Changes

==Geotextiles/filter fabric==

==Geotextiles/filter fabric==

*Clogging of filter fabric has been observed in many field studies, e.g. ''"outflow ceases while water is still ponded above the drainage layer is most likely due to fines clogging the fabric and the need for more hydraulic head for the water to pass through the fabric"''<ref>Willard, L.L., T. Wynn-Thompson, L. H. Krometis, T. P. \ Badgley, and B. D. Neher. 2017. “Does It Pay to Be Mature? Evaluation of Bioretention Cell Performance Seven Years Postconstruction.” Journal of Environmental Engineering 143 (9).</ref>

*Clogging of [[filter fabric]] has been observed in many field studies, e.g. ''"outflow ceases while water is still ponded above the drainage layer is most likely due to fines clogging the fabric and the need for more hydraulic head for the water to pass through the fabric"''<ref>Willard, L.L., T. Wynn-Thompson, L. H. Krometis, T. P. \ Badgley, and B. D. Neher. 2017. “Does It Pay to Be Mature? Evaluation of Bioretention Cell Performance Seven Years Postconstruction.” Journal of Environmental Engineering 143 (9).</ref>

*Laboratory research has demonstrated that the performance and clogging of maturing filter fabric can be predicted mathematically, based upon the media/filter material particle size distribution <ref>Palmeira, E. M. and Trejos Galvis, H. L. (2016). Opening sizes and filtration behaviour of non-woven geotextiles under confined and partial clogging conditions. Geosynthetics International. [http://dx.doi.org/10.1680/jgein.16.00021]</ref>.  

*Laboratory research has demonstrated that the performance and clogging of maturing filter fabric can be predicted mathematically, based upon the media/filter material particle size distribution <ref>Palmeira, E. M. and Trejos Galvis, H. L. (2016). Opening sizes and filtration behaviour of non-woven geotextiles under confined and partial clogging conditions. Geosynthetics International. [http://dx.doi.org/10.1680/jgein.16.00021]</ref>.  

*Again, in Australia geotextile is only recommended around the sides of the practice :''"Geotextile fabrics are not recommended for use between layers in bioretention systems due to the risk of clogging."'', and :''"Conventional bioretention systems have... ...a permeable geotextile liner around their sides (no liner along the base)"'' <ref>Water by Design. 2014. Bioretention Technical Design Guidelines (Version 1.1). http://hlw.org.au/u/lib/mob/20150715140823_de4e60ebc5526e263/wbd_2014_bioretentiontdg_mq_online.pdf.</ref>. This practice is also seen in Massachusetts bioretention design documentation<ref>Massachusetts Department of Environmental Protection. . “Bioretention Areas.” 1999. http://prj.geosyntec.com/npsmanual/bioretentionareas.aspx.</ref>, indeed the side walls geotextile is also said to be ''"(optional)"''<ref>Massachusetts Department of Environmental Protection. 2014. “Bioretention Areas & Rain Gardens.” 2014. http://prj.geosyntec.com/npsmanual/bioretentionareasandraingardens.aspx.</ref>.

*Again, in Australia geotextile is only recommended around the sides of the practice :''"Geotextile fabrics are not recommended for use between layers in bioretention systems due to the risk of clogging."'', and :''"Conventional bioretention systems have... ...a permeable geotextile liner around their sides (no liner along the base)"'' <ref>Water by Design. 2014. Bioretention Technical Design Guidelines (Version 1.1). http://hlw.org.au/u/lib/mob/20150715140823_de4e60ebc5526e263/wbd_2014_bioretentiontdg_mq_online.pdf.</ref>. This practice is also seen in Massachusetts bioretention design documentation<ref>Massachusetts Department of Environmental Protection. . “Bioretention Areas.” 1999. http://prj.geosyntec.com/npsmanual/bioretentionareas.aspx.</ref>, indeed the side walls geotextile is also said to be ''"(optional)"''<ref>Massachusetts Department of Environmental Protection. 2014. “Bioretention Areas & Rain Gardens.” 2014. http://prj.geosyntec.com/npsmanual/bioretentionareasandraingardens.aspx.</ref>.

