LANDFILL MANAGEMENT IMPROVEMENT IN MEXICO CITY: GROUND SUBSIDENCE MONITORING AND LEACHATE MANAGEMENT = LANDFILL MANAGEMENT IMPROVEMENT IN MEXICO CITY: GROUND SUBSIDENCE MONITORING AND LEACHATE MANAGEMENT

다국어 초록 (Multilingual Abstract)

Bordo Poniente Etapa-IV (BP-IV), the landfill for the Mexico City in the United Mexican States, is located on the widely flat Exlago Texcoco area, where an underground aquifer is highly saline and not suited for drinking purposes. Which has a comparative advantage than any other locations that stands on a potable aquifer.
Meanwhile BP-TV stands on very soft, highly compressible, clayey layers of about 60 meters thickness. It implies that if landfill is embanked in a thick layer in one operation in a short period, landslide and/or slope failure will easily take place. Therefore, thinner landfilling operation and time passage for stable ground subsidence and consolidation are principally required in order to maintain safe operation of solid waste landfill on such a soft and compressible ground.
Although BP-IV employs the bottom impermeable liner (single high-density-polyethylene 1.0 nun thick sheet), it had not employed leachate collection and treatment system; leachate had sometimes been seeping out at cells’ slope foot on to the surrounding road.
In view of the situation, monitoring activities and ad- hoc improvement works are being implemented e.g.: ground subsidence monitoring in relation with landfill thickness with time passage; landfill gas and leachate quality monitoring with re-circulation experiment; and leachate collection and re-circulation system construction with appropriate technologies.
With objectives of verifying the landfill stability regarding landslide and/or slope failure and pursuing maximum possible landfill capacity of the site, ground subsidence monitoring is being carried out.
For the following purposes, leachate collection and recirculation is being implemented.
ㆍ To improve anaerobic conditions of wastes landfilled by leachate re-circulation;
ㆍ To accelerate decomposition of organic pollution loads by leachate re-circulation;
ㆍ To construct leachate collection and re-circulation system at low costs; and
ㆍ To pump up the leachate in order to lower its head in the landfill cells especially where slope failure risks exist.
These experiences are introduced and discussions are developed in line with the findings of these activities.