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%.
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.