3.0
Environmental Consequences of Restoration Actions and Alternatives
CERCLA, NEPA, and MEPA require the Trustees to assess and disclose the
potential effects of restoration alternatives. Chapter 3.0 discusses
the potential benefits and consequences of each alternative, and evaluates
each alternative according to the Criteria for Selection listed in table
1 (page 13) as a means of explaining why each alternative was not chosen
as the preferred alternative. Table 4 shows how each of the alternatives
was rated against the selection criteria of Table 1.
3.1 Effects of Alternative A: No Action
Under the no action alternative, injuries to groundwater, wetlands,
migratory birds and migratory fish and their habitats would be uncompensated.
Given sufficient time, natural processes should enable natural resources
and associated services to recover to pre-injury levels. However, the
time frame for such natural recovery has been estimated to be in terms
of decades. In addition, the increment of resources and associated services
lost to the public in the past and during the recovery period would not
be compensated. Further, no benefits would be realized from the settlement
with Charles George Landfill Inc. et al., and the obligations
of the consent decree would not be met. This alternative was not rated
against the selection criteria since under this alternative nothing would
change.
3.2 Effects of Alternative B: On-Site
Wetland Restoration
On-site restoration of wetlands would most proximally address the the
services lost due to contamination. However, on-site opportunities are
generally costly, and impractical or undesirable.
Sediment Capping
Capping of the sediments in Flint Pond Marsh, which would require one
to two feet of fill, would alter the bottom contours of the wetland causing
changes in wetland hydrology and associated plant communities. Considerable
time and effort would be required to revegetate capped areas. Short-term
irretrievable losses of wetland habitat would occur while remedial activities
were
being conducted. Long-term impacts may also result from the changes
in hydrology that arise from partially filling the wetland. This alternative
was rated LOW for most of the selection criteria. This alternative
would change the wetland to upland, rather than restore or replace the
resources
that were impacted. It was rated HIGH for proximity since it would
address the immediate location of impact. This would be a costly alternative
that would destroy wetland, therefore, it was rated LOW for cost effectiveness.
This alternative would not enhance the public’s use of the resources,
and therefore, was rated LOW for this criterion. It was rated MEDIUM
for ecological benefit to the public because it would isolate the contaminated
sediments but it would destroy the wetland. Further community involvement
would not be expected. Since this alternative would be simple to perform
it would be expected to have a HIGH likelyhood of success. The unnecessary
capping of wetland would not comply with applicable state and federal
wetland protection statutes, and is, therefore, rated LOW for meeting
applicable laws.
Table 4. Evaluation of alternatives using the
criteria for selecting restoration sites to compensate for ecological
injury caused by the Charles George Landfill (see Table 1).
| ALTERNATIVES |
CRITERIA FOR SELECTION |
| A |
B |
C |
D |
E |
F |
G |
H |
| A. No Action |
x |
x |
x |
x |
x |
x |
x |
x |
| B. On-Site Wetland Restor. |
|
|
|
|
|
|
|
|
| 1. Sediment capping |
L |
H |
L |
L |
M |
L |
H |
L |
| 2. Sediment removal |
M |
H |
L |
L |
M |
L |
L |
L |
| 3. Erosion control |
L |
H |
L |
L |
L |
L |
L |
L |
| 4. Wetland creation |
H |
H |
L |
M |
M |
L |
L |
M |
| 5. Mgmt. invasive plants |
H |
H |
? |
L |
H |
L |
L |
H |
| 6. Rt 3 runoff control |
|
|
|
|
|
|
|
|
