A Research Compendium For Mining And Volcanic Debris-Laden Areas

Compendium of Rehabilitation Strategies for Mining and Volcanic Debris-Laden Areas

REHABILITATION & ECOLOGICAL
RESTORATION R & D FOR MARGINAL &
DEGRADED LANDSCAPES AND SEASCAPES

A Research Compendium
FOR MINING AND VOLCANIC
DEBRIS-LADEN AREAS
DEBRIS-

Department of Environment and Natural Resources
Ecosystems Research and Development Bureau


FOREWORD

Research information and technologies on the restoration of mine
wastelands have proliferated in the past years, however, access to them by the
general public is quite limited. This Research Compendium on Mining Areas
and Volcanic Debris -laden Areas has been developed to serve as a sound and
thorough basis for selection of appropriate, effective and efficient strategies for
the restoration of damaged mining and volcanic ash-laden areas of the country.

This undertaking included an initial compilation of past and recent
scientific and successful rehabilitation works on mine-waste lands and volcanic
ash- laden areas locally and internationally which were organized, integrated
and synthesized into a manual to reflect relevant research strategies and
technologies for possible verification and application under local site specific
conditions.

MARCIAL C. AMARO, JR., CESO III
Director

i


PREFACE

This Research Compendia on Rehabilitation and Ecological Restoration
R & D Technologies for various Ecosystems was published through the efforts of
the Ecosystems Research Development Bureau and its regional research field
counterparts, i.e. Ecosystems Research and Development Sectors. Research
information was gathered from all Regions including those from recent books
and the internet. Ecosystems studied include: critical watersheds, degraded
mine waste areas, volcanic debris laden areas, marginal grasslands and uplands,
damaged urban and coastal sites.

While research and technology information generated in the past years
have proliferated, the changing needs of time require that recent technologies
be collated, integrated, analyzed and synthesized as a basis of decision-making
in verifying the effectiveness and efficiency of said technologies. Managers and
developers particularly in degraded areas need vital source of broad set of
information from which to choose from. This manual hopes to be a meaningful
guide to hasten rehabilitation efforts in these areas.

EVANGELINE T. CASTILLO, Ph. D.
National Program Leader/Coordinator
Rehabilitation Banner Program

ii


ACKNOWLEDGEMENT

This publication is indebted to the following agencies and people who,
in their own way, contributed for the completion of this material:

ERDS Regional Technical Directors and regional focal persons for this
project who contributed in gathering information and articles on the different
rehabilitaion strategies, particularly on species common in the region;

Local mining companies for their collaborative efforts in sharing
information on the different rehabilitation initiatives they have been
undertaking;

Technical Staff of ERDB in gathering the different technologies from
various agencies implementing projects on mining;

DENR-ERDB Management for funding the implementation of this
banner program and the publication of this compendium;

The different library staff of the following offices: DENR Central Library;
College of Engineering Library, UPLB; ERDB Library; College of Forestry, UPLB;
Environment and Management Bureau; and UP Geological Institute Library, UP
Diliman for giving project researchers access to their facilities and resources;

To Ms. Celeste Gonzaga for the editing job;

The GDAERD family, particularly, the support staff for their effort in
encoding, compiling and for their assistance in the final reproduction of these
Compendium.

EVANGELINE T. CASTILLO, Ph. D.
Program/Project Leader

AIDA C. BAJA— LAPIS / MARIA dP. DAYAN
Project Leaders

iii


TABLE OF CONTENTS

FOREWORD i
PREFACE ii
ACKNOWLEDGMENT iii
TABLE OF CONTENTS iv
LIST OF FIGURES vii
LIST OF TABLES x
LIST OF APPENDICES xi

CHAPTER 1
INTRODUCTION 1

Philippine Mining Industry and Its Environmental Impact 1
Volcanic Eruptions and Impacts of Volcanic Ash Deposits 4

CHAPTER 2
PURPOSE OF THE COMPENDIUM 5

CHAPTER 3
DESCRIPTION OF MARGINAL AREAS 6
UNDERSTANDING THE SITE CONDITIONS 6

Mining Areas 6
Mine spoils/waste dump site 7
Mine tailing areas 8

VOLCANIC DEBRIS-LADEN AREAS 9

CHAPTER 4
PRELIMINARY SITE CHARACTERIZATION, ASSESSMENTS 11
AND PROBLEM DIAGNOSIS

Micro-site Assessment Procedures 11
Problem Diagnosis, Analysis and Interpretations 15
Mining Areas 15
Volcanic Ash-Laden Areas 15
Analyzing Poor Plant Growth Performance in Mining Sites 16
Analyzing Erosion Problems for Determination of 16
Appropriate Measures
Project Planning and Design 18

iv


CHAPTER 5
GENERAL MEASURES IN REHABILITATION 19

VEGETATIVE MEASURES 19
Proper choice of plant species for mining land rehabilitation 19
Identifying Candidate Species 21
Potential Grass species 26
Potential Hedgerow/Livepole Species 28

BIOREMEDIATION MEASURES 28
Finding Plants with Bioremediation Potential 28
Types of Metal Phytoremediation 29
Hyper-accumulators 29

Thlaspi caerulescens 29
Stackhousia tyronii 30
Pteris vittata 30
Hibiscus cannabinus 31
Brassica napus 31

Mycorrhiza, a Symbiotic Microorganism with 31
Phytoremediation Potential

Vetiveria zinazoides 34
Imperata cylindrica 34

Microbial Remediation Potential by other microorganisms 34

BIOENGINEERING MEASURES 35
Geomats 36
Extruded geogrids 36
Woven geogrids 37
Geocells 37
Hexagonal wire mesh products (HWM) 38
Jute netting 38
ENGINEERING MEASURES 40
Structural Measures and their Application 41
Retaining Wall 41
Loose rock or stone check dam 41
Pole or log check dam 41

v


Gabions or wire-bound loose stone/rock check dam 41
Rock Gabions 41
Riprap or stone terrace 43
Rock Riprap 43
Bench terraces 43

Increasing Survival and Growth of Plant Species for Mining 43
Land Rehabilitation and Volcanic Debris-Laden areas thru
Effective cultural management practices

Addition of Soil Media as Base Material 44
Liming Application 44
Inoculation with Fitted Mycorrhiza 46
Organic Fertilizer Application 47
Use of Coir Fiber Amelioration Blanket 47

CHAPTER 6
REHABILITATION STRATEGIES IMPLEMENTED BY 48
MINING COMPANIES

Philex Mining Corporation 48
Rapu-rapu Polymetallic Project 48
Atlas Consolidated Mining Development 48
Corporation
Dolomite Mining Project 49
Rio Tuba Nickel Mining Corporation 49
Bagacay Mining Company 49
Benguet Corporation 50
Philex Mining (at Sto. Niño) 50

REHABILITATION STRATEGIES IN PINATUBO VOLCANIC ASH-LADEN 51
AREAS

SHOPLIST OF APPROPRIATE SPECIES AND TECHNOLOGIES FOR
REHABILITATION 53

REFERENCES 54

APPENDICES 60

vi


LIST OF FIGURES

Figure Page
1 The unsightly landscape left by Atlas Mining Company, Cebu. 2
Such inactive or abandoned open pit mines are testimonies
to the environmental degradation of mining.
2 Mining waste materials from the dump site are transported 2
to the river below leading to the communities. Most of the
ricelands close to the waterways were covered with silt,
laden with toxic heavy metals (Suyoc, Placer, SDN).
3 Mined-waste dumps remain barren for years continuing to 3
erode through time.
4 Basic understanding of the problems which are the 6
foundation for determination of appropriate solutions:
physico-chemical conditions of the media (not soil but
mineral media), micro-climate (atmospheric conditions of the
immediate environment), biological (flora, fauna, microflora/
microfauna) and economic considerations of proposed
rehabilitation measures to be employed.
5 The inhibiting effect of cadmium on the growth of oats. 7
6 Mine waste dump or mine spoils comprise the overburden 7
and interburden materials composed mainly of hard rocks,
silt, and sand that are strongly acidic. It is also devoid of
major and minor nutrients to support plant growth.
7 Slope stabilized by bench terraced in the mine waste dump of 8
Antamok, Itogon, Benguet.
8 Mine waste dump area of Manila Mining Company at Placer, 8
Surigao del Norte. Periodic landsliding and slumps have
resulted from its unstable steep slopes.
9 Even with rehabilitation efforts starting either from the base 8
and top ridge and flat areas along valleys, sloping areas
remain unvegetated. Ecological succession failed to proceed
in these areas.
10 Mine tailing areas in Maricalum Mining Company tested with 9
Imperata grass planted at 1 meter spacing. The scheme was
reported to be a failure.

vii


LIST OF FIGURES

Figure Page
11 A close-up photo of the very fine sandy materials. Note that 9
Mimosa pudica, a nitrogen-fixing species was able to survive
the harsh environment. However, the poor microclimate
have limited its capacity to expand outward.

