A Model for
      Regional Solid Waste
     Management Planning

     This report was prepared by the Mitre Corporation, Bedford,
Massachusetts, under Contract No.  68-01-2976.
     An environmental protection publication (Igpi) in the solid waste
management series.  Mention of commercial  producTsdoes not constitute
endorsement by the U.S.  Government.

     Single copies of this publication are available from Solid Waste
Information, U.S. Environmental Protection Agency, Cincinnati, Ohio

         WRAPPING UP

             A Model for
        Regional Solid Waste
        Management Planning
    This report ^HH^as prepared for the Office of Solid Waste
           under contract No. 68-01-2976
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402


    According to a  1973 survey conducted by the
National League  of Cities, municipal officials across
the country  feel that solid  waste management  is
the most  critical issue facing  their administrations.
And  a  recent  Environmental  Protection  Agency
Report  to  Congress on  Resource  Recovery  and
Waste Reduction states that the amount of municipal
solid  waste  disposed annually will increase by 30
million tons in the next 10 years.

    States, regions, counties, cities and towns across
the country  are  facing critical questions about what
to do with solid waste.  How can we  plan systems
that dispose of  these wastes?  Which  of the many
disposal options  is  the best?  Which will meet en-
vironmental  objectives as well as provide the least
expensive  solution?   These questions are particularly
difficult to answer when a plan  must be developed
for a region consisting of a number of municipali-
ties, a  large area,  and  a  complex transportation

    In  order  to assist  decision makers  with these
and other complex  questions,  a  computer model
called WRAP (Waste  Resources Allocation Program)
has been developed.  The model enables  its users  to
quickly sort out all the various options and generate
and calculate the  cost of a  number of solid waste
management plans.

    Each  plan  indicates  the  selection, location and
capacity of sites and processes, and the flow of waste
throughout  the  region's  transportation  network.
Total  annual cost of the system and cost per ton are
computed.  One of  the most important features  of
the model is that it can be used to guide the decision-
making problem in  the selection of alternative sys-
tems and to translate the impact of this selection into
cost figures.

    What  WRAP can do to help decision makers, and
how it can do it, are the subjects of this document.

    This report has  been prepared  by the MITRE
Corporation,  Bedford, Massachusetts, (Contract No.
68-01-2976) for the Systems Management Division
of the Office of Solid Waste, U.S. Environmental Pro-
tection Agency, under the direction of Ms.  Donna M.

                           -SHELDON MEYERS
            Deputy Assistant Administrator for the
                             Office of Solid Waste


                              TABLE OF CONTENTS


MANAGEMENT PROBLEM                                                   1

MAKING TOOL                                                          2

WHAT IS A MODEL?                                                       2

USE THE MODEL?                                                        3

HOW IS THE WRAP MODEL USED?                                             3

WHAT IS NEEDED TO USE WRAP?                                             4

MODEL?                                                               5

BE USED?                                                              5

BEEN USED?                                                            5

THE MODEL ANSWERED?                                                   5

EXAMPLES OF MODEL USE                                                 6

IS AVAILABLE ABOUT WRAP?                                              10

OBTAINED?                                                           10


    The millions of tons of  solid waste produced
annually create difficult decisions that must be made
at local levels. City councils, mayors, town managers,
public works officials, and state  solid waste agencies
must  decide today how to dispose of the solid waste
generated within  their  jurisdictions.  The decisions
were  once rather  straightforward:  engineering firms
were  contracted to upgrade  existing incinerators or,
build  new ones, or new landfill  sites were located.

    But today,  officials are  confronted with  a com-
plex  and confusing  array of  alternatives and  con-
          landfills have traditionally been the  least
expensive method of disposal, but today land is be-
coming difficult  to  find.   Incinerators  designed  to
comply with  environmental  regulations are  increa-
ingly   expensive.     Similarly,  the newly  emerging
resource recovery technologies offer environmentally
sound  waste disposal, but are  generally too expensive
for single communities to  own and  operate.  Thus
there  are strong pressures toward regionalization  of
solid waste management functions.

    Regionalization, however, gives rise to two fun-
damental problems:

    •     complexity of the regional system  design;

    •     obtaining  a  political consensus amongst
          the participants.

