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 more than that of installing a field in a

soil with high potential. The cost factors provide relative estimates of

the costs of installing an SSDS.

The soil potential ratings and associated cost factors, assuming a typical

system, are defined below.

High Potential - These soils have the best combination of characteristics

or have limitations that can be easily overcome using standard installation practices.

The cost factor is 1x to 2.0x.

Medium Potential - These soils have significant limitations, such as low

percolation rate, that generally can be overcome using commonly applied designs.

The cost factor ranges from 2.0x to 2.5x.

Low Potential - These soils have one or more limitations, such as low percolation

rate and depth to seasonal high water table, that require extensive design and

site preparation to overcome. The cost factor ranges from 2.5x to 3.5x.

Very Low Potential - These soils have major soil limitations, such as depth to

bedrock, that require extensive design and site preparation to overcome. A permit

for an SSDS may not be issued unless the naturally occurring soils meet the minimal

requirements outlined in the State health code. It is unlikely that these soils

can be improved sufficiently to meet State health code regulations. The cost factor

ranges from 4.25x to 6.0x.

Extremely Low Potential - These soils have multiple major limitations, such as

flooding and depth to seasonal high water table, which are extremely difficult

to overcome. A permit for an SSDS may not be issued unless the naturally occurring

soils meet the minimal requirements outlined in the State health code. It is

unlikely that these soils can be improved sufficiently to meet State health code

regulations.

Not Rated - Areas labeled Not Rated have soil characteristics that show extreme

variability from one location to another. The work needed to overcome adverse soil

properties cannot be estimated. These areas commonly are urban land complexes or

miscellaneous areas. An on-site investigation is required to determine soil

conditions at the site.

This data set is a digital soil survey and generally is the most

detailed level of soil geographic data developed by the National

Cooperative Soil Survey. The information was prepared by digitizing

maps, by compiling information onto a planimetric correct base

and digitizing, or by revising digitized maps using remotely

sensed and other information.

This data set consists of georeferenced digital map data and

computerized attribute data. The map data are in a soil survey area

extent format and include a detailed, field verified inventory

of soils and miscellaneous areas that normally occur in a repeatable

pattern on the landscape and that can be cartographically shown at

the scale mapped. The soil map units are linked to attributes in the

National Soil Information System relational database, which gives

the proportionate extent of the component soils and their properties.