State of New Mexico

(a) Subsurface Drainage Geotextile - Provide Class 2 geotextiles for drain system installations that require use of very coarse, sharp angular aggregate with a 1-inch- diameter or greater, or require a depth of trench greater than 6 ft. Provide Class 3 geotextiles for general underdrain installations that require smooth graded surfaces having no sharp angular projections and fine aggregate.

(b) Separation Geotextile - Use a Class 2 separator for Pavement Structures constructed over soils with an R-value greater than 20 to separate dissimilar Materials where water seepage is allowable. Use Class 2 geotextiles where installation requires a depth of trench greater than 10 ft, where stone drop height is to be more than zero, or where there is no sand cushion protection. The Department requires field trials where stone drop height exceeds 3 ft or where individual stone weight exceeds 250 lb. Use Class 3 geotextiles to prevent mixing of a Subgrade soil and an aggregate cover Material (Subbase, base, select Embankment, etc), to separate dissimilar Materials where water seepage is allowable. Do not use Class 3 geotextiles under pavement. The Contractor may also use Class 3 geotextiles in Structures or under conditions where the geotextile is protected by a sand cushion or by “0 drop height” placement of stone. Use Table 604.2.4:1, “Required Class of Separator Geotextile and Cover Thickness for R-values Greater Than or Equal to 20,” to determine the class of separator geotextile and the required minimum thickness.

(c) Stabilization Geotextile -Provide stabilization geotextile in wet, saturated conditions to provide separation, filtration, and also reinforcement. Use stabilization geotextiles for Pavement Structures constructed over soils with R-values from 10 to 20. The Contractor may provide stabilization geotextiles made of woven or non-woven Material. The Contractor may use stabilization geotextiles in applications that require a design by a licensed professional engineer. Obtain Department approval of these designs.

(d) Erosion Control Geotextile - The Department prohibits the use of woven slit film geotextiles or geotextiles made from yarns of a flat tape-like character. If the Contractor uses a woven monofilament geotextile, the Contractor shall provide a Class 2 geotextile, otherwise the Contractor shall provide a Class 1 geotextile.