Cover shaft 1.5 x 1.5 concrete like structure

Hello everyone, I have the shaft (see picture attachment) where I need to pour some kind of cover.

Explanation. The red row of bricks will be removed again Blue should then be the cover Yellow an entry into the shaft

It will be filled with water later.

Do I need to insert steel beams and then concrete around them with a thickness of about 20 cm or so? I would drill holes by core drilling and then insert the steel beams there and concrete them into the wall.

Thanks for your feedback.

Is there also a plan for this?

I would try to find a concrete precast element and then provide a support in the upper right corner.

How do you want to make that waterproof?

There is no prefabricated part with a hatch as such and it would have to be installed with machine effort, which is out of the question. A support should also be avoided. A core drill is available for embedding into the masonry.

Without a plan of the inventory, it's hardly possible to recommend anything here. Are those basement walls above and to the right? Concrete formwork blocks? Is this a rainwater collection shaft? The concrete works even without steel beams, just add rebar and it's fine. Of course, there are shaft covers as FT. As a DIY project, probably not suitable due to lack of lifting equipment?

Sorry thought I wouldn't write a novel, it is a collection basin for water which will be sealed accordingly later.

All 4 walls are 25 cm concrete formwork blocks with 14 mm reinforcement.

Now a lid just has to be put on or in. Later the whole thing is to be covered with soil and planted, with a lid as an inspection opening to crawl in for cleaning etc.

Remove ceiling formwork with an opening of approximately 62 cm. Construct supports and reinforcement steel according to structural requirements. Concreting.