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...
1. Dr. Antonio M. Daño, A. Exconde, V. Manalo and R. Amante
ERDB, College, Laguna
ECOSYSTEMS RESEARCH AND DEVELOPMENT BUREAU
Department of Environment and Natural Resources
College, Los Baños, Laguna 4031 Philippines. 536-2269/2229 local 256. Fax no. 536-2850. erdb@denr.gov.ph
1
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. 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. Toledo, Cebu, Philippines
The once sleepy town of Toledo, Cebu became a chartered city with the operations
of Atlas Consolidated which was replicated in other large-scale mining areas.
4
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. 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. 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. Bagacay Mines, Samar, Philippines
The Bagacay site, which was formerly worked for the recovery of 8
pyrite/copper, exhibits many environmental problems
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. 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. Methodology
1. Establishment of Monitoring Devices
Installation of monitoring devices (staff gages,
raingages, and other monitoring gadgets).
Production of thematic maps of Bagacay sub-
watershed
2. Conduct of monitoring and assessment activities
Actual monitoring and assessment on hydrologic
behavior of the sub-watershed
11
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. 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. Results
3.1 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. Results
3.1 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. Bagacay Mines, Samar, Philippines
No mine rehabilitation and maintenance works in the mining
area in general have been undertaken. Revegetation of affected areas
were initiated by MGB through various contractors but the survival is
16
17. Site Description
Figure 1 – Map showing the location of Bagacay Mine in Hinabangan, Western
17
Samar relative to Taft Watershed.
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. Taft Watershed
Taft 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. 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. 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. 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. 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. 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. 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.
27. Results
Secondary 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
29. 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
30. 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
31. Bagacay Mines
Figure 3. Open pit area in Bagacay Mines. 31
32. 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
33. Results
Waste 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
34. 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 35
2,3,5,6
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
36. 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
37. 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
39. 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
40. 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
Month
Streamflow discharge of Taft watershed at the mouth (Q1) and
downstream of confluence of Taft River and Guila-gila creek.
40
41. Table 4. Observed streamflow (m3/sec) from the 3 affected creeks as
monitored 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
42. Figure. Observed total streamflow (m3/sec) from the 3 affected creeks
and % contribution to Taft River as monitored by ERDB-DENR.
3.5
3
2.5
Streamflow (m3/sec)
2
streamflow (m3/sec)
Streamflow (%)
1.5
1
0.5
0
Jan
Jun
Jul
Mar
Apr
Feb
Dec
May
Month 42
43. 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
44. 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
45. 16
Results
14
12
Concentration (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
46. Results
Table. 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
47. 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) 512.5 630.44 553.69 606.5
Riverbed materials which are potential source of pollutants when mixed
with flowing water were also found to be highly acidic having pH of
about 2.5. Levels of toxic chemical like iron, copper, cadmium, lead, and
zinc are also high as shown in the table. 47
48. 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
49. Guila-guila Creek, Bagacay Mines
49
The team measuring the site selected for installing hydrologic instruments.
51. 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