Damage at the flooded Bang Poo Industrial Estate is estimated at 900 million baht as officials work to prevent future occurrences of the flooding that has crippled factories.
Veeris Ammarapala, governor of the Industrial Estate Authority of Thailand (IEAT), said manufacturers inside the industrial park had made a preliminary assessment of the damage at between 800 and 900 million baht.
"The damage is a rough estimate by the factory operators. They are trying to determine the cause to claim compensation from insurance," he told an NBT programme on Friday.
The industrial park in Muang district of Samut Prakan houses about 500 factories making goods for both domestic consumption and exports, according to provincial information.
Bang Poo suffered what the IEAT chief admitted were the "worst floods" since the estate was founded in 1977. It is one of the oldest industrial zones in the country.
Heavy rains in the small hours of Aug 29 lashed the industrial park and neighbouring areas for hours, leaving them almost a metre under water. Pictures showed the water level up to the roofs of parked cars on the premises.
Mr Veeris said the unusually heavy rainfall exceeded the water management capacity of the park. The estate's network of ponds can retain 350,000 cubic metres of water -- but more than three times that amount hit Bang Poo that day.
The agency will seek state permission to build new canals to drain more water to the Chao Phraya River, he added.
Suchatvee Suwansawat, the president of the Engineering Institute of Thailand, said on Wednesday the area around Bang Poo is vulnerable to flooding. The pan-shaped area has sunk beneath sea level after more than 50 years of underground water usage, he said.
The drainage system is inadequate for the density of factories, he added.
The institute proposed more water retention areas be built for industrial and public use, including exercise parks.