Chemical characterisation of the water resources in the Heights of Guanapo, Trinidad: science and the social context

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1 Topic: Watershed Management & Solid Waste Management Chemical characterisation of the water resources in the Heights of Guanapo, Trinidad: science and the social context Denise M. Beckles, Grace-Anne Bent, Leonette Cox, Sharda Mahabir, Vincent Cooper, Gideon Ramtahal, Maria Allong Abstract Solid waste disposal in Trinidad and Tobago is accomplished via five landfills, intended to store waste safely and prevent release of contaminated material; however, the extent to which local landfills can achieve this aim is unknown. The environmental impact of leachate and other solid waste products can be significant, and this lack of reliable data limits the ability of stakeholders in solid waste, water and community management to deal effectively with the issues associated with landfills. In addition, there is often little cooperation among interested parties, leading to fragmented studies and unused data. The Guanapo area includes a small landfill without an engineered liner, quarrying and farming as well as residential uses. The Guanapo and Maturita Rivers may be influenced by these activities, and combined they flow into the Caroni River, a major source of drinking water for Trinidad. A comprehensive chemical characterisation was done for the surface water supplies in the area for a variety of parameters in both water and sediments over a two-year period. The results to date indicate that in most surface water locations, the parameters of greatest concern were metals (Cd, Cu, Pb, Hg; mg/l), nutrients (nitrate-n, mg/l; phosphate-p; mg/l), and turbidity (1-360 NTU). Sediment concentrations for metals were orders of magnitude greater. The results indicate that the surface water supplies in the Guanapo area are influenced by a variety of contaminants which has implications for all water users, both public and private. The inclusive approach used during the project activities ensured that the data generated had the desired wider societal impact, resulting in a number of positive changes by the landfill operator, as well as a more informed community. Introduction Solid waste disposal in Trinidad and Tobago is accomplished via five landfills across the country, of which the Solid Waste Management Company Limited (SWMCOL) manages four; three in Trinidad (Beetham, Forres Park and Guanapo) and one in

2 Tobago (Studley Park). In 2004, approximately 530,090 tonnes of waste was deposited at the three SWMCOL landfills in Trinidad (CSO 2007), and it is estimated that by the year 2020, this value will rise to 1.4 million tonnes (Singh 2009). It is clear that waste disposal is, and will continue to be for some time, a major concern of national development. This conclusion is supported by the recent production of an integrated solid waste management policy document (EGARR 2012), which outlines the Government of the Republic of Trinidad and Tobago s agenda for solid waste management to the year A properly designed and operated sanitary landfill may minimize the impact on the environment; however, this is not the norm in Trinidad and Tobago and the wider Caribbean. The use of improper waste disposal methods can have significant impact to human health and the environment. The percolation of water through the waste generates leachate, a highly toxic liquid that may contain heavy metals, toxic and/or persistent organic pollutants, plant nutrients, biodegradable organic matter and pathogenic microorganisms. The ability of the landfills in Trinidad and Tobago to adequately contain leachate is unknown. The concerns surrounding the landfill are more complicated than simply a matter of determining contaminant concentrations. The Heights of Guanapo community is itself divided on the issue of what to do about the landfill, as the landfill is also a source of livelihood to residents who scavenge the garbage piles. Legal and illegal residential and agricultural land use dominates the immediate area, and so emission of pollutants of all types from the Guanapo Landfill has the potential to impact the people of the Heights of Guanapo. Strong environmental decision-making requires reliable scientific data; this is often lacking, and can hurt the decision-making process. The goal of this study was to assess the level of contamination in the surface water resources of the Heights of Guanapo, to provide national stakeholders in the area of solid waste and water resources management with vital, current and accurate data concerning the level of contamination occurring around the Guanapo Landfill in Trinidad and to facilitate the positive interaction of community, university and Government stakeholders. Experimental Site Description. The Guanapo Landfill is situated in the Heights of Guanapo area, which is in the foothills of the Northern Range in the north eastern part of Trinidad. There are a number of rivers that flow through this area; the landfill sits between the El Cedro and Maturita tributaries, both of which flow into the Guanapo River, and eventually join the Caroni River. Figure 1 illustrates the site and the points at which samples were taken.

