Monday, November 13, 2006

Applying Soil Morphology to Long Term Acceptance Rate Determination.

David Lindbo1, Joe Lynn2, Kevin Neal2, and Gene Young2. (1) Norh Carolina State Univ, Williams Hall, Campus Box 7619, Raleigh, NC 27695, (2) NC DENR, OSWW, Parker Lincoln Bldg, Raleigh, NC 27695

Soil morphology and site conditions are used in many states to determine the suitability of a building lot for a decentralized wastewater treatment and dispersal system.  Although rules exist in many states they are at times ambiguous or only assess whether the site can or can not be used for wastewater treatment and dispersal.  The rules often provide little guidance on the specific procedure in determining a final long term acceptance rate (LTAR) based on multiple soil and site conditions.  Instead they leave this critical decision up to the site evaluator.  The end result is that two site evaluators can come up with vastly differing LTARs on the same site.  Using the North Carolina rules for wastewater treatment and dispersal as a starting point we developed a standardized procedure to assign an LTAR.  Each section of the rule that dealt with a specific soil or site parameter was rated.  A step-by-step procedure was then developed to include each parameter.  The result is a procedure that is reproducible from site to site and from practitioner to practitioner.