Warden City Water Supply Wells No. 4 and 5

Facility Site ID: 2802409 Cleanup Site ID: 1618

  • Site Status

  • Cleanup Started

Cleanup Underway

EDB soil contamination was found on Simplot's property near the city wells.
EDB soil contamination was found on Simplot's property near the city wells.

Ecology issued the Cleanup Action Plan in May 2020, which requires Simplot to complete the following actions to clean up the pesticide ethylene dibromide (EDB) in soil and groundwater:

  • Excavating as much contaminated soil as is technically possible.
  • Cleaning excavated soil onsite by extracting contaminated vapors from it.
  • Filing an environmental covenant on the property restricting drilling any new water wells into the contaminated groundwater.
Soil excavation, treatment, and monitoring

Cleanup contractors hired by Simplot excavated about 3,000 cubic yards of contaminated soil from March through May 2021. The soil is stockpiled and covered at the site. Treatment is scheduled to begin in summer 2022. Soil samples will be collected and tested for EDB until soil meets state standards.

Groundwater monitoring

Groundwater samples are collected twice a year to detect any EDB movement off property and track the rate of EDB reduction. With contaminated soil removed, Simplot’s consultant estimated it will take 3 to 5 years for EDB concentrations in groundwater to reduce to 0.05 micrograms per liter, the federal standard for drinking water.

Site History

In 1989, the City of Warden tested their public water wells in response to changes in Washington Department of Health monitoring guidelines and found wells 4 and 5 contained EDB at levels exceeding safe drinking water standards.

Further investigation found EDB in soil on property owned by Simplot, the party responsible for cleanup. From 1971 to 1992, Simplot stored, blended, and transported agricultural chemicals, including the pesticide EDB, at the site. Contaminated soil at the Simplot property was found to contain EDB at levels that are a potential risk for groundwater contamination and consistent with EDB levels in groundwater.

The city notified residents that the EDB levels were not likely to affect the general population, but recommended that pregnant women and children not drink the water. To temporarily fix the problem, the city stopped using the most contaminated well and blended the less contaminated water with clean water to reduce contaminants to meet drinking water standards.

In 2011, Ecology entered into an Agreed Order with Simplot, requiring them to complete a remedial investigation and feasibility study to identify all contaminated areas and propose cleanup options.

The remedial investigation and feasibility study became final after undergoing public comment July 30 through August 28, 2018. We responded to comments from one person. You may read a summary of the investigation findings and four cleanup options in the notice that was mailed to local residents.

We used public input and the information Simplot gathered to develop a cleanup proposal. The following draft documents were available for public review and comment February 3 through March 4, 2020, before becoming final:

  • Cleanup Action Plan — explains our proposed cleanup plan for the site
  • Agreed Order — legal agreement requiring J.R. Simplot Company (Simplot), the party responsible for funding and completing cleanup, to follow the Cleanup Action Plan to remediate ethylene dibromide (EDB) contamination in soil and groundwater
  • State Environmental Policy Act (SEPA) documents — we have reviewed the cleanup actions using the SEPA checklist, and decided they won’t adversely affect people or the environment
You may read a summary of the cleanup actions in the notice that was mailed to local residents. We responded to one set of comments.

