NATURAL RESOURCES CONSERVATION SERVICE CONSERVATION PRACTICE STANDARD POND SEALING OR LINING - FLEXIBLE MEMBRANE (No.) 521A A manufactured hydraulic barrier consisting of a Materials. Flexible membrane liner functionally continuous layer of synthetic or materials shall meet the requirements of the partially synthetic, flexible material. specifications indicated in the following tables: To restrict, impede, and control seepage of water and contaminants from water and waste Minimum Bentonite Content for impoundment structures for water conservation Geosynthetic Clay Liners and environmental protection. Type Minimum Bentonite Content Wastewater Water GCL 0.75 lb/sq. ft. On ponds and water storage structures that require treatment to control seepage rates within Reference Specifications for acceptable limits. Geomembranes On earthen waste storage ponds or lagoons and Type Applicable Specification other waste impoundment structures that require HDPE treatment to control seepage of contaminants LLDPE from the storage structure. LLDPE-R PVC Design. Structures to be lined shall be Minimum Geomembrane Thickness Criteria constructed to meet all applicable NRCS Type Minimum Thickness standards. All inlets, outlets, ramps, and other Wastewater Clear Water appurtenances may be installed before, during, or after the liner placement, but shall be done in HDPE 40 mil 30 mil a manner that does not damage or impair the NRCS Mtl. Spec. 594, LLDPE 40 mil 30 mil proper operation of the liner. Geomembrane Liner 36 mil 24 mil Design and installation of the flexible membrane PVC 40 mil 30 mil shall be in accordance with manufacturer EPDM 45 mil recommendations. All flexible membrane FPP 40 mil 30 mil installations shall be certified by the installer or manufacturer as meeting the material and FPP-R 36 mil 24 mil installation requirements of the plans and PE-R NR 24 mil specifications. EPDM Manufacturer recommendations shall be followed with regard to protection from weather FPP and exposure.
NATURAL RESOURCES CONSERVATION SERVICE CONSERVATION PRACTICE STANDARD POND SEALING OR LINING - FLEXIBLE MEMBRANE (No.) 521A A manufactured hydraulic barrier consisting of a functionally continuous layer of synthetic or partially synthetic, flexible material. To restrict, impede, and control seepage of water and contaminants from water and waste impoundment structures for water conservation and environmental protection. On ponds and water storage structures that require treatment to control seepage rates within acceptable limits. On earthen waste storage ponds or lagoons and other waste impoundment structures that require treatment to control seepage of contaminants from the storage structure. Design. Structures to be lined shall be constructed to meet all applicable NRCS standards. All inlets, outlets, ramps, and other appurtenances may be installed before, during, or after the liner placement, but shall be done in a manner that does not damage or impair the proper operation of the liner. Design and installation of the flexible membrane shall be in accordance with manufacturer recommendations. All flexible membrane installations shall be certified by the installer or manufacturer as meeting the material and installation requirements of the plans and specifications. Manufacturer recommendations shall be followed with regard to protection from weather and exposure. Materials. Flexible membrane liner materials shall meet the requirements of the specifications indicated in the following tables: Minimum Geomembrane Thickness Criteria Type Minimum Thickness Wastewater Clear Water HDPE 40 mil 30 mil LLDPE 40 mil 30 mil 36 mil 24 mil PVC 40 mil 30 mil EPDM 45 mil FPP 40 mil 30 mil FPP-R 36 mil 24 mil PE-R NR 24 mil Minimum Bentonite Content for Geosynthetic Clay Liners Type Minimum Bentonite Content Wastewater Water GCL 0.75 lb/sq. ft. Reference Specifications for Geomembranes Type Applicable Specification HDPE NRCS Mtl. Spec. 594, Geomembrane Liner LLDPE LLDPE-R PVC EPDM FPP
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