3 Figure 1. The Heights of Guanapo area, showing the landfill, important water courses and the locations at which samples were taken. 1, Leachate Pond; 2, Leachate Stream, 3, Georges; 4, Corbeaux Bay; 5, River Valley; Quarry not shown. Not shown in the figure is one surface water sample point that was taken far upstream near the quarry. The land use in the catchment is primarily forested (79%), however, agriculture, the landfill, quarrying operations and residential and other light industrial activities also occur in the area. The landfill itself has been active as a dumpsite since the early 1970 s, in 1983 the Solid Waste Management Company Limited (SWMCOL) took over operations, upgrading the facilities to include a leachate collection system and gas vents. (Chang 1998) The landfill today covers some 12 hectares and receives roughly 270 tonnes of waste a day.

4 Sample Collection. Surface water and sediment samples were taken over a two year period. The sites at which samples were taken are illustrated in Figure 1; these included samples taken from one of the leachate ponds, an off-site leachate stream, and rivers in the area. Samples were collected in pre-cleaned plastic or glass bottles, as appropriate to the analyte of interest. Once collected, samples were stored at 4 C until analysis. Analytical Methods. All of the water samples were analysed for a wide variety of analytes, however for this paper, only the following analytes will be discussed: metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn; Method 3125, metals in water by ICPMS), nitrate-n and phosphate-p (Method 4100 B, ion chromatography with chemical suppression of eluent conductivity) and turbidity (Method 2130 B, turbidity by nephelometry). The water analytes were measured using procedures from the Standard Methods for the Examination of Water and Wastewater (SMEWW, 1998). Sediments were analysed for the same suite of metals. Stakeholder Engagement. Throughout this study, major stakeholders were always kept appraised of the different stages of the work, as well as significant findings. This was achieved through regular community meetings at the Heights of Guanapo, discussions with the Guanapo Community and Environmental Development Organisation (GCEDO), meetings with management at both the Solid Waste Management Company Limited of Trinidad and Tobago (SWMCOL) as well as the Water Resources Agency (WRA). Results and Discussion The surface water in the Heights of Guanapo shows evidence of influence by the activities in the area. This is particularly evident in the values for a variety of parameters found at the various sites. Tables 1, 2 and 3 show the concentration of selected metals and physicochemical parameters in surface water (Table 1 and 3) and sediment (Table 2) in the Heights of Guanapo. The data show wide variability in the concentrations for most parameters. The variability in the leachate concentrations is a general trait, as the leachate composition will be affected by a variety of factors, including the types and volumes of the waste that is disposed of in the landfill the age of the stored material, the hydrogeology of the site and climate, particularly the amount of rainfall (Abbas 2009). In 1995, the composition of the waste at the Guanapo Landfill is approximately 28% organics, 20% paper, 6% glass, 10% metals, 20% plastics, 9% textiles, 6% rubber and leather, 1% other (CSO, 2007); it is likely that these data are somewhat different today.

5 Table 1. Selected metal concentrations found in surface water samples in the Heights of Guanapo. Values in the table show the minimum-maximum range for the metal over the entire study period. Concentration, µg/l Cr As Cd Pb Hg Cu Zn Leachate Pond BD BD Leachate Stream BD BD Georges BD BD BD BD BD BD BD Corbeaux Bay BD BD BD BD BD BD BD River Valley BD BD BD BD BD BD Below detection. Quarry BD BD BD BD BD BD BD Table 2. Selected metal concentrations found in surface sediments in the Heights of Guanapo. Values in the table show the minimum-maximum range for the metal over the entire study period. Concentration, mg/kg dry weight Cr As Cd Pb Hg Cu Zn Leachate Pond BD BD BD Leachate Stream BD BD BD Georges BD BD BD Corbeaux Bay BD BD BD BD River Valley BD BD BD BD BD BD Below detection. Quarry BD BD

