Ask PDCA Library

Does The American National Standards Institute (ANSI)/American Society of Safety Professionals (ASSP) have a standard for installation & extraction of piles?

The standard, ANSI/ASSP A10.19-2017 "Requirements for Pile Installation and Extraction Operations", is a solid resource for conducting safe operations in the installation and extraction of piles, whether concrete, steel, timber, sheets, composites or synthetics.  This standard establishes safety requirements for the installation and extraction of piles during construction and demolition operations and is designed to prevent injuries and illness to persons exposed to hazards associated with pile driving and extraction operations.

You can purchase a copy of the standard here

Hard copy and electronic version: 
List Price: $110.00 - $140.00
ASSP Member Price: $95.00 - $125.00

The PDCA can provide input to future revisions to ANSI/ASSP A10.19-2017 in areas that relate to requirements found in the new OSHA crane standard and new general technology in the pile driving industry. 
Individuals interested in providing comments,
please contact the PDCA office at 904-215-4771

Is there a standard method of verifying 
"pile plumb"? 

Question:
"I am having an issue with my pile driving contractor regarding the methods used to verify "pile plumb". I am looking for a general practice in testing a pile's plumb. The contractor has indicated they only use the 'survey method' to calculate slope. The geotechnical engineer on the project indicated that a four-foot level must be employed to verify plumb or the bottom of the pile may have 'kicked'.  Is there a standard method of verifying the plumb of the pile? "

Responses are from PDCA members:
Some contractors in the Pacific Northwest use a six-foot-long level, instead of a four-foot level. This provides a little more accuracy when checking for pile plumb.

The same method applies to pile drivers in South Carolina additionally, just measure from the end of the level over to the pile to get your variance from plumb.

You can also use a four-foot digital level, which is what a New Jersey contractor does to verify pile plumb. Some four-foot digital levels will actually give you a LCD readout of the degree of plumb.

I am unfamiliar with the term "survey method" to calculate plumb. My experience is similar to that of your geotechnical engineer, where a four-foot level is used to determine plumb deviation from vertical (on H-piles). The level is set against the pile and plumbed vertically, and the gap between the pile and the end of the level not touching the pile is measured and reported, along with the compass direction of the lean (e.g., ¼-inch in four feet SW). Obviously, the longer the level, the more accurate the plumb deviation determination will be. Whatever method is used, the results must be compared to specified plumb deviation limits.

I received your question about verifying the angle of inclination on piles being driven on your project. It is common practice in the Gulf Coast Region for pile driving inspectors to require piles be checked with a carpenter's level, once placed, and prior to the start of actual driving. Because both timber piles and H-piles can have deviation over their length, the longer a level is, the more useful it can be. Timber piles can be the most difficult to have truly plumb at start and finish because of their irregular shape. H-piles can have a "sweep"/deviation in trueness due to improper handling and lack of support in shipment and handling.

All piles can be best controlled by the use of a positioning device at the base of the leads/pile gate. Additional alignment aids can be provided between the base of the hammer and the ground for maximum control of the pile during driving. It is not unusual for piles that have been verified as "plumb", prior to commencing driving, test as being out of plumb or off-position at final penetration. That phenomenon is explained by eccentricity of the pile/deviation from trueness, and differences in drive resistance encountered by the pile across its diameter. The worst-case scenario occurs when part of a pile's cross-section encounters debris, and influences the pile to move away from the additional resistance.

Do you know the impact of pile installation on soil mechanics and good ways of assessing it?

Wave Equation Analysis Programs
End of initial drive vs. re-strike after seven days
Author: Bill Marczewski, P.E., M.ASCE, BSM Engineering, Inc.
Published Q1 2014
Discusses the impact of pile installation on soil mechanics and ways of assessing it

Basic soil mechanics and pore water pressure
At the most elementary discussion of soil mechanics, one should recall and remember that individual soil particles in contact with each other can only transfer shear forces from one adjacent soil particle to another. This relationship is generally depicted at the micro-soil structure level. The space between adjacent soil particles is referenced as the 'void' area and is comprised of air when there is no ground water present, and is water when ground water is present. When water is present in these voids, or in the "pores" of the soil structure, we must consider the effects of pore water pressure changes during pile driving operations in order to understand our onsite observations.

Pile installation and pore water pressure
During pile driving operations, with both vibratory and impact hammers, the adjacent soil is disturbed in the localized region of the driven pile causing the pore water pressure to increase between the soil particles at the micro-soil structure level, thereby decreasing the available skin friction to resist pile installation penetration. When the soil disturbance from pile driving installation at the End of Initial Driving (EOID) has ceased, the pore water pressure in the soil begins to decrease or 'soil setup occurs' as the soil attempts to restore itself to the at-rest condition prior to disturbance from the pile driving operation.

