Section 25-13 - Pressure Distribution Systems (a) General Design Requirements: - (i) The basic elements of a pressure distribution system include a dosing tank, filter, and a means to deliver specified doses to a small diameter pipe network within a soil absorption system. Pressure distribution is required for mound systems or for bed systems with a width greater than twenty-five (25) feet.
- (ii) Pumps must be sized to match the distribution system curve or demand. Pumps shall be designed for sewage pumping applications and be accessible from the ground surface.
- (iii) The control system for the pump and dosing tank shall, at a minimum, consist of a "pump off" switch, a "pump on" switch, and a "high liquid alarm".
- (A) All electrical connections must be made outside of the chamber in either an approved weatherproof box or an explosion-proof junction box.
- (B) The wiring from the junction box to the control box must pass through a sealing fitting to prevent corrosive gases from entering the control panel.
- (C) All wires must be contained in solid conduit from the dosing chamber to the control box.
- (iv) The pressure transport piping between the tank and the soil absorption system shall be designed to prevent freezing.
- (A) The ends of lateral piping shall be constructed with long sweep elbows or an equivalent method to bring the end of the pipe to finished grade. The ends of the pipe shall be provided with threaded plugs, caps, or other devices to allow for access and flushing of the lateral.
- (B) All joints in the manifold, lateral piping, and fittings shall be solvent-welded using the appropriate joint compound for the pipe material. Pressure transport piping may be solvent-welded or flexible gasket jointed.
- (C) Where automatic siphons or other devices are used, they shall be designed to empty the dosing tank in less than ten (10) minutes.
- (v) The pressure distribution system shall have a combination of at least three (3) vertical feet of filter sand and/or unsaturated native soil above the high groundwater level. The filter sand shall conform to ASTM C-33, with less than 2% passing the #200 sieve.
(b) A design package for pressure distribution systems is provided online at the Division's website to assist the applicant in submitting a completed application for coverage under the general permit for small wastewater systems. The worksheet and calculations were prepared by a registered professional engineer employed by the Wyoming Department of Environmental Quality, Water Quality Division. The general design requirements stated in this section are incorporated into the worksheets such that by properly completing the forms and installing the components, the system will comply with these requirements.
020-25 Wyo. Code R. § 25-13