Manchester's subsurface is a layered story of glacial till, river alluvium, and made ground. We see it every time we open a test pit near the Irwell or dig into the stiff boulder clay under Deansgate. A grain size analysis — combining sieving for coarse fractions with hydrometer sedimentation for the fine particles — is the first step to understanding how that soil will behave under load. Without it, you are guessing at drainage, compaction characteristics, and frost susceptibility. We run this test in-house under ISO 17025 accreditation, and we routinely cross-check results against plate load testing to validate bearing capacity predictions on Manchester sites.
A hydrometer on Manchester alluvium often reveals 20-30 percent silt, enough to shift the soil from sand to silty sand and change your drainage assumptions.
Scope of work in Manchester
Critical ground factors in Manchester
The biggest risk we see on Manchester projects is relying on visual-manual classification alone. A builder looks at a brown silty clay and assumes it is cohesive, then designs a foundation that does not account for the sand lenses that act as drainage paths. We have seen retaining walls fail in Salford because the grain size analysis was skipped and the backfill was assumed free-draining. A proper sieve and hydrometer test catches those lenses. It also identifies collapsible soils — loose fine sands that densify when saturated — which are common in the old river terraces along the Mersey Valley. We flag those risks in our reports so the structural engineer can design accordingly.
This service complements our laboratory testing work for a complete project analysis.
Our services
Beyond the standard grain size curve, we offer complementary analyses that give you more confidence in your Manchester ground model.
Full Particle Size Distribution (Sieve + Hydrometer)
Complete grading curve from 125 mm down to 1 micron, including D10, D30, D60, Cu, and Cc. Suitable for foundation design, filter specification, and compaction control.
Combined Grain Size and Atterberg Limits
We pair the sieve-hydrometer test with liquid and plastic limits on the fraction passing 425 microns. This gives you a full classification under the Unified Soil Classification System (USCS) and AASHTO.
Rapid Sieve Only (Coarse Fraction)
For clean sands and gravels where fines content is low, we offer a reduced sieve test down to 75 microns. Results in 48 hours. Ideal for fill acceptance and sub-base verification.
Quick answers
What does a grain size analysis cost in Manchester?
A combined sieve and hydrometer test typically ranges between £70 and £130 per sample, depending on whether you need a full distribution curve or just the coarse fraction. The price includes sample preparation, washing, sieving, sedimentation readings, and a certified report.
How long does the test take from sample delivery?
The sieve portion takes one working day. The hydrometer requires sedimentation readings over 24 hours, so the full test is usually completed within two to three working days. We can expedite to 48 hours for an additional charge.
Do I need both sieve and hydrometer for Manchester soils?
Yes, in most cases. Manchester's glacial till and alluvial deposits often contain a significant silt fraction that passes the 63-micron sieve. Without the hydrometer you miss that fraction, which affects drainage classification, frost heave potential, and compaction behaviour. We recommend the full test for any foundation or earthworks design.
What sample size do you require?
For a standard sieve and hydrometer test we need approximately 3 kg of disturbed material. If the sample contains gravel, we ask for 5 kg. The sample should be sealed in a plastic bag or airtight container to preserve moisture content.