A simple storage box to keep stuffs into and to keep everything neat without actually taking additional space specially when the existing space is nearly cluttered. The idea of having an inground storage box came to my mind when I was (still doing) my solar project to be able to store my batteries somewhere and didn't want to take additional space and wanted everything to blend inside the environment. The box would also house some electronics and wiring and make all connections and keep everything out of view such as providing power to my garden lights and pond accessories.
So the first thing is to find out where to put the storage box which I found in a corner close to my pond and people rarely go over there and I could easily store 5 car batteries of 12v easily and since these batteries emit gasses, it is best suited outside and needs to be aerated so the place is ideal.
Other ways of doing this project was to use building block to make the enclosure and then use slabs to cover it or even make a mould inside the hole around the soil and then just pour concrete and put rebar in it that would have looked much cleaner and to the right side and then later on the slabs would have just to be placed on top to cover it which would have been much easier as oppose as the way that I made it.
Step 1: Measurements and Materials Needed
Once the location has been found, the first thing that I did was to place one battery on the ground and measure its length, width and height which then I estimated 5 car batteries Stacked side by side to give the length and then allowed for about 10 cm on each all 4 sides because of the concrete walls and that would also serve as support for the slabs that would cover the box (as a top lid) but also to be able to walk on it as even though people don't go over there frequently, sometime people do adventure specially to clean, store things temporarily or harvest some fruits. Once these has been done, the markings can be drawn on the ground and then the digging can start.
Since I had concrete leftover due to previous construction i wanted to use those and later realised my mistakes and other alternatives that I had. For the box walls, I needed to add rebar in order to better hold the structure in place, thus I measured the length, width and height and then cut the rebar according to its uses. Because I could not make the mould in place in the ground to then just insert the rebar and concrete in one place (too lazy) I just measured the length and width of the longest two sides, then I divided into 4 so that I could get 4 slabs which will be easier to carry for me from one place to another. Then for the 2 sides which were very short I could just make 2 slabs for each side and then bring them on site.
Step 2: Prepare Rebar, Mould and Pouring of Concrete
From there on it was time to prepare the rebars cut to length for each slabs and the use my pieces of wood to make the moulds in which the slabs will be made. The plastic was laid down which would prevent the slabs to stick to the existing concrete and the the mould can be assembled onto the plastic sheet . Then it was time to start pouring the concrete in the moulds about half way and then add the rebar and continue to fill until the desired / required height has been achieved.
Once again the mistakes that I made before of wrongly mixing the concrete and making these during the winter time didn't help at all. When I removed the slabs from the moulds, they started to crack and broke like biscuits even when dried and I could see the gravel with gaps between them showing signs of wrong fusion. At that time I was just desperate and put those in a corner until there was some additional work that needed to be done where additional materials were brought in and also good sealed concrete where I could again resume with the project.
Step 3: Putting the Slabs Into the Ground and Make the Box.
Back to my hole I made sure that I left enough room and made the hole as boxy as possible to get the right size. Then I prepared a concrete mix and laid in have a flat and levelled base in ground. From there I let it dried for about a day and then brought the slabs and put them in the soil which was a nightmare as they would break into small pieces and fall all over the place and when put aside wouldn't stand at all. I has to enlarge the hole again on three side as one side was the retaining wall. From there I would put the slabs into the hole on all four sides and then the previously prepared rebars was pushed into the ground behind the slabs where I would use pieces of wood to retain the slabs in place and then start pouring concrete on the back of the slabs between the soil so that they would stick and then had to use other stuffs just to be able to retain the slabs and the concrete poured in such as battery, wood pieces, rocks etc...
I had to do these actions up until the whole bos was completed and prepared concrete around 4 times during different days as once it cured I could move onto another part of the box as you can see in the pictures. When the box was complete I had to cut any excess rebar as people could step on those pieces and get hurt as well as would prevent the slabs from laying flat and be unstable. After some time I prepared additional moulds 5 of them where slabs would be prepared to be used to cover the box as well as to be able to withstand much weight and that time they came out nicely and very polished (well personally I was satisfied) which were hard and be very sure that they won't break even under huge weight. Later on the slabs were placed on to the box which went all well and I was very satisfied and then noticed that I didn't leave any space for my wires and other things to go in and out but hey lets leave that for another project. Picture of the slabs being put onto the box and also how I also used it to put my water hose as I saw that It wouldn't get dirty as before it was on the ground and when water mixes with the hose it just gets dirty.