Pasco Landfill NPL Site
More Than 35,000 Drums Of Industrial Waste Removed
After more than 30 years of environmental investigation and cleanup, Ecology is announcing the removal of more than 35,000 drums of industrial waste from the Pasco Landfill Superfund site. The cleanup is a lasting solution that will end releases of hazardous substances to soil and groundwater from industrial waste that was buried 50 years ago.
Cleanup activities at the Pasco Landfill began in the early 2000s, and significant work has been completed at several industrial waste zones and municipal solid waste disposal areas within the site. The responsible parties began the waste removal work in Zone A of the landfill in fall 2020 under Ecology’s oversight, with all drums removed by early June 2022. In total, about 23,500 tons of waste were safely removed and hauled to out-of-state facilities designed to dispose of hazardous materials.
The drum removal work was done under a temporary structure with an air treatment system. Air quality was monitored during the cleanup action to ensure worker and community safety. After the waste was excavated, characterized, and separated by waste type, it was transported to disposal facilities in Grand View, Idaho, and Arlington, Oregon.
The Zone A waste removal work is being followed by thermal treatment of the remaining contaminated soil located below the former drum repository. The thermal treatment system started up in April 2024 and will operate for about a year, depending on treatment efficiency. Learn more about thermal treatment in our May 3, 2024, blog post.
Following thermal treatment, a final cover system will be placed on Zone A, and the site will continue to be restricted with fences, signs, and limitations on how the property is used.
Groundwater monitoring and the maintenance of landfill covers will continue beyond the completion of active cleanup. The groundwater protection area around part of east Pasco will stay in place until Ecology determines it is no longer necessary.
Cleanup timeline
- June 2025 and beyond: Construct final cover over Zone A after thermal treatment is finished. Monitor cleanup progress of entire site and maintain landfill covers and fences and signs around the site.
- April 2024 - May 2025: Operate in-situ thermal remediation (ISTR) system, which will remove and destroy remaining mobile contamination in Zone A. The ISTR system uses electricity to power heating rods buried underground to uniformly heat the contaminated soil to about 250°F by thermal conduction. The heaters are spaced at 12-foot intervals throughout the Zone A treatment area. Each heater location includes a vapor-recovery screen that draws steam and contaminants to a vapor treatment system.
In the treatment system, the vapor is condensed to remove water and heavier contaminants, which are stored in tanks in secondary containment to catch any leaks until they are treated or disposed offsite. Treated water that meets state standards is discharged to a nearby swale. Remaining contaminated vapor passes through the regenerative thermal oxidizer that was used to treat Zone A soil contamination prior to the drums being removed. The thermal oxidizer eliminates the vapor contaminants to the low levels required under an Ecology-issued air quality permit. - July 2022 - March 2024: Design and install thermal remediation system to treat remaining contaminated soil in Zone A.
- April 2021 - June 2022: Construction of the temporary structure over Zone A and its air-handling system were completed. Contractors moved the structure into six different positions to excavate, segregate, and characterize drums for offsite disposal.
- November 2020 - April 2021: The Zone A cover is removed, and the site is prepped for the drum removal. Over 200 rolloff boxes of municipal solid waste, almost 40 rolloff boxes of tires, and 18 rolloff boxes of hazardous waste were excavated and disposed off-site.
Información en Español
- Limpieza: Relleno Sanitario de Pasco comienza etapa final
- Más de 35,000 barriles de desechos industriales removidos del Pasco Landfill
- Preguntas Frecuentes: Limpieza del Relleno Sanitario de Pasco
- Borrador del Plan de Acción de Limpieza, acuerdos legales y documentos de la Ley de la Política Ambiental Estatal
Site Background
The Pasco Landfill is about 1.5 miles northeast of the City of Pasco, north of the intersection of Kahlotus Road with U.S. Highway 12. The landfill property covers nearly 200 acres and is surrounded by agriculture and commercial businesses. The Basin Disposal transfer station on Dietrich Road is at the southern end of the landfill. The landfill no longer accepts waste and is closed to the public. Gates, fencing, and signs restrict access to this active cleanup site.
