Terra Terrabilius. At the time of Christopher Columbus, mapmakers  did not have GPS and thus the information on their maps was very limited – pretty much to what the captain of a recent voyage was able to relate.   So the map maker would draw the land and islands that were known and then beyond that would inscribe “Terra Terrabilius” meaning the fear of the unknown.  Maybe that is term that should be used in underground excavation today.

Underground excavation is HIGH RISK. It is because, in part, of the difficulty in defining the precise nature of what is underground and the character of the material that is to be encountered . . .and the frequency of what is to be encountered.  In other words, information or inadequate information is a major contributor to the risk of an underground excavating contractor.

  • There are about 25-35 million miles of underground utilities and a demand for more and more
  • There are about 2.5 million miles of pipelines
  • The soils have been in the making about 4.5 million years and have not done so uniformly.  The character of subsurface conditions (density, thickness, 
    compressibility, stability,  water, environmental conditions, archeological finds, etc) can vary frequently throughout a construction site.  And often do.
  • Unexpected variances cause stop and go, delays, loss of productivity, schedule slippages which are damaging to the contractor, the owner and the public alike.
  • DOT has a concept termed Every Day  Counts. That should be the bumper sticker for all projects, but the monsters located below the surface often gobble up those days.

As a result of the risks encountered in this netherworld, Owners  have had a tendency to shift (or attempt to shift) these risks to contractors, either by largely doing nothing during the preconstruction phase and placing this duty on the contractor, or through contract clauses which disclaim any responsibility or liability for any information furnished (if any) , exculpates the owner from responsibility for such information and then goes on to deny any liability for damages for delay or impact to productivity.  However:

  • Owners are learning that such risk shifting clauses are not necessarily iron clad shields against liability
  • Further, Owners are realizing that legal clauses do not assure project success.
  • And seldom reduce the cost of these projects;  contrarily, they often add to the cost and schedule impacts.
  • When conflicts over money arise, relations often become adversarial.  Adversarial relations do not lend themselves to successful projects.
  • And they are beginning to realize that the power to improve project success lies in a more collaborative approach with the owner/geotechnical scientist/design engineer/contractor functioning as a metaphorical knight on a white charge to fight the dragons of the underworld.

This article will deal with the various approaches to underground construction and present trends in delivery systems. It is the thesis of the article that an early on collaborative approach to investigation and design with constructionese as well as designees is the approach with the highest probability of delivering a successful project.  The Report on Shaping the Future of the Construction Industry by the World Economic Forum, states that “collaboration is, or should be, a hallmark of the construction industry itself. The Industry’s future success will rely largely on an effective collaboration among all the stakeholders.”

Note: This article is the foundation for a short power point to be presented at the UCT’s annual conference in New Orleans, Louisiana on January 30, 2018.  Neither the power point nor the article can be exhaustive and the reader must take this in consideration when perusing the article.  A separate article will later be written highlighting the key technology that should be considered in the pre-construction phase.  For example, the full range of technology such as BIM, AI and others are deliberately omitted from this particular article but will be subsequently be covered.

Nature of Projects. 

There are four very distinctly different types of excavations but all have much in common.

  • Open Cut (Cut and Cover)
    • Utilidors (such as DisneyWorld)
    • Joint Trenching
    • Common Corridors
  • Trenchless
  • Immersion (Subaqueous)
  • Tunnels
    • It is worthy to review the Code of Practice for Risk Management of Tunnel Works prepared by the International Tunneling Insurance Group in 2006.

But then excavations may be small enough to accommodate spread footings (and the issue may be whether to form or whether the soil is strong enough without forming).  Still takes information doesn’t it?

What they have in common is risks associated with the unknown. That risk (the risk of meeting budget, quality and schedule goals)  diminishes in direct correlation to preconstruction  discovery providing engineers with adequate information for designing the most effective and safest structure, and contractors adequate information to develop prudent means and methods and rates of production so  the work can be priced with reasonable contingencies.    And thus Risk Management is an essential ingredient of Excavation Management.  And information  management is an essential ingredient of risk management.

