Monobox Maintenance Holes

A rectangular monobox MH consists of a true monolithic top and bottom component. In the case of a monobase, the four walls and the base slab are poured together in one continuous concrete pour. Similarly, the monotop consists of the four walls and the top slab. The two halves are stacked to create a complete structure with only one joint. The geometry of these sections allows for much larger hole openings in the four walls to accommodate very large pipe and box units. The standard inside length and width dimensions of these chambers are available in 2400 x 1800mm, 3000 x 2400mm, 3900 x 2400mm and 3900 x 3000mm. Aside from these standard sizes, Con Cast Pipe also has the capability to manufacture specialty sized monobox manholes as well. The height of each monobase and monotop can be varied by 150mm increments. This precast structure is supplied with a shiplap joint that can be filled with a mastic joint treatment.

  • Maintenance holes where pipe sizes are too large for a circular structure
  • Stormwater management structures
  • Underground storage tanks
  • Oil/grit separators and septic tanks
  • Watermain Chambers
  • Electrical Chambers

  • Quick installation since the entire structure only consists of a top half and a bottom half
  • Much larger pipe can be accommodated since all lift points are on the horizontal slabs
  • Most sections can be produced with large hole openings, eliminating any concrete pucks to be removed and disposed of on-site

  • Plant Prequalification Program
  • CSA S6 – Canadian Highway Bridge Design Code
  • OPSS 407 – Construction Specification for Maintenance Hole, Catch Basin, Ditch Inlet, and Valve Chamber Installation
  • OPSS 516 – Construction Specification for Excavating, Backfilling Compacting for Maintenance Holes, Catch Basins, Ditch Inlets, and Valve Chambers
  • CSA A23.4 Precast Concrete – Materials and Construction

Selecting the right Monobox Maintenance Hole for your application is easy with the help of our Sales or Engineering staff. Con Cast Pipe has a range of sizes, and appurtenances to suit your every need.