MELBOURNE CRICKET GROUNDRECONSTRUCTION

Written by Gary Thomas

Introduction.The MCG was reconstructed in 1991. The construction was of a ‘Perched water table’ method.

The oval was reconstructed on a clay base with a fall of 1% or 1:100.

The time frame for the project was very tight with the start the day after the football grand final (September) and playable in December for the shield and one day cricket. Its first major event was the Boxing day test (Australia v West Indies).

BaseAfter the complete removal of the existing oval a series of sub-clay collector drains and pits were installed before the clay base was compacted and shaped.

BaseThese drains after installation were surrounded by sand and then covered in clay and compacted so later sinkage did not occur.

BaseThe clay base was shaped with a fall of 1% or 1:100. Thisbase was then compacted with vibrating rollers.

Base

BaseThe removal of such large amounts of material in a short time meant a well managed work schedule was essential.

BaseLarge portions of the oval however were found to be of a soft and unsuitable type of material to make a base. Crushed scoria was used as an excellent substitute.

BaseOnce the base was formed a perimeter ringed drain was installed before all other drains were installed.

FencingThe original oval was not a level surface around the northern side. The grandstands in some parts had to have a concrete retaining wall built up to create a standard level to work to.

IrrigationAll irrigation sub-mains where installed 500mm below the final level of the clay base and clearly marked. This had to be carried out at this level to keep clear of yet to be installed drains.

Wicket heating cablesWiring to the centre wicket had to be protected during the construction process. This cabling was a previous effort to keep the couchgrass growing for extended periods in our mild climate.

Work scheduleDuring reconstruction the turf wicket had to be maintained and prepared for the upcoming test on completion of the oval.

The base shape was a dome. The oval was ringed by a series of herringbone shaped drains.

Drains

DrainsAll drainage trenches were lined with ‘geotextile’ cloth to stop the migration of clay into the drains.

The machinery automatically dug the trench and removed the base material from the site in one operation.

Drains

Levels were constantly checked with lasers to guarantee the slopes met specifications.

Drains

Drainage layersOn completion of the base and its drains a ‘Perched water table’ construction was installed within channels.

The use of rounded river gravel as a drainage material created a problem of leveling. This material can easily be moved by its rounded nature and size (7 to 12mm) but was used to keep costs down compared to blue metal.

Drainage layers

A railing system with specially adapted leveling bars attached to excavators were used along a series of girders. The river gravel was installed to a constant depth of 100mm.

Drainage layers

Once the river gravel was finished the rootzone material was installed. This consisted of the “primary sand layer” (ACI Sports 40), then the amended layer (ACI Sports 40 amended with 10% sphagnum peat moss and 6kg/m3 Netlon mesh elements).

Blind layer

Pea gravel

Primary sand

Amended layer

The topsoil once leveled had the girders removed.

Topsoil

The project was completed by working outwards to the eastern exit ramp being the last area completed. This displays the importance of a thorough work schedule.

Work schedule

Turfgrass establishmentThe common couch sod (mixture of C1, C2 and C3) was laid and a sand topdressing was applied and the surface rolled to consolidate. C1 became ‘Legend’, and C3 became ‘Bosker’ couch.

Wicket preparationDuring the reconstruction of the oval the wicket still had to be prepared. The camera cables can be seen being installed during this process.

Wicket preparationThe levels of the wicket however had not been allowed for in the design of the oval. These levels had to be adjusted and a small problem of soft sand run-ups for the test occurred.

The project was completed on time, although the surface for other sports was over-sown with Ryegrass during the following winters, and this tends to now dominate the sward.