Grandfather on Building a Foundation

Grandfather on Building a Foundation

One of the better memories of my childhood was going for walks with my Grandfather, Edward “Speedy” Gerkin. He was my mother’s father. My earliest memory of him is probably when I was about four, but this story takes place when I was about five or six, apparently in the year 1956.

My grandfather was born in West Virginia in 1984 so he was about 72 in 1956. In his youth he was a running back on a football team. He acquired the nickname, Speedy, because, during a football game against an Eastern Pennsylvania team, he ran down a player from behind and tackled him. The player he tackled happened to have the reputation of being the fastest runner in the local area. After the game a number of locals approached my grandfather and offered him money if he would run a foot race against the player to resolve who was the fastest. My grandfather declined.

My grandfather only had an eight grade education, becoming an apprentice machinist for a railroad sometime in his teens. The railroad he worked for had a football team and during his early years he spent a lot of time playing for that team. Grandfather made a career of working as a machinist for the railroad. I believe he was forced to retire in the early 1950’s when his employer at that time, Union Pacific, ordered him to take a physical and discovered he had a heart murmur. It was a condition he’d had since birth.

Grandfather never owned an automobile. To get around in the city he either walked or took a “street car” as he called them. I believe the street cars were replaced with buses sometime in the early 1950’s. For long distance travel, he took the train. Back then passenger trains were a lot more prevalent than today.

I think grandfather took a walk most every day. He knew a lot people who lived near the downtown area and had several favorite bars and a bookie he liked to visit. Not infrequently I accompanied him on his walks.

So one day our walk took us past the site where construction workers were installing the foundation for Northwestern Bell’s new building. The location was adjacent to Dodge St. between 18^th and 19^th streets. For protection of pedestrians who passed by, the construction contractor built a covered walkway. The walkway was made from rough cut lumber and had several openings where people could observe the construction. These “windows” were up too high for me to see through, but my grandfather lifted me up. I saw a pile driving operation for the first time. It was a noisy operation, but I found it interesting. Figure 1 below shows the crane that would be rigged to drive the piles and stacks of piles.

Figure 1: Crane Used for Pile Driving & Piles

Grandfather then went on to explain the process and purpose of the piles. As he explained it, the piles would be driven into the ground and filled with concrete. This would allow the building to be supported by bedrock below the softer soil.

I was so impressed that I decided I’d like to build a pile supported structure. I didn’t have a lot of material to work with though. Back then fruits were shipped in wooden crates like the one in Figure 2. There was a corner grocery store at the end of the block on which I lived. From time to time I acquired empty crates from this store. I liked building things from the wood. After learning about pile foundations from my grandfather I decided to try building my own pile supported structure. Although I didn’t have enough wood to construct a building, I did make a platform like that shown in Figure 3.

I cut strips of wood from the boards I took off the long sides of the crates. These were my “piles”. I drove them into the ground in the front yard. The end pieces of the crates I set on top of the piles. These end pieces were not secured to the piles beneath so the resulting platform was pretty unstable. I think my dad made me remove my platform a few days later because it was a nuisance.

Figure 2: An Orange Crate

Figure 3: My Pile Supported Floor

Sometime after seeing the Northwestern Bell construction site, I had to have my tonsils removed. As I rode in the cab with my mother, we passed by the site on the campus of Creighton University where the Mary Rogers Brandeis Student Center was under construction. I heard the now familiar sound of piles being driven into the ground.

Sometime after that I lost interest in piles. However that was not my last encounter with a pile driving operation.

In 1976 I graduated from the University of Nebraska with a bachelor’s degree in Civil Engineering. I had chosen to study civil engineering for several reasons. First, I wanted to be an airline pilot. A cousin of mine who was actually my mother’s first cousin was a pilot for the now defunct Eastern Airlines. I was worried that my eyesight might not be good enough to be a pilot. I knew I had a problem with depth perception. My cousin gave me advice that went something like this”

“Mike, there are eye doctors that specialize in keeping pilots qualified. I would, advise you to get a college degree of some kind. The airlines will try place pilots who are no longer qualified to fly elsewhere within the company if they have other skills.”

Taking his advice I decided to go get an engineering degree. I figured I ought to study aeronautical engineering. The University of Nebraska didn’t have an aeronautical engineering program; but an advisor assured me that with a mechanical or electrical engineering degree I could likely find employment in the aerospace industry. Since resident tuition is usually much cheaper than nonresident tuition, I decided to go to college in Nebraska. My advisor also explained that the first two years of courses were pretty much the same for all engineering students. I enrolled at the University of Nebraska at Omaha although they didn’t offer a mechanical or electrical engineering program.