The time it takes for the soil to fully recover from pile driving operations, or for the pore water pressure to fully dissipate, is often thought to be around seven days, or 168 hours, but is not exact. Many of the conditions associated with the change in the pore water pressure of soil during pile driving have been observed by pile contractors and monitoring inspectors for years. The value of these observations need to become a baseline of understanding for all parties involved in design and installation support leading to capacity determination of a driven pile. In doing so, a competitive edge will be established by those obtaining clarity in this simple, but often confusing, subject.

EOID versus Beginning of Restrike (BOR)
EOID is often associated with an increase in pore water pressure and a decrease in available skin friction to resist pile penetration during initial installation. This ease of installation is often associated with not achieving the required ultimate axial pile capacity. However, this is not an accurate representation of the soil resistance that is available, or the ultimate capacity available. The maximum soil skin resistance available can only be determined when the pore water pressure in the soil dissipates over time, or maximum at approximately seven to 10 days after EOID.

The value of accurate pile installation records is paramount to properly determining the final ultimate axial capacity. Termination of pile driving for equipment breakdowns, pile splices, shift changes, etc. should be clearly noted in the monitoring logs as well as the time associated with allowing the pile to sit undisturbed until initial pile driving is complete. For long piles driven to depths beyond 100 feet in order to meet minimum embedment criteria, the effect of pore water pressure and driving delays associated with pile splices or stops in driving should be carefully considered.

Piles driven to minimum embedment depth but not achieving the required ultimate pile capacity is a common observed installation condition, and to some degree, this condition should be expected. Such pile installation conditions warrant the need for the contractor to restrike these piles at varying time intervals after EOID. The time intervals between restrikes can be random but should be accurately reported.

Increased capacities resulting from BOR taken at two hours from EOID have yielded significant increases in ultimate axial capacity at some projects, while others have not been observable until 48 hours after EOID. In general, design engineers like to see the blow count associated with BORs occurring at the seven-day interval (168 hours) after EOID. The time associated with the seven-day BOR is often thought to be the time it takes for the soil pore water pressure to fully dissipate and allow the soil to restore itself such that increased axial capacities can be observed during pile restrikes.

Wave Equation Analysis Programs (WEAP) and predicted capacities
It should be understood that the observed axial capacity at the EOID will not, and should not, match the predicted capacity of a WEAP analysis that utilizes soil setup resistance models having time intervals greater than zero. A time interval of zero is the same as the EOID condition. When using the proprietary computer software program GRLWEAP™ produced by Pile Dynamics, Inc. it is important to recognize that these WEAP analyses are produced using a default time interval of 168 hours (seven days) to report their predicted ultimate resistance capacity. With this being the case, you should not expect a WEAP prediction using "setup time = 168 hours" to correlate with the onsite observed conditions associated with EOID, or "setup time = 0 hours." Because this time variable can be manipulated, it is recommended to perform multiple WEAPs associated with EOID (t=0 hours) and other time increments pertinent to the specific project needs.

WEAP predictions should be compared against actual driving conditions to validate their usefulness in pile capacity prediction. The use of wave equation analysis is a powerful tool to support driven pile installation projects and when incorporated with high strain dynamic testing using a Pile Driving Analyzer (PDA) to verify hammer performance can lead to exceptionally efficient pile installation projects.

Is properly illuminated pile driving SITES at night inherently more dangerous than A daytime operation?

Pile driving is inherently dangerous by the nature of the work being done and the number of people working in unison to lift, locate and drive piles.

As the typical job site is often crowded and the ground uneven, vision and communication between the crew is critical. Even well lit job sites at night reduce vision, causing hidden dangers to exist. Glare from artificially lighted job sites is an additional issue that can cause temporary loss of vision during pile driving operations.

There aren't many pile driving personnel that would not consider working at night to be more dangerous than working during the daylight hours. Additionally, production at night is lower, and damage to pile driving equipment is higher.

In regard to the question: Is properly illuminated pile driving at night inherently more dangerous than daytime operations?


The answer is yes. USACE specifications for hazard safety analysis (HSA) require nighttime operations to be very specific concerning work procedures, hazards associated with nighttime work and illuminating the site properly. They will check to ensure there is sufficient light (at a minimum) prior to night work starting. Any work performed at night has additional safety hazards regardless of the artificial illumination.

The hazards can include (this list is not exhaustive):
  • Shadows created by locations of lights
  • Reflection/glare from lights
  • Eyes adjusting to dark and light changes (moving in and out of the lighted areas)
  • People moving into the light from the dark (public, vehicles, crews, etc.)
  • Noise from the light plans (if gas powered)
  • Crews adjusting to working at night
  • Crane operator adjusting to lights, especially looking up at tip of boom
  • Weather affecting the work area
Contractors have performed many projects with nighttime pile driving operations and regardless of the amount of illumination, the aforementioned issues and the hazards they create have to be recognized and mitigated accordingly. The work can be done safely; the crews and teams just need to be aware of the additional hazards and have an extra eye out for each other.

