UpperSilverCreek_MitigationPlanAddendum_WithCoverLetter_30Nov2015_Final

Innovation Done Right We Make a Difference
I N T E R N A T I O N A L
November 30, 2015
Paul Wiesner
Western Supervisor, Project Management
North Carolina Department of Environmental Quality
Division of Mitigation Services
5 Ravenscroft Dr., #102
Asheville, NC 28801
Subject: Mitigation Plan Addendum for the Upper Silver Creek Restoration Project in Burke
County
Catawba River Basin — CU#03050101-050050
Service Contract No. 003270
DMS No. 94645
Baker Project No. 120598
Dear Mr. Wiesner,
Please find enclosed the revised Mitigation Plan Addendum for the Upper Silver Creek Restoration
Project in Burke County. It is based on field discussions and written comments from DMS, Corps of
Engineers, and NC-DEQ. Included are revised asset tables and maps detailing the reclassification of
0.42 WMUs from riparian to non -riparian wetlands.
If you have any questions concerning the Addendum or require any additional information, please feel
free to contact me at 919-481-5731 or via email at [e-mail].
Sincerely,
1� 14-
Scott King, LSS (#1301), PWS (#1908)
Michael Baker Engineering, Inc.
Michael Baker Engineering, Inc.
pa -F-LPA xw&A auvPoRT MBAKERINTLCOM 8000Regency Parkway, Suite 600,Cary NCz7518
Office: 919.463.5488 1 Fax:[phone]

Upper Silver Creek Stream and Wetland Restoration Project — Mitigation Plan Addendum
Michael Baker Engineering respectfully submits this wetland WMU reclassification as an addendum to
the mitigation plan for the Upper Silver Creek Restoration project (DMS Project #94645). The revised
table reclassifies 0.42 WMUs from riparian to non -riparian wetlands.
On October 26, 2015, Baker personnel met on site with representatives from the Corps of Engineers, NC
Division of Water Resources, and NC Division of Mitigation Services to inspect existing wetland
mitigation areas proposed for reclassification from riparian to non -riparian. After discussion, it was
determined that the wetland area located within a seep along a slope in the southwestern portion of
the project was located outside of the geomorphic floodplain and acceptable for reclassification (see
Figure 2). Currently the wetland area is classified as predominantly Riparian Wetland Enhancement
(JDW1A) at a 2:1 credit ratio for 0.21 WMUs, with two pockets of Riparian Wetland Restoration (areas
R1A and R113) at a 1:1 credit ratio for 0.21 WMUs. This addendum simply reclassifies those WMUs as
Non -Riparian (see Table ES.2.Rev).
During the field investigation Baker also agreed to install an additional monitoring well in the newly
reclassified non -riparian wetland area (see Figure 2). It will be installed in the upper portion of the
wetland enhancement area over the winter 2015 before the growing season begins in 2016 to capture
groundwater data for Monitoring Year 2 onward. The existing monitoring well located in this non -
riparian area was installed in one of the wetland restoration areas. Thus this non -riparian wetland area
will have two groundwater monitoring wells located within it.
Additionally, during the GIS analysis conducted to reclassify and revise the WMUs for the project, two
errors were discovered in the original mitigation plan calculations of the acreage for the R4 and R5
riparian wetland areas proposed for restoration. The acreage for R4 was reported as 0.62 ac but is
actually 0.44 ac, while the acreage for R5 was reported as 1.53 ac but is actually 1.29 ac. These errors
subsequently resulted in the miscalculation of the total WMUs for the project, with a mistaken reported
overage of 0.41 WMUs. The corrected WMU values are reflected in the revised asset Table ES.2.Rev.

