20100597 Ver 1_Mitigation Bank Proposal_20071212

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Wetland and Natural Resource ,06
Consultants
December 9, 2007
Ms. Amanda Jones
US Army Corps of Engineers
Asheville Regulatory Field Office
151 Patton Avenue
Asheville, NC 28801
RE: Sixmile Creek Stream and Wetland Mitigation Bank
Mecklenburg County, North Carolina
Dear Ms. Jones
D EC 1 2 2007
The purpose of letter is to request a convening of a Mitigation Bank Review Team meeting for
the proposed Six Mile Creek Tributary Stream and Wetland Mitigation Bank. The proposed bank
is located in Mecklenburg County, North Carolina and has previously been submitted as part of
the NC Ecosystem Enhancement Program for Catawba Basin 03-08-88 (RFP #16-D06032-A)
The intent is to revisit the site with an MBRT to present an alternative to the actions described in
a prior submittal titled Sixmile Creek Tributary Stream and Wetland Restoration Project (March
24, 2007). While we believe the prior proposal is technically sound, we have concluded that less
invasive treatment can yield equivalent ecological values. Namely, the prior proposal called for
intensive stream restoration and surface manipulation (micro-topography). Our proposal is to
enhance vegetation and stabilize existing reaches of stream. Added value would also result from
the installation of a fore-bay and or level spreader structure that will result in sheet flow through
the wetland and eliminate an existing by-pass ditch which directly discharges stormwater to
Sixmile Creek.
The proposed wetland enhancement is equivalent in value to restoration and works to move the
existing wetlands toward a higher value climax forest in a more certain fashion. Our proposal is
to plant the site with bottomland wetland tree species and then to annually mow invasive
softwood species. Unlike classic restoration sites we believe it necessary to actively manage and
monitor the site for 7 years so that we can ensure that the mast producing hardwood trees will not
be shaded out by less desirable softwood species (Left to natural succession, the site would be
dominated by Sweetgum, Green Ashe and Red Maple). Further, though the site has been
determined to have wetland hydrology it is obvious that the cut-off ditch was installed to reduce
wetland hydrology to establish pastureland. We believe that it is appropriate to request
enhancement ratios approaching 1 to 1 for the 28 acres of wetlands since we will be restoring the
natural hydrology and enhancing forested conditions.
The necessary stream enhancement will can be achieved with profile and dimension
modifications that ensure that the stream continues to function in an appropriate manner. Based
on our observations we believe that appropriately spaced log vanes and plantings will achieve the
necessary stability; currently, isolated segments of instability result from the unregulated
stormflows. Currently, one main tributary enters the wetland area and branches into three minor
Sparta Office
3674 Pine Swamp Road
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tributaries. Each stream segment will be stabilized in situ resulting in approximately 4000 linear
feet of stream work.
Key to the success of the site will be the design and construction of the forebay and level spreader
structures that will reduce scour velocities while the site recovers from the restorative work.
Forthcoming detailed site surveys will determine the elevation of necessary for the level spreader;
currently, the spreader is projected to be constructed parallel to the existing by-pass ditch in high-
ground.
The bank proponents will review and likely accept the most current release schedule in effect
upon approval of the bank. In the interim, the bank proponents have reviewed the standard Credit
Release Schedule adopted by the Corps of Engineers, Wilmington District and propose the
schedule presented below which has been modified to reflect a 7 year monitoring plan for the
wetland component.
• 10% after first year, if interim success measures are met (total 25%):
• 10% after second year; if interim success measures are met (total 35%);
• 10% after third year; if interim success measures are met (total 45%);
• 15% after fourth year; if interim success measures are met (total 60%);
• 15% after fifth year, if interim success measures are met (total 75%);
• 12.5% after sixth year, if interim success measures are met (total 87.5%);
• 12.5% after seventh year, if the bank site meets the overall objectives and Success
Criteria set forth in the mitigation plan (total 100%).
The bank proponents have reviewed the Wilmington District Process for Preservation of
Mitigation Property and finds that all mechanisms appear attainable; final assessment will need to
be made by the proponents counsel.
We have opted to submit this letter without a copy of the prior proposal in hopes to reduce
excessive printing. The prior proposal includes all appropriate mapping and site documentation.
This proposal calls for the elimination of the intensive restoration. Please let me know if you
need another copy of the document.
st regards,
(hris Huysman
336 / 406-0906
Cc: Ms. Susan Yates, Centex Homes

Six Mile Creek Tributary Stream and Wetland Mitigation Bank
Summary Sheet
Goals:
• Restore a bottomland hardwood forest with attendant small stream
Functions:
• Improve flood attenuation
• Improve riparian dispersal corridors
Endangered Species:
• Carolina Heelsplitter habitat will improve
Wetland Component (28 acres):
1. Vegetation:
¦ Hardwood species comprised of mast producing trees
¦ 20% cap on any one species of planted hardwood
¦ Existing wetland vegetation will be maintained
¦ Survival of 260 stems per acre at year 7
2. Soils:
• Hydric soils present. within the site
• Soils will not be disturbed but for planting
3. Hydrology:
• Existing hydrology supports a wetland
• Target 12% to 25% annual hydrology
4. Site Management:
• Annual bush-hogging and mowing in dry summer months
• Annual manual control of invasive species
Stream Component (4000 linear feet)
1. Bank Stabilization:
• Fabric and root wads to stabilize sloughing banks
• Willow staking
2. Grade Control
• Log vanes to maintain grade
• Rock Vanes to maintain grade
Proposed Ratios:
• 1 to 1 for all wetland work
0 1 to 1 for all stream work