20160978 Ver 1_MEMO_Draft MP Comments_07.24.2017_20170731

M E M O R A N D U M
fires
302 Jefferson Street, Suite 110 Raleigh, North Carolina 27605 919.209.1052 tel. [phone] fax
TO: North Carolina Interagency Review Team
FROM: Brad Breslow, Daniel Ingram- RES
DATE: July 24, 2017
RE: Response to Polecat Mitigation Site (Neu -Con UMBI) Draft Mitigation Plan
Comments
Listed below are comments provided by the NCIRT regarding the Polecat Draft Mitigation Plan and RES'
responses:
General comments:
A new table was added to the beginning of the document and mislabeled tables were updated. Please
note many tables now have new numbers, most notably Mitigation Credits (previously Table 8) is now
Table 10.
Kim Browning, USACE Comments:
1) Adjusted SMUs are referred to in several tables, but it's never mentioned how the credits are adjusted
from 6255 SMUs to 6567.
Credits were adjusted based on correspondence with Todd Tugwell, USACE, and in accordance with
Section XI(C)- Procedures to Calculate Credits for Non-standard Buffer Widths, published in the October
2016 Wilmington District Stream and Wetland Compensatory Mitigation Update. A detailed description of
the methodology and calculations is included in Section 6 and Figure(s) 11.
The following text was added to the mitigation plan, in Section 6:
Buffer measurements for additional credit were made horizontally, beginning from the edge of the wetted
perimeter and extending to the nearest edge of the wooded buffer in any direction. Due to the minimum
required widths, additional credit was not generated until a stream is at least 75 feet inside the edge of the
buffer. Areas within the project that are being used to generate additional credit are solely being usedfor
the generation of stream mitigation credits, and will not be used for the generation of any other credit type
(i.e., the same square foot of buffer cannot be used to generate wetland credit, nutrient offset credits or
state buffer credits). Area within a buffer may only be used to provide credit for one stream (i.e., where
buffers exist between two project streams, these areas may only be counted toward credit for only one of
the streams, and areas within the minimum required buffer of any creditable stream may not be used for
additional credit for any other stream).
In order to calculate credit adjustments, each side of the stream was evaluated separately. The lengths of
individual reaches were multiplied by the mitigation ratio to yield stream credits, and the results were then

adjusted by the increase or decrease percentage indicated in Table 11. Finally, the resulting credit amounts
were totaled for each side of the stream and then divided by two to yield the final number of credits.
2) Endangered Species Act follow-up is mentioned for the historically mapped Red -Cockaded woodpecker
in 1999. A request was sent to USFWS for review in March 2017; however, we received follow-up from
USFWS Nov. 9, 2016 indicating that there is expected to be minimal adverse impacts to fish and wildlife
resources.
Mitigation plan has been updated to state the USFWS coordination was completed in November 2016 as
part of the Instrument Modification Public Notice period.
3) Table 1, page 8 references 6567 adjusted SMUs, with contradictory information in Table 8, page 25
referencing 6554 adjusted SMUs.
Tables have been updated to be consistent. Proposed SMU total is 6,567
4) Financial Assurances: Page 50 references a Construction Performance Bond of $238,000. The same
paragraph references a sum of $237,000.
Paragraph has been updated to read $238, 000 throughout.
5) Vegetative monitoring should occur for both random and fixed plots.
Monitoring will occur in both random and fixed plots. For random plots, species and height will be
recorded for all woody stems. The location (GPS coordinates and orientation) of the random plots will be
identified in the annual monitoring reports.
6) A watershed map is not included. There is a vicinity map included.
The service area watershed has been added to Figure 1. The project watershed is shown on Figures 2 and
6.
7) Existing wetlands are described on page 21, totaling 13.41 acres. Are these areas being proposed for
NCDWR crediting? It appears that this is the case on the maps, but it's not described in the text.
Areas with existing wetlands are being used to generate either NCDWR crediting or additional stream
credits. No wetland credits are being generated.