Table ES.2: The original wetland mitigation plan asset table (from approved the mitigation plan,
dated October 2013):
Table ES.2 Upper Silver Creek Mitigation Plan Overview (Wetlands)
UpperSilver Creek Mitigation Plan-EEP Project 494645
—Comments
_,
ENHANCEMENT WETLANDS
Jurisdictional Wetland 1 (JDWla) - Riparian
Existing jurisdictional wetland; 2:1 enhancement proposed to include minor
Enhancement
0.53
0.53
2:1
0.26
ding in areas of fill and altered drainage patterns, replanting of mowed
(2:1)
vegetation to include woody bottomland wetland species. Some peripheral
benefit from hydrology enhancements to tributary (UT3) and mainstem.
Jurisdictional Wetland 1 (JDWlb) — Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 to include
significant enhancements to hydrology and vegetation. UT3 will be raised to
ring hydrology within Y of the surface and will be routed along the
Enhancement
0.9
0.9
2:1
0.45
periphery of this wetland. In addition, hydrology from the mainstem will be
(2.1)
augmented (base flow elevation raised by 0.5') and will be routed closer to
e wetland area. Mowed vegetation will be planted with woody bottomland
etland species.
Jurisdictional Wetland 2 (JDW2) —Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 (typical
enhancement ratio) to include plug of existing drainage ditch which has
Enhancement
0.51
0.51
2:1
0.25
altered wetland hydrology, planting of woody bottomland wetland species to
(2.1)
replace mowed grasses, minor grading of lower part of wetland and increase
f baseflow elevation of mainstem by approximately 1.5 feet.
Jurisdictional Wetland 3 (JDW3) — Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 to include
"nor grading to remove less than 12" of overburden, reduction of hydraulic
gradient by plugging existing drainage ditch and raising baseflow elevation
Enhancement
0.03
0.03
2:1
0.02
f mainstem (these will serve to decrease the gradient of groundwater flow
(2.1)
within the project area, resulting in an increased hydroperiod for adjacent
wetlands). The area will be planted with woody wetland species to replace
owed grasses.
Jurisdictional Wetland 4 (JDW4) — Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 to include
eduction of hydraulic gradient to adjacent areas by plugging existing
Enhancement
0.24
0.24
2:1
0.12
drainage ditch and raising baseflow elevation of mainstem. The mainstem
(2:1)
ill also be relocated which should increase the influence of its hydrology o
adjacent areas and decrease the gradient of groundwater flow. The area will
e planted with woody wetland species to replace mowed grasses.
Jurisdictional Wetland 5 (JDW5) — Riparian
Enhancement
81
0..81
0
2:1
0.40
xisting jurisdictional wetland; enhancement proposed at 2:1 to include
rc
(2.1)
moval of overburden (fill) from areas where vegetation reflects the altered

