Bagacay_Abandoned_Mine_ Samar


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There are seven identified prioritized abandoned mine sites: Philippine Pyrite Corporation - Bagacay, Hinabangan, Western Samar; Basay Mining Corporation - Brgy. Maglinao, Basay, Negros Oriental, Thanksgiving Mine, Benguet Exploration Inc. - Camp 6, Kennon Road, Tuba, Benguet, Black Mountain Inc. - Tuba, Benguet, Consolidated Mines, Inc. - Ino & Capayang, Mogpog, Marinduque, Palawan Quicksilver Mines - Tagburos, Puerto Princesa, Palawan, Western Minolco Corp. - Atok, Benguet The Bagacay Mine in Western Samar ranks first for remediation. The Bagacay site, which was formerly worked for the recovery of pyrite/copper, is located at the border of a nature reserve. It exhibits many environmental problems, including the formation of Acid Mine Drainage (AMD) and the related spread to nature of potential toxic metals. MGB has conducted a preliminary investigation into the environmental impacts at Bagacay Mine and developed some initial rehabilitation plans including some revegetation trials. These plans are insufficient for final closure and rehabilitation but can be identified as interim remediation measures...

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Bagacay_Abandoned_Mine_ Samar

  1. 1. Dr. Antonio M. Daño, A. Exconde, V. Manalo and R. Amante ERDB, College, LagunaECOSYSTEMS RESEARCH AND DEVELOPMENT BUREAUDepartment of Environment and Natural ResourcesCollege, Los Baños, Laguna 4031 Philippines. 536-2269/2229 local 256. Fax no. 536-2850. 1
  2. 2. Introduction IMPORTANCE OF MINING  Contributes to the economic development of a number of industrialized countries which in many ways based their development on their natural resources.  Sustains and enhances economic growth in developing countries with knowledge and improvements in exploration and extraction techniques and have appropriate institutional and regulatory framework. 2
  3. 3. Introduction MINING IN THE PHILIPPINES  In the Philippines, almost all of the mines are located in remote areas, proponents have to invest in infrastructure and build self-contained towns, benefiting not just the mining community but also the neighboring villages.  Mining built Baguio into one of the country’s premier cities. 3
  4. 4. Toledo, Cebu, PhilippinesThe once sleepy town of Toledo, Cebu became a chartered city with the operationsof Atlas Consolidated which was replicated in other large-scale mining areas. 4
  5. 5. Introduction MINING IN THE PHILIPPINES Mining Act of 1995  paved the way for the formulation of guidelines on mine rehabilitation.  Final Mine Rehabilitation and Decommissioning Plan which provides a guarantee for clean-up after mine operation and abandonment is now required of new applicants. 5
  6. 6. Introduction  DENR identified rehabilitation and remediation of abandoned mines as one of the priorities for the National Program Support - Environment and Natural Resources Management Project. - Exclusively deals with abandoned mines where responsible entity can no longer be found and where Government will take the responsibility for its environmental issues and concerns 6
  7. 7. Introduction  Bagacay Mines in Western Samar ranks first for remediation out of the seven priority abandoned mine sites identified by the Mines and Geosciences Bureau (MGB).  Environmental problems in Bagacay Mines: - Formation of Acid Mine Drainage (AMD) - Pollutants from the mining site were blamed for the death of Taft River. 7
  8. 8. Bagacay Mines, Samar, PhilippinesThe Bagacay site, which was formerly worked for the recovery of 8pyrite/copper, exhibits many environmental problems
  9. 9. Introduction To a considerable extent, management of surface runoff and drainage determines the success or failure of a mining or any land reclamation project. Reclaimed overburden tends to allow little infiltration because of compaction during reclamation, subsidence, and the accelerated weathering. To implement appropriate rehabilitation strategies, understanding the condition of the area particularly the hydrology is deemed necessary. 9
