By Dan May
On Our Land
Dan May
News coverage of recent extreme weather events in southwest Connecticut, western North Carolina and central Florida prompted my wife to ask me if our home in Orange would be “safe” in similar events. She has taught introductory meteorology in the past, so her question was not specifically weather-related, but concerned more with our home’s location and any potential risk from wind, flooding and landslides.
We have much sympathy for victims of storm events, in part because we suffered through two major property losses when we lived in Ohio. A wind- and hailstorm destroyed our roof, siding and a few windows, as well as hammered our new car. A few years later, a 100-year downpour led to widespread flash- and river-flooding, filled our basement with sewer-line backup, and shut the city down for a week.
My most vivid memories of those events are not the lost dollars, but the image of household storm debris piled everywhere along with the pervasive stench of sewage and mildew. There was also the protracted aggravation of cleanup, restoration and insurance claims and disputes. It will be many months before this year’s storm victims will be at ease, and even then, emergent mold and other recurring hazards will cause concern.
When we came to Connecticut and looked for a home in Orange, physical setting was as important as a house’s architectural features. To us “location, location, location” meant nothing near a stream or river that would be within its 500-year floodway; no ridgeline setting exposed to prevailing wind; no large trees near the house; and no evidence of slope movement. I probably drove our realtor crazy, and she said I was about the only person who ever walked around a house outside before going inside.
Weather hazards naturally can occur anywhere, but location as well as structural design (and drainage) affect the overall risk level and likelihood of major damage. We ultimately found a nice home on the leeward east side of Turkey Hill Preserve, set on a well-graded excavated bedrock building pad about 60 feet below the ridgeline, and about 80 feet above the closest stream. Built by a structural engineer, too. Rainfall and wind are not likely to be a problem for us in up to 500-year events as we also are vigilant in maintaining tree setbacks.
Most building designs and related zoning restrictions are based on the expectation that a dwelling should withstand what is known as a 100-year event. Such an event is based on historical records and is so named by having a probability of occurrence of 1 percent in any given year. A 500-year event reduces the annual probability down five-fold to 0.2 percent. Since storms in recent decades have become increasingly severe compared to earlier records in actuarial use, published 100-year estimates currently underestimate hazards. Add in our misfortune in experiencing two 100-year events in three years, and we opted for a lower-risk site location and premier homeowner’s insurance. Limiting risk limits your choices, though, and comes at a cost.
Even so, we got a bit nervous when we first saw the pictures and videos of widespread landslides in North Carolina that accompanied the flooding. The bedrock of the Blue Ridge Mountains in the Asheville region is similar to that of western Connecticut, and although the mountains are higher there, the terrain is broadly similar. And parts of Connecticut have on occasion received rain amounts exceeding 20 inches in a single storm.
However, we recalled that North Carolina has thick soils known as saprolite that grade slowly into solid bedrock well below the surface. When saturated on hillsides, these thick clayey soils can become fluid and yield landslides or mudflows. In contrast, New England was glaciated and only has very thin soil above often-exposed bedrock, so widespread slope failure is not likely in western Connecticut. We also recognized that Connecticut has more stringent zoning restrictions for construction than North Carolina, and some of the homes lost near Ashville would never have been built in hazardous locations in our region in the first place.
Nationally, as damage claims from severe weather events have risen, insurance companies are becoming more sophisticated in assessing site-specific risks and premiums for homes, commercial properties and even municipalities. And everyone is collectively paying more for coverage, if it is even available.
Future mitigation of increasingly common storm damage will rely on some combination of updated and more rigorous design standards, increased zoning restrictions and a rethinking of personal property insurance and presumptive liability. It will not be inexpensive.
Dan May is a local geologist.