200 years & less than an inch of corroded material...

It can take 200 years for piles in the ground
to corrode one-eighth of an inch

QUESTION 1:
In disturbed soil (the top 10 feet) there is available O2 that is not present in undisturbed soil (below 10 feet). How long can this top 10 feet be considered as "O2 available" for a higher corrosion rate? I am assuming 15 years?

QUESTION 2:
Within this top 10 feet there is a water table that fluctuates throughout the year. Does this slow movement of water continue to feed the "available O2," or does this water table not affect the "available O2?" (soil ph="6.8)" (resistivity =5,600 ohm-cm) 

The following quotation from an article refering to a presentation by
Melvin I. Esrig, Ph.D., P.E., "Dr. Esrig then discussed commonly seen corrosion rates for various environments based on oxygen content and water conditions. The rates, from low to high, are typically quoted in millimeters per year in the published literature. The published rates vary between 0.015 mm/yr to 0.075 mm/yr. Based on the rates presented, it was estimated that it may require between 90 and 200 years for 0.125-inch of corrosion to take place for piles in water and in the ground, respectively, to occur. Based on these findings, the common engineering solution for sizing piles is to simply add this 1/8-inch to the thickness of the pile wall (A. Filotti added emphasis).

It was also found that the rate of corrosion might not be constant over the lifetime of the structure. The corrosion process often results in an oxidized protective layer that prevents further exposure to oxygen and decreases the corrosion rate. In mechanically active environments, such as marine wave action conditions, the mechanical action causes the protective layer to be removed and can maintain or increase the corrosion rate.

A case study by M. Romanoff of the National Bureau of Standards was presented wherein 40 piles were driven into various soil conditions and were allowed to corrode for as much as 40 years. It was found that the predominant form of corrosion was pitting, which was concluded not to be of engineering significance.

Dr. Esrig then went on to present various other case studies to illustrate the effects of low acid environments (US Steel Research Laboratory), high salinity environments (LNG facility in Cove Point, Md.), stray electric current (Jacob K. Javits Center, Manhattan, N.Y.), and H-piles near waterfront conditions (North Hudson Hospital & Watermark High Rise, North Bergen, N.J.).

The preferred engineering solution is to avoid the problem if possible. This is usually not a viable solution and the most common solutions include the use of concrete piles or adding protective coatings. Jacketing piles in concrete can be a solution if the conditions allow. Cathodic protection often results in high initial project costs and the need to be maintained. The most common solution is to add 0.125-inch of steel to the thickness of the piles. This may add costs to the project if it has not already been accounted for through driveability analyses or lateral capacity requirements. A brief discussion on the New York City Building Code requirement for all pile steel to be designed assuming a yield strength of 36 ksi or less, regardless of the true material strength, often results in piles that may have reserve capacity to account for 1/8-inch corrosion."

Reference and Credit to-
American Society of Civil Engineers 2005-2015
Full Article Referenced
When is Corrosion of Piles
a Potential Engineering Problem?

Do You Know The pros and cons of using test piles as production piles?

Using probe and test piles as production piles is the normal practice within the driven pile industry.  There are several reasons for using test piles as production piles in a foundation system.  On the other side, there is very few reasons that you may not want to use the test piles in the foundation.

You would want to use test piles as production piles when:
  • If you use test piles as production piles, you have an economic advantage, because ultimately you are using fewer piles and therefore lower your material costs for the project
  • If the test piles reach or surpass the engineer's criteria for design loads, they should be satisfactory for production piles.  If they hold a lower load, they can still be utilized.
Reasons to not to use test piles as production piles could include:
  • If the pile is damaged during lateral testing
Other considerations when considering using or not using test piles include:
  • If using a PSPC concrete pile as the test pile in a production pile location, order a long length in case the pile does not achieve the required load, in which case you can continue driving; steel can be added on by welding additional lengths
  • Drive several probe piles in permanent locations and then test the pile with the least number of total hammer blows or with the lowest final blow count
In conclusion, there are valid reasons to use test piles as production piles given the right circumstances.

Pile Driving Detail for the General Public

The following is a detailed description that could be used to help inform the general public about the role of piles and the pile driving industry.

Archeologists have determined that driven piles have been used for thousands of years. Who knows how the ancient Egyptians figured it out; maybe they were trying to push their beach umbrellas into the sand and discovered that it takes more force to install the pole farther. Longer poles (piles) offer greater resistance and support. A beam placed across the top of several piles can support a lot of weight. The Greeks and Romans utilized driven piles to support bridges, aqueducts and other structures in poor soils, many of which are still in use today. The Roman Circus in Arles, France was built on 30,000 driven piles and modern archeological excavations have discovered the piles are still in good condition and supported their loads for about a thousand years, until the structure fell into disuse. While other historic examples are abroad, throughout Europe, the basic principles for piles are still used today.