| C. Off-Site Wetland Restor |
|
|
|
|
|
|
|
|
| 1. Brox Prop. on Flint Pond |
M |
H |
? |
H |
M |
H |
L |
H |
| 2. Sandpit on Groton Rd |
H |
L |
L |
H |
M |
H |
? |
H |
| 3. Sandpit on Red Gate Rd |
H |
H |
H |
M |
H |
M |
M |
M |
| 4. Brox Prop. by Town Highway Dept. |
H |
M |
L |
H |
M |
H |
L |
H |
| 5. Middle School Site |
H |
M |
M |
H |
M |
H |
L |
M |
| D. Acquisition of Property |
|
|
|
|
|
|
|
|
| 1. Brox Prop. on Flint Pond |
M |
H |
? |
H |
M |
H |
L |
H |
| 2. Regonini Properties |
L |
H |
? |
H |
M |
H |
H |
H |
| 3. Larter Property |
L |
H |
? |
H |
M |
H |
H |
H |
| 4. Elkareh Prop/Dunstable Rd |
L |
H |
? |
H |
M |
H |
H |
H |
| 5. Elkareh Prop/Flint Road |
L |
H |
? |
H |
M |
H |
H |
H |
| 6. Japp Property |
L |
M |
? |
H |
M |
H |
H |
H |
| 7. Larter Prop/Main St. |
L |
M |
? |
H |
M |
H |
H |
H |
| 8. Greene Property |
L |
L |
? |
L |
M |
H |
H |
H |
| 9. Bell Property |
L |
L |
? |
H |
M |
H |
H |
H |
| 10. Woodward Property |
L |
L |
? |
H |
M |
H |
H |
H |
| 11. O'Coin Property |
L |
L |
? |
H |
M |
H |
H |
H |
| E. On-Site Migratory Fish Restoration |
|
|
|
|
|
|
|
|
| 1. Fish passage on Flint Pond |
H |
H |
L |
H |
L |
M |
L |
H |
| 2. Repair of Flint Pond Dam |
M |
H |
? |
M |
M |
L |
H |
H |
| 3. Bank stabilization on Merrimack River |
L |
M |
L |
L |
L |
L |
M |
M |
| F. Off-Site Migratory Fish Restoration |
|
|
|
|
|
|
|
|
| 1. Fish passage on Shawsheen River |
M |
M |
L |
M |
M |
M |
L? |
H |
| 2. Fish passage on Concord River |
H |
M |
H |
H |
H |
M |
H |
H |
Sediment Removal
Sediment removal, or dredging wetland areas affected by contamination,
would likely result in increased injury to wetlands due to physical habitat
disturbance, particularly due to the removal of well developed wetland
soil and existing vegetation. Following sediment removal, new soil would
need to be brought in and the site revegetated. Losses in habitat value
would occur until the dredged areas recovered from remedial activities.
Dredging activities associated with sediment removal would also resuspend
contaminants and possibly increase contaminant loads in currently less
contaminated portions of the wetland. Finally, lowering contaminant levels
in the areas which exceeded sediment biological effect levels would require
significantly more funds than are currently available. At an estimated
cost of excavation and disposal of $1,040,245/acre (ERM 1994), restoration
of the 2.75 acres of the most contaminated sediments would cost approximately
$3,656,803 (HMM 1990).
This alternative was rated LOW for most of the selection criteria. It
was rated MEDIUM for the extent that it restores, replaces or enhances
the natural resources that were injured because, although the issue
of contaminated sediments would be resolved, the same mature, well-developed
wetland could not in reality be replaced. It was rated HIGH for proximity
to the injured resources since it would immediately address the location
of impact. This alternative would cost more money than the Trustee
Council
has available for restoration, therefore, it was rated LOW for cost
effectiveness. This alternative would not enhance the public’s
use or enjoyment of the resources, therefore, it was rated LOW for this
criterion. It
was rated MEDIUM for environmental benefit to the public since it would
remove the contaminated sediments but it would also severely impact
the integrity of the wetland. Community involvement would not be expected
with this alternative. Technically the project has a high likelihood
of success, however, it is not a viable project because the expected
costs are greater than the funds available, therefore it was rated
LOW
for this criterion. The unnecessary dredging of wetlands would not
comply with wetland protection statutes, therefore, this alternative
was rated
LOW for compliance with applicable laws.
