Permeability is a section property
A surface that looks like loose gravel is not automatically a compliant permeable pavement. Infiltration depends on the surface, compaction, aggregate grading, base, native soils and drainage outlets. Determine whether the design needs infiltration into the subgrade, temporary detention or positive conveyance elsewhere.
Understand surface grading
Densely graded aggregate may compact into a stable surface but contain fines that restrict infiltration. Open-graded material may transmit water more readily but behave differently for accessibility and stabilization. Aggregate design should reconcile these properties instead of assuming maximum void space provides the best path.
Protect the pathway base
Subgrade saturation, sediment migration and inadequate base storage can undermine an otherwise well-selected surface. Site-specific soils and rainfall determine whether subsurface drainage or separation layers are needed. Coordinate with a qualified designer when the pathway forms part of a regulated stormwater strategy.
Evaluate surface treatments
A polymer binder can affect the behavior of the aggregate surface. Do not claim a specified infiltration rate or compliance solely because the binder is described as water-based. Request data for the actual installed system and build a mockup using the proposed aggregate if permeability is a critical requirement.
Inspection and maintenance
Sediment, leaf litter, nearby landscaping soil and washouts can change drainage over time. Establish cleaning and inspection procedures compatible with the chosen surface. Document observed ponding or erosion so the owner can distinguish clogged surface conditions from more fundamental subgrade or outlet problems.
Test the complete drainage section
A visible aggregate texture is not proof of infiltration capacity. Water must pass through the surface and underlying layers without causing saturation or instability. Consider maintenance sediment, native soil permeability and drainage outlets. Where a regulatory stormwater requirement applies, request test evidence for the full installed assembly.
Field review before final selection
For permeable gravel pathways, evaluate the proposed aggregate and surrounding site conditions against the actual project goals. Maintain an inspection record of material source, finished grade, surface condition, curing weather and any failed mockup locations. Treat supplier coverage calculations as planning figures until verified by a project-specific test, and confirm procurement details before scheduling the work.