Project:
Calabasas Landfill – Characterization and Modeling for Side Slope Final Cover
Overview
The Calabasas Landfill is owned by the County of Los Angeles and operated by the Sanitation Districts under a joint powers agreement. The landfill was operated as a Class II waste management facility from February 14, 1961, through September 14, 1965. Subsequently, it was operated as a Class I facility (e.g., accepting hazardous and nonhazardous wastes) through July 31, 1980, when the Los Angeles County Sanitation Districts suspended Class I operations and began operating the landfill as a Class III facility (e.g., accepting nonhazardous municipal wastes). Refuse has been placed over both lined and unlined areas at the CALF, consistent with requirements in effect at the time the refuse was placed. The landfill is permitted for disposal on 305 acres and the current refuse footprint encompasses 296 acres.
Location:
Los Angeles County
Owner / Client:
Los Angeles County Sanitation Districts
Performance Period:
2011-2014
Services:
- Solid Waste Engineering
- Final Cover Design and Final Closure Plans
Scope of Services Provided by AES
AES characterized and modeled the performance of the existing interim final soil cover over approximately 95 acres of side slopes at the Calabasas Landfill to demonstrate its suitability as an evapotranspirative (ET) final cover that is an engineered alternative to the prescriptive final cover per California Code of Regulations (CCR) Title 27.
Characterization of As-Constructed Side Slope Cover – AES characterized 95 acres of existing side slope cover with 47 auger borings, laboratory testing for geotechnical and unsaturated hydraulic characteristics, and evaluation of vegetation conditions.
Unsaturated Flow Modeling – Unsaturated flow modeling was performed using the UNSAT-H model to demonstrate equivalence of the side slope evapotranspirative cover to the prescriptive Title 27 cover. Modeling was performed at each of the 47 test locations. The cover percolation modeling took into consideration the landfill irrigation patterns and vegetation types. In areas where the cover performance failed to meet equivalence requirements, mitigation measures were developed and implemented.
Cover Equivalence Demonstration Report – The results of the cover characterization and modeling were documented in a report that was submitted to the RWQCB to obtain approval of the existing interim cover as a suitable alternative evapotranspirative final cover.