[Federal Register: September 14, 2007 (Volume 72, Number 178)]
[Notices]
[Page 52596-52598]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr14se07-84]
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TENNESSEE VALLEY AUTHORITY
Bear Creek Dam Leakage Resolution Project, Franklin County, AL
AGENCY: Tennessee Valley Authority (TVA).
ACTION: Issuance of Record of Decision.
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SUMMARY: This notice is provided in accordance with the Council on
Environmental Quality's regulations (40 CFR parts 1500 to 1508) and
TVA's procedures implementing the National
[[Page 52597]]
Environmental Policy Act. TVA has decided to implement Alternative 2--
Modify Dam and Maintain Summer Pool Level of 576 Feet, the preferred
alternative identified in its Final Environmental Impact Statement
(EIS), Bear Creek Dam Leakage Resolution Project.
FOR FURTHER INFORMATION CONTACT: Charles P. Nicholson, NEPA Policy
Program Manager, Environmental Stewardship and Policy, Tennessee Valley
Authority, 400 West Summit Hill Drive, WT 11B, Knoxville, Tennessee
37902-1401; telephone (865) 632-3582 or e-mail cpnicholson@tva.gov.
SUPPLEMENTARY INFORMATION: TVA completed Bear Creek Dam in 1969 at mile
74.6 on Bear Creek in Franklin County, Alabama. The dam and associated
reservoir are part of the Bear Creek Project authorized for the
purposes of flood control, recreation, and economic development,
including water supply. Excessive leakage of water has occurred through
the foundation of Bear Creek Dam since its completion and this
increases the risk of dam failure. TVA has unsuccessfully attempted
repairs on several occasions. The most recent of these repair efforts
was in 2004-2005; after TVA refilled the reservoir to its normal summer
pool level of 576 feet above sea level, excessive leakage continued.
Since then, TVA has operated the reservoir at a reduced summer pool
level of 568 feet as a precautionary measure to reduce the leakage and
provide a greater margin for flood management. However, following
periods of heavy rainfall, the reservoir level can rise, and the risk
of dam failure increases. TVA prepared this EIS to evaluate
alternatives for a long-term solution to the problem of excessive
leakage through Bear Creek Dam.
TVA published a Notice of Intent to prepare this EIS in the Federal
Register on June 2, 2006. A public scoping meeting was held on June 20,
2006 and attended by about 150 people. Scoping comments were received
from two federal agencies, four state agencies, and several
individuals. The Notice of Availability of the Draft EIS was published
in the Federal Register on June 1, 2007. TVA held a public meeting on
the Draft EIS on June 26, 2007 and accepted comments through July 16,
2007. Comments on the Draft EIS were received from three federal
agencies, one state agency, three local public water suppliers, and
three individuals. The Notice of Availability of the Final EIS was
published in the Federal Register on August 10, 2007.
Alternatives Considered
TVA identified four alternatives in the EIS
Under Alternative 1, the No Action Alternative, TVA would not
implement a long-term solution to the leakage problem and would attempt
to operate the dam at the originally-intended summer pool level of 576
feet. Normal winter pool would remain at 565 feet. Under this
alternative, TVA would implement new seasonal minimum flows from the
dam as recommended by the U.S. Fish and Wildlife Service to improve
habitat conditions for endangered species in Bear Creek downstream of
the dam. Adoption of Alternative 1 would not remedy the leakage
problem, and the dam would be at risk of failure, which would cause
downstream flood damage. Although this alternative differs from the
current interim operating regime, it better represents the historic
baseline conditions.
Under Alternative 2, Modify Dam and Maintain Summer Pool Level of
576 Feet, TVA would repair or rebuild the dam in place or immediately
downstream and restore the normal summer pool to 576 feet. TVA would
also implement the new seasonal minimum flows described above for
Alternative 1 and raise the normal winter pool by one foot to 566 feet.
The existing roadway across the dam would be returned to service
following dam repairs. Three sub-alternatives are considered under this
alternative. Alternative 2a is the construction of a roller-compacted
concrete structure at the downstream edge of the existing dam. This
structure would be keyed into the bedrock, and a cutoff wall would be
installed beneath the structure to prevent seepage. Alternative 2b is
the placement of additional earth fill on the downstream dam face and
the installation of a cutoff wall into bedrock on the downstream side
of the dam. Alternative 2c is the installation of a cutoff wall into
bedrock on the upstream dam face.
Under Alternative 3, Lower Dam and Maintain Summer Pool Level of
565 Feet, the existing dam would be partially removed and stabilized. A
grout curtain or cutoff wall would be installed within the dam and into
the underlying bedrock to prevent seepage under the dam. The existing
roadway across the dam would be rebuilt. The reservoir pool level would
be maintained at approximately 565 feet throughout the year.
Under Alternative 4, Remove Dam and Restore Former Creek Channel,
TVA would remove Bear Creek Dam and the reservoir would be eliminated.
The former creek channel would be dredged of excess sediment to
facilitate water flow. A bridge would be built to replace the existing
roadway over the dam.
Comments on the Final EIS
The U.S. Environmental Protection Agency (EPA) commented on the
final EIS. Their comments focused on potential effects to wetlands and
sought clarification of responses to previous EPA comments on the draft
EIS. Due to favorable hydrologic conditions, approximately 77 acres of
scrub-shrub, emergent, and aquatic bed wetlands have developed at
various locations around the reservoir fringe at the interim summer
pool elevation of 568 feet. None of these wetlands is forested. The
forested wetlands on Bear Creek Reservoir are confined to the heads of
coves where tributary streams enter the reservoir. The hydrology of
these areas depends on the tributary streams, and the forested wetlands
are generally unaffected by fluctuation in the reservoir level.
