Remove trees, shrubs, grass and other vegetation where necessary. If it is necessary to remove soil, reserve for later use. Fill soil should be free of rocks, plants, debris, and frozen clods over two inches. Grade and level area to be used for constructed wetland cell. Compact fill to the required elevations, filling in any disrupted or low-lying areas.
Mechanical compaction is necessary to ensure proper base preparation.
The soil may need to be dried or moistened as maximum compaction occurs when the soil is moist. Constructed Wetland Cell Size the wetland cell at one gallon per square foot or a five-day detention time. This sizing refers to the area between the inlet and outlet manifold pipes. If multiple systems are to be built, conduct a void ratio test on the gravel to determine the correct detention time. For example, a two bedroom home would require 300 square feet of wetland area with dimensions of 25 by 12 feet.