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Concrete manholes

With an industry striving for improved pipeline and manhole construction quality and performance concrete drainage systems manufacturers need to ensure continuous innovation. Delivering reduced waste, lower costs, faster build times and minimise environmental impacts.

Production techniques continue to advance and the use of modern logistics systems ensure excellent product quality and reliable service.

Using responsibly sourced raw materials from local suppliers helps keep "pipe miles" low and reduces embodied impacts. The use of modern, high performance seals helps maintain water tightness and integrity of joints.

Moist trades are eliminated, benching on web sites is prevented, and lifting holes are sealed when in the right position. This allows follow-up operations to begin immediately.The use of modern, high performance seals helps maintain water tightness and integrity of joints.

The flexibility of concrete drainage systems allows for many special features in the factory which allows them to simply be placed into position on site. These “offsite solutions” can replace lengthy in-situ operations, thus improving site safety and product quality, reducing waste, speeding-up installation and reducing costs.

A prime example of a recent offsite solution that was introduced in the construction manhole construction industry was the concrete manhole ring system. This system is packed with an array of benefits that will satisfy designers, contractors, and operators alike. Using locally sourced raw materials helps reduce transportation costs and environmental impacts.

The new concrete manhole design offers:

  • Reduced construction time
  • Decreased installation costs
  • Improved safety on site
  • Superior quality
  • Watertight system
  • Reduced carbon footprint
  • Concrete Manhole Ring Construction

Manhole construction traditionally requires the base to be formed on-site, in the trench where the channel, connections, and benching are built. This often happens in wet and unpleasant conditions. The process can take around 40 hours per concrete manhole and is not always successful.

Particularly in terms of leakage where egress of waste water can lead to contaminated groundwater and ingress can contribute to the common problem of overloaded sewer networks. In addition to increased energy usage and running costs at treatment works and pumping stations.

Concrete Manhole Design

The new concrete manhole ring design comprises a precast concrete monolithic base unit. This is completed with channel and benching with predetermined combinations of inle (s) and outlet. They also have a new design of chamber ring with watertight, flexible joints and no lifting holes, thereby removing points of possible leakage.

Both base units and chamber manhole rings are made with thicker, stronger walls. The robust design means that the requirement for a concrete surround is eliminated, unless specifically required. The excavation is backfilled sooner and there is less need for men to work in confined spaces. This reduces time spent in the excavation, further improving site safety and reducing installation costs.

Concrete Manhole Ring Installation

Installation of the whole system is both quick and efficient. When you're in the right position, you can eliminate wet trades, avoid forming benching on site, and start follow-up operations immediately. Field trials indicate that time savings of over 30% can easily be achieved and costs reduced by well over 10%, particularly when installed without a concrete surround. Demonstration videos are available for the CPM Group's Perfect Base, F P McCann #39;s Easi- base and Stanton Bonna's Watertight Manhole System

The Environmental Advantages

The system also yields environmental advantages as less concrete is used, there is less waste and less excavated material is disposed of in landfill. An annual saving of over 22,000 tonnes of CO2e is estimated in the UK if all manholes manufactured by members of The British Precast Drainage Association changed to the new precast base system.

The quality of material and finish is well above that normally achieved on site. The full system is manufactured under factory conditions by third party certified companies to ISO 9001 quality management system. Products are Kitemarked to BS EN 1917:2002 and BS 5911-3:2010. Concrete Manhole rings and Inspection Chambers and tested under laboratory conditions.

UK Water companies have embraced the new precast manhole base system and given their acceptance to use the design for new projects. The new system replaces the use of traditional in-situ construction and full acceptance is anticipated throughout the UK.