24/11/2024

Monaco Bel Air: Completion of Works by Soletanche SAM and Soletanche Bachy France Teams!

The teams from Soletanche Bachy France and Soletanche SAM have completed the deconstruction, excavation, and retaining works for the Bel Air project, located on the heights of Monaco.

Due to its location on the slopes of the Azure mountain, this technical project required numerous environmentally friendly solutions (eco-design, electrified equipment, etc.).

Project Context

Due to limited space for new developments, Monaco focuses on demolition and reconstruction to create new housing. The Bel Air residence project, situated at the northwest border of the Principality, is part of the National Housing Plan (PNL). This initiative will lead to the construction of a residential and commercial complex consisting of three towers ranging from 13 to 24 stories.

During the six-month preparation phase, the teams secured the site, set up a logistics area for semi-trailer turnarounds, installed a gantry crane for bungalows, built on-site facilities and pathways, and collaborated with Monaco’s services to electrify the project. Heavy work then began. Using three electric Brokks, the demolition phase evacuated 25,000 tons of debris between July and December 2023. By early 2024, a large work platform on the rocky base was ready for mass excavation.

The project also included civil engineering structures such as beams, slabs, and supporting columns integrated into the future building. These tasks were completed under challenging access conditions, with workshops over 25 meters high. Site logistics required exceptional coordination, given the constraints of a single entry/exit point. The greatest challenge was synchronizing multiple activities—micro-blasting, excavation, demolition, drilling, formwork, concreting, and debris removal—within the confined space.

Reducing the Project’s Environmental Impact

The teams focused on eco-design and phase optimization to minimize resource and material use. The initial design planned for 12,835 linear meters of nails, 1,122 meters of anchors, and 82 micropiles. However, the efforts of the teams and the design office reduced these figures to 8,323 linear meters of nails, 656 meters of anchors, and 28 micropiles.

Project Progress

The works aimed to prepare a platform for the general contractor to build the new Bel Air. This involved lowering the foundation level of the future building by 6 meters from its existing level, widening the base by 10 meters, and creating a vertical retaining wall 32 meters high.

Results

Reduced material, cement, and steel usage, as well as lower energy and water consumption, leading to a 560-ton reduction in CO2 emissions just for supplies.
To minimize noise and air pollution, Soletanche Bachy prioritized electric equipment, such as drills and electric Brokks.

Switching from thermal to electric drilling reduced non-road diesel (GNR) consumption by 70%. Acoustic barriers, a 10-meter-high debris shield, and misting systems were installed to limit dust and noise, essential given the sensitive environment and the nearby active Princess Grace Hospital below the site. The micro-blasting method involved explosives to remove 37,000 m³ of rock.

The excavations progressively gave way to secure rock walls with over 4,000 m² of concrete lining, 7,000 meters of anchors, and 600 meters of micropiles. A low-carbon shotcrete mix was also used, reducing CO2 emissions by 167.6 tons.

Congratulations to the teams for completing this project, which required exceptional technical and organizational precision!