Geotextiles

• Material specifications should conform to Ontario Provincial Standard Specification (OPSS) 1860 for Class II geotextile fabrics.
• Fabrics should be woven monofilament or non-woven needle punched. Woven slit film and non-woven heat bonded fabrics should not be used as they are prone to clogging.

Primary considerations are:

1. Maximum forces that will be exerted on the fabric (i.e., what tensile, tear and puncture strength ratings are required?);
2. Load bearing ratio of the underlying native soil (i.e. is the geotextile needed to prevent downward migration of aggregate into the native soil?);
3. Texture (i.e., grain size distribution) of the overlying fill material; and
4. Permeability of the native soil
5. Suitable apparent opening size (AOS) for non-woven fabrics, or percent open area (POA) for woven fabrics, to maintain water flow even with sediment and microbial film build-up;

Recommended criteria for selection of geotextile fabric

Percent media passing 0.075 mm (#200 sieve)	Non-woven fabric apparent opening size (AOS, mm)	Woven fabric percent open area (POA, %)	Permittivity (sec-1)
>85	≤ 0.3	Not recommended	0.1
50 - 85		≥ 4
15 - 50	≤ 0.6		0.2
5 - 15			0.5
≤ 5		≥ 10

Filter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils.

The natural ground material characteristic of or existing by virtue of geographic origin.

A broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.

Soil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls.