2019.02.04 CC Packet - Laserfiche WebLink

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Effective April 28, 2015 Chapter Four Subsurface Sewage Treatment System Regulations SECTION 15 DOSING OF EFFLUENT 15.1 General. When pumping or dosing is necessary, it must comply with this Section. 15.2 Pump Tanks. (1) Pump tanks shall meet or exceed the requirements of Section 13.2 or 13.3. All dosing chambers must be vented. Pump tanks shall have a maintenance hole with a minimum diameter of 20 inches (least dimension) which allows access and removal of any plumbing or other device. These maintenance holes shall meet or exceed the requirements of Section 13.17 and Section 13.18 of this Chapter. (2) The pump, pump controls, and pump discharge line must be installed to allow access for servicing or replacement without entering the pump tank. (3) The pump tank must either include an alternating two -pump system or have a minimum total capacity of 500 gallons for design flow values of 600 gallons per day or less or 100 percent of the design flow for design flow values of greater than 600 gallons per day. (4) An SSTS with a pump must employ an alarm device to warn of failure. (5) The inlet of pumps must be elevated at least four inches from the bottom of the pump tank or protected in some other manner to prevent the pump from drawing excessive settled solids. (6) Electrical installations must comply with applicable laws and ordinances including the most current codes, rules, and regulations of public authorities having jurisdiction and with Minnesota Rule, Chapter 1315.0200, which incorporates the National Electrical Code. (7) MSTS and Other Establishments must include an alternating two -pump system and have a minimum capacity of 50 percent of the design flow. 15.3 Pumps for Gravity Distribution. If a pump is used to lift effluent into a gravity distribution system, the following apply: (1) The pump must discharge at least 10 gallons per minute but no more than 45 gallons per minute. (2) The pump must be constructed and fitted with sound, durable, and corrosion -resistant materials. (3) The pump must have sufficient dynamic head for both the elevation difference and friction loss. 15.4 Pumps for Pressure Distribution. Pumps used for pressure distribution must meet the following requirements: (1) Pumps must be constructed and fitted with sound, durable, and corrosion -resistant materials. (2) The pump discharge capacity must be based on the perforation discharges for a minimum average head of: (A) 1.0 foot for'/4-inch and 3/16-inch perforations for dwellings; (B) 2.0 feet for 1/8-inch perforations for dwellings (C) 2.0 feet for'/4-inch and 3/16-inch perforations for MSTS and other establishments; and, (D) 5.0 feet for 1/8-inch perforations for MSTS and other establishments. (3) Perforation discharge is determined by the following formula: Q =19.65 cd2hv2 Where: Q = Discharge in Gallons Per Minute (GPM) c = 0.6- = coefficient of discharge d = perforation diameter in inches h = head in feet 15.5 Pump Discharge Head. The pump discharge head must be at least five feet greater than the head required to overcome pipe friction losses and the elevation difference between the pump and the distribution device. 58 Washington County Development Code