Mae Haupt, NCDENR Comments:
1) Quality Control: The wetland areas referenced in Table 7 should be labeled on Figure 7.
The wetlands have been labeled on Figure 7.
2) Page 33: the reach PC1 is proposing buffer enhancement, however, the reach appears to be wooded.
What buffer enhancements are proposed that would support the credit?
Buffer enhancement is proposed because the area contains significant concentrations of Chinese privet.
The EIII approach allows high quality aquatic habitat to be protected and enhanced through invasive
species treatments and supplemental plantings in the riparian buffer.
3) Quality Control: on page 33 Reach PC2 and PO paragraphs refer to different reaches in the first
sentence.
Paragraphs have been updated.
4) Quality Control: Velocity Approach paragraph refers to Table 17, should be Table 15.
Updated

5) Section 10 Performance Standards: this section needs to be revised to conform with the October 2016
Mitigation Guidance.
Updated.
6) Section 11 Monitoring Requirements: this section needs to be revised to conform with the October 2016
Mitigation Guidance.
Updated.
7) Section 11.4- they need to state of the 26 veg plots, how many are fixed and how many are random.
Planting area was updated to 17.72 acres (see Section 11.4 and updated figuresl2/13). There will be 14
total vegetation plots: 11 fixed and three random.
8) DWR recommends stream gauges in those upper reaches where the dominant flow is intermittent, for
example reach KZl.
A crest gauge is shown in the monitoring plan just downstream on KZ2 where restoration work is proposed.
Reach KZI has a drainage area of over 500 acres and was determined to be a perennial feature by DWR.
Furthermore, because no channel work is proposed on this reach, RES did not plan to place a crest gauge.
However, if deemed appropriate by the IRT we will place a gauge at the upstream end of KZl.
9) Site plan sheet S6: for reach KZ5 it appears that the tributary is entering the stream at a meander bend.
DWR recommends that the confluence be designed into a riffle. In addition, it looks like there is some
slope as the reach comes into KZ4, DWR recommends some type of structural step down if appropriate.
RES typically designs confluences to occur along the outside of a meander bend of the receiving stream.
This location is selected to dissipate energy as the flows converge, and so that the two flows will converge
at an angle pointed in the downstream/down valley direction. Structure number/placement revised at the
downstream end of KZ5 to account for the drop into KZ4
10) Site plan sheet S 14 and S15: the reach shows M1 coming into the wetland area, and labeled as P1,
however, it does not look like any work is being done on the channel. Reach M1 is listed as restoration at
a 1:1 ratio. DWR questions the restoration label for this section of M1. Perhaps this portion of M1 should
be EIII or preservation?
Reach MI has been historically straightened and its current flow path as it approaches the wetland is
ditched straight to the west to tie in with PCIIPC2 (See Figure 7). The restoration approach at this
downstream end is to redirect the flow back into the relic channel and restore the historic hydrologic
connection.
11) Quality Control: site plan sheets S21-23 label PC3 as EII when other parts of the plan refer to this reach
as EIII.
Plan sheets updated to read EIII for Reach PC3.
Todd Bowers, US EPA Comments:
1) 4.1.1 (p. 16): Drainage Area text does not match drainages given in Table 4 (p. 17).
Text and tables updated to match correct drainage areas.
2) 4.1.2 (p. 16): Project drainage area does not match total drainage for PC3 in Table 4
Text and tables updated to match correct drainage areas.
3) 4.2; Table 4: See previous comments on drainage areas for MI1 and PC3.
Text and tables updated to match correct drainage areas.

4) 4.2.3.1 (Page 17): Reach KZO is listed as 341' existing and 34F is proposed including a break to the
existing length. How wide is this break and what is the actual existing length?
Existing and proposed length is 341 linear feet for Reach KZO. The reach includes an existing 18 " CPP
culvert that is outside of the proposed easement. The easement break for this culvert is 30'.
