Stabilization of Unfinished Dam Structure of The Columbia Dam and Reservoir Project

TENNESSEE VALLEY AUTHORITY

Stabilization of Unfinished Dam Structure of The Columbia Dam and

Reservoir Project

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 1500 to 1508) and TVA's

implementing procedures. TVA has decided to implement the dam site

stabilization Option 2 identified in its Final Environmental Impact

Statement (EIS), Use Of Lands Acquired For The Columbia Dam Component

Of The Duck River Project. The Final EIS was made available to the

public in April 1999. A Notice of Availability of the Final EIS was

published in the Federal Register on April 16, 1999.

The Final EIS also analyzed various uses of the property acquired

for the Columbia Project. TVA has not yet made a final decision on the

use of these properties, but expects to decide this soon. When the land

use decision is made, another Record of Decision will be issued.

Although the dam structure is located on project property, stabilizing

the existing dam structure will have no effect on the land use

decision. TVA has determined that the two actions are independent of

each other.

FOR FURTHER INFORMATION CONTACT: Linda B. Oxendine, Senior NEPA

Specialist, Environmental Management, Tennessee Valley Authority, 400

West Summit Hill Drive, WT 8C, Knoxville, Tennessee 37902-1499;

telephone (423) 632-3440 or e-mail [email protected].

SUPPLEMENTARY INFORMATION: In 1968, TVA proposed the Duck River Project

that involved the construction of two dams and reservoirs on the Duck

River in middle Tennessee, south of Nashville. As proposed, one dam was

to be built at River Mile 248 near Normandy and the other at River Mile

136 near Columbia. Congress began appropriating money for the Duck

River Project in December 1969. Construction of Normandy Dam and

Reservoir began in June 1972 and was completed in 1976. Construction of

the Columbia Dam and Reservoir was begun in August 1973 but was halted

in 1983 because of the potential to jeopardize the continued existence

of several endangered mussel species within the Duck River.

In 1995, after efforts to transplant endangered mussels to other

stream reaches failed, TVA decided the Columbia Dam Project could not

be completed. Accordingly, TVA proposed to address future use of the

lands acquired for the project and what should be done about the

unfinished dam structure.

The Columbia Project lands are located in the Duck River watershed

between the city of Columbia (on the west) and U.S. Route 431,

Lewisburg-Franklin Pike (on the east), in Maury County, Tennessee. The

reach of the Duck River included in this study extends from

approximately River Mile 130, in Columbia, upstream to River Mile 165,

at Carpenters Bridge, 3 kilometers (2 air miles) west of U.S. Route

431.

When construction of Columbia Dam was halted in 1983, the Columbia

Project was about 45 percent complete. The concrete portion of the dam

was about 90 percent complete and the earth-filled section was about 60

percent complete. The river had been diverted through a 600-meter

(2000-foot) long constructed channel located along the east side of the

work site (the diversion channel) and a dike had been built to keep

normal stream flow out of the construction site. Approximately 46

percent of the land required for the reservoir (5200 of 11,140 hectares

[12,800 of 27,500 acres]) had been acquired, and approximately half of

the 72 kilometers (45 miles) of roads affected by the reservoir had

been relocated.

On February 25, 1995, TVA issued a Notice of Intent to prepare an

EIS on alternatives for use of lands acquired for the Columbia Project.

The Tennessee Duck River Development Agency, the U.S. Army Corps of

Engineers, and the U.S. Fish and Wildlife Service decided to cooperate

in the preparation of this EIS. A public scoping meeting was held at

Culleoka School near the Project site on April 18, 1995. The Notice of

Availability of the Draft EIS was published on January 6, 1997. The

public and interested agencies were invited to submit written comments

on the draft or to attend a public meeting on January 27, 1997 at

Columbia Senior High School.

TVA received a total of 2,890 separate sets of comments which

included input from over 4,600 individuals, three federal agencies,

four state agencies, six identified county and local governmental

agencies, and over 20 other organizations. The comments indicated that

most people and agencies want the Columbia Project lands to be

available for a variety of public uses and little or none of this land

used for industrial, commercial, or residential development. Only 43

comments were received about the existing dam structure and what should

be done about it. Comments were mixed, but most supported

implementation of Option 2, stabilization of the dam with a lower

profile. The Notice of Availability of the Final EIS was published on

April 16, 1999.

[[Page 28857]]

Alternatives Considered

To address the effects of the existing dam structure, construction

dike, and diversion channel on the river and its flow, three dam site

stabilization options were evaluated. Under Option 1--Maintain Current

Status of the Dam Structures, TVA would remove or minimize possible

safety and environmental hazards on and around the dam and diversion

channel site. Under Option 2--Stabilize Existing Flood Profile, TVA

would modify the existing concrete and earthen components of the dam to

stabilize the present control on flood flows. The concrete and earthen

portions of the dam would be demolished and reshaped at a lower

elevation to maintain existing upstream flood elevations and preserve

downstream flood benefits. Under Option 3--Restore Original Hydraulic

Conditions, TVA would remove enough of the concrete and earthen

structures at the dam site to reestablish pre-construction hydraulic

conditions along this part of the river. Option 2 was identified as

TVA's preferred alternative.

Decision

TVA has decided to implement Option 2 because this would stabilize

flood elevations at their current levels, address public safety

concerns, and avoid substantial additional construction in the river.

Option 1 would not address public safety concerns as effectively as

Option 2. Under Option 1, the existing dam structure would be left

largely intact and in place and have a continuing effect on the visual

setting of the area. Option 3 would fully address public safety

concerns and return the river to its pre-construction hydraulic level,

but completely removing the dam structure would increase downstream

flood elevations and have required considerable more work in the river

with associated environmental impacts.

Environmentally Preferable Alternative

Except for aesthetic impacts, TVA has concluded that Option 1 is

the environmentally preferred alternative because it would minimize

potential adverse impacts to the pond and fringe wetlands which exist

adjacent to the concrete part of the dam. However, Option 2 would more

effectively address public safety concerns at the dam site. Under

Option 2, the shape and height of the modified dam would also have less

of a visual impact on the landscape. Although Option 2 could involve

some work in the river, TVA has determined that the potential

environmental impacts of Option 2 will be insignificant.

Environmental Mitigation

Standard construction, demolition, and best management practices

would be followed in all aspects of the dam stabilization project to

minimize noise, erosion, dust, and other potential impacts. Disturbed

areas will be seeded and planted with native vegetation to help

stabilize the site and to promote the re-establishment of the natural

ecosystem.

Dated: May 17, 1999.

Ruben O. Hernandez,

Acting Executive Vice President, River System Operations and

Environment.

[FR Doc. 99-13534 Filed 5-26-99; 8:45 am]

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