Emergency services were called to the site on the corner of Melrose Drive and Launceston Streets in Phillip around 2.30pm on Saturday.

No-one was injured in the collapse, which took away part of a roadway. One lane remains closed on Melrose Drive.

The 15-metre high retaining wall had been held in place by reinforced steel piers encased in concrete and sprayed concrete buttressing.

The deluge which hit Canberra on Friday and intermittently throughout Saturday, coming after major falls a few days earlier, is suspected to have triggered the massive ground shear, which caused a multi-storey carpark nearby to be evacuated and an exclusion zone put in place.

WorkSafe ACT is investigating the incident.

Canberra Airport reported 43.8mm of rain from 9am on Friday.

The weather for the next three days is expected to be relatively stable, with possible morning frosts, light winds, partly cloudy conditions and daytime temperatures up to 14 degrees.

Showers are expected to return to the national capital on Friday, when there is an 80 per cent chance of rain.

The major rain events in the past week have resulted in Icon Water being forced to release partially treated effluent into the Molonglo River from the 147-million litre dam at the Lower Molonglo Water Quality Control Centre, the largest inland waste water treatment facility in the country.

Residents on the section of the Murrumbidgee River from the junction of the Molonglo River and above Burrinjuck Reservoir are being asked to avoid drawing water from the river for either potable (drinking or food preparation) or non-potable (domestic or stock watering) purposes.

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