Geotextile filter design

Geotextile filter design parallels sand filter design with some modifications. The three elements of adequate flow, soil retention, and clogging prevention remain the same. 

The second part of the geotextile filter design is determining the opening size necessary for retaining the upstream soil or particulates in the leachate. It is well established that the 95% opening size is related to the particles to be retained in the following type of relationship. 

Heibaum, M., 2014. Rethinking geotextile filter design. Proc. 10th International Conference on Geosynthetics (lOICG), September 21—25, 2014, Berlin, Germany. Paper 142, 8 p. 

Luettich, S.M., Giroud, J.P., Bachus, R.C., 1992. Geotextile filter design guide. Geotextiles and Geomembranes 11, 355—370. 

When a geotextile filter is to be used for environmental applications, it becomes necessary to design the filter with resistance to biological clogging. Biological clogging, initiates with the development of a network of... 

The filtration opening size and PSD are important in the design retention criterion that refers to geotextile filter capacity to retain the fine particles of base soil. It is commonly expressed as (Eq. [8.5]) ... 

The permeability criterion of the filter system refers to the capacity of the geotextile filter to guarantee free liquid flow across the filter s plane. For this function, geotextile cross-plane permeability or permittivity is necessary for the design, and sometimes also thickness and porosity. 

For internally stable, well-graded granular soils, the results so far obtained using a theoretical method (Moraci et al., 2012c) have shown the importance of an upper limit value for the design of a geotextile filter. 

Cazzuffi, D., lelo, D., Mandaglio, M.C., Moraci, N., 2015. Recent developments in the design of geotextile filters. In Keynote Lecture in the 2nd International GSI-Asia Geosynthetics Conference (GSI-Asia 2015), Seoul, Korea (Rep.), June 24—26, 2015. 

Moraci, N., Mandagho, M.C., Cazzuffi, D., 2010. The geotextile filters in contact with granular soils design criteria and parameters. Rivista Italiana di Geotecnica — Italian Geotechnical Journal 2/2010 45—69 (in Italian). 

RFpc is related to the quality of the filter geotextile and can be assumed to be minimal as long as the adjacent fill or soil next to the geotextile filter meets filtration design criteria. StUl, upstream soil particles may embed themselves in a thick filter geotextUe and block flow above the geotextUe s voids. 

Koemer, G.R., Koemer, R.M., Martin, J.P., 1994. Geotextile filters used for leachate collection systems testing, design and field behavior. Journal of Geotechnical Engineering Division, ASCE 120 (10), 1792-1803. 

Figure 12.1 Design chart for geotextile filters, di, indicative diameter of the base soil fep, coefficient of permeability of the geotextile filter ks, coefficient of permeability of base soil risk of piping of finer particles.

Laboratory test results have shown that geotextiles can be successfully employed as filters in most simations, even in some cases when available design criteria would not recommend their use. This highlights the need for more realistic filter design criteria where filters in service conditions are more accurately simulated. On the other hand, some experimental techniques also have to be improved and complementary tests may be needed if the range of application of geotextile filters is to be expanded, or... 

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