Select fill is an excavated clay based product that packs very well and is only appropriate for filling holes or placing where appearance is not a concern. Select fill is the ideal product used in building a pad or a compact foundation like the base for the foundation of a home or lining a pond to prevent leaks and because of its density can be difficult to work with, but is a consistent blend of sand and fine clay and meets all of the specifications for even the most demanding construction jobs.