⚖️ Construction Manager (CM) — Contractual & Risk Management

A Differing Site Condition (DSC) is a physical condition encountered at the work site that materially differs from: (Type I) what the contract documents indicated, or (Type II) conditions normally encountered in the type of work. DSC claims are the most frequent and highest-value claims on CDOT bridge rehabilitation projects — because the combination of incomplete historical drawings, unknown corrosion extent, hidden subsurface utilities, and aging bridge geometries makes "what you bid" almost always different from "what you find."

• Type I DSC — Contradiction with Contract Documents: The contract drawings show a flange plate at 3/4-inch thickness; the actual plate is 9/16-inch after section loss measurement. The specifications show 3 existing bearing assemblies; 5 exist in the field. The geotechnical report shows rock at 18 feet; the GC hits rock at 7 feet. Each is a Type I DSC — the field contradicts the document.
• Type II DSC — Unusual Conditions: A void discovered behind the concrete abutment facing during patching. A gas pocket in the river sediment that ignites during pier drilling. Pack rust between built-up section plies that was extreme even by bridge standards. These are conditions that are unusual compared to what a reasonable contractor would anticipate on a bridge rehabilitation project.
• Notice requirement is absolute — and time-limited: The FAR-equivalent clause in CDOT's standard contract requires the contractor to provide written notice of a potential DSC before disturbing the condition — or within 48–72 hours of discovery. Notice submitted after the condition has been disturbed, or weeks after discovery, may be denied regardless of merit. The CM's inspector must understand this notice requirement and immediately flag any potential DSC to the GC for formal notice submission.
• The CM's role is neutral — not adversarial: When the GC submits a DSC claim, the CM's job is not to minimize CDOT's exposure or to advocate for the GC. The CM's job is to investigate objectively — gather facts, review contract documents, compare conditions as-found to conditions as-described, and provide CDOT with an accurate, fair assessment. A CM who reflexively denies DSC claims without investigation exposes CDOT to claim escalation and litigation at far greater cost than a fair, timely resolution would have incurred.

Bridge rehabilitation contracts are uniquely prone to scope ambiguity because they are built on a foundation of incomplete information — original drawings that may be 80 years old, partial as-built records, and rehabilitation drawings that describe work on a structure whose actual condition is not fully known at bid time. When the GC's interpretation of the contract scope differs from CDOT's interpretation, the result is a scope dispute — which can range from a simple 2-page change order to a multi-year arbitration.

• The three most common ambiguity sources on CDOT bridge rehab projects:
  1. Scope boundary ambiguity: "Repair deteriorated steel" — what constitutes deteriorated? 10% section loss? 20%? The specification may not define the threshold, and the GC bids based on an assumption while CDOT expects a different standard.
  2. Included/excluded work conflicts: The bid schedule lists "bearing cleaning and repainting" but the specifications also reference "replace bearings as directed." If the inspector directs bearing replacement, is that a change order or included in the base contract?
  3. Original drawing applicability: A 1938 bridge drawing shows a connection detail. The repair specification references the 1938 drawing. But the bridge has been modified since 1938 and the connection no longer matches the drawing. Which governs — the drawing or the field?
• Ambiguity is resolved against the drafter: The legal principle of contra proferentem — ambiguous contract language is construed against the party that wrote it (CDOT) — creates owner liability for unclear specifications. Courts and arbitrators consistently award scope dispute claims to contractors when the contract language has two reasonable interpretations.
• The CM's pre-construction review is the best scope dispute prevention tool: Before NTP, the CM should conduct a systematic scope review — reading every pay item description against every specification section and every drawing note, specifically looking for: undefined thresholds, contradictions between documents, references to drawings that may not match field conditions, and work descriptions that reasonable contractors would interpret differently. Ambiguities identified before the contract is executed can be resolved by addendum. Ambiguities identified during construction become claims.

Chicago's river corridor carries the legacy of 150 years of industrial activity — manufactured gas plant sites, historical rail yards, petroleum storage, and municipal waste disposal. When bridge rehabilitation work involves subsurface excavation at abutments, pier foundation work, or soil disturbance in adjacent areas, the GC may encounter contaminated soil, free-phase petroleum, or unknown hazardous materials that were not identified in the pre-construction environmental investigation. The regulatory response to these discoveries is immediate, automatic, and not within the CM's or CDOT's control to moderate.

• IEPA Voluntary Site Remediation Program (VSRP) or Agency-Initiated Action: Any discovery of contaminated soil or groundwater that exceeds IEPA Tier 1 cleanup objectives triggers reporting obligations under the Illinois Site Remediation Program. The CM must notify CDOT and IEPA within the contractual reporting window (typically 24–48 hours). The remediation response — soil characterization, containment, disposal, and agency approval — can take weeks to months depending on the extent of contamination and the regulatory pathway selected.
• Mid-project peregrine falcon nest — federal discovery that becomes a stop-work: An active peregrine falcon nest discovered after mobilization triggers an immediate work restriction under the MBTA regardless of project schedule. This is an environmental discovery that generates a force-majeure-type stop-work with no contractual remedy for schedule acceleration. (See also Wildlife section under Environmental Challenges.)
• Unknown UST or AST discovery: Underground storage tanks (USTs) or aboveground storage tanks (ASTs) discovered during abutment excavation or approach work require immediate work stoppage, soil testing, IEPA notification, and potentially licensed environmental contractor mobilization for assessment and removal. USTs from former gas stations, maintenance facilities, or industrial operations are found in the approach areas of Chicago's older bridges with some regularity.
• The contaminated soil disposal cost is the GC's risk — unless it's a DSC: If the contract documents' geotechnical report mentioned "potential for soil contamination in the project corridor" but the GC bid assuming clean soil disposal, the GC may bear the cost differential. If the environmental investigation gave no indication of contamination and the soil is found to be contaminated, the cost premium for hazardous soil disposal is a valid Type I DSC claim. The CM must review the contract's environmental disclosures carefully before making a determination.