Why do we use piles?
Commercial buildings, bridges and skyscrapers are large structures that need a lot of support. Usually, the soil conditions will not support the structure's weight and deep foundations are needed. When you walk across a field, sometimes your foot stays right on the surface. Ten feet further along, your foot sinks in the mud; different soils, different support.

How do we install piles?
Pound them in! This simple procedure is the most efficient installation method.
We call it "driving the pile" or "pile driving." By observing how fast the pile goes down, we can determine how much weight the pile can support.

What about noise and vibrations?
Unfortunately, driving the pile produces noise we can hear and vibrations we can feel.  This noise is no greater than your lawn mower or a motorcycle. It will drop off quickly as you move away from the pile hammer. In the vast majority of cases, noise is not a problem.

The vibration that you feel can be measured with seismic instruments. A general rule of thumb is that ground vibrations are not significant at distances greater than the length of the pile being driven. In other words, if the pile is 50-feet long and your building is more than 50-feet away, significant vibrations are unlikely to occur. If your building is relatively close, or you have a concern, ask the pile driving contractor or engineer to measure the vibrations at your building to assure they are below safe industry guidelines. The professional engineer who designed the pile has analyzed the soil conditions and has selected a pile type that should not damage surrounding structures.

Advantages of driven piles
One of the advantages of pile driving is that it is relatively fast. This reduces the overall nuisance to the neighbors.

Who is the pile driving contractor?
Pile Driving Contractors are experienced professionals, typically with many years in the deep foundations business, whom tend to be sub-contracted on a job as they have the equipment and experience to drive a safe and secure deep foundation.  The typical goal for all deep foundation projects is to complete the job quickly and efficiently; at the same time, overly satisfying all parties involved in the project, including the local residents.

Do you Know How to Preventing Premature Wear on Hydraulic Hoses?

Preventing Premature Wear on Hydraulic Hoses
Author: The Hose Company
Published Q4 2014

Being smart about hydraulic hose use is a good way to extend their life and prevent failure


Many factors reduce the life of hydraulic hose assemblies. Construction teams should take the proper precautions and conduct regular inspections of the hoses and fittings as a job starts, works and closes.

Manufacturers of equipment using hydraulic hose and fittings will make selecting the proper hose for your application easy. However, as a safety check, you should understand the min/max of working pressure specific for your equipment; purchase the correct hose with an inner tube specific for the fluid moving through the hose, and the internal and external temperature requirements for the location and equipment. Operating below minimum temperature, twisting, pulling, kinking, crushing or abrading the hose will decrease the life of the hose and may cause failure.


Different hydraulic hose series and sizes have a SAE-required minimum bend radius specification. This simply means that flexing the hose less than the specified minimum bend radius can drastically increase the possibilities of the hose failing and reduces the hose life cycle. Even though there is a minimum on bending of the hose, there is also a maximum. The hose should not be bent in more than one plane and, if the hose follows a compound bend, it should be coupled into separate segments or clamped into segments.

When installed on equipment, the hose should not touch or rub any moving components to prevent external friction to the cover of the hose. Not only does friction cause premature wear but also torqueing the hose ends during the installation process must be completed properly. A hex wrench needs to be held on the bolt near the crimped side of the fitting (to keep the fitting from twisting) while torqueing the female or male swivel to its proper torque specification. If not completed properly, the hose crimp may twist, damaging the internal construction of the hose. Even though it can be difficult at times, especially on the larger sizes and high-pressure hose assemblies, it cannot be stressed enough how important this procedure is to the life of your hose. Special tooling may be required to do this properly. One of the best tools on the market for this is called a RIDGID® Model No. 25 Hex Wrench, 20-inch, one-inch to two-inch pipe capacity. If your team does not have two of these in their toolbox, you may want to consider adding them.

In specialized industries, such as pile driving, drilling, oil and mining, there are times when hoses are used in ways they are not designed or rated. Special ingenuity is required, especially when multiple hoses are banded or bundled together and hung in the air as a requirement for the application. There are no hose types specifically designed for this type of application. Therefore, all small details are crucial, like having the weight equally distributed. If not properly banded or bundled when hung, one of the larger hoses could begin to carry more weight than the other, and it will most likely cause major hose failures. Failures include the fitting being pulled off the hose from the additional weight and large amounts of pressure. Not only is this damaging to the hose but it can cause serious injuries.

If your application requires quick disconnect fittings, it is important that when connecting them together both the coupler and the nipple are cleaned and free of dirt and debris. Not cleaning the quick disconnects will damage the body of the fittings, not allowing them to lock together properly and can allow contamination inside your equipment's hydraulic system. 

