Laserfiche WebLink
■Systems serving facilities such as RV parks,mobile home parks,apartments,and unit developments are usually <br /> under the control of's single customer or responsible association.At the discretion of the engineer,such systems <br /> may be designed with shared tanks,subject to requirements of the Oregon State Plumbing Code. <br /> ■Tanks shall be sized according to flow per criteria published in OAR 340-71-220(4),On-Site Rules,page 71-51. <br /> Minimum tank capacity shall be 1000 gallons. <br /> ■Construction details and configuration of tanks shall generally conform with OAR 340-73-050,Dosing Tank <br /> Construction,page 73-13,All tanks shall feature inlet and outlet risers with lockable covers.Covers shall be <br /> designed for H-20 loading in traffic areas.Inlet riser shall be minimum 8"diameter.Outlet risers shall be sized to <br /> accommodate and access the equipment installed,with 24"diameter as a minimum.Intermediate 8"risers will be <br /> required on large tanks over 3000 gallons. <br /> ■Tanks shall be designed for all anticipated structural loads,including soil backfill.Where vehicle access is <br /> allowed,the tank shall be protected with an appropriate structural slab.All designs shall be stamped per OAR 340- <br /> 52. <br /> ■To assure retention of solids and grease in the tank,all tanks shall feature a plastic effluent screen.Screens shall <br /> conform with the standard published in OAR 340-73-055(1)(d)on page 73-15.No unscreened discharges will be <br /> allowed. <br /> ■Flotation of tanks in areas of high groundwater shall be anticipated in system design.Structural design features <br /> and operational procedures shall be employed to prevent flotation.Equalization of buoyancy through hydrostatic <br /> pressure-relief valves installed in a STEP tank will not be allowed.Normally a tank should be filled immediately <br /> after installation and,on passing the leakage test,should not be pumped down more than 3'thereafter. <br /> ■Existing septic tanks should be removed or abandoned in place.Existing tanks which fully meet the requirements, <br /> including leakage test,may be considered for use in the STEPlSTEG system.However,to retrofit the effluent <br /> screen,flow controls,access risers,and other specified features is usually impractical. _. <br /> ■Existing watertight tanks in good condition may occasionally be allowed,on a case-by-case basis,to remain in <br /> service and under the customer's private control as pretreatment units discharging to a new tank meeting the <br /> approved specifications. <br /> ■Existing building drains should be replaced and inspected per code.Alternatively,a eleanout shall be installed <br /> adjacent to the building and the drain shall be tested in accordance with the Oregon State Plumbing Code.Only <br /> watertight drains in good condition may be connected to a STEPISTEG tank. <br /> ■Pipe connections to tanks shall be made with an approved commercial waterstop manufactured for the intended <br /> purpose.Field improvised waterstops or adapters will not be approved. <br /> ■All sewage from the building including kitchen,laundry,and bath wastes shall be intercepted and conveyed to the <br /> STEPISTEG tank. <br /> ■Prior to start-up,tanks shall be smoke-tested to confirm that all connected plumbing is properly vented through <br /> external house stacks,in accordance with Oregon Building Code Agency regulations.Internal venting into attics will <br /> not be allowed. <br /> PUMPS AND OUTLET PIPING <br /> ■To maintain the efficiency of the specified screen,each individual pump discharge and gravity outlet shall be <br /> limited to 10 gpm maximum.flow rate by means of a flow-control orifice,regardless of influent flowrate or <br /> downstream head conditions.Flows exceeding 10 gpm tend to blind the screen over time,requiring them to be <br /> cleaned.Flows shall generally be controlled between 5 and 10 gpm. <br /> ■Effluent pumps shall be submersible turbine pumps and shall generally comply with the provisions of OAR 340- <br /> 73-055,sized as appropriate for head/capacity conditions of the design.Installed pumps shall be capable of passing a <br />