The endless saga of the parking-building-built-on-a-
stream-spring: the (hydrostatic) force is with it
Last year I was saying
And next to that page 3 article, we find More delays for library, garage, and the library director “said opening day is “fluid”, and really hinges on when the site work and driveway access to the building can be completed”.
Fluid is a particularly apt word to use for two buildings on the same block, one of which, the parking-building-built-on-the-stream, is built directly on an aquifer. Just this afternoon the local cable station carried an interview with Jim Firestone, where they showed video of the completely flooded foundation for the parking-building-built-on-the-stream. It gives new meaning to floating debt.
Debt it is, and increasing, but the building ain’t floating.
In fact, it’s been flooding, and cracking. Last week The Husband took a look (the basement water had gone down some since we’ve had a dry spell) and saw that the basement floor’s got cracks. Plenty of them. The building’s barely 1.5 years old.
The Husband believes the cracking’s due to hydrostatic pressure from the water coming up from Harry’s Brook, on which the garage building was built. If you ever built a swimming pool in an area that has a high water table (say, in a place in Florida, or obviously, here in The Principality) and had to empty it for cleaning or repairs, the first thing the pool guy tells you is to make sure to fill it soon because the water (i.e., hydrostatic) pressure can make the walls of the pool collapse.
Hydrostatic pressure’s force is huge. I asked Ken Adams (who kindly took time from his home work at SmadaNek Central) if he knew how to calculate it, and he replied,
Not sure how you would calculate the pressure exerted upward by spring water on a structure above it. If it works like water pressure underwater, then you get 1 atmosphere for every 30 feet or so. That would make the pressure in your case 1/2 atm, or about 7.5 pounds per square inch. There are a gross of square inches in a square foot, so the pressure in psf would be 1,080 pounds.
That’s 1,080 pounds per square foot. Huge, in a building that large.
Now the Town Topics headline says Garage Analysis Suggests a Flaw In Structural Design; the Packet says
An independent analysis of the Spring Street garage — part of downtown redevelopment efforts — suggests the seepage in the basement potentially is the fault of the design team, Borough Engineer Carl Peters said.
It indicates that “the floor wasn’t designed to withstand the pressure,”
No sh*t, Sherlock.
The proposed remedy would strengthen the lower level slab of concrete then cover it with a “sandwich” slab. Of course that would make the basement ceiling lower. How much lower, we won’t know yet. We also don’t know if any remedy would work at all.
The proposed repairs are estimated to “fall in the range of $300,000 to $400,000”, which the Borough administrator says “lies with Nassau HKT, the project’s developer. Nassau HKT may work with HNTB [the building’s architects, who are based in Kansas City, Mo.] [no, I don’t know why Kansas City] to recoup the money.”
If all this remedial work is finished by Thanksgiving (granted, that’s a big “if”), then the developer can start building the other building on Tulane street. That way the downtown merchants would have a doozy of a holiday season with all the ensuing traffic detours, chaos and construction in the central business district.
Strategic planning, if there ever was.
Ken Adams says
I am not a professional engineer, nor have I ever even worked as an EIT. I make no claims as to the accuracy of my calculations, nor the veracity of my assumptions.
There, now no one can sue me for being wrong.
And yet I appreciate your help all the same, Ken!
Ken Adams says
Glad to give it, too!