Embankment construction Initial soil stripping and grubbing began at the site in April 2018. The footprint areas for the two embankments were cleared down to native, undisturbed soil using dozers or smooth-bucket trackhoes with laser-leveling controls. Some localized areas did not respond well to proof rolling and compaction; i.e., the soil moisture content was high enough that the soil deformed beneath the compaction equipment by pumping rather than compacting to a tight, solid condition. A heavy-duty, nonwoven separation fabric was then placed on the ground and a 2-foot (0.6-m) layer of well-graded rock (quarry spalls) was placed and compacted with five to six passes of a vibratory roller to a tight, unyielding condition. Next the fabric was wrapped back over the top of the rock fill to encapsulate it and provide a top layer of separation fabric in preparation for laying a leveling course of approved structural fill. This subgrade enhancement treatment is shown in Figure 4. Subgrade preparation Those areas with pumping subgrade were overexcavated by about 2 feet (0.6 m), and the wet soil was removed and wasted. GWFV wall installation Once the subgrade was compacted and leveled to the proper grade, the toe-line of the wall was surveyed and marked FIGURE 4 Subgrade enhancement using nonwoven separation fabric to encapsulate a 2-foot (0.6-m) thick layer of compacted quarry spalls; granular leveling layer on top www.GeosyntheticsMagazine.com 1020GS_p26-35.indd 31 31 9/22/20 1:19 AMhttp://www.naue.com http://www.GeosyntheticsMagazine.com