Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Abstract: 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 in many states mention site and soil conditions, they are at times ambiguous or only assess whether the site can or can not be used for wastewater treatment and dispersal. Often the rules provide little guidance on the specific procedure for determining a final long term acceptance rate (LTAR) based on multiple soil and site conditions, relying on the discretion and experience of the field practitioner to determine the final LTAR. 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. This procedure is based on principles of water and air movement in soil as well as expected treatment capacity. Each section of the rules that deals with a specific soil or site parameter was rated. The result is a step-by-step procedure that includes each parameter in the final LTAR determination. The procedure is reproducible from site to site and from practitioner to practitioner. Once the LTAR for the soil/site is determined it can be further adjusted based on wastewater strength, flows and other applicable factors related to expected performance.