The landfill opened in 1958. Waste was burned in trenches until 1971, when the site became a sanitary landfill. From 1972 to 1975, the landfill accepted industrial waste. Some was delivered in 55-gallon drums and disposed in two zones. The rest was delivered as bulk liquids that were placed into large evaporation lagoons.
The site was added to the U.S. Environmental Protection Agency’s National Priorities List (NPL) in 1990. The landfill closed in 2001.
The City of Pasco passed an ordinance in 2001 that defined a groundwater protection area around part of East Pasco that is over a plume of groundwater contaminated by the landfill. A restrictive covenant is in place that prohibits activities and land uses at the landfill that could expose people to contamination.
Waste zones
- The New Waste Landfill received municipal waste until closure in 2001. This area is not included in the current cleanup.
- The Municipal Solid Waste Landfill Area received household and commercial garbage until closure in 1993.
- The Balefill/Inert Waste Area received household waste and construction debris until closure in 1989. Garbage was compacted into bales, stacked, and buried.
- Industrial Waste was disposed in five zones:
- Zone A contained an estimated 35,000 55-gallon drums of solvent and paint sludges, cleaners, and other hazardous waste. The drums were removed and properly disposed off-site in 2022.
- Zone B contained nearly 5,000 drums of herbicide-manufacturing waste that were excavated and disposed offsite in 2002. In July 2019, Ecology granted a request for this zone to become its own cleanup site; see the Zone B section below for more information.
- Zones C and D contain residues from disposing approximately 3-million gallons of plywood resin waste, wood treatment and preservative waste, lime sludge, cutting oils, paint and paint solvent waste, and other bulk liquid waste. These zones were combined in 2002.
- Zone E contains approximately 11,000 tons of sludge from paper manufacturing.
Potentially liable persons (PLPs)
Thirty-plus different parties, legally called potentially liable persons (PLPs), share responsibility for cleanup of contamination from past landfill operations. The PLPs have grouped themselves by the type of wastes each party (or their predecessor companies) disposed at the site, and shared cleanup objectives. The four groups include:
- Industrial Waste Area Group III (IWAG)
- Landfill Group
- Bayer CropScience (Zone B)
- Unaffiliated
We provide regulatory oversight of the cleanup work under the Model Toxics Control Act (MTCA). Agreed orders and enforcement orders are in place between Ecology and the PLPs that require the PLPs to investigate and clean up the landfill.
Contamination
- Dioxins
- Herbicides
- Metals
- Polychlorinated biphenyls (PCBs)
- Semi-volatile organic compounds (SVOCs)
- Volatile organic compounds (VOCs)
Cleanup
Following the 1999 feasibility study, cleanup began in the early 2000s on the industrial waste zones and Municipal Solid Waste Landfill. Multi-layer cover systems designed to contain the waste were installed. Drummed herbicide waste from Zone B was removed and disposed offsite. Systems to treat contaminated soil vapors, landfill gas, and groundwater were installed. These interim cleanup actions reduced the potential threat to people and the environment while we developed the final cleanup plan. They also provided information about the effectiveness of different cleanup methods.
Additional investigations, monitoring, and evaluation of the interim cleanup actions from 2008 to 2019 helped improve the performance of the existing cleanup systems and increased contamination removal.
In 2018, the IWAG and the Landfill Group each submitted a Focused Feasibility Study (FFS) evaluating final cleanup options for all the landfill zones. The studies compared cleanup options for the entire Pasco Landfill, taking into account the effectiveness of past and ongoing cleanup actions. The studies also helped us draft our Cleanup Action Plan.
