1️⃣ Purpose of 4.24 (1999) / 4.23 (2017)

Both editions answer a simple on-site question: “What do we do if the crew digs up something historically or scientifically important?” The answer: protect the find, notify the Engineer promptly, let the Employer take custody, and follow the Engineer’s instructions. If those instructions cause delay and/or Cost, the Contractor can claim relief—subject to the claims procedure and strict time bars.

Why it exists (risk story):

• Public interest & legality: Finds (fossils/antiquities) are placed under the Employer’s care and authority. This safeguards legal compliance and reputation.
• Orderly process: Contractor must prevent removal/damage, notify quickly, and await instructions—typically including a short stop-work radius and preservation steps.
• Fair relief: If complying with instructions drives extra time or cost, Contractor may recover EOT and Cost (note the 2017 nuance on Profit—see §3).

Implications:

• Employer: Gains custody/control and must steer lawful handling; avoids reputational harm.
• Contractor: Must protect & notify—fast. Relief is available, but only if the claim is run on time with proper records.

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2️⃣ Clause Breakdown (close-to-text, plain English)

📘 1999 — Clause 4.24 Fossils

• Custody & protection: Any fossils/antiquities found on Site go under the Employer’s care and authority; Contractor must prevent removal/damage.
• Notice & instructions: On discovery, Contractor promptly gives notice; the Engineer issues instructions on what to do (e.g., fence off, call heritage authority).
• Entitlement: If complying with those instructions causes delay/cost, Contractor (subject to 20.1) gets:
  • EOT under 8.4, and
  • Cost (added to the Contract Price); then the Engineer proceeds under 3.5 to agree/determine.
• Claims mechanics: Notice within 28 days; fully detailed within 42 days; monthly updates if continuing; final within 28 days after effects end. Late notice can forfeit entitlement.

📒 2017 — Clause 4.23 Archaeological & Geological Findings

• Custody & protection: Same principle—Employer’s care/authority; Contractor prevents removal/damage.
• “Pre-disturbance” inspection: Give Notice as soon as practicable, in good time so the Engineer can inspect/investigate before it’s disturbed; then the Engineer issues instructions.
• Entitlement: If complying with instructions causes delay/cost, Contractor (subject to 20.2) gets EOT and Cost (note: not “Cost plus Profit” here).
• Claims mechanics: Notice of Claim within 28 days (20.2.1), Fully Detailed Claim within 84 days (20.2.4/20.2.6 continuing), monthly updates, final within 28 days after effects end.

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3️⃣ Key Interpretations & Practical Implications

A. Trigger for entitlement
It’s not the discovery itself but complying with the Engineer’s instructions that unlocks EOT/Cost. Keep work paused just enough to protect the find until told otherwise.

B. Time bars are make-or-break

• 1999: Miss 28 days and entitlement can be lost entirely. Then, 42 days for the detailed claim; monthly if continuing; final within 28 days after effects end.
• 2017: 28-day Notice of Claim; 84-day fully detailed claim (or monthly interim if continuing), then a final within 28 days after effects end.

C. Profit or no Profit?
Under 2017 4.23, the text points to Cost (not “Cost plus Profit”) for these findings. This contrasts with other places in 2017 where “Cost plus Profit” is explicit—here it’s not. Plan valuations accordingly.

D. Engineer’s 2017 procedure (3.7) tightens timelines
2017 folds most disagreements/claims into 3.7 Agreement/Determination with 42-day time limits for agreement/determination and even deemed outcomes (e.g., deemed rejection if late). Use this spine if instructions or decisions stall.

E. Records culture matters
Both editions expect contemporary records—photos, coordinates, log entries, stop-work radius, manpower/equipment standby codes—so the Engineer can verify. This underpins valuation in interim certificates while the claim is being processed.

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4️⃣ Cross-Referencing (how the clause “plugs in”)

• 1999: Entitlement is expressly routed to 8.4 (EOT) and 3.5 (Determinations), via 20.1 (Contractor’s Claims) trigger. It’s all packaged inside 4.24 itself—very handy.
• 2017: Entitlement is expressly subject to 20.2; the 3.7 engine (consultation → determination → time limits → NOD) governs how the claim is agreed/determined.

