HomeMy WebLinkAbout20180785 Ver 1_KCI Response to IRT Comments Hip Bone MP final 2020.03.17_20200325
Date: March 17, 2020
To: Kim Browning, USACE
From: Tim Morris, Project Manager
KCI Associates of North Carolina, P.A.
Subject: Hip Bone Creek Restoration Site
Mitigation Plan Review – Response to IRT Comments
Cape Fear River Basin ‐ 03030003
Chatham County, North Carolina
DEQ Contract No. #7528
DMS Project #100059
USACE AID #: SAW‐2018‐01160
Below are our responses to comments received on the mitigation plan for the Hip Bone Creek Restoration
Site. All of the following changes have been completed in the revised mitigation plan. Please contact me
if you have any questions or would like clarification concerning these responses.
Mac Haupt and Erin Davis, NCDWR:
1. Page 6, Section 3.1 – In addition to identifying the streams as headwater systems, it’s important to
note their origins as downstream of farm ponds.
The wording has been changed to “The project streams begin as headwater systems on the site,
with Tributary 1 (T1) and Tributary 2 (T2) beginning downstream of two farm ponds.”
2. Page 8, Section 3.1.2
a. It would be helpful see property boundaries in the vicinity of the project. Could a tax parcel layer
please be added to Figure 2 or a zoomed out Figure 5?
The Chatham County Parcel Data has been added to Figure 2.
b. What are the anticipated future land uses for the project watershed?
We have added at the bottom of 3.1.2.: “The development pressure for the project watershed is
anticipated to be low to moderate. This section of Chatham County has retained its rural
character and the majority of residences within the project watershed are farm homesteads or
other rural acreages.”
c. Please include a discussion of existing vegetation within the p roject site, in particular the species
composition of the forested areas along the upper T1 and T3 wetlands.
We have added to the first paragraph in 3.1.2: “There are sections of narrow forested wetland
area along T1 and T3. The overstory vegetation in these sections consists primarily of red maple
(Acer rubrum) in the canopy with an understory of Chinese privet (Ligustrum sinense), and mixed
rushes and sedges.”
d. Please discuss any site constraints (e.g. existing utilities, existing crossings/paths). Are the
existing stream crossings fords or culverts? Does the electrical line crossing the top of T3 have
an associated easement?
We have added at the end of the first paragraph in 3.1.2: “There are five existing piped crossings
at the site, most in disrepair, and one private power line that crosses the top of T3.”
3. Page 12, Section 3.1.3
a. Besides Chinese privet, what other invasives have been documented on site?
In the second paragraph of 3.1.3, we added: There is an existing riparian buffer in this area with
a sparse canopy of native hardwoods, and an understory that is comprised primarily of Chinese
privet and other invasive species such as autumn olive (Elaeagnus umbellata) and callery pear
(Pyrus calleryana).
b. In this section T2 is identified as a linear wetland; however, the JD lists it as a 368 linear foot non‐
wetland water. Please confirm this feature type.
We added to the end of the first paragraph of 3.1.3.: “Tributary 2 (T2), which was included as a
stream in the jurisdictional determination, will be treated as contiguous wetland feature for the
purpose of this project’s accounting following a field decision with the North Carolina
Interagency Review Team (IRT) (see Appendix 12.9).”
c. Please include a table or brief discussion of the NC SAM, NC WAM and DWQ Stream Id form
results.
We added Table 3. Existing Stream and Wetland Conditions, which summarizes the results of
these stream and wetland analyses. All other table numbering in the report has been adjusted
as a result.
d. Side note, it was confusing having the appendices referred to as sections within the plan
narrative.
These “Sections” have been changed to Appendices.
4. Page 18, Section 4.0 – Please state what assessment method was used to determine that “all
stream channels have low functional values”.
We have noted that he North Carolina Stream Assessment Method (NC SAM) was used to determine
the quality of the existing streams.
5. Page 20, Section 6.0 – It would be helpful to have the information in paragraph two stated earlier in
the document, perhaps in the Introduction.
We have now added the information regarding what stream reaches are not being used for stream
mitigation credit in the last paragraph of Section 1.0.
6. Page 20, Section 6.1 ‐ Flow is a general concern for this project. In particular, whether flow will be
sustained in the upper 300‐foot section of T1 Reach 1 that is proposed to be raised 1‐2 feet.
We believe that the riparian wetland at the base of the pond in addition to the surrounding seepage
inputs from the hillsides will provide adequate hydrology for this reach of T1.