12 During rainy season, massive erosion of volcanic ash and 10
lahar area were experienced due its quite loose mineral
particles.
13 Plant indicators present in the mined-out area shall be 12
photo-documented.
14 Cogon with purplish blades is an indicator of low 12
phosphorus content.
15 Media productivity contour map using pH values. 14
16 Mere establishment of plant species without consideration 16
of the environmental limitations in the planning process
resulted in poor growth performance affecting survival in
the long run.
17 Two basic strategies or lines of defenses in arresting soil 17
erosion.
18 Sloping mine waste of Mogpog, Marinduque with landsliding 17
and gullying starting from the middle slope to the bottom of
the slope.
19 Its extensive and thick root system binds the soil and at the 26
same time makes it very difficult to be dislodged an
extremely tolerant to drought.
20 When buried by trapped sediment, new roots are developed 26
from nodes and vetiver will continue to grow with the new
ground level eventually forming terraces, if trapped
sediment is not removed.
21 Vetiver grass turned brown in peak summer but regrew 27
when intermittent rainfall came during the next season
(Pilot demonstration site at Placer, Surigao Del Norte).

22 Construction of a bamboo-reinforced embankment in 27
progress

viii


LIST OF FIGURES

Figure Page
23 Morphological characteristic features of Thlaspi plant. 29
24 Sunflower is easily available species for propogation. 30
25 Braken fern possess dark green large, long leaflets 31
compared to other ferns.
26 Various varieties of ferns consistently thriving in almost all 31
mined-out and mine spoils throughout the country.

27 Mechanisms of how mycorrhiza help respond to metal 32
toxicity.
28 Robust batino plant in the mine waste dump site. 32
29 Comparative growth performance of Agoho (Casuarina 33
equisetifolia) in mine waste areas of Itogon, Benguet.
30 Spores of vesicular –arbuscular (VA) mycorrhiza Glomus sp. 33
Mycorrhiza has been identified as a major player in
removing of heavy metals in soils like the mine waste areas.
31 Geomats main function is to protect the land against 36
superficial erosion caused by the impact of rain drops and
rills, or the flood action for river channels.
32 Extruded geogrid polymers are commercially available 37
materials.
33 Geogrid materials may also be woven or bonded. 37
34 Its function is to hold soil or other loose material in place 37
and to prevent the superficial soil from slipping down slopes.
35 Woven geotextile are double-twisted materials. 38
36 Biomats and biotextiles are similar to geomats in function 38
but differ in that they come from biological materials.
37 Close-up view showing jute netting in a roadbank in Cavite. 39
38 Biomat Installation Procedures 39
39 Gabion illustration of Installation Design (Front View) 41

ix


LIST OF FIGURES

Figure Page

40 Gabion illustration of Installation Design (Top View) 42
41 One of the most practical measures preferred for mining 43
Rehabilitation
42 Soil can be enclosed by organic materials such as coir for 47
moreassurance of survival under harsh conditions.
43 Mine waste area of Benguet Corporation in Antamok, Itogon, 50
Benguet prior to rehabilitation (left).
44 The same mine waste area with 2-year old benguet pine 51
inoculated with mycorrhiza (right)
45 Mycorrhizal rain tree growth performance after three years. 51

LIST OF TABLES

Table Page
1 Total heavy metal content (in mg/kg) on-site and 7
corresponding environmental and health threshold levels.

2 Blocking Scheme in a slope for determination of soils for pH 14
and other laboratory analysis
3 Leopold Matrix of Species for Rehabilitation of Mining and 22
Volcanic Debris Ash-Laden Areas
4 Relative Neutralizing Power (RNP) for common lime 45
materials.

x


LIST OF APPENDICES

Table Page
1 Biophysical Requirements of Species Suitable for 61
Rehabilitation of Mining & Volcanic Debris-Laden Areas
2 Seed Technologies for Various Species Suitable for 76
Rehabilitation of Mining & Volcanic Debris-Laden Areas
3 Nursery Techniques and other Cultural Management 92
Practices of Species Suitable for Rehabilitation of Mining
& Volcanic Debris-Laden Areas
4 Pest and Disease Control Strategies in the Nursery and 107
Plantation for Species Suitable for Mining & Volcanic Debris
-Laden Areas
5 Field Plantation Cultural Management Techniques of 112
Species Suitable for Mining & Volcanic Debris-Laden Areas
6 Inert Materials Functions 123
7 Cost Analysis of Coco coir Technology 124

Plate No. Page
1 Cocomat Application and Installation Techniques. 125

xi


Chapter 1

INTRODUCTION

Philippine Mining Industry and Its Environmental Impacts

The Philippines is among the world’s richly endowed countries in terms
of mineral resources. It ranks second in the world’s source of chromite and
considered as one of the largest in the world. The country is projected to be the
next mining wonder in the next few years as the country’s gross production
from local minerals is expected. Also, as further projected, the country is eyed as
the mining country of the Pacific region by 2010. Recent figure of mining
contribution to GDP in 2005 was 68.4 billion pesos which doubled the gross
production in 2002 of 35.2 billion (Manila Bulletin and Philippine Star, 2007).
The total exports of mineral and mineral products have doubled from US$ 820
million in 2005 compared with the recent value of US$ 206 billion.

The mining industry plays an important role in the country’s economic
development as it has increased direct employment from 101,000 in 2002 to
141,000 which is a significant portion of the population and has indirectly given
other income generating opportunities. Moreover, the industry paid taxes, fees
and royalties of about PhP 3.1billion in 2005 which is more than double the
2002’s PhP 1.4 billion.

Mining activities are governed by rules and regulations and strict
compliance to measures abating environmental degradation due to
indiscriminate mining processes are closely monitored by multi-sector
stakeholders to ensure that a responsible mining is well in place. It is the desire
of the government that there should be balanced consideration between
socio-economic gains and environmental accountability while engaging in
mining.

However, it is a sad reality that in the course of any mining activity,
unavoidable physical damage to ecosystems and destruction to habitat are
committed. Open-pit mining clears the vegetation covering the deposits,
inevitably exposing the soil and permanently changing the landscape and land
use (Fig. 1.).

1


Fig. 1. The unsightly landscape left by Atlas
Mining company, Cebu. Such inactive
or abandoned open pit mines are
testimonies to the environmental
degradation of mining.

One critical activity in mining is the disposal of mining wastes. Waste
materials usually drains into the major water systems. The transport of quite
loose particles, medium to large rocks and boulders from waste dump areas
becomes inevitable (Fig. 2).

Fig. 2. Mining waste materials from the
dump site are transported to the
river below leading to the
communities. Most of the ricelands
close to the waterways were
covered with silt, laden with
toxic heavy metals (Suyoc, Placer,
SDN).

The mining process exposes heavy metals and sulfur compounds that
were previously locked away in the earth. Rainwater leaches these compounds
out of the exposed earth, resulting in "acid mine drainage" and heavy metal
pollution that can persist after the mining operations have ceased.

