By Gary Brierley and David Hatem
Many Contractor submittals for design/bid/build tunneling projects are related to how the Contractor intends to create the underground openings inside of which the finished facility will be constructed. As such, these submittals are focused on two distinctly different aspects of construction as indicated below:
How does the Contractor intend to design the temporary structures such as shaft walls, tunnel linings and lateral bracing structures needed to support the underground openings inside of which the finished facility will be constructed?
What are the means and methods of construction that the Contractor intends to utilize in order to excavate and control the ground that will be supported by the above temporary structures?
In general, both of these types of submittals have a significant impact on the successful outcome of a tunneling project as they are intended to explain how the Contractor will actually implement the various design and construction requirements as established in the contract document. However, and as is always the case for an underground project, the ground conditions and ground behaviors encountered during construction will have a significant impact on how those construction submittals are implemented in the field. No other form of construction has such a huge interface between project design and project construction as does the underground, and the primary objective of many Contractor submittals for an underground project is to explain how that interface will be managed on a project-specific basis.
There are two primary objectives that must be accomplished with respect to the construction of the underground openings; i.e., those openings must be made both safe and stable. Project safety is the sole responsibility of the Contractor and all work inside of an underground opening must be performed in accordance with OSHA requirements and with the Contractor’s own safety program. In addition, and as defined by OSHA, the Contractor must have Competent Persons on site who are responsible for making certain that the work is proceeding in accordance with all required safety protocols and the Contractor’s submittal for project safety must make that responsibility abundantly clear.
The primary responsibility for the stability of underground openings also belongs to the Contractor, but, in some cases, those structures are designed based upon design criteria included in the contract documents provided by the Owner. This is especially common if the so-called temporary structures will be incorporated into the finished facility or if construction of the temporary structures could have potentially negative consequences for nearby, existing third-party structures. In general, and in order to accomplish ground stability, the Contractor will be required to either employ or retain the services of registered professional engineers who will design and stamp the plans for the temporary structures and to document how those designs were accomplished in a project submittal. All in all, the above approach to Contractor submittals for a tunneling project is easy to describe but can be exceedingly difficult to accomplish for large, complex underground projects in densely populated urban environments.
Unfortunately, almost all of the published literature about project submittals is related to above-ground structures and are usually referred to as “shop drawings”. For instance, an ASCE publication titled Quality in the Constructed Project defines three classes of “shop drawings” as described below:
- Class 1: Shop drawings for structural components that will become part of the finished facility, and which are fabricated or constructed according to prescriptive requirements defined in the contract document.
- Class 2: Shop drawings for manufactured items that are provided in accordance with performance requirements as defined in the contract document.
- Class 3: Shop drawings for structural components that will not become part of the finished facility, but which are intended to be used for construction purposes such as erection, shoring, formwork, bracing, scaffolding or access.
As can be seen from the above, only Class 3 shop drawings relate in any way to the temporary structures that are needed to support an underground opening, but even this description completely misses the mark with respect to how critically important the temporary structures are for the success of an underground project as compared to an above-ground building. For instance, it is not an exaggeration to say that approximately 75% of the risk and the cost of an underground project is related to the excavation and support of the underground openings inside of which the finished facility will be constructed. It is also important to note, as stated above, that all of the design and construction procedures needed to create those openings are dependent upon one’s knowledge of the ground conditions surrounding those openings as described in the contract document’s geotechnical reports.
In general, project submittals serve as an important building block for project success by providing an opportunity for the Contractor’s design professional to communicate with the Owner’s Engineer of Record (EOR). It is simply not possible to document every detail of design and construction in the contract document, especially for an underground project, and project submittals serve as a mechanism for defining and resolving those details as construction proceeds. For instance,
What does the Owner need to know in order to have confidence that the Contractor is fully aware of its responsibilities as expressed in the contract document?
What does the Owner need to know about the types of temporary structures that will be designed by the Contractor’s design professional possibly in accordance with design criteria provided in the contract document? This need for information by the Owner is particularly important as it relates to potentially detrimental impacts to existing adjacent and/or overlying third party structures and utilities.
And, finally, what does the Owner need to know about how the Contractor intends to actually construct the project? This process is usually referred to as the “means and methods” of construction and this issue is particularly important and controversial with respect to the construction of underground openings.
