A.
The subgrade area shall be cleared of fences, trees, logs, stumps, brush, vegetation, rubbish and any other perishable or objectional matter. The area shall be stripped of all topsoil, and any other unsuitable material encountered shall be removed and replaced with material suitable for fill under pavements.
B.
The subgrade shall be properly prepared by bringing to the designed line and grade the suitable materials available at hand, if any, or such other suitable materials as loam, course sand, gravel, stone dust or cinders. These subgrade materials shall be mixed, stabilized, compacted and rolled with a ten-ton roller, in such a manner as to produce a stable surface upon which the stone base will be placed. If materials are sandy or of such consistency that they will not produce a hard surface, additional loam of approved quality free from all vegetable or other foreign matter shall be added. The subgrade shall be rolled thoroughly with a roller weighing not less than 10 tons until the entire surface is firm and will not heave or be otherwise distorted by the rolling operation. If any soft or other unstable areas develop within the surface limits of the pavement, the deleterious material shall be removed and suitable material replaced and rolled so that a proper subgrade true to line and grade is produced. Before the stone base is placed, this subgrade must be approved and accepted by the Engineer or Superintendent of Public Works.