20080737 All Versions_Mitigation Information_20080905

Privateer Farm
Addendum to the NCDOT UMBI
Date 9/5/08
A. Site History
The Privateer Farm stream and wetlands restoration site is located in United States
Geological Survey (USGS) Hydrologic Unit (HU) 03030005 and North Carolina
Division of Water Quality (NCDWQ) Cape Fear River sub-basins 15 and 16 along Little
Alligator Swamp and Harrison Creek The project is located in the Southeastern Plains
Level III Ecoregion (Southeastern Floodplains and Low terraces Level IV Ecoregion) and
includes portions of Cumberland and Bladen Counties, approximately 6 miles from the
southern boundary of CU 03030004 (see Figure 1) The surrounding area includes
hundreds of elliptical shaped wetlands, called Carolina Bays, and is listed by the National
Audubon Society as an Important Bird Area (IBA) for its unique habitats
The Privateer Farm Mitigation site encompasses a 430-acre boundary contained within
the 4,600 acre farm property The property owners, Ms Sharon Valentine and Mr
Marvin Johnson, intend to restore the entire property to its historic wetland ecosystem
The restoration project involving historic Harrison Creek is the first step toward this goal
and is the centerpiece of the restoration effort (see Figure 2) The North Carolina
Department of Transportation (NCDOT) holds a conservation easement over the
restoration site, the easement is included in Appendix A The remainder of the farm
property to be restored will likely enter into the Natural Resources Conservation Services
(MRCS) Wetlands Reserve Program
Prior to restoration, stream and riparian functions on the site had been severely impacted
as a result of agricultural conversion Harrison Creek was channelized in the early 1980s
to reduce flooding and provide a drainage outlet for the extensive ditching across the site
Asa result, the stream existed as a very large canal through the project site Backwater
conditions were imposed along extensive sections of the stream due to culverts and debris
blockages, and natural riffle and pool sequences were nearly non-existent Harrison
Creek is classified as Class C waters, which are suitable for aquatic life propagation and
survival, fishing, wildlife, secondary recreation, and agriculture
B. Project Goals
The goal of the project is to restore functional stream and wetland systems to the Site
The stream system that historically flowed through the Site was channelized and, as a
result, was highly incised ("Gc" type stream - Rosgen classification) prior to restoration
The natural channel design for the restored stream involved the construction of a new,
meandering channel across the agricultural fields The furthest upstream portion of the
project used sections of the remnant historic channel for Harrison Creek that were still
visible within the existing wetland areas The remaining portion of the restored channel
was constructed as a Rosgen "C" stream type with design dimensions based on historic
reference parameters for Harrison Creek These reference parameters were determined
from historic aerial photographs, the topography of the valley, and local reference reach
information The total stream length across the Site was increased from approximately
25,000 LF to 34,000 LF Restoration activities for the Site involved moving the stream
channel back to its historic location and elevation, and filling drainage ditches to raise the
local water table and restore wetland and stream hydrology The plan also included
scarification of the fields and breaking of the local plow pan to increase surface water
storage and provide a range of hydrologic conditions suitable for a variety of native
wetland plant species
C. Site Construction
While restoration of the stream channel followed the historic pattern of Harrison Creek,
the restored stream would most appropriately be considered a tributary to Harrison Creek
Flow from the headwaters of Harrison Creek was channelized around the perimeter of the
farm as part of the conversion of the site to agricultural land Due to elevation differences
between the restored stream and the channelized stream around the perimeter of the farm,
flow from the headwaters of Harrison Creek could not be diverted into the restoration
channel without causing significant hydrologic trespass issues beyond the property
boundary of Privateer Farm Therefore, the restored channel was designed to function as
a headwater to Harrison Creek, with a drainage area of approximately one square mile,
increasing to a drainage area of six square miles at the downstream end of the project
(Figure 2)
Due to the extensive length of stream restoration and changes in drainage area from the
beginning to the end of the project, the project was divided into five stream reaches
