How an AI QA Tracker Found 101 Stormwater Pits With No Inspection Coverage

Three months into a major road upgrade, the stormwater drainage was mostly in the ground. The contractor’s HP/WP register had hundreds of entries across dozens of submissions. From the outside, the QA system looked active.

When we mapped that register against the full pit schedule — pit by pit, inspection type by inspection type — we found 101 out of 153 stormwater pits had zero QA coverage. No foundation Hold Point. No excavation Witness Point. No installation Witness Point. Nothing.

This article walks through how that tracker was built, what it found, and why every Principal’s representative on a civil drainage project should be running the same analysis.

Why Manual Register Reviews Miss Coverage Gaps

On a large civil project, a Hold Point and Witness Point register can run to hundreds of entries across earthworks, drainage, pavements, bridgeworks, and utilities. Reviewing it manually — cross-referencing each entry against a pit schedule — is slow and typically only happens when something goes wrong.

The contractor’s location coding system gives you the raw material to do better. On a typical civil drainage project, stormwater HPs and WPs are coded something like this:

  • [PROJECT].SW.04.200.8-200.9 — stormwater line between pits 200.8 and 200.9
  • [PROJECT].N.R.EW.01.CH160-CH410 — North side, Road, Earthworks, chainage 160 to 410

The pit numbers embedded in those codes map each HP/WP entry to a specific physical asset. Extract those references, load the full pit schedule, and you can instantly see what’s covered — and what isn’t.

Building the Tracker

The analysis steps were:

  1. Export all HP/WP register entries to a structured format
  2. Parse pit references from location codes in each entry’s subject line
  3. Load the full pit schedule from the designer’s drainage drawings
  4. For each pit: check which of the four expected inspection types have been raised

The four expected inspections for each stormwater pit are:
– Foundation HP — before blinding concrete, per B30 Cl. 4.4
– Excavation WP — notification before pit/pipe excavation commences
– Installation WP — precast unit placement
– Pipework WP — pipe installation between adjacent pits

The tracker below shows the actual results from a live road upgrade project. Use the tabs to filter by series or coverage status.

LIVE DEMO
Stormwater Pit QA Coverage Tracker — [Road Upgrade Project]

What the Results Showed

101 of 153 pits had zero coverage across all four inspection types. Another 46 were partial. Only 6 pits — all in the earliest-constructed section — were fully complete.

Two systemic patterns emerged beyond the raw numbers:

Excavation WPs were almost universally missing. Across the 300, 400, 500, and 600-series pits, Foundation HPs and downstream installation/pipework WPs had been raised — but the excavation notification step was consistently skipped. This wasn’t random; it was a pattern that pointed to a process gap in the contractor’s QA workflow.

Entire pit series were completely dark. The 310, 320, 400-1 to 400-3, 410-3 to 410-4, 500-10+, and 600-1 to 600-2 pits had nothing raised at all — no HP, no WP of any type. Either those pits hadn’t been constructed at the time of the analysis, or work had proceeded through mandatory inspection points without any notification to the Principal.

Why This Matters Under the Specification

TfNSW B30 Clause 4.4 requires the contractor to present the excavated foundation area to the Principal for inspection before placing blinding concrete for each foundation member. This is a mandatory Hold Point listed in B30 Annexure C1.

If that Hold Point isn’t in the ITP and isn’t raised in the register, the pour goes ahead without a record of Principal inspection. Once blinding is placed, the opportunity to inspect the foundation condition is permanently gone. No retrospective test result can substitute for that inspection.

The same logic applies to the installation and pipework WPs. They exist so the Principal has the opportunity to witness key construction steps — once the concrete is poured and the trench is backfilled, those opportunities are closed.

The Contractor’s Position vs The Principal’s Risk

For pits already built with no coverage, the options are limited:

  • Direct the contractor to provide retrospective evidence — compaction test results, photos, survey records — to demonstrate the work was carried out conformantly. This is possible but relies entirely on the contractor having maintained adequate records independently.
  • Issue an NCR where evidence is insufficient or unavailable, and reserve the right to direct remediation.
  • Accept the gap under a documented risk assessment if the work is accessible for future inspection and the conformance risk is considered manageable.

None of these is a good outcome. The value of finding this while work is still in progress — before the later-series pits are installed — is that you can enforce the inspection process going forward and at least close the gap on the remaining pits.

How Long This Takes to Build

For a project with a structured HP/WP register and a designer-issued pit schedule, the core analysis takes a few hours. The steps are:

  1. Export the register to CSV
  2. Extract pit references from location codes using pattern matching
  3. Load the pit schedule (usually from drainage design drawings or schedules)
  4. Cross-reference: for each pit, which inspection categories have entries?
  5. Flag zero-coverage and partial-coverage pits

The output is a coverage map. Not an audit trail, not a conformance certificate — just a clear picture of where the QA process has and hasn’t been followed. That’s the starting point for every conversation that follows.

earthworks QA coverage article
ITP review article

Methodology developed on a live civil infrastructure project. All pit references and coverage data are illustrative. Specification references are to TfNSW B30 Ed 4/Rev 2.