5) 4.2.3.2 (Page 18): Reach KZ1 also has a 74' break due the proposed Atlantic Coast Pipeline (ACP)
project. Shouldn't the existing length be 863' plus this 74' break (937) and then reduced to 863' proposed
for mitigation?
Text has been updated to reflect that existing stream length is 937 linear feet. The length proposed for
mitigation credit is 863 linear feet (937' minus the 74' break for the ACP pipeline).
6) 4.2.3.6 (Page 18): No mention of the ditch upstream of KZ5. This ditch is included in the conservation
easement yet there is no discussion of the hydrologic connection to KZ5 and why this stream is not being
restored or enhanced in any manner other than an allusion to planting as evidenced by Figure 11.
Based on coordination with the IRT, the ditch upstream of Reach KZ5 was not deemed a viable candidate
for compensatory stream mitigation. This ditch is included in the easement because it is being proposed
for nutrient offset credit through a separate banking instrument with NCD WR. Text has been updated in
this section to acknowledge the hydrologic connection of the ditch with Reach KZ5.
7) 4.2.3.7 (Page 18): Reach KZ6 should be 1287' per Table 8 (Page 25)
Existing stream length for KZ6 is 1260 linear feet. This discrepancy has been updated to be consistent
between Section 4, Table 1, and Table 10.
8) 4.2.3.8 (Page 19): Reach MI1 should be 1934' per Table 8.
Existing stream length for MII is 1924 linear feet. This discrepancy has been updated to be consistent
between Section 4, Table 1, and Table 10.
9) 4.2.3.9 (Page 19): Reach PC existing length is not given.
Existing stream length for Reach PC] is 605 linear feet. Updated in Section 4.
10) 4.2.3.10 (Page 19): Reach PC2 existing length should be 373' per Table 8. The given drainage area
(3046 acres) matches Table 4 but not Section 4.1.1.
Existing stream length for Reach PC2 is 373 linear feet. Update in Section 4. Drainage areas throughout
the document have been updated to be consistent.
11) 4.2.3.11 (Page 19): Reach PC3 drainage area matches Table 4 but not Section 4.1.1.
Updated.
12) 4.2.7 (Page 21): Existing wetlands (WA, WB and WC) are not labeled in Figure 7 of existing conditions.
The wetlands have been labeled on Figure 7.
13) 4.2.7.3 (Page 21): "PC IB" should read "PC1 and PC2"
Updated.
14) Table "7" (Page 22): Should be "Table 5"
Updated.
15) Table 8 (Page 25): Many mistakes in this Table. Many of the proposed lengths do not match the
proposed lengths given in Section 8.2. There is an asterisk for the Adjusted SMUs with no footnote
explaining how/why the SMUs are adjusted. The final calculated SMUs do not match Table 1 or Figure 10
and should be 6567 assuming the individual calculation are correct (which do not appear to be in many
cases).
Updated.

16) 8.2 (Page 31): Many of the design reaches have lengths that do not match Table 8. Please recheck
calculations from designs and carry those corrections forward into Table 8, Table 1 and the table in Figure
10 for consistency. Be sure to include the breaks, reason(s) for the break and the type of break (culvert,
powerline, easement, etc)
Section 8.2, Table, and Table 10 have been updated to be consistent. Breaks and reasoning are explained
in footnotes on Table I and in Section 8.2.
17) 8.2 (Page 33): Reach KZ5 is listed as KZ3 in paragraph. Please include justification for not including
the ditch upstream of the Priority 2 restoration. Why is this ditch not included in the restoration plan for
restoration when it appears to be included in the conservation easement?
Based on coordination with the IRT, the ditch upstream of Reach KZ5 was not deemed a viable candidate
for compensatory stream mitigation. This ditch is included in the easement because it is being proposed
for nutrient offset credit through a separate banking instrument with NCDWR.
18) 8.2.2.1 (Page 36): Table 13 should be corrected to Table 11 in second paragraph.
