Install duct banks within footprint (linear) Checklist

The checklist

Pre-Excavation and Layout

1. 1Verify permits, utility locates, and clearances using GPR and potholing; record locate tickets, pothole photos with depth scale, and approvals per approved project specifications and authority requirements.
2. 2Set out duct bank alignment and grade with total station; establish offset stakes and benchmarks; tolerance ±10 mm horizontal, ±10 mm vertical; save survey file and stake photos.
3. 3Confirm materials on site: conduits, spacers, reinforcement (if required), concrete mix submittals, warning tape, markers; record delivery tickets, lot numbers, and approvals.

Trench Excavation and Bedding

1. 4Excavate trench to design line/grade with shoring or sloped sides as required; trench width = duct bank OD + ≥150 mm clearance each side; daily excavation inspection signed and photographed.
2. 5Trim and compact subgrade to 95% MDD (Standard Proctor) using plate compactor; verify with in-situ density test; level tolerance ±10 mm; attach test report and level readings.
3. 6Place 75–100 mm fine granular or sand bedding; screed level; compact lightly; confirm thickness at start, mid, end with measuring rod; photo evidence with scale.

Spacers and Conduit Placement

1. 7Assemble spacers to maintain conduit separation per approved project specifications and authority requirements (e.g., ≥50 mm clear); verify at start and every 3 m; photo each check.
2. 8Place conduits into spacers to design grade; check fall 0–5 mm/m toward structures if specified; digital level readings every 6 m; acceptance ±5 mm/m; record readings.
3. 9Secure spacers and any reinforcement to prevent float using tie wire at ≤1.5 m intervals; gently wiggle test before pour; supervisor sign-off and photos.
4. 10Install movement sleeves/expansion joints where ducts cross structures or joints as specified; provide 10–15 mm movement gap; photo joint detail with ruler.
5. 11Cap and label all conduit ends to prevent debris and water ingress; labels match drawings; photo caps and tags; record tag schema in checklist.

Concrete Encasement and Curing

1. 12Confirm minimum concrete cover around conduits ≥50 mm on all sides using spacer chairs/gauge blocks; measure at start and mid-bay; photo with scale.
2. 13Verify concrete mix, slump 75–125 mm unless otherwise approved; record batch tickets, on-site slump tests, and sample IDs for compressive tests.
3. 14Place concrete by pump/chute, top-down; use pencil vibrator to consolidate without moving ducts; continuous observer confirms no spacer shift; sign inspection log and attach video/photo.
4. 15Screed and finish encasement top to uniform level; tolerance ±10 mm from design; check with straightedge and staff; photo finished surface.
5. 16Protect and cure: wet burlap or curing compound applied per data sheet; minimum 24 h before backfill; record application time, ambient temperature, and curing method.

Cover Depth, Backfill, and Warning Tape

1. 17Survey top-of-encasement and verify cover depth to finished grade per approved project specifications and authority requirements (typically ≥600 mm); check every 10 m; attach survey points.
2. 18Backfill in 150–200 mm lifts with approved material; compact to 95% MDD; document lift-by-lift density tests and roller/compactor model used.
3. 19Install non-detectable or detectable warning tape 300 mm above duct bank, continuous and centered; photo with tape depth measurement and tape specification.
4. 20Restore surface (subbase, asphalt, concrete, or topsoil) to match adjacent profile; crossfall and level within ±10 mm; photos before/after and level checks.

Markers, As-Builts, and Handover

1. 21Install route markers at changes in direction, entries, and ≤50 m intervals; include durable labels; capture GPS coordinates and photos of each marker.
2. 22Fix marker plates in structures/curbs where required; engraving per specification; photo close-up and context; record plate IDs in log.
3. 23Survey as-built: centerline, elevations, cover depths; produce redlined drawings and point files; submit for review; attach survey report and photo index.
4. 24Final inspection with stakeholders; confirm cable pulls are excluded from this scope; collect signatures, warranties, and QR-linked digital QA pack.

Preview the printable checklist

Preview page one below. Open the image or download the PDF for all pages.

