The Sealed Manhole system is available in 1200, 1500 and 1800mm diameters and comprises:
- monolithic precast concrete base (available pre-benched in any configuration
- sealed chamber ring (with a thicker wall than a standard ring)
- rubber joint (so no tokstrip of similar product is required)
- sealed cover slab which is supplied with the required access
This unique system of products combines to form the Marshalls Civils and Drainage Sealed Manhole system. Designed and manufactured to last at least 120 years, it provides a sealed manhole system giving up to 40% savings on greenhouse gases compared to traditional manhole construction. It eliminates the need of ready-mixed concrete to form the traditional base, chamber benching and further concrete to surround the manhole. A complete manhole can be installed in just 30 minutes, ensuring safe site practice as it reduces the need to work in confined spaces and eliminates the need for wet trades, resulting in rapid construction compared to traditional methods, and a reduction in the time the excavation is open.
- Safer construction: no requirement to work in confined spaces. No requirement to form a concrete surround. Reduction of open excavation.
- GHG savings: up to 40% savings on GHG emissions compared with traditional build.
- Fast installation: modular solution eliminates the need for wet trades resulting in rapid construction compared to conventional methods.
- No need to surround in concrete unless specifically required – 130mm wall thickness.
- Available at short notice: Marshalls' modern methods of production enables just-in-time delivery of all components including monolithic bases at short notice.
- Design freedom: all designed monolithic perfect base characteristics such as location of the inlets and outlets and invert configuration can be manufactured individually and exactly in accordance to the wishes of the specifier.
- Perfect hydraulics: everything flows. Optimised flow characteristics by customised base configuration of all inlets and precise drop in channels and pipe connections.
- Watertight: the combination of a thicker wall and rubber joints ensures a watertight structure.
- No water ingress into sewerage network reduces treatment costs: the combination of a 130mm wall and sealed rubber joint to withstand a minimum of 5m / head pressure*
- Combined seal includes load distributor – Load distribution ensures even distribution of vertical loads*.
- Allows joint inspection: correct installation can be visually confirmed.
- Efficient construction: available in varying depths.
- Base options: pre-benched or plain bottom with or without inlet/outlets.
- Pre-fit options: Hydro-brakes, penstocks, non-return valves and filters.
- Flexible connections: can connect to plastic, clay or concrete.
- The whole system from base to cover slab is subject to testing.
- Complies with the requirements of BSEN 1917 and BS5911-3.
- High-quality durable concrete with a minimum 120 year design life.
- Full take-off service and lifting apparatus available.
*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.