20111003_Mitigation Plans_20101013

Turner Street Marsh Restoration Plan
R-3307, Highway 70 Improvements
Beaufort, Carteret County
Federal Aid Project No. STPNHF-70(43)
State Project No. 8.1162501
WBS No. 34528.1.1
October 13, 2010
The North Carolina Department of Transportation (NCDOT) will perform on-site
mitigation for impacts associated with R-3307. Improvements to US 70 from existing
four lanes at Radio Island to US 70 North of SR 1429 (Olga Road).
The mitigation site is located just north of the town of Beaufort along Turner Street
adjacent to Town Creek. The mitigation is proposed to restore 1.4 acres of salt marsh by
causeway removal along Turner Street. This mitigation will be used to offset the 1.1 acres
of impacts to salt marsh, at a 1:1 ratio, associated with TIP R-3307. The residual 0.3
acres of restoration will be retained by the NCDOT as on-site assets for future projects in
the area.
Existing Conditions
Turner Street is currently a two lane secondary road that crosses Town Creek
approximately 300 feet south of West Beaufort Road. Town Creek flows to the west
under Turner Street through four 60 ft. long, 95"x 67" corrugated aluminum pipes. To
the south of the crossing, a salt marsh wetland dominated by smooth cordgrass (Spm4ina
alternillora) runs along the both sides of the causeway and extends outward along Town
Creek.
The Environmental Assessment (EA) dated October 2004 and the Finding of No
Significant Impact (FONSI) dated August, 2006, for TIP R-3307, provide further details
concerning natural resource and roadway conditions.
Proposed Conditions
The mitigation site will consist of 1.4 acres of salt marsh restoration at the proposed
Turner Street Bridge. The NCDOT will remove the existing culverts and approximately
560 ft. of causeway. The causeway and any higher knolls within the right-of-way will be
graded to a target elevation of -0.2 ft ins]. This elevation is slightly higher than the mean
tide level and is within the range of elevations taken in the adjacent marsh. The
restoration area will be planted on three foot centers with smooth cordgrass.
The Natural Environment Unit shall be contacted to provide construction oversight to
ensure that the wetland mitigation area is constructed appropriately.
Monitoring
Target elevations will be verified during construction to ensure the restoration area
achieves the sane hydrologic regime as the adjacent salt marsh wetland.
The quantitative marsh vegetation monitoring will be accomplished in accordance with
the draft guidelines for "Site Monitoring Surveys for Emergent Marsh Mitigation",
established by the National Marine Fisheries Service. through the evaluation of randomly
distributed I square meter plots located by GPS within the site.
The vegetation component of the wetland site will be deemed successful if the following
criteria are met:
1. At year five, the average of all plots should have a scale value of 5 (>75%
vegetative cover) consisting of wetland herbaceous species, not including any
invasive species:
2. A minimum of 70% of the plots shall contain the target (planted) species.
NCDOT will perform the monitoring described above for 5 years or until the site is
deemed successful. The site will be protected in perpetuity and placed on the Natural
Environment Unit's Mitigation GeoDatabase.