PB-236 543
A STUDY OF PNEUMATIC SOLID WASTE COLLECTION SYSTEMS
AS EMPLOYED IN HOSPITALS
ROSS HOFMANN, ASSOCIATES
PREPARED FOR
ENVIRONMENTAL PROTECTION AGENCY
1974
DISTRIBUTED BY:
National Technical Information Service
U. S. DEPARTMENT OF COMMERCE
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BIBLIOGRAPHIC DATA
SHEET
lii Ir and Sulu ulc
1. Report No.
EPAZ*i3Q/SW- 7tic
PB 236 543
l\ Study of PNEUMATIC SOLID VIASTE COLLECTION SYSTEMS
As Employed in Hospitals
5-.Report Date
1974
6,
Autliorfs )
Ross Hofmann, Associates
8< Performing Organization Kept.
No.
Performing Organization Name and Address
Ross Hofmann, Associates
2908 Salzedo
Coral Gables, Florida 33134
10. Project/Task/Work Unit No.
11. Contract /Grant No.
EPA-68-03-0300
12. Sponsoring Organization Name and Address
U. S. Environmental Protection Agency
Office of Solid Waste Management Programs
Washington, D. C, 20460
13. Type of Report & Period
Covered
Final
14.
15. Supplementary Notes
16. Abstracts
This report summarizes a study that assesses the technical and economic feasibility
of pneumatically transporting hospital solid waste. Three hosnitals employing
pneumatic collection systems were surveyed. Variations in systems design and
utilization were investigated and reported upon. Cost information was accumulated
and analyzed for each hospital. Operational, oerformance and environmental analyses
were performed for all systens involved. This report should be helpful to hospitals
already employing pneumatic systems from the standpoint of ootimizing operating
procedures and should be further helpful for new installations from a design
standpoint.
17. Key Words and Document Analysis. 17o. Descriptors
* Pneumatic Conveyors, * Hospital Solid Wastes, * Hand Cart Systems
17b. Identifiers,Open-Ended Terms
Storage-Collection of Waste, Hospital Solid Wastes, Vacuum Collection Systens
17c. COSATI Field/Croup
18. Availability Statement
19. Security f lass (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
|2I. No. of Pages
I --» -»
USCOMM-DC 14952-P72
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A STUDY OF PNEUMATIC SOLID WASTE COLLECTION SYSTEMS
AS EMPLOYED IN HOSPITALS
'This final report (SW-?5c) describes uork perfcrr.ed
for the Federal solid vacte -nanacenent r.r>oacans under contrast ;1o, 68-03-0300
to ROSS HOFMANN, ASSOC.
md is reproduced a,?- received fror, the contractor
U.S. ENVIRONMENTAL PROTECTION AGENCY
1974
i a.
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This report as submitted*by the grantee or contractor has not been
technically reviewed by the U.S. Environmental Protection Agency (EPA).
Publication does not signify that the contents necessarily reflect the
v4ews and policies of- EPA». nor does mention of cor™iercial products
constitute endorsement or recommendation for use by the U.S. Government
An environmental protection publication (SW-75c) in the solid waste
management series.
n
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FOREWORD
The problen of solid waste nanagerent in hosoitals has been
and continues to be of major concern to hosnital administrators.
The nature of the waste requires that snecial consideration be given
to handling, processing, and disposal. The oast increase in the use
of disposables in place of reusables has increased ner patient solid
waste generation levels to new highs. The cost of hosnital solid waste
management adds to other already high hospital systems costs. In
light of these problems, careful consideration is being given to
devising systems which are effective from both a cost and an environ-
mental point of view.
This report examines pneumatic transoort of solid wastes, a
method which appears to offer both environmental and economic benefit
when properly utilized. It is the purpose of this rerort to discuss
the state of the art of pneumatic trarsnort of hospital solid waste
and to make broad recommendations to improve systems use and desinn.
Although, there have been some editorial revisions, this publication
is essentially as delivered from the contractor.
Harvey W. Rogers, of the Systems Management Division of OSWMP,
served as project officer for this contract effort.
--ARSEM J. DARNAY
Deputy .Assistant Administrator
Solid Waste Manaaement
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INDEX
Sunmary of Findings
Introduction 1
i. Solid Waste Management in Hospitals 4
The Size bf the Hospital Community 5
The Impact of Disposables -J
Quantities of Hospital Waste 9
Environmental Problems from Hospital Wastes 11
Infectious Wastes H
Hazardous Wastes 16
Plastics IB
Hospital Waste Management Patterns 21
Personnel Utilization 22
The Use of Containers in Waste Handling 23
The Elements of the Solid Waste System 24
Automation and ffechattiiSation in Waste Management 25
2.. Architectural Design Influences on Transport Systems 28
Planning Solid Waste transport Systems 28
The Vertical Chute-Pneumatic Tube System for Solid
Waste Transport ?2
Sizing the System 33
Vertical Chutes 33
Loading Station? 34
Chute Loading Rooms 36
Fan Room >7
Control Center 37
Collector Boxes 38
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2. Architectural Design Influences on Transport Systems (Cont.)
Structural Strengths for Installing Equipment 39
General Considerations 39
3. Design and Construction Considerations for Pneumatic
Transport Systems 41
Single Tube Full Vacuum Systems 41
Multiple Loading Full Vacuum Systems 44
Double Tube Full Vacuum Systems 45
Gravity Chutes to Vacuum Systems 47
Sizing of the Chutes and Tube 51
Strength of the Chutes and Tube 54
Fire Dampers 59
Tube and Chute Hanging Methods 61
System Coatings and Abrasion 61
Diverter Valves 62
Collector Boxes 63
The Fan Room 66
Filters 67
Sound Attenuators 68
Relief Valves 69
Feed Air 69
Compressed Air System 70
Roof Air Inlets and Dampers 70
Sprinkler Systems 71
Loading Stations 71
Clean Out Ports 72
Control Systems 73
Supervisory Panels and Alarm Systems 74
Cycling Times in Pneumatic Systems 75
4. Final Reduction and Off-Site Removal 78
Volume Reduction 79
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£. Final Reduction and Off-Site Removal (Cent.)
Cleanliness in the Central Waste Collection Room 80
Compactors 81
Dry Grinders, Mills, and Hoggs 84
Incineration 85
Off-Site Hauling Vehicles 93
Sanitary Landfills 94
Salvage, Recycling, and Resource Recovery 95
§. Description of the Survey Hospitals 98
St. Mary's Hospital, Duluth, Minnesota 98
Veterans Administration Hospital, San Diego, California 104
Martin Luther King, Jr. Hospital, Los Angeles, California 110
£. Quantities and Types of Hospital Solid Waste 115
Total Waste Generated by the Survey Hospitals 115
Ratios of Waste to Hospital Population Segments and
Utilization 116
Types of Waste Transported by Band Cart 120
Generation Points and Quantities of Waste Transported
by Cart 126
Comparisons of System Utilization
Cart Hauling Versus Pneumatic Transport 130
Quantities of Waste Transported by Pneumatic Tube 132
The Sizing of Unit Loads 132
Daily Quantities Transported 133
Floor Compactors 135
Chute Loading Hours and Volumes 135
The Interfacing of Soiled Laundry and Waste in
the Pneumatic System 142
Waste Generation Points and Volumes 144
7. Operational and Performance Analysis 147
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8. Codes and Regulations 154
9. Environmental Testing 161
Sound Level Readings 161
Odor Detection 174
The Problems Created by Aerosols 177
Housekeeping Practices 178
Bacteriological Testing 180
10. Economics of Hospital Waste Management 192
Capital Costs of the Transport System 192
Capital Costs of Interfaced Equipment 193
Operating Costs of the Pneumatic System 194
Operating Costs of Interfaced Systems 194
Division of Fixed Costs Between Waste and Laundry
Transport 195
Cost Analyses 196
St. Mary's Hospital 196
Veterans Administration Hospital 208
Martin Luther King, Jr. Hospital 220
11. Economic Feasibility of Pneumatic Solid Waste Transport
Systems 233
12. System Ratings and Comparative Analysis 241
Appendix
Glossary of Terms
IV
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SUJWARY OF FINDINGS
1. In an effort to reduce operating coats and improve efficiency in the
transportation of solid waste, over 160 American hospitals have in-
, or contracted for, pneumatic tube transport systems. Approximately
3fltOs additional hospitals axe currently investigating the possible advantages
0$ totalling such a system.
Z. In the majority of such installations, the basic designing of the
sysJ&CKt has been performed by system vendors, as to type of system to be
used* number of stations, length of run, speed of operation, full-vacuum or
gpsviifcyrto-vacuum, single or multiple bag loading, mechanical and electrical
eleven t-s, safety devices, structural strengths, and location of components;
retche?' than by independent, professional consultants with in-depth experience
in such systems.
3v Iti very few cases-have detailed feasibility studies been performed
on a* professional level before- the decision has been made to install such
As a result, the true*-economic savings, or the additional operating
have be«n unknown by the hospital administration until as long as two
after the systems have been in operation.
4» The capital costs of?such installed systems have increased considera-
over the past 10 years with- some of the current installations amounting to
over, $750,000.
5~, The installed systems are not being used to the full extent practi-
cable* by many hospitals and much of the solid waste is being hand carted
aceund the pneumatic transport system. With under-utilization, the potential
operational savings are seriously reduced.
6* Due to this under-utilization of the systems in the hospitals sur-
veyed.in this study, none were-saving enough labor expense to recapture the
capital investment in the system; However, if utilization is increased to the
lew*tSireocmmended in this report, the investment could be recaptured on a
basis by labor savings in each of the three hospitals, when compared.
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to costs of hand hauling all wastes by the more conventional cart method.
7. The reasons for under-utilization are many and varied:
a. System mechanical failures and high maintenance factors.
b. Limitations in the size of tube diameter and system power, and
the consequent size of load the system will handle.
c. Management decisions in individual hospitals that certain items
will not be transported through the system (such as metal cans,
glass bottles, and potentially infectious materials) for fear of
breakage, noise, contamination, or damage to the system.
d. Feelings on the part of management that hand carting of waste
materials can be done more efficiently, due to the generating
points of the materials versus the configuration and loading
stations of the pneumatic system.
e. The preference of management for hand cart waste collection
methods in many areas as a more efficient method for clearing
the floors.
f. The hours of operation permitted the pneumatic system.
8. Maintenance costs for such systems have proven to be high, due to a
combination of design and construction weaknesses and overloading or improper
loading of the system by operating personnel.
9. The efficiency and speed of operation of the pneumatic transport
system varies extensively between the designs of the various vendors. The
gravity-to-vacuum, heavy-wall, multiple bag systems, while more expensive to
purchase and install, are superior from a design and construction viewpoint;
operate more efficiently; handle far larger loads per hour; and have the low-
est operating costs. The weakest and most inefficient systems are the thin
wall, single bag, full-vacuum systems; particularly where a single tube and
suction fan handles both solid waste and soiled laundry.
10. Virtually all such transport systems are designed to accept waste
in a bagged condition. Bag breakage or ripping presents a serious problem
during transport, due in many instances to poor system design or construction.
With all but the heavy-wall, gravity-to-vacuum systems, loose waste presents
operational problems. Bagging of all waste has proven expensive. As
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plastic bags are normally used, the increasing scarcity of these
may present operational problems in the future.
From the environmental aspects, all such pneumatic systems are an
over the straight gravity chutes, or hand hauling methods, for
transporting solid waste. Mien the collector boxes at the end of the trans-
&$>£ Hne are cloee-conneeted to attrition mills or compactors, the
benefits are further increased.
The major environment a}, weaknesses in the pneumatic tube systems,
they are operating properly, involve the collector boxes at the end
the tube, the fan rooms, and the filtration of the effluent air from the
With bagged waste and the speed of bag travel, the vacuum tubes appear
£g be relatively self-cleaning,
4.3, The sound levels of the systems while in operation are relatively low
and do not appear to be annoying to patients. Odor levels are not objection-
The limited bacteriological testing that has been performed did not
pathogens of any significant level. The systems appear safe to use
operator viewpoint. Fire safety codes are satisfied.
. User acceptance varied considerably between hospitals in view of
and maintenance problems experienced. Amounts of waste trans-
by the pneumatic system ranged from a low of 25.1% to 38.8% to 60.3%
the three hospitals, with the balance of the waste hand cart trans-
It is possible to both modify and expand all three of the systems
particularly in the collection system at the end of the line, or if
wings are constructed.
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INTRODUCTION
In June 1973, Ross Hofmann, Associates was employed by the Environmental
Protection Agency to study solid waste management practices in hospitals.
Particular emphasis was to be placed on pneumatic transport systems for the
moving of solid waste through a hospital complex. Three hospitals were se-
lected for in-depth study of their pneumatic transport systems: St. Mary's
Hospital in Duluth, Minnesota; Martin Luther King, Jr. Hospital in Los Angeles,
California; and the Veterans Administration Hospital in San Diego, California.
The following report was a result of the Consultant's work. It has been
divided into two main sections. The first section covers the principal fac-
tors involving solid waste management in hospitals. It describes the magni-
tude of hospital solid waste and the environmental effects from it; the various
management methods that are used; and the problems that are encountered as a
result of both internal and external constraints. It describes in detail the
equipment that is used in hospitals for pneumatic transport systems and for
systems of final reduction and off-site removal of solid waste. This material
is covered in Chapters 1 through A and sets the background for any study of
solid waste management and transport within a general hospital.
The second section, covered by Chapters 5 through 12, concentrates pri-
marily on the three hospitals that were surveyed and the problems they have
encountered with the use of pneumatic solid waste transport systems. It anal-
yzes the hospitals, their architecture, the systems they employ, the loads of
waste they must handle; and it analyzes the performance of their systems,
ranging from costs to environmental affects. The conclusion of this section
rates and compares the systems the three survey hospitals are using.
The delivery of health care has now become the largest retail industry in
America. Hospital operating costs account for approximately one-third of this
enormous expenditure. Labor payrolls account for almost 65 percent of total
hospital expenses, and hospitals are turning increasingly to methods for labor
reduction, including automation and mechanization. In the management and
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fo'll 6i hospital solid waste, mechanization is a fairly recent deveiop-
,* w'ijth' pneumatic tube ay£tefis the method that has attracted the most in-
tffttL
principle of a pneumatic tube systeia for the transmission of solid
16 over 50 years old. The use of large diameter tubes (over 14 in,
aiameter) for this p^rp'bse dates back to 1941, and the designs involve
iuliy pneumatic or gikvitjf trarfsfer in vertical chutes, combined with
fi'neumatic trinsier ih hdfiztinta'l aiid rising runs. In all cases, a suc-
fHnciple rattier than a prilling (at blowing) principle has been used.
first sUch syitfcias Will werfe installed in hospitals in the United
werfe an outgrowth of Syfeteins originally developed for moving linens in
laundries. Only iihetis, not solid waste, were moved pneumatically
in hospitals. The fir^fc such system for handling solid waste in a
tai was not installed until the midsixties. While many advances for
tube transfer have bfeen designed in Europe, only one such system,
originally in Sweden for use in solid waste collection, has been in-
in U.S. hospitals to date.
M Is usually thfe casb with system designs that have been developed for
Hild and adapted to ariothet fleld^ the conversion of large diameter pneu-
Mllfc lube systems from laundry and industrial use into a structure and oper-
brgariization as cotaplek as a modern U.S. hospital has presented innum-
problems: to the engineers and architects, the manufacturers, and the
personnel. The economic feasibility of many systems that have been
or contracted for hais not yet been proven. Users of certain instal-
have registered serious complaints with the authors of this Report as
to ^£1 technical merits of such systems.
quantity oE such systems installed to date in hospitals ie still
, but Is growing. Sixty-otte are claimed by ECI Air-Flyte Corporation,
Ifc additional 68 on order; 23 In total installed and on order by Trans-
iy^Vems; eight by Envirogehlcs Company; two by American Sterilizer Company;
feii by other firms. It is felt that an in-depth study, under the sponsor-
l&lp1 Bf the United States Government, will greatly contribute to further know-
1bf these systems in View of the limited research published to date.
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In the Report that follows, we have analyzed hospital solid waste manage-
ment and pneumatic transport systems from several viewpoints and with separate
disciplines. At first glance, these separate evaluations may appear to over-
lap, or even duplicate each other. We believe that this is not the case, and
that each evaluation interfaces with the next one in a logical progression, and
that the data assembled by one discipline or phase is essential to the next.
Each of the three pneumatic solid waste transport systems studied handles
both solid waste and soiled laundry. Therefore, there is of necessity an in-
teraction between these two types of materials in the complete system, when a
common tube is utilized for both materials, and a possible interaction when
separate tubes and a common suction fan are used. Although many of the details
of laundry removal were not studied, since this effort was intended to address
only solid waste management practices in hospitals, the interaction and impact
of the linen removal system on the solid waste removal system was analyzed,
evaluated, and the results included in this Report.
With continually rising operational costs in hospitals, coupled with the
increasingly serious environmental problems in solid waste management, consid-
erable interest in the results of the study have been expressed to the research
team by hospital personnel in various parts of the country, by governmental
agencies, and by the vendors of solid waste management equipment. It is hoped
that the data given in the Report will prove useful in assisting hospitals in
solving these problems, as well as indicating some of the areas in which fur-
ther in-depth research may produce beneficial results and guide lines.
To obtain the background data covered in the first four chapters of this
report, over 100 medium to large size hospitals have been researched by the
survey team, in addition to the three institutions that are described in depth.
We would like to express our appreciation to the administration and staffs of
all the hospitals who cooperated so completely in the investigations of their
solid waste management systems, and to the Project Director and Staff Engineers
of the Office of Solid Waste Management Programs, U.S. Environmental Protection
Agency, whose constructive criticism and guidance was invaluable in the prep-
aration of this Report.
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-SOLID WASTE MANAGEMENT IN HOSPITALS
Over the past 20 years, various surveys have been conducted and articles
Jiaye been published on the amount and types of solid waste being generated by
hij|fp4.tals. Unfortunately, a review of this material, which is quite limitedf
indicates a certain amount of disagreement among the researchers as to the
magnitude of the problem. There is not a firm consensus of opinion as to the
amount of solid waste generated by hospitals, which departments generate how
much, and the make-up of the waste. Most surveys have measured the solid
WfSte in terms of weight, in pounds. The measurements have been limited
usually to the total weights generated by a relatively few hospitals. The
u*ual procedure has been, then, to divide the patient census of the hospital
i-ntp the total weight of waste recorded and to arrive at a figure of "X"
pounds "per patient day" as the critical factor in solid waste analysis. The
cube pr volume of the waste, which is equally important in designing solid
waste management systems, does not seem to have been recorded in most surveys.
It is for this reason, probably, that figures have varied considerably
between hospitals. Solid waste is generated by people, by the activities in
which people are engaged, and is affected by the size and complexity of the
building in which the activities take place. "People," in a hospital setting,
includes much more than patients. It must include all the staff and all the
visitors. Hospitals do not staff on an identical basis. The ratio of staff
£o patients varies as much as 50 percent between hospitals, depending on the
work patterns and the level of efficiency.
Hospitals do not perform identical work loads per patient. One may have
the bulk of its cases as minimal care. Another may be engaged in very sophis-
ticated and intensive care. Another may have heavy teaching and/or research
Activities and large research laboratories and animal quarters. Another may
have thousands of outpatient and emergency visits annually. One may be crowd-
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ed with visitors, another extremely light in this respect.
Hospitals with identical patient census figures vary somewhat in size and
architectural layout. Theoretically, this should not affect the solid waste
load generated if waste comes strictly from "people activities." For some
reason (that may be from attitudes on the part of staff and visitors), archi-
tectural design affects the waste generated to some degree.
THE SIZE OF THE HOSPITAL COMMUNITY
In attempting to assess the impact on the United States of the solid waste
load generated by all hospitals, a review of the industry as a whole, and its
work load, reveals some interesting facts. Hospitals represent a major sector
of the so-called "health care" industry. By 1973, it is estimated that Ameri-
can health care expenditures had risen to $94.1 billion, surpassing education
as the largest service industry. Hospital care costs have reached $36.2
billion. Sales by manufacturers to the health care industry are estimated to
be $3 billion.2
However, the sheer quantity of acute medical care, rated by average num-
ber of inpatients staying in hospitals, has not changed substantially in the
past 20 years, as can be seen from a review of the statistics published by the
American Hospital Association. The number of hospitals has increased 7 percent.
A.H.A. registered hospitals in 1955 numbered 6,596; a high point of 7,172 was
3
reached in 1967; and by 1972 this had declined to 7,061.
The number of available beds actually has declined. With 1,604,000 in
1955, by 1965 this had increased to 1,704,000, and dropped to 1,550,000 by
1972.4
Average daily patient census has fallen as well. In 1955 it was calcu-
lated to be 1,363,000, rising to 1,430,000 in 1963, and falling by 1972 to
1,209,000, the lowest since the late 1940's. Hospital personnel looking after
these fewer patients has more than doubled over this period, rising from
1,301,000 in 1955 to 2,671,000 by 1972.5
A similar rise has been seen in the number of admissions, a statistic
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that has had a direct connection to cleaning rooms of waste to prepare for new
patients, and to the number of patients and visitors going through the system,
In 1955, 21,073,000 patients were admitted to hospitals. The figure shows a
regular increase each year, with 33,265,000 patients admitted annually for
1972. A similar increase in activity is seen in annual number of outpatient
visits, which have Increased from 99,382,000 in 1962 to 219,182,000 by 1972.
It has been estimated that since 1954 the total solid waste load of all
hospitals combined has increased 350 percent in the United States. Admissions
have increased only 57 percent; outpatient visits by 120 percent; and staff by
105 percent. Other factors obviously have increased the solid waste output.
Moft administrators feel that the bulk of the increase has come from the
quantity and type of care rendered. When inflation is removed as a contribut-
ing factor, this would appear to be the case. Care and treatment of hospital
patients has become more complex; the number of procedures, injections, I. V.'Sj
treatments, and medications given the average patient has risen geometrically in
20 y«*ir». Each procedure leaves a residue of solid waste to be disposed of.
THE IMPACT OF DISPOSABLES
Probably the greatest effect on the solid waste load generated by hospi-
tals comes from the use of paper, foil, glass, and plastic "disposable" pro-
ducts, as against reprocessing items for further use. Disposables range in
nodical items from syringes and hypodermic needles, to surgical dressings and
complete operating room patient drapes, to entire bedside sets of basins, cupss
and pans. They include the containers for entire meals when the dietary de-
partment has switched to "convenience" foods. And they include tremendous
quantities of paper containers from vending machines that hospitals have in-
stailed in snack bars. They include the millions of plastic bags used in a
year fco line waste baskets and trash cans and to transport waste. All of these
iteas: are designed to be used once and thrown away.
Not only do the products add enormously to the warehousing and solid waste
problems; all of them are packaged in further quantities of plastic and paper,
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and the packaging has become much more elaborate as each year passes, in order
to increase the eye appeal and saleability of the product. It is currently
estimated that the packaging of the disposable products adds a solid waste load
that exceeds that of the products themselves.
The phenomenon of packaged disposables is an outgrowth of consumer mer-
chandising of the thousands of items we buy in drug stores, super markets, and
variety stores. The theory was originally sold to hospitals by a few large
hospital supply dealers on the basis that they would save the hospital process-
ing labor and therefore operating cost. The hospitals, always pressed for capi-
tal funds to purchase processing equipment, and able to obtain operating dollars
by raising rates to patients and third party reimbursers, welcomed the dispos-
ables with open arms. Unfortunately, it now has been discovered that, after
approximately 18 years of intensive merchandising of these products, many hos-
pitals actually have experienced a net increase in personnel due to the number
of staff needed to store, issue, and inventory the disposables.
The trend toward disposable versions of hospital products started with
those items that were the most difficult to clean, package, sterilize, and
maintain in a reusable version; while at the same time offering possibilities
of an extremely low cost throw-away substitute. The first items were hypoder-
mic needles, syringes, and tubing of various types. These products were fol-
lowed quickly by "sharps" (cutting blades), laboratory petri dishes and slides,
patient bedside utensils, food service settings, I.V. and topical solution
administration sets, surgical and examining gloves, surgical trays and sets
for O.R. and the floors, surgical drapes and clothing, and even bed sheets.
From 1973 figures that are based on reports to the Department of Commerce
and published by trade magazines for the surgical and hospital supply industry,
the enormous production of disposable medical and surgical supplies in the
United States can be seen. The dollar totals are based on manufacturers'
selling prices. The cost to the consumer would be approximately double these
figures (Table 1).
In addition to the items made from plastics, textiles, glass, and metal
by the hospital supply manufacturers, there are the millions of bottles of ir-
rigating and intravenous solutions in glass or plastic, as well as the
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packaged "unit dose" medications, supplied by the pharmaceutical manufacturers,
in plastic, paper, and foil, which are purchased weekly by the hospitals,
The average disposable product is relatively low priced. To give an idea
odE the enormous volume of solid waste they have created, we find that the annual
.sale of disposable products to hospitals has increased by approximately $700
Q
million in 18 years. If we convert this huge annual dollar purchase into
pounds and cubic volume, we find that by 1973, disposables had more than
doubled the solid waste load in American hospitals.
TABLE 1
HEDICAL AND SURGICAL SUPPLIES
Disposable Product 1973 Sales Volume at Manufacturing Level
needles, disposable $ 80,400,000
flypodermic needles, "reusable" 7,100,000
Syringes, plastic 37,500,000
Syriages, other 51,300,000
Dressings, bandages 76,600,000
Adhesive plaster and self-adhering bandages 158,300,000
Surgical and medical gauze 8,900,000
Cotton balls and cotton wool 30,500,000
Sponges, pads, other dressings 104,200,000
Sutures 136,300,000
Transfusion and blood donor supplies 85,000,000
Another factor that has added to the solid waste load, to a lesser extent,
concerns the information systems that have mushroomed in hospitals. Use of
paper in all shades and colors, often with disposable interleafed carbons, ft
simple requisitions, to photocopies of memos, letters, and reports, to compute:
print-outs, has grown by almost 500 percent in hospitals since 1950.
om
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QUANTITIES OF HOSPITAL WASTE
Many statements have been made concerning the abnormally large quantity
of solid wastes that hospitals generate compared to other institutions, to
office and commercial buildings, and to residential complexes. A hospital is
a community in itself; with a total population made up of patients, staff, and
visitors. Hence, comparisons should be made between the hospital as a com-
munity, and a residential complex of similar size, to determine how valid has
been the criticism that the hospital generates a far larger waste quantity
than does a residential community of equal size.
The 1968 National Survey of Community Solid Waste Practices determined
that residential complexes generate approximately 3.0 pounds, or 0.53 cubic
feet, of waste daily per capita occupancy (or resident). It has been estima-
ted that the average density of this raw waste is 170 pounds per cubic yard, or
6.3 pounds per cubic foot. (Compared with the average of hospital raw waste,
as we shall see from figures given later, this is extremely dense.) This
waste includes yard cuttings and trash, as well as all waste generated indoors.
It has also been estimated that between 1968 and 1974, residential waste
has increased approximately 4 percent per year. If this holds, then currently
residences are generating an average of 3.7 pounds per resident. This would
be made up of yard cuttings and outside waste amounting to 0.8 pounds and a
balance from building interiors of 2.9 pounds. The interior waste, which
would be comparable to that generated by a hospital in this current study,
can be defined, using the classifications issued by the American Public Works
Association (APWA), as "garbage" and "rubbish or mixed refuse." The make-up
would be 0.5 pounds of "garbage" (waste generated in the preparation, cooking,
and serving of food) and 2.4 pounds of "rubbish or mixed refuse" (paper, card-
board, cartons; wood, boxes, excelsior; plastics; rags, cloth, bedding;
leather; rubber; metals, tin cans, foil; dirt and dust; glass, bottles; stones,
brick, ceramic, crockery; and other mineral products).
When we refer to "solid waste" in hospitals in the present study, we mean
exactly that. Studies have been made in this field in which "soiled reusables"
(such as soiled laundry, soiled utensils and dishes, or soiled patient items
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from bedpans to treatment equipment) were included in the total waste. We do
not believe an item can be classified as "waste" that will be cleaned, and
possibly sanitized or sterilized, and then reissued for further use. "Waste,"
for the purpose of this study, is material that will no longer be used, but
will be discarded, presumably moved off-site, and presumably will be destroyed
(or at least drastically modified in a recycling process). The definition of
"soiid" is that it has insufficient liquid content to be free flowing at room
temperature.
The exact quantity of solid wastes being generated by tine 7,061 A.H.A.
registered hospitals in 1974 has been a matter of considerable discussion and
disagreement among researchers. Surveys have been limited in any study to less
than a dozen hospitals. Different surveys have included or omitted various
materials in their definition of "hospital solid waste" and most comparisons
have been of the "apples to orangas" type.
The research team that performed the present study has reviewed, to the
best of our knowledge, virtually every article that has been published in tech-
nical journals on this subject over the past ten years and has reviewed copies
of several studies, both published and unpublished, that have been performed
by governmental agencies, hospital personnel, independent researchers, and
other consulting groups.
From this material, we can at least state that the general consensus of
opinion is that during the last 20 years hospital solid waste has experienced
over a threefold increase. Various surveys that have been made would indicate.
that in 1950 hospitals generated approximately three pounds of solid waste
per day for each of the 1,253,000 inpatients being cared for, or a total of
3,740,000 pounds per day. Continuing research over the years on the growth
of the hospital solid waste load would indicate that the current figure is
over 10.0 pounds of solid waste for each of the 1,209,000 inpatients. A total
current waste load of 12,000,000 pounds for all of America's hospitals appears
to be a reasonable figure from the information that is available.
Viewing hospitals as a community, consisting of inpatients, outpatients,
staff, and visitors, the permanent 24-hour population in 1974, exclusive of
visitors, would total 4,600,000 people. This would mean that the hospital in-
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dustry is generating over 2.6 pounds of solid waste for each member of the
hospital community. This is not too far from the current estimate of 2.9
pounds per resident for interior waste from other communities.
ENVIRONMENTAL PROBLEMS FROM HOSPITAL WASTES
INFECTIOUS WASTES
Solid wastes generated by hospitals are not in exactly the same category
as those generated by homes or other dwelling units. While the total of hos-
pital solid waste appears to be only in the neighborhood of 6,000 tons per
day, and therefore less than 2 percent of the total solid waste load of the
nation, from a biological hazard viewpoint, hospital wastes contain a certain
amount of materials not normally found in other institutional or home wastes.
In any discussion of biological hazards, the words "concentration" and
"dilution" immediately arise. The spread of disease among humans is caused
by contact between the human system and the various bacteria or viruses that
are inimicable to the system. This contact may be by direct touch or through
the air, the water, or the soil. If the bacteria or viruses are diluted in a
large field, the chances of entering and affecting the human host are consider-
ably lessened. If they are both virulent and concentrated, the chances for
spread of disease are strengthened.
Some investigators have stated that the type and concentration of bac-
teria and viruses found in hospital solid waste are little different from that
found in the wastes generated from dwelling units, offices, factories, and
other institutions of this country. Other researchers have given a completely
opposite view and stated that hospital wastes may be potentially dangerous to the
environment due to their "infectious" content. Unfortunately, the very few
surveys that have been made (our own included) are inconclusive. Up to the
present, no large-scale surveys have been made—either "in-house" or off-site
at landfills—to prove or disprove the biological hazards of hospital wastes.
Theoretically, the difference between the biological hazards of waste
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generated in hospitals, with their population of "sick" people, and the waste
generated by dwelling units and other buildings that are occupied basically by
'Veil" people, lies in the concentration factor. A proportion of the waste
materials generated by hospitals in the treatment of patients has been exposed
directly or indirectly to various bacteria in a fairly concentrated form. From
2 to 8 percent of hospital wastes consist of such materials as: dressings for
wounds, incisions, and burns; plaster casts; infectious laboratory samples;
bacteriological cultures and media; pathological specimens; animal remains and
biological specimens; body fluids and secretions, blood, urine, feces, and
tissues; needles and syringes; disposable treatment devices in plastic, metal.
aa4 glass; "sharps"; newborn, pediatric, and geriatric diapers; and various
contaminated disposable containers.
Idhile such materials may represent only a small percent of the. total hos-
pital waste load, it it known from observation of waste handling practices
that these potentially infectious items are not completely isolated from all
other wastes in the hospital system. At some point, there is a reasonable
possibility that these "infectious" wastes can be intermixed with other wastes.
Ihe leading generation points for known infectious wastes are the surgical
, the clinical and research laboratories, the research animal quarters,
autopsy suite and pathology laboratory, and the renal dialysis department.
4s ttese wastes come from specific departments or sources, segregation of in-
C&ctious waste is possible by handling all wastes from these particular areas
as infectious. Another known generation point is any care and treatment area
or room for a known infectious case—inpatient, outpatient, or emergency.
Hany hospitals have switched to the use of almost complete disposable care and
treatment devices for such known cases. The waste load has risen accordingly.
Infectious hepatitis appears to be a possibility in the waste from a renal
dlalysis department. Hence, all waste from this area is regarded as suspect.
la view of the highly infectious nature of this particular virus, it is sug-
gested that any materials used in dialysis and around known hepatitis cases be
handled with extreme care. One suggestion made is that if wastes from known
casfes of hepatitis (or other highly infectious bacteria or viruses) are being
transported, that they be moved in a virtually "unbreakable or unrippable"
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bagging system. Further, that "needle sticking" of the waste handlers be
absolutely prevented by the methods used. The expense of the containers
should be secondary.
The major problems in isolating possibly "infectious" wastes arise from
the general patient care and treatment areas, both inpatient and outpatient,
where large numbers of patients are being cared for by nursing personnel and
diagnosis is often incomplete at the time. It is in these areas that infec-
tion level of most waste is usually unknown.
It is the conclusion of the research team that conducted the present
study of hospital wastes, that too many hospitals are attempting to classify
their wastes into categories that may not be logical—such as "definitely in-
fectious," "potentially infectious," or "safe," It is our feeling that all
solid waste should be handled with good management practices, regardless of
generation source, both with in-house and off-site methods and systems. By
standardizing on well thought out and efficient waste handling methods, pro-
perly supervised and executed, for all wastes, not only will financial advan-
tages be achieved, but breaks in waste handling systems and resultant cross
contamination should be greatly reduced.
External constraints have made the segregation of solid wastes extremely
difficult, and hospitals have occasionally gone to extreme methods to solve
these constraints. Burning known infectious material, along with the poten-
tially infectious, in on-site incinerators, was a common practice until a few
years ago. Today, with much more rigid air pollution codes and, in general,
rather poor incinerator installations that are incapable of handling the large
volumes of plastic used for disposables, hospitals have reduced the practice
of bulk burning. An exception is the pathological waste, required to be in-
cinerated by local regulation in most communities.
The majority of hospitals have turned to compacting their solid wastes
to reduce hauling costs and contracting to have them hauled to a landfill or
municipal incinerator. However, the nation is rapidly running out of sanitary
landfill areas. Further, many such landfills are increasingly reluctant to
accept hospital wastes for various reasons, ranging from potential effect on
ground water, to dangers to personnel from the aerosols such waste may create.
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In certain instances, hospitals have attempted to use gennicidal sprays
on a large scale in connection with their compaction of waste. In general,
this has proven to be impractical due to the difficulty of penetration of the
chemicals through the waste mass.
At least one major health department has objected to hospitals transport-
ing wastes through city streets no matter how "sealed" the vehicle may be, or
what precautions are taken, and this has put further constraint on the use of
landfills or municipal burning.
ttt one community, hospitals have attempted to solve the problem by vet
grinding of solid waste and flowing it into the sewer system. This procedure
may df may not be practical. The opening of the waste grinder has been limiteu
to ttd more than 9 in. by 6 in. to prevent overloading or overuse. This has
iliVdlved considerable manual handling of the material, to the point of sorting
and f»te-crushing to fit the opening. The practice may involve risks to hos-
pital personnel, plus potentially high labor cost to the hospitals. Grinding
hafl also proven to have problems in maintenance of equipment, plus problems in
flotation and sedimentation. With the sewer systems designed basically to
4£€6^t food wastes, and with hospital waste consisting of as much as 80 per-
cent in paper and plastic, external constraints have developed on the part of
the Sewer and sanitary departments, who are worried as to the effect on their
Systems should this practice spread.
A« a last resort, faced with these various external and internal con-
Stfaints, some hospitals have turned to investigating the possibilities of
Sterilizing their wastes froth potentially infectious areas, before centrally
collecting them and moving them off-site. Conventional steam and ethylene
dftide gas autoclaves and industrial retorts have been used; bactericidal and
spbricidal sprays have been tested. In addition, experiments have been con-
dueted on sterilizing encapsulated waste within the plastic waste bags by
ethylene oxide or formaldehyde pellets. Sterilization of waste has proven to
tie expensive, due to the difficulty in automating such a system compared to
incineration, and has done nothing to reduce the total volume of waste for
which the hospital must pay off-site hauling costs. Further, because of the
labor, equipment, and supply costs involved, it has been limited to waste from
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known infectious cases and has offered no guarantee that the remaining wastes
are "safe" to handle.
The consulting team in researching this present study was unable to locate
much in definitive data from other surveys as to exactly what tests have been
done on determining how "infectious" and how "hazardous" hospital waste actu-
ally is, day in and day out, across the board, and what actual effects this
has had on the environment and human health. The bulk of the judgements that
have been made in this connection have been based on the source of the waste
and the conclusion that, if the waste came in contact with known organisms at
the source, it was capable of retaining and transmitting these organisms.
Considering the number of hospitals and the number of patients being
treated in the United States, surprisingly few studies have been conducted as
to "how infectious" are these infectious wastes; and what type of bacteria are
present in what levels. Some university hospital studies have shown patho-
genic organisms present in the wastes, particularly if an organic substrate is
present. Significant counts were made of coliforms, fecal streptococci,
staphylococci, Candida albicans, and Pseudomonas. Bacillus organisms are most
noticeable, particularly staphylococci and streptococci. With the amount of
paper and cotton cloth in the waste, it is known that the mix is ideal for
transmission of viruses, with a potential transmission time duration as long
as 5 to 8 days. However, the studies have been on such a small scale as to
not be useful when the conclusions are extended to all hospitals.
A literature review conducted by a commercial firm under an H.E.W.
contract and completed in 1967, entitled "Solid Waste/Disease Relationships,"
did an extremely thorough survey of the research conducted to that year. A
total of 755 references were analyzed, but the conclusions could only point
out suspected disease pathways through solid waste systems. Opinion was ex-
pressed repeatedly as to the direct transmission effects between waste and
disease, but, as the researchers for this report found, few solid facts were
presented or conclusive proofs offered.
