Sealed Manholes

Sealed manholes provide access to underground utilities, such as below-ground drainage and stormwater solutions. The seal is designed to prevent unauthorised access, water ingress, and debris entry.

Marshalls' sealed manholes and manhole covers are made from high-quality, durable concrete designed to withstand harsh weather conditions and high traffic loads. Available in 1200mm, 1500mm, and 1800mm diameters, they feature a monolithic precast concrete base and a sealed cover slab supplied with your required access.

Marshalls' sealed manholes comply with BSEN 1917:2002 and BS5911-3 and have been accepted for use by all major UK companies.

These products are manufactured to last a minimum of 120 years and provide up to 40% savings on greenhouse gases compared to traditional manhole construction, eliminating the need for ready-mixed concrete to form the traditional base, chamber benching and further concrete to surround the manhole.

Practical advantages:

• Safer construction: There is no requirement to work in confined spaces, no requirement to form a concrete surround and a reduction of open excavation
• Fast installation: The modular solution eliminates the need for wet trades resulting in rapid construction compared to conventional methods
• Efficient construction: Available in varying depths for efficient construction
• Available at short notice: Our modern production methods enable just-in-time delivery of all components, including monolithic bases, at short notice
• The combined seal includes a load distributor: Load distribution ensures an even distribution of vertical loads*
• Allows joint inspection: Correct installation can be visually confirmed
• Full take-off service available
• Lifting apparatus available for fast, effective and safe handling

Specification advantages:

• Base options: available pre-benched or plain bottom with or without inlet/outlets
• Pre-fit options: Hydro-brakes, penstocks, non-return valves and filters can be pre-fitted at the factory
• Flexible connections: The perfect manhole can connect to plastic, clay or concrete, giving you a larger choice
• 130mm wall thickness: No need to surround the manhole in concrete unless specifically required - saving time and money
• Watertight: The combination of a thicker wall and rubber joints ensures a watertight structure
• Greenhouse gas savings: Up to 40% savings on greenhouse gas emissions compared with a traditional build - contributing to your project's sustainability goals
• Perfect hydraulics: Optimised flow characteristics are achieved by customising the base configuration of all inlets and precise drop-in channels and pipe connections

Manufacturing advantages:

• Fully tested under factory conditions: The whole system, from base to cover slab, is subject to testing
• Kitemarked solution manufactured under factory conditions: Complies with the requirements of BSEN 1917 and BS5911-3
• Design freedom: All designed monolithic perfect base characteristics, such as the location of the inlets and outlets and invert configuration, can be manufactured individually and exactly in accordance with the specifier's and client's wishes

*Please note Watertightness is defined in BS EN 1917 as resisting a 5m head for 15 minutes, this is to simulate a temporary surcharge condition not a permanent head of water. Shafts in high water tables are subject to buoyancy effects.

We have some useful videos on the perfect Sealed Manhole System and also on how to install the best system.

If you would like a CPD style presentation on the Sealed Manhole please take a look at our CPD Page