Design ratios were the same for each design reach and were based on reference reach
information The size of each restored channel reach increased from upstream to
downstream to reflect the increasing drainage area
The channel design allows discharges greater than bankfull flows to spread onto the
floodplam, dissipating flow energies and reducing stress on streambanks In-stream
structures were used to control stremmbed grade, reduce stress on streambanks, and
promote bedform sequences and habitat diversity The in-stream structures consisted of
root-wads, log vanes, and log weirs that promote a diversity of habitat features in the
restored channel Streambanks were stabilized using a combination of erosion control
matting, bare-root planting, and transplants Transplants provided immediate shading to
the restored stream, as well as living root mass to increase streambank stability and create
holding areas for fish and other aquatic biota
The new stream channel was constructed "in the dry" and all stabilization practices were
in place prior to routing stream water into the new sections of channel When
construction of a new reach was completed, plugs were installed in the old channel to re-
direct the water into the new channel After the water had been diverted, the process of
filling the old channel with soil began
The large road that ran from north to south through the middle of the project area was
graded to floodplain level in order to fill the road-side canals, and to allow flood flows to
spread over the restored floodplain The north-south road was completely removed within
the limits of the project Two roads that cross the project area from east to west were left
in place and to allow for access across the restoration site to other parts of the farm
The as-built data collected after construction documented that the total area of restored
riverme wetlands was 402 5 acres (excluding 2 5 acres for road accesses), with 25 acres
of enhanced rtverme wetlands, and 34,005 LF of restored stream channel Construction
of this project was completed in April 2005
Bare root trees were planted within all areas of the conservation easement A minimum
50-foot buffer was established along all restored stream reaches In most areas, the final
buffer area was more than several hundred feet wide and included restored wetland areas
In general, bare-root vegetation was planted at a target density of 680 stems per acre, or
an 8-foot by 8-foot grid Planting of bare-root trees was conducted during the dormant
season, with all trees installed prior to March 20, 2005
Observations were made during construction of the Site regarding the relative wetness of
areas to be planted Planting zones were determined based on these assessments, and
planted species were matched according to their wetness tolerance and the anticipated
wetness of the planting area Species planted are summarized in Table 1
Table 1 ,
Bare-root Tree Species Planted Across the Privateer Farm Restoration Site
Common Name Scientific Name':' Percent 1 i Total Wetness Tolerance
lanted Number
bv Species of Stems
Willow oak Quercus phellos 86% 23,300 weak - moderate
Swamp chestnut Quercus michauxtt 86% 23,300 weak
Laurel oak Quercus launfolia 60% 16,200 moderate - weak
Overcup oak Quercus lyrata 63% 17,000 moderate
Swamp tupelo Nyssa bzflora 79% 21,300 tolerant
Water tupelo Nyssa aquatzca 82% 22,000 tolerant
Bald cypress Taxodium distichum 116% 31,200 tolerant
Water oak Quercus nigra 86% 23,300 weak - moderate
Sycamore Platanus occidentahs 108% 29,200 moderate
Green ash Fraxinus pennsylvanica 108% 29,200 moderate
Shumard oak Quercus shumardaa 65% 17,500 weak
Cherrybark oak Quercus pagoda 59% 15,900 weak -intolerant
Notes
1 Based on informati on from US Army Corps of Engineers (USACE) Wetland Research Program
(WRP) Technical Note VN-RS-4 1 (1997)
D. Current Status
The project is nearing the end of the fourth year of monitoring (as of September 2008)
Data for Year 4 monitoring will be collected during the fall of 2008, and will include data
from 30 hydrologic monitoring stations and 15 vegetation monitoring stations placed
throughout the Site, in addition to stream monitoring data, as required by the approved
Restoration Plan Monitoring data for the Privateer Farm Site are summarized below
Vegetation Momtorm
Fifteen vegetation monitoring plots are located randomly throughout the project site The
vegetation monitoring for 2007 indicated an average survivability of 498 stems per acre,
which is on a trajectory to achieve an average vegetation survival criteria of 320 stems
per acre surviving after the fifth growing season Three monitoring plots had lower than
expected survivability rates for Year 3 The survivability rates for Plots 11, 13, and 14
ranged from 33 to 49 percent and densities ranging from 279 to 331 Volunteer species
