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Rain water sewerage ”Grønnemosen”

Sub base compensation

Project name Rain water sewerage ”Grønnemosen” Volume 1.300 m³ expanded clay 10–20 mm Location Søborg, Denmark Year 2013-2014
Contractor Per Aarsleff A/S Designer COWI A/S Owner/Builder Nordvand A/S


As part of the climate change adaptation Nordvand A/S has established a new system for managing storm water in Søborg. The rainwater sewer system is running through the Green Marsh where there is soft soil and thus probability for settings. In order to neutralize the settings of the sewer system, expanded clay 10-20 mm was chosen as load compensation and load reduction.

Why Expanded Clay:

Expanded clay was due to the low density the only option to the job. Other filling materials were considered but pneumatic blowing and delivery of 100 m3 at a time were decisive factors.


Expanded clay was tipped directly into the excavation as load compensation. The access conditions were very narrow and required the best drivers. Expanded clay was distributed and compacted with tracked vehicles. Between the sewer pipes expanded clay was pneumatic blown and compacted with a light vibrating plate.

Key Issues:

Blowing and Load reduction

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