This table shows sand material specifications.
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Parameter specification Size Notes
Sand clean AASHTO M-6 or ASTM C-33 concrete sand 0.02” to 0.04” Sand substitutions such as Diabase and Graystone #10 are not acceptable. No calcium carbonated or dolomitic sand substitutions are acceptable. Rock dust cannot be substituted for sand.
Underdrain Gravel AASHTO M-43 1.5” to 3.5”
Geotextile Fabric (if required)

ASTM D-4833 (puncture strength - 125 lb.) ASTM D-1117 (Mullen Burst Strength - 400 psi)

ASTM D-4632 (Tensile Strength - 300 lb.)
0.08” thick equivalent opening size of #80 sieve Must maintain 125 gpm per sq. ft. flow rate. Note: a 4” pea gravel layer may be substituted for geotextiles meant to separate sand filter layers.
Impermeable Liner (if required)

ASTM D-4833 (thickness) ASTM D-412 (tensile strength 1,100 lb., elongation 200%) ASTM D-624 (Tear resistance - 150 lb./in)

ASTM D-471 (water adsorption: +8 to -2% mass)
30 mil thickness Liner to be ultraviolet resistant. A geotextile fabric should be used to protect the liner from puncture.
Under-drain Piping ASTM D-1785 or AASHTO M-278 minimum 4” rigid schedule 40 PVC 3/8” perf. @ 6” on center, 4 holes per row; minimum of 3” washed #57 stone over pipes; not necessary underneath pipes