Difference between revisions of "Clogging"

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[[File:Clogged drain.jpg|thumb|Drain clogged by 9 squares of 32 = 28 %]]
[[File:Clogged drain.jpg|thumb|Street drain clearly clogged by 9 squares of 32 = 28 %]]
==Grates and orifices==
==Grates and orifices==
Debris in stormwater is often deposited in the narrowest parts of our low impact development systems. Garbage, leaf litter and sediment all contribute towards the clogging of these structures.  
Debris in stormwater is often deposited in the narrowest parts of our low impact development systems. Garbage, leaf litter and sediment all contribute towards the clogging of these structures.  

Revision as of 19:58, 19 October 2018

Street drain clearly clogged by 9 squares of 32 = 28 %

Grates and orifices[edit]

Debris in stormwater is often deposited in the narrowest parts of our low impact development systems. Garbage, leaf litter and sediment all contribute towards the clogging of these structures. It is often prudent to assume that maintenance will be intermittent and to include a clogging factor into engineering calculations to account for periods in which the debris has not been removed.

A suggested value of 0.5 is often adopted. This is equivalent to 50 % of the cross-section of the structure being clogged during the flow being calculated.

Geotextiles/filter fabric[edit]

  • 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 [1].
  • Elsewhere the mechanisms behind the clogging have been studied and characterised using CT-scanning technology [2].

Due to concerns about clogging, many types of facility may be constructed with limited or no filter fabric within:

  • The use of filter fabric is referred to as a practice in 'older bioretention designs' In the upstate forever LID guide[3]. They go on to suggest that a choker course by used instead to separate the filter media and reservoir aggregate. Filter fabric may be used in side walls and should be placed directly over and within 2 feet of the perforated pipe drains when used in an underdrain.
  • 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[4].


[5] [6] [7] [8] [9]

Filter media[edit]

Salty water has been shown to cause degradation of the filter media, and subsequent loss of the initial text and flow conditions [10]

  1. ↑ 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. [1]
  2. ↑ Miszkowska, A., S. Lenart, and E. Koda. 2017. Changes of Permeability of Nonwoven Geotextiles due to Clogging and Cyclic Water Flow in Laboratory Conditions. Water 9(660). doi:10.3390/w9090660.
  3. ↑ Upstate Forever. 2005. “Bioretention - LID Fact Sheet.” Greenville, South Carolina. https://www.upstateforever.org/files/files/CAW_LIDFact_Bioretention.pdf.
  4. ↑ Tahvonen, O. 2018. Adapting Bioretention Construction Details to Local Practices in Finland. Sustainability 10(276). doi: doi:10.3390/su10020276.
  5. ↑ 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..
  6. ↑ 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.
  7. ↑ 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).
  8. ↑ Massachusetts Department of Environmental Protection. . “Bioretention Areas.” 1999. http://prj.geosyntec.com/npsmanual/bioretentionareas.aspx.
  9. ↑ Massachusetts Department of Environmental Protection. 2014. “Bioretention Areas & Rain Gardens.” 2014. http://prj.geosyntec.com/npsmanual/bioretentionareasandraingardens.aspx.
  10. ↑ 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. [2]

A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

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.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Low Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

The engineered soil component of bioretention cell or dry swale designs, typically with a high rate of infiltration and designed to retain contaminants through filtration and adsorption to particles.

The engineered soil component of bioretention cell or dry swale designs, typically with a high rate of infiltration and designed to retain contaminants through filtration and adsorption to particles.

The technique of removing pollutants from runoff as it infiltrates through the soil.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

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