ECOSYSTEMS RESEARCH AND DEVELOPMENT BUREAU Department of Environment and Natural ResourcesCollege, Los Baños, Laguna 4031 Philippines. 536-2269/2229 local 256. Fax no. 536-2850. erdb@denr.gov.ph

Dr. Antonio M. Daño, A. Exconde, V. Manalo and R. AmanteERDB, College, Laguna

1

Introduction

Contributes to the economic development of anumber of industrialized countries which in manyways based their development on their naturalresources.

IMPORTANCE OF MINING

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

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

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

Introduction

Mining Act of 1995

paved the way for the formulation of guidelines onmine rehabilitation.

Final Mine Rehabilitation and DecommissioningPlan which provides a guarantee for clean-up aftermine operation and abandonment is now required ofnew applicants.

MINING IN THE PHILIPPINES

5

Introduction

DENR identified rehabilitation and remediation ofabandoned mines as one of the priorities for theNational Program Support - Environment and NaturalResources Management Project.

- Exclusively deals with abandoned mines whereresponsible entity can no longer be found and whereGovernment will take the responsibility for itsenvironmental issues and concerns

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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

Bagacay Mines, Samar, Philippines

The Bagacay site, which was formerly worked for the recovery of pyrite/copper, exhibits many environmental problems

8

Introduction To a considerable extent, management of surface

runoff and drainage determines the success orfailure of a mining or any land reclamation project.

Reclaimed overburden tends to allow littleinfiltration because of compaction duringreclamation, subsidence, and the acceleratedweathering.

To implement appropriate rehabilitationstrategies, understanding the condition of thearea particularly the hydrology is deemednecessary. 9

ObjectivesThis study aims to assess the hydrologic behavior of sub-watersheds affected by mining operation in BagacayMining 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.

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Methodology1. 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

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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 available maps, aerial photos and actual surveys including field verification.

Cross sectioning and stream profiling in the hydrological stations

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Methodology3. Streamflow and Water Quality of Micro-watershed

Water samples and riverbed materials from monitoredsub-watersheds were taken at different times for sixmonths (to cover rainy day and dry season). Waterquality parameters considered include temperature,pH, dissolved oxygen and heavy metals (iron, copper,cadmium, lead and zinc).

Water samples including sand materials at theriverbed were brought to Leyte State University,Baybay, Leyte laboratory for analysis.

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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

Results

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.

3.1 Area Description

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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 isalmost nil

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Site Description

Figure 1 – Map showing the location of Bagacay Mine in Hinabangan, WesternSamar relative to Taft Watershed.

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Taft WatershedTotal area -55,785.3 has.

Basin perimeter - 146.2 kmBasin length - 46 km Basin width - 9.06 kmTotal length of streams

181.43 km Ave. annual temperature

27.76°CAve. annual relative

humidity - 27.76°C

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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

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Results

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.

Soil Analysis in Bagacay Mined-Out Area

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Results All soil samples were

noted to have aboveaverage total Cu content,with four (4) sites abovethe maximum permissiblemetal concentration.

The highest valuerecorded was 6202.88me/kg Cu.

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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.

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ResultsCharacteristics 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

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Results

Creeks Area (has)

Creek A 136

Guila-guila creek 166

Creek B 115

Total 417

Table 1. Drainage areas of creeks draining mining affected areas.

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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

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)

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Figure 2. Sub-watersheds affected by mining surface working areas.28

ResultsOpen 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

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

Figure 3. Open pit area in Bagacay Mines.

Bagacay Mines

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WD Location Area (has)

Ave. Thickness

* (m)

Slope (m)

Volume(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

ResultsBagacay Mine has three waste dumps , all almost devoid of

vegetation and contains pyritic materials with an estimated total area of 12 has.

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ResultsWaste Dumps

A. WD 1 DrainageWater 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 Drainagecontains gullies which drain its water/ seepages to the main pit

before flowing to Taft River.

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TP. No. Location Area (has.)

