Geosynthetic Membrane Seepage Prevention for Chemical Wastewater Pools
The seepage prevention of chemical wastewater pools using geosynthetic membranes is an important engineering measure, which can effectively prevent the pollution of the surrounding environment caused by the leakage of wastewater. The following is the relevant content about the geosynthetic membrane seepage prevention for chemical wastewater pools:
Types of Geosynthetic Membranes: Commonly used geosynthetic membranes include high-density polyethylene (HDPE) geosynthetic membranes, low-density polyethylene (LDPE) geosynthetic membranes, polyvinyl chloride (PVC) geosynthetic membranes, etc. HDPE geosynthetic membranes are widely used in the seepage prevention of chemical wastewater pools due to their advantages such as high strength, chemical corrosion resistance, and low permeability.
Specification Parameters: Select appropriate thickness and specifications of geosynthetic membranes according to the properties of chemical wastewater, the depth of the pool, and the service life. Generally, the thickness of HDPE geosynthetic membranes is between 1.0 - 2.0mm, and the width of each roll is usually 6 - 8m.
Site Cleaning: Remove sundries, sharp objects, and protruding rocks in the wastewater pool to ensure that the bottom and walls of the pool are flat and smooth, without obvious unevenness and cracks.
Foundation Treatment: For soft foundations, compaction or reinforcement treatment is required to improve the bearing capacity and stability of the foundation. If there are cracks or holes in the foundation, they should be sealed and repaired.
Material Inspection: Geosynthetic membranes and related welding materials, anchoring materials, etc. should be strictly inspected for quality before entering the site. Check the quality certification documents, test reports, etc. of the products to ensure that the materials meet the design requirements. At the same time, conduct an appearance inspection of the geosynthetic membranes to check for any damages, holes, scratches, and other defects.
Laying Sequence: Generally, start laying from the bottom of the pool and then extend to the pool walls. During the laying process, pay attention to making the long side of the geosynthetic membrane perpendicular to the water flow direction to reduce the scouring of the water flow on the geosynthetic membrane.
Laying Method: After unfolding the geosynthetic membrane, try to avoid wrinkles and hanging phenomena of the geosynthetic membrane. The geosynthetic membrane can be laid flat on the foundation manually or by machine, and it should be fixed in time with sandbags or other heavy objects to prevent it from being blown up or moved by the wind.
Connection Method: The connection methods of geosynthetic membranes mainly include welding and bonding. Welding is a widely used connection method, which has the advantages of high connection strength and good sealing performance. Commonly used welding methods include hot wedge welding, hot melt extrusion welding, etc. Before welding, clean and treat the welding surface of the geosynthetic membrane to ensure the welding quality. During welding, strictly control the welding temperature, speed, and pressure and other parameters to ensure that the welds are uniform and firm, without defects such as virtual welding and missed welding. Bonding is suitable for the connection of some special parts or small areas, and special adhesives need to be used and operated according to the product instructions.
Anchoring at the Pool Bottom: At the edge of the bottom of the pool, an anchoring groove needs to be excavated. Put the edge of the geosynthetic membrane into the groove, and then backfill and compact it with soil or concrete to achieve the anchoring of the geosynthetic membrane at the pool bottom. The depth and width of the anchoring groove are generally determined according to the specifications of the geosynthetic membrane and the design requirements, usually with a depth of 30 - 50cm and a width of 20 - 30cm.
Anchoring on the Pool Walls: For the pool walls, 预埋件 (embedded parts) or expansion bolts can be used to fix the geosynthetic membrane on the pool walls. First, install the embedded parts on the pool walls or drill holes and drive in the expansion bolts. Then, connect the edge of the geosynthetic membrane to the embedded parts or expansion bolts through special fixing parts, and use sealant and other materials for sealing treatment to prevent the wastewater from leaking from the connection part.
Function: In order to protect the geosynthetic membrane from being damaged by external factors such as ultraviolet radiation, mechanical damage, and chemical corrosion, a protective layer needs to be set on the surface of the geosynthetic membrane.
Material Selection: The materials of the protective layer can be selected according to the actual situation, such as clay, sand and gravel, concrete, etc. For small wastewater pools, clay or sand and gravel can be used as the protective layer, with a thickness of generally 30 - 50cm. For large wastewater pools or occasions with high seepage prevention requirements, concrete can be used as the protective layer. The strength grade and thickness of the concrete should meet the design requirements, generally with a strength grade not lower than C20 and a thickness of 10 - 20cm.
Construction Requirements: When laying the protective layer, pay attention to avoiding damage to the geosynthetic membrane. If clay or sand and gravel are used as the protective layer, it should be laid in layers and compacted to ensure the compactness of the protective layer. If concrete is used as the protective layer, it should be poured and cured according to the relevant specifications of concrete construction to ensure the quality of the concrete.
Inspection during the Construction Process: During the laying and welding process of the geosynthetic membrane, real-time inspection should be carried out. For example, use the inflation method or vacuum method to inspect the welds to check whether there is any air leakage in the welds. For the found defects, they should be repaired in time.
Acceptance after Completion: After the geosynthetic membrane seepage prevention project of the wastewater pool is completed, a comprehensive acceptance inspection is required. The acceptance content includes the laying quality of the geosynthetic membrane, the quality of the welds, the quality of the anchoring, the construction quality of the protective layer, etc. Acceptance can be carried out through methods such as appearance inspection, sampling inspection, and pressure testing. For example, send the geosynthetic membrane for sampling inspection to test whether its physical and chemical properties meet the requirements; conduct a water filling test on the pool to observe whether there is any leakage of the geosynthetic membrane.
During the construction of the geosynthetic membrane seepage prevention for chemical wastewater pools, the construction personnel should strictly operate in accordance with the design requirements and relevant specifications to ensure the quality of the seepage prevention project, so as to effectively prevent the pollution of the environment caused by the leakage of chemical wastewater.
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