Staff Report
The Santa Barbara County Public Works Department received top honors in the 2020 Outstanding Local Streets and Roads Project Awards. The awards program — sponsored by The League of California Cities, the County Engineers Association of California, and the California State Association of Counties (CSAC) — recognizes cities and counties in California for creative and cost-effective projects that improve local streets, roads and bridges.
The Public Works Department received the award for using a tire-derived aggregate (TDA) wall to reconstruct a section of Ortega Ridge Road. Storm season weather cycles caused the material beneath the road to expand and shrink, which led to cracks, slip outs and, constant maintenance. This problem was solved by partnering with CalRecycle to use 80,000 tires as lightweight fill material to prevent the ground under the road from slipping.
The pilot project was the first in the State to combine the use of TDA and a mechanically stabilized earth retaining wall. The lightweight and permeable nature of the TDA reduces loading of underlying soils subject to seasonal expansion and contraction to reduce settlement, and the MSE wall and the reinforcement grid textile supports the road. CSAC praised the project for its streamlined design and construction, reduced environmental impacts, smaller construction footprint and realized cost savings.
Public Works engineering geologist Chris Doolittle and team members worked on a solution to the problem starting in 2014, after first being involved in investigating settlement at the site over 20 years ago.
“Every few years, the road would settle to the point that it required our maintenance crews to install a pavement overlay to maintain the profile,” Doolittle said. “In 2015, the extent of road settlement forced us to realign the road and close down to one lane of alternating traffic. After the Thomas Fire Debris Flow in 2018, this was the sole access point to Toro Canyon until bridges on State Route 192 were repaired or replaced, and only after their completion were we able to close the road and construct the project.
“It was through coordination with CalRecycle that this pilot project was funded and we received the technical know-how to develop and construct the project.”
Funding for the $665,000 construction project was provided by CalRecycle TDA Grant Funding ($110,000), TDA Pilot Project Funding ($330,000), the Santa Barbara County General Fund ($43,000), and the State Transportation SB1 Fund ($182,000). Additional construction engineering costs were reimbursed by CalRecycle’s TDA Grant Funding ($36,000). The project was constructed by Raminha Construction and completed in August 2019.
“I like this project because we got the departmental support to venture out away from past tried and true techniques to go for something different,” Doolittle said. “This program’s success means we can solve more problems with these new techniques for future projects.”
For details regarding Senate Bill 1 Transportation Funding Projects in Santa Barbara County, visit http://rebuildingca.ca.gov/. For a list of scheduled road projects and road closures, visit PWSB.net, or contact the Transportation Division of County Public Works at (805) 739-8750. Click here to watch a short video on this innovative project.
