THE JOHNSTOWN FLOOD – AN ENGINEERING FAILURE

0

THE JOHNSTOWN FLOOD – AN ENGINEERING FAILURE

The small town of Johnstown is located about 50 miles east-southeast of Pittsburgh, in the Allegheny Mountains, in southeastern Pennsylvania.  Prior to May 31, 1889 Johnstown would be all but unremarkable in nearly every way. But on May 31, 1889 events in Johnstown Pennsylvania would forever change the landscape of the United States, as a “natural disaster” that would have otherwise affected many people in a larger area, would be amplified by poor engineering and inadequate maintenance that would ultimately claim the lives of 2,209 people.

Introduction and Background

Johnstown Pennsylvania situated at the confluence of the Stony Creek and Little Conemaugh River, forming the Conemaugh River.  About 14 miles upstream from Jonestown, the Little Conemaugh River divides into the North Fork and South Fork.  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 (Figure 1).
http://www.swartzentrover.com/cotor/Tree/JohnstownFlood/Map.jpg
Figure 1: Relationship between Johnstown, PA and South Fork Dam
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.

Construction

The dam measured about 72 feet high by about 931 feet long.  The reservoir (Lake Conemaugh) behind the earthen South Fork Dam was about 2 miles long, and about 60 feet deep at its deepest point.  These measurements would allow for about 12 feet of “freeboard” before the water level in the reservoir would overtop the South Fork Dam.  Modern-day measurements put the water level in the reservoir about 450 feet above street level in Johnstown.
Running under the center of the dam was a huge stone culvert used to discharge water into the South Fork Creek to be fed to the canal via the Little Conemaugh River.  The water into the culvert was controlled by five sets of valves and cast iron pipes, each about 2 feet in diameter.  In the event that the discharge culvert could not handle water flows during heavy rains, an 85 foot-wide spill-way was cut through the solid rock of the hillside near the eastern end of the dam.
http://smoter.com/flooddam/images/culvert.jpg
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.
Screenshot 2014-05-09 11.51.36.png
South Fork Dam – Before (see headland indicated by arrow for reference)

Flood Event

In late May 1889 a strong storm system produced about 6 to 10 inches of rain within a 24-hour period throughout the Allegheny Mountains, causing rivers throughout the area to expand to near-capacity.  By 11 a.m. the water was even with the sagging center of the dam and started to eat at the small mound that had been thrown up by a plow. There are also several reports of a thick layer of debris that was blocking the spillway.  Workmen frantically tried to keep the water from breaking through the crest of the dam.  The water through the trench the plow had cut was running almost knee-deep and its force had widened the trench but had not cut much deeper as hoped.  The tremendous weight of the water in the lake forced several serious leaks to develop on the outer face of the reconstructed section (center).  Some of the workmen also reportedly refused to venture out on the dam.  Around 11:30 a.m. the small mound of earth thrown up by the plow suddenly gave way and the water started over the dam, quickly widening out to about 50 feet.
At about 3:10 in the afternoon of May 31, 1889 the South Fork Dam ultimately failed, releasing about 20 million tons of water down the Valley.  In previous years, many “alarms” had been sounded regarding the imminent failure of the dam.  Under the misguided belief that this final alarm was just another “false alarm”, many people in Johnstown did not seek higher ground.  By the time the floodwater reached Johnstown, it was no longer water, but rather included much of the debris from the 14-mile long Valley between the South Fork Dam and Jonestown.  The debris flow was reportedly up to 1/2-mile wide and may have been as tall as 40 feet above ground in places.  There was no safe refuge in town.
Screenshot 2014-05-09 11.51.22.png
South Fork Dam – After (see headland indicated by arrow for reference)
Note construction details exposed in slump blocks in right-center of photo