At a glance

• Comprehensive field checklist for linear, within-footprint duct banks, covering trench alignment, bedding, spacers, concrete encasement, cover depth, warning tape, and utility markers. Reduces rework by mandating SI tolerances, batch records, density results, and time-stamped photo evidence.
• Built for multidisciplinary crews and inspectors, it aligns installation with approved project specifications and authority requirements while preserving flexibility for local conditions. Clear acceptance criteria and measurable checkpoints shorten approvals and speed up reinstatement and surface restoration.
• Proven sequencing minimizes conduit float, misalignment, insufficient cover, and mislabelled routes. Guidance on survey control, controlled placement, and curing windows ensures the bank stays stable, drainable, and accurately locatable post-backfill, supporting safe future excavations and maintenance activities.
• Interactive online checklist with tick, comment, and export features secured by QR code.

How to Use This Interactive Checklist

1. Preparation: confirm drawings, specifications, permits, and utility locates; gather tools (total station, digital level, compaction tester, slump cone), safety gear, and forms; brief crew on roles and evidence requirements.
2. Using the Interactive Checklist: start interactive mode, assign items to team members, tick steps as completed, attach photos, test reports, and survey files; add comments for nonconformities and tag reviewers.
3. Export and Sharing: generate a timestamped PDF/Excel export, including photos and logs; share the QR code so stakeholders can verify authenticity and access the live record in the field.
4. Sign-Off: collect digital signatures from contractor, inspector, and owner’s representative; finalize approvals; archive the signed package with QR authentication in the project CDE.

Layout, Excavation, and Bedding Essentials

Accurate survey control anchors a successful linear, within-footprint duct bank. Establish clear offsets and benchmarks so trenching tracks design line and grade, preventing clashes and excessive bends. Trench stability, achieved through shoring or compliant side slopes, minimizes deformation of the bedding and prevents wall collapse. Compact subgrade to 95% MDD and place 75–100 mm of fine bedding to form a uniform support plane. Bedding thickness and level are quick to verify with a measuring rod and staff; record readings and photos at start, mid, and end segments. This disciplined approach preserves conduit geometry and simplifies spacer installation. As-built the trench before conduit placement to catch variances early. A real-world cue: if bedding humps exceed ±10 mm, conduits telegraph high spots and float during the pour. Correcting subgrade now beats chiseling hardened concrete later.

• Survey offsets and benchmarks set with total station.
• Subgrade compacted to 95% MDD; level within ±10 mm.
• Bedding 75–100 mm; verify thickness at multiple stations.
• Shoring or slopes per approved safety plan.
• Photo and survey evidence captured before conduits.

Spacers, Conduit Placement, and Stable Encasement

Spacers lock in conduit separation and cover, eliminating contact points that can abrade cables later. Assemble spacer racks to the approved layout and dry-fit the first bay to validate clearances. Conduit placement follows design grade; verify fall with a digital level where drainage is specified. Tie spacers and any reinforcement to prevent float during the pour. Concrete placement should be controlled and well consolidated—use a pencil vibrator with short insertions to avoid moving the ducts. Confirm concrete slump and batch data on arrival, and collect samples if required. Finish the top neatly to a uniform level within ±10 mm. Early-stage photos of spacer spacing and cover gauges save disputes. If a spacer shifts during vibration, stop, realign, and re-check before continuing.

• Spacer separation verified at start and every 3 m.
• Conduit grade tolerance within ±5 mm/m.
• Concrete slump 75–125 mm unless otherwise approved.
• Vibrate lightly; verify no spacer movement.
• Finish level tolerance ±10 mm with straightedge.

Cover Depth, Backfill, Warning Tape, and Marking

After curing, validate cover depth to the top of encasement along the route. Many authorities require 600 mm or greater; confirm against approved project specifications and authority requirements. Backfill in controlled lifts, compacting to 95% MDD, and document density results. Install continuous warning tape 300 mm above the duct bank so future excavations get early visual cues. Surface reinstatement must match adjacent levels and crossfall, proven by level checks and photos. Install route markers and plates at required intervals and transitions; add GPS positions for fast future locate. Produce full as-builts capturing centerline, elevations, and cover. The result is a safe, traceable utility corridor ready for future cable pulls outside this scope.

• Cover depth checked every 10 m with survey points.
• Backfill in 150–200 mm lifts to 95% MDD.
• Warning tape at 300 mm above encasement.
• Markers at changes, entries, and ≤50 m intervals.
• Complete geo-referenced as-builts and photo index.