20210106 Ver 1_DWR Response Letter 12-8-2021_20211208

IA Martin
Variettc
December 08, 2021
Sue Homewood
Division of Water Resources
Department of Environmental Quality
450 W. Hanes mill Rd, Suite 300
Winston Salem, NC 27105
Dear Ms. Homewood:
Thomas Brown
East Division Wetland Specialist
Please reference the Request for Additional Information from your office, received by email on October
5, 2021, associated with SWR#20210106. A response to the request can be found below, with the
questions/comments from the request underlined.
1. Please provide a description and explanation of the floodplain boulder/ log sills as this
is a feature DWR does not typically see in NC stream restoration.
See details on Sheet 5.14 of the design plan set. The floodplain boulder and log sills will be buried beneath
the design surface of the floodplain and will not be visible after construction is complete. The sill
structures will provide grade control for the floodplain area while vegetation becomes established to
prevent down -valley channel migration and/or short -cutting of the proposed channel.
2. Have appropriate site investigations been completed to determine whether bedrock
is likely to be encountered within the proposed relocation area? Is depth to
groundwater known within the relocation area?
Martin Marietta has conducted exploratory drilling along the corridor of the proposed channel. Results
from this effort show that bedrock should not be encountered with the construction of the proposed
channel. Depth to water table is not known in the area of the proposed channel, but the proposed channel
will generally follow the same elevation as the existing stream and therefore is expected to intercept
ground water in a similar way to the existing condition.
3. The Division appreciates that the plans include a notation that 4-6 inches of topsoil
will be added to the proposed excavation area. DWR is still concerned that this
amount of topsoil may not be sufficient to support tree and shrub growth depending
on the type of subsoil within the restoration and floodplain area. Please provide
further details on site soils expected within the restoration and floodplain area and
Martin Marietta East Division
2235 Gateway Access Point, STE 400, Raleigh, NC 27607
m. [phone] e. [e-mail]
www.martinmarietta.com

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the whether the expected soils within these areas will support the proposed
vegetation or provide a brief soil restoration plan to further explain what actions will
be taken to ensure future vegetation success.
The underlying subsoils will be prepped and loosened with the excavator teeth prior to the placement of
4-6 inches of topsoil. The project team is confident that we will meet the vegetation success criteria
established for the project.
4. Please clarify whether there will be any phasing of seeding/ stabilizing
topsoil/ floodplain soils to ensure that construction areas will be stabilized as quickly as possible to avoid
problems that could occur if all bare areas remain so until
completed construction and final stabilization activities.
All disturbed areas and stockpiles will be stabilized with temporary ground cover per the guidelines
established in the existing NCGO2 permit.
5. Please modify the planting list as recommended by NCWRC. DWR also recommends
removing black walnut from the planting list due to its allelopathic nature. DWR also
recommends that you consider whether the site will be wet enough to support
buttonbush.
See attached revised vegetation sheet (6.2)
7. DWR requests that you make the following changes to the monitoring plan:
a. Please add photo points at the inlet and outlet of the new crossing.
b. Please update Table 10.2 to provide site specific information such as stream
feature names and correct numbers of vegetation plots, gage stations and
photo points.
c. Please specify how bankfull events will be measured.
a. and b. Please see attached updated monitoring plan containing table 10.2.
c. Bankfull events will be measured using crest gages installed near the upstream and downstream
portions of the restored main channel (Stream A). The gages will be monitored after significant
precipitation events to determine peak water levels relative to the adjacent bankfull elevation.

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We appreciate the opportunity to respond to this request. Please feel free to contact me by phone or
email at any time for any additional information or clarification.
Sincerely,
Thomas Brown
East Division Wetland Specialist
Attachments by email:
Exhibit I Updated Monitoring Plan 12-8-2021
1111 DENVER QUARRY PRELIM DESIGN -REVEGETATION SPECIES LIST