Make contacts with and get to know the architects, structural engineers and general contractors in your area. Let them know your capabilities and availability.

1) Whether clients overlap or not, clear it with your employer first. They would likely have grounds to fire you if they find out. If a client knows you work for them, they can sue them, too. May not go anywhere, but it's an added risk of potential defense costs. And if you slip up and use any resources owned by them (books, software, computer, etc.), then they may not be able to be dismissed so easily.

2) How would this work, exactly? Let somebody else do the drilling and you assess what they pull up? Or are you thinking just shallow stuff for slab subgrades and the like?

3) Not sure how things are in your area, but residential might be tough. It's usually not required, and so convincing somebody to spend a few thousand dollars on your report will be a tough sell.

4) You might try knocking down doors at some contractors offices - GCs, site contractors, and foundation contractors. Most of them will run into an issue somewhere and need an assessment, though that kind of work may not fit with your day job.

Make friends with some local Civils. We get a lot of referrals from them.

I've often done work with other clients while employed by another consultant (office). They were aware of it and the condition was that my other work would not interfere with my office work (grounds for firing). Most offices were unhappy about it, but there was little they could do about it. First thing I did was approach my client to see if the work could be done through the office.

I checked with my lawyer and he noted that if you informed your client that the office had no involvement, then there would be no liability for the office. Things may be different in other jurisdictions. My projects included large warehouses and 20 storey buildings.

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

"I checked with my lawyer and he noted that if you informed your client that the office had no involvement, then there would be no liability for the office."

I have not check with a lawyer, I`ve always heard that it goes a little bit beyond this - if you use a work laptop, work software (CAD), a work reference book, or even a work pad of paper for your moonlighting gig, your office could be help liable.

I always use my own equipment, including my own laptop computer even when at the office... not even used company pencils. It used to irk the IT department at the last place I worked. At the end of the day, I would upload my day's work from my laptop.

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik