SECTION 252:515-19-53. Final cover

(a)   Design standard. When final cover is installed, it shall be installed in accordance with the approved closure plan, and shall, at a minimum, be comprised of an erosion layer over a barrier layer.

(1)   Barrier layer. The barrier layer shall be at least 24 inches of earthen material with a hydraulic conductivity:

(A)   less than or equal to the hydraulic conductivity of any bottom liner system or natural subsoils present; or

(B)   no greater than 1 x 10^-5 cm/sec; whichever is less.

(2)   Erosion layer. An erosion layer shall be installed above the barrier layer, consisting of at least one foot of soil capable of sustaining plant growth.

(3)   Gradient. To prevent ponding, the final cover gradient on top of the fill, as measured from the center of the fill area to the break in slope between the top and sides of the fill, shall be four percent (4%) (25:1), unless otherwise approved by the DEQ.

(4)   Side slopes. The final side slope gradient shall not exceed twenty-five percent (25%) (4:1).

(5)   Vegetation. Vegetation meeting the requirements of OAC 252:515-19-54(3), (4), and (5) shall be established during the first growing season.

(6)   Contours. Surface contours, including final grading of completed disposal areas, shall prevent ponding of water and erosion of fill areas.

(7)   Waste free. The final cover material shall be free of garbage, trash or other unsuitable material.

(b)   MSWLFs. A flexible membrane liner equivalent to that used in the bottom liner system shall be installed between the barrier layer and the erosion layer at MSWLFs equipped with a composite liner.

(c)   Alternative final cover. The DEQ may approve the use of an alternative final cover design upon a demonstration the alternative provides equivalent protection to that afforded by (a) and (b) of this Section.

[Source: Added at 20 Ok Reg 1151, eff 6-1-03]