Executive Summary
February 1999

This report was prepared pursuant to Resolution A-96-02 and Appendix G of the MTP which were adopted July 11, 1996 by the Puget Sound Regional Council General Assembly.

Background
This report fulfills one of the provisions of the Regional Council's Resolution A-96-02, requiring a review of land use plans for areas affected by significant aviation noise levels from Sea-Tac International Airport. The analysis reviewed the comprehensive plans for the following communities: Burien, Des Moines, Federal Way, Kent, Normandy Park, SeaTac, Seattle, Tukwila, and King County. After outlining the regional, state, and federal mandates for compatible land use planning, the report then describes the issue of land use compatibility around airports and the methodology and findings of the land use plan analysis. After Section J of the full report, there are six colored map exhibits depicting noise sensitive facility locations and planned land uses for all or portions of communities in the vicinity of Sea-Tac International Airport. The appendices to this report include supporting data from the analysis and excerpts from local comprehensive plans relevant to this study.

Mandates
The Regional Council's Resolution A-96-02 amended the region's Metropolitan Transportation Plan in July 1996, and instructed the Regional Council to conduct an initial review of land use plans for areas that are within the 65 Ldn contour around Sea-Tac Airport, and to provide annual reviews of future changes. This document reports on the initial findings of the analysis of land use plans and aviation noise levels as mandated in Resolution A-96-02. It also reports on recent land use plan amendments in communities around Sea-Tac Airport.

In addition, the State's Growth Management Act (GMA) as amended in 1996 now requires towns, cities, and counties to use their comprehensive plans and development regulations to discourage the siting of incompatible land uses adjacent to public use general aviation airports. This report, together with continuing coordination between the State, the Regional Council, and local land use planning agencies, is designed to provide information and technical guidance to local planners which will help to implement these provisions.

Methodology
The project objective was to evaluate existing and planned land uses in areas located within the 65 Ldn/DNL noise contour. This report uses the terms "Ldn" and "DNL" interchangeably. The Federal Aviation Administration's noise compatibility guidelines have changed over the past several years. Previously, the average day-night noise level designation was shown as "Ldn". The current method of designating this same day-night average noise level is shown as "DNL". The two designations are used interchangeably. Both noise levels are measured in "A" weighted noise scales, known more commonly as dBA, a measure of sound in decibels. "A" weighted noise scales are the most commonly used measurement for environmental noise because they most closely represent the way human ears perceive noise.

This report relies on airport noise and land use information respectively derived from the Port of Seattle and the communities surrounding the airport. The Port's official existing conditions (1994) and forecast future (2010) noise contours (as published in the Port of Seattle's Final Supplemental EIS for the Proposed Master Plan Update Development Actions at Seattle-Tacoma International Airport, dated May 1997) were obtained in digital form. These noise contours were integrated into the Regional Council's geographic information system for use in analyzing the land use plans.

The Final Supplemental EIS provided data on existing and forecast noise impacts on population and housing. In addition, the Final Supplemental EIS provided data for other noise-sensitive facilities, such as schools, churches, libraries, etc., which are not typically designated on community land use plan maps. These data provided additional background information for the land use plan analysis.

The comprehensive plans for communities in the vicinity of Sea-Tac Airport were collected and their land use plan data were analyzed. Land use designations from nine comprehensive plans were mapped using the Regional Council's computerized geographic information system (GIS). The resulting map is a consolidated land use map showing planned land uses for the communities affected by noise around Sea-Tac Airport. The dozens of land use categories contained in the consolidated map were collapsed into a workable list of eight categories which distinguished compatible from incompatible uses. These final eight categories were: low density residential, medium density residential, high density residential, commercial, mixed use, industrial, parks and open space, and other (agriculture, right-of-way, etc.). The U.S. Department of Transportation's Federal Aviation Administration (FAA) has developed guidelines identifying the relative compatibility and incompatibility of different land uses around airports. The FAA's compatible land use guidelines were used to separate compatible and non-compatible uses. Commercial, mixed use, industrial, parks and open space, and "other" are generally compatible with airport noise and were therefore excluded from the further impact analysis. The land use plan analysis then focused on the three remaining groups of uses that are low, medium, and high density residential land uses. Sea-Tac Airport noise contours were then overlaid on the land use plan map and the GIS database was used to calculate the extent of incompatible land uses (low, medium, and high density residential) inside the noise contours.

Results of Land Use Plan Analysis
Exhibits 3 and 4 of the full report show that significant effort has been made to plan for compatible land uses in areas most affected by the airport (areas within the 70 and 75 DNL noise contours). Large areas to the north and south of the airport have been planned for industrial, commercial, and park uses, reflecting a continuation of historical trends. In addition, the Port's acquisition program has removed significant numbers of homes from these areas.

