20200018 Ver 1_Notice of Mitigation Plan Addendum Approval & Initial Credit Release

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Harry and Paul,

The 30-Day As-Built/MY0 and Mitigation Plan Addendum review for the NCDMS Laurel Valley Mitigation Site (SAW-2020-00053) ended July 23, 2023. Per Sections 332.8(g)(2) and 332.8(o)(9)
of the 2008 Mitigation Rule, this review followed the streamlined review process. All comments received from the NCIRT are incorporated in the email below. There were no objections
to approving the mitigation plan modification request or issuing the initial 30% credit release of 1,459.257 warm stream mitigation units. Please find attached the mitigation plan
addendum approval letter and updated signed ledger.

Mitigation Plan Addendum and Modification Request

Maria Polizzi, DWR

1. I have no issues with the Mitigation Plan addendum.

Dave McHenry, WRC

1. No comments on the addendum.

Erin Davis, USACE

1. DMS’ questions/comments regarding the proposed Addendum and MY0 Report (comment #5) provided clarity and transparency, which was helpful for this review and understanding the modification
request.

As-built Drawings and MY0 Report

Maria Polizzi, DWR

1. As-built plans show numerous substitutions of brush toe for cover logs. Can you explain why this change was needed?
2. Based on Photo Point 3 the crossing at UT1-Reach 1 does not appear to be embedded per plan.
3. I like the layout of the longitudinal profiles; these are much easier to read than others I have seen.

Dave McHenry, WRC

1. I don’t have appreciable comments on YR 0 report. But what stands out to me is the apparently wide scour and/or excavated pools of culvert outlets at ~ sta. 101 and ~ sta. 206+40.
I have seen this on a few projects lately, versus restoring a more natural channel width, and I realize engineers may be trying to minimize the risk associated with existing pipes
that are retained. So, it’s probably just worth watching (as I am planning, as possible) to gage that sediment deposition, lateral scour, and or pool outlet lowering don’t develop
over the years. The UT at 101 is small too. Fortunately, these culverts are backwatered.

Erin Davis, USACE

1. Section 2 and Table 10 both state that the veg survey was completed in January 2023 and that construction planting of the site was completed in March 2023. How was the veg survey
done before the completion of site planting?
2. There were numerous bank treatment changes from brush toe to cover logs. On other projects we have observed that cover logs can become displaced or eroded behind. Are these concerns
based on the number of substitutions and size of the stream reaches? Also, based on the redline it appears that in some channel bends include a cover log sandwiched between brush toe
sections, is this accurate?
3. DWR made a mitigation plan comment (#25) about impacts and potential mortality of existing trees proposed to remain along designed stream channels. Since the three sections of channel
realignment were done in order to save trees, please track mature tree survival in these areas through monitoring.
4. DWR previously asked whether outlet stabilizations included rock placement and Wildlands responded no except for the floodplain pool (comment/response #28). Were non-hardened options
considered for wetland/floodplain outlets along UT1 and UT2? Please include photos of rock sills and rock outlet stabilizations added along UT1 (Sta. 206+96 & Sta. 224+05) in MY1 report.
5. Why was the plunge pool depth not modified downstream of the existing crossing at Sta. 101 along East Prong Hunting Creek? Is the mid channel bar in this area shown in PP19 a concern?
6. Please include a photo of the new French drain installed along CE and driveway boundary in the MY1 report.
7. The project fencing is shown in the middle of the utility corridor where the easements overlap. Has the extent of veg maintenance area been clearly marked inside the fence line? Per
Wildlands response to USACE mitigation plan comment #34, CE signs were to be installed.

Please reach out with any questions.

Regards,

Erin

Erin B. Davis

Mitigation Specialist, Regulatory Division

U.S. Army Corps of Engineers, Wilmington District

[phone] work cell

its and 0.565 wetland mitigation units. Please find attached the current signed ledger. The IRT is not requesting a site visit at this time.

Maria Polizzi, DWR

1. The planting density of sycamore appears high in Veg. Plot 6 at 43%. The planting plan shows 15% for this species. Be sure to maintain proper spacing when planting to avoid areas
with a high density of one species.
2. I like the callouts for species density on your CCPV.
3. Thanks for including so many photos. These are very helpful.