were noted in Plots 8 and 14 Both of these plots demonstrated the presence of numerous
Acer rubrum (red maple) saplings that were 3 inches to 1 foot in height Plot 14 also
showed Liquidambar styraciflua (sweet gum) saplings growing within the plot boundary
If low survivability continues to be an issue, supplementary plantings may be necessary
Stream Flow Monitoring
Two automated stream stage gages were installed along the restored stream after
construction, with one gage installed at the upstream end of the project and the other at
the downstream end of the project Both streamflow gauges have documented the
occurrence of at least one bankfull flow event during each of the first three years of
monitoring
Geomorphic Monitoring
Sixty-eight permanent cross-sections are installed along the restored stream, at intervals
of approximately 500 - 600 feet Cross-section data collected for Year 3 indicate very
little adjustment in channel dimension has occurred since restoration of the stream
channel, with all monitored cross-sections maintaining their design parameters within
acceptable ranges Some cross-sections indicate that minor bed scour features observed
during Year 2 have filled back to as-built conditions during Year 3 (Cross-sections 6, 7,
9, 16 and 22) Several pool cross-sections are beginning to show the formation of point
bar features (Cross-sections 20, 32, 42, 44, 54) There are no cross-sections that indicate
that presence of bank erosion or head-cutting, and no areas of bank erosion or head-
cutting have been observed on the site during Year 3
The longitudinal profile data for Year 3 indicate that minor adjustments in bed elevation
are occurring along the design reaches, but changes are on the order of several tenths of a
foot in most locations This is attributed to the dense growth of vegetation along the
channel toes that restricts flows near the center of the channel This restriction under low
flow conditions concentrates flows and provides for some scouring of the thalweg in
certain reaches However, this scouring is considered a normal bed adjustment process
and has not been observed to cause channel instability or head-cutting Log weir grade
control structures were installed along all restored stream reaches for this purpose, and

the longitudinal profile data indicate that these structures are maintaining grade Based
on current monitoring data, the stream is functioning as designed
Photographic Monitoring
Photographs were taken in October of the Year 3 growing season to document the
evolution of the restored stream channel Restored pools have maintained a variety of
depths and habitat qualities, depending on the location and type of scour features (logs,
root wads, etc ) Permanent vegetation seeded on the restored stream banks and
floodplams has become dense and lush Photographic monitoring indicates that the site is
on a trajectory to meet restoration goals
Wetland Hydrology Monitoring
The total monthly rainfall for the 2007 growing season was below the approximated
long-term average for the area, as summarized in Table 2 For much of 2007, North
Carolina was considered to be in severe drought conditions Data collected during Year 3
from the fifteen automatic monitoring well gauges at the Site showed that groundwater
levels met hydrologic success criteria for only five of the gauges The ten automatic
gauges that did not meet the success criteria exhibited a continuous hydropenod from 3 1
percent to 9 1 percent However, the gauges did exhibit a cumulative hydropenod from
10 to 58 days or 3 9 percent to 24 0 percent of the Year 3 growing season, indicating that
the locations experienced significant wetness, but the water table, fluctuated rapidly,
therefore, surface saturated conditions during the 2007 growing season were not present
for long periods of time It should be noted, that the groundwater conditions recorded at
the Privateer Farm site were consistent with the conditions noted at the reference site,
indicating that the failure to meet success criteria was more likely attributable to the
uncharacteristically low regional rainfall totals rather than a design flaw or failure
Table 2
Comparison of Historic Average Rainfall to Observed Rainfall (Inches) Average, 2007
Precipitation
January 4 16 3 06 5 13 2 75
February 3 43 2 22 411 2 54
March 4 37 3 24 5 22 1 42
Apnl 3 06 1 77 4 13 2 91
May 3 29 2 25 4 2 1 46
June 4 18 2 36 5 02 2 95
July 5 21 3 69 6 7 2 61
August 521 3 54 6 36 0 88
September 4 77 2 36 6 46 2 8
October 3 15 1 73 3 76 N/A
November 2 88 1 75 3 76 N/A
I December 3 24 2 3 3 81 N/A
In addition, data from monitoring Years 1 and 2, when rainfall conditions were closer to
normal, indicated that the site did meet hydrologic success in those years During 2008,