These  issues can  best  be  addressed by developing
and clearly  presenting  technical and economic data
about   the   consequences  of  various  regional
    Selection and implementation of a regional solid
waste management plan can be viewed as one of ec-
onomic choice in which  decision makers must seek
the  least  expensive  solution  that meets  environ-
mental  and  political constraints.   In  this context,
solid  waste  management planning  is  sensitive to  a
number of important conditions.

    First,  there  are  important variations in  condi-
tions  found  in different  regions.   The quantity of
waste generated may vary considerably:   from a very
few  tons per day  to  many thousands  of  tons per
day.   Regions differ  in  the  prices obtainable for
recovered materials and in the transportation costs
necessary to realize those prices.   They also differ
in the availability and proximity of land  for landfill.
Therefore, the system that is right  for one region  is
not necessarily right for another.

    Secondly,  there is  a tradeoff on haulage costs
versus processing costs  —  that  varies among tech-
nologies — which is  represented  by the choice be-
tween central or dispersed locations  for processing
facilities.   Larger facilities can generally process  a
ton of refuse at  a lower  cost  than  smaller  facilities.
Thus,  the  decision to choose  a centralized process-
ing center makes available  economies  of scale in
processing,  but at the  expense  of higher haulage
costs  to achieve the required volume  of waste.  On
the other hand, a system  of dispersed processing will
offer  lower haulage costs at the sacrifice of econo-
mies of scale  in processing.
                                  TRANSPORTATION COST
            O SIZE OF REGION
            O GROSS TONNAGE
    Finally,  a  proper economic analysis  of choice
should not only identify which alternative solid waste
management  plan  is preferred but also the compara-
tive costs of other "good" alternatives. This informa-
tion assists decision makers in their search for the
best "politically acceptable" alternative.


    Faced with an array of available alternatives and
considerations, decision makers  are confronted with
the  recognition  that  although  regionalizing  solid
waste  management functions has economic  advan-
tages,  regionalization  itself gives rise to some ques-
tions:  Where should the disposal facility be located?
What is  the preferred technology?   Who should  it
serve?    How large should it  be?  Should  partici-
pating communities haul their  refuse directly to the
facility,  or through intermediate transfer  stations?
What size and where should the transfer stations be?
What  will a  system  that  meets  all the  objectives
cost?  What are good  alternatives and what will they
cost?  In  sum, what is the most economically pre-
ferred  regional system design and what are the costs
associated with changing that design?

    In order to assist those faced with these complex
issues, the U.S. Environmental Protection Agency has
sponsored  the development  of  a  computer model
called  the  Waste  Resources  Allocation  Program,
WRAP.  It specifically evaluates the economic trade-

                    How WRAP Can Help
      The decision maker.
         defines issues to be examined
         defines all processing and disposal alternatives
       WRAP provides for uniform data definition
         evaluates all options presented
         selects lowest cost regional plan
         identifies physical plan behind lowest cost solution
       The decision-maker.
          uses WRAP to generate  a set of alternative plans
         evaluates these alternative plans
          considers the economic impact of choosing  among alternatives
offs  within the  entire processing and disposal  sys-
tems, including haul costs of collection vehicles to
a disposal facility, capital  and  operating costs of
transfer  stations,  resource recovery  facilities  and
landfills, transfer haul costs, and revenues available
from materials and energy recovery. It helps to  sort
out all the various options within a specific region by
indicating  a preferred solution  that  identifies  the
minimum cost  regional solid waste management plan
that meets all the objectives determined by its users.
Use  of  the model enables officials to study and  ana-
lyze the costs  and implications  of all  available alter-


     A model is an abstract representation of a system
(which  can be a real  thing  or an idea)  that is being
studied or  examined.   Although a model  is never
more than a partial representation of reality, its use
allows one to adequately predict the effect of changes
in the system  on that system's overall  effectiveness
or cost.

     The use of models is not new to modern man.
From  the beginning  of history,  models  have  been
used to represent objects or ideas in an  effort to ex-
press meanings.    Physical  models  are  perhaps the
most familiar; however, mathematical models (models
in which  the system is represented by a set of equa-
tions which  can  be  manipulated  mathematically)
form the basis of the scientific disciplines.
     Increasingly, computerized mathematical models
 have  been used as  aids  in  management planning.
 These are simply sets of mathematical equations ex-
 pressed  or written according  to a particular set of
 rules so that  they can be processed by the computer.
 The  advent of  the  computer has proven invaluable
 in modeling,  as  it frees its users from time consuming
 and cumbersome calculations.


