Soil Pollution in Thailand

Soil and groundwater are critical components of the environment, serving as essential resources for agricultural production, drinking water, and maintaining ecological balance. The protection of these resources is vital to ensuring food security, public health, and sustainable development. Contaminated soil and groundwater can lead to severe environmental and health problems, including the disruption of ecosystems, the spread of diseases, and the contamination of food and water supplies. Consequently, effective regulation and management of these resources are imperative for any country.

Thailand faces significant environmental challenges related to soil and groundwater contamination. Rapid industrialization, urbanization, and agricultural activities have increased the risk of pollution. Industrial waste, agricultural runoff, and improper disposal of hazardous substances contribute to the contamination of soil and groundwater. The country’s tropical climate, characterized by heavy rainfall and flooding, exacerbates the spread of pollutants, making it crucial to have robust regulatory measures in place. These environmental issues not only threaten the public health but also impact the economy, particularly sectors dependent on natural resources.

 

Development of Regulations on Soil Pollution

First effort on setting up regulations on contaminated sites in Thailand began with the establishment of standards for soil and groundwater by National Environmental Board (hereinafter “NEB” or “the Board”) in 2000. However, such standards had no requirements for target facilities to conduct regular sampling for land contamination or reporting. The situation has led to discovery of many contaminated sites, which are mostly industrial sites during the following 15 years. Soon after, NEB’s resolution suggested that Ministry of Industry would require some industrial facilities to perform regular sampling, report and remediation.

After some studies, Department of Industrial Works (DIW) published Ministerial Regulations on the Soil and Groundwater Contamination Control in Factory Areas on April 29th, 2016, which became effective in October 2016. Under the Ministerial Regulation, Notification of Ministry of Industry on the Contamination limit, Inspection Criteria, Notification, Report Compilation and Proposal for Control and Reduction of Contamination on Soil and Groundwater was announced in October 2016.

 

The regulation mainly targets 12 types of factories which are,

  1. textile yarn or fiber industry – type 22 (1, 2, 3, and 4);
  2. pulp or paper industry – type 38 (1 and 2);
  3. chemical industry – type 42 (1 and 2) ;
  4. paints industry – type 45 (1, 2, and 3);
  5. chemical related industry – type 48 (1, 2, 3, 4, 6, and 12);
  6. petroleum refinery industry – type 49;
  7. non-ferrous metal basic industries – type 60;
  8. electrical equipment (light bulb, insulation and transformer) industry – type 74 (1, 4, and 5);
  9. product finishing industry (polishing, painting, plating, anodizing) – type 100 (1, 2, and 5);
  10. central waste treatment plant – type 101;
  11. waste sorting and landfill – type 105; and
  12. Waste recycling industry – type 106.

 

The regulation also defined “contaminants” in soil and groundwater which are composed of 126 substances including volatile organic compounds (VOCs), heavy metals, and pesticides and insecticides. It requires newly operated factories to 1) collect soil and groundwater samples from factory areas, 2) compile monitoring reports as background levels before operation, 3) collect soil and groundwater samples on second time within 180 days after starting the operation, and 4) submit the report to Ministry of Industry within 120 days after due date of second time inspection with background values.

It also requires that existing factories to collect sample in factory area for the first time within 180 days after this regulation become effective and must compile a monitoring report within 180 days after the due date of first-time monitoring.

As long-term obligations, existing factories are required to 1) collect sample on second time within 180 days after the first inspection and 2) submit a report within 120 days after due date of second time inspection. In case that the report indicates contamination levels exceeding specified control values, business operators must compile a proposal to control such contamination or to reduce contamination such that is within control within 180 days.

 

Issues of the Current Regulations and Proposal for New Regulations

Although the regulation has fixed major problems on monitoring requirements, there are still many associated issues that would later emerge, such as there is no laboratory in Thailand that can analyze all contaminant parameters specified in this regulation, sampling period is flexible so that most of the facilities perform resampling when result is not favorable, construction quality as well as placement of monitoring wells, quality of sampling and sample handling etc. The DIW has been gathering feedback from industries and experts since its announcement.

