USACE / NAVFAC / AFCESA / NASA UFGS-43 31 14 (April 2006)
---------------------------
Preparing Activity: USACE Superseding
UFGS-43 31 14 (August 2004)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 43 31 14
TRICKLING FILTER
04/06
NOTE: This guide specification covers the requirements for a trickling filter
for use in sewage treatment plants normally handling domestic sewage.
Edit this guide specification for project specific requirements by adding, deleting,
or revising text. For bracketed items, choose applicable items(s) or insert
appropriate information.
Remove information and requirements not required in respective project, whether
or not brackets are present.
Comments and suggestions on this guide specification are welcome and should
be directed to the technical proponent of the specification. A listing of technical
proponents, including their organization designation and telephone number, is
on the Internet.
Recommended changes to a UFGS should be submitted as a Criteria Change Request
(CCR).
PART 1 GENERAL
NOTE: Special consideration must be given to sewage carrying industrial wastes
containing components detrimental to biodegrading microorganisms. The following
information should be shown on the project drawings or provided by the project
designer:
a. Dimensions of filter tank and elevation of base slab.
b. Design flows and loading rate.
c. Available head.
d. Depth of filter bed.
e. Size of inlet piping.
f. Location of vent stack pipes.
g. Design loads for wind and ice where applicable.
h. Clearance of arms above filter surface.
i. Number of distribution arms.
j. Type(s) of filter media to be allowed.
k. Type of filter blocks.
1.1 RELATED SECTIONS
NOTE: Other items associated with the trickling filter, but not covered in
this section, include (when used) valves, sluice gates, slide gates, gratings,
and manhole steps. These items should be covered in the appropriate section
of the project specifications.
Concrete work for trickling filter tank, including rotary distributor base shall be in accordance with Section
[_____]. Steel work for trickling filter tank, including foundation, shall be in accordance with Section
[_____]. Supply piping and valves shall be in accordance with Section [_____].
1.2 REFERENCES
NOTE: This paragraph is used to list the publications cited in the text of
the guide specification. The publications are referred to in the text by basic
designation only and listed in this paragraph by organization, designation,
date, and title.
Use the Reference Wizard's Check Reference feature when you add a RID outside
of the Section's Reference Article to automatically place the reference in the
Reference Article. Also use the Reference Wizard's Check Reference feature
to update the issue dates.
References not used in the text will automatically be deleted from this section
of the project specification when you choose to reconcile references in the
publish print process.
The publications listed below form a part of this specification to the extent referenced. The publications are
referred to within the text by the basic designation only.
[AMERICAN BEARING MANUFACTURERS ASSOCIATION (ABMA)ABMA 11(1990; R 1999) Load Ratings and Fatigue Life for Roller BearingsABMA 9(1990; R 2000) Load Ratings and Fatigue Life for Ball Bearings][AMERICAN INSTITUTE OF STEEL CONSTRUCTION (AISC)AISC 360(2005) Specification for Structural Steel Buildings, with Commentary][AMERICAN SOCIETY OF CIVIL ENGINEERS (ASCE)ASCE Report No. 13(1961) Filtering Materials for Sewage Treatment Plants][AMERICAN WATER WORKS ASSOCIATION (AWWA)AWWA C151/A21.51(2002; Errata 2002) Ductile-Iron Pipe, Centrifugally Cast, for Water][ASTM INTERNATIONAL (ASTM)ASTM A 123/A 123M(2008) Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel ProductsASTM A 153/A 153M(2005) Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel HardwareASTM A 36/A 36M(2008) Standard Specification for Carbon Structural SteelASTM A 475(2003) Standard Specification for Zinc-Coated Steel Wire StrandASTM A 48/A 48M(2003; R 2008) Standard Specification for Gray Iron CastingsASTM A 53/A 53M(2007) Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and SeamlessASTM B 209(2007) Standard Specification for Aluminum and Aluminum-Alloy Sheet and PlateASTM B 209M(2007) Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate (Metric)ASTM B 429/B 429M(2006) Standard Specification for Aluminum-Alloy Extruded Structural Pipe and TubeASTM C 144(2004) Standard Specification for Aggregate for Masonry MortarASTM C 150(2007) Standard Specification for Portland CementASTM C 159(2006) Standard Specification for Vitrified Clay Filter BlocksASTM C 700(2007a) Standard Specification for Vitrified Clay Pipe, Extra Strength, Standard Strength, and PerforatedASTM C 88(2005) Standard Test Method for Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate][THE SOCIETY FOR PROTECTIVE COATINGS (SSPC)SSPC SP 8(1982; E 2004) Pickling]1.3 SYSTEM DESCRIPTION
The trickling filter shall include a rotary distributor, reinforced concrete walls and base, filter media, filter
block underdrainage system, and all other components indicated or necessary for proper operation.
