20061152 Ver 1_More Info Received_20070827

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Evans, Mechwart, Hambleton 8~ Tilton, Inc.
Engineers, Surveyors, Planners, Scientists
August 24, 2007 ~~~ ` , ~~-', ~'? ~!~ ~~
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Mr. Kevin Barnett AUG `~ 7 2007
North Carolina Division of Water Quality
Asheville Regional Office DENT, - VYA~i"~R ~i;/~LiIY
2090 U.S. Highway 70 YV~TIAbR.~:~+~DSTO'~PAI'LAiER6RANCH
Swannanoa, NC 28778
Re: Response to Request
Silver Creek Stream
Project # 06-1152.
Dear Mr. Barnett:
for Additional Information;
Restoration Project; DWQ
On behalf of Wetlands Resource Center (WRC), we are providing the discussion that follows and
the attached information in response to the letter dated May 25, 2007, in which the State of North
Carolina provided Section 401 certification for the Silver Creek stream restoration project in Burke
County. The letter indicated a number of conditions to be fulfilled within 60 and 90 days related to the
accounting for sediment that was previously discharged to the main stem of Silver Creek and the impacts
to two tributary streams. This letter documents the actions taken to fulfill these conditions. Corresponding
sediment data tables and site photographs are also included on the enclosed disk and were collected and
documented by WRC.
Sedimentation Clean Up
Pre Clean-up Conditions
Cross-sectional sedimentation depth measurements were taken along the specified 375 foot reach
of Silver Creek downstream of the restoration project during the week of June 4, 2007, before clean-up
activities commenced. This data is presented in the Excel spreadsheet entitled "375 Sediment" on the
enclosed disk (within rows labeled as "Before"). Sediment cross-sections were taken at 75 foot intervals
along the 375 foot reach. Cross-sectional depth measurements were taken at 2 foot intervals across the
width of the stream (left bank to right bank, facing downstream). The first number given indicates the
depth of water at the measurement location; the second number indicates the depth of sediment. The
depth of sediment value refers to a measurement of the sand (sediment) above the "natural" bottom of the
stream channel.
Photographs were taken at each cross section location to document the pre clean-up condition and
are provided on the attached disk within the folder labeled "PRE Photos 375 ft". The photo file names
correspond to the cross section interval they depict (e.g., picture filename "down 75" refers to a photo that
was taken at a section 75 feet downstream of the restoration project).
Post Clean-Up Conditions
Removal of accumulated sediment within the 375 toot reach occurred during the week of July 16,
2007 (within the 60 days specified in the Section 401 certification letter), according to the methodologies
described within the 401 permit application document (E1VIH&T, 4/24/07). Removed sediments were
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NCDWQ -Asheville August 24, 2007
Silver Creek Stream Restoration; DWQ Project # 06-1152 Page 2 of 3
placed in an upland location and stabilized, as indicated on the attached spoil area exhibit and photos
within the folder labeled "stabilized sediment photos". As required, the cross-section sediment depths
were taken again along the 375 foot reach following removal of sediment. This data is presented in the
Excel spreadsheet entitled "375 Sediment" on the enclosed disk (within rows labeled as "After"). Post
clean-up photographs were taken at each cross section location and are provided on the attached disk
within the folder labeled "POST Photos 375 ft". Again, the photo naming convention describes the
location along the channel reach
In addition, cross-section sediment depth measurements were also taken at 75 foot intervals
downstream from the 375 foot clean-up area for an additional 1500 feet (refer to Excel table entitled
"1500 downstream"), following removal of sediment within the 375 foot reach. Sediment measurements
were also taken upstream from the Silver Creek restoration project at 75 foot intervals for 1500 feet (refer
to Excel table entitled "1500 upstream"). In addition to the sedimentation measurements, photographs
were taken at each of these additional cross section locations. The photographs taken for each reach are
included on the enclosed disk within folders labeled "POST Photos Downstream 1500 ft" and "POST
Photos Upstream 1500 ft", respectively. As before, the naming convention for the individual photos
suggests the location of the corresponding cross-section location. For example, the photo labeled "up 450
ft" within the folder "POST Photos Upstream 1500" shows the cross section 450 feet upstream from the
beginning of the Silver Creek Project.
