TM 5-814-7
K, the erodibility factor for the above topsoil, is 0.21
board crest-to-crest dimensions are 172 feet by 252
C, the cover factor for well established grass-like
feet).
plants is, 0.01
(5) Proposed dimensions of the 200, 000 cy landfill'
P, the erosion control practice for normal
are approximately 20 feet deep, with inboard crest-to-
conditions, is 1.0
crest dimensions 400 feet wide by about 800 feet long.
A, the soil loss in tonslacre/year, limited to < 2 per
The size of the landfill is based upon the following
RCRA guidance documents
disposal volumes:
(a) The LS landslope factor must be < 5.4;
Containerized ash
10 cy/day
therefore the following design slopes could be used:
Sludges (20 cy/day, with 1/2 dried
30 cy/day
Slope
Slope Length
Vertical Height
without volume change, and 112
solidified by absorbents, with a
3:1
34
11
doubled volume)
4:1
85
21
Operational soil cover needs (2:1
20 cy/day
5:1
180
35
(b) Based upon a design freezing index of
waste:soil ratios for 40 cy of
waste)
500 for the region, the silty clay topsoil when barren can
TOTAL
60 cy/day
freeze to a depth of about 2 feet (EPA SW-867, page
1,200 cy/mo
29).
2
14,400 cy/yr
(6) The sludges produced by the acid
(6) When 100-year flood levels are determined to be
neutralization process can be solidified by adding
above the project area, earthfill levees of compacted
nonbiodegradable absorbents or by solar drying; when
impervious soil can be constructed to prevent flooding
absorbents are used, the resultant waste volume is
(see figure 6-1).
doubled. The net May through October evaporation rate
(7) Liner systems details for this hypothetical facility
of 24 inches allows solar drying (the net annual
(including leak detection and leachate collection
evaporation of 5 inches precludes use of solar
systems) are illustrated in figures 6-2 and 6-5. The
evaporation ponds).
proposed incorporation of a secondary soil liner for the
c. Required design elements and procedures.
two waste units in this example problem (and for any
(1) Design elements for the surface impoundment
waste unit) should be based upon the premise that there
include:
is little or no potential for ground-water flow into the
a dike along two perimeters of the impoundment
detection system. The construction of project earthfills
run-on control ditches
and proposed clay liners (in accordance with placement
a double liner system with leak detection which
requirements described in paragraph 6-3 and in EPA
includes a protective cover, a primary synthetic
SW-870) will provide an adequate secondary liner and
liner, a leak detection system, and a secondary
soil subbase for other liner elements at this facility.
soil liner.
(a) Given a DA requirement to limit the number
inlet and outlet pipes (12-inch-diameter pipes to
of field seams and locate such seams to minimize the
be provided; these will be equipped with
potential for leakage, field panel widths of approximately
automatic flow controls to prevent overtop ping).
100 feet for the primary synthetic liner are proposed.
ground-water monitoring wells
The liner material for the two waste units will be
(2) Design elements for the landfill include:
restricted to CPE and CSPE, based upon compatibility
an earthfill berm along the end of the landfill
testing and panel size needs. The actual panel sizes
run-on/run-off control facilities
and layouts are contingent upon required spacing for the
a double liner system with leak detection, which
leak detection and leachate collection systems and will
includes a leachate collection system, a primary
be developed after selecting these design dimensions.
synthetic liner, a leak detection system and a
(b) Calculations for the leak detection and
secondary soil liner
leachate collection systems, and material selections,
final cover (for closure)
are:
ground-water monitoring wells
(3) Figure 5-1 illustrates layouts for typical surface
Infiltration rates for system design:
impoundments and a landfill, and figures 5-2, 6-1, 6-2, 6-
--Assuming seepage through the secondary
5, 6-6, 6-7 and 6-10 show design details.
(4) Proposed dimensions for the 2, 000, 000 gallon
1
A desired service life of 15 years requires
capacity surface impoundment are a 10-foot liquid depth
about 200,000 cubic yards of capacity.
with a 2-foot freeboard, 3:1 construction slopes, base
2
Based upon 5 days/week, 20 days/month, 240
dimensions 100 feet wide by 180 feet long (in-
days/year.
C-2
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