I had trouble mastering mechanics of materials, dynamics, thermodynamics and electric circuits, so I questioned if I should even consider pursuing an engineering degree.

During the summer of 1972, however, I was offered a position as an engineering aid with the Bureau of Land Management in Canon City, Colorado. I assisted the District Engineer surveying various civil engineering projects like small dams, roads, and fence lines. I though the engineer I worked for had a great position. He did field work in the beautiful mountains of Colorado during the summer and in the winter he worked in the office designing projects for the upcoming construction season.

There was one type of project that really spurred my interest in civil engineering. He designed small dams to store water for use by wildlife and livestock. He was able somehow to predict whether there would be sufficient water to fill the dam to the desired capacity. This required the knowledge of a science called hydrology. I wished to learn more about applying this science to engineering problems. After getting a “D” in mechanics of materials for the second time and barely getting a “C” in electrical circuits in the semester following my experience in Colorado, I decided to study civil engineering.

After receiving my degree I first went to work in Nevada in the hydrological section of the Lower Colorado Regional Office of the U.S. Bureau of Reclamation. Unfortunately I had trouble applying hydrological techniques to practical problems. Subsequently I worked for the U.S. Geological survey in Portland, Oregon and the Puget Sound Naval Shipyard in Bremerton, Washington. In 1983 I took a job as a construction inspector at Fort McCoy near Sparta, Wisconsin.

It was at Fort McCoy that I encounter pile construction again. One of the projects I had to inspect was the replacement of two bridges constructed of timber with ones to be constructed primarily of concrete.

Figure 4: Drawing Showing Bridge Components.

I now had the opportunity to see the pile driving operation up close

Figure 4 shows the main components of the type of bridge that was being used to replace the old timber bridge. As shown in the figure the foundation consists of steel H piles with a reinforced concrete cap. Figure 5 shows more detail on what H piles look like after they’ve been driven into the soil. Although Figure 5 is not taken from the project I inspected, the pile group is very similar. I include it to show the shape of “H’ piles.

The strength of a single pile to support its share of the weight of a structure is dependent on the length of the pile, the friction between the pile and surrounding soil, and the bearing capacity of the material below the tip of the pile. These same factors also provide resistance to pile driving. The resistance to pile driving is overcome by the force imparted to the pile as it is being driven by hammer of the pile driver. As the pile is forced into the ground this resistance increases until it reaches a point to where the pile is said to be in “refusal”. At this point the hammer impact force is insufficient to overcome driving resistance; it is often associated with an equivalent blow count of approximately 10 blows per inch. That is, ten blows of the hammer will only drive the pile another inch into the ground. When the driving has reached this point, theoretically the pile has reached the required strength to support its share of the weight of the structure.

My job as a construction inspector was to observe the pile driving operation to see that the contractor followed the proper procedures. In particular, I was to determine when each pile had been driven to refusal.

So, approximately 28 years after my first observation of a pile driving operation, I was doing it again. The difference now was that I was doing it up close and getting paid for it.

Figure 5: A Line of Driven “H” Piles

Of course the type of piles used in the pile driving operation I observed as an engineer were different than those I saw with my grandfather. Having researched the method of construction of cast in place driven concrete piles I will describe it.

The type of pile used for constructing a cast in place concrete pile consist of a steel tube (looks like a pipe) fitted with a steel head. See figure 6.  The steel head can be fixed to the pipe if the casing is to remain in the soil or at can be detachable to allow for extraction and reuse of the tubing. It may be necessary to use a pile where the casing is left in place if groundwater conditions might adversely affect the placement of concrete or the soil surrounding the pile is too soft or pliable to serve as a form for the freshly placed concrete. I don’t know whether the casings for the piles used for the northwestern Bell building foundation were left in place. Nevertheless, the process for installing the piles is the same except for the extraction phase.

Phase 1: The pile head is placed on the steel tube casing and the pile is driven to refusal. Figure 6 shows the pile in place ready for the next phase.

Figure 6: Pile Driven Into Soil

Phase 2: Concrete reinforcing is lowered in to the casing. Figure 7 shows the reinforcing in place.

Figure 7: Pile Concrete Reinforcing Lowered into Casing

Phase 3: Concrete is placed in the steel tube.

Phase 4: The steel casing is extracted. Figure 8 shows the pile after concrete placement.

Figure 8: Pile with Concrete in Place

I don’t know how my grandfather, a machinist with only an eighth grade education gained his knowledge of pile construction. I suspect it was just by observing the process and asking questions. Nevertheless, you can see how this experience had an impact on my life.