It should be noted that EPA’s Record of Decision determined that
contamination of Dunstable Brook could warrant remediation. The sediments
of Dunstable Brook were retested as part of the 1995 Five-Year Review.
This round of testing indicated that environmental contaminants were
present and available for uptake by biota used for the testing. EPA
resampled the affected area in 1998 and found decreased concentrations
of cPAHs.
EPA recalculated the risk associated with the cPAH levels using revised
relative potency factors and determined that the sediments no longer
posed an unacceptable human health risk. Therefore, removal of sediments
was determined to be unnecessary.
Erosion Sediment Removal
Removal of sediments that eroded into wetlands adjacent to the landfill
due to the capping of the landfill would also likely result in increased
injury to the wetlands due to physical disturbance, especially since
the affected area has revegetated. With excavation carried out by heavy
equipment it would be difficult to limit sediment removal to just the
eroded sediments. Also, the affected areas have revegetated so the site
would have to revegetate again after the eroded sediments were removed.
This alternative was rated LOW for all of the criteria except it is located
at the area of impact so was rated HIGH for proximity to the area of
impact.
Wetland Creation
Conversion of uplands to wetlands is not feasible at the landfill site.
Roads and staging zones at the landfill are unavailable for wetland creation
opportunities due to the need to maintain their current functions. Although
there is upland adjacent to Flint Pond and Flint Pond Marsh, no sites
were found that are available for acquisition and that could technically
be converted to wetland (based on topography). Also, unless the upland
habitat is degraded (such as is the case with a sandpit), the upland
habitat is already serving important functions and there may not be a
net gain in ecological value in converting high quality upland habitat
to wetland. Upland buffers also serve adjacent wetland habitat by filtering
contaminants before they reach the wetlands and by providing wildlife
habitat. Some species of wildlife are specific to the upland/wetland
edge.
Conversion of uplands to wetlands would, therefore, result in irreversible
losses of habitat services associated with those uplands.
This alternative was given a HIGH rating for the degree to which it
could restore the injured resources since it would create additional
wetland habitat, and HIGH for proximity to the injured resources since
it would take place adjacent to the sites of impact. It was rated LOW
for cost effectiveness since wetland creation is typically very costly. It
was rated MEDIUM for public use since it should create more habitat for
wetland wildlife viewing or hunting. It was rated MEDIUM for ecological
benefit because it would create wetland habitat but possibly at the loss
of other valuable habitat. It was rated LOW for continued community involvement
as there would be no need or mechanism for this. It was rated LOW for
expected project success since no viable location was found, and creation
sites need to be chosen carefully if success is to be expected.
Management of Invasive Plants
(Common Reed (Phragmites australis) and Purple Loosestife (Lythrum
salicaria))
Wetland restoration through management of common reed and/or purple
loosestrife in Flint Pond Marsh or wetlands adjacent to the landfill
is not preferred as the primary alternative as it requires intensive
on-going management, and because efforts are not consistently successful.
Control measures for common reed in flooded situations such as Flint
Pond Marsh include hydroraking, cutting below the annual water line,
and herbicide application (glyphosate). However, none of these control
measures are considered a permanent cure, but rather are methods for
managing the spread of the species that may require on-going maintenance
(Tiner 1998). Glyphosate is a broad-spectrum herbicide, and if it is
not applied carefully, surrounding vegetation can be affected.
Chemical and physical control measures for purple loosestrife include
application of broad-spectrum herbicides, hand-pulling, and mowing. These
measures are intensive and expensive and relatively ineffective, particularly
for large stands of purple loosestrife. Biological control, with the
use of leaf-feeding beetles (Galerucella calmariensis and G.
pusilla) and a root-boring weevil (Hylobius transversovittatus)
is the only long-term strategy which has been recommended to reduce the
invasion of this exotic plant (Malecki et. al. 1993). Biological
control of purple loosestrife is now permitted in the Commonwealth of
Massachusetts, however, written documentation of long-term studies indicating
the best sites and methods are lacking. Therefore, the effort would be
somewhat experimental. It is known that beetles survive poorly in wetlands
that are persistently flooded as the beetles overwinter in the duff (surface
soil) in purple loosestrife stands (Janice Taylor, USFWS, pers.comm.).