Why 2017 refined the wording: to enforce pre-disturbance inspection, unify claims processing under 20.2, and anchor decision speed/accountability under 3.7.

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5️⃣ “What-If” Scenarios (decision-ready)

A) Find at the trench wall (perfect compliance) ✅
Crew fences off a 10–20 m radius, photographs, logs coordinates, and issues immediate notice. Engineer instructs to hold, heritage authority inspects, minor re-routing follows. You book EOT and Cost for standby/re-sequencing, log daily codes, and roll monthly interim claims (2017: under 20.2.6 continuing).

B) “Only a small shard—carry on” (self-help risk) ⚠️
If you resume without notice and disturb the find, you risk breaching the duty to protect and losing entitlement (late or missing notice under 28 days can be fatal in 1999; 2017 also enforces a 28-day Notice of Claim).

C) Late notice but good records 🕒
You reported on Day 35 with a strong record trail (photos, daily logs showing you discovered it later than assumed). The Engineer can still consider—but both editions allow late-notice consequences; relief may be reduced or lost depending on how the late notice prejudiced investigation (2017 spells this out in 20.2.7).

D) Engineer silent on instructions 📨
In 2017, escalate via 3.7 time limits: consultation → determination within 42 days; failure can result in deemed rejection, enabling DAAB steps, or direct arbitration for non-compliance with final binding outcomes. Keep Notices crisp.

E) Variation or not? 🔀
If the find triggers design change or route re-alignment, clarify whether the Engineer’s directions are preservation-only (recoverable as Cost) or also a Variation (separate valuation logic). The 1999 text leans on 3.5; 2017 folds it into 3.7—either way, label the instruction clearly to avoid double-counting.

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6️⃣ Suggestions for Clarity & Improvement (PC-ready wording) ✍️

Goal: reduce disputes by nailing definitions, timelines, and roles—without upsetting FIDIC’s balance.

(i) “Promptly” = concrete hours
Model PC text:
“On discovery, the Contractor shall issue an Initial Notice within 24 hours, with photos, GPS coordinates, a sketch and a proposed stop-work radius.”
—Supports pre-disturbance inspection (2017) and contemporaneous records culture (both).

(ii) Minimum stop-work radius
Model PC text:
“A default 10 m radius (adjustable by the Engineer) shall be cordoned within 4 hours of Notice.”

(iii) Engineer response SLA
Model PC text:
“The Engineer shall issue holding instructions within 48 hours of the Initial Notice. If none are received, the Contractor shall maintain preservation-only measures and is entitled to Cost for such measures pending instruction.”
—Ties to EOT/Cost entitlements while you await 3.7 progress.

(iv) Chain-of-custody & Authority contact
Identify the competent heritage authority and documentation (forms, hand-over receipts) to avoid ambiguity.

(v) Claims hygiene
Model PC text:
“All preservation/re-sequencing activities shall be coded to a dedicated Cost/Time code; daily logs and photos are mandatory.”
—Aligns with contemporary records expectations and smooths interim certification.

(vi) Variation flag
Model PC text:
“If instructions require removal/relocation of the find or redesign, the Engineer shall state whether this is a Variation (Clause 13) in the same Notice, to clarify valuation route.”

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7️⃣ Final Takeaways 🚩

• Protect first, notify fast. The Employer has care/authority; you must prevent disturbance and give Notice in time.
• Entitlement flows from instructions. EOT & Cost arise from complying with the Engineer’s directions—not from the mere find.
• Time bars rule the day. 28 days for initial claim notice (both); 1999: 42 days detailed; 2017: 84 days detailed (or interim), monthly, then final within 28 days after effects end.
• 2017 adds procedure muscle. 3.7 imposes consultation/determination with 42-day limits and deemed outcomes—use it to avoid drift.

🤔 Quick interpretative checks

• Can we claim “Cost plus Profit” in 2017 for fossils?
  No—4.23 points to Cost (not Cost + Profit) when complying with instructions.
• Do we have to stop work immediately?
  You must protect and avoid disturbing the find; the 2017 edition explicitly requires notice in time for pre-disturbance inspection—so yes, a controlled stop in the immediate vicinity is expected until instructions arrive.
• What if the Engineer takes too long?
  Use the 3.7 ladder (consult → determine within 42 days) and its deemed outcomes to keep momentum—and to preserve dispute options if needed.