Workers install a synthetic liner at the Soil Management Area landfill being built on Chevron’s Guadalupe Restoration Project site in the Nipomo-Guadalupe Dunes. The state-approved Class II landfill will store approximately 1.1 million cubic yards of hydrocarbon-impacted soil that remains from earlier cleanup efforts. Credit: Nick Forselles / Noozhawk photo

Following years of work cleaning up an old oil field, Chevron plans to donate more than 2,700 acres of coastal dunes to the U.S. Fish and Wildlife Service, a move that would double the size of the Guadalupe-Nipomo Dunes National Wildlife Refuge.

The donation agreement, signed on Sept. 16, would expand the current 2,553-acre refuge in northwestern Santa Barbara County and southwestern San Luis Obispo County. The refuge will help protect habitats for 29 special-status species, including the endangered California red-legged frog, western snowy plover and La Graciosa thistle plant.

In a written statement, FWS representatives called the donation agreement a first step in the potential acquisition process and said they look forward to working with Chevron and the community.

The property borders the existing refuge and was once the site of oil field operations run by Unocal from 1949 to 1994. Over several decades, leaking pipelines released an estimated 8.5 to as much as 12 million gallons of a kerosene-like diluent into the dunes, contaminating soil, shallow groundwater and surface water, including the Pacific Ocean.

Chevron acquired Unocal in 2005 and began the process of decommissioning the former oil field, which included 240 wells, nine tank batteries and more than 180 miles of pipeline. Beyond removing the old equipment, the Guadalupe Restoration Project has been ongoing for nearly three decades. 

“It’s been an immense effort,” said Jeff Moore, public affairs adviser for the Chevron Environmental Management Company.

“Then there’s the environmental remediation portion of it, and that is addressing the hydrocarbon-impacted soil, the impacted groundwater and surface water,” he said.

Waves crash behind coastal dunes at Chevron’s Guadalupe Restoration Project site, where habitat restoration has reestablished native vegetation and wetland areas along the coastline. Credit: Nick Forselles / Noozhawk photo

One of the bigger challenges for the company has been managing the soil without further disturbing the fragile dune environment, and Moore said that approximately 1.1 million cubic yards remain before the project is complete.

Chevron initially used land farming to treat the soil, but later began hauling the non-hazardous material to the Santa Maria Regional Landfill, where it was used as daily cover for municipal waste. Hauling was paused in 2018, as the company pivoted to a more sustainable method.

“We came up with what we thought was a better solution and that was to construct an on-site landfill just to manage the rest of our hydrocarbon-impacted soil,” Moore said.

The resulting Soil Management Area (SMA) was approved by the state in 2021 as a Class II landfill, with construction beginning in 2022 on a site already disturbed by Unocal’s operations.

“By building a landfill on site, we eliminated over 69,000 truck trips between here and Santa Maria Regional Landfill,” Moore said. “Those were trucks that would have gone through Guadalupe and the city of Santa Maria.”

Chevron has also taken steps to recycle and repurpose materials throughout the project. 

An on-site water treatment system filters contaminated groundwater and runoff from the landfill. While the water isn’t drinkable, Moore said it “can be discharged to the environment” and used for irrigating habitat restoration areas. 

Recovered hydrocarbons, rather than being discarded as waste, are sent to Chevron refineries in Richmond and El Segundo to be processed into new energy products.

“It comes out on the other end as jet fuel or gasoline or diesel fuel,” Moore said.

Part of the restoration requirements also include guidelines on native plants.

“The plants that we plant here must come from this site,” Moore said. “We can’t source the plants from other locations.”

To meet that need, the company has collected more than 4,200 pounds of seed and grown more than 111,000 plants in its on-site nursery.

“We’ll go out and gather seed, and then that seed will get cleaned and stored for when we need it in the future,” Moore said.

A view of the Guadalupe-Nipomo Dunes and Pacific Ocean from the northwestern portion of the Guadalupe Restoration Project site. More than 2,700 acres are slated for permanent conservation through a planned land donation to the U.S. Fish and Wildlife Service. Credit: Nick Forselles / Noozhawk photo

Moore said the eventual cover of the Soil Management Area itself will also support plants and wildlife. 

“We will place about 3 to 4 feet of native soil on top of the cover system, and then we will restore the habitat,” he said. “After about 10 years or so, it’s going to look like another one of these huge massive dunes out there.”

Chevron expects to complete the work needed for the land transfer within the next three to five years, though some responsibilities will remain with the company even after the transfer.

“We will still also be responsible for any ongoing groundwater remediation that may be required,” Moore said. “That work typically takes decades.”

He said any future decision to allow public access would be made by FWS.

— Noozhawk staff writer Nick Forselles can be reached at nforselles@noozhawk.com.