FRONTERA MATERIALS, INC.

Crushed and Broken Limestone Mining and Quarrying

This includes (1) establishments primarily engaged in developing the mine site, mining or quarrying crushed and broken limestone (including related rocks, such as dolomite, cement rock, marl, travertine, and calcareous tufa) and (2) preparation plants primarily engaged in beneficiating limestone (e.g., grinding or pulverizing).

Construction Sand and Gravel Mining

This includes establishments primarily engaged in one or more of the following: (1) operating commercial grade (i.e., construction) sand and gravel pits; (2) dredging for commercial grade sand and gravel; and (3) washing, screening, or otherwise preparing commercial grade sand and gravel.