As you approach the intersection of Sawmill Run Blvd. and Woodruff Street just before you go under the old Concrete Railroad Trestle for the abandoned Wabash Railroad you will see a very large rock sitting there on the corner behind a wooden spoke fence.
Not much more than a rock sitting there but a very significant one which taught The state of Pa. the City of Pittsburgh and its contractors and engineers not to mess with mother nature.
For this rock is one of the many which killed a bulldozer operator and 2 motorists when Blasting was being done on the hill side to remove rock and stabilize the hill.
Engineers and blasters assured everyone they could safely blast rock. Have a 15 minute waiting period then allow traffic to flow thru. They where very wrong after one of the blasts and things went very wrong.
I was in the North Side that day working on a job when a Got a call from a used car dealer customer on W. Liberty Ave. who needed service I finished up the North Side work and started heading into the South Hills When I hit a high amount of traffic on the Liberty Bridge and then it came over the radio.
There was a terrible accident where they where blasting to clear rock along and the hill had come down and crushed vehicles. I was able to slowly get over the bridge and thru the Liberty Tunnels and up W. Liberty to customer by then it was all over the TV as he had a small set on in the sales office.
After stopping all traffic blasting then waiting 15 minutes to be sure it was safe they let traffic thru the area when the hill side gave way. Trapping and Killing a Bulldozer operator a motorist and tractor trailer driver.
Do not show it respect and it will kill you when building known all the way back to even the days when
Native Americans roamed the area.The Monongahela river is an Indian term loosely translated stands for river bank of sliding rocks. But warnings in both cases where ignored when previous slides where ignored.
It is caused by the way the sediments and soft rock layers came together to form the geology of the region.
It is also described on page 37 in Pa geology guide link below
The soft porous rock allows for water penetration and dirt and with the freeze thaw action allows layers of rock to break off after a hillside is dug into. You have to allow for a gradual slope and cut in steps or benches as they are called when you cut into a hill not a steep 90 degree angle unless you properly reinforce it. Which was not done in both cases years of exposed outcropping allowed the stone to blow outward and give way. There was a prior slide in both cases and this area in particular is none for the extreme dangers it poses and likely hood of it happening . Its like a house of cards and must be properly managed to prevent problems. As you can see in case below before the sawmill run accident no bench cut in but afterwards there where and there has been no further incidents.
http://www.dappolonia.com/pdfs/pprofile77.pdf
http://www.dappolonia.com/pdfs/pprofile77.pdf
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