Abstract: A weather resistant commodity stockpile and collection pond covering system made up of a plurality of sheets joined together in waterproof seams. A plurality of flexible cords are tightly encapsulated and fixed in each sheet at spaced apart locations within thermally welded prayer seams and utilized for retention of the cover system and the hanging of ballast bags. The peeling stresses on the prayer seams are transferred as shearing stresses to lap seams formed by welding choker strips to the cover sheets on either side of each prayer seam. Side cords encapsulated in edge seams along side edges of adjacent sheets are abutted together and secured by flexible ties to form joints between sheets. Those joints are made waterproof by edge flaps attached to the sheets which are extended over each joint and sealed to the face of an adjoining sheet.