Similarly, rainwater on piles of mining waste (tailings) can adversely
transfer pollution to freshwater supplies. In the case of gold mining, cyanide is
intentionally poured on piles of mined rock (a leach heap) to chemically extract
the gold from the ore. Some of the cyanide ultimately finds its way into nearby
water. Huge pools of mining waste "slurry" are often stored behind
containment dams. If a dam leaks or bursts, water pollution is guaranteed.

The increasingly higher quantities of these heavy metals being released
into the environment by anthropogenic activities, primarily associated with
industrial processes, manufacturing and disposal of industrial and domestic
refuse and waste materials pose a major environmental and human health
problem which needs an effective and affordable technological solution. Heavy
metals contaminate the soil and water. Particularly affected are irrigation
facilities posing threat to agricultural productivity and destruction of adjacent
marine ecosystems. Thus, in every mining activity, negative consequences to
the environment and various ecosystems are manifold and impacts to human

2


welfare are equally significant. As such, prior to setting any mining industry,
mitigating measures and rehabilitation plans are prescribed in all phases of the
activities.

In 1995, the guiding principles emphasized by the government were the
pursuance of responsible mining, rehabilitation of abandoned mines and to
safeguard the ecological integrity of areas affected by mining.

Vast mining areas however lie unsightly to the public as they have
remained for decades as abandoned without any rehabilitation efforts made
(Fig. 3).

Fig. 3. Mined-waste dumps remain
barren for years continuing to
erode through time.

In the course of mining operations in the past, major environmental
catastrophes have placed mining industry in jeopardy. Case in point was in
1996, whereby toxic mining wastes of Marcopper Mining Company in
Marinduque spilled into the main waterways which was caused by its
defective waste disposal facilities. This resulted in millions of fish kill which
significantly affected fish catch, and threatened the health and livelihood of the
population living in nearby coastal communities.The pit of Atlas Mining in
Toledo City, Cebu gave way to the clogged drainage that released acidic water
to the sea that caused the poisoning of marine life along the coastal areas. The
latest incident was in Rapu-rapu Island where high level of cyanide was released
in the coastal zones that killed fishes. Mining companies have been penalized
by suspension of operations and payment of a huge sum of money. This served
them a lesson to abide by the regulations as provided by the Philippine Mining
Act of 1995.

To date, there are 65 non-performing mining tenements that were
cancelled, representing 68,000 hectares of mineral land which is open to serious
investors for development (Reyes, 2007). Out of these, 24 were already
abandoned and need immediate rehabilitation (MGB, 2007). These areas were
left out after several years of mining operations leaving behind toxic waste
materials, overburdened areas that are stony, rocky and acidic.

3


These areas have open pits and mine tailings. Aside from this, there are
large portion of reforested mine waste areas with plants of poor health status
which were observed to die prematurely.

Volcanic Eruptions and Impacts of Volcanic Ash Deposits

Aside from mine waste areas, volcanic ash-laden areas pose another
great challenge in rehabilitation. The eruption of Mt. Pinatubo in the early
1990’s has destroyed vast tracts of agricultural land in adjacent provinces. With
a stroke of nature, millions of tons of volcanic ash, mudflow carrying pyroclastic
materials and other debris were deposited on the once productive areas turning
them into barren and idle areas. Aside from the tremendous losses of life and
properties, the vegetation which provides the basic needs of man for food and
shelter, clean air and water has been totally devastated. There is an urgent need
to find prompt research solutions to the vegetative rehabilitation of the
degraded areas which require primary succession.

In deep-volcanic ash laden areas wherein agricultural crops would be
difficult to grow, long–term species such as trees would be the most suitable.
Both the species and strategies for afforestation are wanting. Plant species must
have the ability to promptly colonize the thick ash-laden sites. To wait for
natural ecological succession to occur starting with lower forms of life may be
too long and impractical to meet the urgent needs of our people. Successful
afforestation strategies must therefore be characterized by their efficiency to
shortcut the route of long-term ecological succession.

4


Chapter 2

PURPOSE OF THE COMPENDIUM

This compendium is intended to provide the necessary information and
technologies using plant species for vegetative restoration, as well as other
engineering strategies, their combinations or mixes that can be adopted to ensure
success in rehabilitation works.
The data were gathered from various research outputs from published
articles and journals, as well as from documented experiences and success stories
that have shown positive results. When research literature were still found
fragmentary, the research team (comprising ERDB and regional research
counterparts) supplemented their research data from those coming from various
regulatory and research institutions and integrated R & D related subject matters
to form science-based protocols for rehabilitation. This compendium hopes to
provide several potential strategies to choose from to suit specific conditions of
damaged areas.
The contents of the compendium include the status of Philippine mining
industry, description of marginal sites, purpose of the development of the
compendium, site characterization assessment and problem diagnosis,
rehabilitation measures and/or technologies in mining and volcanic debris-laden
areas.
In the Appendices, each common plant species for mining were categorized
into tables where selection can be done for appropriate application in
rehabilitation using vegetative means. Each species was described morphologically
and characterized according to its site requirements, needed amelioration, control
measures for pest and diseases, and planting strategies. The complete information
of the species have been presented in the appendices in a matrix form (template)
for easy reference. Information on several bio-engineering strategies to choose from
were also provided for areas where vegetative measures would not be sufficient.
It is envisioned that this compendium will be of valuable application to the
mining industry, watershed development, vegetation of denuded areas, restoration
of places affected by natural disasters such as volcanic ash-laden, landslide areas
and the like. The target client and users of the mining compendium will be those
who are involved and engaged in rehabilitation work as mandated by
environmental law and in compliance with the provision of Philippine Mining Act of
1995.
Furthermore, it is hoped that end-users of the compendium will find it as a
useful guide in various stages of rehabilitation, reclamation and ultimately the
restoration of disturbed sites into, at least a more productive if not in its original
state. Likewise, may this compendium, with its assemblage of knowledge and
practices, fit well into the need for rehabilitation measures that will minimize the
cost of a rather expensive rehabilitation works.

5


Chapter 3

DESCRIPTION OF MARGINAL AREAS

Understanding the Site Conditions

Before rehabilitation efforts could be done, it is imperative to develop a
complete understanding of the on-site conditions of these areas before we can
provide proper ecological solutions to them (Fig. 4)

ON-SITE CONDITIONS

Physico-
Microclimate
chemical

Biological Economic

Complete understanding the ecological
status of the site for rehabilitation

Fig. 4. The basic understanding of the problems which are the foundations for determination of
appropriate solutions: physico-chemical conditions of the media (not soil but mineral
media), micro-climate (atmospheric conditions of the immediate environment), biological
(flora, fauna, microflora/microfauna) and economic considerations of proposed
rehabilitation measures to be employed.

A. Mining Areas

Mined-out areas consist of the open pits which are left behind after the
mining operation. They are characterized by being acidic and saline due to
oxidation of pyretic materials (Yao, 2001). It is the most difficult sites for
rehabilitation, because the pH fall below 4.0 that it plant survival and growth
become nil if not ameliorated. These areas are usually untouched for
rehabilitation unless bulk of soils is brought back to the site.

In a gold mine area, heavy metals on site are way above normal levels.
Typically, these include copper, arsenic, chromium, lead, zinc and strontium,
elements that are later carried away by running water to the low lying areas.
Table 1 shows the results of study in Australia ((Truong, 1995),have shown that
indeed heavy metal content in a gold mine exceeded the set threshold levels.
The negative effect of them in plants is further reflected below (Fig. 5).

6


Table 1. Total heavy metal content (in mg/kg) on-site and corresponding
environmental and health threshold levels.

Heavy Metals Thresholds mgKg-1
Environmental Health GOLD MINE
Heavy Metals mgKg-1 Total Content
Arsenic (As) 20 100 Arsenic 1,120
Chromium (Cr) 50 - Chromium 55
Copper (Cu) 60 Copper 156
Manganese (Mn) 500 Manganese 2000
Lead (Pb)
(Pb) 300 300 Lead 353
Zinc (Zn) 200 Zinc 283

General Plant Responses to Heavy Metal Toxicity

Fig. 5. The inhibiting effect of cadmium on the growth of oats .

