Section R317-401-7 - Construction and Installation of Branched Drain Basin Systems7.1. Branched Drain Basin Construction Details. (a) Mulch shields shall be constructed of a durable material and should be placed for optimum effluent distribution.(b) Aggregate shall be placed in the basin in a manner that will allow proper effluent distribution, prevent ponding, with a minimum depth of 6 inches over graywater flood level, and as required in Table 6.(c) Backfill may not be placed over the mulch shields or flow splitters until after inspection and approval by the regulatory authority.(d) Access to any flow splitter or mulch shield shall be within 6 inches of finished grade.(e) Branched drain basins shall be constructed in accordance with Table 8 and Table 9. TABLE 8
Mulch Basin Sizing
Soil Type | Mulch Basin Loading Rate, gallons of graywater per day per square foot | Maximum gallons per mulch shield per day(a) |
Sand | 5 | 60 |
Loam | 3 | 40 |
Clay | 1 | 20 |
(a) The number of gallons per mulch shield per day is site specific an d the designer may need to decrease the number of gallons per mulch shield when appropriate or as required by the regulatory authority. TABLE 9
Mulch Basin Construction Details
Description | Minimum | Maximum |
Cleanouts | 1 | --- |
3-way Valve or similar (per stub out location) | 1 | --- |
Discharge Points (per stub-out location) | 2 | 16 |
Double Ell Flow Splitter | 1 | --- |
Pipe Diameter | 2 inch | 4 inch |
Pipe Slope | 1/4 inch per foot | --- |
Mulch Shield Volume | 5 gallons | --- |
Air gap in mulch shield above highest perforation | 6 inches | --- |
7.2. Construction, Inspection and Testing. (a) Installation shall conform to the equipment and installation methods described in the approved plans.(b) Any surge tank shall be filled with water to the overflow line prior to and during construction inspection. All seams and joints shall be left exposed and the tank shall remain watertight.(c) The irrigation system shall be installed in the area which has soils similar to the soils which have been evaluated, and has an absorption rate corresponding to the given soil classification.(d) A graywater stub-out may be allowed for future construction, provided it is capped prior to connection to the installed irrigation lines and landscaping. Any stub-out shall be permanently marked: GRAYWATER STUB-OUT, DANGER UNSAFE WATER.(e) A flow test shall be performed throughout the system, from surge tank to the point of graywater discharge. All lines and components shall be watertight.(f) Written operation and maintenance procedures including checklist and maintenance instructions from the designer shall be provided to the owner prior to the regulatory authority issuing written approval or authorization.(g) The installed graywater system shall be operated only after receiving a written approval or authorization from the regulatory authority after the regulatory authority has made the final construction inspection.Utah Admin. Code R317-401-7
Adopted by Utah State Bulletin Number 2020-08, effective 3/26/2020