Therefore, sites such as Flint Pond Marsh and one of the wetlands adjacent
to the Charles George Landfill would be poor candidates for biological
control of purple loosestrife. The small wetland adjacent to the landfill
and right next to Dunstable Road, is choked with purple loosestrife and
is not persistently flooded, and could, therefore, be a possible candidate
for biological control of purple loosestrife. However, this site is relatively
small (less than one acre), so only a small area of habitat would be
benefitted.
This alternative was rated HIGH for extent of restoration of injured
resources because this alternative would signficantly improve the habitat
in the areas that were injured. It was also rated HIGH for proximity
to the injured resources. It was rated MEDIUM for cost effectiveness
because of the cost of purchasing the equipment and because control of
invasive plants can require intensive labor to be successful. It was
rated HIGH for extent of ecological benefit to the public because it
should increase the wildlife use of the wetlands. It was also rated HIGH
for ecological benefit to the public for the same reason. It was rated
LOW for community involvement, with the exception of whomever would be
responsible for the long-term management. It was rated LOW for expected
success since success would require long-term intensive management. It
was HIGH for compliance with applicable laws.
Control of Runoff from Route
3 into Flint Pond Marsh
Residents around Flint Pond raised the question as to whether storm
runoff from Route 3, which is presently being directed to Flint Pond
Marsh, could be directed elsewhere. The Trustee Council does not have
any authority over Route 3, however, since planning for the Route 3 expansion
is presently occurring, an opportunity exists for the drainage to be
changed by the MassHighways. We are presently working with MassHighways
to determine the present plans for the Route 3 section through Tyngsborough.
However, we have been informed by the Massachusetts Department of Environmental
Protection that the Commonwealth requires that stormwater discharges
be treated, such as by a detention basin, before being discharged into
a natural waterbody. Also, the U.S. Fish and Wildlife Service serves
as an advisor to the U.S. Army Corps of Engineers on dredge and fill
permits, which will provide another avenue for encouraging MassHighways
to provide for discharging into detention basins before discharging into
Flint Pond. Since this is not really a restoration to be undertaken by
the Trustee Council it is not evaluated here in comparison to the other
alternatives.
3.3 Effects of Alternative C: Off-Site
Wetland Restoration
Off-site restoration of wetlands would compensate for many of the wetland
services lost as a result of contamination from the Site. Wetland creation
and/or enhancement near the sites impacted would provide additional wetland
habitat to species of migratory birds that use wetlands. In addition,
restoration efforts would also create or improve habitat for other wildlife
species and provide other wetland functions. However, the Trustee Council
was unable to find a site with good restoration potential that was available
for acquisition. The sites that were found are described and their evaluations
discussed (see Tables 1 and 4 on pages 13 and 33, respectively).
Brox Property on Flint Pond
This site offers limited opportunity for wetland restoration. The site
is disturbed by historical excavation but the areas that were dug to
the water table seem to be developing into productive wetland areas on
their own. The upland portion remains relatively denuded and could benefit
from the spreading of topsoil and revegetation. However, the upland would
remain upland as it is too far above the water table to allow for wetland
creation. Restoration of upland habitat would help support adjacent wetland
habitat and Flint Pond. Acquisition of this property would protect it
from potential future development. However, based on two conversations
with a representative for the landowner, it does not appear that the
landowner is interested in selling this property to the Trustee Council.
This alternative was rated MEDIUM for the extent to which it would restore
the injured resources because it would provide a buffer for Flint Pond
and adjacent wetlands, however, no wetlands would be created, restored,
or enhanced. It was given a HIGH rating for proximity to injured resources
since it is located adjacent to Flint Pond. Cost effectiveness is difficult
to evaluate without having an appraisal of the property. It was given
a HIGH rating for the extent that it would enhance the public’s
ability to use and enjoy the public resource since it would likely
be open for public use. It was given a MEDIUM rating for its environmental
benefit to the public; it was not given a HIGH rating because of the
lack of wetland restoration potential. It was given a HIGH rating for
community involvement because public access would be expected. It was
given a low rating for expectation of success since the owner does
not
appear to be willing to sell. This alternative would be expected to
be in compliance with applicable laws.
