Ill. Admin. Code tit. 77, pt. 905, app A, ILLUSTRATION M, exh. A

Current through Register Vol. 49, No. 2, January 10, 2025

Exhibit A - Loading Rates in Square Feet Per Bedroom and Gallons/Square Feet/Day

Design Group	Soil Group (Most Limiting Layer)	Minimum Separation To Limiting Layer¹	Permeability Range	Size of System
Design Group	Soil Group (Most Limiting Layer)	Minimum Separation To Limiting Layer¹	Permeability Range	Residential Reg. Absorption (ft²/bedroom)	Institutional/Commercial Allowable Application Rate (GPD/ft²)
I	1A	NR³	Very Rapid	NR³	NR³
II	2A; 2B; 2K	3 feet	Rapid	200	1.0
III	3B; 3K	3 feet	High Moderately Rapid	220	0.91
IV	3A; 3L; 4D; 4K	3 feet	Low Moderately Rapid	240	0.84
V	4A;; 4B; 4H; 4L; 5D	3 feet	Very High Moderate	265	0.75
VI	4F; 4M; 5B	3 feet	High Moderate	290	0.69
VII	4N; 5A; 5C; 5H; 5K; 6D	2 feet	Moderate	325	0.62
VIII	4O; 5E; 5I; 5L; 6A; 6B; 6E; 6H; 6K	2 feet	Low Moderate	385	0.52
IX²	5F; 5M; 6C; 6L; 7D; 7F	2 feet	High Moderately Slow	445	0.45
X²	5G; 6F; 6I; 7E; 7C; 7H	2 feet	Low Moderately Slow	500	0.40
XI²	5N; 6G; 6J; 6M; 7F; 7I	2 feet	Slow	740	0.27
XII²	7G; 7J; 7L; 8E; 8I	2 feet	Very Slow	1000	0.20
XII²	5O; 6N; 6O; 7M; 7N; 7O; 8J; 8M; 8O	NR³	NR³	NR³	0.00
XIII	9	SUBSURFACE DISPOSAL NOT RECOMMENDED

NOTES:

¹ Limiting layers include fragipans; bedrock; compact glacial tills; seasonal high water table or other soil profile features that will materially affect the absorption of liquid from the disposal field.

² Soils in this group are less than the minimum percolation rate established in Appendix A, Illustration H as suitable for subsurface seepage systems.

³ NR = Subsurface disposal system not recommended.

Ill. Admin. Code tit. 77, pt. 905, app A, ILLUSTRATION M, exh. A

Amended at 37 Ill. Reg. 14994, effective August 28, 2013