Where I stay, theres a site (see intro here) nearby that used to be a coal gasification plant (produces coal gas for lightning etc.). The plant contaminated the soil with PAHs and heavy metals with decades of use. The land was laid fallow for i think 10-20 years now.

Currently, our Government is using thermal remediation to purge the contaminants. Essentially its 24/7 heating of the soil, with fumes piped through chambers where its misted and foamed to remove pollutants. The tender was announced on public news (link here).

The issue is the site is densely populated. Despite the filters, the fumes released are still pungent, with a foul smell thats like a mix of LPG, sewage, burnt rubber and tar. Residents have been reportedly feeling sick, from anything like hay fever/allergy/flu, to inflammation, nausea, difficulties breathing to vertigo/black-out and gastro-intestinal issues.

I did some research, and my guess is its PAHs but not sure how to detect heavy metals since most are odorless except for Arsenic. The project contractors claimed they have filtered and did soil washing but the odor is just too pungent to ignore.

Im just thinking if its reasonable and safe for the remediation to be done on-site in a dense residential zone? The contractors claimed that systems and filters are working well and they did not detect any pollutants, and its within safe limits. Seems contradictory when empirically, residents are all falling very ill.

Otherwise, what other alternatives are there to thermal remediation on-site? I suggested them to halt all project works in the interim to investigate and prevent further leaks. However, the contractor and agency insisted to proceed and tweak along the way, all while exposing residents to the fumes.

  • It's relatively easy to buy gas sensors for the air pollution component of this, and you could likely even buy cheap aliexpress or banggood air quality monitors to get some idea (volatile organic compunds or VOC is they keyword). Heavy metal testing requires a lab, but there are many in Singapore (and Maylasia, or elsewhere, you only need a few grams for a test sample: google.com/search?q=singapore+soil+heavy+metal+test
    – Móż
    Mar 4, 2021 at 23:22
  • Getting into a fight with your government over safety is going to need legal as well as scientific expertise, because this is one of the classic situations where people die and 30 years later the government or companys says "sorry we lied about that for the last 30 years". Community protest is necessary, but only one component, and as a kiwi I can't really help... you'll more than I doabout the political stuff where you live. If you can get a university environmental department or someone from one on side that will help a lot.
    – Móż
    Mar 4, 2021 at 23:25
  • Meantime, for those who have reasonably airtight homes, HEPA air filters work really well. In Australia bushfire season where the smoke cuts visiblity to 100m in the middle of Sydney, a portable in-room filter can cut PM10 from >1000 to <10 fairly realiably. It's a race between air leaking in bringing new smoke and the filter removing it. I own several, and the key thing seems to be buying extra filters with the purifier... and if you can't get extra filters don't buy the unit that uses them. When it's bad you might need a new filter every day, you can see the dust they have filtered out.
    – Móż
    Mar 4, 2021 at 23:27
  • The obvious alternative is what Singapore always does... truck it to Maylasia and dump it, or process it there. Bad alternative! Better to use a chemical incinerator that's been modified to deal with the huge amount of ash that's produced when you "burn" soil. That's expensive, but there are companies in Singapore that do it: nea.gov.sg/our-services/pollution-control/hazardous-waste/… (incinerator rules exist, therefore incinerators exist)
    – Móż
    Mar 4, 2021 at 23:33
  • We do export to SEA nations for recycling and salvage but I don't think any is reckless dumping..which is what Indonesia, Vietnam is facing etc. We have our man made landfills which is however running out now. Thanks for the comment on the fumes. It's challenging to capture PAHs and VOCs on personal handheld devices. Testing professional is expensive and government can register and attribute to environmental sources.
    – Thinkerer
    Mar 8, 2021 at 4:39


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