1.4 SUBMITTALS
NOTE: Review submittal description (SD) definitions in Section 01 33 00 SUBMITTAL
PROCEDURES and edit the following list to reflect only the submittals required
for the project. Submittals should be kept to the minimum required for adequate
quality control.
A “G” following a submittal item indicates that the submittal requires Government
approval. Some submittals are already marked with a “G”. Only delete an existing
“G” if the submittal item is not complex and can be reviewed through the Contractor’s
Quality Control system. Only add a “G” if the submittal is sufficiently important
or complex in context of the project.
For submittals requiring Government approval on Army projects, a code of up
to three characters within the submittal tags may be used following the "G"
designation to indicate the approving authority. Codes for Army projects using
the Resident Management System (RMS) are: "AE" for Architect-Engineer; "DO"
for District Office (Engineering Division or other organization in the District
Office); "AO" for Area Office; "RO" for Resident Office; and "PO" for Project
Office. Codes following the "G" typically are not used for Navy, Air Force,
and NASA projects.
Choose the first bracketed item for Navy, Air Force and NASA projects, or choose
the second bracketed item for Army projects.
Government approval is required for submittals with a "G" designation; submittals not having a "G" designation
are for [Contractor Quality Control approval.][information only. When used, a designation following the "G"
designation identifies the office that will review the submittal for the Government.] The following shall be
submitted in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:
SD-02 Shop Drawings
Rotary Distributor[; G][; G, [_____]]
Detail drawings of rotary distributor including manufacturer's descriptive and technical literature,
catalog cuts, and installation instructions. Detail drawings shall contain equipment layout
and anchorage, and sufficient details to demonstrate that the rotary distributor will properly
function as a unit.
SD-03 Product Data
Spare Parts
Spare parts data for the rotary distributor, after approval of the detail drawings and not
later than [_____] months prior to the date of beneficial occupancy. The data shall include
a complete list of parts and supplies, with current unit prices and source of supply.
SD-10 Operation and Maintenance Data
Operating and Maintenance Manuals
[Six] [_____] copies of the operation manual outlining the step-by-step procedures required
for system startup, operation and shutdown. The manuals shall include the manufacturer's name,
model number, service manual, parts list, and brief description of all equipment and their basic
operating features. [Six] [_____] copies of the maintenance manual listing routine maintenance
procedures, possible breakdowns and repairs, and troubleshooting guides. The manuals shall
include simplified wiring diagrams for the system as installed.
1.5 EXTRA MATERIALS
All standard spare parts shall be provided as recommended in the manufacturer's instruction manuals for each
component of the equipment.
PART 2 PRODUCTS
2.1 MATERIALS AND EQUIPMENT
2.1.1 Standard Products
Unless otherwise specified, provide materials and equipment which are standard commercial products in regular
production by the manufacturer and suitable for the required service. Structural steel shall conform to ASTM A 36/A 36M
. Steel pipe for structural members and distributor arms shall conform to ASTM A 53/A 53M. Steel members which
will be in contact with sewage, completely or intermittently, during normal operation of the equipment shall
have a minimum thickness of 6 mm 1/4 inch. All cast iron shall conform to ASTM A 48/A 48M, Class 30. Aluminum
alloy used for structural members and pipe shall conform to ASTM B 209M ASTM B 209 (3003-H14) and ASTM B 429/B 429M
(6063-T6), respectively.
