Oregon Administrative Rules › Chapter 340 - DEPARTMENT OF ENVIRONMENTAL QUALITY › Division 73 - CONSTRUCTION STANDARDS › Section 340-073-0055 - Dosing Assemblies: Effluent Pumps, Controls and Alarms, and Dosing Siphons

Current through Register Vol. 63, No. 7, July 1, 2024
(1) Design and
			 equipment must emphasize ease of maintenance, longevity, and reliability of
			 components and must be proven suitable by operational experience, test, or
			 analysis acceptable to the department.
(2) Easy means of electrical and plumbing
			 disconnect must be provided. All apparatus must be constructed and installed to
			 facilitate ease of service without having to alter any other
			 component.
(3) Component materials
			 must be durable and corrosion-resistant such as Type 316 stainless steel,
			 suitable plastics, or 85-5-5 -5 bronze.
(4) Pumps, Siphons, Controls, and Alarms. All
			 pumps, siphons, controls and related apparatus must be field tested under
			 working conditions and found to operate and perform satisfactorily. Electrical
			 components used in onsite systems must comply with applicable requirements of
			 the State of Oregon Electrical Code and the standards in this section.
(a) Motors must be continuous-duty with
			 overload protection.
(b) Pumps must
			 have durable impellers of bronze, cast iron, or other materials approved by the
			 department.
(c) Submersible pumps
			 must be provided with an easy, readily accessible means of electrical and
			 plumbing disconnect and a noncorrosive lifting device as a means of removal for
			 servicing.
(d) Except where
			 specifically authorized in writing by the agent, the pump or siphon must be
			 placed within a corrosion-resistant screen or vault with a filtering device
			 that extends into or above the tank's service access manhole. The screen or
			 filtering device must have at least 12 square feet of surface area, with
			 1/8-inch openings. In lieu of the screen, the agent may allow other methods
			 with equal or better performance in preventing the passage of suspended solids
			 to the pump or siphon.
(e) Pumps
			 must be automatically controlled by float switches with a minimum rating of 12
			 amps at 115 volts A.C. or by a department-approved, equally reliable switching
			 mechanism. Except as otherwise required in this division, the switches must be
			 installed so that no more than 20% of the projected daily sewage flow is
			 discharged each cycle. The pump "off" level must be set to maintain the liquid
			 level above the top of the pump or to the designer and pump manufacturer's
			 specifications.
(f) An audible and
			 visual high water level alarm with manual silence switch must be located in or
			 near the building served by the pump. Only the audible alarm may be
			 user-cancelable. The switching mechanism within a dosing tank or chamber
			 controlling the high water level alarm must be located so that at time of
			 activation the tank has a remaining volume equal to 1/3 or more of the system's
			 design flow, as measured below the invert of the inlet, for effluent storage.
			 The alarm and pump must be on separate circuits. Commercial applications using
			 duplex pumps are not subject to the 1/3 storage reserve requirement.
(g) When a system has more than one pump, the
			 department may require the pumps to be wired into the electrical control panel
			 to function alternately after each pumping cycle. If either pump should fail,
			 the other pump will continue to function while the high water level alarm
			 activates. A cycle counter must be installed in the electrical control panel
			 for each pump.
(h) All pump
			 installations must be designed with adequate sludge storage volume below the
			 effluent intake level of the pump.
(i) All commercial systems with a design flow
			 greater than 600 gallons must be constructed in duplex (two or more alternating
			 pumps) unless otherwise authorized in writing by the department. Controls must
			 be provided such that an alarm will signal when one1 of the pumps
			 malfunctions.
(j) All pumps serving
			 commercial systems must be operated through a pre-manufactured electrical
			 control panel. A means of monitoring pump performance through the use of
			 elapsed-time meters and cycle counters is required.
(k) Where multiple pumps are operated in
			 series, an electrical control panel must be installed to prevent the operation
			 of a pump or pumps preceding a station that experiences a high level alarm
			 event.