NHIS: Non-Hazardous Hydrocarbon Impacted Soil Program
geosynthetic clay liner installation

Installation of the Geosynthetic Clay Liner (GCL) portion of the Final Cap.


The City of Santa Maria has produced a 17-minute-long video that explains the Non-Hazardous Hydrocarbon Impacted Soils (NHIS) Program. The video begins by showing the careful loading of the sand onto trucks at the Guadalupe Dunes and the many precautions taken by the inspection crew. The video shows the arrival of the sand at the Santa Maria Regional Landfill, where the trucks are weighed prior to depositing their loads. Mark van de Kamp of the City Manager’s Office and Gonzalo Garcia of Chevron Environmental are the narrators. Mr. Garcia discusses the environmental sensitivity of the Guadalupe Dunes and the precautions that Chevron takes to preserve and enhance the natural setting. The video is 36 megabytes and requires Windows Media Player, which can be downloaded for free. For an overview of commonly asked questions about the NHIS Program, view our NHIS Fact Sheet.

What is “Non-Hazardous Hydrocarbon Impacted Soil?”

A century of oil production in California has left large quantities of soils that are impacted with residual oil. These soils are from oil field sumps, tank farm locations, pipeline leaks, or petroleum product spills. Rigorous testing determines what soils meet the Santa Maria Regional Landfill NHIS acceptance criteria. These oil-impacted soils contain more soil than oil. Under current regulations, these soils are not considered hazardous. The NHIS project at the landfill helps dispose of impacted soils that are structurally unsuitable to leave in place to support residential and industrial construction. In many areas, oil companies have determined that the NHIS needs to be removed. In some areas, such as the Guadalupe Dunes, NHIS may pose a risk to surface waterways and groundwater. The Central Coast Regional Water Quality Control Board (CCRWQCB) tested the NHIS from the Guadalupe Dunes in a laboratory and approved it as being within the landfill’s acceptance criteria. Rigid controls are set in place to ensure that any NHIS brought to the landfill is completely safe.

The CCRWQCB reviews and monitors the NHIS project at the Santa Maria Regional Landfill. The October 22, 2004 report, “Status of California Regional Water Quality Control Board Central Coast Region Staff Report,” addresses the Board’s approval of the Santa Maria Landfill NHIS program, noting that “the project will serve to provide a single monitored disposal location for oil field waste.”

How is this project accomplished? In April 2002, after appropriate Requests for Proposals were processed, a Public-Private Partnership was developed with Central Coast Remedial Resources, Inc. for delivery and acceptance of the impacted soils.

soil being deposited on final grade

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