Search Results (23)

Phosphorus is a ubiquitous contaminant in urban and agricultural landscapes. A retention basin located in the southern part of Barnegat Bay, New Jersey, was identified as receiving stormwater runoff with elevated phosphorus concentrations. The basin is surrounded by expanding urban development, contributing to the progressive degradation of water quality in the bay, which is already highly eutrophic. This study evaluated the effectiveness of a culvert retrofit with a green filter media composed of granulated-aluminum-based drinking water-treatment residuals (Al-WTR) and granular carbon (5:1 ratio, w/w) for the removal of phosphorus and suspended sediments from stormwater runoff. The performance of the filter media was assessed through water quality monitoring following runoff events over a 12-month period. The results indicated that the green filter media achieved up to 52% removal of total phosphorus from stormwater influent. However, treatment efficiency declined after approximately five months due to clogging of the geotextile bag housing the media. The replacement of the geotextile bag restored phosphorus removal performance (59%), highlighting the importance of routine maintenance. The findings demonstrate a cost-effective, environmentally sustainable, and innovative green engineering approach for mitigating phosphorus contamination in urban stormwater. Full article

In the treatment of soda-residue-stabilized soil with high water content using drainage boards with vacuum preloading, the boards often prone to clogging and bending under lateral pressure, reducing their hydraulic conductivity and affecting the soil reinforcement. In this study, the structure of the standard plastic drainage board (filter membrane + filter core) was improved, and three types of new anti-clogging plastic drainage boards with different structures were developed (Type X: geotextile + filter core, Type Y: geotextile + wire mesh + filter core, Type Z: geotextile + filter membrane + filter core). Permeability tests were subsequently used to determine the optimal structure. In-lab vertical draining tests with vacuum preloading were carried out on the selected model to study the change in water content, vacuum pressure, surface settlement, vane shear strength, and pore water pressure of soil with drainage board insertion depth, providing a reference for the application of new anti-clogging drainage boards in engineering. The results showed that: (1) the type Y anti-clogging plastic drainage board (geotextile + wire mesh + filter core) exhibits the most balanced performance in terms of permeability, anti-clogging ability, tensile strength and bending strength and is suitable for vacuum preloading of soda residue with high water content; (2) the mechanical properties and anti-clogging performance of drainage boards are highly dependent on their structural configuration. Introducing a wire mesh between the filter core and the geotextile significantly enhances the tensile and bending strength of the drainage board without noticeably compromising its drainage performance; (3) the insertion depth of the drainage board significantly affects drainage efficiency, vacuum transmission rate, and strength development of the soda residue. The effective reinforcement range of the drainage board is not limited to the insertion depth but also extends below the bottom of the drainage board. Full article

In response to the dual challenges of the mechanical behavior of steel sheet pile cofferdam and sediment control in urban water intake projects, a multi-method integrated study was conducted based on the Nenjiang Project. The results show that the peak stress of FSP-IV steel sheet piles (64.3 MPa) is located at a depth of 5.5–8.0 m in the center of the foundation pit, and that the maximum horizontal displacement (6.96 mm) occurs at the middle of the side span of the F pile. The internal support stress increases with depth, reaching 87.2 MPa at the bottom, with significant stress concentration at the connection of the surrounding girder. The lack of support or excessively large spacing leads to insufficient stiffness at the side span (5.3 mm displacement at the F point) and right-angle area (B/H point). The simultaneously developed sediment control integrated system, through double-line water intake, layered placement of the geotextile filter, and the collaborative construction of the water intake hole–filter layer system, achieves a 75% reduction in sediment content and a decrease in standard deviation. This approach ensures stable water quality and continuous water supply, ultimately forming a systematic solution for water intake in high-sediment rivers. Full article

Green roofs are increasingly being adopted as sustainable, nature-based solutions for managing urban stormwater, mitigating the urban heat island effect, and saving energy in buildings. However, the long-term performance of their individual components—particularly filter geotextiles—remains understudied, despite their critical role in maintaining system functionality. The filter layer, responsible for preventing clogging of the drainage layer with fine substrate particles, directly affects the hydrological performance and service life of green roofs. While most existing studies focus on the initial material properties, there is a clear gap in understanding how geotextile filters behave after prolonged exposure to real-world environmental conditions. This study addresses this gap by assessing the mechanical and structural integrity of geotextile filters after five years of use in both extensive and intensive green roof systems. By analyzing changes in surface morphology, microstructure, and porosity through tensile strength tests, digital imaging, and scanning electron microscopy, this research offers new insights into the long-term performance of geotextiles. Results showed significant retention of tensile strength, particularly in the machine direction (MD), and a 56% reduction in porosity, which may affect filtration efficiency. Although material degradation occurs, some geotextiles retain their structural integrity over time, highlighting their potential for long-term use in green infrastructure applications. This research emphasizes the importance of material selection, long-term monitoring, and standardized evaluation techniques to ensure the ecological and functional resilience of green roofs. Furthermore, the findings contribute to advancing knowledge on the durability and life-cycle performance of filter materials, promoting sustainability and longevity in urban green infrastructure. Full article

