PUC §787: (a) Any public utility, or its contractor, to whom an excavation permit has been issued by any local agency for the installation, removal, maintenance, or repair of underground facilities may backfill

(a) Any public utility, or its contractor, to whom an excavation permit has been issued by any local agency for the installation, removal, maintenance, or repair of underground facilities may backfill the permitted excavation in any public road or highway with native spoil if all of the following conditions are met: (1) The native spoil is competent spoil. (2) Compaction meets the local agency’s requirements using industry standards for testing compaction. (3) The public utility or its contractor has no physical evidence of, or substantial reason to believe that there has been, contamination of the soil from hazardous wastes. (4) Within 30 days prior to compaction, a local agency has not provided the public utility or its contractor with physical evidence of, or substantial reason to believe that there has been, contamination of the soil from hazardous wastes. (b) If a local agency has determined through prior experience that the public utility that is applying for, or benefiting from, the excavation permit has previously neglected to adequately fill or compact prior excavations, whether directly or through its contractors, the local agency may, as a condition of the excavation permit do either or both of the following: (1) Require the public utility to post a bond, with a term not exceeding one year, amounting to two times the cost for the local agency to repair the backfill work, if done improperly, or any related collateral damage. (2) Require the public utility to submit a report from a registered soils engineer that the proper compaction of the excavation has been achieved. (c) For purposes of this section: (1) “Competent spoil” means soils that can be treated to bring their moisture content into the optimum range, and that can achieve the compaction required by the local agency. (2) “Local agency” means any city or county agency. (3) “Public utility” means any electrical corporation, gas corporation, heat corporation, water corporation, telephone corporation, pipeline corporation, sewer corporation, telegraph corporation, where the service is performed for, or the commodity delivered to, the public or any portion thereof.