     WRAP is such a computer model. It can be used
as a tool by  decision makers who are seeking a  solid
waste  management   plan  that  most  economically
meets  environmental and  political  criteria.   The
model reviews information about the region and  from
this provides a minimum  cost regional solid waste
management  plan.

     A key capability of WRAP is its ability to bal-
ance  the economies  of  scale achievable through
centralization of processing  at  one location against
the additional haul costs required for centralization.
This makes  it possible to determine what levels  of
centralization make the most economic sense.
    WRAP consists  of a series of equations which
consider the sources  of solid waste generation over a
given  planning region, a set  of possible sites, and
processes to be considered at those sites, as well as
various site and process capacity constraints.  The
processes can  be transfer stations, resource recovery
processes  (including  the  extraction  of recoverable
resources  to  be  marketed),  secondary  processes
(which receive the  residue of primary processes as in-
put) and various disposal processes.  WRAP  further
considers  many   transportation  route  alternatives
from  sources of waste generation to  sites, and from
sites to sites, and  allows for site traffic constraints.

    Processing costs  are  input to WRAP so as to re-
flect the  economies  of scale available for each proc-
ess, and the revenues  from the marketing of recovered
materials.   Haul costs are included,  which increase
directly with both tonnage and travel time.

    WRAP has three  essential components:

    structure  — which assures that each alternative
          considered  is feasible in  the  sense that all
          wastes generated are entered  into  trans-
          portation, that all wastes arriving at a site
          are  processed,  that all residues generated
          are  processed  at the  site or entered into
          transportation, and  that no process ex-
          ceeds the  indicated  tonnage maxim urns;

     cost  — which assures that each  alternative is
          properly costed, including  economies  of
          scale where appropriate; and

     procedure  —  an  organized mathematical pro-
          cedure which  allows  those options  which
          improve  the   solution   to   be  separated
          from  those that make  it worse,  and in-
          dicates when the procedure  has identified
          the least cost solution.


     When  planning  a   regional   system,  decision
makers should consider  many different siting, proc-
ess, capacity and transportation alternatives.  Design-
ing  the  minimum cost plan could  involve hundreds
of  time  consuming  and  cumbersome  calculations.
The WRAP model should be  used  because it allows
its  users  to make these  calculations in a relatively
brief period of time, thereby permitting a continuous
planning  and  decision process.  The model makes it
practical to examine many more questions and alter-
natives than would be possible without its use.

     Because the model mathematically analyzes the
economic advantages and disadvantages of each of the
alternatives, it avoids the potential  errors of decision
based purely on intuition.


    To use  the  WRAP model, data and information
about  the region  are structured in a set  of model
runs. Each run examines specific issues and questions
that decision  makers wish to address.   The lowest
cost solution for each alternative being examined is
generated by the model, as well as  a regional system
plan for each  alternative.  Decision makers can then
use the model to  calculate the  incremental costs of
moving from  one alternative   to  another,  and in
particular, the costs  of moving from  less political
acceptability to greater acceptability.   In any given
planning region, for  example, WRAP can be used to

quantify the system cost difference  in  a regional
system compared with a county by county solution;
or the system  cost  impact  of the political accepta-
bility  or  technical  availability  of certain  resource
recovery or disposal processes; or the system  cost
impact  of alternative  revenues  for marketing re-
covered materials and energy.

    Each  plan  generated by  WRAP indicates what
kinds of waste disposal technologies would be  best
for the  region based  upon  differing  assumptions,
where  to  locate  the  facilities for processing  and
disposal  as well  as transfer  stations,  how  much
capacity to install at each  site, and the  transporta-
tion network to  link  the  elements of the system
together to achieve the minimum cost solution.