The Role of the Owner

The Owner is the front-end driving force who  can choose among these pathways in managing risk.  They are:

  • The Pass the Buck Approach:  Have conducted some level of subsurface investigation but attempt to avoid any liability for the resultant report through:
    • Disclaimer Clauses
    • Exculpatory Clauses

The problem is that often these clauses do not provide the owner an ironclad shield against liability, do not aid in producing successful projects, and are claims contagion. ( See an interesting article by a Canadian firm entitled Risk in Underground Construction,  on this subject)

  • Conduct NO pre-bid site investigation burden of underground exploration and risks on the contractor.
    • The practical problem with this approach is that some level of discovery is required for the design engineer to develop an effective design and for the contractor to provide a price based on selection of proper means and methods which is reasonable and not loaded with contingencies.
  • Develop the Best Approach to achieve Project Goals for All the Parties:  In either a design-bid-build or design build delivery system, develop a risk sharing approach aimed at a process best suited to project success instead of simply legal prophylactics. This is the approach primarily discussed in this article.

In the latter  approach, the level of success is augmented through a collaborative, team approach of the parties, from the outset of the project through its completion. 

Shift the Risk to the Contractor.                                                            In this approach (usually a design-bid-build delivery system), the risk morphs into a legal/contractual approach.  The contract will contain disclaimer and exculpatory clauses (legal jargon for saying that the Owner is washing its hands of any liability for any conditions on or below the surface, including utilities or difficult subsurface conditions . . .no matter what they are.  In this case, it is up to the contractor to ferret out the conditions on its own, and then attempt to develop a price which has a “windage” contingency low enough to get the job and high enough to keep it from going bankrupt it major difficulties are encountered in the subsurface conditions.

Such contracts also generally contain a No Damages for Delay Clause which provides the Owner is also not going to be liable for any cost to the contractor for any delay or interference caused by the Owner for any reason, including Change Orders.

Often these arrangements create adversarial relationships between the owner and the contractor due to disputes over the claims and quality issues. Decision making is often dilatory and lacking in objectivity. 

No research yet has shown that attempts to transfer unreasonable risks have improved project success.  And when issues are left to judges and juries to decide instead of the parties in real time on a project, the cost and schedule overruns have already occurred, the toothpaste is out of the tube.

And for these very valid reasons, Owners are beginning to re-think delivery systems, trending toward an approach which is most likely to produce project objectives (and framed in the concept of Every Day Counts – fostered by DOT but a concept that should be embedded in all construction projects.) The industry is weary of overruns, and disputes, and is looking for ways to improve budgets, schedules and the elimination or major reduction of claims.

Prudent Pre-Construction Phase – Best Practices

In either a design-bid-build or design-build, the elements of the “prudent preconstruction” should be the same. Risk Management is Information Management. And Risk Management Begins with Early On Management with the Owner being the driving force. 

The Owner will do these things at the outset:

