Joseph Gallagher Ltd is seeking a Principal Geologist to lead how ground conditions are understood, challenged and managed across specialist ground engineering and underground infrastructure projects. This is a technical authority role within a design-and-build contractor: you will influence bids, ground investigation, design strategy and construction methodology, then remain involved when work reaches site. Projects may include tunnelling, HDD, microtunnelling, pipe jacking, shafts, utilities, water and energy infrastructure, complex excavations and groundwater-related works. You will turn geological uncertainty into clear engineering decisions, practical controls and buildable solutions.

What You’ll Be Doing

· Lead geological interpretation and ground-model development from tender and ECI through construction.

· Set investigation, testing, monitoring and parameter-selection strategies proportionate to project risk.

· Own or assure ground-related risk, geological reports, technical submissions and difficult project decisions.

· Challenge assumptions and connect geology, geotechnical design, temporary works and construction method.

· Advise project and commercial teams on risk, opportunity, scope, programme and further investigation.

· Represent JGL in client reviews, workshops and technical discussions with consultants and approving bodies.

· Resolve unexpected ground and groundwater issues with site teams using evidence-led, auditable decisions.

· Mentor engineers and geologists and improve standards, guidance and lessons learned.

What We’re Looking For

· A relevant geology, engineering geology or geoscience degree.

· Chartered status, or clear readiness to achieve it within an agreed period.

· Substantial experience interpreting complex ground investigations and developing ground models for infrastructure or heavy civils.

· Experience across early-stage work, detailed design and construction support.

· Strong judgement on ground variability, groundwater, geotechnical parameters, constructability and risk.

· Experience of technical assurance, developing others and working directly with Network Rail, National Highways and/or comparable major infrastructure stakeholders and approving authorities.

Desirable Experience

· Contractor or design-and-build experience in tunnelling, trenchless, shafts, utilities, water, rail, highways, energy or cable infrastructure.

· Groundwater-control, observational method, digital ground-modelling or ECI experience.

· Experience of additional Environment Agency, major utility or comparable UK regulatory and asset-owner assurance requirements.

Why Join JGL?

You will work where interpretation directly shapes design and construction—not at arm’s length from delivery. The role offers variety across major UK infrastructure sectors, authority to influence project strategy, and the opportunity to build JGL’s geological capability. You will work alongside civil, geotechnical, temporary works and construction specialists on problems where practical judgement matters.