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Panic in the Boiler Room
Equity was conducting groundwater delineation activities at a site located in the Bronx.
As part of the groundwater investigation, a monitoring well was to be installed in the basement boiler
room. Adjacent properties had similar basement groundwater monitoring wells at relatively the same elevation above
sea level. The well logs for those wells indicated "static" groundwater approximately three feet
below each basement slab.
After coring through the 2-foot concrete slab, water
was encountered just below it. Initially, it was thought that an unmarked water line had been breached however that
was not the case. Unlike neighboring properties, groundwater was just below the slab.
Encountering shallow groundwater is not an unusual situation but, the extremely high hydraulic
pressure coming from the hole was. Not an artesian condition but, definitely enough hydraulic pressure to
fill the entire basement in a few short hours. This had everyone looking for their bathing
suits as outside temperatures were close to 100 degrees and the basement boiler room temperatures were much higher.
Initial efforts to control the water flow and seal the hole were unsuccessful. Sump pumps did
not work, multiple trash pumps working in unison did not work, all combinations of grouting/bentonite did
not work, opinions from plumbers and advice from multiple drilling contacts met with failure attempting to control
the hydraulic pressure and stop the flow of water. We even tried the "finger in the dike technique".
The local Fire Department was visited for ideas on how to handle a "hypothetical" situation to no
avail. The FDNY will only respond to an emergency situation (e.g., sumps cannot handle flow creating a flood
like dilemma and/or electrical/mechanical systems are at risk) exists. It was now late in the evening and
to add to the current crisis, the basement's sump pumps decided to burn out. Murphy was
at it again!
Now, for all those consultants and facility managers
out there, you can probably imagine the situation growing in the basement boiler room. To
temporarily stop the flow of water coming into the basement, "ingenuity" had to take center stage. A
small container was inserted into the hole to act as a plug. However, once set in place the groundwater gremlins
decided to have a little fun and turned the container into a projectile. Eventually,
a second attempt to temporarily plug the borehole was successful. You would be surprised what heavy duty plastic
trash bags and 50 lbs of sand can hold back!. With the problem of
flowing groundwater temporarily at bay, there was finally time to craft a permanent solution. A
natural rubber air-inflatable test plug was selected. The plug was inserted into the core hole and inflated
with an air compressor. After capping the air valve, hydraulic cement was used to seal the remainder of the boring.
Lessons Learned: 1) We all know stuff happens in the field even
during routine operations. Stuff happens that is always unexpected and always at the wrong time. Leprechauns
with the right solution never pop out of corings with rainbows, pots of gold, or practical solutions.
Team work and cool heads will always prevail. 2) When drilling in basements located near bodies of water always
triple check your elevations. Do not rely heavily on neighboring property conditions. Be prepared to
manage the most improbable hydrogeologic encounter. Robert M. Fry |
