SPEL Thundaflo

Heavy Duty Channel Drain System

Spel Thundaflo

SPEL Thundaflo is a heavy duty channel drainage system (aka trench, linear or slot), uniquely designed for the industrial environment – forecourts, forklift working areas, truck loading bays, airports.

A proven system since 1996:

  • Three Metre sections
  • Independent Positioning System
  • Built-in-fall or Zero gradient Channel
  • Unique rugged steel design
  • Grating design to suit application

Unique Robust Design

Thundaflo channel diagram - Unique Robust Design

Easy Installation

Step 1 - Dig trench and set out reinforcing cage and channel sections

  • Trench is dug and reinforcing steel cage set in position.
  • Channel is laid on top of the reinforcing steel cage.
  • The fibreglass rods are inserting through the brackets and hammered into the ground on an angle - bottom splayed out.
  • The torsion springs are also attached to the fibreglass rods.
  • Note that the top torsion spring is positioned at the top of the fibreglass pole to prevent the fibreglass being splintered while being hammered into the ground.

Dig Trench and Set Out Reinforcing Cage and Channel Sections
Dig Trench and Set Out Reinforcing Cage and Channel Sections

Step 2 - Channel is raised into approximate position

  • Each three metre section is raised into approximate position.
  • Sections are then connected.
  • Note that as each section is raised the fibreglass poles are placed under tension forming a very rigid structure for the concrete pour.

Channel is raised into approximate position
Channel is raised into approximate positions

Step 3 - In position and ready for concrete pour

  • The vertical position of the channel can be adjusted very accurately along the fibreglass rods and securely locked into place with the torsion springs.
  • The lower torsion spring holds the channel in place while the upper torsion spring prevents float during the concrete pour.
  • Positioning poles can be easily trimmed with a battery powered grinder if they extend above the height of the channel.
  • Polystyrene is inserted into the top of the channel to prevent the ingress of wet concrete into the channel during the pour.
  • Note that the polystyrene insert can be reused.

In position and ready for concrete pour
In position and ready for concrete pour

Step 4 - One concrete pour with no cold joints

  • One concrete pour in two passes/stages.
  • Initial stage up to 50mm above bottom of channel to "haunch" channel and reinforcing steel.
  • Second stage to top of channel. Note that wet concrete can be dumped on top of the polystyrene insert to "mitigate any risk of float" during this process. This is important where ground conditions are soft and/or large section channel is being installed.

In position and ready for concrete pour
One concrete pour with no cold joints

Step 5 - Finished installation

  • Chip seal was used in this project where the concrete reinforcing was leveled to 30mm below the top of the frame. This enables the wheel load to be transferred directly into the concrete surround.
  • Grates are inserted and secured in place with bolt and brace.
  • The tested load rating of this ThundaFlo channel drain is E400 (AS3996), extra heavy duty.

Finished installation
Finished installation

Replacing Damaged Poly-modular Drain

damaged one metre polymodular drain
The broken down poly-modular drain. The key problem is that the drain has parted company with the concrete surround and imploded. It appears that several attempts have been made to resurrect the drain, a very expensive and unsuccessful exercise!

damaged one metre polymodular drain close-up
A close up view of the broken poly-modular drain where the walls of the drain have imploded. We observe this problem occurring with many of these types of drains and is the reason SPEL Thundaflo is reinforced with a 5mm thick steel rim.

break out damaged one metre polymodular drain
Breaking out the damaged poly-modular. A saw cut is made down each side of the broken poly-modular drain and then dug out.

drilling starters
The trench is dug to approx 150mm below the channel depth (200mm wide drain) taking into account the built-in-fall. Holes are drilled for the rebar stirrups.

rebar inserted with epoxy
Rebar is inserted into the holes and cemented with expoxy resin.

rebar tied to form stirrups
Rebar is tied to form stirrups. The bottom of the stirrups need to be about half the distance between the bottom of the channel and the trench bottom. 125mm Width, 60mm from the bottom of the channel & 200mm width, 75mm from the bottom of the channel.

height adjustments
SPEL THUNDAFLO is positioned using the Independent Positioning System (IPS) to adjust the height.

torsion springs attached to fibreglass rod
Torsion springs can be attached to the bottom of the fibreglass rod to form a "foot" where soil conditions are unsuitable (either too soft or rocky) for the fibreglass rods to be hammered into the ground.

cutting fibreglass robs
The fibreglass rods are trimmed to below the surface.

top torsion springs engaged to prevent floating
The top torsion spring is engaged to prevent the system from floating during the concrete pour.

poly insert to prevent wet concrete ingress
Poly is inserted into the frame to prevent the ingress of wet concrete into the channel and assist with screeing.

wedged fibreglass rods
Fibreglass rod is cut to length and the wedged between the frame and the side of the trench to firmly brace the system. A very flexible and effective method to ensure there is no movement while during the concrete pour.

concrete pour
Start of concrete pour. Note how well the poly insert is preventing the ingress of concrete into the channel. A major hassle to clean if this should occur!

concrete pour second stage
A Single concrete pour is made in two stages. The 1st stage is to the bottom of the channel and final stage is to the top. The is to mitigate upward hydraulic pressure and prevent the system from floating.

concrete screening
Wet concrete everywhere... Note how well the poly insert prevents the ingress of concrete into the channel

concrete screeing completed
Finishing off: The poly insert greatly assist in screeing the concrete.

finished replacing poly-modular drain
Poly insert removed, grates are inserted...rock solid for many years

125 Series: Channel and Shoe-Guard Grating

Gull Te Kuiti

System diagrams

Thundaflo drainage system 125 series isometric drawing

Thundaflo drainage system 125 series profile drawing

Channel flow rate curves are available upon request.

Grating diagram

Thundaflo drainage system 125 series grating drawing

Grating flow rate curves are available upon request.

200 System: Channel and Shoe-Guard Grating

Caltex Hamilton forecourt

System diagrams

Thundaflo drainage system 200 series isometric drawing

Thundaflo drainage system 200 series profile drawing

Channel flow rate curves are available upon request.

Grating diagram

Thundaflo drainage system 200 series grating drawing

Grating flow rate curves are available upon request.

200 System: Channel and Shoe-Guard Grating

BP Tauriko driveway

System diagrams

Thundaflo drainage system 200 series isometric drawing

Thundaflo drainage system 200 series profile drawing

Channel flow rate curves are available upon request.

Grating diagram

Thundaflo cross-flo 200 series grating drawing

Grating flow rate curves are available upon request.

Past Projects

Thundaflo C208 Cross-flo Z energy Hamilton NZ

Thundaflo Caltex station

Thundaflo BP petrol station

Thundaflo BP Bulls

Thundaflo drainage system completed job

Thundaflo drainage system Waitomo

Thundaflo drainage system completed job zoom in

Thundaflo drainage system completed job close up

Thundaflo drainage system NPD Christchurch

Thundaflo drainage system manukau long range landscape