UC Delivers

Road Project Saves California $1.2 Million

The Issue

In 2004, the California Department of Transportation (CalTrans) was planning to construct the 5.5-mile final segment of State Route 7. The designed highway converted about 295 acres of prime farmland to non-farm uses. In order to construct the highway above the flood plain, more than 1.5 million yards of soil was needed for the roadbed embankment. The required embankment material for the project was to come from a 570-acre farm site in the state’s right of way at the project site.

What Has ANR Done?

Based on the requirements of the project environmental document that calls for preserving topsoil, CalTrans planned to remove and stockpile 16 inches of the topsoil and then remove 1.5 to 2.5 feet of soil for the roadway embankment. CalTrans planned to return the topsoil to the farm for future agricultural uses. It was believed that the topsoil would provide better crop production than the soil being removed for the embankment.

At the request of CalTrans, UC advisors Khaled Bali and Herman Meister initiated research to find an alternative solution to the costly planned topsoil preservation. They collected 342 soil samples from approximately 57 locations (approximately one location per 10 acres) from depths ranging from one to six feet below the surface. They evaluated the soil texture, salinity, nitrogen and phosphorous levels for post-construction mediation efforts. The advisors found that saving the top 16 inches of soil would not offer any significant benefits for the future of agriculture at the site. However, the removal of the approximately 1.5 to 2.5 feet of soil needed to construct the roadway would lower the elevation of the field and impact the underlying drainage system in the area.

The Payoff

Road Project Saved $1.2 Million

Bali recommended that, rather than removing, stockpiling and returning the top 16 inches of soil, a new drainage system be constructed for the 570-acre site to prevent salinity buildup in the rootzone. The recommendation saved the State of California more than $1.2 million by eliminating the expensive topsoil preservation operation.

Clientele Testimonial

“The recommendation has helped in terminating an expensive and not needed operation, which helped expedite the completion of the project. The joint efforts of the University of California, Imperial County; and the Department of Transportation, two departments of the State of California, to conduct research and taking the proper steps for serving the best interest of the citizens of the State of California, is an exemplary example of cooperation”. -- Mr. Jitendra Goyal, CalTrans Senior Resident Engineer

Contact

Supporting Unit: Imperial County

Khaled Bali, UCCE-Imperial County, 1050 E. Holton Rd., Holtville, CA 92250,(760) 352-9474, kmbali@ucdavis.edu