Prosser Airport Aircraft Applicators
Nunn Rd, Prosser, WA 99350


Ecology is providing an opportunity for the public to review and comment on the proposed removal from the Hazardous Sites List (HSL) for the Prosser Aircraft Airport Applicators, located at 111 Nunn Road in Prosser. The HSL is a statewide list of contaminated sites. The site is currently ranked a “3” on the list. A rank of “1” is the highest level of concern, while a rank of “5” is the lowest.

Ecology is asking for your comments on the proposed removal of the site from the Hazardous Sites List.

You are invited to:

•   Review the Prosser Airport Aircraft Applicators site No Further Action letter, dated September 10, 2021

•   Review the “Monitoring and Closure Report (Rev01) Former Mary Bonney Site Prosser Airport Prosser, Washington” prepared by Shannon & Wilson Inc., dated August 16, 2019

•   Send your comments to Ecology for consideration. Comments will be accepted October 29, 2021 through November 29, 2021

Submit your comments in writing to Frank Winslow at 1250 West Alder Street, Union Gap, WA 98903, by email: or online at Prosser Airport Aircraft Applicators eComments. After the public comment period ends, Ecology will review and respond to comments received and will hold a public meeting if 10 or more people request one. If no revisions are necessary, the site will be removed from the Hazardous Sites List.


The Prosser Airport Aircraft Applicators site is currently an aircraft hangar and surrounding property has been the location of an aerial pesticide applicator operation since prior to 1966. Investigation revealed areas of stained soil. Soil sampling confirmed contamination from pesticides (e.g., dinoseb, DDT, dieldrin, and others) and petroleum. The site is currently owned by the Port of Benton.


Some cleanup activities have already occurred. More extensive sampling has been completed to determine the extent of the contamination. Excavation of contaminated soils has taken place. Groundwater monitoring wells have been installed.
Ecology entered into Agreed Order with the Port of Benton to complete an Interim Action, Final Interim Action Report, and associated work products to remediate contamination.  Ecology has determined that the Interim Action has met the substantive requirements in the Agreed Order.  Although Interim Action work covered by the Agreed Order has been completed, recent monitoring indicates that there is still residual groundwater contamination (pesticides, petroleum products, and metals) remaining on site and the possibility of an additional remaining source area exists.

Ecology has recommended that the Port of Benton enroll in the Voluntary Cleanup Program to characterize and address any remaining contamination on Site.

You can find site documents by using the "View Electronic Documents" link in the bar on the right, or requesting information from the Central Regional Office public records coordinator.


Map showing site location as Benton County, WA SITE INFORMATION


View Electronic Documents

Cleanup Site Details Report

Facility Site ID: # 7474148

Cleanup Site ID: 2188

Prosser, Benton County

Status: Cleanup Started   Get definitions of Status terminology

Document Repositories:

Central Regional Office
1250 W Alder St
Union Gap, 98903-0009