    Users  need  four things  to  apply the  WRAP
model:  a sense  of the kinds  of questions for which
answers are wanted; access to analytical  skills; the
use of or access to a computer; and data.
                                   • SITES
                                   TRAfJSFEZ STATIONS
Questions To Be Asked

    In  order to  sort  out the various alternatives
and options, as  well as to illuminate potential  poli-
tical issues, users  should have some feeling for the
kinds of questions  for  which they desire answers.
For example,

    •     where should  transfer stations be located?

    •     is resource recovery viable? or

    •     what is  the cost impact of locating an ele-
          ment  of the  system in one place versus

On the  other hand, time and budget should be allow-
ed to answer additional questions, for it has usually
been the case that the  first few runs in answering a
question have suggested  additional questions.

Ana ytical Skills

    Model users either  need to have, or have access
to,  persons with  analytical skills (for  example, re-
gional  planners) who are capable of examining the
situation  and  identifying  and  structuring issues
which  WRAP  will  address.   In  addition,  persons
with technical skills, who can actually use the model,
are  necessary.  The nature and extent of the skills
neeced can be determined by reading the supporting
information available about the WRAP  Model, or by
inquiring  of EPA's Systems  Management Division


    It  is  necessary to  have access to  a computer,
the  actual  size  requirement  of which may  vary
according to the  dimensions  of the problem being
addressed.    WRAP has  been  designed  to  operate
on an IBM 370/165 system.


    Two basic groups  of data are required: those
that are tailored to the specific planning region; and
those that are generally  applicable throughout the
courtry.  The former  group  must  be  provided by
the users;  the  latter  group is  available  from earlier
runs but  should  be reviewed  before use.   A brief
description  of the specific kinds of data required
is  provided here.   However,  all of these data  and
potential  sources  are described in greater  detail in
supporting volumes of the WRAP model designed
for its users.

    Data  to be provided include  estimates of waste
generation volumes, possible  sites being considered
for the location  of transfer stations,  primary  and
secoidary solid waste processing facilities, and land-
fills; data  on  the local  transportation network in
terms of transit times between the sources of waste
generation and each site, and  among sites; and esti-
mates  of revenues from the sale of recovered energy
and materials, representing local market  conditions.

    Other  data   required which  are  perhaps  the
mosl  difficult to  obtain are the costs of the various
solid  waste disposal processes being considered as
well as the estimated costs per ton-minute of trans-

porting the refuse in packer and  transfer vehicles.
The  costs of all solid waste disposal processes being
considered need  to  be  provided  as input to the


    The  WRAP model has been developed to assist
a wide range of decision  makers  who must  make
choices  concerning  the  future  direction  of solid
waste  management.   This includes  officials  within
various regional or county agencies, state agencies
which are responsible for this  function,  and city
agencies  or officials,  who are contemplating regional

    Because the model has been developed to assist
in regional solutions, it  should  not be used unless
there are large  enough geographical areas to warrant
investigation of economic tradeoffs.


    The  WRAP Model should  be  used by decision
makers  who  are  faced  with  situations  in  which
local  solid  waste  disposal options are  no  longer
available, and regional solutions  must be considered.

    For  example, the model can be used in the early
regional  planning  stages  to identify how  large the
region should  be and  which  communities  should
participate.   It can  determine  which technology is
most  appropriate  and  where   it   and subscribing
transfer  stations should  be located  to  produce the
minimum  system  cost  to the  communities.   The
model can be used to determine the economic fea-
sibility of a system proposed for the region, the eco-
nomic effects of alternative  volumes of waste, and
the effects of variations in revenues from recovered

    During the early stages of planning, data, espe-
cially  concerning  process  costs and  markets are
necessarily estimates. The quality  of the model's
solutions  are,  of course,  only as good  as the data
supplied  to it. As the planning process progresses and
better data becomes available, WRAP should be used
to verify earlier  plans or  to evaluate any changes
which might be indicated.


    The  WRAP model has been used in  Northeast
Massachusetts and Greater St. Louis, and is currently
being used in other areas.

    For   the  Commonwealth  of  Massachusetts,
the model was  applied  to  a region encompassing
63 communities in Northeast Massachusetts and New
Hampshire  in an  effort  to assist the Commonwealth
in the initial  planning stages  of a regional solid waste
management  plan.  The Commonwealth's plan em-
phasizes  the implementation  of regional  resource
recovery  systems throughout the State, and it desired
assistance in  identifying the  most efficient regional
system design for the first region.

