 9280 9290 9300 9310
Station (ft)
Figure 6. Profile through channel fill at the end of the Scott Creek restoration reach.
Tributary Connections
Six smaller tributaries will flow into the restored Scott Creek system along its length (Figure 1). The
restoration approaches for these tributaries will be comparable to the design approach described for the
headwater sections of Scott Creek (station 10+00 to 43+00). The design approach will restore the
functions of small, braided headwater stream and wetland systems. This will be accomplished by
filling the existing ditches and grading the valley bottoms such that flows will be diffuse, spreading
across the restored wetland floodplain. The downstream grades of the tributary valleys will match those
of the restored Scott Creek floodplain, such that tributary flows enter the system without causing scour
or erosion.
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Page 6 of 6
C
SUPPORTING DOCUMENT F
HELL SWAMP HYDROLOGIC MODEL ANALYSIS SUMMARY
LJ
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• Hydrologic Model Analysis
Wetland hydrology is one of three determinant factors in the attainment of restored
wetlands. The Corps of* Engineers Wetland Delineation Manual (Wetlands Research Program
Technical Report Y-87-1) provides the minimum criteria that all types of wetlands possess. This
minimum definition is that wetland hydrology exists if, during the growing season, the water
table is normally within 1 foot of the soil surface for a continuous period of 5 to 12.5 percent of
the growing season. The growing season is accepted to mean the period of time between the
average last day in the calendar year having an air temperature of 28° Fahrenheit in the spring
and the first day having an air temperature of 28° Fahrenheit in the fall. Since the water table is
typically rainfall dependant, and rainfall and temperature vary by location, the Natural Resources
Conservation Service (NRCS) has published data that lists the average rainfall and the growing
season for a given region. This data, also known as the WETS data, shows the Aurora weather
station in Beaufort County has a growing season of 282 days and a normal rainfall of 50 inches.
DRAINMOD is a computer program that can be used to predict the water table depth on
a day-to-day basis over several years, thus allowing the model to predict hydrology for dry,
average and wet years. The program was written by Dr. Wayne Skaggs in 1978 at the North
Carolina State University and has been found to be reliable on a wide range of crops, trees, soils
and climatological conditions. The program is recognized by the NRCS and is used by their staff
for work in predicting the water table elevations in drained and undrained soils. Data needed for
the model includes hourly rainfall amounts and temperatures, soil properties including lateral
permeabilities, site drainage geometry, and crop type. A minimum of 20 years of rainfall and
temperature data should be used to capture dry, average and wet years.
Key parameters for each condition (existing, post construction riparian, and post
construction non-riparian) were used in the modeling. The key pre-restoration parameters for
modeling the existing system are: ditch spacing 200 feet, ditch depth 2 feet, surface storage 0.5
inch and average rooting depths representing typical crops.
For post restoration modeling, two types of wetlands were modeled: riparian and non-
riparian. Modeling for the post restoration, non-riparian areas are for those areas of the site that
are at least 200 feet from the stream or headwater valley invert which, from this distance, would
leave this location with no detectable drainage. The following parameters were used to represent
the non-riparian portion of the site: ditch spacing 400 feet with a ditch depth of 2 inches, surface
storage representative of the restored site was set at approximately 1.2 inches, and average
rooting depths typical of a forested condition.
Modeling for the riparian sections of the site represents those areas of the site that are
adjacent to the proposed headwater valleys. Valley width for this type of system can vary
between 100 and 200 feet. An average distance of 150 feet was used for the ditch spacing in the
model. The model will predict the water table depth at the midpoint between the 150 foot ditch
spacing; 75 feet. A ditch depth of 4 inches was used for the valley invert and a surface
roughness of 1.8 inches was used for the surface storage.
•
PCS Compensatory Mitigation Plan F-1 Hell Swamp/Scott Creek Watershed
Supporting Document A
Thirty-seven (37) years of data from the Belhaven weather station were used in the
model. Data from adjacent stations was used to supplement missing records of hourly
temperature or rainfall in the Belhaven set.
•
One indicator of the hydrology present is the longest number of consecutive days that the
water table is within the range of the wetland criteria. The table below shows the longest number
of consecutive days for the riparian and the non-riparian wetlands. In the time period modeled,
the riparian areas calculate to be wetter in 25 of 36 years, while the non-riparian areas are wetter
in 2 out of 36 years.
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Model Year
' Does not include overbank flooding or wind tides
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While these scenarios were modeled to represent average conditions across the restored
wetland site, it is important to note that the model predicts conditions at a specific location and
that the hydrology across the sit e is expected to be variable, based on topography, soils, and
varying water inputs. It is also important to note that DRAINMOD does not account for
overbank flooding events or wind tides and, therefore, model simulations for floodplains may be
conservative (i.e., actual conditions will likely be wetter than predicted). The modeled scenarios
provide a basis for estimating the average hydrologic condition over the restored site, however it
is important to note that the hydrology of the targeted restored wetland system (Coastal Plain
small stream swamp) is highly variable across a given site, supporting the ecological and
functional diversity that makes these systems valuable. Areas of the restored site that are drier
than the conditions predicted but still exhibit jurisdictional wetland hydrology should be
considered successful and part of a diverse wetland community.
PCS Compensatory Mitigation Plan F-2 Hell Swamp/Scott Creek Watershed
Supporting Document A