  • Put together a qualified team
    • COLLABORATION.  This is the time to begin a collaborative team.  By collaboration is the commitment of each team member to work together to work together to make input, identify issues and conflicts which they work through in real time.  The process can and should begin at the outset of the project and continue throughout.  Exculpatory clauses and unreasonable risk shifting are the enemies of collaboration and are generally not consistent with best practices leading to project success. A collaborative approach can and should occur in a design bid build or a design build.
    • Selection of team members should match complexity of project.  Big Dig was “Too Big to Succeed”, so the owner must select team members whose track record is one of success on like projects, and who have a strong management plan for handling risks. 
      • Excavation is not for the faint hearted or inexperienced.  The degree of expertise should match the characteristics and complexity of the project.
    • A pre-qualification issue should be the condition of the equipment to be used.  A major pump storage became almost a year behind simply because the heavy excavation and  construction equipment was largely worn out, having just been brought over from another project the contractor had just completed.
  • Commit to a strategy for project success which involves information management, accountability to the party which has the greatest ability to control the issue, a collaborative approach between the parties which continues throughout the project, a process for dealing with variances and conflicts which do not slow momentum and which do not impair the team approach.
  • Commission the Geotechnical Engineer to conduct a thorough Site Investigation (Again, the nature of the project and potential soil conditions will dictate the degree of investigation and the requirements of the Geotechnical Baseline Report it will prepare.
    • Above ground conditions
      • Including potential interferences, hazards
    • Utilities Location using ASCE 38-02 as guideline
    • Below ground conditions
      • Nature and Characteristics of Soils
      • Density/thickness
      • Compressibility/Strength
      • Water
      • Extent of Conditions
      • Environmental Conditions, toxicity
      • Safety issues both to contractor and third parties and potential damage to property, and ventilation
        • Ground Protection
        • Shotcrete
        • Rock bolts
        • Attention to portal design
      • Interpretations and expectations of the information
      • Quantity Surveys
    • Recommend feasibility of excavation methods (such as open cut or trenchless, e.g.)

Note: For Tunnel Excavation, one may wish to refer to Joint Code of Practice for Risk Management of Tunnel Works in the UK issued by the UK Tunnelling Society and the Code of Practice for Risk Management of Tunnel Works prepared by the International Tunnelling Insurance Group

And in addition, the GBR should contain:

  • Method for Working with Contractor During Project. A Communication Protocol.
    • A recommended process for “looking ahead for subsurface conditions” so that variances can be anticipated
    • A process for handling disputes
  • How to Process Changes
  • The requirement for an as-built
  • Recommendation as to Type of Excavation (See Appendix B)
  • In a design-bid-build, it is strongly urged that input from a construction contractor is important.
  • If this is a design build contract,  the owner has two options:
    • The first is to do no geotechnical investigations and transfer the total burden of investigation for both design and construction purposes to the design build contractor  In such a case, the contractor, bidding without geotechnical information, must price a pig in a poke both as to design and to construction means and methods as well as pricing. For example, how can a contractor choose cut and cover versus trenchless without knowledge of the nature of the materials to be encountered?
    • The second option is to conduct is to conduct adequate information as to subsurface  so that the proposing contractors have enough data and criteria to at least develop a proposal that has some basis in fact, instead of total conjecture.   But in due course, the contactor must do an adequate subsurface investigation on which to base design and means and methods.   
  • The National Research Council, in making recommendations for the excavation of the Super Collider stated that a geotechnical Design Summary Document should be prepared, with no disclaimers, and included as a contract document.

NOTE: The GBR is the baseline for the contractor to be able to have adequate information for preparing an estimate (based on its determination of necessary means and methods, and its productivity forecast – rate of production) with a reasonable contingency.  This protects the owner against inflated estimates from which the contractor may gain a windfall profit and the contractor against a financially disastrous project due to failure to estimate conditions far more onerous than it anticipated.  If the actual conditions materially differ from those characterized in the GBR, the contractor is entitled to additional cost, based on a method set forth in the document (e.g. unit prices).  If the conditions do not vary, the contractor is totally responsible for the cost of and schedule for excavating the materials (quantities and conditions) indicated in the GBR, unless the Owner makes changes to the project.

It is emphasized that the reduction of uncertainty means the reduction of risks to both parties; the management of information is the ultimate management of risks.

The Design Phase. 