    Under  EPA sponsorship, the model was applied
to identify  and illuminate issues in Greater St. Louis,
where the Union  Electric Co. is proposing to install
an 8,000 ton-per-day resource recovery system using
the shredded fuel process developed by them.  The
proposed  system  included  the marketing  of the
recovered fuel to  Union  Electric's power generating
stations within  Greater  St. Louis.   A local regional
planning agency, the East-West Gateway Coordinating
Council,  requested EPA  to  fund an application of
the model  to provide further insights  into  the ad-
vantages  to the communities of participating in such
a plan.


    Use of the WRAP model by the Commonwealth
of Massachusetts  provided  significant  information
concerning  the  elements and makeup of the  state's
first regional resource recovery system.

    In response to a request from five communities
in the Merrimack Valley region who  were faced with
critical   disposal  problems,   the   Commonwealth
agreed to sponsor the implementation of a regional
resource  recovery system that would  provide compre-
hensive, full scale disposal services to  those communi-
ties. Recognizing that there would be clear economic
advantages to creating a larger region, the Common-
wealth used the model to determine:

    •     Which  of  the  many technologies would
          produce the minimum cost solution?

    •     How large an area should the system serve
          in order to minimize the cost?

    •     Where  should  the facility be  located and
          what size should it be?

    •     Which  communities  should participate  in-
          transfer stations,  and where and what size
          should those transfer stations be?

    •     What  will  be the overall  system costs  of
          alternative system designs?

   - The model  indicated that with  all options avail-
able, gas pyrolysis facilities  at two sites in the region
would provide the minimum  cost solution  at $4.40
per ton.  Because  gas pyrolysis is in  the developmen-
tal stages and not available for implementation, the
model was asked to provide the "next best" solution,
and selected  sanitary landfill in six locations through-
out the  region, at an incremental cost of around  $3
per ton.  Recognizing that landfills  are  of question-
able  political  acceptability  in  Massachusetts the
model was asked  to  pick the next best system, and
selected  the dry  shredded fuel  process  at a single
location for  an incremental cost of $4 per ton over
the original solution.  (A later analysis  showed that
the markets for shredded fuel at that time were weak,
thus a different technology was finally  recommend-
ed.) The selected  system in  each case indicated which
communities  should  participate, the location and
size of transfer stations  and the secondary resource
recovery facility, as  well  as  the most economical
transportation routes for communities  to utilize  in
reaching the facility.

    The  use  of  the  model  enabled the  Common-
wealth to determine the minimum cost  regional sys-
tem design, as well  as the  incremental costs of pro-
ceeding  to  a  regional  design of  greater political
    In  the  Greater St. Louis area, the  East-West
Gateway Coordinating Council asked EPA to fund an
application of the model to assist in the resolution of
two issues of primary importance in that area.  One
was to  determine  the economic feasibility of com-
munity  participation  in a resource recovery system
proposed by Union Electric compared  to continued
landfill  operations.  The second issue concerned the
design of a  resource recovery system, e.g., what de-
sign would produce the minimum cost to the parti-
cipa its?

    Based upon the data inputs, the model solution
indicated  that the  resource  recovery  system was
indeed  a  viable,  economically  feasible solid  waste
management plan,  and was in almost  all cases the
least  cost system as compared to landfill.  The gen-
erated solution included the location  of the facilities
and transfer stations.

    The model was then asked  to provide informa-
tion relative to the incremental costs of changing that
design.  Specifically, what would be the incremental
cost of prohibiting the flow of waste  across the state
boundaries of Missouri and Illinois; of losing a parti-
cular  market or a portion  of the tonnage; and, what
would be the effect on  the regional  design and the
cost  of forcing the model to consider locating the
facility in a particular  location?

    \lthough the  cost  of each of these  solutions
did lot vary significantly, the result of these varia-
tions, both singly and together, changed the structure
of the preferred solid waste plan.  For example, pro-
hibiting  the interstate  flow  of  waste altered  the
regional configuration by locating the shredded fuel
processing   facility  farther away  from  the   urban
area, and deeper into the suburbs.