soil conditions, plugging/removal of ditching in the immediate vicinity and
so upstream along the long linear ditch that parallels the stream,
enhancement of wetland hydrology as a result of Priority I stream restoration
d an increased base flow elevation, and increased storage/runoff retention
y disconnecting direct ditch connections to the main channel and increasing
onding and recharge.
Jurisdictional Wetland 6 (JDW6) — Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 to include
diversion of additional overland flow into the area, raising of mainstem of
Enhancement
0.30
0.25
2:1
0.13
Silver Creek to create high level of groundwater and floodplain connectivity
(2.1)
with wetland, replanting to establish woody wetland species to replace
owed grasses.
SUBTOTAL
3.32
3.27
1.63
RESTORATION WETLANDS
Restoration Wetland 1 (Rl) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
Restoration
0
0.21
1:1
0.21
nor grading to create connectivity to hydric soils, route overland flow into
areas to increase ponding and infiltration, and planting with target of
hardwood bottomland forest ecosystem to replace mowed grasses.
Restoration Wetland 2 (112) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
removal of less than 12" of overburden from past fill activities thought to be
Restoration
0
1.22
1:1
1.22
associated with road construction, remeandering of UT3 through the middle
f the proposed restoration wetland to restore hydrology, and replanting with
wetland herbaceous and hardwood bottomland forest ecosystem to replace
�niowed grasses, predominantly fescue.
Restoration Wetland 3 (R3) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
removal of less than 12" of overburden from past fill activities thought to be
associated pasture enhancement, plugging of drainage ditch that extends into
Restoration
0
0.18
1:1
0.18
the area to restore hydrology (reduce hydraulic gradient), and potential to
divert some larger stream flows from UT3 into this vicinity through overland
hannels that would mimic a complex floodplain with abandoned channels
d abundant roughness elements affecting floodplain flow paths.
Restoration Wetland 4 (R4) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
removal of less than 12" of overburden from past fill activities thought to be
associated with channel dredging, channel restoration to include removal of
Restoration
0
0.62
1:1
0.62
levy along mainstem creek bank to enhance floodplain access and also to
wise base flow elevation relative to floodplain elevation, and replanting with
edand herbaceous and hardwood bottomland forest ecosystem to replace
owed grasses (predominantly fescue).
Restoration Wetland 5 (R5) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
removal of less than 12" of overburden from past fill activities thought to be
associated with pasture enhancement, removal of adjacent ditch should
Restoration
0
L53
1:1
1.53
educe groundwater drawdown rate by raising the potentiometric surface in
this area, and replanting with wetland herbaceous and hardwood bottomland
orest ecosystem to replace mowed grasses.
Restoration Wetland 6 (R6) — Riparian
Restoration
0
1.54
1:1
1.54
Restoration wetland; credit proposed at 1:1. Proposed activities will include
removal of less than 12" of existing overburden thought to be placed for

pasture enhancement, removal of ditch features at the top of the wetland and
adjacent to the mainstem that are reducing ponding volumes and recharge,
wising the baseflow level and modifying the typical design cross-section of
e mainstem in this area to increase floodplain activation frequency, and
constructing minor diversions of overland flow and flow from high flow
Ients on UT 1 into the area to further enhance hydrology. The area will be
eplanted with a target hardwood bottomland forest plant community to
eplace existing mowed grasses and herbaceous wetland species.
SUBTOTAL
0
5.3
5.30
CREATION WETLANDS
Creation Wetland 1 (Cl) — Riparian
Creation wetland; credit proposed at 3:1. Proposed activities to include
grading of existing drainage ditch to a more natural and broad swale with a
ow gradient and intermittent ponding areas. This is already a high recharge
area, but reconnection of the main stem with the floodplain will create a
Creation
significant increase in flooding to this area as well. Higher global water
(3:1)
0
0.99
3:1
0.33
tables will reduce groundwater flow out of the area. The increase in
hydrology and the grading efforts should create conditions necessary for
etland creation. The area will be replanted with a target hardwood
ottomland forest plant community to replace existing mowed grasses and
erbaceous wetland species.
SUBTOTAL
0
0.99
0.33
etland Summary
IF
PIK almh&l
Restoration 5.30 1:1 5.30
Comments
Enhancement 3.27 2:1 1.63
Creation 0.99 3:1 0.33
TOTAL WMUs 7.26

Figure ESA: The original mitigation plan asset map
0
�J
♦
1 lasoL Reach I
•'
LEGEND:
Proposed Project Stream Components
o Enhancement II
�Pnouty II Restoration
f�
}}
Aa
�Priodty I Restoration
Proposed Project Wetland Components
m n1
rnoenwra
El Creation
® Restoration
� Enhancement (Jurisdictional Wetlands)
wa
n
1
1
1 F
1
1
o� A
*Date of aerial photography, 2010 Figure ES.1 Proposed Project
roject Reach Alignment Components
Boundary
Upper Silver Creek
Mitigation Plan
"1 Burke Count, NC
� r
0 100 200 AM /r
F—
Existing P
� j Easement
Streams
Project Per
Parcels

