Working Platforms for Large Rotary Foundation Rigs – for Safety Terence P. Holman, Ph.D., P. E . and Richard Marshall, CHST June 15, 2017 Topic Outline

• General Introduction to Working Platforms and Issues • Applicable Codes, Statutes, and Standards • Geotechnical Engineering and Site Preparation Issues • Contractual Language and Team Obligations Safe Working Platforms for Specialty Equipment

• Safety – A safe site is easier to manage. There are fewer opportunities for working areas to be unsafe. The piling crews work safer. A reduction in the possibility of an accident will have a positive effect on your Workers Compensation statistics.

• Quality – by installing the pile correctly the first time, we save time and cost of unplanned rework and we can start to develop the ‘get it right first time’ theme.

• Production – if you have taken proactive steps to have a safe site producing a quality product you will achieve your production targets.

• Risk of Failure – The cost of a rig going over is incalculable. The list starts with accidents and injuries and possible fatalities, work being stopped, loss of equipment, employing lawyers, being sued, physical and mental stress for everyone involved, negative publicity, possible prison sentences. General Introduction to Working Platforms and Issues Every year, piling rigs, rotary rigs, and cranes fall over or are subject to near misses due to Working inadequately prepared or maintained site Platforms ‐ surfaces –all such incidents involve potential fatalities or serious injury to operators, ground The Problem crews, and typically cause extensive damage to equipment. What is a Working Platform ?

A working platform is the foundation for a drilling or piling rig that may weigh anything from 5 tons to 375 tons and all of the ancillary equipment that may be used on the platform to service the rig.

Modern equipment is becoming increasingly heavy, often with higher centers of gravity, to cater for the demand for deeper and larger diameter foundations to take higher load capacities, combined with the need for more environmentally friendly installation techniques Drill Rig Stability – Fundamental Mechanics

Machine’s Center of Gravity Forces

Drilling Tipping Axis

Machine’s Center of Gravity Forces

Tipping Axis Drilling The closer the rig’s center of gravity is to the tipping axis, the less stable the rig becomes. By necessity, this system must include the dead weight of tooling (out in front of the rig) and other forces such as pullback forces. Drill Rig Stability – Tramming/Transit

The red arrows represent the force of gravity on the drill rig.

When tramming down a slope, the weight is further away from the tipping axis, which increases the risk of an overturn.

Tipping Axis Tipping Axis It should be everyone’s aim to minimise accidents on construction sites and to prevent any injuries to personnel and the possible long term implications of such injuries.

Delays to projects caused by accidents to skilled operators and the downtime while equipment is being repaired are likely to be extensive. There is sometimes a lack of understanding with project management and supervisory staff regarding the importance of preparing a safe working platform capable of supporting the equipment to be used, and disagreement as to whose responsibility it is to design, prepare and maintain such a platform throughout the course of the project. Ground Conditions

You must have a level, stable work platform to operate from. . . period New pile driving rig sinking due to poorly compacted platform Ground Conditions

The contractor must know the ground bearing pressures and distributions their rig(s) or mobile cranes will generate in the configuration they will be used.

This information may be supplied in the operators manual or by calling the manufacturer. It’s their responsibility to know this information, and only work from a stable, level platform that will support the rig or crane. Codes, Statutes, and Standards Fatal Accident in Toronto ‐ 2011

In this terrifying accident, a young backhoe operator was killed when the large, heavy, high center of gravity drill rig trammed into a soft area of the site. The rig immediately went out of level, and toppled over – without any means for the operator to stop it from happening. Working Platforms

ONTARIO REGULATION 213/91 CONSTRUCTION PROJECTS ROTARY FOUNDATION DRILL RIGS Effective July 1, 2016 (Excerpted Highlights)

156.3 Sections 156.4 and 156.5 apply when a drilling operation at a project uses a rotary foundation drill rig that can exert a ground pressure of 200 kilopascals or more under its tires, crawlers or outrigger pads in any configuration, including during its operational activities. Working Platforms

156.4 (1) Before a drilling operation described in section 156.3 begins, a professional engineer shall, (a) design a supporting surface for the drill rig in accordance with good engineering practice to adequately support the drill rig during all drilling and drill rig set‐up activities; (b) designate and design a path of travel for the drill rig to use on the project to ensure the path of travel safely supports the drill rig; and (c) prepare a written report described in subsection (2). O. Reg. 345/15, s. 19. Working Platforms

