{
  "plant": "PEG227, Georgetown Regional / Jelutong STP",
  "audit_date": "2026-10-25",
  "scope": "Historical dimension interpretation, not a current survey or as-built verification",
  "sources": [
    {
      "id": "M01",
      "title": "Foundation Works for a Sewage Treatment Plant Using Ground Improvement Methods in Malaysia",
      "authors": "Y. W. Yee, C. G. Chua, H. K. Yandamuri, Keller (M)",
      "date": "2009 technical paper; publisher page copyright 2010",
      "original_url": "https://rpsonline.com.sg/proceedings/9789810831240/html/GI173.php",
      "doi": "10.3850/9789810831240_GI173",
      "access_url": "https://www.scribd.com/document/263231290/coloane-beton",
      "locator": "Technical paper 10-65 E, section 3.0 Treatment Plant Structures. Original proceedings pp.677-684; exact section page unverified.",
      "status": "Public indexed reproduction text verified; original publisher metadata verified. Full original PDF not retrieved. Saved HTML is a public preview page, not the paper PDF.",
      "excerpts": {
        "group_dimension": "approximately 90m x 60m x 7m high",
        "upper_floors": "additional 2 floors on top of the tank",
        "retaining_wall": "up to 4m high",
        "joint": "25mm gap"
      },
      "local_html": "/opt/data/research/georgetown-stp-peg227-2026-10-25/measurement-audit/sources/M01-Keller-technical-paper-10-65E-Scribd-public-preview.html"
    },
    {
      "id": "M02",
      "title": "Ground Improvement - Applications and Quality Control",
      "author": "V. R. Raju, Keller Far East",
      "date": "16-18 December 2010",
      "access_url": "https://www.scribd.com/document/294610796/Ground-Improvement",
      "original_index_url": "https://citeseerx.ist.psu.edu/document?doi=6a648ea49af770a5461d79b18acc2a7333fd9d35&repid=rep1&type=pdf",
      "locator": "IGC 2010 GEOtrendz, printed p.129, Sewage Treatment Plant on Marine Clay and Old Landfill; Figure 9.",
      "status": "Public indexed reproduction text verified; original PDF not retrieved. Public preview HTML saved.",
      "excerpts": {
        "reactor_dimension": "12 sequential batch reactors of size 80 m x 60 m x 7 m tall"
      },
      "lineage": "General review cites Yee et al. (2009) for fuller project details; it does not explain the differing dimensions.",
      "local_html": "/opt/data/research/georgetown-stp-peg227-2026-10-25/measurement-audit/sources/M02-Raju-IGC2010-Scribd-public-preview.html"
    },
    {
      "id": "M03",
      "title": "Ground Improvement, Third Edition",
      "editors": "Klaus Kirsch and Alan Bell",
      "date": "2013",
      "access_url": "https://books.google.com/books?id=pWaRpPfmHOYC&pg=PA49",
      "indexed_url": "https://ndl.ethernet.edu.et/bitstream/123456789/33970/1/Ground%20Improvement.pdf",
      "locator": "Printed p.49, section 2.8.4, Figure 2.21.",
      "status": "Root previously verified the figure visually in authorised Google Books preview. Dimension paragraph checked in indexed text. Entire book not downloaded.",
      "excerpts": {
        "group_dimension": "twin tanks of approximately 90 m × 60 m × 7 m"
      },
      "lineage": "Reproduction of Keller (2009), technical paper/brochure 10-65 E. Apparent IO-656 in some OCR is not a reliable identifier.",
      "existing_preview": "/opt/data/research/georgetown-stp-peg227-2026-10-25/previews/PEG227-published-whole-site-layout-Keller-2009.jpg"
    },
    {
      "id": "M04",
      "title": "Ground Improvement Techniques for Infrastructure Projects in Malaysia",
      "authors": "V. R. Raju and Y. Hari Krishna",
      "date": "1-6 October 2008",
      "access_url": "https://www.scribd.com/document/478652416/TC-on-GI-GS-First-Report-pdf",
      "locator": "Embedded IACMAG 2008 paper, section 5.1; Figure 10 plan, Figure 13 hydrotest photos, Figure 14 water-height/settlement graph. Proceedings pp.3671-3682; exact individual page unverified.",
      "status": "Public indexed reproduction text only. Original conference PDF not retrieved; graph pixels not inspected in this audit.",
      "excerpts": {
        "group_dimension": "90m x 60m x 7m high",
        "layer": "150mm thick",
        "graph_title": "Avg. Water Height (SBR 7&8)"
      },
      "lineage": "Earlier contractor account sharing authorship with M01. It explicitly describes six twin groups and two extra floors over SBR 1&2.",
      "caution": "The compilation also contains other projects: the 23m-diameter, 15m-high digesters buried 8m refer to Bunus, not Jelutong."