In addition to the above, it is necessary for the Owner to provide a schedule for when the submittals need to be provided and for how much time the Owner will need in order to review and respond to each submittal. In conjunction with this schedule, the Owner is also required to maintain a log of all submittals in order to make certain that they are being prepared in a timely manner. All in all, it is important for the Owner to identify which submittals are necessary for project success and to make certain that those submittals are being prepared, submitted, and reviewed in accordance with contract requirements.
In order to accomplish the above, the Owner will prepare a project specification entitled “Submittal Procedures” for inclusion in the contract document that explains the procedures for submittal preparation. For instance, a typical Submittal Procedures specification will require the following:
- The Contractor shall accept responsibility for the completeness of each submittal and shall verify that all field measurements, quantities, dimensions, and installation requirements are properly documented.
- The Contractor shall indicate that all of the design and/or performance criteria as presented in the contract document are clearly expressed in the submittal.
- The Contractor shall identify any ambiguity and/or perceived mistake in the contract document and identify the potential impact that those ambiguities or mistakes could have on the production of a particular submittal.
- The Contractor shall be required to retain the services of qualified and registered design professionals to prepare, seal, and stamp submittals containing supporting calculations for the design of the temporary structures.
The Contractor is also required to review the submittal schedule proposed by the Owner and to either agree with that schedule or to propose modifications thereto; especially with regard to the Owner’s proposed timeframe for review and comment. When all is said and done, the proposed submittal schedule must be made compatible with the Contractor’s critical path schedule for construction in order to avoid project delays.
With the above in mind, it is now possible to establish three rather different classes of project submittals that are compatible with an underground project for comparison with those classes listed above for an above-ground structure. For instance, the authors of this paper are of the opinion that submittals for an underground project fall into the three classes as described below:
- Class A – Those submittals that are related to any and all project components intended to become part of the finished facility, and which are prepared in accordance with the “prescriptive” requirements as provided in the contract document.
- Class B – Those submittals that are related to design of the so-called “temporary” structures that are required in order to support the space inside of which the finished facility will be built. In general, and as stated above, these structures must create openings that are both safe for the workers and stable with respect to all existing third-party structures and utilities. Hence, and in many cases, these structures may need to be designed in accordance with design criteria as provided in the contract document.
- Class C – Those submittals that are related to a description of the “means and methods” that the Contractor intends to employ in order to accomplish all of the above, and it is here where the greatest degree of controversy exists as compared to an above-ground structure. For an above-ground structure, submittals that discuss the means and methods of construction typically are not allowed to become part of the contract document and the Owner will, for the most part, avoid providing any comments about the means and methods of construction. However, things are not so simple for an underground project where the means and methods of construction are inextricably connected with most of the project risks and costs and which submittals need to be prepared in accordance with any “performance” requirements as established by the project specifications.
Once the Contractor has produced the submittals as described above, it now becomes the Owner’s responsibility to “review and approve” those submittals and in order to begin this discussion, it is important to define exactly what is meant by the use of the word “approve” in conjunction with project submittals. As defined by the American Institute of Architects (AIA) the use of the word “approve” by the Owner is limited to a determination that the submittal was prepared “in conformance with the design concept expressed in the contract document.” It is also important to note that in performing this function it is proper for the Owner to assume that the Contractor has already checked each submittal for contract conformance and has indicated in writing, that there are no deviations from contract requirements. Hence, the primary objective of the “approval” process as defined by the AIA is to make certain that both parties have a clear understanding of what it means to “conform” to contract requirements.
Based on the above and based on what must be accomplished in order to produce a successful underground project, it is now necessary to discuss the “approval” process as it relates to each class of submittal listed above for tunnels. For instance, Class A submittals relate to any project component that will become part of the finished facility and which must conform to the “prescriptive” requirements as provided in the contract plans and specifications. If that is the case and the submittal accurately accomplishes that objective, then that submittal can be returned to the Contractor with the following language:
- Owner acknowledges that Submittal XYZ has been prepared in conformance with contract requirements. However, contractor is still responsible for the quantities, coordination, and dimensions needed to accomplish the above and for any deviation from contract requirements unless approved by the Owner in writing. The Contractor also remains completely responsible for performing all of the means and methods of construction in accordance with OSHA safety protocols and the Contractor’s written safety program.
If the above is not the case, then the submittal should be returned to the Contractor with notes about what the Owner believes are the issues of contractual nonconformance and with a statement to “resubmit based upon the exceptions noted.”
