Tuesday, September 28,1999
WF West High School Commons
342 S.W. 16th
Chehalis, Wa. 98532

Wednesday, September 29,1999
Rochester High School Commons
19800 Carper Road SW
Rochester, Wa. 98579

Introduction

This fact sheet provides information about the Centralia-Chehalis Flood Damage Reduction Project Study and invites public comment on the U.S. Army Corps of Engineers (Corps) scoping of issues for the preparation of an Environmental Impact Statement (EIS). The cities of Centralia and Chehalis have been subject to repeated flooding for many years. This flooding has caused extensive damage to private and public property and the occasional closure of Interstate Highway 5 and other critical local highways and roads. The road closures have resulted in economic losses as well as disrupting emergency response actions by local governments. Long-term development throughout the Chehalis River basin has also harmed stream habitat functions of the Chehalis River and its tributaries. This has placed high pressure on the remaining habitat resources to support sustainable fish and wildlife resources. It is likely that losses of wetlands, riparian areas, and back channels have also contributed to increased flooding in the area.

Purpose of Project Study

The purpose of the Centralia-Chehalis Flood Damage Reduction Project Study is to evaluate ways to reduce flood hazards to the cities of Centralia and Chehalis and the adjacent urban areas and to improve fish and wildlife habitat in the area where it is possible and appropriate. Flood hazards are defined as significant damage to existing structures or facilities, high risk to life, and closures of important roadways.

Past Study - Skookumchuck Dam Modification Project.

In June of 1984 the Corps completed a report that recommended Congress authorize the modification of the private dam on the Skookumchuck River to provide flood storage. This would reduce flood damages downstream in the Skookumchuck valley, the town of Bucoda, and the city of Centralia. Subsequently, Congress in Section 401 (a) of the 1986 Water Resources Development Act (Public Law 99-662) authorized the Corps to construct the "works of improvement" that were recommended in the 1984 report. The Corps began work on design studies in February 1988 with the City of Centralia as the project sponsor. Work continued through 1990, when further project design work was stopped, because the Corps found that the project was not economically justified. The useful information developed during the design process was provided the local governments in a Wrap-up Report in May 1992.

Recent Lewis County Study Activities.

Following the severe 1996 floods, public interest in flood damage prevention significantly increased. Lewis County took the lead in 1997 by establishing a countywide Flood Control Zone District. Lewis County contracted with a consultant for studies to identify possible changes to the Corps' 1984 proposal that could result in a potentially economically justified project. The County wanted a community-based alternative to the Washington Department of Transportation's (WDOT) proposal for improvements to Interstate Highway 5 (1-5). The WDOT's proposal included raising the 1-5 grade near Centralia and Chehalis by up to 12 feet. Lewis County feared that this proposal would increase flooding hazards both in the area and downstream. Instead. Lewis County wanted to explore ways to provide comprehensive flood, relief without raising 1-5.

In May of 1998, Lewis County completed a "Pre-Feasibility Analysis of Alternatives" report which described a plan that appeared to be economically justified and warranted further consideration. This plan was further refined in their November 1998 "Draft Interim Report' and included modification of Skookumchuck Dam combined with overbank excavation near Centralia and flood bypass measures near Chehalis.

In July of 1998, Lewis County requested that the Corps resume design work on the originally authorized project for Skookumchuck Dam, with the county as the local sponsor. However, Lewis County requested that the Corps consider their alternative plan to form a more complete flood damage reduction project for the Centralia-Chehalis urban area. The Corps resumed work on the project in a partnership with Lewis County to explore flood damage reduction measures.

Why must an EIS be prepared?

The Corps has determined that they need to prepare an EIS because of the potential for flood damage reduction actions to impact environmental resources, including impacts to the human environment. The Corps and Lewis County have identified several areas that require thorough evaluation. These include impacts to wetlands, fish and wildlife habitat, and cultural and historical resources as well as potential increases in downstream flooding and impacts to water quality. This effort is part of the requirements under the National Environmental Policy Act (NEPA). NEPA provides for public involvement at various steps in the environmental review process particularly when a federal agency (like the Corps) prepares an EIS. Opportunities for public involvement exist during scoping and public review of a Draft EIS. The first step is to go through the public scoping process.