    },
    {
      "id": "M05",
      "title": "Government of Penang Gazette, Volume 51 No.21, Notice 435",
      "date": "11 October 2007",
      "notice_date": "12 September 2007",
      "url": "https://govdocs.sinarproject.org/documents/state-governments/penang/government-of-penang-gazette/pggn021y2007.pdf",
      "locator": "Printed p.588 / PDF p.2, Notice 435 schedule.",
      "status": "Official-agent PDF retrieved; local extracted text independently checked.",
      "excerpts": {
        "plot": "No. Pelan Akui—PW 802. Luas—14.674 hektar."
      },
      "local_file": "/opt/data/research/georgetown-stp-peg227-2026-10-25/investigation-round2/official/2007-Penang-Gazette-vol51-no21-notice435.pdf"
    },
    {
      "id": "M06",
      "title": "Three Years Operation of a 270 MLD C-TECH SBR - Lessons for New Technologies",
      "author": "M. C. Goronszy",
      "date": "2011; exact day/month unverified",
      "event": "5th European Water & Wastewater Management Conference",
      "url": "https://conferences.aquaenviro.co.uk/wp-content/uploads/sites/7/2018/08/Goronszy-M.-Bisasco-Pty-Limited.pdf",
      "locator": "Background to process selection; exact PDF page unverified.",
      "status": "Primary publisher PDF indexed text verified; current PDF fetch failed (web 404, VPS 403). No PDF bytes or page image.",
      "excerpts": {
        "burial_constraint": "in ground basin construction depth limit of 2 metres"
      },
      "lineage": "Process-provider account; historical design constraint, not a current level survey.",
      "event_metadata_url": "https://aquaenviro.co.uk/proceeding-category/5th-european-waste-water-management-conference/page/2/"
    }
  ],
  "evidence_matrix": [
    {
      "id": "D01",
      "subject": "Twin-group footprint",
      "value_m": [
        90,
        60
      ],
      "basis": "Each of six twin-tank groups, comprising twelve basins",
      "sources": [
        "M01",
        "M03",
        "M04"
      ],
      "status": "Explicit, approximate, historical",
      "interpretation": "The 90 by 60 m dimensions describe a pair. Individual basin clear spans, wall thicknesses and the measurement faces are unspecified.",
      "allowed_label": "Historical twin-group size: approximately 90 × 60 m; not surveyed."
    },
    {
      "id": "D02",
      "subject": "Conflicting footprint statement",
      "value_m": [
        80,
        60,
        7
      ],
      "basis": "Raju describes twelve reactors without defining a twin-group measurement",
      "sources": [
        "M02"
      ],
      "status": "Unresolved conflict",
      "interpretation": "Do not average 80 and 90, or explain the difference as buildings/walkways without drawing evidence. The source does not resolve individual versus group dimensions.",
      "allowed_label": "Alternative 2010 report: 80 × 60 × 7 m; basis unresolved."