Sandpit on Groton Road
This site was considered a potential restoration site because the upland
was degraded (sandpit) and because there was a small pond of water on
the site suggesting that a portion of the site has a shallow water table.
However, the amount of wetland that could be created on the site is unknown
and would require an extensive and expensive investigation to determine.
Also, a large area of upland would need to be restored to a more productive
state to make the wetland restoration worthwhile. This site is relatively
far from the area of impact. The landowner could not be reached.
This site was rated HIGH for the extent to which it could replace the
injured resources because theoretically the types of wetlands injured
could be re-created and, therefore, increase the amount of habitat available
to the animals that use those wetland habitats. It was given a LOW rating
for the proximity to the injured resources. Cost effectiveness is difficult
to evaluate without an appraisal of the property but this alternative
would be expected to be costly. It was given a HIGH rating for public
use since it would be expected to be open to the public. It was given
a MEDIUM rating for environmental benefit because it is a relatively
long distance from the area of impact and possibly only a small area
of wetland could be created. Community involvement would be expected
to continue since the property would be open for public use. The potential
for technical success can not be evaluated without further study, however,
the fact that the landowner could not be contacted makes the project
unviable. This project would be in compliance with applicable laws.
Sandpit on Red Gate Rd/ Dunstable
Rd/ and Brookview Circle
This site is considered to have good restoration potential because it
has access to water; the site was excavated to the water table in some
locations and the site is adjacent to Dunstable Brook. The site is an
old sandpit, so quality habitat would not be altered to create wetland.
Although some of the site has developed into wetland already, the topography
is flat and lacks diversity, and the ponded areas lack depth. A berm
between the site and Dunstable Brook impedes water exchange. Much of
the site is vegetated with invasive plants: purple loosestrife chokes
part of the site; a discrete stand of Phragmites seems to be expanding;
Japanese knotweed is growing on the berm; and sugar locust trees are
distributed throughout the site. The southeast corner of the site remains
upland sandpit with relatively little vegetative development. Therefore,
there is ample opportunity to improve the site. The challenge for this
restoration is that the site is broken up into at least eight different
small parcels with different owners. All of the landowners would have
to be interested in participating for the project to be viable. The Trustee
Council was interested enough in this project to hire the Natural Resources
Conservation Service (NRCS) to survey the microtopography of the site
so that a draft map of what the restoration might look like could be
developed. Once this draft restoration map was developed and shown to
the landowners, some of them decided not to participate, deeming this
restoration alternative inviable.
This project was rated HIGH for the extent it restores, replaces, or
enhances the resources injured since it would create wetland habitat
of a type similar to what was injured. It was rated HIGH for proximity
to the injured resources since Dunstable Brook was impacted a short
distance upstream. It was rated HIGH for cost effectiveness since the
site was
already excavated, so the creation effort was essentially already started,
and it could be partnered with a land protection alternative, the Regonini
Properties. It was rated MEDIUM for the extent the alternative would
enhance the public’s ability to use, enjoy or benefit from the
natural resources. This is because the site should attract more wildlife
to the area which would be enjoyed by the immediate landowners. It
would also create more habitat by increasing the quality of the habitat,
and
the additional wildlife produced would also move to adjacent habitats.
But this site would essentially be closed to the general public because
it is ringed by private residences. It was rated HIGH for environmental
benefit to the public because it would partially replace resources
that were lost. It was rated MEDIUM for community involvement because
there
was potential for long-term active management by the landholder and
adjacent landowners but the site would not be open to the general public.
