HomeMy WebLinkAbout20090048 Ver 2_MP(CommentResponseIRT)_20160115
Wildlands Engineering, Inc.
LITTLE PINE CREEK II Stream and Wetland Restoration Project
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January 15, 2016
Harry Tsomides
North Carolina Division of Mitigation Services
5 Ravenscroft Drive, Suite 102
Asheville, NC 28801
RE: Final Mitigation Plan Addendum and Plan – IRT Comments
Little Pine II Project, Alleghany County
New River Basin – HUC 05050001
EEP Project ID No. 856
DENR Contract #D13022S
SCO ID 07‐07088‐01
Dear Mr. Tsomides
We are in receipt of Andrea Hughes’s December 11, 2015, comment letter on the Mitigation Plan
Addendum and Plan Set for the Little Pine Creek II Stream and Wetland Restoration Project, submitted
by Wildlands to DMS digitally on October 22, 3015. The comments provided and Wildlands’ responses
are detailed below in blue italics.
Commenter ‐ Todd Bowers, USEPA, 24 November 2015:
1. General comment: Well written plan with clear and concise approach to restoration of site
aquatic resources.
Thank you.
2. Page 15 – Section 8.2 and 8.3 (Sheet 3.2): planting plan is heavily weighted towards Acer rubrum
(red maple) in wetland 1 planting zone and riparian and hill slope buffer zones. Recommend
omitting or limiting inclusion of red maple to 5% of overall species. Recommend replacing with
Quercus lyrata or michauxii in Wetland 1 Planting zone and with Oxydendrum arboreum in
riparian and hill slope zones.
Acer rubrum is now at 5%. The plant selection has been modified – please refer to the planting
plan sheets for new species and distributions. Quercus michauxii is now included at 5% for
Wetland 1 and Oxydendrum arboreum is now listed at 5% for riparian and hill slope zones.
3. Page 19 – Section 8.6.2: Limit or omit Acer rubrum from planted species (see comment above)
Acer rubrum is now at 5%.
4. Page 19 – Section 8.6.2: Include statement on how volunteer tree species will be dealt with.
A statement has been added to Table 9 under ‘Vegetation’.
5. Page 20 – Section 9.0/Table 9: Include contingency plan for beaver activity and damage.
Beaver management has been added to Table 9 under the stream component/feature
maintenance approach.
Wildlands Engineering, Inc.
LITTLE PINE CREEK II Stream and Wetland Restoration Project
Page 2 of 6
6. Page 22 – Section 10.2: What are the “geomorphically significant events” and how will they be
monitored and documented?
A geomorphically significant event is defined by DMS in their February 2014 Stream and Wetland
Monitoring Guidelines as a flow event that is at least 66% of the 2‐year recurrence interval flow.
This geomorphically significant event is no longer referenced in the document since the project
was instituted prior to the 7 year monitoring requirement, and the Qgs is not required.
7. Page 22 – Section 10.3: It is unclear what “trending towards success” really means here. For
instance if the tree density is 270 stems per acre at year 5 with annual mortality of 10%, would
this be considered “trending toward success”? (It is still not less than 260 stems/acre). I would
not recommend terminating monitoring of vegetation based on this.
If at year 5 the stem count is at least 270 stems per acre and stem density is vigorous (i.e.,
appears to be trending towards success), and invasive species are not threatening ecological
success, monitoring of vegetation on the site may be terminated with written approval by the
USACE in consultation with the NC Interagency Review Team.
8. Page 22 – Section 10.3: Please calculate and provide the number and size of vegetation plots
(plots/acre) anticipated to be used for monitoring.
The following note was added to Table 10: The size of individual quadrants will be 100 square
meters for woody tree species and shrubs. Vegetation assessments will be conducted following
the Carolina Vegetation Survey (CVS) Level 2 Protocol for Recording Vegetation (2006). The
number of vegetation plots is also included in Table 10.
9. General comment: Since this is a restoration project for providing compensatory mitigation for
impacts to aquatic resources that is part of a local watershed plan (Little River and Brush Creek
LWP), I recommend that the sponsor develop and include a very basic sampling plan to
demonstrate that water quality benefits are being achieved at some level. Baseline upstream
and downstream water sampling followed by an interim sampling period at Year 4 and again at
closeout would be a good start. I am not suggesting that we tie water chemistry into the
performance standards for credit release but we should be able to provide evidence that the
project restored or improved the physical, biological AND chemical integrity of the aquatic
resources on site and that it was consistent with the goals of the Clean Water Act and the Local
Watershed Plan.
While DMS staff and state agency partners collect water quality data at selected mitigation
project sites, as staff and other resources become available, water chemistry data has not been
collected or planned for Little Pine II. Providing comparison to pre‐construction data may be
difficult as there is currently no pre‐construction data set against which to compare any post‐
construction data and therefore to evaluate improvement, and it is not be feasible to collect
meaningful water quality data prior to construction. However, the comment is appreciated and
DMS will consider including the site in their water quality monitoring program.
