20061483 Ver 1_Restoration Plan_20101101

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UT Pembroke Creek Wetland
and Stream Restoration Site
Conceptual Repair Plan
Project # 283
Chowan County
Submitted to:
Pfl:U(. f=h."A
N(.DFNR-FF'II. 1652 Mail Service C'entLr. RAeil,h. N('27699-1652
Submitted: October 2010
WOMMMEMw4himm
KCI
ASSOCIATES OF NC
Landmark Center II, Suite 220
4601 Six Forks Road
Raleigh, NC 27609
Phone: [phone]
Fax: [phone]
Project Manager: Adam Spiller
Email: [e-mail]
Project No: 12090965B_20
UT Pembroke Creek KC/ Associates of North Carolina
EEP Project # 283 Conceptual Repair Plan
1.0 Executive Summary
1.1 Site Description
The North Carolina Ecosystem Enhancement Program (EEP) restored, enhanced, and
preserved wetlands and restored a headwater wetland valley, which is analogous to a
stream in this setting at the UT Pembroke Creek Site in Chowan County, North Carolina.
The 59-acre site is located within the USGS 8-digit HUC 03010205 of the Pasquotank
River Basin. Prior to restoration, the site was planted in row crops and had been ditched
since the 1920's. The restoration project in fall of 2007 restored and enhanced the
wetland by filling the ditches and focusing the hydrology into headwater wetland valleys.
The project also preserved a large forested wetland and decommissioned an animal waste
lagoon adjacent to the project. The project goals and objectives are listed below.
Goal: Modify the channelized water features, based on reference condition, with the
intent to restore the sites primary wetland functions such as nutrient cycling, flood
storage, and providing wildlife habitat.
Objectives:
• Improve water quality in the basin by filtering nutrients through on-site wetlands.
• Buffer flood flows downstream by increasing infiltration and storage areas.
• Design a waterway through the wetland complex with appropriate cross-section,
slope, and pattern as to provide nutrient filtering, flood storage, and wildlife
habitat while meeting the appropriate success criteria for the wetland.
• Improve terrestrial and aquatic habitat diversity.
• Establish a contiguous buffer along the project that can serve as a migration
corridor for local fauna.
• Use natural materials and native vegetation into the proposed restoration design to
the greatest extent possible.
• Establish a native forested riparian plant community within the non-wetland
buffer area.
• Establish a headwater wetland community.
• Provide an aesthetically pleasing landscape.
1.2 Adaptive Management Needs
The two roads that divided the site into three separate pieces were site constraints in the
original design of the project. The restoration installed road crossings on each road where
water can flow over the roads to facilitate the movement of water through the site. One
road (Road A) runs east-west and separates the two large restoration parts of the project,
and the other road (Road B) runs north-south and separates most of the preservation part
of the site from the restoration part (see Plan Sheet 2). Even with the installation of the
crossings, these two roads are still impeding the flow of water through the wetland. Road
B is specifically holding water in a large depression in the center of the site. During the
winter months, this area of standing water occupies almost three acres. This artificially
long hydroperiod is atypical for headwater wetlands. There is also a structure at the
bottom of the site that provides a stable flow path for water leaving the site. The elevation
of this structure impedes the natural flow of water through the site. It holds water in the
preservation wetland, preventing a natural drawdown throughout the site. In the future
some of these issues may be resolved by the increased evapotranspiration that comes with
more mature vegetation on the site. In the meantime the water needs to move down the
valley and draw down as it would in a natural wetland.
UT Pembroke Creek KC/Associates of North Carolina
EEP Project # 283 1 Conceptual Repair Plan
These hydrologic concerns are linked to problems with the planted vegetation
survivability. In the depressions with long durations of standing water many of the
planted trees have died. Some of the plants may have survived if more flood tolerant
species were planted and the planting stock had been more mature. In other parts of the
site Juncus effusus has become so thick and tall that it is outcompeting the planted
vegetation.
1.3 Additional Project Information
Summary information/data related to the occurrence of items such as beaver or
encroachment and statistics related to performance of various project and monitoring
elements can be found in project monitoring reports. Narrative background and
supporting information can be found in the mitigation and restoration plan documents
available on EEPs website. All raw data supporting the tables and figures in the
appendices are available from EEP upon request.
2.0 Repair Approach
2.1 Description
In early June 2010, KCI conducted a site survey at the UT Pembroke Site. This survey
was used to verify the elevations of the roads, the road crossings, the grade transition
structure, and the elevation of the surrounding wetland areas. The information from this
survey was used to develop this conceptual plan for repairs at the UT Pembroke Site to
correct the failures described in Section 1.2.