    The application  of the model provided signi-
ficant information concerning the economic viability
of resource  recovery  in  comparison  with landfill


    Examples  of the  kinds of  issues which  WRAP
can address are provided here to illustrate its capa-
bilities  and  versatility.  These examples are  drawn
from  actual model  applications  in  St.  Louis and


    The WRAP model was  used to analyze a 450
square mile area in Greater  St. Louis, encompassing
185  municipalities,  and  roughly two  and one-half
million  people, producing an  estimated  8,000 tons
per  day  of  residential,  commercial and industrial
waste.  One hundred eighty five landfills and dumps,
and  two  incinerators  currently  provide  inadequate
disposal services to  the area,  often  in violation  of
environmental  regulations.    The  Union  Electric
Company   is proposing a  large  resource  recovery
system using the shredded fuel process developed  by
the  company,  including  the marketing of the fuel
to Union  Electric's steam generating stations within
the region.

    Data  for the application was  drawn  from  an
earlier report prepared for  the  East-West  Gateway
Coordinating Council,  one of the agencies concerned
with  the  course of  solid  waste  management in the
region.  The data comprised costs of the proposed
Union Electric process, the  Bureau of Mines residue
recovery process, transfer  stations, landfills, transfer
haul and rail haul, revenues from the sale of recovered
materials  and energy,  as  well as waste generation
tonnages and possible site locations.

     In  Massachusetts,  the  Commonwealth desired
to provide solid  waste disposal  services  for  North-
eastern   Massachusetts  communities  faced   with
critical  disposal problems.   The  WRAP  model was
used  to analyze a  750 square mile  region, encom-
passing  63  communities,  with  over  one million
people.     Data for the  Massachusetts  application
included  costs  of  various  disposal  technologies,
including   pyrolysis,   dry  shredded  fuel,  landfill,
residue   recovery,  transfer   stations  and  transfer
haul, as well as waste generation tonnages and possi-
ble sites.

Is Resource Recovery Economically Viable for a
Planning Region Under Consideration? How Can
WRAP Help in Determining the Answer?

     The WRAP model was used in Greater  St. Louis
in an effort  to determine the answer to one of the
questions   facing the  region:   Is  it  economically
sensible for the region's  communities to participate
in the  proposed Union  Electric resource recovery
system?   Because  the  size of the region  under con-
sideration  was  extremely large, the  seven-county
area  and  the City  of St. Louis were divided into
29  districts, in  order to promote an  effective  and
rapid manipulation of the data.  The district bound-
aries   consolidate  smaller   subdistricts  of  similar
character.  This  classification was used  for the analy-
sis  and presentation of data  for  areas  larger than
subdistricts, but  smaller than counties.
                 GREATER  ST. LOUIS

    Estimates were  used for 1980 waste generation
tonnages  for each of the 29  districts.  Thirty-four
sites throughout the region were identified as possible
locations  of transfer stations, primary and secondary
processing facilities, and landfills.

    Two  initial  model  runs were made to  answer
the  question  of  resource recovery  viability based
upon  locally  supplied  data.   When  offered only
resource recovery as an  option (Run A), the WRAP
model  generated  a  minimum cost  regional  plan,
at a cost  of  $1.253 per ton.  When offered  landfill
as an  option, only  one-half of one percent of the
waste  flowed to  landfill, while  99.5%  entered  re-
source  recovery  processing.   Run B operated at a
cost of $1.249  per  ton, only  four tenths of a cent
less than Run A, as shown.

              U Resource Recover) A Viable Option9
        (A ( ompanson of the WRAP Model Runt, m St Louis)
A  ReM>uri.e Recovery
Landfill Seleued
B  Ljndtili Added Ji Option     1 24l>    for 400 TPD (0 57r of total)

    The model  solution indicated that the resource
recovery system proposed by St. Louis could indeed
be competitive with landfill.  The revenues for fuel
and  secondary  materials proved too  attractive to
permit a regional system that relied on landfill.

Which of  the  Many Solid Waste  Disposal Options
Is Best for a  Planning  Region in  Terms of Total

System Cost?  What Are the Effects on the Regional
System of the Unavailability or Political Unaccepta-
bility of Those Options Selected?