2.1.2 Materials Protection
All ferrous metal surfaces shall be pickled in accordance with SSPC SP 8. All ferrous metal surfaces, including
rotating assembly, distributor arms, supports, and attachments shall be zinc coated in accordance with ASTM A 123/A 123M
or ASTM A 153/A 153M, as applicable. The interior and exterior of all fabricated ferrous metal components shall
be pickled and galvanized after fabrication. To prevent corrosive action, insulating components such as gaskets,
couplings, or bushings, of a dielectric-type which will prevent corrosion of bimetallic-type contacts, shall
be used at connections between dissimilar metals.
2.1.3 Rotary Distributor
The rotary distributor shall be suitable for the uniform distribution of sewage over the filter bed at the rates
of flow and operating conditions specified herein. The rotary distributor shall include distributor arms, center
column, and other appurtenances necessary for proper operation. The rotary distributor shall rotate solely from
the reaction of sewage flowing through jets or nozzles in the distributor arms and shall operate freely and effectively
over the entire range of operation.
2.1.3.1 Design and Operating Requirements
NOTE: Delete ice coating requirements in warm climates.
The rotary distributor shall be designed for a filter bed of [_____] mm feet inside diameter. Design flows shall
range from a minimum of [_____] L/second gpm to a maximum of [_____] L/second gpm, and the average design loading
shall be [_____] L/second gpm. The total head available at the inlet (above the media surface) shall be [_____]
at the maximum rate of flow. The maximum velocity in the arms shall not exceed 1.22 m/second 4.0 fps. The rotary
distributor and each of its component parts shall be designed to withstand all structural and mechanical stresses
brought about by the following loadings: weight of equipment plus liquid; wind loading; and a live load of [_____]
N pounds at any point on the arm; and an ice coating of [_____] mm inch thick. Safety factor for the foregoing
shall be a minimum of 1.6 based on the yield point of the steel. The anchorage of concrete center pier shall
be designed to resist, with a 2.0 minimum safety factor, a maximum overturning moment brought about when arms
on one side of the distributor are filled with water and those on the other side are empty. Vertical deflections
at the end of the distributor arms shall not exceed 100 mm 4 inches and arms shall have a clearance above the
surface of filter bed as indicated. The rotary distributor shall be designed for continuous 24-hour service
under design load without excessive wear, damage, or failure. Stresses developed under the aforementioned operating
conditions and loads shall not exceed the stresses allowed under AISC 360.
2.1.3.2 Center Column
NOTE: Delete bracketed wording pertaining to weirs or dependent on the provisions
of weirs when distributors have less than four arms, except when two-compartment
arms are used.
The trickling filter tank should be constructed in accordance with Section
03 31 00.00 10 CAST-IN-PLACE STRUCTURAL CONCRETE. Walls should have standard
finish. Horizontal surfaces should have screed finish. Insert the following
requirements in the appropriate place: "The hollow concrete center pier, including
installation of anchor bolts, shall be constructed in accordance with the recommendations
of the manufacturer of the rotary distributor, as approved by the Contracting Officer."
Type IIA cement normally will be specified, but Type V cement will be specified
when the soils contain in excess of 0.2 percent water soluble sulfate as SO(4),
or waste water contains in excess of 1,000 parts per million sulfates. Alkali
reactive aggregates require use of a cement containing less than 0.60 percent
alkalies. Type I cement may be permitted when it can be assured that the water
soluble sulfates in the soil will be less than 0.1 percent and the waste water
will contain less than 150 parts per million sulfates over the design life of
the project. Air entrainment admixtures will be used in all types of concrete.
