Building Class A Development Over Landfill-PPT Presentation

PPT Presentation

Pdf Summary

The Sole Mia development demonstrates how closed landfills can be developed when their variable ground conditions are carefully investigated and managed. The 193-acre site operated as a landfill in the 1970s and closed in 1980. Its heterogeneous landfill layer is about 20–25 feet thick, overlying limestone and sand. Although most self-weight settlement of the old landfill was considered complete, monitoring and test sections showed that long-term creep could continue.<br /><br />Pilot test sections compared deep dynamic compaction (DDC), surcharge preloading, and combinations of the two. About 80–90% of primary settlement occurred within a month after preload placement. DDC reduced settlement compared with untreated areas, while two passes performed similarly to four. Areas where surcharge was removed showed little subsequent creep; areas where it remained continued to settle. The project therefore used DDC and preload for settlement-sensitive features, DDC alone for roads and parking away from buildings, and neither where ground was structurally supported or not settlement-sensitive.<br /><br />Typical preloads were 5 feet over DDC-treated ground and 10 feet over untreated ground. Buildings were supported on augered cast-in-place piles embedded in competent rock. Installing piles through landfill required waste predrilling or localized removal; tires and other obstructions created challenges, particularly for larger piles.<br /><br />Key lessons include the importance of site-specific test sections, monitoring, and combining ground-improvement methods to control long-term settlement. Improved areas experienced ongoing settlement, generally around 1/5 to 1/8 inch per year in DDC areas and closer to 1/10 inch per year where DDC and preload were combined. The project also showed that piles can be installed successfully through landfill, but larger-diameter piles may require casing or other specialized techniques.

Keywords

closed landfill

ground settlement

deep dynamic compaction

surcharge preloading

landfill remediation

soil improvement

pilot test sections

augured cast-in-place piles

long-term creep

site-specific monitoring