Integrated hydrogeological andenvironmental restoration of landslidesaffecting a large asbestos mine dry tailingsdumpFranc...
Width 800 mHeight 200 – 250 mEstimated Volume 50-60 Mm3Slope 35 – 45 degrees
The site was recognized as one of the most serious environmentalissues of Italy.-deep seatedinstabilities-erosion gullies-...
Two communities with about 10,000 inhabitants wereunder the influence of the dust plumes.An international contest was orga...
The restoration project had to consider numerous other global and sometimescompeting objectives:- Minimize dusting.- Limit...
The Team recognized that:Designs based on codes or recommendations maydiffer quite significantly from designs based on Ris...
EXAMPLE: using anaerial tramway tohaul waste material,rather than trucks.It is important torecognize thatalternatives risk...
The 4.5 km of dirt tracks between the top and the toe of theslope were a potential source of dusting and large carbonfootp...
Slope stability control procedures:- Unloading of the crest of the dump slope by diggingthree, 10 m wide benches and by st...
Runoff control procedure:Deep gullies, had formed in the upper part of the slope.- Overall runoff controlthrough a network...
Re-vegetationThe reforestation/re-vegetation of the area was amajor challenge within the project due to thescarcity of nut...
The reforestation process was intensely monitored and scrutinized. By the end of theworks, the first trees and shrubs, hyd...
Risk Based Decision Making (RBDM) procedures at everystep of the design process were used to develop thebest engineering d...
The integration of geotechnique, hydraulics, pedology and risk management withinthe designers’ multidisciplinary group led...
Integrated hydrogeological and environmental restoration of landslides affecting a large asbestos mine dry tailings dump F...
Width 800 m           Height 200 – 250 m           Estimated Volume 50-60 Mm3           Slope 35 – 45 degrees10/11/11     ...
The site was recognized as one of the most serious environmentalissues of Italy.-deep seatedinstabilities-erosion gullies-...
Two communities with about 10,000 inhabitants wereunder the influence of the dust plumes.An international contest was orga...
The restoration project had to consider numerous other global and sometimescompeting objectives:- Minimize dusting.- Limit...
The Team recognized that:Designs based on codes or recommendations maydiffer quite significantly from designs based on Ris...
EXAMPLE: using anaerial tramway tohaul waste material,rather than trucks.It is important torecognize thatalternatives risk...
The 4.5 km of dirt tracks between the top and the toe of theslope were a potential source of dusting and large carbonfootp...
Slope stability control procedures:- Unloading of the crest of the dump slope by diggingthree, 10 m wide benches and by st...
Runoff control procedure:Deep gullies, had formed in the upper part of the slope.- Overall runoff controlthrough a network...
10/11/11   11
10/11/11   12
Re-vegetationThe reforestation/re-vegetation of the area was amajor challenge within the project due to thescarcity of nut...
The reforestation process was intensely monitored and scrutinized. By the end of theworks, the first trees and shrubs, hyd...
Risk Based Decision Making (RBDM) procedures at every           step of the design process were used to develop the       ...
The integration of geotechnique, hydraulics, pedology and risk management withinthe designers’ multidisciplinary group led...
Balangero asbestos mine dumps restoration a few years after, in the aftermath of quinn storm and rolf medicane events
Balangero asbestos mine dumps restoration a few years after, in the aftermath of quinn storm and rolf medicane events
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Balangero asbestos mine dumps restoration a few years after, in the aftermath of quinn storm and rolf medicane events

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The Balangero asbestos open pit mine, located 35km NW of Torino (Italy), was the largest operation of this kind in Western Europe. The dry tailings were lifted by a conveyor belt from the mill and dumped over a natural slope with an approximate angle of 25 degrees, progressively reaching a maximum thickness estimated at 80 m.

By the '80s the dump was deeply scarred by various local and large scale instabilities, to the point that houses located at the toe, on the opposite side of the valley, were evacuated.

The award winning restoration project used a multidisciplinary approach including hydraulics, geotechnical, pedological and risk engineering to yield a well balanced and sustainable solution. This paper illustrates the Risk Based Decision Making (RBDM) process used through the feasibility, design and construction follow-up of the environmental restoration of the 60 Mm3 dry Balangero asbestos tailings dump.

