20171041 Ver 1_RES Comment Responses_2018_20200303

MEMORANDUM

302 Jefferson Street, Suite 110 Raleigh, North Carolina 27605 919.209.1052 tel. [phone] fax
TO: North Carolina Division of Mitigation Services
FROM: Cara Conder - RES
DATE: June 18, 2018
RE: Response to Little Sebastian Mitigation Site Draft Mitigation Plan Comments
DMS Project ID No. 100027, Contract #7187

Paul Wiesner, NCDMS Comments:

General Comment: Please include the September 29, 2017 Post Contract IRT Meeting Minutes
in the appendices of the revised mitigation plan and confirm that the mitigation plan is consistent
with the meeting notes and IRT response e-mails (attached for reference).
Added September 29,2017 IRT meeting minutes to Appendix B and language to the mitigation plan
in Section 1.2 that the plan is consistent with the meeting notes and IRT response emails.

Executive Summary: Please reference the thermal regime. Please provide a brief introduction of
the Gideon site to describe the benefits such as easement continuity and riparian corridor.
Thermal regime cool added, along with a brief introduction of the Gideon site.

Section 1.2 - Project Outcomes: Edit the sentence “Due to its water classifications”. The
proposed improvements may result in outcomes consistent with these water quality classifications
but the outcomes are not “due to” them.
Removed the first part of the sentence and changed to “Proposed improvements to the Project will
help meet the river basin needs…”

Section 1.2 - Project Outcomes: Stating the proposed improvements will meet the water quality
needs of the basin should be reworded unless the parameters are to be quantified.
Revised the wording

Section 2.1 - Site Selection: This section indicates that improvement and restoration of water
quality will be achieved. Edit this assertion or modify the monitoring plan to include water quality.
Edited the language about achieving goal 1; however, goal 1 is being addressed, just not
quantified.

Section 3.1 - Watershed Summary Information-(Page 4): Land use comprises most of the text
under the drainage area subheading. Suggesting adding land use to the subheading.
This has been added to the subheading.

Section 3.2 - Landscape Characteristics: Please add a section for the site geology and provide
discussion.
This section has been added.

Section 3.2 - Landscape Characteristics-Existing Wetlands: DMS recommends contacting the
USACE and including the final PJD in the revised mitigation plan prior to the IRT mitigation plan
review.
The PJD is included in Appendix I.

Section 3.2 - Landscape Characteristics – Soil Survey: Please label the soil survey section
according to the entire discussion in the paragraph.
Moved ecoregion narrative to the beginning of the landscape characteristics, and the soil survey
section only discusses soil characteristics.

Section 3.3 - Land Use - Historic, Current, and Future: Land use discussion within the Gideon
site should be included in this section.
Added Gideon references along with the total protected area with both easements for the future
land use.

Section 5 - Mitigation Project Goals and Objectives: Project Goals - How is the improvement
of water quality/reducing sediment and nutrient loads, and increasing DO going to be measured
for success? Suggest clarifying this goal and tying it directly to an objective AND performance
criteria. Same comment for reduction in temperature.
This has been revised to reflect that our goals will indirectly support the goals of the RBRP to
improve water quality and reduce sediment and nutrient loads. This will not be a measurable
objective. Two additional goals have been added that are already tied to objectives: Improve
instream habitat, and restore and enhance native floodplain vegetation.

Section 5 - Mitigation Project Goals and Objectives: Project Objectives - What are the
appropriate pattern, dimension and profile? Is the intent to construct stream for a particular
discharge, or dominant discharge or bankfull discharge? Please clarify.
The objective has been reworded to: Design and reconstruct stream channels sized to convey
bankfull flows that will maintain a stable dimension, profile, and planform based on modeling,
watershed conditions, and reference reach conditions.

Section - 6.2 Design Parameters:
• Reach JN2-B: The text notes minimal grading and buffer reestablishment. Will any
structures be utilized/ installed in this Enhancement I reach? Yes, one log cross vane and
two log sills will be utilized. This has been added to the mitigation plan.
• Reach JN2-D: The channel appears to have been heavily modified/ditched. Is limited
grading the best approach for this reach? The minimal grading was a typo/carry over from
Reach JN2-C. Language in the mitigation plan has been updated to reflect that there is
some channel relocation, bed and bank stabilization, and removing an existing ford
crossing and access road. Also, a structure has been added on this reach on the design
plan set.
• Reach MC1-C: Please discuss the transition into the Gideon site. Does the proposed
treatment compliment both sites? The restoration continues into the Gideon site for another

1,030 LF and will be a seamless transition. The Gideon site is being permitted concurrently
and will be constructed at the same time as Little Sebastian.
• USGS Regional Regression Equations: Please verify this equation is applicable/valid for
each of the drainage areas calculated. The equation is correct, but is not applicable to small
drainage areas. The table has been updated accordingly. The USGS Regional Regression
Equations are used in the process for verification that bankfull flows are appropriate.
• Section 5 indicates that two agricultural BMPs will be installed on the site (project
objectives). Please describe these and their proposed location in the Section 6.2 text. There
is only one BMP and the reference to two BMPs was a typo that carried over from the
proposal. The objectives have been reflected to show a single BMP. One BMP was
originally on Reach JN2-A, but per the IRT site visit notes, if the reach is intermittent the
BMP will not be constructed, rather the easement will be extended to provide preservation
to the origin point in the forested watershed. The JD determined the limits of the stream
preservation. The BMP will be installed at the top of Reach BS1-A, which already has the
conservation easement extended beyond the stream origin point. This BMP will be a dry
detention basin and has been added to the language in the mitigation plan for Reach BS1-
A.

