Appendix E — Geotechnical Report Preparation

Differing Site Conditions, Report Disclaimers and the Boring Location Plan

Levy (2007) notes that a large share of construction disputes arise during sitework, when excavation exposes ground that does not match what the geotechnical report led bidders to expect. A boring describes the strata only at its own location, and a hole drilled a few yards away can show something quite different. Standard report disclaimers say so, and often add that the owner should carry an allowance for foundation costs that cannot be known until construction. Levy points out that this cuts both ways: the disclaimer concedes that actual conditions will only be revealed by excavation, and the recommended allowance is really a contingency for the owner’s benefit, since the owner commissioned and paid for the report.

To support a differing-conditions claim the contractor must show that (1) the contract documents indicated certain conditions that formed the basis of the bid, (2) its reading of those documents was reasonable, (3) the conditions encountered differed materially, (4) they could not reasonably have been anticipated, and (5) the costs claimed arise solely from the difference. Recoverable delay costs can include direct labor and equipment, weather-shifted work, acceleration, idle rented equipment, extended field office and home-office overhead, and lost productivity. On unit-price public work Levy cites a common yardstick that quantities varying by 20% or more from bid quantities may justify repricing.

Source example. On a two-building campus project with an “unclassified” site, rock was found at about El. 162.8 where boring B-23 showed rock at El. 152, and other areas did not match the logs either. The owner rejected a $288,000 rock claim. By sliding a transparent overlay of the boring location plan over the building footprint, the contractor showed that the geotechnical engineer had plotted every boring about 50 ft west of its true position; shifted 50 ft east, all logs matched the field conditions, and the owner paid. On a second project, unsuitable soil below the footing “payline” was settled by agreeing on a reasonable limit to the depth the contractor “owned” on an unclassified site.

For railroad work: Boring location plans for embankment, culvert and bridge work should be tied to railroad stationing (milepost and track centerline offset) and surveyed coordinates, and checked against the plan sheets before issue; a plotting error is indefensible once a contractor finds it. Log presentation should state the date of water readings and note where conditions between borings are inferred. Keep disclaimer language factual and pair it with clear baseline statements (for example, expected top of rock or depth of soft fouled subgrade) so that the railroad and contractor share one reference for judging whether a condition is truly different.

Source: Levy, S. M. (2007). Project Management in Construction, 5th ed. New York: McGraw-Hill, pp. 271–281. Summarized and paraphrased; figures reproduced for internal reference. Full reference under Supplemental Sources.

Unforeseen Ground Conditions Claims and What the Report Must Support

Twort and Rees treat claims for unforeseen ground conditions as among the hardest a resident engineer handles. Their discussion is based on Clause 12 of the UK ICE conditions, which is broadly comparable to the differing-site-conditions clauses in North American contracts. The contractor may claim for physical conditions, other than weather, that could not reasonably have been foreseen by an experienced contractor. Their main points:

• Deleting the clause does not remove the risk. Bidders simply add a premium, and the owner pays it whether or not bad ground is found. Bidders usually cannot drill their own borings, so price is their only defense.
• “Everything” descriptions do not work. Describing the excavation as “all materials including boulders, rock and running sand” does not override the clause, because the extent of each material is still undefined.
• Magnitude is the usual issue. Often the event itself was foreseeable and what was unforeseen was its scale. Their example is a hard siltstone band that was logged in the borings but then stayed in the tunnel crown for a long distance. If borings show variable ground, a contractor cannot be expected to have foreseen uniformly bad ground.
• Payment. The contractor recovers costs reasonably incurred plus a reasonable profit: labor (including standing time and uneconomic working), materials (including abandoned temporary measures), plant working and standing, site overheads and justified head-office costs. The resident engineer’s own daily records are the check.
• Prevention. Their first precaution for minimizing claims is an adequate site investigation, followed by complete design and documents before bidding.

The authors note that a fair clause often means the owner pays no more than if the condition had been known and written into the contract.