The slopes were hit by storm Quinn and Medicane Rolf and came out unscathed. That was after surviving heavy summer storms in 2010 and 2011.

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Balangero asbestos mine dumps restoration a few years after, in the aftermath of quinn storm and rolf medicane events

  1. 1. Integrated hydrogeological andenvironmental restoration of landslidesaffecting a large asbestos mine dry tailingsdumpFranco Oboni, Riskope International, Vancouver, CanadaCesar Oboni, Riskope International, Vancouver, CanadaClaudio Angelino, Polithema srl, Turin, ItalyBartolomeo Visconti, Polithema srl, Turin, Italy
  2. 2. Width 800 mHeight 200 – 250 mEstimated Volume 50-60 Mm3Slope 35 – 45 degrees
  3. 3. The site was recognized as one of the most serious environmentalissues of Italy.-deep seatedinstabilities-erosion gullies-mud slidesetc...Leading to theevacuation ofhouses locatedat the toe, onthe oppositeside of thevalley.
  4. 4. Two communities with about 10,000 inhabitants wereunder the influence of the dust plumes.An international contest was organized by the “owner”of the project, i.e. an agency named RSA.Our team recognized two main objectives had to bemet:a) limiting the volume of earth movements andb) reducing the overall costs of the restoration tomatch stringent financial limitations imposedby RSA’s budget.
  5. 5. The restoration project had to consider numerous other global and sometimescompeting objectives:- Minimize dusting.- Limit air pollution.- Control the geotechnical stability of a large area.- Control the area water runoff guiding collected water across steep cross slopes.- Give strong and immediate support to new vegetation on sterile soils.- Limit the use of concrete/steel or any other artificial material given the sensitivelocation of the site at the footsteps of the Alps, in a visible, densely inhabited area.
  6. 6. The Team recognized that:Designs based on codes or recommendations maydiffer quite significantly from designs based on RiskBased Decision Making (RBDM).Differences may go as deep as choosing a differentmaterial hauling system, a different drainage patternetc.Alternatives which are perfectly code-compliant andrequire the same investments and maintenance mayexpose the owner to totally different levels of risk allalong their expected life.
  7. 7. EXAMPLE: using anaerial tramway tohaul waste material,rather than trucks.It is important torecognize thatalternatives risksmay have verydifferent time frames,which is taken intoaccount by CDA/ESM
  8. 8. The 4.5 km of dirt tracks between the top and the toe of theslope were a potential source of dusting and large carbonfootprint, given the need for a fleet of small tonnage trucks.Thus, hauling trucks wereultimately discarded becauseof environmental risks:-pollution from exhausts,-fibres dispersion from theexcavated material-need to upgrade the existingtracks-extra costs for ancillarytemporary structures).
  9. 9. Slope stability control procedures:- Unloading of the crest of the dump slope by diggingthree, 10 m wide benches and by storing the resultingmaterial at the valley bottom in an 8 m high fill.-Cutting a series of eight, 2.5 m wide, “path-waysberms” across the slope, each about600 m long.
  10. 10. Runoff control procedure:Deep gullies, had formed in the upper part of the slope.- Overall runoff controlthrough a network of small“horizontal” wooden channels,50 to 100 cm wide.- Transfer of the collectedwater towards the toe of theslope using four main “vertical”channels located along theslopes
  11. 11. Re-vegetationThe reforestation/re-vegetation of the area was amajor challenge within the project due to thescarcity of nutrient materials in the sterile soil ofthe dump.Good re-vegetation was a significant projectobjective and critical to overall dump stability.
  12. 12. The reforestation process was intensely monitored and scrutinized. By the end of theworks, the first trees and shrubs, hydroseeding had already undergone 3 or 4vegetative seasons and allowed a “real time” control of the success of the operation. Intotal the re-vegetation effort included: 450,000 m2 of hydro-seeding, 15,000 shrubs,7,300 trees and 267,000 live cuttings.
  13. 13. Risk Based Decision Making (RBDM) procedures at everystep of the design process were used to develop thebest engineering design in terms of technical results andbudget limitations.
  14. 14. The integration of geotechnique, hydraulics, pedology and risk management withinthe designers’ multidisciplinary group led to a well-balanced and environmentallysustainable project allowing the gradual recovery through natural processes of anotherwise highly compromised area.
