Appendices

Measurement and Payment Pitfalls for Geotechnical Pay Items

Twort and Rees’ chapter on bills of quantities is essentially a list of the measurement-and-payment wording that leads to claims. The points that bear on geotechnical work:

• Quantities are a best estimate. Do not pad them, and do not shift quantities between depth bands to build in a hidden reserve. Some owners pay the bid quantity unless the variation is obvious, so the quantities must be fair to both parties.
• Rock. Where rock is suspected but its extent is unknown, a provisional quantity is hard to bid. The authors suggest a provisional sum with a rate negotiated if rock is found, while expecting a related delay claim. Define rock in the contract by the method needed to remove it: explosives or hydraulic or pneumatic breakers. Consider a separate intermediate class for hard bands that need ripping but are not rock. Measure rock jointly in the open excavation with the contractor’s staff.
• Data to bidders. Supply the geophysical and boring data so that bidders can make their own judgment of rock depth and extent.
• Working space. State that only the volume within the pay limits is measured, and repeat this in items where contractors commonly claim extra excavation.
• Earthwork from borrow. Fill is paid as net volume in place. Give bidders all available data on the fill source, its bulking and its unit weight. Make the filling rate include setting aside and double-handling unsuitable borrow material, which cannot be measured. Use separate items for stripping overburden and for reinstating the borrow pit.
• Method-related and temporary works items. If temporary works such as access roads or dewatering are itemized as owner requirements, they must be fully specified. Otherwise leave them for the bidder to price as method-related items, fixed or time-related, and state that listing a method does not imply the engineer has approved it.

For railroad work: Each GSP in this template should end with a measurement-and-payment paragraph that applies these lessons:

• Undercut paid by the cubic yard within neat lines below the plan subgrade, with a stated pay limit.
• Unsuitable subgrade removal and replacement as a separate unit-price item with an estimated quantity tied to the borings.
• Rock defined by removal method.
• Geotextile and drainage pipe paid by area and length.
• Temporary shoring adjacent to live track, and dewatering, either fully specified as owner items or left as contractor-designed lump sums, but not both.

Spell out which item absorbs the work of handling material during short track windows, such as stockpiling and re-handling, so that it does not become an extra.

Source: Twort, A. C., and Rees, J. G. (2004). Civil Engineering Project Management, 4th ed. Oxford: Elsevier Butterworth-Heinemann, pp. 182–186, 189–194. Summarized and paraphrased. Full reference under Supplemental Sources.

Writing Enforceable GSP Language: Common Defects and a Review Checklist

The ASCE guide lists recurring specification defects drawn from Committee surveys:

• conflicts between sections or with the drawings;
• unattainable results or tolerances, which make users lose confidence in the whole document;
• ambiguous intent, which produces high bid contingencies and arguments during construction;
• references to standards that are unnecessary or not available in the field;
• over-specification of methods.

Its writing rules:

• Use short sentences in the imperative mood (“Compact each lift…”).
• Use “shall” for the contractor and “will” for the owner or engineer, and do not interchange them.
• Define “day” (calendar, working, or 24-hour).
• Drop “any” and “all” when the context already covers them.
• Remove phrases such as “as the engineer shall direct”.

Appendix F of the guide classifies actual problem wording:

• Superfluous: “furnish all labor, supervision, tools…” belongs in the conditions of the contract, not in every technical section.
• Ambiguous: “shall not occur without written approval” without saying whose approval. Another example is “an additional set for each additional 100 cubic yards”, which leaves open whether 199 CY needs one set or two.
• Left to the discretion of site personnel: “no further lifts until the inspector allows”, “compaction tests at locations selected by the Owner”, “restore to original condition as much as possible”, “neat and workmanlike manner”. The guide notes that bidders price the worst case and then perform to a reasonable one. It recommends replacing each phrase with a method, a code reference, or a measurable criterion.
• Conflicts with commercial terms: safety, rejection rights and schedule statements already covered in the general conditions.