  10. 10. Objectives This study aims to assess the hydrologic behavior of sub-watersheds affected by mining operation in Bagacay Mining area. Specifically, the study aims to: 1. Determine the watershed characteristics of areas affected by mining operation; 2. To quantify streamflow volume and relative contribution of affected sub-watersheds; and 3. To determine water quality status of affected water channels. 4. To determine pollution load of affected water channels. 10
  11. 11. Methodology1. Establishment of Monitoring Devices  Installation of monitoring devices (staff gages, raingages, and other monitoring gadgets).  Production of thematic maps of Bagacay sub- watershed2. Conduct of monitoring and assessment activities  Actual monitoring and assessment on hydrologic behavior of the sub-watershed 11
  12. 12. Methodology  Streamflow and water quality were regularly monitored at established water gauging station using staff gage and float method.  Characterized and quantified geo-morphological features of the micro-watershed based on availa ble maps, aerial photos and actual surveys including field verification.  Cross sectioning and stream profiling in the hydrological stations 12
  13. 13. Methodology 3. Streamflow and Water Quality of Micro-watershed  Water samples and riverbed materials from monitored sub-watersheds were taken at different times for six months (to cover rainy day and dry season). Water quality parameters considered include temperature, pH, dissolved oxygen and heavy metals (iron, copper, cadmium, lead and zinc).  Water samples including sand materials at the riverbed were brought to Leyte State University, Baybay, Leyte laboratory for analysis. 13
  14. 14. Results3.1 Area Description From 1956 – 1985, Marinduque Mining and Industrial Corp. (MMIC), who previously owns the property, operated the mine primarily for copper minerals In 1986, Philippine Pyrite Corporation (PPC), a subsidiary of PHILPHOS, operated the mine till 1992 for pyrite concentrates PPC ceased operation in 1992 due to the rising operational cost of recovery and aggravated by labour dispute. 14
  15. 15. Results3.1 Area Description  Both Bagacay Mine and PPC utilized open pit mining method where the ore is mined by drilling, blasting, loading and hauling  Report of the MGB Region 8 estimated the total mine affected area to be approximately 137.5 has. This includes the mine pit, tailings ponds (8), waste dumps, access roads and other industrial areas. 15
  16. 16. Bagacay Mines, Samar, Philippines No mine rehabilitation and maintenance works in the miningarea in general have been undertaken. Revegetation of affected areaswere initiated by MGB through various contractors but the survival is 16
  17. 17. Site Description Figure 1 – Map showing the location of Bagacay Mine in Hinabangan, Western 17Samar relative to Taft Watershed.
  18. 18. Taft Watershed Total area -55,785.3 has. Basin perimeter - 146.2 km Basin length - 46 km Basin width - 9.06 km Total length of streams 181.43 km  Ave. annual temperature 27.76°C Ave. annual relative humidity - 27.76°C 18
  19. 19. Taft WatershedTaft Watershed Characteristics Karst region with sinkholes and underground channels Parent materials are generally metamorphic Limestones abound in the area. Soil is calcareous in elevated and mountainous areas In the lowlands, soil is mostly acidic exhibiting clayish texture 19
  20. 20. Results Soil Analysis in Bagacay Mined-Out Area  Chemical characteristics of the soils, showed that almost all soil samples have ultra acid to extremely acid pH of as low as .  Areas with higher pH were mostly vegetated indicating the importance of soil pH in establishing vegetation in the abandoned area. 20
  21. 21. Results All soil samples were noted to have above average total Cu content, with four (4) sites above the maximum permissible metal concentration. The highest value recorded was 6202.88 me/kg Cu. 21
  22. 22. Results  Nearly 80% of the total land area of Taft Watershed was covered with forests of which 15,289 hectares were closed canopy forest while 17,993 hectares are open canopy forest  Cultivated areas and croplands that are mostly planted to coconut accounted for about 17% of its total land area. 22
