HomeMy WebLinkAbout20050061 Ver 3_Application_20070605
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STATE OF NORTH CAROLINA a;~.~.;.
DEPARTMENT OF TRANSPORTATION ~~~~~~,~
MICHAEL F. EASLEY P. O. Box 25201, Raleigh, NC 27611-5202 LYNDO TIPPETT
GOVERNOR PHONE: 919-733-2520 SECRETARY
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May 31, 2007
Mr. Monte Matthews
U. S. Army Corps of Engineers ~ ~ ~.1~ ~ ( v '
Raleigh Regulatory Field Office l.~
6508 Falls of Neuse Road, Suite 120
Raleigh, NC 27615
Subject: Modification to 404 Individual Permit No. 200520314
Modification to 401 Individual Permit No. 05-0061
TIP # R-3415
Widening of NC 67 from Jonesville to Booneville
Yadkin County, North Carolina
WBS: 34541.3.2 (DWQ Permit Fee: $475)
Dear Mr. Matthews:
We have recently started construction of the subject project. As you are aware, over the course of the last
month we have identified a number of locations along the project corridor where quality onsite mitigation
can be preformed in lieu of payment to the Ecosystem Enhancement Program. Although there are
insufficient on-site opportunities to offset impacts for the entire project, we believe that these onsite
improvements can substantially lower our offsite mitigation obligations. We therefore request that the
mitigation requirements in our permits be lowered by accepting the proposed onsite mitigation identified in
this letter.
Construction of this project will require stream relocations at Sites 1, 3 and 6. We believe that the
relocated channels as designed will be a substantial improvement over current conditions. In addition,
scaling errors have resulted in a minor overestimation of the actual culvert extension lengths. The net
result is a 51' reduction in actual culvert extension length throughout the project. A summary table is
attached.
There are other onsite improvements that we will be making at many of the culvert extension locations. A
site by site proposal is listed below with a summary table attached.
Site #1
This triple barreled 9'x15' RCBC will be extended a total of 24'. Adding concrete sills to both stormwater
barrels will isolate base flow to the western barrel. This will increase base flow depth inside of the culvert
and will improve aquatic life passage during periods of low flow. Floodplain construction will provide the
P. O. Box 250, N. Wi~r:esBORO, NC 28659
PRONE (336)667-9111 Fax (336)667-4549
Mr. Monte Matthews
R-3415 Modification, NC 67, Yadkin
Page 2
May 31, 2007
stream earlier access to the easternmost stormwater barrel during storm events. This will decrease water
velocity in the other two barrels and will reduce bed and bank scour potential at the outlet. Constructed
filoodplains will be seeded with native grasses and matted with coir fiber and will look similar to the triple
barreled culvert that we visited on the US 601 project on April 17, 2007.
We are proposing to place the inlets of all three barrels at grade (there is no need to bury the Billed
stormwater barrel extensions and this should prevent a head cut in the base flow barrel). The base flow
barrel outlet will be placed at grade as well.
As a result of the overestimated culvert extension length and the onsite improvements listed above, it is
requested that offsite mitigation associated with this culvert extension be reduced from 32' down to 0'.
Site #1 also has a stream relocation. The existing channel is incised with very little sinuosity and numerous
vertical eroding banks. The new stream channel will provide increased sinuosity and two cross vane rock
weirs. Banks will be placed on a 3:1 slope, seeded and matted with coir fiber. Type I Streambank
Reforestation will be implemented and shall consist of 50% Salix ni~ra and 50% C:ornus amomum. Please
note that eve a(so plan to relocate the eastern rock weir to the western end of the relocated channel where it
will be more beneficial in preventing a headcut. There will be no net loss of stream footage associated with
this relocation.
If the onsite mitigation is approved, the Department is proposing to acquire additional right-of--way to
provide a permanent protected buffer. The proposed buffer will extend southward from the top of the new
Streambank to a distance 30' away. Woven wire restricted access fencing will be erected on the new right
of way line to prevent mowing in the protected buffer. The adjacent land is a grassed meadow.
Considering that the existing channel has no protected buffer, we believe that the proposed 30' buffer is
more than adequate onsite compensation. Our local DWQ representative has verbally agreed to this
proposal. We are also proposing 3-year visual and photographic monitoring.