Whether or not it is design-bid-build or design-build, the elements of design will remain pretty much the same. In design build, changes and claims will diminish, and as both design and construction are under one contract with fewer delays due to change orders and dilatory decision making, schedules are generally enhanced.    Best Practices will dictate under any delivery system,  that a geotechnical engineer be commissioned to perform the functions enumerated above and the GBR will become a baseline document for both the designer and the basis of estimating and means and methods selection by the contractor.  So the DESIGNER will perform the following functions:

  • Comply with appropriate design standards and codes
  • Perform the design typically in the three phases and obtain input and approval in each phase before proceeding to the next
  • Using input from the GBR, the Owner and the Contractor, decide on the nature of the excavation (open cut, trenchless, immersion, tunnel, joint pipe, utilidor)
    • This includes mapping of existing utilities and known structures which could interfere with excavation
    • Some reports indicate that a utility is being damaged every 6 minutes (about 700,000 a year), so location and prevention of damage is obviously a major priority.
  • If open cut trench  or tunnel, develop design for ground support, potential for both walls and overhead material to cave or fall in (provide  requirements for shoring, shotcrete, rock bolts, etc) 
  • Provide requirements for blasting if indicated.
  • Provide requirements for water management if indicated.
  • Provide requirements for safety of personnel and third parties, and prevention of damage to property.
  • Work with contractor to develop reasonably attainable construction schedule.
  • Constructibility review among the designer, geotechnical engineer and contractor. The geotechnical engineer and the design engineer should be involved with the construction team throughout the project.
    • The engineer may specify that RCPs be laid “in the dry”, but a contractor, considering the nature of the terrain and flow of water, may realize that it would be commercially impractical to do so.
    • The construction schedule should be a product of the owner’s needs, the nature and risks of the project, and the input of the team, including the construction contractor.
  • Communication among the parties  is among the highest priorities and it is recommended that a communication protocol be developed and incorporated into the documents.
    • Timeliness of communication and decision making (including response time)  is of the essence
  • The contract should provide a framework that allows problems to be avoided, solved – or when a full solution is beyond the means of the manager – managed in such a way the project can proceed. (The NRC Recommendations Report for the Super Collider)
  • So the Design Phase is more than some drawings and specifications.  It is that, but it also is an opportunity for the team to develop a real game plan for most effectively and cooperatively estimating and constructing the project, with processes for maintaining momentum and achieving win-win results for the team members.

The Contract Document

The contract should embody the work products developed by the Geotechnical Engineer and the Designer, as set forth above.  In addition:

  • Partnering is a concept which facilitates the parties working together and may be a requirement set forth in the contract.
  • Dispute Resolution Boards (DRBs) on larger projects are often good vehicles for overseeing progress as well as facilitating the resolution of disputes and maintaining momentum
  • Statements of responsibility and accountability should be set forth clearly.  It is preferred that geotechnical information prepared during the preconstruction phase be set forth as a contract document with no disclaimer (as recommended by the NRC), but if not, then the contract should make it unequivocal that the burden and risk of all underground is that of the contractor.
    • Nevertheless, it is recommended that a geotechnical engineer be assigned and a protocol set forth for working through any issues which might arise.
  • It is the recommendation of the author that no damage for delay clauses NOT be included in the contract and that the owner take accountability for delays and impacts for which it is responsible.
  • All contracts should require the contractor to produce at least the following management plans.  On larger projects, it is also recommended that there be two Notice to Proceeds: the first an administrative one in which the contractor prepares and submits all its deliverables for review and or approval, and has its own construction team ready for mobilization.  The second is the construction notice to proceed after all the planning has been done and the team is prepared to then hit the ground running.  NOTE: These deliverables are not just some documents required by the contract, but the opportunity to truly think out how to best manage the project, deal with risks and improve productivity.  That is what PRE-PLANNING is all about.
    • Safety
      • There is a great sign  often seen in neighborhoods: “Drive as Though Your Children Are Playing Here” and one at highway construction: “Drive as Though Your Father is Working Here”.  On excavation projects, manage safety as though the one you love the most is working here!
    • Quality – including test procedures
    • Special plans (such as shoring, blasting, de-watering, traffic control, dust control, environmental control etc)
    • Supply Chain (Purchase Agreements, POs, Logs, Submittals, Tracking Procedure)
    • Schedule (Recommend that consideration be given to Linear Scheduling.                 
    • Communication Protocol
    • Protocol for working with Engineer and Geotechnical Engineer.