The
project was rated MEDIUM for compliance with applicable laws because
some existing low quality wetland would be altered to create higher
quality wetland, which could be controversial.
Brox Property on Kendall Road
behind Highway Department
This property was considered as a restoration site because the upland
is degraded sandpit and there is a small pond on the property which indicates
possible access to groundwater. Theoretically, it would be possible to
create wetland around the perimeter of the pond, but groundwater studies
would be required to determine exactly where the groundwater table is
around the pond. In addition to creating wetland, an extensive amount
of upland would need to be restored around the wetland for the habitat
to be of value. A representative for the landowner indicated through
a phone conversation that the owner was unlikely to be interested in
selling this property.
This alternative was rated HIGH for the extent to which it would restore,
replace, or enhance the natural resources that were injured since habitat
similar to what was injured would be created. It was rated MEDIUM for
proximity to injured resources since it is separated from Flint Pond
by Kendall Road. It was rated LOW for cost-effectiveness because the
effort, including the preliminary testing, would be costly and potentially
only a small area of wetland would be created. It was rated HIGH for
the extent that it would enhance public use because once the property
was acquired it would be open for public use. It was rated MEDIUM for
environmental benefit to the public because it would create similar habitat
to what was injured but possibly only a small area. It was rated HIGH
for continued public involvement since the property would be open for
public use. It was rated LOW for the extent to which the project would
be successful because a lot more needs to be known about the water table,
and the landowner appears to be unwilling to sell. Compliance with applicable
laws would be expected to be high.
Middle School Site on Westford
Road
This site was considered a potential restoration site because it includes
an old sandpit adjacent to Bridge Meadow Brook. Some of the sandpit
was excavated to the water table and wetland vegetation has developed.
There
are two small areas, each about an acre in size: one on the north side
of the brook and one on the south side of the brook. The berms along
the banks of the brook could be breached to provide water to enhance
wetlands areas and to help absorb flood waters. Construction of a middle
school is planned for the area, making the enhanced wetland areas potentially “living
laboratories”. However, recent development of housing around
the wetlands, in conjunction with the nearby construction of a school
limits
the amount of surrounding upland available as habitat to support the
wetland areas. The Town of Tyngsborough has been hesitant to give approval
to the enhancements because the entire property may be needed for the
school.
This alternative was rated HIGH for the extent to which it restores,
replaces, or enhances the natural resources that were injured. It was
rated MEDIUM for proximity to injured resources because it is not on
Flint Pond or Dunstable Brook. It was rated MEDIUM for cost effectiveness
because it is a relatively small area that would be enhanced and the
habitat around it is compromised by development. It was rated HIGH
for the extent to which it would enhance public use. It was rated MEDIUM
for environmental benefit to the public because it could serve as a “living
laboratory” for students at the middle school and would help absorb
flood waters, however, the enhanced areas would be relatively small.
It was rated HIGH for the extent it provides an oportunity for community
involvement to continue because it could be used as a “living lab” for
the school. It was rated LOW for the extent to which the project would
be expected to be successful because, although it is technically feasible,
the Town has not given an approval to the project because the land
may be needed for The school.
3.4 Effects of Alternative D: Acquisition
of Equivalent Resources
Acquisition of equivalent resources is generally selected only after
in-kind restoration projects have been evaluated because it results
in preservation of existing resources rather than in replacement of lost
resources. This is reflected in Criterion A of the evaluation of alternatives
(Table 3 on page 25), which is “the extent to which the alternative
restores, replaces, or enhances the natural resources that were injured”.
All of the acquisition alternatives were rated as LOW for this criterion
except the Brox Property, which has good potential for active restoration.
Since the acquisition alternatives were mostly rated the same for the
criteria in Table 3, they are not discussed and compared in this section.
Table 4 provides a new list of criteria for evaluating and comparing
acquisition alternatives. This table is discussed in section 2.5.
