Geotechnical Instrumentation and Monitoring: A Planning Checklist for Project Teams

A useful geotechnical instrumentation and monitoring brief connects five things: the project question, the information already available, the measurements needed, the timing and review process, and the people authorised to act on the results. Starting with an instrument list reverses that logic. The FHWA’s historical instrumentation manual describes monitoring planning as a process that begins with the project objective and questions before instruments are selected, while ISO 18674-1 describes field instrumentation across project stages before, during and after construction.¹²

This guide is intended to help project managers, procurement teams and technical advisers assemble an initial project brief for technical discussion. It is not a completed monitoring design, instrument specification, construction approval or substitute for the responsible engineer’s assessment. Its purpose is to show what is known, what is still uncertain and which decisions need technical ownership before equipment, data services and delivery scope are specified.

What question does the monitoring need to answer?

The first planning task is not choosing a sensor. It is defining the question the monitoring is expected to help answer. A statement such as “monitor movement” or “monitor groundwater” identifies a broad concern, but it does not yet tell the technical team what must be measured, where, over what period, or how the information will be used.

The FHWA planning method makes this sequence explicit: understand the project conditions, develop the relevant working hypotheses, define the geotechnical questions and then identify the purpose and parameters to be monitored.¹ For a current project, those steps need to be applied by the nominated technical team rather than copied as a generic formula.

Define the project concern and intended use of the information

Start by describing the observed or anticipated concern without turning the brief into an unsupported diagnosis. For example, “movement has been observed near the excavation” is an observation. The cause of that movement may still be a technical question.

A useful objective definition should capture:

• the project stage or activity associated with the concern;
• what behaviour or condition needs to be understood;
• what decision, review or record the monitoring information is expected to support;
• the relevant asset, ground zone or work area; and
• important unknowns that the technical team still needs to resolve.

This distinction matters because the same broad concern can lead to different measurement requirements. Monitoring intended to establish a pre-construction reference condition is not the same task as monitoring intended to track behaviour during staged excavation, and neither is automatically equivalent to long-term operational monitoring.

The brief should therefore state the intended use of the information in practical terms. That may include checking whether observed behaviour is consistent with expectations, identifying a trend for technical review, documenting conditions through a construction stage, or providing evidence for an agreed project decision. The project-specific technical team must still determine the appropriate measurement method and decision criteria.

Identify who will review the results and make decisions

A monitoring brief should identify the people or roles that sit between a measurement and a project decision. At minimum, distinguish:

1. who acquires or receives the data;
2. who checks whether the data are usable;
3. who performs any required technical interpretation; and
4. who has authority to decide or instruct the project response.

These roles may be held by different organisations. A data logger, dashboard, automated report or notification can move information between them, but it does not itself perform the engineering decision.

The FHWA manual’s task-assignment section similarly separates activities such as planning, instrument procurement, installation, maintenance, data collection, processing, interpretation and implementation of results.¹ That is useful planning context, not a prescribed responsibility allocation for an Australian project. The actual allocation should reflect the project contracts, nominated advisers and agreed service scope.

What project information should be assembled first?

Monitoring requirements are only as useful as the project information they are based on. Before asking for a detailed instrumentation proposal, assemble the current information that explains the site, the works, the affected assets and any existing monitoring.

Ground information, affected assets and existing monitoring

Relevant inputs may include geotechnical investigation reports, geological information, groundwater information, design drawings, construction drawings, asset drawings, survey records, previous monitoring data and records of existing instruments. The objective is not to collect every available document. It is to identify the sources that materially affect the monitoring question and to make their status visible.

The FHWA manual identifies project layout, subsurface conditions, groundwater conditions, nearby structures or facilities, environmental conditions and planned construction methods as examples of project conditions that may need to be understood before a monitoring programme is developed.¹

Use a simple register rather than allowing critical information to remain implicit:

Old information is not automatically unusable, but its limitations need to be explicit. A superseded drawing, incomplete monitoring history or uncertain reference datum should be marked as such rather than silently treated as current.

