Okla. Stat. tit. 27A, § 27A-2-10-801.2: Solid waste landfill - Exterior and interior

slopes.

A. Except as provided in subsection B of this section, the

owner and operator of a solid waste landfill shall ensure the

following:

1. Exterior slopes, to the edge of the permitted footprint, are

maintained at all times to be no steeper overall than four (4)

horizontal to one (1) vertical (4:1), except as otherwise provided

in a plan approved by the Department of Environmental Quality; and

2. All interior slopes are maintained at all times to be no

steeper overall than three (3) horizontal to one (1) vertical (3:1),

except as otherwise provided in a plan approved by the Department.

B. The working face slopes of a solid waste landfill may vary

during daily placement of waste but shall be graded to meet the

applicable interior or exterior slope grades prior to placement of

the daily cover of soil or approved alternate daily cover material.

C. The Environmental Quality Board is authorized to promulgate

rules recommended by the Solid Waste Management Advisory Council as

needed to implement the provisions of this section.