3.5 Effects of Alternative E: On-Site
Migratory Fish Restoration
Fish
Passage for Flint Pond: Migratory fish restoration through construction
of fish passage at the two Flint Pond dams would involve a relatively
high cost for a relatively small gain. Fish passage facilities would
allow alewife and blueback herring, and American eel to migrate into
Flint Pond. Herring may not have historically entered this tributary
to the Merrimack River because it may not have provided the relatively
deep, quiet water environments, prior to impounding, needed for spawning.
The present condition includes the impounded Flint Pond, which could
provide an opportunity for herring spawning. However, habitat is limited.
Although the pond provides potentially 61 acres of spawning habitat,
there is no additional habitat upstream, and the shallow depths of
Flint Pond may cause the water temperatures to be too warm for juvenile
herring. Further, the pond appears to be silting in, as evidenced by
an increase in floating-leaved aquatic plants (primarily lilypads).
Given the relatively high price tag of constructing fish passage at
this location, estimated to be approximately $200,000, this alternative
may not be cost-effective.
This alternative was rated HIGH for the extent that it restores, replaces,
or enhances the natural resources that were injured because it would
enhance the fishery that may have been injured. It was rated HIGH for
proximity to injured resources since the work would take place at the
site of injury. It was rated LOW for cost-effectiveness because of
the high cost of the work and the relatively low likelyhood of success.
It
was rated MEDIUM for the extent to which the alternative will enhance
the public’s ability to use, enjoy, or benefit from the resource
because the project would theoretically bring herring into Flint Pond,
but success of reproduction may be limited by high water temperatures.
It was rated LOW for ecological benefit to the public because the success
of the project is expected to be LOW. It was rated MEDIUM for the extent
that it provides for continued community involvement because the fish
ladder would require some on-going maintenance. It was rated LOW for
the extent to which the project is expected to be successful. It was
rated HIGH for compliance with applicable laws.
Stabilization
of Bank Erosion in the Merrimack River through Tyngsborough:
Abatement of bank erosion on the Merrimack River does not appear to
be cost-effective. There are numerous locations on the Merrimack River
in Tyngsborough and towns downstream with eroding, sloughing banks. The
causes of the erosion range from natural processes to land development
causing destabilization of the river banks. Excessive erosion results
in degradation of aquatic habitat due to increased turbidity in the water
column and siltation of the substrate. Placement of riprap is the most
common method used to stabilize banks in rivers with significant ice
scour, which is expected in a large river such as the Merrimack. Riprap
is relatively costly, averaging $40 per linear foot. Riprap can also
contribute to degradation of the river system by increasing water velocities
which can aggravate erosion both upstream and downstream.
This alternative was rated LOW for the extent to which it restores,
replaces, or enhances the natural resources that were injured. Although
reducing erosion and, thus, turbidity would be beneficial to aquatic
resources, it is unlikely that enough areas could be stabilized that
turbidity could be reduced to a meaningful extent. Also, if riprap
is used, it often degrades the aquatic habitat as much as it enhances
it.
It was rated MEDIUM for the proximity to injured resources because
the areas of erosion extend up and down the Merrimack River. It was rated
LOW for cost-effectiveness because bank stabilization in a large river
is expensive and a lot of bank would need to be stabilized before turbidity
would be reduced to a meaningful degree. It was rated LOW for the extent
to which the alternative will enhance the public’s ability to
use, enjoy, or benefit from the natural resources that were injured
because
stabilizing a few banks will not likely increase the number of fish
in the river. It was rated LOW for extent of environmental benefit
to the
public because a lot of bank would need to be stabilized before there
was a meaningful reduction in turbidity, and the riprap can do damage
to the river system. It was rated LOW for continued ommunity involvement.
It was rated MEDIUM for likelihood of success because technically the
stabilization is possible in some locations, but the overall goal of
improving habitat for migratory fish may not be met. It was rated MEDIUM
for compliance with applicable laws because bank stabilization is frequently
permitted when property is in danger but, otherwise, permitting can
be difficult.