However, things are not so straightforward for Class B submittals which are related to the design of “temporary” structures needed to support the safe and stable openings inside of which the finished facility will be built. For instance, and in order to demonstrate this situation, let’s discuss a tunnel that is being built for water transmission in an urban area. Obviously, the Contractor must propose to use a support system for the tunnel that is compatible with all OSHA and Contractor-imposed safety protocols, and which is designed by a design professional who is either employed or retained by the Contractor. If all of the above is accomplished in accordance with contract requirements then that submittal will be stamped by the Contractor’s designer and can be returned to the Contractor “with no exceptions noted” since it conforms with the Contractor’s responsibility to have this work performed by a registered professional engineer.
However, let’s assume that a portion of this tunnel is being constructed immediately adjacent to the footing foundations for a historic church and for this portion of the tunnel the contract document provided prescriptive design criteria for the temporary structures. In essence, the contract is now saying that the tunnel must still be made safe, but it must also be made sufficiently stable so as not to cause distress to the church. In this case, the Contractor’s design professional is obligated to take into account specific contract requirements for its design and to design the support structures based on those requirements. In addition, the Owner’s design professional would then be obligated to review that submittal with those requirements in mind and to either approve or reject the submittal based on that review. In either case, however, and as described above, the Contractor now has a set of Class A and Class B submittals that are deemed to be in “conformance” with contract requirements, and which establish how the structures needed both to construct the finished facility and to support the underground openings inside of which the finished facility will be constructed.
Having completed all of the above, it is now necessary to turn our attention to the Class C submittals wherein the Contractor is expected to describe the means and methods of construction that will be utilized in order to excavate the ground, to install the temporary structures, and to control ground movements during the process of excavation and support. The Class C submittals are radically different as compared to anything required for an above-ground structure but are critically important to the successful completion of an underground project. It is also important to note that the types of Class C submittals needed for each underground project will be highly variable depending upon the size, shape, and depth of the opening, on the ground conditions in which the opening will be constructed and on possible third-party impacts associated with those construction procedures.
In general, there are two types of Class C Submittals for an underground project; i.e., the planning submittals and the highly technical submittals associated with various construction activities. With respect to the planning submittals, the contract document generally requires the preparation of one or more Quality Control Plans as listed below:
- Tunnel and Shaft Work Plan
- Water Control Plan
- Inspection and Testing Plan
- Geotechnical Monitoring Plan
Quality Control Plans are related primarily to the planning efforts that are needed in order to make certain that the project is being constructed in “conformance” with contract requirements. As such, the Contractor will be required to indicate how the work will be performed, the qualifications of the persons doing the work, the testing and inspection services that will be utilized in order to show that the work is being performed in a proper manner, and the geotechnical monitoring program that must be implemented in order to show how the ground is reacting to construction operations. In addition to the above, the general contractor is responsible for managing the quality of work performed by its subcontractors and by the suppliers of the equipment and manufactured items needed both for construction and for inclusion in the finished facility.
The above submittals for Quality Control Plans provide the Owner and its design and construction management professionals with an excellent opportunity to oversee and to manage the work being performed. In general, various project specifications will provide detailed performance requirements for accomplishing the work in a proper manner; especially the testing and monitoring service, and the Owner has every right to enforce those requirements unless they are modified by change orders during construction.
In addition to the Quality Control Plans the contract document will also require project submittals for implementing a variety of highly technical project specifications detailing the contractual requirements for the equipment needed to excavate the ground, such as tunnel boring machines or drilling jumbos, and for the construction procedures needed to control and support the ground during the process of excavation such as construction dewatering, consolidation or jet grouting, ground freezing, and secant piles or slurry walls, to name a few. In general, many of these submittals are prepared in accordance with the project specifications by highly specialized subcontractors that perform this work on a regular basis and who have the knowledge and experience about how to adapt each procedure to the anticipated ground conditions.
However, and despite all of the above, these submittals must still be “reviewed and approved” by the Owner’s designers, consultants, and construction management personnel for “conformance” with contract requirements and unlike the Class A and Class B submittals which are based largely on “prescriptive” contractual requirements, the Class C submittals can be based on both “prescriptive” and “performance” requirements; i.e., How does the Contractor propose to actually construct the project? As such, the Owner must employ individuals who are qualified both to evaluate the submittals and to check that the Contractor’s technical submittals are adequate to demonstrate that the work will be performed as required by the contract and this is without a doubt one of the more difficult field activities associated with a tunneling project.
