Remediation of a Sinkhole Induced by Quarrying

By Thomas J. Abkemeier, M.ASCE and Richard W. Stephenson, F.ASCE
(the following was from a yearly 2003 conference by the American Society of Civil Engineers)

On the morning of April 28, 1997, a sinkhole developed beneath a Burlington Northern Santa Fe Railway track. The sinkhole caused the derailment of 22 railroad cars, spilling diesel fuel from the engines that ignited, resulting in a fire and injuries to railroad personnel.

Railroad personnel filled the sinkhole with about 500 cubic yards of rock fill, and traffic resumed while a subsurface study was carried out. The study resulted in a grouting program where 40 to 50 cubic yards of grout were injected into the subsurface.

In August of 1999, the track subsided again. A second investigation conducted in October 1999, involved a tomographic imaging survey to define weaker zones beneath the track that may have contributed to the August ground movement. A much more extensive grouting program followed this study in April 2000. A total of 2746 cubic feet of neat cement/fly ash grout and 162 cubic feet of sand-cement/fly ash grout were injected into the underlying bedrock.

In July of 2000 another and larger subsidence occurred, and a second tomographic imaging survey was conducted.

In April of 2002, the sinkhole reactivated and continuing movement occurred over a period of weeks. About this time, a large volume of sand-laden water was reported entering the adjacent quarry. A third grouting program was conducted and involved injection of cement, chemical, and hot asphalt grouts. The grouting appears to have arrested both the subsidence as well as the inflow of water into the quarry.

Note how many times it reactivated and failed to be repaired properly. Did it continue to fail because someone was trying to save money on the repair? This is common as sinkhole remediation is quite costly.

Alabama Power has so much trouble with this at the nearby dam that they have built a cement facility right there.

There has been no discussion about sinkholes occurring under the rail lines here in Vincent, because WRQ claims there won't be any sinkholes. They are in direct opposition with many noted geologists including the USGS about what massive dewatering does in a Karst terrain as a result of mining.

Highly toxic chemicals travel right through downtown every day on this rail line.

The consequences of a sinkhole developing under our rail line could have disastrous results. No one has even mentioned it, so if it does happen they have no plan to address it. That is quite alarming.

White Rock keeps telling the community that sinkholes are not a concern and disputes John Newton's geological study of the Dry Valley area of Shelby County as outdated. Robert Wood, WRQ "geologist" in a March 16, 2010 memorandum to the Vincent Planning Commission, even goes so far as to say Mr. Newton "never determined how many of the sinkholes within his study would have occurred anyway had there been no mining." He also says; "The geology and hydrogeology of Dry Valley is very different than the Vincent area."

Those are (to use the term Mr. Fowler is so fond of) "bold faced lies" and he knows it. He is deliberately misleading the officials and Shelby County and should be fired immediately as he has lost all credibility as a professional.

From one of several of Mr. Newton's geological surveys in Shelby County, "Case History No 911" page 246:

"Dewatering or the continuous withdrawal of large quantities of water from carbonate rocks by wells, quarries and mines in numerous areas in Alabama is associated with extremely active sinkhole development. Numerous collapses in these areas contrast sharply with their lack of occurrence elsewhere."

Geologic description of the Dry Valley area same case study page 245:

"The terrain used to illustrate sinkhole development is a youthful basin underlain by carbonate rocks such as limestone and dolomite. The basin contains a perennial or near perennial stream (Spring Creek is one of ours here in Vincent near the quarry site). This particular terrain is used because it is very similar to that of 10 active areas of sinkhole development in Alabama that have been examined by the author. Factors related to the development of sinkholes that have been observed in these areas are generally applicable to other carbonate terrains."

Consulting the geologic maps for mineral deposits show what deposits in the Vincent area that WRQ is after and they have said it themselves in their documents:
Limestone and Dolmite.
This terrain in Vincent is also described exactly as in the sentence above as a "youthful terrain overlain by carbonate rocks such as limestone and dolomite."

Mr. Wood would have us believe that the geology of Shelby County Karst is completely different depending on where the Karst is in the county. He also goes on to say that in the Dry Valley area multiple quarries created a dewatered zone between their sites and they were discharging water across each others cones of groundwater depression and dewatered zones.

What he is attempting to say to explain away the increased sinkhole activity is called impoundment. It is the overburden of water which results in collapse. This occurs most commonly as a result of heavy rainfall not quarrying disharging. What he does not say is:
(From Environmental Hydrogeology 1997:
"Collapses resulting from the draining of impoundments in cones of depression are not uncommon."
(In the forward of the book: "This book contains information obtained from authentic and highly regarded sources"
He attempts to blame collapse on sheer water volume and weight, while EH clearly states it is the draining of the water that most often causes the collapse.

It is still a dewatering issue that causes the increased, frequent subsidence. Heavy rainfall and drought conditions are known natural variables in sinkhole formation in Karst terrain and not disputed as such.

But, if Mr. Wood wants to use discharging as a cause then we need to ask how his claim will effect the surrounding land in Vincent. We won't need several quarries discharging water as this one will be pulling massive amounts based on what he has said about the amounts WRQ will be withdrawing from the ground. They will have to put the excess amount somewhere won't they?

So, it seems he has put himself in a box with his own statement.

Mr. Newton does not mention this "cross watering and discharging" as the main cause of man induced sinkholes once in any of his studies, nor do others mention it in subsequent studies. What they all say is dewatering from wells, mining and quarrying are the culprit for increased, rapid forming sinkholes. If what Mr. Wood suggests was indeed the case, it would have been prominently stated as a part of the numerous studies done on the area would it not?

One other geologist calls it like it is:

"The problem is the solution----stop dewatering."

Mr. Wood is attempting to discredit any other geologist besides himself and buffaloing the officials with "high brow" language he knows is designed to deceive.

The lengths WRQ and their hired guns will go to is astounding and reckless.

They will not get away with this rest assured. Exposure is coming.

***Tomorrow the post will address how sensitive Karst terrains are for groundwater pollution addressed by the ASCE conference.
WRQ is lying about this issue too and it will be proven courtesy of the ASCE.