When designing a subsurface seepage system the absorption capacity of the soil for each lot shall be determined by one of the methods described below. Lot boundaries must be located prior to on site soil investigations or percolation tests.
(A) Soil investigations shall be conducted in the following manner:
(1) Determination of soil characteristics on sites proposed for development with private sewage disposal systems shall be based on soil boring data collected by a soil classifier or a state licensed professional engineer.
(2) There shall be a minimum of three borings per soil absorption system site. The soil borings shall be at least 50 feet apart, and the proposed subsurface seepage system shall be located within the area where the soil borings were located. More soil borings may be necessary for accurate and appropriate evaluation of a site where there is some concern about the consistency of the soil materials. One of the borings shall be made at the lowest elevation of the proposed absorption field area. Borings shall extend a minimum of 60 inches below the natural ground surface. An observation pit shall be used in gravelly materials.
(3) Observation and determination of soil characteristics may be also determined from a pit dug by a backhoe or other excavating equipment. The Health Department may require soil bits (backhoe excavation) in cases where ground is frozen, where the soil materials are considerably varied in texture, where there has been previous or current fill material, cutting of soils, or where gravelly soils are encountered. Such soil pits shall be prepared at the perimeter of the expected soil absorption area to minimize damage to natural soil structure. Soil pits shall extend a minimum of 60 inches below the natural ground surface.
(4) Site characteristics to be described include zones of seasonal and permanent water saturation, USDA soil textural changes, USDA soil structural features, slope, compaction and depth, soil coloration, depth of limiting layer, depth of soil mottling (depth of low chroma equal to or less than two and a value of four or more-Munsell Color system), internal drainage classification, and permeability range, and other limiting soil characteristics that may reduce permeability.
(B) Only those persons who meet the qualification as specified in the State Department of Public Health, Private Sewage Licensing Act and Code can perform soil investigations.
(C) Septic systems evaluation forms provided by the county must be completed and provided to the Health Department. The Health Department will review and make final determination on type of septic systems and lot sizes.