Principal environmental impacts on pipeline tracks as a result of mining operations and their mitigated actions

Ferreira, Gilda Carneiro; Chang, Maria Rita Caetano; Lemos, Cássia Maria Gama

doi:10.1590/0370-44672015690152

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Mining • Rem: Rev. Esc. Minas 69 (2) • Apr-Jun 2016 • https://doi.org/10.1590/0370-44672015690152 copy

Principal environmental impacts on pipeline tracks as a result of mining operations and their mitigated actions

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

This study deals with the main environmental impacts and possible mitigation measures for many pipeline tracks, due to the mining of different substances in areas of interference between mining activities and mineral research and those resulting from construction and gas pipeline operation. By monitoring the identified interferences/disturbances, it was determined that although punctual and small in number, the extraction of mineral resources in the proximity of the gas pipelines could represent risks for the security of the undertaking. In general the risks are consequence either of the use of explosives or of induced erosive processes that could lead to pipeline instability. It is necessary to block the mining activities on both sides of the pipeline tracks in order to minimize risks to the pipeline, to others, to society, and to the environment. Also, the establishment of "flexible" track limits could be adopted in areas adjacent to the pipelines for the exploration of some mineral deposits, thus prioritizing security preservation with a minimum of socio-environmental impacts.

Keywords:
gas pipeline; mineral extraction; environmental disturbance

SUBSTANCE	MINING METHOD	AVERAGE BENCH HEIGHT	MONITORING PROCEDURE
Coal	Underground, room and pillars (with and without pillar retraction)	-	Watching for surface features that are indicative of ground sinking. Measurement of ground vibration levels.
Clay	Open-pit mining, multiple benches	4 m	Monitoring of the security strip for its preservation during mining advancement. Monitoring of the slope stability.
Clay	Strip mining	Average of 1 m to 2.5m	Monitoring of the security strip for its preservation during mining advancement. Monitoring of the slope stability and new transportation routes.
Sand	Dredging	1 m to 5 m	Monitoring of the mining procedures to inhibit them along the gas pipeline track. Watching for eventual exposition of the pipeline in the river bed.
Sand	Dredging (into submersed pit)	2 m to 10 m	Monitoring of the security strip for its preservation during mining advancement. Observation of the slope stability and new transportation routes.
Sand	Open-pit mining, single bench	1 m to 1.5m	Monitoring of the security strip preservation during mining advancement. Monitoring of the slope stability and new transportation routes.
Gravel	Strip mining	4 m	Monitoring of the security strip for its preservation during mining advancement. Monitoring of the slope stability and new transportation routes.
Gravel	Strip mining at the river bed	1 m to 5 m	Monitoring of the security strip for its preservation during mining advancement. Watching for river margin stability.
Gems: fluvial alluvium	Open-pit mining at the river bed or along their margins	1 m to 3 m	Monitoring of the mining advancement for slope stability.
Grit	Open-pit mining, multiple benches	10m to 15m	Monitoring of the security strip for its preservation during mining advancement. Monitoring of the slope stability. Measurement of ground vibration level caused by blasting when using explosives.
Limestone	Open-pit mining, multiple benches	10m to 15m	Measurement of ground vibration levels.
Granite/Gneiss Diabase/Basalt (Rocks for crushing)	Open-pit mining, multiple benches	10m to 20m	Measurement of ground vibration levels. Monitoring of the slope stability at the work-front for extractions positioned above the pipeline track.
Granite (Dimension stone)	Quarrying	4 m to 6 m	Measurement of ground vibration levels. Monitoring of the advancement of the extraction fronts that are generally scattered on the site. Monitoring of the slope stability and new transportation routes.
Granite (Hewn stones)	Open-pit mining, cut in blocks	1 m to 5 m	Measurement of ground vibration levels. Monitoring of the advancement of the extraction fronts that are generally scattered on the site. Monitoring of the slope stability and new transportation routes.
Mineral water	Spring water extraction	-	Flow measurement at the spring. Chemical and biological analysis of the mineral water.

