ᐅ Concrete the cover of the shaft, 1.5 x 1.5 meters, using the same construction method as the main structure.

Hello everyone,
I have a shaft (see attached picture) where I need to cast some kind of cover.

Explanation:
The red row of bricks will be removed.
The blue area will be the cover.
The yellow area is an access opening into the shaft.

It will be filled completely with water later on.

Do I need to install steel beams and then cast concrete with a thickness of about 20cm (8 inches)? I was thinking of drilling holes by core drilling and then sliding the steel beams in and embedding them into the wall with concrete.

Thanks for your feedback.

Is there a plan for this as well?

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

How do you plan to make this waterproof?

There is no prefabricated element available with a hatch, and it would have to be installed using machinery, which is not possible.
A support column should also be avoided.

A core drill is available for embedding into the masonry.

Without an existing plan, it is difficult to make any recommendations here. Are these basement walls above and to the right? Are they made of concrete formwork blocks?

Is that a rainwater collection shaft?

The concrete works fine without steel beams; just add reinforcing steel bars and it will be fine.

Of course, shaft covers are available as factory-made parts. As a DIY project, it might not be suitable due to the lack of lifting equipment.

Sorry, I thought I wouldn't write a novel. It is a collection basin for water that will be properly sealed later.

All four walls are made of 25cm (10 inches) concrete formwork blocks with 14mm (0.55 inches) reinforcement.

Now a cover needs to be put on or inserted. Later, the whole thing will be covered with soil and planted, with a cover serving as an access point for cleaning and maintenance.

Remove formwork from ceiling shuttering with an opening of approximately 62cm (24 inches). Construct supports and reinforcement steel according to structural requirements. Proceed with concreting.