Aftermath

In Johnstown, there was an industrial steelworks plant against the river.  By most accounts, and as is evident in several photos taken the day after the flood, the steelworks severely damaged.  Also destroyed were nearly every house in town along with nearly every business, bridge, civil structure and building.  Little was left standing.  Nothing was left unaffected.  Communications of the day were carried primarily via telegraph that followed rail lines.  With the demolition and destruction of the bridges and rail lines, telegraph lines were also clipped.  Investigators subsequently concluded that “the failure was due to the flow of water over the top of the earthen embankment caused by the insufficiency of the waste-way [spillway] to discharge the flood water.
http://2.bp.blogspot.com/_dgNPxBlFp40/TO0wABIqvlI/AAAAAAAACUc/8N9ZSKCJE1s/s640/Johnstown-Flood-1.jpg
Images showing devastation due to flooding caused by collapse of the South Fork Dam
http://www.jaha.org/edu/flood/rebuild/img/panoramas/550w/JT_pano-1889flood-550.jpg
On June 5, 1889 Ms. Clara Barton, the founder and then-president of the American Red Cross (ARC) arrived in Jonestown in what would be the ARC’s first domestic disaster relief effort.  Donations poured into the area from every state in the nation, with more than $3.7 million collected from local, domestic, and international resources.  It would be five years later when an observer remarked that he “would’ve been hard-pressed to imagine the destruction in the Valley on May 31, 1889.Jonestown residents blamed and ultimately sue members of the South Fork Fishing and Hunting Club.  Ultimately however, neither the Club nor individual members were held legally accountable or responsible for the disaster.  Rather than recognize inadequate maintenance programs and unauthorized modifications to the dam, local courts deemed the disaster as an “Act of God”.  Furthermore, it was also reported that individual Club members effectively hid their personal assets behind the Club’s financial structure.
In the time since, many smaller “nuisance” floods have come and gone in Johnstown.  The first physical improvements to reduce the impact floods would have on Johnstown would not be made until 1936.  To this day, high-water marks from present-day floods are recorded at City Hall.
References
Encyclopedia Britannica, 11th edition, Cambridge University Press (common access)
Gibson, C., 2010, “Our 10 Greatest Natural Disasters”, American Heritage
Smoter, F. W., 2004, “The Cause of the Johnstown Flood”, Civil Engineering, pp. 63-66, May 1988

LISTING OF STATE MINERALS, ROCKS / STONES, FOSSILS, AND GEMSTONES

0



LISTING OF STATE MINERALS, ROCKS / STONES, FOSSILS, AND GEMSTONES

Legislatures and governors from most, though not all of the 50 States have specified a mineral, rock / stone, fossil, and/or gemstone that they feel represents their respective state (see table below). In most cases, the species selected reflects a significant part of the particular state’s economy, as with New Hampshire choosing granite, West Virginia choosing coal, and Indiana with Salem limestone (which was used in the construction of the Empire State Building and The Pentagon). So generally speaking, this listing of state minerals makes sense. However, oddities remain.
First of all, not all states, specifically Kansas have chosen a state mineral, rock / stone, fossil, or gemstone, while several other states such as Alabama, Colorado, and Texas have chosen a state mineral, rock / stone, fossil, AND gemstone. Secondly, several of the state “minerals” are also individual elements on the Periodic Table (i.e. gold, copper, and silver). Arguments have been made that such metal reserves are not technically “minerals”.
Then there is COAL. The State of Kentucky identifies coal as a mineral, while both Utah and West Virginia identify coal as a rock / stone. But since coal is formed with the compression and consolidation of ancient organic material, one could also make an argument that coal could also represent a fossil.
Similarly, the State of Mississippi lists their choice of a rock / stone as PETRIFIED WOOD, while petrified wood is listed as the State Fossil for Arizona and a gemstone for Washington. In one particular instance (Vermont), the State Fossil is identified as one individual beluga whale skeleton that dates back a mere 11,000 years, while New York chose the eurypterid, a fossil dating back to the time long before the opening of the Atlantic Ocean. With regard to “agatized coral” with the State of Florida, the formation of an agate presents as a rock / stone, but being that coral is an animal, one could also argue that it is the state fossil.
So take a minute and review this list. Maybe you will find something that interests you. And perhaps you will associate a mineral, rock / stone, fossil, and/or gemstone with where YOU live, or where you have traveled.
Listing-of-State-MineralsListing-of-State-MineralsListing-of-State-MineralsListing-of-State-MineralsListing-of-State-MineralsListing-of-State-MineralsListing-of-State-MineralsListing-of-State-MineralsListing-of-State-Minerals


Concrete - lab reports

0

Uses of concrete include but are not limited to structural components such as beams, columns, piles,  foundations, frames, and walls. The enhancement of the elastic strength of concrete when  reinforced with steel is primarily the due to the adhesion of the two materials. The bond  between concrete and steel remains undisturbed by normal variations of load and temperature.  The coefficients of thermal expansion of concrete and steel are similar, allowing the two  materials to work together without internal stresses due to differences in thermal deformations.  In the case of fire, steel in reinforced concrete is protected from loss of strength due to  excessive heat by the insulating properties of concrete. Additionally, the steel is protected from  corrosion by a film of cement attached to its surface. For these reasons, codes specify a  minimum required concrete cover. Steel reinforcement for concrete varies and may consist of  bars, stirrups, wires, and welded wire fabric. For most reinforcing steel, deformations are rolled  on the surface of the bar (in accordance with ASTM specifications) in order to increase the bond  between concrete and steel.   