more "typical" rainfall totals were reported for the site Therefore, it appears that the site
is performing as designed and the abnormally dry conditions encountered in 2007 will
not prevent the site from meeting restoration goals
During Year 3 of the monitoring period AW6 and AW24 dataloggers were replaced due
to communication errors, while wells MW25, AW24, AW20, AW 19, AW 13 and AW8
were either damaged or destroyed The site visits at these gauge locations showed signs
of bear activity around the wells such as, bite marks on PVC and bent support posts All
dataloggers or well casings have been either replaced or repaired and the aforementioned
wells are now fully operational and collecting data when Monitoring Report 3 was
prepared Complete monitoring reports for the Privateer Farm site are available at
http //www ncdot org/doh/pieconstiuct/l)e/iieu,/Monitonng/defatilt html
E. Community Types
Following construction, the as-built data indicated that the total area of restored rivenne
wetlands was 402 5 acres (excluding 2 5 acres for road accesses), with 25 acres of
enhanced riverme wetlands The upper portion of the project area to the northern road
crossing (approximately 72 acres) has subsequently been classified as Headwater Forest
The middle portion of the project area (from the northern road crossing to the southern
road crossing the property (approximately 333 acres), has been classified as Bottomland
Hardwood Forest The lower portion of the project area (approximately 25 acres) has
been classified as Rivenne Swamp Forest
All three wetland types were evaluated in the summer of 2007 with the North Carolina
Wetland Assessment Method (NCWAM) and received an overall score of high quality
The Rrverme Swamp and Bottomland Hardwood forests received a low score for the
habitat function These low habitat scores reflect the lack of mature trees and expected
strata However, the habitat scores are expected to improve over time as the vegetation
trends toward the expected canopy and diversity
Based on vegetation monitoring, it appears that all of the wetlands on the site are on a
trajectory to meet restoration goals Of the fifteen vegetation plots, twelve are on a
trajectory to exceed the project goals of 320 stems per acre after five years The three
plots that were determmed to be currently below the desired trajectory (Vegetation Plots
11, 13, and 14) are located in the Bottomland Hardwood forest section For Vegetation
Plot 11, surviving stream species were predominantly sycamore and swamp chestnut
For Vegetation Plot 13, surviving tree species are oak species (willow oak, overcup oak,
and laurel oak), and for Plot 14 surviving tree species are predominantly sycamore Total
stem counts for these sites have been relatively consistent for Plot 13 since July 2005,
while steeper declines were reported for Plots 11 and 14 Total stem counts for July 2005
were 26 for Plot 11, 17 for plot 13, and 30 for Plot 14 In September 2007, total stem
counts were 19 for Plot 11, 16 for Plot 13, and 16 for Plot 14
Three sections of the restored stream, corresponding to the three wetland evaluation
locations, were evaluated using the draft North Carolina Stream Assessment Method
(NCSAM) during the summer of 2007 While the NCSAM is still under development,
the draft metrics and procedures were used to gain a general measurement of restored
stream function The stream sections adjacent to the Riverme Swamp and Bottomland
Hardwood forests received a low quality score for the habitat function These scores are
characteristic of a site with low richness and diversity of benthic macromvertebrates, lack
of mature vegetation in the stream-side area and lack of in-stream habitat types The
drought conditions and age of the site contributed to these reduced scores However,
these factors are expected to improve over time since the site is protected in perpetuity
The NCSAM forms for Privateer Farms can be found at
http //www ncdot orf;/doh/preconstruct/pe/neu/Monitoring/Pnvateei Farms I pdf
E. Proposed Credits
The following credit ratios are used in the calculation of mitigation credits
Stream Restoration - 1 1
Wetland Restoration - 1 1
Wetland Enhancement - 2 1
Based on the ratios above, the Privateer Farm Mitigation Bank is expected to generate the
following amounts of mitigation credit
Riverme Wetlands - 415 credits (402 5 acres of restoration and 25 acres are
enhancement)
Streams - 34,005 feet (all restoration)
F. Credit Release Schedule / Available Credits
A total of 34,005 stream and 415 wetland credits are expected to be generated by the
Privateer Farm project
Wetland Credit Release Schedule
If deemed appropriate by the Interagency Review Team (IRT), 15% of a bank's total
restoration credits shall be available for sale immediately upon completion of all of the
following