For railroad work: The decision to issue a factual report only, or a factual report with a design report, determines what an “experienced contractor” can reasonably be expected to have foreseen. To make a later claim decidable:

• Describe the variability, not just the average. Show the range of depth to firm subgrade along the track and the stations where borings are widely spaced.
• State plainly where conditions between borings are interpreted rather than observed.
• Put quantities that depend on ground conditions (undercut depth, rock excavation, obstructions under embankments) into unit-price or provisional items in the GSPs rather than lump sums.

When a claim arises, the boring logs, the report’s stated variability and the inspector’s daily records are the evidence the railroad will rely on.

Source: Twort, A. C., and Rees, J. G. (2004). Civil Engineering Project Management, 4th ed. Oxford: Elsevier Butterworth-Heinemann, pp. 212–219, 223–224. Summarized and paraphrased. Full reference under Supplemental Sources.

Differing Subsurface Conditions Clauses and the Factual/Interpretive Split

Goldbloom argues that subsurface risk belongs mostly with the owner, because only the owner has the time and budget to explore the site. Bidders get a few weeks to price the work and cannot drill their own borings. If each of several bidders had to do that, the owner would pay for the same exploration several times over. Borings and test pits show conditions only at the points sampled, so some differences during construction should be expected. A Differing Subsurface Conditions (changed conditions) article covers this. Its trigger is a condition that (1) differs materially from what the contract documents indicate, or (2) could not reasonably have been anticipated, and that (3) materially affects the cost of the work. The contractor must give notice before the condition is disturbed. The engineer then investigates, and if the claim is justified, an equitable adjustment is made in writing.

The book’s case history comes from a reservoir project that included a railroad relocation. Excavation for the dam was paid under two items, Earth Excavation and Rock Excavation. Rock was defined as ledge that needed drilling and blasting. At one abutment the contractor hit cemented glacial till that a 2½-CY shovel could not dig, and the borings had not shown it. The contract had neither a disclaimer nor a changed-conditions clause. The engineer still recommended paying for the extra drilling and blasting on force account, and the dispute was settled without litigation.

Goldbloom’s disclosure rules:

• Disclose everything the designer knew, or should have known from records available to it. Withholding information invites misrepresentation claims.
• State who drilled the borings and when, and where bidders can inspect the samples and cores. Note that samples dry out in storage, and that groundwater readings reflect conditions at the time they were taken.
• Keep factual data separate from interpretation. In general, do not disclaim the factual data. Recommend that bidders have the interpretations reviewed by their own qualified specialist.
• Reference reports by others can be furnished “for information only”, clearly marked as not part of the contract documents.

For railroad work: The GDR/FGR split described in this chapter maps onto Goldbloom’s factual/interpretive distinction. Bid packages for undercutting, cut-slope or culvert jobs should include the factual report: logs, lab data, groundwater observations with their dates, and GPR or ballast-fouling records. Interpretive design documents should be labeled as such. The pay-item definitions for excavation classes (common, rock, boulders, unsuitable subgrade) need to match how the logs describe materials, because the cemented-till case turned on that definition. Confirm with the railroad’s contracting group whether its standard agreement includes a changed-conditions article. If it does not, put the gap on the project risk register.

Source: Goldbloom, J. (1989). Engineering Construction Specifications: The Road to Better Quality, Lower Cost, Reduced Litigation. New York: Van Nostrand Reinhold, pp. 37–39, 182–186, 298–300. Summarized and paraphrased. Full reference under Supplemental Sources.

Float, Float Ownership and Geotechnical Hold Points in Special Provisions

Haidar defines four kinds of float in arrow notation, where activity ij has duration d_ij and T(E) and T(L) are the earliest and latest event times:

Table E-PM1. Float definitions (after Haidar 2016, Eqs. 3.6–3.8)

Because total float is shared, using it on one activity reduces it for all later activities on the path. Haidar stresses that the contract should say who owns float. The common default is that the project owns it and whoever uses it first gets it. An extension of time is then due only when an owner-caused event is predicted to push total float below zero on a path that is critical to completion. A contractor who wants a private buffer should show it as a time contingency in the baseline. NEC3 Clause 63.3 preserves terminal float when planned completion is earlier than the contract date. He also notes that in resource-constrained schedules the float concept, and sometimes the critical path itself, breaks down.

