Anyone aware of the approx rough costing of a retaining wall currently?

27m L x 4m H holding in mud/clay

 

Just off the cuff from experience rather than exact 

That is a high retaining wall so would probably need to be buttressed. A couple of years ago I had a 28m x 0.2m wide x 0.9m high wall done for around 130,000 baht but you are not going to be anywhere near that.

Recent topic on wall building costs:

 

https://aseannow.com/topic/1348235-building-a-boundary-wall-cost-in-2025/