Facility Site ID: 11687976 Cleanup Site ID: 7906

Current Status - July 2021

Cleanup Excavation at the Bothell Former Hertz Site
Cleanup Excavation at the Bothell Former Hertz Site
On May 31, 2018, the Washington Department of Ecology and the City of Bothell have entered into an agreement called an Agreed Order, which requires the City to clean up the Bothell Former Hertz Site. Previously, the City of Bothell completed a Remedial Investigation and Feasibility Study (RI/FS) on August 10, 2017. This study determined the nature and extent of remaining contamination and evaluated possible methods to clean up the site. They also prepared a Draft Cleanup Action Plan describing how they will clean up the site. A comment period was held to get public input on these documents, and Ecology responded to all comments.

Interim action soil cleanups were conducted in September 2010, March 2012, and March 2013 that removed petroleum hydrocarbon contaminated soils, underground storage tanks and associated facility structures from the ground. Following the excavations, confirmation samples were taken. Oxygen Release Compound (ORC) was placed in the 2010 excavation. Following the interim action soil cleanups, no samples representing soils remaining on Site had concentrations Site cleanup levels. Thus, there are no soil chemicals of concern (COCs) remaining on Site other than HVOCs from the Bothell Service Center Simon & Son Site. The CAP requires 5-7 years monitoring and estimated 5-7 years restoration time frame. It allows a modified sampling frequency after 2 years of quarterly monitoring which was recently accomplished.

Lot D redevelopment

Portions of the BSCSS and the Bothell Former Hertz sites has been reparceled in the Lot D property, requiring modifications to the monitoring well network and the recirculating bioremediation system. Safeguards are in place to protect residents and workers in the redeveloped property, such institutional controls on land use, vapor barriers and vapor mitigation such as venting to prevent vapor intrusion risks to indoor air quality, and indoor air monitoring. However, since a large mass of contamination has already been removed, any human health risks from remaining contamination in groundwater are considered to be minimal or nonexistent.

Institutional controls on land use are under a May 13, 2020 environmental covenant.

The SR 522 ROW portion passing through the Site follows institutional controls established under the Memorandum of Agreement (MOA) between Ecology and the City on Right of Ways at its downtown MTCA sites. South of SR 522, the southern half of Bothell Former Hertz and Bothell Landing sites are under a May 13, 2021 environmental covenant.

The environmental covenants flag remaining groundwater contamination at the Site (petroleum hydrocarbon and arsenic) and specific requirements such as prohibitions on groundwater withdrawal and use, preservation of monitoring wells, and vapor controls. The CAP requires groundwater monitoring for monitored natural attenuation (MNA) for a period of five to seven years, or until cleanup levels are met for eight consecutive quarters. Given that two years of quarterly monitoring has been completed, Ecology has proposed that groundwater monitoring for natural attenuation continue at the Site for an additional three years with some modifications to the well network (see below).

Five year periodic reviews shall also be implemented as part of the cleanup. The institutional controls shall remain in place for parcels that are part of the Site boundary.

Site Background

The Bothell Former Hertz Site (also known as Aarenco, or AA Rentals of Bothell) is generally located on both sides of the newly constructed SR 522 roadway, between Bothell Way NE and 98th Avenue NE / NE 180th Street, in Bothell, Washington. The City of Bothell purchased the property in 2009. They entered into an Agreed Order with Ecology in 2011 for investigation of contamination on the site. The property had been developed from 1918 until 2010, when the City of Bothell demolished buildings on the Site for its SR 522 Bothell Crossroads realignment project. Past property use included automobile repair and dealerships, fueling, and equipment rental. Before the property was purchased by the City of Bothell in 2009, it contained a Hertz equipment rental office, storage yard, and equipment repair shop. The property contained a building used as an automobile dealership. A petroleum company is listed as a lessee in 1930. The building included a gasoline dispensing facility with Underground Storage Tanks (USTs). Three USTs were removed from the property in 1993. Petroleum-affected soils were encountered during the UST removals, and an unknown quantity of affected soils remained at the property underneath buildings. 

In 2008, the City of Bothell conducted Phase I and Phase II Environmental Site Assessments (ESAs) at the Site prior to its purchase of this and adjoining properties. The 2008 Phase II ESA included soil and ground water sampling where three former USTs had been removed in 1993. Petroleum hydrocarbons were detected in soil and ground water exceeding state cleanup standards. Vinyl chloride and volatile organic compounds (VOC) were detected at concentrations exceeding state cleanup standards in ground water samples. Other VOCs were detected in groundwater at the time, including common solvents - tetrachloroethene and trichloroethene. The concentrations were below state cleanup standards. The VOC detections in groundwater appear to be from Bothell Service Center Simon & Son Cleanup site, which is being cleaned up separately. Arsenic was also detected in one well above cleanup levels. In summer 2010, Bothell completed an independent cleanup action at the Site to remove approximately 12,000 tons of soils contaminated with mostly oil petroleum hydrocarbons from former underground storage tanks. Some limited remedial investigation was also conducted at that time. Interim action soil cleanups were conducted in 2012 and 2013.

