The history of wetland replication is mixed. Scientific reviews
conclude that for the most part replications fail to reproduce the
range of values – in quantity and quality – of the wetlands
they are intended to replace, in particular, difficulties in replicating
proper hydrological conditions in a consistent and enduring fashion
seem to be a major source of the problem.
The Commission shall strongly discourage any plan that requires
wetland replication.
In those rare instances where replication is approved by the
Commission the following conditions must be met:
A.
The replicated wetland must be constructed in full and conditionally
approved prior to construction of any structures. At a minimum the
replicated wetland must reproduce all the values and functions of
the original wetland as determined by the Commission. The Commission
may require that additional values and functions be incorporated into
the replication design.
B.
In circumstances where replacement of specific functions and values
would require substantial amounts of time before being completely
replicated (for example, those provided by large mature trees) the
Commission may require additional compensation of area, functions,
values, etc. beyond those required in other sections of this chapter
and its regulations.
D.
A qualified wetland scientist, employed by the applicant, shall be
required by the Commission during the construction of the wetland
replication area. The credentials of the wetland scientist shall be
submitted to the Commission for approval prior to the start of construction.
E.
Siltation barriers shall be placed around the proposed wetland replication
area prior to start of construction.
F.
Prior to the start of wetland construction detailed measurements
of the depth of the soil O and A horizons within the wetland to be
lost during construction shall be conducted. The project shall use
this information to determine the suitability of these horizons for
reuse in the replication area and to calculate the need for additional
soil materials. The top 12 inches of soil from the original wetland
must be transplanted with soil structure- especially lamination and
density profile- intact to the replication area. This is intended
to preserve plant, invertebrate and planktonic communities of the
wetland and inhibit the blossoming of invasive species.
G.
Soil materials to be reused (from the wetland to be lost during construction)
shall be removed and placed in the prepared replication area within
one day. If this is not possible, these soils shall be stockpiled
for the minimum amount of time feasible and kept loosely covered and
moist at all times. Each day any soils are stockpiled the project
manager shall notify the Commission in writing of the stockpiling,
the volume of soils stockpiled, the reason therefore, and the expected
duration of the stockpiling. The notification shall contain a certification
signed by the wetland scientist that s/he has inspected the stockpile
that day and that it is loosely covered and moist.
H.
The proposed replication area shall be excavated to a depth of one
foot below the proposed final grade, as specified in the specification
and plans submitted as part of the application and referred to in
the order of conditions (OOC). The subsoil within the replication
area shall be examined by the wetland scientist to determine whether
it is fine-extured (fine sandy loam or finer, as defined by NRCS standards).
If the subsoil is coarse-textured, it shall be replaced with fine-textured
material to allow for the development of a capillary fringe between
the groundwater and the soil surface.
I.
Following placement of topsoil a minimum of 48 hours shall pass prior
to planting of wetland vegetation to allow for rebound of buried or
compacted peat. The final grade shall be adjusted as necessary.
J.
The wetland scientist shall visit the replication area weekly following
planting and seeding for the duration of the first growing season
to determine the need for irrigation and additional fertilization
and to inform the site contractor of these requirements.
K.
Erosion control structures shall be removed upon stabilization of
the replication area to allow free circulation of water between the
wetland replication area and the adjacent natural wetland
L.
The wetland scientist shall inspect the wetland replication area
twice each year during late spring and during the mid- to late summer
of the first two full growing seasons. A written report shall be submitted
to the Commission at the end of each growing season.
