Monday, July 27, 2015

GYY: The Great Johnstown Flood of 1889

On May 31, 1889, a neglected dam and a phenomenal storm led to a catastrophe in which 2,209 people died. It's a story of great tragedy, but also of triumphant recovery. This was one of the worst American man-made tragedy prior to September 2011.

The details of this tragedy are horrific.   You can read more about what transpired leading up to the collapse of the South Fork Dam on the Little Conemaugh River here, but what is more disturbing is that after several warnings.   Nothing was done to fix, correct, or even save the dam even on the day it failed.

Photo of damn before the collapse

The original construction of the dam was not sound when it was built.  In the 1830’s, the Commonwealth of Pennsylvania built the South Fork Dam along the South Fork of the Little Conemaugh River to hold back water in a reservoir as a local water supply for a series of canals. 
The dam suffered a major break on June 10, 1862, when the up-stream portion of the stone culvert (control tower) running under the dam collapsed.  Although there was little damage to property downstream, a large section of the dam over the damaged portion of the culvert collapsed and was washed away.

In the original specifications, there was to be a 10-foot deep spillway at the southern edge of the dam.  When the crest of the dam was lowered by about 2 feet to widen the roadway, the capacity of the spillway was reduced by one-fifth (20%).  Furthermore, because of the way in which the dam was reconstructed in 1880 and 1881, the repaired section settled until it was at least six inches lower than the ends of the dam.

It is not uncommon for the best earth dams to settle, especially at their centers, which is also the weakest point and where the water pressure is the greatest.  But with proper maintenance earthen dams can be built back up.  At the South Fork Dam the part of the embankment which should have been the highest (center), if only by inches, was the lowest.

With increased rail traffic in the area in the 1850s, accompanied by a period of unusually low rainfall, there was apparently little need for such a series of canals.  As a result, the South Fork Dam and reservoir was sold in 1881 to a local hunting and fishing club with members made up primarily of steel, coal, and railroad executives.  With the operation of the reservoir under the “South Fork Fishing and Hunting Club”, little was done to maintain the South Fork Dam.  There were evidently reports of numerous leaks through the South Fork Dam when the Club owned the structure and reservoir.  There were also reports where the steel pipe used in the overflow system had been sold for scrap prior to purchase by the Club.

The original club house for the South Fork Fishing and Hunting Club.

Henry Clay Frick led a group of speculators, including Benjamin Ruff, from Pittsburgh to purchase the abandoned reservoir, modify it, and convert it into a private resort lake for their wealthy associates. Many were connected through business and social links to Carnegie Steel.

Henry Clay Frick
Development included lowering the dam to make its top wide enough to hold a road, and putting a fish screen in the spillway (the screen also trapped debris). These alterations are thought to have increased the vulnerability of the dam. Moreover, a system of relief pipes and valves, a feature of the original dam, was not replaced, so the club had no way of lowering the water level in the lake in case of an emergency. The members built cottages and a clubhouse to create the exclusive and private mountain retreat. Membership grew to include more than 50 wealthy Pittsburgh steel, coal, and railroad industrialists.

The city officials from Johnstown pleaded with Frick to reinforce the dam and make it more stable.   Their pleads were ignored.

On the morning of May 31, in a farmhouse on a hill just above the South Fork Dam, Elias Unger, president of the South Fork Fishing and Hunting Club, awoke to the sight of Lake Conemaugh swollen after a night-long heavy rainfall. Unger ran outside in the still-pouring rain to assess the situation and saw that the water was nearly cresting the dam. He quickly assembled a group of men to save the face of the dam by trying to unclog the spillway; it was blocked by the broken fish trap and debris caused by the swollen waterline. Other men tried digging another spillway at the other end of the dam to relieve the pressure, without success. Most remained on top of the dam, some plowing earth to raise it, while others tried to pile mud and rock on the face to save the eroding wall.

John Parke, an engineer for the South Fork Club, briefly considered cutting through the dam's end, where the pressure would be less, but decided against it. Twice, under orders from Unger, Parke rode on horseback to the nearby town of South Fork to the telegraph office to send warnings to Johnstown explaining the critical nature of the eroding dam. But the warnings were not passed to the authorities in town, as there had been many false alarms in the past of the South Fork Dam not holding against flooding. Unger, Parke, and the rest of the men continued working until exhausted to save the face of the dam; they abandoned their efforts at around 1:30 p.m., fearing that their efforts were futile and the dam was at risk of imminent collapse. Unger ordered all of his men to fall back to high ground on both sides of the dam where they could do nothing but wait. During the day in Johnstown, the situation worsened as water rose to as high as 10 feet (3.0 m) in the streets, trapping some people in their houses.

At around 3:10 p.m., the South Fork Dam collapsed, freeing the 20 million tons of Lake Conemaugh to cascade down the Little Conemaugh River. It took about 40 minutes for the entire lake to drain of the water. The first town to be hit by the flood was South Fork. The town was on high ground, and most of the people escaped by running up the nearby hills when they saw the dam spill over. Some 20 to 30 houses were destroyed or washed away, and four people were killed.

On its way downstream toward Johnstown, 14 miles away, the crest picked up debris, such as trees, houses, and animals. At the Conemaugh Viaduct, a 78-foot (24 m) high railroad bridge, the flood temporarily was stopped when debris jammed against the stone bridge's arch. But within seven minutes, the viaduct collapsed, allowing the flood to resume its course. Because of this, the surging river gained renewed hydraulic head, resulting in a stronger wave hitting Johnstown than otherwise would have been expected.

The small town of Mineral Point, one mile (1.6 km) below the Conemaugh Viaduct, was hit with this renewed force. About 30 families lived on the village's single street. After the flood, only bare rock remained. About 16 people were killed.

Here is a summary of the tragedy from the history channel: 
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If you would like to find out more about this event, please check out these resources below:
Sources and more research:

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