What Should a Trial Trench Survey Report Include?

What Should a Trial Trench Survey Report Include?

A trial trench survey report is one of the most important documents produced during a utility investigation. It records the exact position, depth and condition of underground services exposed during excavation — and it may be referred to for years to come by engineers, contractors and utility companies.

Getting the report right matters. An incomplete or inaccurate report can lead to utility strikes, design errors and costly disputes down the line. This guide covers everything a professional trial trench survey report should include.

1. Project Information

Every trial trench survey report should start with clear project information so it can be identified and filed correctly. This should include:

• Project name and number
• Site address and location
• Client name
• Engineer or surveyor name
• Date of survey
• Trench reference number (e.g. TT-001, TT-002)
• Weather conditions on the day of survey

2. Trench Location and Dimensions

The report should clearly record the physical location and size of the trial trench:

• Grid reference or coordinates — Easting and Northing of the survey reference point
• Trench width — the excavated width in metres
• Trench depth — the total depth excavated in metres
• Bearing — the direction of the trench (degrees from North)
• Above Ordnance Datum (AOD) level — the reduced level at ground surface if known
• Groundwater level — if encountered during excavation

3. Ground Build-Up Layers

The ground build-up describes the layers of material from the surface down to the base of the trench. This should be recorded in sequence from top to bottom and include:

• Surface type — e.g. Tarmac, concrete, grass, footpath
• Surface thickness — in millimetres
• Sub-layers — e.g. binder course, base course, sub-base, bedding
• Natural ground — e.g. clay, sand, made ground, gravel
• Depth of each layer — top and bottom depth from ground level in metres

An accurate ground build-up helps engineers understand the local ground conditions and is essential for any subsequent design work in the area.

4. Underground Service Schedule

The service schedule is the heart of the trial trench survey report. For every underground service exposed it should record:

• Service type — water, gas, electric LV, electric HV, telecoms, foul sewer, surface water, street lighting, oil etc.
• Depth to top of service — from ground level in metres
• Depth to bottom (invert) of service — from ground level in metres
• Diameter — in millimetres
• Material — e.g. MDPE, cast iron, uPVC, clay, HDPE
• Colour — pipe or cable colour
• Horizontal distance from reference point — in metres
• Grid coordinates — Easting and Northing calculated from bearing and distance
• Condition — any visible damage, corrosion or unusual findings
• Notes — any relevant observations

Each service should be given a unique reference number (e.g. Service 1, Service 2) that ties it to the cross-section diagram and service schedule.

5. Cross-Section Diagram

The cross-section diagram is a scaled drawing showing the side view of the trial trench. It is the most visual and most useful part of the report for engineers and designers. It should show:

• Ground level (GL) clearly marked at 0.00m
• Trench walls showing the excavated profile
• Ground build-up layers drawn to scale with depths labelled
• Each underground service drawn in the correct position with its service number
• Depth scale on the left hand side in metres
• Horizontal scale showing distance from the reference point
• AOD level if recorded
• Groundwater level if encountered
• North arrow and reference point

The cross-section should be drawn to a consistent scale — typically 1:20 or 1:25 — and should be clear enough for anyone reading the report to immediately understand the position and depth of every service found.

6. Site Photographs

Photographs provide visual evidence of what was found during the survey and should be included in every trial trench report. Essential photographs include:

• Overview of the trench location — showing the surrounding area and any reference points
• Each service exposed — close-up showing the pipe or cable clearly
• Depth measurement — a photograph showing a tape measure or staff against each service
• Ground build-up — showing the layers visible in the trench wall
• Any unusual findings — damaged services, unexpected materials etc.

Photographs should be clearly labelled with the trench reference and service number so they can be matched to the service schedule.

7. Surveyor’s Notes and Observations

The report should include a notes section for any additional observations that don’t fit neatly into the schedule. This might include:

• Services that could not be exposed safely
• Evidence of previous excavation or backfill
• Conflicting utility records — services found in different positions to records
• Ground conditions that differed from expectations
• Any safety concerns observed during the survey

8. Report Format and Presentation

A professional trial trench survey report should be presented clearly and consistently. Best practice is to produce the report on A3 landscape format — this gives enough space for the cross-section diagram and service schedule to be shown side by side on the same page.

The report should include your company name, logo and contact details and should be issued as a PDF to ensure the formatting is preserved when shared with clients and other engineers.

How Trial Trench Surveys Software Helps

Trial Trench Surveys is purpose-built software for civil engineers that captures all of the above information and generates a professional A3 PDF report automatically.

As you enter each service the cross-section diagram draws live on screen — so you can see the survey building up in real time. Grid coordinates are calculated automatically from bearing and distance. Photos can be attached to each service and included in the report.

The finished report includes:

• Project information header
• Trench location and dimensions
• Ground build-up schedule
• Full service schedule with depths, diameters, materials and coordinates
• Scaled cross-section diagram
• Site photographs
• Surveyor notes

Everything a professional trial trench report needs — generated in one click.

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Summary — Trial Trench Survey Report Checklist

A complete trial trench survey report should include:

1. Project information — name, date, engineer, client
2. Trench location — coordinates, bearing, AOD level
3. Trench dimensions — width and depth
4. Ground build-up layers — surface to base of trench
5. Service schedule — type, depth, diameter, material, colour, distance, coordinates
6. Cross-section diagram — drawn to scale showing all services and layers
7. Site photographs — overview, each service, depth measurements
8. Surveyor notes — any additional observations

A well-prepared trial trench report protects everyone involved — the client, the engineer and the contractor — by providing an accurate and permanent record of what was found underground.