Todd Engineers: Azusa

Azusa Landfill Technical Support
San Gabriel Basin Superfund Site
Azusa, California

The San Gabriel Basin is the largest Superfund site in the nation resulting from regional groundwater contamination that has been investigated since 1979. Commingled plumes of contaminants extend for more than eight miles downgradient from industrial sources in the northeastern portion of the basin. The Azusa Landfill is surrounded by these sources and is one of approximately nineteen facilities named as a Potential Responsible Party (PRP) in the Baldwin Park Operable Unit (BPOU).

Key Issues
Largest superfund site in the nation Commingled plumes of VOCs, perchlorate and other contaminants Numerous sources in large industrial area operating for six decades

Cross section of distribution of TCE in groundwater.

For more than 12 years, Todd Engineers has assisted the Azusa Landfill, former owner Browning-Ferris Industries, and current owner Allied Waste with technical and groundwater issues beneath and in the vicinity of the site. Groundwater flow and contaminant transport in the basin is influenced by operation of basin recharge facilities that change groundwater flow directions beneath the site more than 130 degrees. These conditions, along with the widespread presence of groundwater contamination and PRPs, have required detailed and complex technical evaluations. Our work in the basin has involved all aspects of contaminant hydrogeology as indicated below.

Services Provided

Regional interpretation of changing groundwater flow directions with recharge amounts at nearby spreading facilities seasonally and over time
Documentation of regional plume movement and response to changing groundwater flow
Geochemical characterization for plume delineation
Evaluation of pumping impacts on contaminant transport
Development of PRP allocation strategies
Soil gas and vadose zone characterization
Monitoring well siting and evaluation
Characterization of landfill gas and liquids
Geochemical fingerprinting including strontium isotopes
Vadose zone and groundwater modeling for impact analysis and remedial design
Development of remedial alternatives
Evaluation of proposed conjunctive use impacts on regional plumes
Documentation of gravel mining operations and groundwater recharge