A new technique for stabilizing surficial slope failures using recycled plastic reinforcing members has been developed. The

objective of the project described in this report has been to develop, evaluate, and document a technique for stabilization of surficial

slope failures using recycled plastic reinforcing members. The project has been undertaken in three sequential phases to provide for

logical evaluation of project accomplishments and refinement of the scope of work based on results of activities undertaken

throughout the project. This report is the final technical report for the entire three phase project, which describes the accumulated

activities performed throughout all three phases of the project.

The principal project tasks undertaken include development of a general design methodology, evaluation of the material properties of

recycled plastic members from several different manufacturers, establishment of full-scale field test sections at five different sites,

monitoring the performance of these sites for periods ranging from two to five years, evaluation and interpretation of field

observations, “calibration” of the developed design method, and finally, development of technology transfer materials.

The following conclusions are drawn from the work performed as part of this project: (1) the technique of using recycled plastic

reinforcement to stabilize surficial slope failures has proven to be effective at providing long-term stabilization; (2) observed

performance at the test sites suggests a typical behavioral pattern consisting of an initial period in which little movement is observed

and little load is transferred to the reinforcement, a period of increasing movement and increasing mobilized loads in the

reinforcement, followed by a period of stabilized movements and loads in the reinforcing members as a result of the slope coming to

equilibrium; (3) while the required member spacing depends on the conditions present at a site, a “standard” pattern that appears

sufficient for most sites consists of using recycled plastic reinforcing members placed in a 3-ft by 3-ft (0.9-m by 0.9-m) staggered

arrangement over the entire slide area; (4) reliable installation can be accomplished with either a percussion hammer similar to what

is used on many drill rigs, or a simple drop-weight hammer similar to what is used to install guard rail posts; (5) care must be used

when selecting recycled plastic products for use in slope stabilization applications as the properties of these materials can vary

substantially from product to product; and (6) costs for the technique vary with the reinforcement pattern selected but appear to be

substantially less than those for most other competing slope stabilization technologies.

Given the cost effectiveness and successful demonstration of the technique, it is recommended that the technique be implemented in

“production” operations. The primary challenges to implementation are likely to involve developing appropriate contracting

methods for selection of qualified installation contractors and for acquisition of suitable recycled plastic product. In the early phases

of implementation, it is further recommended that limited monitoring be performed of both construction operations as well as post

construction performance to further expand the database of cases where the technique has been used and to provide for reliable

evaluation of the technique in production operations.