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Septic tank absorption fields are subsurface systems of the or perforated pipe that dstribute effluent from a septic tank into natural soil. the soil material from a depth of 18 inches to 6 feet is evaluated. The soil properties considered are those that affect both absorption of effluent and construction and operation of the system. Properties that affect absorption are permeability, depth to water table or rock, and susceF~t- ibility to flooding. Slope is a soil property that affects difficulty of layout and construction and also the risk of soil erosion, lsteral seepage, and down slope flow of effluent. Large rocks or boulders increase construction costs. Sewage lagoons are shallow ponds constructed to hold sews~s within a 3epth of 2 to feet long enough for bacteria to decompose the solids, A lagoon has a nearly leael floor and sides, or embankments, of compacted soil material, The assumption is made that the embank- ment is compacted to medium density an3 the pond is protected from flooding. Properties are considered that affect the pon3 floor, These are permeability, organic matter, snd slope, and if the floor needs to be leveled, depth to bedrock becomes important, Shallow excavations era those that require digging or trenching to a depth of less than 5 feet, as for exsmple, • excavations for pipelines, basements, open ditches, and cemeteries. Desirable soil properties are good workability, moderate resistance to sloughing, gentle slopes, absence of rock outcrops or big stones, and freedom from flooding or a high wster table. dwellings, as rated in the table, are not more than three stories high and are supported by foundation footings plsced in undistrubed soil. The features that affect the rating of a soil for dwellings are those that relate to capacity to support load and resist settlement under losd, and those that relate to ease of excavation. Soil properties that affect capacity to support load are wetness, susceptibility to flood- ing, den sit?, plasticity, texture, and shrink-swell potential. Those that affect excavation are wetness, slope, depth to bedrock, and content of stones an d rocks.