Modification to existing Contract. Excavation of existing soil to produce a pit 45' wide x 90' long x 4' deep, not including sloped side walls inside the IPEx relocatable building M7-1062. Includes in... Modification to existing Contract. Excavation of existing soil to produce a pit 45' wide x 90' long x 4' deep, not including sloped side walls inside the IPEx relocatable building M7-1062. Includes install of liner with landfill-grade impervious 60 Mil HDPE Text Liner system; Backfill with W12 granite screenings at 2% moisture content or less; and cover remaining top surface (60' wide x 110' long) with at least 18” of W12 granite screenings at 2% moisture content or less.