Forested/scrub-shrub wetlands also occur on flats associated with
Island Branch and further upstream. Based on the size of trees present,
these wetlands have persisted in this location for over 20 years and
would not be inundated when the reservoir is refilled. No forested
wetlands would be affected adversely under Alternatives 1 and 2.
Forested wetlands have not developed in the drawdown zone between
elevation 576 feet (normal summer pool) and 565 (normal winter pool)
because tree growth is inhibited by extended inundation during the
growing season.
Because they perform only minor wetland functions due to their
fringe nature and because traditionally accepted hydric soil
characteristics are not present, TVA does not consider these wetlands
to be jurisdictional wetlands in accordance with the Clean Water Act.
Accordingly, no compensatory mitigation is required to offset their
loss.
Bear Creek Reservoir is narrow with fairly steep, rocky banks and
few areas of overbank. Fringe wetlands are likely to become
reestablished along parts of the normal (576 foot) summer shoreline,
particularly in bottomland areas associated with tributaries, if the
reservoir were refilled under Alternative 1 or 2. Shoreline steepness
and the presence of adequate soil substrate are the primary factors
affecting wetland development at the current 568-foot summer pool level
and at the 576-foot normal summer pool elevation under Alternatives 1
and 2. Competition from exotic plants or animal life does not
[[Page 52598]]
appear to present any barrier to wetland establishment.
Much of the Bear Creek Reservoir shoreline has eroded since the
reservoir was filled in 1969, and rock outcrops and bluffs are common
along the shoreline. No critically eroding shoreline has been
identified. At the 576-foot elevation, shoreline vegetation present
prior to the 2005 emergency drawdown has not decreased. Refilling the
reservoir under Alternatives 1 and 2 is not expected to cause
additional erosion. Thus, establishment of shoreline buffers to prevent
erosion is neither feasible nor necessary.
Returning the reservoir to its original full summer pool is
expected to result in water quality conditions virtually identical to
the pre-2005 conditions. Most of the shoreline surrounding Bear Creek
Reservoir is undeveloped and forested. Runoff from upland areas enters
the reservoir primarily via tributary streams. The degree of upland
runoff filtered by wetlands is dependent on those wetlands present in
coves and associated with streams. These areas have not been affected
dramatically by changes in reservoir levels. Historically, low levels
of dissolved oxygen have occurred in the deeper portions of the
reservoir. Currently there are no plans to improve dissolved oxygen.
However, TVA will continue to monitor water quality on Bear Creek
Reservoir and would take remedial measures as necessary.
Decision
TVA has decided to implement Alternative 2, Modify Dam and Maintain
Summer Pool Level of 576 Feet. Under this alternative, the original
project objectives of flood control, recreation, economic development,
and water supply would be met. The new seasonal minimum flows would
improve conditions for endangered species downstream of the dam, and
the one-foot increase in the winter pool level would improve operating
conditions for the public water supply intake and treatment plant on
the reservoir.
Three alternative methods of repairing the dam are identified in
the EIS. TVA has selected Alternative 2a, the construction of a roller-
compacted concrete structure at the downstream edge of the existing
dam.
Environmentally Preferred Alternative
Alternative 2--Modify Dam and Maintain Summer Pool Level of 576
Feet is the environmentally preferred alternative. Implementation of
this alternative would afford a stable water supply source for the
Franklin County Water Service Authority and would restore water-based
recreational opportunities on Bear Creek Reservoir. Repair of the dam
under this alternative would provide increased flood protection to
downstream areas compared to the other alternatives. Operation of the
dam under Alternative 2 to provide target minimum flows would provide
improved water quality for three federally listed mussel species known
to occur downstream of Bear Creek Dam.
The potential environmental consequences of implementing any of the
three Alternative 2 repair methods are similar. However, Alternative
2a--Roller-Compacted Concrete Structure is preferable to the other two
methods in that it would most likely provide the best long-term
solution to the leakage problems. It would provide protection against
the probable maximum flood. The need for future construction
disturbance would be reduced under Alternative 2a.
Mitigation
Standard construction best management practices would be followed
in all aspects of the proposed repairs and construction to avoid or
minimize adverse environmental impacts. TVA would ensure that all
necessary permits are obtained from the appropriate regulatory agencies
and that permit requirements are met. TVA would ensure that all site
operations adhere to the requirements in each permit and would employ
all necessary actions to minimize environmental impacts. The following
non-routine measures would be implemented to reduce the potential for
adverse environmental effects:
Construction buffers would be delineated around any caves
within one-fourth mile of a construction area. The buffer for caves
would be 200 feet. Within this buffer, vegetation would not be cleared,
and vehicles or equipment would be restricted to existing roads.
TVA would increase patrols and monitoring of cultural
resources within the reservoir drawdown area until conditions are
stabilized or protected.
Archaeological surveys as required by the Memorandum of
Agreement between TVA and the Alabama State Historic Preservation
Officer will be conducted, and mitigation will be performed on any
sites or resources determined to be eligible for inclusion on the
National Register of Historic Places in accordance with the terms of
the Memorandum of Agreement.
Dated: September 10, 2007.
Janet C. Herrin,
Senior Vice President, River Operations.
[FR Doc. E7-18146 Filed 9-13-07; 8:45 am]
BILLING CODE 8120-08-P