Page 191 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

7/168 Leak impact Factor
necessary. A working definition by which most people would shown in Table 7.22 are taken from Ref. [20], which in turn
recognize a sensitive area might suffice. Such a working defini- modified the National Oceanic and Atmospheric Administration
tion would need to address rare plant and animal habitats, frag- (NOAA) Guidelines for Developing Environmental Sensitiviv
ile ecosystems, impacts on biodiversity, and situations where Index (ESr) Atlases and Databases (April 1993), other NOAA
conditions are predominantly in a natural state, undisturbed guidance for freshwater environments, and FWS National
by man. To more fully distinguish sensitive areas, the definition Wetlands Research Center.
should also address the ability of such areas to absorb or In spills over water, the spilled materials behavior is critical in
recover from contamination episodes. determining the vulnerability of the water biota and the potential
The environmental effects ofa leak are partially addressed in migration of the spill to sensitive shorelines. Table 7.19 relates
theprodud hazard score. The chronic component of this value some properties of spilled substances to their expected behavior
scores the hazard potential of the product by assessing charac- in water. This can be used to develop a scoring protocol for
teristics such as aquatic toxicity, mammalian toxicity, chronic offshore product dispersion based on the material’s properties.
toxicity, potential carcinogenicity, and environmental persist- (See also Chapter 12 for offshore pipeline risk assessments.)
ence (volatility, hydrolysis, biodegradation, photolysis). When As an example of an assessment approach, an evaluation of a
the RQ score is above a certain level, the pipeline surroundings gasoline pipeline in the United Kingdom identified, weighted,
might need to be evaluated for environmental sensitivity. and scored several critical factors for each pipeline segment.
Liquid spills are generally more apt to be associated with The environmental rating factors that were part of the risk
chronic hazards. The modeling of liquid dispersions is a very assessment included
complex undertaking and is approximated for risk modeling
purposes. Landcovertype
Areas more prone to damage andor more difficult to reme- Distance to nearest permanent surface water
diate can be identified and included in the risk assessment, Required surface water quality to sustain current land use
Since the RQ definition includes an evaluation of environmen- Conservation value
tal persistence, spills of substances whose chronic component, Habitat preserves
RQ, is greater than 3 are normally the types ofproducts that can Habitats with longer lived biota (woods, vineyards,
cause contamination damage. The threshold value of RQ 2 3 orchards, gardens)
eliminates most gases and includes most non-HVL hydrocar- Slope
bon substances transported by pipelines. Some exceptions Groundwater
exist, such as H,S where the chronic component is 6 and yet the Rock type and likelihood of aquifer
environmental impact of an H,S leak may not be significant. Permeability
The evaluator should eliminate from this analysis substances Depth to bedrock
that will not cause environmental harm. Accumulation effects Distance to groundwater extraction points.
such as greenhouse gas effects may need to be considered in
environmental sensitivity scoring. This assessment included consideration of costs and diffi-
In the United States, a definition for high environmental sen- culties associated with responding to a leak event. Points were
sitivity includes intake locations for community water systems, assigned for each characteristic and then grouped into qualita-
wetlands, riverine or estuarine systems, national and state parks tive descriptors (low, moderate, high, very high) [%I.
or forests, wilderness and natural areas, wildlife preservation Another example of assessing environmental sensitivities is
areas and refuges, conservation areas, priority natural heritage shown in Appendix E
areas, wild and scenic rivers, land trust areas designated critical
habitat for threatened or endangered species and federal and D3. High-value areas
state lands that are research natural areas [8 11. These area labels
fit specific definitions in the US. regulatory world. In other For both gas and liquid pipelines, some areas adjacent to a
countries, similar areas, perhaps labeled differently, will no pipeline can be identified as “high-value” areas. A high-value
doubt exist. area (HVA) can be loosely defined as a location that would suf-
Shorelines can be especially sensitive to pipeline spills. fer unusually high damages or generate exceptional conse-
Specifically for oil spills, a ranking system for impact to shore- quences for the pipeline owner in the event ofa pipeline failure.
line habitats has been developed for estuarian (where river cur- In making this distinction, pipeline sections traversing or other-
rents meet tidewaters), lacustrine (lake shorelines), and riverian wise potentially exposing these areas to damage should be
(river banks) regions. Ranking sensitivity is based on the scored as more consequential pipeline sections. HVAs might
following [20]: also bring an associated higher possibility of significant legal
costs and compensations to damaged parties. Characteristics
Relative exposure to wave, tidal, and river flow energy that may justify the high value definition include the following:
Shoreline type (rocky cliffs, beaches, marshes)
Substrate type (grain size, mobility, oil penetration, and Higher proper@ values. A spill or leak that causes damages
trafficability) in areas where land values are higher or more expensive
Biological productivity and sensitivity. structures are prevalent will be more costly to repair or
replace. Another example of this might be agricultural land
The physical and biological characteristics of the shoreline where more valuable crops or livestock could be damaged,
environment, not just the substrate properties, are ideally and especially where such damage precludes the use of the
used to gauge sensitivity. Many of the environmental rankings area for some time.