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HAZARDOUS HASTES
Several researchers have stated that all hospital wastes should be regard-
ed 4d "hazardous" when they are Intermingled in a central collection point, in
a campactor, or at a landfill. Infectious wastes are obviously hazardous in
view of potential effects on handlers and the environment. However, in this
Section the term hazardous is used to denote wastes generated from hazardous
materials: from any element, compound, or combination thereof, that is flam-
mable* corrosive, detonable, toxic, radioactive, an oxidizer, or is highly
tftactive; and that in the process of handling, storing, processing, packaging,
or transporting, may have detrimental effects upon personnel, equipment, or
the environment.
tn the total waste load of a hospital, the quantity of such materials is
Stall—normally less than 2 percent of the volume. However, all such material
requires special handling in transporting and disposal and hence can be one of
thfe ttbst expensive elements of in-hospital waste processing.
Radioactive materials are probably the best controlled of the hazardous
frolpital wastes. They may be in the form of radioactive liquids, containers,
and disposable materials, animal carcasses, or tissues. Handling techniques
vary between hospitals and with the radioactive substance. The most common
Method with liquids of relatively low level output is to dump the waste into
the Sewer system. Another method is to store both liquid and solid wastes in
fc Secure area in containers with foot operated lids, allow the radioactivity
to decay, then hand carry the -waste through and out of the building. Other
hospitals move the radioactive substances directly to the incinerator and
burn them. Often this can result in high radioactivity in the ash; with some
institutions storing ash for as much as three months to permit radioactive
before burial. Other hospitals transport such wastes in sealed con-
through the institution and bury it; in selected locations of their
tfffo; In municipal disposal sites; or ship it to one of the national disposal
Bittts. The decay of radioactivity then takes place away from the hospital.
Chemical wastes form the bulk of the remaining hazardous wastes, with
Certain medicines and pharmaceutical products making up the remainder. These
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may be in liquid, powder, or solid form. The range of chemicals, solvents,
and heavy metals is wide for potential effect on human beings, as well as on
the hospital equipment and structure. They include strong acids and caustics
of a highly corrosive nature; solvents in a wide range used from the labora-
tory to the maintenance department; compounds of mercury, arsenic, and cyanide,
all highly poisonous. As much of the material is used in laboratory work and
research activities in larger hospitals, as well as part of the workings of
patient care and analytical apparatus, it becomes fairly wide spread through
the institution. In many cases, it is in liquid form and the disposal method
for a high percentage is into the sewer system. Recent OSHA regulations pro-
hibit this practice for some chemicals. Some heavy metals, such as mercury,
are subject in many hospitals to a reclamation program with varying degrees
of success. Other liquid items generated in large quantities, such as certain
solvents and acids, are transported in special canisters and then disposed of
off-site, either buried, put into special wells or landfills, or shipped to
reclamation centers.
TABLE 2
COMMON TOXIC CHEMICALS REQUIRING SPECIAL HANDLING IN HOSPITALS
Boric acid
Hydrochloric acid
Nitric acid
Orthophosphoric acid
Phosphoric acid
Potassium hydroxide
Sodium hydroxide
Sulfosalicylic acid
Sulfuric acid
Trichloroacetic acid
Benzene
Carbon disulfide
Carbon tetrachloride
Chloroform
Copper sulfate
Iodine crystals
Mercury
Phenol
Potassium dichrornate
Potassium permanganate
Silver nitrate
Sodium dichrornate
Sodium floride
Toluene
Xylene
Zinc chloride
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PLASTICS
In the total make-up of hospital wastes, plastics of all types account
for 11 to 20 percent of the total cube and from 5 to 12 percent of the total
weight, depending on the hospital's supply practices in purchasing disposables
There are over 100 different uses of plastics in a hospital that relies heavil
on disposables; and probably as many as 700 different formulations supplied
attong these. The soft plastics are used for packaging; drainage and intra-
venous tubing; containers; sheeting; waste bags; examining gloves; tape; surg-
ical dressings and drapes; bed fabrics and clothing; masks. Hard plastics are
us«4 for bedside utensils; bottles; surgical and food trays; syringes; ash
tt&ys; containers; dishes and tableware; heart, lung, and dialysis machine
fatt6. Various foams—mostly polyurethane and styrene—are used for heat-
resisting cups and packaging materials. Among hospital wastes, plastics create,
unique disposal problems.
During incineration, plastics give off the most heat of any major classi-
flfeation in the waste, some exceeding 20,000 BTU per pound. This substantial
liftfct can create breakdown of incinerator linings. In addition, the particular
emissions are considerable if flash burning occurs; as in the case of syringes
(kndwn as "syringe puff"). Flash burning can make it difficult to control the
burning rate, which is essential in order to ensure that on a regular basis
combustion contaminants remain at or below 0.1 grains of particulates per
cubic foot of gas calculated to 12 percent of C02 at standard conditions.
It will be noted that polyethylene is one of the plastics that under com-
bustion generates an extremely high BTU output. It is one of the most widely
used plastic materials, accounting for 30 percent of total production. All of
the plastics will burn at 350 F to 450 F, but to be incinerated in a smokeless
and nearly contamination-free fashion, the combustion temperatures must be
1,800 F to 2,000 F for many common formulations. In many conventional incin-
erators, the introduction of plastics to combustion chambers that are not pre-
heated has merely melted the plastic, clogged the grates, and deposited molteu
puddles which burn erratically and even explosively.
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TABLE 3
INCINERATION OF PLASTICS
Type of Plastic
Poly vinyl chloride
Polyure thane
Polystyrene foam
Polypropylene
Polyethylene
Nylon
Vinyl
Acrylic
Heat of Combustion
cal/gram BTU/lb
7,040
9,050
7,040
10,100
11,064
8,050
8,050
7,040
13,700
17,600
13,700
19,600
21,600
15,700
15,700
13,700
Specific Heat
cal/°C/gram
0.35
0.45
0.35
0.50
0.55
0.40
0.40
0.35
Destruction of certain plastics by burning releases corrosive chemicals
into the exhaust gases. Polyvinyl chloride when burned gives off hydrogen
chloride gas, which is toxic to humans. In a post-incinerator scrubber this
forms hydrochloric acid and the effluent water must be neutralized. Addition-
ally, the polyvinyl chlorides have a corrosive effect on incinerator grates
and other metals as well as incinerator firewalls. Iron smokestacks will
collapse after continued large scale burning of many plastics, since the re-
sultant gas penetrates and eats the iron in an action similar to etching.
Plastics are not biodegradable in the same manner as animal and vegetable
substances. One of the prime reasons for their popularity is that they are
durable and offer long-lasting protection. If taken to a sanitary landfill,
their life can be many years. None of the plastics commonly used in hospitals
are broken down in the short run by weak acids or weak alkalines of the type
which might be encountered in a landfill; they are extremely resistant to
attack by bacteria and fungi. While not immune to ultraviolet in sunlight,
the attack is slow and affects only the surface of the plastic. Some of the
plastics—notably polystyrene—have poor weatherability, but none of them de-
grade completely. There is a form of advantage in this to the landfill.
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Since virtually all plastics are essentially nonbiodegradable materials, they
d<> not contribute to the pollution of ground water or evolution of gases.
They may, however, in certain physical forms, introduce special problems
in landfills because they are difficult to compact efficiently, due to their
resiliency, with ordinary equipment such as tractors, drag-lines, or steel-
wheeled compactors. Plastic films, sheets, and bags tend to become entangled
in the treads, wheels, and radiators of spreading and compacting equipment.
Because plastics are not readily biodegradable, composting has no effect
on them. If plastic wastes are introduced into sewage treatment systems s they
create problems. Sewage treatment plants are designed to handle basically
biodegradable animal and vegetable products. Not only are many sewer systems
already overtaxed, but also waste water is often reclaimed and reused and thr
danger of chemical contamination could be present.
From the above remarks, it is apparent that the advantages of plastics
to hospitals for the fabrication of disposables and for packaging may be self-
defeating. Each year during the past 10 years, the purchase of plastics by
hospitals has increased at a rate of approximately 20 percent, in each case
replacing an item made of paper, glass, metal, rubber, or a textile made £rom
animal or vegetable fibers. In most cases, the plastic use has been in high
volume, as it represents a disposable item that replaces a reusable item.
Long before the current energy crisis affected the production of plastics,
many hospitals decided that they had reached the point of no return in the
purchase of plastics. With the current converting of hospitals to reusable
items, the ever-rising plastic purchase curve may commence to level off, or
actually decline. Recent surveys by the study team have shown that several
large hospitals feel that the most successful way they can combat their present
solid waste problems is to greatly reduce purchasing of disposables. In order
to reduce labor costs, at least 70 large hospitals have spent large sums on
automating and mechanizing their processing departments, such as Pharmacy,
Central Sterile Supply, Medical Records, and Dietary, and embarked on a seriour
return to reprocessing reusables manufactured from glass, metal, and other
materials.
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HOSPITAL WASTE MANAGEMENT PATTERNS
The management of solid waste in hospitals has greatly improved during
the past 20 years. It has also become much more expensive in personnel, sup-
plies, and equipment that are used.
Any visitor to a hospital quickly learns that he is viewing a complicated
and interrelated set of work procedures in which peaks and valleys are very
evident. A hospital is a structured environment which (though many patients
may not like to admit it) is designed to give efficiency to the medical and
surgical care being rendered. There are early and mid-morning peaks in work
loads ranging from giving patients baths, to readying them for medical and
surgical procedures, to tidying nursing floors so that they give an uncluttered
appearance to the patients and their visitors. Other peaks of activity are
created by the serving of meals, given to most of the patients at their bed-
sides. There are also slack periods during which, in nursing wings, nothing
appears to be happening except the updating of patient charts at the nursing
station.
The ancillary and support departments are operated for the benefit of
the medical team as well as the inpatients and outpatients. Surgeries have
their peak periods during the morning and early afternoon hours. The labora-
tory and radiology find that the bulk of their work takes place during certain
hours of the day, based on the time samples are collected or pictures made, in
order to provide physicians and surgeons with diagnostic data within the time
frame they have set. The kitchen and the food pantries on the floors are
obviously tied in to meals, with hospital cafeterias often serving twice as
many people at a sitting as there are inpatients in the hospital. Central
sterile supply, the receiving department, and the warehouses must fit the
routine of supply management in the institution, with peak times for breaking
open cartons and issuing supplies and materials to the floors.
This routine of peaks and valleys has a definite effect on the way solid
waste is managed in the average hospital. As mentioned, activity connected
with the diagnosis, care, and treatment of patients involves people and it
involves supplies, and these in turn generate solid waste in peaks and valleys
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throughout the 24 hour day over which all hospitals operate. In most hospitals
successful waste management means concentrating on the peaks to eliminate them
as rapidly as is practical.
PERSONNEL UTILIZATION
There appear to be two basic approaches in utilizing personnel for waste
pick up and transport.
The first is known as "random" collection, in which a large number of the
total staff each devote a percentage of their time to handling waste. For
instance, during the day shift, the maids and porters from the housekeeping
department clear waste from baskets in patients rooms, outpatient clinics, and
from public areas. Assisting them may be the nurse aides who will also move
waste; along with technicians in the laboratory, pharmacy, radiology, inhalatio-a
therapy, and central supply department; clerks and typists in the offices; and
maintenance, engineering, supply, and laundry workers. Most of this personnel
is not on duty during the evening shifts. During night hours waste pick-up is
performed mainly by nurses aides from patient rooms and the Emergency clinics.
In each case the amount of handling of waste by an individual is relatively
limited; consisting mainly of emptying baskets or other containers, normally in
a bagged condition, and carrying the bags to a nearby collection room on the
floor, or depositing the bags in the nearest vertical chute.
The total hours used by all this staff added together become quite sub-
stantial, even though the individual increments are in minutes. As a result of
ti«e and methods studies, many hospitals have switched partially or totally
from the random collection system; and have set up one or more specialized
voste handlers to cover the entire building.
On a "structured" system the maids and porters and possibly nurse aides
may clear and bag waste from patient waste baskets and carry the bagged waste
a distance of 50 to 70 feet to a nearby collection room, such as a soiled
utility room on a nursing floor, or a chute room, where they will leave it for
piefc-up by specialized handler(s). The special waste handlers, from the house-
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keeping,or materials management department, will then pick up the bags and
transport them vertically by chute or cart. Normally these handlers will also
make "sweeps" of the building and clear all containers from support and ancil-
lary areas and from all offices, public areas, and corridors. This is now the
most common labor method used by hospitals.
Some hospitals have taken the system one step further and only the spec-
ialized handlers are permitted to remove and bag waste from any container or
area of the hospital.
Time and cost studies have revealed that such specialization reduces the
overall labor cost considerably and gives management a much tighter control
over waste handling practices. If abnormal peaks develop in any area they can
be handled quickly and as part of an entire, integrated system.
THE USE OF CONTAINERS LN WASTE HANDLING
During the past 20 years, hospitals have become sensitive to accusations
that their environment is "germ laden" because of the sick patients and the
potential "carriers" among the staff who are handling these patients. The out-
breaks of staphylococcus in many hospitals a few years ago clearly revealed
the contact problems that a hospital must face. More limited, less known, and
much more deadly, have been problems with other bacteria and viruses, such as
infectious hepatitis.
While American hospitals have installed the heaviest quantities of steril-
izers to be found anywhere in the world, in order to rapidly kill bacteria
present on supplies, material, and equipment, they have also learned that
"sterile filth is no more desirable than unsterile filth." To maintain a pro-
perly controlled environment in a hospital, constant cleaning of almost every-
thing is essential.
With research into aerosols and the effect of airborne contamination in
hospitals, administrators have learned that open, overflowing waste baskets
and trash cans cannot be permitted in a "clean" environment. It has been
determined that solid waste in a hospital should be contained or encapsulated
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almost as quickly as it is generated and, secondly, that it should be removed
as rapidly as possible from the nursing and support areas packaged in a bag
durable enough to withstand transport. The number of waste baskets and trash
containers has increased each year, with the galvanized metal container (with
the lid missing) giving way to synthetic, rust-proof rubber created by Industrie
designers and with a lid that locks in place.
The number of plastic bags to line these containers has increased to the
point where they are used almost universally in hospitals, adding to the increast
of plastic in the waste stream. The bags are capable of sealing, self tying,
or closing with twist wire bends, to provide a spill-proof, leak-proof contain-
erization when transporting waste through the building. Only a few years ago
the few that were used were usually of flimsy, clear plastic. Today such bags
are available in a host of sizes, thicknesses, construction, and colors. Red
bags are available for infectious waste; yellow for glass and metal cans; tan
or clear to line waste baskets; black, white, or brown to hold other bags dur-
ing, transport; laminated bags or plain, straight sides or gusseted, with mil
thicknesses from 1.5 to 10; even anti-static bags for use in surgeries.
THE ELEMENTS OF THE SOLID WASTE SYSTEM
Solid waste management in a hospital is a "stepped system." A series of
operations follow in logical order, one step at a time.
The first step is to contain the waste intially, as it is generated, where
it ±& generated. This normally involves discarding it into a nearby waste
basket or trash can, which is usually lined with a plastic bag.
The second step is normally the initial horizontal transport of the bagged
waste* from the waste container to the initial collection point. This may be
one of several locations. For example, the waste may be moved to a chute room
or soiled utility room. Or it may be placed directly into a gravity chute and
dropped to a collection room in the basement or first level. Or it may be
picked up by a hauling cart and taken horizontally to an elevator, vertically
to a lower level, and then horizontally to an intermediate collection area in
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the basement, or taken all the way to a final and central collection point.
Or it may mean placing it in a pneumatic tube system for delivery to a central
collection point.
The waste may be processed in some manner before it reaches the final and
central collection point. It may be compacted on the floors before transport
through the building. It may even be sterilized.
The third step is to move the waste from all the initial and intermediate
collection points to a final and central collection point in the building or
in an adjacent service building.
As the fourth step, all the assembled waste from all parts of the complex
is usually processed in some manner. This may mean merely dumping it into an
open hauling vehicle for off-site removal. More commonly it means compacting
it in special equipment so that volume reduction is obtained. Or it may be
incinerated. Or it may be shredded, pulverized, or milled.
The fifth step is to haul it off site, bagged, or as raw loose waste, or
compacted, or ground, or milled, or in the form of ash residue.
AUTOMATION AND MECHANIZATION IN WASTE MANAGEMENT
The majority of hospitals transport solid waste within the building by
hand methods, either hand carrying it in bags, or moving it by a pushed or
pulled cart. These methods have been used in virtually the same manner since
the first hospitals were formed.
While many hospitals have gravity chutes to transport waste vertically,
hand methods must be used to carry or push the waste to the chute loading sta-
tions; and hand methods or carts must be used to carry the waste from the col-
lection room at the bottom of the chute to some central collection point.
Gravity trash chutes have created fire hazards in some hospitals. In the past
few years, new fire codes, requiring better construction specifications, fire
walls, and sprinkler systems, have obsoleted many existing chutes.
Many more hospitals have purchased mechanized volume reduction equipment
than have purchased mechanization for waste transportation.
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The first volume reduction equipment were the incinerators that virtually
every hospital had installed by the 1920*s. During the 1950's, wet grinders
for garbage were installed in kitchens, serving the dual function of volume
reduction as well as transport to the sewer line. During the past 10 years,
as hauling costs have mounted, compactors have been purchased by over 40 per-
cent of the hospitals, ranging in size from home-type units for installation
on nursing floors and in ancillary departments, to heavy duty machines coupled
to 40 cubic yard off-site waste hauling vehicles.
The most recent additions in mechanical equipment for volume reduction
have been the shredders, attrition mills, hoggs, and dry grinders that a few
hospitals have installed. These, like compactors, range from small, portable
units for shredding office paper, to 3 ton per hour attrition mills installed
at the central collection point and connected either to a compactor or an in-
cinerator.
Less than 200 of the 7,000 hospitals in the United States have automated
and mechanized the transportation of solid waste. Among these institutions a
variety of methods are being used: including wet grinding or pulping; carry-
ing in tote boxes on vertical and horizontal conveyors, or in dumb waiters;
the use of automated carts, either controlled by electric circuits on the floor
6r suspended from overhead rails; the use of combination systems, with auto-
mation of the vertical movement (ranging from gravity chutes to automatic ele-
vators) tied in with hand or cart movement for horizontal transportation in
fctte lower levels.
A survey of over 100 hospitals that have already installed or are purchas-
ing various types of automated transport systems for solid waste reveals that
the installed cost ranges from $100,000 to over $1,000,000 for the equipment
and space utilized. Only a small number of these institutions have employed
cfte services of professional consultants and engineers, knowledgeable in solid
wafete management, and with in-depth experience in the design and feasibility
of these expensive systems. In very few cases were intensive feasibility
studies made of the volume of waste by specific generation points before the
systfems were designed. The location of sending stations, the routing of the
syWtem, and the design specifications were usually done by a system manufacture
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and incorporated into the construction drawings by the architect.
Hospitals for the first time are studying in great depth the economic
feasibility of such automation and mechanization. These studies are revealing
that some of the directions that have been taken in the past have not resulted
in operational savings. Caught in the squeeze between shrinking capital dol-
lars for equipment and pressures to reduce operating costs, hospitals are
learning the importance of feasibility studies, done professionally and done
in depth, before embarking on expensive programs of automation.
With the external constraints and pressures on hospitals from local com-
munities with regard to the off-site removal ot waste, combined with the inter-
nal pressures, hospitals are also looking at another aspect of solid waste man-
agement; namely the possibility of drastically reducing the generation of waste
in the first place. This involves their entire philosophy of operation. It
particularly involves decisions concerning the purchase and use of disposables
versus reprocessing medical and surgical supplies. Some hospitals that, up to
two years ago, were heavy users of disposables have made abrupt changes in this
direction. There are instances where the purchases of these items have been
reduced by as much as 50 percent and replaced by reprocessed reusables. The
effect on the total solid waste load has been dramatic, in some cases cutting
the total cube by as much as 65 percent. A subsidiary effect has been a con-
siderable reduction in operating budget, as these same hospitals are learning
9
that intelligent, mechanized reprocessing is now also economically feasible.
REFERENCES
1. The 1973 A.H.A. Guide to the Health Care Field.
2. Hospital Industries Association Reports, 1973.
3. The 1973 A.H.A. Guide to the Health Care Field.
4. Ibid.
5. Ibid.
6. Ibid.
7. Ross Hofmann, Associates, unpublished surveys, 1954, 1967, 1973.
8. Hofmann, R. E., Automation of hospital Sterile Processing, 3rd ed.,
Coral Gables, Ross Hofmann, Associates, publishers, 1972. 176 pp.
9. Ibid.
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2- ARCHITECTURAL DESIGN INFLUENCES
A modern hospital is probably the most complex institutional structure
that has been designed in the Twentieth Century. The interrelationships be-
tween patient areas, both inpatient and ambulatory, and the ancillary and sup-
port departments run into the thousands. What is done in one function or area
of the complex affects directly or indirectly dozens of other areas and func-
tions. In the field of solid waste management, these complications are seen in
every study performed in the past 20 years.
The architectural and engineering design of a hospital is always a com-
promise. There are over 100 major, support systems involved, of which solid
waste management, movement, disposal, and removal is only one. Within spaces
that have often been likened to the "interior of a submarine," several support
systems, often designed by several different disciplines, must fight for
entrance and egress, routes, support lines from interfacing systems, and sheer
space. The maze of pipes, wires, ducts, chases, etc., is thus a compromise and
it is compromised still further by the installing trades and change orders
during construction.
PLANNING SOLIff WASTE TRANSPORT SYSTEMS
No hospital has yet been designed where the solid waste management system,
whether it be pneumatic tube or other method, takes precedence over all else
and thus has been able to obtain ^ perfection in layout." Being a compromise,
to fit with other systems into the structure, there are obviously built-in
weaknesses in the system layout when superimposed on an architectural design.
Too often, a study of such systems reveals chat the mechanical components
are operating satisfactorily, ant4 the human elements in operation and mainte-
nance are doing exactly what they #re supposed tc do, yet the system is "weak"
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in one or more aspects of performance, due entirely to the architectural lay-
out having compromised the system to too great a degree.
The installed systems usually do not operate at 100 percent efficiency
unless they are planned on facts that are carefully assembled and then they
are programmed to meet these facts. Good system design and layout cannot be
"ivory towered." Architectural planning must move from being isolated at the
drawing board to being married with industrial and management engineering.
Before lines are drawn, and the fixed route, chutes, stations and collectors
are positioned, what each must perform should be determined in detail, based
on firm projections of the amount of waste (and laundry) that will be genera-
ted by each and every department and section of the hospital that must be ser-
viced. Volume-use-time relationships must be established through a typical
industrial engineering approach.
With an existing hospital, these facts are readily obtainable by the use
of standard survey and statistical techniques in which all quantities,
sources, and types of the waste being generated are carefully recorded. For
new construction, projections have to be made based on figures obtained from
hospitals of similar size, with similar programs, and in a similar zone of
service. In both cases, operating projections for at least ten years must be
made so that the systems are neither over- nor under-sized.
The parameters that must be developed before any systems can be planned
and designed are the following:
1. What materials, defined as waste, must be managed, and what is their
make-up from a variety of standards—e.g. combustible or non-combustible;
"contaminated" or "safe," biological, infectious, hazardous, radioactive, tox-
ic, or explosive; grindable or non-grindable (such as food wastes); dissolva-
ble, or able to be slurried into a sewage system or wet pulping system; patho-
logical and surgical, human and animal parts, and tissues; material make-up
(paper, plastic, wood, metal, glass, ceramic, and textile).
2. What segregation, if any, of waste will be maintained, to separate
the "problem" wastes from the so-called "safe" or general waste, and how prac-
tical is segregation, as well as alternate methods of handling the segregated
wastes.
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3. From whence will each type of waste be initially generated,
4. In what quantities (both weights and volumes), at each generation
point, and at what times of day (peaks, valleys, and averages) will such waste
be generated, by type.
5. From what points in the building, by what routes, to what points
(interim as well as final) will all the different solid wastes have to be
collected, packaged, moved, stored, collected again, reduced, and ultimately
removed to some off-site location.
6. Due to either internal or external constrains, what time limitations
nay apply.
7. What safety regulations or limitations must or should be followed in
handling and packaging these wastes for transportation within and away from
the building.
Solid waste management is a "stepped system," and each step must lead
logically to and be interfaced with the next step, so the result is one con-
tinuous flowing system without false breaks. To convert this to a hospital
setting, it is essential that the following steps be studied, analyzed, and
evaluated before the architectural design can be finalized:
1. How the waste will be initially deposited by the person or device
generating it, and in what type of container (e.g. lined wastebasket or gar-
bage can, closed or unclosed, mobile cart, or cloth bag), and in what location
2, How the waste will be transported from this point, over what route,
over what period of time, at what time, by whom, in what type of container,
and by what method (cart or hand carried), to a waste chute or other removal
method.
3. What temporary storage and/or processing will occur between initial
generation points and the transporting of the waste (e.g. use of soiled utili-
ty rooms, floor storage rooms, corridor storage, autoclaving or melting,
floor compacting, grinding, double bagging or special packaging, and/or label
ing, etc.); what volumes and types will be involved, and over what time ele~
meats.
4. What transporting problems and times may be involved. This includes
waiting times for access to elevators and waste chutes and the routes that
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must be followed, to remove from the floor to a central collecting point.
5. If the waste is unloaded into an intermediate location, it must then
be moved once more, either manually by cart, or by one of a number of available
automated methods, to a central and final collection and/or reduction point.
6. From the central collection room, the waste may be transported into
the final storage or reduction area. This can be located in a trash room in-
side the lower levels of the building; in & separate trash building; on, or
adjacent to, the loading dock, incinerator room, or compactor area. Or some
automation may occur, feeding directly into a hogg or grinder, then via a surge
tank into an incinerator or compactor, or directly into a compactor and/or in-
cinerator. Space for the various equipment items must be carefully planned.
7. Finally, there must be determined what volume reduction will occur
in each step of the system "in the house," and how this affects the spaces
planned for waste storage.
Solid wastes and their removal interface with the handling of the returns
of soiled reusables for reprocessing, such as patient bedside utensils, medi-
cal-surgical reusable equipment and supplies, eating and drinking tableware
and utensils, and both surgical and patient linens. Studies and analyses must
clearly define these interfaces and how they affect and interact with the solid
waste management.
Solid waste removal also interfaces and may affect clean material delivery
and storage. Most hospital material consultants have for years preached the
dangers of cross-contamination and the desirability of "clean" and "dirty" sep-
aration. This is basically a management engineering problem. The architectu-
ral design will obviously affect the problem and potential solutions tremen-
dously. Some areas, such as surgical suites and laboratories, are often
designed with "clean" and "dirty" corridors that establish a positive material
flow to greatly reduce the problem. Other areas, such as kitchens, attempt to
direct flow by equipment placement. Other areas, which are major solid waste
generators, such as patient care and treatment departments, attempt to control
the problem solely by personnel management and the introduction of "clean"
and "soiled" utility rooms. However, the corridors, patient bedrooms, and
treatment rooms are simultaneously used for the transportation of both soiled
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and clean items. Cross-contamination is a real possibility.
THE VERTICAL CHUTE--PNEUHATIC TUBE SYSTEM FOR SOLID WASTE TRANSPORT
The principle of pneumatic waste transport systems is a simple one, vexy
similar to a large size vacuum cleaner, combined with a fixture that high-rise
buildings have had for many years—the gravity drop, vertical trash chute.
To implement the system, one or more vertical waste chutes are installed
in the hospital, with openings installed in them on each floor being serviced,
These openings are the "loading stations" of the system. They receive solid
waste, normally contained in plastic bags sized to fit the diameter of the
chute. The loading stations are similar in appearance to those in standard
gravity chutes. In one system they are almost identical to these, as modified
gravity chutes are used for the vertical drop. In other systems they are
sophisticated by the inclusion of a hopper that has an outer door for the use
of the operator in loading the waste, and an inner door that opens on a timed
cycle to permit the bag to drop into the chute.
At the bottom of the chute is a connection to a tube of identical diameter
that pneumatically carries the waste horizontally through the hospital and
finally deposits it in a box or tank known as a "collector." On a timed basic
that is part of the total transport cycle, doors open in the base of the col-
lector and drop the waste, by gravity, onto or into whatever is the next step
in the process—a compactor, a cart, a dry grinder, a truck, or a trash room
floor.
There are two basic system designs. One uses a gravity chute and the
bagged waste drops down onto a plate or slide valve at the bottom. This plate
cycles on a timed basis, opening to let the waste fall into a horizontal tube
and an air stream that carries it to the collector box. This is known as a
gravity to vacuum system. The other system uses a vacuum or air stream to pull
Che bag the entire route, from the loading station in the vertical chute to the
collector box. This is known as a full vacuum system.
Both systems use large fans to pull the waste through the system, with the
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transport air allowed to enter the system at the opposite end to the fan. It
is the velocity of the suction air stream that sets the speed at which the
waste moves through the system. When the waste drops into the collector box,
the suction air continues through a port in the box, and by more tubing, tra-
vels to the suction fan, and through it by an exhaust duct to the atmosphere.
SIZING THE SYSTEM
VERTICAL CHUTES
Based on chute loading surveys and time studies, it is obvious that select-
ing the proper number of loading stations and the proper location for each is
not simple. We are dealing with a system of vertical chutes that are connected
horizontally, at the bottom usually. While it is possible to lead the flow of
material downward other than by a straight vertical drop, it complicates the
installation of the system and increases the expense.
If the areas to be serviced are laid out identically and are stacked
exactly one above the other in a high-rise structure, the installation of a
straight vertical chute is relatively simple. It can go straight up through
the middle of the heaviest activity, floor after floor. The loading stations
will be stacked above each other on each floor for deposits into the chute.
With this situation there is still some flexibility of architectural de-
sign on each floor, as we are dealing with a round chute. It can be loaded
from different directions on each floor, such as loading second floor from
the north side of the chute, third floor from the south side, fourth floor
from the west side, and so on. Hence, location and entrance into chute rooms
can differ somewhat in the floor plans when stacking floors in an architectural
design.
However, if in stacking, architecturally, one floor above the other, it
is decided that the location of the chute loading stations will change hori-
zontally from floor to floor, the design becomes complicated. If on second
! floor the chute loading station is to be next to the nursing station, and on
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the third floor this is still desired but the nursing station has been moved
fifty feet to the west of the second floor location, and on fourth floor
twenty feet to the east, we need a vertical connector between the three that
must travel fifty feet horizontally on one floor and twenty feet on the other
J.H order to link up. With a full vacuum system, this is possible, providing
there is ceiling space for the tube. With a gravity drop system, it is out
of the question.
J$ is obvious that, architecturally, the lower the height of the building
o* the less vertical drops required, the easier it is to design a system; the
were important the horizontal rune become. However, as few one and two story
hospitals are being constructed today, the designers have to worry about the
Vertical stacking problems.
STATIONS
TO reduce the number of vertical chutes and loading stations to a minlmu; ,
ra should do «xtreaely detailed analyses of the entire waste load of
building and then "zone" the entire complex, locating the vertical chutes
and loading stations on a coapromise basis-. It would be impractical to have
% chut.e loading station exactly where every small sub-section generating solio
vjaftte. would like one. A rule of thumb is used that is based on walking time
tp, load the chute. An area radiating out from the chute station between 70
anjt 1QQ feet is considered ideal to be serviced by the particular station.
To date, zoning on this basis has left something to be desired in any
dftfj.gn we have studied. The simplest way to check this is to run a one-week
sj^vey, recording every bag that is deposited in every chute. A review of ch
chapter on volumes of waste generated shows that 90 percent of the total vol-
ufle in any hospital is deposited in under 50 percent of the chute loading
stations. This raises the question as to whether the remaining 50 percent of
t^, chute loading stations were worth the expense of installing. How much
did this virtually unused 50 percent of the stations cost? How many years of
extra walking labor time to haul this 10 percent of the total waste to the
other 50 percent of the stations would be involved before the extra stations
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pay for themselves?
Hence, in zoning a system, walking distance to the chute station must be
factored mathematically with volume of waste generated within each zone, before
a decision can be made whether a particular station should be installed. This,
in turn, means virtually designing the operational procedures for waste col-
lection before the system is designed.
Some basic facts are known in any hospital as to where the greatest vol-
umes of solid waste are generated and over what periods of time during the day
and what the make-up is.
On the basis of weight, as can be seen from the chapter on volumes and
types of hospital waste generated, from 10 percent to 20 percent cannot be
deposited easily in a pneumatic chute and tube system as they are currently
constructed. The size of the waste pieces defeats the ability to load into
the chute. Typical examples are large cardboard cartons, construction materi-
als, crating and packing materials, iron pipe, large metal drums, etc. If
these items end up on the floors of the hospital, they will have to be hand
trucked to the central collection point. Certain other items, either liquid
or solid, should not be loaded because of their hazardous nature; such as
highly corrosive, explosive, inflammable, or radioactive materials. These
may be 1/2 percent of the total waste. Other items possibly should not be
sent through the chutes, unless they are packaged in spill-proof, unbreakable
containers; such as highly infectious fomites, laboratory samples, and patho-
logical specimens. These may be as much as 4 percent of the total load.
The remaining 75 percent to 90 percent of the total waste generated by
the hospital could be transported by the chute system and the generation
points, times, and material make-up are known for all hospitals in a general
way. Past studies have shown that 80 percent of the total is generated by
20 percent of the departments, with surgery, dietary, nursing stations, mater-
nity, laboratories, and the computer department leading the way. This overall
data can be refined in an existing hospital or projected with comparative
studies for a new hospital.
From this, a grid can be made for each floor on a zoned basis, as we have
described, and the vertical chutes and desired loading stations overlaid on
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the architectural plan. Hopefully, with a building in the design stage, the
architect and owner will agree to permit the vertical risers to be placed in
the proper locations, With an existing building, the placement will depend
on finding a clear vertical route or shaft (duct shaft, elevator shaft, etc,}
even to the point of placing it external to the building, because there is an
way to put it through internally.
CHUTE LOADING ROOKS
It is essential for the owner to realize that the architect must enclose
the vertical chute in a fire-rated shaft. With its installation, a chimney
has been added to the building that could spread a fire in the lower part of
the building upwards. This take* up space and must be allowed for. The
latest thinking is that the chute loading room and the chute should be a com-
plete, fire-rated envelope, with the chute rooms sprinkled, because of the
possibility of storing trash in them while waiting to load a chute.
this raises the question of how large a chute loading area should be.
Until a few years ago, when gravity trash and laundry chutes were installed
the Loading doors could be in an open corridor or an open alcove. Modern cod
prohibit this and call for a room in which to load the chutes, and normally
with a fire-rated door. With a gravity to vacuum system, there should be no
delay in loading the chutes, ffee chute loading room should be only large
enough to: comfortably carry the wAfte bags into the room; comfortably
maneuver the cart or other conveyance being used to carry the bags; and allow
the room door to open and close wijjjbout getting in the way of loading or cart
maneuvering.
With a full vacuum single bag system, as will be seen, there is often
waiting time to load the chutes. Aides, nurses, maids, and porters may refvu-r
to wait; also such delays a«e expensive in labor wasted. Administration at
the same time wants the patient routes, nursing stations, support areas, and
corridors clear of waste and soiled laundry and wants to prevent cross-
csftfcamination between the soiled and clean supplies. The dilemma arises—
-------
where to temporarily store the waste and laundry until it can go down the
chute. And secondly, what quantity will be involved at any point in time.
While admittedly temporarily storing waste bags and laundry bags in the chute
room is not good practice, it is better than storing them in the adjacent hall-
ways. With a full vacuum system, that cycles slowly and accepts only one bag
at a time, in peak periods some such storage will be necessary. The rule of
thumb that has developed is to allow enough floor space in the chute room to
hold a cart capable of holding 12 bags. This means a chute room at least
45 square feet in size.
FAN ROOM
The main architectural requirements are sufficient space to hold and be
able to easily maintain the installed equipment; sufficient strength of floor
to hold the heavy fan and motor without transmitting vibration into the sur-
rounding area; sufficiently thick walls to prevent transmission of sound out-
side the room; adequate space and air flow to keep the room and its equipment
cool; proper location in the complex so that the effluent air from the fan
can be exhausted without affecting the environment.
There is no fixed rule as to where the room should be located in the
complex as long as the above criteria are met. In general, fan rooms are
installed on a roof area or on ground level.
CONTROL CENTER
Architecturally, the optimum location for this area is in the general
location of other control engineering centers in the hospital. In the vici-
nity of the Engineer's office is the probable location.
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COLLECTOR BOXES
A major weakness in many hospitals is that they have too small an area
for a loading dock and receiving section. With a pneumatic tube system, this
area must be large enough to fulfill its function.
If the hospital has an in-house laundry, the soiled laundry collector
box frill be installed in the soiled section of the laundry and should have a
receiving and sorting area under it of at least 120 square feet.
If the laundry is remote from the hospital, the most protection from
theft and the least labor in handling at the end of the line, is to construct
a truck well, with a protective and locked fence around it and load an open-
top truck or trailer at this location. The linen collector would be placed
above the open trailer. Hence, at least 15 feet total head height would be
required from base of well to top of collector.
The trash collector should be placed where it can be most directly fed
into the collection and reduction equipment that will be used. This also
infers providing sufficient vertical height and floor space to accommodate
all the necessary equipment. This also infers that the location is easily
available to hauling trucks for removal of loose or compacted waste or
Incinerator ashes. This can be an area adjacent to the hospital loading dock.
a separate dock area, or in a separate service building.
If the collector is to discharge directly into a compactor-hauling bin
asenbly, a minimum of 14 feet head height and a minimum floor area of 12 ft
by IS ft is required for the compactor, plus space for the placement of the
receiving-hauling bin.
If the collector is to discharge into an attrition mill or hogg, with
a cyclone-surge tank-filter assembly, the vertical space required is up to
21 ft. Often, the hogg is recessed into an 8 ft deep pit to reduce floor
level height problems as well as reduce noise transmission. Floor space to
provide proper maintenance room for this entire arrangement is a minimum of
20 ft by 30 ft. To this must be added the space required for a compactor
and hauling bin or an incinerator following the surge tank. Hence, in
total, 1,500 to 1,650 square feet of space say be required.
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STRUCTURAL STRENGTHS FOR INSTALLING EQUIPMENT
The heaviest equipment is at the end of the line with items such as com-
pactors, hoggs and attrition mills, surge tanks, and incincerators. Equally
heavy, per square foot of floor space, are the heavy motors in the fan room.
Next are the collector boxes, many of which are suspended from ceiling beams.
All floor and ceiling loads should be calculated carefully to ensure there is
sufficient structural support.