Construction over navigable water triggers a set of specialized insurance and indemnification requirements that significantly exceed standard construction project insurance programs. The combination of federal maritime law jurisdiction, the unique liability exposure from dropping materials into the Chicago River, and the involvement of marine equipment creates a coverage landscape that most GCs' standard insurance programs are not designed to address — and that many project managers discover too late in the project setup process.

• Jones Act and maritime worker injury liability: Any worker injured while working on a floating vessel (barge, work platform) on a navigable waterway may be classified as a "seaman" under the Jones Act (46 U.S.C. §30104). Jones Act seaman status dramatically expands the injured worker's legal remedies — including the right to sue for unseaworthiness of the vessel and the right to maintenance and cure (daily living expenses and medical care during recovery). Standard workers' compensation insurance does not cover Jones Act claims. The GC must carry Maritime Employers Liability (MEL) coverage for all workers on floating platforms.
• US Longshore and Harbor Workers' Compensation Act (USL&H): Workers engaged in maritime employment (loading, unloading, building, repairing vessels) on navigable waters may be covered under the federal USL&H Act rather than Illinois workers' compensation. USL&H benefits are significantly higher than state WC benefits — particularly for permanent disability. Standard WC policies do not automatically include USL&H endorsements; they must be specifically added.
• CDOT's minimum insurance requirements for over-water work: CDOT's standard contract requires, for projects involving work over navigable water: CGL minimum $5M per occurrence, Umbrella/Excess minimum $10M, Pollution Liability minimum $5M (for lead paint abatement), Maritime Employers Liability minimum $1M, and Builder's Risk with a marine extension covering the bridge and all materials in transit over water. These requirements routinely exceed what smaller GCs carry as standard coverage — creating a pre-bid insurance procurement requirement that adds weeks to project setup.
• Pollution liability is the most frequently underestimated coverage gap: A standard CGL policy contains a "pollution exclusion" that eliminates coverage for bodily injury or property damage caused by pollutants — which includes lead paint debris and blast media entering the Chicago River. Without a standalone Pollution Liability policy, a containment failure event that releases lead paint into the river has zero insurance coverage under the GC's primary CGL. The cleanup cost, IEPA fines, and third-party claims are uninsured losses. Pollution Liability on a bridge repaint project costs $15,000–35,000/year in premium — a trivial cost relative to the uninsured exposure.

Force majeure — "superior force" — refers to extraordinary events beyond the reasonable control of either party that prevent contract performance. On Chicago river bridge projects, force majeure events are not theoretical — they have occurred repeatedly, with the COVID-19 pandemic and the 2019 polar vortex being the most recent large-scale examples. The CM's role in force majeure events is to document, manage, and negotiate their contractual impact — determining what constitutes an excusable delay, what additional costs are compensable, and what the schedule recovery plan must achieve.

• CDOT's standard force majeure clause — what it covers and what it doesn't: CDOT's standard contract excuses delays caused by acts of God, acts of the government, fires, floods, epidemics, quarantine restrictions, strikes, freight embargoes, and unusually severe weather. The clause typically grants a time extension only — not additional compensation — for non-compensable force majeure events. Extended general conditions (superintendent, trailer, insurance, bonds) during a force majeure delay are the GC's risk unless the contract explicitly grants cost recovery for the specific event type.
• Chicago River flooding — when is it "unusual"?: The Chicago River floods regularly — spring floods of 1–3 feet above normal pool are routine. A flood that raises river level by 5 feet and submerges the work barge is not unusual if the contract documents disclosed that the river is subject to seasonal flooding. A 50-year flood event that raises the river 12 feet and collapses the containment structure is genuinely unusual. The CM must compare the actual flood event against historical records and the contract's geotechnical baseline to determine whether it constitutes a force majeure or a disclosed risk that the GC priced.
• Polar vortex events — "unusually severe weather" threshold: The 2019 polar vortex brought temperatures to -27°F in Chicago — a record. Coating operations were impossible below +50°F surface temperature. Steel became brittle below -20°F, creating FCM handling restrictions. Under most CDOT contracts, "unusually severe weather" is measured against a 10-year average: if the actual temperature or precipitation exceeds the 10-year mean by a defined margin, it qualifies as force majeure weather. The CM must maintain a daily weather log that captures actual conditions for comparison against historical averages — both for force majeure determination and for ordinary weather delay claims.
• COVID-19 as a force majeure precedent: During the March–May 2020 construction shutdown period in Illinois, CDOT issued a blanket force majeure determination for all active bridge projects — granting time extensions without requiring individual project-level force majeure filings. However, cost recovery (extended general conditions during the shutdown, PPE procurement, productivity losses from social distancing requirements) was contested project-by-project. Projects with strong contemporaneous documentation of shutdown costs recovered substantially more than those without. The COVID experience is a permanent lesson in force majeure documentation.