All tables have been updated. .
19) 8.3.1.2 (Page 41): Tables 13 and 14 have slightly different design shear stresses. Both groups still meet
the allowable shear stress for the substrate (sand, silt, clay) but I am concerned about the differences as an
inconsistent value.
The slight difference in shear stress results presented in Tables 16 & 17 is to be expected and should not
be of concern given that the two sets of analyses (Stable Channel Design and Shear Stress Analysis) are
using different calculations/input.
20) Stable Channel Design should be listed in "Table 13" rather than "Table 15"
Updated.
21) Velocity Approach should be listed in "Table 15" rather than "Table 17"
Updated.
22) 10.2 (Page 44): Vegetation monitoring should describe both random and fixed plots.
Updated.
23) 11.4 (Page 46): Vegetation monitoring should describe both random and fixed plots. Also be sure to
describe what the monitoring period is and how soon after planting the first monitoring event will occur.
Updated.
Following text was added to section 11.4- "Plots will be a mixture offixed and random plots, with 11 fixed
plots and three random plots. For random plots, species and height will be recorded for all woody stems.
The location (GPS coordinates and orientation) of the random plots will be identified in the annual
monitoring reports. Vegetation will be planted and plots established at least 180 days prior to the initiation
of the first year of monitoring. "
Travis Wilson, NC WRC Comments:
This applies to multiple RES sites, and we have seen it on others as well. But specifically right now it
applies to: Pole Cat, Meadow Spring, Dairy Land, and Hanna Bridge draft mitigation plans. RES is using
a detail for stream crossings with culverts that includes a constructed riffle or "riffle grade control" at the
outlet of the culvert and in some cases also the inlet. There are several issues with this I would like to point
out:

1) In the world of transportation projects this is an impact that is not allowed except for very specific and
unavoidable circumstances. NCDOT is not allowed to place rip -rap in the stream channel on perennial
streams. In some cases RES is proposing this detail inside crediting portions of the easement.
2) A "constructed riffle" at the outlet of a pipe will be designed to handle higher shear stress than the typical
stream cross section riffle (i.e. Bigger rock). That larger rock combined with altered channel width and
water depth in the culvert will likely result in limited to no aquatic passage.
3) Working with NCDOT over the years we have agreed on an armored plunge pool or armored scour hole
detail at the outlet of the pipe. This design allows for adequate water depth for aquatic passage, sets grade
control at the downstream end of the plunge pool and allows for a more natural riffle at the inlet, a run
through the culvert, and pool at the outlet design. The riffle design at the inlet (if necessary) can be designed
without having to account for higher exit velocities from the culvert therefore bed material is not oversized
to account for shear stress and it can be sized adequate for the stream. The armored plunge pool is pretty
self-explanatory. Rock is pushed into the substrate and banks to preform a scour hole and a rock vane or
sill is used at the outlet to set the grade.
4) One other point on culvert crossings. RES is showing an elevated culvert in areas where multiple lines
of pipe are required. Presumable the elevated culvert is set at bankfull, and the other pipe is set for
normal/low flow. The use of rock toe to create a bench at the inlet and outlet of the elevated pipe, as well
as define the low flow channel and prevent scour around the elevated culvert is recommended.
5) Hannah Bridge is the only one that does not include the riffle grade control at the installed culverts,
however #4 above would still
To ensure channel stability and aquatic passage, the Riffle Grade Control (RGC) Detail requires that all
rip -rap will be installed a minimum of 0.5 feet below the proposed stream bed and that an equal mix #51#57,
surge stone and native substrate material be used to back fill the stream bed to proposed grade. A Log Sill
is proposed at the downstream end of the proposed RGC to provide additional channel stability and to
ensure adequate water depth for aquatic passage is maintained across the RGC.
Per our discussion on 7117117 WRC (Travis Wilson) agrees that the proposed design outline above is
sufficient to maintain aquatic passage across the RGC.