The center column shall be mast-type or turntable-type and shall include a stationary assembly, rotating assembly,
seal, bearing assembly, lubricating fittings, and anchor bolts. Ample port areas or openings shall be provided
to permit unrestricted flow of sewage from inlet in stationary assembly through rotating assembly into distributor
arms.
a. Stationary Assembly: Elements of the stationary assembly shall be of cast iron, structural steel,
steel pipe, or aluminum alloy. The stationary assembly shall have a [_____] mm inch diameter inlet and
be designed for anchorage to the hollow concrete center pier by anchor bolts.
b. Rotating Assembly: Elements of the rotating assembly shall be of cast iron, structural steel, or
aluminum alloy, except as otherwise specified herein. Turntable, when provided, shall be of cast iron
only. Steel for nonstructural applications shall have a minimum yield point of 207 MPa 30,000 psi.
[An adjustable weir shall be provided to divide the flow between the primary and secondary arms so that
only primary arms will operate at minimum flow and that all arms will discharge uniformly at maximum
flow. The weir shall be accessible for adjustment without dismantling the equipment. The weir shall
be in the rotating assembly, unless provided in each secondary arm as specified hereinafter.] Rotating
assembly shall have machined surfaces suitable for installation of distributor arms and shall be of a
height that provides suitable anchorage for distributor arm supports.
c. Seal: A mechanical seal or an air gap shall be provided to prevent the leakage of water between
the stationary and rotating assemblies at the maximum hydraulic head. Any type of seal employing mercury
as the sealing element will not be allowed.
(1) Mechanical Seal: The mechanical seal, if selected, shall be designed to withstand the
full hydraulic head in the rotating assembly. Seals shall have an annular ring of replaceable
grease-resistant neoprene or tetrafluoroethylene with a low coefficient of friction. Seals
between horizontal surfaces shall be maintained against the seal plate by annular steel weight
strips and steel seal clamps. Seals between vertical surfaces shall be spring loaded in steel
retainer rings attached to the rotating assembly.
(2) Air Gap: An air gap, if selected, shall be provided to prevent the liquid from entering
the rotor bearing and shall require no auxiliary equipment to maintain the air gap between the
fixed feeder pipe or column and the rotating sleeve and/or drum. Means shall be provided to
prevent the liquid level in the rotating equipment from rising positively to the elevation of
the air gap. The relief device provided to prevent this shall be constructed to force any overflow
to discharge on the surface of the filter, visible to the operator and at a point above or apart
from normal distribution outlets.
d. Bearings: The radial and axial loads of the rotating assembly and distributor arms shall be transmitted
to the stationary assembly by an anti-friction thrust bearing of the ball or roller type. Guide or steady
bearings shall be provided where necessary to maintain alignment. Bearings shall be designed so that
the rotating assembly will maintain its alignment, start freely, and operate satisfactorily at the minimum
head at all conditions of wind and temperature. Bearings shall be designed for the vertical thrust of
the machine full of water and the horizontal thrust due to eccentric loads on the arms. Bearings shall
have a minimum rated life expectancy of 100,000 hours (L-10). When equipment is operating continuously
under specified loading conditions, load rating and fatigue life shall be based on ABMA 9 and ABMA 11
, as applicable.
e. Lubrication Fittings: All moving parts subject to wear and all bearings shall be provided with adequate
means for lubrication. Lubrication shall be by grease or oil, as suitable. Greased bearings shall be
provided with fittings for grease gun service. If not easily accessible, the bearing lubrication fittings
shall be provided with grease tubing extended to convenient locations. The grease fittings shall prevent
over-lubrication and pressure build-up injurious to bearings. Each oil reservoir shall be liberal in
size and be provided with an opening for filling, an overflow opening at the proper location to prevent
overfilling, an oil-level sight glass, and a drain at the lowest point. Provide the manufacturer's recommended
lubricant sufficient for 6 months of normal operation.
f. Anchor Bolts: Anchor bolts, with necessary hex nuts and washers, shall be Type 304 stainless steel.
Anchor bolts and accessories shall be provided to secure the stationary assembly to the hollow concrete
center pier.