• 156.5 (1) Before a drilling operation described in section 156.3 begins, the employer responsible for it shall, • (a) develop a drilling procedure for the drill rig in accordance with subsection (2) and have it approved by a professional engineer; and • (b) have a copy of the drilling procedure provided to, and reviewed with, the workers engaged in the drilling operation. Working Platforms

(3) While a rotary foundation drill rig is in service at a drilling operation described in section 156.3, the employer responsible for the drilling operation shall ensure that, (a) the drilling procedure described in subsection (2) is implemented; and (b) the drilling procedure is followed by the workers engaged in, and in the vicinity of, the drilling operation. The Solution

In Europe and Australia, members of the Piling Federation created a Working Platform Certificate to be prepared for ALL platforms that piling rigs are required to work from. This may involve multiple certificates on some projects such as bridge sites.

The Certificate confirms that the working platform has been properly designed and constructed in accordance with the design, and that it will be adequately maintained to ensure that the platform integrity.

The Certificate requires the signature of the Principal or Main Contractor on the project and must be handed to the Piling Contractor before piling or other foundation work commences on the site. Working Platform Certificate

• The use of some form of Certificate is a way of increasing the awareness of working platform safety and the importance of maintaining the platform in good condition throughout the course of the contract.

• The Federation of Piling Specialists in the UK introduced the Working Platform Certificate and the system is now in extensive use throughout the UK. It has proved to be a highly effective way of overcoming the problems that existed prior to its introduction.

• Reported incidents have decreased significantly.

• The Certificate does not state who should carry out the design work but the members of the Federation strongly recommend that qualified geotechnical engineers (i.e. third party) be engaged to undertake the work. Ground Conditions

A10.23 6.1 The project constructor shall:

6.2 Ensure that drilled shaft equipment not be assembled or used unless the ground conditions on which they are moved or placed are firm, drained (except for marshes/wetlands) and graded to the extent that the equipment manufacturer’s specifications for adequate support and degree of level are met. Geotechnical Engineering and Site Preparation Issues Geotechnical Elements of Working Platforms

Stable uniform Stable trapezoidal Unstable triangular pressure distribution pressure distribution pressure distribution Geotechnical Elements of Working Platforms

RR RL RR RL RR RL

FR FL FR FL FR FL Drill Rig Stability‐Bearing Pressures Vary with Rotation about Pin Geotechnical Elements of Working Platforms • Problematic Subsurface Conditions DRILL TOOL AXIS AND LOAD 3 to 5 ksf Track Bearing Pressures

WORKING PLATFORM AGGREGATE

SOFT TO FIRM FINE‐GRAINED PIPE

STIFF OR DENSE Geotechnical Elements of Working Platforms • Bearing Capacity (actually matters for once) • Local shear and punching shear control Okamura et al (1998) Meyerhof (1974) and Meyerhof and Hanna (1978) Ground Conditions – Piling Rigs This is an example of a constructed and maintained working platform –in this case for a dedicated drill rig to operate from. This is the beginning of a safe and productive working platform for a heavy rotary foundation drilling rig or mobile crane to operate from. Design Options for Subgrade Stabilization

• Design of Undercutting and 3 to 5 ksf Track Bearing Pressures Replacement • What thickness of dense granular soil or aggregate is needed? WORKING PLATFORM AGGREGATE Hu • Empirical methods for more stable situations (e.g. 2 ft, etc.) • Quantitative methods for less GG or GT favorable situations (i.e. bearing SOFT TO FIRM FINE‐GRAINED SOILS capacity) T mob • Do I need geosynthetics (GG or GT) for tensile reinforcement?

• Potential reduction in Hu STIFF OR DENSE SOIL • Possibly needed for BC stability Design Options for Subgrade Stabilization • Design of Crane Matting • Timber and steel mats are “flexible” and have defined structural properties and capability to handle shear and bending • Objective is to control load distribution to the subgrade, but flexible nature needs to be understood • Reference Duerr, D. (2015). Mobile Support Crane Handbook

Typical Cantilevered Mats Double Mats, Perpendicular Single Mat Contractual Issues

