Articles & Case Studies


Posted: Tuesday 15th April 2014

The new Hidderley Park housing development near Camborne, Cornwall is a scheme with provision for up to 270 residential units, retail outlets and a small number of workshops. Consulting engineer for the site is GTA Civils, with environmental, landscaping and ecological design works being undertaken by Cornwall Environmental Consultants Ltd. Construction on the site started in 2013 and is scheduled to continue for the next few years. All construction works, including house building, ground works, drainage, street lighting etc. are the responsibility of Robertson Developments Limited.

Whilst much of the construction work on developments such as this relates to visible, above-ground structures such as houses and other units, of equal importance is the infrastructure work - utility services for delivering energy, telecommunications and drinking water and removing effluent. Such developments are increasingly required to deliver high standard sewers, with due consideration being given to the choice of drainage material to ensure reliable, long-life serviceability. In this instance, after careful consideration of the various pipe options available, the design team opted to utilise Densleeve pipes, joints and fittings etc. as manufactured by Naylor Drainage Ltd of Cawthorne, Barnsley.

According to Jason Mitchell, Managing Director of Robertson Developments: “After looking at what was available to us, we decided to use the Naylor Densleeve system because of the trusted Naylor brand and the back-up available from our local supplier, Redruth-based Civils Store Limited.”


Because Hidderley Park is a new development, all of the drainage system is being installed using open cut techniques; Robertson Developments is using Densleeve pipes in diameters from 100 mm up to 300 mm, in conjunction with the Milton Precast Perfect Manhole system, to create the drainage network.

Naylor’s Densleeve underground drainage system of plain-end vitrified clay pipes and fittings, with flexible sleeve couplings, was developed for open cut building drainage and associated sewerage installations and is manufactured to comply with the stringent requirements of BS EN295. When installed in general accordance with the Naylor Sitework Instructions, the Naylor Densleeve system meets the latest technical requirements of the Building Regulations, BS8005 and BS8301.

Densleeve is available in diameters DN100, 150, 225 and 300. In addition to this standard UK range, DN200 and 250 pipes are manufactured for key export markets.

Densleeve pipes are plain ended and are normally jointed using high impact polypropylene connectors with elastomeric seals that provide watertight, flexible mechanical joint assemblies, complying with BS EN295-1: System G The standard Densleeve pipes, polypropylene couplings and elastomeric sealing rings are resistant to attack from substances which are commonly encountered in sewer flows. Nitrile seals are also available for use in contaminated ground. All joints accept angular deflection and shear resistance without leakage, when tested under an internal or external water pressure of 50 kPa (5 m head of water).

Another major advantage of the plain-end design of the Densleeve system is that pipes can be quickly and easily cut to intermediate lengths on site and can still be jointed using normal couplings. This feature retains the ease in jointing, reduces wastage and damage and is particularly cost effective.

The Densleeve range also incorporates a full range of fittings including bends, saddles, rest bends, junctions, universal, rainwater, paving and square gulleys, hoppers, traps and other widely used accessories, all of which are connected using the standard coupling system.

For Naylor Drainage Ltd, Edward Naylor, Managing Director commented: “We have been making clay drainage since our foundation in 1890 and much of our early production is still in service. The residents of Hidderley Park should expect their sewerage system to similarly stand the test of time.”

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