Doublegrove Street Project

The Los Angeles County Department of Public Works leads the way to greener, more cost effective roads by applying our three prong sustainable approach in the maintenance, rehabilitation, and construction of our roads. The sound strategies of this approach are to (1) take care of roads that are in good condition, first; (2) use recycled materials in the treatment selections; and (3) reutilize the existing materials in-place.  The Doublegrove Street Project is a leading example of the cost effectiveness and environmental custodianship of our sustainable approach.  The project is located in the Los Angeles County unincorporated community of Valinda. The scope included preserving an entire neighborhood network consisting of approximately 27 lane miles of fair to good residential roadways. The objective was to mitigate the higher cost and greater construction impact to the community normally associated with deteriorated roads by extending the pavement life now. This strategy can achieve a cost savings by up to 50 to 75 percent. The preservation treatment strategy included removing and replacing the entire thickness of asphalt for localized but severely distressed areas; micro-milling the surface of the existing asphalt pavement to improve rideability; constructing a chip seal on the micro-milled surface; and applying a slurry seal over the chip seal. The combination of the slurry seal and chip seal is called the cape seal.  The project integrates three innovative and unique approaches into a typical cape seal project. The first was micro-milling to remove slurry and imperfections. This allowed a better bond surface, neater join lines, and, most importantly, improved ride. The second was that all Reclaimed Asphalt Pavement (RAP) was reused in slurry and chip seal applications saving tons of virgin materials from being mined. Lastly, the County utilized the Job Order Contract process in selecting a contractor. This streamlined the design and contracting tasks, improved collaboration with the contractor, and shortened the construction time.   The contract cost for the project was $1,650,000 (76 cents per square foot). Comparing equivalent service lives and costs between traditional hot mix treatments and cape seal treatments, the cape seal treatment saved $200,000.  This project is an environmentally responsible project, which reduced the GHG emissions by 85%, energy consumption by 76%, and landfill deposition by 4,700 cubic yards. This project is the 16th pavement preservation project successfully completed by the County in the last 5 years and is a testament of a proven model for other agencies to adopt. In summary, the Doublegrove Street Project improved the overall quality of the local streets and road system in a cost effective and green way. The County’s commitment to implementing sustainable projects, like Doublegrove, address existing funding shortfalls and meet the objective of AB32 by reducing GHG emissions.