Later, in 2023, DIW set up a working group to update the regulation and later on March 28th, 2024, the draft Notification of Ministry of Industry on Contamination limit, Inspection Criteria, Notification, Report Compilation and Proposal for Control and Reduction of Contamination on Soil and Groundwater B.E. XXXX was published on DIW’s website for public consultation. The content of the draft notification can be summarized below:

  • The new notification is intended to entirely replace the current Notification of Ministry of Industry, which was announced in 2016.
  • Factories can apply for exemption from the mandatory soil and groundwater sampling when soil of such factory is covered with impermeable materials or does not handling materials which can be considered as hazardous waste or having hazardous chemical of less than 1 ton per year.
  • The notification defines “standard” levels of contamination for soil and groundwater which are composed of 38 parameters of volatile organic compounds (VOCs) and heavy metals. The number of regulated components is reduced from 126 as set in the current regulation.
  • The notification defines “background” level of contamination to be derived from average level of at least 3 first samplings plus 3 times the amount of standard devia The sampling must be conducted at 5-points composite sampling points. This concept is newly introduced.
  • Under the draft, it is required that 3 types of factories monitor for all parameters specified in this draft notification that are central waste treatment plant – type 101, waste sorting and landfill – type 105 and waste recycling industry – type 106. All other types of factories are required to monitor for 9 parameters in soil (arsenic, cadmium, lead, manganese, mercury, zinc, total petroleum hydrocarbon C5–C8, total petroleum hydrocarbon C9– C18 and total petroleum hydrocarbon C19–C32) and 10 parameters in groundwater (arsenic, cadmium, lead, manganese, mercury, zinc, benzene, ethylbenzene, toluene and total xylene).
  • If a factory uses more than 1 ton per year of any contaminant specified in this notification after starting its operation, such a contaminant substance should be included in the scope of its regular soil and groundwater monitoring. Also, in case of reduced use of such contaminant specified in this notification into below 1 ton per year, the factory can apply for stop of
  • Installation of monitoring well must be conducted for at least 2 wells, one up-gradient and one down-gradient. The up-gradient well can be located in nearby factories.
  • In case of contamination level is found to be higher than background level or standard. The proposal for control and reduction of contamination must be done. After proposal is accepted, report on progress must be submitted periodically.

 

Standard levels for contamination are as shown in the table below.

No. Parameters Standards
Soil
(mg/kg dry weight)		 Groundwater
(mg/l)
1. Arsenic 23 0.01
2. Atrazine 5.8 0.003
3. Benzene 3.5 0.005
4. Benzo (a) pyrene 1.2 0.0002
5. Cadmium 79 0.003
6. Carbon disulfide 729 –
7. Carbon tetrachloride 2.0 0.005
8. Total Chromium – 0.1
9. Hexavalent Chromium 0.25 –
10. Copper 3,330 1
11. Cyanide 117 0.2
12. 1,2-Dichloroethane 1.4 0.005
13. 1,1-Dichloroethylene 912 0.007
14. cis-1,2-Dichloroethylene 303 0.07
15. trans-1,2-Dichloroethylene 277 0.1
16. Ethylbenzene 18 0.7
17. Lead 800 0.01
18. Manganese 1,765 0.08
19. Mercury 3.1 0.001
20. Methylene chloride 499 0.005
21. Nickel 1,471 0.02
22. Polychlorinated Biphenyls 0.56 0.0005
23. Pentachlorophenol 2.3 0.001
24. Selenium 130 0.01
25. Silver 368 –
26. Styrene 861 0.1
27. Tetrachloroethylene 72 0.005
28. Toluene 804 1.0
29. Total Petroleum Hydrocarbon (C5 – C8) 29 –
30. Total Petroleum Hydrocarbon (C9– C18) 2.1 –
31. Total Petroleum Hydrocarbon (C19 – C32) 1.3 –
32. 1,1,1-Trichloroethane 640 0.2
33. 1,1,2-Trichloroethane 3.5 0.005
34. Trichloroethylene 4.2 0.005
35. Vanadium 246 –
36. Vinyl chloride 0.95 0.002
37. Total Xylene 259 10
38. Zinc 6,670 3

 

This revision of the soil and groundwater monitoring requirement will definitely get support from industries since it should reduce cost of soil and ground monitoring in the long run and align better with international standards.