1. GENERAL
    1. Domestic Water System - System Requirements
      1. Reliability
        1. Adequate volume and pressure of water must be available at all times. On-site pressurization should be considered if the city supply is not reliable. Prior to the start of design work, contact the City of Corvallis Water Department to determine their requirements and pressures.
      2. Capacity
        1. System capacity shall be based on peak flow demand rates of the plumbing system, make-up to HVAC equipment, and process water requirements.
      3. Pressure
        1. A minimum domestic pressure of 40.0 psig is required at the most remote use points.
        2. If the public system cannot furnish this, provide booster pumps in mechanical room with drain.
        3. Maximum water pressure within a building should not exceed 80.0 psi.
        4. Provide multiple pressure-regulating assemblies with a full line size bypass with isolation valves.
        5. Coordinate the location for easy maintenance.
      4. Design velocities
        1. To assure a quiet piping system, design velocities shall not exceed those noted below. Piping sized according to the velocities above still must not exceed the allowable pressure drops specified in the Uniform Plumbing Code, per the current Oregon amendments.
        2. Max. velocity
          1. Mains mechanical rooms: 10 ft. per sec.
          2. Mains and branches in other areas: 8 ft. per sec.
      5. Routing
        1. Route site fire and water lines to avoid other utilities, vaults, and trees.
        2. Coordinate routing with the landscaping plan to verify that no piping is within ten feet of any new tree and outside the drip line of any existing trees.
           
