In My Back Yard: Geotechnical Investigations and Subsurface South Slope Exploration

IMBY... In My Back Yard returns to its roots with this  construction update. For those familiar with THE STORY you will be glad to see that we are moving on with the remediation of our damaged crack houses.

After five fucking years of endless soul-killing litigation in the Brooklyn civil court system before the Honorable Justice Laura Jacobson, my neighbors and I have embarked on another financially and emotionally draining journey, hiring what seems like all the king's horses and all the king's men to put our Humpty Dumpty houses together again.

First this, then that, then this.
So you finally find a respected general contractor(s) you like for the job, but they all tell you that foundation repair on 100 year old brick rowhouses is complicated to say the least. The builder tells you he needs detailed drawings, an approved plan, a set of DOB approved marching orders  to know how to bid for the job.  He tells you that he requires the professional advice of a licensed engineer.  Someone who has a vast knowledge of all the possible technological solutions currently out there to remedy your particular shit-storm of a problem.   The one best suited to your individual foundation site.

So now you hire the services of an Engineer.  But Engineers work with hard facts and data.  They need to know what's what.  So your engineer  contracts out the specialized services of a geotechnical engineering firm.  We need someone with a thorough understanding of the principles and practices of subsurface soil investigative techniques in order to determine the current soil conditions and, in our case, how our properties have been affected by the haphazard excavation and construction of the Armory Heights Plaza's three story underground parking garage.

A truck mounted boring rig is the first piece of heavy equipment to show up on a construction site, sometimes even before it starts to look like one.

Leading the Industry Since 1957
So that's where we are today.  Let me introduce you to the Soil Mechanics Drilling Corporation of Seaford Long Island.  They will be performing our subsurface exploration demonstration for today.


The Standard Penetration Test with a Split Barrel Sampler.
This is what is known in the geology business as "The Farmer's Daughter".

First the equipment.  Take note frugal homeowners.  Limited access to the site (say the enclosed backyard of a Brooklyn row house) unfortunately requires the use of a portable drilling/boring rig.  This means all the individual parts of the drilling rig have to be taken off a truck and lugged to the boring site, in this instance through one's kitchen, then assembled out in the backyard.    Afterwards the rig has to be broken down and brought through the kitchen again and out to the street, where it gets loaded back on the truck.  That, as they say... costs a premium.

The portable drilling rig,  assembly required.

Your standard "Donut Hammer".

Briggs and Stratton engine equipped with rotating cathead.

The Parts Diagram for the S.P.T

Opening the borehole. Concrete hole saw cuts right through 5 inch thick patio making way for the iron sampling rods. During the construction of the parking garage this entire patio slab migrated away from the rear wall of our house.

The three man crew sets up and operates the rig.  It took all of three hours to set it up, perform the test sampling, and break it back down.  In Brooklyn it's actually bad news if they strike oil.

Ready to start.  Wrapping the rope around the spinning cathead.

Split Barrel Sampler:  The two haves of the barrel shown separated revealing the soil sample.

The biopsy

The threaded ends allow for the fastening of both halves of the barrel.

The soil samples are removed and placed in glass jars for study back at the lab.  This sample taken from approximately 20 feet deep revealed dense peat-like organic matter. You could actually see what looked like plant material; bark, seeds, stems, within the the sample.   Evidence of some type of long ago bog-like geography perhaps?  Maybe a sheep pasture?

The sample box.  All combined Soil Mechanics performed a total of 6 boring tests.  Besides the actual collection of these samples a written descriptive log was maintained documenting the entire process from start to finish.

Once back at the lab, the extracted boring samples are analyzed, and then a geotechnical report will be issued by Soil Mechanics Corp.  
Our engineer will use this information to design, if needed, an underpinning plan to stabilize our compromised foundations.  Our general contractor will work with the engineer to come up with some kind of estimate as to the cost of the repairs.  Anticipating what the engineer is going to prescribe to remedy our ailing homes?   I fear that I already know what he is going to say.  There is seldom good news.   Stay tuned...