Reports :

1- Job mix design
2- Sieve analysis
3- Crushing
4- Air content test
5- Ultra sound test
6- Core drill test
7- Schmitt hammer test
8- Crushing of beams
9- Specific gravity
10- Workability

Download :
Here 



DEEP FOUNDATIONS VERSUS SHALLOW FOUNDATIONS

1

DEEP FOUNDATIONS VERSUS SHALLOW FOUNDATIONS

As the names would seem to imply, the primary difference between a shallow and deep foundation is the depth that the foundation extends into the ground.  Shallow foundations spread structural load to soils that are near the ground surface.  Shallow foundations are commonly implemented in residential construction or for any structure with generally light loads (weight of the overlying structure).  Deep foundations, as you might have guessed, extend structural loads to soils that are not near the ground surface.  These deeper materials generally have a much greater load bearing capacity than material near the ground surface.  Deep foundations are commonly implemented when dealing with very large design loads, such as those associated with large buildings or bridges.  Some deep foundations are driven into the ground, such as concrete piles, while others are put in place by excavation and drilling.
bridge-construction
Aside from difference in depth, another significant difference between shallow and deep foundations is the way that the design loads are transferred to the soil.  Shallow foundations primarily transfer loads to the soil by bearing pressure (loads are supported by the soils directly below the foundation).  Deep foundations also transfer loads to soil through bearing pressure (albeit to much deeper soils with generally greater load bearing capacity), but additionally transfer loads by friction with the soils along the length of the foundation; making deep foundations significantly more stable than their shallow counterparts.
deep-foundations

BRIDGING A GAP

The need for bridges was clear even in ancient times.  As early roads began to connect villages together, the necessity of traversing natural obstacles encountered along the way became increasingly important.  While a person carrying limited supplies could likely cross a river or stream by swimming; the same was not true for the carts and wagons needed to transfer large amounts materials and resources between destinations.  Thus, the need for permanent sturdy bridges was born.  This is a need that has only grown over time as human society entered the modern era.
Some modern bridges traverse huge distances, such as the Danyang-Kunshan Grand Bridge in China which runs approximately 102.4 miles in length; while others are much smaller, sometimes simply extending across a creek or slough.  However, a common requirement in the construction of all modern bridges is the need for stability.  As is the case with all construction (bridge, house, skyscraper or otherwise) stability begins with the foundation.  The foundations of a bridge are of critical importance as they must support the entire weight of the bridge and the traffic loads that it will carry.
bridge-construction

DEEP FOUNDATIONS IN BRIDGE CONSTRUCTION

The most common type of deep foundation for modern bridge construction is piling.  Piles used for bridge construction may be concrete, steel, or timber; the most common of which is pre-cast concrete piles.  In short, the piles are put in place by a large crane and driven into the ground to competent subsurface material by means of a large (usually diesel powered) hammer which is hoisted above the pile by crane.   The lengths of the piles vary greatly depending upon the depth to competent material in the area where the bridge is being constructed.
deep-foundations-bridge-construction
As the piles are hammered into the ground, soils are displaced and friction builds up along the “skin” of the pile.  This friction factor significantly supplements the bearing pressure of the pile.  When the desired depth is achieved and the piles are sitting atop competent bearing material, the piles are capped and tied together; allowing the bridge to be constructed upon the solid foundation provided by the piles.