  2. BUILDING SYSTEM
    1. Risers and mains
      1. For ease of maintenance, locate risers and mains at or near an exterior wall in an accessible location, such as a mechanical equipment room, storage room, or custodial room.
        1. A main shut-off valve shall be installed on the riser before any branch take-off.
        2. Pipe runs below the building floor slab shall be avoided, except for short branch lines serving “island” fixtures.
      2. In multi-story buildings, locate a shut-off valve on the branch feeding each level.
        1. In addition, provide sectional valves for each self-contained or special purpose area, to permit a localized shut-down without affecting other parts of the system.
        2. Provide shut-off valves for each toilet room.
        3. Provide an access door in the toilet room with the shut-off valves toilet rooms.
    2. Backflow Prevention
      1. All potable and non-potable water, such as lines labs, HVAC equipment, cooling water, or other water make-up systems to equipment shall have a pressure-reducing type backflow preventer (RPBP) installed in parallel (duplex) located in an accessible location.
        1. A floor sink or other approved fixture shall be nearby to receive piped discharge from the RPBP.
        2. Back-flow protected lab water shall be identified differently from those serving domestic purposes, such as drinking fountains, kitchens, and rest rooms, etc.
      2. Kitchen equipment with chemical injection systems (i.e. dishwashers, hood wash systems, beverage systems) require a pressure-reducing type backflow preventer (RPBP) located in an accessible location. A floor sink or other approved fixture shall be nearby to receive piped discharge from the RPBP.
      3. All potable and non-potable building supply water shall be protected by two (2) backflow preventers (BFP), installed in parallel to allow for testing or repair of the device without shutting off the building’s water supply. Provide unions or flanges on both sides of the device.
    3. Water hammer protection
      1. A sealed chamber-type, maintenance free, water hammer arrestor shall be installed upstream of all solenoid valves, flush valves, water mixing valves or other quick-closing valves.
        1. The size, quantity, and location are to be as recommended by the manufacturer of water hammer arrestors.
        2. Simple air-chamber type units are not acceptable.
    4. Trap primers
      1. Trap primers shall be provided to protect the trap seal of infrequently used fixtures (generally floor drains).
        1. A single trap primer may be used to serve more than one fixture.
        2. A manifold provided by the trap primer manufacturer shall be provided. Provide access for inspection or locate trap primers exposed.
        3. Provide a shut-off valve on the water supply line to the primer.
        4. Locate trap primers in an easily accessible location.
    5. Water heating
      1. Provide steam to hot water generators for domestic hot water.
      2. Specifications:
        1. The hot water temperature at any fixture shall not exceed 120 deg. F, as per plumbing code. Generate water at temperatures necessary to attain 120 deg. F at taps. Provide a recirculating system controlled by Honeywell Aquastat Controller. Special use areas such as kitchens and certain labs may require higher temperatures.
      3. Selection of water heater capacity shall be based on the recommendations of the ASHRAE Handbook for Hot Water Systems or on other standard engineering practices.
      4. Use the Oregon Plumbing Specialty Code for sizing pipe.
      5. Some areas or equipment may require higher temperatures than the 140 deg. F, recommended above, such as cafeterias, kitchens, etc. In such cases, a separate heater or local booster heaters of appropriate capacity shall be used.
      6. Use of electric instantaneous units may be used at remote isolated locations. Preferred manufacturers:
        1. Controlled Energy Corporation, Powerstar, Powerstream, or Ariston with a minimum five year warranty.
      7. When tank electric water heaters are pre-approved by Owner’s Authorized Representative and Responsible Maintenance Manager, pre-approved manufacturers are RUUD Brand.  Tank shall be commercial grade and shall carry a minimum 10 year-manufacturer’s warranty.
    6. Fixtures
      1. Refer to OSU Construction Standard 22 40 00 for Plumbing Fixtures requirements and standards.
    7. Piping Materials
      1. Use Type L copper for all domestic cold and hot water, and recirculated hot water piping and all water piping down stream of RP devices
    8. Valves
      1. Select valves for the appropriate function:
        1. Gate valves or butterfly valves or ball for shut-off or sectionalizing service, globe valves for flow modulation.
        2. Specialty valves shall be employed where appropriate, such as check valves on a pump discharge, pressure regulating valves for equipment requiring lower-than-available system pressure, solenoid valves, etc.
        3. Flanged or threaded end valves are preferred.
        4. Locate valves in accessible locations, not more than six feet above the floor, if frequently used, and with a union on the downstream side of threaded end valves.
      2. Provide each valve with a brass disc not less than 1-1/4” diameter engraved with numbers, piping service, and normal operating position (i.d. NO, NC) corresponding to valves shown on diagrams.
        1. Fasten discs to valves with #14 brass wire or #16 brass jack chain.
      3. Galvanized piping shall not be used in any water system.
    9. Insulation
      1. Insulation is required for all hot water piping, cold water and industrial cold water piping.
      2. Insulate horizontal portions of rain water piping above ceilings or finished soffits in areas where there is a possibility of condensation.
      3. Provide flexible molded vinyl insulation kit on exposed waste and supply piping below ADAAG lavatories and sinks.
    10. Accessories
      1. Pipe line accessories such as unions, pressure or temperature test plugs, flow sensors, gauges, flexible connectors, etc. shall be employed as appropriate to assure a well-functioning, easy-to-maintain system.
      2. Expansion joints or expansion loops shall be installed on long, straight runs to compensate for thermal expansion of the pipe whenever the calculated expansion is +/- 1/8 inch or more. Spacing and location shall be based on the maximum probable temperature fluctuation and the thermal coefficient of the pipe material.
    11. Supports
      1. For parallel pipe runs, trapeze-type supports shall be spaced to suit the smallest pipe in the group. Spare room for 20% future pipe lines should be reserved.
      2. Hanger spacing shall also be coordinated with the supporting steel overhead. Hangers shall be of sufficient strength to support the pipes and contents plus 200 pounds. Metallic pipes shall not be in direct contact with hangers or the supporting structure.
      3. Provide seismic bracing according to SMACNA requirements.
         
