Conference Agenda

<p>Geotextile tubes are a technology used in different sectors such as water supply and sanitation, mainly in the final stage, to dewater the sludge generated in wastewater and water treatment plants. This paper presents geotextile tubes at the beginning of the water supply system (i.e. catchment). This paper shows a large-scale remediation project that used geotextile tube dewatering technology to desand the stream where part of the water catchment of São Carlos city – (São Paulo, Brazil) is carried out. The geotextile tube used was a full-scale manufactured with woven polypropylene geotextile. This paper aims to present the hydraulic performance of the system and the degradation of the geotextile tube during the life service. Complete monitoring of the retention and dewatering capacity of the system was carried out, as well as the effluent quality throughout the operation. Granulometric distribution at different heights of the filter cake is presented to better understand the deposition of particles inside the geotextile tube during the dewatering process. Changes were observed in the geotextile's tensile strength and permittivity properties after application, and this allowed calculating reduction factors referring to the durability of the geotextile tube.</p>

<p><strong>ABSTRACT</strong>: Due to a lack of granular fill materials, soft clay slurry dredged from seabed may have to be used for land reclamation. In this paper, a new product, the horizontal drain enhanced non-woven geotextile sheet (HDeGs), and a method to use HDeGs as horizontal drains for consolidation of soft marine clay using vacuum pressure is introduced. The construction procedure for the use of HDeGs and the vacuum preloading for consolidation of slurry clay for land reclamation is discussed. Model tests have been conducted and the results have demonstrated the effectiveness of the proposed method. The advantages of using HDeGs over the other methods are elaborated. The potential of using this method for land reclamation projects is also discussed.</p>

The consolidation of marine deposits for marine infrastructure, dredged mud disposal, as well as new reclamation, is a time-consuming process due to the low permeability of the soft marine clay. In vacuum preloading, the discharge efficiency of prefabricated vertical drains (PVD) significantly decreases with bending and clogging as soils consolidate. Ele-vating the temperature in soils in an appropriate way is an important method for increasing the efficiency of vacuum consolidation. In this study, a physical model test was carried out with a heating aided PVD installed in the Hong Kong marine deposit (HKMD) slurry. A stepwise heating scheme was implemented to investigate the effects of heating on the discharge behaviour of vacuum preloading. The temperature distribution and evolution in the model, the water discharge volume of the slurry, and the response of water discharge rate to temperature change at different stage of consolidation are analyzed and discussed.

<p>On request of Finnish Transport Infrastructure Agency (Finland), Norwegian Public Roads Administration (Norway) and Swedish Transport Administration (Sweden), Sintef (Norway) has prepared guidelines on the use of geosynthetics in Nordic conditions. The ROUGH project (RecOmmendations for the Use of GeosyntHetics in Nordic conditions) has been realised together with several manufacturers of geosynthetics. The paper focuses on the behaviour of drainage geosynthetics during installation in Nordic conditions. The test conditions included prior storage at Nordic temperatures under which the products were also installed, Nordic conditions such as crushed rock and compaction, followed by laboratory tests of the exposed and unexposed geosynthetic samples.</p>

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<p>Researchers and professionals have used several test methods (laboratory or in-field) as a tool for evaluating the dewatering performance in geotextile tubes. These test methods include bench-scale tests, midscale tests or semi-performance tests (hanging bag test and the geotextile tube dewatering test) and finally, full performance tests. Among the bench-scale tests (not standardized) are the cone test, falling head test, pressure filtration test and the most recent, the Pressurized Two-Dimensional Dewatering Test (P2DT). In this work, the P2DT were used to analyze artificial slurry's dewatering performance in the radial and axial directions. The tests were performed with a woven geotextile and artificial slurry conditioned with flocculant polymer under different hydraulic pressure configurations (with and without internal pressure) and different filling cycles. The artificial slurry was manufactured in the laboratory from a soil sample with known granulometry. During the analyzed filling cycles, it was observed that in the P2DT configuration with internal pressure (balloon use), there was a greater percolated volume with lower turbidity values when compared to the configuration without internal pressure. The results showed in both test configurations that the percolated volume and its turbidity were higher in the radial dewatering direction when compared to the axial direction. The results show the influence of the dewatering direction on the system's performance, which is an important fact to consider in the design of geotextile tubes. In addition, the results indicate the limitation of one-dimensional bench tests in predicting the performance of geotextile tubes.</p>

<p>Water and sewage treatment almost everywhere is a source of sludge due to the need of periodical cleaning of the treatment plant. In many places around the world water and sewage plants may discharge sludge without any treatment on natural water bodies posing a risk to the environment. A viable way to treat these sludge is to reduce its volume through dewatering and then to dispose the solid residue at legal landfill areas. The present paper aims to explore the efficiency of two variants of the dewatering technique with geotextile bags, analyzing the dewatering processes aiming at improving the conditions of disposal of residues with high-water content. It describes field tests performed with two geotextile bag systems, one with a geotextile bag without lateral restraints and the other with a geotextile bag with lateral restraints. Both systems were submitted to two filling cycles. Field and laboratory tests were performed using sludge from the DCTA water treatment plant in São José dos Campos – Brazil. Volume, height abatement, and solid contents due to the dewatering process were collected per time interval and compared across the two geotextile bag systems. The results showed that the geotextile bag system with lateral restraints was able to receive 20% more sludge in volume than the geotextile bag system without lateral restraints. On the other hand the results also showed that the geotextile bag system without lateral restraints reached 38% higher solid contents than the geotextile bag system with lateral restraints. At the end the results showed that both geotextile bag systems were successful, resulting in dewatering efficiencies greater than 990%.</p>

<p>Because of the excellent drainage performance, pefabricated board drains have been widely used for nearly half century and are still developing rapidly. At present, they are mainly used in the vertical drainage channel for vacuum pre-compression soft foundation reinforcement technology, as well as horizontal drainage channels. As a kind of engineering material, the pefabricated board drain has been improved greatly from paper to high performance plastic, and the discharge capacity has been greatly improved. Now harmonica type core plate structure has become the mainstream, and high permeability filter and anti-silting filter have been applied. Pefabricated board drains that can measure depth have been widely used, and new pefabricated board drains with degradable, heatable, and multiple independent channels have emerged. However, there are still many existing problems, such as the choice of hydrophilic filter or hydrophobic filter, and how to solve the reduction of water flux caused by siltation and bending when applied in fine-grained soil environment.</p>