Each soil group number is based off of the number represented in the USDA "Soil Survey Of Jo Daviess County, Illinois". The following soil groupings are used as a guideline. If the soil scientist finds soil characteristics that are not usual for a particular soil type, such as soil depth or soil texture, and the information can be substantiated and documented, then the health authority can change the drainfield sizing or system type to better reflect the soils characteristics.
A. Group I:
1. Group I of soils exhibits the following characteristics: deep, greater than five feet (5') to bedrock; good drainage (well or moderately well); no seasonal wetness closer than four feet (4') from the surface. In instances where seasonal wetness is closer than four feet (4') from the surface, curtain drains may be required to maintain a minimum of two feet (2') of soil below the trench bottoms which is protected from seasonal wetness. Soil textures are dominantly silt loam, silty clay loam, and loam. Soil colors are dominantly yellowish brown and brown in the subsoils. Parent material is loess and silty alluvium. Upland or stream terraces are not subject to flooding.
2. Soil types in this group are: 36B, 36C, 87A, 175B, 175D2, 274C2, 274D2, 274E2, 274F, 279B, 279C2, 279D2, 280B2, 280C2, 280D2, 280E2, 280F, 386B, 386C2, 680C.
3. Drainfield sizing is three hundred (300) square feet per bedroom for residential use/.67 gallon per square foot per day application rate for commercial.
B. Group II:
1. Group II of soils consists of deep, greater than five feet (5') to bedrock; good drainage (well and moderately well); and no seasonal wetness closer than four feet (4') from surface. In instances where seasonal wetness is closer than four feet (4') from the surface, curtain drains may be required. Soil textures are dominantly loam, silty clay loam, light silty clay, and clay loam. Soil colors are brown, reddish brown and strong brown in subsoils. Parent material is loess/glacial till, glacial till eighteen inches (18") thick. Upland or stream terraces are not subject to flooding.
2. Soil types in this group are: 27D2, 119C2, 419C2, 755F2.
3. Drainfield sizing is four hundred (400) square feet per bedroom for residential use/.5 gallon per square foot per day application rate for commercial.
C. Group III:
1. Group III is made up of soils that are deep, greater than five feet (5') to bedrock. Soil color indicates a need for tile drainage (somewhat poor to poorly drained). Soil textures are dominantly loam, silty clay loam, silt loam, and light clay loam. Soil colors are grayish brown or yellowish brown with mottles or gray to olive gray with brownish mottles. Uplands or stream terraces are not subject to frequent flooding. Parent material is loess and silty alluvium.
2. Soil types in this group are: 41B, 61B, 68, 172, 278B, 8284, 7430B, 8070, 8239.
3. Drainfield sizing is three hundred (300) square feet per bedroom for residential use/.67 gallon per square foot per day application rate with curtain drain for commercial use.
D. Group IV:
1. Group IV consists of shallow soils less than five feet (5') to bedrock; good drainage (well and moderately well). Soil textures are dominantly loam, silt loam, silty clay loam and clay loam with a thin layer (usually less than 12 inches of silty clay or clay residuum). Soils colors are yellowish brown, brown, strong brown and reddish brown. Uplands. Parent material is generally loess over dolomite residuum and dolomite.
2. Soil types in this group are: 29C2, 29D2, 429B2, 429C2, 429D2, 429E2, 403D, 540C2, 681E, 731B, 731C2, 731D2, 785F, 785G, 873D2, 873E2, 905F, 928D2.
3. These soils are not suitable for a conventional drainfield.
E. Group V:
1. Group V consists of soils developed in shale bedrock that is at depths of less than five feet (5'). Drainage is fair to poor (well to poorly drained). Seasonal wetness (perched water) is at depths just above shale. Soil colors are yellowish brown, brown or gray brown with mottles above the shale. Shale is gray, greenish gray, and olive brown with mottles. Soil textures are silt loam, silty clay loam, silty clay over clay shale. Uplands.
2. Soil types in this group are: 417B, 417C2, 417D2, 417E2, 417F, 418B, 418C2, 418D2, 547C2, 547D2, 547E2, 572B, 732B, 745B, 753B, 753C2, 753D2.
3. These soils are not suitable for a conventional drainfield.
F. Group VI:
1. Group VI consists of soils that are on bottomlands and upland drainageways that are subject to frequent flooding for long periods that will adversely affect septic drainfields. Parent material is silty alluvium.
2. Soil types in this group are: 3077, 3333, 366, 8415, 3451, 3579, 1334.
3. These soils are not suitable for a conventional drainfield.
G. Group VII:
1. Group VII consists of soils that are very sandy at shallow depths of two feet (2'). These soils do not contain enough fine soil particles (clay) to adequately treat effluent and may cause ground water pollution.
2. Soil types in this group are: 53D, 88B, 88D, 565B, 565C2, 779F, 800.
3. These soils are not suitable for a conventional drainfield.
H. Group VIII:
1. Group VIII consists of soils that are deep and drainage is restricted (somewhat poor). Soil textures are silt loam and silty clay loam in the upper part over silty clay and clay. Soil colors are yellowish brown to gray brown in the upper part and reddish brown or gray brown with mottles in the lower part. High stream terrace topographic position. Parent material is loess/laucaustrine clay.
2. Soil types in this group are: 261, 569C2, 569F2, 576.
3. These soils are not suitable for a conventional drainfield. (Ord., 4-7-2008)