  23. 23. Results Characteristics of Affected Channels 1. Area and Topography A.Guila-guila creek  Largest of the three affected tributaries  Guila-guila creek drains most of the water coming from the open pit and tailings pond 1, 4 and 8 B. Creek B  Has the least drainage area  Drains most of the water coming from the tailings pond 2, 3, 5, 6, 7 and waste dump 2 23
  24. 24. Results Table 1. Drainage areas of creeks draining mining affected areas. Creeks Area (has) Creek A 136 Guila-guila creek 166 Creek B 115 Total 417 24
  25. 25.  LAND USE. Most of the areas covered by the mining concession is covered by second growth forest The peripheries of three (3) small sub-catchments affected by the mining operation were also covered by brush and secondary forest.25
  26. 26. ResultsSecondary forest and Brushland  Among the most common species observed in the area include: a. Talahib (Saccharum spontaneum) b. Malatungaw (Melastoma malabathricum) c. Runo grass (Miscanthus sp.) d. Hambabalud (Neonauclea formicaria) e. Datiles (Mutingia calabura) f. Ipil-ipil (Leucaena leucocephala) g. Hindang (Myrica javanica) 27
  27. 27. Figure 2. Sub-watersheds affected by mining surface working areas. 28
  28. 28. Results Open Pit  There are four abandoned open pits or surface working sites in Bagacay Mine, estimated at more than 18 hectares, excluding the affected adjacent areas (i.e. mine roads and others).  The main pit is estimated at 15 hectares and almost without vegetation.  Benches are still visible in some parts while in others, they are covered by collapsed pit walls and bench materials. 29
  29. 29. Open Pit Upstream of the main pit is the headwater of Guila- guila Creek which almost traverse from North to South. Guila-guila creek at the lower part of the open pit. 30
  30. 30. Bagacay Mines Figure 3. Open pit area in Bagacay Mines. 31
  31. 31. Results  Bagacay Mine has three waste dumps , all almost devoid of vegetation and contains pyritic materials with an estimated total area of 12 has. Ave. Area Slope Volume WD Location Thickness (has) * (m) (m) (m3) 1 E of main pit 4 8 30 331,835 2 SE of mill plant 5 10 40 533,493 3 NW of main pit 2 8 30 182,027 32
  32. 32. ResultsWaste Dumps A. WD 1 Drainage Water and seepages are found draining along gullies that flows towards downstream Guila – guila Creek before draining to Taft River. B. WD 2 Drainage  has no significant drainage canals and its water / seepage are drained through gullies that join to a small creek (A) that flows towards Taft River. C. WD 3 Drainage contains gullies which drain its water/ seepages to the main pit before flowing to Taft River. 33
  33. 33. Tailings Pond  There are eight (8) Tailings Pond (TP) in the area and is estimated to be about 11.0 hectares Dam Embankment Area Tails Vol.TP. No. Location Length Height (has.) (m3) Slope (0) (m) (m) SW of the mill 0.15 4,390 22 3 30 1 plant NE of the mill 4 335,341 782 8 352,3,5,6 plant NW of the mill 2 133,029 107 6 35 4 plant NE of the mill 2.5 127,540 172 5 35 7 plant and below TP 2,3,5 and 6 W of the mill 2 101,935 145 6 30 8 plant and above TP 1 34
  34. 34. 35Figure 5. Tailings pond 8 as viewed from the boundary of the open pit.
  35. 35. Results Others  Remnants of the other structures (motor pool, power plant and other buildings) were still visible. The structures were cannibalized for the remaining scrap iron. These areas are also unvegetated due to the scattered acidic materials.  The water/seepages in these areas are drained through small gullies that flow towards Guila-guila Creek. 36
  36. 36. 3.3 Rainfall Pattern 3,900 mm annual rainfall of Borongan, Eastern Samar  2,914 mm annual rainfall of Catbalogan, Western, Samar  Bagacay area is estimated to have an annual rainfall of about 3,400 mm. 37
  37. 37. Results Rainfall Pattern in the Area 38
  38. 38. Results 3.4 Streamflow The nearest gauged river in the area is the Tenane River which is located beside the Taft River.  Tenane River has a drainage area of 39,200 hectares while Taft River has an area of 55,800 hectares.  The two watersheds have a comparable geology, topography, land use and climate.  The streamflow pattern behaves similarly to the rainfall pattern in the area. 39