The application of geotextiles as filter materials in various systems, such as biofilters, wetlands, and wastewater treatment plants, has grown significantly in recent years. The ability of these materials to support biofilm growth makes them ideal for the removal of organic and inorganic contaminants present in wastewater. The objective of this research was to analyze clogging through variations in permeability, using column tests for 80 days with two types of nonwoven geotextiles with different grammages (GT120 and GT300), as well as to study the efficiency in the removal of organic matter. A synthetic wastewater was used, allowing the specific observation of biological clogging and the treatment carried out exclusively by microorganisms. The results indicated that bioclogging was not a significant factor within the experimental period. Through the mass test, a continuous increase in biofilm growth over time was observed for both geotextiles. For scanning electron microscopic (SEM) images, GT300 presented a larger biofilm area. A higher removal of COD (80%), N (52%), and P (36%) by microorganisms present in GT300 was found, which appears to be associated with its greater thickness and weight. The higher mesh density provides a larger area for the growth of microorganisms, allowing a greater amount of biomass to establish itself and contributing to the efficient removal of pollutants. These findings highlight the potential of using geotextile filters in wastewater treatment applications, where biofilm growth can positively contribute to contaminant removal without immediately compromising permeability. Full article

Among the various types of polymeric materials, geosynthetics deserve special attention. A geosynthetic is a product made from synthetic polymers that is embedded in soils for various purposes. There are some basic functions of geosynthetics, namely, erosion control, filtration, drainage, separation, reinforcement, containment, barrier, and protection. Geosynthetics for erosion control are very effective in preventing or limiting soil loss by water erosion on slopes or river/channel banks. Where the current line runs through the undercut area of the slope, the curvature of the arch is increased. If this phenomenon is undesirable, the meander arch should be protected from erosion processes. The combination of geosynthetics provides the best resistance to erosion. In addition to external erosion, internal erosion of soils is also a negative phenomenon. Internal erosion refers to any process by which soil particles are eroded from within or beneath a water-retaining structure. Geosynthetics, particularly geotextiles, are used to prevent internal erosion of soils in contact with the filters. Therefore, the main objective of this review paper is to address the many ways in which geosynthetics are used for erosion control (internal and external). Many examples of hydrotechnical and civil engineering applications of geosynthetics will be presented. Full article

In recent decades, there have been individual cases of damage to the revetments of the German North Sea estuaries due to clogging by precipitated ochre products. This process is defined as ochre clogging and has been extensively explained in the literature. The primary aim of the investigations was to better understand the clogging process under in situ conditions and the causative environmental conditions surrounding the filters. Extensive in situ investigations were therefore carried out. It was found that a permeability reduction in geotextile filters can be strongly accelerated by ochre clogging, which appears to be a biogeochemical process. This describes a combined action of the chemical precipitation of iron and manganese, precipitation by microorganisms, and physical clogging. A further aim of this study was to establish limit values for the decisive ochre clogging parameters, which could be used to quantify the susceptibility to ochre clogging. It was shown that the determination of the iron and manganese content of the groundwater, as well as the redox capacity of the groundwater, is sufficient to assess the tendency for ochre clogging. To minimise the negative impact on filter performance, recommendations for an adapted filter design have been developed as a guide for planners. Full article

Subsurface pipes covered with geotextiles and filters are essential for preventing clogging and ensuring efficient drainage. To address low salt discharge efficiency due to subsurface drainage pipes (SDPs) clogging easily, sand gravel, straw, and combined sand gravel–straw were set above SDPs, respectively, within a setting of uniform geotextiles. The influences of different filter materials on the drainage efficiency and salt discharge effect of the SDPs, as well as the effects of different filter materials on the salt drainage efficiency and anti-siltation effect of the SDPs were studied by performing simulation experiments in a laboratory. The results confirmed the following: (1) The salt removal rates of the SDPs externally wrapped with materials exceeded 95%. The subsurface pipe treated with the sand gravel filter material had the highest desalting rate (93.69%) and soil profiles with total salt contents that were 17.7% and 20.5% lower than those treated with the straw and combined sand gravel–straw materials, respectively. (2) The soil salinity of the sand gravel filter material around the SDPs was between 1.57 and 3.6 g/kg, and the drainage rate (R) was 0.97, so its salt-leaching effect was the best. (3) The sand gravel filter material increased the characteristic particle size of the soil above the SDP by 8.4%. It could effectively intercept coarse particles, release fine particles, and facilitate the formation of a highly permeable soil skeleton consisting of coarse particles, such as sand particles surrounding the soil. (4) The use of the straw filter material produced dense filter cake layers on the upstream surfaces of the geotextiles. When the sand gravel and combined sand gravel–straw filter materials were used, soil particles remained in the geotextile fiber structure, and a large number of pores were still retained. Therefore, the sand gravel filter material was the most suitable for the treatment of Yinbei saline–alkali soil in Ningxia Hui Autonomous Region. Full article

