Organic Material Soil Enrichment - Providing hydraulic functionality in situ for challenging sites

by Curt Kerns, M.S., R.P.Bio., C.F.S.

Since the dawn of agriculture, we have known the beneficial effects of adding organic materials to soil. Onsite wastewater management has hitherto utilized soil science more adapted to structural purposes, such as calculating load bearing capability, rather than wastewater management biology and soil hydrogeology. That agricultural soils scientists have been largely ignored has been an impediment to onsite wastewater management progress. For the past eight years, WetlandsPacific Corp. personnel have been adding organic materials to soil with excellent results. While many treat soil hydraulic characteristics as fixed they are not. Soils are a dynamic media capable of significant changes in hydraulic properties. Fine grain soils while providing isotropic (all direction) water movement often have very slow rates of percolation that result in significantly increased infiltration area requirements. Coarse soils typically move water anisotropically, that is only in one direction, which is downwards as described by Darcy’s Law. Capillary water movement, also delineated by Darcy’s Law, is capable of moving water horizontally as well. Additionally, highly porous soil may not offer the necessary retention time for complete biologically community contaminant removal with concomitant adverse groundwater water quality implications. The addition of significant quantities of organic material rectifies the hydraulics of both excessively tight and overly porous soils. The practice can also improve the directional water movement ability of soils allowing even porous soils to move water isotropically. Depending upon the C:N:P (carbon, nitrogen, phosphorus) ratio of the specific organic substances used, nitrogen sequestration can be an additional benefit. Several case studies will be presented.

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“The significant problems we face cannot be solved at the same level of thinking we were at when we created them.” Albert Einstein

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