USEFUL STRUCTURES AS A WORK OF ART

As we look to the future, the scale and complexity of bridge design continues to become ever grander.  The aesthetics of a finished bridge is also increasing in importance in the modern era; as bridges are viewed not only as functional constructs to traverse natural obstacles, but as works of art.  However, one must always remember that a structure is only as strong as its foundation.

deep-foundations

Sources

Gascoigne, Bamber. HistoryWorld. From 2001, ongoing. http://www.historyworld.net/wrldhis/plaintexthistories.asp?historyid=ab97
Katharine Gammon. LiveScience. February 28, 2013.  http://www.livescience.com/34448-worlds-longest-bridge.html
A&SW Consultants, Inc. Construction Training and Qualification Program: Pile Driving Inspector. Version 1.1-6/10. Prepared for the Florida Department of Transportation

Tower Cranes

0


Tower cranes are a common fixture at any major construction site. They're pretty hard to miss. They often rise hundreds of feet into the air, and can reach out just as far. The construction crew uses the tower crane to lift steel, concrete, large tools like acetylene torches and generators, and a wide variety of other building materials.

Tower cranes rise 150 feet in the air and lift up to 19 tons. Plus, they actually build themselves! They're simply amazing. Learn how these structures accomplish such feats.










Most Commonly Asked Questions During the Interviews for the Civil Engineers

0



1.Introduce yourself?
2. What are your career preferences?
3. How much salary you are expecting?
4. What is your plan regarding continuing your education?
5. Tell us about your hobbies?
6. What are your strengths & weaknesses?
7. Are you ready to work in a team?
8. Can you work in stress?
9. What good things you liked in your ex boss?
10. How do you feel working on weekend?
11. Define success?
12. How good your communication is?
13. Where do you see yourself in next 2 years?
14. You like trying new things or stay with old ones?
15. Why you have applied for this position?
16. Tell us about your family?
17. Areas where you can revamp your skills?
18. What if you are not selected for this position?
19. What makes you feel that you are the best candidate for this position?
20. What you preferred, money or work?
21. Tell us about your subjects?
23. What is your greatest strength?
24. What are you looking for in a job?
25.What kind of person would you refuse to work with?
26. What is more important to you: the money or the work?
27. Tell me about your ability to work under pressure.
28. Do your skills match this job or another job more closely?
29. What motivates you to do your best on the job?
30. Describe your management style.
31. How do you propose to compensate for your lack of experience?
32. Describe your work ethic.
33.What qualities do you look for in a boss?
34.What position do you prefer on a team working on a project?
35. Do you have any questions for me?



Culverts - Hydrology

0

Culvert

Description

A culvert is a closed conduit used to convey water from one area to another, usually from one
side of a road to the other side.

Importance to Maintenance & Water Quality


Disposal of runoff from roadway ditches will help preserve the road bed, ditches, and banks.
Strategically placed culverts, along with road ditch turn-outs, will help maintain a stable velocity
and the proper flow capacity for the road ditches by timely outleting water from them. This will
help alleviate roadway flooding, reduce erosion, and thus reduce maintenance problems. In
addition, strategically placed culverts help distribute roadway runoff over a larger riparian
filtering area. Culverts preserve the road base by draining water from ditches along the road,
keeping the sub-base dry

For the whole article you can download from :



Contents :

this article talks briefly about :

- Culvert Profile
- Culverts For Stream Crossings
- Culverts For Runoff Management
- Maintenance At Sensitive Aquatic Environment Crossings
- Fish friendly designs
- Culvert Installation/Replacement
- Head Walls (Headers)
- Cleaning and Maintenance

Sand cone test - Soli lab report

0

        When a sample of soil is classified as being suitable to be used in certain earthwork( after performing several tests on it in the lab), it is necessary as well to do some tests on the soil in the field to check if it satisfies some engineering specifications or not, such as: compaction. Compaction is done to decrease the spaces in order to increase the unit weight, reduce settlements, decrease permeability and increase the bearing capacity of the soil. A well-compacted soil must achieve a dry unit weight of more than 90% of the maximum dry unit weight which is determined in the lab using the standard or modified proctor test. The unit weight of a compacted soil in the field can be calculated using the sand cone method or the rubber balloon method or the nuclear gauge method. In this experiment the sand cone method is used to calculate the unit weight of soil.


Types of shallow foundation

0

Basically there are 5 types of shallow foundations:

1) Strip footing:



The strip footing is employed in case of a load-bearing wall. The strip footing is also used for a row of columns that are very closely held and spaced such that their spread footing overlap or tends to nearly touch each other. In such cases it is more economical and effective to use a strip footing than to use a number of spread footings held in a single line. Thus, a strip footing is also called as continuous footing.