Bordo Poniente: Large Steps toward Cleaning Mexico City

Mexico City generates approximately 10,000 tonnes of solid waste per day and half of this amount ends up in landfills. The remaining volume goes through recycling programs, with 1,023 tonnes being used for waste-to- energy purposes while 507 tonnes are used as compost. Bordo Poniente was opened in 1985 and over time became the sole sanitary landfill of Mexico City. 25 years later, it had become the largest landfill in Latin America and the city’s main environmental liability. Bordo Poniente contained 70 million tonnes of solid waste that reached a height of 25 meters and housed 1.5 million tonnes of methane gas trying to reach the surface.

In November 2010, the government of Mexico City signed an agreement with federal authorities to stop operations at the landfill. In the agreement, it was settled that the local government would conduct the closure in compliance with appropriate technical standards. The initiative started back in 2007 during a C40 Cities Climate Leadership Group meeting where former Mexico City mayor Marcelo Ebrard and other leaders identified Bordo Poniente as one of the biggest sources of greenhouse gas emissions in the city. Even the Clinton Climate Initiative opened offices in Mexico City in order to support the local government’s efforts to find a solution to the problem. Shutting down Bordo Poniente seemed like a great idea, as it would prevent 1.8 million tonnes of carbon dioxide from being released into the atmosphere annually, or around 26% of the city’s greenhouse emissions. Although the closure of Bordo Poniente is regarded by many as Marcelo Ebrard’s most assertive action against climate change, its subsequent management sparked some controversy. Months after the closing of the landfill, people became curious as to why nothing was being done to recover the 374 hectares of federal land. Although the closure did prevent further accumulation of solid waste, it did not spark off actions to manage the hazardous materials and restore the land. The garbage was not covered to avoid unpleasant odors and the compost plant continued for months receiving 2,000 tonnes of waste each day. These were stored in an open space without the required industrial handling, rotting in the open and attracting all kind of pests.

Currently, the landfill presents several bodies of leachate that boil when combined with methane gas and carbon dioxide. This situation is particularly concerning during the rainy season when these toxic fluids are washed away and mix with clean water reservoirs. Furthermore, the plastic membrane that covers the landfill’s floor, intended to prevent leachate from permeating into the subsoil, is torn and leading to potential serious pollution of subterraneanwaterbeds. Both CONAGUA and SERMARNAT have issued warnings on the dangers that Bordo Poniente’s poor management poses to the inhabitants of Mexico City and the metropolitan area. Nevertheless, actions are being taken since the city was authorized to produce and use biogas from the landfill to recover some of the investments that its closure entails. In addition, this action forced the city to introduce garbage separation and recycling programs as well as waste-to-energy initiatives to reduce the need for more landfills. Mexico City also made an agreement with CEMEX, one of the largest producers of cement and building materials in the world, to supply 3,000 tonnes of solid waste inorganic fractions every day to use as fuel.

The Bordo Poniente biogas project was won by the BMLMX Power Company consortium, which was chosen because of its experience in closing landfills, infrastructure for capturing biogas, electricity production, and obtaining carbon credits. BMLMX Power Company, a consortium made up by Mexican and Spanish firms, will be in charge of definitely closing down the Bordo Poniente landfill and building a plant to capture biogas. The consortium will operate for 25 years, beginning in 2014 and ending in 2039, investing US$60 million into this development. The Bordo Poniente project is planned to produce 58MW, enabling the Mexico City government to buy electricity for street lighting 10% below CFE prices, and saving the city US$22 million annually. The project will not require investment from public funds since it is contracted out, granting BMLMX Power Company the rights to exploit the biogas that comes from the 70 million tonnes of rubbish buried in Bordo Poniente. Part of this initiative is aimed at reducing public expenditure because proper waste management will translate in lowering waste management costs and it goes hand in hand with the current local administration’s plan of implementing mechanisms to avoid accumulating waste in landfills.

The CEMEX initiative and the biogas plant are alternatives but do pose a small but significant challenge to Mexico City’s inhabitants and government: garbage has to be separated and disposed properly. Once the recyclable materials have been separated, remaining materials are processed through a mechanical separator that divides organic from inorganic waste. The latter is used for biogas generation and compost production while the inorganic waste is sent to be processed as alternative fuel for CEMEX.

On June 2013, the Mexico City government submitted the executive project to finally close down the Bordo Poniente and have SEMARNAT assess environmental impacts before beginning biogas extraction in 2014.