Mine spoils/waste dump site are places where the originally removed
layers from mined- out areas are dumped. Because of periodic dumped
materials, rock materials therein are variable in terms of size and chemical
composition (Fig. 6 and 7).

Fig. 6. Mine waste dump or mine spoils
of Manila Mining Company at
Placer, Surigao del Norte com-
prise the overburden and inter-
burden materials composed
mainly of hard rocks, silt, and
sand that are strongly acidic. It
is also devoid of major and
minor nutrients to support

7


Fig. 7. Slope stabilized by bench terraced in
the mine waste dump of Antamok,
Itogon, Benguet.

Because of general lack of homogeneity in a given site, collection of
mineral and their chemical analysis are preliminary part of site characterization
activities.

Sloping mine waste lands are often last choice for rehabilitation by
developers due to safety reasons (too steep slopes, unstable materials highly
prone to landsliding, and erosion (Fig. 8 and 9).

Fig.8. Mine waste dump area of Manila Mining
Company at Placer, Surigao del Norte.
Periodic landsliding and slumps have
resulted from its unstable steep slopes.

Fig. 9. Even with successful rehabilitation
efforts in mine waste dumps starting
either from the base or top ridge and
flat areas along valleys, sloping areas
remain unvegetated. Ecological
succession failed to proceed in these
areas.

Mine tailing areas are extensive mine waste dump areas which consist of
lighter particles refuse material resulting from processing ground ore (Fig. 10).
These materials have passed over a sieve in milling, crushing, or purifying
operations and treated as inferior in quality or value. Materials consist of small,
uniform, mostly sand and silt-sized particles (Fig. 11). Because of very fine
texture, the soil is loose but the bulk density is high. This in effect controls
particle aggregation and soil texture thus rendering very low water holding
capacity.
8


Fig. 10. Mine tailing areas in Maricalum
Mining Company tested with Imper-
ata grass planted at 1 meter spac-
ing. The scheme was reported to be

Fig. 11. A close-up photo of the very fine
sandy materials. Note that Mimosa
pudica, a nitrogen-fixing species was
able to survive the harsh environ-
ment. However, the poor microcli-
mate have limited its capacity to

These areas are not only deficient in clay minerals and microorganisms
but are basically nil in organic matter, nitrogen, phosphorus and potassium
while excessive in heavy metals. Sand blasting during windy days causes rapid
transpiration resulting in the death of intolerant species. Although located in flat
areas, erosion in these areas are also prevalent coming from wind sources.

B. Volcanic Debris - Laden Areas

The Philippine islands consist of several active volcanoes which from
time to time erupted in the past years. These events brought about voluminous
ejection of volcanic gases, molten rocks, volcanic ash and other pyroclastic
materials several kilometers into the air. Areas within the immediate vicinity of
the volcano were buried to as deep as 50 to 100 meters. Spewed up materials
generally constituted dacite, andesite, basalt and pumice.

As a result of eruption of volcanoes, volcanic debris, molten rocks and
pyroclastic materials were deposited as loose materials in vast areas
surrounding the volcano. The eruptions of Mt. Pinatubo in Central Luzon 1991
and Mt. Mayon in Albay (still actively erupting) have left vast areas with two
general types of materials: 1) lahar-pyroclastic mudflow deposits which covered
their major drainage and 2) volcanic ash- deposited loose sand and silt materials
which buried extensive low-lying grounds. Inasmuch as the majority of areas
which now needed rehabilitation efforts are of the volcanic ash-laden materials,
this compendia shall deal more on said topic.
Generally the vast desert-like areas are often exposed to weathering
and pressures of extreme conditions that barely supports life. The volcanic ash

9


Substrate is generally very loose and pliable thus prone to erosion, devoid of
nutrients for plants to grow and water is very limiting in the area.

The sandy mineral particles that cover the thick land areas are
characterized by low water holding capacity and require irrigation for the plant
to survive. At the same time, even it is of poor water holding capacity, areas
under deep volcanic ash can easily be washed out by high intensity and heavy
rainfall (Fig. 12).

Fig. 12. During rainy season, massive erosion of volcanic ash and lahar
area were experienced due its quite loose mineral particles.

Assessment of chemical status of the volcanic ash with time revealed
that during the first month, the volcanic ash media was initially acidic due to the
effects of sulfur dioxide. But after this was leached and/or volatilized in the
atmosphere, volcanic ash pH became neutral (values ranged from 6.0-7.2). The
pH status however decreased three years later. With mineralization process in
the later years, ash mean value ranged from 5.0-5.9.

Although the mineral media attained high pH level, chemical analysis
revealed low concentration of macro and micro nutrients. In the sterile media,
nitrogen, potassium and micronutrients content were all nil. Only phosphorus
was medium in content. There was also no starter microsymbiont found. Such
imbalance in the nutritional status, poor physical conditions (i.e. low water
retention capacity) and droughty atmospheric condition all redound to the need
for special strateg(ies) that would address all the limitations in order to
succeed in such areas.

Natural succession takes a long process. But a system to accelerate the
pace can be done in a much faster time thru current technologies. Starter
volcanic ash-laden sites can be pilot tested to showcase the viability of
converting desert-like conditions to a mini-forest cover in a much shorter time
imagined. Later, these nucleus areas are designed to be growing points to
expand ecological restoration of more areas in the long run.

10


Chapter 4

PRELIMINARY SITE CHARACTERIZATION, ASSESSMENTS AND PROBLEM
DIAGNOSIS

Proper diagnosis of problems besetting a site requires a ful characterization
of the on-site biophysical conditions as well as the off-site socio-economic
situation of nearby affected communities.

Micro-site Assessment Procedures

Because of the observed site heterogeneity, it is a basic step to conduct
micro-site assessment of a proposed area to be rehabilitated. The following are
the procedures to be undertaken:

1. Collect baseline secondary information of the proposed mining area for
rehabilitation prior to the on- site reconnaissance and field verification.

2. Site Characterization of Selected Site (s)
The following specific site conditions of the chosen site(s) shall be
characterized:

Mine spoils/mine waste dumps – soil and fragmented rocks hauled and
dumped on the surface of the mountain

I. General site description
A. Specific classification of mine waste area (mine waste/mine
tailings)
B. Location (Sitio, Brgy., Municipality, Province)
C. Accessibility – distance from the nearest road networks from the
nearest barangay.
D. Boundaries – direction (N, E, W, S)
E. Microclimate
• Rainfall (secondary data) - Rainfall or precipitation is the
amount of water that fall upon the earth.
• Temperature (air and soil) - Temperature is the degree of
hotness or coldness of the air.
• Sampling of diurnal temperature range for the whole day
(8, 10, 12, 2, 4 o’clock at least 3 sampling days using air/
soil thermometer)
• Relative humidity (wet and dry bulb thermometer)

11


F. Ecological

• Flora (Vegetation) -Observation on the presence of naturally growing
plant species and occurring in the mined-out/mine waste dump areas
must be properly photo-documented (Fig. 13 and 14).

Fig. 13.Plant indicators present in the mined-out area must be photo- documented.

Fig. 14. Cogon with purplish blades is an
indicator of low phosphorus

• Fauna- Observation of the presence of specific fauna (birds, insects
etc.) in the area (faunal indicators).

II. Detailed characterization of the micro-site

A model area must have a minimum area of one (1) hectare. The
whole area must be subdivided into compartment units depending
on the natural limitations of land features (bodies of water, ridge,
heterogeneity of the sites, etc.). A minimum of two major
compartments may be selected to verify the technologies.

Each compartment units must have its own individual micro-site
characterization as a basis for the field treatment lay-out and application
of future demonstration of different rehabilitation technologies.

