Infrastructure Malta is carrying out studies up to 40 metres below road level at the upper part of Saqqajja Hill, amid concern about the geological fragility of the area after part of a retaining wall collapsed.

The site, known also for its cultural sensitivity as it lies above Phoenician remains and part of the Roman city of Melite, has been closed for emergency works.

Fr Eugene Paul Teuma expressed concern that buildings in the area, including the former Santo Spirito Hospital now housing the National Archives and the Franciscan Friary, are in “considerable danger”.

Part of the friary, mainly built in the 13th century, dates to Roman times.

But Fr Teuma explained that the Knights of Malta had imposed a particular condition for the friary if it were to remain outside the Mdina walls: it was meant to self-destruct if the site was taken over by the enemy.

This means the friary could come down with the slightest movement.

“Most of the underground rock is friable, cut through by Roman tunnels and World War II shelters 12 metres below street level.

“These tunnels lie above a thick layer of clay and beneath a layer of compacted soil, which is preserving pristine archaeology,” Fr Teuma said.

Back in 1980s, Fr Teuma reported deformation of the friary’s main refectory arches. Soon after, a three-metre deep sinkhole in Saura Street swallowed up a Mini Minor vehicle.

Another hole appeared on St Francis Street a few years ago, causing stone blocks on the friary’s facade to crack, he explained.

Fr Teuma is calling for a full archaeological investigation, a geological study and cavity mapping of the area as well as an investigation of any structural damage in surrounding buildings.

Photo: Mark Zammit Cordina

Alternative accommodation for residents

When contacted, a spokesperson said Infrastructure Malta was carrying out emergency repairs while planning long-term consolidation for the area.

It had closed off part of Saqqajja Hill and provided alternative accommodation to the residents of two houses located in the area.

While most of the work is required in the top layers of infill materials that date back a few decades, archaeologists authorised by the Superintendence of Cultural Heritage are on site to ensure that any unearthed remains of value are documented and protected.

The archaeologists will also examine the material that was swept from behind the collapsed wall onto adjacent fields by rainwater.

Part of the wall is being repaired to render the overlying road safe for construction vehicles that will be used for further, long-term interventions.

Infrastructure Malta is meanwhile extracting core samples ranging from nine to 40 metres beneath the existing road level.

These tests will extend from the Saqqajja roundabout to the Santo Spirito Hospital area “to ensure that the final solutions secure the entire zone, not just the location where the wall collapsed”.

The agency is also looking into reports of water ingress in nearby properties to identify its source and ensure it does not adversely affect the road foundations.

“Tests are ongoing but, according to initial information, the area lies mostly on a deep layer of clay.

"The presence of extensive vegetation next to the retaining wall also indicates the presence of underground water throughout the year, which can render the area unstable.”

Asked about the material that will be used to rebuild the wall, the spokesperson said Infrastructure Malta will be finalising plans in the coming weeks.

Rebuilding the collapsed wall

However, one option being considered is the embedding of reinforced concrete columns deep into the ground, bridged together with horizontal ground beams and an overlying slab beneath the road surface.

This solution can reinforce the retaining wall, the road and nearby areas.

Once such reinforcement is in place, the collapsed section of the wall can be rebuilt using masonry identical to the rest of the wall and, if necessary, stronger concrete foundations.

The agency is discussing potential interventions with the superintendence so that it can plan construction methods with the least possible impact on any archaeological remains and nearby historic buildings.

If excavations are required, extracted material will be put aside and examined by archaeologists before it is recycled for other infrastructural works or disposed of, the spokesperson added.