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National Surveyors Week

March 18-24, 2012 is National Surveyors Week.  Surveying has existed since the beginning of recorded history.  Examples include:

        Stonehenge (c. 2500 BC) suggests that the monument was set using peg and rope geometry.

        Egyptians’ command of surveying resulted in nearly perfect squareness and north-south orientation of the Great Pyramid of Giza.

        Under the Romans, land surveyors were established as a profession.

Surveying encompasses a broad spectrum of jobs and terrain.  Surveyors can be researchers, computer specialists, mapmakers, business owners, expert witnesses in court, and even crime investigators.  They can work outdoors and indoors, in mountainous terrain and cities, and even map land under water.  Surveying is required in the planning and execution of nearly every form of construction.  The profession blends old and new by relying on historical data while implementing new technology.  

On-line Maps

So the aerial view of your property clearly shows your fence or shed on your property but your neighbor just had a survey done and there’s a stake on your side of the fence.  How can this be?   Maps depicting land boundaries can be viewed on numerous Internet sites, including County websites.  However, they are merely for reference and should not be relied upon for boundary information.  We have seen maps as much as 30 feet off.  If you are making decisions about your property or question what your neighbor is doing on theirs, having a boundary survey done by a Professional Land Surveyor is the only way to accurately delineate your property.  

ANOTHER 100-Year Storm! How Can This Be?

The term “100-year flood event” can be misleading. It is not an event that happens once in 100 years.  Rather, it is the amount of precipitation needed to achieve a flood elevation, and this event has a 1% chance of being equaled or exceeded in any given year. In this area, it is the elevation based on a 24-hour rainfall of 5.9-6.0 inches. Encountering a "100-year storm" on one day does not decrease the chance of a second 100-year storm occurring in that same year or any year to follow.

More recently, FEMA has tried to clarify the probability of a 100-year flood by saying that it has about a 26 percent chance of occurring during the life of a 30-year home mortgage. That's about triple the risk of a fire during that same period.  There’s also been talk about changing the terminology and/or metric for measuring flood risk.  However, key players -- such as FEMA, the Army Corps of Engineers and the National Weather Service -- have not agreed on a new metric.  Until then, it will be up to engineers, hydrologists and flood agencies to inform the public as to the terminology used.

In Minnesota, most municipalities require storm sewers to be designed for a 10-year storm event.  Larger events create ponding at catch basins until the water reaches the emergency overflow elevation (EOF).  The EOF is typically designed to be 1’-2’ lower than adjacent buildings.  Stormwater ponds are designed for the 100-year, 24-hour storm event.  However, there are many factors that can contribute to flooding.  Among other factors, frozen ground, saturated soil, high river/lake levels, silted catch basins and an intense rainfall (flash flood event) can exacerbate flooding.