Ground Investigation Commissioning Preparation Checklist

Write down who asked for the investigation — a designer, an engineer, a lender, the local authority, or your own caution — and what they said they needed from it.

The requester determines what the work has to cover, and an investigation commissioned without that conversation frequently misses what was actually wanted.

Note which decisions are waiting on the result, such as a foundation approach or whether a basement is being pursued, and record which of those are urgent.

Naming the dependent decisions is what lets a professional say whether the scope proposed will actually unblock them.

Ask your designer or engineer to state in writing what information they need from the ground before they can proceed, and keep that statement in the file.

A written statement of need is the closest thing to a brief an owner can hold, and it is what makes competing proposals comparable.

Collect anything already known about the ground here, including previous reports, information given at purchase and what neighbours have described, marking each source.

Existing information can sometimes narrow what is needed, but only if it reaches the person scoping the work rather than sitting in a drawer.

Write down what you know about the site's history, including anything previously built here, filled in, demolished or tipped, and how you know it.

Site history shapes what is worth looking for, and an owner or neighbour's account is often the only record of a filled pond or an old outbuilding.

Measure roughly how wide the narrowest point of the route onto the site is, including gates, side passages and gaps between buildings, and photograph each.

Equipment is chosen to suit access, so describing the access accurately beforehand is what avoids the wrong plant arriving.

Note anything overhead along the route or above the proposed positions — cables, branches, a canopy, a first-floor projection — and photograph each obstruction.

Overhead constraints are frequently missed in photographs taken at eye level, and they matter to anything that has to stand upright.

Never approach, measure against or attempt to establish clearance from overhead cables; report what you can see and leave the assessment to the contractor.

Note whether the route or any proposed position involves land you do not own or share, and write down who would have to agree to it.

Access over a shared drive or a neighbour's land is a conversation to have early, and it is one that cannot be resolved on the day.

Photograph the surfaces the equipment would cross — lawn, block paving, a resin drive, a soakaway area — and note which of them you would mind being marked.

Damage to a driveway is a foreseeable consequence rather than a surprise, and stating in advance what you care about changes how the work is planned.

Note where vehicles can stand, whether there is anywhere to park nearby, and whether water or power is available on site if it is asked for.

These are ordinary practical questions that get asked at short notice, and answering them in the brief removes a round of messages.

Decide who will be present, how the contractor gets onto the site, and who has authority to answer a question if something unexpected is found.

Decisions get made on site whether or not anyone is available, so naming the person who can answer avoids them being made by default.

Collect every plan, drawing or letter you hold that shows buried services, including anything provided when the property was bought or when work was last done.

Owner-held records are often the only documentation of a private supply or a run that was diverted during earlier work.

Photograph where the water, gas, electricity and any other supply enters the building, and note the direction each appears to come from.

The entry point and its direction is a genuine clue to where a run crosses the garden, and it is information only the occupier can easily give.

Walk the site and photograph every cover, marker post, stop tap, inspection chamber and grating, marking each position on a sketch plan.

A marked plan of visible covers is one of the more useful documents to hand over before anybody plans where a hole goes.

Write down anywhere you know has been dug before — a soakaway, a cable to a shed, an old drain, a garden light run — and when it was done.

Private runs installed by previous owners appear on nobody's records, and the occupier's memory is the only source that exists.

Send everything you have gathered to whoever is carrying out the work before a date is agreed, and keep a copy of what you sent and when.

Handing information over late means it arrives after the positions have been planned, which is the point at which it is least useful.

Record what you know and hand it over, but leave the question of whether any position is clear of services entirely to the people carrying out the work.

Owner-held records are incomplete by nature, and treating them as clearance is how buried services get struck.

Establishing what is buried and whether a position can be bored is the responsibility of suitably qualified people, and never a conclusion for an owner to reach.

Ask for a plan showing the proposed positions before the visit, and keep it in the file alongside the note of what the investigation is meant to answer.

A marked plan is the artefact that connects the scope to the site, and without one nobody can say afterwards whether the work matched the brief.

Ask how the proposed positions relate to where the new building or extension would sit, and record the answer in your own words in the file.