2.1.1 Piped Road Crossings
To ensure that Road A does not impede the natural surface flow between the two
halves of the restored wetland, three drainage pipes will be installed under the
access road that runs west to east. The pipes will be 8" schedule 40 PVC. These
pipes will increase the volume of water that can flow from the northern to the
southern half of the site without flowing over the top of the road. The current
elevation of the two crossings on Road A is 17.6'. The new pipes will be
installed approximately two tenths higher than the road crossings. This will
maintain primary flow through the headwater wetland valley, but larger flows
will access the pipes and not be impeded by the presence of the road, improving
drawdown time.
2.1.2 Additional Road Crossing
To reduce the quantity of standing water in the depressional area adjacent to
Road B an additional road crossing will be installed (see Plan Sheet 2). This
action will distribute some of this water across the road and into the preservation
wetland, where it will flow south to the grade transition structure. This will not
eliminate the standing water, because parts of the depression will still be lower
than the crossing, but it will reduce the area of standing water, especially in the
winter months and improve the drawdown time for the site. The current elevation
of the road adjacent to the depression is 15.5'. The elevation of the proposed road
crossing will be around 14.3' This elevation is only 0.2' below the wetland
valley's primary road crossing farther south on Road B, but between the
depression and the current primary road crossing there are high parts of the
wetland that hold water in depressions and prevent access to the crossing. Instead
of a large amount of grading within the wetland valley to adjust these elevations,
UT Pembroke Creek KCl Associates of North Carolina
EEP Project # 283 2 Conceptual Repair Plan
the additional road crossing is an alternative that will minimize direct
construction impacts to the restored wetland.
2.1.3 Alteration to Grade Transition Structure
Currently the grade transition structure contributes to the ponding and long
hydroperiod at the site. The top of the structure is set at 15.0', which is higher
than the southern parts of the preservation wetland and the primary road crossing
on Road B (14.5'). To reduce the amount of standing water in the preservation
wetland the top of the existing grade transition structure will be lowered. This
will involve removing the two logs from the top of the structure and grading
down the stone by approximately one foot. The second log structure is piping and
will be reconstructed at 13.9' in elevation. Filter fabric will be installed to
prevent piping. These measures will still maintain a small ponded area at the
southern part of the preservation wetland; however this structure will no longer
influence the flow and hydroperiod on the western side of Road B. This elevation
has been selected based on the current elevations of the water table in the
restored and preservation wetlands, which provide a reference for restoring a
seasonal drawdown of the water table across the project site. Since some parts of
the preservation wetland are lower in elevation than 13.9', there will still be
pockets of standing water, but the adjusted structure will restore a natural
drawdown process in the preservation wetland and the other wetlands south of
Road A.
2.1.4 Additional Planting
The site will also be planted with additional trees (see Plan Sheets 3 and 4). The
planting will include a variety of containerized and tubling materials. The areas
of standing water will be replanted with approximately 3,500 trees that are
tolerant of these conditions, such as bald cypress (Taxodium distichum) and water
tupelo (Nyssa aquatica). Other parts of the wetland restoration will be planted
with approximately 4,850 tublings to increase the woody species diversity and
fill in any areas that experienced increased mortality. Fifty-five 1" caliper trees
will be planted along portions of the conservation easement that are bordered by
row crops, and some will be put in the large ponded area.
2.2 Repair Goals and Objectives
Goals:
• Modify the wetland hydrology at the UT Pembroke Creek Site to decrease the
amount and duration of standing water in the restored and preserved wetlands
while maintaining the site's wetland hydrology.
• Increase the site's vegetative density, with particular attention to the areas with
standing water.
Objectives:
• Add piped road crossings between the northern and southern parts of the site to
facilitate surface flow.
• Build an additional road crossing between the southern part of the site and the
preservation wetland, providing a flow path for the excess standing water in the
restored wetland.
• Adjust the grade transition structure at the outlet of the preservation wetland to
decrease the amount of standing water in the preservation wetland.
• Plant native trees and shrubs in parts of the site that have experienced excessive
mortality of the previously planted vegetation.
UT Pembroke Creek KC/Associates of North Carolina
EEP Project # 283 3 Conceptual Repair Plan
2.3 Constraints Analysis
An overhead utility line runs adjacent to Road A. A fiber optic cable also runs underneath
this road.
