The Puente Valley Operable Unit is a 5-square-mile area of contaminated groundwater that runs beneath the City of Industry, City of La Puente and portions of unincorporated areas of Los Angeles County. The primary contaminants found in PVOU groundwater are volatile organic compounds (VOCs), 1,4 dioxane, perchlorate, and hexavalent chromium.

In 1998, the U.S. Environmental Protection Agency (EPA) released the Interim Record of Decision for the Puente Valley Operable Unit (PVOU) that described, in part, EPA’s selected remedy for both shallow and intermediate zone contamination. It stated that the remedial action for the shallow zone shall prevent contaminated groundwater from migrating beyond its current lateral and vertical extent as described in the Remedial Investigation/Feasibility Study (RI/FS).

The remedial action selected by EPA for the intermediate zone shall prevent contaminated groundwater from migrating beyond the San Gabriel Valley Water Company (SGVWC) B7 Well Field Area (an area defined by 14 wells in the immediate area of SGVWC’s B7 Well Field).

In 2005, the EPA issued an Explanation of Significant Differences for the PVOU, mandating treatment for all emergent chemicals in both the shallow and intermediate zones.

The San Gabriel Basin Water Quality Authority has helped to fund the SGVWC treatment facilities, which include ion exchange, advanced oxidation process with ultraviolet light, air strippers and granular activated carbon systems.

Additional information:

Appendix A in WQA’s Groundwater Quality Management and Remediation Plan (406 Plan)

EPA’s San Gabriel Valley Area 4 Superfund Site Puente Valley Operable Unit Fact Sheet