Vacant land shall not be assessed by the WPCA
until such time as it is built upon and derives a direct benefit from
the sewerage system. Owners of vacant land may approach the WPCA and
request the option of having a sewer benefit assessment levied against
said vacant land based upon the application of this chapter. For the
purposes of this type of assessment levy, the average (mean) residential
assessment of $72,582 shall be used for the determination of the value
charge portion of the sewer benefit assessment formula. The value
charge portion of sewer benefit assessments levied in this manner
shall be adjusted at the issuance of a certificate of occupancy, and
any increased amount due shall be subject to appreciation charges
as described below and shall be due and payable at the time of levy.