Fires, combustible and poisonous gases, and offensive odors are again pointed out as the risks and nuisances associated with the George Town landfill in the latest of a series of reports about dump sites in the Cayman Islands.
The report, by U.K. consultants Amec Foster Wheeler, is based on data collected from monitoring and surveying in April 2014. The report is dated Aug. 3, but it was not made public until Aug. 28.
The report presents a risk assessment of contaminants and other hazards associated with the landfills in Grand Cayman, Cayman Brac and Little Cayman, and includes recommendations for environmental improvements and monitoring.
In George Town, stockpiled tires, a particular fire hazard, need to be removed, according to the report.
In the past two years, there have been five fires at the landfill. In March of this year, a blaze started in a large pile of residential waste near a big pile of discarded tires.
In addition to the 62,000 tons of municipal and commercial waste the landfill receives per year, it also receives 16,000 tons of materials such as scrap metals, tires and waste oils.
“There are significant stockpiles of metals and tires representing a number of years’ accumulation,” the report stated.
MLA Roy McTaggart told the Cayman Compass on Sunday that he believes a bidder to remove the tires from the landfill has been identified, although he does not know whether a contract has been awarded or concluded.
“We know we need to get rid of those tires and find a solution,” Mr. McTaggart said.
The assessment also states that the landfill needs to begin daily capping – covering landfill waste with layers designed to isolate and stop the spread of contaminants. The report notes that the landfill has only a thin soil cover on one flank.
The report also recommends:
- Monitoring the groundwater well at least on an annual basis
- Monitoring the North Canal every six months to assess surface water contamination
- The Department of the Environment should reinstate annual sampling in North Sound to monitor marine water contamination.
The consultants’ environmental investigation in George Town monitored existing and new groundwater wells, surface water and sediment sampling in canals and dykes surround the site and in North Sound, and dust and landfill gas monitoring. Additionally, samples of vegetation surrounding the landfill and from North Sound were analyzed. Finally, historical data for groundwater and surface waters was considered.
At the Cayman Brac landfill, groundwater boreholes were installed and sampled, surface waters were sampled, and landfill gas was also monitored and sampled. At the Little Cayman landfill, where waste is burned, some soil and surface water sampling was conducted. The report found no significant pre-existing environmental data for the Sister Island landfills.
The report on the George Town landfill describes the varying degree of risks for site visitors, adjacent residents and commercial users, and water.
The report summarizes its risk assessment outcomes for the George Town landfill as follows:
- Site workers and visitors: Moderate risks from arsenic in soils, hydrogen sulphide, other landfill gas trace components and methane. Moderate to low risk from hydrocarbons from waste storage area, assuming appropriate PPE (personal protective equipment) is worn
- Adjacent residents (Lakeside Apartments or Parkside Close): Moderate to low risk from landfill gas trace components and from methane (as a potentially explosive gas). Low risk from arsenic in soils. Medium potential dust nuisance. High odor nuisance. Medium risk associated with animals, pests, and contaminated waters used for recreational purposes. High risk for nuisances from landfill fires
- Adjacent commercial/industrial users: moderate to low risks from landfill gas trace components and methane. Moderate risks from landfill gas trace components from contaminated sediments. Low risks from arsenic in soils
- Groundwater: moderate risks from hydrocarbons (due to spill and overtopping of bunds). Low risks for ammonia. Negligible risk for arsenic
- Surface water canals: High risks from hydrocarbons. Moderate risks from ammonia and orthophosphate. Moderate to low risk from iron
- North Sound: High risk from ammonia in canal water. Moderate to low risks from ammonia. Moderate risks from metals.
A summary of the risk assessment for Cayman Brac is as follows:
- Site workers and visitors: Moderate to low risks from landfill gas trace components. Moderate risks from methane. Low risks from hydrocarbons from the waste oil storage spills (provided PPE is worn). Medium risk from clinical waste disposed in the uncovered pit within the landfill
- Adjacent residents: low risks from landfill gas trace components. Moderate to low risks from methane. Medium nuisance from potential dust and odor. Medium risk from nuisance associated with landfill fires. Medium risks from insects. Low risk from scavenging animals and birds
- Groundwater: Moderate risks from hydrocarbons. Moderate to low risks from ammonia
- Shrimp pond: Moderate risks from metals leached from the landfill. Potentially elevated nutrients and iron from run-off and groundwater have an assessed medium impact on pond water quality
- Ocean: Medium risk to water quality from potentially elevated nutrients and iron in groundwater base flow.
Little Cayman landfill risk assessment outcomes:
- Site workers and visitors: Moderate to low risks from combustion products and metals in soils. Low risk from hydrocarbons in soils
- Adjacent residents: Nuisance from potential dust and odor is assessed as low. Low risks from animals or birds. Medium risk from insects. Medium risk from nuisance from landfill fires
- Groundwater and offsite pools: Moderate risks from hydrocarbons. Moderate to low risks from metals. Low risks from ammonia. Moderate to low risks to offsite pools from metals. Medium risk to offsite pools associated with elevated nutrients, iron and solids
- Booby pond: Medium risks from air transport of smoke and combustion products.
This report comprises “Task 2” of the first phase of the National Solid Waste Management Strategy for the Cayman Islands. “Task 1” was a review of existing environmental information and an initial risk assessment done in February 2015.