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Illinois Administrative Code (Last Updated: March 27, 2024) |
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TITLE77. PUBLIC HEALTH |
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PART905. PRIVATE SEWAGE DISPOSAL CODE |
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Section905.APPENDIX A. Illustrations and Exhibits |
§905.ILLUSTRATION H. Subsurface Seepage System Size Determination
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Section 905.APPENDIX A Illustrations and Exhibits
Section 905.ILLUSTRATION H Subsurface Seepage System Size Determination
Section 905.EXHIBIT A Gravel System
Time (minutes) required for last 6 inches of water to fall
FOR RESIDENTIAL USE Required Absorption Area (sq ft)/bedroom)
FOR INSTITUTIONAL OR COMMERCIAL USE Allowable application rate (GPD/sq ft) (5)
Recommended depth from bottom of the trench to the limiting layer
18 - 60
200
1.0
90
210
.95
3 feet
120
235
.85
150
265
.75
180
290
.69
240
320
.62
300
350
.57
2 feet
360
385
.52
NOTE:
1.
Absorption area is figured as trench bottom area in absorption trenches and bottom area in seepage beds.
2.
Seepage beds require 1½ times the seepage field absorption area specified.
3.
Over 360 is unsuitable for subsurface seepage systems.
4.
Under 18 is unsuitable for subsurface seepage systems.
5.
Divide the required total gallons per day by this number to get the number of square feet required
(Source: Amended at 20 Ill. Reg. 2431, effective March 15, 1996)
Section 905.APPENDIX A Illustrations and Exhibits
Section 905.ILLUSTRATION H Subsurface Seepage System Size Determination
Section 905.EXHIBIT B Gravelless System
Time (minutes) required for last 6 inches of water to fall
FOR RESIDENTIAL USE Required Absorption Area (sq ft)/bedroom)
FOR INSTITUTIONAL OR COMMERCIAL USE Allowable application rate (GPD/sq ft) (5)
Recommended depth from bottom of the trench to the limiting layer
8 inch
10 inch
8 inch
10 inch
18 – 60
100
70
2.00
3.00
90
105
70
1.90
2.86
3 feet
120
120
80
1.66
2.50
150
135
90
1.48
2.22
180
145
100
1.38
2.00
240
160
110
1.25
1.82
300
175
120
1.14
1.66
2 feet
360
195
130
1.0
1.54
NOTE:
1.
Over 360 is unsuitable for subsurface seepage systems.
2.
Under 18 is unsuitable for subsurface seepage systems.
3.
Divide the required total gallons per day by this number to get the number of lineal feet required.
(Source: Amended at 20 Ill. Reg. 2431, effective March 15, 1996)