Method and apparatus for constructing filter zones in earthfill dams

A method for constructing a filter zone of an earthfill dam, said method comprising the steps of:

• placing first and second relatively coarser and relatively finer particulate materials in a truck having a load body with a longitudinal barrier that segregates said first and second particulate materials on opposite sides of said truck;
• advancing said truck along a predetermined path that corresponds to a horizontal cross-section of said filter zone while ejecting said first and second particulate materials simultaneously and rearwardly from said load body in uncompacted flows that are convergent towards said path, so that in a single pass said first, relatively coarser particulate material and said second, relatively finer particulate material are deposited simultaneously in adjoining elongate berms generally on first and second sides of said path so as to form a stratum of said filter zone;
• grading said elongate berms of said first and second particulate materials with a dozer that trails said truck along said predetermined path, so as to at least partially compact said particulate materials and form a generally level upper surface on said stratum;
• and
• repeating sequentially the steps of advancing said truck along said predetermined path while ejecting said particulate materials and grading said berms with said dozer trailing said truck, so as to form a plurality of said strata in overlying relationship such that said relatively coarser particulate material forms a coarse filter portion of said filter zone and said relatively finer particulate material forms a fine filter portion of said filter zone.

An apparatus for constructing a filter zone of an earthfill dam, said apparatus comprising:

• a vehicle;
• and
• a load body mounted to said vehicle for transporting first and second relatively coarser and relatively finer particulate materials and discharging said materials therefrom, said load body comprising:
• a load box having an interior for containing said particulate materials;
• an ejector assembly mounted, in said load box for discharging said particulate materials therefrom, said ejector assembly comprising:
• a forward bulkhead that extends generally transversely across said interior of said load box;
• a divider bulkhead that extends from said forward bulkhead generally longitudinally through said interior of said load box so as to maintain segregation of said first and second particulate materials therein;
• and
• means for translating said forward bulkhead rearwardly through said load box so as to discharge said particulate materials from a rearward end thereof;
• and
• a chute assembly mounted proximate said rearward end of said load box, said chute assembly comprising:
• first and second generally downwardly-directed chutes for receiving separately said first and second particulate materials that are discharged from said load box and directing said materials downwardly as said vehicle is driven forwardly so as to deposit first and second elongate berms that form a stratum of said filter zone.