For railroad work: GSPs often create geotechnical hold points that act as schedule constraints. Examples include a settlement or piezometer monitoring period before the next fill lift or before final track surfacing, a load test before production piles, and a curing and verification period for treated ground. Write each hold point into the GSP with a stated minimum duration and the measurable criterion that ends it, so that bidders put it in the baseline schedule rather than treating it as float. Say whether an extension caused by monitoring results is an excusable delay, and coordinate that wording with the railroad’s contract staff. Treat track windows and outages as fixed constraints in the same way. A hold point that is clearly specified seldom produces a dispute; an unstated one usually does.

Source: Haidar, A. D. (2016). Construction Program Management – Decision Making and Optimization Techniques. Cham, Switzerland: Springer International Publishing, pp. 71–75, 78. Summarized and paraphrased; figures reproduced for internal reference. Full reference under Supplemental Sources.

Planning GSP Production: Scope-of-Work Memorandum and Review Flow

The ASCE guide recommends a planned specification production process instead of copying the last similar job. Copied specifications carry irrelevant requirements and repeat past omissions. Small projects are not exempt: the guide notes that small jobs often produce large claims because of careless or incomplete documents.

Its flow chart has thirteen steps:

1. Agree the scope and specification philosophy with the owner.
2. Obtain the owner’s contract terms and standard specifications.
3. Review them for applicability to the project.
4. Outline the required sections and set a production schedule.
5. Draft outline specifications. Decide early on special clauses such as differing site conditions, price escalation, schedule incentives and dispute review boards.
6. Hold technical reviews.
7. Owner review.
8. Expand the drafts.
9. Constructability and engineering review.
10. Owner review.
11. Resolve comments in meetings.
12. Prepare and submit the final draft.
13. Owner issues the documents for bid.

Steps 10 to 12 often repeat. Reviews should include field staff who will inspect the work and experienced construction people who can spot constructability problems.

The first document produced should be a scope-of-work memorandum. It lists the areas and types of work, the items furnished by the owner or others, and the specification sections and drawings required. The memorandum is a management tool and not a contract document. Its content later goes into the Summary of Work and the agreement, which lets technical sections stay generic.

Other points from the guide:

• Drawings carry quantities, dimensions and geometry. Specifications carry quality. Duplicating information between them almost always produces conflicts.
• Assign testing responsibility explicitly, and state which results mean acceptance or rejection.
• Research field conditions during design. A clause that makes the contractor verify existing conditions does not replace that research. Resolve known unknowns with the owner as contract requirements.

For railroad work: Treat GSP integration as a scheduled, budgeted deliverable, not a task for the end of the report. A geotechnical scope memo for a culvert replacement or slide repair would record:

• which GSPs are needed (earthwork, shoring, dewatering, ground improvement, instrumentation);
• which items the railroad supplies, such as ballast, flaggers, track work by railroad forces and disposal sites;
• how each GSP ties to the factual and interpretive reports.

Get the railroad’s standard specifications and agreement forms at Step 2, since many Class I railroads have their own. Include the resident engineer or construction manager in the constructability review.

Source: ASCE Construction Institute Committee on Specifications (L. Eckersley, Chair) (2013). Preparation of Construction Specifications for Civil Projects. Reston, VA: American Society of Civil Engineers, pp. 6–12, 16–17, 22–23, 29–30. Summarized and paraphrased; figures reproduced for internal reference. Full reference under Supplemental Sources.

Defining Rock, Uncertain Work and Bulking When Linking the Report to the Bid Documents

Spain’s commentary on how the CESMM3 measurement rules work gives several points that apply directly when a geotechnical report feeds a bid package.

