Final Environmental Impact Report - Whittier Bridge/I-95 ...

Planting and Seeding
Whittier Bridge/I-95 Improvement Project FEIR
Chapter 1.0: Changes Since the Draft Environmental Impact Report and Resolution of Additional Issues
Wetland plantings will consist of woody species prevalent in nearby forested wetlands (red maple,
green ash, gray birch, black chokeberry [Photinia melanocarpa], highbush blueberry, silky dogwood
[Cornus racemosa] and winterberry) (Figure 1-13). Woody plantings will be relatively dense (15 feet
on center for trees, and 8 feet on center for shrubs) to establish a cover as soon as possible to
inhibit invasive species colonization. A wetland seed mix of early successional grasses and sedges
will be applied to stabilize the soils and to discourage invasive species colonization.
The steep slope of the upland will be reduced to a 3:1 slope, with steeper sideslopes near the edges
of the berm, and stabilized with a native conservation seed mix. Upland tree and shrub species will
be planted on the upland slope to further stabilize the slope and hasten reestablishment of early
successional forest. The species recommended, including gray birch, staghorn sumac (Rhus
typhina), American hazelnut (Corylus americana), bayberry (Myrica pennsylvanica) and sweet fern
(Comptonia peregrina), all occur in the project area and will likely succeed on the site. It is expected
that additional woody upland species will naturally recolonize the upland slope. The portion of the
sideslope that falls within 10 feet of the proposed Shared-Use Path will be seeded only to stabilize
the slope until the construction of the Shared-Use Path occurs.
Construction Access, Sequencing and Schedule
Construction of the wetland replication site will occur under close supervision of an experienced
Wetland Mitigation Specialist (environmental monitor), who will provide weekly site inspections at a
minimum, and be present for the initial stages of major components of the work. These include, at a
minimum: establishment of erosion controls prior to soil disturbance; inspection of proposed topsoil
for suitability and lack of invasive species; approval of subgrades and final grades prior to planting
and seeding; inspection of nursery stock prior to installation, planting and seeding; and removal of
erosion controls at project completion.
Construction site access to the Wetland H mitigation site will be obtained from the intersection of
Merrill Road and Elm Street (Route 110) via a temporary road that will be located mostly within the
alignment of the proposed Shared-Use Path. The Shared-Use Path will be constructed after
completion of the wetland replication area. All erosion control measures proposed for the affected
section of the Shared-Use Path will be installed in the initial construction stage of the wetland
replication area. During excavation of the wetland, grades will be maintained to prevent runoff from
disturbed substrates draining untreated into the wetland. Management techniques will include
multiple erosion control fences and starting excavation from the back of the site to reduce direct
runoff into the wetland.
Sequencing of construction at the Wetland H mitigation site will occur as follows:
Have wetland mitigation specialist approve topsoil composition and source, and nursery material;
Clear temporary construction access road of trees and establish erosion controls as necessary,
following route of Shared-Use Path where possible;
Prepare substrate surface as necessary to support equipment for construction;
Protect site from access by motorized recreational vehicles;
Install compost filter tubes, including orange snow fence around perimeter of grading area for
erosion and sedimentation control;
Clear mitigation site of woody material;
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