The chief architectural problem is to eliminate vibration, either within
the tube system, or being transmitted as sound or noticeable structural vibra-
tions. In the chapter on construction analysis, the importance of vibration
isolation has been stressed. The importance of rigidly and strongly anchoring
the pneumatic tube to the structure has also been shown. This infers concrete
or other dense material capable of holding the mounting system.
GENERAL CONSIDERATIONS
When an analysis is performed of the total waste removal problem of a
hospital, it is seen that a pneumatic chute and tube system does not solve all
removal problems. Items that are too large for the chutes, or for one reason
or another are considered too "hazardous" to send down the chutes, will still
be transported manually from generation points to the central collection area.
Whether the material is bagged and sent down the chutes or is hand hauled
in a cart of some type to the ground level, the importance of avoiding cross
flows and cross-contamination between the transportation of solid waste and
the transportation of soiled reusables for reprocessing and the transportation
of clean supplies cannot be overstressed. This appears to be one of the major
archiectural weaknesses discovered when an analysis is made of solid waste
; management in hospitals. The use of service corridors and service elevators
for the movement of supplies and of solid wastes appears to have been installed
in too few hospitals. Such corridors and elevators should not be available
to patients and the general public, and should have limited use for the move-
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ment of staff. Too often, we see an elevator or a main corridor being used
simultaneously for the transportation of a cart loaded with bags of solid
waste, a patient being moved on a stretcher, several of the hospital staff?
from nurses to porters, and a sprinkling of visitors. It would appaar that
more attention should be given in the designing of hospitals for clear
separation of traffic flows, to avoid this situation. Further, conditions of
this type usually create much extra waiting time in both the movement of
supplies and the transportation of solid waste, increasing the operational
costs to the hospital. This is particularly true when service elevators,
reserved exclusively for supply movement, have not been included in a high-
rise structure.
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3 DESIGN AND CONSTRUCTION CONSIDERATIONS
The purpose for which pneumatic tube systems are used in hospitals is to
transport safely and free of cross contamination, without plugging, or failure
to move, loads of solid waste and soiled laundry. As it is possible for a
transporting bag to break or spill in transit, this infers also the ability to
transport loose particles of solid waste and loose textile items. These facts
set certain limits and define certain standards for any such system.
It is impossible to study the existing systems with respect to the move-
ment of solid waste only, as in many cases both soiled laundry and solid waste
are transported in the same vertical chutes and pneumatic tubes. In other
cases, they are in separate chutes and tubes but controlled by a common suction
fan. The transporting of laundry affects the transporting of waste, and vice
versa.
A review of these systems that have been installed in hospitals reveals
a wide variation in design and construction standards, despite the fact that
all such installations are supposed to perform almost identical tasks. A
detailed analysis indicates that these variations in approach arose from the
fact that the owners, the specifiers (architects, engineers, and consultants).
and the vendors attempted in many cases to reduce the capital cost of the in-
stalled system, despite a potential for serious effects on operating costs
during the first ten years of use.
SINGLE TUBE FULL VACUUM SYSTEMS
The first pneumatic transport design used in a hospital was a single tube
system, to carry both solid waste and soiled laundry, and with a single fan at
the end of the line to create the suction to carry the load through the system.
This fan runs during the period of the day the system operates. There are
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separate loading stations throughout the complex for solid waste and for soil;
laundry. These are normally in the same "soiled" collection room, and are ad-
jacent to each other, leading into a common vertical riser or chute. When a
chute loading door is opened it exposes a sloped hopper, or loading station
with an iniier door leading to the vertical chute. The operator places a sin-
gle bag of waste, ot of soiled laundry, in the indicated (waste or laundry)
hopper and closes the outer door, fie then presses a button or turns a switch
to activate the movement.
This creates a sequence of events. A roof damper opens to allow air to
be sucked through the vertical chute involved and through to the exhauster
fan. All other chute roof dampers remain closed. A damper over a continuous
operating fan is raised, allowing the fan to suck in this air; or alternative
ly the suction fan starts up. After proper air flow is established itr tb« sj
tern, the inner door of the loading hopper opens by a compressed air cylinder
allowing the bag of waste or laundry to drop into the vertical chute and In.t^
the suction of the ait stream. Depending on whether the waste or laundry se-
quence has been activated by the operator, at some point in the system a
"aiverter" valve swings into the proper position to shunt the bag into the
proper collector box at the end of the line—either waste or soiled laundry,
After a timed delay to ensure the bag has dropped into the chute, the innax-
dbor of the station closes.
The bag travels the tube system and drops into the collector box. The
effluent air stream that provides the suction continues out of a port in Hz*.
box and travels by more tube to the fan; it continues through the fan and ic.
exhausted to atmosphere. At this point the dampers all close. Based upon ?
prefigured time cycle, doors Bpeti in the bottom of the collector box and dro
the bag out of it by gravity otito the floor, a cart, or whatever else is de-
signed into the system beneath the box. The system is then ready to start;
over again and accept its next bag. In short, all such systems work on the
same principle as a vacuum cleaner. They are Called "full vacuum" syr,terns,
the vacuum is pulled on the vertical risers, or chutes, as well as on all lh
horizontal tubing, creating a suction throughout every part of the system.
Such a "single tube" system obviously can create problems. Originally,
-42-
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some had only one loading door at each station with two activating switches to
push—one marked "trash" and one marked "laundry." If the operator pushed the
wrong switch, the diverter valve had no way of. knowing this. Waste wound up
with soiled laundry and vice versa. To prevent this, separate loading doors
and hoppers were used—one for waste and one for laundry—each still leading
into the common vertical chute, the separation being purely psychological.
However, human mistakes still could occur. Or, mechanical and electrical
problems could develop, in which the diverters could be faulfy and not divert
as scheduled: again resulting in misdirected loads.
Another problem with "single tube" systems is that a bag of waste could
break or spill in transit. When followed by a bag of laundry, particles of
waste often ended up in the soiled laundry, the most common being broken glass.
It was also discovered that such single tube, full vacuum systems were
rather slow. They were designed to carry a single bag in the system at a time,
with a total cycle time, from the placing of the bag in the chute loading hop-
per to dropping out of the collector, as high as 40 seconds. This meant that
less than two bags per minute could go through the system. The standard "push
button" design ensures that the inner door of the loading hopper provides a
positive seal or closure between the "soiled" chute room (and the loading hop-
per) and the vertical-horizontal pneumatic system. The inner door leading to
the chute must be closed completely before the outer door of the loading hopper
can be opened. This is accomplished by an electric or air-operated lock on
the outer door. The purpose is to ensure that the system operates on "one bag
at a time." Also that it does not draw air in from the chute room and hence
change the basic balance of the vacuum pull for which it was designed. Such
systems often have as many as 50 or more loading stations (divided between
waste and laundry) and they cycle normally on a "first come-first served"
basis, with relays activating the stations from a simple memory circuit.
Let us assume that, during the morning service peak, seven people decide
to use the system, in various parts of the hospital, at the same time; and
that each has up to five bags of laundry and three of waste to get rid of on
this particular trip. Let us assume further that all seven operators load
their first bag (waste or laundry) about the same time into the particular
-43-
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cfrate Station they are using. Each also pushes his activating switch. The
system cycles on a "priority load" basis through relays in the control panel.
Each operator must wait until the system has cleared and the signal light on
Ms dder shows his first bag has been transported, so that he can load in his
Second bag, and so on for each successive bag. He waits his turn in line as
the System cycles between stations. For each bag, he may be second in line
or seventh.
Assuming a total of eight bags for each operator and seven stations being
loaded simultaneously, this is a total of 56 bags being put into the system at
a pteftk period. Assuming each bag takes as little as 30 seconds to travel its
complete route, only two per minute can be transported in total. Hence, an
operator could be waiting by his chute station for as long as 28 minutes until
he could get rid of his last bag. Obviously, this is an unsatisfactory situ-
ation, as all seven people loading the chute would be in virtually this same
position and approximately 7 x 28, or 196 minutes (over 3-1/4 manhours) of
expensive labor would be used aerely in waiting time to load only 56 bags into
vertical chutes.
MULTIPLE LOADING FULL VACUUM SYSTEMS
To avoid this problem of nolding people at chute loading doors while they
thieir turn will come quickly, certain busy hospitals asked for a change
ifc thfe loading sequence and cycling. They requested that the principle of one
%ag at a time in the system be eliminated. They insisted that the tube system
%fe capable of hauling, in a single pull, a train of up to twelve bags at once.
In a full vacuum system, this was called a "key-lock" method. Instead of
the "go" button, the operator turned a key to activate the switch.
overrode the system's normal cycling. As long as the key was "on," the
iiitter door remained open, as did the fan damper and roof damper. In short,
the Vacuum remained on and pulled as many bags as the operator could drop in,
tftfle tffter another, or that the collector box at the end of the line would hold,
To hold a succession of bags, the collector must be of larger size than for a
-44-
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single bag system. When the key was turned the other way, the collector box
doors would open and drop the whole load of bags it held at the end of the line.
Then the entire operation could be repeated at the same chute station or at a
different station.
A difficulty in this is that only one operator can use the system at one
time. When he is loading his door, all other doors lock closed automatically
to avoid overloading the system with too many bags. Hence, it is normal for
such a system to be used only by special operators, who travel from station to
station and load out all the bags of waste (and laundry) that various other
hospital personnel have deposited adjacent to the chute station. At least
there is the labor advantage of only one individual engaged in waiting time,
and that time is reduced by at least 75% through multiple loading.
Further, this loading process has certain hazards. The operator is over-
riding a full vacuum system. Both inner and outer doors of the loading hopper
remain open. While air to create the vacuum is being sucked from the roof vent
at the top of the vertical chute, it is also being sucked by the fan from the
open chute loading door. We have observed enough vacuum force to pull open
the heavy door of the chute room itself and to require the operator to hold
open the outer door of the chute station with the full weight of his body. A
positive "open position" latch appears to be a necessity.
Another problem of the single chute system lies in the fact that it is
used to carry completely dissimilar objects in a common tube. Laundry is nor-
mally sent through the system in cloth bags, packed rather full and weighing
from 5 to 20 pounds each. Waste is usually in plastic bags with loaded weights
of from 2 to 12 pounds. Yet the same tube and the same suction force or air
velocity is required to carry this wide divergence in load in a single tube
system.
DOUBLE TUBE FULL VACUUM SYSTEMS
Due to the problems described in the single tube full vacuum system, de-
signers decided to sophisticate the construction of such systems, though it
-45-
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Single Tub* Stotion
Double Tube Station
2.
Sprinkler Head
PLAN VIEW
•Compressed
Air Lint
Sprinkler Head
PLAN VIEW
Compressed
Air Line
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Acctee
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- Signal
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£- — Finished Floor
JRONT VIEW
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These drawings show the
various configurations used in
loading the stations of the
full vacuum systems. With a
single tube station that ac-
cepta both solid waste and
soiled laundry, many different
configurations can be used to
enter the loading hopper into
the vertical chute. Close
proximity of waste and laundry
loading doors, despite clear
markings for the material to
be loaded, allows room for
loading error by operators.
FIGURE 1. TYPICAL FULL VACUUM PNEUMATIC TUBE STATIONS FOR SOLID WASTF
LAUNDRY
-46-
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would increase the capital cost.
The first approach was to utilize separate tubes for waste and for laun-
dry. Obviously, this would permit totally different construction specifica-
tions for each tube. At first a common fan was used to pull the air for both
tubes and a common return air line led from the collector boxes to the fan.
This still meant the systems had to cycle in the same manner as the single
tube system, as the fans and the logic were not designed to operate both the
waste and laundry systems simultaneously or independently. The latest systems
are entirely independent and separate, each with its own fan, so that loading
of either system does not affect the other. The double tube system utilizes
either the push button, one bag at a time method, or the key-lock method for
multiple loads.
GRAVITY CHUTES TO VACUUM SYSTEMS
It was also apparent that pneumatic tube systems for moving solid waste
and/or soiled laundry have certain operational problems that must be solved in
providing a satisfactory design.
The first problem already mentioned is the speed of removal of the solid
waste or soiled laundry from the floor. The second problem is whether this
has to be done by special personnel trained to load the chutes, or whether any-
one, from janitor to nurse, can handle the task, and on a completely random
basis; by merely coming up to any chute door, opening it, and depositing in the
proper chute ("trash" or "laundry") as many bags at a time and at any time as
is desired. Thirdly, to be economically feasible the system must move at least
95% of the total waste cube and weights safely and without any cross-contamina-
tion problems. There cannot be all sorts of exceptions as to the type of
waste that cannot be sent through the system for fear of damage to either the
system or the environment and thus must be hand-carried around the system.
A cursory examination of the "old fashioned" gravity chutes show they meet
all the loading criteria we have mentioned. Anyone can load them at any time
and as fast and as much as desired. And further, the loading can be in bags
-47-
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OE as completely loose items. The only limitation on the load descending the
chute is that is is small enough, or secure enough, not to lodge in the verti-
cal chute. If it meets these requirements, gravity does the work and the
load dumps out at the bottom. The mess often created at the bottom is another
consideration altogether. It is off the upper floors of the building.
0»e of the systems studied takes advantage of this thinking. The verti-
cal chutes are simply the "old fashioned" gravity chutes with separate chutes
for aolid waste and laundry. The chute doors and loading ramps inside them
ate similar to those found in other gravity chutes. Some additional features
have teen added. On the waste chutes, the loading door is slightly smaller
than on the laundry chute. Normally, a rubber baffle is placed at the outer
circumference of the vertical waste chute, at the end of the sloped loading
hopper, to prevent any solid waste that may be descending from the floors
above from flying into a chute station when it is being loaded. Further, a
fan downstream in the system creates a slight negative pressure through the
chute at all times by pulling 200 to 300 CFM of air. This prevents contami-
nated air from entering the loading station when the chute door is opened.
At the bottom of each vertical chute is a heavy steel plate termed a
"slide valve." The solid waste or the laundry falls down the chute and lands
OB this plate, collecting vertically in the chute. On a predetermined time
cycle (every few minutes) through the action of a pneumatic cylinder, the
plates slide, or swing open, through the chute wall, one at a time, and drop
thft load each is holding into a short transition section below them. They
then swing shut and the vertical chute is momentarily empty.
The chamber below the valve curves at the bottom into a horizontal tube
of the same diameter on the downstream side; an inlet air line of like dia-
meter enters on the upstream side. When the slide valve dumps its load down,
the suction fan pulls the inlet air against the load, carries it into the hori-
zontal tube and the suction air flow, to the collection terminal at the end of
the system.
Discharge of the chute load is quite rapid (10 to 15 seconds). In the
cycling, one chute at a time is discharged, starting at the downstream end,
timed so that as one valve closes, the next valve opens, until the whole cycle
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(for all chutes) has been completed. Loads from two to three chutes may si-
multaneously travel in the tube to the collection terminal, if the cycling is
programmed in this fashion to expedite movement. Normally the cycling is fig-
ured so that chutes are emptied when the storage load has reached a cubic yard.
As the cycling can be pre-programmed by a time clock, the waste cycle and the
laundry cycle do not have to be the same. For example, in peak periods the
laundry chutes could be emptied twice as many times as the trash chutes.
It will be noted that this is entirely different from the "key-lock,"
full vacuum system described earlier. While the vacuum suction is pulling the
waste or the laundry through the system, there is no vacuum being pulled on
the vertical chute is a gravity-vacuum system. It remains a gravity chute,
but with a negative pressure in it.
Such a system is not problem-free. A bag can break when it hits the
slide valve after the vertical drop. Further, it can contain glass, other
breakable objects, and liquids. Thus, the vacuum pull of such systems is de-
signed so that it can move loose objects, such as broken glass; or it can move
a "plug" such as a single bag or a train of several bags. Observations have
been made of as many as 20 heavy laundry bags being moved simultaneously in
this system. The surfaces of the slide valves are the main environmental haz-
ard. They must be kept clean on a regular basis. This aspect is discussed in
a later section.
These are "double tube" systems. With separate vertical chutes for waste
and laundry, the vacuum, or pneumatic, horizontal tubes are also separate and
usually constructed to entirely different specifications. Normally, the vacuum
is supplied by a single fan for both the waste and laundry lines, on the theory
that the system has enough storage capacity at the bottom of each gravity chute
to permit a cycling sequence to take place over a period of several minutes
without slowing down chute loading. A diverter valve switches the fan suction
to the system (waste or laundry) being serviced in a particular cycle. A but-
terfly valve opens to let in inlet air. The exhauster fan starts and when full
flow is reached the discharge valves open in sequence.
Such a system has much larger loads going through it at one time than the
other systems described, in order to clear the deposits from the bottom of
-49-
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Discharge Valve
Open —, |— Closed
VIEW
Loading
Door —
Chute from
• Floor Abovt
Cover Lock
Finished Floor
FLOP* MOUNTED CHARGING STATION
Pneumatic
Transport Tube
ELEVATION
FIGURE 2. GRAVITY-PNEUMATIC TRANSPORT jYSTEM SHOWING CHUTE STORAGE AND
DISCHARGE VALVE
-50-
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several gravity chutes during a complete cycle. Hence, the collectors at the
end of the line are quite large, usually 3 cubic yards minimum, in order to
hold these volumes. The system is fast, with a capability of transporting
and collecting 24 cubic yards of waste or linen in one hour, in medium duty
operation; or as much as 10 cubic yards in an 8 minute cycle in a heavy duty
operation (the equivalent of 75 fully packed laundry bags of 3.6 cubic feet
each).
SIZING OF THE CHUTES AND TUBE
After years of experimentation in hospitals, it has been determined that
there are optimum handling sizes for bags of both solid waste and soiled laun-
dry. The laundry comes from two main sources: the patient bed linen and
surgical or treatment linen from O.B., O.R., and ancillary areas such as
O.P.D., E.R., Radiology, I.C.U., Recovery, etc. The solid waste comes from a
wider variety of sources, ranging from waste baskets in patient rooms, offices,
and support departments; disposable drapes in O.K.; animal bedding in research
facilities; cartons, packing and crating material, generated from incoming
supplies and equipment; solution bottles found in certain treatment areas;
snack bar, cafeteria, and kitchen containers, paper, cans, and bottles.
Is there a maximum and minimum weight and cube of these items, when bag-
ged for ease of handling, as well as an ideal or optimum size load? Apparently
there is, and several factors enter into the determination.
The first factor is convenience of deposit at the initial stage of waste
generation. Over the years a variety of sizes of waste baskets and trash con-
tainers have developed in hospitals. They are designed to be of the proper
cube to hold in an uncompressed form the amount of waste generated during a
fixed period (8, 16, or 24 hours) in the area they serve: patients' room, of-
fice, public hall, snack bar, laboratory, utility room, etc. Secondly, they
are designed to be loaded gently and by gravity, so that contamination of the
surrounding area by aerosols, or contamination to the people doing the loading,
is kept to a minimum, without shoving and stuffing, without spillages outside
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the container.
With the advent of disposable plastic bags, hospitals started buying
these in large quantities to line their waste containers. The theory was that
this further reduced aerosols and waste handling. Once the container was fill-
ed, or partially so, the entire bag load could be removed and taken away in a
closed condition for disposal. This brought in another consideration for siz-
ing containers. These bags used for liners had to hold a convenient amount in
both weight and cube that one individual could easily lift out and carry to
•one place for disposal.
Obviously, there should be direct engineering relationships between the
diameter of the tubes in any pneumatic solid waste movement system, and the
suction power of the air stream, versus the size or cube of containers and
loaded waste bags, and the weight of an average bag, and the number of bags
that Bust be moved at one time. Too often we have discovered the two sets of
considerations appear to have little connection with each other in the systems
that have been installed.
Under the National Fire Prevention Association's Code, Section 82, grav-
ity waste chutes in a hospital must be 24 in. in diameter in order to take the
bulk of the waste sent down them. This will be discussed further in the sec-
tion on codes and regulations. Pneumatic systems in hospitals have not been
constructed to this size, as it was felt they would be too expensive to in-
stall. The bulk of the pneumatic transport system chutes and tubes are 16 in.
in diameter, some are 18 in. in diameter, a few are 20 in. in diameter. The
NfPA Code states that 16 in. should be "a minimum."
How does this compare with the size of waste loads that are generated and
the waste container liners in use in the various hospital departments?
On an average, waste baskets in patient rooms and in offices measure 11
in. to 14 in. in diameter by 13 in. to 17 in. deep. The average flat dimen-
sions of the liner bags are 22 in. wide by 22 in. long. Bulk trash containers
vairy considerably in size, depending on the location being serviced. The
largest are found in public areas, animal research quarters when bedding is
-------
up to 36 in. wide by 52 in. long in flat dimension, fitting into these bulk
containers as large as 22 in. diameter by 24 in. high.
If the pneumatic chutes and tube system are to be used to remove solid
waste from all sections of the hospital, the containers and bag liners must
be sized to match the tubes. For such an expensive, automated system to be
self liquidating and economically feasible in labor saving cost, it must carry
at least 95 percent of the total solid waste generated. This is discussed in
depth in the section on economics.
The containers and bag liners used for initially depositing the solid
waste cannot be larger than will go in the chutes. It is both a bad sanita-
tion practice and wasteful of labor to have to break down by hand into smaller
bags the waste collected in the initial deposit containers so they will fit
the chutes. Alternatively, the chutes and tube system should be capable of
moving groups of smaller bags such as are found in half-filled waste baskets,
or these can be placed in a larger "chute transport" bag. If there is such a
thing as an "average" trash chute bag, it would be a plastic bag, 34 in. long
by 24 in. wide (flat), which stuffed full and tied would be approximately
15 in. in diameter by 25 in. long, and weigh, leaded, 4 to 14 Ib, depending on
the make-up of this waste.
Hence, there is a minimum size of chute and tube that should be installed
and a maximum size of waste container and bag that should be used, if the hos-
pital is to have a complete system from start to finish. It is now generally
agreed that pneumatic tubes should be at least 18 in. diameter for optimum
loading of bagged waste, and that 16 in. diameter is on the borderline as a
minimum size.
Laundry is generated in different bulk and weight than waste; usually in
larger unit quantities, and for this reason- alone it is most difficult to use
the same chute and tube to carry both laundry and waste successfully. Laundry
from patients' rooms breaks down satisfactorily into a bundle for a complete
bed change, along with towels and gowns, for two patients. This weighs on an
average 8.5 Ib dry and up to 10.0 Ib damp, and it fills a flat cloth bag 32 in.
long by 23 in. wide, ending up as a bagged load 15 in. in diameter by 26 in.
long. Other typical patient linen loads (gowns, towels, sheets) weigh 5.0 to
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15, Q Ib in such a bag. O.K. linen and treatment linen from single procedures
4f mu.ch larger in bulk and weight, with the "average" size bagged bundle 17 in.
i$ diameter by 30 in. long, weighing up to 20 Ib in damp condition. For this
$Qis4b^y contaminated laundry, a large hamper bag with flat dimensions of
2'7> IBU wide by 38 in. long keeps the "stuffing," and possible spread of aero-
,,. Sp a. minimum. It la thus seen that the pneumatic laundry tubes are more
if they ace slightly larger than the trash tubes. The preferred
SOB maximum efficiency is 20 in. in diameter.
STRENGTH OF CHUTES AND TUBE
Having determined the ideal diameter of the tube for the system, along
themaximum weight to be moved in horizontal runs and upward slopes, it
is-tfcen necessary to determine-the suction or air flow required to pull the
hfcayiejst' permissible load over'the planned distance of the system, at the
S9$£d.
-------
light 20 gauge sheet metal and were usually square rather than round in cross
section, for ease of fabrication. The tubes were hung from ceilings or slabs
by threaded bolts, usually into concrete.
This light sheet metal can create problems when a pneumatic system is
used under heavy loads. The major problem is collapsing of the tube or fit-
tings when excess vacuum is pulled on them. The chief cause of such excess
vacuum is the plugging of a tube by bags getting lodged at some point and the
fan continuing to pull against the plug. From the figures given previously,
it can be seen that on the full vacuum, single bag systems the heaviest weight
to be pulled in a 16 in. chute could be a 15 Ib bag of uncompacted waste, or a
laundry bag weighing 18 Ib. In an 18 in. chute, the weights could increase to
17.5 and 20 Ib respectively as the bag diameters are increased from 15 in. to
17 in. In a key-lock multiple loading system, with 12 bags in a train, the
average total weight being pulled could amount to 108 pounds of waste and 180
pounds of laundry in a 16 in. system and up to 140 pounds of waste and 220
pounds of laundry in an 18 in. system, based on average weights transported.
These figures indicate that over a 7 year period, averaging 6 hours use
per day, the fatigue point of the metal would be reached if 20 gauge steel
were used in a 16" diameter single bag system. With a multiple bag system,
16" diameter, this fatigue point would apply to 18 gauge. In an 18" diameter
system, the same condition would apply to 16 gauge and 14 gauge steel respec-
tively.
To give some engineering figures on vacuum being pulled in these systems
and speed of air travel, we find that air travel speeds range from 50 feet
per second to 100 feet per second at the maximum with 80 feet per second proba-
bly an average. The lowest air speed permissible to move a medium sized
waste bag has been calculated at 15 feet per second. To convert these to
vacuum, we find that while many of the fans can pull 9 in. Hg, the average
system operates around 5 in. Hg,with fan cut offs at around 6 in. Hg. It has
been calculated a bag would move and the system could clear at as low as 1.0
PSIg.
This has led to three developments in installing such systems. First,
maximum vacuum pressure for the system is established by the engineers or
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20.
*
u
3
III
O
o
(A
hi
|
Comparing the three commonly used
tube diameters with (1) potential
wall thicknesses (metal gauge) and
(2) potential vacuum or pressure
that can occur in pneumatic trans-
port, the accompanying curves in-
dicate that to withstand the aver-
age maximum 4.4 P.S.I, system
pressure, a 20" tube should be
constructed of 13 ga. metal or
heavier; 18" tube of 14 ga. or
heavier; and 16" tube of 15 ga.
metal or heavier.
PS.I. AVERAGE MAX
FAN CAPACITY
,-f 24 PS I AVERAGE
*) FAN OPERATING
PRESSURE.
20" D1A
18" OIA.
I 2 3456789 10
VACUUM IN PS I
FIGURE 3.
AU.OWABLE VACUUM FOR VARIOUS DIAMETERS AIJO WALL THICKNESSES OF PNEUMATIC TUBES
SUPPORTED EVERY 8'
-56-
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consultants and, after installation, the entire system is tested against this
by artifically plugging the inlet air. All elements must pass this test before
the system is accepted. Secondly, relief valves are being placed at the end
of the system immediately before the fan. When vacuum reaches a predetermined
danger point, the valve opens to atmosphere to avoid both fan motor damage and
collapsing of tubes. Thirdly, specifiers have begun calling for much heavier
tube and fittings than 18 gauge steel and this entails quite different fabri-
cating and coupling methods. The calculations given in curves in Fig. 3 show
engineering requirements that must be met.
Mild steel can be lock-formed to manufacture a tube in 18 gauge thickness,
and, with heavy equipment, even in 16 gauge thickness. Heavier tube walls than
this are normally seamless welded.
The gravity-pneumatic systems use up to 1/4" wall thickness in seamless
pipe or tube for pneumatically transporting waste, and with round cross sec-
tion fittings in wall thicknesses up to 3/8 in. However, as the vertical
chutes in the gravity-pneumatic systems do not have a vacuum pulled on them,
they can be built of much lighter metal than the tube at the base that trans-
ports the waste under vacuum. Normally, the chutes are built to the same
strength specifications found in other top-grade gravity waste chutes (14 or
16 gauge).
As the fittings (elbows, Y's, tees) appear to be the most subject to
abrasion in waste movement, it is now common practice that they be specified
at least- one metal gauge heavier than the straight lengths of tube, and always
in round cross section to provide smooth air flow.
The heavier wall welded tube requires entirely different coupling methods.
The original Swedish designs for heavy-wall tube called for butt welding each
length to the next. This proved tc be far too expensive. Further, weld
flashes inside the tube were very difficult to grind smooth. Unless this was
done, bag ripping could result.
It must always be borne in mind that the most successful pneumatic systems
have the most even and smooth inside surfaces to provide excellent air flow
without turbulence and complete absence of bag tearing. In this respect,
they are no different from small pneumatic message tubes. This means that
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A rather wide range of methods
is used to join together or couple
the straight and curved tube sec-
tions. These include, for the light-
er gauge tubes, formed flanges with
bolt holes held together by as many
as 15 bolts, with gaskets between to
ensure air-tight seals; flanges that
ate covered on the exterior by a
clamp ring to provide for rapid as-
sembly and disassembly; and various
support strapping devices.
For the heavier wall tubing and
fittings, the thickness of the tube
permits machining or chamfering the
edges of the metal and welding the
two sections together. In addition,
external sleeves can be cemented or
welded on to the tube to increase
the rigidity of the joint. Ball and
docket methods have also been used,
combined with welding.
The smoothness and concentricity
of the joins are absolutely essential
to avoid bags ripping in transit. It
is extremely important that inspec-
tors be present during installation
to see alignments are made properly.
I.-FLANGE AND BOLT COUPLING METHOD-FOR
TUBING 16 GA. AND LIGHTER
yaaKKiga-rafftyj
k
4)
m
i
K*™«™™^
(
2-CLAMP COUPLING METHOD-FOR TUBING IS
GA. AND LIGHTER
Si««v» Waitle*
Or Glued
Air F
s- SLEEVE COUPLING METHOD-FOR HEAVY
WALL TUBE
Wold
4-BELL AND SOCKET COUPLING METHOD-FOR
HEAVY WALL TUBE UP TO >/*"
FIGURE 4. COUPLING METHODS USED IN PNEUMATIC TUBE SYSTEMS
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when two tubes, or a tube to a fitting, are joined, the alignment must be as
perfect as possible. Slip joins that are externally welded, or bell and socket
chamfered joins, provide this type of alignment in all seamless welded tubing
that is 14 gauge and heavier in thickness.
Despite the fact that these are pneumatic systems with a powerful vacuum
in force in the tube, the designers are extremely cautious when it comes to
raising waste vertically. This is based on experience in the sort of items
found loose in these waste systems (such as a 4-ft length of steel pipe).
They prefer to rise vertically in slopes not exceeding 30°, with clean-out
ports at the bottom of such risers for the removal of overweight solid objects
that may be put in the system.
FIRE DAMPERS
One part of the tube system still presents a problem. Codes require
fusible link fire dampers wherever the tube penetrates a fire wall. This
means an actual gap exists in the smooth tube wall. At this point, a turbu-
lence is always created in the air stream which instantaneously balloons out
the transport bag or tends to hurl loose waste particles in the opening. It
is essential that such dampers be well constructed, with no sharp corners in
the interior surfaces, and that the fusible link and damper holding device in
.no way projects into the interior of the tube in a way that could rip a waste
* bag. An inspection of these devices reveals that much further thought should
be devoted to their design and construction. Too often the latches have
broken from vibration and closed the fire damper, causing serious plugging of
the system.
The concern for spread of a fire is not from a fire starting within the
pneumatic system, but rather one starting in a room and spreading through a
fire wall. The fire could melt thin wall tubing and pass through the fire
wall, melting further tubing on the other side and hence spreading to adjoining
areas. If this is the logic, it would appear more desirable to place the
fusible link on the exterior of the tube and a much heavier metal and a
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Wall
Tub*
Fusible Link
Promt
Tub*
Handle To Pull Back
Heavy Plato Fire Damper
Spring To Keep Tension
And Pull Down When Link
Melts
Sweep Button Switch To
Indicate Damper Has Closed
FIGURE 5. FIRE DAMPLR DESIGN
ELEVATION
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different guillotine door device than currently used. The drawing in Fig. 5
is a suggested approach that appears practical. It has the further advantage
of permitting reopening and fastening the door from the tube exterior.
TUBE AND CHUTE HANGING METHODS
Another extremely inportant aspect of installing such tube systems is the
method of hanging or fastening the assembled tubing and fittings to the build-
ing structure. For years, arguments existed on small message tube systems as
to whether the lines should remain flexible and move as the carriers traveled
through or whether they should be mounted rigidly.
On the large diameter (16 in. and up) pneumatic waste and laundry tube
systems, there is no argument. With potential weights of over 18 Ib in a
single laundry bag, traveling at up to 4800 ft per minute, the consensus is
that the tubing must be held rigidly to reduce noise level and prevent fatigue
at all joins. Tube hangers must be of sufficient strength to prevent shearing
from metal fatigue and well fastened into solid concrete in such a manner that
they cannot vibrate loose; and installed as frequently as one every four feet
of tube length.
Chutes and loading hoppers also must be mounted rigidly and supported at
each floor level to the building structure to avoid fatigue from the "bounce"
effect of a heavy load tumbling downward. This also applies to collectors
and diverter valves.
SYSTEM COATINGS AND ABRASION
Three types of considerations are involved in coating the tubes and
fittings used. First, there must be moisture protection for the tubing if
it is buried below ground and subject to water attack. While stainless steel,
rust-proof tubing has been used in these areas, it is limited to the lighter
metals of down to 16 gauge and is quite expensive. A more common method is to
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wrap or coat mild steel tube for corrosion protection in accordance with AWWA
specifications.
The second consideration concerns sound deadening of exposed pipe and
fittings. Various materials such as fiber glass or magnesia are used to wrap
the pipe after installation, in thicknesses up to 2 in. and densities up to
3 Ib.
Thirdly, the interior surfaces of mild steel tubing are often coated
with galvaneal or epoxy paint to ensure a rust proof lining, particularly
with laundry tubes.
Abrasion of the tube has been discussed at considerable length by the
designers of these solid waste systems, both in the United States and in
Europe. A mixed bag of waste can easily contain as high as 25% glass which
is subject to breakage, and total waste from a hospital can contain as high as
10% abrasive material—glass, metal, etc. In Sweden, abrasion tests on tube
elbows, of a radius three times the tube diameter, measured tube wall erosion
as high as 1/64 in. per year. To combat this, the latest designs request radii
in bends of as much as five times the tube diameter (which cuts the erosion
figure in half); with a minimum of three times. If the 1/64 in. or .0156 in.
of erosion per year holds true, 20 gauge sheet steel is only .0368 in. thick,
and hence could wear through in slightly over two years at the erosion point.
Fourteen gauge at .078 in. would last five years, and 8 gauge would last 11
years.
Several light gauge systems carrying trash have been installed in the
U.S. and do not appear to show wear this drastic. However, conservative en-
gineering indicates that 14 gauge metal is preferred as a minimum for tube
elbows and that, wherever the architectural considerations permit, radii be
five times the diameter of the tube and never less than three times the
diameter.
DIVERTER VALVES
Single tube systems that handle both solid waste and laundry must have
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diverter valves to direct either the waste or the laundry to the proper col-
lector box at the end of the line. These have been a source of problems in
this system design. If the operating relay hangs up, the valve may not swing
into proper position. This also applies if the air cylinder operating the
valve malfunctions. Further, the valve must swing shut completely to avoid
line leakage and particles of trash getting into soiled laundry. The valve
interior that shifts to divert the load must be designed and constructed so
that loose paper or linen cannot jam it at the edge, or lodge on it and
prevent it from closing tightly.
The latest designs in such valves appear to be much more efficient. In-
stead of a plate swinging over within the tube to direct the flow, an entire
inner tube swings over, ensuring a complete continuation of the tube system.
A recent test, in which the older style plate-type diverter was replaced by
the tube type, showed a considerable increase in vacuum pull in the system,
indicating the increased efficiency of the new style valve and lack of line
leakage.
COLLECTOR BOXES
As described earlier, the bagged or loose solid waste and laundry is
carried to a collector box, hopper or tank at the end of the transport tube
line, and the air stream continues through a port in the box to the suction
fan. The material being transported hits the interior of the box at full
speed, usually entering into it at a speed of 80 ft per second or 4,800 ft
per minute. This is approximately 55 miles per hour. When a bag of laundry
weighs as much as 18 Ib, or when a bag of waste contains heavy glass or
•etal, the shock to a square box is fairly substantial. Further, every at-
tempt is made to keep the effluent air, exiting the box to the fan, as free
as possible from lint, liquids and debris. Screens protect the outlet port
for this purpose and they, in turn, must be protected from either being damaged
by the blows from bags entering the box, or from flying debris clogging them.
At the bottom of the box are doors that open at the end of the transport
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cycle to let the solid waste and laundry drop by gravity into a container,
compactor, cart, etc. below. The rubber gaskets on the doors, providing an
air seal, are a major maintenance item. Examination of maintenance records
has revealed that the hinges used on collector box doors were a weak point
subject to frequent shearing. It would appear that heavier duty and continous
hinges should be used.
Hie first collector boxes were not sophisticated in design and were
originally used only for laundry. They were ruggedly constructed of heavy
plate and normally accepted a single bag at a time. As solid waste systems
became more common, it was seen that a collector box that worked well for
laundry did not necessarily serve solid waste as well. One of the main prob-
lems in waste was bag breakage and glass breakage when hitting the collector.
Secondly, there is a tremendous variation in weight between the various ele-
ments in the waste, ranging from light paper or plastic films to heavy metal,
glass or wood. This makes the separation process difficult between the drop"
out of the waste and the discharge of clean effluent air to the fan without
clogging the debris screen with "fines," or lighter particles of paper and
plastic in the waste.
As a result, the designers turned to principles used in industry and
introduced either cyclone inertial separators, or widened discharge tubes in
the collector boxes. With the cyclone separator design, the box has a cylin-
drical top and conical bottom. The cyclone designs used as waste collectors
at the end of the pneumatic tube systems work slightly differently from
standard industrial cyclones.
The waste enters at a tangent, whirls around the circumference at the
top and works its way inward and down at a reduced velocity. The downward
notion of the air drives the trash, including fines, to the bottom of the
cylinder. Here it is received into a middle section by pneumatically opera-
ting doors. On a timed cycle it is dropped out of this by a second set of
pneumatic doors into a compactor bin or other receiver below the collector.
The effluent air leaves through a flared tube at the top of the cylinder with
a much wider opening than that in which the air stream entered the collector.
This has the effect of reducing the escape velocity in proportion to the
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Flared Outlet To Reduce Air
Velocity
Electrical Conn.
For Control Circuit
Air Cylinder
'---£
Collector Doors
>\!
\*
Air Cylinder t
A"
Air Sealing Gasket
Collector
Doors
Air Cock
— Continuous Hinge
CYCLONE TYPE BAGGED OR LOOSE WASTE
COLLECTOR FOR LARGE VOLUME OR MULTIPLE
LOADING SYSTEMS
FIGURE 6. TYPICAL DESIGNS OF SOLID UASTE COLLECTOR BOXES
BOX TYPE BA6SED WASTE COLLECTOR
FOR SMALL VOLUME. SINGLE BAG SYSTEMS
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ratio of the two openings.