Dave McHenry, WRC

1. Aside from being impressed by the cool rail car bridge crossing, the only thing that caught my attention was maybe a split channel at 18+50, though it’s not real clear from photo
if that is truly the case. They note they had bedrock issues in this general location and had to reroute things a bit.

Erin Davis, USACE

1. Photo Point 10 – A vegetated mid channel bar is shown. This appears to the approximate location where bedrock was encountered, and the channel was widened. Please include a condition
update and additional photos in the MY1 report, including whether proposed hand repairs were completed.
2. Photo point 19 – The BMP outlet appears heavily armored. In future designs please consider embedding the stone more to reduce the risk of riprap trapping crossing wildlife.
3. Figure 3 CCPV – Several monitoring stations were relocated from the approved mitigation plan monitoring figure 11 locations. While it is anticipated that some gauges and veg plots
may be slightly shifted (a few feet) in the field, we expect the general locations of monitoring stations to align with the mitigation plan figure that was reviewed, commented on, and
approved by the IRT. Justifications need to be provided for any major monitoring station changes (e.g., bedrock encountered, change in planted area).

a. Planted wetland reestablishment credit areas must demonstrate that they meet the vegetation performance standard; please relocate veg plot 3 completely within wetland reestablishment
credit area as shown on the approved mitigation plan monitoring figure 11.
b. USACE made a mitigation plan comment (#3) requesting a temporary veg transect in the berm/spoil removal area along Reach 1A near XS 1. As stated in Baker’s response, please include
this data in the MY1 report.
c. DWR made a mitigation plan comment (#6) requesting shifts in the groundwater well locations in the southeast reestablishment wetland. The upper well was relocated closer to the credit
area boundary as per USACE and DWR request. But the lower well (MCW4) was installed a distance from the stream and overlapping a rehabilitation area rather than closer to the stream
channel as per DWR request. Please explain why the DWR request was not met.
d. Why were groundwater wells in the northwest reestablishment wetland shifted from their originally proposed locations, MCW1 to the south and MCW2 to the north?

Please reach out with any questions.

Regards,

Erin

Erin B. Davis

Mitigation Specialist, Regulatory Division

U.S. Army Corps of Engineers, Wilmington District

[phone] work cell

lately, versus restoring a more natural channel width, and I realize engineers may be trying to minimize the risk
associated with existing pipes that are retained. So, it’s probably just worth watching (as I am planning, as
possible) to gage that sediment deposition, lateral scour, and or pool outlet lowering don’t develop over the
years. The UT at 101 is small too. Fortunately, these culverts are backwatered.

Erin Davis, USACE
1. Section 2 and Table 10 both state that the veg survey was completed in January 2023 and that construction
planting of the site was completed in March 2023. How was the veg survey done before the completion of site
planting?
2. There were numerous bank treatment changes from brush toe to cover logs. On other projects we have
observed that cover logs can become displaced or eroded behind. Are these concerns based on the number of
substitutions and size of the stream reaches? Also, based on the redline it appears that in some channel bends
include a cover log sandwiched between brush toe sections, is this accurate?
3. DWR made a mitigation plan comment (#25) about impacts and potential mortality of existing trees proposed to
remain along designed stream channels. Since the three sections of channel realignment were done in order to
save trees, please track mature tree survival in these areas through monitoring.
4. DWR previously asked whether outlet stabilizations included rock placement and Wildlands responded no
except for the floodplain pool (comment/response #28). Were non-hardened options considered for
wetland/floodplain outlets along UT1 and UT2? Please include photos of rock sills and rock outlet stabilizations
added along UT1 (Sta. 206+96 & Sta. 224+05) in MY1 report.
5. Why was the plunge pool depth not modified downstream of the existing crossing at Sta. 101 along East Prong
Hunting Creek? Is the mid channel bar in this area shown in PP19 a concern?
6. Please include a photo of the new French drain installed along CE and driveway boundary in the MY1 report.
7. The project fencing is shown in the middle of the utility corridor where the easements overlap. Has the extent of
veg maintenance area been clearly marked inside the fence line? Per Wildlands response to USACE mitigation
plan comment #34, CE signs were to be installed.

Please reach out with any questions.

Regards,
Erin

Erin B. Davis
Mitigation Specialist, Regulatory Division
U.S. Army Corps of Engineers, Wilmington District
[phone] work cell
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