    Three runs  in the  application  of the WRAP
model  for   the  Commonwealth  of  Massachusetts
provided  the answers  for these questions:  Which of
several  solid waste processing  and disposal  options
(pyrolysis, refuse-derived fuel, and landfill), is best
for the region?  If the  selected option is not available,
or is  politically  unacceptable, what are the effects
on both the system cost and the regional design?

    Input data  was  prepared in a fashion similar
to that in St. Louis.  The region was divided into 13
districts with centroid and  waste generation identi-
fied in each district.   Costs of transfer stations  and
truck  haul,  possible  sites,  and distances and  times
between those sites were determined.  Costs for the
three   solid  waste  disposal  options were  input, as
well as expected revenues from the sale of recovered
products  for  the resource  recovery  technologies,
and a residue recovery process. (It should be  noted
that the residue recovery process used in the model
was that  being  planned at  that time  for the City of
Lowell, under an EPA  grant.)

     Three runs  were  made.   The model solution
indicated  that  with  all  the  options  available  the
minimum cost solution could be achieved through the
selection of  the gas  pyrolysis  technology  at two
locations within  the  63  community  region.   The
minimum  cost  solution included  a single  transfer
station,  and  the residue recovery facility at a system
cost of S4.38 per ton.
  (Options Available)

 E Transfer Stations,
   Shredded Fuel,
   Gas Pyrolysis,
   Residue Recovery,

 F Transfer Stations,
   Shredded Fuel,
   Residue Recovery.
 G Trar sfer Stations,
   Shredded Fuel,
   Residue Recovery
    Structure of
   Run Solution

Two Pyrolysis Facilities
One Transfer Station
Residue Recovery
Six Landfills
Residue Recovery

One Shredded Fuel Facility
Residue Recovery
Four Transfer Stations
    Although the model selected the pyrolysis tech-
nology  it was still in the developmental stages and
not  ready  for  implementation.    Consequently,  a
second  run  was made, and the model was  asked  to
provide the "next best"  solution.  The model selec-
ted landfill  at six locations throughout the  region at
a cost  of $7.34 per ton, or  an incremental cost  of
about S3.00 per ton.
                                                              REGONAL FACILITY

                                                            O RESIDUE RECOVERY
                                                            A TRANSFER STATION
                                                           C—1 LANDFILL

                                                          WHERE SHOULD THE ELEMENTS OF THE REGIONAL PLAN BE LOCATED
                                                                  IN ORDER TO ACHIEVE MINIMUM SYSTEM COST?
                                                                         (MASSACHUSETTS RUNS E.F&G]
     Because  landfill  disposal  is  of questionable
political acceptability  in Massachusetts, Run G was
made  asking  the  model for the next best solution.
The model determined that, given markets for the
sale of the recovered  products, the minimum cost
solution consisted of a dry shredded  fuel process in
one location, with four subscribing transfer stations
and the  residue recovery  facility.  The cost for this
system was $11.23 per ton, or an incremental cost of
roughly $4.00 per ton.

     The results of the WRAP application indicated to
the Commonwealth  which of the  many  solid waste
disposal  options would provide the minimum system
cost  wiile meeting  all applicable criteria.   Most
importantly,  the  WRAP application gave the Com-

monwealth the  incremental  dollar costs of the un-
acceptability  of another.
Where Should the Components of a Regional Solid
Waste  Management System Be Located in Order to
Achieve the  Least Cost System?  How  Large Should
They Be?  And Whom Should They Serve?

     In  the   applications  of WRAP  previously  dis-
cussed, a  variety of questions were asked.  In pro-
viding  an  answer to each, WRAP generated a system
design which comprised the best regional design that
would produce  the minimum  cost  while answering
the  specific question.   Each design  indicated where
the facilities  should be located; how large and where
the transfer stations should be; and how the system
should be  linked together.

    The optimal region design generated by WRAP
for Massachusetts is shown schematically in the figure
above.  The location and size of the system compon-
ents for each plan varies according to  which option
was  selected.   In the  regional design  in which the
gas pyrolysis technology (Run E) was  selected, one
processing facility handled 700  tons  per day, and
served  15 communities,  while  the  other, at  1500
tons per  day,  served  34 communities.  A single
transfer  station  served one community with 90
tons per day.

