(A) Earth excavation shall include clay, silt, sand, gravel, hardpan, disintegrated shale and rock debris, junk, brick, loose stones and boulders and all materials not classified as rock or rubble as herein specified.
(B) Rock excavation shall include solid deposits so firmly cemented together that their removal requires continuous use of pneumatic tools or blasting. The use of blasting methods shall be used only with written permission of the city.
(C) Rubble excavation shall include buried concrete foundations, beams, walls and other materials that require continuous use of pneumatic tools or blasting. The use of blasting methods shall be used only with written permission of the city.
(D) Payment for trench excavation in rubble or rock, as defined in this specification, shall be made at the unit price per cubic yard for rock excavation, if set forth as a bid item.