It is vital that the hose be allowed to keep its functionality as a "flexible-pipe" and not be restricted from changing in length when under pressure. If it can be avoided, it is recommended that hoses for high pressure and low pressure not be crossed or banded together to avoid friction since each hose will expand in length at different rates. Hoses should be kept away from hot parts to increase their life cycle. However, protective insulation may be used in high ambient temperature areas.

The last and easiest thing that can be done to increase your hose and fitting life cycle is to avoid contaminates by using caps/plugs. Not only should you clean your quick disconnects, but you should always clean and cap your hoses when removing from equipment.  You really do not want any dirt to get inside. 

requirements or standards for brackets on the back of a crane to hold...

What are the requirements or standards for using brackets on the back of a crane to hold power units or compressors? Are brackets allowed if you have an engineer's stamp or manufacturer's approval?

Many pile driving contractors attach a power unit of some type to the rear of a crane. This is done for convenience purposes only, and should never be done to increase the lifting advantage of a crane.

Power units or compressors mounted to the rear of cranes in the south Louisiana region were normal back "in the day." Recently, that trend has run into severe scrutiny by agencies such as OSHA, insurance companies providing contractor coverage, client safety staff/engineers and crane manufacturers. Crane manufacturers are concerned about the method for securing the bracket to the crane structure, additional loads and wear imposed by the weight and its eccentricity on the crane. Safety concerns from the other groups are centered on the balance and load handling capacity of the crane, and the security of the attachment to the crane frame.

The mounting platform should be designed by a registered professional engineer, and obviously the "wet" weight of the power unit and support must be known. It is also wise to consult the crane manufacturer generally they are interested in providing support and pertinent information. Most will assist in the plan and preparation of the crane, (possible counterweight reduction, for example) with a main concern being rearward stability especially when tramming the crane onsite.

Although the practice continues, prudent contractors are now involving the crane manufacturer in the method used for attaching the bracket and getting their approval in advance. Other groups are likewise concerned and carefully reviewing the crane's weight handling capacity based on the additional counterweight effect of the compressor mounting to the rear of the crane.

You may have heard the phrase "we do this all of the time," and that may be true. The crane user should have some back-up information to justify their particular application. Prudent piling contractors should do their due diligence.

In New York, in order to use the bracket on the back of a crane to hold a power unit or compressor, two conditions have to be fulfilled:
  1. Have an engineered solution for the bracket, signed by a professional engineer
  2. Obtain the crane manufacturer approval for the proposed solution
If you are going to mount a power pack or compressor on the back of a crane, the two items noted above should be the minimum before making the modification.

Remembering OBAMA's 2016 OSHA fines InCREASE

The 2016 federal budget bill raises OSHA fines

In November 2015, President Obama signed the 2016 federal budget bill. This is not something that the average person delves into, especially the private sector, like PDCA members who are doing their best to secure, manage, complete and get paid for work so their business can exist.

In the new budget bill, there was a small provision that could have a giant financial impact on PDCA members.  The impact comes in the form of adjustments in OSHA fines. The U.S. Department of Labor's Occupational Safety and Health Administration (OSHA) has not made any increasing adjustments of fines since 1990. The new 2016 federal budget directs OSHA to raise fines to keep in line with the Consumer Price Index, which has risen approximately 82 percent since 1990. In addition, OSHA has been directed to make annual adjustments based on the index changes.

What does this mean to the construction industry?
OSHA fines will steeply rise in August 2016, when the directive goes into effect.  Some examples include the change in fines for a "simple" posting requirement that previously would cost a company a maximum fine of $7,000; now, the cost could be $12,740 ($7,000 x 1.82 = $12,740). While this is a significant increase and could have a major impact on many small companies, it is nothing compared to a fine for "willful violations." If OSHA determines an employer knowingly failed to comply with a legal requirement or acted with "plain indifference" to employee safety, the fine will be devastating. For instance, a willful violation penalty is currently $70,000. Given the new directive, this violation would now be $127,400. With the construction industry leading the way in fatalities, safety will now be more important than ever.

PDCA suggested that all companies review your safety manuals to make sure they are up-to-date, ensure that your policies are being conveyed and implemented from the top down, educate your employees and make safety a critical pillar of your organizational culture.

PDCA's "Toolbox Safety Review" booklets on many construction topics, including:
Crane, rigging and signaling
Overhead power lines
Welding, cutting and brazing
Marine construction
Compressed gases
Heat illnesses
PPE
Hazard communications
Fueling
Flammable and combustible material
Fire prevention
Fall protection
Material handling
First aid/BBP
Industrial trucks (forklifts)
Housekeeping
Back injuries
Lightning
Vehicle safety
Road work safety
Ladder safety
Cell phone use

Copies can be obtained by calling the PDCA office at 904-215-4771.

