Got some bad soil delivered not sure how to remediate it

As the title says, I had some soil delivered earlier this year for my garden, and it seems to be very poor quality.

My plants are severely stunted. Direct-seeded and transplanted plants are barely growing 8 weeks later. (garden was great last year). While I don't have an EC and have not done a soil test yet, I suspect the issue is it's loaded with salts from too much commercial fertilizer or something.

My fault for not testing the soil beforehand. My guy who delivers soil has always been solid until now.

Anyway... I'm not sure what I can do now. I can't really don't think I can add anything to it in terms of more nutrients because it seems the soil is all locked up. I guess I could just water the hell out of it to flush it out but given it's like five yards of soil that was placed on top of my existing garden, the ability to leach it out seems nigh impossible. It would just continue to leach down into the soil below it, no?

So.... is my only option just scraping it all off and hoping for the best? Am I just screwed? I feel like I just killed my entire garden. Please someone tell me there's a reasonable solution here.

 

I think the first step is to get a full chemistry analysis.
Can you be more specific with quality?
what is the texture? Sand Silt Clay or loam?
Does it have reasonable structure?
Is it blended with organic matter?
Is the organic matter composted?
You might have a phosphorous deficiency if your seedlings are stunted.
You might have nitrogen drawdown if organic matter isn't composted