Cal. Pub. Util. Code § 1417
At any time within 30 days subsequent to the entry of such judgment, the owner of the lands, property, and rights may file with the commission a verified petition in writing, alleging that by reason of expenditures made by the owner subsequent to the date of the filing of the original petition with the commission, for the purpose of preserving or improving the lands, property, and rights, or by reason of other acts and occurrences subsequent to that date, the just compensation theretofore fixed by the commission should be increased, and praying that the commission make its finding increasing such compensation. At any time within 30 days subsequent to the entry of the judgment, the political subdivision may file with the commission a verified petition in writing, alleging that by reason of loss or destruction of the lands, property, and rights, or by reason of depreciation or deterioration thereof or by reason of other acts and occurrences, subsequent to the date of the filing of the original petition, the just compensation theretofore fixed by the commission should be decreased, and praying that the commission make its finding decreasing the compensation. The commission shall in each instance cause a copy of such petition or petitions to be served upon each party other than the petitioner, who was named as the political subdivision, owner, or claimant in the original proceeding before the commission, together with a written notice specifying the time and place of hearing on such petition or petitions, which time shall be within 45 days after the entry of the judgment by the court, and shall cause written notice of the time and place of the hearing to be served upon each petitioner in such petition or petitions. If both such petitions are filed, the commission may consolidate them for hearing and decision.
Ca. Pub. Util. Code § 1417