Current through Vol. 42, No. 1, September 16, 2024
(a) Valley fills
and head-of-hollow fills shall meet the requirements of Section
460:20-43-24
and the additional requirements of this Section.
(1) Drainage control.
(A) The top surface of the completed fill
shall be graded such that the final slope after settlement will be toward
properly designed drainage channels. Uncontrolled surface drainage may not be
directed over the outslope of the fill.
(B) Runoff from areas above the fill and
runoff from the surface of the fill shall be diverted into stabilized diversion
channels designed to meet the requirements of Section
460:20-43-10 and, in
addition, to safely pass the runoff from a 100-year, 6-hour precipitation
event.
(b)
Rock-core chimney drains. A rock-core chimney drain may be used in
a head-of-hollow fill, instead of the underdrain and surface diversion system
normally required, as long as the fill is not located in an area containing
intermittent or perennial streams. A rock-core chimney drain may be used in a
valley fill if the fill does not exceed 250,000 cubic yards of material and
upstream drainage is diverted around the fill. The alternative rock-core
chimney drain system shall be incorporated into the design and construction of
the fill as follows.
(1) The fill shall have,
along the vertical projection of the main buried stream channel or rill, a
vertical core of durable rock at least 16 feet thick which shall extend from
the toe of the fill to the head of the fill, and from the base of the fill to
the surface of the fill. A system of lateral rock underdrains shall connect
this rock core to each area of potential drainage for seepage in the disposal
area. The underdrain system and rock core shall be designed to carry the
anticipated seepage of water due to rainfall away from the excess spoil fill
and from seeps and springs in the foundation of the disposal area. Rocks used
in the rock core and underdrains shall meet the requirements of Section
460:20-43-24(f)
(2) A filter system to ensure the
proper long-term functioning of the rock core shall be designed and constructed
using current, prudent engineering practices.
(3) Grading may drain surface water away from
the outslope of the fill and toward the rock core. In no case, however, may
intermittent or perennial streams be diverted into the rock core. The maximum
slope of the top of the fill shall be 33h:1v (3 percent). A drainage pocket may
be maintained at the head of the fill during and after construction, to
intercept surface runoff and discharge-the runoff through or over the rock
drain, if stability of the fill is not impaired. In no case shall this pocket
or sump have a potential capacity for impounding more than 10,000 cubic feet of
water. Terraces on the fill shall be graded with a 3 to 5 percent grade toward
the fill and a 1 percent slope toward the rock core.
