Who we are

Welcome to GSTL

Geo Site and Testing Services Ltd (GSTL) was established in 2011 and is an UKAS accredited laboratory to ISO 17025.

GSTL is at the forefront of geotechnical testing. We offer the most up to date methods both in the laboratory and on-site. We offer soil, aggregate, rock, and concrete testing services to a range of industry sectors. As well as a comprehensive portfolio of on-site testing, window sampling, and coring services.

Our UKAS accredited laboratory and office is situated in Llanelli, South West Wales, with quick access to the M4.

GSTL was acquired by Phenna Group in December 2020. We are one of a group of specialist businesses owned by Phenna. Our focus is on the testing, inspection, certification, and compliance (TICC) sector. Find out more about the Phenna Group portfolio here.

GSTL: Specialised Lab Facilities

GSTL excels in delivering professional and trusted independent geotechnical testing services. Our state of the art laboratory has a dedicated team of 35 staff. Our team provides a wealth of knowledge and combined testing and technical experience.

GSTL is a proud holder of UKAS certificate no 2788 which ensures that you will always receive the highest quality service. Our reputation throughout the years remains consistently high. We constantly develop to offer the most innovative and modern laboratory testing techniques available. Ensuring we can meet the specific needs unique to your site.

We know how important it is for you to access your reports quickly and easily. All your test results and reports are available for you to conveniently download at any time, using our simple online system.

GSTL’s bespoke database allows us to monitor turnaround times. As well as keep track of equipment calibrations and staff training. Our staff are kept up to date with the latest testing techniques, delivering you with the best service possible.

GSTL Values

All GSTL employees follow our four core company values:

  • white tick icon Customer first – staff will provide a positive customer experience and deliver services that consistently exceed customer expectations
  • white tick icon Trust – employees will inspire trust by showing integrity, honesty, and transparency in their words and actions
  • white tick icon Innovation – our team will share ideas and constantly innovate to offer clients the most modern, leading-edge testing services available
  • white tick icon Teamwork – our employees support each other in a united effort to deliver high-quality tests and reports on time, every time

GSTL Clients

At GSTL, we have extensive experience of working with clients from a variety of sectors. Delivering a diverse array of professional testing services, including:

  • Geotechnical classification testing for motorway and infrastructure upgrades
  • Classification testing, chemical testing, and effective stress testing for bridges
  • Sample logistics, soil testing, rock testing, and plate bearing testing for the renewable energy industry
  • Soil testing services: including classification testing, permeability testing, and shear strength testing for local authorities and flood defence projects
  • Geotechnical testing works for nuclear power station sites

Read our case studies to learn more.

GSTL Mission Statement

GSTL is a leading specialist in the delivery of high-quality geotechnical testing of construction and civil engineering materials. This includes, Soil, Rock, Aggregate and Concrete materials.

Our mission is to keep our clients’ projects on budget and on track. Achieved through providing accurate, comprehensive, and rapid UKAS accredited laboratory and site testing services.

At GSTL we aim to deliver exceptional customer service. Using modern methods and the latest technology on all site and ground investigations, we deliver precise results in easily accessible reports.