• Who owns the Site and subsurface conditions? • Who owns the responsibility for the Working Platform? It’s a temporary construction measure but critical for site safety… • Who owns the responsibility for maintaining the Working Platform? • What are the roles and responsibilities of the Specialty Contractor, General Contractor, project Foundation Engineer, and the inspecting Geotechnical or Foundation Engineer? ACCESS & UTILITIES:  A firm, level and dry drill pad of ____ feet by ____ feet must be provided at each drilled shaft location.  A work trestle shall be constructed (by others) at all shaft locations that is capable of withstanding the weight and reaction force of the drilling and oscillato r equipment. __ each reaction piles must be driven at each shaft location for the Contractual Issues oscillator to sit on with the capacity to withstand reaction forces during extraction. The reaction piles must be tied back into the main trestle. The trestle and finger(s) must withstand the reaction forces of the oscillator. The reaction forces have been supplied on a separate attachment within this proposal. A minimum ___ ton crane shall be used at each shaft location. The dimensions of the dig crane and oscillator have been attached separately within this proposal along with other pertinent info pertaining to trestle • Evolving proposal and contractual language design. Work trestle must be of sufficient size to provide unimpeded access for MDCI’s operations at all times. The trestle must allow for two cranes to be working on the finger from Specialty Contractors  A/ main minimum trestle finger at the and same main time. trestle width of 40’ is required with enough space for equipment to safely maneuver from main trestle onto each finger.

• General consensus within ADSC is that TECHNICAL:  The trestle must be constructed so as that it will not deflect more than __ inches in any direction while the drilled shafts are being installed. Owners and CMs should be responsible for SPECIFIC EXCLUSIONS: cost of constructing and maintaining While the attached Standard Conditions (Rev. 04/15) apply to this project, we wish to specifica lly emphasize the following exclusio ns : adequate platforms –it’s an overall site Safe access/egress including dry, level, firm, work platform for the entire site is required to be prep and safety issue provided by others, including all-weather benches and ramps. Site Access Prepare and maintain clear, well drained, stable, uninterrupted access ways suitable for • Specialty Contractors must provide equipment moving under its own power without sinking or rutting for the duration of the project. Access includes adequate ramps at suitable levels. Access must be available at the time and to the extent necessary complete and accurate details of the to meet scheduled operations. OSHA 1926.1402 applies to the access ways and ramps for our equipment and Purchaser is the “controlling entity”. Our rig with tools weighs ____ pounds and exerts a ground drilling and support equipment to be used pressure of ___ pounds per square foot while moving over a track width of ___ feet. The maximum slope of the access ramp must be equal to or less than __ degrees (___ percent) along the longitudinal axis of the on the project including the bearing drill equal to or less than ____ degrees (____ percent) along the transverse axis of the drill. Access ramps pressures, dimensions and working space must be at least 2 foot above ground water. Working Platform ‐ Prepare and maintain a clear, well drained, stable, level and uninterrupted working required to operate safely. platform suitable for equipment moving under its own power without sinking or rutting for the duration of the project. OSHA 1926.1402 applies to the work platform for our equipment and Purchaser is the “controlling entity”. Our rig with tools weighs ____ pounds and exerts a ground pressure of ___ pounds per square foot during operation over a track width of ___ feet. The maximum slope of the working surface is __ degrees (___ percent) after the mast is erected. Working platforms must be at least 2 foot above ground water. Contacts

Terence P. Holman, PhD, PE Rick Marshall Chief Geotechnical Engineer Director of Safety Turner Construction Co. and Board ADSC: The International of Directors Member for ADSC: Association of Foundation The International Association of Drilling Foundation Drilling Parkway Tower 55 E. Monroe St., Suite 1430 8445 Freeport Parkway, Suite 325 Chicago, IL 60603 Irving, TX 75063 Office: 312.327.2882 Office: 469.359.6000 (www.adsc-iafd.com) Cell: 513.609.1010 (www.adsc-iafd.com) Ground Conditions

If you go to the ADSC website, there is a link to a short video. This video offers a re‐creation of an actual fatal accident –a result of a poor working platform. Reference Material to Assist

The FPS in the UK in conjunction with the Building Research Establishment (BRE) have produced a good practice guide to the design, Installation ,maintenance and repair of ground Supported working platforms entitled “Working Platforms for Tracked Plant”.

In addition the Piling Federation have posted on their web site the following discussion papers from the UK documentation: • Working Platform Design Sensitivity • Calculation of Track Bearing Pressures for Platform design • Rig Loading Spreadsheet • Guide to Hydraulically Bound Working Platforms

There are links to this document and other related information on the ADSC website under the Safety & Updates button Working Platforms

The FPS – Federation of Piling Specialists has developed a “Working Platform Guidance” section which includes a ground pressure calculator for piling rigs

http://www.fps.org.uk/