Coarse, broadly ed, cohesionless glacial till soils are uently encountered in construction projects. In filtration applications, these soils can present design problems because of their high silt content, 10V plasticity and sometimes internal instability. Engineers often are of using geotextiles with such soils. To determine the filtration capability of geotextiles with till soils, gradient ratio tests (ASTM D 5101) were performed using tills from northwestern Washington State (U.S.A.). d four different geotextiles. The 1esults of these tests indicate adequate retention of the till soils by the geotextil ; HO’NeVer, some clogging of the geotextiles WclS observed. Initial indications are that existing geotextile filter design criteria do not adequately predict the behavior of these soils.