Correspondence A P LA/l 9.07, 8' ors a_C 7
708 SW 3rd Avenue, Suite
INTERFACE 400
Portland, OR 97204
ENGINEERING 503-382-2266 OFFICE
Project Memorandum
SUBJECT/PROJ TVFR - Walnut Street DATE: September 25, 2008
ECT:
PROJECT 2007-0432 FROM: Victoria Haynes
NUMBER:
TO: Jeff Bringenberg APPLIES
Peck/Smiley /Ettlin Architects TO: ❑ MECHANICAL
4412 SW Corbett Avenue ® PLUMBING
Portland, OR 97201 ❑ ELECTRICAL
❑ FIRE/LIFE SAFETY
❑ TECHNOLOGIES
PHONE FAX ❑ LIGHTING
NUMBER: (503) 248-9170 NUMBER: (503) 248 -0223
Jeff,
The following describes the rainwater harvesting system that was designed for Tualatin Valley
Fire and Rescue, Station #50 in Beaverton, OR, per the State of Oregon Building Codes Division
(Alternate method ruling No. OPSC 08-03):
Purpose: Use rainwater harvested from the roof of the station to supply the building's toilets and
urinals.
System Description:
1. Rainwater is collected from a metal roof via a gutter system that is screened for its entire
length.
2. Storm water flows to below grade via black ABS waste piping, through to an underground
concrete cistern. There are two high capacity filters at the inlets to the cistern that divert the
first flush of rainwater to the municipal storm drain system. These devises have a removable
stainless steel 0.15" fine mesh filters. The cistern is equipped with manholes for cleaning and
maintenance, is watertight and is designed to withstand the weight of the surrounding soil and
full capacity of water. The filters are self-draining.
3. Rainwater enters into the tank through a calming inlet, to eliminate turbulence of the
incoming water as it enters the tank.
4. There is a '/2 HP submersible pump that is fed through a floating stainless steel suction filter
(water is not drawn from the bottom of the tank).
5. Water is pumped from below grade back to the building via polypropylene pipe, through a bag
filter to an expandable diaphragm type pressure tank, sized on the peak flow capacity of the
pump.
6. Piping is marked at maximum 5'-0" intervals as "non-potable /rainwater harvested" water.
7. Harvested rainwater is routed to flush valves at urinals and water closets. Fixtures served by
harvested rainwater will have a sign that indicates they use non-potable water.
8. If the water level in the cistern drops to under the level required to operate the pump, a
solenoid valve, controlled by a float switch in the tank, opens to allow city water to supply the
fixtures. There is a reverse pressure backflow preventer that serves the entire building as well
as one where the city water connects to the rainwater harvest supply.
9. The cistern is equipped with an overflow to the municipal storm system. This overflow is
protected by a backwater valve.
System Components:
1. All piping, valves, fixtures and storage tanks are an approved type listed, designed and
intended for water use.
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2. Harvested rainwater is not exposed to daylight.
3. All downspout and overflow piping has been sized to table 11-1 of the OPSC.
4. The system will be washed clean and treated with bleach prior to going into service.
Victoria Haynes,
Interface Engineering Inc.
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