Section 7.1 - Success Criteria: Specify which reaches will have transducers/ flow gauges
installed.
Added what reaches will have transducers/flow gauges: JN2-A and BS1-A.

Section 8.6 – Scheduling/ Reporting: “A mitigation plan and as-built drawings document…..”;
this should be, “A Baseline Monitoring report and as-built drawings document…..”. Please update
accordingly.
This has been fixed.

Table 16: The tree height success criteria in the table does not match what is reported in the text
(Section 7.2). Please update the table and QA/QC the table and report text to confirm they are
consistent.
The table has been updated to match the text – it had the Piedmont height criteria originally.

Figure 1 - Vicinity Map: This map appears to be a vicinity map for the Gideon site rather than
the Little Sebastian site. Please change the emphasis to highlight the active site.
This map has been revised to highlight the Little Sebastian site.

Figure 10A: Please update the title to “Little Sebastian Mitigation Site”.
This map has been revised.

Figures 10A-10C: Section 5 indicates that two agricultural BMPs will be installed on the site
(project objectives). Please show the proposed BMPs on the conceptual maps.
This was a typo in Section 5. Two BMPs were presented in the proposal, however since the entire
stream origin is being protected and the reach is intermittent, there will not be a BMP on Reach
JN2-A. One BMP is being installed on reach BS1-A even though this is a restoration reach and
the stream origin is being protected. Additionally, this has been added to the conceptual map and
design plans.

Appendices: Please check appendices for map order and labeling consistency.
The appendices and map order have been reviewed and revised as needed for map order and
labeling consistency

Preliminary Plan Set:
• Title Sheet – Please label the individual stream reaches. Done
• Sheet E1 Construction Note 7 – Add that any compromised trees should be removed to the
note. Done
• Sheet E2 – Edit the linetype to emphasize the project conservation easement. Done
• Sheet S1 – Add profile to include the proposed crossing. Done and now Sheet S2 and all
subsequent sheets will be number off because there is an additional sheet now.
• Sheet S12 – Add profile if needed for the crossing. A profile is not needed for this ford
crossing, as there is no change in bed elevation.
• BMP Sheets - Add sheets detailing the proposed BMPs noted in Section 5 of the report text
and show their locations on the applicable plan sheets. The one BMP on BS1-A has been
added to Sheet S7 and Sheet D2 has the structure details.
• Sheet P1: This appears to be the planting plan for the Gideon Mitigation Bank. Please
provide the planting plan for the Little Sebastian Mitigation Site. Please QA/QC the
document to confirm that other elements of the Gideon Mitigation Bank site MP have not
been included in the Little Sebastian Site MP. This was a mistake and we apologize. The
document has been QA/QCed for other Gideon elements.
• Sheet P1 Planting Note 1 – Add language to the effect “and final approval has been issued”
to the end of the first sentence. Done
• Sheet M1 – The monitoring plan sheet is not consistent with what is proposed in Section
8-Monitoring Plan (specifically the number of vegetation plots). Please QA/ QC the report
text and plan sheets to confirm that they are consistent. Consider moving the flow gauge
on Reach JN2 to the Enhancement I section rather than the preservation section. The
number of vegetation plots in Sheet M1 has been updated to match the mitigation plan,
which is 8 plots. The plan set and mitigation plan are consistent. The flow gauge on Reach
JN2 should stay in the preservation section to document intermittent flow per the post-
contract IRT site visit.
• Sheet D3 Log Vane Plan View - Consider extending the stone backfill along the entire
length of the log into the streambank. Done
• Sheet D4 Double Log Drop Plan View - The contact “hinge” point between the two rows
of logs is prone to piping. Consider adding a note to not require contact at the hinge point
as directed by the engineer. We extended the filter fabric and stone backfill along both logs
(including the hinge point) in order to reduce the risk of piping.
• Structure Details – Please provide boulder size specifications everywhere applicable within
the plan sheets. Done, these are on Sheets S4, S5, and S11, and D5. Rocks must have an
intermediate diameter of at least 24" for headers and 24-30" for footers. Sill rocks shall
have an intermediate diameter of at least 18". All rocks shall be approved by engineer
prior to installation. Width of header and footer rocks must be at least 36". Depth of header
and footer rocks must be at least 24".