NTPEP APPROVED - GTX-2013-01-043. GEO 1540 is a woven monofilament filtration geotextile made of 100% high-tenacity polypropylene yarns. This product's Percent Open Area of 10% gives it excellent hydraulic properties, while reducing the chances of clogging. GEO 1540 resists ultraviolet and biological deterioration, rotting, naturally encountered basics and acids. Polypropylene is stable within a pH range of 2 to 13. GEO 1540 meets the following M.A.R.V. values except where noted. Click here for Product Data Sheet.