• Define rock in geological terms, tied to the borehole logs. The definition of rock decides how much rock excavation is paid, so it belongs in the preamble to the bid schedule. Spain advises against the familiar wording “material which in the opinion of the Engineer can only be removed by blasting, pneumatic tools or wedges,” because it leaves the taker-off, the estimator and the site staff uncertain. He recommends using the same terms as the boring logs.
• Measure the full excavation depth across layers. The commencing surface is the top of the whole excavation and the excavated surface is its bottom, however many layers lie between them. Stripping over a cut-and-fill site can produce two items for the same work. A note in the preamble, or a wider item description, avoids that.
• Measure net, from the drawings. Round sensibly, considering the effect on the total.
• Use a provisional sum, not provisional quantities. Where the design is not developed enough for real quantities, carry the work as a provisional sum in the general items. Do not use provisional quantities, which invite high rates on small items that pay off when the quantities grow. Carry a separate general contingency.

Spain’s data chapter gives bulking factors for converting excavated volume to loose volume:

Table E-PM2. Table: Bulkage of excavation, percent increase over in-place volume (after Spain 1995, Chapter 9)

For railroad work: when the report’s recommendations become special provisions:

• Write the rock-excavation definition from the logged descriptions, such as weathering grade, RQD and refusal criteria, so that the pay line matches the subsurface profile in the report.
• Carry the uncertain parts as a provisional sum, with the reason stated in the report. Examples are the depth of soft subgrade below a planned undercut and the extent of a slide that is still moving.
• State plainly that bid quantities are neat in-place volumes. Haul and disposal volumes are then the contractor’s calculation, using bulking factors like those above or values measured on site.

Source: Spain, B. (1995). Taking Off Quantities: Civil Engineering. London: E & FN Spon, pp. 10–11, 19, 23, 194. Summarized and paraphrased. Full reference under Supplemental Sources.

Design Proposals and “Mini-Drawings” as a Budgeting Tool

Oberlender’s chapter on design proposals is written for the design-side project manager, who must turn a sponsor’s request for proposal into an engineering scope, a work-hour budget and a schedule. The key steps:

• Lock the assumed scope. Where the RFP is vague and the sponsor cannot clarify it, define the scope as well as you can, budget it, and document the assumptions back to the sponsor. When better information arrives, that portion is re-priced.
• Discipline detail sheets. Each discipline lead converts the project definition into a discipline scope, a specification list and a preliminary drawing list. With the discipline manager, the lead estimates work-hours by personnel category. The project manager then adds project management, clerical and reproduction hours.
• Mini-drawings. These are quick hand sketches on letter-size sheets, one for each full-size sheet expected in the final set, in final order, with plans, sections and details blocked out. They give an early sheet count, show the expertise needed, support the work-hour estimate, and later serve as drafting assignments and a progress record.
• Sanity checks. Compare drawings per facility, hours per drawing, design cost as a percentage of construction cost, and expected duration against past projects. Confirm that the people in the budget will actually be available.
• Contingency. The most common error in design schedules is leaving no allowance for permit delays, client review time and slow responses to information requests.

He also recommends budgeting design in work-hours rather than dollars, because hours are what drive design.

For railroad work: The “mini-drawing” translates directly into a mini-report, a one-page-per-item dummy of the geotechnical report. List each figure (site location, boring location plan, subsurface profile along the track centerline, cross-sections at each repair station, stability output sheets), each appendix (boring logs, lab summary, calculations, GSPs) and each table, and assign estimated hours to every item. Building this dummy from the report outline in this appendix during the proposal makes the sheet and figure count visible. It also exposes scope the client may not have priced, such as a second cross-section for a slide that extends past the original limits, and gives a ready basis for the client-review allowance and the peer-review hours required under I.11.

Source: Oberlender, G. D. (2000). Project Management for Engineering and Construction, 2nd ed. Boston: McGraw-Hill, pp. 118–134. Summarized and paraphrased. Full reference under Supplemental Sources.