FHWA Foundation Load Test Database

FHWA Deep Foundation Load Test Database

The Federal Highway Administration (FHWA) Office of Infrastructure Research and Development (HRDI) would like to announce the availability of the updated FHWA Deep Foundation Load Test Database (DFLTD v.2). Instructions on how to install and use the DFLTD are provided in the associated User Manual (FHWA-HRT-17-034). The DFLTD v.2 contains over 1,600 research quality load test results on various types of piles and drilled shafts.

The database is relational where the records can be queried in numerous ways to include foundation type and size, subsurface soil information and location. The functionalities included in the software will help facilitate best practices and greater reliability in the design and construction of different deep foundation elements. The DFLTD v.2 can be used by federal and state agencies, universities, consultants and contractors, design engineers and planners and research and development professionals.

The DFLTD v.2 replaces the previous DFLTD (v.1) developed at TFHRC to meet current operating system requirements and also adds new information on over 150 load tests on large diameter open-end piles (LDOEPs). The DFLTD v.2 was developed as part of an ongoing research study to evaluate the bearing resistance of LDOEPs and calibrate resistance factors for both static and dynamic analysis methods. The DFLTD v.2 and the user manual can be downloaded from the Turner-Fairbank Highway Research Center website using the following link:

Is there an industry standard for allowing a crane's running block inside a lead while operating a diesel hammer on a batter pile?

To answer this question, it is first necessary to understand what occurs during the driving of piles with diesel hammers inside "U-shaped" leads:
  1. The hammer is guided by an open frame system with cross bracing in the lead system.
  2. Initiation of the firing sequence on diesel hammers is performed by engaging a mechanism on the back of the diesel hammer, into the ram and lifting the ram with the mechanism. As the mechanism must release its attachment to the ram in order for the ram to fall and begin the injection and firing of diesel fuel, the device is normally referred to as a "trip mechanism."
  3. Safe/proper operation of a diesel pile hammer is for the crane operator to manipulate the position of the trip mechanism during the process of driving piles.  The design of diesel hammers is based on the trip mechanism not being at the top or bottom of the frame during hammer operation. 
Because of the difficulty of handling pile hammers on batters, most diesel hammers driving batter piles can be equipped with a hydraulic cylinder and external hydraulic power unit to lift and release the ram. This lessens the difficulty of handling the diesel pile hammer and maintaining the required batter angle during operation.

As the crane must be secured to the pile hammer during the driving process and the nature of pile driving dictates constant movement of the hammer (in response to pile movement and resistance), positioning a crane block, especially while on a batter, inside the leads is not recommended. The block will have a tendency to contact the structural members of the lead system as the load on the handling line varies.

It is recommended that diesel hammers be equipped with hydraulic start/trip mechanisms for batter applications. The greater the batter and the heavier the ram for the particular diesel hammer, the more critical this recommendation becomes. 

It is also recommended that a handling sling (with no overhaul ball) connect the diesel hammer to the crane's load block for all operations. The length of the sling is based on keeping the crane's load block out of the lead's framework. 

Pile Driving Contractors Association, aka PDCA, member companies with significant experience driving batters as severe as 12-on-12 with both diesel and hydraulic hammers have been reported.  Complete lead systems that address the complications of handling line direction while on batters for swinging leads and a variety of fixed leads are available through PDCA associate member companies, including USA Manufacturers of impact diesel hammers, hydraulic impact hammers (HIH), leads, spotters and other equipment.

What are pile driving cushions?

There frequently exists some confusion about pile driving cushions; what they are, the purpose they serve and whether they are needed. To answer these questions, it is necessary to understand that we can summarize this as there two different types of cushions used in pile driving hammer cushions and pile cushions. All cushions are similar in that they act as shock absorbers to protect elements of the driving operation and they are consumables. Beyond that, they are different, depending on their type and what they are intended to protect. 

Hammer Cushions
Hammer cushions are provided primarily to protect impact hammers from destructive forces during operation and to permit the maximum amount of useable energy to be transmitted to the pile while preventing damaging energy from being rebounded to the hammer. With only a few exceptions, almost all impact hammers air/steam, diesel and/or hydraulic hammers require the use of cushion. Manufacturers, in the design of their hammers, make engineering decisions regarding the amount and type of cushion required for the various models in their product line. Specific types and sizes of cushioning, once determined, are provided for in attachments to the base of the hammer, directly under the point of impact and usually in conjunction with the drive cap design and attachment. Using the wrong size or thickness of hammer cushions or poor cushion maintenance can cause considerable damage to the hammer and, in extreme cases, expose the crew and immediate area to the possibility of injury or damage due to failing (and falling) pieces of the hammer. Hammer cushions are consumables and over time get "used up," failing to provide adequate shock absorbency. This is due to compression of the cushions' materials or due to charring or burning. For this reason, cushions should be checked frequently for condition and changed when necessary.

