TABLE I: SOIL SUITABILITY FOR ONSITE WASTEWATER DISPOSAL.

SOIL SUITABILITY FOR ON-SITE WASTEWATER DISPOSAL
TABLE 1 (See Also Corresponding Notes and Illustration 1)
				Size of System
Depth to Seasonal High Groundwater Table from Natural Soil Surface 1	Permeability Range ln/Hr Required Separation 1	System Type	Associated USDA Soil Textures	Maximum Allowable Slope %	Assigned Soil (Basal) Loading Rate (gpd/ft.2)	Assigned Linear Loading Rate (gpd/lf)	Residential Square Foot Per Bedroom	Non- Residential Gallon Per Day Per Square Foot	Percolation Rate for Sizing Mantle for Illinois Raised Filter Bed
					Type 4 & 5 Systems	Type 4 & 5 Systems
>66	Very Rapid 2 greater than 20, 2 foot4 to 4 foot separation	1, 2, 3, 4, 5	Gravelly Sand Coarse Sand	25 2	N/A 2	N/A 2	N/A 2	N/A 2	10 min/in.
60—65		2, 3, 4, 5
54—59		3, 4, 5
24—53		4, 5
12—23		5
>66	Rapid 6 to 20, 2 foot4 to 4 foot separation	1, 2, 3, 4, 5	Loamy Coarse Sand, Sand	25	0.8	10	200	1.0	10 min/in.
60—65		2, 3, 4, 5
54—59		3, 4, 5
24—53		4, 5
12—23		5
>54	Mod Rapid 2 to 6, 2 foot4 to 3 foot separation	1, 2, 3, 4, 5	Fine Sand Gravelly Loam, Gravelly Sandy Loam Sandy Loam, Loamy Fine Sand	20	0.6	8	275	.80	30 min/in.
48—53		2, 3, 4, 5
42—47		3, 4, 5
24—41		4, 5
12—23		5
≥42	Upper Moderate 1.0 to 2.0 18 inch3 to 1 foot separation	1, 2, 3, 4, 5	Very Fine Sandy Loam, Loam Very Fine Sand, Silt Loam, Loam, Sandy Clay Loam, Silty Clay Loam, Clay Loam	15	0.4	6	350	0.70	60 min/in.
36—41		2, 3, 4, 5
30—35		3, 4, 5
18—29		4, 5
12—17		5
≥42	Lower Moderate .6 to 1.0 18 inch3 to 2 foot separation	1, 2, 3, 4, 5	Clay Loam, Silty Clay Loam, Silt Loam	15	0.4	4	480	0.50	100 min/in.
36—41		2, 3, 4, 5
30—35		3, 4, 5
18—29		4, 5
12—17		5
≥42	Mod Slow 5 .2 to .6 18 inch3 to foot separation	1, 2, 3, 4, 5	Silty Clay Loam, Clay Loam, Silty Clay, Clay (Dense Loam Tills)	10	0.2	3	700	0.30	125 min/in.
36—41		2, 3, 4, 5
30—35		3, 4, 5
18—29		4, 5
12—17		5
NOTES CORRESPONDING TO TABLE 1
1. Required separation is measured from the bottom of trench in a type 1, 2 or 3 system, bottom of aggregate in type 4 system or bottom of sand fill in a type 5 system. When a less permeable soil layer is located less than 24 inches in moderate soils, less than 36 inches in moderately rapid soils, or less than 48 inches in rapid soils, from the bottom of trench aggregate or sand fill; the seepage system shall be sized at the more limiting permeability.
2. Not suitable fix development. A variance will be considered when demonstrated that treatment will reduce the groundwater Nitrate levels to less than ten (10) milligrams per liter leaving the property, or the density of domestic wastewater disposal is less than or equal to 1 per 1.5 acres, and the effluent meets the requirements of NSF standard 40.
3. The required separation from bottom of trench or aggregate to the seasonal high groundwater can be reduced to eighteen (18) inches in moderate soils: a) when a type 4 system is used, and when the limiting layer is 18-23 inches from the natural soils surface and/or b) when LPP distribution is utilized and seasonal high groundwater is twenty four (24) inches or greater from the natural soil surface. Refer to columns 1 and 3 in Table 1.
4. The required separation from bottom of aggregate or sand fill to the seasonal high groundwater can be reduced to twenty four (24) inches when a type 4 or type 5 system is used, and when the seasonal high groundwater is 24-53 inches from the natural soil surface and with treatment capacity to reduce groundwater Nitrate levels to less than ten (10) milligrams per liter leaving the property.
5. Systems must be pressurized utilizing duplex pumps alternating to each half of the seepage field or low pressure pipe distribution as specified in section 2000.

 

(Ord. O-201711-51-031, passed 11-14-2017)