In light of the onsite improvements detailed above and considering the poor condition of the existing stream
channel, it is requested that offsite mitigation associated with this stream relocation be reduced from 325'
down to 0'.
Site #2
This triple barreled 8'x12' RCBC will be extended a total of 21'. As with Site #l, concrete sills will be
added to both stormwater barrels to isolate base flow to the western barrel. As a result, base flow depth
and aquatic life passage will be improved during periods of low flow. Floodplain construction will provide
the stream earlier access to the easternmost stormwater barrel during storm events. This will decrease
water velocity in the other two barrels and will reduce bed and bank scour potential at the outlet.
Constructed floodplains will be seeded with native grasses and matted with coir fiber and will look similar
to Site # 1.
This culvert is also perched. We will construct the outlet extension with the proposed 1' drop and add a
sloped concrete floor in the base flow barrel. A concrete sill will be added at the end of the base flow
barrel outlet extension up to the natural streambed elevation at that location. I do not believe that will
cause the entire culvert to back fill with natural stream material but do think that will help reduce scour at
Mr. Monte Matthews
R-3415 Modification, NC 67, Yadkin
Page 3
1`1 ay 31, 2007
the outlet since the extension will be on a > 10% grade due to the existing perched condition. We will place
tlhe inlets of all three barrels at grade.
As a result of the overestimated culvert extension length and the onsite improvements listed above, it is
requested that offsite mitigation associated with this culvert extension be reduced from 28' down to 0'.
Site #3
This double barreled 8'x 8' RCBC will be extended a total of 43'. Base flow will continue to be isolated to
the western barrel by adding a sill to the stormwater barrel inlet. Floodplain construction will provide the
stream earlier access to the stormwater barrel during storm events. This will decrease water velocity in the
base flow barrel and will reduce bed and bank scour potential at the outlet. Constructed floodplains will be
seeded with native grasses and matted with coir fiber.
'This culvert is also perched. As with Site #2, we plan to add a sloped concrete floor to the base flow barrel
extension to transition the vertical drop inside of the culvert and reestablish aquatic life passage. Please
note that burying the outlet of this culvert extension will not facilitate retention of natural stream substrate
material. Since the slope will be less than 5%, we plan to place the outlet of this culvert at grade.
Due to the overestimated culvert extension length and the onsite improvements listed above, it is requested
that offsite mitigation associated with this culvert extension be reduced from 46' down to 0'.
Site #3 also has two stream relocations on the inlet side of the culvert, which were constructed last week.
Prior to relocation, the eastern channel had eroded the roadway shoulder over the years. As a result, a
small retaining wall was constructed several years ago to stabilize the area until the channel could be
relocated under this TIP project (see attached photographs). The section just downstream of the wall was
also armored with large concrete slabs years ago. The new channel has provided a more natural setting for
this stream and placed it farther away from the roadway. The retaining wall and concrete slabs were
replaced with 2:1 earthen slopes that were seeded with native grasses and matted with coir fiber. Please
note that we have eliminated Detail 33 (riprap embankment) from the plans. Across vane rock weir has
also been added to the stream. Type I Streambank Reforestation will be implemented and shall consist of
50% Salix nigra and 50% Cornus amomum. There is a net gain of 3' of stream associated with this
relocation.
If the onsite mitigation is approved, the Department is proposing to acquire additional right-of--way to
provide a permanent protected buffer. The proposed buffer will extend northward from the top of the new
streambank to a distance 30' away. Woven wire restricted access fencing will be erected on the new right
of way line to prevent mowing in the protected buffer. The adjacent land is a grassed meadow.
Considering that the existing channel has no protected buffer, we believe that the proposed 30' buffer is
more than adequate onsite compensation. Our local DWQ representative has verbally agreed to this
commitment. We are also proposing 3-year visual and photographic monitoring.
In light of the onsite improvements detailed above, and considering the poor condition of the
preconstruction stream channel, it is requested that offsite mitigation associated with this stream relocation
be reduced from 282' down to 0'.