  3. SANITARY SEWER SYSTEMS
    1. Design Criteria
      1. Capacity
        1. All calculations for pipe capacity shall be based on the current Plumbing Code. Cooling tower blowdown will also discharge into the sanitary sewer system.
        2. Verify and obtain written approval from the OSU Project Manager that the existing downstream sanitary sewer mainline has capacity for the new sanitary sewer system based on peak flows.
      2. Slope (pitch)
        1. Slopes of sanitary sewer lines within a building are set by code.
        2. Verify that design considerations are acceptable to local jurisdictions and obtain approval prior to proceeding with design work.
      3. Tests
        1. Sanitary sewer systems are tested per code, generally tested at 10 feet of head for a period of 4.0 hours with no visible loss of water.
        2. The exceptions are pumped portions, which should be tested at 1 1/2 times the pump head.
    2. Routing
      1. Route site sanitary lines to avoid other utilities, vaults, and trees.
      2. Coordinate routing with the landscaping plan to verify that no piping is within ten feet of any new tree and outside the drip line of any existing trees.
      3. Include continuous #14 tracer wire with all exterior sewer installations.  Tracer wire should be secured and reachable from finished grade at manhole and cleanout facilities.
    3. Material
      1. Hubless cast iron or galvanized steel pipe is acceptable.
        1. Below-grade portions of piping shall be hubless plain-end cast iron piping to a point five feet beyond the exterior face of the building.
        2. Specify four (4) band fittings above and below grade.
    4. Freeze Protection
      1. The minimum depth of pipe cover must be three feet, or one foot below the frost line, whichever is greater.
    5. Exterior sewer systems
      1. Manholes
        1. All drop connections at manholes must be approved by the OSU Project Manager. 
        2. Manhole steps are to be installed.
        3. Continuous tracer wire must be reachable form finished grade inside the manhole cone.
      2. Cleanouts
        1. Cleanouts shall be two-way except at dead-end lines.
        2. Stand pipe should match the primary pipe size up to six (6) inches maximum.
        3. Tracer wire must be reachable from finished grade within the cleanout cover.
    6. Building sewer systems
      1. Vents
        1. Provide vents in accordance with code. To reduce the number of roof penetrations, collect vents in the ceiling or attic space.
      2. Cleanouts
        1. In addition to code requirements, provide cleanouts at major pipe junctions. Avoid locations such as lobbies, conference rooms, private offices, or other special areas.
      3. Floor drain system
        1. Provide traps and vent at all floor drains directly connected to the sanitary sewer. Pipe runs should be located between columns to avoid footing pressure zones.
      4. Distribution of floor drains shall be:
        1. In mechanical equipment rooms at appropriate points to collect discharge or drainage from equipment.
        2. Near water heating equipment.
        3. In each toilet room.
        4. At each emergency shower.
      5. Drains serving outdoor wash pad areas, trash enclosures, loading docks or other areas that could conceivably generate contaminated rain-water runoff and/or contaminated process water shall be plumbed to the sanitary sewer system. Plumbing code requirements may dictate the use of a fixed roof, diking or slope control to minimize rain water collection.
         
  4. STORM DRAINAGE SYSTEM
    1. Design Criteria
      1. Slope
        1. Provide an engineering analysis to determine a pipe size, considering flow, velocity, and available fall. Design for pipe with space capacity.
      2. Tests
        1. Same as the sanitary sewer system.
      3. Routing
        1. Route site storm lines so as to avoid other utilities, vaults, and trees.
        2. Coordinate routing with landscaping plan to verify that no piping is within ten feet of any new tree and outside the drip line of any existing trees.
    2. Exterior Drainage System
      1. Manholes
        1. Manhole steps are to be installed.
        2. Continuous tracer wire must be reachable from finished grade inside the manhole cone.
      2. Cleanouts
        1. Cleanouts shall be two-way except at dead-end lines.
        2. Stand pipe should match the primary pipe size up to 6 inches maximum.
        3. Tracer wire must be reachable from finished grade within the cleanout cover.
      3. Materials
        1. Corrugated pipe (e.g. ADS) shall not be used for storm water drainage with the exception of detention facilities and open channel culverts.
    3. Building Drainage System
      1. Roof drains, overflows, gutters
        1. Cast iron or bronze roof drains shall be distributed to serve approximately equal areas.
        2. An overflow drain shall be located within five feet of each roof drain with the rim two inches above finished roof surface.
        3. Overflow drains shall be connected to an independent drainage system, discharging at a point visible from the outside.
        4. Discharge locations shall be selected so as not to spill or splash over or down the exterior walls of the building so as to avoid unsightly staining.
        5. Pipe sizing for the overflow pipe system is to be the same as for the roof drains.
      2. Roof Drains: Provide minimum 4” diameter drainpipe wherever feasible to minimize obstructions. Provide cleanouts and access panels for drain lines routed through walls, interior spaces, and outside the building.
        1. Provide removable scupper covers with sufficient flow to minimize leaf obstructions.
        2. Provide removable, cleanable debris screen at roof drain
      3. Rainwater leaders
        1. Materials for the roof drainage and overflow piping are to be identical.
        2. Hubless cast iron or galvanized steel pipe is acceptable. Vertical drops shall be located adjacent to exterior walls.
        3. Below-grade portions of piping shall be hubless plain-end cast iron piping to a point five feet beyond the exterior face of the building.
        4. Specify four (4) band fittings above and below grade.
        5. One vertical leader may serve only one roof drain.
        6. Extend rainwater leaders below the grade and connect it to an on- site storm drainage system or run it to the site civil piping system.
      4. Sump Pumps
        1. For small, independently drained areas (area ways, ramps, loading docks), a small local sump and pump will be required if no gravity connection to the mains is possible.
        2. The simplest arrangement shall be employed, utilizing a small, cast-in-place sump with submersible pump(s).  Sloping surfaces shall direct rainwater to the sump.
        3. In areas where a build-up of rainwater is not critical, a single pump is acceptable. In other situations or as designated by local jurisdiction, duplex pumps shall be used.
        4. Pumps shall be controlled by integral or separate level sensors.
          1. Duplex pumps are to have an automatic alternating arrangement.
          2. An additional level sensor shall be provided at all sumps to signal high liquid level alarm conditions.
        5. An oil/water separator shall be provided prior to the sump pumps where required, as designated by the local jurisdiction.
           