2.1.3.3 Distributor Arms
The distributor arms shall be attached to the rotating assembly by flanged or screwed connections. The arms
shall be of steel pipe, structural steel with minimum wall thickness of 6 mm 1/4 inch, or aluminum alloy. [When
the adjustable flow division weir specified in paragraph Rotating Assembly, is not provided in the rotating assembly,
one adjustable, accessible overflow weir shall be provided in each secondary arm to cut off flow to that arm
at minimum flow and to allow uniform flow of all arms at maximum flow.] The end of each arm shall be provided
with a quick-opening shear gate for flushing. Arms shall be supported from the rotating assembly by cables,
steel tie rods with turnbuckles, or a steel truss. Wire strand for cables shall conform to ASTM A 475. Arm
supports shall be designed to support the design loads. Arms shall be laterally braced by means of horizontal
steel tie rods with turnbuckles. Each arm shall have openings spaced to distribute the flow uniformly over the
filter bed. Nozzles and spreaders shall be provided at each opening and shall be of corrosion-resistant nonferrous
material. Nozzles shall be designed to provide maximum reactive force with minimum head loss. Spreaders shall
be designed to disperse the flow evenly from each opening. Each spreader shall be easily removable for cleaning
and shall be equipped with replaceable orifices permitting variation of flow capacity with different orifices.
Rectangular-arm distributors shall have orifices in the spreaders. Orifices and openings shall be of nonclogging
design.
2.1.3.4 Center Pier Supply Fittings
The [_____] mm inch supply inlet line junction fitting shall be a [base tee and riser pipe] [base-plate with
short riser pipe and flange] suitable for the rotary distributor center column attachment. The construction
shall be ductile iron, or steel conforming to AWWA C151/A21.51 or ASTM A 53/A 53M, respectively.
2.2 FILTER BLOCKS
The underdrain system shall include rectangular and cut tile blocks, cover blocks for drainage channels, and
vent blocks. All blocks shall conform to ASTM C 159, Type I-H, except cover blocks shall not have apertures
and vent blocks shall have openings to accommodate vent stacks. Cut or angle blocks shall be cut on an angle
to conform approximately to the wall curvature. Filter underdrain blocks shall have semicircular inverts or
equivalent section and shall cover the entire floor of the filter. Vent stack pipes shall be of extra strength
vitrified clay pipe conforming to ASTM C 700 and shall be provided as indicated.
2.3 FILTER MEDIA
2.3.1 Quality
NOTE: When plastic media is to be used exclusively, delete all requirements
for and reference to other materials.
The media shall be [crushed stone or crushed slag][ or ][plastic].[ Crushed stone or crushed slag shall conform
to ASCE Report No. 13.] The top 460 mm 18 inches of media shall have a loss by the 20-cycle sodium sulfate soundness
test of ASTM C 88 of not more than 10 percent by weight; the balance of the media shall pass a 10-cycle test
using the same criteria. Plastic media shall be random-dumped ring type or stacked modular type. Random-dumped
ring type shall be of long term heat aging, rigid polypropylene plastic specially manufactured as trickling filter
media, with a minimum void volume of 90 percent, and a minimum surface area per cubic meter feet volume of 82
square meters 25-square feet. Plastic stacked modular type shall be of saran, polyvinyl chloride (PVC), fiberglass
reinforced resins, or plastic equally resistant to oxidation, ozone aging or effects of ultraviolet exposure,
and shall have minimum void volume and surface area per cubic meters feet volume as required for random-dumped
ring type media. The media shall provide a minimum projected life of 25 years in the intended service. Projected
life shall be based on case history or simulated aging tests as performed by an independent testing laboratory
acceptable to the Contracting Officer. Such tests shall be substantiated by certified and notarized test reports.
Installed media shall provide support for the weight of two workmen working together on any part of the surface
of the filter without damage or displacement of the media.
2.3.2 Size and Grading
[Stone or slag media shall conform to ASCE Report No. 13, Grading size 90 to 63 mm 3-1/2 to 2-1/2 inches.][
Plastic media shall be the manufacturer's standard as approved by the Contracting Officer.]
PART 3 EXECUTION
3.1 INSTALLATION AND CONSTRUCTION
3.1.1 Placing Rotary Distributor
NOTE: Delete bracketed wording pertaining to weirs or dependent on the provisions
of weirs when distributors have less than four arms, except when two-compartment
arms are used. Coordinate with paragraph CENTER COLUMN.
