Type 1 and Type 2 private sewage disposal systems shall be designed to minimum requirements as follows:
A. Pretreatment shall be by septic tank sized for the projected design flow or by a Class I aeration device sized for the projected design flow.
B. Effluent distribution to the absorption trench may be by drop box, distribution box, or low pressure pipe (LPP) distribution.
D. Distribution in the absorption trench shall be by perforated pipe.
E. No perforated pipe shall be located closer than three (3) feet to the distribution device.
F. The invert of the distribution pipe shall be a minimum of six (6) inches above the trench bottom.
G.
1. The square footage of a gravel trench bottom shall be per Column 8 of Table 1 for residential properties and equal to the projected flow in gallons per day (GPD) divided by the assigned domestic wastewater loading rate in gallons per day per square foot (Column 9, Table 1) for non-residential properties.
2. The soil loading rate is determined by the most restrictive permeability within 24 inches below the aggregate in moderate soils, 36 inches below the aggregate in moderately rapid soils and 48 inches below the aggregate in rapidly permeable soils.
3. Illinois Department of Public Health approved chambers will be sized at one (1) lineal foot of chamber per lineal foot of three (3) foot wide gravel trench for those chambers with approved absorption areas of at least three (3) square feet per linear foot; OR
4. Will be sized at one (1) lineal foot of chamber per lineal foot of two (2) foot wide gravel trench for those chambers with approved absorption areas of at least two (2) square feet per lineal foot but less than three (3) square feet per linear foot.
H. The maximum trench length shall be one hundred (100) feet from the distribution device (excluding the solid header).
I. The maximum trench width shall be thirty-six (36) inches; the minimum trench width shall be twelve (12) inches.
J. Trenches shall be separated by a minimum of five (5) feet of undisturbed soil. See Tables VI and IX.
K. The minimum trench depth for a Type 2 system shall be twelve (12) inches into the original soil surface.
L. The minimum depth of gravel in the absorption trench shall be twelve (12) inches with six
(6) inches of gravel beneath the distribution pipe and two (2) inches above. Gravel shall not be placed closer than thirty-six (36) inches to the distribution device.
M. Every Type 1 and Type 2 system shall be covered with a minimum of six (6) inches of earth cover.
N. Where distribution to and into a Type 1 or Type 2 system is by low pressure pipe (LPP), the applicable requirements of § 8.04.540 shall be met.
O. Seepage beds, shall be sized at 1.5 times the absorption area specified in Table I.
P. Type 1 and Type 2 systems shall meet the requirements of all other applicable sections of the Ordinance.
(Ord. O-201711-51-031, passed 11-14-2017)