6 Although the Guanapo Landfill is classified as municipal waste only, it is highly likely that hazardous materials, for example, batteries, will enter the landfill comingled with domestic waste. This can have an impact on the metal concentrations seen in the leachate. The concentration of metals in the surface water resources in the Heights of Guanapo do seem to indicate that the landfill is influencing the rivers and streams in the area. There is at least one direct leachate transport point from the landfill, the Leachate Stream, which empties into the El Cedro Tributary. In times of high rainfall, there have also been breaches at the leachate ponds, in which case the Leachate Stream becomes a river, carrying large quantities of leachate into the environment. In addition, the metal concentrations in the sediments are at considerably higher concentration. This is a common observation, as it is possible for the metal ions to either adsorb onto suspended sediments which are then deposited (Singh 1999, Zahra 2014). Table 3. Selected physicochemical parameter values for surface water samples in the Heights of Guanapo. Values in the table show the minimum-maximum range for the parameter over the entire study period. ph DO, mg/l Turbidity, NTU Nitrate-N, mg/l Phosphate- P, mg/l Leachate Pond Leachate Stream Georges Corbeaux Bay BD River Valley BD BD Below detection. Quarry BD However, there is also evidence that the landfill is not the only source of contamination the area. The data indicates that all of the metals observed in the leachate can also be found in the river water and sediments at the Quarry site (Table 1). This location is not influenced by the landfill, and so highlights the additional role of the quarry activities on the quality of the Guanapo River. At the George s site (Site 3) the results for turbidity and phosphate-p (Table 3) also indicate the presence of other activity. On the day with the highest turbidity at George s (363 NTU), the turbidity in the Leachate Stream was only 140 NTU. Given the likely effects of dilution on entry to the Guanapo River, it is clear that there was some other activity in the area that was causing the high turbidity at the George s site. This, in conjunction with higher nutrient loadings at this location, suggests that the agricultural activities

7 which also occur in the area may have some part to play in the water quality of the Guanapo River. The role of the residential activity in the area should not be left out, as a significant fraction of residents use pit latrines, particularly in the areas close to the Maturita Tributary. (Surujdeo-Maharaj 2012) Regardless of the sources, it is clear that the lower reaches of the Guanapo River are polluted with a variety of chemicals. Using the Canadian Environmental Quality Guidelines for Aquatic Life as a water quality benchmark (CEQG 2014), the river water for all of the surface water sites sampled exceeded the standards for cadmium, lead, mercury and copper. For the sediments, the situation was similar; with the exception of the River Valley site, all of the sites had sediment metal concentrations exceeding the standards (CEQG 2014) for all of the metals monitored in this study. The situation at River Valley was only slightly better, as it did not exceed the standard for mercury. These data show an increasing level of pollution over time; as earlier studies (Surujdeo-Maharaj 2012) reported much lower levels of a variety of water quality parameters in the water of the Guanapo River. Data collected between 1993 and 2010 showed the following ranges for selected analytes: phosphate-p, mg/l; nitrate-n, mg/l; turbidity, NTU; cadmium, µg/l; chromium, µg/l, copper, µg/l; lead, µg/l and zinc, µg/l (Surujdeo-Maharaj 2012). With the exception of phosphorus, the other parameters all indicate worsening conditions with time, highlighting the need for remedial action. This increasing level of pollution is of concern to the residents of the Heights of Guanapo as well as to the major stakeholders, SWMCOL, responsible for management of the landfill, and the Water Resources Agency (WRA), responsible for managing the water resources in the area. The residents of the area, many of whom have lived there for over 25 years (Surujdeo-Maharaj 2012) are concerned about the quality of the water in the river, as it is used for a variety of activities, including recreation, irrigation, washing and in a small fraction of cases, cooking. Prior to this study, the community as a whole did not have access to scientific data on the quality of the environment in their area. To address this the study included three public meetings, as well as a number of more informal interactions with the members of the Heights of Guanapo community. In addition, the two institutional stakeholders, SWMCOL and WRA were provided all of the data from this study. This has already paid dividends, as SWMCOL has already used the data to modify policy surrounding the Guanapo Landfill. The organisation has aggressively pursued a waste segregation scheme, removing plastic, white waste and other bulky material from the waste stream entering all of the country s landfills. This material is shredded and provides a source of raw material for recycling. More specific to the Heights of Guanapo, the Guanapo Landfill is to receive a new leachate treatment

