in our utility room we have what is basically an open drain with the pipe from the sinks and washing machine going into it. there is a plastic grille on it like you have in outside drains to catch leaves and it is about the same size.
our builder reckons it is a diy job: get a rubber bung/seal of some type and fill it with concrete above. it sounds simple but I don't know the name of the product to buy.
Either it is an amateur bodge, or the utility room was built or extended over the back yard with no thought of tidying the drain or of meeting building regulations.
I expect it is set in concrete and difficult to dig up.
Not all keen on covering it with concrete.
Ask around for a dependable and experienced local plumber to look at how you can keep the ability to rod it and to allow air admittance. If it is connected to a nearby soil pipe rising to roof level and has a manhole nearby it will not be so bad.