Construction and Performance of Two Large Rockfill Embankments

TWO rockfill embankments were constructed as sites for building refinery structures in western Colorado. The fills ranged in maximum thickness from 80‐155 ft (25‐48 m). Test fills were done to develop construction‐method specifications that would produce an economic yet dense fill. It was assumed that if dense fills were constructed, long‐term settlement of the fills could be minimized. The specifications developed called for a maximum 2‐ft (0.6‐m) lift thickness compacted by six passes of a smooth‐drum vibratory compactor. Settlements of the fills were monitored for 44‐70 months after construction. The results of the monitoring indicated that the majority of settlement occurs within nine to 18 months after construction. Interior fill points settled less on a percentage basis than points near the fill crest. Overall, the total settlement of the fills was 0.05‐0.10% of the fill height for interior points and 0.10‐0.20% of the fill height for crest points. The results of the settlement monitoring confirmed that the test‐fill program and method specifications provided for the construction of fills in which long‐term settlements were minimized.