3.6 Effects of Alternative F: Off-Site
Migratory Fish Restoration
Off-site restoration for migratory fish would compensate for injuries
that possibly occurred due to the release of contamination from the Site
into the Merrimack River. Since migratory fish move up and down through
the watershed, an increase in reproduction in one portion of the watershed
should ultimately contribute to a higher population throughout the watershed.
A proposal to survey the habitat of the Shawsheen River was received
by the Trustee Council. Herring have been observed in the lowermost parts
of the Shawsheen, which suggests that the upstream portions of the river
should be investigated for their potential to provide habitat for migratory
fish. However, without further assessment of the suitability of the habitat
in the river, it is difficult to judge whether money would be well spent
restoring migratory fish to this river system. The Trustee Council received
another proposal to provide fish passage, and stocking and monitoring
of shad and herring in the Concord River. It is already known that quality
habitat is present in the upstream reaches of the Concord/Sudbury/Assabet
Rivers. Therefore, since it is known that quality habitat exists in the
Concord River, and conversely, since little is known about the suitability
of the habitat in the Shawsheen River for migratory fish, it appears
that restoration of migratory fish in the Concord River would be more
prudent.
Restoration of historical fish runs would be consistent with on-going
federal and state activities. Organizations involved with these activities
in Massachusetts include: the Massachusetts Department of Fisheries,
Wildlife, and Environmental Law Enforcement, the Massachusetts Division
of Marine Fisheries, the Massachusetts Riverways Program, the U.S. Fish
and Wildlife Service, the U.S. Army Corps of Engineers, as well as numerous
non-profit organizations. Any dam work would be conducted during low-flow
periods to minimize impacts on the river, however, the overall impact
of constructing a fishway would be positive. No impacts on threatened
and endangered species is expected. The construction of a fishway at
the Talbot Mills Dam would be consistent with the Massachusetts Wetlands
Protection Act (310 CMR 10.57 10.00), the Clean Water Act (Section 404),
and the Rivers and Harbors Act (Section 10).
The Shawsheen River alternative was rated MEDIUM for the extent to which
it restores, replaces, or enhances the natural resources that were
injured because of the unknown probability of success. It was rated MEDIUM
for
proximity to the injured resources because, although it is located
well outside of Tyngsborough, the same population of migratory fish would
be addressed. It was rated LOW for cost-effectiveness because of the
questions about the projects potential for success. It was rated MEDIUM
for the extent the alternative would enhance the public’s ability
to use, enjoy, or benefit from the resource because if the project
was successful a fishery would be restored to the river for the public
to
utilize. However, since the amount of habitat available is in question
it is not clear how much of a run is possible. It was rated MEDIUM
for environmental benefit to the public for the same reasons as the
previous
criterion. It was rated MEDIUM for the extent that community involvement
can continue because volunteers are often used to assist in monitoring
fish returns and maintaining fish ladders. It was rated LOW for the
extent the project is expected to be successful because of the many
unknowns.
It was rated HIGH for compliance with applicable laws.
The Concord River alternative was rated HIGH for extent to which the
alternative restores, replaces or enhances the natural resources that
were injured because it would restore runs of migratory fish to a large
area of historical habitat. It was rated MEDIUM for proximity to the
injured resources because, although it is located well outside of Tyngsborough
the same population of migratory fish would be addressed. It was rated
HIGH for cost effectiveness because the project is expected to be successful,
and if it is successful, a substantial run of migratory fish will be
restored to a large area of historical habitat. It was rated HIGH for
the extent to which it will enhance the public’s use of the resource
because a fishery will be restored to a substantial area of the Concord,
Sudbury, and Assabet Rivers, which will benefit the entire watershed.
It was rated HIGH for environmental benefit to the public for the same
reason as the previous criterion. It was rated MEDIUM for the extent
of continued community involvement because volunteers are often used
to monitor fish returns and maintain fish ladders. It was rated HIGH
for the likelihood of success because similar projects in other watersheds
have been successful, and because quality spawning and incubation habitat
has been documented in the system. It was rated HIGH for compliance
with applicable laws.
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