A. Topographical Features

Terrain/slope (using abney hand level)
Elevation (altimeter)

12


B. Geological Features

1. Description (secondary information and field observations)
• Type and nature of rock deposits (gold, copper, zinc, iron, chromite,
silver, nickel, etc.)
• Physical characteristics (description of rock fragments- relative size,
variability of size, relative imperviousness, drainage (waterlogging)
and aeration)
• Erosion description (relative formation of rills, gullies and landslides)
depths, extent/percentage of area affected and erodibility of loose
rocks and mineral particles

2. Collection of mine waste media samples for physical and chemical
analyses

Basis of Media Sampling in the Field

a. Narrow and long slope

The occurrence of fertility gradient is usually more pronounced
in sloping areas, i.e. with the lower portion more fertile than higher
areas. Take mine waste media samples for physical and chemical
property determination. Utilizing representative points along the
contour of various contour/ slope locations (i.e. top, middle, and
bottom), collect composite samples from at least 5 points. The
distance in between 1 contour sampling line will depend upon the
slope length, degree and heterogeneity. Get mine waste media
samples from a depth of at least 30 cm.

b. Media Heterogeneity

If the area is very heterogeneous, a soil productivity contour map
must be made. It is a simple but informative presentation of soil/media
heterogeneity. It is advisable to conduct uniformity trial to assess the
pattern of soil heterogeneity so that a suitable remedy can be achieved
by proper blocking. Fig 15 is a slope subdivided into blocks ex. Column
A, Row 1 as one unit (Table 2). The whole slope has 16 unit blocks. The
map describes graphically the productivity level of the experimental
site base on moving averages of contiguous unit. Values represent
numerical pH.

13


Mineral Sampling Field Lay-out

Analysis of pH indicates blocks column a-row 1, column b-row 2 and
column d-row 4 had the same pH value of 3 of the sampling area point
representing that block.
Column Column Column Column
A B C D
Row 1 3 3 3 5

Row 2 4 3 4 5
Row 3 4 5 4 3

Row 4 5 5 4 3

Table 2. Blocking Scheme in a slope for determination of pH and other laboratory analysis.

pH 3 pH3 pH 3 pH 5

pH 4 pH 3 pH 4 PH 5

pH 4 pH 3
pH 4 pH 5

pH 5 pH5 pH 4 pH 3

Fig 15. Media productivity contour map using pH values

In volcanic ash laden areas which are located in relatively flat areas, the
media are more or less homogenous in composition. Hence sampling scheme is
simpler and fewer soil samples should be taken. A minimum of 5 samples for
every hectare would suffice.

Quick field chemical, qualitative tests for pH, nitrogen, phosphorus and
potassium using Soil Testing Kit must be done.

Laboratory Quantitative Analysis

Quantitative chemical analysis of the following are also required:
Macronutrients (Nitrogen, phosphorus, potassium, calcium,
magnesium);
Micronutrient (Zinc, copper, manganese, molybdenum, boron);
Heavy metals (Gold, nickel, lead, etc).

14


Problem Diagnosis, Analysis and Interpretations

Characterization of site conditions has bearing on the analysis of the
nature of various problems, and ecological factors for proper decision making.
Usually, a summary of the major identified ecological problems besetting our
mining and volcanic ash laden areas are as follows:

Mining Areas

Barren site – droughty atmospheric conditions, high heat load, lack of water
Rock, mineral media - variable or heterogenous materials; no soil;
Generally dumped rocks are loose but compacted by
tractors in mine waste areas;
Nil symbiotic microbes; extremely acidic condition and
increasing acidity thru time; fixed macro and
microelements; possess high levels of unwanted heavy
metals; hazardous to health when transported to
waterways;
Slope condition-steep slopes >30%

Mine waste areas: steep to very steep; rills and gulley formation prevalent;
Landsliding and slumps occurring; hazardous to human;

Mine tailings: Flat areas; Occurrence of wind erosion;
Flora - None or nil existing flora only ferns and mosses;

Presence of company support for rehabilitation:
Low in long abandoned mined-out areas
LGU support: minimal Illegal panning and extraction activities

Volcanic Ash laden Areas

Media: Loose, fine mineral particles, high percolation rate, pH more or else
neutral to basic, low in available nutrients.

Type of Erosion experienced in the site: Wind erosion
Flora: N-fixing trees like ipil-ipil, kakawate, agoho; pasture legumes; grass
species associated with mycorrhizal i.e. Imperata, napier and talahib;

Problems: Barren, desert-like areas hardly vegetated except if seeds are
carried to the area by wind and germinates during wet season; heavy
sedimentation and siltation of bodies of water;

15


Analyzing Poor Plant Growth Performance in Mining Sites

The choice of plant species is one of crucial steps in decision-making.
Most often multiple problems arise in the course of plant development.
Because of the very harsh environment in mining sites, that no plant is able to
survive at the initial stage or there is low plant survival; remaining seedlings
suffer from stunted growth, nutrient deficiency and/or heavy metal toxicity
symptoms; and most often, trees have very poor health resulting to death early
in life (Fig. 16.). Aside from these, sloping areas remain unvegetated, ecological
succession failing to proceed in these areas. Choice of site to be rehabilitated
should thus give priority to this erodible site or else active erosion advancing
to rill and gully formations and occurrence of slumps/landslides are bound to
predominate.

Fig. 16. Mere establishment of plant species without consideration of the environmental
limitations in the planning process resulted in poor growth performance affecting
survival in the long run.

Analyzing Erosion Problems for Determination of Appropriate Measures
Erosion is the natural process whereby external agents such as wind or
water resource transport soil particles to far distances. In the wet tropics like
the Philippines, rainfall is mainly responsible for the removal of superficial layers
resulting in rills or gullies of about 10-60 cm depth. Over time, rills and gullies
deepen and these cause slopes to become over-steep, thus precipitating
instability.

In an open, sloping area (Fig. 17), the largest exposed surface ground
area can be economically controlled by covering the land by vegetation. In
particular, cover crops, creepers and stolons can do this as first line of defense.

16


SCHEMES TO CONTROL

LINE OF DEFENSES COVERING

FIRST LINE OF DEFENSES

2nd LINE OF DEFENSES

STABILIZING

Fig. 17. Two basic strategies or lines of defenses in arresting soil erosion

Instability or deep-seated problems can arise on their own depending
on slope geometry’s inherent soil strength, ground or pore-water characteristics
(Fig. 18). These are basically geotechnical/geological problems that have to be
addressed by proper studies and analyses.

Through available computer programs, the evaluation of the stability of
slopes to determine their factors of safety against sliding or failure has now
become less tedious or laborious.

Fig. 18. Sloping mine waste of Mogpog, Marinduque with
landsliding and gullying starting from the middle slope
to the bottom of the slope.

On the other hand, shallow-seated problems, which lie in the 60-250
cm depth, do not lend themselves for accurate computer program computation.
They present a chronic problem in the wet tropics with the attendant heavy
rainfall and inherent highly erodible slope materials. However, it is believed this
problem can be dealt with very effectively by bioengineering measures.