The Appendix G checklist is a quick review tool. It asks whether related sections are listed and duplication removed; whether references are current, available in the field and have their options selected; who tests, by what method and in what report format; and who measures, by what method, and whether payment is tied to the measured quantity.

For railroad work: GSP drafts should be checked against Appendix F before issue. For example, “Compaction tests shall be taken at locations selected by the Engineer” can be rewritten as “The Engineer will test in-place density at a minimum frequency of one test per [__] CY per lift, at locations selected by stratified random sampling”, with the frequency taken from the railroad’s standard. “Remove unsuitable material as directed” should become a defined criterion, such as a proof-roll deflection or classification trigger, plus an ordered-quantity pay item. Phrases such as “protect the track” should be replaced by citing the railroad’s fouling, flagging and monitoring requirements.

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. 3–4, 31–33, 54–60. Summarized and paraphrased. Full reference under Supplemental Sources.

Fixed, Time-Related and Quantity Items in the Bid Schedule

Seeley describes the method-related charges introduced in CESMM. Many construction costs do not scale with the quantity of permanent work. Examples are bringing plant to site and removing it, site offices, temporary works and supervision. If these costs are spread through unit rates, any change in quantity overpays or underpays the contractor, and disputes follow. CESMM lets the bidder enter them separately, as one of two types:

• Fixed charges. These do not depend on quantity or time, for example establishing and removing a plant. They are paid when the operation described is complete.
• Time-related charges. These run in proportion to how long the resource is needed, for example running costs or maintaining a temporary access road. They are paid in instalments according to the proportion of the activity’s duration that has elapsed or been completed.

Method-related charges are not remeasured. If the contractor priced a crane for 22 weeks and used it for 28, the price does not change automatically. If dewatering priced in the bid turns out to be unnecessary in a dry season, the sum is still paid, because the contractor carried the risk. The charges are adjusted only when an ordered variation changes the work or its duration. The contractor must describe each charge, including the resources and the parts of the work it relates to, but is not bound to use the method described. Seeley notes the risks: front-loaded charges, and vague descriptions that are hard to certify.

For railroad work: on railroad jobs, durations depend on track windows, and the windows are controlled by train traffic and the railroad’s operating decisions. A geotechnical special provision template therefore benefits from three kinds of item:

1. Fixed items, such as mobilizing hi-rail or on-track equipment, building a temporary access road or crossing, and installing and removing instrumentation.
2. Time-related items, paid per day or per window, such as dewatering, standby while waiting for track time, and an instrument-reading program.
3. Quantity items, such as cubic yards of undercut, tons of subballast and ballast, and linear feet of drains.

When a cancelled window then stretches the schedule, the extra cost lands on the time-related items, where it can be checked. It is not hidden in the cubic-yard rate. The template should also state which costs the railroad pays directly, such as flagging and work trains, so that bidders do not price them twice.

Source: Seeley, I. H. (1993). Civil Engineering Quantities, 5th ed. Basingstoke: The Macmillan Press, pp. 59–66. Summarized and paraphrased. Full reference under Supplemental Sources.

Excavation Classification and Differing-Condition Thresholds in the Earthwork GSP

Writing for owners, Levy (2010) explains how the earthwork specification allocates subsurface risk. Declaring the site unclassified makes the contractor responsible for removing whatever is found, including rock, shale, hardpan, old foundations, pavement and debris, at the bid price. That protects the owner, but bidders respond by carrying a contingency large enough to cover the worst case, and the owner pays it whether or not bad ground appears. Levy asks owners to consider whether it is cheaper to pay actual costs for legitimate unforeseen conditions than to buy that contingency up front.

He summarizes two claim types recognized in public contracting and generally accepted privately. A Type I claim requires that the contract documents indicated the subsurface condition, that the contractor read them reasonably and relied on them in its estimate, that actual conditions were materially different and reasonably unforeseen, and that the costs claimed relate only to the difference. A Type II claim requires showing what usual conditions would have been expected, what was actually found, that it differed materially from the known or usual, and that cost increased. Owners typically answer that conditions were not really different, should have been anticipated, or that the contractor used the wrong equipment or inexperienced operators. Levy cites agencies that use a 15% quantity rule as evidence of material difference, and an FHWA statement that federal-aid contracts carry a changed-conditions clause triggered when a major item changes by more than 25%. To support a claim the contractor should record the time and condition observed, the superintendent’s daily-log entry, photographs, statements from the operator or foreman, and the operation and exact location, and should notify the owner’s representative before the material is removed.

Levy also cautions that springs absent during a summer drilling program may reappear in spring, and that rock can lie between widely spaced borings.

For railroad work: In GSP-01, state whether excavation is classified or unclassified, and if classified, define rock and unsuitable material by measurable criteria and pay limits (paylines) below subgrade. Where undercut of soft subgrade beneath track is expected, carry it as a unit-price item with an estimated quantity rather than burying it in a lump sum. Include a notification clause that requires the contractor to stop and notify the railroad’s representative and the geotechnical engineer of record before removing material it considers different, so the condition can be observed and photographed in place.

Source: Levy, S. M. (2010). Construction Process Planning and Management: An Owner’s Guide to Successful Projects. Burlington, MA: Butterworth-Heinemann (Elsevier), pp. 21, 260–264. Summarized and paraphrased. Full reference under Supplemental Sources.

Measurement and Payment Rules for Earthwork Items

Seeley summarizes the earthwork rules of CESMM3 Class E. They are a useful checklist for writing the measurement-and-payment part of an earthwork special provision, because each rule closes off a common dispute:

• One item, one excavation type, one material. Topsoil, rock, artificial hard material and “other natural material” are separate items. Disposal, on-site placement and reuse as fill are also separate items.
• Depth class means total depth. The depth range in the description is the full depth of the excavation, not the thickness of each layer, because total depth is what drives the choice of equipment. Where rock about 10 ft thick lies under about 23 ft of gravel, Seeley measures two items. The first is excavation in other material, 16–33 ft maximum depth, ending at the top of rock. The second is excavation in rock, 6.6–16 ft maximum depth, starting at the top of rock.
• Undefined material is soft natural soil. Running sand is not a separate class. It is treated as a groundwater problem, which is the contractor’s risk.
• Isolated boulders and rock are not measured separately unless the piece exceeds about 1.3 CY, or about 0.33 CY where the excavation is less than about 6.6 ft wide.
• Working space, support of excavation sides and removal of dead services are deemed included in the rate. Backfill to working space is not measured.
• Net volumes from the drawings, with no allowance for bulking, shrinkage or waste. Disposal is the net excavation minus the net volume reused as fill. Double handling is paid only where it is expressly required.
• Fill items include compaction. Fill items state the material and any differing compaction requirement. Trimming of excavated and filled slopes is measured separately by slope range.
• A protective layer can be its own stage. The last 6–12 in. above formation can be made a separate item, and so can topsoil stripping.

For railroad work: for subgrade undercutting and embankment repair, the special provision should state the following. (1) The pay limits, as neat lines measured from a stated datum such as bottom of tie or design subgrade elevation. (2) A separate item for soft spots ordered below the planned undercut grade, so overruns are paid at a known rate. (3) A rock definition that uses the boring-log descriptions. (4) Whether fouled ballast is measured as excavation or as a separate removal-and-disposal item. (5) Whether stockpiling and rehandling is an item. Short track windows often force rehandling, so state it rather than leaving it to be argued.

Source: Seeley, I. H. (1993). Civil Engineering Quantities, 5th ed. Basingstoke: The Macmillan Press, pp. 87–89. Summarized and paraphrased. Full reference under Supplemental Sources.

Watching Fill Quality and Allowing for Bulking

Twort and Rees make a practical point about earthwork control: in situ density tests prove compliance after the fact. A sand-cone test takes hours, so it records past performance and cannot serve as real-time control. Real-time control comes from an inspector who watches every load as it is dumped, spread and compacted, has authority to reject material, and calls the resident engineer when in doubt. The cues they describe:

• Bounce. “Cushioning” or bounce under loaded haul trucks signals inadequate compaction, usually because the material is too wet or has too much clay or silt.
• Rutting. Severe rutting means the material is too wet or too clayey.
• Composition. Too much sand or gravel in a clay fill is easy to see. A change in clay color alone may not mean a change in suitability.
• Early rejection. If unsuitable material is caught after only a few loads, it can usually be mixed out with suitable material. Deliberately blending two different fills seldom works; zone them separately instead and recheck borrow composition periodically.