Table ES.2.Rev: The revised mitigation plan addendum wetland asset table:
Table ES.2.Rev Upper Silver Creek Mitigation Plan Addendum: Wetland Assets
UpperSilver Creek Mitigation Plan-DMS Project 494645
— -Comments
All I
ENHANCEMENT WETLANDS
Non -Riparian
Jurisdictional Wetland 1A (JDW1A) — Non -Riparian
Existing jurisdictional wetland; 2:1 enhancement proposed to include minor
Enhancement
0.42
0.42
2:1
0.21
grading in areas of fill and altered drainage patterns, replanting of mowed
(2.1)
vegetation to include woody bottomland wetlandspecies.
SUBTOTAL
0.42
0.42
2:1
0.21
Riparian
Jurisdictional Wetland 1B (JDW1B) — Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 to include
significant enhancements to hydrology and vegetation. UT3 will be raised to
ring hydrology within 1' of the surface and will be routed along the
Enhancement
1.01
1.01
2:1
0.51
periphery of this wetland. In addition, hydrology from the mainstem will be
(2.1)
augmented (base flow elevation raised by 0.5') and will be routed closer to
e wetland area. Mowed vegetation will be planted with woody bottomland
etland species.
Jurisdictional Wetland 2 (JDW2) —Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 (typical
enhancement ratio) to include plug of existing drainage ditch which has
Enhancement
0.51
0.51
2:1
0.25
altered wetland hydrology, planting of woody bottomland wetland species to
(2.1)
replace mowed grasses, minor grading of lower part of wetland and increase
f baseflow elevation of mainstem by approximately 1.5 feet.
Jurisdictional Wetland 3 (JDW3) — Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 to include
"nor grading to remove less than 12" of overburden, reduction of hydraulic
gradient by plugging existing drainage ditch and raising baseflow elevation
Enhancement
0.03
0.03
2:1
0.02
f mainstem (these will serve to decrease the gradient of groundwater flow
(2.1)
within the project area, resulting in an increased hydroperiod for adjacent
wetlands). The area will be planted with woody wetland species to replace
owed grasses.
Jurisdictional Wetland 4 (JDW4) — Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 to include
eduction of hydraulic gradient to adjacent areas by plugging existing
Enhancement
0.24
0.24
2:1
0.12
drainage ditch and raising baseflow elevation of mainstem. The mainstem
(2:1)
ill also be relocated which should increase the influence of its hydrology o
adjacent areas and decrease the gradient of groundwater flow. The area will
e planted with woody wetland species to replace mowed grasses.
Jurisdictional Wetland 5 (JDWS) — Riparian

