§ 73.166. Design of pressure distribution for individual residential spray irrigation systems.
(a) Design of pressure distribution in an individual residential spray irrigation system shall comply with the following:
(1) Conveyance of effluent from the storage tank to the spray field shall be through a delivery pipe sized to minimize friction loss.
(2) Check valves shall be prohibited on delivery lines. Air relief valves may be placed at high points in the delivery lines to prevent air locks.
(3) The delivery line and laterals shall be designed so that the effluent will drain back to the storage tank or otherwise designed to prevent freezing of the lines and sprinkler heads.
(4) Individual laterals shall be sized to minimize friction loss. The hydraulic loss (friction and elevation changes) within a lateral shall be less than 20 % of the operating head of the sprinklers.
(5) Design of laterals should include consideration of measures to prevent freezing of lines.
(6) Spacing of laterals and sprinklers shall provide for distribution of the effluent over the spray field using a design nozzle pattern that does not overlap adjacent spray nozzle wetted perimeters.
(7) Design of the spray field shall be based on the manufacturer’s sprinkler specifications listing operating head, wetted diameter, nozzle size and discharge rate which shall be attached to the system design.
(8) Sprinklers shall be installed on risers 18 inches to 5 feet above grade level.
(9) Sprinklers shall be kept clear of obstructing vegetation for a radius of 5 feet.
(10) The design head of the sprinkler may not exceed the manufacturer’s specifications for each system component.
(11) The minimum pump capacity shall equal the total discharge from all sprinklers when operating at design head.
(12) Total pump head shall be calculated by addition of all losses incurred due to elevation changes, pipe and fitting friction losses and the design head of the sprinkler.
(13) The effluent shall be discharged to the spray field once per day. A manual override shall be installed in the system to allow interruption of this spray cycle when weather conditions are not conducive to spraying.
(14) The permittee shall conduct a test pressurization of the completed spray field in the presence of the sewage enforcement officer prior to covering the piping system from view. During the test, the sewage enforcement officer shall confirm that all joints are water tight, the design head is achieved and the manual override is functional.
Authority The provisions of this § 73.166 issued under section 9 of the Pennsylvania Sewage Facilities Act (35 P. S. § 750.9); The Clean Streams Law (35 P. S. § § 691.1—691.1001); and section 1920-A of The Administrative Code of 1929 (71 P. S. § 510-20).
Source The provisions of this § 73.166 adopted November 7, 1997, effective November 8, 1997, 27 Pa.B. 5877.
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