Summer and fall have come and quickly gone and what an interesting year it was at Beatrice Area Solid Waste Agency. This last March we finished construction of our newest landfill cell. This new landfill cell was constructed in between what is considered our old landfill which was used last in the late 80s and our newest landfill cells which we continue to fill with large heavier items that will not be affected by the wind, as this last area is at the highest elevation of the entire landfill.
The bottom of the new cell is approximately 20 feet below the surrounding ground and is lined with layers of compacted clay and also a high density poly ethylene liner to prevent any groundwater contamination through the life of the landfill. The bottom of the cell gently slopes downward towards the center so as water drains down through the eventual garbage it is collected in this sump area and drained out through corrugated tile piping that runs the length of the cell. This sump area is comparable to a ditch that runs the length of the cell and is filled with gravel to help filter the solids from entering the drain tile. This water then drains out to our leachate containment pond.
During construction our engineering group decided to install a retention dam across the new cell approximately half way through the new cell. This dam would hold any new rain water above the retention dam and allow landfill operators to pump this rain water out into the drainages around the landfill. This was rain water that had not touched garbage and was considered storm water. If the rainwater would have would have come in contact with garbage it would have then been considered leachate and would have had to stay in the cell to eventually drain out through the bottom drains or be pumped out.
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Shortly after construction was completed and before garbage had been placed in the cell the landfill received approximately 3 inches of rain over an evening. Our engineer’s retention dam did as it was supposed to do for as long as it could before the water crested the retention dam and washed it out. This large amount of rainwater had now collected at the lowest end of the landfill. After discussing the situation with our engineers it was determined that as the water rapidly washed out the retention dam it washed the silt from the dam over the top of the drainage tile and across the entire length of the cell. This silt on top of the sump area would prevent any drainage thru the sump area. After discussing our situation with our Nebraska Department of Environmental Quality inspector landfill personnel began pumping the storm water out of the cell and draining it into our storm water containment pond. After the rain water was pumped out and the cell floor began to dry the retention dam was rebuilt and the silt over the sump area was removed and the cell floor was brought back to original design standards.
Currently we estimate we have approximately 6.5 years of life left before this newest cell is full. Soon we will begin working with engineers to begin the permitting process of constructing our new landfill. This new landfill will be built on land directly across from our current compost site on land the city currently owns and farms out. Permitting and construction of a new landfill is estimated to take up to 5 years to complete.