INSTALLATION GUIDELINES. Landfills and mines

Transcription

1 INSTALLATION GUIDELINES Landfills and mines

2 Introduction Recommendations This installation manual gives general recommendations for the installation of the drainage geocomposites InterDRAIN and TechDRAIN in landfills and mines. These recommendations are subjected to the guidelines exposed by the site engineering management. and InterDRAIN and TechDRAIN drainage geocomposites are widely used in mining as well as in landfills. Common applications are: drainage of infiltrating water, collection of gas from anaerobic decomposition and/or collection of leachate. Since the installation process is the same for both products, throughout this installation manual InterDRAIN will be used to refer to both, InterDRAIN and TechDRAIN.

3 Preparation of the supporting ground Step 1 InterDRAIN may be installed over a regularized soil layer, granular material or another geosynthetic material. Ground preparation must be performed before proceeding with the installation of InterDRAIN, ensuring that the ground is as flat as possible. All cavities, irregularities and bumps that exceed 1 cm should be eliminated. If InterDRAIN is installed on top of a waterproofing geosynthetic (GBR-P or GBR-C), this element should be fully installed (including all seams and welds in all panels). ANCHOR TRENCH Anchor trench > 1 m COVER SOIL Step 2 WATERPROOFING Anchor trenches must be executed at the top of the slope and in the intermediate berms of the slopes, unless dead weights are used. Anchor trenches can be rectangular with minimum dimensions of 50 x 50 cm or can also have another geometry if it is accurately justified. For anchor trenches on top of the slope, the minimum distance between the trench and the slope is 1 m. It is not recommended to execute anchor trenches in the intermediate berms of the slopes in order to avoid transversal welds. If they must be done, they will be placed as close as possible to the upper slope. SEW OR STAPLE COVER SOIL WATERPROOFING There is no need for anchor trenches in the bottom of the slope. If trenches are opened in order to accommodate perforated drainage pipes, which will collect the water coming from InterDRAIN, these trenches may also be used to anchor the geosynthetic materials.

4 Step 3 deployment The first roll of InterDRAIN must be unrolled along the slope, from the crown downwards, ensuring a full contact with the ground. Subsequently the second roll will be unrolled next to the first one. The installation procedure must continue accordingly roll by roll, bottomed or overlapped along the roll length. The deployment of the rolls must be executed in the expected main flow direction (maximum slope direction) and in a continuous manner in order to avoid their movement due to the wind s action. The product must be installed well stretched, avoiding folds and wrinkles. If it were necessary, the position of InterDRAIN must be manually corrected after its deployment. In the presence of wind InterDRAIN must be weighted with sandbags or equivalent, preferably along the overlaps. These weights must remain installed until the soil cover or another geosynthetic layer has been placed on top of the drainage geocomposite.

5 ROLL 1 OVERLAP (10cm) CONTINUOUS SEWING OR LEISTERING (Recommended) PLASTIC TIE ROLL 2 OVERLAP (10cm) Overlaps Step 4 Adjacent drainage geocomposites must ensure a continuity of the drainage core. To do so, the drainage cores must be bottomed and the geotextiles should present a minimum overlap of 10 cm. A second option is to overlap, with a minimum of 10 cm, one geonet on top of the other geonet. It is recommended that adjacent geonets are joined by tying the geonet cores together with plastic ties (1 tie per meter). It is also recommended to heat bond or wedge weld the geotextile overlaps in order to guarantee continuous properties for this filter and separation element. OVERLAP (10cm) CONTINUOUS SEWING OR LEISTERING (Recommended) ROLL 1 ROLL 2 UPPER ROLL CONTINUOUS SEWING OR LEISTERING (Recommended) OVERLAP 80 cm (MINIMUM) LOWER ROLL SLOPE Longitudinal overlaps between rolls must be avoided as much as possible. If they were to be needed, it is recommended to execute them as close as possible to the bottom of the slope and rolls must be overlapped by placing the upper roll over the lower roll, in order to ensure a continuous flow inside the geonet. On the other hand, this overlap will also avoid that the geocomposite can be lifted by the wind. The minimum recommended overlap is 80 cm. It is also recommended to heat bond or wedge weld the geotextile overlaps.

6 Cover layer and backfilling of the anchor trench Step 5 Before covering InterDRAIN it must be ensured that there are no uncovered geonet areas (without a geotextile or with a cut or damaged geotextile). If the geotextile has been damaged (during or after the installation), the damaged piece of geotextile must be substituted by a larger patch, ensuring at all times that the drainage geonet is not left uncovered. Once all geosynthetic layers have been installed, prior to the cover soil extension, all anchor trenches must be backfilled to avoid any possible movements in the drainage geocomposite. It must be ensured that the cover soil material in contact with InterDRAIN is free of large or sharp elements that may puncture or damage the geosynthetic layers. It is recommended to place the soil cover from the bottom of the slope upwards to avoid high stresses on InterDRAIN, unless it is otherwise justified through adequate calculations. Geotextiles must be covered within 14 days after the installation unless they are UV treated.

7 Construction equipment Wide track vehicles should never ride directly over InterDRAIN unless a cover soil layer with a thickness > 0,15 m is placed as a protection element for the geosynthetic layer. It is not recommended to ride over the geocomposite with vehickes that use rubber tires. Occasionally they may ride directly over it in the planar areas (never in the slopes) reducing as much as possible the speed and avoiding any sharp turns and any fast accelerations or decelerations which may damage the geotextile. Notes InterDRAIN rolls are packed in black plastic film bags to ensure that the geotextiles are protected against UV rays. These bags must not be removed until the product must be installed. It is forbidden to store unpacked drainage geocomposites. When moving the product it is very important not to drag the rolls. They must be preferably lifted or rolled because dragging them would damage the geocomposite, specially the geotextile layer. Note that the geotextile is a filter element that ensures the hydraulic properties of InterDRAIN by avoiding the soil to enter the geonet core. InterDRAIN may be modelled or slightly bended in order to adapt to the soil's topography. InterDRAIN rolls are manufactured in standard dimensions. To adapt their length to the specific site conditions, they may be cut with a knife or cutter. It is recommended to install only the geocomposites that can be covered the same day of the installation. After unpacking the drainage geocomposites and unrolling them, the material may not be exposed to the sun for a period that exceeds 14 days, unless the nonwoven geotextile has special UV stabilization. INTERMAS NETS S.A. Ronda de Collsabadell, 11 (Polígono industrial) LLINARS DEL VALLÈS (Barcelona) - SPAIN Tel Fax geo@intermas.com