4
Mr. Monte Matthews
R-3415 Modification, NC 67, Yadkin
Page 4
May 31, ?007
Site #4
This 4'x 5' RCBC will be collared and extended a total of 64' with 60" RCP. This culvert is also perched.
In order to minimize upstream headcut potential, we plan to place the inlet of this culvert at grade. Due to
the existing perched condition, burying the outlet of this culvert extension will not facilitate retention of
natural stream substrate material. As a result, we plan to place the outlet at grade.
As a result of unperching this culvert and reestablishing aquatic life passage, it is requested that offsite
mitigation associated with this culvert extension be reduced from 60' down to 0' or any other lesser number
deemed appropriate. If the Corps is unwilling to provide onsite credit for this improvement, then the off
site mitigation requirement should be increased from 60' to 64' since that is the actual length of the culvert
extension.
Site #5
This 6'x 5' RCBC will be extended a total of 36'. In order to minimize upstream headcut potential, we
plan to place the inlet of this culvert at grade. We will bury the outlet extension 1' and add a concrete sill
up to the natural streambed elevation at that location to assist with substrate retention.
Although this culvert is functioning fairly well, there is substantial streambank instability in two sharp
bends just downstream of the culvert (see plan sheet and attached photos). As a means of reducing off-site
mitigation associated with impacts at this site, we had considered eliminating these sharp bends and
stabilizing the banks even though they are beyond our construction limits.
At the time of our field inspection you considered this proposal to be an improvement in spite of the net loss
of stream footage. After a more detailed review, this turned out to be an impractical means of offsetting the
mitigation fee at this site. As a result, we will revert back to the initial plan to pay the off-site mitigation
and leave the downstream area as is. The off-site mitigation requirement should still be reduced from 38'
down to 36' since that is the actual culvert extension length.
Site #6
Site #6 is a short stream relocation that will basically eliminate a bend in the creek that is falling within our
fill slope. The relocated stream section will have 2:1 banks and will be seeded and matted with coir fiber.
Type I Streambank Reforestation will be implemented and shall consist of 50% Saliz nigra and 50%
Corpus amomum. Total net loss of stream footage associated with this relocation will be 49'.
If the onsite mitigation is approved, the Department is proposing to acquire additional right-of--way to
provide a permanent protected buffer. The proposed buffer will extend southward from the top of the new
relocated streambank to a distance 30' away. Woven wire restricted access fencing will be erected on the
new right of way line to limit disturbance in the protected buffer. The adjacent land is wooded.
Considering that the existing channel has no protected buffer, we believe that the proposed 30' buffer is
more than adequate onsite compensation. Our local DWQ representative has verbally agreed to this
commitment. We are also proposing 3-year visual and photographic monitoring.
We therefore request that offsite mitigation associated with this stream relocation be reduced from 126'
down to 49'.
Mr. Monte Matthews
R-3415 Modification, NC 67, Yadkin
Page 5
May 31, 2007
Site #7
This 4'x 5' RCBC will be collared and extended a total of 44' with 60" RCP. This culvert is also perched.
For reasons previously stated, we plan to place the inlet and outlet of this culvert at grade.
As a result of the overestimated culvert extension length as well as unperching this culvert and
reestablishing aquatic life passage, it is requested that offsite mitigation associated with this culvert
extension be reduced from 48' down to 0' or any other lesser number deemed appropriate. If the Corps is
unwilling to provide onsite credit for unperching the culvert, then the off site requirement should still be
reduced from 48' down to 44' since that is the actual length of the culvert extension.
Site #8
This 4'x 4' RCBC will be collared and extended a total of 36' with 54" RCP. We plan to place the inlet
and outlet of this culvert at grade. There are no onsite improvements available at this location. However,
the off site mitigation requirement should be reduced to from 49' .down to 36' since that is the actual length
of the culvert extension.
Site #9
This 4'x 4' RCBC will be collared and extended a total of 68' with 54" RCP. This culvert is also perched.
As with several of the other sites, we plan to place the inlet and outlet of this culvert at grade since that
appears to be the most logical alternative.
As a result of the overestimated culvert extension length as well as unperching this culvert and
reestablishing aquatic life passage, it is requested that offsite mitigation associated with this culvert
extension be reduced from 98' down to 0' or any other lesser number deemed appropriate. If the Corps is
unwilling to provide onsite credit for unperching the culvert, then the off site requirement should still be
reduced to from 98' down to 68' since that is the actual length of the culvert extension.