7. Page 20, Section 6.1 – Since establishment of vegetative cover and vigor can be a challenge on Priority
2 restoration banks/benches, please include a discussion on how the soil restoration will be addressed
during construction and reference potential adaptive management.
We have added the following: “Furnished or salvaged topsoil will be used to surface treat all planting
areas within the floodplain extents shown on the plans. Adequate lime and fertilizer will be used to
ensure adequate vegetative stabilization.”
8. Page 21, Section 6.2 – In order to justify a 2.5:1 ratio, please include bank grading in list
proposed work (as noted on Design Sheet 9).
We have added this.
9. Page 21, Section 6.3 – Given that multiple wetland restoration areas abut the proposed
conservation easement boundary, is there a concern about hydrologic trespass?
No, we are not concerned at this location. The areas that we are including in the conservation
easement encompass the lowest elevations of the site and then adjoin upland pasture. The conditions
in these adjoining areas will be similar to the existing conditions and should not impede the
landowner’s future use of the land.
10. Page 21, Section 6.4 – The number of crossings for the project size is concerning. Fragmentation impacts
the potential functional uplift.
We try to minimize the number of crossings wherever we can, but landowners often desire crossings
where they currently have them to continue using their land outside of the easement, which was
the case at this site. We always do our best to install structures and roadways that minimize the
impact of the crossings by having continuous flow through the pipes.
a. Four of the five crossings are proposed to be 30 feet wide. However, the lower T1 crossing is
proposed to be 60 feet wide. Can this crossing width be reduced to 30 feet? If not, please
explain why.
We needed a 60‐foot easement exception to accommodate a landowner request ensuring
adequate access in future years. However, the current proposed configuration will not use the
entire 60‐foot length for the crossing. Approximately 30 feet will be used for the pipe and the 15‐
foot roadway. The remainder of stream in the exception will be restored similar to the rest of the
project.
b. The T3 crossing is located approximately 150 feet north of the proposed conservation easement
boundary. Can this crossing be relocated south of the easement boundary? If not, please explain
why.
Unfortunately, the topography in that location doesn’t allow for that type of reconfiguration.
c. Will the proposed crossings be gated and/or will the proposed fencing overlap the culvert to limit
livestock access to the stream?
Yes, all of the crossings will be fenced to exclude livestock and gates will be installed at all
crossings to allow easy access as necessary.
11. Page 23, Section 6.6 – Sheets 3 and 4 Details for proposed riffle enhancement, riffle grade
control, and stabilized rock outlet differ from text included in this Section. The details have 30%
native stream material while the text states 10%. The details do not include class 1 stone while the
text does. Please make text and details consistent.
This has been corrected in the report to match the detail.
12. Page 26, Section 6.8
a. Please include native seed mix composition (species, quantity, wetland status).
Please see the planting lists on Sheet 17 of the Construction Plans.
b. Please identify target communities.
In general, we prefer not to designate a specified community type since a site can generally not
be converted to that community within the timeframe of monitoring. We do select trees that are
in line with the surrounding community types, though.
13. Page 30, Vegetation Performance – Note that only volunteer species that are included on the
approved mitigation plan plant list may count toward the vegetation performance standard.
We added: “Volunteers that are included on the approved mitigation plan plant list must be present for
a minimum of two growing seasons before being included in performance standards in Year 5 and Year
7.” Additionally we added an extra list of native trees that could be used for substitutes or seen as
desirable volunteers. This text reads, “Other native desirable species that have the potential to volunteer
at the site or be used for planting substitutions towards the performance standard include other native
oaks (Quercus sp.), native Celtis species (Celtis sp.), tulip poplar (Liriodendron tulipifera), native hickories
(Carya sp.), native dogwoods (Cornus sp.), native elms (Ulmus sp.), black walnut (Juglans nigra), native
Nyssa species (Nyssa sp.), and cottonwood (Populus deltoides).”
14. Page 30, Stream Hydrologic Performance – Please rephrase: The project streams must also show a
minimum 30 days’ continuous flow days within each calendar year.
We rephrased to state: “The project streams must also show a minimum of 30 continuous flow days
within each calendar year (assuming normal precipitation).”
15. Page 31, Section 8 – For installed gauges and wells, DWR recommends quarterly data download and
inspection to reduce the risk of data loss due to instrument malfunction.