Differing Site Conditions and the As-Planned / As-Built / Adjusted Schedule Method

Hutchings describes changed conditions, also called unforeseen or differing site conditions, as a standard clause in federal contracts that is increasingly used by other public owners. The policy behind it is that the owner accepts certain subsurface and latent-condition risks so that bidders do not have to carry large contingencies for them. His examples of qualifying conditions include a buried pipeline that is missing from the drawings or shown in the wrong place, unusually severe weather for the season and location, and expansive clay in the excavation that was not identified in the geologic survey or the prior soil investigations. He notes that severe weather may be ruled excusable (time only) but not compensable.

He also lists constructive changes, informal owner acts or omissions that increase cost or time. These include defective plans and specifications, the engineer’s interpretation of documents, demanding a higher standard than specified, improper rejection of work, changes in method or sequence, and owner nondisclosure of pertinent facts. The contractor must give written notice within the contract period or may waive the claim.

To measure the time effect of a change after the fact, Hutchings uses three schedules:

1. As-planned – the accepted baseline.
2. As-built – the historical schedule built from the periodic updates, which contains every effect that actually occurred.
3. Adjusted – the as-built with the effect of the one change removed from each update.

The difference between the as-built and adjusted completion dates is the time attributable to that change. Before a change is made, a single revised as-planned schedule that includes the change shows its predicted effect on the end date.

For railroad work: the geotechnical report is the baseline against which a differing-condition claim is judged, so write it with that use in mind. Present factual data (logs, groundwater readings, lab results) separately from interpretation. State the limits of the data between borings. Include or reference all relevant information the railroad holds, such as historical borings, earlier slide reports and drainage records, because withholding pertinent facts can itself become a constructive change. During construction, document any suspected differing condition immediately: milepost, station and offset, depth, photographs, samples, and the work affected. Report it to the railroad’s project manager in writing the same day.

Source: Hutchings, J. F. (2004). Project Scheduling Handbook. Civil and Environmental Engineering Series, Vol. 15. New York: Marcel Dekker, Inc., pp. 209–212. Summarized and paraphrased. Full reference under Supplemental Sources.

Assumptions Versus Risks: The Acid Test and the Assumption Register

Bissonette treats the line between a valid assumption and an unrecognized risk as central to planning. An assumption bounds the work to known constraints, or records a condition outside the team’s control that the stakeholders have agreed to. He applies a two-question “acid test” taken from the PMBOK® Guide:

1. Could the assumption or constraint prove false?
2. If it were false, would one or more project objectives be harmed?

If both answers are yes, the statement is a risk and must be moved to the risk register or reworded until it passes. A companion sentence form, “<assumption> may prove false, leading to <effect on objectives>,” makes the consequence explicit. His examples show the range of outcomes. One assumption is valid because a contract clause already provides an equitable adjustment if customer-furnished equipment arrives late. Another, “the team assumes no liability for scope omissions,” fails the test and should prompt more planning. He recommends an assumption register on every project, whatever its size. Its columns are number, description, “could it prove false?”, “if false, would it affect the project?” and “convert to a risk?”.

For railroad work: Geotechnical reports are full of assumptions: groundwater at the level measured during drilling, subsurface conditions between borings similar to those at the borings, no undocumented fill or buried timber trestle, drainage outfalls that remain functional, and tie and ballast renewal staying on the maintenance cycle. Run each one through the acid test before the report is sealed. Assumptions that pass belong in the limitations or design-basis section. Those that fail, such as a water level measured in a dry month at a site that seeps in spring, should be stated as a risk with a recommended response, for example a piezometer, a contingency quantity or a construction-phase observation. Including a short assumption register in the report appendix helps the railroad’s reviewers and the contractor see what the recommendations depend on. It also gives a clear basis for comparison if conditions found during construction differ.

Source: Bissonette, M. M. (2016). Project Risk Management: A Practical Implementation Approach. Newtown Square, PA: Project Management Institute, Ch. 5, “Assumptions Versus Risks” (unpaginated e-book; PDF pp. 62–65). Summarized and paraphrased. Full reference under Supplemental Sources.