[[File:Gravel_diagram.jpg|thumb| 75 mm drop from the impervious surface onto the gravel diaphragm]]
[[File:Gravel diaphragm.png|thumb|Note the fall from the impervious surface to the gravel surface]]
[[File:Gravel diaphragm.png|thumb|Note the fall from the impervious surface to the gravel surface]]
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*Typical dimensions for the trench excavation are 300 mm deep and 600 mm wide. The trench may be any length,
*Typical dimensions for the trench excavation are 300 mm deep and 600 mm wide. The trench may be any length,
*The trench should be lined with geotextile before filling with gravel,
*The trench should be lined with geotextile before filling with gravel,
−
*River rock or decorative aggregate may be included in a layer at the top of the gravel fill, for aesthetic value.
+
*River rock or decorative [[stone]] may be included in a layer at the top of the gravel fill, for aesthetic value.
==Materials==
==Materials==
===Gravel===
===Gravel===
−
{{:stone}}
+
The type of medium sized aggregates recommended for gravel diaphragms are described in [[choker layer]]. In some contexts it may be desirable to apply a surface layer of more decorative [[stone]].