Clean Harbors Buttonwillow, LLC - Hazardous Waste Facility Class 2 Permit Modification for Groundwater Monitoring Program


SCH Number
Public Agency
Department of Toxic Substances Control
Document Title
Clean Harbors Buttonwillow, LLC - Hazardous Waste Facility Class 2 Permit Modification for Groundwater Monitoring Program
Document Type
NOE - Notice of Exemption
Present Land Use
Hazardous Waste Landfill
Document Description
Project Description: The California Department of Toxic Substances Control (DTSC) approved a Class 2 permit modification to the groundwater monitoring section of the Clean Harbors Buttonwillow, LLC Hazardous Waste Facility Permit (HWFP). The modification includes changes to the designation of existing groundwater monitoring wells, changes to sampling frequency, changes to the statistical analysis methodology for groundwater analytical data, updates to the groundwater sampling and analysis plan, and updates to the monitoring well construction procedures. Background: The Clean Harbors Buttonwillow, LLC Facility (Facility) is a 320-acre commercial hazardous waste storage, treatment, and disposal facility. The Facility is fenced and has been cleared of all native vegetation. Hazardous waste management and disposal activities at the Facility are regulated under conditions of a Resource Conservation and Recovery Act HWFP issued by DTSC in 1996. HWFP Condition V.C. requires the Facility to operate and maintain a groundwater detection monitoring program in accordance with Title 22, Article 6 groundwater monitoring requirements. The purpose of a detection monitoring program is to provide the earliest possible detection of a release to groundwater from a regulated unit. HWFP Condition V.C.1.d. requires the Facility to submit a permit modification to replace specific groundwater monitoring wells once the wells no longer yield representative groundwater samples. The permit modification is required because declining water levels have caused multiple monitoring wells to go dry. None of the dry wells included in this modification can be replaced with deeper wells at the same location because the dry wells are located at the bottom of their respective water bearing zones. Therefore, the monitoring well network was modified to provide a functioning detection monitoring program. Other changes include administrative updates that will ensure the modified program fulfills the purpose of a detection monitoring program and maintains data validity. Project Activities: The permit modification will modify the monitoring well network as necessitated by long term decreases in regional water levels. The permit modification will also change statistical analysis of groundwater data from inter-well to intra-well analysis for applicable monitoring wells by using a different statistical model. Additionally, the permit modification will change the groundwater sampling and elevation measurement frequency from quarterly to semi-annually. Lastly, the sampling and analysis plan will be updated to incorporate the required changes. No well construction is proposed as a part of this modification.

Contact Information

Ryan Dominguez
Agency Name
Department of Toxic Substances Control, Permitting Division
Contact Types
Lead/Public Agency

Agency Name
Clean Harbors Buttonwillow, LLC
Contact Types
Project Applicant


Other Location Info
Project Location: 2500 West Lokern Road, Buttonwillow, CA 93206

Notice of Exemption

Exempt Status
Categorical Exemption
Type, Section or Code
Title 14 CCR Section 15301
Reasons for Exemption
Existing Facilities. The permit modification will modify the approved groundwater monitoring network to for information collection purposes. The modification will not result in any expansion of the existing Facility or the existing use of the Facility. Further, the modification will not alter the hazardous waste management activities from the current permitted activities. The Facility is not on the Hazardous Waste and Substances Sites (Cortese) List compiled pursuant to Government Code 65962.5. DTSC has determined that approval of the project would not result in a significant effect on the environment due to unusual circumstances. As a result, DTSC finds that the project is exempt from further environmental review under California Environmental Quality Act (CEQA).
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