DM Civil

DM Civil Concrete Capability

March 2024

Since DM Civil was founded in 1976, concrete work has often featured as a component in any contract, if not the key scope of works. Our company has built concrete elements and structures including:

  • Pre-cast and insitu-cast vehicle and pedestrian underpasses
  • Pre-cast and insitu-cast boat ramps
  • Insitu-cast storage dam spillways
  • Insitu-cast trunk watermain valve pits
  • Insitu-cast industrial and municipal use building structures
  • Insitu-cast main sewer access chambers
  • Precast stormwater main drain bridges
  • Precast road bridges
  • Insitu-cast ground tanks

Potable water retaining ground tanks have been build by DM Civil since the 1990’s when the Araluen Golf Course Estate storage tanks were constructed in Roleystone. Since then, we have constructed the base ring beam and associated works for the Carabooda 60 megalitre main water supply, the Coral Bay 800 kilolitre water supply main tank and the Dalwallinu town supply ground tank.

The Dalwallinu 2 megalitre ground tank and associated works was constructed for Water Corporation in 2018. The 20m diameter tank was cast insitu with 6m high walls, cast in 3 lifts and covered with a concrete roof. The roof was constructed using precast beams and panels, supported by precast columns, which were topped with an insitu-cast sloping cap. The construction was subject to strict quality assurance measures to ensure longevity of the asset and to comply with drinking water standards.

The Dalwallinu ground tank construction comprised the following steps:

  • Bulk earthworks for the tank foundation by removal of unsuitable material and replacement with clean sand fill to subgrade level;
  • Installation of MSCL outlet pipework below the tank base;
  • Forming and pouring a concrete block trial mix for testing prior to tank construction;
  • Placement of a mass concrete blinding layer as a firm and level access to the tank area and for installation of the tank base steel reinforcement and wall starter bars;
  • Forming and pouring the tank base with 40MPA special mix concrete;
  • Placement and propping of wall formwork first lift including injection tubes for hydrophilic seal material;
  • Fixing of first lift reinforcing steel including incorporation of a stainless steel manway code welded to the reinforcement;
  • Forming and pouring second lift of wall including surface treatment of first lift top edge to ensure a waterproof seal;
  • Forming and pouring third lift of wall to 6.0m level including formed top pockets to incorporate roof beam and surface treatment of second lift top edge to ensure a waterproof seal;
  • Craning into place over starter bars, RC columns that were precast on site and propping in place and injecting epoxy grout in tubes incorporated during the precasting process;
  • Craning into place precast Delta Beams to bear on the third wall lift pockets and the precast RC columns;
  • Craning into place precast Delta Core panels to span between beams with subsequent grout fill to perimeter units;
  • Pouring a single roof slab of the Delta Beams and Panels to form a homogeneous cover over the tank;
  • Fixing the ventilator units and access hatched into the concrete roof;
  • Fixing of the tank external stainless steel tank filling pipework and the internal fibre reinforced plastic (FRP) pipework and supports;
  • Construction of the FRP internal and external access ladders and security screens;
  • Filling and leak testing of the tank for commissioning.

DM Civil has now commenced construction of a similar design of ground tank located at Lakelands on the northern side of central Mandurah. The 850 kilolitre tank is being built to Water Corporation standards to the same design as the Dalwallinu tank, but with a reduced capacity. Our experience on the Dalwallinu project will be used to ensure that the same high standards are maintained for this project and that our workforce continues to gain and retain the skills and expertise for this scope of works.