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|  | + | <p>Geotextiles prevent downward migration of smaller particles in to larger aggregates, and slump of heavier particles into finer underlying courses. <br> | 
|  | + | The formation of biofilm on geotextiles has also been shown to improve water quality:<br> | 
|  | + | *By degrading petroleum hydrocarbons[https://www.icpi.org/sites/default/files/techpapers/1309.pdf] | 
|  | + | *By reducing organic pollutant and nutrient concentrations [http://www.mdpi.com/2073-4441/7/4/1595/pdf] | 
|  | + | </p> | 
|  | + | <p>When installing geotextiles an overlap of 150 - 300 mm should be used.</p>   | 
|  | Material specifications should conform to [http://www.raqsb.mto.gov.on.ca/techpubs/OPS.nsf/0/2ccb9847eb6c56738525808200628de1/$FILE/OPSS%201860%20Apr12.pdf Ontario Provincial Standard Specification (OPSS) 1860 for Class II geotextile fabrics]. |  | Material specifications should conform to [http://www.raqsb.mto.gov.on.ca/techpubs/OPS.nsf/0/2ccb9847eb6c56738525808200628de1/$FILE/OPSS%201860%20Apr12.pdf Ontario Provincial Standard Specification (OPSS) 1860 for Class II geotextile fabrics]. | 
|  | *Fabrics should be woven monofilament or non-woven needle punched.   |  | *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. |  | *Woven slit film and non-woven heat bonded fabrics should not be used, as they are prone to clogging. | 
| − | <p>Primary considerations are: | + | <p>In choosing a product, consider: | 
|  | <ol> |  | <ol> | 
| − | <li>Maximum forces that will be exerted on the fabric (i.e., what tensile, tear and puncture strength ratings are required?);</li> | + | <li>The maximum forces that will be exerted on the fabric (i.e., what tensile, tear and puncture strength ratings are required?),</li> | 
| − | <li>Load bearing ratio of the underlying native soil (i.e. is the geotextile needed to prevent downward migration of aggregate into the native soil?);</li> | + | <li>The load bearing ratio of the underlying native soil (i.e. is the geotextile needed to prevent downward migration of aggregate into the native soil?),</li> | 
| − | <li>Texture (i.e., grain size distribution) of the overlyingfill material; and</li> | + | <li>The texture (i.e., grain size distribution) of the overlying and underlying materials, and</li> | 
| − | <li>Permeability of the native soil</li> | + | <li>The 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.</li> | 
| − | <li>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;</li>
 |  | 
|  | </ol> |  | </ol> | 
|  | <br> |  | <br> | 
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|  |    <tr><td align="center" valign="middle">≤ 5</td><td align="center" valign="middle">≤ 0.6</td><td align="center" valign="middle">≥ 10</td><td align="center" valign="middle">0.5</td></tr> |  |    <tr><td align="center" valign="middle">≤ 5</td><td align="center" valign="middle">≤ 0.6</td><td align="center" valign="middle">≥ 10</td><td align="center" valign="middle">0.5</td></tr> | 
|  | </table> |  | </table> | 
| − |   | + |    | 
|  | [[category:materials]] |  | [[category:materials]] |