Grand Junction Office; Floodplain/Wetlands Statement of Findings for Site Characterization Activities at the Uranium Mill Tailings Site Located Near Shiprock, NM

DEPARTMENT OF ENERGY

Grand Junction Office; Floodplain/Wetlands Statement of Findings

for Site Characterization Activities at the Uranium Mill Tailings Site

Located Near Shiprock, NM

AGENCY: Grand Junction Office, Department of Energy.

ACTION: Floodplain/wetlands statement of findings.

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SUMMARY: This Floodplain/Wetlands Statement of Findings is prepared

pursuant to Executive Orders 11990 and 11988 and 10 CFR Part 1022,

Compliance with Floodplain/Wetlands Environmental Review Requirements.

The U.S. Department of Energy (DOE) is proposing to conduct site

characterization activities at the Uranium Mill Tailings Site near

Shiprock, New Mexico. The purposes of the activities are to determine

the extent of ground water contamination and to investigate flow

patterns in the ground water system; this information will assist DOE

in selecting a ground water remediation strategy for the site in

accordance with 40 CFR 192, Health and Environmental Protection

Standards for Uranium and Thorium Mill Tailings. Portions of the

proposed field activities would occur on the 100-year floodplain of the

San Juan River and in a nearby wetland. Approximately 18,000 square

feet (0.4 acre) of the 100-year floodplain and approximately 120 square

feet (0.003 acre) of the wetland area would be temporarily disturbed by

these field activities. A floodplain/wetlands assessment was prepared

that described the effects, alternatives, and measures designed to

avoid or minimize potential harm to or within the affected floodplain/

wetlands. The assessment found that the proposed action would have

minimal temporary or long-term impacts on the floodplain and associated

wetland.

DATES: Written comments are due to the address below no later than

October 13, 1998.

ADDRESSES: Written comments should be addressed to Audrey Berry, U.S.

Department of Energy-Grand Junction Office, 2597 B3/4 Road, Grand

Junction, Colorado; or transmitted electronically by E-mail via

Internet to Audrey.B[email protected]; or by facsimile at (970)

248-6040.

FOR FURTHER INFORMATION ON THIS PROPOSED ACTION, CONTACT: Don Metzler,

Project Manager, U.S. Department of Energy, Grand Junction Office, 2597

B3/4 Road, Grand Junction, Colorado 81503, Telephone 1-970-248-7612 or

1-800-399-5618, E-mail Don.M[email protected].

FOR FURTHER INFORMATION ON GENERAL DOE FLOODPLAIN/WETLANDS

ENVIRONMENTAL REVIEW REQUIREMENTS, CONTACT: Carol M. Borgstrom,

Director, Office of NEPA Policy and Assistance (EH-42), U.S. Department

of Energy, 1000 Independence Avenue, SW, Washington, DC 20585, (202)

586-4600 or (800) 472-2756.

SUPPLEMENTARY INFORMATION:

Background

The Notice of Floodplain/Wetlands Involvement for the Shiprock site

characterization activities was published in the Federal Register on

June 23, 1998 (63 FR 34153). The Floodplain/Wetlands Assessment was

completed in August 1998.

Project Description

The Shiprock site is located on the Navajo Nation in northwestern

New Mexico, approximately 1 mile (1.6 kilometers) south of Shiprock,

New Mexico, and about 30 miles (48 kilometers) west of Farmington, New

Mexico. The proposed action would involve (1) installing monitoring

wells to characterize ground water quality and other hydrologic

properties, and (2) constructing a surface water distribution system

consisting of a 30-foot-long, 4-foot-high, concrete intake structure on

Bob Lee Wash; a connecting 6-inch diameter, 2,000-foot-long pipeline

along the upper limit of the 100-year floodplain; and a 1- to 2-foot

deep, gravel-filled infiltration trench underneath the last half of the

pipeline. Most of the pipeline would be outside the wetlands, in

higher-elevation areas. The intake structure would divert a portion of

the flow in Bob Lee Wash into the pipeline and infiltration trench and

increase ground water flow in the floodplain alluvial aquifer. The

purpose of the surface water distribution system would be to flush

ground water contaminants towards the San Juan River and decrease

contaminant concentrations within the aquifer. Features of the surface

water distribution system would be in place for two to three years.

Because contaminated ground water is present in the floodplain alluvial

aquifer, the monitoring wells and surface water distribution system

must be located on the floodplain.

Alternatives

No alternative sites or actions exist for the proposed

characterization activities; the only other alternative would be no

action. Under a no action alternative, no impact to the floodplain or

wetland would occur. The ground water contamination, however, would

remain in place, and no additional characterization would be performed.

Floodplain and Wetland Effects

Installation of the monitoring wells, pipeline, and infiltration

trench would directly affect approximately 18,000 square feet (0.4

acre) of floodplain. Present vegetation consists primarily of inland

saltgrass (Distichlis spicata) and salt cedar (Tamarix ramosissima).

The areas disturbed by installation activities would be more

susceptible to wind and water erosion until vegetation became

reestablished. None of the proposed characterization activities would

be expected to affect lives, property, or any natural and beneficial

floodplain values. In addition, the construction of an intake structure

across Bob Lee Wash would directly affect approximately 120 square feet

(0.003 acre) of wetland. This construction within a wetland would

require regulation under Section 404 of the Clean Water Act. The U.S.

Army, Corps of Engineers has been consulted and a Nationwide Permit

will be required before construction begins.

Diversion of water from Bob Lee Wash through the intake structure

and into the pipeline could potentially affect the downstream emergent

wetland over time by reducing the amount of water supplied by the wash.

Temporary displacement of birds, small mammals, and other wildlife in

adjacent areas may occur during installation of the intake structure

and the associated pipeline and trench. Wildlife use of the wetland

would be expected to return shortly after construction work is

complete. No threatened or endangered species would be affected.

Floodplain and Wetland Mitigation Measures

Potential adverse effects within floodplain and wetland areas would

be mitigated by (1) installing monitoring wells only in higher-

elevation areas (2) reseeding floodplain areas where vegetation has

been disturbed as a result of characterization activities (3) avoiding

wetland areas whenever possible by constructing most of the pipeline

and all of the infiltration trench outside wetlands (4) diverting a

minimal amount of flow from Bob Lee Wash (5) using access routes that

are well outside wetlands, and (6) monitoring emergent wetland

boundaries annually for the duration of the proposed activities to

ensure wetlands are not permanently reduced. With the implementation of

these mitigation measures, the proposed action would be protective of

the 100-

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year floodplain and associated wetland at the Shiprock site and would

conform to the Navajo Nation's floodplain protection standards.

Issued in Albuerque, N.M. on September 16, 1998.

Constance L. Soden,

Director, Environmental Protection Division, U.S. Department of Energy,

Albuquerque Operations Office.

[FR Doc. 98-25688 Filed 9-24-98; 8:45 am]

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