Here's a link to my answer to a similar question: https://www.houzz.com/discussions/love-this-look-but-how-are-you-keeping-the-steel-from-rusting-away-dsvw-vd~181816

Eggleston Farkas Architects thank you for replying to that question. That is the same steel we use on our projects and a very clear answer. Thanks again!

This is so beautiful! Are the steel walls in the ground or ground level. If they are in the ground what was the process?

Friday,
. The house was constructed on unstable former marsh land. In order to stabilize the area, the entire garden space was excavated down to a depth of approximately 15-20 feet to remove organic material. Engineered fill replaced this soil and the area was allowed to settle for several months prior to construction. Heliocoil pilings were then used to support the entire steel wall structure and to create support for the very largest boulders. Boulders were first set. The corten steel plate was bent on site, attached to these pilings, and templates created in order to cut the steel around the boulders. Access to the site was very limited. In order for machinery to reach the back of the property, a reinforced “road’ was created between the adjacent property and the house with barely enough space for the excavator to travel to the lower level. Moving each boulder and large tree to the back of the site was a very slow and challenging process. n.

Karin, thank you for your comment. We do not have a spec sheet as each project is so different and custom designed/engineered. I would give advise that research your corten steel as there are different grades of it (along with the various thicknesses).