What is the EIS public scoping process?

Scoping is a public process designed to determine the range of issues to be addressed in the EIS. Scoping occurs as early as possible after a federal agency (in this case, the Corps) makes a decision to prepare an EIS. It is an open process intended to obtain the views of other agencies and the public regarding what should be addressed in the EIS. The Corps published a Notice of Intent to Prepare an EIS on September 9th in the Federal Register. This began our scoping process. We invite both written comments and participation in our public scoping meetings. The scoping of an EIS includes gathering information on the types of impacts we should evaluate and the range of suitable alternatives to solve the study problem. We have identified some issues in our evaluation and we have also developed a preliminary list of alternatives. We anticipate that the scoping process will identify additional issues and alternatives.

What significant issues have been identified so far?

Based on our preliminary review of public and private concerns to date, we have identified (in the list below) the issues that Will require in-depth analysis in the EIS. We encourage you to let us know if there are other issues that we should address or if you know of information sources that will assist us in our analysis.

• Flooding characteristics, which includes any potential to increase flood damages elsewhere in the basin and impacts from erosion or sedimentation.
• Impacts to fish and wildlife habitat.
• Impacts to wetlands.
• Impacts to riparian areas.
• Impacts to cultural and historical resources.
• Impacts social and economic resources.
• Transportation.
• Hazardous materials in the project area.

What specific environmental studies have been identified to date?

The Corps and Lewis County have identified (list below) the major environmental studies we will be pursuing in the coming year. Most of the identified studies are intended to establish baseline conditions for our assessment of potential impacts.

Fisheries Survey. We will review the existing information on fish distribution and use in the Chehalis River and its tributaries. We will also conduct field surveys to verify instream habitats and fish use of the Skookumchuck River and fish use of portions of the Chehalis River during spawning.

Wetland Inventory. We will prepare a comprehensive wetland inventory based on current information sources and field surveys.

Riparian Area Inventory. We will prepare a comprehensive riparian area inventory based on current information sources and field surveys.

Cultural and Historical Resource Survey. We will review existing information and conduct a field investigation in cooperation with the Chehalis Indian Tribe and the Washington State Historic Preservation Office to identify important historical and cultural resources.

Environmental Restoration Opportunities. In cooperation with State and Federal resource agencies, the WDOT, the Chehalis Indian Tribe, and other interested parties, we will identify potential restoration opportunities that may be incorporated into the final project. These restoration efforts may be in addition to any mitigation requirements for unavoidable adverse impacts from the final project.

What alternatives will be considered in the EIS?

The Corps and Lewis County have identified the initial alternatives listed below to identify appropriate studies required. As the study continues, these alternatives may change, other alternatives may be identified, or alternatives may be combined to form different alternatives.

No Action. Allow current conditions and programs to remain as currently planned.

Authorized Project. The project identified in the Corps' 1984 report that would modify Skookumchuck Dam to provide flood storage.

Lewis County Alternative. The Lewis County plan referenced earlier that consists of three major elements: (1) modification of Skookumchuck Dam to provide flood storage; (2) overbank excavation near Centralia; and (3) flood bypass measures near the City of Chehalis.

Chehalis Indian Tribe Alternative. The Chehalis Indian Tribe suggested a plan that would consist of a series of flow restriction structures. These structures would be strategically located on the mainstem and/or tributaries of the Chehalis River. These would temporarily store floodwater in selected areas of the existing floodplain to reduce flood peaks downstream.. This alternative would not interfere with fish passage during non-flood flows. Some possible sites include the Chehalis River near Mellen Street, Salzer Creek, the Chehalis River downstream of the South Fork, the lower South Fork, and the Chehalis River upstream of the South Fork.

Levee Alternative. This alternative would consist of a levee system to protect Bucoda, Centralia, Chehalis, and the immediate urban areas.

Non-Structural Alternative Measures. This alternative would include such measures as flood warning system improvements, structure relocation, structure floodproofing, structure raising, bridge/road/railroad modifications, etc

What is the purpose of the public scoping meetings?