Construction sequence, access and information gaps

Monitoring is also affected by how the project will be built and operated. The brief should identify relevant construction stages, temporary works, access restrictions, work areas that will change over time, and any activities that could affect installation or later readings.

Questions worth resolving early include:

• When will the monitoring area become accessible, restricted or altered?
• Which works must occur before instruments can be installed?
• Which project changes are expected to affect the monitored condition?
• Will construction activities create a risk of damage, loss of access or loss of reference points?
• Are there programme interfaces with drilling, surveying, electrical work, telemetry installation or civil works?
• Which missing inputs prevent the technical team from defining coverage, range, timing or installation requirements?

The purpose is to expose dependencies. It is not necessary to request confidential tender material that does not affect the monitoring scope.

Which measurements, locations and instruments need to be defined?

Once the question and available information are clear, the next step is to translate them into measurement requirements. Instrument selection follows from that translation; it should not replace it.

Translate the objective into measurement requirements

Define the physical quantity or behaviour that needs to be observed, the zone or asset it relates to, the expected range of interest, the required data quality and the way the information will be interpreted. The FHWA manual lists parameters such as groundwater pressure, deformation, load and strain as examples, and stresses that parameter selection should follow the project question.¹

A small number of examples illustrates the distinction:

These examples show why a brief should name the measurement requirement before naming a product. The project team may already have a preferred instrument type, but the requirement should still state what that instrument must achieve in the actual installation. For deeper instrument-specific comparison, the separate Piezometers and Inclinometers resources can be used when those articles are published.

Define coverage before comparing equipment

Coverage is a separate decision from product model. A single point measurement, a set of measurement points and a profile along a casing do not provide the same information. The required coverage should reflect the monitoring question, anticipated behaviour and method of later interpretation.

Before comparing equipment, define as far as the available evidence allows:

• the assets, sections, zones or depths that need information;
• whether point measurements or profile information are required;
• what spatial gaps would make interpretation difficult;
• expected measurement range and direction where relevant;
• compatibility with existing casing, datums, readers, loggers or other infrastructure; and
• what needs to remain accessible for checking, maintenance or retrieval.

Do not invent spacing, depths or quantities simply to complete a procurement schedule. Where those values depend on ground behaviour or design assumptions, mark them as unresolved technical decisions and identify who will resolve them.

How should installation, baseline readings and monitoring stages be scheduled?

Monitoring timing should be linked to project change. The brief needs to state when instruments, reference information and review processes must be available relative to the works—not just a generic start date.

Establish the reference information before relevant changes occur

A baseline or reference reading creates the comparison point for later data. Its adequacy depends on the instrument, installation, measurement convention and project purpose. A later reading cannot reconstruct a condition that was never measured before the relevant change.

ISO’s public description of ISO 18674-1 places geotechnical field monitoring in contexts before, during and after construction.² That supports treating timing as a lifecycle issue, but the public abstract does not provide a project-specific baseline procedure or establish Australian compliance requirements.

Reference continuity can also be instrument-specific. SISGEO’s FAQ for its digital inclinometer probes states that probes are individually calibrated and that a reference reading taken with one probe should not simply be treated as interchangeable with another; the manufacturer describes taking a new reference measurement when the probe changes.⁵ This is a useful example of why instrument identity and reference method matter. It is not a universal rule for every monitoring technology, and the FAQ’s description of ISO 18674-3 is a manufacturer account rather than independent review of the full standard.

The brief should record what reference information is required, when it must be collected, who will assess its adequacy and what limitation applies if the intended baseline cannot be obtained.

Define monitoring stages and review points

A stage-based schedule is usually more useful at briefing stage than a guessed fixed frequency. The project team can then assign actual intervals after the technical requirements are established.

