•   S P E C I F I C A T I O N S  F O R   T U B E   S E T T L E R   S Y S T E M S     •


Under this section of the specification, the contractor shall install a tube settler system in approximately _____ square feet of the sedimentation basins as described herein and as shown in the contract drawings.

It is the intent of the specifications that the equipment, when installed in accordance with the drawings and the manufacturer's recommendations will permit efficient operation at the design flow of ____ GPM. Such equipment shall consist of a number of tube-like channels at least 4.0 square inches in cross sectional are being approximately
(2' - 0") (3' - 0") long and orientated at approximately 60° from the horizontal to assure that the settled particles will be purged from the tubes by force of gravity alone.

The tube settler system shall be manufactured by a company that is regularly engaged in the manufacture of this product and who can demonstrate its knowledge of the technology, and its competence and expertise in the field.

All components of the system shall be provided by a single manufacturer. It shall be the sole responsibility of the contractor to coordinate all design, fabrication, assembly, and installation of the components in the clarifier. The manufacturer shall submit detailed drawings and design data on all components for the installation. Design calculations for the support structures shall be submitted and sealed by a registered engineer.

The tube settler modules shall be as manufactured by Enviropax, Inc. of Salt Lake City, Utah.

The materials of construction for the tube settler modules shall be Acrylonitrile Butadiene Styrene (ABS) and shall be strong, rigid, resistant to chemical deterioration in an outdoor environment.

The resin utilized shall be prime grade, virgin, high impact, and have the following physical characteristics:



Specific Gravity


Rockwell Hardness


Tensile Strength, psi


Tensile Modulus, psi


Flexural Strength, psi


Flexural Modulus, psi


Deflection Temp.@ 264 psi in °F


Impact Strength (izod)

ft - lbs / inch @ 73 °F


ft - lbs / inch @ 0 °F


Drop Dart, 1/8" Sample


ft - lbs / inch @ 73°F

Monsanto (3)

ft - lbs / inch @ 0°F

Monsanto (3)

The tube settler module shall be built up of a number of corrugated sheets with alternately placed flat sheets. The individual sheets shall be solvent welded to provide strong continuous bonds and thereby form a durable homogenous structure with each tube being continuos and imperforate, eliminating mixing currents that resuspend settled solids within the tube. The corrugated sheets shall have the inclined channel configurations molded integrally therein, so that all the tubes shall have the same angle of inclination when installed in the basin.

The finished (after thermoforming) thickness of the plastic used in the modules shall not be less than twenty (20) mils, and twenty-five mils for the corrugated and flat sheets respectively. The edges of the plastic shall be clean, smooth, and free from burrs caused by sawing or trimming the parts to minimize the possibility of sludge buildup or growth.

The completed modules shall have a minimum height of
(19.5") (30") and be manufactured to the necessary widths and lengths to minimize field modification.

The baffles shall be constructed of corrugated fiberglass reinforced plastic with a structural
(aluminum) (stainless steel) frame. The fiberglass panels shall have corrugations of 2.5" pitch and 1/2" depth and be 8 oz. material. The panels shall have the following nominal properties: Glass content 27% (ASTM-2584-86), Barcol hardness 40-60 (ASTM-2583-81), flexural strength 22,000 psi (ASTM-790-81), flexural modulus 900,000 psi (ASTM-D-790-81), tensile strength 11,000 psi (ASTM-D-638-82A).

The structural (aluminum) (stainless steel) frame shall be fabricated of (Type 6061-T6) (304 SS) structural shapes. The panels shall be attached by means of 304 stainless steel fasteners to provide an adequate secure attachment.

The collection troughs shall be constructed of 1/4" minimum thickness fiberglass reinforced plastic (FRP) consisting of 24 oz. woven roving and a 10 mil surface matt. The trough shall have a gel coat on all exposed surfaces which is stabilized against attack by sunlight and all chemicals involved in the flow stream.

The FRP shall have a ultimate strength of not less than 16,000 psi, flexural strength of not less than 25,000 psi, flexural modules of elasticity of not less than 838,000 psi, and a glass content of not less than 30%. The above characteristics shall be in conformance with ASTM Standards D638 and D790.

Reinforcing and stiffener sections shall be designed to meet the load design characteristics.

The V-notch weir plates shall be constructed of 1/4" thick cast acrylic material precision machined to the dimensions shown on the contract drawings. The weir plates shall have an ultimate tensile strength of 10,000 psi or greater, flexural strength of not less than 15,000 psi, compressive strength of 17,000 psi, and a modulus of elasticity of not less than 450,000 psi. Test methods on these mechanical characteristics shall be evaluated in accordance with ASTM-D-638, D-695, and D-790 test methods.

The supports shall be constructed of fabricated structural
(mild steel) (aluminum) (stainless steel) (fiberglass) members and shall have the proper surface preparation as noted in the Painting Section of the contract specifications.

All fastening hardware and expansion anchors shall be 304 stainless steel of adequate size to meet the design requirements.

The tube modules shall be capable of supporting their own dead weight [ 2 ft - (3.5 PSF) (5.5 PSF), 3 FT - (5.3 PSF) (8.3 PSF) ] and an additional live load of 10 PSF uniformly distributed. The minimum design for the support structure shall include all dead loads resulting from tube modules, supports, troughs, weirs and baffles, and a uniformly distributed live load of 10 PSF or a moveable concentrated live load of 250 lbs.

The tube settler modules, troughs, weirs and baffles shall be provided in such configurations as shown on the contract drawings as to minimize, if not eliminate field trimming, cutting or modifying and are to be installed as shown on the drawings, and in accordance with the manufacturer's recommendations. Care shall be exercised by the contractor in unloading, transporting and placing tube modules. Tube modules shall remain in their containers and protected from environmental extremes until they are installed. Installers may walk on the tube modules to facilitate installation but planking should be used to protect edges of the modules from breakage. The tube modules are flammable and consequently care should be taken not to expose them to welding, sparks,or open flames.

The contractor shall submit detailed drawings showing the configuration of the tube settler modules and the manner in which they are to be installed. The installation drawings shall include detailed instructions to the installer regarding any field trimming or other modifications required to fit to the sedimentation basins. Shop drawings shall be fully dimensioned for construction.

tube settlers
PVC Tube Settler specs
Drawings of equipment