Results
The depth of sediment within the 375 foot section averaged 5.0 inches before sediment removal
activities commenced. Following sediment removal efforts, the depth of sediment was found to average
2.3 inches within that reach. The 1500 foot section upstream from the Silver Creek project averaged 3.3
inches of sediment, and the 1500 feet downstream from the 375 foot reach averaged 2.1 inches. These
measurements indicate that the sediment removal was successful, since the average post clean-up
sediment depth within the 375 foot reach is similar to the depths of sediment measured upstream and
downstream of the project. On-average, the sediment depths are less downstream from the 375 reach than
upstream from the Silver Creek restoration project. This suggests the downstream reach does not contain
sediment beyond the depths observed on other portions of Silver Creek that would have not been
impacted by the stream restoration project completed by WRC.
Restoration along Unnamed Tributaries B and C
Required Restoration -Unnamed Tributaries B and C
As a condition of the issued 401 permit, WRC was to restore Unnamed Tributaries B and C such
that pattern, profile, and dimension of the channels is restored and stable. The adjacent 25 foot riparian
zone along the stream reaches were to be stabilized, planted and protected by cattle exclusion fencing as
described within the 401 permit application document (EMH&T, 4/24/07). The plantings were to blend
with the plantings already proposed within the 30 foot buffer along the Silver Creek mainstem as part of
the restoration plan.
As shown in the enclosed map, the stream stabilization work, buffer plantings, and fence
installation were completed during April, 2007. In addition, the culverts that had been replaced within
Unnamed Tributaries B and C were taken out and re-set 20% below the elevation of the stream bed, to
promote a native stream bed within the culverts. Photos within the folder labeled "trib b photos"

NCDWQ -Asheville August 24, 2007
Silver Creek Stream Restoration; DWQ Project # 06-1152 Page 3 of 3
document the restored portion of Unnamed Tributary B, and photos within the folder labeled "trib c
photos" document the restored portion of Unnamed Tributary C.
Post-Restoration Monitoring_ -Unnamed Tributaries B and C
The May 25, 2007 letter specified certain conditions related to monitoring of these two tributary
channels. We propose that the monitoring data taken along the tributaries will be provided within the
annual monitoring reports for the Silver Creek full-delivery restoration project prepared for submission to
the EEP and which address the published restoration guidelines for the State of North Carolina. As part
of that monitoring effort, stream geomorphology and general stability will be assessed in the spring and a
vegetative assessment will be performed in the fall of each year. The DWQ will receive a copy of each
annual monitoring report no later than December 31st of each monitoring year. We anticipate the first
monitoring report to be submitted at the end of 2007.
To ensure that stability is achieved and the riparian plantings are surviving, the restored portions
of Unnamed Tributaries B and C will we monitored for a period of 5 years. This monitoring shall
coincide with planned monitoring events along the Silver Creek mainstem and Unnamed Tributary A as
required by the EEP and described above. Vegetation monitoring will consist of annual woody stem
counts within sampling plots established along the tributaries. To provide consistency with the monitoring
of the rest of the restoration project and in conformance with the states' monitoring guidelines, a single
100 m~ sample plot will be established within the planted riparian areas of both Unnamed Tributaries B
and C. Photographs taken along the streams will also be provided within those monitoring reports for
comparative purposes.
Respectfully Submitted,
EVANS, ME HWART, HAMBLETON & TILTON, INC.
'I _
V
Mil s F. Hebert, P.E.
Attachments
Cc (w/o attachments): Steve Chapin, USACE Asheville
Cyndi Karoly, NCDWQ
Danny Smith, DWQ Wetlands and Stormwater Unit
Laura Herbert, NCDENR Division of Land Resources
Ron Linville, NC Wildlife Resources Commission