- Splayed : Most precast headwalls and Sewers for Adoption compliant headwalls have splayed wingwalls. Our standard range of headwalls all have splayed wingwalls.
- Rectangular : Our rectangular (RSFA) precast headwalls have been designed to comply with Severn Trent Water specifications for concrete outfalls. Althon rectangular headwalls are also Sewers for Adoption compliant and are available with wall profiles to suit bank gradients of 1 : 1, 1 : 2 and 1 : 3
- Right & Left Hand Angled : The Environment Agency’s preferred headwall outfall construction type for pipework discharging into a main river. Angled precast headwalls allow pipework entering a watercourse at an angle to be accommodated or for an outfall to be situated on a bend in a river
Select the internal diameter of the pipework being used with your headwall. The opening in the headwall will be cast to suit the outside diameter of the specified pipe material and diameter
Choose the material of the pipework you will be using with the headwall. The opening in the headwall will be cast to suit the outside diameter of the specified pipe material and diameter
Althon Sewers for Adoption precast headwalls should be used when a concrete headwall is part of a Section 104 Agreement and the sewers are to be adopted once completed by the local Water Company. The materials used and installation must comply with the ‘Sewers for Adoption’ guidelines
Select whether or not your require handrails factory fitted to your headwall. Various arrangements such as Kee Klamp Handrail ® to 3 sides of the headwall or to the backwall only are available
Select whether you will require a grating on your headwall. If you wish to have a penstock or a flap valve fitted please select a Cranked Grating
Sewers for Adoption Compliant headwalls for pipework over 350mm should be fitted with a SFA Type 1 Outfall Safety Grille
Select if you would like an appropriately sized flap valve fitted on your headwall.
Flap valves prevent water backing up the discharging pipework during storm events and periods of flooding
If you require a grating as well please select a Cranked Grating
Select if you would like an appropriately sized penstock fitted on your headwall.
Penstocks are used to isolate the flow of water and manage water levels
If you require a grating as well please select a Cranked Grating
Backwall heights
This is the overall height of the backwall of the headwall. Headwalls within a specific range often have a variety of backwall heights available.
Backwall height should be a consideration when considering cover to invert levels or the profile of the surrounding area or slope of the bank.
We are able to cast the invert level of the opening into the backwall of our precast headwalls to a specified level.
Single or multiple pipe openings
We cast the openings in our precast headwalls to suit the specified pipe diameter and material and if required to a specified invert level.
We are also able to accommodate multiple pipe openings in our headwalls. These openings can be arranged anywhere on the backwall of the headwall.
Where required we are also able to cast openings for pipework through the wingwalls (side walls) of our precast headwalls
Specifiable pipe invert levels
Typically we cast the pipe openings in our standard precast headwalls at a 100 – 150mm invert level up from the spillway of the headwall.
Sewers for Adoption compliant precast headwalls should have the invert level of the pipe opening set 225mm above the spillway.
When requested we can set the invert level of the pipe opening wherever on the backwall of the headwall you require.
We cast the openings in our precast headwalls to suit the specified pipe diameter and material and are also able to accommodate multiple pipe openings in our headwalls
Maximum pipe size
This refers to the largest single opening we are able to accommodate in any given headwall.
The diameter opening relates to the internal diameter of any given pipework.
We will cast the opening into our headwalls slightly larger than the outer diameter of the specified pipework to make installation on site as easy, fast and safe as possible.
Sewers for Adoption Compliant headwalls for pipework over 350mm should be fitted with a SFA Type 1 Outfall Safety Grille
Our Sewers for Adoption compliant outfall safety grilles are hinged with a padlock facility. On SFA compliant grating should be 270mm wider than the pipe OD
