EXAMPLE DESIGN PROBLEM
Solid hazardous wastes (for landfilling) consist
C-1. Purpose and Scope
of (1) incinerator ash containing lead (10 cubic
The design example in this appendix illustrates
yards (cy) per day), and (2) sludges produced by
predesign considerations and design principles that
relate to the development of plans for a hazardous waste
b. Pre-design evaluation. Given the scenario
landfill and surface impoundment. Both facilities are
described above, the design engineer will initially review
assumed to be developed for an existing government
available documents and evaluate site conditions and
owned, contractor-operated, industrial installation that
waste types and quantities. In addition, the engineer will
perform additional hydrogeologic services identified in
materials. Where appropriate, the design engineer is
paragraph 3-3 of this TM including geologic mapping of
directed to primary references for additional details, as
the proposed site locations, drilling borings and
well as to several figures in this TM for typical layouts
excavating test pits, and testing soils for geotechnical
and design details. As needed, assumptions underlying
properties. Based on the available information, logs of
the selection of design elements will be noted.
borings, and additional test results, engineering
C-2. Design Example
properties of soils and related pre-design calculations
a. Site Scenario. The general location, size,
and evaluations will be made; these are summarized
hydrogeologic conditions, climate, and anticipated
(1) Available data verify that both the
surface impoundment and the landfill can be developed
A 2,000-acre installation in the Midwest char-
with adequate' vertical separation, and hydraulic
acterized by rolling hills above an adjacent val-
separation from ground water. Construction areas are
well above the 100-year flood plain. Both units allow
Located within Seismic Zone 2, as defined by
paragraph 3-4 of TM 5-809-10.
soils for soil berms and secondary liners, and soil cover
needs for the operation and closure of the landfill.
tall snowfall of 17 inches.
(2) Tests of clayey soils determine that
Average daily maximum temperature of 80F
they exhibit a Liquid Limit of 40 and a PI of 18, a dry
for May through October and average daily
density of 105 pcf, an optimum moisture content of 19
minimum of less than 32F for December, Jan-
percent, and a permeability of 3 x 10-8 cm/sec at
uary and February.
optimum plus 4 percent. When they were subjected to
the hazardous wastes to be contained, the clayey soils
exhibited a permeability of 5 x 10-8 cm/sec.
(3) Based on stability analysis, earthfill
100-year, 24-hour design storm of 5.8 inches.
berms or dikes constructed with on-site clayey soils will
Design freezing index of 500 for the region.
have an adequate factor of safety for stability under static
Silty clay topsoil 1 to 3 feet in thickness.
and seismic loadings, provided they are constructed with
Glacial till clayey soils interspersed with dis-
a 12-foot-minimum crest width, a maximum height of 25
continuous sand stringers to a depth of 200 feet
feet, and side slopes of 3:1 or less (see para 3-3).
over a shale bedrock.
(4) Based on current publications on
Ground water (which occurs within on-site
compatibility testing (EPA SW-870), supportive
swales) found at depths ranging from 90 to 120
information from several lining manufacturers, and
feet below the surface; flow direction is toward
accelerated testing (using the waste to be contained), the
the adjacent valley.
following liners were determined to be suitable for the
Ground water of drinking water quality exists
project: chlorinated polyethylene (CPE), chlorosulfonated
in only limited amounts; it is not a measurable
polyethylene (CSPE), and high density polyethylene
source of recharge to the valley aquifer.
(HDPE) (see para 6-3).
Liquid wastes (designated for the surface im-
(5) In accordance with the Universal Soil
poundment) consist of acidic wastewater; maxi-
Loss Equation, (EPA SW-867, page 37) A = RKLSCP,
mum volume of liquid waste storage is
R, the rainfall erosion index for the location, is