109.4 Differing Site Conditions and Changes in the Work (for Sec 109.4)

Differing site conditions include subsurface or latent physical conditions at the site differing materially from those indicated in the contract, or unknown physical conditions of an unusual nature differing materially from those ordinarily encountered and generally recognized as inherent in the work. Changes in, or extra, work includes items of work not provided for in the contract as awarded, but found essential to the satisfactory completion of the contract.