Existing jurisdictional wetland; enhancement proposed at 2:1 to include
removal of overburden (fill) from areas where vegetation reflects the altered
soil conditions, plugging/removal of ditching in the immediate vicinity and
Enhancement
0.81
0.81
2:1
0.40
so upstream along the long linear ditch that parallels the stream,
(2:1)
enhancement of wetland hydrology as a result of Priority I stream restoration
d an increased base flow elevation, and increased storage/runoff retention
y disconnecting direct ditch connections to the main channel and increasing
ponding and recharge.
Jurisdictional Wetland 6 (JDW6) — Riparian
Existing jurisdictional wetland; enhancement proposed at 2:1 to include
diversion of additional overland flow into the area, raising of mainstem of
Enhancement
0.25
0.25
2:1
0.13
Silver Creek to create high level of groundwater and floodplain connectivity
(2.1)
with wetland, replanting to establish woody wetland species to replace
owed grasses.
SUBTOTAL
2.85
1 2.85
1.43
RESTORATION WETLANDS
Non -Riparian
Restoration Wetland 1A (R1A) — Non -Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
Restoration
0
0.06
1:1
0.06
nor grading to create connectivity to hydric soils, route overland flow into
areas to increase ponding and infiltration, and planting with target of
hardwood bottomland forest ecosystem to replace mowed grasses.
Restoration Wetland 1B (R1B) — Non-Riarian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
Restoration
0
0.15
1:1
0.15
nor grading to create connectivity to hydric soils, route overland flow into
areas to increase ponding and infiltration, and planting with target of
hardwood bottomland forest ecosystem to replace mowed grasses.
SUBTOTAL
0
0.21
1:1
0.21
Riparian
estoration Wetland 2 (R2) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
removal of less than 12" of overburden from past fill activities thought to be
Restoration
0
1.22
1:1
1.22
associated with road construction, remeandering of UT3 through the middle
f the proposed restoration wetland to restore hydrology, and replanting with
edand herbaceous and hardwood bottomland forest ecosystem to replace
owed grasses, predominantly fescue.
Restoration Wetland 3 (113) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
removal of less than 12" of overburden from past fill activities thought to be
associated pasture enhancement, plugging of drainage ditch that extends into
Restoration
0
0.18
1:1
0.18
the area to restore hydrology (reduce hydraulic gradient), and potential to
divert some larger stream flows from UT3 into this vicinity through overland
hannels that would mimic a complex floodplain with abandoned channels
d abundant roughness elements affecting floodplain flow paths.
Restoration Wetland 4 (R4) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
removal of less than 12" of overburden from past fill activities thought to be
Restoration
0
0.44
1:1
0.44
associated with channel dredging, channel restoration to include removal of
levy along mainstem creek bank to enhance floodplain access and also to
wise base flow elevation relative to floodplain elevation, and replanting with

herbaceous and hardwood bottomland forest ecosystem to replace
�Ietland
nowed grasses (predominantly fescue).
Restoration Wetland 5 (R5) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities to include
removal of less than 12" of overburden from past fill activities thought to be
associated with pasture enhancement, removal of adjacent ditch should
Restoration
0
1.29
1:1
1.29
educe groundwater drawdown rate by raising the potentiometric surface in
this area, and replanting with wetland herbaceous and hardwood bottomland
orest ecosystem to replace mowed grasses.
Restoration Wetland 6 (116) — Riparian
Restoration wetland; credit proposed at 1:1. Proposed activities will include
removal of less than 12" of existing overburden thought to be placed for
pasture enhancement, removal of ditch features at the top of the wetland and
adjacent to the mainstem that are reducing ponding volumes and recharge,
wising the baseflow level and modifying the typical design cross-section of
Restoration
0
1.54
1:1
1.54
e mainstem in this area to increase floodplain activation frequency, and
constructing minor diversions of overland flow and flow from high flow
vents on UT 1 into the area to further enhance hydrology. The area will be
replanted with a target hardwood bottomland forest plant community to
replace existing mowed grasses and herbaceous wetland species.
SUBTOTAL
0
4.67
4.67
CREATION WETLANDS
Creation Wetland 1 (Cl) — Riparian
Creation wetland; credit proposed at 3:1. Proposed activities to include
grading of existing drainage ditch to a more natural and broad swale with a
ow gradient and intermittent ponding areas. This is already a high recharge
area, but reconnection of the main stem with the floodplain will create a
Creation
significant increase in flooding to this area as well. Higher global water
(3:1)
0
0.99
3:1
0.33
tables will reduce groundwater flow out of the area. The increase in
hydrology and the grading efforts should create conditions necessary for
etland creation. The area will be replanted with a target hardwood
ottomland forest plant community to replace existing mowed grasses and
erbaceous wetland species.
SUBTOTAL
0
0.99
0.33
etland Summary
IF
—
Comments
Restoration:
0.21
1:1
0.21
Non -Riparian
Restoration:
4.67
1:1
4.67
Riparian
Enhancement:
0.42
2:1
0.21
Non -Riparian
Enhancement:
2.85
2:1
1.43
Riparian

Creation:
0.99
3:1
0.33
Riparian
TOTAL WMUs
6.85
Figure 2: The revised mitigation plan addendum wetland asset map
Figure 2