03-6910. National Nuclear Security Administration, Los Alamos Site Office; Floodplain Statement of Findings for the Fire Road Project at Los Alamos National Laboratory, Los Alamos, NM

AGENCY:

National Nuclear Security Administration, Los Alamos Site Office, Department of Energy.

ACTION:

Floodplain Statement of Findings.

SUMMARY:

This Floodplain Statement of Findings is for the construction of improvements to existing firebreaks and access roads into remote forested areas at Los Alamos National Laboratory (LANL) for the purpose of providing reliable access for fire fighting crews. The improvements will focus on changes to drainage crossings and improved roadbeds within floodplain areas. Improvements would be minor and would mostly consist of installing culverts and stabilizing roadbeds. These roads are limited use roads that are restricted to official access only. In accordance with 10 CFR part 1022, NNSA has prepared a floodplain/wetland assessment and will perform this proposed action in a manner so as to avoid or minimize potential harm to or within the affected floodplain.

FOR FURTHER INFORMATION CONTACT:

Elizabeth Withers, U.S. Department of Energy, National Nuclear Security Administration, Los Alamos Site Office, 528 35th Street, Los Alamos, NM 87544. Telephone [phone], facsimile [phone]; or electronic address: [e-mail]. For further information on General DOE Floodplain Environmental Review Requirements, contact: Carol M. Borgstrom, Director, Office of NEPA Policy and Compliance, EH-42, Department of Energy, 1000 Independence Avenue, SW., Washington DC 20585-0119. Telephone [phone] or [phone], facsimile [phone].

SUPPLEMENTARY INFORMATION:

After the May 2000 Cerro Grande Fire event, NNSA developed a Wildfire Hazard Reduction Program for LANL. This program includes the improvement of firebreaks (also known as “fuel brakes”) and fire roads for access to remote portions of LANL through the upgrade and maintenance of the existing fire road network. There are about 12 firebreaks and 40 fire roads at LANL that will be improved as part of this project (see the attached figure). These improvements will require the following: (1) Clearing each road of hazard trees (mostly these are dead or dying trees) to keep the road open and passable; (2) grading of the roads and realignment of sharp curves to improve drainage; (3) cut and fill of road areas where needed to accommodate heavy fire fighting equipment; and (4) installation of culverts only in areas where the substrate is unstable, so as to minimize the number of culverts requiring maintenance. Disturbed soil will be revegetated after work is completed. Firebreak and road improvements will commence in fiscal year 2003 and be completed over the next 9 months.

In accordance with DOE regulations for compliance with floodplain and wetlands environmental review requirements (10 CFR part 1022), NNSA prepared a floodplain/wetland assessment for this action. The NNSA published a Notice of Floodplain Involvement (volume 68, number 39). This notice announced that the floodplain/wetland assessment document was available for a 15-day review period at two public DOE reading rooms in Los Alamos and Albuquerque, New Mexico, and that copies of the document could be obtained by contacting Ms. Withers at the above address. No comments were received from the Federal Register notice on the proposed floodplain action.

Project Description: Implementing the proposed improvements to firebreaks and fire roads would allow the passage of emergency fire fighting vehicles into remote portions of LANL. Each road would be graded and drainage crossings would be improved. All of the drainage crossings on the roads in the project area receive intermittent flow during seasonal storms and spring runoff.

Hazard trees that impede emergency vehicle passage would first be removed. Drainages would be graded to existing channel depth or crossed with a culvert. Most of the drainages are composed of hard substrate, and would not need a culvert. Where the substrate is soft and unstable and where the channel is much deeper than the roadbed, a culvert would be installed. Because of the high maintenance costs associated with culvert crossings, this method of drainage improvement would be limited to the extent practicable.

All roads would be stabilized with drainage improvements. At appropriate locations, water bars and off-drains would be constructed in the improved road. Each of these drainage features would be stabilized with rock or erosion matting to prevent erosion. They would be built to temporarily impede flow without impounding water. This would reduce erosion and sediment transport into the streams. Steep slopes created by the road improvements would be rehabilitated using revegetation, soil stabilization mats, hydro mulching, and other soil stabilization methods, as appropriate. Fuel breaks would be treated the same as fire roads.

Alternatives: Alternative methods were considered for constructing improvements to the firebreaks and fire roads at LANL. A combination of methods were selected that would minimize the environmental impacts and be the least disruptive to existing environmental resources in the area.

Floodplain Impacts: The proposed action would have the potential for minimal impacts to the floodplain. Possible impacts of the proposed project on the floodplains would include movement or ponding of water within the project area and the subsequent displacement of sediment; however, these improvements are anticipated to improve existing conditions in the floodplain by correcting erosion problems with road crossings. Should a rain event occur during this activity, there may be some sediment movement down canyon because of the loosened condition of the soil from the clearing and construction activities.

Floodplain Mitigation: Impacts to the floodplain would be minimized by following Best Management Practices at the construction area (such as the placement of silt fences, straw bales or wattles, or wooden or rock structures to slow down water runoff and run-on at cleared sites). Post-construction reseeding and re-vegetation along the sides of the stream channel will minimize soil disturbance and reduce or prevent the potential for soil erosion. Specific local mitigation actions for each fire road are described in section 6.1 of the floodplain/wetland assessment.

No debris will be left at the work site. No vehicle maintenance or fueling would occur within 100 feet of the stream channel. Any sediment movement from the site would be short term and temporary.

Issued in Los Alamos, NM on March 17, 2003.

Ralph E. Erickson,

Manager, Department of Energy, National Nuclear Security Administration, Los Alamos Site Office.