ᐅ Substructure for Driveway on Cohesive Soil

Hello everyone,
I requested a quote for our future driveway. I asked the landscaping contractor how the substructure and drainage would be designed.

According to the soil report, there is about 70-90cm (28-35 inches) of topsoil on our property, partly mixed with gravel. Below that is load-bearing clay soil, which is only partially permeable to water.

Everywhere I read that the organic material should be completely removed.

According to the landscaping contractor, it is completely sufficient to excavate only enough to make room for a roughly 25cm (10 inches) thick base layer and an approximately 15cm (6 inches) thick upper base layer plus the paving. Proper infiltration should not be an issue with the right choice of stones and jointing material.

I am a bit skeptical about this and would like to hear your opinions.

Thanks in advance

kbeh1988 schrieb:

According to the landscaper, it is perfectly sufficient to excavate only as much as needed to make space for a bottom base layer about 25cm (10 inches) thick and a top base layer plus paving about 15cm (6 inches). With the right choice of stones and jointing, infiltration should not be an issue.

I’m a bit skeptical about this and would like to know your opinion.

I’m not skeptical. There are heavy rains a few times a year (increasingly), and the water just runs off the surface. This should be monitored by the local water authority. If you meet their requirements, this is a practical approach.

Please share the composition from the soil report. I’m less concerned about infiltration, but more about the load-bearing capacity and the possibility of settlement.