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Temporary Landfill Cap Completed

Oct 15, 2015

By Sara Verrillo

The installation of a temporary cap to cover approximately 30 acres of ACUA’s landfill was recently completed. The project cost approximately $2 million.

The temporary cap is made of reinforced LLDPE laminate and covers several landfill cells that are no longer in use. It is held down by 28,700 bags of sand and has a warranty of five to six years, but will likely last much longer. 

The cap prevents gas from escaping the sides of the landfill and directs it towards the existing gas collection systems. It also keeps water from infiltrating the landfill, which prevents the production of leachate – or water contaminated after passing through trash. Because of this, odors will greatly decrease. In fact, since the temporary cap was installed, there have been zero odor complaints.

The temporary cap will also decrease maintenance time and costs by decreasing the erosion of side slopes surrounding the landfill. Before the cap, landfill crews spent many hours repairing landfill side slopes washed away by heavy rainfall. The temporary cap now covers the side slopes of the landfill that were most prone to erosion.

As you can see through this video, water now flows off of the temporary cap and is directed to stormwater basins. This water does not need to be specially treated like leachate would have.  

The reason this area is receiving a temporary cap rather than a permanent cap is that ACUA is permitted to extend the life of the landfill by building 20 ft. walls around this area after cell #9 is filled to capacity (in approximately five years). The trash will fill in these areas like a cheese wedge. Each wall will extend the life of the landfill by another five to six years. Once these walls are built and filled to capacity, we plan to request additional permitting for walls around cell #9.