The  Pre-Bid Conference

The pre-bid is more than just another damn meeting.  It is a way station – an opportunity to pause –  and to attempt to clarify the meaning of the geotechnical and contract documents.

For example, in a Midwestern case, the log borings showed “water at” a given elevation.   The contractor, believing this meant static water, estimated on that basis: that is, the water was simply going to be where it was indicated and was not under pressure.  However, when he excavated, it turned out that the water came shooting up like Ole Faithful.  It was artesian water (water under pressure).  The contractor said that in the industry, “water TO” meant water under pressure and “water AT” meant static water.  The engineer said it was quite the contrary. How nice it would have been for this simply phrase to have been clarified prior to the contractor estimating.

On the USBR irrigation ditch from Los Banos, California to Gilroy, rock known as metagraywacke was noted in the soils report.  The  Contractor,  seeing a drill and blast specification, bid on the basis that the rock could be blasted and the debris hauled away.  Instead, when the metagraywacke was exposed to water and oxygen, it became like a syrup and almost had to be dipped out by a ladle.  Again, a meaningful pre-bid conference could have been used to explain the weird characteristics of he material and have prevented a major claim.

Of course, many contractors will say they are afraid to ask questions because of the presence of competition and they may give away an edge in doing so.  But they may also give away much of their company assets if they significantly underestimate when a simply question could have avoided the catastrophe.  That is a business  decision and a function of the degree of blind risk a contractor is willing to undertake.  Our call is to err on the side of beating the competition on the basis of the company’s competence and knowledge and not on a gamble.

The Pre-Con and Partnering

The pre-construction conference is sometimes held at the same time, or about the same time as the partnering conference.  Not all projects have partnering programs; and many such programs are not necessarily value added.  But the concept is basically this: the team members commit to collaborate – to work together – to attempt to foresee difficulties before they become large and to work together to resolve them with the best possible resolution. 


Pre-construction is the most vital phase for increasing the probability of success of any project, and especially underground excavation.  It is because both  successful design and construction are the children of adequate information (and prudent expectations and probabilities based on that information).  Legal disclaimer and exculpatory clauses do not provide information, only tend to move conflicts from the construction site to the courtroom site.

This industry, fractured and disjointed, is beginning to see the value of a collaborative and shared risk approach as the best practice in achieving project goals for all the stakeholders.  And when “all the stakeholders” is used, that includes the manufacturers and engineers providing technology which is improving productivity in leaps and bounds.

Because momentum is so important to the success of a construction project, developing an approach for the team to work through a variance in the soil conditions is essential.  It can be one of two approaches:  a legalistic one in which the parties are simply interested in protecting their tails or a solution oriented one in which the parties are interested in developing an expeditious one which keeps the momentum rolling.  Collaboration is the way to go: disclaimers and exculpatory clauses and adversarial relationships are not.

APPENDIX A – Underground Testing Technology as well as the old tried and true  can greatly assist in reducing excavation risk through the use of various devices for exploration and testing.  For example:

  • Ground penetrating Radar
  • Acoustic (Sonar)
  • Test pits
  • Trenches
  • Test Holes
  • Aland augers
  • History of other excavations in the area
  • Laboratory Testing

It serves the industry well to check on what other nations are doing in the area of underground testing.  The Japanese, for example, seem to be on the forefront of this area.

Appendix B – The Trade-off Between Open Cut and Trenchless

Trenchless is certainly soil dependent, preferring sandy, well  graded  gravelly sandy, or clay to more difficult conditions, such as rock or other onerous materials.  Minimal above ground or surface excavation is required.

Open Cut has more steps in the process, and under certain circumstances may be more costly as a result. 
But open cut is not soil dependent in that it can handle rock and other difficult materials.  In open cut these steps are required which trenchless does not need  necessarily  be bothered with:

  • Road detours
  • Traffic Control
  • Shoring
  • De-watering
  • Backfilling – Borrow Material
  • Compaction – Testing

And in trenchless, safety to the work force and third parties should be minimized.