New Jersey Administrative Code
Title 7 - ENVIRONMENTAL PROTECTION
Chapter 9A - STANDARDS FOR INDIVIDUAL SUBSURFACE SEWAGE DISPOSAL SYSTEMS
Appendix D

SOIL SUITABILITY CLASSIFICATION OF NEW JERSEY SOILS

Explanation of the Soil Suitability Classification System

The suitability of soil for onsite disposal of sanitary wastewater by means of individual subsurface sewage disposal systems is classified based upon the type and depth of soil limiting zones as outlined below. Definitions and criteria for recognition of soil limiting zones are provided in Subchapters 2 and 5 of this chapter.

The soil suitability classification consists of a Roman numeral from I to III which is indicative of the severity of the limitation and a letter symbol which indicates the type of limiting zone. (In general the limitation is considered more severe when the limiting zone occurs at a shallower depth in or below the soil profile). Where more than one type of limiting zone is present, the primary classification of the soil is based upon whichever limiting zone(s) presents the most severe limitation (highest numerical symbol). Secondary limitations are given based upon limitations which are less severe (lower numerical symbols). The primary classification is stated first, followed by secondary classifications in parentheses. For example, the classification for a soil with a seasonally high water table (top of a regional zone of saturation) at a depth of 1.5 feet and a massive rock substratum at a depth of 7 feet would be IIIWr(IISr).

Where two or more limiting zones are present with the same degree of limitation, a compound symbol is used in primary or secondary classifications, consisting of a Roman numeral showing the degree of limitation together with a letter symbol for each type of limited zone. For example, the classification for a soil with a seasonally high water table at a depth 2.5 feet and a fractured rock substratum at a depth of 3 feet would be IIWrSc.

Soil Suitability Classes of New Jersey Soil Series

The type of standard septic system installation, if any, which can be approved on a specific site depends upon the soil suitability class which must be determined based upon detailed onsite soil evaluation. Such evaluation is costly and would normally not be performed prior to the purchase of land or the granting of preliminary or conceptual approvals for large tracts of land which are to be subdivided for residential or commercial development. In these or other situations where more general information regarding soil suitability is required, preliminary determinations may be made based upon information contained in the county soil surveys which are published by the U.S.D.A.--Soil Conservation Service in cooperation with the N.J. Agricultural Experiment Station and Cook College of Rutgers, The State University. These soil surveys contain descriptions of the various soil series which occur in New Jersey together with maps showing the geographic distribution of the soils. At present, published soil surveys or preliminary field maps are available for every county in the state with the exception of Essex and Hudson.

A soil series is a group of similar soil types having major horizons which are similar in thickness, arrangement and other important characteristics. The soil suitability classes provided for each New Jersey soil series listed below are based primarily upon the soil profile descriptions given in the soil survey reports.

Soil series may be divided into one or more soil phases which differ in the texture of the surface horizon, stoniness or some other property. Although soil phase differences may affect design and construction requirements, they are generally not a factor in determination of the soil suitability class given for a particular soil series. In some cases a soil series may have one or more variants which may differ significantly with respect to the types or depths of soil limiting zones. In such cases each variant is treated as a separate soil type with respect to the classification.

Each soil series is characterized by a range of soil profile characteristics so that two or more soil suitability classes may be possible for a given soil series. The soil suitability classes given below are those which are considered most typical for a given soil series. Other soil suitability classes are possible depending upon conditions which may vary from location to location.

Soil survey maps delineate the boundaries of soil mapping units in which a specific soil series, soil phase, soil complex, association or other grouping is predominant. Within every soil mapping unit however, there may be areas of dissimilar soils which are too small and scattered or otherwise impractical to show at the scale of mapping used. For this reason, use of the soil survey is not a substitute for onsite soil evaluation when detailed information for a specific site is required.

Many soil series in the coastal plain region of southern New Jersey are underlain by stratified sedimentary formations which consist of layers of contrasting grain size. In some cases layers of highly permeable sand and gravel may alternate with hydraulically restrictive layers of silt and clay. Where hydraulically restrictive layers occur at depths less than nine feet they will be a determining factor for the soil suitability classification. The presence of such layers below a depth of five feet however, is generally not indicated in the soil survey reports and therefore may not be reflected in the soil suitability classes given here. As a result, coastal plain soils series which are classified as having no limitation (Roman numeral I) with respect to hydraulically restrictive horizons and substrata may in some locations have IIHr or IISr limitations. In other cases, soil series which are assigned classifications of IISr or IIISr may in some locations have permeable substrata at depths below the extent of soil survey data such that a classification of IIHr or IIIHr may be appropriate.

In the northern portion of the state many soil series are described as having bedrock substrata at shallow depths below the soil profile. Soil survey reports generally do not provide information relative to the permeability of these rock substrata. Rock substrata underlying soil profiles of the same soil series may often range from excessively permeable to relatively impermeable. Soil suitability classes are given to represent those conditions which are considered most typical for a soil series. In many cases, however, soil series which are given classes of I or IISc may in some locations have the more severe limitations associated with classes IISr or IIISr. Classifications of rock substrata given here must be regarded as preliminary in nature and may be subject to modification based upon detailed onsite evaluation and testing.

Following is a listing of miscellaneous mapping unit designations which do not consist of any one specific soil series or soil series variant. In general these mapping units cannot be assigned a soil suitability class due to extreme variability or a lack of data. The type of limitations which are generally associated with these mapping units are indicated below: