Check out some technical and specific terms about dams for a better understanding.
Areas of Influence
The areas of scope of an enterprise's environmental impacts. They are defined by
environmental analysts and are divided in two categories: Direct Influence Area – Is
geographically close to the works and the activity itself, as well as mine operations,
Indirect Influence Area – Includes a more comprehensive number of people and systems.
ANM (National Mining Agency)
Agency attached to the Ministry of Mines and Energy, which is responsible for the management
of mining activities and Brazilian mineral resources.
CECOM (Emergency Control and Communications Center)
Vale´s center, installed in Itabira (Minas Gerais), which controls the actuation of the
sirens in emergency situations.
Dams are structures designed by engineers to be used as reservoirs for containment and
accumulation of liquid substances or the mixture of liquids and solids from the process that
improves the physical and chemical qualities of ore.
Indicator for the volume of the material conditioned in the dam and its safety
Currently, there are four:
It indicates the normal status.
It indicates some instability. The 24-hour reinforced monitoring begins.
It indicates everyone shall evacuate the Self-Rescue Zone as soon as the sirens are actuated. This evacuation
procedure will be assisted by Vale and the Civil Defense.
This level indicates that the people in the Secondary Safety Zone shall
provided with assistance through educational measures and evacuation
training. These trainings are scheduled by the Civil Defense and
communicated to the local population. The sirens are also actuated to
certify that there is no one in the Self-Rescue Zone.
Watch the video to understand the definitions of dams.
Watch the video to
understand the definitions of dams levels
Dam Safety Index
Factor constantly evaluated through complex calculations to determine the safety
of a dam.
Recently, the regulatory agencies have made the criteria of this index even more
conservative, in order to increase the safety of workers and inhabitants of the
this type of operation.
Process that is part of the last phase of the decommissioning of a dam. It refers
to the treatment of a structure so that it does not present dam characteristics
and is reincorporated to the relief and the environment.
Process of ending the use of a dam permanently. At the end of the process, the
becomes stable and is reincorporated to the relief and the environment.
Displacement Monitoring via Satellite
Orbital Radar systems use surface imaging techniques in which spots of the region under
monitoring are lighted by electromagnetic waves and the reflected signal is used to
the behavior of geotechnical structures. Satellites generally use two images to measure
consecutive phase changes at identical positions and altitudes, but at different
When any displacement occurs in the dam, during the collection of the images, it can be
observed through the difference between these images. Possible soil movements can be
measured with millimetric accuracy. It is currently used in more than 70 structures at
Downstream Tailings Dam and Upstream Tailings Dam
Downstream tailings dam is the conventional construction method. The dam shell is built
on compacted soil, regardless of the type of tailings deposited. Raising is built in the
direction of the water flow (downstream).
Upstream tailings dam is the type of dam whose body is built according to the use of
tailings by means of progressive raisings on the deposited tailing. Raising is built in
the opposite direction of the water flow (upstream). The dam requires coarse tailings so
that the shell can be built.
In the dry treatment, no water (from the environment) is required for the processing of
extracted ore; thus, there is no need to build tailings dams.
In the last 10 years, Vale invested almost R$66 billion in facilities and development of
technologies for the dry iron ore processing production. Today, most of our iron ore
production (about 60%) is though dry processing. The company's goal is to reach about
Emergency Action Plan for Mining Dams
The Emergency Action Plan for Mining Dams (PAEBM, Plano de Ação de Emergência de
Mineração) is a document with guidelines on prevention and actions required in emergency
situations. It was developed by Vale and registered in public institutions.
They are instruments of regulation and control present in all phases of the environmental
licensing. These are the rules, obligations, and commitments entered into with the
environmental licensing authority at the time the environmental licenses are granted.
ETAF (Fluvial Water Treatment Station)
Water treatment station Installed at the confluence of the Ferro-Carvão stream with the
Paraopeba River. The objective of this structure, which is being tested, is to reduce the
turbidity of the water and return it to the Paraopeba river. The ETAF will be able to treat
approximately 2 million liters per hour.
Actions organized by Vale with the communities located near the dam region. These
simulate safety and evacuation procedures in emergency situations. Days and times are
previously scheduled and communicated by Vale. The objective is to make the population
of its role in case of eventual dam breach.
Company acquired by Vale on April 27, 2001, and responsible for the construction of the
dam I of Córrego do Feijão mine.
It is the picture of a region estimating effects after a dam breach. It presents the
amount of material contained in the dam through mathematical templates, possible method
for draining the material, and extent of the breach. It is calculated considering safety
factors so that, in case of a breach, the real flooding area is smaller than the
theoretical flooding area.
Geophones are sensors installed in the structures of the dams to measure the speed of
seismic waves (natural or induced). These sensors are installed at the surface of the
structures and collect the vibration waves. Based on the wave speed, the micro seismic
monitoring keeps up with the response of the dam to seismic events. They are installed
at Itabiruçu, dike 3 – Pontal, and Forquilha III dams.
Geotechnics studies the behavior of soil and rock, mostly related to changes made by men.
It is an extremely relevant phase for any construction, and can be performed by
geologists or geotechnical engineers.
Geotechnical Monitoring Center
The monitoring center founded in February 2019 to support Vale's geotechnical operations
in the Southeast region. It uses data from radars and 24-hour cameras that monitor
Vale's geotechnical structures. Using the instruments available, the geotechnical team
reads the areas, and the information is all available in the Monitoring Center, along
with the information from radars and cameras that allows Vale to monitor and make
decisions in a more secure and assertive way.
Immediate Response Group
Internal area of Vale created to ensure focus on structuring actions that involve
repairing the damages caused as well as socioeconomic and environmental recovery of
Brumadinho and affected municipalities.
Instrument that measures angular displacements of the geotechnical structure shell,
verifying the inclination by means of holes made in the structure. Three instruments
have already been installed at Vargem Grande and Doutor dams, and 234 new inclinometers
are being acquired to be installed at two dams.
The dam that does not receive waste, but keeps the characteristics of dam (deposited
This type of dam is different from those that underwent the decommissioning process; that
is, whose structure was changed to be reincorporated to the relief and the environment.
To understand the difference, watch the video.
Independent Committee for Extraordinary Advisory on Support and Recovery
The Independent Committee for Extraordinary Advisory on Support and Recovery (CIAEAR,
Comitê Independente de Assessoramento Extraordinário de Apoio e Reparação), composed
only by external members, was created by Vale to recover from the social and
environmental impacts caused by the breach of the dam from Córrego de Feijão mine, in
Brumadinho (Minas Gerais).
Independent Committee for Extraordinary Advisory on Investigation
The Independent Committee for Extraordinary Advisory on Investigation (CIAEA, Comitê
Independente de Assessoramento Extraordinário de Apuração), composed only by external
members, was created by Vale to support the Board of Directors during investigation of
the causes and possible responsibilities related to the breach of the dam from Córrego
de Feijão mine, in Brumadinho (Minas Gerais).
Independent Committee for Extraordinary Advisory on Dam Safety
The Independent Committee for Extraordinary Advisory on Dam Safety (CIAESB, Comitê
Independente de Assessoramento Extraordinário de Segurança de Barragens), composed only
by external members, was created by Vale to advise the company on issues related to
diagnosis of safety conditions, as well as management and mitigation of risks regarding
ore tailings dams, and to recommend measures to be taken for improvement of the safety
The drones are used for visual monitoring of conservation conditions of the dams,
considering the shell, crest, bottom drain, tailings beach, and extravasation channels,
among others. Several photos of the dam parts are collected, during the drone flight,
and will be analyzed later by the responsible geotechnician. Fábrica and Gongo Soco
mines are monitored by a drone, and another equipment is being acquired for the dam
National Policy for Dam Safety
The National Policy for Dam Safety (PNSB, Política Nacional de Segurança de Barragens),
established by law No. 12,334/10, is a public policy and a system for integration of the
several agencies and different federal entities in order to ensure integrity of the
as to protect the human beings who depend on them or who live in their surroundings as
as the environment.
The recovery process aimed at improving the chemical and physical properties of ore.
The vibrating wire piezometer is used to monitor the progress of piezometric pressure –
the liquid compressibility – in more difficult-to-reach areas of the structures to be
monitored. It consists of a pressure measuring device – vibrating wire type – and a
temperature measuring device. It measures the water level at the point in which is
installed. Today, the dams of Minas Gerais and Mato Grosso do Sul count on 126
(some in phase of installation). In addition, 626 piezometers are under acquisition
be installed in 35 new dams.
It is installed in front of the dam shell, and its operating principle is the emission of
electromagnetic waves. It is used to analyze the small longitudinal movements (common
all structures) at the front side of the shell. This is possible by creating multiple
sectors along the structure (pixels) and analyzing the behavior of each pixel. Radar
monitoring has fast response and millimetric accuracy. Today, there are eight devices
operating at Forquilha III, Mar Azul, Vargem Grande, Gongo Soco, B6, and MAC B5 dams.
Robotic stations complement the radar monitoring.
The construction method to increase the storage capacity of a tailings dam. Several
methods of raising can be used.
Secondary Safety Zone
The Secondary Safety Zone (ZSS, Zona de Segurança Secundária) is the region beyond 10km
minutes from the dam breach point. If the dam breaches, there is enough time for the
people to act for their own rescue and go to the meeting points for assistance. The
points are informed during the trainings conducted by the Civil Defense.
The Self-Rescue Zone (ZAS, Zona de Autossalvamento) is the region up to 10km or 30 minutes
from the dam breach point.
People are responsible for their own rescue. They must get out of the flooding area and go
to a safe zone on her own.
To learn more, watch the video.
Slope is a generic technical term for any sloping surface that delimits a mass of soil, rock
or other material
(ore, slag, barren, rubbish, etc.). Slopes can be natural, when they are formed by nature
without human interference,
or artificial, formed by embankments or modified by works.
In the specific case of mines, slope is the hillside that give support to the pit.
Stability Condition Statement
Document that certifies the safety of a dam. Under current legislation, the signers of
this document are the engineers who work in specialized companies hired for the
To learn more, watch the video.
It is the waste from the recovery process aimed at improving the chemical and physical
properties of ore. It is composed of iron ore, sand, and water. It is not toxic,
Tailings Impoundment Membrane
The structure installed in the Paraopeba river acts as a filtering fabric to prevent the
dispersion of the solid particles – such as clay, silt, and organic matter – that cause
turbidity of the water and change its transparency. For a better understanding, watch
Mixture of water and high concentration of suspended solids carried by the watercourse.
It is a physical property of liquids that reduces transparency due to the presence of
suspended material that affects the path of light through the fluid.
A method that uses cameras with remote-drive zoom and movement resources for full-time
monitoring (24x7). The infrared ray feature also enables the analysis of night images.
Images from video monitoring cameras are sent to a hub device and kept recorded for a
minimum of 90 days. Currently, there are 86 monitoring devices at Vale's iron ore dams
Brazil. The use of artificial intelligence with the cameras for movement analysis is
Inspections in which the technician goes to the area and checks for cracks or any
indication that the dam is not under the conditions required to operate.
It aims at improving the chemical and physical properties of run of mine (ROM). The material
from the mine goes through this process (which uses water) and generates as waste a material
called tailings. This waste is disposed of in dams.