QuestionsQuestions (DENR MEMORANDUM ORDER NO. 99-32, S. 1999)
DMO 99-32 was issued pursuant to Section 63 of Republic Act (RA) No. 7942 (Philippine Mining Act of 1995), Section 166 of DENR Administrative Order (DAO) No. 96-40, the Revised IRR of RA 7942, Presidential Decree (PD) No. 3931 (1976), the Pollution Control Law of the Philippines, and Section 19 of PD No. 1152 (Philippine Environmental Code).
It governs mine wastes and mill tailings management within the territory and the exclusive economic zone (EEZ) of the Republic of the Philippines.
It is the State policy that mine wastes and mill tailings produced by mining operators, permittees, and contractors shall be managed in a technically, financially, socially, culturally, and environmentally acceptable manner that effectively safeguards the environment and protects the rights of concerned communities.
Management must adhere to sustainable development: (1) guided by current best practices to control impacts and protect the environment; and (2) undertaken with due and equal emphasis on economic and environmental considerations, as well as safety, health, social and cultural concerns.
To effectively manage mine wastes and mill tailings in an environmentally sustainable manner, with environmentally acceptable health, safety, social, and cultural concerns.
Mine waste storage shall be located far from: old growth or virgin forest, proclaimed watershed forest reserves, wilderness areas, mangrove forests, mossy forests, national parks, greenbelts, game refuges, bird sanctuaries, and areas proclaimed as marine reserves/marine parks, and tourist zones.
A buffer of not less than 500 meters from the perimeter must be maintained (as defined by law) and for coastal areas, a buffer of not less than 500 meters from the mean low tide level along the coast must be maintained, with the facility above the maximum storm surge level.
Mine waste storage shall be designed and constructed above the maximum flood level. For drainage system design, a 50-year flood (return period) is used for minimum design purposes.
Storage siting must not be located on areas that might promote ARD generation. Design must establish ARD potential; mine waste characterized with ARD potential and/or classified as hazardous or with toxic leachates must be contained separately from materials with no or lower ARD potential. Runoff must be collected/contained and monitored and ARD generation must be avoided, or if generated, neutralized/treated before allowing to flow to water bodies.
Slopes of mine waste storage shall be maintained and managed below its angle of repose.
Seismic consideration shall not be less than 0.15 g under Operation Base Earthquake (OBE) and 0.25 g under Maximum Credible Earthquake (MCE).
At least 1.2 under static loading conditions and at least 0.98–1.2 under maximum probable earthquake loading conditions.
Materials used for embankment shall be non-acid and non-toxic leachates generating materials.
Direct and indirect disposal of mill tailings and mine waste into natural drainage systems (including rivers and tributaries) is prohibited, and flushing of tailings is also prohibited.
DSTP is allowed only when other tailings disposal and management options are not environmentally, socially, technically, and economically feasible or when DSTP shows the least environmental and social risk. It must also be within the carrying capacity of the receiving marine environment.