8 system, as an important step in reducing the level of pollution in the Guanapo River. The consultants involved in this project have already expressed interest in the data collected in this study, as it will provide a recent, reliable baseline for their own investigations. And as one final note, the data from this study is also being utilised by the Land Settlement Agency, the institution responsible for dealing with unlawful tenancy on State lands in Trinidad and Tobago, as they work to regularise the residents in the Heights of Guanapo. The interplay of science, community and institution in this study has resulted in rapid and major change in all aspects, and is set to serve as model for similar studies at other landfills in Trinidad and Tobago. Conclusions The surface waters in the Guanapo River are influenced by human activity in the Heights of Guanapo. The water is impacted by the landfill in the area, as well as quarrying, agriculture and residential activities. The frequent and open communication among all of the stakeholders resulted in a number of positive outcomes, including active steps to remediation of the landfill leachate, along with more long-term actions to improve the well-being of all the entities with an interest in the Heights of Guanapo. Acknowledgements The authors are grateful to the University of the West Indies-Trinidad and Tobago Research and Development Impact Fund, the Solid Waste Management Company Limited, and the Water Resources Agency for their assistance in facilitating this study. References Abbas, A.A., Jingsong, G., Ping, L.Z., Ya, P.Y. and Al-Rekabi, W.S Review on landfill leachate treatments. Journal of Applied Sciences Research 5(5): Canadian Environmental Quality Guidelines (CEQG) Canadian Council of Ministers of the Environment. URL: Accessed May Central Statistical Office (CSO) Chapter 14 Solid Waste. In First Compendium of Environmental Statistics. Trinidad and Tobago. Ministry of Planning and Development, Government of the Republic of Trinidad and Tobago, Port of Spain, Trinidad and Tobago.

9 Chang, T A visual assessment of the existing solid waste disposal sites in Trinidad and Tobago. The Trinidad and Tobago Solid Waste Management Company Limited, Port of Spain, Trinidad and Tobago. EGARR & Associates An Integrated Solid Waste/Resource Management Policy for Trinidad and Tobago. Final Draft. Government of the Republic of Trinidad and Tobago. Port of Spain, Trinidad & Tobago. Singh, A.K., S.I. Hasnain and D.K. Banerjee Grain size and geochemical partitioning of heavy metals in sediments of the Damodar River a tributary of the lower Ganga, India. Environmental Geology. 39: Singh, K., S.O. Kelly, and M.K.S. Sastry Municipal solid waste to energy: An economic and environmental assessment for application in Trinidad and Tobago Journal of the Association of Professional Engineers of Trinidad and Tobago. 38: SMEWW Standard Methods for the Examination of Water and Wastewater, 20e. American Public Health Association, Washington DC, USA. Surujdeo-Maharaj, S Analysis of water quality and socio-economic data for the Heights of Guanapo and La Retreat Areas of the Guanapo catchment. Water Resources Authority, Port of Spain, Trinidad and Tobago. Zahra, A., M. Zaffar Hashmi, R.Naseem Malik, Z. Ahmed Enrichment and geo-accumulation of heavy metals and risk assessment of sediments of the Kurang Nallah feeding tributary of the Rawal Lake Reservoir, Pakistan. Science of the Total Environment : Author contact information and affiliations Denise M. Beckles, Department of Chemistry, Faculty of Science and Technology, The University of the West Indies, St. Augustine, Trinidad & Tobago Denise.Beckles@sta.uwi.edu Grace-Anne Bent, Department of Chemistry, Faculty of Science and Technology, The University of the West Indies, St. Augustine, Trinidad & Tobago Grace-Anne.Bent@sta.uwi.edu Leonette Cox, Department of Chemistry, Faculty of Science and Technology, The University of the West Indies, St. Augustine, Trinidad & Tobago Leonette.Cox@sta.uwi.edu

10 Sharda Mahabir, The Water Resources Agency, Eastern Main Road, Barataria, Trinidad & Tobago Vincent Cooper, Department of Civil & Environmental Engineering, Faculty of Engineering, The University of the West Indies, St. Augustine, Trinidad & Tobago Gideon Ramtahal, Cocoa Research Centre, Faculty of Food and Agriculture, The University of the West Indies, St. Augustine, Trinidad and Tobago Maria Allong, The Solid Waste Management Company Limited of Trinidad and Tobago, 34 Independence Square, Port of Spain, Trinidad & Tobago

Concentration of Metals (Cd, Hg, Ag; mean +SD) in sediment samples collected from Pit Specific Sediment Chemistry Monitoring for CMP 1 in May 2014.

Concentration of Metals (Cd, Hg, Ag; mean +SD) in sediment samples collected from Pit Specific Sediment Chemistry Monitoring for CMP 1 in May 2014. Figure 1: Concentration of Metals (Cr, Cu, Ni, Pb, Zn, As; mean +SD) in sediment samples collected from Pit Specific Sediment Chemistry Monitoring for CMP 1 in May 2014. Figure 2: Concentration of Metals