Step 9 - The biofilter beds are constructed from two different engineered soils placed on a liner and drained to an outlet for monitoring. The soil mixtures are 1) compost, sand and gravel and 2) Residual Biotech Soil™ or RBS™.

Step 10 - The RBS™ is a mixture of compost and municipal solid waste (MSW) incinerator ash developed at the SUNY College of Environmental Science and Forestry (ESF). The bed of soil is vegetated with tall fescue grass and inoculated with earthworms. The RBS™ at the Fessenden farm is free of any harmful contaminants.