This avoids turning an early brief into an unsupported daily, weekly or monthly schedule. The monitoring frequency should be determined from the project question, expected rate of change, decision needs and practical system capability.

How will readings be checked, interpreted and acted on?

Collecting data is only one part of the monitoring process. The brief should make clear how project teams will distinguish a valid reading from a suspect one, how contextual events will be recorded, and who converts measurements into engineering interpretation where required.

Define data checks and supporting observations

The FHWA manual notes that measurements are rarely sufficient by themselves and recommends recording factors that may influence the data, including construction progress, visual observations and relevant environmental conditions. It also recommends planning evidence that helps answer whether an instrument is functioning correctly, including consistency and repeatability checks.¹

For an initial brief, identify the expected controls rather than inventing a detailed quality-assurance procedure. Useful questions include:

• Is every reading traceable to the correct instrument, location, units and timestamp?
• Is the applicable baseline/reference information identifiable?
• How will missing, delayed, repeated or obviously suspect readings be marked?
• Which construction activities, environmental events or site observations should be logged alongside the data?
• Who investigates questionable data and records corrections or exclusions?
• What independent or supporting observations are available when a result appears inconsistent?

The aim is traceability. A clean graph is not evidence by itself that the measurement is correct.

Agree technical review and response responsibilities

The brief should distinguish four stages that are often blurred together:

measurement → data check → technical interpretation → authorised response

For some engagements, the same organisation may perform more than one stage. For others, data acquisition, technical interpretation and project authority are deliberately separated. The brief should state the intended arrangement.

A concise review-and-response checklist is:

• nominate the person or role that reviews data quality;
• nominate the technical adviser responsible for interpretation where interpretation is required;
• define the reporting or review route for normal, suspect and unexpected results;
• identify who approves project-specific trigger or response criteria;
• identify who is authorised to instruct changes to the works or monitoring system; and
• define how communications failures or missing data are escalated without treating absence of data as a measured safe condition.

Automated notifications can support this process, but notification generation, delivery, acknowledgement and engineering action are separate requirements. Detailed remote-monitoring and alert requirements belong in the separate Remote Geotechnical Monitoring requirements resource when published rather than being recreated here.

Who will deliver the work, and what resources are needed?

A technically coherent brief also needs to be deliverable. The required work may span planning, instrument supply, specialist installation, enabling works, commissioning, data acquisition, maintenance, reporting and technical review. Those activities should be allocated explicitly rather than assumed from a package label.

Assign planning, installation and operational responsibilities

Use the brief to identify delivery ownership for each workstream and the evidence expected at completion. A practical starting point is:

A TERRASENSE scope can include instrumentation planning, supply, installation, commissioning, telemetry, reporting and support activities, with engineering interpretation dependent on the engagement. Complementary site works may involve specialist subcontractors. These activities are not automatic inclusions in every proposal; the project-specific scope should identify what is included and who retains technical decision authority.

Identify access, programme and budget dependencies

Budget planning should cover the whole requested monitoring period, not only the instrument purchase. Depending on the project, cost and programme dependencies may include mobilisation, access, enabling works, protection, repeat site visits, readers or loggers, communications, software/platform licences, maintenance, replacement equipment, reporting, data management and project extensions.

The brief does not need prices to identify these dependencies. It needs to expose which items exist, whether they are included in the requested scope, and what project assumptions could change them. A separate Supply-Only vs Turnkey procurement resource can carry the detailed quotation and responsibility comparison when published.

Programme dependencies should be treated in the same way. If a baseline must be completed before excavation, an access window closes after a pour, or a survey reference must be established before installation, those dates are not administrative details—they constrain whether the monitoring plan can be executed as intended.

How will the plan handle changes and project close-out?

Monitoring requirements often change after deployment. Construction sequencing changes, access is lost, an instrument becomes unavailable, monitoring duration is extended, or a new concern emerges. The brief should state how these changes are reviewed so the monitoring arrangement does not drift without technical visibility.

