Recently this water tank was constructed (poured concrete). (I presume it is a water tank, as they laid blue plastic/PVC water pipe, perhaps 24 in. dia., in the vicinity at the same time.) After the outside was finished, they erected this dark (almost black in the picture) inverted umbrella-like screen around the base. I have never seen such a thing, either during construction, or around a finished tank. What is its purpose?
Turns out this was the beginnings of a larger tank (shown in this image) that will encompass the inner concrete tank. As work has progressed, they are welding plates onto the edges of the umbrella-like structure, vertically, to form a cylinder. Having exceeded the height of the inner concrete tank, they are now rounding off the top.
Looks like you are looking at a water tower under construction. There tends to be three main types of water tanks for water distribution systems: Volume, Pressure and Combination.
The first is for mainly for volume and it basically the equivalent of a reservoir. These tend to be built at ground level, and have a large uniform radius from bottom to top. This gives a large volume without much pressure due to ground proximity. Though if built on a nearby hill could provide a decent pressure to the system below.
The second tends to be for pressure. The main matter for supplying pressure pressure is simply height above ground. These type of water towers tend to have narrow central shaft and a wide short top. The pipe running up the centre provides a connection between the water distribution system and a small reservoir at the top of the tower. The reservoir at the top of the tower allows for slight draw downs due to water use without dramatically affecting the height of the water column and thus the pressure in the water system.
The Third type is a combination pressure and storage water tower. These tend to have a a cylindrical shaft smaller than a pure storage water tower and larger than a pure pressure water tower. The tower tends to maintain the radius for the full height of the tower.
I would suspect that what you are witnessing is the construction of a pressure water tower. I am guessing they are building the reservoir at ground level where its easier to work on. Also less damaging should something go wrong and it falls. They will jack/hoist the reservoir up as as the central shaft is built under neath is to support it. In the end it might look something like this:
A very similar one has just been built in this area. The steel "umbrella" may be to retain any water leak from the central tank. I had never seen one previously. Update -June 28. It is a conventional water tank, they do most construction close to the ground then lift it to the top and finish it.