Site #10
This 3'x 4' RCBC will be collared and extended a total of 92' with 48" RCP. This culvert is also perched.
Again, due to existing site conditions, we plan to place the inlet and outlet of this culvert at grade.
As a result of unperching this culvert and reestablishing aquatic life passage, it is requested that offsite
mitigation associated with this culvert extension be reduced from 80' down to 0' or any other lesser number
deemed appropriate. If the Corps is unwilling to provide onsite credit for unperching the culvert, then the
off site requirement should be increased. from 80' to 92' since that is the actual length of the culvert
extension.
I am forwarding a copy of this document to Sue Homewood, NCDENR, Division of Water Quality, for her
review. It is requested that the 401 permit for this project be modified to reflect the revised off-site
mitigation requirements and impact totals. Any permit revision should be sent directly to me with a copy
sent to the US Army Corps of Engineers and the NCDOT Natural Environment Unit.
Mr. Monte Matthews
R-3415 Modification, NC 67, Yadkin
Page 6
May 3l, 2007
If further information is required, or if you need clarification on any of these points, please let me know and
we will work through it together. I'd be happy to meet on-site again with anyone who may be interested.
Your early review and consideration will be appreciated.
Sincerely,
Heath Slaughter
Division 1 1 Environmental Officer
Enclosures
cc: Monte Matthews, US Army Corps of Engineers (1 additional copy)
John Hennessy, Division of Water Quality (5 copies)
Sue f tomewood, Division of Water Quality
Mike Pettyjohn, PE, Division Engineer
Trent Beaver, PE, Division Construction Engineer
Mark Freeman, PE, Resident Engineer
Heath Slaughter, Division Environmental Officer
Neil Trivette, Roadside Environmental Field Operations Engineer
Phi] Harris, PE, Natural Environment Unit
Randy Griffin, Natural Environment Engineering Group
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3.
5.
4.
6.
1. Inlet view of Site #1 culvert. Note that base flow is not isolated to one barrel and a high right bank
is preventing most stormwater flow from entering the easternmost barrel.
2. Outlet view of Site #1 culvert. A floodplain has formed behind the base flow barrel instead of
behind the stormwater barrels. We will correct this situation with appropriate floodplain
construction on the inlet and outlet sides of this culvert.
3. Site #1 downstream view.
4-6. Photos of UT to Lineberry Creek east of the Site #l culvert location.
7.
9.
7. Inlet view of Site #2 culvert.
8.
10.
12.
8. Outlet view of Site #2 culvert. Note that flow is not isolated to the base flow barrel and the culvert is
perched. We will be correcting this situation as well as constructing floodplains.
9. Williams Creek just upstream of the Site #3 culvert. This stream has already been relocated away
from this slope failure and retaining wall.
10. Williams Creek at the Site #3 culvert inlet. Due to the relocation, the concrete slabs no longer armor
this streambank. A floodplain will be created in front of the eastern barrel to reduce water velocity
in the base flow barrel during storm events.
11. View of UT to Williams Creek entering the Site #3 culvert.
12. Site #3 culvert outlet is perched. We will be correcting this situation as well as constructing a
downstream floodplain.
13.
15.
17.
14.
lb.
18.
13. Inlet view of Site #4 culvert.
14. Perched outlet of Site #4 culvert. As mentioned in the letter, the pipe extension will be placed at
grade to reduce the slope of the extension.
15. Inlet view of Site #5 culvert.
16. Outlet view of Site #5 culvert.
17-18. Downstream streambank instability at Site #5.
19.
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:. -.
"s
20.
±i~22.
21.
19. Perched culvert outlet at Site #7. As mentioned in the letter, the pipe extension will be placed at
grade to reduce the slope of the extension.
20. Perched culvert outlet at Site #9. As mentioned in the letter, the pipe extension will be placed at
grade to reduce the slope of the extension.
21. Site #10 culvert inlet.
22. Perched culvert outlet at Site #10. As mentioned in the letter, the pipe extension will be placed at
grade to reduce the slope of the extension.