  39. 39. Results Streamflow Discharge (m3/sec) of Taft Watershed 3.4 Streamflow 70 60  December 50 Highest streamflow m3/sec. 40 Q1 30 Q2  April - lowest flow 20 10 0 MonthStreamflow discharge of Taft watershed at the mouth (Q1) anddownstream of confluence of Taft River and Guila-gila creek. 40
  40. 40. Table 4. Observed streamflow (m3/sec) from the 3 affected creeks asmonitored by ERDB-DENR. Date Guila-guila Creek A Creek B TOTAL December 0.327 0.268 0.227 0.822 January 0.249 0.204 0.121 0.575 February 0.175 0.143 0.121 0.439 March 0.076 0.062 0.052 0.190 April 0.136 0.083 0.066 0.286 May 0.097 0.079 0.067 0.243 June 0.138 0.113 0.095 0.346 July 0.135 0.118 0.103 0.356 41
  41. 41. Figure. Observed total streamflow (m3/sec) from the 3 affected creeks and % contribution to Taft River as monitored by ERDB-DENR. 3.5 3 2.5Streamflow (m3/sec) 2 streamflow (m3/sec) Streamflow (%) 1.5 1 0.5 0 Jan Jun Jul Mar Apr Feb Dec May Month 42
  42. 42. Guila-guila Creek, Bagacay Mines 3.4 Streamflow  No data exist on the streamflow behavior of the three (3) creeks draining the mined out areas.  Table shows the observed streamflow (m3/sec) of creeks draining the mined-out areas as monitored by ERDB-DENR.  Data show that creeks draining the mined-out area contributed about 2% of the mean flow of Taft River. Data show that creeks draining the mined-out area contributed about 2% of the mean flow of Taft River. 43
  43. 43. Results 3.5 Water Quality  Water quality from the affected creeks showed that at the mouth of Gila-gila creeks, the pH level ranged from 3.01 (December) to 1.91 (March). Level of water pH in other sampling points also showed lower pH level.  This indicates that water flowing in the said channels are still very acidic and toxic to living creatures. About 2 kilometers downstream at Barangay Binaloan the pH level were found to be within the limit of Class C water with pH level varying from 7.6 to 6.9. 44
  44. 44. 16Results 14 12Concentration (mg/L) 10 pH Fe 8 Cu 6 Cd Pb 4 Zn 2 0 3-Dec-09 22-Jan-10 13-Mar-10 2-May-10 21-Jun-10 10-Aug-10  pH and Heavy metal Sampling date concentration of Guila- 9 guila creek (upper) and Taft River at Barangy 8 7 Binaluan (lower). Concentration (mg/L) 6 pH 5 Fe 4 Cu Cd 3 Pb 2 Zn 1 0 16-Dec-09 16-Jan-10 16-Feb-1016-Mar-10 16-Apr-10 16-May-10 16-Jun-10 Sampling date 45
  45. 45. ResultsTable. Water Quality criteria for toxic substances in freshwater. Parameter Limit Cadmium (mg/L) 0.01 Lead (mg/L) 0.05 Copper (mg/L) 0.05 Iron (mg/L) 0.02 Zinc (mg/L) 0.01 46
  46. 46. Table. Riverbed soil analysis in various points of tributaries. Parameters Guila-guila Binaloan Creek B Convergence creek (Taft with Taft River) River pH 2.605 7.46 2.415 2.325 Fe (%) 5.13 4.99 4.85 4.81 Cu (mg/kg) 1490.0 2670.0 1617.5 1952.5 Cd (mg/kg) 14.85 14.68 12.4 13.95 Pb (mg/kg) 276.45 237.95 192.75 394.65 Zn (mg/kg) 512.5 630.44 553.69 606.5Riverbed materials which are potential source of pollutants when mixedwith flowing water were also found to be highly acidic having pH ofabout 2.5. Levels of toxic chemical like iron, copper, cadmium, lead, andzinc are also high as shown in the table. 47
  47. 47. Pollution Load 600 500 Pollution load (kg/day) 400 Fe Cu 300 Cd Pb Zc 200 100 0 12/16/09 12/30/09 1/13/10 1/27/10 2/10/10 2/24/10 3/10/10 3/24/10 4/7/10 4/21/10 5/5/10 5/19/10 6/2/10 6/16/10 6/30/10 Sampling Date Iron and copper were the dominant heavy metals found in flowing water from the affected creeks 48
  48. 48. Guila-guila Creek, Bagacay Mines 49The team measuring the site selected for installing hydrologic instruments.
  49. 49. Guila-guila Creek, Bagacay MinesThe team conducting infiltration measurement . Inset: infiltrometer 50
  50. 50. Conclusion and Recommendations The mined-out areas covers about 1 percent of Taft River watershed but contributes about 2 percent of the streamflow of the river system. Affected creeks are still polluted but main river shows signs of recovery. It is recommended that A) limestone checkdams be constructed in the affected creeks to neutralized the acidity of flowing water as well as trapped the heavy metal contaminated sediments in the bottom of the creeks and prevents it from being transported to Taft River; b) Monitor change in pollution load with the improvement of vegetation; c) Insure the stability of waste dump areas in all mining sites. 51
  51. 51. Thank you 52