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Friday, March 10, 2006
Pena: Closure of all open, controlled dumpsites
By Rox Pena
REPUBLIC Act (RA) 9003, the Ecological Solid Waste Management Act of 2000, forced the closure of all open dumps or their conversion to controlled dumps last Feb. 16, 2004. The conversion was meant as a stopgap measure because controlled dumps should also be closed by Feb. 16, 2006. By now, the only legally acceptable disposal sites for residual waste are sanitary landfills like the facility of Metro Clark Waste Management in Kalangitan, Capas, Tarlac.
Recently, the Department of Environment and Natural Resources (DENR) issued an administrative order, giving the guidelines for the closure of all open and controlled dumpsites. The order instructs the Environmental Management Bureau (EMB), as well as the Provincial and Community Environment and Natural Resources Officers (Cenro/Penro) to assist local government units (LGUs) in preparing a closure plan.
For the benefit of LGUs, herewith are the important provisions of the administrative order:
* The LGU should conduct a pre-closure assessment. The aspects, which will be covered by the assessment, will include dumpsite history, location, access, area, lot owner, terrain, surrounding land use, surrounding surface features, nearby human receptors, hydro geologic setting, wells, springs and surface water bodies near site, daily waste volume, waste pile dimensions and volume, extent of exposed waste, period of operation, slope, drainage if any, evidence of contamination, presence of squatters and waste pickers, reports or evidence of spontaneous combustion, reported dumping of hazardous wastes and number and types vehicles which bring in waste.
* Following the site assessment, a closure plan shall be prepared by the municipality or city for its open dump and controlled dump facility. Depending on the actual conditions, this guideline should help minimize risk of aquifer contamination, which is a direct threat to health and environment.
* Site clearing-storage areas for recyclables, makeshift huts and other structures within the boundaries of the disposal facility should be removed. Given the existence of informal dwellers or waste pickers, the closure plan should include where possible and affordable a basic resettlement plan which will also provide alternative source of income to waste pickers and their families.
* Site Grading and Stabilization of Critical Slopes - The most critical aspect of the closure plan is the organization of the usually unstable slope within the site. The closure plan shall make provisions for the identification of areas within the dumpsites with potential instability.
The slope profile shall be re-structured with sustained filling to further reduce the overall stability or until the top and side grades have been attained. The exposed waste should be compacted and the site graded to slopes ranging from two to four percent to facilitate drainage and prevent local ponding. This grade will prevent ponding and promote natural drainage. Side slopes can be generally set at the ratio of one vertical to three horizontal or gentler depending in the nature of waste and actual site conditions.
* Application and Maintenance of Soil Cover - The graded site should be covered with soil, inert or stable material or clay material to prevent entry or water into the waste pile and access by vectors. The final cover should be at least 60 centimeters, which include a 15-cm topsoil and a 45-cm compacted soil. The topsoil, which is usually not compacted, will serve as protection layer for the compacted soil cover, as well as support plant growth. It will act a barrier, which will reduce entry of water into the waste pile, minimize gas migration if any, prevent animals from getting into the underlying waste, minimize the emission of odors and support vegetation growth Provision of Drainage Control System-Peripheral canals or ditches should be constructed around the site to divert runoff. The intention is to prevent contact of the waste pile with water thereby reducing the potential for leachate generation.
* Leachate Management - The pre-closure assessment should determine the points of exit of the leachate from the waste pile from which a canal or ditch can be built to facilitate collection. The contaminated liquid must not be allowed to drain into streams or natural bodies of water.
Natural attenuation maybe resorted to for small quantities leachate. For small dumps, the collected leachate may then be allowed to evaporate or sprayed back into the waste pile. Otherwise, the leachate must be treated.
* Gas Management - In the case of gas, vents made up of local materials such as bamboo or PVC pipes may be installed at selected points within the waste pile. As a general rule, vents may be spaced 50 meters apart. A more extensive leachate and gas management program will be developed and implemented depending on the results of the assessment.
* Fencing and Security - A fence shall be constructed around the dumpsite to prevent unauthorized entry of waste pickers, children and illegal settlers and stray animals. The extent of fencing shall be dictated by field condition. Natural materials such as shrubs or fast growing trees may be used particularly in rural areas. Regular visits by an LGU designated security can be undertaken to deter illegal dumping.
Only a few sanitary landfills are in existence as of this date. How would the DENR implement the closure of open and controlled dumpsites? This is the big challenge for DENR Secretary Angelo Reyes.
(March 10, 2006 issue)
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