In 1994, the total area within the airport's 65 DNL noise contour comprised 12.23 square miles, or 7,827 acres. The future (year 2010) 65 DNL noise contour (with the third runway) is projected to shrink to 7.68 square miles, or approximately 4,915 acres. This is largely due to the federally mandated phase out of older Stage 2 aircraft by the year 2000. The number of homes within these noise contours is predicted to fall from 13,620 in 1994 to 5,520 by the year 2010; resident population will fall from 31,800 in 1994 to 13,220 in the year 2010, a decrease of about 58%. These numbers include existing development and do not account for new development which could be built in the future according to currently adopted land use plans.

The analysis of land use plan data shows some 1,500 acres are planned for residential use within the projected year 2010 65 DNL noise contour. Using residential densities from the communities' land use plans, these areas could support up to 11,828 total housing units and a population of 28,328. The analysis shows that these community plans would allow a significant amount of potential new incompatible (residential) development within the future (smaller) noise contour. This development, if it occurs, could wipe out much of the gain achieved by phasing out Stage 2 aircraft.

As airport and airline actions reduce noise at the source, preventive efforts such as compatible land use planning are likely to become the major tool to address future airport noise. Cooperative land use planning has the potential to help prevent the development of incompatible uses, thus reducing potential future impacts associated with airport activity. The communities surrounding Sea-Tac Airport have made some recent progress in this regard.

Analysis done by the Port of Seattle [see Section F and Tables 2 and 4 herein] confirms that the predicted future reduction in the size of the noise contour will also benefit non-residential land uses near the airport. According to analysis conducted for the Final Supplemental EIS, the number of schools, churches, libraries, hospitals and nursing homes, and parks and recreation facilities affected by significant airport-related noise (defined as greater than 65 DNL) will decline from 77 to 35 after the removal of the older, noisier Stage 2 aircraft from the U.S. commercial airline fleet, which is mandated by January 1, 2000.

In order to realize the full benefits of the shrinking noise contour, this report recommends that public agencies with land use planning, zoning, and building permit authority should cooperate with residential developers, school districts, and other property owners and developers to minimize the construction of new noise-sensitive land uses within the 65 DNL noise contour. Agencies with such authority and others with interest in compatible land use planning have a growing arsenal of tools which can be used to improve compatibility between airports and neighboring communities. Several of these are discussed in Sections B (Mandates) and E (Compatible Land Use Planning Issues) of this report. In addition, the following briefly describes recent and current efforts to address this issue.

Progress Toward Improving Land Use Compatibility
The City of SeaTac amended its comprehensive plan, official zoning map, and zoning code in December 1997 to achieve consistency with the Regional Council's Metropolitan Transportation Plan (MTP) and to allow for the third runway at Sea-Tac Airport. The amendment specifically provides for compatible land uses in the "Westside Area" adjoining the third runway site. The plan amendment changed the future use of some 224 acres from residential to non-residential development, reducing the number of future residents exposed to airport noise above 65 DNL levels by some 1,964.

The City of Burien amended its plan in April 1998. While the amendment did not affect the land use plan map, several goals, objectives, policies, and supporting text related to airport expansion were revised or eliminated. The plan amendments related to: (1) the City Plan's failure to explicitly recognize that the airport may expand through the development of a third runway; and (2) provisions which allegedly purport to preclude the expansion of the airport in violation of RCW 36.70A.200 (Growth Management Act provisions regarding the siting of essential public facilities). The amended plan now states that if the third runway is built, additional plan amendments will likely be necessary to reduce the airport's impact on surrounding communities, with the intent of achieving improved land use compatibility.

In response to a challenge by the Port of Seattle to the Central Puget Sound Growth Management Hearings Board, the City of Des Moines adopted an amendment to its comprehensive plan on October 8, 1998. The plan amendment removed numerous policy statements (see Section I of this report) that expressed opposition to airport expansion and were therefore not in compliance with the region's adopted Metropolitan Transportation Plan (MTP). Since the adoption of the plan amendment the Port has dropped its challenge, the Growth Management Hearings Board has dismissed the case, and the Regional Council has certified the plan under its GMA authority.

The Washington State Department of Transportation (WSDOT) and Department of Community, Trade and Economic Development (DCTED) are coordinating with the Regional Council in clarifying and implementing the provisions of a 1996 state law (SSB-6422) which requires local, regional and state review of the relative compatibility of land uses around general aviation facilities. These agencies have developed procedural criteria for review and certification of comprehensive plans developed under GMA. The WSDOT Aviation Division is also expanding its Land Use Encroachment program and developing technical assistance guidelines to assist local planners.

The Regional Council is developing a handbook for local agency planners (Compatible Land Use Planning Issues for Communities Near Airports). In addition, the Regional Council has revised its comprehensive plan review and certification process to incorporate an analysis of compatible land uses. The intent of this review is threefold: (1) to alert local land use planning agencies about GMA requirements; (2) to initiate discussions between local agencies and the Regional Council; and (3) to help local agencies take steps to avoid future land use compatibility problems around airports.


For more information, contact Stephen Kiehl, skiehl@psrc.org, 206-971-3290
The full report is available from the Information Center, infoctr@psrc.org, 206-464-7532