The Montlake Report

The final report has been completed.

The following questions, raised primarily by the Laurelhurst community, became the focus of the investigation:

• Is the weight of the landfill moving peat and garbage into Union Bay?
• Is the leachate from the landfill contributing to the Eurasian water milfoil problem?
• Is the leachate from the landfill degrading Union Bay’s water quality?
• How would an earthquake affect the Montlake Landfill?
• Is gas escaping from the landfill?
• Was the landfill closed according to regulations in effect at the time?
• Has the landfill caused the depth of Union Bay to change?

The findings of the effort include:

1. In 1959, dikes were placed around and within the landfill to stop lateral movement into Union Bay. Since 1959, there is no evidence to suggest the weight of the landfill cover moves peat or garbage into the bay.

2. Once milfoil is established, as in Union Bay, nutrients added to the bay from urban storm water runoff and landfill leachate do not influence the colonization or growth rate of milfoil.

3. The water quality data obtained to date, shown in Table 4, when compared to State Water Quality Standards (WAC 173-201A), show high levels of lead, silver, pH and fecal coliform. There is no evidence at this time to link these occurrences to the landfill leachate.

4. During a major earthquake, liquefaction may occur within the boundary of the landfill. Structures built on the landfill on pilings, reaching below the peat layer, should not be affected.

5. Methane gas is escaping from the landfill area, but in such small quantities that it does not pose a health concern or combustion hazard.

6. The landfill was closed according to the guidance available at the time.

7. The depth changes occurring in Union Bay can be attributed to the measured rate of natural sedimentation in this area.

After reviewing these results, the following recommendations were made by the work group:

1. Long-Term Testing or Monitoring

• Aerial photos of the Montlake landfill should be taken biennially to monitor University property abutting the Union Bay shoreline. The aerial photos should be analyzed by the Center of Urban Horticulture, and any unusual or significant observation should be reported to the Environmental Health and Safety Department.
• The University should participate, with appropriate agencies, such as the Seattle-King County Department of Public Health and the Washington State Department of Ecology, in the development of a plan to determine any future impacts of the landfill on surface water quality in Union Bay.
• A plan should be developed and implemented by Facilities Services and the Environmental Health and Safety Department, with input from Capital Projects, to assure that a long-term monitoring program is in place for tracking both settlement points and methane, with methane mitigation being part of standard procedures at the site. Such requirements should be incorporated into the Facilities Design Information (FDI) Manual.

2. Clean-Up Activities

• Since federal, state and local agencies have assessed the site and found that it presents no apparent environmental or public health hazard requiring additional closure activities, and based on the data obtained to date, there is no evidence to suggest that it is necessary to make any physical changes or undertake clean-up activities at the Montlake Landfill site at this time.

3. Practices and Procedures for Future Use of the Site

• The Engineering Services Department, the Environmental Health and Safety Department, and the Capital Projects Office should develop and implement an operational policy and management plan regarding grades at the landfill site that recognizes the dynamics of the landfill, and its maintenance requirements. This should be incorporated into the FDI Manual.
• The Capital Projects Office, with input from the Center for Urban Horticulture and the Environmental Health and Safety Department, should develop and implement procedures for construction on the Montlake Landfill site. This should be incorporated into the FDI Manual.

4. Other Recommendations

• In conjunction with the Washington State Department of Ecology and other appropriate agencies, the University should provide technical expertise in the planning activities regarding sediment quality in Union and Portage Bays.
• The University Real Estate Office and Engineering Services Department should monitor implementation of the Ravenna Creek Daylighting Project and assure that the landfill site is adequately protected.
• The University Relations Office and the Environmental Health and Safety Department should be added to the mailing list for information regarding city and county activities, regarding the regional waste water service plan and storm water issues.
• In conjunction with state-wide storm water management planning, the University Engineering Services should participate in the development of a storm water management plan for developed portions on the landfill site.