PUC §185504: (a) In any case in which the authority is required under the provisions of this chapter to pay the cost of removal or relocation of any utility facility, it shall be entitled to the following credits:

(a) In any case in which the authority is required under the provisions of this chapter to pay the cost of removal or relocation of any utility facility, it shall be entitled to the following credits: (1) In the amount of any betterment to the utility facility resulting from the removal or relocation, not in excess of the cost of the increased capacity of the facility. (2) The salvage value of any materials or parts salvaged and retained by the utility. (3) If a new utility facility or portion of that facility is constructed to accomplish the removal or relocation, an allowance of an amount equal to the same proportion of the original cost of the displaced utility facility or portion of that facility as the age of the facility bears to the normal expected life of the facility. (b) A credit shall not be allowed against any portion of the cost that is otherwise chargeable to the utility. (c) A credit allowance for age shall not be applied to publicly owned sewers.