Page 348 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

Table 5 Overall Impact Probabilities for Cases 3 and 4
Overall Impact Probabilifv*
~~
Estimated Annual
leak probability**
count for Probability of ofone or Annual
Average leak 700 miles one or more more impcts Probabilifv changes
rateper and impacts over over life qf changes in in a
Case f. mile-year 50 yeam Impact lfe ifproject project a thousand thousand Notes
3 Pre-mitigation 0.001991 69.1 Drinking water 20.9% 0.47% 209 4.68
leak rate contamination
estimate
Fatality 13.1% 0.28% 131 2.81 2
Injury 46.9% 1.26% 469 12.6 2
Recreational water 91.4% 4.79% 914 47.9
contamination
Prime agricultural 60.4% 1.8% 604 18.36
land
contamination
Wetlands 76.4% 2.84% 764 28.4
contamination
4 Post-mitigation 0.000073 2.6 Drinking water 0.5% 0.010% 5.10 0.1 02
leak rate contamination
estimate Drinking water 0.3% 0.005% 2.55 0.051
contamination, no
MTBE
Fatality 0.5% 0.01 1% 5.25 0.105 2
Injury 2.3% 0.047% 23.38 0.473 2
Recreational water 8.3% 0.17% 83.20 1.736
contamination
Prime agricultural 3.5% 0.070% 34.50 0.702
land
contamination
Wetlands 4.9% 0.10% 49.42 1.013
contamination
LakeTravis water 0.02% 0.0004% 0.19 0.004 4
supply
contamination
Edwards Aquifer 0.02% 0.0004% 0.19 0.004
water
contamination
'Overall impact probability is probability of one or more events in 50 years over 700 miles.
"Overall impact probability, annual, is probability of one or more events in 1 year over 700 miles.
Notes:
1 26 leaks (some less than 50 bbl) over450 miles in 29 years.
2 Fatality and injury rates are based on DOTfatality and injury rates per reportable leak, applied to 700 miles.
3 Leak estimate is for any leak, including <50 bbl; approximate leak count for 50 bbl (reportable) = 1 in 50 years.
4 Pedernales watershed.