In a severe aggravation of pollution, an 800-metre-long trace of wastewater discharged into the Tha Chin River was found near Samut Sakhon’s Khlong Om Noi sluice gate, the Natural Resources and Environment Ministry’s Wastewater Management Authority said yesterday.
The Authority chief, Pairoj Sattayasansakul, and related officials measured dissolved oxygen (DO) value at 0.09 milligram per litre and biochemical oxygen demand (BOD) at 0.04 milligram per litre at the sluice gate. The standard DO level should be least 2 milligrams per litre. Water in Khlong Om Noi was polluted and black in colour, sending a foul smell into the air. There was no fish or oxygen foam on the surface.
Pairoj said this problem in Om Noi has been longstanding, as the area received wastewater from 941 factories and surrounding communities, totalling 100,000 cubic metres of wastewater per day. A helicopter survey by the Authority also found an 800-metre-long trace of black, foul-smelling water from Khlong Om Noi to the Tha Chin River, he added.
He said the solution was to build a wastewater treatment station. The Authority's proposal to build one, at a cost of Bt2.75 billion, with a capacity to treat 80,000 cubic metres of wastewater per day, had received the Cabinet's approval in principle in November 2012. He said the project, to be located on a 13-rai plot of land, was now pending the Cabinet's approval for implementation. He expected construction to begin next year.
Om Noi Municipality mayor Somsak Kwanmuang said his office could not completely solve the problem despite many public complaints of illegal discharging of wastewater into the public canal and many discussions with industry people.
"By law, local bodies can only order a factory to close for seven days. Many times in the past, after a day's closure of a problematic factory, some seniors in the province would ask me to sympathise with factory workers and reopen the factory with a condition that the factory tackle the problem," he said. He added that water pollution might also come from a lack of town planning as factories and residential houses were not segregated.
Om Noi resident Yupin Fakyim, 72, recalled the canal water being clear with plenty of fish, shrimps and crabs. She said it all changed when factories were built since 1957. She urged the authorities to solve the water-pollution problem.
Meanwhile, Public Health Ministry permanent secretary Dr Narong Sahamethapat said provincial health officials yesterday randomly collected 20 samples of fish, crabs and shrimps raised at 100 farms in Samut Sakhon's Mahachai Bay to test for carcinogens like tar and benzene.
The move followed Monday's accident when a 16-metre-long vessel, carrying used oil, sank in the area.
The test results should be out today. If the tar and benzene levels were high, the ministry would issue a warning for people not to eat them and would conduct weekly testing until the marine lives were cleared of such substances, he added.
The health officials, accompanied by Marine and Coastal Resources Office representatives, also surveyed people affected by the oil leakage and set up a mobile medical team at the bay area for one week, to provide advice and initial treatments, he added.
Narong said the oil slick, covering a one-kilometre radius, had been contained and was being treated. He urged the public not to swim in the area and urged operative officials to wear preventive gear for their own safety.