I nstal ls Cold Central Plant Recycled A sphalt Concrete Pavement Over Cement Stabi l ized Pulverized Ba se On Wil lowbrook Community Road Improvement Projec t .

he Willowbrook Community Road Improvement Project recently received the

Overall Winner Award from the Outstanding Local Streets and Roads Awards Program sponsored by California State Association of Counties, League of California Cities, and the County Engineers Association of California. The Los Angeles County Department of Public Works has been implementing sustainable pavement treatments in recent years with significant positive results. Statewide

legislation to reduce greenhouse gas (GHG) emissions was a key element in the development of the county’s sustainable approach that first emphasizes taking care of roads that are in good condition, secondly includes the use of recycled materials in the treatment selections and finally reutilizes and strengthens the existing materials in-place.

Completed in November 2014, the Willowbrook project serves as a prime example of Los Angeles County’s approach to sustainability. The project is

located in the unincorporated community of Willowbrook, near the City of Compton. Due to widespread distress, base failure and yielding subgrade, reconstruction of the roads was the best solution for the neighborhood. The County of Los Angeles first looked at

TWritten By: Brian Hoover

Pavement Recycling Systems, Inc.

Below: Hardy & Harper crews pave 3 inches of CCPR asphalt. The recycled base course asphalt was subsequently overlaid with 1.5 inches of ARHM.

sequencing work so that residents have effective and safe access to their homes. “Recycling strategies also minimize disruptions to the public, who have to deal with heavy trucks that remove and replace paving material.This is illustrated by the fact that the CSPB strategy required only 53 truckloads, compared to an estimated 5,500 truck loads required to fully remove and replace the CMB,” says Estrada. “Additionally, the reduced excavation allowed for easier access to residences and businesses during construction. Daily construction operations began at around 7 a.m. and everything was buttoned up and ready for traffic by 4 p.m.”

These sustainable practices have become instrumental in the County’s approach to reduce costs and environmental impacts. Greg Kelley, the Assistant Deputy Director for the Geo-Technical Materials Engineering Division of Los Angeles County states, “The County of Los Angeles recently implemented a comprehensive sustainable focused pavement treatment approach that concentrated on reducing: greenhouse gas emissions, energy usage, and landfill deposition. The

Willowbrook Community Road Improvement Project required a pavement treatment approach that included reconstructing the existing roadway. The sustainable treatment approach selected involved reusing the existing materials in-place by recycling the existing pavement and strengthening the subgrade beneath it. A significant benefit of reutilizing the existing materials in-place is that it eliminates all the truck trips that would be required to remove and replace the pavement and subgrade material if traditional road constructing methods had been used. Eliminating these tasks reduced the work days and truck traffic resulting in fewer impacts to the community. Furthermore, eliminating these construction activities and material costs reduced the cost of the project by $2.2 million, which enabled us to reinvest these savings into other parts of our road network. As a result of the success of this project, the County will be looking to use this approach for all residential reconstruction projects,” says Kelley.

Project success is best ensured by quality field management; Dennis Beyle was

the Superintendent for Hardy & Harper overseeing all project operations and Chris Rogers was the Superintendent in charge from Pavement Recycling Systems, managing the field operations for company’s ReNew Division. “It is difficult to recognize every individual responsible for the success of the Willowbrook Community Road Improvement Project, but teamwork and constant coordination of individual efforts is what makes jobs like this one go smoothly,” says Estrada. “Everyone on this project worked very well together to achieve harmony between road construction and community, as well as to ensure the project’s success.”

Pavement Recycling Systems, Inc. offers a full range of state-of-the art recycling solutions to reclaim, preserve and rehabilitate pavement at any stage of the life-curve. They are a unique and highly acclaimed company with proven engineered alternatives that raise quality, cut costs, and reduce environmental impact. For more information on Pavement Recycling Systems, Inc., please visit them online at www.pavementrecycling.com or call 800-966-7774. Cc

Recommended SuStainable method conventional Remove & Replace method

ARHM (1.5”) CCPRACP (3”)CSPB (8-10”)

ARHM (1.5”)

AC (2.5”)

CMB (10-12”)

$0.80/SF $0.87/SF $0.68/SF $0.80/SF $1.50/SF $2.32/SF

$786,002 $854,778 $668,102 $786,002 $1,473,755 $2,279,407

TOTAL: $2,308,882 TOTAL: $4,539,164

coSt SavinG: $2.2m

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a complete removal and replacement of the existing pavement, which was estimated to cost $4.5 million. Because of the high cost of construction, the County also evaluated the sustainable engineering strategies for the reconstruction and that came in at a cost of approximately $2.3 million. The decision to go with the more cost effective sustainable solution was ultimately made with much more in mind than just simple economics. Counties, cities and municipalities throughout California are focusing on the sustainable aspects of reconstructing roads utilizing recycling processes. Benefits include energy reduction, landfill space savings, tire recycling through the use of Asphalt Rubberized Hot Mix (ARHM), conservation of non-renewable resources, and the reduction of greenhouse gases.

