Pond Underlayment Pond Underlayment is recommended for all pond liners, especially EPDM liners. Available in several different sizes, Pond Underlayment accommodates any size pond by simply overlapping multiple pieces–no seaming required. Specifications ⌄ UL1210: 12’ X 10’ UL1220: 12’ X 20’ UL6100: 6’ X 100’ UL12100: 12’ X 100’ UL61006: 6’ X 100’ UL121006:12’ X 100’ More Details How to Use Resources No Specifications available. No product additional details available. Teton Pond Liner Information