Investigation carried out well away from the proposed footprint answers a different question, and it is reasonable to understand why positions were chosen.

Note where the proposed positions sit in relation to trees, hedges, the existing building and any boundary structure, and raise anything that concerns you.

Proximity to trees and to existing foundations is frequently the reason a position was chosen, and asking makes that reasoning explicit.

Agree who may move a position on the day if something is in the way, and record that agreement rather than leaving it to whoever is on site.

Positions do get moved, and a relocated hole that nobody recorded is a gap between what was designed and what was investigated.

Ask for a record of where the holes actually went, and keep it with the report rather than relying on the original proposed plan.

The as-executed positions are what the report describes, and a file holding only the intended plan quietly misrepresents the work.

Ask for the scope in writing, listing what will be recorded, sampled and tested, and keep that list at the front of the investigation file.

A written scope is the only way to tell later whether something was excluded deliberately or was never considered at all.

Ask whether contamination is within the scope of this work or is a separate exercise, and record the answer rather than assuming either way.

Owners frequently assume that anything going into the ground looks at everything about it, and the assumption is usually wrong.

Whether contamination assessment is needed on a particular site is a determination for qualified professionals, and what applies locally should be confirmed with the relevant local authority.

Ask whether ground gas is being considered, whether that needs anything left in place afterwards, and how long such an arrangement would remain on site.

Monitoring arrangements can stay on a plot for some time, which is a practical matter for a household and is rarely mentioned unprompted.

Ask whether anything will be recorded about water in the ground, and what such an observation would and would not represent.

Water encountered on a single occasion is an observation at that moment, and knowing that in advance stops it being read as a permanent description.

Ask who will interpret the findings and whether interpretation is included, or whether you will be given factual records for somebody else to use.

A factual record and an interpretative report are different products, and owners regularly discover the difference only when a designer asks for the other one.

Ask whether samples are retained after the work, for how long, and whether further testing could be carried out later without returning to site.

Retained samples can sometimes answer a later question without new holes, but only if the question is asked before they are disposed of.

Ask what happens to the material brought up out of the ground, whether it stays on site and if so where it will be placed.

Material coming out of holes has to go somewhere, and a garden is a small place for it to be left without prior agreement.

Ask how each hole is left at the end of the work, and whether anything remains in place afterwards that you will need to be aware of.

Knowing what will still be in the garden next week is a reasonable thing to establish, and it is rarely stated unless asked.

Agree in writing what reinstatement is included for lawn, paving, drives and planting, and photograph every affected area before the work begins.

Dated before photographs and a written reinstatement expectation are what make an afterwards conversation short instead of long.

Ask what arrangements apply while the work is under way, particularly if children, pets or other occupiers will be on the property that day.

Household arrangements are the owner's part of this, and they are easier to plan when the answer is known in advance.

Do not approach, uncover or inspect any open hole or installed monitoring arrangement; leave everything on site to the people responsible for it.

If anything is installed to be revisited, record what it is, where it is, who will return and what you should do if it is disturbed.

An installation left in a garden with no explanation becomes an object nobody can account for within a surprisingly short time.

Write down, in your own words, that the findings describe the positions investigated, and keep that note with the report so it is read alongside it.

Ground varies across a plot, and a report is often read years later by someone who was not part of the conversation about its scope.

Ask what could be present in the ground between the positions investigated, and what kind of finding would prompt a recommendation for further work.

The answer tells you how much confidence the findings support, which is more useful than the findings themselves in isolation.

Ask who the report is addressed to, who is entitled to rely on it, and what would be involved if a later party needed to rely on it.

Reliance is a question owners meet years later when selling or refinancing, and it is far easier to ask about at the outset.

Ask whether the findings would be considered current in several years, and note the answer rather than assuming a report is permanent.

Owners often hold a report for a long time before it is needed, and whether it is still usable is a question worth having asked early.

Keep the report, the positions plan, the agreed scope and your before photographs together in the property file rather than in a project email folder.

This set of documents is worth more together than separately, and project email folders are the first thing to disappear after completion.