Pile Cushions
Pile cushions, as the name implies, are primarily protection for the pile specifically, precast concrete piles. Pile cushions protect the ends of the pile from spalling damage that would occur when the hammer blow impacts the pile. The cushion also provides attenuation of the blow during driving, reducing tensile forces acting on the pre-stressed pile as it is driven. Pile cushions are provided in various thicknesses and sizes to accommodate the pile and the drive cap, and are determined by the driving conditions as dictated by the size of the hammer and the soil. As each project is different, so are the cushions unique to the particular project at hand. Cushion requirements are best determined by wave equation analysis, which takes into consideration the particulars of the pile, hammer characteristics and the soil composition. Materials used for pile cushions are most frequently plywood or hardwood. Many engineers prefer and specify the use of plywood due to the consistency of the manufactured materials. As in the case of hammer cushions, pile cushions are consumables and lose their effectiveness during driving. For this reason, many specifications and the "PCI recommended practices" recommend the use of a new cushion at the start of driving of each pile. When compared to the cost of the pile they are provided to protect, the cost of the cushion is usually very small and it is frequently false economy to try to use a cushion beyond its useful life. The possible damage to the pile, cost of a re-drive or unscheduled downtime changing a cushion on a partially driven pile are all reasons to be conscious of the condition of the cushions when driving concrete piles.
Additional information

Both hammer cushions and pile cushions have been subjects of previous articles in PileDriver magazine. The article on hammer cushions can be found in the Summer '04 edition and the pile cushion article in the Winter '05 edition.
Back issues of the PileDriver magazine can be found HERE.  

Additionally, manufacturers and some associate members of PDCA can be sources of information about cushions. Many of these can also be found in the "Members" section of the website or in your PDCA Membership Directory.

Have you ever experienced a problem with jetting concrete sheet pile in dense sand?  Any solution?

Problems with jetting concrete sheet pile in dense sand
Published Q1 2015
Author: Andrew C. Mannino, PMP, STS, Manson Construction Co.

Question:
"Have you ever experienced a problem with jetting concrete sheet pile in dense sand?  What was the solution? Has the answer ever been less flow or less jet pressure? Or is it always more flow and more pressure eases installation but makes sheets wander?  Have you ever simultaneously driven and jetted concrete sheet pile? Have you ever mixed air in with water jetting?" Question sent in via Ask PDCA

Answer:
Although I have never jetted concrete sheet pile in dense sand, I have jetted concrete piles into dense sand on Long Island, N.Y. The primary issue we experienced was from over jetting to try and achieve the specified tip elevation. The jetting process in sand forces the materials to segregate between the sand and stone that makes up the stratum. Once the sand is displaced or suspended out of the "pile pocket," you wind up trying to jet into gravel material, which is virtually impossible no matter how much flow or pressure. We learned this by jetting the pile as far as it would go into the bottom and then trying to lift the pile (all while jetting) and then lower again into the jetted hole. Instead of getting the pile to go deeper, it wound up being the opposite. Each re-jet made the pile settle higher and higher.

Eventually we decided to jet the pile as far as it would go and then driving it (pneumatic hammer) to tip elevation or refusal (whichever came first). Because the material was in fact jetted, it made the driving easier and we achieved tip elevation most of the time. The project was a bascule span bridge with 300 sixteen-inch square concrete piles (90 to 130 feet) under each concrete tower (600 total).

In closing, jetting only works in soft materials or sandy materials. If the stratum is a combination of one of these and larger gravel materials you have to be careful not to over jet and separate the material. The sand acts as the "slurry" and allows the jetted pile installation process to work. Once you remove the "slurry" you are left with just the stone or gravel. My experience is no matter how much pressure you can create, it is almost impossible to jet a pile into gravel.


Driven piles are smart for deep foundations in brownfield areas

Brownfield Areas old industrial sites that harbor near-surface contaminated soils and groundwater can be a challenge to redevelop. Many of these sites can be found along waterways in areas where commercial development is profitable and desirable. When deep foundations are required for these new commercial developments, driven piles make an excellent option.

First, with driven piles there are no spoils. Contaminated soil stays in the ground. There is no expensive disposal, special handling or treatment of contaminated material required.

Second, if driven piles have to be driven through contaminated groundwater into a bearing stratum below, research has shown that the driven pile does not create a path for the contaminated groundwater to follow it downward. As each pile is driven, it displaces soil. This densifies the surrounding soil. This is particularly effective in cohesive soils that are often relied upon to confine contaminated groundwater and keep it separated from uncontaminated groundwater below. Driven piles not only improve the ground beneath the new structure but they make it more difficult for groundwater to move through the densified material.