We added: “Daily data will be collected and downloaded from the 8 automatic wells at a minimum
frequency of once each quarter over the 7‐year monitoring period following implementation.”
16. Page 31, Vegetation Monitoring – Currently there are no wetland gauges or veg plots located within
any of the proposed wetland rehabilitation areas or wetland enhancement areas to illustrate
functional uplift. DWR requests two additional wetland gauges be located within proposed
rehabilitation areas. Also, DWR would like to see at least two of the random veg plots be located
annually within the proposed wetland rehabilitation planting areas or enhancement supplemental
planting areas.
Two wetland gauges have been added to the proposed rehabilitation areas. We have noted to place
two of our 8 random vegetation plots within wetland rehabilitation or enhancement areas
17. Page 32, Visual Assessment – Please include photo locations at all crossings.
Photo points have been added for all stream crossings.
18. Please add a Maintenance Plan as a new section or appendix summarizing the types of issues that
may arise during monitoring and how those issues would be addressed, including invasive species
treatment. DWR recommends a minimum annual treatment of Chinese privet.
A Maintenance Plan has been added as Appendix 13.
19. Figure 9 – The flow documentation stations on T3 and T1 are very close to the stream reach start
points. DWR requests these stations be shifted north approximately 50‐75 feet.
The flow stations have been moved 50 feet north on Figure 9.
20. Sheet 1 – The Sheet 1 table does not match the Table 11 values under the Existing Footage/Acreage
and Mitigation Credits columns. Please update.
We adjusted the significant digits in a previous draft of the report and have now made sure Sheet 1
matches the report.
21. Sheet 2 – Please add buried log sill and buried brush material icons to the project legend, as well
as detail sheets.
These have been added to the project legend.
22. Sheet 3 – DWR appreciated the riffle grade control note to include woody debris to enhance
habitat.
23. Sheet 4 – Please add a culvert crossing detail.
A culvert sheet (Sheet 5A) has been added with details for the structures.
24. Sheet 4 – Please confirm that the water quality treatment area will be self‐sustaining and requires no
long term maintenance. Also, will this treatment area be seeded and planted?
Yes, the water quality treatment areas will not require any maintenance in the long term. They will
be seeded with the native seed mix, but trees will not be planted within the treatment area itself.
25. Sheet 4 – The Project Legend includes channel filling. Please include a channel fill detail. If partial
filling is proposed, please indicate the maximum depth from top of bank to be filled. Also, the plan
narrative references “plugging surface ditches”. Please confirm whether ditches will be plugged. If
plugs are proposed, please include a detail identifying the minimum plug width (DWR recommends a
minimum of 50 feet) and whether a restrictive material core will be used.
A channel fill detail has been added to the plans. Most of the surface ditches to be plugged onsite
are not especially deep or wide. These types of ditches will be filled similarly to the channel. Our
experience with sites like this is that large plugs are not necessary for these small surface ditches.
Those surface ditch locations are indicated with notations on the plans.
26. Sheet 9 – Please show floodplain grading extents associated with notes along T3 and T3‐1.
The extent of grading is shown in these areas.
27. Sheet 13 – Please show a wetland planting zone and include seed mix information.
Given the size of the wetlands in relation to the stream riparian buffers, we are considering these as
one contiguous planting zone. We anticipate the riparian wetlands to be integrated with the
streamside vegetation and have designed a planting plan that incorporates species that will succeed
across the site. Our permanent native seed mix information is shown on Sheet 17.
28. Sheet 13 – What does “per design representative guidance” refer to?
Design representative guidance indicates areas where the designer may make minor adjustments
during construction; these field adjustments allow us to ensure that all features are properly installed
and achieve the desired function considering the specific conditions at each location.
29. Sheets 15 & 16 – Please show anticipated gate locations.
These have been added to the specified sheets.
30. For future site submittals, please show the plan view and corresponding profile on the same design
sheet.
Noted.
31. Appendix/Section 12.2 Soil delineation and Borings ‐ The title reflects that a hydric soil delineation
was completed, please show these boundaries on the included figure. While sufficient representative
boring logs were submitted, it’s assumed that additional sample points were taken in the field to
delineate the hydric soil boundaries (i.e. more than one sample point per wetland area). In the future
please, show all sample point locations on the associated soil report figure.
The hydric soil areas have been added to the figure. The point locations will be added for future
sites.
32. Appendix/Section 12.2 Groundwater Data – Please shift labels to align with corresponding lines.
We have reformatted this slightly to improve columns.
