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<ul><li>Material specifications should conform to Ontario Provincial Standard Specification (OPSS) 1860 for Class II geotextile fabrics.</li>
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[[File: Geotextile-GSI.JPG|thumb|The properties of geotextiles vary widely.]]
<li>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.</li>
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See [[Clogging]] for notes on their application in LID structures.  
</ul>
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<p>Primary considerations are:
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<ol>
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<li>Maximum forces that will be exerted on the fabric (i.e., what tensile, tear and puncture strength ratings are required?);</li>
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<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>
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<li>Texture (i.e., grain size distribution) of the overlying fill material; and</li>
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<li>Permeability of the native soil</li>
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<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>
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</ol>
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<table class="table table-bordered">
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Geotextiles can be used to prevent downward migration of smaller particles in to larger aggregates, and slump of heavier particles into finer underlying courses. Geotextiles are commonly used on low strength soils (CBR<4).
<caption><strong>Recommended criteria for selection of geotextile fabric</strong></caption>  
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The formation of biofilm on geotextiles has also been shown to improve water quality:
<tr class="success"><th>Percent media passing 0.075 mm (#200 sieve)</th><th>Non-woven fabric apparent opening size (AOS, mm)</th><th>Woven fabric percent open area (POA, %)</th><th>Permittivity (sec<sup>-1</sup>)</th></tr>
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*By degrading petroleum hydrocarbons<ref>Newman AP, Coupe SJ, Spicer GE, Lynch D, Robinson K. MAINTENANCE OF OIL-DEGRADING PERMEABLE PAVEMENTS: MICROBES, NUTRIENTS AND LONG-TERM WATER QUALITY PROVISION. https://www.icpi.org/sites/default/files/techpapers/1309.pdf. Accessed July 17, 2017.</ref>
  <tr><td align="center" valign="middle">>85</td><td align="center" valign="middle" rowspan = 2>≤ 0.3</td><td align="center" valign="middle">Not recommended</td><td align="center" valign="middle" rowspan = 2>0.1</td></tr>
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*By reducing organic pollutant and nutrient concentrations <ref>Paul P, Tota-Maharaj K. Laboratory Studies on Granular Filters and Their Relationship to Geotextiles for Stormwater Pollutant Reduction. Water. 2015;7(4):1595-1609. doi:10.3390/w7041595.</ref>
  <tr><td align="center" valign="middle">50 - 85</td><td align="center" valign="middle" rowspan = 3>≥ 4</td></tr>
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*When installing geotextiles an overlap of 150 - 300 mm should be used.
  <tr><td align="center" valign="middle">15 - 50</td><td align="center" valign="middle" rowspan = 3>≤ 0.6</td><td align="center" valign="middle">0.2</td></tr>
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Material specifications should conform to OPSS 1860 for Class II geotextile fabrics
  <tr><td align="center" valign="middle">5 - 15</td><td align="center" valign="middle" rowspan =2>0.5</td></tr>
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<ref>ONTARIO PROVINCIAL STANDARD SPECIFICATION METRIC OPSS 1860 MATERIAL SPECIFICATION FOR GEOTEXTILES. 2012. http://www.raqsb.mto.gov.on.ca/techpubs/OPS.nsf/0/2ccb9847eb6c56738525808200628de1/$FILE/OPSS%201860%20Apr12.pdf. Accessed July 17, 2017</ref>. Note when expansive clays are present, a non-infiltrating design may be necessary.  If used, geotextile socks around perforated pipes should conform to ASTM D6707 with minimum water flow rate conforming to ASTM D4491 (12,263 L/min/m<sup>2</sup> at 5 cm head). 
  <tr><td align="center" valign="middle">≤ 5</td><td align="center" valign="middle">≥ 10</td></tr>
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*Fabrics should be woven monofilament or non-woven needle punched.
  </table>
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*Woven slit film and non-woven heat bonded fabrics should not be used, as they are prone to clogging.
</p>
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In choosing a product, consider:
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#The maximum forces that will be exerted on the fabric (i.e., what tensile, tear and puncture strength ratings are required?),
 +
#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?),
 +
#The texture (i.e., grain size distribution) of the overlying and underlying materials, and
 +
#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.
 +
 
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{|class="wikitable"
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|-
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|+Recommended criteria for selection of geotextile fabric
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|-
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!Percent soil/filter media passing 0.075 mm (#200 sieve)
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!Non-woven fabric apparent opening size (AOS, mm)
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!Woven fabric percent open area (POA, %)
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!Permittivity (sec<sup>-1</sup>)
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|-
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|>85||≤ 0.3||-||0.1
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|-
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|50 - 85||≤ 0.3||≥ 4||0.1
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|-
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|15 - 50||≤ 0.6||≥ 4||0.2
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|-
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|5 - 15||≤ 0.6||≥ 4||0.5
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|-
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|≤ 5||≤ 0.6||≥ 10||0.5
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|}
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===Performance research===
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http://www.mdpi.com/2073-4441/7/4/1595/htm
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----
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[[category:materials]]

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