17


Project Planning and Design
The success of reclamation schemes will depend upon the systems
approach employed in a unit area.
(1) The type (s) of general measures applied (i.e. vegetative, or the
combination of vegetative and engineering or bio-engineering,
bioremediation (plants plus the use of their association with symbiotic
microorganism), and engineering measure;
(2) The choice of plant species (if it were vegetative or bio-engineering or
bio-remediation);
(3) The proper methods of establishment, amelioration measures and
periodic care;
(4) The concomitant best research technologies of growing said species
(from the nursery to the field); the same holds true with engineering
measures. The appropriate engineering measure, design and
attendant methodologies for each specific site condition(s) must be
employed.
In planning for the selection of rehabilitation schemes, there is now a
long list of available developed technologies by industries, scientists and
practitioners from which to choose from. These include research information
and technologies on the following areas:

Vegetative Measures:

a. Species-site suitability (the selection of the right species for different
locations),
- Nursery production technologies (schemes of nursery and cultural
management of a species)
- Field establishment, soil amelioration measures and methods of
application
b. Bioremediation (biotechnology) application technologies in ecological
rehabilitation, etc.
c. Bio-engineering (combined plant and engineering) measures
- Selected plant species (used for slope stabilization)
- Innovations with combinations of plant and engineering
measures
- Inert materials manufactured by industries (intended to mimic
natural plant cover) in combination with other schemes
d. Engineering measures

18


Chapter 5
GENERAL MEASURES IN REHABILITATION

The a foregoing discussions will deal on the broad spectrum of available
technologies, strategies, schemes and procedures to choose from depending
upon site situations and appropriateness. One may select several combinations
of schemes and measures for a given slope at varying locations. The systems
approach is the best strategy, i.e. utilizing all possible schemes that would
hasten restoration but also considering the available economic resources in
applying it.
VEGETATIVE MEASURES
Proper choice of plant species for mining land rehabilitation

Biological intervention refers to the use of versatile plant species
(Single/combination of species) such that it can overcome many if not most of
the problems confronting the restoration of degraded areas. The species must
have the following characteristics:
(a) Ability to survive, adapt and grow normally under harsh condition;
(b) Ability to grow at extremely low/high pH levels;
(c) Potential to grow fast/ increase its biomass;
(d) Tolerate drought and fire;
(e) nitrogen-fixing and/or mycorrhizal associations (bioremediation
potential);
(f) Resistance to pests and diseases;
(g) Potential to reproduce even under adverse environment;
(h) Ability to phytoremediate (remove toxic heavy metals from the
mine waste areas).
The species should also possess other environmental functions. The
so-called bio-engineering strategy combines vegetative and engineering
schemes i.e. planting of certain species or mix of different plant forms in a
methodical manner to provide structural cover for erosion control, slope
stabilization and enhanced drainage system. The root system of plants used in
this strategy provides the protective function to the soil.

For erosion control, the choice of vegetation is relatively wide.
Generally, all plants are capable of providing some degree of protection,
whether they are trees, shrubs or herbs: Shrubs and herbs, grasses and creepers
are plant forms for immediate cover while trees provide the best long-term
protection against soil erosion and landslide. A variety of perennial species are
being utilized as hedgerows to stabilize slopes and prevent soil for further
transport downhill.
19


More often, not just a single species but a combination of trees, shrubs,
grasses and creepers would be needed to provide a significant reduction in
surface runoff and soil erosion. Vegetative measures are first choice because
they are rather cheap materials, i.e more or less four times cheaper engineering
structures.
The basic considerations in the selection of tree species as
bio-engineering measure against soil erosion and landslides are as follows:
a. Plants must grow quickly to establish ground cover, have dense rooting
systems and canopies.
b. Roots and aboveground parts should grow rapidly in order to provide the
required protection as soon as possible (rapid lateral growth of stems,
leaves and roots for erosion control)
c. Plant should possess deep and wide root system for good anchorage in
the subsoil. A dense shallow root system can also be used because of the
matting effect
d. Rapid and dense growth of roots vertically for shallow-seated slope
stabilization
e. High root tensile strength and surface roughness for soil reinforcement
f. Plant should produce a large volume of litter to improve the site. Leg-
umes, in particular, can add considerable amount of nitrogen to the soil
through symbiosis with nitrogen-fixing bacteria
g. Prevent or minimize further transport of eroding materials
h. Plant should form dense and wide spreading crowns or interlocking
canopy as early as possible.
i. Ability to be propagated vegetatively/asexually as large section cuttings as
used in brush layering and as large diameter live poles. When using a
species as live poles for slope stabilization, they must also have the
following features:
• Ability to resist impacts imparted by driving
• Ability to grow long straight branches needed for ease in installation
• Ability to withstand burial and impact by moving slope debris
• Ability to propagate from large section hardwood cutting
• Ability to grow rapidly and well when thickly or closely planted
• Ability to root at depth;
• Ability to grow in water logged condition
• Has relative tolerance to insects & diseases
• Grows into a tree it left unattended

20


Identifying Candidate Species
Species selection is important to establishment success in the degraded
mining area. If grown under unsuitable site conditions, generally, a species
would not be able to cope up with the conditions hence affecting its status. The
species is prone to attacks of diseases, insects and pests.
There are many candidate species having multi-functions: fast-growing,
drought tolerant, with coppicing ability, and grows under nutrient deficient
areas.
After a thorough study on all environmental parameters matching with
the long list of species, those that are closely adaptable to the desert-like
conditions of mining and volcanic ash-laden areas were pre-selected and
tabulated in a decision matrix table.

Leopold Matrix in Appendix Table 8 summarizes the pre-selected
appropriate trees, shrubs, and grass species. Each species was described
morphologically and characterized according to its site requirements. The
package of technologies of each species starting from seed technology, needed
amelioration, control measures for pest and diseases, and planting strategies
are presented in the Appendix Tables 1 to 5 in a matrix form (template) for easy
reference.

21

22
Table 3. Leopold Matrix of Species for Rehabilitation of Mining and Volcanic Debris Ash-Laden Areas
SPECIES ELEVATION RANGE (M) DROUGHT TOLERANCE pH REMARKS
Scientific Name Common Name(s) 0 - 1000 0 - 1500 0 - 2000 G M E P Act Wt Nac
TREES
Acacia auriculiformis Japanese acacia, X X X X X X X pH range: 3 - 9.5 Best
Auri, Wattle, Ear- growth: 5 - 6
pod wattle

Acacia mangium Willd. Mangium X X X X
Albizia procera (Roxb.) Benth. Akleng parang X X X X X X
Aziodirachta indica A. Juss. Neem X X X X X X
Calliandra calothyrsus Meissn. Calliandra X X X X X
Casuarina equisitifolia L. Agoho X X X X
Gliricidia sepium (Jacq.) Steud. Kakawate X X X X X X

Leucaena leucocephala (Lam.) de Ipil-ipil X X X X X
Wit.

Piliostigma malabaricum (Roxb.) Alibangbang X X X X
Benth. Var acidum (Korth) de Wit.

Pithecellobium dulce (Roxb.) Kamachile X X X X X X
Benth.

Pterocarpus indicus Willd. Narra X X X X X X

Samanea saman (Jacq.) Merr. Rain tree, Acacia X X X X X

Trema orientalis (Linn.) Blume. Anabiong X X

GRASSES
Pennisetum clandestinum Hoehst. Ex Kikuyu grass up to 3000asl X X
Chiov.
Vetivera zizanioides Vetiver X X X X X
SHRUB
Tithonia diversifolia Wild sunflower 1000 - X X
2000 asl
Albizia lebbekoides (DC.) Benth. Kariskis X X X X X X
Alnus japonica / maritima (Thumb.) Alnus X X X X X
Steud.
Muntingia calabura Linn. Datiles X X X X X X X
Piper aduncum L. Spiked pepper, X X X
Hequillo de hoja
Sesbania grandiflora (L.) Pers. Katurai, Agati, Bacule X X X X

Zizyphus jujuba (L.) Lam. and Mill. Mansanitas X X X X X

GRASSES
Imperata cylindrica (L.) Beauv. Spear grass, alang-alang, cogon, bae mao 2300asl X X
gen
Kikuyo Kikuyo grass X X X
Phyllostachys aurea Carr. Ex A & C. Chinese bamboo X

Rivere
Bambusa blumeana Kauayan tinik X

23

24
Scientific Name ELEVATION RANGE (M) DROUGHT TOLERANCE pH REMARKS
SPECIES Common Name(s) 0 - 1000 0 - 1500 0 - 2000 G M E P Act Wt Nac
SHRUBS
Cajanus cajan (Linn.) Merr. Pigeon pea X X X X X
CREEPERS
Arachia pintic Krap & Greg. num. Amarillo froage X X X
nud. (Cook) peanut, Pinto
peanut
Wedelia trilobata (L.) Hitche Wedelia up to 1300asl X X X

Albizia falcataria (L.) Fosberg Molucccan sau x x x
Alnus maritima (Thumb.) Steud. Alnus x x x x
Alstonia scholaris (L) R. Br. Var. Dita x x
scholaris

Cassia spectabilis (L) Anchoan dilaw
Eucalyptus camaldulensis River red gum x x
Melia dubia Cav. Bagalunga x x
Pinus kesiya Royle ex Gordon Benguet pine x x
Spathodea campanulata Beauv. African tulip x
Serialbizia acle (Blanco) Merr Akle x
Trema orientalis (Linn.) Blume. Anabiong x x

Flemingia macrophylla (Willd.) Malabalatong x x
Merr.

