Section R317-401-6 - Construction and Installation of Irrigation Systems6.1. Each distribution zone shall have a minimum effective irrigation area for the soil characteristics and vegetation needs.6.2. The area of a distribution zone shall be equal to the total length of the perforated pipe sections within the distribution zone multiplied by the width of the proposed trench. The required square footage shall be determined using Table 4 or Table 5. TABLE 4
Subsurface Irrigation System Design
Soil Characteristics | Subsurface Irrigation System Area Loading, gallons of graywater per day per square foot |
Coarse Sand or Gravel | 5 |
Fine Sand | 4 |
Sandy Loam | 2.5 |
Sandy Clay Loam | 1.6 |
Clay Loam | 1.1 |
Clay with Sand or Gravel | 0.8 |
TABLE 5
Drip Irrigation System Design
Soil Characteristics | Minimum Number of Emitters, per gallon per day | Maximum Emitter Discharge, gallons per day |
Coarse Sand or Gravel | 0.6 | 1.8 |
Fine Sand | 0.7 | 1.4 |
Sandy Loam | 0.9 | 1.2 |
Sandy Clay Loam | 1.1 | 0.9 |
Clay Loam | 1.6 | 0.6 |
Clay with Sand or Gravel | 2.0 | 0.5 |
6.3. The lowest point of any distribution zone shall be at least two vertical feet above the maximum groundwater table. Applicant shall provide sufficient groundwater data to the regulatory authority. Subsection R317-4-4.1.B.4 may be used to determine maximum groundwater elevation.6.4. Subsurface drip irrigation system. Subsurface drip irrigation systems shall be constructed so that:
(a) A 140 mesh or 115 micron filter with a capacity of 25 gallons per minute minimum shall be used to prevent drip irrigation system clogging;(b) The filter backwash and flush discharge shall be captured, contained, and discharged to the sewer system or approved onsite wastewater system; (i) filter backwash water and flush water may not be used for any purpose;(ii) sanitary procedures shall be followed when handling filter backwash and flush discharge of graywater;(c) Emitters recommended by the manufacturer shall be resistant to root intrusion and suitable for subsurface and graywater dispersal;(d) Each irrigation zone shall include the minimum number of emitters required to meet the daily graywater flows as defined in Table 5;(e) Minimum spacing between emitters should be 12 inches in any direction, or as recommended by the manufacturer;(f) The system shall provide user controls such as valves, switches, timers, and other controls as appropriate, to rotate the discharge of graywater between distribution zones;(g) All drip irrigation force mains and manifolds shall: (i) meet requirements of Table 7;(ii) be connected with schedule 40 fittings;(iii) be connected as per manufacturer's specifications, inspected and pressure tested at 40 pounds per square inch and shown to be drip tight for five minutes, before burial; and(iv) be buried at a minimum depth of six inches;(h) Lateral distribution lines may be PE or flexible PVC tubing and shall be covered to a minimum depth of six inches;(i) Pressure at the emitter shall meet the manufacturer's recommendations; and(j) Each distribution zone shall include a flush valve, and where applicable, an anti-siphon valve to prevent back siphonage of water and soil.6.5. Subsurface Irrigation System. Subsurface irrigation systems consisting of pipe and gravel or chambers may be used for dispersal of graywater.
(a) Perforated pipe sections shall be a minimum three-inch diameter and shall be constructed of perforated high-density polyethylene pipe, perforated ABS pipe, perforated PVC pipe, or other approved materials as required in Table 7, provided that sufficient openings are available for distribution of the graywater in the trench area. Material, construction and perforation of the piping shall be in compliance with the requirements of the International Plumbing Code and local building code.(b) A subsurface irrigation system shall be constructed in accordance with Table 6.(c) Aggregate shall be placed in the trench to the depth and grade required by Table 6. The aggregate shall then be covered with barrier material to prevent closure of voids with backfill.(d) Chamber systems shall be installed as per manufacturer's specifications. All chambers shall meet requirements listed in Rule R317-4.(e) Backfill may not be placed over the barrier material or chambers prior to inspection and approval by the regulatory authority. TABLE 6
Lateral Construction Details
Description | Minimum | Maximum |
Number of drain lines per zone | 1 | --- |
Length of each perforated line, feet | --- | 150 |
Bottom width of trench, inches | 6 | 36 |
Total depth of trench, inches | 9 | 36 |
Spacing of lines, wall to wall, feet | 4 | --- |
Depth of backfill, inches | 6 | --- |
Depth of aggregate cover over lines, inches | 2 | --- |
Depth of aggregate beneath lines, inches | 3 | --- |
Grade of drain lines, inches per 100 feet | Level | 4 |
TABLE 7
Minimum Standards for Graywater Sewer and Distribution Pipe Materials (a)
Acceptable Graywater Pipe Materials
Type of Pipe | Minimum Standard |
Acrylonitrile-Butadiene Styrene (ABS) | ASTM (b), D-2680, D-2751, F-628 |
Polyvinyl Chloride (PVC) | ASTM D-2665, D-3033, D-3034 |
Acceptable Distribution Pipe Materials
Type of Pipe | Minimum Standard |
ABS | ASTM D-2661, D-2751 |
Polyethylene (PE) | Smooth Wall ASTM D-3350 |
PVC | ASTM D-2665, D-3033, D-3034, D-2729(c) |
Notes:
(a) Each length of graywater sewer and distribution pipe shall be stamped or marked.(b) American Society for Testing and Materials.(c) Although perforated PVC, ASTM D-2729 is approved for absorption system application, the solid-wall version of this pipe is not approved for any application.Utah Admin. Code R317-401-6
Amended by Utah State Bulletin Number 2020-08, effective 3/26/2020