Cleanup Action Plan details
The Cleanup Action Plan became final after public comment in late 2019, and cleanup construction began in October 2020. Plan details include:
- ~35,000 drums of hazardous waste and associated debris from Zone A excavated, characterized, and transported for off-site disposal
- Zone B is becoming a separate site
- The remaining municipal solid waste and industrial waste zones will continue to be maintained and monitored under their existing engineered covers
Off-site Waste Disposal Plan
Zone A drums and associated dangerous and hazardous wastes were transported to disposal facilities in Arlington, Oregon, or Grand View, Idaho.
Some Zone A wastes are Corrective Action Management Unit (CAMU) eligible under Washington’s Dangerous Waste Regulations. The parties responsible for cleanup prepared documentation supporting their petition to dispose certain Zone A wastes off-site as CAMU-eligible. This documentation is an attachment to the Zone A Removal Action Engineering Design Report: Appendix C – Waste Handling, Characterization and Disposal Plan. Ecology determined the Appendix C Waste Plan is adequate, and we invited public input on it September 8 - 22, 2020. We didn't receive any comments.
The disposal facilities in Oregon and Idaho held separate public comment periods and didn't receive any comments, so the Appendix C Waste Plan is final. The Oregon and Idaho departments of Environmental Quality have now approved the plan as well:
- Idaho Department of Environmental Quality approval letter
- Oregon Department of Environmental Quality approval letter
Learn more
- Cleanup Action Plan public notice
- Frequently Asked Questions: Pasco Landfill Cleanup
- Zone A Drum Removal Engineering Design Report
Balefill/Inert Waste Area
In November 2013, a fire was reported in the Balefill/Inert Waste Area where municipal waste and tires were compacted into bales and buried.Early attempts to smother the fire by covering the ground above it with more soil and a plastic barrier did not extinguish it. Following that, liquid carbon dioxide was injected underground over several months to help displace oxygen from the burning areas. This helped cool the fire but didn’t put it out.
In April 2014, Ecology issued an enforcement order to the PLPs. The order directed them to develop and carry out a plan to fully extinguish the underground fire near the Balefill Area.
During late summer and fall 2015, deep trenches were dug around the fire boundaries and filled with a clay-cement slurry, creating a barrier that prevented the fire from spreading and limited oxygen flow to it. Buried waste in the fire zone was then excavated and extinguished. Some combustible materials, such as tires and wood debris, were hauled offsite for disposal. After quenching, leftover waste was returned to the pit and reburied. A final cover of clay, soil, and cement was then placed over the top, effectively sealing off the original fire zone.
In December 2015, temperature and gas monitoring probes were installed around and within the former Balefill Area fire zone. Monitoring data were collected for several months. These data, together with observations made during the construction work, show the fire in the Balefill Area waste is now out.
Lessons learned from this event will be used to help prevent the possibility of future underground fires. Ecology closed out the enforcement order in May 2017 after all required actions were completed and approved.
- View photos of work on the underground fire.
- Download a presentation about the Balefill Area underground fire we gave at the Local Emergency Planning Conference in May 2017.
Zone A
During summer and fall 2016, Ecology saw changes in Zone A soil vapors and underground temperatures, so we asked the PLPs to gather more information. From January through March 2017, the PLPs investigated whether an underground fire was under Zone A. The PLPs issued their Zone A Combustion Evaluation Report (Appendices) in late April 2017. Ecology responded in a letter in early September 2017.
In April 2017, Ecology learned that non-aqueous-phase liquid (NAPL) was in a Zone A groundwater monitoring well (MW-52S). Resampling in June 2017 confirmed an approximate 3-inch-thick layer of NAPL, containing various petroleum hydrocarbons, solvents, and PCBs (polychlorinated biphenyls), was floating on the water table. The NAPL is liquid chemicals leaking from the degrading Zone A drums.
Monitoring and groundwater sampling showed the NAPL was in just one area under Zone A, and had not moved beyond the landfill property boundaries. Absorbent “socks” were installed at well MW-52S in August 2018 to remove NAPL floating on the water table. The socks were regularly replaced when a certain amount of NAPL was captured. The amount of NAPL removed from well MW-52S decreased over time.