The Corps and Lewis County will be holding two public meetings to hear from the public about their issues and concerns regarding the Centralia-Chehalis Flood Damage Reduction Study. We are specifically interested in comments and opinions about the study itself, the range of alternatives, issues and information about natural, cultural, and historical resources, and the environmental studies that we have currently proposed. Meeting participants are encouraged to provide verbal and/or written comments during the meeting. We will also accept written comments throughout the study period. However, to be most useful to us, we would appreciate if the written comments were submitted by October 15, 1999. Please send your written comments to:

U.S. Army Corps of Engineers
Kathleen Kunz, Environmental Coordinator
PO Box 3755
Seattle Washington 98124-3755
kathleen.s.kunz@nwsO2.usace.army.mil

Will there be other opportunities to provide public input during the study?

We will accept comments any time during the study period. We will hold workshops periodically throughout the study period to update the public on our status. The workshops will be announced in the local newspapers and other media upon their scheduling. We will also make copies of the Draft Environmental Impact Statement available for public review and comment when it is prepared.

What technical studies are currently anticipated to be part of the study?

The Corps and Lewis County have identified (list below) major technical studies to provide information to be used in the EIS.

Mapping. The existing Thurston County 2-foot contour (CI) interval topographic mapping will be used. New topographic mapping (2' Cl) will be prepared for the Chehalis River (Cedarville - Pe Ell), Lincoln Creek, Skookumchuck River, Hanaford valley, Newaukum River, Sterns Creek, and South Fork Chehalis River. New 1'Cl mapping will be prepared for the Skookumchuck Dam. About 100 new river sections will be obtained.

Hydrology. Past hydrologic analyses will be updated and discharge values developed for the 2-, 10-, 25-, 50-, 100-, 200-, 500-year and larger events. Reservoir operation options will be investigated regarding fishery impacts, river sedimentation, water supply, and reservoir temperature. Probable Maximum Flood and Standard Project Flood analyses will be -updated using HMR57.

Hydraulic Analysis. The existing hydraulic computer model will be updated throughout its extent and expanded to cover segments of the Black River, Lincoln Creek, Hanaford valley, and South Fork Chehalis valley. An updated analysis of FEMA Floodplain and Floodway maps will be prepared for the FEMA detailed map area. The model will be used to identify the "without-project" condition and to identify effects and impacts of potential flood damage reduction measures. The sediment regime of the rivers will be evaluated to determine impacts on the cost of operation of various alternatives. Hydraulic design of dam features and other hydraulic structures will be undertaken.

Engineering, Design, and Cost Estimates. ED&C studies will be performed to establish conceptual designs for alternative measures and elements. Further work will develop selected alternatives for comparison and evaluation. Detailed design will be developed for the final alternatives, including mitigation and restoration elements, to be included in the EIS.

Geotechnical Studies. For Skookumchuck Dam, geotechnical effort will include a site-specific ground motion study, exploration beneath the dam's downstream berm to determine liquefaction susceptibility of dam foundation silt and alluvium, and a seismic analysis of embankment stability based on dynamic loading methods. Rock core drilling will be conducted at proposed modified structures or features. For floodplain measures, geotechnical work will include field investigations to physically characterize materials to be excavated, stability of cut/fill slopes, erosion potential, permeability, seepage, and potential borrow and materials sources.

HTRW Analysis. Lands potentially needed for alternatives will be reviewed and sites with potential contamination identified. Site investigations will be conducted, as necessary, for project lands.

Economic Analysis. A flood damage appraisal will be developed to determine the existing condition flood damages, including a damage survey and floodplain inventory. Alternative measures will be evaluated to determine possible benefits and a risk-based economic analysis undertaken for the final alternatives.

Real Estate Studies. Rights-of-entry will be acquired during the study as necessary for mapping, design, geotechnical, HTRW, cultural resources, and environmental studies. A gross appraisal of project land cost will be developed, including any necessary relocations, for inclusion in the final alternative cost estimates.

This page created and maintained by Chehalis River Council
Send comments or questions to the: Chehalis River Council