Other collectors employ a physical separation of the effluent air from
the fines and light waste, that could be either carried through in the escape
air to the fan, or could clog the exit screens. The most common principle is
to greatly enlarge the exit opening in relation to the size of the entering
air stream, reducing exit air velocity to allow the lighter waste to descend
by gravity instead of continuing with the exit air.
Mathematically this can be illustrated as follows. Assuming the diameter
of the inlet or transporting pipe to be 18 in., this is 1.77 square feet of
area. It has been determined that a good air exit rate to avoid screen clog-
ging is 4 ft per second. This is at l/20th the rate at which the solid waste
air stream enters the collector when it is traveling at 80 ft per second.
Therefore, to achieve the reduced velocity, the air would have to escape
through a flared tube in the side of the collector that is 20 times the cross
section of the inlet pipe (1.77 square feet), or 35 square feet, which even-
tually would taper down to the regular tube size of 18 in. for return to the
fan. To avoid most light particles being caught in the effluent air stream
and clogging its protective screen, it is probable that the exit port would
have to be twice this size, reducing air flow to 2 ft per second.
The present boxes and cyclone type collectors are a compromise in thic
direction. Drop-out of the trash by gravity is quite gentle and the amount
of light material clogging the debris screens has been drastically reduced.
Automatic compressed air blow-down systems are being added to keep the
screens free of the remaining debris.
THE FAN BOOM
From a design and construction viewpoint, the fan room and all its
equipment is one of the most critical aspects of the system. It is essential
that the room be adequately ventilated and that the temperature not exceed
80 F during operation, in order to protect the electrical equipment installed
in the area. Despite sound attenuation, the noise of the fans and the air
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exhaust is substantial and potentially dangerous to the human ear. The entire
room should be constructed of dense enough walls, floor, and ceiling to prevent
sound transmission. Doors must be large enough for equipment removal in case
of replacement and should be sound gasketed.
Two types of fans are in general use: the enclosed, positive displace-
ment, centrifugal, turbine type exhauster, operating at relatively close tol-
erances, and the much more open, loose tolerance, typical materials handling
type or exhaust fan. Motors in ranges from 100 to 250 HP are used to drive
these fans. Adequate transformers and feeder lines are essential to eliminate
voltage drop with these large motors.
Regardless of the type fan, they are heavy and, when running at full
speed under load, create a considerable vibration. It is standard practice to
mount the fan and motor assembly on vibration isolator pads, inertia blocks,
spring type isolation bases, etc. It is essential that there be sufficient
size and mass to fulfill the purpose intended.
Maintenance of the fan and motor has some special features to it. In
many installations, the fan bushing has been attached to the motor shaft by
heat expanding the shaft for positive union. Cases are reported where it has
been almost impossible to separate these at the site and, in order to perform
motor maintenance, the entire motor-fan assembly has to be removed. For motor
maintenance it is important that the room be designed to facilitate such re-
moval .
FILTERS
While the positive displacement fans are more efficient than the more
open materials handling fans, due to close tolerances the blades must be pro-
tected from waste particles being carried through them. It is good practice
to place a 2 micron bag or roll filter ahead of the fan to protect the blades
from such airborne contaminants. This has the further advantage of cleaning
the exhaust air, before it reaches the fan, of most micro-organisms and thus
protecting the environment from the fan exhaust. The filter must be exceed-
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ingly well constructed, capable of resisting the maximum vacuum created by the
fan. Also, it adds considerably to the air resistance, even in its clean
state (as much as 7 in. water), resulting in the fan having to be sized large
enough to compensate for this.
With the more open tolerance exhauster fans, some manufacturers claim
fife-filters are not required to protect the blades. This may be a risky claim
Where pre-filters are not installed, many maintenance men have discovered lint
and waste materials adhering to the fan blades to the point where the fan, re-
volting at over 3,400 RPM, was thrown out of balance. In one hospital, the
motot base mounting bolts sheared and the base of the housing cracked from
the excessive vibration. It is strongly recommended that pre-filters be
installed ahead of the fan to catch both fine particles and heavier debris
that may be in the air stream. They must be easily removable for maintenance
and strong enough to stand both the air pull and debris in the air. The same
requirements of 2 micron filtration should exist for these more "open" fans as
in the positive displacement fan. This filtration for environmental protection
could be incorporated in the debris filter ahead of the fan or in a second,
bacterial filter on the fan exhaust side.
SOUND ATTENUATORS
The large, heavy-duty exhauster fans and motors are obviously not noise-
less when operating. An extremely large volume of air is being exhausted
outside the fan room. A good rule in designing such systems is to ensure that
a sound attenuator of adequate design and construction is installed after the
fan so as to achieve a total noise level of less than 60 decibels on the "3"
scale when measured at the exterior walls of the building housing the fan
assembly. The higher the octave band, the lower the maximum decibel rating
should be, in order to prevent annoyance to patients, staff, and visitors.
the following gives the allowable maximum noise levels suggested for various
octave bands.
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OCTAVE BAND MAXIMUM LEVEL
(cycles per second) (decibels)
37-75 67
75-150 62
150-300 54
300-600 47
600-1200 41
1200-2400 35
2400-4800 29
4800-9600 27
RELIEF VALVES
An integral part of the fan assembly and tube system should be a relief
valve placed in the tube before the fan. The purpose of this is to avoid
either fan and motor damage; or tube collapse (if the lighter sheet metal
tubing is being used) when for some reason the system plugs and creates a
vacuum higher than the maximum operating design. Such a valve is normally
connected by a tube to the outside air and when the maximum is reached it
opens and the fan pulls this air. Alternatively, a switch can activate to
shut down the exhauster fan in case of too much vacuum being pulled.
FEED AIR
It can be seen from the previous discussion that the air feeding the
system, whether from roof dampers in a full vacuum system, or from basement
level tubes in a gravity to vacuum system, should be dry and clean. In ex-
treme northern climates during winter this has occasionally created problems
when the inlet air drawn through roof dampers is as cold as -30 F. and is
entering a building with temperatures of 70 F. Moisture and condensation may
become a problem with the rapid rise in temperature and in severe cases may
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require pre-heating of the air.
COMPRESSED AIR SYSTEM
Host of the moving parts in the system are activated by rapidly moving
compressed air cylinders. This applies to roof and fan dampers, inner chute
doors, collector box doors, diverter valves, and slide valves. It is essential
that the compressed air be filtered and lubricated and that all lines and
valves be made of rust-proof material. The usual pressure in this system is
125 p.s.i.
This usually requires a separate air compressor used exclusively for the
pneumatic tube system. In many installations, it has been seen that the
systems manufacturer under-calculated the total CFM of air required and the
size of the compressor, with the result that the action of air valves was
•lover than necessary. Other design factors that have been discovered is that
all air cylinders should have individual oilers. Lov points in the compressed
air liaes should have bleed-offs to drain out any collected moisture. In
northern climates with protracted periods of below zero temperatures, air
dryers should be installed in the line, effective up to -60 F, to prevent the
air freezing exposed cylinders such as in roof dampers.
ROOF AIR INLETS AND DAMPERS
On the full vacuum system, the inlet air is obtained from double blade
gooseneck shaped vents installed at the top of the vertical chutes through
the roof and projecting above the roof level approximately 48 in. The dampers
in tills are activated by compressed air for opening and closing.
In the gravity-pneumatic systems, the vents appear similar in design and
have a weather-tight vent relief terminal cap. They also contain a barometric
daaper to maintain 1/4" negative pressure in the vent and a fusible link in
the top door in case of chute fire.
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SPRINKLER SYSTEMS
From actual observation of tests with gasoline-soaked rags that were
ignited and thrown into a full vacuum system, it appears highly doubtful that
the tube system will support open combustion. However, a small smoldering
fire could possibly continue inside a bag of trash. For this to lead to a
fire in the system, there would have to be a plug or a system shut-down, as
on the average the burning material would be dropping cut of the waste col-
lector in 40 seconds, much less remain in the vertical chute. With a gravity
to pneumatic system, the situation is different and there can be storage on
top of the slide valves at the chute bottom for a prolonged time period.
Half inch sprinkler head stations are usually installed in both types
of systems at the station below the roof line in the vertical chute and at
every other floor, or every floor, descending to the lowest. In addition,
occasionally sprinkler heads are installed in the trash collector boxes.
Sprinklers are normally fusible link activated.
LOADING STATIONS
The loading stations are normally faced with a stainless steel panel
from floor to ceiling. There is usually a maintenance door as well as the
chute loading door. These must be U.L. Class "B" labeled, rated at 1-1/2
hours at 250 F. Station doors are either stainless steel or aluminized steel
and are normally side-hinged and self-closing. Bottom-hinged foot pedal
operated doors are used on the waste chutes of gravity to vacuum systems.
Regardless of the hinge system, bottom hinged doors can present problems in
that personnel may rest a heavy bag on an opened door and spring it. The
majority of these chute doors have a 36 in. height from the floor. Some of the
gravity-pneumatic chute doors are as low as 24 in. from the floor to the
loading sill. The buck material is usually stainless steel to ensure cleaning
ease of the door frames.
Maintenance door fasteners, in most systems, are merely a series of
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screws, attaching a maintenance panel to the buck. It is felt that for pre-
ventive maintenance this is a poor method and should be replaced with a hinged
panel and a lock and key to open it, or some other quick opening, tamper-proof
method.
Signal lights are normally positioned in the wall panel, always a red
"In Use" light, to warn prospective users that, either the door is locked, or
the inner hopper door is open and unavailable. Alarm lights or buzzers are
rarely placed at the chute doors. A central maintenance location is preferred.
However, there should be an "Out of Order" flashing light at each station to
warn the operators of a shut down, whether due to maintenance work or a
breakdown.
Most important, prominently displayed over each loading door is an
identification sign such as "Trash" or "Solid Waste"; "Linen" or "Soiled
Laundry." It is essential that these signs be distinctive and boldly lettered.
In cone hospitals, instruction signs or plates are placed over or adjacent to
the loading doors.
CLEAN OUT PORTS
We would like to report that plugs never occur in pneumatic transport
systems, but unfortunately this is not the case. Virtually all such tubes
get plugged with linen and trash from time to time, for a variety of reasons,
ranging from operator carelessness in using the system, to mechanical-electrical
malfunctions. In single bag systems, plugging is usually caused by operators
attempting to override the system and force multiple bags through simultaneous-
ly. There are two types of plugs experienced. The first is self-clearing,
when the removal of a bag or two and the applying of full fan vacuum will allow
the plug to free itself. The second is more serious: the entire plugged load
aust be removed by hand ("fished") from a clean-out port, or a chute station,
or a collector at the end of the line. With 500 feet of horizontal tubing,
this could take time.
This explains the necessity for clean-out ports in horizontal tubing, or
-------
where horizontal runs transfer to upward risers. To have to remove sections
of tube to clear a plug is an extremely expensive job for the maintenance de-
partment .
When installing clean-out ports, it is essential that they be constructed
in such a way as to not weaken the tube wall; that the interior tube surface
be completely smooth and free of projections where it joins the clean-out
port; and that each port be large enough to permit the removal of a full bag
of solid waste or laundry.
CONTROL SYSTEMS
The heart of the electrical operation of all pneumatic waste and laundry
transport systems is the central control panel. This monitors all loading
stations and supplies the logic, through a succession of relays and breakers,
that sequences the opening and closing of all pneumatic cylinders and valves,
which in turn control the routing of air (and hence material) through the
system. It cycles the stations and provides the memory circuits for determin-
ing the order of priority for such cycling (either pre-programmed or first
come-first served). It reads the pressures and vacuums in the entire system
and protects it from damage due to excessive build-up by supplying "fail safe"
shut down actions.
A master switch controls power to the control panel and through it the
entire system. In addition, there are usually separate switches to turn the
exhauster fan on and off and to run it manually or in automatic sequence.
There is usually a high pressure safety switch which activates automatically
a sensor when vacuum exceeds allowable limits. This throws open the
relief valve and/or shuts down the exhauster fan. Before the system can be
returned to normal operation, this switch has to be reset after the cause of
excessive pressure has been corrected.
Various types of memory systems have been designed into such a control
panel and each year the electric designers have made these more sophisticated,
up to the point where mini-computers are now being considered. As the systems
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get more complicated by building them with increased number of stations? the
aeed for speed and accuracy in the circuitry increases. The bulk of the full
vacuum systems have memory systems constructed with stepping relays to activate
the station unloading. Originally, these were quite simple. Whoever pressed
ttoe first station button sent his signal to the first activating relay. The
second button pushed sent its signal to the next relay, where it was held until
the first sequence was completely cleared; and so on through a potential of 50
or acre stations. Activation had to take place by throwing or pushing switches
at the station doors.
As we have seen earlier, with the gravity-pneumatic systems this is not
the case. Adjustable time clocks run the system by determining when the valve,:
should open and they open and discharge into the air stream in a predetermined
sequence, whether they contain a waste load or not.
As the full vacuum systems have been installed more recently, they have
leaned in this direction and cycled in a predetermined fashion. However, only
the loaded stations operate. They usually cycle one chute at a time in se-
quence, such as all the loaded laundry stations for the entire system, then
all the loaded waste stations. One problem that has been noticed is that if
the opening of the station inner doors start at the bottom and work up to the
top in a given chute, the inner door must close on time and completely to pre-
vent a bag from the one above it catching on it and creating a jam. Sequencing
from the top down has proven desirable.
SUPERVISORY PANELS AND ALARM SYSTEMS
From rather simple and crude beginnings, during the past five years the
supervisory panels have improved considerably. They now show the complete
schematic of the system and the exact status, at a point in time, of all major
elements, by means of small lights superimposed on the schematic plan.
One of the hospitals studied constructed its own panel, complete to the
point where the approximate location of a plug in the system can be identified
iastantaneously.
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In the complex supervisory panels, alarms are included, either in the
form of flashing lights or buzzers, or both. The panels monitor items such
as incomplete cycles, loading hopper doors not closed, collector box doors not
closed, diverter valves open, roof dampers open, low or high pressures in the
air flow, high temperatures in fan exhaust, slide or butterfly valves not
opening or closing, dust filters loading up and exerting too much air resist-
ance, etc.
The monitoring of supervisory panels and the resetting of switches,
relays, timers, etc. in the control panel is the function of the Maintenance
and Engineering Department. It is therefore essential that these elements
of the system be installed where they can be reached easily by maintenance
personnel or are under their constant and convenient surveillance. Too often
architects and mechanical engineers designing the structure are inclined to
"bury" such panels.
CYCLING TIMES IN PNEUMATIC SYSTEMS
The time that it takes a pneumatic system to perform a complete cycle
depends on several factors: the design of the system, whether full vacuum
or gravity to vacuum; whether it is a single or multiple bag loading design;
the speed of travel of the material as determined by a combination of the
suction force and the weight being transported; the length of total run from
the collectors to the station farthest away from each collector; and the
pauses or delays built into the control panel by the manufacturer for sequenc-
ing the various components in order to be sure that valves, doors and dampers
have time to open and close without jamming the material being transported.
It should be realized that cycling is on a "constant" time, not a
"variable," in the design of virtually all single bag full vacuum and all
gravity to vacuum systems. What this means is that the time is fixed by the
manufacturer, regardless of the length of run. If a bag can be transported
in 10 seconds from the station nearest the colledtor to the end of the line,
and it takes 50 seconds to transport a bag from the station farthest away
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from (the collector, then the system is timed for all cycles at 50 seconds
in order to achieve simplicity in the control system. With a key-lock,
multiple bag system, overriding the normal time cycle of a single bag pro-
cedure, the operator has control over the length of the cycle, as he manipu-
lates the station door switch.
In a full vacuum system, timing of the length of run starts when the bag
drops out of the loading hopper into the vertical chute. With full vacuum,
and in typical hospital height buildings, the bags do not descend the chute
that much faster than in a straight gravity condition. Assuming a ten-story
building with basement loading stations and with floor-to-floor heights
averaging 13.5 feet, the total vertical drop might be 141 feet. In a gravity
drop, a bag would take at least 2.5 seconds to cover this distance, assuming
it could fall freely. Under an air pull that gives a travel speed of 80 feet
per second, it would take 1.75 seconds.
Horizontal speed at a theoretical 80 feet per second would be 3 seconds
for 240 feet, up to 12 seconds for 960 feet. The 80 feet per second is rarely
maintained over the full run due to line losses, resistances, and slippages,
so it is normal to add 25 percent to these times.
The balance of the time in the cycle is used up in activating the various
components. These segments of time must be added to the travel time in order
to arrive at the total cycle time. In the average full vacuum system, they
are as follows:
Seconds
Opening of air inlet damper 1
Opening of fan damper 1
Allowing air to achieve transport
speed 2
Opening of inner hopper door and
bag dropping 2
Shifting of diverter valve 1
Closing of inner hopper door 1
Closing of all dampers in sequence
after allowing for travel time 3
Opening of collector doors to allow
bag to fall out 2
Closing of collector doors to per-
mit recycling 2
Total sequencing time 15
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Hence, it can be seen that the sequencing of the system components can require
as long as, or longer than, the travel time of the material. Timing of most
full vacuum system substantiates this. An "average" total cycle takes approxi-
mately 30 seconds.
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FINAL REDUCTION AND OFF-SITE REMOVAL
The care and precision of in-house transport of solid waste directly
affects the health and safety of the staff, patients, and visitors in a hos-
pital and equally affects the operating budget of the institution. The most
serious effect on the environment and on the health of the community starts
at the "end of the line," after the loose or bagged waste has been transported
from the floors to some central location, such as the loading dock of the
hospital, and must be removed off-site, with or without further treatment.
Management of hospital solid waste must be viewed as a total problem
that consists of a series of steps in a complicated system. It starts with
the disposing of a waste product in a trash basket or container in a patient
room or support area, and is not solved until the residue waste (loose, com-
pacted, ground, dumped to sewer, or incinerated) is safety treated in some
location remote from the hospital, such as landfill or sewage treatment plant,
All hospitals are subject to various external constraints, designed to inter-
face with satisfactory in-house final treatment and reduction methods; and
these must be compatible with safe off-site removal that ensures satisfactory
public health and environmental conditions. A subsidiary consideration is
that these final treatment and removal procedures also must be economically
feasible: operating costs must be kept to a minimum.
As can be seen from the chapter that analyzes the make-up of hospital
waste, 40 percent is potentially "hazardous." It consists of fomites capable
of transmitting pathogenic organisms; pathological specimens; material from
known communicable disease cases; disposables that are hazardous in nature
from a secondary use viewpoint (plastic items, syringes, needles, and sharps);
potentially infectious material due to contact with wounds, burns, or used in
treatment of patients' surgical incisions; potentially infectious clinical and
research laboratory wastes; human or animal fluids, secretions, tissues, and
feces, and the disposable containers that hold these; toxic, flammable,
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corrosive, explosive, and radioactive substances that have detrimental effects
on people, equipment, and property; and the solid waste that in the process of
assembly and removal may either become contaminated by such known infectious
and hazardous wastes and hence become infectious or hazardous itself; or is
originally infectious or hazardous to a degree not clearly established.
The in-house final collection and treatment systems must consist of
adequately designed and installed equipment and carefully managed operational
practices, that completely avoid transmission and contamination problems
among the hospital personnel. These systems must also ensure that the waste
is satisfactorily treated, reduced, packaged, and containerized so that it
can be moved to the off-site point of final disposition, safely and completely.
With waste loads skyrocketing and exceeding 11 pounds per patient day in
many urban hospitals, the sheer volume to be managed, and the time and expense
to manage it, is too often encouraging "short cuts." The cry of "get it away
from patient, staff, and visitor areas and down to the dock and away from the
hospital" is heard daily. In the process, safety measures can be ignored.
The hospital staff, the community health, and the environment can all suffer
accordingly.
Not only is hospital waste environmentally hazardous in varying degrees,
it is proving more expensive to handle as each year passes. As can be seen
from the chapter on the economics of hospital solid waste management, the ex-
pense is mounting at every step in the process, from original pick-up, through
in-house transportation, through final collection, reduction, and treatment,
to off-site removal.
VOLUME REDUCTION
When a bag of solid waste drops out of a collector at the end of a pneu-
matic tube line, or is dumped into a hauler's trash truck by hand, it is
immediately apparent that in the total volume there is about 20 percent
material and 80 percent air; that mechanical compression or compaction could
give up to a 5 to 1, or 80 percent reduction in volume by simply squeezing
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out all the air and leaving the material. As off-site hauling contracts are
based directly and indirectly on the volume of waste being hauled, as well as
the weight, compaction or other volume reduction techniques reduce hauling
costs.
A second examination of the original waste reveals that it is in all
sorts of shapes and sizes, from flimsy paper and plastic sheets, through heavy
cardboard and crating material, to strong containers made out of glass and
sheet metal. And all of it is capable of being reduced to fairly uniform
particle size by feeding it through the proper type of attrition mill or
"hogg." It is discovered that, if it is decided to transport the ground
waste to another area on-site, now that it is in a more or less uniform size
particle, it lends itself to various materials handling techniques that would
not accept the unground material. It can be handled and transported pneu-
matically in sealed, small diameter tubes; or mechanically in screw conveyors
that are completely encased to avoid atmospheric contamination by the moving
waste. If the ground waste is compacted at some point, it is discovered that
a further volume reduction can be obtained, against compacting the unground
waste.
A third examination of the total hospital waste delivered to the final
in-house collection point reveals that 92 percent of the bulk is combustible
under proper conditions, and after combustion the ash residue is quite small.
CLEANLINESS IN THE CENTRAL WASTE COLLECTION ROOM
From an examination of the solid waste central collection points in
dozens of hospitals, it can be stated categorically that such an area can be
as free of litter, as free of odor, as free of cross-contamination as is the
lobby of the building. In fact, the environmental standards between the two
areas in a hospital—public lobby and central waste collection area—could b<;
the same, with proper foresight. To achieve this at the end of the line,
design standards for equipment and the placement and interfacing of mechanical
items are extremely important. Equally important are the rules for loading
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the equipment, and the managerial supervision over the people doing the loading
in those instances where it is hand fed.
Cleanliness, lack of spillage, and freedom from odor can be achieved
through sensible, well thought-out, and designed mechanization; and they can
be achieved through rigid control over the actions of all personnel entering
the area and hand loading solid waste into collection and/or reduction devices.
Both tight mechanical control and human control are essential.
Design and construction of solid waste collection and reduction rooms
absolutely must follow certain rules if environmental problems are to be
avoided. The most important rule is that once waste reaches this point it
should no longer be exposed to atmosphere, except in the case of a mechanical
breakdown enforcing a divergence from the standard system. At all times, it
should be in tightly covered bins, containers, conveyors, or machinery so that
it does not spread throughout the room or the surrounding area. Most institu-
tions have not paid enough attention to these points. In the hot summer
months, odors from decomposing wastes are noticeable; loose waste spillages
or "float" and liquid spillages can be seen.
COMPACTORS
Stationary compactors for the end of the line are designed to reduce the
volume of waste that must be hauled off-site and thus reduce hauling costs.
With the proper container or sealed mobile bin doing the hauling, the result
is an environmentally safer trip, hopefully with no spillages or leaks along
the way. A final advantage is that in the process of compaction much of the
waste is destroyed, or at least so mixed with other waste that it is difficult
to salvage it for secondary use, and thus create health hazards.
By 1972, over 20 manufacturers were merchandising over 150 different
models of stationary compactors that can be installed in the central waste
collection terminals of hospitals. The rate of compaction varies from 2 to 1
to 5 to 1 depending on the design, the size of the compaction bin, and the
strength of the unit. The designs differ considerably, ranging from units
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with a high receiving volume and quick action that give only a modest amount
of compaction, to units with extremely high compaction rates but much slower
cycling time.
Sizing of the compactor depends on two direct considerations: the total
quantity (cube) of waste being generated and the frequency on which it is
desired to haul the compacted material off-site. The indirect consideration
is the architectural space in which the compactor and hauling bin must be
installed. In virtually all hospital installations the compactor is station-
ary. It is close-coupled to a closed steel container. The compactor contains
a ram or similar device that forces the waste into the container, reducing the
bulk as it compresses the waste. When the container is full with compacted
waste* it is connected to a truck or tractor and hauled away.
Compactor containers used in hospitals are fairly large, on an average
ranging from 20 to 40 cubic yards in size. They are also not the easiest
mobile bins to maneuver. As hauling contractors also charge for the time re-
quired to pick up and drop off these vehicles, the location and ease of access-
is important.
In sizing a compactor and mating hauling container, it is obviously essen-
tial to know the cube of waste being generated each day and to determine the
practical reduction given by compaction. Hauling contractors charge on a trip
basis; the fewer the trips, the less the cost to the hospital. Hospitals
thus attempt to use the largest compactor and container for the waste generatec
weekly, and balance this against the storage problems the waste can create.
OB* limit to size of vehicle is the parking space available. Another limit is
the amount of odor and possible environmental contamination the stored waste
can create. Out of all these considerations, the hospital will size its com-
pactor and container, for hauling weekly, or twice or three times a week.
The National Solid Wastes Management Association, Washington, D.C., gives
a rating to over 135 different models of compactors on a set of 13 key para-
meters. The base size rating defines the charging capacity of the compactor,
measuring the theoretical volume moved by the ram in a single stroke. The
clear top opening, length by width, indicates the largest objects that will
fall freely from top to bottom of the charging chamber. The ram stroke is
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the maximum linear displacement or forward stroke of the ram. The penetration
of the ram into the waste container provides the uniformity of compaction and
it clears the discharge opening of the container prior to decoupling from the
compactor.
The speed at which the compactor moves materials into the hauling con-
tainer is the "cycle time," measured in seconds. The theoretical upper limit
of compactor output based on 100 percent utilization is the "machine volume
displacement per hour," measured in cubic yards per hour. Compaction capa-
bility is measured in terms of pounds force per square inch on the ram face at
stated actuator forces, such as hydraulic pressure.
Another important measurement is the discharge opening which defines the
minimum dimensions for the opening of the mating container.
When a compactor is interfaced with a pneumatic tube waste transport sys-
tem, an efficient and environmentally acceptable design can be achieved.
At the bottom of the pneumatic tube collection hopper there must be suf-
ficient head height, along with length and width to allow the bagged or loose
waste to drop out into the compactor receiving chamber without bridging. Waste
arriving in the final collection room varies tremendously in density once it
escapes from a bagged condition. The major problem is "float—fine particles
and light weight pieces of plastic and paper, all of which may have become
contaminated by contact with other waste. A second problem is liquids in the
waste that can spill out of the transport path. The connection between the
pneumatic system collector box and the compactor receiver chamber must be dust
and liquid tight, so that when waste drops out of the collector none can es-
cape. Further, the connection between this receiver chamber of the compactor
and the hauling bin must be equally tight so that no waste escapes during the
stroking of the ram. There is simply no reason why waste should be spilled,
or float, in such mechanized systems. If it does, it is the result of poor
engineering or poor construction.
The space alloted for installing a compactor should allow for properly
servicing the equipment. When installed indoors or in a protected area, pro-
per cleaning facilities should be provided such as hose and steam cleaner out-
lets, gutters, and floor drains. Also, fire protection devices such as
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sprinkler systems, extinguishers, or injection nozzles for chute fed units
should be provided.
DRY GRINDERS, MILLS, AND HOGGS
The latest development in solid waste handling and reduction at the hos-
pital central collection point is to lead directly from the chute collector
box into an attrition mill or dry grinder, capable of reducing all waste into
a standard particle size. This device must be selected to meet the require-
ments of handling a tremendous variety of material equally well: paper, card-
board, sheet metal and cans, glass bottles, wood products ranging from pencil
size to heavy crating, plastic film and injection- or vacuum-molded plastic
shapes, metal wire, rubber, textiles, animal and vegetable products. The mini
mun capacity should be 6,000 pounds an hour regardless of hospital size,
The oversizing of the grinder is to ensure that it is powerful enough to
reduce any waste item being fed into it. All waste should be reduced to a
particle size of from 3/4 in. to 2 in. diameter for ease of handling and mix-
ing after reduction.
As in the case of the compactor loading compartment, the pneumatic chute
collection box should load into the receiving chamber of the grinder, or mill,
by a dust and water tight, heavy, steel plate transition section, designed in
a way that there is no possibility of bridging. There should be a flexible
connection at this point to positively prevent any transfer of vibration from
the mill to the collector box, as well as the building structure.
The throat openings of such mills are sized to the capacity of the grind
ing or milling "teeth" or banners to prevent overloading. The opening of a
3 ton per hour unit is approximately 3.9 square feet, which is comparable to
the area of a 20 in. diameter tube or chute.
After grinding and reduction, the waste is normally transferred to a
holding and mixing tank. This can be done mechanically in a completely en-
closed screw conveyor, or it can be transferred by a materials handling fan
pneumatically in an 8 in. to 12 in. diameter tube, and dropped into the
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holding tank through a cyclone that removes the excess air. This method also
must involve a completely enclosed system from the attrition mill to the hold-
ing tank. When transferring ground waste pneumatically, the effluent air from
the cyclone should pass through a 2 micron bag or roll filter to prevent con-
tamination of the air outside the area.
The final step in the reduction is to compact the waste from the holding
or surge tank; or to incinerate it. The holding tank must be of a design and
construction that prevents bridging and, as stated, be completely enclosed.
Normally, to provide a safety factor as well as a good mix of the waste par-
ticles, the holding tank should be large enough to hold a 48 hour supply of
the hospital total waste. It can be sophisticated, with level sensors to pro-
vide maximum and minimum cut-offs in volume.
Whether incineration or compaction is the final step, the holding tank
should have a "live bottom" of slowly moving screws. This has the advantage
of mixing the waste into a fairly even mass. It ensures a homogeneous mix-
ture of materials. It is also the most efficient method for moving the waste
out of the holding tank and by completely enclosed screw conveyor into a com-
pactor or an automatically fed incinerator.
INCINERATION
The ultimate disposal of hospital solid waste has an environmental affect
on the air, the water, or the land—discharge of gases and solids from incin-
erators into the atmosphere, discharge of garbage grinders into sewers, dis-
charge of solids into land fills. In recent years, the use of incinerators in
hospitals, because of discharge of pollutant matter into the air, has been un-
popular as the pollution regulations have become more stringent. To combat
this, incinerator designs have greatly improved, from the single-chamber,
smoke-belching, "black boxes" of the 1930's, to the multi-chamber units of the
1970's; with auxiliary burners, controlled overfire and underfire air, auto-
matic feeding devices, and flue g4s scrubbers. However, certain communities,
who have studied the make-up of solid wastes in hospitals, witn their heavy
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load of plastics, are worried as to whether the present advanced state of tech--
no logy in incinerator design can yet meet the emission requirements, day after
day.
It is generally agreed that a properly designed and operated multiple-
chamber hospital incinerator with 700 F to 1,000 F in the primary and up to
2,000 F in the secondary, and with proper retention rates and complete com-
bustion, will sterilize the most infectious and heat resistant organisms found
in the waste. Emission of bacteria, viruses, or spores into the atmosphere
will not be a problem. However, burning must be complete.
Entrained particulates and some gaseous elements are the major air pollu-
tants emitted from the burning of solid wastes in incinerators.
The principal gaseous emissions from incineration are carbon dioxide,
nitrogen, oxygen, and water vapor, none of which can be classified as air pol-
lutants. However, trace gases in the emissions can cause some air pollution
due to their odor; their effect on plants, animals, and property; or their
interaction with components in the outside air to form undesirable secondary
components. Chemical substances in this category are sulfur oxides, nitrogen
oxides, carbon monoxide, hydrogen chloride, aldehydes, organic acids, ammonia.
and hydrocarbons. Criteria exist in certain critical areas on nitrogen oxidejr
and total hydrocarbons, and most areas place limits on permissible sulfur oxid-
emission. Except for the odor-causing elements, the remaining trace gaseous
emissions are not of particular concern in air pollution control.
The particulates, or solids, suspended or entrained in the gas being
emitted are of more serious concern as air polluters. Specific, quantitative
emission limits of gas-suspended particulates have been written into all air
pollution codes. The codes may be expressed in various ways, such as:
<1) total weight of suspended particulate per unit volume of exhaust gases;
(2) total weight of suspended particulate per unit weight of exhaust gases;
(3) total weight of suspended particulate emitted per unit weight of solid
waste charged.
To obtain a standard of reference of the condition of the gas, and thus
to prevent an incinerator operator from avoiding compliance with emission
codes by diluting emitted gases with air or water vapor, almost all codes
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require correction of the emission limits to a specific reference condition.
The most commonly used units for emission values are (1) pounds of suspended
solids per thousand pounds of dry flue gas, corrected to 50 percent excess
air, and (2) grains of suspended solids per standard cubic foot (29.92 in. Hg
and 70 F) of dry flue gas» corrected to 12 percent carbon dioxide. These con-
ditions are approximately equivalent for municipal waste incineration.
By 1966, the consensus of opinion was that emission limits should not ex-
ceed 0.2 grain of particulate matter per standard cubic foot of dry flue gas
corrected to 12 percent CO, in incinerators burning 200 pounds or more of waste
per hour (the usual size found in hospitals); and not to exceed 0.3 grain in
incinerators burning less than 200 pounds per hour. The members of the Incin-
erator Institute of America adopted these standards in 1968 and guaranteed to
meet them.
Many municipal and state codes also have established restrictions on the
opacity of the emissions. These are based on the Ringelman chart. A visual
observation is made of the stack "plume" with the Ringelman chart or scale.
This is a series of reference grids of black lines on white that, when proper-
ly positioned, appear as shades of gray to the observer. The use of the chart
takes a trained technician to achieve consistent visual evaluations. Host
codes require that: (1) the normal, continuous plume quality not exceed Rin-
gelman No. 1; (2) for short periods, not exceeding 3 to 5 minutes, plume qual-
ity not exceed Ringelman No. 2.
To control emissions of suspended particulate matter in the effluent gases
from an incinerator is not a simple matter. The first requirement is an effi-
cient design of the incinerator itself to ensure that the waste is properly
and completely burned in the primary chamber and that the gases are retained
for a sufficient time period in a secondary chamber to burn the particulate
natter still further. Many designs add mechanical devices to remove the par-
ticulates from the gas. The first of these were settling chambers. Starting
around 1957, some units incorporated wetted baffle-spray systems with screens
and baffles and water sprays. Other units incorporated cyclone separators.
More efficient than the wet baffle and spray systems have been the wet scrub-
bers. In these, the entrained particulates must combine with the water itself
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rather than water flushed impaction surfaces. The particulates collide with
water droplets to effect capture. The particles and the water droplets then
form larger droplets that are collected. The efficiency of well-designed
scrubbers is as high as 94 to 96 percent. A problem is that certain chemicals
in the gas, when in contact with water, form corrosive substances, such as
hydrogen chloride forming hydrochloric acid.
Other methods used to trap particulates are electrostatic precipitators
and fabric filters of fiberglas, asbestos, or high-temperature synthetics.
W.P.A. has suggested that there should be no more than 0.08 grain of par-
ticulate matter per standard cubic foot of dry flue gases, corrected to 12
percent C0» (against the present standard of 0.2 grain per cubic foot). This
is the equivalent of 1.6 pounds of particulates per ton of solid waste burned
and means that particulate removal would have to be 95 to 98 percent efficient,
Estimating, in 1973, the solid waste generated at 10.2 pounds average for
1,200,000 patients per day, this is 6,165 tons of hospital waste per day for
the United States. If all this waste were incinerated, it would amount to 4,9
tons of particulate emission into the atmosphere per day for the whole country;
if the 0.08 grain standard were consistently met. As all solid waste burning
of every type, from all sources, in the United States generates less than 4
percent of the estimated particulate matter discharged into the atmosphere,
this 4.9 tons appears a rather infinitesimal amount.
In 1968, the Incinerator Institute of America published their Incineratoi
Standards. Stating that the "basis for satisfactory incinerator operation is
the proper analysis of the waste to be destroyed, and the selection of the best
equipment to destroy that particular waste," they classified mixtures of waste
•ost commonly encountered as "Types 0 through 6." They then classified incin-
erators by capacity and type of waste they are capable of burning as "Class 1
through VII."
Many hospitals have stated that reading these incinerator standards and
waste classifications does not seem to solve their problems. Most hospitals
require incinerators with burning rates from 500 to 1,500 pounds per hour and
capable of handling solid wastes as are typically generated by hospitals. Whr
they ask of the manufacturers and consultants is specific data on the inciner-"
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tor that should be installed to achieve desirable emission rates. The Incine-
rator Standards leave this matter literally up in the air as far as typical
high volume plastic and paper content is concerned.
The question to be answered is whether hospital-operated incinerators can
consistently meet an emission rate as low as 0.08 grains per cubic foot. The
experience in Los Angeles with locally constructed incinerators burning hospi-
tal wastes with large plastic content has shown that to consistently maintain
0.3 grains per cubic foot was difficult with the loading and mixing methods
they used, despite the fact that the Incincerator Institute guarantees to
meet 0.2 grains for this type unit.
With automatic feeding of the incinerator on what amounts to a "B.T.U.
demand" basis, burning can be controlled very accurately. With a waste that
is well mixed, both as to particle size and as to content (paper, plastic,
wood, textiles, etc.) a fairly even-burning fuel is injected into the primary
chamber, load after load. This solves most of the stack emission problems
that have occurred in the past and assists in meeting all present air pollu-
tion standards during burning. This assumes that the incinerator is of a
modern design with proper temperatures and holding times in both the primary
and secondary chambers. Several recent tests, on a continuing basis, reveal
that a system of automatic grinding, mixing, holding, and feeding of typical
hospital solid waste into a properly designed incinerator can consistently
achieve emissions lower than 0.1 grains of particulate matter per cubic foot
of gas. A few such systems, as the forerunners of several more, are going on
line in 1973 and will provide the nation with test data on a continuing basis.
They are tied into pneumatic tube delivery systems and are completely auto-
Bated.
There is a definite trade-off of environmental effects, between the emis-
sions of properly managed incineration, and the effects of hauling and dumping
the raw hospital wastes in landfills. In the balance there appears to be far
less environmental hazard in the route of properly managed incineration.
Incineration obviously has definite advantages in handling hospital
wastes. With incineration, the original waste is sterilized completely, both
with regard to the solids and to the gases. The material hauled off-site does
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not create known problems to either the environment or to the public health of
the community. It is reduced in volume by 90 percent or more, resulting in lev
hauling costs of the ashes. Further, after such reduction only a small portio-
of the original total is placed in land fill, thus extending the useful life
of these valuable sites that are becoming increasingly scarce in our urban
areas.