For instance, let us assume that the contract has a plan and a specification for using jet grout blocks immediately adjacent to the launch and receiving shafts for a tunneling project. In general, the contract will contain requirements for the strength and dimensional properties necessary for the completed jet grout block, but all of the procedures required in order to create that block will be provided in the Contractor’s submittal. Upon review, the Owner must decide if the submittal “conforms” to contract requirements and either approve or reject the submittal with comments based on that review.
Needless to say, this review by the Owner must be performed thoughtfully both by the Owner’s design team and construction management personnel with the goal of accomplishing a “meeting of the minds” between the Owner and the Contactor that the work to be performed is appropriate for its intended purpose and for the ground conditions which the work will be performed. Similar submittals will be required for other construction activities such as construction dewatering, ground freezing, consolidation grouting, spiling, rock bolting and a myriad of other construction activities needed to produce a particular underground opening. For instance, and for the jet grout block discussed above, it will be necessary for the Contractor to drill test holes in order to determine the size and continuity of the grouted soil and to obtain samples of the grouted soil in order to measure its unconfined compressive strength.
Hence, and what is most interesting with respect to the above, is that the Owner is not responsible for monitoring every aspect of the Contractor’s means and methods of construction as compared to the results of those means and methods as observed by the project specific inspection, testing, and monitoring procedures established by the Contractor’s Quality Control Plans. In essence, the question that must be answered by the project Owner during construction is as follows:
- Are the means and methods of construction being employed by the project Contractor and its subcontractors actually producing the safe abd stable underground openings inside of which the finished facility will be erected?
If the answer to the above question is yes, then no action by the Owner is required, but, if the answer is no, then the Owner is within its rights to require the Contractor to modify its means and methods of construction in order to accomplish the specified ground behavior characteristics established by the contract document.
In concluding this paper it is necessary to revisit what needs to be accomplished by each Class of project submittal for an underground project as listed below:
- Class A submittals relate to any and all project components intended to become part of the finished facility and, as such, those project components must be provided in strict conformance with the project plans and specifications.
- Class B submittals are related to the temporary structures required to support the underground space inside of which the finished facility will be erected, and, as such, must be constructed in accordance with the plans and specifications provided by the Contractor’s design professional. In some cases, those structures will be designed based upon design criteria provided by the project Owner, but the Contractor’s design professional is responsible for developing and stamping a final design consistent with the specified design criteria and including that design in the submittal. Hence, and in accordance with well-established legal precedents, it is the Contractor that is responsible for making certain that the temporary structures are designed and constructed both in accordance with its approved submittal and in accordance with its Quality Control Plan for health and safety.
- Class C submittals are related to the construction means and methods needed to implement all of the above, and, as such, must be accomplished in accordance with the inspection, testing, and monitoring requirements established by the contract document. It is not possible for the project Owner to observe and monitor every aspect of the Contractor’s performance during construction, but it is possible for the project Owner to check that the inspection, testing, and monitoring programs established by the Contractor’s Quality Control Plans are being accomplished in a proper manner. If that is not the case, and the results of those inspections, tests, and monitoring protocols indicate that the ground is not behaving as required by the contract document then the project Owner is within its rights to require the Contractor to modify its means and methods submittals of construction in accordance with those observations. Hence, the enforcement mechanism for Class C submittals is not the actual contents of the submittal but the documentation of how the Contractor’s proposed means and methods of construction are actually impacting the ground during construction.
Based on the above and based on numerous professional publications relating to underground construction, the final conclusion to be drawn by this paper is that the Owner must have a group of well-qualified and well-experienced construction management professionals in the field during construction. No one can foresee all of the possible outcomes associated with any particular underground project and it is the observations being made in the field during construction that are crucial to project success. The contract document sets the stage for project success, but it is the working relationship between the project Owner and the project Contractor, as defined by the project submittals, which causes the contract document to be implemented in a proper manner.
As stated at the beginning of this paper, no other form of civil construction has a more complex and a more difficult to define interface between project design and project construction as compared to an underground project. Probably 90% of what must be accomplished for the successful completion of an above-ground structure is revealed by the project plans and specifications for the finished facility but construction of the finished facility for an underground project can not even begin until the underground openings are constructed and therein lies the risk, the cost, and the schedule for an underground project.