Beware Guanapo waters

“Ecological risk associated with use of rivers in the area is high, with the exception of Corbeaux Bay.

The reason for this exception is unknown.

“This high risk is because residents in the area use the river for personal uses, such as recreation and/or bathing. The consequences of exposure to heavy metals in water can be very costly to health of the residents and the economy in the area.” Newsday obtained an abstract of the report, done in May 2016 by a team led by Dr Denise Beckles from UWI’s Department of Chemistry in the Faculty of Science.

SWMCOL on Wednesday had told the JSC that lead is leaching from the Guanapo Landfill into local waterways such as the Guanapo River, which feeds into the Caroni Water Treatment Plant prompting some JSC members to decry a national catastrophe of a scenario of children drinking lead.

On Thursday the Water and Sewerage Authority (WASA) said water flowing into its treatment plant is properly treated by processes such as coagulation/ flocculation and sedimentation, which easily removed any lead contaminants and so produced drinking water that exceeded World Health Organisation (WHO) standards.

However the original UWI report warned that people in contact with the untreated surface and ground water at Guanapo could be risking their health, particularly anyone swimming/bathing in Guanapo River during the dry season.

The report said, “Landfill emissions can negatively impact the air, soil and water around them; and in Trinidad and Tobago, as well as the wider Caribbean, the ability of the current landfills to safely store waste is uncertain.” To fill this data gap, UWI did a full characterisation and modelling exercise of the Guanapo Landfill, in line with the Government’s solid- waste-management policy and existing efforts by the Water Resources Agency (WRA) and WASA to improve water quality in the Guanapo watershed.

“The study has indicated that Guanapo Landfill has a major influence on the water quality of the Guanapo River, though it may not be the only source, as other land uses play a significant role.

“Surface and ground waters are contaminated.

Of the parameters measured in the study the levels of heavy metals were generally of the greatest concern.

Sediments in the area can be highly contaminated with metals, [and] this is affected by season. Both water and sediment metal concentrations are higher during the dry season than in the wet season.” The report said the concentration of metal pollution in river waters is relatively lower in the rainy season apparently thanks to dilution. The slower flow of river water in the dry season also causes more deposition of sediments and therefore a higher concentration of heavy metals in river sediment.

These contaminants are removed during times of high flows, that is, the rainy season.

The report warned of heavy-metal contamination spreading outwards from Guanapo. “The geology of the area immediately surrounding the landfill is porous and heavily interconnected. There is a chance for the downward percolation of groundwater and leachate.

There is evidence that the landfill is impacting the water in the subsurface directly below the landfill.

“Contamination was observed at other groundwater monitoring locations, both shallow and deep at a greater distance from the landfill.

However, it could not be determined if this was as a direct result of leachate movement.” Noting the risk posed by leachate contaminants in local rivers, the report urged the remediation of the landfill.

“Mitigation works should focus on improving the collection, impoundment and treatment of leachate.

“Even with such a system in place, water quality in the Guanapo River will still be below acceptable standards until the contamination of the groundwater has been addressed by suitable techniques.

This can be done by increasing the capacity of the retention ponds, installing an active leachate treatment system, and implementing recycling and other activities to reduce waste (e-waste in particular).

Leachate treatment and other activities to reduce the contaminant loading of the leachate will go a long way towards improving the quality of the river water and bottom sediments.” The report said the air around the landfill had very low levels of volatile organic compounds, but the northern and eastern parts of the landfill should be further monitored.

“Soil samples had low permeability that may be due to a high degree of compaction, resulting in limited vertical transport of landfill gases.” Glad for the input into the research by local residents, UWI, SWMCOL and the WRA, the report said the work has empowered the community by way of providing accurate and reliable information about the quality of the en-