A common mistake contractors make in Edinburgh is assuming that old landfill sites behave like natural ground. The heterogeneous composition of waste — from ash to organic matter — means the ground can settle unevenly for decades. Without targeted landfill geotechnics, foundations crack, gas migrates, and leachate goes uncontrolled. We assess these risks before any slab is poured. That starts with a calicatas exploratorias to profile the waste layers and identify buried obstructions. Only then can a safe fill depth be defined.
Old landfill sites in Edinburgh can settle unevenly for decades. Landfill geotechnics identifies gas, leachate, and collapse risks before any foundation is placed.
Scope of work in Edinburgh
Typical technical challenges in Edinburgh
The glacial till underlying Edinburgh's landfills is dense but variable. Bands of sand and gravel can create preferential pathways for gas and leachate. Over old waste dumps near the Water of Leith, the water table sits within 2 m of the surface. That raises the risk of leachate breakout and uncontrolled methane migration. A phased investigation combining test pits, gas monitoring, and settlement modelling is the only way to reduce these hazards. We base our gas risk assessments on BS 8485:2019 and CIRIA C665.
Our services
We provide four core services for Edinburgh's landfill and brownfield sites.
Waste profiling and zoning
Test pitting, boreholes, and geophysical surveys to map waste type, thickness, and buried obstructions. We produce cross-sections that show where the ground can be loaded safely.
Gas and leachate monitoring
Installation of gas monitoring wells, leachate sampling points, and flow meters. We track CH4, CO2, O2, and liquid levels over time to meet EA permit conditions.
Settlement and stability analysis
Long-term settlement modelling using compression indices from waste samples. Slope stability checks on cover systems and temporary excavation faces, all to Eurocode 7.
Capping and liner design verification
We verify that the mineral liner, geomembrane, and drainage layer meet the project's permeability targets. Field density tests and water pressure checks ensure the cap functions as intended.
FAQ
What is the typical cost of a landfill geotechnical investigation in Edinburgh?
The cost ranges from £1.430 to £7.120 depending on the site area, number of boreholes, gas monitoring duration, and laboratory testing. A small infill site with five test pits and one gas well will be at the lower end. A former municipal dump with 15 boreholes and long-term monitoring sits at the upper end.
How deep do landfill boreholes need to be in Edinburgh?
Boreholes should extend at least 1 m into the natural ground below the waste, or 3 m if the underlying till contains sand layers. In Edinburgh's old quarries and river valleys, waste can be 15 m thick, so boreholes of 16-18 m are common.
What gas protection measures are required for buildings on Edinburgh landfill sites?
BS 8485:2019 classifies sites by gas regime. For a typical Edinburgh landfill with moderate CH4 flow, a Class C membrane plus passive venting layer is standard. If the site shows sustained high methane levels, active extraction or a Class D membrane may be needed.