With properly designed and controlled plants the volume reduction in
municipal incineration is estimated to be from 80 to 90 percent. It is also
estimated that 98 to 99 percent, by weight, of the combustible materials can
be converted to carbon dioxide and water vapor. Total weight reduction of the
waste (with the non-combustible solids, such as glass included) is commonly
75 to 80 percent when it is converted to a dry residue with all the water
content evaporated. Compaction of this residue results in further volume re-
duction, so that the compacted remains may be as low as 4 to 10 percent of the
original volume.
The reduction in weight and volume of hospital waste by incineration is
even more impressive than with municipal waste, due to the far higher per-
centage of completely combustible paper and plastic products in the hospital
output. The make-up of the volume or cube of hospital waste is approximately
the following:
Paper and cardboard 60.OX
Plastics 21.0%
Rubber and gums, natural and synthetic 0.5%
Textiles, cotton and synthetic 7.5%
Animal products 0.5%
Wood products 1.5%
Food products 1.0%
Glass, metal and incombustible 8.0%
In short, 92 percent of the total is combustible. Further, the density
of most hospital waste is lighter than municipal waste. The latter has been
estimated to weigh from 5 to 6.3 pounds per cubic foot as against hospital
waste in an uncompacted or raw form weighing from 2.5 to 4 pounds per cubic
foot, due to the higher quantity of loosely packed and light materials in the
total bulk make-up.
Weight reduction during incineration of the hospital waste is greater
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than with municipal waste, due to the higher percentage of combustibles and
is estimated at 85 to 90 percent. Thus a 2,000 pound lot of hospital uncom-
pacted waste measuring approximately 22.5 cubic yards would end up as an ash
residue that would weigh approximately 260 pounds. Even more dramatic is the
reduction in volume, which is estimated to run as high as 99 percent against
the original uncompacted raw waste cube. It is estimated that incinerator
residue has a land fill compacted density of 2,700 pounds per cubic yard.
Hence the 260 pounds of ash residue would occupy only .097 cubic yards or
approximately .44 percent of the original volume.
In connection with incineration, we have a situation with hospitals that
should be resolved. Virtually all state and local health codes insist that
hospitals maintain a pathological incinerator for the burning and destruction
of such specimens. Such units in general do not meet emission standards and
hence are endangering the environment, although admittedly the emission
volume is quite small in the normal operation of destroying the limited number
of pathological specimens that are generated.
Where problems are created is in the case of hospitals being forced to
destroy by incineration their other contaminated materials, consisting of
large volumes of plastic and paper and other non-pathological matter. In
many communities, this has occurred because the local governments have refused
to permit such contaminated material being hauled to a landfill due to a fear
of affecting the ground water, or for other public health reasons.
Too often we see hospitals that are placed in this position burning these
large volumes of such contaminated waste in their pathological incinerator,
a device that was never designed for this purpose. The air emissions then
become extremely serious and an environmental problem. It would appear
more practical to ensure that this is not done; by insisting that such hospi-
tals install environmentally acceptable incinerators of modern design capable
of both pathological and general waste burning, and with systems of feeding
these that guarantee the desired results.
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OFF-SITE HAULING VEHICLES
The open waste hauling truck or bin, until a few years ago, was the basic
nethod used for off-site removal. It is generally accepted that if such an
open body is used for off-site hauling of only construction and crating ma-
terials, such as generated at the loading and receiving dock, that the effects
on the environment are not too serious. This assumes a well constructed
vehicle with strong sides that is not overloaded. If this same vehicle is used
to haul off-site the general solid waste of the hospital, either hand-loaded
into it or received from pneumatic transport tubes, this is not acceptable.
Too often have we seen such vehicles traveling city streets with red plastic
bag loads of hospital waste signifying infectious materials.
A closed off-site hauling vehicle has been studied from several aspects
as to its effects on the environment in hauling hospital wastes. As seen
from the section on compactors, it is the normal type of trailer used for
hauling compacted wastes. Despite the fact that closed vehicles of this type
have been seen to leak fluids during a haul to a land fill, the Center for
Disease Control states that there has been no documented report of infectious
diseases associated with such hauling. Further, it would appear that closed
vehicles of this type can be constructed that do not leak.
Waste hauling costs in most metropolitan areas have risen as much as
200 percent in the last 15 years. In cities of 100,000 to 200,000, the price
for hauling a 20 to 25 cubic yard compacted load runs from $43 to $48, and
a 35 to 40 cubic yard compacted load runs from $46 to $55. The cost of amor-
tizing the compactor and the hauling bin must be added to these figures. This
Beans that hospitals in these smaller communities, with an average census of
350 patients, are paying from $7,000 to $12,500 per year for the hauling of
their solid waste. In large Eastern cities, the fees are approximately double
this amount.
Obviously every effort should be made to reduce the volume and weight
of solid waste the hospital is forced to haul, by the use of compactors,
attrition mills, incinerators, and similar devices on a self-liquidating
investment basis.
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SANITARY LANDFILLS
At present, somewhere in the neighborhood of 80 percent of all hospital
waste is hauled to a landfill in an untreated form, with at least 40 percent
of the hospitals having first compacted the raw product. Aside from the fact
that landfill sites are becoming in increasingly short supply, there is con-
siderable concern as to the effectiveness of the sanitary landfill operation
in destroying these wastes so that they do not become a health hazard after
burying.
Landfills are accepted by hospitals in much the same manner as they are
by other members of the general community. The same attitude applies to the
hauling contractors who pick up the solid waste. It usually comes as a shock
to investigators surveying hospital solid waste management practices that the
hospital personnel, from top administration to middle management, have only a
vague idea as to who or what is hauling the waste off-site; where it is being
taken; and exactly how it is being handled after it arrives at its destination
It is essential that all hospitals know where their solid wastes are
being hauled off-site; what type of landfill is being used and how it is being
managed. While the hospital has no legal jurisdiction over the landfill, it
has a moral responsibility to the community to know the type of site to which
its contract hauler is transporting the solid waste generated by the institu-
tion.
E.P.A. has published guidelines and recommendations for landfill manage-
ment for several years. The latest are published in the Federal Register for
April 27, 1973. In proposed rules for landfill management, paragraph 204.201:,
"Solid Wastes Excluded," E.P.A. recommends that, "Using information supplied
by the waste generator/owner, the responsible agency, the disposal site owner/
operator and designer shall jointly determine specific wastes to be excluded
and shall identify them in the plans. The generation/owner of excluded wastes
and the responsible agency shall jointly determine an alternative method of
disposal for excluded wastes. The criteria used to determine whether a waste
is unacceptable shall include the hydrogeology of the site, the chemical and
biological characteristics of the waste, and the safety of personnel."
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SALVAGE, RECYCLING, AND RESOURCE RECOVERY
Studying the habits of hospitals in solid waste disposal indicates that
the salvage and recycling practices are used less in hospitals than with in-
dustrial plants or homes. There are several apparent reasons for this. The
most valuable salvage items are metal scrap of known purity, both ferrous and
non-ferrous. Hospitals generate a fairly small amount of metals. A known
major waste item that is easily separated from the waste stream would be glass
bottles and containers. However, glass has an extremely Low recycling rate:
only 4.7 percent of the glass produced uses purchased scrap for its make-up.
The amount of worn-out textiles sold by hospitals to salvage operations
is difficult to pin down. It is known that clean, uncontaminated, patient and
surgical textiles are generated in fairly large quantities by hospitals. How-
ever, recycling of textiles has been declining and the market for the hospital
product consequently falling. Disposable textile products that are mixed in
the solid waste stream are universally destroyed along with the other waste.
Paper and plastics from hospitals have a very low recycling rate. Little
effort seems to be spent on salvaging corrugated board, flat board cartons,
office and computer paper, newspapers, books and magazines, and packaging
paper, despite the fact that paper and cardboard make up 60 percent or better
of the total solid waste. Most hospitals seem to feel that the expense of
segregating this part of the waste, even though clean and uncontaminated, is
much more than they can realize from sale to salvage dealers.
Plastics generated as waste in hospitals are the same type as generated
by homes, stores, and other institutions. Sale as salvage, with present tech-
nology for recycling, is not practical, due to the tremendous number of dif-
ferent chemical formulations used. This makes it impossible to sort these
into like formulations after use; without such sorting little practical use
can be made of the product.
The net result of the above considerations is that hospitals and the com-
munity are left by and large with most of the solid waste that was generated.
Very few saleable materials are diverted from the waste stream. The only
potential resource recovery is to use the waste as energy; to possibly convert
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it to a fuel under a method that will at least recapture the cost of burning
it, and hopefully at least part of the cost of collecting, transporting, and
processing it.
It has been discovered that municipal solid waste is a clean fuel from
the point of view of environmental pollution. Several European municipal
plants, over the past years, plus a few in Canada and the United States
recently, have used solid waste as a fuel in special boilers for steam genera-
tion. Hospital solid waste mixtures, as seen in the section on incineration,
have a relatively high B.T.U. output, and if ground, or milled, and mixed,
have a fairly consistent B.T.U. output. Further, the moisture content is
much lower than in municipal waste and also much more consistent, thus reduc-
ing a major problem in using solid waste as an efficient fuel.
Hospitals are also heavy users of steam for heating and sterilization.
A few are now investigating the potential of capturing the heat generated
during their in-house incineration and putting it to use. The systems are
still in the experimental phase and it is not known how successful the econo-
mics will prove to be. the technology would be similar to that used in cer-
tain municipal incinerator plants, and in some industrial operations, but on
a ouch smaller scale.
What is yet to be determined is whether the waste generated by even the
largest hospitals (500 beds and over) is sufficient to operate an economically
feasible waste heat recovery system.
In municipal plants, successful waste heat recovery systems appear to
involve a 24-hour-a-day operation and a relatively constant burning of waste
during this period. Hospital incinerators usually do not operate over 12
hours, and normally for far shorter periods. Hence the technology of heat
storage must be quite different from that of municipal systems. To date,
experimentation in hospitals has concentrated on piping superheated water
or other fluids from the incinerator to remote storage and heat exchangers,
rather than the direct production of steam at the incinerator or an adjacent
boiler.
It would appear that further engineering and economic research on the use
of waste heat recovery systems in hospitals would be worthwhile and might
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offer a definite economic return for the design effort expended.
The solution to using the heat of the gases from hospital incinerators for
waste heat recovery, as pointed out above, must follow a slightly different
technical direction than with municipal waste. There are three main reasons
for this:
(a) While both municipal and hospital wastes are relatively "clean"
fuels, hospital waste has a higher plastic content. This means
that the incinerator used must be capable of handling plastics in
quantity. Also it means that the effluent gases are more corro-
sive from hospital waste and hence the waste heat recovery boiler
linings, diverter valves, and tubes must be constructed of ma-
terials that will not corrode quickly from the gas.
(b) Hospital waste in medium sized institutions rarely is burned at
rates greater than 1,500 pounds per hour and the average is closer
to 1,000 pounds per hour. Burning times rarely exceed 12 hours
per day and the average is closer to 6 hours per day.
(c) Due to the limited total quantity of waste and short burning hours,
either waste heat storage systems must be developed (such as hot
water storage in tanks), or the waste heat must be used first as
an auxiliary to the main steam supply and for limited use.
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5-DESCRIPTION OF THE SURVEY HOSPITALS
To determine the feasibility of pneumatic waste transport systems in hos-
pitals, three institutions were selected that would give a good cross section
of medium sized hospitals, their solid waste management practices, as well as
types of pneumatic equipment currently in use. The institutions selected were
the Veterans Administration Hospital, San Diego, California; Martin Luther
King Hospital, Los Angeles, California; and St. Mary's Hospital, Duluth,
Minnesota.
ST. MARY'S HOSPITAL, DULUTH, MINN.
St. Mary's Hospital, owned and operated by the Benedictine Sisters Benev-
olent Association, is a 495-bed acute general hospital. During the past year.,
the average rate of occupancy has been 79.8 percent on an active 419 register-
ed beds for adults and children, giving a daily census of 335 patients.
During the survey period, the admissions per day were 42 and the dis-
charges 44, with an average length of stay for each patient of 7.5 days.
There were 44 outpatient visits and 48 emergency visits to the hospital
per day.
The total hospital staff, on a full-time equivalent basis, was 1,033,
giving a total hospital population (inpatient, outpatient, staff) of 1,460 daily
The ancillary and support activities can be seen from the following sta-
tistics of activity during the survey period for daily averages:
Meals served ... 1,743
Laboratory tests for both inpatients and outpatients ... 1,085
Operating Room procedures for inpatients and outpatients ... 31
Radiology procedures for inpatients and outpatients ... 198
Pounds of laundry handled per day ... 6,841
The building complex consists of 518,853 total square feet, of which
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451,530 is maintained by the housekeeping department. The oasic design con-
sists of a West Wing that is ten stories high, a Center Wing that is ten
stories high, an East Wing that is seven stories high, a North Wing that is
connected to the Center Wing by a corridor and is five stories high, and a
Service Building housing the laundry, boiler plant, and waste collection room,
connected to the North Wing, and having a total height of three stories.
The pneumatic trasn and linen system was designed by the vendor and in-
stalled in two phases. The first phase, covering the East and Center Wings,
was completed in October of 1969 for a cost of $109,357. The second phase of
the system was installed complete in January of 1971 at an additional cost of
$73,800. The two phases resulted in a complete system for the hospital cotnr-
prising 41 load stations, of which 20 are for linen and 21 are for waste,
with three vertical pairs of chutes (one for waste and one for linen), one for
the West Wing, one for the Center Wing, and one for the East Wing.
The system that is used is a full-vacuum 16 in. diameter tube with 20
gauge wall system, with separate loading doors and separate chutes for waste
and laundry, and operates on the "single bag" method with no multiple loading
of bags. The chute loading stations are located in chute rooms.
As can be seen from the statistics in the next chapter, approximately
38.8 percent by weight and 67.4 percent by volume of the total waste of the
hospital is sent through the pneumatic system. The balance of the items, that
are either too bulky, or consist of glass and metal cans, are removed by cart
by the housekeeping department during regular "sweeps" of the building over
a 17 hour period each day. The pneumatic waste system operates from 5:00 A.M.
to 10:00 P.M. The cart removal of waste operates during the same time period,
plus additional hauling during the night hours from public lobbies and the
Qnergency Room.
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PENTHOUSE » HOOP
EXHAUST TO ATMOSPHERE
(NO *ILTER IS L^SED I
r
AERO ACUSTiC SOUND »TTE"tUATO*
L'NEN COLLECTORS
BUTTERFLY FAS CAMPER
AIR ACTIVATED
so
'< BASE
CE-L'NG H'JXt
ItCC-IP
0 LIHEN STATION
FIGURE 8
ST MARY'S HOSPITAL
Ouluth-Mmnesoio
AIR RETURN I
LINEN LINE
TtUSH LINE
PNEUMATIC TUBE SYSTEM F
SCUD WASTE ft LAUNDRY
-100-
-------
Loading the single bag, full vacuum
system at St. Mary's Hospital.
During peak periods in
busy nursing wings
single bag systems
rarely can keep up
with the speed waste
is generated, as seen
by the above view of
typical chute roonu
r^p"
l_besl
!Reproduced (rom
available copy.
Lower left: these
nylon mesh bags
virtually eliminate
bag breakage and hence
environmental problems
in this system.
-101-
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* Above: Views of the
box type soiled
laundry and solid
waste collectors
at the end of the
^ line at St. Mary's
^Hospital. The waste
* must be hand carted
.
v from the waste
collector to the
• compactor located in
.the Service Building
court yard.
Reproduced from
best available copy.
-102-
-------
Above: The Engineering Department of
St. Mary's designed and installed a
unique monitoring panel to determine
the status of any loading station.
Right: Typical tubing rising from the
basement into the Service Building.
-
Left: The fan room
equipment is unsophis-
ticated and quite
lightly constructed in
this system, using an
open type materials
handling fan and a
simple exhaust duct
type sound attenuator.
High level vacuum
protection is obtained
by a gate valve before
the fan.
Reproduced from
best available copy.
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VETERANS ADMINISTRATION HOSPITAL, SAN DIEGO, CALIFORNIA
The Veterans Administration Hospital, located in La Jolla, a suburb of
San Diego, California, is owned and operated by the Veterans Administration
of the United States Government. It is a 811-bed general hospital which, dur-
ing the past year, has experienced an average rate of occupancy of 59.0 per-
cent on an active 646 registered beds, giving an average daily patient census
of 400.
During the survey period, the number of admissions per day was 29.4 and
the discharges were 30.3, with an average length of stay for each patient of
11.5 days. There were 199 outpatient visits per day. Emergency visits, as
found in community hospitals, do not occur.
The total hospital staff, on a full-time equivalent basis, consisted of
1,605 people daily, giving a total hospital population (inpatients, outpatient*
and staff) average of 2,204 daily.
The various support activities of this hospital can be seen from the fol-
lowing daily average statistics gathered during the survey period:
Meals served . . . 2,380
Laboratory tests, in- and outpatient . . . 4,936
Radiology procedures . . . 165
Operating Room procedures ... 24
Pounds of laundry . . . 136,848
The hospital has 677,700 gross square feet of enclosed area, consisting or
the penthouse, six floors, a basement, and a mechanical room above the pent-
house. Above the first floor, the building is laid out as a cross, with North
East, South and West wings intersecting in the center, with a loading dock at
the far end of the North wing. The cost of construction was approximately
$35,250,000.
The pneumatic trash and linen system was installed in November 1971, at
a cost of $350,000. It is a full-vacuum, single tube system, for moving both
waste and laundry. The tube is 16 in. in diameter with 20 gauge wall, and ther
are a total of 54 load stations—27 for waste and 27 for laundry. The system
is key-lock operated and permits one operator to deposit 10 to 12 bags of
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laundry and up to 12 bags of waste on a continuous loading basis, one station
at a time.
As can be seen from the statistics in the next chapter, approximately
25.1 percent by weight and 35.A percent by volume of the total waste of the
hospital is sent through the pneumatic system. The balance of the items are
either too bulky, or consist of glass and metal cans, or are deemed infectious
or hazardous. They are removed by cart using an average of 31 cart trips per
day. The pneumatic waste system operates from 6:00 A.M. to 3:30 P.M.
-105-
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•t:fiviiw —1
L- .u»r«
«'
*l *
FIGURE 9
VETERANS ADMINiSTRATrOM nQSPiTAl
Son Diego California
SOl 10 WASTE * LAUNDRY
T»«S" B i
T»ASH
I.INCN LINE
-10ft-
-------
The Veterans Administration Hospital
is noted for its excellent housekeeping
practices.
Above: Special color coded and labeled
containers with distinctively colored
plastic bag liners for the glass and
metal waste.
Top: The loading hopper
of a typical waste chute.
Reproduced Irom
best available copy.
Left: This collection of
bags of solid waste was
assembled to determine the
speed of loading in this
multiple bag system. The
28 bags in the pile were
dispatched in under two
minutes.
-107-
-------
The Veterans Administration Hospital
utilizes a single tube system. Above
is the Diverter Valve Box designed to
divert waste or laundry to the proper
collector.
Above right: The control panel of this system consists of a series of stepping
relays to activate the various roof dampers, inner chute doors, diverter valve,
collector box doors, etc. The entire system requires several miles of wiring,
making the electrical hook-up one of the most costly elements in the installation.
Left: The fan room is
located in a penthouse
atop the hospital. The
fan has an excellent
vibration dampener base.
The RollomatU- filter to
protect the fan can be
seen at the rear, with
the high vacuum relief
system to the right of
the fan motor.
Reproduced
best available copy.
-108-
-------
At the Veterans Administration Hospital two
totally different styles of collectors are
used. Top right is the square, box type,
laundry collector dropping into the soiled
laundry receiving section.
Reproduced from
best available copy.
Top left and lower left:
The cyclone collector
used for waste is designed
to receive rapid and
continuous loading. Note
that most bags are ripped
by the time they emerge
I I ,uii I In- .Ml ill' t i'l . Tilt'
entrance to the compactor
is not close coupled to
the collector and presents
serious aerosol possibil-
ities with broken bags.
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MARTIN LUTHER KING HOSPITAL, LOS ANGELES, CALIFORNIA
Martin Luther King Hospital, owned and operated by Los Angeles County,
is a 394-bed general hospital. During the past year, the average rate of
occupancy has been 64.4 percent on an active 320 registered beds for adults
and children, giving a daily census of 206 patients, including bassinets.
During the survey period, the admissions per day were 28 and the dis-
charges were 38, with an average length of stay of 7.7 days.
The hospital operates a large outpatient department, averaging 360 visitf:
daily, and an equally large emergency service, averaging 218 visits daily.
The total hospital staff, on a full-time equivalent basis, was 2,200
people daily.
The ancillary and support activities can be seen from the following
statistics of activities during the survey period for daily averages.
Meals served . . . 1,519
Laboratory tests for both inpatients and outpatients . . . 4,341
Major surgical procedures ... 6
Minor surgical procedures ... 9
Radiology procedures for inpatients and outpatients . . . 157
Pounds of laundry handled per day . . . 9,524
The building complex consists of 551,251 square feet and includes six
floors plus a basement. It was constructed for a total cost of $23,540,000.
The pneumatic waste and laundry system was installed in March 1972. The sys-
tem is a gravity to vacuum type, utilizing 14 gauge 20 in. diameter gravity
chutes and 20 in. vacuum tubes of heavy wall pipe, operating on a key-lock,
multiple bag principle. The use of gravity chutes means there is no limit
on the number of bags that can be loaded by a single operator. There are
43 loading stations total, of which 19 are for laundry only and 24 are for
waste only. The system includes four vertical tubes for laundry and four
for waste. The cost of the installation was $425,000. The system operates
on a 24 hour day basis. Approximately 60 percent by weight and 85 percent
by volume of the total solid waste is transported by the system.
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VfMflCAL
"'"" fc>. / CO"""
V^N-/"""1'"
••43- JT4T.OK
. • «t ' •« . •<
FIUUKE 10
MARTIN LUTHER KING HOSPITAL
Los Angeles Cot.fomio
-111-
PNEUMATIC TUBE SYSTEM FOR
SOLID WASTE a LAUNDRY
-------
UKWHQMBR!
SBOfNt
MARTIN LUTHER KING
The photograph above shows the different
configurations used for the loading
hoppers of the Laundry and Waste chutes.
The administration constantly reminds
the personnel against overloading the
chutes or transporting breakables.
Reproduced from
available copy.
For basement and first level
loading stations, independent
of the 6-story high vertical
chutes, hydraulic operated
hoppers, as shown above, are
used.
(Left) View of a typical si
valve, separating the vertical
gravity chute from the pneumatic
horizontal tube system.
-112-
-------
All equipment items in the Martin Luther
King system are constructed ruggedly.
Top right: The soiled laundry collector
is virtually a room in itself. Note the
heavy reinforced plate construction.
Top left: The compactor bin is located
in an air conditioned storage room and
large enough to hold a five-day waste
supply.
Lower left: The compactor is close-
coupled to the concrete and steel waste
collector bin.
-------
Three views of the Mechanical-Fan room
at Martin Luther King, showing the ex-
cellent quality of the equipment.
Top left: The alternating exhaust fans,
Top right: The 2 micron bag filter in-
stalled to prevent fan damage and envi-
ronmental problems. Lower left: The
control and monitoring panel.
-------
e,-QUANTITIES AND TYPES OF HOSPITAL SOLID WASTE
To determine the quantities of waste generated by hospitals, numerous
surveys were made during the present study, with in-depth analyses of the
three pilot hospitals. The figures were compared with those the researchers
had obtained from other hospital solid waste studies. The surveys approached
the analyses from several directions. These included weighing and measuring
each individual bag transported through the pneumatic tube system, together
with all waste hand-hauled by cart, over a complete 24 hour period for seven
days in a row. Breakdowns were obtained for each hour of the day, each day
of the week, by each generating point in the building. Analysis was made of
the types of waste generated from all points. Total figures were checked
against totals revealed in the central collection area.
TOTAL WASTE GENERATED BY THE SURVEY HOSPITALS
The three pilot institutions represent a fair cross section of American
hospitals, with a census from 190 to 400, a total population of staff and
patients from 920 to 2,000, and outpatient-emergency visits from 90 to 580 per
day. Each was quite different in type of patient and medical delivery program,
ranging from the "typical" community hospital of a medium sized city, to an
urban area hospital with county ownership, to a hospital with research and
teaching programs. However, it should be pointed out that three hospitals
are too small a sample to be representative of the American hospital system
for the purpose of establishing hospital waste loads on a broad basis.
Other surveys performed by the consultant reveal that, currently, hospi-
tal waste loads based on total hospital population (patients plus staff) vary
as much as 60 percent. As may be expected, the more sophisticated the health
delivery and research, and the larger the metropolitan area in which the
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-------
hospital is located, the larger the waste load. This should not be surprising
when one considers that a major metropolitan daily newspaper weighs as much
as 1.5 Ib, which, if brought into the hospital by and for every member of the
total population (staff and patients) plus a percentage of visitors, would
have the affect of almost doubling the hospital waste load.
Waste from food preparation and from scrapings of plates from the cafe-
terias and snack bars was disposed of through kitchen garbage grinders into
the sewer system in all three hospitals. Thus it does not appear in the waste
delivered at the central collection point to be hauled off-site. As it was
impossible to weigh all such food waste without disrupting kitchen activities,
sampling techniques were used.
From this it is estimated that in a combination of food preparation and
in plate food scraping before dishwashing, an average of 0.21 Ib of such waste
per meal served was generated between the three pilot hospitals.
No "outside yard" or construction wastes were included in the total waste
figures unless they were taken to the central collection point and hauled off-
site with the waste generated in the building. This applies to lawn cuttings.
In the only construction observed during the survey period, the general con-
tractor removed his own waste.
In the survey of the wastes at the three pilot hospitals, detailed anal-
yses were made of the total weights and cubes generated by the material trans-
ported from the floors to the central collection point. These cover a period
of seven consecutive days and all three shifts for each 24 hour day. The sur-
veys were conducted during July, August, and September of 1973.
RATIOS OF WASTE TO HOSPITAL POPULATION SEGMENTS AND UTILIZATION
When hospital wastes are compared on the basis of combining inpatient cen-
sus with outpatient visits and total staff (total full time equivalent of a
24 hour population); and reviewed along with the activities of the ancillary
departments that are large waste producers; then direct comparisons can be made
between hospitals; and between hospitals and other segments of the economy.
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Other surveys of hospitals in major metropolitan areas indicate that 10.0
to 10.4 Ib per occupied bed appears valid for many hospitals.2 The average of
11.3 Ib per occupied bed in the current study is high. The average of 9.2 Ib
per occupied bed obtained by totaling St. Mary's and the Veterans Administra-
tion Hospitals is a fairly representative figure. When Martin Luther King is
added, with its heavy outpatient and E.R. load and the extremely large staff
of 2,200 people handling only 183 occupied beds, the amount of waste per bed
becomes biased.
The importance of factoring waste against the "full time population" of
the hospital can be seen from a review of the statistics in Table 4. Figuring
the waste generated against the total population of the hospital more clearly
shows the valid differences between institutions regardless of scope of work
or staffing patterns used.
"Full time population" of a hospital is a term that is not well understood
by many people. First, it consists of the average daily inpatient census,
rather than the total bed complement that is available. Average daily inpat-
ient census varies considerably between hospitals (anywhere from 45 percent to
95 percent of the total available beds). Secondly, it includes the ambulatory
patients that each day visit the outpatient clinics and emergency service.
Each patient is recorded as a single "visit" in the total population, even
though he may be treated in more than one clinic. Thirdly, the population in-
cludes the "full time equivalent" staff of the hospital, both paid and non-paid
or volunteer. This staff varies by shift and drops off on weekends. First
shift, from 8:00 A.M. to 4:00 P.M., may have two or three times the staff of
the 4:00 P.M. to midnight and the midnight to 8:00 A.M. "Full time" equiva-
lent becomes a weighted average of the staff population of the three shifts.
Each person in the total population is a contributor to the waste load.
The contribution of each person varies with his or her activities and the hours
present in the hospital. As the staff is the largest single block in the total
population, and as the staff varies considerably with the three shifts, as do
outpatient visits, the waste varies similarly by shift and between weekdays
and weekends, often as much as over 50 percent.
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TABLE 4
RATIOS OF SOLID WASTE
TO HOSPITAL POPULATIONS. ACTIVITIES & FLOOR SPACE
ITEM
Average Total Waste per Day:
Founds
Cubic Feet
Total Number of Available Beds
Average Occupancy Rate During Period
Average Number of Occupied Beds
Quantity of Waste Per Occupied Bed:
Pounds
Cubic Feet
Average Daily:
Discharges
Outpatient Visits
E.R. Visits
Laboratory Tests
Radiology Procedures
Meals Served
Avg. No. Full Time Equivalent Staff
Total Hospital 24 Hour Population
(Inpatients, Outpatients, Staff)
Quantity of Waste Per Unit of Full
Time Population:
Pounds
Cubic Feet
Total Gross Floor Space, Sq. Ft.
Quantity of Waste Per 100 Sq. Ft.:
Pounds
Cubic Feet
SI. MARY'S
HOSPITAL
2273
567
419
79.8%
335
6.8
1.7
44
44
48
1085
198
1743
1033
1460
1.6
0.39
451,530
0.50
0.12
V.A.
HOSPITAL
4445
1575
646
61.9%
400
11.1
3.9
30
199
0
4936
165
2381
1605
2204
2.0
0.71
677,700
0.65
0.23
MARTIN
LUTHER
KING
HOSPITAL
3678
1188
320
64.4%
183
20.1
6.5
28
360
218
4341
227
1318
2200
2961
1.24
0.40
551,520
0.67
0.22
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TABLE 5
SOLID WASTE GENERATED DURING
24 HOUR PERIOD AVERAGED FOR 7 CONSECUTIVE DAYS
ITEM
Bagged Waste Transported By P/N Tube:
Pounds
Cube
Avg. No. of Bags in 24 Hours
Avg. Weight, Lbs/per Cubic Foot
Bagged Waste, Cartons, Boxes, Etc.
Transported By Hand Cart:
Pounds
Cube
Avg. No. of Cart Trips, 24 Hours
Avg. Weight, Lbs/per Cubic Foot
Total Waste Transported
Pounds
Cube
Avg. Weight, Lbs/per Cubic Foot
ST. MARY'S
HOSPITAL
882
382
147
2.3
1391
185
15
7.5
2273
567
4.0
V.A.
HOSPITAL
1115
557
316
2.0
3330
1018
57
3.3
4445
1575
2.8
MARTIN
LUTHER
KING
HOSPITAL
2218
1008
528
2.2
1460
180
16
8.1
3678
1188
3.1
From these figures, it can be seen that, of the total waste generated in
the. hospitals, as much as 75 percent by weight is hand carried through the
building. In general, this represents the heavy items in the total waste
load and consists of crating materials, bottles, metal, heavy cartons, and
other items too large to fit the chutes. The figures reveal that this ma-
terial has a density per cubic foot of up to three times the waste sent down
the chutes and therefore occupies as low as 30 percent of the total cube for
the waste from the entire building.
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TYPES OF WASTE TRANSPORTED B\ HAND CART
With the installation of a pneumatic tube waste transport system, the
question is raised as to why wastes would be manually transported, and what
the make-up and quantities might be. In the three hospitals studied, the
wastes that are carted to the central collection point covered a wider variety
and larger quantity than might be expected.
SHIPPING CARTONS, WOODEN BOXES, AND CRATING MATERIAL
Virtually all cardboard outer shipping containers and boxes of 100 pound
test or heavier corrugated board were found to be too large to enter the
chute. These range from I.V. bottle and baby formula cartons, to shipping
boxes for medical and surgical supplies, Pharmaceuticals, chemicals, X-ray
film, EOF paper, and general stores.
The Receiving and Warehouse Departments were the largest producers of
this waste material, as might be expected. In addition, large numbers of
complete cartons of supplies were sent into various support and ancillary
departments (such as dietary, main kitchen, laboratory, central sterile sup-
ply, radiology, and pharmacy) and this added to the waste load from disposing
of the empty cartons. Nursing stations usually received supplies broken down
into smaller units and had few outer cartons. It would seem that this could
be accomplished in the other departments to some degree.
Wooden boxes appear in the kitchen in smaller quantities each year, as
they are replaced by corrugated cartons. Some additional wooden boxes are
hand hauled by maintenance and engineering for heavy items such as plumbing
supplies. Wooden crating material rarely gets on to the floors of the three
hospitals studied. When heavy equipment is received in this material, it is
usually broken down at the dock or in the receiving or warehouse areas.
The quantities of cardboard shipping cartons hand-hauled on a single day
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was substantial. At the Veterans Administration Hospital, San Diego, it
amounted to 445 pieces, originating from the canteeen (68), radiology (30),
laboratory (19), O.R. (4), basement areas (79), day shift for all departments
(113), and night shift for all departments (132). These empty cartons weigh
up to 2-1/2 pounds each. Hence, this is 1/3 of the total weight of hand
hauled waste. The other two hospitals had similar percentages in their total
waste.
None of the hospitals had any mechanical equipment installed in their
receiving area, warehouse, or support departments that would modify such car-
tons and boxes so the material could be bagged and transported by the pneu-
matic chute. This would apply to virtually every hospital in the country.
The authors of this study have for years examined various shredding, grinding,
and crushing devices produced for industrial operations to see if they could
be used for this purpose. To date, none have been found that are small enough,
inexpensive enough, and most important, quiet operating to be practical to
install in the various floor work areas of a hospital. However, if the central
waste collection area, compactor, or incinerator are a considerable distance
from the warehouse or receiving section, it might be economically feasible to
place a chute station at this point, along with a heavy duty grinder or heavy
carton shredder with a bagging attachment. It must be capable of handling all
such material.
In many commercial operations, shipping cartons are cut up with hand
knives to flatten them and expedite waste removal. This also was not done in
the hospitals studied. Admittedly, it must be done properly. All three hos-
pitals had experienced the phenomenon of "box accordioning" in chutes, in
which a flattened box opens in transport and creates a jam. Breakdown, to be
effective, must cut the carton into pieces under 14" by 14" in size.
GLASS AND METAL CONTAINERS
The use of glass containers in hospitals appears to have declined in
recent years and been replaced to a degree by plastics. As an example, certain
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blood is now contained in plastic bags, as well as some I.V. fluids. However,
glass bottles are still substantial, making up as much as 8 to 15 percent of
the total waste weight in hospitals.
Two of the hospitals had experienced glass breakage in the pneumatic
tube system that could possibly create glass splinters in the soiled laundry,
or liquid problems if not emptied before transport. Glass containers are
supposed to be dumped of all liquids before depositing in lined waste contain-
ers, but occasionally this has not been followed out by nursing and technical
personnel. Both these hospitals felt that glass bottles and metal cans, even
though bagged, created noise problems going through the tubes. Aerosol cans
create a special problem and are not sent through the tube system for fear of
explosion possibilities.
For these reasons, both hospitals place all glass bottles and metal con-
tainers in separate and labeled waste receptacles with distinctive bag liners
in each soiled utility room or support department and cart-haul the bagged
glass and metal daily to the central collection point.
The third hospital, using heavier wall tubing, as well as separate trash
and linen tubes, has experienced no problem with glass and metal in the systems,
including aerosol cans.
OVERSIZED BAG LOADS
It was discovered that certain areas, such as O.R., canteen, warehouse,
and Central Sterile Supply, are heavy waste generators and use a certain num-
ber of waste containers, such as 30 gallon plastic garbage cans, with plastic
bag liners too large to send down the pneumatic chutes. Except for the cube
of the load, there was nothing in the material that would create problems in
the system. However, this resulted in these over-sized bags of waste being
cart-hauled. Recommendations were made to install smaller containers, or
adaptors for the regular sized chute bags in the large containers, and send
this material through the pneumatic system.
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INFECTIOUS OR CONTAMINATED WASTE
The survey found the operational thinking to be entirely different between
the hospitals on the subject of handling infectious or contaminated material.
At Martin Luther King Hospital, with a completely closed system and heavy wall
tubing, it was felt that all infectious and contaminated material should go
through the pneumatic system as offering the least possibility for cross con-
tamination and the spread of aerosols creating infection problems in the house.
At the Veterans Administration Hospital, all such material, along with the
material from surgery, is not sent through the system but rather is bagged in
red plastic and hand carted to the incinerator room. At this institution, each
surgery has a kick bucket with a special non-static liner. Waste generated is
placed in these and then double bagged in a red plastic outer bag. It is then
transported in special aluminum carts that are sanitized after each trip. The
V.A. is a heavy user of disposable surgical drapes which adds considerably to
this load. The hospital has experienced considerable bag ripping in the tubes,
and is fearful of contaminating the soiled laundry with contaminated or infect-
ious waste.
At St. Mary's Hospital, infectious and contaminated solid waste is sent
through the system, as their double bagging system has apparently prevented
bag breakage.
The only hospital with research animal quarters was the Veterans Administra-
tion. All bedding generated in cage cleaning is regarded as contaminated and
is red bagged and transported by cart.
Other surveys in hospitals have stated chat the material that can be
definitely established as infectious and contaminated is only in the neighbor-
hood of 4 percent of the total solid waste load. In this present study, the
researchers found that this figure is low by at least 50 percent. The per-
centage clearly established by the V.A. San Diego Hospital as infectious was
almost exactly in line with the other two hospitals in this present study.
It represents 10.7 percent of the 3330 pounds of cart transported material at
San Diego. Eight percent of the total waste transported by cart and tube
generated in each of the three hospitals was clearly established as potentially
infectious.
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HYPODERMIC NEEDLES AND SHARPS
Probably the most dangerous item in a hospital as a potential cause of
spread of infections is a hypodermic needle. With the introduction of dis-
posable needles plus the increase in injections in the past 15 years, the
number of needles generated as waste has increased at least twenty times.
With the increase in drug addiction in the United States, hospitals have also
become sensitive to the use of their needles by drug users, particularly after
use in the hospital. Hence, most institutions break needles after use. The
theory is fine. The equipment to accomplish it, on the nursing floors, is
not. Most nursing station needle breakers are flimsy, and a source of nursing
irritation. The disposable "catch containers" are not satisfactory.
Many examples were given the survey team of broken needles and/or sharps
projecting through the bags and puncturing the hands of waste handlers. It
would seem that all such items could be deposited in the waste in inexpensive
metal cans, such as a taped soft drink can, so that there is no possibility
of injury to waste handlers.
PATHOLOGICAL WASTE
The quantity is quite small, but as most state laws enforce destruction
in pathological incinerators, it is hand carried, normally red bagged, from
operating rooms, autopsy suite, and animal quarters, and disposed of by burning.
RADIOACTIVE WASTE
This is subject to special regulations originally promulgated by the
Atomic Energy Commission and is disposed of in special containers to special
sites. In a hospital, the total quantity is small.
