CITY OF PRINCE GEORGE WELLS PROTECTION PLAN

March 2015
City of Prince George Well Protection Plan
In addition, it would be important to update the numerical flow model to assess the capture zones specifically
in the vicinity of the CN rail tracks, once actual groundwater and surface water levels in these two areas have
been monitored. Given that models are based on assumptions, an independent review of the numerical model
may also be prudent.
Further, it is necessary to evaluate potential mitigation options such as interceptor wells vs lined trench
protective measures in conjunction with the groundwater hydrogeological models for PW660, PW605, and
PW601. These studies would assure the most effective measures are selected and costs are appropriately
quantified.
Defining risks related to CN spill incidents beyond the City’s boundaries are outside the scope of this
assignment. A further assessment by hydrogeologists of the potential risks due to a rail spill into the Nechako
River upstream of the City may have merit due to the speed with which contaminants could be transported into
the City’s aquifer by this point of entry.
4.2 Preventative Measures
Benjamin Franklin once said, “An ounce of prevention is worth a pound of cure.” This is especially true when
dealing with aquifer contamination. A municipality faced with a compromised well can look forward to
exorbitant clean-up bills (with minimal financial support from other levels of government), loss of public
confidence in both the water supply and decision makers, long-term temporary or permanent loss of the
affected well(s), and potential health and environmentally-related legal action.
In a worst case scenario, the City could lose the entire aquifer and all its related wells. DNAPL contaminated
sites for example, which are discussed in An Introduction to Characterizing Sites Contaminated with DNAPLs
(ITRC, 2003) have one of the biggest challenges in the field of environmental remediation because DNALPs:
behave in an relatively unpredictable fashion as they are effected by minute variations in subsurface
pore size distributions, soil texture, soil structure, and mineralogy
often go undetected with standard investigation techniques such as soil borings and monitoring wells
some investigation measures can expand the zone of chemical contamination or develop misleading
chemical concentration data
typically require very small concentrations to render water ‘unsafe’
can become more soluble in water over time, and thus, more toxic
migrate through the subsurface under the influence of gravity and capillary effects so that they can be
present in different places than would be expected by simple groundwater mapping
often require costly remediation
Fortunately, there are a wide variety of preventative measures which can be put into place to mitigate the risk
of a derailment or collision-related spill:
Installation of Interceptor Wells & Trenches
Interceptor wells and lined trenches can be used to prevent the migration of contaminants into and within an
aquifer. The efficiency of either method depends upon:
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