Now, Simplot is following the Cleanup Action Plan to fully remediate the EDB contamination in soil and groundwater.
Legal 3
Document Title Document Date Document Type
CAP Agreed Order: Warden City Water Wells 4 & 5 5/14/2020 Agreed Order
Agreed Order No. 8241 Satisfaction Letter 10/17/2018 Order Notice of Satisfaction/Status
RI/FS Agreed Order, Scope of Work, and Public Participation Plan: Warden City Water Wells 4 & 5 5/27/2011 Agreed Order
Public Information 6
State Environmental Policy Act 2
Document Title Document Date Document Type
Determination of Non-significance: Warden Water Supply Wells CAP 1/21/2020 SEPA Documents
State Environmental Policy Act Checklist: Warden Water Wells CAP 3/25/2019 SEPA Documents
Technical Reports 63
Document Title Document Date Document Type
Approval of final replacement groundwater monitoring well installation report and final compliance groundwater monitoring report 10/26/2023 Site Specific Administrative Document - other (Administrative correspondence)
Final replacement groundwater monioting well installation report 10/13/2023 Site Specific Technical Document - other
Final Cleanup Action Completion Report 8/22/2023 Remedial Action Report
Final Compliance Monitoring Plan with new well location figure 6/28/2023 Site Specific Technical Document - other
Replacement Well Installation and Monitoring Workplan 4/6/2023 Site Specific Administrative Document - other (Administrative correspondence)
Warden City Water Supply Wells No. 4 and 5 - Response to March 13, 2023 Ecology Comments on the proposed Monitoring Well Installation Plan 3/23/2023 Site Specific Technical Document - other
Warden City Water Supply Wells No. 4 and 5 - Revised Groundwater Monitoring Well Construction and Monitoring Plan 3/23/2023 Site Specific Technical Document - other
Replacement groundwater monitoring well installation and sampling workplan 3/15/2023 Site Specific Technical Document - other
Ecology Comments on the Proposed and Revised Groundwater Well Installation Plan 3/13/2023 Site Specific Technical Document - other
Progress Report for February 2023, Warden City Water Supply Wells No. 4 and 5. Washington Facility Site ID No. 2802409; Cleanup Site ID: 1618 Agreed Order No. DE 16890 3/9/2023 Progress Report
Progress Report for January 2023, Warden City Water Supply Wells No. 4 and 5. Washington Facility Site ID No. 2802409; Cleanup Site ID: 1618 Agreed Order No. DE 16890 2/7/2023 Progress Report
Simplot Progress Report November 2022 1/9/2023 Progress Report
Simplot Progress Report December 2022 1/9/2023 Progress Report
Simplot Progress Report November 2022 12/9/2022 Progress Report
Simplot Progress Report October 2022 11/9/2022 Progress Report
Simplot Progress Report September 2022 10/7/2022 Progress Report
Simplot Progress Report August 2022 9/9/2022 Progress Report
Simplot Progress Report April 2022 9/9/2022 Progress Report
Simplot Progress Report July 2022 8/10/2022 Progress Report
Simplot Progress Report July 2021 8/9/2022 Progress Report
Progress Report – Preliminary Soil Vapor Extraction Pilot Study Summary 6/17/2022 Progress Report
Simplot Progress Report May 2022 6/9/2022 Progress Report
Simplot Progress Report April 2022 5/10/2022 Progress Report
Simplot Progress Report April 2022 5/10/2022 Progress Report
Simplot Progress Report March 2022 4/8/2022 Progress Report
Simplot Progress Report February 2022 3/9/2022 Progress Report
Simplot Progress Report January 2022 2/9/2022 Progress Report
Simplot Progress Report October 2021 11/9/2021 Progress Report
Simplot Progress Report September 2021 10/11/2021 Progress Report
Ecology Comments on SVE Performance Plan and revised CMP 9/21/2021 Site Specific Administrative Document - other (Administrative correspondence)
Letter, Concurrence to postpone SVE treatment until 2022 9/21/2021 Site Specific Administrative Document - other (Administrative correspondence)
Simplot Warden_Progress Report_July_2021.pdf 8/9/2021 Progress Report
Ecology Approval Letter, EDR-SVE Implementation 7/20/2021 Site Specific Administrative Document - other (Administrative correspondence)
Simplot Progress Report June 2021 7/9/2021 Progress Report
Simplot Progress Report May 2021 6/9/2021 Progress Report
Simplot Monthly Progress Report, March 2021 4/9/2021 Progress Report
Simplot Progress Report April 2021 4/7/2021 Progress Report
Simplot Progress Report Feb 2021 3/10/2021 Progress Report
Approval letter final Enginnering Design Report 3/10/2021 Site Specific Administrative Document - other (Administrative correspondence)
Final Engineering Design Report 2/28/2021 Engineering Design Report
Simplot Progress Report Jan 2021 2/10/2021 Progress Report
Simplot Jan 2021 Progress Report 2/10/2021 Progress Report
Simplot Progress Report December 2021 1/6/2021 Progress Report
Simplot Jun 2020 Progress Report 7/20/2020 Progress Report
Well Decomissioning Report Well MW-5S 7/1/2020 Site Specific Technical Document - other
Wwell Decommisioning Report for well MW-5D 7/1/2020 Site Specific Technical Document - other
Cleanup Action Plan: Warden City Water Supply Wells 4 & 5 5/1/2020 Cleanup Action Plan
Invitation to negotiate the Cleanup Action Agreed Order, sent to the PLP 8/12/2019 Site Specific Administrative Document - other (Administrative correspondence)
Simplot Q3 2018 Progress Report 9/30/2018 Progress Report
Simplot Sept 18 2018 Progress Report 9/30/2018 Progress Report
Final Remedial Action/ Feasibility Study Report (Except Appendix D) 9/26/2018 Remedial Investigation / Feasibility Study
Final RI/FS Report 9/15/2018 Remedial Investigation / Feasibility Study
Simplot Progress Report Q2 2018 6/30/2018 Progress Report
Draft RI/FS Report, Ecology Concurrence Letter 6/7/2018 Site Specific Administrative Document - other (Administrative correspondence)
Draft Final RI/FS Report ready for public comments 5/17/2018 Feasibility Study
Simplot Q1 2018 Progress Report 3/20/2018 Progress Report
1st Q 2018 Progress Report 3/20/2018 Progress Report
Draft RI/FS Report 3/15/2018 Remedial Investigation / Feasibility Study
Draft RI/FS Report Response to Ecology Comments 3/15/2018 Site Specific Technical Document - other
Monitoring Well Sampling Update, Jan 2018 1/1/2018 Groundwater Monitoring Report
Comments on Draft RI/FS Study 9/25/2017 Site Specific Administrative Document - other (Administrative correspondence)
Change of Ecology's Project Coordinator under Agreed Order 8421 8/22/2017 Site Specific Administrative Document - other (Administrative correspondence)
WARDEN CITY WATER SUPPLY WELLS 4 & 5 Site Hazard Assessment 2/1/2005 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

  • Eastern Regional Office
    N 4601 Monroe St
    Spokane, 99205-1265
    Please schedule an appointment to view print documents at this location.
  • Warden Public Library
    305 South Main
    Warden, 98857
    This location may only have print documents available during open comment periods.

Contaminants 1

Contaminant Type
Soil
Groundwater
Surface Water
Air
Sediment
Bedrock
Pesticides - Halogenated Pesticides C 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.