For more information on this topic please read, "Installation of Driven Piles in Brownfield Sites" by Dr. Gordon Boutwell et al.
A copy can be found here
PRESENTATIONS

What is a best practice to shackle pin the attachment between the crane line and the leads?

The Proper Way to Secure a Shackle Pin

Questions:
What is the proper way to secure a shackle pin as the attachment between the crane line and the leads? Can you weld the shackle pin (or bolt), or does this weaken or fatigue the metal? Is there a "best practice" in the industry for addressing this question?

There are two ways to secure the shackle pin to the shackle bolt, nut and cotter pin, and mousing.

A bolt, nut and cotter pin, such as a Crosby shackle, will solve the problem quickly and efficiently. This type of shackle is intended to be used in a more "permanent" situation, and the attaching point to the leads is a good example.

Caution pay close attention to how the shackle is orientated. It is possible that the hoist line used for the pile hammer may rub, and then possibly wear the cotter pin, causing potential damage to the hoist line or the cotter pin (key) being dislodged over time. A documented inspection of the leads, hammer and all of the associated rigging is a must. If you cannot lay the leads down for an inspection, get some quality binoculars, an aerial lift or possibly a drone to survey the shackle condition and the leads and the boom while you're at it.

Another option is to "mouse" a screw pin shackle. It, too, is an effective way to secure the pin. Caution must be used to ensure the shackle does not rub on the leads and ultimately cut the mousing. Again, daily inspection is key.

One must never weld to a shackle or hook.
The welding process will change the properties of the drop forged heat-treating process and lead to a failure.
Even a "tack weld" is forbidden.


economical way to extract steel pipe piles?

What's the most economical way to extract steel pipe piles?

You are awarded a job on an old project worksite. The site has a few small-diameter driven steel pipe piles (12 inches or less) with the longest pile being 100 feet long. The piles need to be removed. What is the most economical way to do this?

First, if available, you may want to look at the way the piles were initially installed and the soil boring logs for the site. This will help in identifying the weight and possible condition of the piles, as well as the installation method used. The soil boring logs will identify the soil type, which could reveal the level of difficulty you may encounter while extracting the pile.

With these variables known, you can properly apply the correct system to use for extraction purposes. Most commonly used for extracting pipe piles is a vibratory driver/extractor, with a hydraulically operated clamping device. However, extracting the pile with a vibratory hammer will likely involve a slight and fairly simple modification to the existing pile.

The modification involves cutting a "slot" into the pile. The slot should be cut on both sides of the pile 180 degrees apart and approximately 18 to 24 inches in depth.  The purpose of the "slot" is to allow a 0.75-inch minimum flat steel plate to be inserted into the slots. The plate needs to extend the same distance above the pile and should be no less than 1.5 feet in length for 12-inch diameter piles.

Once the plate is in place, it must be welded to the pile using a double fillet "T" weld on both the outside and inside of the pile. This will allow the vibratory hammer clamp jaws to bite on the entire surface of the plate.

Extraction can now begin.

What if the skin friction is too great for the extractor to pull the pile? One recommendation is to "straw" the pile out. To do this, you must drive or vibrate a heavy wall pipe that has an ID greater than the OD of the existing pile. Drive the larger pile down and over (or around) the existing pile. This method should break the skin friction from the existing pile, allowing you to extract the pile with the vibratory hammer using the method described above.

Fall Protection Requirements

Fall Protection Requirements

The USACE EM 385-1-1 Safety and Health Requirements Manual (2014) has a fall protection requirement that you need to be aware of, prior to the start of any USACE project you may have on the go. This revised edition went into effect September 2014 and should be referenced in your contract documents. Fall protection is covered in Section 21. It would be a safe bet that the same fall protection requirements would have to be met if working at a Naval Facility (NAVFAC) as well. This is applicable for any type of project you may be performing if fall hazards exist.

Be aware Section 21.C.04 requires that the contractor's Competent Person (CP) shall have a minimum of 24 hours initial fall protection training, and have annual two-hour refresher thereafter. At the time of publication, this requirement had an 18-month grace period, which has since expired (March 2016). All 24-hour training shall be documented and conducted by a Competent Person trainer. You will most likely get this training through a third party source, and it is strongly recommended that the training be verified as "compliant" with the EM 385-1-1 requirements.

Additionally, you must have a written, site specific fall protection plan, which must include an emergency rescue plan/procedures for any work performed on USACE/NAVFAC projects. If you are considering using an outside local emergency services or onsite in-house professionals (the base EMT/rescue), you need to engage them prior to the start of the project and ensure that they have the necessary training and equipment required to perform a rescue i.e., from piling leads, which requires rescue from height training. If you plan on performing self-rescue using your own competent or qualified persons or subcontractor services, they must also have the same level of training and performance capabilities.

You should have a written fall protection and emergency rescue plan for every project you work,
not just for a USACE project.