A CASE STUDY WHERE BEING GREEN MATTERS: A section of freeway in Central California that was known as the Livingston Bypass Project provides an outstanding example of a green product technology solving a highway construction problem that was seriously impacting contractor productivity and delaying the construction schedule. The heavy highway construction company was unable to efficiently wet and compact the extremely hydrophobic native soils. The natural surface tension of the silty sand soil repelled water and made it almost impossible to efficiently wet the soils and achieve the 95%.

Modified Proctor (ASMT D 1557) density required by the construction specifications within a reasonable amount of time and effort. The contractor needed to moisture condition and compact these soils to construct the subgrades that would then provide a working platform for placement of the aggregate base courses and concrete pavements, and they also needed to construct earthen embankments that were to be built up with layers of horizontal compaction lifts. This section of State Route 99 was designed to run below the grade of the surrounding city as it essentially bisects the City of Livingston. Following construction of the pavement and bridge structures, the slopes of the embankments were to be covered with dense landscape plantings to retain the soils on the relatively steep slopes of the embankments. The contractor’s investigation regarding the potential use of specialty chemicals to solve their compaction problem was complicated by the need to leave the soil healthy and capable of supporting the establishment of trees, shrubs and ground cover.