TerraDrain® Sheet 56/2

TerraDrain® Sheet 56/2 prefabricated drains are constructed using a perforated, formed polystyrene drainage core with a nonwoven filter fabric bonded to both sides. The filter fabric prevents soil intrusion into the flow channels while allowing water to freely enter the drain core from both sides.

TerraDrain® Sheet 56/2 products are designed for subsurface, double-sided drainage applications requiring a moderate compressive strength and flow capacity. TerraDrain® Sheet 56/2 is available with filter fabrics meeting AASHTO M 288-06 specifications.

All values provided are intended for rapid comparison purposes, only. Please refer to a specific product’s Product Data Sheet (PDS) and the disclaimers therein for a detailed listing of all characteristics, associated definitions and values needed for structure design, specification compliance review and product submittal purposes. Please Download PDS for all information transfer, printing and submittal purposes.

Property Test Method English Metric


Material 1
Water Flow Rate
ASTM D4491 110 gpm/ft2 4483 Lpm/m2
Grab Tensile Strength
ASTM D4632 160 lbs 0.712 kN
CBR Puncture Resistance
ASTM D6241 450 lbs 2.00 kN
Apparent Opening Size
ASTM D4571 70 US Std. Sieve 0.210 mm
ASTM D4491 1.8 sec-1 1.8 sec-1
Grab Elongation
ASTM D4632 70 % 70 %
UV Resistance
ASTM D4355 70 % @ 500 hrs 70 % @ 500 hrs
AASHTO M 288-06 2
Survivability Class 2 Class 2


Material 1
ASTM D1777 0.25 in 6.35 mm
Compressive Strength
ASTM D1621 11000 lbs/ft2 527 kPa
Flow Rate 3
ASTM D4716 12.5 gpm/ft 155 Lpm/m

  • 1   PP = Polypropylene; HIPS = High Impact Polystyrene
  • 2   AASHTO Designation: M 288-06 Standard Specification for Highway Applications; American Association of State Highway and Transportation Officials, 2006. Geotextile survivability classification from installation stresses in subsurface drainage applications.
  • 3   In-plane flow rate measured at 3,600 psf (172 kPa) compressive load and a hydraulic gradient of 1.0.