Editor: We bemoan $300,000 spent considering the Southlands application and 60,000 truckloads of fill travelling 56th Street. These result in large part from B.C.'s 2012 "Final Report" concluding their look at dike heights needed to protect us from a projected one-metre sea level rise by 2100. Delta paid consultants for construction level recommendations and Century proposed the needed fill.
So, how about $1.8 billion and 600,000 loads of fill? That's the cost of dike upgrades and volume of fill needed should Delta implement all B.C.'s suggestions, which thankfully are preliminary and unenforceable.
Delta's dike crests vary from 2.8 to 4.0 metres above the Geodetic Survey base. B.C. suggests they need to be between 6.2 and 7.9 metres, an average increase of 4.0 meters.
For example, our 3.6-metre Boundary Bay dike, which as far as I know serves us well, would become 7.6 metres! Is a four-metre increase needed to protect us from one metre of sea level rise? Depends on how it's figured.
History - the worst floods in past centuries - usually determines dike height. B.C. would instead have Delta provide for the theoretical sum of extreme conditions, all occurring at the same time and dike location: subsidence, sea level rise, maximum high tide, storm surge, wind set-up and wave affects.
The result is four times that attributable to sea level rise alone, and likely a proportionately greater increase in cost. The most likely outcome, whatever that is, could be far more affordable than B.C.'s theoretical worst.
Compound this with sea level rise uncertainty. NOAA satellite altimetry reports sea level rise averaging three millimeters per year since 1992, a rate suggestive of much less than one metre increase by 2100.
Some scientists confirm or project rapid global warming caused by increased greenhouse gas, yet others report accurate temperature measurements made from weather balloons and satellites that show no atmospheric warming since 1958.
It may make sense to wait and see who's correct before Delta invests in higher dikes.
Ed Ries
