Managing surface water with culverts

June 26, 2016 Phil Gatehouse


As mid-winter approaches, management of excess surface water becomes a high priority for those on the land, particularly in areas of heavy traffic such as gateways or around small stream tributaries and waterways. Culverts have long been the best way to manage this, but traditionally these were constructed of concrete. RX Plastics bring a new approach to culverts with our plastic pipe solutions.

Why culverts

Water crossing this driveway could be managed with a new culvert

While there have been many changes to the way in which water is transferred across land, particularly with piping now replacing open water races, when it comes to managing excess water piped culverts are still the best method as they allow for seasonal fluctuations in water levels and flooding.

Traditionally concrete was the material of choice, due to its strength and durability. However concrete culverts are not without their setbacks – they can be difficult to install, requiring good curing conditions. Getting materials and tools required to remote locations can also be difficult.

Lightweight plastic options

RX Plastics offer two ranges of plastic pipes, featuring either PVC or Polyethylene (PE). Compared to concrete, using plastic pipe for culvert pipes brings numerous advantages, including weight and ease of installation in more remote areas.

PVC pipe, whilst light takes much of its strength from the bedding material surrounding the pipe. PVC does not return from deformation as readily as Polyethylene, so it is important that the pipe is protected from heavy downforce.

Much of this can be achieved in installation, by selection of appropriate aggregates and compaction around the pipe body.

Polyethylene on the other hand is much tougher, able to withstand heavier loads and more able to return to shape from any deformation. Made from the same material as RX water tanks, the culvert pipe is light and able to withstand the elements. When installed correctly, RX culvert pipe will easily take the weight of a tractor or a truck overhead.

With pipe sizes up to 500mm outside diameter, we can provide culvert pipe suitable for most water flows.

Planning your culvert

The secret to any successful culvert is in its planning and installation.

Before installing your culvert there are several factors that need to be taken into account.

1) Most important is the annual amount of water to be carried, which will need to take into account local rainfall as well as  events such as floods or other periods when the culvert is likely to be put under pressure (storm seasons, snow melt etc).

2) All culvert installations will also require enough fall sufficient to move water through the pipe.

3) Another consideration is if the culvert area is prone to erosion, and if there is a significant amount of water passing through the pipe will it also contain any debris such as soil or branches.

4) Finally, you’ll also need to take into account the crossing point covered by the culvert and the weight and frequency of traffic passing over it.

Culverts are vulnerable to erosion of surrounding land and flood damage, so planning ahead will minimsie any potential hazards. It always pays to have some advice from a suitably qualified engineer, plus we recommend speaking to your regional council – the authority responsible for management of water resources – before undertaking any culvert work.

Find out more about RX Plastics’ Culvert products on our website, or check out our info hub for more resources.


About the Author

Still rivers run deep with Phil, our technical product manager. He is a hands-on kinda guy who has been known to not only get out on the farm to demonstrate products to our customers, but also to turn his considerable skills to whipping up a company brochure or designing a piece of software when the occasion demands it.

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