Tails Vol. (m3)

Dam Embankment Length

(m) Height

(m) Slope (0)

1 SW of the mill

plant 0.15 4,390 22 3 30

2,3,5,6 NE of the mill

plant 4 335,341 782 8 35

4 NW of the mill

plant 2 133,029 107 6 35

7 NE of the mill

plant and below TP 2,3,5 and 6

2.5 127,540 172 5 35

8 W of the mill

plant and above TP 1

2 101,935 145 6 30

Tailings Pond There are eight (8) Tailings Pond (TP) in the area

and is estimated to be about 11.0 hectares

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Figure 5. Tailings pond 8 as viewed from the boundary of the open pit.35

ResultsOthers

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-guilaCreek.

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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.

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Rainfall Pattern in the Area

Results

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Results3.4 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 55,800hectares.

The two watersheds have a comparable geology, topography, land use and climate.

The streamflow pattern behaves similarly to the rainfall pattern in the area.

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3.4 Streamflow

DecemberHighest streamflow

April - lowest flow

0

10

20

30

40

50

60

70

Q1

Q2

Streamflow Discharge (m3/sec) of Taft Watershed

m3/

sec.

Month

Streamflow discharge of Taft watershed at the mouth (Q1) and downstream of confluence of Taft River and Guila-gila creek.

Results

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Table 4. Observed streamflow (m3/sec) from the 3 affected creeks as monitored by ERDB-DENR.

Date Guila-guila Creek A Creek B TOTALDecember 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

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Figure. Observed total streamflow (m3/sec) from the 3 affected creeks and % contribution to Taft River as monitored by ERDB-DENR.

0

0.5

1

1.5

2

2.5

3

3.5

Dec Ja

n

Feb

Mar

Apr

May Ju

n

Jul

Month

Stre

amflo

w (m

3/se

c)

streamflow (m3/sec)Streamflow (%)

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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 creeksdraining 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.

Guila-guila Creek, Bagacay Mines

Data show that creeks draining the mined-out area contributed

about 2% of the mean flow of Taft River. 43

Results3.5 Water QualityWater 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.

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Results

0

2

4

6

8

10

12

14

16

3-Dec-09 22-Jan-10 13-Mar-10 2-May-10 21-Jun-10 10-Aug-10

Sampling date

Conc

entr

atio

n (m

g/L)

pH

Fe

Cu

Cd

Pb

Zn

0

1

2

3

4

5

6

7

8

9

16-Dec-09 16-Jan-10 16-Feb-1016-Mar-10 16-Apr-10 16-May-10 16-Jun-10

Sampling date

pH

Fe

Cu

Cd

Pb

Zn

Con

cent

ratio

n (m

g/L)

pH and Heavy metal concentration of Guila-guila creek (upper)and Taft River at Barangy Binaluan (lower).

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Results

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

Table. Water Quality criteria for toxic substances in freshwater.

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Parameters Guila-guilacreek

Binaloan(Taft River)

Creek B Convergence with Taft River

pH 2.605 7.46 2.415 2.325Fe (%) 5.13 4.99 4.85 4.81Cu (mg/kg) 1490.0 2670.0 1617.5 1952.5Cd (mg/kg) 14.85 14.68 12.4 13.95Pb (mg/kg) 276.45 237.95 192.75 394.65Zn (mg/kg) 512.5 630.44 553.69 606.5

Table. Riverbed soil analysis in various points of tributaries.

Riverbed 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

Pollution Load

0

100

200

300

400

500

600

12/1

6/09

12/3

0/09

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

Pol

lutio

n lo

ad (k

g/da

y)

FeCuCdPbZc

Iron and copper were the dominant heavy metals found in flowing water from the affected creeks 48

Guila-guila Creek, Bagacay Mines

The team measuring the site selected for installing hydrologic instruments.49

Guila-guila Creek, Bagacay Mines

The team conducting infiltration measurement . Inset: infiltrometer 50

Conclusion and RecommendationsThe 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.

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Thank you

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