Illinois Administrative Code
Title 77 - PUBLIC HEALTH
Part 905 - PRIVATE SEWAGE DISPOSAL CODE
Appendix A - Illustrations and Exhibits
ILLUSTRATION M - Soil Suitability for On-Site Sewage Design
Exhibit B - Key for Determining Sewage Loading Rates (Gallons/Square Foot/Day)
Structure and Parent Material |
Single grain; Weak ; Platy2 |
Granular, Angular and Subangular Blocky; Prismatic |
Structureless or Massive |
|||||||||||||
Loess: Outwash; Alluvium; Lacustrine8 |
Till3 |
|||||||||||||||
Week |
Moderate; Strong |
Strong |
Moderate; Strong |
Loess; Outwash; Alluvium; Lacustrine8 |
Till3 |
|||||||||||
Moist Consistence |
lo vfr fr |
vfr fr |
fi |
vfr |
fi |
vfr fr |
fi |
fr |
fi |
vfi |
vfr |
fr |
fi |
vfr fr |
fi vfi |
|
Texture |
A |
B |
C |
D |
E |
F |
G |
H |
I |
J |
K |
L |
M |
N |
O |
|
1. Fragmental; Ext. or Very gravelly sand |
> 1.004 |
N/A5 |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
|
2. Sand; Loamy course sand; Loamy sand; Gravelly sand; Coarse sand; Gravelly loamy sand |
1.00 |
1.00 |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
1.00 |
N/A |
N/A |
N/A |
N/A |
|
3. Fine sand; Loamy fine sand; Coarse sandy loam |
0.84 |
0.91 |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
0.91 |
0.84 |
N/A |
N/A |
N/A |
|
4. Sandy loam; Fine sandy loam; Gravelly sandy loam; Gravelly loam; Gravelly silt loam |
0.75 |
0.75 |
N.A |
0.84 |
N/A |
0.69 |
N/A |
N/A |
0.75 |
N/A |
0.84 |
0.75 |
0.69 |
0.62 |
0.52 |
|
5. Loam; Silt loam; Very fine sandy loam; Sandy clay loam; Silt; Very fine sand; Loamy very fine sand; Gravelly clay loam |
0.62 |
0.69 |
0.62 |
0.75 |
0.52 |
0.456 |
0.406 |
0.62 |
0.52 |
N/A |
0.62 |
0.52 |
0.456 |
0.276 |
N/R7 |
|
6. Silty clay loam (<35% c); Clay loam (< 35% c) |
.052 |
0.52 |
0.456 |
0.62 |
0.52 |
0.408 |
0.276 |
0.52 |
0.406 |
0.276 |
0.52 |
0.456 |
0.276 |
N/R |
N/R |
|
7. Silty clay loam (>35% c); Clay loam (>35% c) |
N/A |
N/A |
0.406 |
0.456 |
0.406 |
0.276 |
0.206 |
0.406 |
0.276 |
0.206 |
N/A |
0.206 |
N/R |
N/R |
N/R |
|
8. Sandy clay; Clay |
N/A |
N/A |
N/A |
N/A |
0.206,9 |
N/A |
N/A |
N/A |
0.206,9 |
N/R |
N/A |
N/A |
N/R |
N/A |
N/R |
|
9. Organics; Fragic; Lithic; Paralithic |
---SOIL PROPERTIES HAVE VERY SEVERE LIMITATIONS; SUBSURFACE DISPOSAL NOT RECOMMENDED----- |
FOOTNOTES:
1 Disturbed soils are highly variable and require special on-site investigations.
2 Moderate or strong platy structure for the soil textures in Groups 4, 5 and 6 have a loading rate of 0.40 g/sq.ft/d. Platy structure having firm or very firm consistency or caused by mechanical compaction has a loading rate of 0.0 g/sq.ft/d.
3 Basal glacial tills structured by geogenic processes have the same loading rates as structureless glacial till.
4 This soil group is estimated to have very rapid permeability and exceeds the maximum established rate in Illustration H, Exhibit A.
5 N/A means not applicable.
6 These soil groups are estimated to have moderately slow to very slow permeability and are less than the minimum established rate in Illustration H, Exhibit A.
7 N/R means not recommended. These soils have loading rates considered too low for conventional subsurface disposal.
8 In some areas, lacustrine material may have physical properties similar to glacial till and should be placed in the glacial till columns.
9 Non-swelling (1:1 lattice) clays formed in bedrock residuum have a loading rate of 0.27 g/sq.ft/d. Swelling (2:1 lattice) clays are not recommended for subsurface disposal.