USACE Comments, Kim Browning:
1. The correct USACE Action ID is SAW‐2018‐01160. Please correct the cover page.
This has been corrected.
2. General Plan Comments:
a. Please include a maintenance section with monitoring. For example, crossings, fence,
invasives…and who will be responsible.
A Maintenance Plan has been added as Appendix 13.
b. This mitigation plan seemed to differ from the NCDMS template, and was difficult to follow at
times. Also, the appendices were included as Section 12, which was confusing.
Minor changes have been made to the plan format as the project progressed. We have changed
the names of the appendices.
3. When submitting the PCN, please include an estimate of the number of trees, or acres, to be cleared
for the NLEB 4(d) Rule.
Noted.
4. Please label wetlands on Figures 8 and 9 to match the JD map. The asset tables should
correspond to these labeled areas.
The wetland labels have been added.
5. Table 4 and Page 21: Please describe the level of microtopography in regards to surface ponding.
We have added “minor wetland microtopography (+/‐ 0.5 foot based on average ground
elevation).” This development of microtopography will add roughness to the wetland terrain and
encourage surface retention in the upper profile, but will not be installed as to allow large swaths
of areas to be ponded more than others.
6. Page 18, last paragraph: “The consideration of future impacts to the areas that could limit
functional uplift opportunities…” Please explain what considerations were given, such as utility
installation through the easement, crossing failures, adjacent land development, pond dam
breeches, etc.
We have added “Consideration of future impacts to the area that could limit functional uplift
opportunities is important when assessing project potential. For this site, the existing ponds onsite
were deemed stable and the likelihood for development immediately adjacent to the site that could
impact the streams after project completion was evaluated to be low. It is predicted that as the site
matures, its ability to mitigate for any negative impacts within the project area and outside of the
easement will continue to strengthen.”
7. Page 21: In wetland rehabilitation areas, if hydrology and vegetation are proposed to be
enhanced, functional uplift should be demonstrated by additional gauges and veg plots. Additionally,
wetland enhancement areas should demonstrate functional uplift. Removal of debris and invasive
treatment is expected on all reaches, so perhaps a discussion of the NCSAM functional assessment
rating as LOW for habitat might be justification.
As stated above, two wetland gauges have been added to the proposed rehabilitation areas. We
have noted to place two of our 8 random vegetation plots within wetland rehabilitation or
enhancement areas.
8. Page 26: Please list herbaceous seed mix and address how fescue will be treated/removed.
We have added to the last paragraph: “Existing undesirable pasture grasses will be sprayed with
herbicide and left fallow until full mortality is achieved. The areas will then be scarified or disked to
break up any existing compaction prior to seeding and stabilizing with temporary and permanent
seed mixes as prescribed in the project plans.”
9. Section 7.0‐Vegetation Performance: Please add 320 steams/acre for monitoring year 3.
This has been added.
a. Volunteers may only count towards success if they are in the approved planting plan.
As noted in a previous DWR comment, we have added this.
10. Section 8‐Veg Monitoring: Please add veg plots to wetland rehabilitation areas (random plots are
fine).
As stated above, we have noted to place two of our 8 random vegetation plots within wetland
rehabilitation or enhancement areas
11. Wetland rehabilitation/reestablishment—It would be beneficial to add some coarse woody debris to
the depressional areas and throughout the wetland for habitat, and to help store sediment, increase
water storage/infiltration, and absorb water energy during overbank events.
At this site, we are showing woody debris installed along T2 and above T3. For the remaining wetland
areas, we will add woody debris as available to encourage habitat development. However, because
this site is not already wooded, there will be a limited amount of wood generated during construction
to add to the site. A note about adding wood to the wetlands and stream floodplain has been added
to the plans and this note was added to the mitigation plan “As available during construction, wood
will be added to the wetlands and the stream floodplain for added habitat complexity, and to help
store sediment, increase water storage/infiltration, and absorb energy during overbank events.”
12. Page 32: Wetland hydrologic monitoring: Please add wells to all wetlands that propose
hydrologic uplift and update Table 14 as necessary.
As noted above, 2 additional wetland pressure transducer gauges have been added to wetland
rehabilitation areas.
13. Page 32: Please depict fixed photo points on Figure 9.
Fixed Photo Points have been added to Figure 9.
14. Please include the approved map for the PJD.
The map was included in Appendix 12.7 with the PJD.
Sincerely,
Tim Morris
Project Manager