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AREAS AND HOURS NOT SERVICED BY THE CHUTE SYSTEM
In two of the hospitals, it was determined that at certain time periods,
general waste should be hauled by cart instead of sent through the chute sys-
tem. This thinking has been revealed in several other hospitals studied by
the survey team. The reasoning is that the system should be shut down during
the late evening hours (for example, from 10:30 P.M. to 6:00 A.M.) in order to
ensure better control over the chute loading. To reduce floor waste to a mini-
mum, at least one "sweep" is made of the building during this period, particu-
larly in public lobbies and in the 24-hour Emergency Department. At the Martin
Luther King Hospital, this is not the case and the chutes are available 24
hours a day.
Certain areas are not served economically by the chute system due to de-
sign, or architectural omissions or weaknesses. For example, time studies in
the V.A. Hospital revealed that, for the first floor office areas, at the end
of the business day less labor is required in collecting the waste if a cart
hauling system is used, emptying all waste baskets in one sweep and taking an
entire cart load directly to the compactor.
It has also been pointed out that this applies to dock and receiving area
waste when it is found that, even though small enough to fit the chute system,
due to the close proximity of the compactor less labor is used if it is carted
directly to the collection room rather than to a chute station that would be
further away.
DENSITY OF HAND CARTED WASTE
The table on page 119 reveals that the hand-carted waste is much heavier
per cubic foot (denser) than the waste transported in the pneumatic system.
This would be expected, as the hand-carted waste consists of corrugated card-
board and crating lumber, glass bottles, engineering supplies, maintenance
materials and metal, in as much as 60 percent of its total; whereas the bagged
waste transported by chute is over 90 percent paper, light cardboard, plastic,
and cloth.
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GENERATION POINTS AND QUANTITIES OF WASTE
TRANSPORTED BY CARTS
There is not the consistency of quantity in transporting the type of
waste handled by cart as there is in sending bagged waste in the pneumatic
tube system. This arises from the fact that the bagged waste has a direct
relationship to the number of people in the total population of the building.
The total waste handled by cart is more dependent on the activities of the
ancillary and support departments and particularly, the delivery of supplies
to the hospital and its departments due to the effect of the quantity of
shipping containers in the total load.
As the Veterans Administration Hospital had the largest census, the most
complex ancillary and support procedures,and the heaviest waste load trans-
ported by cart, it reveals these points most clearly among the three hospitals.
Further, the statistics are comparable with other hospitals that use the cart
movement method for solid waste management. The following breakdown of hand-
carted waste in a typical week shows its make-up and the departments that
produce it.
DIETARY
The quantities transported per day were fairly consistent. They averaged
124 pounds in the morning; 166 pounds in the afternoon; and 125 pounds in the
evening. The bulk of this was shipping cartons, followed by tin cans, some
bottles, and a few wooden boxes.
ENGINEERING
Variations from day to day were extremely heavy. The work period was a
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five day week. Variations arose from the assignment of work schedules.
DAY POUNDS
Monday 250
Tuesday 35
Wednesday 50
Thursday 140
Friday 300
WAREHOUSE
The waste consisted entirely of heavy cartons and wooden boxes and dif-
fered considerably from day to day over the five day work period:
DAY NO. CARTONS NO. WOOD BOXES TOTAL WEIGHT LBS.
Monday 184 0 423
Tuesday 89 140 1048
Wednesday 144 30 554
Thursday 214 50 814
Friday 171 0 393
The day to day variations arise from variations in receipts, as well as issues,
to the floors.
SURGERY
The waste load would be expected to tie into the operating room procedure
schedule, and this can be seen from the following breakdown by weight over the
five day work period: GLASS & TOTAL
DAY CONTAMINATED GENERAL CARTONS LBS.
Monday 12 220 10 242
Tuesday 8 268 10 286
Wednesday 12 200 10 222
Thursday 4 168 10 182
Friday 8 112 3 123
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LABORATORY
This department does both clinical and research work. As can be seen
from the figures, it peaks toward the middle of the week and generates waste
over a seven day work period, with a weight breakdown by type as follows:
GLASS &
DAY CONTAMINATED METAL
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
16
4
28
44
36
12
—
36
120
90
90
72
72
—
GENERAL
96
180
186
30
40
88
—
TOTAL WE
CARTONS LBS .
50
18
21
38
18
28
21
198
322
325
202
166
200
21
RADIOLOGY
Compared to other ancillary departments, this is not a heavy producer of
solid waste, and the weight load is fairly level over the five day work period:
DAY
Monday
Tuesday
Wednesday
Thursday
Friday
CONTAMINATED
0
0
0
0
3
GLASS &
METAL
88
72
94
88
64
TOTAL WE
GENERAL
48
48
40
40
48
CARTONS
44
8
28
14
6
LBS.
180
128
162
142
121
CANTEEN
Indicating a fairly consistent level of activities, the weights of waste
generated during the week days are similar from day to day, with a week-end
decline:
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DAY GLASS & METAL GENERAL CARTONS TOTAL WEIGHT LBS.
Monday 60 103 94 257
Tuesday 192 42 74 308
Wednesday 336 24 22 382
Thursday 288 26 68 382
Friday 328 38 15 381
Saturday 0 112 0 112
Sunday 24 64 74 162
With the exception of the warehouse, which generated an average of almost
650 pounds per day, and the canteen at over 280 pounds, the other support de-
partments were quite similar in load, with daily averages ranging from 150 to
slightly over 200 pounds. The above departments added together represent
just under 50 percent of the solid waste transported by cart. The remaining
solid wastes, moved by hand carts, come mainly from the outpatient clinics,
central sterile supply, nursing stations, laundry cartons, inhalation and
physical therapy, and various offices, as recapitulated in the following
figures of pounds produced each 24 hour period, and the breakdown by type:
CONTAM-
DAY INATED &
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
233
398
435
341
482
175
164
GLASS & METAL
NON-COMBUSTIBLE GENERAL
608
860
710
820
596
520
640
452
328
476
286
308
206
223
CARTONS
174
594
286
810
386
174
130
TOTAL
WEIGHT LBS.
1,467
2,180
1,907
2,257
1,772
1,075
1,157
TOTAL 2,228 4,754 2,279 2,554 11,815
LBS PER WEEK
DAILY 318 679 326 365 1,688
AVERAGE LBS
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COMPARISONS OF SYSTEM UTILIZATION
CART-HAULING VERSUS PNEUMATIC TRANSPORT
Each of the three hospitals has a slightly different philosophy on solid
waste management. This involves the total hours of the day active removal and
transport shall take place; the hours during which the pneumatic system will
operate; how the waste shall be initially collected from each room and how it
snail be removed from the floor; the use of specialized personnel to cart-haul
or load chutes versus random removal or loading by general housekeeping maids
and nursing aides; the items and type of waste that will be deposited in the
chutes versus being hauled from the floors by cart. All are supervisor edicts.
These differences in management philosophies have a marked effect on the
utilization of the pneumatic transport system in each hospital. The percent-
age of total waste transported by pneumatic tube, as against the percentage
hauled by cart, differed substantially in each hospital. The differences are
far greater than would be expected and result almost entirely from management
decisions as to the amount and type of waste that will be permitted to be
transported by chute. In each institution the chute wastes are of lighter
weight and greater cube per pound than the cart transported wastes. This ex-
plains the higher percentages in cubic volume as against weight that are trans-
ported by tube.
When the weights of waste are compared between the hospitals we have seen,
for example, that the Veterans Administration generates a total weight of 63
percent more waste per inpatient than St. Mary's and 40 percent more total
weight for its 24-hour population than St. Mary's. When this is analyzed still
further, almost th« entire difference arises from the extreme weight at the
Veterans Administration Hospital in the items that must be transported by cart
rather than sent through the pneumatic system.
Partly this has to do with the hours during which the pneumatic system is
in operation. The details of this are shown later in this chapter. Partly it
has to do with the supply practices in each hospital and the amount of heavy
waste or large bulky waste that is permitted to go onto the floors of the
building and cannot be transported, due to size, by the pneumatic tubes.
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And partly it concerns decisions that certain items will, for one reason or
another, not be sent in the pneumatic system for fear of breakage, bag tear-
ing or other reasons.
In surveying other hospitals that have pneumatic systems, it would be
safe to state that almost all full vacuum systems that have been installed for
transporting waste to date are under-utilized and that too much material is
going around the systems by expensive hand carting methods.
The figures in Table 6 give the comparisons between the three hospitals,
showing the percentage of material by weight and by cubic foot that is trans-
ported in the pneumatic system as against being transported by hand cart.
TABLE 6
COMPARISONS AND UTILIZATION OF TUBE AND CARTS
ST. MARY'S
HOSPITAL
Avg 24 Hour Weight Transported
by Pneumatic Tube
Avg 24 Hour Weight Moved by Cart
Total Weight in Pounds
% of Total Weight Transported
by Tube
Avg 24 Hour Cube Transported by
Pneumatic Tube
Avg 24 Hour Cube Moved by Cart
Total Cubic Feet
% of Total Cube Transported
by Tube
882
1,391
2,273
38.8%
382
185
567
67.4%
V.A.
HOSPITAL
1,115
3,330
4,445
25 . 1%
557
1,018
1,575
35 . 4%
MARTIN LUTHER
KING HOSPITAL
2,218
1,460
3,678
60 . 3%
1,008
180
1,188
84 . 9%
As seen in the chapter on economics, hand carted waste is expensive
material to transport, requiring as much as 21 manhours per day to clear it
from the floors and move it to the central collection point, for the hospitals
in the present study.
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QUANTITIES OF WASTE TRANSPORTED BY PNEUMATIC TUBE
Seven consecutive 24-hour surveys were conducted at each of the hospitals
to analyze the waste transported by the pneumatic system and to determine:
Where the waste originated
Of what it was comprised
In what chute station it was discharged
At what time of day it was discharged
What were the weights and cubes transported, by type of
waste, time of day, and chute station
What were the weights and cubes of the individual loaded bags
The surveys were conducted at all chute loading doors in the house simul-
taneously, with every bag recorded at every door before deposit into the chutes,
THE SIZING OF UNIT LOADS
The comparisons between the three hospitals of quantities of waste trans-
ported by pneumatic tube must take into consideration the size of the tube and
hence the size of the transport bag used.
Martin Luther King Hospital uses a gravity to vacuum system with a 20"
tube. This permits the use of a bag as large as 29-1/2" wide by 35" long in
the flat; which could produce a fully loaded bag 19" diameter by 25" long,
holding A.I cubic feet of waste.
Both the Veterans Administration Hospital, San Diego, and St. Mary's
Hospital, Duluth, use 16" diameter tubes; permitting the use of bags 23-1/2"
wide by 33" long in the flat, giving a fully loaded bag 15" diameter by 25"
long, holding 2.3 cubic feet.
In view of the cost of transport bags and the waiting times involved in
a full vacuum system, there is a need to load bags as full as practical with
regard to bulk or volume. Weight will obviously vary, depending on the nature
of trash and its compaction in the bag. Surveys reveal that "fully loaded"
15" by 25" bags will vary in total weight, from 3.5 pounds to over 13 pounds,
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with the normal filling practices of housekeeping workers. The "average"
weight of this size bag should be 6.0 to 7.2 pounds when loaded with hospital
chute trash, depending upon whether glass bottles and metal have been included.
The larger bags used in the gravity to vacuum system will average 10.7 pounds
fully loaded, and up to 12.0 pounds average if all glass and metal is deposit-
ed in the chutes.
A three mil thick plastic trash bag will easily support these weights of
waste in the cubes that are listed above. Further, it was discovered at St.
Mary's that such bags have a considerable amount of stretch and could be con-
siderably overloaded as to cube and still go through the system without tear-
ing or without plugging the system, as they "elongate" during transport.
Measurements of a representative succession of bags showed the following dia-
meters and lengths:
16"x29"
17"x24"
16"x25"
17"x29"
14"x29"
14"x22"
16"x24"
21"x26"
19"x28"
15"x27"
20"x27"
18"x29"
16"x29"
15"x27"
21"x25"
16"x25"
13"x26"
17"x27"
21"x29"
19"x30"
16"x26"
18"x24"
15"x24"
21"x28"
17"x26"
15"x27"
19"x27"
19"x26"
18"x25"
16"x23"
17"x23"
DAJLi" QUANTITIES TRANSPORTED
The figures reveal an important fact about pneumatic tube transport sys-
tems. Hospitals that have installed 16" diameter tubes show considerable dif-
ferences in the average cube and weight of the bags of waste that are trans-
ported, while at the same time the density of the waste only varies from 10
percent to 15 percent between such hospitals. This is evident in studying
the figures from the Veterans Administration Hospital and St. Mary's, with a
difference of 44 percent in cube and 70 percent in weight for the average bag
load between these hospitals and only 13 percent in waste density.
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The main reason in all hospitals studied appears to arise from experiences
with plugging and bag breakage when the tube system first starts in operation.
Each hospital experiments with the bagging methods used to avoid this. One
hospital will reduce the loading of individual bags to ensure they are kept
rather small. Another, such as St. Mary's, will lean toward double bagging in
extremely strong bags, even to the point of adding nylon mesh reusable bags
over these. As a result, the loading of individual bags is increased as the
hospital finds the bags are standing up to transport.
Surveying the total number of waste bags placed in the pneumatic system
in the seven consecutive days that were studied, we find the following:
TABLE 7
DAILY QUANTITIES OF WASTE TRANSPORTED IN PNEUMATIC SYSTEM
DAY OF WEEK
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
Weekly Total
Daily Average
Daily Average Cube
Average Bag Weight
Average Bag Cube
Average Weight of
Waste Transported
ST. MARY'S
HOSPITAL
BAGS { LBS .
|
148 | 902
155 j 942
165 j 973
146 1 949
154 919
138 j 801
123 j 689
1029 | 6175
147 j 882
382 cu ft
6.00 Ibs
2.6 cu ft
2.3 Ibs/
cu ft
V.
A.
HOSPITAL
BAGS
170
416
342
571
186
329
206
2210
316
557
LBS.
612
1513
1165
2070
651
1119
679
7809
1115
cu ft
3.53 Ibs
1.8
2.0
cu ft
Ibs/
cu ft
MARTIN LUTHER
KING HOSPITAL
BAGS LBS.
562 2360
522 2192
668 2806
521 2188
662 2780
281 1180
482 2024
3698 15,530
528 2218
1008 cu ft
4.20 Ibs
1.9 cu ft
2.2 Ibs/
cu ft
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FLOOR COMPACTORS
The survey team did an investigation on the use of household compactors
in the three hospitals and found that none were in use. The theory of install-
ing these units by each chute station is that they are inexpensive and will
pay for themselves in under four years by increasing the density and reducing
the bulk volume of waste sent through the system. With the waste generated in
the nursing floors and support departments, it has been discovered that one of
these units gives an average compaction rate of approximately 4 to 1. Pre-
sumably this would reduce the number of bags by 4 to 1 and reduce chute loading
waiting time. It would also increase the weight of each bag by at least four
times and would provide more uniform bag loading.
Not enough hospitals have installed these small home compactors to date
to prove their economic feasibility. However, it is knoxm that, as the cost
of bags used in these is approximately four times the cost of chute bags, no
savings would be obtained in this aspect. Further, they represent one more
step in the process and would add extra labor for lining the chamber with the
compactor bag. As against this, chute loading total time would be reduced 75
percent in a full vacuum system and a much tougher transport bag would be used.
With the exception of large cartons and boxes, cart hauled waste could also be
reduced by 75 percent in bulk.
It would appear worthwhile to study the pros and cons of these units.
CHUTE LOADING HOURS AND VOLUMES
When the figures for waste bags alone are studied, the hourly quantities
placed in individual stations are not particularly large. However, with the
full vacuum systems of St. Mary's and the Veterans Administration, the sta-
tions must be examined for the ability to handle trash and linen at virtually
the same time, and the totals of both within a given hour must be recorded to
show the volume ability of the system.
At first glance it would appear that a full vacuum system,capable of
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receiving only one bag at a time,is quite limited in volume capacity. St.
Mary's, with separate waste and linen tubes, was able to put through the sys-
tem in the morning peak single hour between 110 and 120 bags maximum, of
waste and linen combined.
The Veterans Administration, using a multiple loading and single tube,-
full-vacuum system, and with a specialized operator doing the chute loading
for the entire hospital, was able to send as high as 232 combined laundry and
waste bags through in a single morning peak hour; or over twice what the
limits of the single bag transport system set, despite the use of a single tube,
The housekeeping management practices do enter into this loading speed.
It will be seen that St. Mary's loads waste and linen bags into the system at
a relatively even rate from early morning until late evening, over a 17 hour
period. The Veterans Administration, on the other hand, does the majority of
the station loading in 4 to 6 very high peak hours per day, in the mid-morning
and early afternoon.
These patterns are created by the management system used in each hospi-
tal. St. Mary's uses random loading, in which all maids and porters from
housekeeping that clear the rooms and hospital support departments, and all
nursing aides that handle the laundry on the various floors, also deposit bags
in each of the chutes as they generate them. At the Veterans Administration,
the housekeeping and nursing aide personnel merely clear the areas, tie the
bags, and take them to the chute rooms for temporary storage. One operator
then goes from floor to floor, four to six times per day, and puts the bags
down the chutes on a multiple loading basis. Further, at the Veterans Admin-
istration Hospital, the clearing period from patient rooms and support activi-
ties is over a much shorter time period, and without the late afternoon and
early evening hours found in a community hospital handling private patients.
Figures 11 through 16 show the loading of each chute station in each hos-
pital over each hour of the day that the pneumatic transport system is in
operation. These surveys, over seven consecutive days, reveal clearly the
loading patterns used in each hospital. They also show the management prac-
tices on the part of housekeeping, maids, and aides in clearing the floors;
and they reveal the ability of each system to handle a given volume per hour
from individual stations.
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ST. MARYS HOSPITAL.
SEVEN DAY CHUTE LOADING
FIGURE 11.
5-6 6-7 7-8
~i— —r
8-9 9-10 10-
MORNING
11-12 12-1
2-3 3-4 4-5
AFTERNOON
5-6
LOADING BY TIME OF DAY
~\— —r
6-7 7-8 8-9 9-10
EVENING
FIGURE 12
-E 2-W 2-C 3-E 3-W 3-C 3-E 4-W 4-C 4-E 5-W 5-C 5-E 6-W 6-C 7-W 7-C 8-W 9-W 10-W
I-W I-C
LOADING BY CHUTE STATION
-137-
LEGEND
Monday Friday
Tuesday Saturday
Wednesday Sunday
Thursday
-------
VETERANS ADMINISTRATION HOSPITAL
SEVEN DAY CHUTE LOADING
FIGURE 13
110.
"00 .
80 .
LEGEND
Mondoy ._._ Friday
Tuesday _„_ Saturday
Wednesday Sunday
Thursday
0 .
I-W I-E 2N 2-W 2-S 2-E 3-N 3-W 3-S 3-E
4-W 4S 4-E 5-N 5S 5-E 6N 6-W 6-S 6-E
LOADING BV CHUTE STATION
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5-6
VETERANS ADMINISTRATION HOSPITAL
SEVEN DAY CHUTE LOADING
FIGURE 14
LEGEND
....Monday Friday
Tuesday Saturday
Wednesday . —Sunday
Thursday
7-8
8-9 9-10
MORNING
10-11 11-12 12-1
2
2-3 3-4
AFTERNOON
4-5
5-6 6-7
7-8 8-9
EVENING
9-10
LOADING BY TIME OF DAY
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200
MARTIN LUTHER KING HOSPITAL
SEVEN DAY CHUTE LOADING
FIGURE 15
180.
160 .
I 40 .
130.
100-
80.
20
LEGEND
.... Monday —Friday
Tuesday Saturday
Wednesday . Sunday
Thursday
A-l A2 C-2 C-3 B-A Bl S-I-I WA-I S-I-2 \rV-C2 WB-2 WA2 SI3 WC-3
W63 S14 WC4 W6-4 WA4 SI5 WO5 WB5 WAS
LOADING BY CHUTE STATION
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14 0
I00_
80.
60.
40_
20_
MARTIN LUTHER KING HOSPITAL
SEVEN DAY CHUTE LOADING
FIGURE 16
Mondoy
Tuesday _
Wednesday
Thursday
— Friday
— Saturday
Sunday
8-9 9-10
MORNING
2-3 3-4 4-5
AFTERNOON
6-7 7-8 8-9 9-10
EVENING
LOADING BY TIME OF DAY
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THE INTERFACING OF SOILED LAUNDRY AND WASTE IN THE PNEUMATIC SYSTEM
No hospital has installed a pneumatic tube transport system for waste
alone. In each case soiled laundry is moved along with the waste, either in
the same tube, or in separate tubes, usually with a common fan. Studies of
the loading figures in hospitals such as St. Mary's and the Veterans Adminis-
tration always reveal that the quantities of laundry transported in the system
exceed the waste, in cube, in pounds, and in number of bags sent per hour.
Further, the movement of laundry always takes precedence over the movement of
waste, Only when two entirely separate systems are installed (as in the case
of Martin Luther King) can waste removal be completely independent of laundry.
In St. Mary's and the Veterans Administration, using the full vacuum sys-
tem dependent on a single fan and, in the case of the V.A., restricted to a
single tube, the waste management is highly influenced by the removal of laun-
dry. When laundry must be transported, the system is not available for waste
transport. The figures in Table 8 show how important this influence can be.
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TABLE 8
DAILY QUANTITIES OF WASTE AND LAUNDRY TRANSPORTED BY PNEUMATIC SYSTEM
NUMBER OF BAGS
Day of Week
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
Totals
Daily Average
Percent of Total
Avg.per Operating Hour
ST. MARY'S
HOSPITAL
Waste
148
155
165
146
154
138
123
1029
147
20%
8
Laundry i Total
695
685
648
i
604
561
! 448
! 438
i 4079
1
! 583
i
j 80%
843
840
813
750
715
586
561
5108
730
! 34 42
V.A.
HOSPITAL
Waste
406
342
571
186
329
206
170
2210
316
46%
80
1
Laundry
336
414
506
323
368
261
395
2603
372
54%
80
1
Total
742
756
1077
509
697
467
565
4813
688
96
MARTIN LUTHER KING
HOSPITAL
Waste | Laundry, Total
j j _
562
522
668
521
662
281
482
3698
528
56%
29
344
337
726
354
532
213
406
i 1
2912
416
44%
23
906
859
1394
875
1194
494
888
6610
944
52
UJ
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WASTE GENERATION POINTS AND VOLUMES
From what has been described in the preceding sections, we have seen that
it is virtually impossible to plan a pneumatic transport system and locate the
stations throughout the hospital so that they are loaded equally. Some depart-
ments and nursing floors and wings generate much more waste than others. The
science in designing the layout of such a system is to attempt to place the
stations so that the load is somewhat equalized and that each and every station
can be proven to be worth the expenditure involved in installing it.
Table 9 gives an indication of the equality or inequality of loading of
the individual stations with a combination of waste and laundry bags in each
hospital.
TABLE 9
UTILIZATION OF CHUTE LOADING STATIONS
Hospital
St. Mary's
Veterans
Administration
Martin Luther
King
Total No. of
Stations
Waste — 22
Laundry — 19
Waste— 27
Laundry — 27
Waste — 24
Laundry — 19
No. of
50% of
8
5
6
5
6
6
Stations Used for Sending
Bags 80% of Bags
13
9
11
9
11
10
The pneumatic system was laid out quite differently by the designer in
each of the three hospitals with regard to the departments and stations that
are to be serviced by a given chute station. Hence, direct comparisons are
difficult to make between the hospitals as to the efficiency of the location
of the individual stations, particularly with regard to the ancillary and sup-
port departments. This is heightened by the different concepts in each of the
three institutions concerning what should be hand-carted, versus what should
be transported by the pneumatic system.
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Examined individually, the three hospitals show the following
patterns in a seven day week for each station, rated in descending
the volume of waste bags each station handles.
STATION
Dietary
Intensive Care, P.A.R.,
Floor Dietary, Nursing
O.B., GYN., Nursery,
Floor Dietary, Nursing
C.C.U., Nursing, Floor
Dietary
Med-Surg Nursing
Obstetrics
Med-Surg Nursing
Floor Dietary, Nursing
E.R., X-ray
Floor Dietary, Formula
Room, Nursing
STATION
Nursing
Nursing
Nursing
Nursing
Outpatient Clinics
Nursing
Nursing
Nursing
Nursing
Intensive Care,
Nursing
Nursing
Nursing
NO. OF
BAGS
111
ST. MARY'S
STATION
94
93
67
63
58
54
51
50
49
Med-Surg Nursing
Surgery
Med-Surg Nursing
Med-Surg Nursing
Med-Surg Nursing
Floor Dietary, Nursing
Offices
E.R., X-ray
Offices
Central Sterile Supply
Main Lobby
Laboratory
VETERANS ADMINISTRATION
NO. OF
BAGS
259
208
207
167
155
149
147
141
130
117
97
96
STATION
Nursing
Offices
Med. Illus.,
Card io-Pulmonary
Nursing
Animal Research O.R.
and Lab
Animal Research Lab
Nursing
Animal Research Lab
Animal Quarters
Surgery N
Surgery S
Central Sterile Supply
loading
order of
NO. OF
BAGS
46
43
40
37
37
35
32
25
20
17
10
2
NO. OF
BAGS
89
73
59
55
32
17
10
2
0
0
0
0
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NO. OF
STATION BAGS
Pediatrics, Segment I,
5th Floor 485
Nursing, Wing C,
4th Floor 328
Nursing, Wing A,
3rd Floor 296
Orthopedics, X-Ray,
Segment I, 1st Floor 295
Offices, Wing A,
1st Floor 290
Nursing, Wing B,
4th Floor 279
Obstetrics, Segment I,
2nd Floor 230
O.K. & Labs,
Segment I, 3rd Floor 227
Nursing, Wing B,
3rd Floor 208
Nursing, Wing C,
2nd Floor 205
Nursing, Wing A,
4th Floor 178
Clinics, Segment I,
4th Floor 161
MARTIN LUTHER KING
STATION
Nursing, Wing A,
2nd Floor
Trash Room, C-2
Nursing, Wing C,
3rd Floor
Nursing, Wing B,
2nd Floor
Autopsy, Offices,
Basement A
Kitchen, A-2
Central Sterile
Supply, C-3
Kitchen, Offices,
B-l
Nursing, Wing B,
5th Floor
Not Used, Wing C,
5th Floor
Not Used, Wing A,
5th Floor
Laundry, A-l
NO. OF
BAGS
139
118
89
69
45
27
20
5
4
0
0
0
1 Ross Rofmann, Associates, Solid Waste Surveys of 43 Hospitals, 1970-1971,
unpublished.
2 Ibid.
3 Brewer, J. B., A Case History, in Proceedings, A.H.A. Institute on Hospi-
tal Solid Waste Management, Chicago, May 18-20, 1972.
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7-OPERATIONAL AND PERFORMANCE ANALYSIS
To analyze the operation and performance of a pneumatic transport system
the most revealing documents are the daily maintenance reports made by the
hospital engineering staff. All three hospitals in this study keep excellent
maintenance records and these were made available to the survey team covering
the period from the first day of operation through November, 1973. In the
case of Martin Luther King, this period was 23 months; 20 months for Veterans
Administration; and 47 months for St. Mary's.
These records recorded every malfunction in each system, whether from
mechanical failure or from misuse by operating personnel.
Of the three systems studied, the one at Martin Luther King General Hos-
pital had the highest installed cost at $425,000. It also had the largest
total length of tubing, with over 1,400 ft for waste alone. Comparable fig-
ures for the other two hospitals were $350,000 system installed cost at Vet-
erans Administration Hospital, with a total of 1,894 ft of tubing used for
both laundry and waste; and $193,000 system installed cost at St. Mary's, with
a total of 1,700 ft of tubing for waste and linen combined.
The Martin Luther King installation has 20 in. diameter tubes of 3/16 in.
wall thickness in the horizontal tubes and a combination of 14 and 10 gauge
metal in the vertical chutes. It is a gravity to vacuum system. The other
two systems both use smaller diameter tubes of lighter metal—16 in. diameter
and 20 gauge metal—and are full pneumatic systems with loading hoppers.
The maintenance practices of the three hospitals differ slightly, and
comparisons in maintenance hours used per year must be made very carefully to
ensure that the hospitals, and therefore, their systems, are being compared on
an identical basis.
In analyzing the maintenance of any system, if detailed records are kept
by the engineering department, it will be seen that maintenance hours are re-
corded under three different classifications. The first involves corrective
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maintenance, and fro® the point of view of determining the efficiency of any
system and analyzing its operation and performance, it is the "corrective"
hours that must be expended that reveal most clearly the problems involved
with the system. Any efficient engineering department carries on a preventive
maintenance program, which is used on a constant daily, weekly, or monthly
basis to catch trouble before it occurs and prevent breakdowns in any of the
operating parts of the system. In two of the hospitals (Martin Luther King
and the Veterans Administration) a considerable number of maintenance hours
are being used each year under a classification that is not "corrective" main-
tenance and is something less than "preventive" maintenance. We have termed
this "routine" inspection of the system by the maintenance department. This
comes about because a full man, or part of a man, is assigned full time to
the system, to be on call during normal working hours to handle any problems
that arise with the system. He is not assigned any other duties for these
particular hours and, therefore, his time can only be charged against maintain-
ing the system. Presumably, he is not sitting in an office during these hours
but, instead, is out walking the hospital and determining, on a constant basis,
that the system is operating properly.
Table 10 shows the actual hours recorded from the beginning by each hos-
pital for maintaining their pneumatic transport system, adjusted to a twelve
month average.
TABLE 10
AVERAGE ANNUAL MAINTENANCE HOURS
Corrective Preventive Inspection
St. Mary's 424 284 none
Veterans Administration 454 813
Martin Luther King 171 240 441
The above figures clearly reveal that the least amount of corrective main-
tenance was performed on the heavy wall system at Martin Luther King. The
bulk of this was devoted to making changes in certain architectural areas that
interfaced with the system, with such changes chargeable to the system. The
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corrective maintenance time at St. Mary's and the Veterans Administration is
almost identical on an annual basis. As can be seen from the following ac-
count, in the case of St. Mary's it was used to repair damage to the system
caused by excessive vacuum or vibration and the effects on either the tubing
and fittings or the mounting hangars; while in the case of the Veterans Admin-
istration, it was devoted to basic modifications and replacement of components
of the system, such as collectors and diverters. Due to the assignment of
personnel on a full time basis at the Veterans Administration, in order to
keep the system running, it was virtually impossible to divide the "non-
corrective" work between preventive hours and inspection hours.
The most serious operational problems in the Martin Luther King installa-
tion were revealed shortly after the hospital started up the system and they
cannot be blamed on the system vendor, but rather on architectural designs of
surrounding areas.
Laundry was to be collected at the end of the tube line in a plastered
room with a closed door. It was discovered that plastered walls lacked the
strength to withstand the vacuum pulled by the system. A large steel room was
built within the linen collection room to act as a collector and solve the
problem.
The original valve rooms were not vented and again the plaster walls would
not stand the vacuum pulled through the slide valves. Vented doors have been
placed in all such rooms.
The waste bin under the vendor's collector was supplied by the general
contractor, not the system vendor, and was constructed with sloping sides which
tend to bridge, slowing the drop to the compactor at times.
Materials used in maintenance have been door locks, air valves, and var-
ious filters in the system. The filters alone account for 68 percent of all
materials used for maintenance.
The Veterans Administration Hospital appears to have had the most drastic
changes in the basic design and construction of the system, as a result of main-
tenance experience showing weaknesses in operation and performance. This might
be expected as it is a single tube system, attempting to transport both waste
and laundry in the same tube, with great variations in bag weights and cubes
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between the two products, as well as potential interferences of one with the
other.
Shut downs of as long as 30 days occurred during the first 16 months of
operation while sections of the system were rebuilt.
At Veterans Administration Hospital, other than, the normal replacement of
filters, the most prevalent problem has been with diverter valves and the at-
tendant waste and laundry plug-ups which result when these valves malfunction.
New diverter valves were installed which are more positive in action and there-
fore not as prone to jam. Also, a new cyclone collector was installed above
the compactor which reduces bag breakage and plug-ups, and problems with the
travel timers were rectified.
In addition to plug-ups attributable to problems with the diverter valves,
Veterans Administration Hospital also experienced many instances of lighter
bags overtaking heavier bags in the tubes, which also causes plugs. Over the
18 month period covered by the maintenance records in our possession, there
were a total from all causes of 62 instances of trouble with the tubes plug-
ging, some involving as many as 100 bags of linen. Of these, 35 were cases of
linen blockages, 20 were cases if waste bag plugs, and 7 were not identified
as to cause. It should be pointed out that the average blockage requires two
men seven hours to clear.
The system operating procedures were changed from single bag loading (as
is used at St. Mary's) to a keylock multiple bag loading. A single operator
per shift was then placed in charge of all chute loading throughout the build-
ing. Under the new operating procedures, to avoid the cycling of the diverter
valves as much as possible, all linen is supposed to be moved from all floors
in the hospital first, starting at the top floor and working down. Following
this, the system is shifted to waste transport and all waste is removed, from
the top floor down. This reduces wear on the diverter valves and tends to re-
duce jams.
The downtime of this system is more frequent on the weekend (usually four
or five times) than during the week. It is felt that this is related to more
efficient operational control of the system during the week.
An examination of the maintenance records of St. Mary's Hospital reveals
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that most of the trouble with the pneumatic system involves laundry blockages
and waste bag plugs. This has resulted in tubes and air lines collapsing, and
therefore requiring replacement; as well as seams rupturing, which require
riveting or strengthening. Over the 2.16 year period covered by the mainten-
ance records in our possession, there have been a total of 297 instances of
trouble with the tubes plugging. Of these, 142 were cases of laundry blockage,
68 were cases of waste bag plugs, and 87 were not identified as to the cause.
There were also 14 occasions when either a tube collapsed or a seam split to
the point of requiring riveting. In general, St. Mary's has solved all prob-
lems of tube plugging and bag breakage by the use of nylon transport bags.
However, it is obvious that the 20 gauge metal in the bends and tube of the
system is on the light side for trouble-free operation. Further, St. Mary's
feels that single bag loading is unnecessarily time consuming for a hospital
of this size, resulting in expensive labor waiting to load chute stations.
All three of the pilot systems studied are equipped with fusible link
fire dampers, as required. There was no indication that a fire had actually
occurred in the systems. However, these fire dampers have been a cause of bag
ripping and occasional plugs of the system.
None of the systems appear to have experienced serious shut-downs from
electrical or hydraulic line problems. St. Mary's has experienced some freez-
ing weather problems in roof dampers which were corrected by air drying units
being installed.
The three systems have entirely different exhauster fan-filter arrange-
ments as well as design of the dampers or valves ahead of the fan to protect
the system in case of high vacuum from a plug in the system. The most sophis-
ticated and best working is at Martin Luther King. Fan protection has been
100 percent with the bag filter installed ahead of the fan. No tube damage
from plugging has occurred. At Veterans Administration, a rollomatic filter
is installed ahead of the fan and appears to operate efficiently. Initially
there was no relief valve ahead of the fan at the V.A. and when excess vacuum
was drawn as the result of a plug, fan noise and vibration was considerable.
This has been corrected by installing a quick acting relief system.
These two systems offer a good comparison between the two types of pre-fan
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2 micron filters. Both the bag and the rollomatic filters operate efficiently.
However, changing the bag filters appears to involve considerable maintenance
labor.
St. Mary's also had a fan relief valve installed ahead of the fan, after
the installation was made. It is less sophisticated than the other two and
does not appear to work as efficiently. There is no filter ahead of the fan
and the lack of it has resulted in fan damage from lint and dust adhering to
the fan blades. At one point, the fan became so unbalanced that the vibration
cracked the motor base. It appears that a pre-fan filter is a necessity.
Both the Veterans Administration and Martin Luther King discharge directly
from the collector to the compactor receiving bin. The slight additional cost
for direct discharge appears to greatly improve the operation from a sanitary
viewpoint. When the time to cart haul from the collector to the compactor and
hand load the compactor (St. Mary's) is factored, it would appear that enough
labor could be saved in approximately two and a half years to amortize a direct
loading arrangement.
The time required to clear a pneumatic transport system of a plug (either
laundry or waste bags) differs considerably between the three hospitals. The
surveys that were conducted reveal the absolute necessity of clean-out ports
located strategically throughout the system, should plugging occur. Unless
these are present, the normal procedure is to either "fish" the bags back to
the nearest loading station or, alternatively, to physically remove a section
of horizontal tubing in the general location of the plug (if the location can
be determined), remove the bags, and reconnect the tube. Obviously, this is
extremely time consuming for the maintenance department. Clean-out ports do
not appear to be included in the original designs of pneumatic transport sys-
tems of the thin wall, full pneumatic type. They are usually included in the
designs installed by Envirogenics utilizing gravity to vacuum and heavy wall
tubing, and normally they are strategically placed at locations where the hori-
zontal tubing commences a vertical rise. ihis makes bag removal fairly simple.
All three systems have experienced plugging from improper loading from
time to time and it would appear that the principal management solution is to
carefully control the personnel using the system.
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All have experienced some cross-over between waste ending up in the laun-
dry collector and laundry in the compactor. In the case of St. Mary's and
Martin Luther King, this is due 100 percent to operator carelessness in loading
the chute doors, as these are double tube systems. In the case of the Veterans
Administration, it is felt that the problem has been created by faulty opera-
tion of the diverter valve in the single tube system.
As pointed out in the chapter on Design and Construction, the single bag
systems are the most costly in labor utilization, and a single tube, single bag
system uses the most labor in waiting time of any method. The multiple bag,
double tube system is far less expensive to load; with the gravity chute to
vacuum tube, and random loading, the least expensive from a labor viewpoint of
any method. This is completely borne out in the labor figures for the three
hospitals, as can be seen from the chapters on Economics.
All three hospitals are designed differently architecturally but all have
at least four vertical wings to service, involving either horizontal walking
distances on each floor to vertical chutes installed on a "zoned" basis, or
the necessity for at least four vertical risers. The result, as can be seen
from the chute station utilization figures, is that a relatively small number
of stations carry the bulk of the load and the remaining are installed on a
convenience basis. With the multiple bag system installed at two of the hospi-
tals (Martin Luther King and V.A.). the floor pick-up time, and walking time to
the chute stations, far exceeds the loading time. At St. Mary's, where consid-
erable waiting time is involved to load the single bag stations, pick-up and
walking time is slightly less than loading time.
