Those are exactly the type of concrete castings you would expect to see being used throughout the City. My guess (could be wrong) is that the farang business owners in Boyztown may have helped finance this.
The entire water management system in Thailand needs to be modernized. They've been kicking this around for years with input from experts from around the world. Not only have they been dragging their feet on this massive project, but Thais (in general) don't know what "preventive maintenance" is, and I would guess that the water pumps in Pattaya are both outdated (under capacity) and poorly maintained.
I hate to make a mountain out of a mole hill, but it actually is a mountain. The lack of investment in infrastructure improvements in Pattaya over the past 50 years, coupled with the fact that the funds needed to support improvement projects disappear into thin air, has contributed to Pattaya completely imploding. The population (in normal times) has exceeded the capacity of the city's infrastructure, i.e., electric systems, water drainage and purification, roads and highways, as well as the buildings themselves, many of which are falling apart due to lack of preventive maintenance. Generally speaking, Thais don't fix anything until it breaks. Well the City is now broken.
Their solution to this problem was to choose the only option available to them, and that was to abort thoughts of investing trillions of baht in Pattaya's infrastructure, and start investing in expanding tourist destinations farther down the eastern seaboard (from Na Jomtien to Rayong). Thus you have the EEC Project (Eastern Economic Corridor), which has been in full swing for the past 5 years.
The town where I live (Bang Saray) is the first town on the southerly path of the EEC. Three years ago I watched them dig up all of the drainage pipes along the ocean (which were those cheap small diameter plastic pipes), and replace them with those large concrete castings. This was done under the supervision of the Navy. Even during the most brutal torrential rain storms we don't even get a puddle filled with water on our roads - yet Pattaya (at least South Pattaya) is completely under water. According to what I was told before making a decision to invest in Bang Saray, this is all part of the EEC expansion. The work I just described has continued south along the coast in Sattahip and now making its way towards Rayong.