The 38-acre Ascon Landfill site operated as a waste disposal facility for nearly 50 years up to the mid 1980’s, receiving waste from oil drilling operations and construction debris. With its potential exposure of hazardous conditions to the public and the environment, the site’s Responsible Parties (RPs) were ordered by the California State Department of Toxic Substances Control (DTSC) remediate the site to acceptable health risk levels.

Why does this project matter?

The remediation of the Ascon Site has been a longstanding beacon of targeted community interest and concern, considering its closeness to nearby residential areas, which include a high school, a community park, and regions of environmental sensitivity.

Starting in the 1990’s, DTSC oversaw many investigations in order to appropriately characterize the site’s nature and extent of hazardous materials, as well as health risks. These investigations ultimately led to preparation of a Remedial Action Plan (RAP), that studied various options to remediate the site. DTSC’s preferred remediation alternative included partial source removal of hazardous materials with a protective cap over the site. Before DTSC’s preferred RAP remediation plan could be implemented, environmental review was necessary to assess and mitigate the potential environmental impacts the remediation measures would have on the public and the environment.

What is ESA doing to help?

ESA prepared the EIR for the RAP’s preferred remediation plan consisting of partial source removal and a protective cap.  ESA also prepared a subsequent Mitigated Negative Declaration for the Interim Removal Measures Workplan, which was undertaken to enable assessment of materials at the Project site, and to permit their removal.

Collectively, the CEQA analyses addressed the short- and long-term impacts of the RAP’s remediation and cap in place measures. ESA’s air quality and health risk scientists modeled tens of thousands of data points to assess the human and ecological risks associated with implementing the remediation plan. ESA’s biologists performed nesting bird and botanical surveys and developed a mitigation strategy for the approximately 150,000 southern tarplant, a sensitive plant species, that would be impacted by the Interim Removal Measures Workplan. In addition to CEQA compliance, ESA contributed to the review of the cap’s design details and developed the long list of Project Design Features and Mitigation Measures that the project’s RPs are committed to implementing during the remediation activities.

The EIR for the Ascon Landfill Site was certified and the DTSC filed a Notice of Determination in 2015. Cleanup and remediation on the site began in January 2019.


Client California State Department of of Toxic Substances Control (DTSC)

Location Huntington Beach, California

ESA prepared a Mitigated Negative Declaration for the Interim Removal Measures Workplan to enable assessment of the materials underneath tarry and oil waste at two lagoons, and to permit their removal at the site.

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