This uses clean gravel consisting of uniform, rounded stones and small pebbles.

This percid darter needs fresh-flowing water with a clean gravel and mixed rubble substrate.

The mine administration at once ordered the delivery of clean gravel, and a few days later it actually arrived.

In many cases, the material used is a 4-inch layer of clean gravel.

For example, the soil at the surface has become contaminated, so engineers decided to spread clean gravel on top to reduce the exposure of workers.

Look for areas of clean bright gravel as these areas are where the fish lay their eggs.

We'd have to scrub the gravel clean first, and even if we did sell it they're projecting a rate higher than the current rate.

It was well-tended, the crushed gravel clean and without unwanted growth.

Because the Tippecanoe darter needs clean gravel to spawn its eggs, it is very sensitive to siltation.

Beyond him lay a wide tree-lined road and pavements of clean beige gravel.