Facility Site ID: 7057711 Cleanup Site ID: 2220

  • Site Status

  • Awaiting Cleanup

Status

Olalla Landfill
Olalla Landfill

Kitsap County Public Works, Solid Waste Division is preparing a final Remedial Action Status Report that addresses Kitsap Public Health District and Ecology’s comments on the draft document. The final document will be posted on the electronic documents along with Ecology’s Opinion letter once complete.

Site Background

Olalla Landfill Site Map
Olalla Landfill Site Map

The landfill is in southern Kitsap County, east of Highway 16 and southwest of SE Burley-Olalla Road and Bandix Roads. The closed landfill consists of two adjoining areas: Phase I to the south and Phase II to the north

Olalla landfill began accepting waste in the late 1950s or early 1960s. Municipal solid waste was disposed in the Phase I area. Construction and demolition waste, and a small volume of septic waste, was disposed in the Phase II area.

The landfill closed in accordance with an approved Closure Plan in 1989. The Phase I Area has a two-foot thick compacted bentonite-amended, low-permeability soil cover to reduce infiltration. A passive landfill gas system of perforated pipes beneath the low-permeability cover connects to three passive landfill gas flares. The Phase II Area has a soil cover.

Kitsap County Public Works Solid Waste Division maintains and performs environmental monitoring at the Olalla Landfill.

Cleanup Activities

Water supply well sampling locations and results
Water supply well sampling locations and results

Cleanup activities began at the landfill because the concentrations of naturally-occurring metals (i.e., arsenic, iron, and manganese) and vinyl chloride exceeded the groundwater quality criteria in the upper aquifer downgradient (west) of the landfill. 

Kitsap County Public Works prepared a Remedial Investigation/Feasibility Study (Volume I and Volume II) in May 2014 and a Cleanup Action Plan in December 2014. The Cleanup Action Plan requires the monitored natural attenuation of contamination in the upper aquifer and land use controls. 

This upper aquifer is the source of drinking water for three residences west of Olalla Landfill (one adjacent to the landfill parcel on SW Burley Olalla Rd, one southwest of the site, and one west of the site on the other side of Olympic Drive SE). 

Offsite water wells were sampled in 2010 and 2011 during for the Remedial Investigation Report and in 2020 and 2021 for the Remedial Action Status Report. The sampling results are summarized below and shown in the attached table. 

  • The concentrations of arsenic and vinyl chloride were below the primary maximum contaminant levels for drinking water. Vinyl chloride was not detected.
  • The concentrations of iron and manganese slightly or nearly exceeded the secondary maximum contaminant levels for drinking water in water wells OW-3 (screened in the lower aquifer) and OW-4 (screened in the deep aquifer). The secondary maximum contaminant levels are based on aesthetic criteria for drinking water.

Regulating Agencies

Ecology’s Solid Waste Management Program oversees corrective action at the closed landfill in accordance with the state Model Toxics Control Act (MTCA) regulation (Chapter 70A.305 of the Revised Code of Washington and Chapter 173-340 of the WAC.).

Ecology develops regulations and guidelines and provides assistance to Kitsap Public Health District. Kitsap Public Health District regulates post-closure care at the closed municipal solid waste landfill under Chapter 173-304 WAC.

Learn How Ecology Is Protecting The Environment In Your Community

What's In My Neighborhood shows contamination cleanup sites in Washington state. Ecology encourages cleanup of these sites to protect the health of people, plants, and animals. Cleanups are projects that remove, treat, or contain potentially harmful substances.

Report An Environmental Issue

Northwest Region Office
Northwest Region Office
To report an environmental problem or concern, any time, day or night, use the online reporting form.

Counties: Island, King, Kitsap, San Juan, Skagit, Snohomish, and Whatcom
Email:
 nwroerts@ecy.wa.gov
Phone: 206-594-0000

Requesting Accommodation

Ecology is committed to providing people with disabilities access to information and services. To request an ADA accommodation, contact Ecology by phone at 360-407-6831 or email at ecyadacoordinator@ecy.wa.gov. For Washington Relay Service or TTY call 711 or 877-833-6341.  Visit Ecology’s website for more information.

​If you speak a non-English language, free language services are available.

Technical Reports 16
Document Title Document Date Document Type
Olalla Landfill - Opinion on the Remedial Action Status Report, Revision 2 (March 29, 2023) 4/25/2023 Site Specific Administrative Document - other (Administrative correspondence)
2022 Annual Monitoring Report, Olalla Landfill 3/31/2023 Groundwater Monitoring Report
Olalla Landfill - Remedial Action Status Report, Revision 2 3/29/2023 Performance/Confirmational Monitoring Plan or Report
Olalla Landfill - Annual Monitoring Report 2021 3/14/2022 Groundwater Monitoring Report
Olalla Landfill - Annual Monitoring Report 2020 3/1/2021 Groundwater Monitoring Report
Olalla Landfill - Annual Monitoring Report 2019 3/1/2020 Groundwater Monitoring Report
Olalla Landfill - Annual Monitoring Report 2018 3/1/2019 Groundwater Monitoring Report
Olalla Landfill - Annual Monitoring Report 2017 2/1/2018 Groundwater Monitoring Report
Olalla Landfill - Annual Monitoring Report 2016 3/1/2017 Groundwater Monitoring Report
Olalla Landfill - Compliance Monitoring Plan, Post Closure Monitoring Under the Olalla Landfill Cleanup Action Plan 3/17/2015 Sampling and Analysis Plan
Olalla Landfill - Independent Cleanup Action Plan 12/23/2014 Cleanup Action Plan
Olalla Landfill - Opinion on Draft Cleanup Action Plan 12/2/2014 Site Specific Administrative Document - other (Administrative correspondence)
Olalla Landfill - Opinion on Independent Remedial Investigation/Feasibility Study 9/5/2014 Site Specific Administrative Document - other (Administrative correspondence)
Olalla Landfill - Remedial Investigation/Feasibility Study Vol 1 of 2 5/1/2014 Remedial Investigation / Feasibility Study
Olalla Landfill - Remedial Investigation/Feasibility Study Vol 2 of 2 5/1/2014 Remedial Investigation / Feasibility Study
Olalla Landfill - Site Hazard Assessment 1/23/2008 Site Hazard Assessment Report
There may be more documents related to this site. To obtain documents not available electronically, you will need to make a public records request.

Places to see print documents

  • Solid Waste Program - Northwest Regional Office
    15700 Dayton Ave N
    Shoreline, 98133
    This location may only have print documents available during open comment periods.

Contaminants 8

Contaminant Type
Soil
Groundwater
Surface Water
Air
Sediment
Bedrock
Halogenated Organics - Halogenated Organics S C
Metals - Metals - Other S C
Non-Halogenated Organics - Petroleum Products-Unspecified S
Non-Halogenated Organics - Non-Halogenated Solvents B
Non-Halogenated Organics - Polycyclic Aromatic Hydrocarbons S
Other Contaminant - Conventional Contaminants, Organic S S
Other Contaminant - Conventional Contaminants, Inorganic S C
Metals - Arsenic S C
S
Suspected
C
Confirmed Above Cleanup Levels
B
Below Cleanup Levels
RA
Remediated-Above
RB
Remediated-Below
R
Remediated
This contaminant list was based on our best information at the time it was entered. It may not reflect current conditions at the site.