Page 389 - Materials Chemistry, Second Edition

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360 Waste Management Practices: Municipal, Hazardous, and Industrial
A wide range of variables are incorporated into the HELP model including weather, soil type,
design feature, surface storage, snowmelt, runoff, infiltration, evapotranspiration, vegetative growth,
soil moisture storage, lateral subsurface drainage, leachate recirculation, unsaturated vertical drainage,
and ultimately leakage through the soil and composite liners. Use of the HELP model requires general
climatic data (e.g., precipitation, relative humidity, and solar radiation) for performing each landfill
design analysis. HELP has a historical database built into the program which contains 5 years of daily
precipitation data for 102 cities throughout the United States. The model also contains default values
for soil characteristics, total porosity, field capacity, wilting point, and saturated hydrologic conduc-
tivity. Other parameters incorporated within the model include layer thickness, area, slope and maxi-
mum drainage distance, layer description, surface characteristics, and geomembrane characteristics.
The inclusion of these default values allows the user to formulate hypothetical situations to determine
the impact of a particular landfill design on the local environment.
The program provides for rapid estimation of the daily, monthly, annual, and average annual
amounts of runoff, evapotranspiration, drainage, leachate collection, and liner leakage that may
result from the operation of a wide variety of landfill designs. The model applies to open, partially
closed, and fully closed sites.
The goal of this activity is to familiarize you with the HELP model and its capabilities. You will
generate results and evaluate two landfill types using data for two hypothetical land disposal facil-
ities. The procedures for performing an analysis are provided below along with a series of ques-
tions. A list of relevant terms has also been provided.

DOWNLOADS
The HELP model can be downloaded from the U.S. Army Corps of Engineers site, http://www.wes.
army.mil/el/elmodels/ Engineering documentation for Version 3 of the model is also available at this
site. The complete HELP User’s Guide is available at: http://www.epa.gov/cgi-bin/claritgw?op-
Display&document clserv:ORD:0790;&rank 4&template epa

A.10.1.3.1 Using the HELP Model

Some Notes about the Use of DOS Screens
For many students, experience with DOS may be minimal. Some instructions are provided below
for operating HELP in the DOS mode.
Moving between cells: By pressing the Page Down key or Page Up for selecting next/previous
screen; Up and Down arrows — to move through the cells of a screen; Tab and Shift-Tab keys —
to move to the right and to the left between the same line.
Moving within an input cell: Each input cell is set to a given width depending upon the type of
information expected to be entered in that cell.
Terminating: Press the F9 key to quit without saving changes, return to the main menu and
exit the program; Esc key and Ctrl-Break — end some options and allow to continue with other
operations; F10 — save the data; Ctrl-Alt-Del —termination of input or execution (by resetting or
turning off the computer).
On-line help: Available from any cell location on the screen; F1 — information about the oper-
ations and purposes of the screen; F2 – specific technical assistance for the highlighted cell; F3 –
various functions of keystrokes.
System of units: The HELP model allows the student to use either: the customary system of
units (a mixture of U.S. and metric units traditionally used in landfill design) or metric units.
The value for a particular variable can be input for the first time or at a later time during the
program session. If an input cell is left blank, a value of 0 will be assigned to the corresponding
variable. The program will warn the user when a blank or zero is an inappropriate value.