Wildlands Engineering, Inc.
LITTLE PINE CREEK II Stream and Wetland Restoration Project
Page 3 of 6
Commenter ‐ Mac Haupt, Ginny Baker, Sue Homewood, NCDWR, 25 November 2015:
1. DWR is recommending that the designer take note of what is going on just above Reach 1. It
appears that the landowner had built a temporary dam and it had recently failed causing the
stream to move significantly to stream bank right and flow is currently vectoring into a meander
bend which would (eventually) likely have the stream enter the project at a different location
than is currently shown on the plans.
Wildlands notes the potential for upstream channel migration. This area will be reevaluated
closer to the start of construction to determine whether additional bank protection measures are
needed, or, if significant migration has occurred, the design of the tie in point will be adjusted as
needed.
2. DWR has concerns about the statement from the second paragraph of Section 8.1 “Due to
conservation easement constraints, Little Pine Reach 1 is designed to be straighter than the
typical C type stream and kept approximately in the same alignment adjacent to the left valley
wall”. Wildlands has indicated that, “they added some outer bank protection because of the lack
of pattern to dissipate energy”. DWR would like to know if they utilized a little more riparian
buffer area (even if they have <30 feet), would that reduce the risk in their design? DWR would
be willing to allow less than 30 ft buffers in this area if it improves the stability of the design.
Wildlands reviewed the above‐mentioned discussion in the mitigation plan and we understand
why DWR has concerns. In response, we completed a thorough review of the design and the
mitigation plan text. We feel that the design is sound but the discussion of the constraints and
the design was incomplete and inaccurate. We revised Section 8.1 to provide an accurate,
thorough discussion of the constraints on Little Pine Reach 1 and the selected design.
While Reach 1 is somewhat confined by the location of the conservation easement boundary on
the right floodplain and the presence of Wetland 1 on the left floodplain, the design still falls well
within acceptable reference ratios for the channel type. Therefore, we do not feel a change in the
design, including increasing the stream belt width and reducing the buffer width, is necessary. If
there are additional concerns, Wildlands is happy to discuss further.
3. DWR has noted the proposed cross‐section in Figure 4 Monitoring Components in the Mitigation
Plan Addendum. DWR believes a few more cross‐sections are warranted for this project given
the extensive history, design review and ultimate stream re‐design. Typically, DWR likes to see
the cross‐sections located at representative portions of the site or areas that will have
significant channel modification (e.g. a large section of channel meander is being moved). DWR
has the following recommendations for locations of cross‐sections:
a. Reach 1‐ 100+50, 102+00, 104+00
b. Reach 2‐ 107+50, 108+00, 109+50, 116+25, 120+00, 124+00
This is above the requirements for 2 cross sections per 1000 LF. Wildlands proposed 5 cross
sections for the 2,451 LF length of Little Pine Creek. It is our opinion that cross sections in
areas directly downstream of a bridge in a compound bend, for example, are not the best
choice for long term monitoring. However, two additional cross sections will be added to
help address this request and provide the information to determine success in terms of
stability for the project beyond that minimally required. See revised Figure 4 for updated
cross section locations.
Wildlands Engineering, Inc.
LITTLE PINE CREEK II Stream and Wetland Restoration Project
Page 4 of 6
4. During DWR’s site visit on November 10th, 2015, staff noticed a couple of gauges on site (one in
the preservation area and one in the enhancement area?). However, these gauges were not
listed in Figure 4 (Monitoring Components). DWR would like to confirm the presence and
location of the gauges on site and, moreover would recommend placing several gauges on site
with regard to the wetland enhancement. DWR believes placing a gauge in Wetland 1 and 2A
would be beneficial to document the changes in the water tables relative to the stream
restoration, particularly in wetland 2A. One or two gauges in the preservation wetland would be
beneficial as well (if they are not already there).
There were 6 gauges installed during the development of the 2008 Plan. Please reference the
2008 Plan – the gauge locations are depicted on Figure 18, and the data record is provided in
Appendix 9. Wildlands does not have access to the data from these gauges and these gauges
are no longer logging.
At least two gages will be placed on the site: one in Wetland 1 and one in Wetland 2A (both
enhancement wetlands). DMS will confer internally and determine the feasibility/need for a
gauge in preservation Wetland 2B. Please see revised Figure 4 for the two planned monitoring
gauge locations.
1. During the site visit, it was noted that there was a significant length of stream that is running
through the wetland portion of the site. DWR was wondering why this stream preservation was
not included in the Mitigation Plan (Tributaries D, E, and F, >750’). If stream preservation credits
are to be included revisions that incorporate those additional stream assets should be made to
all corresponding sections, tables, and figures in the Final Mitigation Plan.