Subsurface drainage pipes covered with filters and geotextiles are the key to preventing clogging and ensuring efficient drainage. To improve the salt discharge efficiency of these subsurface drainage pipes, different layers of geotextiles were set outside the pipes with the aid of uniform gravel filters. This paper reports our findings from laboratory simulation of subsurface drainage pipes and experiments. The study examined the influence of different layers of geotextiles on the drainage efficiency, salt discharge effects of subsurface drainage pipes, and the effect of superimposed geotextiles on the salt drainage efficiency as well as the anti-clogging effect of subsurface drainage pipes. The results are as follows: (1) The geotextile and filter material wrapped around the subsurface pipe facilitated the movement of water towards the subsurface pipe, which could promote the salt discharge of the subsurface pipe. However, in the single leaching experiment, the reduction in soil pH was not significant for different scenarios. (2) The salt removal rate of the geotextile-wrapped subsurface pipes was more than 95%. The salt removal rate of the double-layer geotextile scenario was the highest (96.7%), and the total salt content of soil profiles was 8.3% and 31.3% lower than those of the single-layer and triple-layer geotextile scenarios, respectively. The drainage efficiency of the double-layer geotextile scenario was the highest, and the salt distribution in the 0–60 cm profile was relatively uniform, ranging from 2.3 to 3.0 g∙kg⁻¹. (3) The clogging in the triple-layer geotextile scenario was caused by the geotextile, i.e., a dense filter cake layer formed on the surface of the geotextile. The clogging in the single-layer and double-layer geotextile scenarios was the clogging of the geotextile itself, i.e., soil particles retained in the fiber structure of geotextiles. (4) In the case of the single-layer and double-layer geotextile scenarios, the soil particles failed to completely clog the selected geotextiles, and there were still a large number of pores retained. The double-layer geotextiles integrate filtration, clogging prevention, and drainage promotion to provide the best salt drainage with the subsurface pipe. This study reveals the influence of the filter on soil water salt and salt discharge and provides a theoretical explanation and technical justification for the application of the subsurface pipes salt discharge technology in saline soil ameliorate. Full article

This research aims to assess the clogging process of geotextiles within silt fences. For that purpose, the filtering efficiency, flow rate, and clogging of three geotextiles (GTX-1, GTX-2, and GTX-3) employing two distinct soils and under three sediment discharge cycles were investigated. The analysis adhered to the American standard D5141-11 and, as further analyses, qualitative and quantitative inspections were conducted through microscopic images of the materials. The results showed greater clogging of the nonwoven geotextile, GTX-1, with higher retention efficiency (approximately 100%) and better turbidity removal for both soils, equal to a reduction of around 94%. For GTX-2, a woven geotextile with a larger pore opening, less intense clogging and lower retention efficiency were observed after the third discharge; the average was 96% for both soils. GTX-3, a woven geotextile with a smaller apparent opening, exhibited a behavior similar to GTX-1: as the number of cycles increased, the material experienced more clogging and higher retention efficiency for soil 1 (approximately 98.5%). Based on these findings, it can be inferred that the discharge cycles impact the tested geotextiles in diverse ways and, therefore, the selection of the material should be contingent on project requirements. Full article

Geotextile tubes have offered a cost-effective and convenient solution for the treatment of dredged slurry in recent years. Despite their benefits, the dewatering process of this method remains cumbersome and time-consuming. The incorporation of flocculants into dredged slurries has been shown to mitigate the clogging of geotextile tubes, thereby enhancing the efficiency of the dewatering process. To quantify the impact of flocculant addition on the dewatering performance, a series of laboratory tests were conducted to investigate the sedimentation behavior of flocculant-treated river-dredged slurries under filtration of woven geotextiles. The impact of different flocculants is evaluated with the sedimentation rates of dredged slurries, specifically nonionic polyacrylamide (NPAM) and cationic polyacrylamide (CPAM). Results demonstrated that both NPAM and CPAM, at an optimal concentration of around 250 mg/L, could substantially increase the settling rates of slurries when filtered through geotextiles. At equivalent flocculant concentration, NPAM outperforms CPAM in accelerating sedimentation rates. It is also evidenced that adding flocculants can significantly augment the particle size and permeability of slurries. After adding flocculants, the water content and dry density of the final sediments exhibit a more uniform distribution in the vertical direction compared to the original slurry. Furthermore, scanning electron microscopy was employed to analyze the micromorphology of the final sediments treated with different NPAM concentrations. The results showed that the slurries exhibited significant void structure under treatment with the optimal concentration of NPAM, demonstrating the flocculants’ effectiveness in enhancing the dewatering process of river-dredged slurries when filtered with geotextiles. Full article