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0-CODES AND REGULATIONS
Solid waste handling in hospitals is affected by a series of codes and
regulations. As virtually all construction in a hospital requires a building
permit, it involves, normally, submittal of drawings and specifications for
the proposed construction and approval of the finished work by regulatory
bodies. This usually involves a local building department; the local and/or
state fire marshal regulatory bodies, either local or state, concerned with
the construction and operation of hospitals; and, if Federal Hill-Burton
money is involved, the approval and inspection of the Hill-Burton agency and
its regional office.
Probably the most important aspect in such approvals, when solid waste
is involved, concerns the fire safety aspects. National fire codes, as pub-
lished by the National Fire Protection Association (NFPA) are used as the
basis for approvals for rubbish handling facilities and incinerators by most
local and state jurisdictions. The latest codes are the 1972-1973 version.
Building Construction and Facilities are covered in Volume 4, with the
standards on incinerators and rubbish handling covered in Standard 82.
Sections 70 and 80 of this Standard cover rubbish or solid waste chutes
and systems. Sections 10 and 30 cover incinerators.
It should be noted that NFPA, in their Standard, does not include design
criteria for the purpose of reducing air pollution. They state that for such
criteria the authorities having jurisdiction should be consulted.
The following paragraphs from Sections 70 and 80 directly apply to solid
waste management in hospitals, the control of system design, and the inspection
of the facilities by agencies that are guided by the NFPA codes.
70. Rubbish Chutes
701. General
7011. Rubbish chutes are usually employed where there is a
relatively large area on each floor from which rubbish is collected. This
makes a chute a convenience in handling rubbish in many manufacturing plants,
apartment houses, office buildings, and institutions. The procedure is to
bring the collected rubbish from each floor to the opening in the chute. The
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chute then conveys the refuse to its disposition point. A rubbish chute shall
serve no other purpose.
7012. There are three types of rubbish chute systems, each
with separate fire safety criteria.
a. General Access Gravity Type Rubbish Chute.
b. Limited Access Gravity Type Rubbish Chute.
c. Pneumatic Rubbish Chute.
7013. Definitions.
a. General Access Gravity Type: A rubbish chute of this
type is an enclosed vertical passageway in a building to a storage or compact-
ing room where the rubbish is transferred by gravity only. All occupants of
the building are free to use the chute at any time.
b. Limited Access Gravity Type: A rubbish chute of this
type is an enclosed vertical passageway in a building to a storage or compact-
ing room where the rubbish is transferred by gravity only. Authorized person-
nel only may use this chute, gaining entry by key to a locked chute door.
c. Pneumatic Rubbish Chute: A rubbish chute of this type
has limited access. It may be a vertical, horizontal, or inclined enclosed
passageway and having sufficient mechanical applied airflow to convey refuse
without clogging to point of disposition.
702. Construction
7021. A steel or steel-jacketed refractory chute may be support-
ed at intervals by the building structure, in which case expansion joints
shall be provided at each support level. Other kinds of chutes shall rest
upon a substantial noncombustible foundation having a fire-resistance rating
of at least 3 hours.
7022. Gravity chutes should be constructed straight and plumb
with no offsets whenever possible. If offsets are required they shall deviate
not more than 15° from the vertical, and shall be properly reinforced. All
chute interiors shall be smooth and without projections.
7023. The size of a refuse chute shall be in accordance with
the following:
a. Gravity Type Chutes: The size of the chute shall not
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be less than 22-1/2 by 22-1/2 inches or 24 inches in diameter inside measure-
ment.
b. Pneumatic Conveyor: The size of the chute shall not
be less than 16 inches diameter, inside measurement.
7024. Masonry rubbish chutes shall be constructed of clay or
shale brickwork not less than 8 in. thick or of reinforced concrete not less
than 6 in. thick. Such chutes shall be lined with firebrick (ASTL Type G, low
duty, or the equivalent) not less than 4-1/2 in. thick.
7025.
a. Metal rubbish chutes shall be made of stainless steel
or galvanized or aluminum-coated steel with no screws, rivets, or other pro-
jections on the interior surface of the chute. Laps or joints shall be of a
design so that liquid will drain to the interior of the chute. The steel shall
not be lighter than as indicated below:
1. For chutes handling Type 2 or Type 3 wastes, or a
combination of both, the portion of a chute located not more than 6 stories
'below the roof of the building shall be made of steel not lighter than No. 18
gage and any other portion shall be made of steel not lighter than No. 16 gage.
2. Chutes handling wastes other than Type 2 or Type 3
shall be made of steel not lighter than No. 14 gage.
b. Metal chutes may be lined with firebrick (ASTM Type G,
low duty or the equivalent) not less than 2-1/2 inches thick. Unlined steel
chutes shall be equipped with automatic sprinklers installed in accordance with
NFPA Standard No. 13, Section 4310 and other applicable provisions, and the
outlet of the chute shall be equipped with a self-closing steel door held open
by a fusible link.
c. Rubbish chutes may be made of listed medium-heat ap-
pliance chimney sections approved for this use.
d. Rubbish chutes, other than masonry chutes conforming
to 7024 or constructed of masonry walls having a fire resistance rating not
less than specified below, shall be enclosed in all stories above the storage
or compacting room within a continuous enclosure constructed of materials
which are not combustible, such as masonry, and extending from the ceiling of
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the storage or compacting room to or through the roof so as to retain the
integrity of the fire separation as required by applicable building code pro-
visions. The walls of the enclosure or the walls of the masonry chute shall
have a fire resistance rating of not less than 1 hour if the building is less
than 4 stories in height and not less than 2 hours if the building is 4 or
more stories in height. Any opening in the enclosing walls shall be equipped
with self-closing fire doors approved for Class B openings.
7026. A rubbish chute shall extend (full size) at least 4 ft.
above the roof of the building. The chute shall be open to the atmosphere.
703. Service Openings
7031. Service openings shall be provided in accordance with
the following criteria:
a. General Access Gravity Chutes: All service openings
into a rubbish chute shall be provided with a self-closing, self-latching,
bottom-hinged hopper-type door approved for Class B openings and having a
rating of not less than 1 hour with "Temperature rise: 30 min.-250° F max."
The door frame shall be firmly built into the chute and the design and in-
stallation shall be such that no part of the frame or door will project into
the chute.
b. Limited Access and Pneumatic Chutes: All service open-
ings into a rubbish chute shall be provided with self-closing, self-latching
doors approved for Class B openings and having a rating of not less than one
hour with "Temperature rise: 30 min.-250° F max." The door frame shall be
firmly built into the chute and the design and installation shall be such that
no part of the frame or door will project into the chute.
7032. The area of each service opening shall be limited to
one-third of the cross-sectional area of the chute.
7033. Every service opening shall be enclosed in a room or
compartment separated from other parts of the building by walls and floor and
ceiling assemblies having a fire-resistance rating of not less than 1 hour
with openings to such room or compartment protected by approved fire doors
suitable for Class B openings.
704. Chute Terminal Rooms or Bins
-157-
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7041. Rubbish chutes shall terminate or discharge directly into
a room or bin separated from the incinerator room and from other parts of the
building by walls and floor and ceiling assemblies having a fire-resistance
rating equal to that specified for the chute. Openings to such rooms or bins
shall be protected by approved self-closing or automatic fire doors suitable
for Class B openings.
7042. Rubbish chutes other than charging chutes covered in
Section 40 and combined chimney flue and charging chute covered in Section 50
shall not discharge directly into an incinerator.
705. Automatic Feeding or Stoking Systems
7051. Systems for the automatic transfer of waste materials
from a rubbish-chute terminal room or bin to an incinerator or other means of
automatic feeding or stoking incinerators shall not be installed unless special
permission of the authority having jurisdiction has been obtained.
NOTE: There may be situations where arrangements are made for
handling refuse mechanically and automatic stoking of incinerators which would
not introduce an unreasonable hazard. In such cases, the authority having
jurisdiction may permit such an arrangement, taking into consideration the
whole layout, its relation to the rest of the building, the presence or absence
of complete sprinkler protection, the continuity and competence of the personal
supervision attending the operation, ventilation, access for fire fighting, and
similar factors. See also Standard for Installation of Blower and Exhaust Sys-
tems for Dust, Stock, and Vapor Removal, NFPA No. 91.
706. Automatic Sprinklers
7061. Automatic sprinklers, properly installed, provide a
reliable and effective means for fire extinguishment and shall be installed in
chute terminal rooms or bins. A short length of hand hose connected to a
suitable water supply should also be provided. Fires of the nature likely to
occur at chute terminals are generally difficult to control by ordinary means
due to the large amount of smoke evolved and consequent difficulty of access
by the fire department. Automatic extinguishment of such fires in the incipient
stage is, therefore, of primary importance.
-158-
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80. Rubbish Handling
803. Rubbish Receptacles
8035. Wastebaskets and small containers for rubbish should be
of noncombustible material. Large quantities of rubbish shall be handled in
metal ash cans, drums, or similar containers.
8037. Approved waste cans and receptacles shall be provided
for oily waste and other materials requiring special handling.
8038. Barrels and similar containers for rubbish and ashes
shall be substantial, approved metal construction, maintained in good condi-
tion and provided with handles and a cover. They shall be provided with a
flange at the bottom to provide at least a 2-in. air space between the bottom
and the floor. Containers and barrels shall be kept covered.
804. Bailing and Compacting
8041. The location of rooms for the collection and baling or
compacting of refuse should be given careful consideration to avoid creating
an exposure hazard to the rest of the building. Quick-burning fires of the
flash variety are to be expected where waste paper is handled in large quanti-
ties.
8042. If a rubbish room or bin is not provided, refuse shall
be stored in covered metal cans only.
8043. Rooms used for baling or compacting shall be cut off
from the rest of the building by ceilings, floors, and walls, the minimum
fire resistance of which is 2 hours, with door openings protected by fire
doors suitable for Class B openings.
8044. Automatic sprinklers, properly installed, provide a re-
liable and effective means for fire extinguishment and shall be installed in
baling and compacting rooms. A short length of hand hose connected to a suit-
able water supply should also be provided. Fires of the nature likely to
occur in baling and compacting rooms are generally difficult to control by
ordinary means due to the large amount of smoke evolved and consequent diffi-
culty of access by the fire department. Automatic extinguishment of such fires
in the incipient stage is, therefore, of primary importance.
-159-
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The foregoing discusses national codes and regulations and only those
pertaining to fire safety.
In addition, there are literally hundreds of additional regulations per-
taining to waste handling in hospitals, promulgated in municipalities, counties,
and states, by various governmental boards and agencies covering the regulation
of health facilities and the control of the environment. Health departments
have published regulations affecting both the in-house handling practices,
as well as off-site reaoval; environmental control bodies have concentrated on
off-site handling practices. All hospitals should be aware of all such regu-
lations to ensure they are in compliance when they install methods for waste
management.
-160-
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f\- ENVIRONMENTAL TESTING
The hazardous nature of a large proportion of hospital solid waste and
possible environmental effects has been established through various studies
that have been performed over the past 15 years. The effect on the hospital
environment of the use of a pneumatic system, transporting encapsulated solid
waste, has not been completely documented in past studies.
Environmental effects from such a system may be classified under three
general headings. First the systems involve machinery; in particular, fans
moving moderately heavy loads at high speed within closed metal tubes. The
increased noise (if any) that this creates in the hospital environment must be
measured. Secondly, it has been established in other studies that solid waste
contains many odor-causing components. If the encapsulating method is destroy-
ed in the system, or if housekeeping practices are unsatisfactory, possibilities
exist that an odor condition may develop. Thirdly, the system consists of.
chutes opening onto nursing areas, closed tubes, and collector boxes joined to
fans that exit the air from the system. With possibilities of bag breakage
within the system, coupled with a lack of self-cleaning and sanitizing devices,
bacterial contamination of the hospital environment is a possibility. The
survey team conducted tests within each of the hospitals in these three areas;
noise level readings were taken; odor readings were registered; and bacterial
counts made of both the pneumatic system and the adjacent area. In addition,
notations were made of the presence or absence of dust and litter (including
ruptured waste bags) along with any physically unsafe or hazardous conditions,
including any problems in transporting and disposing of chemical and toxic wastes.
SOUND LEVEL READINGS
In an institutional setting such as a hospital there are many areas and
many times of day where "quiet" or a lack of sound is desired to assist in the
recovery of patients, or simply to avoid interference with staff activities,
such as conversations.
-161-
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Sound or "noise" is caused by a variation in atmospheric pressure. It
may be sudden and extremely loud, such as gunfire. It may be at a constant
s
level that a person "gets used to" and finally does not even notice. It may
be, in either case, of a level and frequency that can be dangerous to the point
of causing a loss of hearing, suddenly or gradually. Or it may be merely
annoying, such as a faucet dripping, or chalk squeaking against a blackboard,
and not have any permanent effect on the listener's hearing.
100
DISTANCE--FE
FIGURE 17. CURVES SHOWING HOU. NOISE INTERFERES WITH
SPOKEN OR SHOUTED CONVERSATION
Before we can evaluate the possible effects of sound on hearing, or dis-
comfort, we must know three things about it: (a) the sound pressure level;
(b) the frequencies present in the sound, from low pitch to high; and (c) the
duration of the sound at these frequencies and pressure levels.
-162-
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To measure sound pressure, an instrument known as a "sound level meter"
is used. This is an electronic ear that converts sound into electrical signals
and displays them on a dial. The levels are expressed in decibels (dB), an
arbitrary measuring unit, in a scale from 0 to 140. The weakest sound that a
person with excellent hearing can detect in an extremely quiet location is
assigned the 0-dB value. At 140-dB the threshold of pain is reached in hear-
ing. In between are the levels found in institutions, homes, offices, and
factories, ranging from 50- to 60-dB as a typical office noise level, to a
power lawn mower at around 100-dB, or a riveting machine at 118-dB, which is
the discomfort level.
Coupled with sound pressure level is the frequency or pitch of the sound.
This is measured in "hertz" -units. The frequency has much to do with how loud
a sound appears to be to the ear. The higher the frequency, the more annoying
and the more physical effect on the human hearing. The human ear can tolerate
more low frequency sound than high.
Hence, the more sophisticated meters for measuring sound levels have
built-in weighing networks that permit responding to some frequencies more
than others, similar to the reaction of the human ear. Acoustical standards
have established three such networks and designated them "A," "B," and "C."
Very low frequencies are severely suppressed or discriminated against in the
"A" network (as the human ear would do); they are moderately discriminated
against in the "B" network; and they are accepted in the "CM network, which
gives a flat response across all frequencies.
if the sound level being measured is higher on the "C" network than on
the "A," the noise source is predominantly at the low frequencies (below 600
hertz), since the "A" network discriminated against the low frequencies and
give a lower dB reading. If the readings on the sound level meter are pro-
gressively higher, going from "A" to "B" to "C" networks, then the predominant
portion of the sound source is below 600 hertz in frequency. If, on the other
hand, the readings on all three networks are close together in dB, it indicates
that the sound energy is of a higher frequency (above 600 hertz).
-163-
-------
« -5
ui
5 .to
-.5
-20
-25
ui
oc
u
oc -40
-49
z
^
B AND C
20 SO 100 200 500 1000 ?POO
FREQUENCY IN HERTZ
spoo iopoo
FIGURE 18
PREOUENCV RESPONSE FOR A.B.AND C NETWORKS WEIGHTING CHARACTERISTICS
As stated, sound levels and frequencies present two problems in a hospital
complex: they may be annoying to patients, staff, and visitors; or they may be
dangerous to the level of damaging hearing. To prevent hearing damage, Federal
regulations under the Occupational Safety and Health Act (OSHA) of 1970 set per-
missible noise limits to protect the workers in any place of employment.
TABLE 11
PERMISSIBLE NOISE EXPOSURES
Duration, per
Day, Hours
8
6
4
3
2
1-1/2
1
1/2
1/4 or less
Sound Level in
dB(A), Slow Response
90
92
95
97
100
102
105
110
115
When sound levels and duration exceed those values given above, protection
against the effects of noise exposure must be provided and a continuing, effec-
tive hearing conservation program must be administered.
-164-
-------
To determine how much sound the pneumatic transport systems generate in
each of the three survey hospitals, sound level readings were taken inside and
outside each chute loading room; inside and outside the rooms containing col-
lector boxes and compactors; in the mechanical rooms that contain the motors
and exhaust fans; and at the exit side of the fan exhaust outside each building.
The. instrument used in this survey was a Type 2 Sound Level Meter meeting
Standard SI.4-1971 of the American National Standards Institute (ANSI). It
was calibrated twice each day during the survey. All readings were taken with
the equipment operating and waste bags going down the chutes.
The following tables present the reduced data obtained during the survey.
The first table for each hospital contains data taken within each chute room,
3 to 5 feet from the hopper loading door. It shows the maximum, minimum, and
average dB readings on all three networks for all loading stations on each
floor of the hospital.
The second table for each hospital contains maximum, minimum, and average
dB values of all three networks for each vertical chute within the hospital,
covering all floors through which the chute passes. Here it can be seen that
the average dB values, for all three networks, for all three hospitals, are
consistently close together and vary within any one hospital by only a few
dB's. There is a difference between hospitals, due to the different types of
systems installed.
The third and fourth tables for each hospital present data in the same
format as the first and second tables, but the readings were taken outside the
chute rooms, 3 to 5 feet from the outside door of the chute room.
The average readings outside the rooms were consistently lower than those
inside, for all three hospitals. The difference between inside and outside
average readings was more pronounced at St. Mary's and Veterans Administration
Hospitals than at Martin Luther King Hospital. This is attributed to the fact
that the gravity to vacuum system at Martin Luther King, with its absence of
vacuum noise at the loading hoppers, proved to be a very quiet system even
inside the chute rooms.
The method of taking sound readings also indicated that, regardless of
the type of pneumatic system, there was virtually no correlation between the
-165-
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vertical distance a bag drops and the sound level produced.
An examination of the first four tables for all hospitals will show peaks
and valleys among the data. As an example, one can see that the highest A-
network noise level inside a chute room at Martin Luther King occurred at the
fourth floor in Wing A and was 72 dB(A). This may be considered against an
average of 66 dB(A) for the entire fourth floor, or against 63 dB(A) for the
entire Wing A. Peaks of this nature occurred in all the hospitals surveyed.
Several elements contribute to these peaks. Architectural considerations
creating acoustical differences can and do occur. Different methods of hang-
ing the chutes also contribute. An important contributing factor to sound
level variations was found to be the actual content of the waste bag going
down the chute. Those that contained a large amount of hard plastic and cans
not only created a higher sound level but in most cases could be heard going
all the way down the chute.
It will be noted that the dB readings consistently increase as the meter
recorded sound from the A to the B to the C networks. This is a clear indica-
tion that the sound caused by bags of waste traveling through the system, both
vertically and horizontally, is predominantly in the low frequency range
(below 600 hertz) and is relatively tolerable to the human ear. The sound
from each bag is relatively sudden, of quite short duration, and with little
continuing reverberation or echo effect. Even though bags may be transported
constantly over an 8-hour day, the maximum readings are well below OSHA per-
missible noise exposure levels.
On the other hand, as seen from the A-network, the maximums in the corri-
dor are from 62 dB(A) to 71 dB(A), which is approaching the "annoyance" level
for quiet conversation or a resting patient. Therefore, physical locations of
chutes and tubes should always consider this.
-166-
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TABLE 12
IL:-!**^!!.^ HOSPITAL
Load Station Sound Levol Analysis
Inside Ch-jte Rooms. 3'-5' t'roi loading KODPLT Door
All Stations
on Floor
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Averages
All Stations, Ea
Verc1c.il Chute
West Wing
Center Wing
East Wing
Averages
All Stations
on Floor
L.
2 .
3.
4.
5.
6.
7.
6.
9.
10.
/vet aw;
Al 1 Stations , f ;
\Vrtlr..l fh..t<
wos» wing
Centt. Wlnj',
Aver j r-t s
A-Netvork, dB(A)
Max.
78
77
73
72
70
74
72
70
71
70
73
Mir..
67
74
66
70
61
69
69
70
71
70
69
ch A- Network,
Max.
78
74
77
76
Min.
61
65
67
64
Load St?
Outside
Chute
A-Netvork
Max.
62
66
61
65
65
61
69
61
60
60
63
nch A-N
c- K:*x
69
65
65
6fc
. V.in
59
59
5S
63
59
59
65
61
60
60
60
Avg.
71
75
70
71
65
72
71
70
71
70
70
dB(A)
Avg .
71
69
71
70
B-Nrtwork,
Max.
79
ei
73
75
70
74
73
75
71
73
74
Mln.
70
74
6E
70
65
71
72
75
71
73
71
B-Network,
Max .
79
75
SI
78
ticns Sourd Leve
Poons^
, do (A)
Avg.
60
63
60
64
61
60
67
61
60
60
6,"
Min.
67
65
70
67
dB(E)
Avg.
74
77
71
73
67
73
73
75
71
73
72
dB(B)
Avf .
73
71
73
72
C-Network, dB(C)
Max.
82
85
75
76
75
76
76
75
72
74
76
Min.
77
77
72
73
68
74
74
75
72
74
73
C-Netwurk,
Max.
82
77
85
81
Min.
68
72
73
71
Avg.
80
80
73
75
72
75
75
75
72
74
75
dB(C)
_AvgL._
74
74
77
75
1 Analysis
3'-5' from Outside Tcor
B-Network,
Ma*.
67
68
62
65
62
65
66
61
59
61
r'-4
Min.
65
64
60
65
59
62
66
61
59
f 1
62
dB(B)
Avg.
66
66
61
65
61
64
66
61
59
61
63
• 'U.-1..-1- , i'i.'(A) B-N'etwork, difb)
•-.. ^!'.
59
r-9
1,1
Sy
.. \v_fc_.
62
62
61
6:
M.ix.
67
63
67
.. PL
Min .
59
61
S^1
60
__._A".E.-_ . ._
63
64
63
63
C-Network,
Hax.
77
74
64
68
67
66
70
64
70
64
68
Win.
72
68
63
66
63
66
70
64
70
64
67
C-Network,
-*i*7;--
73
~,2
77
74_
Min.
64
64
63
f'4_
dB(C)
Avg.
74
70
64
67
65
66
70
64
70
64
67
dB(C)
__Avg.
68
65
69
67_
-167-
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TABLE 13
MARTIN LU1HER K'.
SG HO
SPtTAI.
Load Station EOUM Level Analysis
Inside Chute Roocs, 3'-5" frc-n Loading Hopper Door
All Stations
on Floor
Basement
1.
2.
3-
4.
5.
Averages
A-Network, dB(AI
Max. Min. Avg.
63
70
62
66
72
64
66
63
63
58
58
62
64
61
All Stations, Each A-Xetwork
Vertical Chute Max. Kin
Segment 1
Wing A
Wing B
Wing C
Awe rages
70
72
68
64
69
62
59
58
58
59
63
65
60
62
66
64
63
• Avg.
65
63
62
61
63
Load Station Sound
Outside Chutrr R..OC:-, 3'-
All Stations
on Floor
Basement
1.
2.
3.
4.
5.
Averages
All Stations,
Vertical Cii.
Segment I
Wing A
Wing B
Win*; C
Averages
A-Netvoik
Max. Min
62
62
63
64
60
59
62
Kiicl. A-N
Jte Max
59
62
62
63
62
6:
58
57
58
58
53
59
. Yin
S3
57
58
59
56
, UBiA)
Avg.
62
61
60
bi
59
59
eO
1 *• L ' *• '
• -vg .
58
60
5V
67
tu
B-Network,
Max. Min.
63
72
64
69
68
67
67
63
63
63
59
64
66
63
B-Netvork,
Max. Min.
72
64
67
65
67
64
59
63
£3
62
dB(B)
Avg.
63
66
64
64
66
67
65
dB(B)
Av,,.
68
63
65
64
65
C-N'etwork,
Max. Kin.'
67
72
69
77
65
70
70
67
67
65
60
63
69
65
C-Network,
Max. Min.
77
67
71
69
71
64
60
65
63
63
dB(C)
Avg.
67
69
67
68
64
70
67
dB(C)
Avg,
70
65
68'
66
67
Lewi Analysis
5" from Outside I'cur
B-Ke
fc2
62
64
66
64
fcC
63
twoik,
Min.
62
56
58
60
57
59
59
Avg.
62
60
61
64
Cl
CO
61
P-Kotwr.rl , dl;OO
62
64
66
66
t-4
50
58
59
60
58
59
6J
62
64
6i
C-Setwork,
Max. Min.
64
64
67
69
68
65
66
64
57
64
61
64
64
62
C-Niilwork ,
Max. Kin.
67
68
69
66
67
57
61
64
64
62
dS(C)
Avg.
64
62
66
66
65
65
65
dr.(c)
Avg.
64
f4
65
66
65
-168-
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TABLE 14
VETERANS
Inside
All Stations
on Floor
1.
2.
3.
4.
5.
6.
Averages
All Stations, Each
Veitical Chute
North Wing
West Wing
South Wing
East Wing
Averages
APftlNISTFATlON HOSPITAL
Load Station ?cunc
Chute Rt.cms, 3' -5' i
A-Network,
Max. Min.
76
89
85
81
79
78
82
73
80
78
75
70
70
74
A-Network,
Max. Min.
89
88
80
85
86
7t>
n
70
70
72
dB(A)
Avg.
75
85
83
77
73
74
78
do (A)
Avg.
81
79
75
76
78
le .'*.' J Analysis
t OKI Loading Hopper
B- Network.,
Max. Min.
76
81
87
87
82
80
83
B-Ket
Max.
87
81
80
87
84
75
72
75
76
75
77
75
work,
Min.
72
75
75
78
76
dB(B)
Avg.
77
78
80
80
78
79
79
dB(R)
Avg.
79
77
77
81
79
Load Static-.-, Sound Levi 1 Analysis
Outside Chute Koccs, 3'-5' free, Outside Do
All Stations
on Floor
1.
2.
3.
It.
5.
6.
Averages
All Stations, Each
Vortical Chutf
North Wing
West Wing
<;ou(h Wing
tat, i *tnf.
AvcrupeL
A-Netwerk ,
Max. Min.
n
65
72
68
69
68
70
A-N
Max
68
77
68
69
71
55
56
60
62
62
61
59
ot worV
''in
50
C2
60
5r>
58
dB(A)
Avg.
66
61
66
65
65
65
65
, dB'O
. AV4-
63
60
fc'.
S,
65
B-Network ,
Max. Min.
73
6fJ
76
77
75
70
74
B-Ke
Max.
76
7?
7^
11
75
60
62
63
69
63
69
64
t vork ,
run.
63
1°.
6J
6'J
64
dB(B)
Avg.
69
66
72
72
f.9
70
70
dB(E)
AVd.
68
72
68
70
70
Door
C-Netvork, dB(C)
Hax. Min. Avg.
84
90
90
85
83
87
87
82
87
86
79
76
79
82
C-N'etwork,
Max. Min.
90
90
88
90
90
or
79
82
76
76
78
C-Network.,
Max . Min .
79
78
79
74
76
76
77
69
71
69
72
71
71
71
C-Network,
K;ix. Min.
79
79
74
78
76
73
72
69
69
71
81
88
89
82
78
84
84
dB(C)
Avg.
84
85
83
85
84
dB(C)
Avg.
74
75
74
73
74
73
74
dB(C)
Avg.
75
75
71
74
74
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The fifth table for each hospital presents maximum, minimum, and average
data on each network, for the fan (or equipment rooms), the collector, and
the compactor areas. Readings were taken in several locations within each room,
5 to 10 feet from the operating equipment. The sixth table presents data for
the same pieces of equipment, with readings taken 10 feet from outside the
area with the equipment running. As might be expected, all these areas are
noisy ones. The fans used in these systems are high-horsepower fans which
create noise when running. Collectors have metallic dampers which bang loudly
when they open and close. The rams on all the compactors were noisy. The
dB(A) readings in the fan rooms in all hospitals were at least 95 dB(A) average,
and at one hospital it was as high as 104 dB(A). All of these are at a level
where noise protection for workers is required by OSHA if workers must remain
in these areas for extended periods. Even short, yet constant, periods of ex-
posure might be harmful to an individual worker over a period of months or
years. A worker should not remain in the 95 dB(A) fan room in excess of four
hours in any day or the 104 dB(A) fan room in excess of one hour.
The fan rooms of two of these hospitals were on or near the roof, where
they are not likely to annoy anyone. Happily, this includes the noisiest one
at 104 dB(A)—which, incidentally, does not have a sound attenuator. The fan
room for the third hospital (Martin Luther King) is at ground level, in a small
service building. This service building is located approximately 40 feet from
a brick wall at the edge of the hospital property and beyond which is a resi-
dential area of small homes. A series of readings was taken at this wall, 40
feet from the fan attenuator. The average readings at this point were 76 dB(A),
77 dB(B), and 80 dB(C). These readings are sufficiently high to be annoying
to some people.
In general, the analysis shows that Martin Luther King Hospital, with its
gravity to vacuum system, has the quietest system. Veterans Administration
Hospital, with a full-vacuum single-tube system with diverter valves, was the
noisiest, while St. Mary's Hospital, with a small-tube full-vacuum and using
nylon mesh bags in the chutes, was in the middle. Because of the consistent
increase in dB readings from A-network to B-network to C-network in all hospi-
tals, it is concluded that most, but not all, of the sound is of a low fre-
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quency variety which is not so annoying to most individuals. The general dB
levels throughout patient areas of all three hospitals are considered to be
sufficiently low as to not cause annoyance, with the possible exception of
Veterans Administration Hospital, which may cause problems in some areas. It
was observed at Martin Luther King Hospital that both the automatic cart
system and the tote box system were a higher noise level source than the pneu-
matic tube system.
TABLE 15
MARTIN LUTHER KING HOSPITAL
SOUND LEVEL ANALYSIS OF FANS, COLLECTORS, AND COMPACTORS
INSIDE ROOMS, 5' - 10' FROM EQUIPMENT
Equipment
Name
Fan
Collector
Compactor
A-Network, dB(A) B-Network, dB(B) C-Network, dB(C)
Max. Min. Avg. Max. Min. Avg. Max. Min. Avg.
95 94 95 96 95 96 100 98
103 94 98 98 93 96 101 94
103 94 98 98 93 96 101 94
99
97
97
TABLE 16
MARTIN LUTHER KING HOSPITAL
SOUND LEVEL ANALYSIS OF FANS, COLLECTORS, AND COMPACTORS
OUTSIDE ROOMS, 10' AWAY
Equipment
Name
Fan
Collector
Compactor
Sound attenuator,
A-Network,
Max . Min .
86
72
72
89
70
68
68
73
dB(A)
Avg.
77
70
70
82
B-Network, dB(B)
Max. Min. Avg.
87
75
75
91
72
71
71
74
79
73
73
83
C-Network,
Max. Min.
89
84
84
95
76
75
75
79
dB(C)
Avg.
82
78
78
87
ground level
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TABLE 17
ST. MARY'S HOSPITAL
SOUND LEVEL ANALYSIS OF FANS, COLLECTORS, AND COMPACTORS
INSIDE ROOMS, 5'-10' FROM EQUIPMENT
Equipment
Name
Fan
Collector
Compactor
A-Network,
Max. Min.
106
70
75
101
69
70
dB(A)
Avg,
104
70
72
B-Network,
Max. Min.
108
76
77
106
73
72
dB(B)
Avg.
107
74
75
C-Network,
Max. Min.
110
81
85
107
80
78
dB(C)
Avg.
108
80
82
TAKLE 16
ST. MARY'S HOSPITAL
SOUND LEVEL ANALYSIS OF FADS, COLLECTORS, AND COMPACTORS
OUTSIDE ROOMS, 10' AWAY
Equipment
Name
A-Network, 42
-------
TABLE 19
VKTh'RAN-; ADMINISTRATION HOSPITAL
SOUND LEVEL ANALYSIS OF FANS, COLLECTORS, AND COMPACTORS
INSIDE ROOMS, 5'-10' FROM EQUIPMENT
Equipment
Name
Fan
Collector
Compactor
A-Network, <1B(A) B-Network, dB(B) C-Network, dB(C)
Max. Min. Avg. Max. Min. Avg. Max. Min. Avg.
96 94 95 96 96 96 98 97 98
92 80 86 91 87 88 92 89 91
92 80 86 91 87 88 92 89 91
TABLE 20
VETERANS ADMINISTRATION HOSPITAL
SOUND LEVEL ANALYSIS OF FANS, COLLECTORS, AND COMPACTORS
OUTSIDE ROOMS, 10' AWAY
Equipment
Name
Fan
Collector
Compactor
Sound attenuator,
on roof
A-Network,
Max.
95
81
81
73
Min.
94
77
77
73
dB(A)
Avg.
95*
78
78
73
B-Network,
Max.
101
81
81
84
Min.
99
78
78
84
dB(B)
Avg.
101*
79
79
85
C-Network,
Max .
103
84
84
91
Min.
101
79
79
91
dB(C)
Avg.
102*
81
81
91
* The area 10' outside the door to the fan room contains three air compressors,
which contributed to the overall sound pressure level and accounts for these
average dB readings outside the fan roorr being generally higher than the cor-
responding ones inside the fan room.
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ODOR DETECTION
Tbe solid waste generated in hospitals contains many items capable of pro-
ving a variety of odors. Although all three hospitals surveyed place their
solid waste into plastic bags prior to depositing them in the pneumatic tube
system, there is a very real possibility that some of these encapsulated items
mi^ht become free at some points in the system and create a noxious odor which
-culd be detectable by, and annoying to, patients or staff in the vicinity.
•Ml three of the hospitals in the survey have experienced occasional problems
in the past with the plastic solid waste bags breaking, ripping, or coming open
either while being loaded into the chutes or at some point during their transit
•f the system. As examples, a bag can break when it hits the slide valve in a
gravity to vacuum system; it can break when it hits a diverter valve in a single
; ube system; it can break when it enters the collector box at a speed of as much
~ 80 feet per second. Further, the bag can contain glass, other breakable ob-
jects, and liquids. The management practices in many hospitals do not permit
glass and liquids to be placed into the tube system. Nevertheless, people con-
ti-.ue to do so occasionally. At one of the hospitals in this study, the survey
;:;ia!» observed the face of a slide valve which was covered with dried blood,
f-eces, liquids, and other wastes. This valve room ixad a moderate but definite
odor,
For these reasons, the survey team, using techniques developed in the past,
performed odor detection tests in all three hospitals. These tests were carried
out at each chute loading station, inside and outside of the collector boxes,
adjacent to the compactors, in trie fan rooms, and in the effluent air downstream
-------
1 = No odor present
- = Threshold, or just recognizable odor present
3 = Slight odor present
4 = Moderate odor present
5 = Strong odor present
In addition, while determining the odor readings, the survey team made note
of the presence or absence of dust, litter, ruptured waste bags, and any physi-
cal hazards directly attributable to the pneumatic systems.
At Veterans Administration Hospital, San Diego, odor detection readings
were taken at a total of 28 locations. Of these, no odor was present at 13
locations, or 46 percent of the total readings. There were 9 locations, or 32
percent of the tctal, where there was just a recognizable odor present (Code 2).
Four locations, or 14 percent of the total, had a slight odor present (Code 3).
Only one loading station (6W) had a rtadiug as high as Code 4 (moderate odor
present). Strong odor (Code 5) was detected at the collector box leading into
the compactor. Overall, 93 percent of all locations tested had only a slight
odor, or less.
At Martin Luther King Hospital, Los Angeles, odor detection readings were
taken at a total of 36 locations. Of these, no odor was present at 13 loca-
tions, or 36 percent of the total readings. There were 17 locations, or 47
percent of the total, where there was a just recognizable odor present (Code 2).
One location, or 3 percent of the total, had a slight odor present (Code 3).
This reading was taken directly behind the compactor. There were four locations,
or 11 percent of the total readings, which had a moderate odor present (Code 4).
Only one of these Code 4 locations was inside the hospital proper and occurred
inside the chute loading room on the fourth floor in Wing A. This location
also had the highest sound level reading of all chute loading rooms inside
the hospital, but this appeared to be a coincidence since no correlation be-
tween sound level and odor level could be determined at this loading room.
The remaining locations with Code 4 odor readings were in the effluent air
downstream of the sound attenuator and in one slide valve room (Room 50-57).
This is the slide valve mentioned in the introduction to this section which
had wastes on its face caused by bag breakage. The Code 4 readings obtained
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in the effluent air were taken at locations directly behind and under the sound
attenuator and at a spot approximately 40 feet west of the attenuator. This
latter location is close to a group of private homes, the residents of which
could be annoyed by this Code 4 odor. This situation probably could be allevia-
ted by more frequent disinfectant spraying of the compactor and dust filter.
Strong odor (Code 5) was detected at the collector leading into the com-
pactor. Overall, 86 percent of all locations tested had only a slight odor,
or less.
At St. Mary's Hospital, Duluth, odor detection readings were taken at a
total of 30 locations. Of these, no odor was present at 14 locations, or 47
percent of the total readings. There were 11 locations, or 37 percent of the
total, where there was a just recognizable odcr present (Code 2). Three loca-
tions, or 10 percent of the total readings, had a slight odor present (Code 3) .
these occurred inside chute loading rooms on the third floor of the West wing,
the fifth floor of the East wing, and the ninth floor of the West wing.
Moderate odor (Code 4) was detected at the collector box, and strong odor
(Code 5) was detected at the compactor. Overall, 93 percent of all locations
tested had only a slight odor, or less.
Not all of the odors detected in the three hospitals were necessarily
noxious, unpleasant, or annoying. A few were caused by bars of soap being
stored in the chute room, and these were subjectively judged by the survey
team to be actually pleasant odors. Others were caused by such things as
ether, various antiseptics, and soiled linens, as well as the components of
solid waste.
Overall, because of the relatively low odor code readings obtained, it
is our opinion that none of the three hospitals surveyed have a significant
odor problem within the hospital itself that can be attributed to the pneu-
matic solid waste transport system. Most of the moderate and strong, un-
pleasant type odors were associated with the "end of the line" equipment,
away from areas occupied by patients and staff. The most significant of these
was the situation described above at Martin Luther King, where there is a po-
tential of annoying occupants of nearby homes.
Table 21 gives a summary of the occurrences of various odor levels in
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the three hospitals:
TABLE 21
SUMMARY OF OCCURRENCES OF VARIOUS ODOR LEVELS
Odor
Code
1.
2.
3.
4.
5.
V.A.
HOSPITAL
No. of
Occurrences
13
9
4
1
]_**
% of
Total
46%
32%
14%
4%
4%
MARTIN LUTHER
KING HOSPITAL
No. of % of
Occurrences Total
13
17
1
4
1**
36%
47%
3%
11%
3%
ST. MARY'S
HOSPITAL
No. of
Occurrences
14
11
3
I*
1**
% of
Total
47%
37%
10%
3%
3%
Totals
28
100%
36
100%
30
100%
* Trash collector box
** Compactor
THE PROBLEMS CREATED bY AEROSOLS
In pneumatic tube systems, whether it is a gravity to vacuum system or a
full vacuum system, there is a constant negative pressure in the system when.
it is operating. This assures that air is always pulled from the load sta-
tions toward the waste collector. Therefore, with these type systems, the
probleir. found in straight gravity chutes, in which air in the chute contami-
nates the load stations, does not exist if the system is functioning properly.