2.4 Mitigation Projection
The repairs will alter the path of the headwater wetland valley (see Figures 1 and 2). By
installing the new road crossing, the headwater wetland valley will cross Road B and
flow south along the eastern side of the road to the site's downstream outlet. This change
will convert some area from wetland preservation to headwater wetland valley (stream)
restoration. This modified flowpath coincides with the natural valley through the site. The
flat valley is also the reason that Road B was built in this location. Since the road is not in
the conservation easement, the 100' corridor for the new location of the wetland valley
will extend to the western side of Road B. This change will decrease the preservation
credit, but increase the restoration credit at the site. In addition to altering the location of
the centerline at the new road crossing, this asset projection also corrects a conflict in the
centerline location that was carried over from the as-built documentation. This conflict is
illustrated in Figure 1, where the centerline is not in the center of the wetland valley. The
centerline has been repositioned and stationed in Figure 2. See Tables 1 and 2 for the
revised credit calculation.
2.5 Estimate of Cost
It is anticipated that the cost for this project, including all work associated with replanting
the site and modifying and adding structures, will total approximately $107,710.
UT Pembroke Creek KCI Associates of North Carolina
EEP Project # 283 4 Conceptual Repair Plan
TABLES AND FIGURES
UT Pembroke Creek KCI Associates of North Carolina
EEP Project # 283 5 Conceptual Repair Plan
Table 1. Project Restoration Components
Project Number and Name: 283 - UT Pembroke
Y
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Restoration C ? L
u L d wIi ? L
L
Original
Post Repair
Project Component Level L V ,=
p .a a C
Q a
Stationing
Stationing
Comment
00+00 to 34+73 00+00 to 34+81 This feature is 100 feet wide
Headwater Wetland Valley Restoration 4,488 if 4,344 If and and for its entire length,
40+00 to 58+72 40+00 to 57+18 encom assin 9.94 acres.
Riparian Wetlands Restoration 13.81 ac 14.41 ac N/A N/A
Non-Riparian Wetlands Restoration 4.46 ac 4.46 ac N/A N/A
Non-Riparian Wetlands Enhancement 5.26 ac 5.26 ac N/A N/A
Riparian Wooded Wetlands Preservation 8.95 ac 8.35 ac N/A N/A
Non-Riparian Wooded Wetlands Preservation 16.97 ac 16.97 ac N/A N/A
Table 2. Post-Repair Component Summations
Project Number and Name: 283 - UT Pembroke
Restoration Level Stream (If) Riparian Wetland (Ac) N
Ri
i
A U
l
d
A B
ff
A BMP
Riverine Non-Riverine on-
par
an (
c) p
an
(
c) u
er (
c)
Restoration 4,450 14.41 4.46
Enhancement 5.26
Enhancement I
Enhancement Il
Creation
Preservation 8.35 16.97
H Preservation
UT Pembroke Creek KCI Associates of North Carolina
EEP Project # 283 6 Conceptual Repair Plan

Figure 1. Pre-Repair Site Asset Map 6°
UT Pembroke Creek Chowan County, EEP Project # 283
xyr.; Wetland Valley Centerline (4,488 If) Non-Riparian Wooded Wetland Preservation (16.97 ac)
Headwater Wetland Valley (9.94 ac) Riparian Wetland Restoration (13.81 ac)
Non-Riparian Wetland Enhancement (5.26 ac) Riparian Wooded Wetland Preservation (8.95 ac) " KC1
Non-Riparian Wetland Restoration (4.46 ac) 200 1W o 200 400 S,3OC IATI S E)'f NC
Feet V

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..................
Figure 2. Post-Repair Site Asset Map
loft_ UT Pembroke Creek, Chowan County, EEP Project # 283
Wetland Valley Centerline (4,355 10 [77 71 Non-Riparian Wooded Wetland Preservation (16.97 ac)
??,(}?v?t!ttl ® Headwater Wetland Valley (9.94 ac) tZ] Riparian Wetland Restoration (14.41 ac) KCI
Non-Riparian Wetland Enhancement (5.26 ac) = Riparian Wooded Wetland Preservation (8.35 ac)® Non-Riparian Wetland Restoration (4.46 ac) Zoo 100 0 200 400 ASSO IATP-, of TIC
Feet
PLAN SHEETS
UT Pembroke Creek KCI Associates of North Carolina
EEP Project # 283 8 Conceptual Repair Plan

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