Mammoth Water Extractor Risk Matrix

Mammoth Water Extractor

Risk Matrix-01

Frequency LevelDescriptionFrequency of Events
5Almost certain (occurs often) Expected to happenOccurs on very Blast
4Likely (known to occur) May easily happenOccurs Once a Week
3Possible (known to occur occasionally) May HappenOccurs Once a Month
2Unlikely (has occurred somewhere) May happen sometimesOccurs Once a Quarter
1Rare (could happen but unlikely)Occurs Once a Year


Severity LevelImpactHealth & SafetyBlasting Result & OutcomeLoss/Damage
5Catastrophic/Critical- Multiple Injuries
- Misfired blast
- Work on dangerous ground
- Frozen ground
- Re blast & repair cost
- Production interruption
- Penalties
>R 1.0 Mil
4Severe/Major- Single Fatality/Permanent disabilities
- Uneven broken ground removal
- Risky work environment
- Poor fragmentation
- High loading cost
- Slow production
- Secondary blasting
R.0.8 – 1.0 Mil
3Major/Moderate- Reportable injury/noise induced hearing loss
- Property damage
- Flyrock
- Property damage
- Financial loss
R 0.5- 0.8 Mil
2Moderate/Minor- Lost time injury/Health effect with reversible impairment
1Minor/Low- Medical treatment case/
Slight health effect with no impairment

Stemming Wet Holes
  1. Ensure that the stemming material is suited to the stemming length to achieve the required result
  2. Water in the stemming area will affect the effectiveness of a consolidated stemming
  3. Bottom charge all water-filled holes. This will result in water on top of the charge
  4. Remove the water and explosives gunk in the stemming length with a water extractor before stemming the hole. The hole will be dry and the stemming can affectively be consolidated.
  5. 10% aggregate is normally used when;
    - holes are situated in a pool of water
    - to ensure the optimum fragmentation in very hard rock
    - a short stemming is needed i.e., hard rock in collar area that may create slabbing.
    - no flyrock is allowed in restricted areas

Drill chippings (not fine sand) can be used effectively in dry holes as indicated below

General Stemming Chart ‐ Flyrock effect

Hole Diameterx BurdenDry Hole Graded AggregateGraded Aggregate in WaterDry Hole Drill ChippingsDrill Chippings in WaterResult ‐ Flyrock Effect
10 x Dia0.4 x BModerateHighHighExcessive
15 x Dia0.6 x BLittleModerateModerateHigh
20 x Dia0.8 x BLittle or noneLittleLittleHigh
25 x Dia1.0 x BNoneLittle/noneLittle/noneModerate
30 x Dia1.2 x BNoneNoneNoneLittle
35 x Dia1.5 x BNoneNoneNoneNone

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