Alabama Administrative Code
Title 420 - ALABAMA STATE BOARD OF HEALTH
Chapter 420-3-1 - ONSITE SEWAGE TREATMENT AND DISPOSAL
Site Evaluation
Section 420-3-1-.40 - Soil Testing Depth Requirements
Current through Register Vol. 42, No. 11, August 30, 2024
(1) The correct testing depth to determine permeability shall be the least permeable horizon that is at or within 18 inches below the EDF bottom or EDS discharge area. If a restriction is present, the correct testing depth shall be the least permeable horizon that is at or within the required MVS depth below the EDF bottom. Percolation tests maybe conducted at different depths to aid in this determination. In no case shall the test depth be less than 12 inches.
(2) Sites where the EDF bottom will be installed above the natural ground surface shall be evaluated at a depth of 12 inches from the natural ground surface, prior to adding fill. See 420-3-1-.61 Controlled Fill Mound Systems.
(3) A site having more permeable soils located below slowly permeable clay layers (but not a restrictive layer or horizon, see Table 7 footnote 4), and which can still meet the required separation distance above the ASHES or other limiting layers, may be considered for an EDF. However, trench bottoms shall not exceed 60 inches below the natural surface.
(4) The LHD may require observation pits where questions arise about soil conditions or where soils are difficult to evaluate with manually operated equipment.
Previous Rule .64 was renumbered .40 per certification published December 30, 2022; effective February 13, 2023.
Authors: David Gray, John Clement, Boyd Rogers, Richard Smith
Statutory Authority: Code of Ala. 1975, §§ 22-2-2(4); 22-2-2(6); 22-10-1, et seq.; 22-26-1et seq.
