Where granular sub-base is required, the Subdivider/Developer shall use CA-6 sub-base aggregate granular material, Type A, conforming Section 311 - Granular Sub-base of the IDOT Standard Specifications.
(A) The sub-base shall be constructed in layers not more than four (4) inches thick when compacted, provided, however, that if tests indicate that the desired results are being obtained, the compacted thickness of any layer may be increased to a maximum of eight (8) inches.
(B) In the event it is necessary to undercut the subgrade due to soft or spongy areas, CA-3 aggregate shall be used as fill in order to bring the subject area to subgrade elevation.
(C) The granular material shall be compacted to not less than ninety-five percent (95%) of the standard laboratory density.
(1) The standard laboratory density shall be the maximum density determined according to AASHTO T 99 (method A or C).
(2) A coarse particle correction according AASHTO T 224 will be used with Method A and may be used with Method C.
(D) Equipment used for placement of granular sub-base shall consist of either a suitable spreader box or by the blading of end-dumped or tailgated material, provided however, that the latter method will be allowed only if it can be accomplished without undue segregation of the material.