The NAPL under Zone A and concerns about waste smoldering underground are two important reasons Ecology required the drums to be removed from Zone A. This will stop the sources of these uncontrolled releases and potential fire hazards.
Treating soil contamination
Treatment technologies removed about 1 million pounds of contaminants from soil beneath Zone A since 1997. A soil vapor extraction system vacuumed contaminants from the soil above the water table. The contaminated vapors were treated on-site using a high-temperature incinerator called a thermal oxidation treatment unit.
Operating the thermal oxidation treatment unit required a permit from Ecology’s Air Quality Program. Ecology responded to two sets of comments on the air quality permit from two of the PLP groups. We held another comment period from March 20 through April 20, 2017, to address changes we made to the permit in response to these comments. The same two PLP groups commented on the revised permit. We responded to comments and approved the permit.
The operating permit required annual performance testing of the thermal treatment unit. Performance testing in 2017, 2018, and 2019 confirmed the ability of the treatment unit to meet the conditions of Ecology’s air quality permit.
Cover system
The engineered Zone A cover system was installed in 2001 and removed in 2021 to excavate the drums for final, off-site disposal. The cover included several layers of soil, plastic geomembrane, and clay that were many feet thick. The cover system was installed to prevent people, animals, and precipitation from contacting contaminated soil and waste. The system was designed to quickly shed rainfall and snowmelt to adjoining stormwater holding ponds or allow plants that grow on its surface to use the water. A new cover system will be installed after the Zone A cleanup work is completed.
Zone B
In 2002, nearly 5,000 drums of herbicide-manufacturing waste were excavated and taken to a hazardous waste disposal facility. Some contaminants remain in the soil, so a protective, engineered cover was installed in 2013. The cover includes several layers of soil, plastic, and clay that are many feet thick.
This cover keeps people, animals, and precipitation from contacting the contaminated soil beneath it. Without the engineered cover, rain and snow melt could flush contaminants deeper into the soil or to the underlying groundwater. Fencing further prevents access to Zone B.
Becoming a separate site
The PLPs primarily responsible for Zone B cleanup work (Bayer CropScience Inc.) petitioned Ecology in late 2018 to remove Zone B from the Pasco Landfill site and establish a new, separate cleanup site. We considered the following before approving the request in July 2019:
- Zone B’s location in relation to other waste disposal areas at the site
- Historical and recent groundwater monitoring results and site-wide groundwater flow patterns
- The previous drum removal
- Known and anticipated engineered cover system performance
We will prepare separate cleanup documents and a separate legal agreement for Zone B. Zone B PLPs will be solely responsible for maintaining the cover and institutional controls, and monitoring groundwater. They will no longer participate in cleanup activities for the rest of the Pasco Landfill site.
However, Ecology retains the right to rename Bayer CropScience Inc. as a PLP for the Pasco Landfill Site if Zone B-type contaminants are found in other areas of the site.
Zone C/D
Waste materials in Zone C/D are protected by covers installed in 2001. Portions of the Zone C/D cover also extend over a trench where garbage was burned prior to 1971. The cover system prevents people, animals, and precipitation from contacting contaminated soil and waste. Without the engineered cover, rain and snow melt would cause contaminants to flush deeper into the soil or to the underlying groundwater. Fencing further prevents access to this zone.
Zone E
Waste materials in Zone E are protected by a cover installed in 2001. The cover system prevents people, animals, and precipitation from contacting contaminated soil and waste. Without the engineered cover, rain and snow melt would cause contaminants to flush deeper into the soil or to the underlying groundwater. Fencing further prevents access to this zone.
Recent Public Outreach
From September 8 to September 22, 2020, Ecology held a public comment period for the Zone A Removal Action Engineering Design Report: Appendix C – Waste Handling, Characterization and Disposal Plan and didn't receive any comments. Some Zone A wastes are Corrective Action Management Unit (CAMU) eligible under Washington’s Dangerous Waste Regulations. The parties responsible for cleanup prepared the Appendix C Waste Plan in support of their petition to dispose certain Zone A wastes off-site as CAMU-eligible. Zone A drums and associated dangerous and hazardous wastes will be transported to disposal facilities in Arlington, Oregon, or Grand View, Idaho.