*In Finland the use of a choker course has been advocated for in place of filter fabric as replacing a clogged fabric layer would disturb established [[planting]]<ref>Tahvonen, O. 2018. Adapting Bioretention Construction Details to Local Practices in Finland. Sustainability 10(276). doi: doi:10.3390/su10020276.</ref>.  

*In Finland the use of a [[choker course]] has been advocated for in place of filter fabric as replacing a clogged fabric layer would disturb established [[planting]]<ref>Tahvonen, O. 2018. Adapting Bioretention Construction Details to Local Practices in Finland. Sustainability 10(276). doi: doi:10.3390/su10020276.</ref>.  

*However, a recently revised document in Oklahoma suggests that geotextiles have a place in the base of the reservoir, but a choker course is best employed between layers inside the practice<ref>McLemore, A.J., J.R. Vogel, and S. Taghvaeian. 2017. “Bioretention Cell Design Guidance for Oklahoma.” http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-10743/BAE-1536web.pdf.</ref>

*However, a recently revised document in Oklahoma suggests that geotextiles have a place in the base of the reservoir, but a choker course is best employed between layers inside the practice<ref>McLemore, A.J., J.R. Vogel, and S. Taghvaeian. 2017. “Bioretention Cell Design Guidance for Oklahoma.” http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-10743/BAE-1536web.pdf.</ref>

*Filter fabric certainly has application in supporting backfield of native soils over [[infiltration trenches|infiltration]] and [[exfiltration trenches]] which comprise crates or [[clear stone]]<ref>Stormwater Management for Smart Growth, Allen P. Davis, Richard H. McCuen, Springer Science & Business Media, Aug. 16, 2005</ref>.

*Filter fabric certainly has application in supporting backfield of native soils over [[infiltration trenches|infiltration]] and [[exfiltration trenches]] which comprise crates or [[clear stone]]<ref>Stormwater Management for Smart Growth, Allen P. Davis, Richard H. McCuen, Springer Science & Business Media, Aug. 16, 2005</ref>.

==Pipes==

==Pipes==

Some clogging of perforated pipes is likely to occur between maintenance visits. As mentioned above a clogging factor of 0.5 is often applied. See [[Flow through perforated pipe]].  

Some clogging of perforated [[pipes]] is likely to occur between maintenance visits. As mentioned above a clogging factor of 0.5 is often applied. See [[Flow through perforated pipe]].  

Various opinions are offered about how to mitigate the accumulation of sediment. The appropriate solution may depend on whether the water is flowing into the pipe (see [[underdrains]]), or out of the pipe as in [[exfiltration trenches]].

Various opinions are offered about how to mitigate the accumulation of sediment. The appropriate solution may depend on whether the water is flowing into the pipe (see [[underdrains]]), or out of the pipe as in [[exfiltration trenches]].

==Filter media==

==Filter media==

Salty water has been shown to cause degradation of the filter media, and subsequent loss of the initial texture and flow conditions <ref>Kakuturu, S.P., and S.E. Clark. 2015. Clogging Mechanism of Stormwater Filter Media by NaCl as a Deicing Salt. doi: 10.1089/ees.2014.0337. [https://static1.squarespace.com/static/55c211c8e4b06ea5799e6c03/t/5605b199e4b08dbc6e74a369/1443213721385/Clogging+mechanism+of+stormwater+filter+media.pdf]</ref>

Salty water has been shown to cause degradation of [[bioretention]] [[filter media]], and subsequent loss of the initial texture and flow conditions <ref>Kakuturu, S.P., and S.E. Clark. 2015. Clogging Mechanism of Stormwater Filter Media by NaCl as a Deicing Salt. doi: 10.1089/ees.2014.0337. [https://static1.squarespace.com/static/55c211c8e4b06ea5799e6c03/t/5605b199e4b08dbc6e74a369/1443213721385/Clogging+mechanism+of+stormwater+filter+media.pdf]</ref>

 

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