978 LAWS OF MARYLAND. [CH. 506

to be laid, into four classes, namely, agricultural, small acre-
age, industrial or business, and subdivision property. Im-
mediately upon the commencement or within twelve months
after the completion of a water supply or sewerage project
the Commission is empowered and directed to fix and levy a
benefit charge upon all property abutting upon said water
main or sewer, in accordance with the classification, and
shall in writing notify all owners of said properties into which
class their respective properties fall and the charge deter-
mined upon, naming also in said notice a time and place
when and at which said owners will be heard. Such notice
may be mailed to the last known address of the owner, or
served in person upon any adult occupying the premises, or in
the case of vacant or unimproved property, posted upon the
premises. The classification of any property as made by the
Commission shall be final, subject only to revision at said
hearing. The Commission may change the classification of
properties from time to time as said properties change in
the uses to which they are put. Said benefit shall be levied
for both water supply and sewerage construction and shall
be based for each class of property upon the approximate
cost of said construction as an integral part of the whole
system and the number of front feet abutting upon the street,
lane, road, alley or right of way in which the water pipe or
sewer is placed.

All front foot benefit charges heretofore levied by said
Commission, whether by original levy or by increase, as the
same stood charged by said Commission against the respective
properties on December the 31st, 1926, are hereby ratified and
confirmed and determined to be a reasonable charge, and such
front foot benefit charges as the same had been levied or in-
creased by said Commission are hereby declared to be a lien
upon the properties against which the same were charged by
said Commission and enforceable as a lien under the pro-
visions of the law relating thereto at the time the same were
in default. The front foot benefit charge herein levied shall
not be increased nor shall any additional front foot benefit
charge be levied against the property upon which there had
been levied a front foot benefit charge as of December 31, 1926.

Wherever through error, inadvertence or oversight or by
reason of any judgment or decree any property subject to a
front foot benefit charge under this Act has not had the same
levied against it or where the same has been levied by an