The Ottawa Operation’s target silica bearing formation is the St. Peter Sandstone, which is a massive formation in areal extent and thickness. Aerially, it extends from Minnesota to Arkansas and from Illinois into Nebraska and South Dakota. On a regional basis, the St. Peter Sandstone ranges in thickness from a few feet to over 1,200 ft, with a general thickness of 100 ft to 200 ft. In northern Illinois, the thickness can be over 300 ft thick. The St. Peter Sandstone is the only strata of economic interest at the Ottawa Operation, and is very uniform in depositional nature and continuity throughout much of the surrounding region. BOYD considers the subject silica sand deposit to be of low geologic complexity. Furthermore, the geology of the St. Peter Sandstone is well understood after a lengthy history of commercial operations at Ottawa. Within the defined resource boundaries, the St. Peter Sandstone exhibits: (1) low depth of cover, (2) lateral continuity, (3) a minimum thickness of 70 ft, (4) gentle dipping, and (5) minimal faulting. The two members of the St. Peter Sandstone—the coarser-grained upper Starved Rock and finer-grained lower Tonti members— are easily identifiable and separable during mining and can be blended as required to meet product specifications. Deleterious materials such as iron (which manifests as orange staining) are easily removed during mining and processing. The sandstone unit is covered by a thin layer of overburden that is generally less th ........

Surface silica sand mining has been conducted at the Ottawa Operation for over 100 years. Recent and current mining operations are located in the South Ottawa Pit, on the south bank of the Illinois River. In and around the Ottawa Operation, the St. Peter Sandstone generally exhibits a shallow depth, flat altitude, and consistent thickness. These characteristics favor conventional surface mining techniques. Since the target sandstone formation does not extend below the water table, the quarry is ‘dry-mined’ using truck and shovel mining methods. Mining occurs in a stair-like fashion to recover sand from the top of the formation (in elevation) down to the lowest practical elevation (generally 5 ft from the bottom of the St. Peter Sandstone). The thin overburden, including topsoil, cap rock and vegetation, is cleared and transported to several mined-out areas in pit where it is stockpiled for future reclamation needs. The material is poorly consolidated and thus drilling and blasting is typically not needed for this stage of the mining operations. Overburden removal is performed, as required (usually one year in advance of sand mining), by third party contractors and does not appear to hinder sand mining to any appreciable degree. Once the overburden has been stripped, the poorly cemented sandstone is drilled and blasted in a series of benches between 40 to 75 ft high. Drilling and blasting are performed by local third-party contractors several times a year depending on pr ........

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