Paper No. 134-4
Presentation Time: 8:50 AM
PILOTING RISK MITIGATION AT A LEAD CONTAMINATED SITE IN BANGLADESH
Bangladesh has a widespread issue of lead (Pb) contamination in soil associated with the informal recycling of Used Lead Acid Batteries (ULABs). Pure Earth’s Toxic Site Investigation Program has already identified about 300 such lead contaminated sites from active and legacy ULAB recycling operations. Lead is released into the environment as dust and acid during battery breaking and atmospheric deposition during smelting of lead plates. There are limited options to address toxic sites in Bangladesh, so Pure Earth and its partners piloted a risk mitigation project at two abandoned informal ULAB recycling sites situated in Kathgora village in the Dhaka district. X-ray Fluorescence (XRF) mapping revealed high concentrations of lead in surficial (1 to 2 cm) soil in the broader impacted area covering a total of about 4 hectares, with Pb concentrations generally ranging up to the 5,000 to 10,000 ppm. Pb concentrations ranged up to almost 120,000 ppm (12%) in recycling. Children were exposed to the Pb predominantly by playing in and around waste piles, and hand-to-mouth behavior of contaminated soil and dust. The mean blood Pb levels measured in 69 children living in the area was 19.1 ug/dL, with a maximum of 47.5 ug/dL.
The area is geologically characterized by about 10 m thick top clay layer of Pleistocene age which was well suited for burying the lead impacted soils onsite. Soil exceeding 400 ppm over the 4 hectare area was scraped by hand from the impacted area including from residential yards. Roughly 400 m3 of lead impacted soil was buried in a containment structure approximately 2 m below ground surface and capped with a geotextile to mitigate disturbance. Unimpacted soil excavated from the containment structure was used to cap the contaminated soil and was spread across the scraped areas. Post cleanup XRF mapping showed Pb levels were well below the 400 ppm. The risk mitigation project included community education and house cleaning. Blood lead levels among children in the area showed significant declines in BLLs, with a 20% reduction within 7 months and a 35% reduction after 14 months. The pilot remediation project was the first of its kind in Bangladesh, and has brought significant environmental and public health impacts in the area, and can be replicated at other ULAB recycling sites.