From September 3 to October 3, 2019, Ecology held a public comment period for the Cleanup Action Plan, legal documents that include a scope of work and schedule, and State Environmental Policy Act documents (SEPA checklist | determination of non-significance). We held a public meeting at Virgie Robinson Elementary School on September 17, and our presentation is available for online viewing. You may also view our presentation at the September 23 Pasco City Council meeting. We responded to eight sets of comments. You may read them in our Response to Comments. The draft documents became final without further changes, and cleanup is moving forward under an Enforcement Order we issued November 8, 2019 because the PLPs could not meet the November 4 deadline to move forward under a consent decree.
From September 12 to October 26, 2018, Ecology held a public comment period for the Focused Feasibility Studies that evaluate final cleanup options for all areas of the Pasco Landfill (see the English/Spanish public notice). We held a public meeting at Virgie Robinson Elementary School on September 26, and our presentation is available for online viewing. The comment period end date was extended from October 12 to October 26 in response to a request from the Franklin County Commissioners. We responded to six sets of comments. You may read them in our Response to Comments.
In October 2017, Ecology mailed a Zone A Update to residences and businesses near the Pasco Landfill to inform the community about a potential underground fire and new groundwater contamination leaking from the drums in this zone.
In May 2017, Ecology presented information about putting out the fire in the Balefill Area at the Local Emergency Planning Conference in Chelan, Washington.
**If you are part of a group interested in a presentation about the Pasco Landfill, please contact Erika Beresovoy at erika.beresovoy@ecy.wa.gov or 509-385-2290 for scheduling.**
Next Steps
Zone A cleanup activities began in October 2020, and more than 35,000 drums of hazardous waste were removed in early June 2022. Thermal treatment of remaining contaminated soil in Zone A started in 2024. When it's finished, a new protective cover will be constructed over Zone A.
The landfill site is not accessible to the public, and many measures are in place to ensure community safety. Ongoing monitoring will continue throughout the landfill and in areas where the groundwater plume extends off the property.
When the Zone B draft Cleanup Action Plan, legal agreement, and SEPA documents are ready, we will make those available for public comment and notify the community using the same mailing list we have for the Pasco Landfill.
Site use restrictions called institutional controls are in effect
Institutional controls can be fences, signs, or restrictions on how the property is used. For instance, an institutional control may prohibit installing drinking water wells or disturbing a protective cap that isolates contamination. These restrictions keep the contamination contained and keep people from being exposed to the contamination. The controls are usually listed in environmental covenants recorded with the county.
Periodic reviews are required when institutional controls are required at a site. Ecology conducts reviews to make sure the controls remain effective and the cleanup still protects human health and the environment. We conduct periodic reviews about every five years.
Institutional Controls 2
Environmental Covenant
Restrictions/Requirements
- Prohibit Soil Disturbance
- Restrict All Ground Water Extraction/Well Installation
- Restrict Land Use
Restricted Media
- Groundwater
- Soil
Other Upland Instrument
Restrictions/Requirements
- Restrict All Ground Water Extraction/Well Installation
Restricted Media
- Groundwater
Documents 126
Legal 17
Public Information 40
State Environmental Policy Act 12
| Document Title | Document Date | Document Type |
| SEPA Environmental Checklist: Pasco Landfill CAP | 8/27/2019 | SEPA Documents |
| Determination of Non-significance: Pasco Landfill CAP | 8/27/2019 | SEPA Documents |
| Determination of Non-Significance RTO: Pasco Landfill | 11/23/2016 | SEPA Documents |
| SEPA DNS Pasco Landfill Balefill Fire Addendum | 7/21/2015 | SEPA Documents |
| SEPA Pasco Landfill RTO DNS | 6/25/2015 | SEPA Documents |
| SEPA Pasco Landfill RTO 2015 | 6/8/2015 | SEPA Documents |
| SEPA DNS Enforcement Order Pasco Landfill Fire 4-28-14 | 4/28/2014 | SEPA Documents |
| SEPA Checklist Enforcement Order Pasco Landfill Fire 4-28-14 | 4/28/2014 | SEPA Documents |
| Pasco Landfill NPL Site Zone B DNS | 7/9/2010 | SEPA Documents |
| Pasco Landfill NPL Site Zone A DNS | 7/9/2010 | SEPA Documents |
| Pasco Landfill NPL Site Zone A SEPA Checklist | 7/9/2010 | SEPA Documents |
| Pasco Landfill NPL Site Zone B SEPA Checklist | 6/8/2010 | SEPA Documents |
Technical Reports 57
Places to see print documents
-
Eastern Regional OfficeN 4601 Monroe StSpokane, 99205-1265Please schedule an appointment to view print documents at this location.
