A Model for
        Regional Solid Waste
        Management Planning
    This report ^^MBpwas prepared for the Office of Solid Waste
           under contract No. 68-01-2976
For sale by the Superintendent ot 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-
    Local 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.
                                                               THE ECONOMIC TRADEOFF IN REGIONAL DESIGN
                                                         COST PER
                                                          TON OF
                      PROCESSING COST
                                                                                         TRANSPORTATION COST
                                                                   O SIZE OF REGION
                                                                   O GROSS TONNAGE
                                                                   O NUMBER OF PARTICIPANT COMMUNITIES
                                                            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  maximums;

    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.
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.

Analytical 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
needed 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
country.  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
secondary 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
most  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-

    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?

    Although the  cost  of each of these solutions
did not 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  SI.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.

               h Resource Recover A Vuble Opium1'
         (A Cimtpjrisun nt the WRAP Model Runs 111 St Louis)
A  Resource Recover}

li  L..mlhH Atlikdjs Option
                    I 249
                               Ljndtil] Selected

                           to, 400TPDIO S", ol totjl)
    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 $4.38  per ton.
  (Options Available)

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

 F Transfer Stations,
   Shredded Fuel,
   Residue Recovery.
 G Transfer 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 $3.00 per ton.
                                                            O RESIDUE RECOVERY

                                                            A TRANSFER STATION
                                                          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  while 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.
                 (ST LOUIS RUN E]
         RUN Al
                                RUN E
                         ONE-HALF COMMERCIAL TONNAGE
                         REGIONAL SYSTEM COST  SI 7S TON
    Runs  H  and  1  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

G         Only shredded fuel available

H         Doubled tonnage,
          all options available

I          Doubled tonnage,
          only shredded fuel available

                                          Sll 23/ton


                                          $8 47/ton

    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


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