Subsurface sewage disposal systems (SSDS) consist of a house sewer, a septic

tank followed by a leaching system, any necessary pumps and siphons, and a

groundwater control system upon which the operation of the leaching system

depends. This interpretation focuses mainly on the septic tank leaching field

and groundwater control system Soil Potential Ratings Soil potential ratings 

indicate the relative quality of a soil for a particular use compared to other

soils in a given area, in this case the State of Connecticut.

The rating criteria were developed by a committee of State and local

sanitarians, engineers, and installers. The soils data was provided by

the USDA Natural Resources Conservation Service (NRCS), and the performance

and site conditions for a typical system were defined. This information

provided a standard against which various combinations of properties of

soils within Connecticut could be compared.

The engineering and installation practices used to overcome various soil

limitations were listed, and their costs estimated. This information was

used to identify limitations and costs associated with installing an SSDS

on each soil in Connecticut. Soils with no or minor limitations for the

installation of an SSDS were rated the highest. Conversely, soils requiring

extensive site modification and design were rated the lowest. The ease of

system installation, and therefore cost, formed the basis of the rating scheme.

Rating Classes

The rating class definitions refer to installation of an SSDS that meets

State and local health code regulations. Soils with high potential have

characteristics that meet the performance standard. A typical system can

be installed at a cost of "x", which represents the going rate for installing

an SSDS. The actual value of x varies depending upon many factors unrelated

to soil properties.

The cost of installing a leaching field is expressed as a multiple of x and

called the cost factor. For example, a cost factor of 3x to and 3.5x means

that the estimated cost of installing a leaching field in the particular

soil ranges from 3 to 3.5 times m