2.5.10.2
Weirs
The influent and effluent weirs shall be of sufficient length so that the
flow does not exceed [_____] L cubic feet per minute per weir length at the
average daily flow. The influent weir shall be [_____] mm inch above the
effluent weir. The effluent weir shall be [_____] mm inch above the top of
the cell dividers. The weirs shall be fabricated of Type 304 stainless
steel and shall be [_____] deep with [_____] mm inch adjustment. The weirs
shall be mounted on [_____] mm inch mild steel plate with Type 304
stainless steel hardware on [_____] mm inch centers and sealed with a
neoprene rubber gasket. The overflow weir shall be a minimum of [_____] mm
inch above the effluent weir. The weir shall be the full width of the
filter. The overflow shall not discharge into the backwash channel.
2.5.10.3
Backwash Channel and Washwater Trough
The bottom surface of the washwater trough shall be at least [_____] m feet
above the overflow weir. The backwash channel shall be constructed of
[stainless steel] [fiberglass reinforced plastic] [_____]. A tank drain
shall be provided in the backwash channel.
2.6
PRESSURE FILTERS
2.6.1
Pressure Filter Tank
**************************************************************************
NOTE: Delete the partition wall requirement if the
vessel will not be divided into multiple filter
cells.
**************************************************************************
The pressure filter tank shall have a diameter of [_____] m feet, a height
of [_____] m feet, straight shell length of [_____] m feet and shall be
oriented [horizontally] [vertically]. Each vessel shall be provided with
[_____] partition wall to divide the vessel into [_____] filter cells. The
filter vessels shall be of welded steel construction and shall be tested to
withstand a hydrostatic pressure of [_____] Pa psi in excess of the working
pressure of [_____] Pa psi. The vessel shall be designed and fabricated in
accordance with the ASME BPVC SEC VIII D1 and shall be so stamped and
certified. Lifting lugs, supports, connections and appurtenances shall be
as detailed on the drawings. The filter tank construction shall be in
accordance with Paragraph Tank Requirements and prepared in accordance with
the requirements of Paragraph PAINTING and Paragraph MATERIALS PROTECTION.
2.6.2
Underdrain System
Each filter shall be furnished with a [pipe laterals with nozzles] [pipe
laterals with orifices] [porous plate] [_____] underdrain system. The
underdrain shall be of the standard manufacturer's design particular to the
supplied filter unit and furnished with the constructed package unit. The
underdrain system shall be designed to withstand all loads due to design
pressures, design loading rates, and loads from the media to be installed
in the filter tank.
2.6.3
Media
The media shall provide uniform voids distribution from coarse to fine in
the direction of flow. Filter materials shall conform to the requirements
SECTION 11393
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