Gravel trenches, mound system beds and perimeter drain aggregate all need to be covered with a barrier material that keeps the back-filled soil from penetrating down into the aggregate. In the past, this fabric has been called geo-textile fabric (in Indiana). Our new septic rule, 410 IAC 6-8.2, requires a heavier and stronger material.
View the Indiana State Department of Health’s list of approved manufacturers here: Interpretation_410_IAC_6-8-2-66_Barrier_Materials_11-03-11
The new rule states:
410 IAC 6-8.2-66 Barrier materials
Sec. 66. (a) Barrier material shall meet the following requirements:
(1) Be synthetic fabric, either spun bonded or woven.
(2) Have the following physical characteristics:
(A) A weight equal to or greater than three and one-tenth (3.1) ounces per square yard.
(B) A grab tensile strength equal to or greater than eighty (80) pounds.
(C) A grab tensile elongation less than or equal to fifty percent (50%).
(D) A trapezoid tear strength equal to or greater than thirty (30) pounds.
(E) A puncture resistance equal to or greater than thirty (30) pounds.
(F) A Mullen Burst equal to or greater than one hundred forty-five (145) pounds per square inch.
(G) A permittivity of less than or equal to 2.2 sec-1.
(H) A water flow rate less than or equal to one hundred fifty (150) gallons per minute per square foot.
(I) A UV resistance at five hundred (500) hours equal to or greater than seventy percent (70%) strength retained.
(3) Have the following chemical characteristics:
(A) Be nonbiodegradable.
(B) Be resistant to acids and alkalies within a pH range of 4 to 10.
(C) Be resistant to common solvents.
(b) Installation of barrier material shall meet the following requirements:
(1) For aggregate trenches and elevated sand mound aggregate beds, barrier material shall be placed on the aggregate to prevent soil particle movement into the aggregate.
(2) The barrier material shall cover the aggregate of aggregate trenches and elevated sand mound aggregate beds from side to side and from end to end.