The Willowbrook Community Road Improvement Project focused on reutilizing the existing materials in-place to reconstruct approximately 6 miles of residential roadways (983,000 square feet). The scope of work

included constructing a structural pavement section consisting of 1.5 inches of ARHM on 3 inches of Cold Central Plant Recycled Asphalt Concrete Pavement (CCPRACP) over 8 to 10 inches of Cement Stabilized Pulverized Base (CSPB). Significant benefits were achieved by using treatments that re-use the existing pavement and subgrade materials in-place, rather than the reconstruction methodology of removing the existing materials and replacing them with new pavement materials. Compared to the remove and replace method, the sustainable treatmentresulted in shorter construction durations

with fewer community impacts; a 68 percent reduction in energy consumption; a 57 percent reduction in GHG emissions; the reduction of landfill deposition by 32,000 cubic yards; the diversion of 18,300 scrap tires from landfills; and a cost savings of $2.2 million. These savings enabled Los Angeles County to invest in improvements in other county roads. In addition to all of this, construction time was cut by 30 percent.

Hardy & Harper, Inc. of Santa Ana, CA was the general contractor on this overall $4.6 million project that called for the reconstruction of roadway

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Left: The RAP from the existing pavement is processed at the on-site Central Plant with PASS R engineered emulsion and stockpiled. Approximately 1,200 tons of CCPR asphalt were manufactured daily.

Below: The CCPR asphalt is loaded onto trucks for the short haul from the Central Plant to the paving operation.

pavement, construction of sidewalks, driveways, curbs and gutters, as well as cross gutters. In addition, Hardy & Harper installed all of the striping and pavement markings, as well as performance of other appurtenant work including: parkway improvement, American Disability Act curb ramp installation, tree removal and replacement and traffic control. Work began the first week of March 2014 and was completed on budget in mid-November 2014. Pavement Recycling Systems, Inc. was subcontracted to perform all of the cement stabilization, asphalt removal and asphalt recycling, as well as for delivery of recycled asphalt material back to Hardy & Harper’s paving machines.

In all, 18 separate streets were reconstructed throughout the Willowbrook community, with 124th Street being the longest stretch of roadway affected. Pavement Recycling Systems began their portion of work by milling off the existing asphalt and stockpiling it at a centralized recycling site. Next, they cement treated and stabilized 8 to 10 inches of subgrade to correct

any structural deficiencies and improve its strength and R-Value. They then took the milled asphalt or RAP, crushed it to 1” minus material, and processed with 3 percent Pass R engineered emulsion manufactured by Western Emulsions in the Cold Central Plant Recycling process. Once it was blended, the recycled asphalt was trucked back ito the paving machines for paving on the newly cement stabilized and pulverized base. Finally, a 1 1/2 inch ARHM, totalling 9,100 tons, was paved over the recycled asphalt base course.

Marco Estrada has been with Pavement Recycling Systems for 14 years and is the company’s Director of Business Development. He has been instrumental in increasing the awareness and education of the sustainable process to a long list of agencies during his tenure. “Sustainability and the use of the recycling process is recognized through engineering standards, such as the Caltrans Highway Design Manual and the Green Book Standard Specification for Public Works, as a standard engineering practice,” says Estrada. “It has

gone way beyond economics, as more agencies embrace these sustainable engineering practices. The drive for sustainability and reduced community impacts are also significant motivators at this time.”

Sustainable methods are designed to not only save money, time and the environment, but also to perform as long as removal and replacement with new pavement materials.. According to Estrada, “there is no compromise in quality or lifecycle…. it is for these reasons that sustainable practices are readily becoming the new traditional and conventional. As cited in the California Local Streets & Roads Needs Assessment 2014 Update, there are over 150 California public agencies utilizing these processes.” That does not, however, mean that there are not challenges. “We always have to take the local residents into consideration and respect their day-to-day life styles and activities,” says Estrada. “We do everything we can to minimize the impact that our work will have on their daily lives.” According to Estrada, this is accomplished by

Left: PRSI’s Wirtgen 240i Soil Stabilizer mixes 3% of cement and water into the subgrade soils to provide higher strength and increased support for the overlying asphalt pavement.

Above: A prime coat is placed on the CSPB prior to the placement of the recycled base course asphalt.