Mississippi Administrative Code › Title 15 - Mississippi Department of Health › Part 18 - Division of On-site Wastewater › Subpart 77 - On-site Wastewater Regulations › Chapter 5 - INDIVIDUAL ONSITE WASTEWATER DISPOSAL DESIGN STANDARD › Subchapter 6 - SUBSURFACE DRIP IRRIGATION › Rule 15-18-77-5.6.3 - Design

Current through June 25, 2024
Utilizing USDA soil groups as classified by textures is
						the most appropriate criteria on which to base loading rates for this system.
						The size of the disposal field shall be based on the most restrictive soil,
						naturally occurring within 2 feet of the ground surface or to a depth of 1 foot
						below the trench bottom, whichever is deeper. Criteria and techniques for soil
						and site evaluation can be found in Chapter 03 Regulation Governing Residential
						On-site Wastewater Disposal Systems: Soil and Site Evaluation.
1. Prior to the design of the Subsurface Drip
					 Irrigation System, the suitability of the site must be demonstrated through
					 acceptable soil permeability rates, acceptable soil conditions (Table I) and
					 other topographic characteristics. The design and construction of the
					 Subsurface Drip Irrigation System must conform to the drip tubing
					 manufacturer's specification (Figure 1).
2. A minimum of 6 inches of naturally
					 occurring soil must be present above a restrictive horizon or a predominantly
					 gray soil (50%) before placement of appropriate fill. Subsurface Irrigation
					 System is not recommendable on hydric soils conditions.
3. Except where hydric soils are present, a
					 clean fill material may be used to overcome seasonal water table limitation.
					 The fill material shall consist of a minimum of 50 percent sand particles equal
					 to or greater than 0.25
mm
. Clay content shall be 20 percent
					 or less. Organic matter shall be removed from the native soil surface prior to
					 placing and incorporating the fill. This fill must be incorporated into the
					 native soil to prevent a textural interface from developing. When fill material
					 is used the entire fill area must be sodded to prevent erosion, or other
					 effective erosion control methods used. The full depth of fill material must
					 extend at least 2 feet in all directions from drip tubing and at that point
					 shall be sloped at a grade of no steeper than 3 to 1.
4. In soils that contain a restrictive
					 horizon, within 5 feet of the surface, there shall be a minimum of 12 inches of
					 unsaturated soil between the bottom of the drip tubing and any perched or
					 seasonal water table.
5. In soils
					 that do not contain a restrictive horizon, within 5 feet of the surface, there
					 shall be a minimum of 24 inches of unsaturated soil between the bottom of the
					 drip tubing and any perched or seasonal water table.
6. Drip tubing must be installed a minimum of
					 6 inches deep. The maximum depth may not exceed 18 inches. In all cases there
					 shall be a minimum of 12 inches separation between the water table and
					 restrictive horizon.
7. Minimum
					 separation between drip emitter shall be 2 feet. A 2 foot horizontal separation
					 must be between drip tubing lines for slopes of less that 20 percent for slopes
					 of 20 percent or greater shall be a minimum of 3 foot horizontal separation.
8. Drip tubing shall either be
					 placed 4 inches lower than the supply manifolds or water breaks shall be used
					 to prevent effluent from flowing along the drip tubing to the supply manifold
					 trenches.
9. Valves, fittings,
					 level control switches and all other components must be designed and
					 manufactured to resist the corrosive effects of wastewater and common household
					 chemicals.
10. Electrical equipment
					 shall be protected with safety devices (overload interrupting devices, fuses,
					 etc.). Electrical equipment shall comply with appropriate
National
					 Electrical Manufacturer's Association (NEMA)
requirements. Electrical
					 component parts shall be covered by the manufacturer's limited
					 warranty.
Miss Code Ann.
						§
												41-67-3