    },
    {
      "id": "D03",
      "subject": "Tank height",
      "value_m": 7,
      "basis": "Reported nominal tank height, described as high/tall",
      "sources": [
        "M01",
        "M02",
        "M03",
        "M04"
      ],
      "status": "Historical wording corroborated; datum unknown",
      "interpretation": "This is not verified operating water depth. Slab, raft, wall-crest, roof and ground datums are undefined; buried and above-ground portions remain unknown.",
      "allowed_label": "Historical tank height: approximately 7 m; datum/current height unverified."
    },
    {
      "id": "D04",
      "subject": "Floors above SBR 1&2",
      "value": 2,
      "unit": "additional floors",
      "sources": [
        "M01",
        "M04"
      ],
      "status": "Explicit historical description",
      "interpretation": "Administration/equipment accommodation above the twin group. No floor-to-floor height, overall building height or current use is specified.",
      "allowed_label": "Historically two extra floors above SBR 1&2; storey heights unknown."
    },
    {
      "id": "D05",
      "subject": "Separation gap",
      "value_m": 0.025,
      "sources": [
        "M01"
      ],
      "status": "25 mm stated",
      "interpretation": "No joint detail locates every interface. Do not use this as an aerially measured gap or as row spacing."
    },
    {
      "id": "D06",
      "subject": "Perimeter RC retaining wall",
      "value_m": 4,
      "basis": "Reported historical maximum",
      "sources": [
        "M01"
      ],
      "status": "Up to 4 m, not uniformly 4 m",
      "interpretation": "Retaining-wall height does not establish fence height or current boundary-wall geometry."
    },
    {
      "id": "D07",
      "subject": "Land reservation area",
      "value_ha": 14.674,
      "converted_value_m2": 146740,
      "sources": [
        "M05"
      ],
      "status": "Official 2007 schedule",
      "interpretation": "Timur Laut, Seksyen 1 Jelutong, Lot Petak A, certified plan PW802. Polygon, bearings and side lengths were not retrieved. Area alone cannot calibrate the current fence boundary."
    },
    {
      "id": "D08",
      "subject": "In-ground construction-depth constraint",
      "value_m": 2,
      "sources": [
        "M06"
      ],
      "status": "Primary indexed wording; page/bytes unavailable",
      "interpretation": "Historical design limit related to groundwater. It does not prove actual burial of every basin. Do not subtract it from 7 m to assert 5 m above ground."
    },
    {
      "id": "D09",
      "subject": "Hydrotest water-height graph",
      "sources": [
        "M04"
      ],
      "status": "Indexed labels show a 0-7 m axis; curves unverified",
      "interpretation": "An axis limit and filling procedure do not establish exact test depth or normal operating level."
    },
    {
      "id": "D10",
      "subject": "Ground-treatment depths",
      "sources": [
        "M01",
        "M02",
        "M04"
      ],
      "status": "Exclude from tank depth",
      "interpretation": "VCC/DSM depths and groundwater/soil-layer thicknesses refer to foundations and ground conditions. They are not basin height, water depth or roof elevation."
    },
    {
      "id": "D11",
      "subject": "Other plant units",
      "sources": [],
      "status": "No verified dimensions found",
      "interpretation": "No actual heights/depths obtained for pump wells, grit/grease chambers, sludge tanks, digesters, gas holders, disinfection channel, outfall inverts or auxiliary buildings. No volume-derived or generic-storey inference."
    }
  ],
  "decision": "90 × 60 m applies explicitly to twin groups in the most specific accounts. The 80 × 60 × 7 m alternative conflicts. Historical tank height is about 7 m; current dimensions and operating depths remain unverified.",
  "dependency": "M03 reproduces M01. M04 shares contractor/authorship lineage. Repeated citations are not independent field measurements.",
  "method": "Public sources only; no purchase, outreach, registration or access bypass. Files are HTML snapshots/metadata unless identified otherwise.",
  "corroboration_manifest": "/opt/data/research/georgetown-stp-peg227-2026-10-25/measurement-audit/sources/primary/dimension-corroboration-manifest.json"
}