Chemicals of concern remaining in groundwater after the interim action cleanups are:
  • Total petroleum hydrocarbons (gasoline, diesel and motor oil range)
  • Arsenic
  • Halogenated volatile organic compounds (HVOCs), from the adjacent Bothell Service Center Simon & Son dry cleaning site, which is a separate state cleanup site.

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.

Other Upland Instrument

County Recording #:
County Recording Date:

Covenant Restrictions

  • Maintain/Protect Monitoring System
  • Ongoing Maintenance of Remedy
  • Prohibit Soil Disturbance
  • Restrict All Ground Water Extraction/Well Installation
  • Restrict Domestic Ground Water Extraction/Well Installation

Media Restrictions

  • Groundwater
  • Soil
Legal 9
Public Information 4
Document Title Document Date Document Type
Bothell Former Hertz Updated Public Participation Plan 4/2/2018 Public Participation Plan
Bothell Former Hertz 2018 comment period mailer 4/2/2018 Fact Sheet\Public Notices
Bothell Former Hertz - Draft Agreed Order and Draft Public Participation Plan Fact Sheet 3/25/2011 Fact Sheet\Public Notices
Bothell Former Hertz - Draft Public Participation Plan April 2011 3/25/2011 Public Participation Plan
State Environmental Policy Act 2
Technical Reports 21
Document Title Document Date Document Type
Quarterly Progress Report October - December 2020 1/4/2021 Progress Report
Quarterly Progress Report July - September 2020 10/1/2020 Progress Report
Quarterly Progress Report April - June 2020 7/7/2020 Progress Report
Annual Groundwater Compliance Monitoring Report Bothell Paint, Bothell Hertz, and Bothell Landing Sites Bothell, Washington 6/23/2020 Groundwater Monitoring Report
Quarterly Progress Report January - March 2020 4/1/2020 Progress Report
Quarterly Progress Report #7 Oct 1 - Dec 31, 2019 1/15/2020 Progress Report
Quarterly Progress Report #6 July 1 - Sept 30, 2019 10/1/2019 Progress Report
Quarterly Progress Report #5 Apr 1 - Jun 30, 2019 7/1/2019 Progress Report
Quarterly Progress Report #4 Jan 1 - Mar 31, 2019 4/1/2019 Progress Report
Quarterly Progress Report #3 Oct 1 - Dec 31, 2018 1/3/2019 Progress Report
Quarterly Progress Report #2 10/1/2018 Progress Report
Quarterly Progress Report #1 April 1 - June 30, 2018 7/2/2018 Progress Report
Final Cleanup Action Plan Bothell Former Hertz Facility Bothell Washington 5/29/2018 Cleanup Action Plan
Compliance Monitoring Plan Bothell Former Hertz Facility Bothell, Washington 1/2/2018 Cleanup Action Plan
Draft Final Cleanup Action Plan Bothell Former Hertz Facility Bothell, Washington 8/10/2017 Cleanup Action Plan
Draft Final Remedial Investigation/Feasibility Study Report Bothell Former Hertz Facility Bothell, Washington 8/10/2017 Remedial Investigation / Feasibility Study
Progress Report for Period Ending June 2013 8/9/2013 Progress Report
Progress Report for Period Ending March 2013 4/8/2013 Progress Report
Progress Report for Period Ending December 2012 1/28/2013 Progress Report
Bothell Former Hertz - Documentation of Soil Cleanup 1/28/2011 Site Specific Technical Document - other
Bothell Former Hertz - Preliminary PLP Status Letter 7/14/2010 Site Specific Administrative Document - other (Administrative correspondence)
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

  • Northwest Regional Office
    15700 Dayton Ave N
    Shoreline, 98133
    Please schedule an appointment to view print documents at this location.
  • King County Bothell Regional Library
    18215 98th Ave NE
    Bothell, 98011
    This location may only have print documents available during open comment periods.
  • Bothell City Hall
    18415 101st Ave NE
    Bothell, 98011
    This location may only have print documents available during open comment periods.

Contaminants 6

Contaminant Type
Surface Water
Halogenated Organics - Halogenated Solvents C
Other Contaminant - Conventional Contaminants, Organic RB C
Metals - Arsenic B C
Non-Halogenated Organics - Petroleum-Diesel RB RA
Non-Halogenated Organics - Petroleum-Gasoline RB RB
Non-Halogenated Organics - Petroleum-Other RB RA
Confirmed Above Cleanup Levels
Below Cleanup Levels
This contaminant list was based on our best information at the time it was entered. It may not reflect current conditions at the site.