Piper arborescens Palo verde x x x
Grasses
Thysanolaena maxima Tambo x

Drought Tolerance: E - Excellent Soil Conditions:
(withstands long drought period, AcT - Tolerance to
6-9 months dry season) acidic soils
M - Moderate WT
(well tolerant to extended - Wide tolerance to
drought) soil conditions
G - Good (moderately tolerant to extended dry periods) Nac - Not tolerant to acidic soils
P - Poor (requires high, evenly distributed rainfall)

25


It is worthy elaborating some of the morphological and functional mechanisms
by some of these species:

Potential Grass species

Vetiver has been the identified most promising species because of its special
features and functional versatility. Morphologically, it possesses extremely deep
and massive finely structured root system, capable of reaching down to two to
three meters in the first year (Fig. 19).

Fig. 19. Its extensive and thick root system
binds the soil and at the same
time makes it very difficult to be
dislodged an extremely tolerant
to drought.

It has stiff and erect stems which can stand up to relatively deep water
flow (0.6-0.8m). It has dense hedges when planted close together, reducing flow
velocity, diverting run-off water and forming a very effective filter. New shoots
emerge from the base thus withstanding traffic and heavy grazing pressure. It
also has the ability to regrow very quickly after being affected by drought, salt
and other adverse soil conditions when the adverse affects are removed (Fig.
20).

Fig. 20. When buried by trapped sediment,
new roots are developed from nodes
and vetiver will continue to grow with
the new ground level eventually form-
ing terraces, if trapped sediment is
not removed.

Physiologically, vetiver has tolerance to extreme climatic variation such
as prolonged drought, flood submerged and extreme temperature from 140C to
550C. It grows in a wide range of soil pH (3.0 to 10.5). It has a high level of
tolerance to soil salinity, sodiity and acid sulfate. It can also tolerate toxic levels
aluminum, manganese, arsenic, cadmium chromium, nickel, copper, mercury,
lead, selenium and zinc, on grass species.

26


After being affected by drought, salt and other poor soil conditions, it
has the ability to regrow very quickly when the adverse affects are removed
(Fig. 21).

Bambusa blumeana (tinik) is considered a rehabilitation species
because of its versatility, since it can grow either in the upland or lowland as
long as proper establishment and management techniques are followed. A study
on other bamboo species like bayog showed they are also effective in mine
tailing areas with survival rates of 99% and 97%, respectively. They are also
drought resistant and they could tolerate water logging up to 63 days.

Fig. 21. Vetiver grass turned brown
in peak summer but re-
grew when intermittent
rainfall came during the
next season (Pilot demon-
stration site at Placer,

Bamboo strips can also be used as reinforcing element for deep- seated
instability. As a material, bamboo has been found to have very high tensile
strength to weight ratio. The tensile strength is about 265-388 Mpa nearing
that of a mild steel at 480 Mpa.

In Malaysia Expressway, the use of 6 steep, bamboo reinforced
embankments with side slopes varying from 1:1.2 to 1:0.85 (v:h) along
roabdbank (Fig. 22). To date, no faulting regarding its performance; construction
cost is low than conventional reinforced soil walls.

Fig. 22. Construction of a bamboo-reinforced embankment
in progress

27


The chief drawbacks however are as follows: a) Long-term durability.
i.e. prone to attack of fungi, insects, etc. if not treated properly by chemicals; b)
variability due to non homogeneity and anisotropy, being a naturally-occurring
material (not-manufactured).

Potential Hedgerow /Live Pole Species

For slope stabilization purpose there are potential plant species with
capacity to reproduce vegetative and utilized as hedgerows or live poles:
Africa tulip (Spathodea campanulata) Kapok (Ceiba pentandra L.)
Agoho ( Casuarina equisetifolia) Katurai (Sesbania grandiflora)
Anabiong (Trema orientalis (Unn.) Blume) Macaranga gigantea
Anchoan dilaw (Cassia spectabilis Malungai (Moringa oleifera)
Bamboo (Bambusa blumeana Schult) Mangium (Acacia mangium)
Calliandra (Calliandra tetragona) Mulberry (Morus alba L.)
Calliandra calothyrsus Mulberry (Morus alba L.)
Dapdap (Erythrina Orientalis Unn) Narra (Pterocarpus indicus)
Datiles (Muntingia calabura L.) Narra (Pterocarpus indicus)
Dita (Alstonia scholaris L.) Neem (Azadirachta indica A. Juse)
Falcata (Paraserianthes falcataria) Rensonii ( Desmodium rensonii )
Flemingia (Flemingia congesta), Sunflower (Tithonia diversifolia).
Flemingia (Flemingia macrophylla) Teak (Tectona grandis Unn)
Giant Ipil-ipil ( Leucaena diversifolia) Teak (Tectona grandis Unn)
Guava (Psidium guajava J) Tubang-bakod (Jatropha curcas L.)
Gubas (Endospermum peltatum) Tubang-bakod (Jatropha curcas L.)
Ilang-ilang (Cananga odorata Lam) Vetiver (Vetiveria zizanoides)
India Bitongol (Flacourtia indica (Burm.f) Yellow dapdap (Erythrina
Merr) variagata)
Ipil-ipil (Leucaena leucocephala) Yemane (Gmelina arborea)
Kakawate (Gliricidia sepium (Jacq) Walp).

BIOREMEDIATION MEASURES
Finding Plants with Bioremediation Potential

One major task of mining industries is the management of its mining
wastes. Bioremediation is an environment-friendly technology that uses the
natural properties of plants and microbes to reduce, if not eliminate, harmful
effects of hazardous wastes in an area.

28


Phytoremediation is the ability of plants to extract, detoxify, and/or
sequester environmental pollutants from soil and water. It is one of the
technologies that use green plants to remove pollutants from the environment
and render toxic wastes harmless to living organisms.

Phytostabilization of heavy metals is also termed in place inactivation
or phytorestoration. There are different types of phytoremediation technique
that involve stabilizing heavy metals with green plants in contaminated soils, as
follows:

Types of Metal Phytoremediation
(1) phytostabilization- in which plants stabilize the pollutants in soils, thus
rendering them harmless;

(2 phytofiltration or rhizofiltration- in which plant roots grown in aerated
water, precipitate and concentrate toxic metals from polluted effluents;

(3 phytovolatilization-in which plants extract volatile metals (e.g., Hg and Se)
from soil and volatilize them from the foliage; and

(4) phytoextraction- in which heavy metal hyperaccumulators, high-biomass,
metal-accumulating plants and appropriate soil amendments are used to
transport and concentrate metals from the soil into the above–ground
shoots, which are harvested with conventional agricultural methods.

Hyper-accumulators: Are plants species that possess the ability to extract
elements from the soil and concentrate them in the easily harvested plant
stems, shoots or leaves. Some of the identified species are:
Thlaspi caerulescens (Alpine pennycress)
This plant belongs to the weedy member of
the broccoli and cabbage family. It thrives in
soils with high levels of zinc and cadmium. This
is because the plant possesses genes that
regulate the amount of metals taken up by the
roots from the soil and deposit these elements
in other parts of the plant (Fig. 23).

Fig. 23. Morphological characteristic
features of Thlaspi plant.

