Site Project Documents

We provide documentation to help you understand DTSC’s cleanup, permitting, enforcement, and investigation efforts

Ascon Landfill Site

Huntington Beach, Orange County

The Ascon Landfill site is a vacant 38-acre parcel which formerly operated as a landfill from 1938 through 1984. Much of the waste disposed at the site in its early years came from oil drilling operations, including waste drilling muds, waste water brines, and other drilling wastes. These liquid and semi-liquid wastes were deposited into open lagoons and pits. From 1971 to 1984, some of the lagoons and pits were filled in or covered with solid waste materials (construction debris). The site is adjacent to residences, a community park, a high school, and an industrial area; and is approximately 0.25 miles from the beach. In 2003, the State of California and the Responsible Parties entered into a Consent Order for the site’s clean up.

Initial remedial work efforts included an Emergency Action (2005-2006) and an Interim Removal Measure (2010-2011) that changed the physical nature of the Site through removal of waste materials, grading, and installation of stormwater control features and best management practices. The Final Environmental Impact Report (EIR) was certified on June 18, 2015 and the Final Remedial Action Plan (RAP) was approved on June 19, 2015. The selected remedy involves waste removal from Pit F, strengthening of materials in Lagoons 4 and 5, waste reconsolidation, and covering with an engineered cap that will have a vegetated cover.

The Responsible Parties conducted Lagoon 5 solidification and oil well abandonment from July 2017 through May 2018, in preparation for RAP implementation.

In January 2019, the Responsible Parties began implementation of the full-scale remedy described in the RAP. At both a May 15, 2019 City meeting and a June 6, 2019, DTSC public meeting, community members voiced ongoing concerns about strong nuisance odors, including physical symptoms among local residents, resulting from the remediation work. On June 6, 2019, the South Coast Air Quality Management District (SCAQMD) issued a Notice of Violation to the site due to nuisance odors and DTSC suspended the remediation implementation work until additional monitoring and odor mitigation measures have been implemented.

During the pause in remediation, an Emergency Action excavation was completed in 2020 at the Site’s northwest berm to address slope stability concerns. Additionally, DTSC allowed for the Pit F remediation work to proceed, because that component of the remedy was planned to be completed within a negative pressure enclosure, considered to provide the highest practicable level of odor mitigation. The excavation and removal of Pit F waste was completed in August 2021.

As part of the DTSC-required, additional monitoring and odor mitigation measures to be completed prior to the restart of full-scale remediation, two separate odor mitigation approaches are being pilot tested on Site. The pilot testing involves a few small and highly controlled excavations during which data will be collected to evaluate and optimize odor management methods during excavation. The pilot test findings will used to develop a restart workplan. Full-scale site remediation will not resume until DTSC has approved this restart work plan.

Additional background information and project documents for the Ascon site can be found on the Ascon page of the Envirostor database.

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