Changes to the works, equipment or monitoring requirements

For each material change, record:

• what changed and when;
• which monitoring objective, instrument, location, reference, schedule or data process may be affected;
• who assesses the technical impact;
• whether a new instruction, baseline/reference, configuration record or acceptance check is required; and
• who communicates the approved change to affected project parties.

Examples include a revised excavation sequence, relocation of access, replacement of an instrument or reader, loss of a monitoring point, extension of the monitoring period, or a change in the project decision that the data must support.

This change record is an editorial recommendation for completeness, not a claim that it is an existing TERRASENSE procedure or a substitute for the project’s formal change-control system.

Completion criteria, records and continuing obligations

Construction completion does not automatically mean monitoring is complete. The responsible project team should decide the monitoring completion criteria based on the project requirement, technical advice and contractual obligations.

Before close-out, clarify:

• who decides that monitoring can stop, continue or transition to another arrangement;
• what final data, reports, installation records, calibration/reference records and configuration information are required;
• whether instruments are to remain in place, be protected, retrieved or decommissioned;
• what access to data must continue after the active monitoring service ends;
• who owns or administers ongoing equipment, accounts or subscriptions; and
• whether continuing monitoring, maintenance or review obligations remain with any party.

Unknown close-out requirements should be carried as open decisions rather than replaced with an assumed end date.

Project planning checklist: what should your brief contain?

The final brief should make the distinction between known, provisional and unresolved information visible. It should be detailed enough for the technical team and suppliers to understand the problem and next decisions, but it should not force the project manager to invent engineering values simply to fill a table.

Use the following matrix as a working planning aid.

A brief is ready for the next technical discussion when its important unknowns are visible and owned—not when every cell contains a guessed answer. The technical team can then convert the brief into project-specific instrumentation, monitoring, data-service and delivery requirements.

Discuss Your Project

If you are preparing an instrumentation and monitoring brief, bring the available project information and the unresolved questions rather than trying to finalise technical values prematurely. TERRASENSE can discuss instrumentation and monitoring requirements, turnkey delivery scopes, and monitoring strategy where requested, subject to the agreed engagement, project conditions and the responsibilities retained by the nominated technical team.

Public references

1. Federal Highway Administration (FHWA), Geotechnical Instrumentation Reference Manual, FHWA-HI-98-034, October 1998, Chapter 6, especially Sections 6.1–6.6, 6.9, 6.12–6.13 (printed pp. 6-1 to 6-6; PDF indices 98–103). https://rosap.ntl.bts.gov/view/dot/75281/dot_75281_DS1.pdf

2. International Organization for Standardization (ISO), ISO 18674-1:2015 — Geotechnical investigation and testing — Geotechnical monitoring by field instrumentation — Part 1: General rules, public Abstract and General information/Status sections. https://www.iso.org/standard/63168.html

3. SISGEO, Vibrating wire piezometers, product page, “Vibrating wire piezometers” description and readout context. https://sisgeo.com/products/piezometers/vibrating-wire-piezometers/

4. GEOKON, Model 6180 Vertical In-Place Inclinometer System — Instruction Manual, Document Revision C.2, release 28 August 2024, Sections 4.1–4.2, printed p. 12 / PDF index 17, together with the Model 6180 product page. These sources describe the model-specific inclination output and calculation of lateral deflection/profile. https://www.geokon.com/content/manuals/6180-MEMS-IPI-Manual.pdf and https://www.geokon.com/6180

5. SISGEO, FAQ#118 — Is it possible to use the reference reading (zero reading) taken with a digital inclinometer probe as a reference reading for another digital inclinometer probe? FAQ body. https://sisgeo.com/products/b-r-a-in-mems-probe-inclinometer/b-r-a-in-mems-probe-inclinometer-2/is-it-possible-to-use-the-reference-reading-zero-reading-taken-with-a-digital-inclinometer-probe-as-a-reference-reading-for-another-digital-inclinometer-probe/