  5. NATURAL GAS SYSTEMS (FUEL GAS)
    1. Design criteria
      1. General
        1. Natural gas shall be considered the primary fuel for kitchen cooking equipment.
      2. Pressure
        1. The gas pressure is normally located by the seven-inch water column on the downstream side of the gas meter.
      3. Capacity
        1. The capacity of the system is the total connected load from all present and future use points.
      4. Piping
        1. The pipe above grade shall be:
          1. Threaded or welded black steel where located inside a building
          2. Galvanized steel where exposed to the weather.
      5. The pipe above grade, when exposed, shall be painted with paint suitable for corrosion protection.
    2. Valves
      1. Valves shall be readily accessible and located as designated by code and local utility company requirements.
      2. Provide valves at each capped stub out for future extension, and at each piece of equipment. Request the local utility company to provide a valve upstream of the gas meter.
    3. Accessories
      1. Provide a gas pressure regulator with a built-in internal relief and low- pressure cut-off, or for large demands, a gas pressure regulator with an internal relief and separate low-pressure cut-off.
      2. Vents shall be provided from each pressure regulator. Vents shall run independent and terminate outside the building at a location in compliance with code.
      3. Provide pressure gauges with gauge cocks on the upstream and downstream side of each regulator and a separate low pressure cut-off to aid in checking the gas pressure.
    4. Tests
      1. Gas piping shall be tested with air at 100 psig for four hours with no loss in pressure.
    5. Gas supply
      1. Coordinate the location of the gas meter with Northwest Natural Gas Company.
      2. Northwest Natural Gas Company has all known gas pipe lines documented.
      3. Install seismic gas shut-off at meter prior to entry into building.
         
  6. BUILDING SYSTEM
    1. Pressure
      1. Piping within the building shall be sized and distributed at 6.5-7” water column, unless a higher pressure is required for the equipment.
    2. Piping
      1. All piping shall run above the slab, with branches connected to the top of mains.  When necessary, due to structural conditions, piping may be installed in other locations with the permission of the local jurisdiction.
    3. Equipment Connections
      1. All connections to equipment shall terminate with a dirt tee and shut-off valve. Flexible connectors are not acceptable.
         
  7. MANUFACTURERS
    1. OSU maintains a stock of spare plumbing parts for most components on campus.
    2. The following table lists preferred brand and manufacturers for plumbing components.
    3. The brand of company name listed is to be used as the basis of design for that component. Provide a list of alternate manufacturers to the OSU Project Manager for review with the OSU FS Shops with the 100% design development documents. Provide a list of any changes or additions with the 95% construction document review.
    4. See Section 22 40 00 for OSU approved plumbing fixture list
       

 

Last Updated: 
02/10/2020