29


Stackhousia tyronii (Sunflower)
A hyper-accumulator plant that can
provide a cheap and ‘green’ method of
cleaning contaminated agricultural and
industrial sites. This plant can also be used
to clean pastures and croplands
contaminated by heavy metals from
fertilizer and industrial pollution (Fig.
24).The study deals on how S. tyronii takes
up metal elements from the soil and how
Fig. 24. Sunflower is easily available species the plant can survive in a toxic condition
for propogation. considering that 4% of its leaf dry-weight is
pure nickel metal. It explained further that
immediately after the nickel is absorbed, the plant root detoxify it by forming an
organo-metallic complex.

Pteris vittata (Braken fern)
Braken fern soaks up ar-
senic with staggering efficiency,
i.e. 200 times higher in the fern
than the concentrations in
contaminated soils where it was
growing (Fig. 25). In greenhouse
tests using soil artificially infused
with arsenic, arsenic
concentrations in the fern’s fronds
have reached 22,630 ppm (2.3% of Fig. 25. Braken fern possess dark green large, long
the plant comprise arsenic). leaflets compared to other ferns.

Many other ferns were identified pioneer species in mining areas (Fig.
26.) They were observed verdant and persistently growing in its rocky sites and
were acclimatized for a long time in the area.

Nitrogen-fixing plants are most suited to be planted in barren mining
and volcanic ash laden areas. They have the capability to draw freely nitrogen
from the atmosphere through the aid of nitrogen-fixing organisms (Rhizobium
and Frankia). They survive and grow normally with lesser fertilizer input. Some
of these are:

30


Narra (Pterocarpus indicus) Yemane (Gmelina arborea)
Agoho ( Casuarina equisetifolia) Ipil-ipil (Leucaena leucocephala)
Kakawate (Gliricidia sepium (Jacq) Giant Ipil-ipil ( Leucaena diversifolia)
Walp). Ipil-ipil (Leucaena leucocephala)
Anabiong (Trema orientalis (Unn.) Flemingia (Flemingia macrophylla)
Blume) Flemingia (Flemingia congesta),
Falcata (Paraserianthes falcataria) Rensonii ( Desmodium rensonii )
Mangium (Acacia mangium) Calliandra (Calliandra tetragona)
Dapdap (Erythrina orientalis) Calliandra calothyrsus
Yellow dapdap (Erythrina variagata) Anchoan dilaw (Cassia spectabilis
Kakawate (Gliricidia sepium) Ferns
Katurai (Sesbania grandiflora)

Fig. 26. Various varieties of ferns consistently thriving in almost all mined
out and mine spoils throughout the country.

Ferns are symbiotically–associated with Anabaena a nitrogen-fixing
microorganism. Its persistence in these sub-marginal conditions can be
accounted to its ability to draw nitrogen from the atmosphere.

Hibiscus cannabinus L. (Kenaf) and Brassica napus L. (Canola) were
found to be both effective in detoxifying soil and water contaminated with
selenium. These species were used to do biological clean-up of soils and water.
Kenaf also provides mats for soil erosion control while grass seeding and pads
were used to sanitize chemical and oil spills.

Mycorrhiza, a Symbiotic Microorganism with Phytoremediation Potential

There are more than 500 known species of endomycorrhiza. Fig. 27
shows various spores of various species. Mycorrhizal fungi have an
extraordinary capacity for growing, dispersing and surviving stress periods.
These abilities make them highly successful organisms despite their dependence
on plant organism for growth and reproduction. With its multifunctional
physiological capability, it can assist plants to cope up with the countless
environmental stresses, as follows:

31


• water stress
• nutrient stress ( pH, N, P nutrient, other micronutrients)
• salt stress
• toxic/heavy metals
• water
• aeration
• soil structure problems
• other biotic factors such as pathogens
• atmospheric pollutants
• elevated carbon dioxide

It has been the realization that mycorrhiza has exclusion mechanisms
i.e. it does not bring to its above-ground parts high levels of arsenic, cadmium,
chromium and mercury hence it can be a material for phytoremediation. Heavy
metal levels can be gradually reduced in the contaminated sites and can be
disposed off safely elsewhere with use of this biofertilizer. Fig. 27 explains for
the plant physiological responses to inoculation.

How the micro symbiont mycorrhiza help
respond to plant metal toxicity

Fig.27. Mechanisms of how
mycorrhiza help respond to
Better soil exploration metal toxicity.
- Improved root growth
Heavy metals - Changed root structure
accumulated in - Proteoid roots
hyphae are not
passed to host Differences in P extraction
(EXCLUSION - Phosphate solubilization
MECHANISM) - Phosphatase production

Phytochelatins Modification of rhizosphere
vacuolar - Rhizosphere acidification
accumulation citric acid, piscidic acid or
proton excretion
- Glomalin production

In the mine waste area of Antamok, Benguet, positive responses to
mycorrhizal inoculation were found in outplanted agoho (Casuarina
equisetifolia) and batino (Alstonia macrophylla) (Fig. 28 and 29).

Fig. 28. Robust batino plant in the mine waste
dump site.

32


Fig. 29. Comparative growth
performance of Agoho
(Casuarina equisetifolia)
in mine waste areas of
Itogon, Benguet.

Recently, species like Tubang bakod (Jatropha curcas) using mycorrhiza
have enhanced survival rate even under harsh conditions.

The good news is that a mycorrhizal type called vesicular-arbuscular
mycorrhiza can infect almost all vascular plants, hence it will have wide
applicability (Fig. 30). Also, the microorganism works in marginal, degraded
environment.

Fig. 30. Spores of vesicular–arbuscular (VA) mycorrhiza Glomus sp. Mycorrhiza has
been identified as a major player in removing of heavy metals in soils like
the mine waste areas.

ERDB has started producing VA mycorrhiza (endomycorrhiza) as pure
inoculants for reforestation, agroforestry and coastal rehabilitation since 2000.
It is producing more mycorrhiza from various provenances inoculants to be
tested in mine waste areas.

A mycorrhizal seedling produces 8 times as much root and hyphal
surface than ordinary uninoculated plants, absorbs 3 times more nutrients and
water from the soil, and is drought-resistant and disease-resistant than normal
plants, significantly greater survival, growth and yield, increased quality of
seedlings under stressed field conditions.

33


Vetiveria zinazoides (vetiver)

It was discussed that vetiver can tolerate toxic levels of heavy metals.
This is accounted to its symbiotic association with mycorrhiza which confines
the heavy metals to its roots. Its roots can accumulate more than five times the
chromium and zinc levels. Because of this exclusion mechanism, its shoots can
be safely grazed by animals or harvested for mulch as very little of this heavy
metal are translocated to the shoot. Heavy metal levels are gradually reduced
in the contaminated site and can be disposed off safely and elsewhere. As such,
areas contaminated with high levels of arsenic, cadmium, chromium and
mercury can be planted to vetiver.

Imperata cylindrica (Cogon)

Being proven as excluder of heavy metals Pb, Zn and Cu, the roots of
the species accumulated low levels of metals by avoiding or restricting uptake.
Shoots of the species accumulated much lower concentrations of metals by
restricting transport because they are symbiotically associated with mycorrhiza.

Microbial Remediation Potential by other microorganisms

Certain microbes are also capable of converting or transforming
pollutants and other harmful chemicals into less hazardous form or even
immobilizing them. Identified natural indigenous bacterial and fungal microbes
singly or in combination of both were converted to viable standardized bacteria
and fungi in concentrated liquid formats. One of these products is Petroclear
used for gasoline, oil, diesel, hydraulic fluid and pesticide spills.

These products are a live synergistic blend of bacteria chosen for its
ability to metabolize certain types of hydrocarbons. The bacteria feed on the
contaminants where they derive their nutrition for growth and development.
After going through complex chemical reactions, the waste is transformed into
the final metabolic waste products - water and carbon - which serve as food for
the bacteria. The consequence of this natural process is that wastes are used up
completely or converted into innocuous products like water and carbon dioxide.
Once the food source is depleted, the remaining microbes self-remediate
producing clear water without traces of hydrocarbons. Toxins and pathogens
are also eliminated.

34

A Research Compendium For Mining And Volcanic Debris-Laden Areas

A Research Compendium For Mining And Volcanic Debris-Laden Areas

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