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Construction & Contractors/well water problem from blasting?


Blair wrote at 2012-06-06 19:44:11
If aquifers are inter mingling, one way to verify other than the obvious chemistry changes you noted (visually and odour), would be to determine if your static level (water table)has risen with in the well casing. Your drill log from when the well was completed would indicate the static level upon completion of the well. Ensure that the well has had ample time to recover (resting static - no pumping for 12hrs.)Then measure the static level and compare that figure with the original drill log.

If the static level is closer to the surface than before,you have aquifers mixing. You either have a broken seal on your well or the activity may have disturbed the natural seal with in the formation. One other way to determine if the water is inter mingling, providing you have a previous water chemistry from before the event, re test the water again using the same parameters as before and if some of the chemical constituents are way out of wack ( say more than 100 ppm)theres definitely inter mingling. Hope that helps

Eric Dussell wrote at 2013-05-26 14:12:34
The damage mechanism is not from regulatory external vibration.  Safe limits for wells seals and components is 5 ips.  But this contains a large safety factor.  The mechanism is chemical.  Stripping of ground cover at a construction site exposes soils and rocks containing Fe/Mn-bearing minerals to acidic rain.  Lowering of the pH leaches these elements, mobilizing them in the groundwater.  When drawn into the well during drawdown and exposed to oxygen during use, ferrous Fe changes to ferric Fe and precipitates out.   The good news is that this is a temporary effect, clarifiying over time as ground cover is reestablished.  Also burial of organic debris can create local reducing conditions, mobilizing Fe.  Its a construction, not blasting impact.

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Robert Cummings, P.E.


I can answer questions related to rock blasting, rock and soil excavation (such as tunnels and highway cuts), stability of such excavations, and foundations in rock and soil. I can also answer questions related to geology and mining.


30+ years as a geotechnical engineer and minerals engineer. Active consulting practice in rock blasting, geotechnical engineering, and rock mechanics for mining and heavy construction.

Society of Mining Engineers, Deep Foundations Institute, Association of Engineering Geologists, and International Society of Explosives Engineers.

Mining Engineering, AEG Bulletin.

BS and MS Geological Engineering

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