I don’t agree, the engineer should have foreseen reasonable predictable conditions.
A site survey should have added to the evidence.
Experience and local information would have added to the decision making process.
To add 800 fees and 10k building costs because he hadn’t investigated sufficiently is scandalous.
Used be a saying in the building profession "come in cheap and make it up on the extras”
A 2nd opinion is best option, and if it proves substantially different consider changing engineers.
Again, the engineer can only do what he is engaged to do. By my reading he was not asked to do initial soil compaction test. And i also reiterate that the only true way of seeing the foundation as a whole is to open the strip foundation. Which was done, and the engineer advises on the visual and physical inspection of these open foundations.
Was the engineer engaged to produce working construction drawings??
If he was you would clearly see a note saying that the foundation type is subject to site and soil conditions. The majority of one off houses in this country are build from planning drawings, not construction drawings... a situation that drives me mad!
Experience and local information would not have changed the soil conditions. Are you saying the engineer should have designed the raft foundation before opening the strips?? and charged accordingly without knowing if it was required or not??
also, i would be fairy positive here and say that the engineer is engaged at this stage to periodically inspect the work with a view to certifying stage payments and producing an opinion on compliance at the end. If so his first inspection is at the 'open foundation' stage. Clients invariably confuse this to be some kind of 'supervision' engagement, which it isnt.
The OP needs to know that there is absolutely nothing strange or unusual about this situation.
But as Kerak states, get a second opion.... but as i stated above also, foundations are not something either the client or the certifier should skimp on.