Wis. Admin. Code Department of Natural Resources § NR 504.12 - Minimum design and construction criteria for CCR landfills
(1) APPLICABILITY.
In addition to ss. NR 504.04 to 504.10, applicable to all landfills or
landfills accepting high volume industrial waste, this section includes design
criteria that are applicable to the construction of a new or existing CCR
landfill or a lateral expansion of a CCR landfill.
(2) RUN-ON AND RUN-OFF CONTROLS. An existing
or new CCR landfill or any lateral expansion of a CCR landfill shall be
designed, constructed, operated, and maintained with a run-off and run-on
control system in accordance with the requirements under s. NR 504.09 (1) (f)
and (g) and all of the following:
(a) A
run-on control system shall prevent flow onto the active portion of the CCR
landfill during the peak discharge from a 24-hour, 25-year storm.
(b) A run-off control system from the active
portion of the CCR landfill shall collect and control, at a minimum, the water
volume resulting from a 24-hour, 25-year storm.
(3) LINER DESIGN.
(a) A new CCR landfill or a lateral expansion
of a CCR landfill shall be designed, constructed, operated, and maintained with
a composite liner that meets the requirements under s. NR 504.06 (2) and (3)
and a leachate collection and removal system that meets the requirements under
s. NR 504.06 (5). The composite liner shall consist of 2 components; the upper
component shall consist of a nominal 60-mil or thicker geomembrane liner, and
the lower component shall consist of a minimum 4-foot-thick layer of compacted
clay. A GCL and soil barrier may be used in place of the clay layer of a
composite liner in accordance with s. NR 504.06 (7). In addition to the minimum
design and construction criteria for landfill liners and leachate collection
systems under s. NR 504.06, the liner and leachate collection system shall meet
all of the following:
1. The leachate
collection and removal system shall be designed, constructed, operated, and
maintained to limit the leachate head level on the liner to one foot or
less.
2. The leachate collection
and removal system shall be constructed of materials that exhibit all of the
following properties:
a. Chemically resistant
to the CCR and any non-CCR waste managed in the CCR landfill and the leachate
expected to be generated.
b. Of
sufficient strength and thickness to prevent collapse under the pressures
exerted by overlying waste, waste cover materials, and equipment used at the
CCR landfill.
3. The
leachate collection and removal system shall be designed and operated to
minimize clogging during the active life and during the long-term care of the
landfill.
4. The geomembrane
component of the liner shall be installed in direct and uniform contact with
the compacted clay soil component.
5. A liner that utilizes a GCL and soil
barrier layer in accordance with s. NR 504.06 (7) shall be designed to have a
liquid flow rate no greater than the liquid flow rate through 2 feet of
compacted soil with a hydraulic conductivity of 1 x 10 -7 cm/sec. The liquid
flow rate comparison shall be made using the following equation, which is
derived from Darcy's Law for gravity flow through porous media:
Q/A = q = k (h/t + 1)
Where:
Q = flow rate (cubic centimeters / second).
A = surface area of the liner (squared centimeters).
q = flow rate per unit area (cubic centimeters / second / squared centimeter).
k = hydraulic conductivity of the liner (centimeters / second).
h = hydraulic head above the liner (centimeters).
t = thickness of the liner (centimeters).
(b) A new CCR landfill or a
lateral expansion of a CCR landfill shall be designed and constructed with a
subbase grade that is located no less than 5 feet above the upper limit of the
uppermost aquifer, or shall demonstrate that there will not be an intermittent
recurring or sustained hydraulic connection between any portion of the base of
the CCR landfill and the uppermost aquifer due to normal fluctuations in
groundwater elevations, including the seasonal high water table.
Note: A new CCR landfill or lateral expansion of a CCR landfill is also required to comply with s. NR 504.06 (2) (b) or (4) for zone-of-saturation landfills. The definition of an uppermost aquifer can be found under s. NR 500.03 (246m).
(c) A new CCR landfill or a lateral expansion
of a CCR landfill may not be constructed over a closed CCR surface
impoundment.
(4) FINAL
COVER SYSTEM.
(a) A new or existing CCR
landfill or a lateral expansion of a CCR landfill shall be designed and
constructed with a final cover system that meets the requirements under s. NR
504.07.
(b) The owner or operator
of a new or existing CCR landfill or a lateral expansion of a CCR landfill may
propose an alternative final cover system design within a written closure plan
in accordance with s. NR 504.10 and all of the following:
1. The permeability of the final cover system
shall be less than or equal to the permeability of any bottom liner system or
natural subsoils present or shall be no greater than 1 x 10 -5 cm/sec,
whichever is less.
2. The design of
the final cover system shall include an infiltration layer that achieves an
equivalent reduction in infiltration as the layers specified under s. NR 504.07
(4).
3. The design of the final
cover system shall include an erosion layer that provides equivalent protection
from wind or water erosion as the topsoil layer specified under s. NR 504.07
(7).
4. The disruption of the
integrity of the final cover system shall be minimized through a design that
accommodates settling and subsidence.
Notes
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