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)