SUBSTANCE	MINING METHOD	ENVIRONMENTAL IMPACTS	MITIGATING ACTIONS
Coal	Underground, room and pillars (with and without pillar retraction)	Reduction of the shaft ceiling could cause sinking of the ground in mines with pillar retraction. Vibration due to blasting for disassembling the ore and host rock.	Pillar maintenance. Use of non-electric initiators and delays for reducing vibrations. Vibration levels cannot be higher than those determined in the specific study in accordance with ABNT standards.
Clay	Open-pit mining, multiple benches	Alteration of the ground topography could induce erosive processes. Exposure of the water table and vegetation removal.	Establishment of a strip blocking the mining activity on both sides of the pipeline track. Remodeling, stabilizing and revege-tation of the lateral slopes (Environmental entities recommend an inclination of 1:2.5). Implantation of the drainage network.
Clay	Strip mining	Generation of irregular pits with exposure of the water table and vegetation removal.	Remodeling, stabilizing and revegetation of the lateral slopes; recuperation of the pits (Environmental entities recommend an inclination of 1:1 for slopes and a maximum pit depth of 2.5 m). Reinforcement of the pipes at crossings with the transportation route.
Sand	Dredging	Riverbank erosion, deepening of the ditch with eventual exposure of the pipeline and downstream silting. Vegetation removal and destabilization of the river banks.	Execution of the extraction at a minimum distance from the pipelines tracks and river banks, preserving their stability. Revegetation and execution of the erosion contention works. Establishment of a strip blocking the mining activity on both sides of the pipeline track (strip width must be determined in a specific study, in accordance with ABNT standards).
Sand	Dredging (into submersed pit).	Formation of flooded pits with varied dimensions (depth depending on the ore thickness). Erosion acceleration of the pit borders. Vegetation removal.	Inclination of 30% in the first 5 m to 10 m of the pit; maximum height of the embankment of the pit = 10 m; minimum distance of 25 m to 50 m between the pits and the property borders. Establishment of a strip blocking the mining activities along both sides of the pipelines.
Sand	Open-pit mining, single bench	Vegetation removal, topographic lowering with localized exposure of the water table. Formation of flooded pits. Localized destabilization of the lateral slopes along the pipeline tracks.	Revegetation and erosion contention works on the slopes close to pipeline tracks. Reinforcement of the pipelines crossing transportation routes. Slope rest angle of approximately 30º.
Gravel	Strip mining	Formation of flooded pits with varied dimensions. Water table exposure and vegetation removal.	Remodeling, stabilizing and revegetation of the lateral slopes; recuperation of the pits (Environmental entities recommend an inclination of 1:2 for slopes and a maximum pit depth of 2 m). Establishment of a strip 15 m wide blocking mining activities along both sides of the pipelines.
Gravel	Strip mining at the river bed	Modification of the geometry of the river bed. Vegetation removal.	Mining must be executed at a minimum distance from the river banks, depending on the width of the river. River banks must be stabilized. Establishment of a strip 15 m wide blocking the mining on both sides of the pipeline.
Gems: fluvial alluvium	Open-pit mining, at the river bed or along their margins	Generation of irregular pits with water table exposure. Vegetation removal.	Remodeling, stabilizing and revegetation of the lateral slopes (Environmental entities recommend an inclination of 1:2.5). Construction of dams to preserve the water quality.
Grit	Open-pit mining, multiple benches	Modification of local topography accelerating erosive processes. Generation of ground vibration due to blasting for the extraction of massive rocks.	Stabilization of marginal mining slopes (inclination consistent with type of terrain) and revegetation. Use of non-electrical initiators and delays to reduce vibration.
Limestone	Open-pit mining, multiple benches	Modification of local topography accelerating erosive processes. Generation of ground vibration due to blasting for the extraction of massive rocks.	Stabilization of the mining slope. Utilization of delays along the entire blasting line and non-electrical initiators for vibration reduction. Establishment of a security strip as per the specific study of the vibration levels, in accordance with the ABNT standards.
Granite/Gneiss Diabase/Basalt (Rocks for crushing)	Open-pit mining, multiple benches	Generation of ground vibrations due to blasting for the extraction of massive rocks accelerates erosive processes close to the pipeline track. Transportation routes could cross the pipeline track.	Utilization of delays along the complete line of blasting and non-electric initiators for vibration reduction. Stabilizing mining slope near the pipelines. Reinforcement of the pipelines at transportation crossing routes. Establishment of a security strip, which width must be determined by a specific study of the vibration levels in accordance with ABNT standards.
Granite (Dimension stone)	Quarrying	Acceleration of surface erosional processes. Production of a large amount of mining waste and removal of local vegetation. Production of ground vibrations due to low-intensity blasting using gunpowder to extract rock mass. Transportation routes that could cross the pipeline track.	Stabilization of the mining areas. Burying the mining waste and revegetation of the area. Reinforcement of the pipelines at the crossings with the transportation route. Vibration measurements in the case explosives must be done.
Granite (hewn stones)	Open-pit mining (cut in blocks)	Acceleration of surface erosional processes. Production of a large amount of waste. Removal of local vegetation. Generation of ground vibrations due to low-intensity blasting using gunpowder to extract rock mass. Transportation routes that could cross the pipeline track.	Stabilization of the mining areas. Burying the mining waste and revegetation of the area. Reinforcement of the pipelines at crossings with the transportation routes.
Mineral water	Spring water extraction	The water exploitation site and the protection area of the spring should not interfere with the pipeline track. The construction of the pipeline could impact the spring water, changing it recharge and modifying the water quality.	Perform a hydrogeological study before the construction of the pipeline track. Monitoring the spring conditions (flow, water quality) for a period not less than one year.

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[TFN01] Source: modified from Ferreira (2011)FERREIRA, G.C. Interferências ambientais e legais entre atividades minerárias e a implantação e operação de gasodutos. Rio Claro: Universidade Estadual Paulista Júlio de Mesquita Filho, 2011. 107 p. (Tese de Livre-Docência).