     Run  F  generated  a minimum cost design com-
prising six landfills, and no transfer stations.  Run G
generated  a design consisting of a single dry shredded
fuel facility  to  serve  the entire  region, with  four
transfer stations serving a  total of 34  communities.
The remaining  19 communities hauled their waste
directly to the facility.

How Can  WRAP Help in Determining  the Effect on
the Preferred Regional Design of Having More or Less
Than the Expected Volume of Tonnage?

     In both  the St. Louis and  Massachusetts appli-
cations, runs of the WRAP model were made to deter-
mine the  effect  on both the makeup of the regional
system and the overall system cost of having more or
less than the expected tonnage.

     For St.  Louis, Run E asked  the model:   What
is  the  preferred  regional design if  the private haulers
in the  region, who are largely responsible for the haul
and  disposal  of commercial waste,  do not join the
regional system? In order to determine this effect,
Run E included  only half the amount of commercial
tonnage generated  in the region.   Since commercial
tonnages tend to  be concentrated  in urban areas,
the model generated a solution which caused primary
processing to be relocated toward the suburbs.  The
cost  impact  of  this  change  was  relatively  small.
Based upon locally supplied data, the model  gener-
ated  a  system cost of $1.75  per ton,  or an incre-
mental  cost of $.31  per  ton over the base case for
that solution.
                 1ST LOUIS RUN E]
         RUN A I
       RUN E
                         REGIONAL SYSTEM COST  SI 75 TON
    Runs  H  and  I  were  made  to determine  the
effects of  doubling the amount of tonnage in  the
region on both the design generated when all options
were  available (Run G).  The purpose of these runs
was to determine how sensitive the model  solution
was to radical changes in tonnage.

    Run H generated a regional configuration that
was identical to  that of Run E but with  two addi-
tional transfer stations.  The effect on the system
cost  was  a decrease  from  $4.38 per  ton to  $3.45
per ton.

    Run  I generated a somewhat different design
from  that generated by the earlier Run G.  The addi-
tion of twice the amount of tonnage caused a reloca-
tion of the shredded fuel facility to a more northerly
location, four  transfer stations in slightly different
locations,  and the  residue recovery facility in  the
northeastern part of the region.  As in Run H, the sys-
tem  cost  decreased from  $11.23 per  ton  to $8.47
per ton.
       Comparison of Massachusetts Runs E, G, H and I
 Run                Structure             Solution Cost
  E         All options available               $4.38/ton

  G         Only shredded fuel available          S11.23/ton

  H         Doubled tonnage,                 $3.45/ton
            all options available

  I          Doubled tonnage,                 $8.47/ton
            only shredded fuel available

    Use of the WRAP model in both Massachusetts
and St. Louis provided its users with valuable infor-
mation concerning the most economically preferred
solution for those regions.


    Comprehensive information that  describes and
documents the use of the WRAP model is available.
This information  comprises  three  documents:   A
User's Guide; A Programmer's  Manual;  and a full
documentation of the model applications made for

The User's Guide (127 Pages)

    This  guide  is addressed  to the individual or
group of individuals  who are intending  to use the
WRAP model to assist in the  decision-making proc-
ess.  The  model is  fully  described in terms of its
makeup and equation  structure to familiarize the
users  with its capabilities.   The  guide  contains a
full description  of the kinds of data required for its
use, as well as how to prepare and utilize those data
and  how  to interpret  outputs.  Examples of pre-
pared data inputs are provided,  as well as a guide to
the design and operation of the model.
The Programmer's Manual (345 Pages)

    Addressed  to  the data processing individual,
this  manual  provides information about how  the
program is actually  applied and how  it is run.  An
overview  of how the  computer program  is set  up,
and how information  inside the program is stored
is provided.

Operational and Exercise Runs (222 Pages)

    This includes a full documentation of the model
applications  made for EPA in St. Louis and Massa-
chusetts.   It contains a detailed  description  of all
data inputs and outputs  used, where these were
obtained, and the assumptions used.  The  document
is  addressed to any individual who desires to ana-
lyze and  review the actual model application in an
effort to more fully understand its capabilities.


    For further information about the WRAP model,
call or write:

        Office of Solid Waste Management
       U.S. Environmental Protection  Agency
                401 M Street S.W.
             Washington, D.C. 20460
                at (202) 755-9125