During prior asset determinations, there was uncertainty over the acceptability of including
stream assets amidst wetland preservation. These streams are now included in the project as
preservation assets. Please see Table 5 and Plan Sheet 0.3.
Commenter ‐ Andrea Hughes, USACE, 4 December 2015:
1. All temporary and permanent impacts to existing wetlands and streams must be accounted for
in the PCN and the loss or conversion of those waters must be replaced on‐site. Please include a
map depicting the location of all impacts with the PCN.
This map will be provided with the PCN.
2. Section 8.1, Stream Design. The addendum indicates (due to conservation easement constraints)
that the proposed design for Little Pine Reach 1 could result in lateral cutting and bank erosion.
Please provide additional information regarding the proposed design. Are the constraints a
result of attempting to maintain the minimum buffer widths? Are there alternatives (other than
armoring the stream bank) that would reduce the risk of lateral cutting and bank erosion?
Please refer to the answer provided for Mac Haupt, Ginny Baker, and Sue Homewood’s question
2. Section 8.1 has been revised to provide more information about the design and constraints on
this reach. No design change has been made.
3. Section 8.3, Wetland and Buffer Planting. The addendum states that the target community is
based on conversion to a Piedmont Bottomland Forest. Proposed species for the riparian buffer
include Red Maple, Yellow Buckeye, River Birch, White Ash, Tulip Poplar, Sycamore, and
Sassafras. The approved mitigation plan indicates riparian planting based on conversion to a
Montane Alluvial Forest (low mountain alluvial forest) including Spicebush, Pawpaw, Ironwood,
Wildlands Engineering, Inc.
LITTLE PINE CREEK II Stream and Wetland Restoration Project
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Witch‐hazel, Eastern Redbud, Hazelnut, Tag Alder, Hazelnut, Persimmon, Hackberry, Hickory,
Tulip Poplar, and Sycamore. Please provide rationale for the change in species composition.
The planting plan now reflects a selection of species typical of a Montane Alluvial Forest. Please
refer to the updated plan sheets and Section 8.3. The plant list includes diverse species that have
shown past success on similar mitigation projects.
4. Planting Plan (Sheet 3.2). The addendum indicates Calycanthus floridus will be planted in
Wetland 2A. According to the National Plant List, this species is listed as FACU. Please provide
rationale for inclusion of this species in the planting plan for Wetland 2A.
Calycanthus floridus is no longer included in the planting list for Wetland 2A. Please refer to the
planting plan sheets for new species and distributions.
5. Planting Plan (Sheet 3.2). The addendum indicates that Acer rubrum will constitute 20% of stems
proposed for the hillslope areas, 10% of the stems proposed for the riparian buffer, and 20% of
the stems proposed for Wetland 1. We recommend limiting Acer rubrum to 5% of planted
species for all areas.
Acer rubrum is now at 5% on all plant lists for the project.
6. Please note that requirements for early termination of monitoring also include vigor, and Years
1‐5 monitoring should demonstrate no invasive species issues.
The statement about early termination of monitoring has been removed, as the project is
proposed for 5 years of monitoring. Please refer to discussion in the answer to question 7,
below.
7. Table 10.0, Monitoring Requirements. The frequency of monitoring for Dimension, Substrate,
and Vegetation monitoring should be changed to years 1,2,3,5, and 7. Representative photos
should be provided on an annual basis.
This is an older project where DMS had to reassign a new designer and it was instituted
originally started well prior to the 7 year stream guidance. DMS typically uses the project
beginning date to determine the monitoring duration and monitoring requirements and that is
the rationale for 5 years monitoring, with longitudinal profiling included.
8. Section 11.0, Monitoring Plan. Complete monitoring reports should be provided for post‐
construction, years 1,2,3,5, and 7. In years 4 and 6, a summary of the site conditions may be
provided along with photos, current condition plan view map, and applicable hydrology data.
Please see response to previous comment.
9. All intermittent stream channels proposed for restoration must document a minimum 30 days
of continuous flow on an annual basis.
The only stream channels labelled as intermittent proposed for credits are Tributary E and
Tributary F. These streams are proposed for preservation only.
10. The approved mitigation plan includes preservation credits associated with tributaries D, E, and
F in Wetland 2B. The addendum does not list these tributaries in Table 5, Determination of
Credits. Please indicate if the project will include mitigation credits associated with tributaries D,
E, and F.
Table 5 has been modified to include these tributaries. These tributaries are now also shown on
the plan set on Sheet 0.3.
Wildlands Engineering, Inc.
LITTLE PINE CREEK II Stream and Wetland Restoration Project
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11. Please provide a copy of the JD approval letter.
This is now provided in Appendix 2.
12. Please provide a revised monitoring locations map (with the additional cross‐sections noted
above).
Please see revised Figure 4.
13. Please provide a copy of the conservation easement with all exhibits.
These are now provided in Appendix 3.
Sincerely,
Christine D. Blackwelder, Senior Environmental Scientist