Geosynthetic materials (i.e., geogrids, geotextiles and other geocomposites) act as an interlayer system and are widely used in construction applications. In pavement structures, geosynthetic layers provide potential benefits such as reinforcement, reflective cracking mitigation, increased fatigue life, and improved drainage and filtering. However, few studies have addressed the installation and construction practices of geosynthetics in pavements. Furthermore, the study of geosynthetics and their contribution during construction are limited. In this paper, a full-scale field study was conducted and three trial sections were constructed; two types of geosynthetics, a fibreglass geogrid and a geogrid composite, were installed in the asphalt binder course and at the interface between the subgrade and base layer, respectively, to be compared with a control section without geosynthetic reinforcement. Trial sections were instrumented to monitor the pressure applied on the subgrade, the strain in the base lift of the asphalt binder course, the temperature, and the moisture within the pavement structure during construction. In addition, post-construction field testing was performed to measure the stiffness of the pavements after construction. The results indicated that geosynthetic-reinforced pavements can maintain pavement resilience during construction and significantly mitigate the disturbances caused by construction activities. The geogrid embedded in the asphalt layer was demonstrated to reduce the pressure at the subgrade caused by paving equipment by 70% compared with the control section, while simultaneously reducing the longitudinal and transverse strain at the bottom of the asphalt layer by 54% and 99%. Observations from the geogrid composite test section also demonstrate the potential to minimize the impacts of future freeze–thaw at the subgrade due to the improved drainage and indirect insulation effect. Full article

Geosynthetics have been commonly used for the construction of civil engineering structures such as retaining wall, road and railways, coastal protection, soft ground improvement work, and landfill systems since the 1960s. In the past 40 years, the development of polymer materials has helped to prolong the life of geosynthetics. In terms of the practical use of geosynthetics, engineers must understand their appropriate application. The first part of this paper provides a basic description of geosynthetics, including their types, components, and functions. The second part deals with the geosynthetics used as filters. This part briefly presents the mechanism of filtration, the factors affecting the durability of geotextile filters, design concepts, laboratory tests, and case studies. The third part of the study covers the use of geosynthetics for stabilisation. Its mechanism was explained separately for geogrids and for geocells. Several examples of applications with geosynthetics intended for the stabilisation function are described in the last part of this paper. Full article

To avoid serious clogging and loss of drainage capacity, which puts the underground structure at risk of anti-floating failure, the buried drainage filter must be equipped with a nonwoven geotextile layer. In this scenario, nonwoven geotextiles are subjected to normal compressive stress, which can cause changes in geotextile porosity and structure, affecting the filtration behavior of the geotextile filter. In this paper, in order to evaluate the filtration compatibility of the soil–geotextile system, gradient ratio (GR) tests were performed under a hydraulic gradient of 1.0 using a specially designed gradient ratio filtration device capable of applying normal stress. In total four nonwoven geotextiles and two types of soil were used. The results of the gradient ratio filtration tests were discussed in terms of GR values, the permeability of the soil–geotextile system, and the amount of fines retained in geotextiles. It was shown that under a larger normal compressive stress, the GR value would also increase, while the permeability coefficient of the soil–geotextile system decreased. The filtration responses to various soil–geotextile combinations differed under normal compressive stress. A thick nonwoven geotextile with a small filtration opening size exhibited poor filtration performance while benefiting soil retention. Fines retention was influenced by geotextile thickness, soil type, and normal compressive stress magnitude. In addition, for nonwoven geotextiles filter fine-grained soil under normal compressive stress, the test results indicated that anticlogging design criteria should be improved. Full article

The recent trend in coastal research centers around environmental sustainability, especially in coastal conservation. A seawall typically has three layers, namely core, filter, and hard rubble/concrete armor. In the current study, a two-layered seawall is proposed, comprising a coir geotextile roll from the coastal regions, along with sand encapsulated in a geotextile over an impermeable core. This can be considered as a quasi-soft solution against the traditional, three-layered, hard alternative. The objective of this study is to investigate the combined effect of slope and porosity, of this composite structure, on the wave reflection. The findings show that the composite structure provides less reflection coefficient values compared to traditional rubble mound seawalls. Four orientations and positions of coir rolls with geosynthetic sandbag were tested. The armor layer with coir rolls overlain by geosynthetic sandbags over an impermeable core could be a better alternative, as it increases the hydrodynamic performance by 59% as compared to sandbags, used alone, over an impermeable core on a slope of 1:2. Full article