-
Mid-Columbia Library, Pasco Branch1320 West Hopkins StreetPasco, 99301This location may only have print documents available during open comment periods.
Contaminants 15
| Contaminant Type | Soil |
Groundwater |
Surface Water |
Air |
Sediment |
Bedrock |
|---|---|---|---|---|---|---|
| Other Contaminant - Base/Neutral/Acid Organics | C | |||||
| Halogenated Organics - Halogenated Organics | C | C | ||||
| Metals - Metals Priority Pollutants | C | C | ||||
| Metals - Metals - Other | C | |||||
| Halogenated Organics - Polychlorinated biPhenyls (PCB) | C | C | ||||
| Non-Halogenated Organics - Phenolic Compounds | C | C | ||||
| Non-Halogenated Organics - Non-Halogenated Solvents | C | |||||
| Halogenated Organics - Dioxins/Furans | C | |||||
| Non-Halogenated Organics - Polycyclic Aromatic Hydrocarbons | C | |||||
| Halogenated Organics - Halogenated Solvents | C | |||||
| Other Contaminant - Conventional Contaminants, Organic | C | S | ||||
| Other Contaminant - Conventional Contaminants, Inorganic | C | S | ||||
| Non-Halogenated Organics - Other Non-Halogenated Organics | C | |||||
| Reactive Wastes - Other Reactive Wastes | C | |||||
| Pesticides - Pesticides-Unspecified | C | S |
- S
- Suspected
- C
- Confirmed Above Cleanup Levels
- B
- Below Cleanup Levels
- RA
- Remediated-Above
- RB
- Remediated-Below
- R
- Remediated
Public Comment Period
From April 2021 – June 2022, over 35,000 drums of hazardous waste were removed from Zone A of the closed Pasco Landfill and taken to Grand View, Idaho, and Arlington, Oregon, for safe disposal. Since April 2024, underground thermal treatment has removed and destroyed about 9,100 pounds of chemicals from contaminated soil around the area where the drums were buried.
Recently, some chemicals being removed from the treatment process were not fully captured by the system and traveled to groundwater. Groundwater is not a source of drinking water in the area, and people are not currently at risk. Increased chemical recovery in Zone A is underway to correct this situation.
You are invited to review and comment on the amended Enforcement Order to address groundwater contamination. Ecology is requiring the parties responsible for cleanup to:
The amended Enforcement Order includes the Cleanup Action Plan, scope of work, and schedule for completing the new activities.
Review the documents
Submit comments via email, mail, or online by 11:59 p.m. January 20 to:
Jeremy Schmidt, jeremy.schmidt@ecy.wa.gov
N. 4601 Monroe St., Spokane, WA 99205-1265
Online comment form
Next steps
The Enforcement Order amendment went into effect November 20, the day we issued it. The parties responsible for cleanup have already begun the required work to address the situation as quickly as possible. We are working closely with them to ensure public safety.
We planned a 60-day comment period to allow people more than 30 days to respond after the community receives the public notice in the mail. We will hold a public meeting if 10 or more people request it.