Over the past decade, Los Angeles County Public Works (Public Works) has utilized sustainable pavement treatments with outstanding success. Public Works continues its commitment to preserving and improving the quality of roads in a cost effective and environmentally responsible way. California mandate AB 32, a state law requiring the reduction of greenhouse gas (GHG) emissions, and limited budgets were the key motivators for developing a sustainable approach that emphasizes: (1) focusing on preserving roads in good condition; (2) using recycled materials in pavement treatments; and (3) reutilizing materials in-place when reconstructing roads. The Keith Drive, Et AL Project (Project), completed in October 2021, showcases the benefits of Public Works’ sustainable approach. This project was funded using RMRA funds.
Within the residential part of unincorporated West Whittier and South Whittier, the pavement condition of nearly 9.7 miles of residential roads and alleys (1,700,000 square feet) was rated poor and exhibited widespread distresses and localized base failure. Reconstruction of the roads was considered as the best solution for the neighborhoods. The traditional reconstruction method of removing and replacing the existing road materials was estimated to cost $12 million. Public Works’ proposed sustainable reconstruction approach method of reutilizing the in-place materials was estimated to save $7.4 million and achieved significant environmental benefits.
The Project scope included removing 3” of the existing asphalt concrete (AC) for use in the Cold Central Plant Recycling (CCPR) process; cement stabilizing 8” to 12” of the remaining AC, base, and subgrade; placing the removed 3” of reclaimed asphalt pavement using the CCPR process on the cement stabilized base material; and constructing 1½” of Asphalt Rubber Hot Mix (ARHM) on the CCPR AC. Using this approach yielded significant benefits. The Project required less construction workdays and reduced traffic impacts. Environmental benefits included a 97% reduction in GHG emissions, 96% reduction in energy consumption, and 16,000 cubic yards of landfill reduction. The ARHM placed as the wearing surface resulted in 29,000 scrap tires being diverted from a landfill. The cost savings of $7.4 million was reinvested to improve other Los Angeles County roadways and to include new curbs, gutters, and sidewalks with new ADA approved access ramps in the Project. The Project required collaboration between the different divisions in Public Works which facilitated a smooth design and construction process to minimize the impact on residents.
In summary, the three-pronged sustainable approach used at the Keith Drive Project is a proven formula for addressing the issues of limited funding, reducing GHG, and conserving resources in a pragmatic manner. This Project serves as a model and success story for other agencies looking to implement sustainable reconstruction treatments.