The rotary distributor shall be installed in accordance with the recommendations of the manufacturer and by workmen
experienced in the installation of this type of equipment. All components with galvanized or other corrosion-protective
coating shall be carefully checked and any damaged or abraded areas shall be restored to the original or an equivalent
coating. Proper alignment of all equipment shall be provided. The anchor bolts shall be set in place and the
nuts tightened against the shims. After the foundation alignments have been approved, the stationary assembly
shall be securely bolted in place. The alignment of equipment shall be further checked after securing to the
foundations and, after confirming all alignments, the stationary assembly shall be finally grouted in place.
Equipment shall be aligned with associated piping and under no circumstances will "pipe springing" be allowed.
[The weirs shall be set in accordance with the directions of the manufacturer, based on anticipated flows.]
3.1.2 Placing Filter Block
Filter underdrain blocks shall be laid in a dry mortar bed. The mortar shall contain one part cement conforming
to ASTM C 150, Type II, and 4 parts sand conforming to ASTM C 144, except a 1:3 cement-sand mortar bed for the
first course of blocks where cover blocks are used. After the blocks are laid and before the stone is placed,
the dry mortar bed shall be dampened by sprinkling. Filter blocks shall be installed providing an uninterrupted
flow through the drainage channels in the blocks to the effluent channel. Blocks shall be laid in true alignment,
with cross joints staggered in longitudinal rows at right angles to the center drains. The rows of blocks shall
start at the edge of the drainage channel and end at a sufficient distance from the filter wall to provide an
air passage around the inside periphery of the filter. Air ducts comprised of either blocks or stacks shall
be provided for venting air to the atmosphere as shown on the drawings. A plan layout of filter block units
shall be provided by the manufacturer.
3.1.3 Placing Filter Media
[Stone or slag media delivered to the filter site shall be stored on wood planks or other approved clean hard
surface areas. Stone and slag shall not be dumped directly into the filter. The media shall be rescreened or
forked at the filter site to remove all fines before placement in the filter. Material shall be placed by hand
to a depth of 300 mm 12 inches above the filter blocks and all material shall be placed without damaging or displacing
the underdrains. The remainder of the material may be placed by means of belt conveyors, wheelbarrows, or other
approved equipment. The media shall be placed in layers not exceeding 450 mm 18 inches in depth. Filter media
shall be placed as near as practicable in final position to avoid excessive rehandling; special care shall be
taken to avoid breakage or segregation of different size particles. Dumping the filter media directly from trucks
into the filter, dropping the filter media from heights exceeding 1 m 3 feet or throwing the media into the filter
will not be permitted. If it is determined that an excessive amount of fractured stone or dust is passing into
the underdrains, the Contractor may be required to remove and rescreen the filter media at a location outside
the filter walls. There shall be no walkways or runways over the filter except for the purpose of installing
materials or equipment for the filter. Storing materials, such as cement or sand, or placing heavy construction
equipment within the filter walls will not be permitted. Concrete, sand, dirt, or other materials deleterious
to the filter shall not be passed over the filter by any means. No material shall be dropped from a height greater
than 1 m 3 feet. Trucks, tractors, or other heavy equipment shall not be driven over the filter during or after
construction.] [Installation of plastic filter media shall be made in accordance with the recommendations of
the media manufacturer.]
3.2 FIELD TESTS AND INSPECTIONS
Perform all field tests. Provide all labor, equipment, and incidentals required for the tests, except that water
required for the field tests will be supplied as set forth in the CONTRACT CLAUSES. The Contracting Officer
will witness all field tests and conduct all field inspections. Give the Contracting Officer [_____] days prior
notice for dates and times for acceptance tests. Any deficiencies found shall be rectified and work affected
by such deficiencies shall be completely retested at the Contractor's expense. The distributor mechanism shall
be tested to demonstrate correct alignment, smooth operation, and uniformity of flow distribution over the filter
media. After acceptance and before contract closing, the Contractor shall submit operating and maintenance manuals
as specified in the Submittals paragraph, under SD-10.