1 Execution of the mitigation banking instrument by the Sponsor, the Corps, and
other agencies eligible for membership in the IRT who choose to execute the
agreement,
2 Approval of the final mitigation plan,
3 Delivery of the financial assurances,
4 Recordation of the preservation mechanism, as well as a title opinion acceptable
to the Corps covering the property,
Additionally, no later than the first full growing season following initial debiting of the
bank, the Sponsor must complete the initial physical and biological improvements to the
bank site pursuant to the mitigation plan Subject to a bank sponsor's continued
satisfactory completion of all required success criteria and monitoring, additional
restoration mitigation credits will be available for sale by a bank sponsor on the following
schedule
• 10% after first year, if interim success measures are met (total 25%),
• 10% after second year, if interim success measures are met (total 35%),
• 10% after third year, if interim success measures are met (total 45%),
• 15% after fourth year, if interim success measures are met (total 60%),
• 15% after fifth year, if Success Criteria are met (total 75%), and
• 25% after fifth year, if the bank site meets the overall objectives and Success
Criteria set forth in the mitigation plan (total 100%)
The above schedule applies;only to the extent that the bank sponsor documents
acceptable survival and growth of planted vegetation, and attainment of acceptable
wetland hydrology as described under the success criteria in the mitigation plan The final
25% of credits will be available for sale only upon a determination by the IRT of
functional success as defined in the mitigation plan
Stream Credit Release
The following credit release schedule applies only to those stream projects where
Restoration or Enhancement I has been performed where pattern, dimension, and profile,
or dimension and profile (respectively) have been improved
If deemed appropriate by the,IRT, 15% of a banks total stream credits shall be available
for sale immediately upon completion of all of the following
1 Execution of the mitigation banking instrument by the Sponsor, the Corps, and
other agencies eligible for membership in the IRT who choose to execute the
agreement,
2 Approval of the final mitigation plan,
3 Delivery of the financial assurances,
4 Recordation of the preservation mechanism, as well as the title opinion covering
the property that is acceptable to the Corps
Additional stream credits would be available according to the following release schedule
• Construction release 15 % upon completion of all initial physical and biological
improvements made pursuant to the mitigation plan (30% cumulative)
• After year 1 10% provided channel is stable and all other success criteria are met
(40%)

• After year 2 10% provided channel is stable and all other success criteria are met
(50%)
• After year 3 10% provided channel is stable and all other success criteria are met
(60%)
• After year 4 10% provided channel is stable and all other success criteria are met
(70%)
• After year 5 15% provided channel is stable and all other success criteria are met
(85%)
A reserve of 15% of the banks total stream credits shall be released any time after 2 bank-
full events have occurred, in separate years, provided the channel stable and all other
success criteria are met In the event that less than two bank-full events occur during the
monitoring period, remaining credit release shall be at the discretion of the IRT
The current debit ledger for the Privateer Farm site is provided below
Table 3
Current Credit Ledger for the Privateer Farm Site

* it 1 :_0111

.,?Fe. ,
AjVer

x

N r
ame Basin y ?t?l•
1 a 1 P Debit
Comment
Privateer
Site Cape Fear 3030004 U-2519 1 5 1 ratio,
riverme
Warm Stream mitigation
Restoration 25,676 5,828 19,848 for non-
Riverme rrverme
Wetland impact
Restoration 125 62 52 97 72 65
-7 G. Proposed Geographic Service Area
The service area for the Site is proposed as the portion of the Southeastern Plains Level
III Ecoregion of the Lumber and Cape Fear River Basins This includes portions of the
following CU's 03030004, 03030005, 03030006, 03030007, 03040203, and 03040204
This proposal is based on the following factors
• The Site is constructed and in its fourth year of monitoring
• The Site is meeting success criteria, is a large, high quality mitigation site, and is
showing trends toward a mature forested wetland and stream system
• The Site is in the same Level III Ecoregion As reported by Gnffith and Omemik, the
ecoregions were developed to denote areas of similarity in ecosystems, similarity in
the type, quality, and quantity of environmental resources, and are relevant federal
and state resource management agencies' goal to integrated ecosystem management