On moisture, they note that wet borrow and a wet formation may simply mean stopping work. Rolling the day’s surface smooth and to a fall sheds rain. Dry fill must be watered on the spread layer and mixed in, not just wetted on the surface.

On quantities, they stress bulking. Haul units have a fixed body volume. At a bulking factor of 1.2, each load carries about 83% of its body volume measured in place; at 1.35 it carries only about 74%. A disposal price based on the first figure but met with the second is about 12% short. They quote typical bulking of about 1.1–1.3 for granular and soft soils, about 1.4 for hard clays and 1.6–1.7 for broken rock. They also show how excavator bucket size is matched to truck return interval and loading cycle time, after allowing for bulking.

For railroad work: On embankment widening and subgrade replacement during a work window, there is no time to wait for density results before the next lift or before returning the track to service. Write the inspector’s authority to stop placement and reject loads into this GSP. Specify a test fill or roller-pattern trial at the start, and use proof-rolling observations as the lift-by-lift control, with nuclear or sand-cone density tests as the record. Size haul and disposal by loose volume. Undercut ballast and fouled subgrade spoil bulks significantly, and disposal along the right-of-way or off site is often the item that runs over.

Source: Twort, A. C., and Rees, J. G. (2004). Civil Engineering Project Management, 4th ed. Oxford: Elsevier Butterworth-Heinemann, pp. 228–231. Summarized and paraphrased. Full reference under Supplemental Sources.

Measurement and Payment Provisions for Earthwork GSPs

Goldbloom treats Method of Measurement and Basis of Payment as the parts of an earthwork section that generate the most disputes. The quantity of earthwork is hard to predict, so most items are paid on measured actual quantities. A Fixed (Plan) quantity can be used where the geometry is fully defined. It is computed by average end areas from the engineer’s preconstruction cross sections and the plan dimensions, and it is marked “Fixed” in the bid schedule.

His recommended practices:

• Excavation classes. Use Unclassified Excavation when little rock is expected. Use separate Common and Rock items when rock is present, and pay boulders larger than 1 CY as rock. The rock price includes scaling loose rock from the final faces.
• Additional depth (undercut) excavation. Pay it separately per CY, measured in place before and after removal, and only where the engineer orders it. Pay the replacement backfill separately as well.
• Temporary support. Pay trench sheeting separately by the square foot. If sheeting is buried in another unit price, the contractor has a financial reason to leave it out, which is a safety problem. If the contractor chooses to slope back instead, pay as if the trench were vertical and sheeted. Provide a separate item for sheeting the engineer orders left in place.
• Borrow. Measure in the original position at the pit after clearing and stripping, not in the fill, because the placed fill may consolidate for years. If trucks must be used for measurement, require loads struck off level.
• Dewatering is normally included in the related excavation price. Topsoil stripping is its own item.
• Pay temporary fencing and barricades separately, so that the protection actually gets provided.

For railroad work: When adapting GSP-01 for subgrade rehabilitation or embankment repair, pay ordered undercut of unsuitable subgrade per CY, measured in place, with select fill and geosynthetics as separate items. Measure imported subballast and fill in place or at the source, not by truck count. If excavation support next to live track (shoring or soldier piles beside the fouling limit) is carried in a lump sum, its scope must be stated explicitly. Define the excavation classes so they match the boring logs. Whatever the specification says, the railroad’s contract form and pay-item list govern.

Source: Goldbloom, J. (1989). Engineering Construction Specifications: The Road to Better Quality, Lower Cost, Reduced Litigation. New York: Van Nostrand Reinhold, pp. 208–218. Summarized and paraphrased. Full reference under Supplemental Sources.