  15. 15. Integrated hydrogeological and environmental restoration of landslides affecting a large asbestos mine dry tailings dump Franco Oboni, Riskope International, Vancouver, Canada Cesar Oboni, Riskope International, Vancouver, Canada Claudio Angelino, Polithema srl, Turin, Italy Bartolomeo Visconti, Polithema srl, Turin, Italy10/11/11 1
  16. 16. Width 800 m Height 200 – 250 m Estimated Volume 50-60 Mm3 Slope 35 – 45 degrees10/11/11 2
  17. 17. The site was recognized as one of the most serious environmentalissues of Italy.-deep seatedinstabilities-erosion gullies-mud slidesetc...Leading to theevacuation ofhouses locatedat the toe, onthe oppositeside of thevalley. 10/11/11 3
  18. 18. Two communities with about 10,000 inhabitants wereunder the influence of the dust plumes.An international contest was organized by the “owner”of the project, i.e. an agency named RSA.Our team recognized two main objectives had to bemet:a) limiting the volume of earth movements andb) reducing the overall costs of the restoration tomatch stringent financial limitations imposedby RSA’s budget. 10/11/11 4
  19. 19. The restoration project had to consider numerous other global and sometimescompeting objectives:- Minimize dusting.- Limit air pollution.- Control the geotechnical stability of a large area.- Control the area water runoff guiding collected water across steep cross slopes.- Give strong and immediate support to new vegetation on sterile soils.- Limit the use of concrete/steel or any other artificial material given the sensitivelocation of the site at the footsteps of the Alps, in a visible, densely inhabited area. 10/11/11 5
  20. 20. The Team recognized that:Designs based on codes or recommendations maydiffer quite significantly from designs based on RiskBased Decision Making (RBDM).Differences may go as deep as choosing a differentmaterial hauling system, a different drainage patternetc.Alternatives which are perfectly code-compliant andrequire the same investments and maintenance mayexpose the owner to totally different levels of risk allalong their expected life. 10/11/11 6
  21. 21. EXAMPLE: using anaerial tramway tohaul waste material,rather than trucks.It is important torecognize thatalternatives risksmay have verydifferent time frames,which is taken intoaccount by CDA/ESM 10/11/11 7
  22. 22. The 4.5 km of dirt tracks between the top and the toe of theslope were a potential source of dusting and large carbonfootprint, given the need for a fleet of small tonnage trucks.Thus, hauling trucks wereultimately discarded becauseof environmental risks:-pollution from exhausts,-fibres dispersion from theexcavated material-need to upgrade the existingtracks-extra costs for ancillarytemporary structures). 10/11/11 8
  23. 23. Slope stability control procedures:- Unloading of the crest of the dump slope by diggingthree, 10 m wide benches and by storing the resultingmaterial at the valley bottom in an 8 m high fill.-Cutting a series of eight, 2.5 m wide, “path-waysberms” across the slope, each about600 m long. 10/11/11 9
  24. 24. Runoff control procedure:Deep gullies, had formed in the upper part of the slope.- Overall runoff controlthrough a network of small“horizontal” wooden channels,50 to 100 cm wide.- Transfer of the collectedwater towards the toe of theslope using four main “vertical”channels located along theslopes 10/11/11 10
  25. 25. 10/11/11 11
  26. 26. 10/11/11 12
  27. 27. Re-vegetationThe reforestation/re-vegetation of the area was amajor challenge within the project due to thescarcity of nutrient materials in the sterile soil ofthe dump.Good re-vegetation was a significant projectobjective and critical to overall dump stability. 10/11/11 13
  28. 28. The reforestation process was intensely monitored and scrutinized. By the end of theworks, the first trees and shrubs, hydroseeding had already undergone 3 or 4vegetative seasons and allowed a “real time” control of the success of the operation. Intotal the re-vegetation effort included: 450,000 m2 of hydro-seeding, 15,000 shrubs,7,300 trees and 267,000 live cuttings. 10/11/11 14
  29. 29. Risk Based Decision Making (RBDM) procedures at every step of the design process were used to develop the best engineering design in terms of technical results and budget limitations.10/11/11 15
  30. 30. The integration of geotechnique, hydraulics, pedology and risk management withinthe designers’ multidisciplinary group led to a well-balanced and environmentallysustainable project allowing the gradual recovery through natural processes of anotherwise highly compromised area. 10/11/11 16

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