Cal. Pub. Cont. Code § 20857

If the person files a written election to enter upon the direct performance of the work at its own cost and expense, no further proceedings shall be taken in the matter unless such person neglects or fails for 30 days, or for such further time as the legislative body may grant, to make the improvement. If the improvement of the portions of the street required to be improved by such person is not made with diligence or in all respects similar to the improvement of the rest of the street, or with the same materials or under the same specifications, and to the satisfaction of the superintendent of streets, the legislative body may, by resolution entered in its minutes, prescribe such terms and conditions as to it may seem fit and proper before permitting the said person to continue with the work.