System

{{entity:Water Treatment Plant}} {{hex:57F73A59}}, QC review session. The project entered this session at first-pass-complete with 210 requirements across 6 documents, 195 trace links, and 100 facts in the SE:water-treatment-plant namespace. Ten subsystems fully decomposed into 50+ components across prior sessions 207–210.

Findings

Lint findings (6 total: 0 high, 3 medium, 3 low):

The two substantive medium findings concerned degraded-mode requirements. {{sys:ARC-DECISIONS-007}} describes the distributed PLC architecture’s resilience to SCADA server failure but provides no quantified performance floor for degraded operation — no scan cycle time, no setpoint retention duration, no resynchronisation target. {{sub:SUB-REQS-056}} was flagged for “manual overrides” language but is actually an audit logging requirement — false positive, acknowledged.

The “basin” abstract-metric finding (medium) incorrectly flags “per basin” as a statistical measure; it is standard WTP engineering unit-rate notation in {{ifc:IFC-DEFS-041}} and {{sub:SUB-REQS-031}}. Acknowledged.

Two low ontological-ambiguity findings note that {{entity:Water Treatment Plant}} is classified Abstract while {{entity:UV Disinfection Reactor}} {{hex:D7F73058}} and {{entity:Filtration Subsystem}} {{hex:DFB73218}} are Physical. This is correct: the plant is a system-level abstraction; the reactor and subsystem are physical assemblies. Acknowledged. The 61 requirements lacking “shall” are all ARC decisions and VER entries, which by design use descriptive rather than prescriptive language.

Verification coverage: 51 VER entries covered all 48 IFC requirements but only 3 of 76 SUB requirements (SUB-REQS-004, -005, -011). Overall VER/SUB+IFC ratio was 41.1% — below the 50% QC threshold.

Potential duplicate: {{ifc:IFC-DEFS-020}} (Sedimentation Effluent Launder → Filtration) specifies identical flow (900 m3/hr) and turbidity thresholds (2/5 NTU) as {{ifc:IFC-DEFS-011}} (Sedimentation → Dual-Media Gravity Filter Cell). These describe the same physical interface from different decomposition perspectives. Noted for validation session review.

Diagram scaffolds: All 13 diagrams contain 0 blocks and 0 connectors — they were created as empty structures and never populated with block/connector data. This is a tooling artefact from the scaffolding sessions and does not affect requirements or trace integrity.

PART_OF completeness: Initial query showed 32 PART_OF facts against 60+ entities. Investigation revealed all relationships already existed as bound entity-graph facts but were not returned in the initial 200-fact namespace query. Re-storing confirmed all component→subsystem and subsystem→system relationships are present and bound to entity UUIDs.

Orphaned requirements: 10 ARC decisions (ARC-DECISIONS-001 through -010) have no trace links. This is structurally correct — the trace linkset schema defines derives (STK→SYS→SUB/IFC) and verifies (SUB/IFC→VER) but not architecture decision tracing.

Corrections

New degraded-mode requirement: Created {{sub:SUB-REQS-078}} — “When the SCADA server or network backbone fails, the {{entity:Distributed PLC Network}} SHALL maintain autonomous local control with scan cycle ≤100 ms, retain setpoints for ≥72 hours, and resume SCADA synchronisation within 30 seconds of restoration.” Traced to {{sys:SYS-REQS-015}}.

11 new VER entries ({{sub:VER-METHODS-052}} through {{sub:VER-METHODS-062}}) covering safety-critical and process-critical SUB requirements:

• {{sub:VER-METHODS-052}}: Chlorine vacuum fail-safe ({{sub:SUB-REQS-003}})
• {{sub:VER-METHODS-053}}: UV biodosimetry validation ({{sub:SUB-REQS-013}})
• {{sub:VER-METHODS-054}}: Chlorine CT tracer study ({{sub:SUB-REQS-014}})
• {{sub:VER-METHODS-055}}: Rapid mix G-value verification ({{sub:SUB-REQS-036}})
• {{sub:VER-METHODS-056}}: Raw water pump performance ({{sub:SUB-REQS-045}})
• {{sub:VER-METHODS-057}}: SCADA hot-standby failover ({{sub:SUB-REQS-049}})
• {{sub:VER-METHODS-058}}: Emergency diesel start timing ({{sub:SUB-REQS-060}})
• {{sub:VER-METHODS-059}}: Priority load verification ({{sub:SUB-REQS-066}})
• {{sub:VER-METHODS-060}}: Sludge dewatering cake solids ({{sub:SUB-REQS-068}})
• {{sub:VER-METHODS-061}}: Surge transient analysis ({{sub:SUB-REQS-076}})
• {{sub:VER-METHODS-062}}: Degraded SCADA autonomy test ({{sub:SUB-REQS-078}})

All 11 entries have verifies trace links. VER coverage now 62/126 = 49.2%.

7 lint acknowledgements stored in Substrate (3 new this session + 4 from prior sessions).

flowchart TB
    WTP[Water Treatment Plant]
    RWI[Raw Water Intake]
    CF[Coagulation and Flocculation]
    SED[Sedimentation]
    FIL[Filtration]
    DIS[Disinfection]
    CSD[Chemical Storage and Dosing]
    SCADA[SCADA and Instrumentation]
    EPG[Electrical Power and Emergency Gen]
    SLU[Sludge Handling]
    TWD[Treated Water Storage and Distribution]

    WTP --> RWI
    WTP --> CF
    WTP --> SED
    WTP --> FIL
    WTP --> DIS
    WTP --> CSD
    WTP --> SCADA
    WTP --> EPG
    WTP --> SLU
    WTP --> TWD

    RWI -->|raw water| CF
    CF -->|flocculated water| SED
    SED -->|settled water| FIL
    FIL -->|filtered water| DIS
    DIS -->|disinfected water| TWD
    CSD -->|chemicals| CF
    CSD -->|chlorine| DIS
    SED -->|sludge| SLU
    FIL -->|backwash waste| SLU
    SCADA -->|control signals| RWI
    SCADA -->|control signals| FIL
    EPG -->|power| SCADA
    EPG -->|power| RWI

Residual

The IFC-DEFS-011/020 potential duplicate requires engineering judgement during validation — they may legitimately describe the same interface at different abstraction levels, or one may need to be superseded. The 13 empty diagram scaffolds should be populated in a future session if the diagramming tool supports block creation. VER coverage for non-safety SUB requirements (flocculator drives, weir systems, PAC feed) remains below 50% and can be expanded during validation if budget permits.

Next

Validation session (Flow D). Key focus areas: confirm decomposition matches real-world 50 ML/d conventional treatment plant architecture, validate interface protocols and performance values against industry norms (AWWA standards, state drinking water design criteria), assess the IFC-DEFS-011/020 duplicate, and verify that safety-critical subsystems (chlorine gas, UV, emergency power) have adequate requirement depth.