As seen, since basically the tubes do not leak, the major aerosol prob-
lems with these pneumatic systems appear to exist at the end of the line, prin-
cipally in two areas. First, leakage generally occurs between the waste
collector and reduction equipment, whether this equipment is an attrition mill,
a compactor, or an incinerator. Second, problems can. occur in the fan-mechani-
cal room, where effluent air from the system, is exhausted into the ambient
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atmosphere adjacent to the hospital. There not only are leakages around the
fan itself, the exit ducts, and sound attenuators, but there are often filters,
with potentially high bacteriological counts, and which must be manually
changed and disposed of.
HOUSEKEEPING PRACTICES
The methods used in each hospital to control the environmental conditions,
to keep the areas clean, and to manage failures or weaknesses in the pneumatic
systems that cause bag breakage and the spread of waste and possible contami-
nation, were observed by the survey team during each site visit. As has been
stated repeatedly in this report, the most automated system for transporting
and collecting waste, is subject to various weaknesses, caused by human error
or by mechanical, electrical, and design weaknesses affecting the equipment
and the safe encapsulation of every bag of waste. Further, the equipment
itself may provide unsafe working conditions by the manner in which it operates
VETERANS ADMINISTRATION HOSPITAL
One broken waste bag was observed at Veterans Administration Hospital.
This bag was lying on the floor of the laundry room, directly under the linen
collector. The bag was completely ruptured and its contents spread over an
area of approximately 25 square feet. Laundry workers cleaned up the mess
(wearing gloves to do so) while the team was still present. This hospital,
witn its single-tube system, frequently has cross-over problems, with laundry
bags going to the compactor and waste bags going to the laundry. While the
survey team was in the laundry, the doors of the linen collector opened six
times but instead of laundry bags coming down, a moderate amount of loose
trash, paper, and dust floated out. This was also swept up by the laundry
workers.
No unsafe or hazardous conditions were seen. There was no visible dust
inside the hospital other than that coming from the linen collector. The
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effluent air filter on the roof, howtsvcr, was approximately 30 percent covered
by a heavy layer of thick dust. Ibis restricts air flow and obviously affects
the efficiency of the pneumatic system. This was immediately brought to the
attention of hospital management by the survey team so that the filter could be
either cleaned or changed.
MARTIN LUTHER KING HOSPITAL
No broken waste bags were actually seen by the environmental testing team.
However, as mentioned previously, bags containing unauthorized waste had
obviously broken in the past on the. face of one slide valve.
No unsafe or hazardous conditions were found except in the slide valve
rooms. There arc two such valves in each valve room, one for waste and one
for soiled laundry. The valves consist of heavy, 20 in. diameter metal plates
which are automatically controlled. When they are activated they swing rapid-
ly, and without warning, out of the chutes and into the small room. Even though
there are signs posted in the valve rooms warning of this danger, a person who
is unfamiliar with the operation of these large automatic valves, or even one
who is familiar but may become careless because of this familiarity, could be
struck and seriously injured by the valve plates when they swing out. This
situation could be alleviated by placing a wire mesh screen around the areas
covered by the valve plate when it swings out. Such a screen should have a
removable section so that maintenance personnel can periodically clean the
valve face.
ST. MARY'S HOSPITAL
No broken bags, litter, dust, or unsafe conditions attributable to the
pneumatic, solid waste transport system were observed anywhere in this hospital.
St. Mary's had established the practice of placing their plastic solid waste
,s, several at a time, inside large, heavy nylon mesh bags prior to depositing
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them in the chutes. As can be seen from the chapter on Economics, these
nylon mesh bags are a significant item of expense, amounting to 25 percent of
the average total direct costs per year to operate the pneumatic solid waste
transport system. Nevertheless, the practice appears to have solved the prob-
lem of bag breakage and ripping, and also appears to be a causative factor in
lower sound levels in the chutes.
BACTERIOLOGICAL TESTING
Many researchers have considered the fact that up to 15 percent of raw
hospital waste is potentially infectious, and that from 2 to 8 percent of the
total, due to the nature of the waste products and their generation points,
has proven pathogenic organisms present in high concentrations, particularly
if an organic substrate is present. Tests of waste samples have shown that
Bacillis organisms are most prevalent, particularly streptococci and staphylo-
cocci, with Staphylococcus aureus the predominant pathogen. Significant
counts have been made of coliforms, Candida albiens and Pseudomonas. In addi-
tion, waste mixtures have high concentrations of paper and cotton textiles that
have proven ideal for the transmission of viruses. Other researchers have
shown that Escherichia coli can contaminate hospital environments. Of the many
fungi to be found in the environment, the systemic, or deep seated, mycoses
create the most problems for humans. Many are airborne, entering through the
respiratory tract, are found in hospital wastes, and can create allergens in
hospital patients and staff.
The recorded biologically hazardous nature of hospital wastes indicate
that the housekeeping practices used in collecting, transporting, centralizing,
reducing, and moving these materials off-site must be excellent at all times.
If there are breaks in management technique, the environment of patient and
ancillary areas will be contaminated, with a good possibility of affecting the
patients and staff.
In preparing the methodology for bacteriological testing, the survey team
worked in close association with administrative, housekeeping, materials
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management, and maintenance staffs of the three survey hospitals. The labora-
tories were consulted as to the environmental testing performed in the past.
All three hospitals have excellent laboratory facilities and personnel and all
three institutions are knowledgeable on both the importance and the methods of
testing for bacteriological levels in the hospital environment to prevent the
spread of infections, bacteria, and viruses encountered in treating patients.
In embarking on bacteriological testing of a solid wasge management
program, and the systems and equipment that are used in the program, it is
important to understand how hospitals normally handle solid waste and exactly
what are the main purposes of such testing.
As has been pointed out repeatedly in this Report, well-managed hospitals
follow certain definite procedures in handling waste:
1. Whether "infectious" or not, the waste products are. deposited
into some sort of container that is lined with some sort of
removable bag.
2. This deposit is made at the point of waste generation and nor-
mally as rapidly as the waste is generated.
3. The deposit is normally made with a "gentle" motion—a gravity
drop into the open bag—by nurses, aides, technicians, doctors,
etc., and without stuffing, shoving, and forcing the waste into
the bag. This prevents the waste from being "stirred up" and
hence inhibits the spread of aerosols in the area of the waste
container.
4. When the bag holding the waste is reasonably full, it is re-
moved from the waste container and normally is tied or sealed
immediately to prevent spillage of the waste and/or the further
spread of aerosols.
5. The encapsulated waste is then removed from the generation area,
to the central collection point in the building, and eventually,
in either a reduced or a whole form, off-site.
In short, the bagged waste collection systems used by most hospitals
appear to have been well thought out and capable of preventing contamination
of the hospital environment by the waste; assuming the personnel follow each
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procedure properly and bags of a proper construction are always used. Ob-
viously the bags must be completely sealed and must be water- and air-proof
to prevent any leaching of the encapsulated waste onto the surfaces with
which the bags come in contact during the process.
All three of the survey hospitals were extremely conscious of the potential
environmental effects to the institution from solid waste. All used the pro-
cedures of encapsulating it in containers (waste baskets, trash bins, etc.)
lined with plastic bags at the immediate point of generation, of not over-
loading such containers and bags, and of carefully tying or sealing the bags
before removing them from the containers to commence transporting them. All
impressed upon the nurse aide, housekeeping, and materials management personnel
the importance of these procedures and the potential hazards of a torn, ripped,
or punctured bag during the collection and transport process; including the
fact that bags could contain disposable needles and sharps that could puncture
the sides or bottoms and cut or puncture the handler. In all observations made
by the survey team, handling personnel always picked up the bags by the tied
top and maneuvered them in this position. Literally hundreds of such bags of
waste were followed by the survey team during the initial collection process
in which they were picked up from a waste container. At that stage, various
transport methods were used. Most bags were deposited in a cart and then
either moved to a chute room and transported by the pneumatic tube method,
or the cartload was moved from the floor by hand. Alternatively the bag was
hand carried from the initial deposit container to the chute room and sent
through the pneumatic system, or it was carried either directly or via a
soiled utility room to a nearby hand cart for movement off the floor.
Environmental testing in connection with such a system has one main
purpose: to determine whether any breaks are occurring in the system; as the
result of human error; or of weaknesses in the bags, and the bagging and
sealing methods; or from the waste content itself (such as sharp objects
puncturing the bags and allowing waste to escape) ; or from the equipment used
in transporting and reducing the waste.
Carts are used to transport waste tc chute rooms, and in some hospitals
from the collector boxes to the compactor, incinerator, or other reduction
-1S2-
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and off-site hauling equipment. Carts are also used to transport certain
wastes from the floors that do not go through the pneumatic system. Hence
the surfaces of the carts should be tested to determine their bacterial levels.
In the case of a pneumatic tube transport system, the configuration of the
equipment indicates where breaks in the technique could occur. There are six
main components that should be tested. First, the chute rooms are recipients
of waste bags, and it should be determined whether the bacterial levels of the
floors and walls of these rooms differ from the nearby rooms and corridors.
Secondly, the chute loading stations have the waste bags dropped into them;
the doors, sills, and loading hoppers should be tested. The vertical chutes
and pneumatic tubes that carry the bagged waste and the collector boxes at the
end of the line will probably have the highest counts in view of the possibili-
ties of bag breakage in transit. The effluent air from the collector boxes
goes to the fan room where, if there are filters, bacteria can be trapped, or
can escape to the outside atmosphere, through the sound attenuator, possibly
allowing some contamination to escape into the fan room itself, or remain
within the equipment.
As the purpose of the present study was to determine the effect of the
pneumatic tube system on the improvement of environmental conditions,
bacteriological testing was limited to this system.
The survey team believed that the bacterial levels of the waste itself
have been sufficiently documented by other researchers. It is apparent that
such levels will, be found in the waste from any hospital that is tested and
will also be found in the hospital compactors as the result of rupturing the
waste bags during compaction.
While no torn bags or loose waste were observed, the chute rooms and
chute loading station, as well as the hand carts, were tested in all three
hospitals for bacterial contamination; to determine whether the levels in and
around this equipment exceeded the levels of the adjacent areas with their
normal "people and material traffic." For a point of comparison, all the
hospitals involved make routine checks on the floors and walls of the nursing
units and ancillary departments.
As transport through the pneumatic tube system was the next step in the
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operation for from 35 percent to 85 percent of the volume of the waste in each
hospital, and as visual inspection bad revealed considerable bag breakage when
the bags dropped from the collector boxes at the end of the line, bacterial
levels were then recorded within the tube and within the collector box at each
hospital, as well as in the room holding the collector box (and the compactor).
As it was observed that the majority of bags were torn by the action of
the compactor, it was obvious that readings would be quite high within this
unit if bacteria were present in the waste. No readings were taken of the
interior surfaces of the compactor. Concentration was instead on the area out-
side the collector box and compactor to determine leakage and the efficiency
of the linkage between these two units.
To record the quality of the transport air, readings were taken of the
filters adjacent to the exhaust fans and within the sound attenuator or exhaust
duct after the fan, as well as within each of the fan rooms.
An interesting sidelight, in embarking on a program of bacteriological
testing of a pneumatic transport system is the firm conviction on the part of
many of the staff that, despite all they have observed in the way of careful
methods used in waste handling, the results from testing of the pneumatic
system will be colonies that are "T.N.T.C." (too numerous to count). This is
a general psychological reaction to solid waste. Experienced waste handlers
know they are dealing with a dangerous substance that has the capacity to
sicken or even kill its handlers. It is also a reaction to the tube system
and to a degree a lack of trust in its efficiency to safely transport encapsu-
lated bags of waste. Too many handlers have observed ruptured bags emerge
from the collector boxes. Maintenance crews are particularly convinced that
the elements of the pneumatic system present one of the most dangerous environ-
ments with which they must work. Instances were given the research team of
maintenance men developing skin rashes and other afflictions that they
claimed resulted from working on the pneumatic system. Unfortunately it was
impossible to verify any connection from the available records.
To properly evaluate the efficiency of a pneumatic tube waste management
system and in encapsulating solid waste, two types of readings were required.
1. Surface sampling—Swab and RODAC samples from the surface areas of
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the equipment, such as the hand carts for moving the waste; and the sills,
frames, doors, tubes, collector boxes, filters, and fan room equipment of the
pneumatic tube system.
2. Air sampling—To record the spread of aerosols in the chute loading
rooms, the collector-compactor rooms, and the fan equipment rooms.
As the greatest activity occurred in each hospital between 8:00 a.m. and
3:00 p.m., samples were collected during this peak period. They were taken
to the laboratory immediately after collection and the interval between sampling
and analysis did not exceed three to four hours.
Tryptose Glucose Yeast Agar (DIFCO) (Standard Methods Agar) was used as a
general plating medium for enumeration of bacterial populations and an indicator
of the general level of contamination.
Tellurite Glycine Agar (BBL) vas used for the quantitative detection of
coagulose-positive staphylococci. Selective inhibition is attained by means
of lithium chloride, tellurite and glycine; pathogenic coagulose-positive
cocci form black colonies on the surface within 24 to 48 hours which can be
counted easily.
MacConkey Agar (BBL) was used for the detection of Escnenchia coli; a
bile salt mixture is used for inhibitions of gram-positive organisms.
Cooke Rose Bengal Agar (DIFCO) was used as a selective nedium for the
isolation of fungi; selectivity is obtained by the dye, rose bengal, and two
antibiotics, penicillin and streptomycin.
For sampling, a one percent peptone phosphate buffer solution was used
as a dilution fluid to preserve microbes.
The principal specific bacteria for which samples were taken and cultures
made were Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa.
Bacillus subtllis, and Escherichia coli. In addition, effort was made to
determine the incidence of saprophytic bacteria in general and of fungi on the
equipment and the waste management areas.
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VETERANS ADMINISTRATION HOSPITAL
The personnel of the Veterans Administration- Hospital are acutely aware
of the potentially deleterious effects upon the hospital environment from the
hospital's solid wastes. All levels of hospital administration—from top
management, through department director level, through section head level, and
in the various laboratories—are actively int«res£ed in whether contamination
from solid waste is affecting patients, staff, or visitors. In particular,
they are interested in whether the pneumatic solid; waste transport system is
or is not contributing to surface or air contamination. Equally, they are
interested in whether this pneumatic system is superior to the system of hand
hauling solid waste with respect to the spread of bacteriological contamina-
tion.
Certain staff personnel of this hc.spit.al have been accustomed to routine-
ly performing periodic bacteriological testing to determine the level of con-
tamination at various points in the hospital. Recent manpower shortages in
the laboratories, however, have limited their capabilities to perform as many
of these tests as they would like. Despite laboratory manpower shortages,
the testing program was welcomed and given complete cooperation by the hospi-
tal administrative staff.
Microorganisms of particular interest were staphylococcus aureus,
pseudomonas aeruginosa, and klebsiella. Information on other bacteria which
might be present was also desired, even though these bacteria might be non-
pathogenic.
The survey team felt that a minimum of one half of the chute loading
stations should be tested in order to assure a reliable and representative
testing of the system. These should be those receiving the highest use fac-
tor. The following stations were selected:
IE 2E 5E
2S 4S 6S
3N 4N 5N
3W
Test samples were also taken inside one half of the trash carts and one
-186-
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half of the soiled linen carts; in the trash and linen collectors; inside
the incinerator room; inside the compactor room; in the compactor loading
hopper; in the fan room; and adjacent to the effluent air filter.
The results have not uncovered the presence of any pathogenic fomites
or air contamination inside the hospital attributable to the pneumatic tube
system. Non-pathogenic organisms likewise have not been uncovered to a
significant level.
-187-
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MARTIN LUTHER KING HOSPITAL
This hospital also has a staff extremely conscious of the potential en-
vironmental effects to the institution of solid waste. Here again, the sur-
vey team found from personal discussions that all echelons from top manage-
ment down to working staff were aware of the hazards that might arise from
the problems of solid waste disposal. Although this attitude was generally
held in all areas, it was particularly noticeable among the microbiology lab-
oratory staff.
The hospital routinely and regularly conducts their own microbiological
testing throughout the institution. This routine testing, done by the hospi-
tal staff, has normally been undertaken to determine the general level of
airborne cross-contamination that might be present inside the hospital. The
staff expressed great interest to the survey team, however, in conducting
tests to determine whether or not any contamination which might be present
could be attributed to the pneumatic solid waste transport system, and how
the hand hauled cart system might compare to this.
The microorganisms of particular interest were staphylococcus aureus,
pseudomonias aeruginosa, and klebsiella. Information on other bacteria pres-
ent was also sought.
The team felt that a minimum of one half the chute loading stations
should be included in the survey in order to assure a representative sample.
The following stations were selected:
Segment I, 1st floor Wing A, 1st floor Wing B, 3rd floor
Segment I, 2nd floor Wing A, 2nd floor Wing B, 4th floor
Segment I, 3rd floor Wing A, 3rd floor Wing C, 2nd floor
Segment I, 5th floor Wing C, 4th floor
Test samples were also to be taken inside one half of the trash carts and
one half the soiled linen carts; in the trash and linen collectors; inside the
incinerator room; inside the compactor room; in the compactor loading hopper;
in the fan and filter room; and adjacent to the effluent air filter.
The results have not uncovered the presence of any pathogens such as
staph aureas or pseudomonas anywhere in the hospital that might be attributable
-188-
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to the pneumatic tube system. Traces of Id. eb si el la., however, were found on
the laundry floor. There were fewer than five colonies, which is not con-
sidered a significant concentration. Klebsiella is an organism which in con-
centrations of approximately 40 colonies or above can cause throat and nose
infections, intestinal infections, sepsis in the bloodstream, and meningitis.
Several non-pathogens were identified. These included staphylocoecus
epidermis, diphtheroids. and bacillus subtilis. The face of all slide valves,
both trash and linen, and the floor near the compactor, had colonies of these
non-pathogens, which were too numerous to count. None of these were consid-
ered significant, being non-pathogens.
-189-
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ST. MARY'S HOSPITAL
This hospital is also acutely aware of the need for excellent housekeep-
ing and of the potentially dangerous effects upon the hospital environment
that could be attributed to the handling of solid waste. It was found, after
conducting several personal interviews, that top management was interested
not only in good housekeeping practices but also in whether contamination from
solid waste was affecting patients, staff, or visitors. There was interest
in whether either the pneumatic tube system or the hand hauled waste system
could contribute to surface or air contamination in the hospital. Extensive
laboratory testing in the past did not appear to have been carried out fre-
quently on a regular basis on these particular elements.
Here again, the microorganisms of particular interest were staphylococcus
aureus, pseudomonas aeruginosa, and klebsiella. Information on other bacteria
present was also desired, even though they might be non-pathogens.
The following chute loading stations were selected for testing:
3 East 4 Center 2 West
4 East 5 Center 4 West
5 East 6 Center 8 West
7 Center
Test samples were also taken inside one half the trash and linen carts;
in the trash and linen collectors; inside the incinerator room; in the com-
pactor loading hopper; and adjacent to the effluent air ducts.
No pathogenic bacteria were identified in any of the locations. Non-
pathogenic bacteria such as staphylococcus epidermis and diphtheroids and
bacillus subtilis were identified. The highest colony count of any of these
non-pathogens was 13, which occurred in trash chute 2 West.
-190-
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REPORT OF BACTERIOLOGICAL TESTING
ST. MARY'S HOSPITAL
AREA TAKEN FROM
Trash chute/ L-C
Trash chute/1-W
Trash chute/3-E
Trash chute/2-E
Trash chute/3-C
Trash chute/3-W
Trash chute/2-W
Trash chute/0. R.
Trash chute/5-E
Trash cart /incinerator room
Trash hopper/incinerator room
Linen hopper/laundry
Trash car t /incinerator room
Trash hopper /incinerator room
Linen hopper/laundry
Linen chute/2-W
Linen chute/3-E
Linen chute/3-W
Trash cart /incinerator room
Trash hopper/incinerator room
Trash cart/ incinerator room
Trash hopper /incinerator room
Linen hopper /laundry
Methodology: Swab samples streaked on
staphylococcus aureus and on MacConkey'
C -
1 -
0 -
0 -
0 -
1 -
13 -
0 -
0 -
5 -
0 -
0 -
0 -
0 -
0 -
0 -
1 -
1 -
0 -
0 -
0 -
0 -
0 -
0 -
C -
s -
p -
TYPE OF
S - P SWAB SAMPLE
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
0-0
Colonies
Staph aureus
Fseudomonas
nidnnitol salt agar for
s agar
for pseudomonas
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
dry
wet
wet
wet
wet
wet
detection of
All were in-
cubated at 37°C. for 48 hours.
-191-
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10-ECONOMICS OF HOSPITAL WASTE MANAGEMENT
The transporting and reduction of hospital solid waste has become increas-
ingly costly during the past fifteen years as the volume of waste has increased
along with hourly cost of the labor and supplies that must manage it. With
labor representing as high as 80 percent of the average hospital's operating
budget, every effort is made to conserve wages. Automation and mechanization,
by the installing of methods such as pneumatic transport systems, has been one
approach hospitals have used.
Most hospitals are now approaching capital expenditures on the basis that
they must save enough labor for such capital outlays to be self-liquidating in
under a ten year period. In the case of solid waste transport systems this is
an extremely difficult goal to achieve due to a variety of factors, ranging
from high capital installed costs, to cost of supplies, maintenance, power and
utility requirements, to the feasibility of using the automated system to the
maximum degree for the waste that must be transported as against hand cart or
other methods.
CAPITAL COSTS OF THE TRANSPORT S\STEM
In evaluating the costs of an automated installation such as a solid waste
pneumatic transport system, the amount of space taken up in the building by all
the components of the system and the value of the space, coupled with the in-
stalled price of the equipment, and the installed cost of all utilities that
are necessary for the operation of the system, are the principal factors. Based
on the original construction records these costs were obtained from the archi-
tect for each of the three pilot study hospitals. Space required for waste
handling external to the pneumatic tube system, yet exclusively devoted to this
purpose also must be included, such as chute loading rooms, waste storage areas,
compactor and incinerator areas. To this must be added the cost of the money
for purchasing the space and equipment; the interest on investment that will be
incurred over the expected life of the system. In developing costs, the space
used and the pneumatic system were capitalized as an investment over a twenty
year period.
-1*2-
-------
It is extremely difficult to obtain completely accurate figures in the
capital cost between the equipment itself and the labor required to install it.
A reasonable rule of thumb appears to be that, in the final installed price,
installation labor represents approximately 60 percent of the total.
CAPITAL COSTS OF INTERFACED EQUIPMENT
In a complete analysis of a solid waste pneumatic transport system it is
Important to also investigate the costs of all other equipment that interfaces
with the tube system. These items fall into two general classifications.
(1) Accessory equipment that is necessary to ensure the successful operation of
the transport system: such as carts to move the waste to the chute doors and
away from the final collector; or conveyors or other devices that will move
waste from remote points to provide a mechanical interface with the pneumatic
system; and reduction equipment such as floor compactors and shredders or grind-
ers to ensure waste will fit into the chutes- (2) General waste handling equip-
ment that is independent of the transport system but provides further efficiency
in solving the overall problem: such as compactors, attrition mills, inciner-
ators and gas scrubbers, trucks, scales, lifts, balers, conveyors, and off-site
hauling vehicles and containers. Finally, for the waste that is not handled by
the pneumatic transport system there are the capital costs of elevators and
other similar items, a portion of which are used for the transport of waste at
various times of the day.
In the three pilot hospitals, equipment on the floors that interfaced with
the pneumatic system were hand carts which were used to haul waste to chute
loading rooms and also to move bulky waste from the floors to the central col-
lection point. All of the hospitals had reduction equipment installed (com-
pactor and incinerator) after the final collector of the pneumatic system.
All of the hospitals were high rise structures and used elevators. In develop-
ing waste management costs such equipment was not capitalized, as it can be
purchased separately from the structure. A straight line depreciation method
was used, extending over the expected equipment life.
-193-
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OPERATING COSTS OF THE PNEUMATIC SYSTEM
The principal operating cost is labor. The first element is for materials
handling: the hours required to haul waste from the various points of generation
to the chute loading doors; depositing waste in the chutes (including waiting
times); moving waste from the collector at the end of the line to reduction units
such as compactor or incinerator. The second element is labor for maintenance,
both corrective and preventive. The third element is slightly different, yet
similar, to maintenance; namely housekeeping labor required to keep the system
and its interfacing areas clean and presentable. The fourth element is the cost
of training all labor elements in the operation of the system as well as direct-
ly managing the people who are actually doing the work. To these direct labor
costs must be added the fringe benefits and other labor overhead elements.
The second heaviest operating cost involves the supplies in which waste is
stored and transported, namely the various disposable bags and closures. Thirdly
are the costs of utilities, such as power to run the system.
OPERATING COSTS OF INTERFACED SYSTEMS
As seen from the preceding chapters, the pneumatic system handles only a
percentage of the total waste of each institution. The balance is hand-hauled
by cart to the central collection point. The labor for this has been separated
from the labor used for the pneumatic system.
The next major element in this group is that labor required to load and
maintain the reduction equipment at the end of the line, such as compactor and
incinerator, and to ensure that the housekeeping of this equipment, and the
area in which it is installed, is satisfactory.
The additional supplies for the interfaced equipment consist primarily of
the bags required to contain the hand-hauled waste and the cleaning materials
required for the reduction areas.
The utility costs of power for the compactor and incinerator, gas and oil
for the latter are the next item to be included. The final cost at the end of
-194-
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the line is the contract for hauling the waste off-site to the landfill. (This
applied at each of the three hospitals.)
A final item that must be included in determining the total waste manage-
ment costs for an institution is the cost of all the storage containers through-
out the floors of the building, ranging from waste baskets to 44 gallon contain-
ers, amortized over their expected life.
DIVISION OF FIXED COSTS BETWEEN WASTE AND LAUNDRY TRANSPORT
It could be argued that the entire fixed charges of installed equipment
and space costs, maintenance labor, and utility costs for a pneumatic system
could be charged against either waste or laundry transport, on the basis that
any hospital could elect to remove either product from using the system at
some point in time. (A review of all hospitals with pneumatic systems has re-
vealed that this has happened in a few cases due to management decisions.)
However, when the systems were originally installed for transporting both
products, as in the case of the three hospitals in the present study, it is
more logical to divide these fixed system costs between waste and laundry trans-
port. This approach has been used in this chapter and the following one to
determine the economic feasibility cf a pneumatic transport system. The basis
for the calculation is the number of bags of each product (rather than weight
or cube) that travel the system, as individual bag loads more closely repre-
sent the true use factor of such a system.
Tables 22 through 45 analyze all the foregoing cost factors for each of
the three hospitals studied and compare financially the systems each is using.
-195-
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TABLE 22
COST ANALYSIS
ST. MARY'S HOSPITAL, DULUTH
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
CAPITAL COSTS
Building Costs
Total Total Cost/
Construction Square Square
Costs Feet FcjQt
Total Cost/
Cubic Cubic
Feet Foot
$24,386,090 518,853 $47.00 7,902,910 $3.09
1. Area Costs
Laundry collector
Waste collector
Fan room
Control panel
Load stations (chute
rooms), total
Totals
Square Feet
576
216
265
150
1,008
2,215
Value e $47.00
$ 27,072
10,152
12,455
7,050
47,376
$104,105
Total
$104,105
2. Volume Costs
Length. Ft. Volame ;jg
Linen, waste
& air tubes 1.700
Totals 1,700
2,363
Value 6 $3.09
$7,302
$7,302 $ 7,302
3. Cost of Pneumatic System - Equj^aent and Installation
$193,157
TOTAL CAPITAL INVESTMENT FOR SPACE AND
TOTAL CAPITAL COST PER YEAR. 7% INTEREST. 20-^EAR LIFE
-------
IABL£ 23
COST ANALYSIS
ST. MARY'S HOSPITAL, DULUTH
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
DIRECT COSTS
1. Labor
Haul to and
load chutes
Avg. Rate
w/Fringes
Move to and load
compactor
Maintenance,
corrective and
preventive
$2.66
2.86
4.95
Total Labor Costs
Avg.
Hrs./
Month
441
74
Avg.
Cost/ Hrs./ Cost/
Month Year Year
$1,173 5,292 $14,077
212
292
888 2,540
708
3,505
Total
Dollars
$1,677 6,888 $20,122 $20,122
2.
Bags to Transport Waste
Black plastic
Nylon mesh
Total Supplies Cost
No./
ttonth
7,000
4,410*
Cost/
Month
$ 400
873
$1,273
No./
Year
84,000
52,900
Cost/
Year
$ 4,800
10,476
$15,276
$15,276
3. Total Utilities (Power S, Control)
TOTAL DIRECT COSTS
Cost/Month
$510
Cost/Year
$6,121 $ 6,121
$41,519
* These are reusable transport bags in which the plastic waste bags are
placed to prevent breakage or bag ripping. Each nylon bag is used for one
transport, then emptied, laundered, and re-issued. Total average inventory
is approximately 600. Average life is 200 uses. Cost for each use: to
purchase, fill, handle, dump, launder, store, and re-issue = $0.198 each per day.
-197-
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TABLE 24
COST AK&LYSIS
SI. MARY'S HOSPITAL* DULUTH
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
SUMMARY OF ANNUAL COSTS
CAPITAL COSTS AMORTIZED; $36,548
DIRECT OPERATING COSTS;
Labor $20,122
Transport Bags 15,276
Utilities 6,121
Total $41,519
INDIRECT OPERATING COSTS:
Downtime $ 255
TOTAL COST PER YEAR; $78,322
TOTAL COST PER MONTH: $ 6,527
DEDUCTION Of FIXED CHARGES PER YEAR
ASSIGNED TO LAUNDRY TRANSPORT (80%);
Capital Costs $29,238
Utilities Costs 4,897
Maintenance Costs 2?804
Total Deductions $36,939
NET COST PER YEAR FOR WASTE TRANSPORT: $41,383
NET COST PER MONTH FOR WASTE TRANSPORT: $ 3,449
-1S8-
-------
COST ANALYSIS
ST. MARY'S HOSPITAL. DULUTH
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
(Continued)
Total Pounds Transported per Month:
Total Cost per Pound
of Solid Waste Transported:
26,733
$ 0.13
Total Cubic Feet Transported per Month;
Total Cost per Cubic Foot
of Solid Waste Transported:
11,578
$ 0.30
Total Bags Transported per Month:
Total Cost per Bag
of Solid Waste Transported:
4,456
$ 0.77
-199-
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TABLE 25
ST . MARY ' S HOSniAL*
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
Labor
Cost/Hr.
Hrs./Mo. Cost/fete. Hgs./Yr. Cost/Yr.
Totals
Pick up bags,
load cart, walk
to elevator $2.93
Elevator time,
including wait-
ing, loading,
311
$ 911 3,732 $10,935
and unloading 2.93
Walk from ele-
vator & unload 2.93
Total Labor Costs
Ba^s to Receive and Transport
No . /Month
Beige plastic 20,000
Clear plastic 10,000
Red plastic 1,600
Clear kick bucket 1,600
Clear poly 5,000
Total Supplies Cost
68
10
389 $1
Waste
Cost/Month
$ 240
345
84
53
286
$1,008
199 816
29 120
,139 4,668
No. /Year
240,000
120,000
19,200
19,200
60,000
2,391
352
$13,678
Cost /Year
$ 2,880
4,140
1,008
639
3,432
$12,099
$13,678
$12,099
Utilities
Elevator power
25UP x 0.746 x $0.015
x 4.5 hrs./day x 7 x 4.33
Cost/Month
§38
Cost/Year
$456
$ 456
-------
COST ANALYSIS
ST. MARY'S HOSPITAL, DULUTH
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
(Continued)
Depreciation of Equipment
Elevator,
@ $60,000, 25-year life,
used 20% of the time
Waste baskets, trash containers
@ $3.50, 5-year life
Carts,
2 & $200, 10-year life,
Total Depreciation Costs
Cost/Month
Cost/Year
$
40
73
3
$ 480
880
40
$116
$1,400
$ 1,400
-201-
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TABLE 26
COST ANALYSIS
St. MARY'S HOSPITAL, JPULUTH
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
SUMMAJLV OF ANNUAL COSTS
Labor $13,678
Transport Bags 12,099
Utilities 45b
Depreciation 1,400
TOTAL COST PgR YEAR; $27,633
TOTAL COST PER MONTH; $ 2,303
Total Pounds Transported per Month: 42,161
Cost per Found
of Solid Waste Transported: $ 0.06
Total Cubic Feet Transported per Month: 5,607
Cost per Cubic Foot
of Solid Waste Transported: $ 0.41
Total Cart Trips per Month: 455
Cost per Cart Load of Solid Waste: $ 5
Cost per Bag Equivalent: $ 0.32
-------
TABLE 27
COST ANALYSIS
ST. MARY'S HOSPITAL, DULUTH
END OF LINE SOLID
Avg.
Avg. Rate Hrs./
Labor w/Fringes Month
Load incinerator $2.93 30
Incinerator ash
removal 2.93 38
Clean compactor
and bin (none - done
Clean compactor
and incinerator
areas 2.93 20
Maintenance ,
compactor and
iticinerator 2.93 12
Total Labor Costs 100
Off-Site Hauling
2 times per week ^ $44
Cleaning
Total Hauling Costs
Amortization of Space
Incinerator room, 20-year life,
162 sq. ft. @ §47
Loading dock, 20-year life
Total Amortization Costs
Depreciation of Equipment
Incinerator, 10-year life
Compactor, 10-year life
Total Depreciation Costs
WASTE HANDLING
Avg.
Cost/ Hrs./
Month Year
$ 88 360
111 456
by contractor)
59 240
35 144
$293 1,200
$381
15
$396
$ 76
$ 76
$152
$283
42
$325
Cost/
Year
$1,055
1,336
703
422
$3,516
$4,572
176
$4,748
$ 914
914
$1,828
$3,400
509
$3,909
Total
Dollars
$ 3,516
$ 4,748
$ 1,828
$ 3,909
-203-
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COST ANALYSIS
ST. MARY'S HOSPITAL, DULUTH
END OF LINE SOLID WASTE HANDLING
(Continued)
Utilities
Incinerator
Compact or
total Utilities Costs
Avg.
Cost/
Month
_ _ 1
$ 12
Cost/ Total
Year Dollars
$ 132
$ 144 $ 144
-204-
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TABLE 28
COST ANALYSIS
ST. MARY'S HOSPITAL, DULUTH
END OF LINE SOLID WASTE HANDLING
SUMMARY OF ANNUAL COSTS
Labor $ 3,516
Off-Site Hauling 4,748
Space 1,828
Equipment 3,909
Utilities 144
TOTAL COST PER YEAR $14,145
TOTAL COST PER MONTH $ 1,179
Total Incoming Pounds Handled per Month: 68,894
Cost per Incoming Pound Handled: $ 0.02
Total Incoming Cubic Feet Handled per Month: 17,185
Cost per Incoming Cubic Foot Handled: $ 0.07
Total Bags and Bag Equivalents Handled per Month: 11,736
Cost per Bag and Equivalent: $ 0.10
-205-
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TABLE 29
COST ANALYSIS
ST. MARY'S HOSeiTAL, BULtJTH
SUMMARY OF TOTAL HOSPITAL SOLID WASffe COSTS
Per Annum
1. Labor;
Pneumatic System $20»122
Hand Hauled System 13,678
End of Line System 3^516
Total $37,316
Less Laundry % of
P/N Maintenance (80%) 2,804
Net Labor Cost $34,512
2. Transport Bags;
Pneumatic System $15,276
Hand Hauled System 12,099
Total Transport Bag Cost $27,375
3. Capital Costs:
P/N System & Space $36,548
End of Line Space 1»B28
Total $38,376
Less Laundry % of
P/N Capital (80%) 29^238
Net Capital Cost $ 9,138
4. Depreciation of Equipment;
Hand Hauled System $ 1,400
End of Line System 3,909
Total Depreciation $ 5,309
5. Off-Site Hauling Contract^ $ 4,748
-206-
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COST ANALYSIS
ST. MARY'S HOSPITAL, DULUTH
SUMMARY OF TOTAL HOSPITAL SOLID WASTE COSTS
(Continued)
Per Annum
6. Utilities:
Pneumatic System $ 6,121
Hand Hauled System 456
End of Line System 144
Total $ 6,721
Less Laundry % of
P/N Utilities (80%) 4,897
Net Utilities Cost $ 1,824
7. Indirect Costs - Downtime of P/N System; $ 255
TOTAL NET COST PER YEAR; $83,161
TOTAL NET COST PER MONTH : $ 6,930
Total Pounds Disposed per Month: 68,894
Net Cost per Pound Disposed: $ 0.10
Total Cubic Feet Disposed per Month: 17,185
Net Cost per Cubic Foot Disposed: $ 0.40
Total Bags and Bag Equivalents per Month: 11,736
Net Cost per Bag and Equivalent: $ 0.59
Percent of Total Net Cost Attributable to Pneumatic System: 58%
Percent of Total Net Cost Attributable to Hand Hauling: 42%
-207-
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TABLE 30
COST ANALYSIS
VETERANS ADMINISTRATION HOSPITAL. SAN DIEGO
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
CAPITAL COSTS
Building Costs
Total
Construction
Costs
Total
Square
Feet
Cost/
Square
Foot
Total
Cubic
Feel
Cost/
Cubic
Foot
$35,250,000 677,700 $52.01 14,645,165 $2.41
1. Area Costs
Square Feet Value (g $52.01 Total
Laundry collector 63 $ 3,277
Waste collector
& compactor 578 30,062
Fan room 465 24,185
Control panel 156 8,114
Load stations (chute
rooms), total 3.238 168,408
Totals' 4,500 $234,046 $234,046
2. Volume Costs
Length. Ft. Volume @ 16"D Value @ $2.41
Linen & waste
tube 1,303 1,818 $4,381
Air tube 591 825 1.988
Totals 1,894 2,643 $6,369 $ 6,369
3. Cost of Pneumatic System - Equipment and Installation $350,000
TOTAL CAPITAL INVESTMENT FOR SPACE AMD SYSTQ1
TOTAL CAPITAL COST PER YEAR. 7% INTEREST, 20-YEAR LIFE
-208-
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TABLE 31
COST ANALYSIS
VETERANS ADMINISTRATION HOSPITAL. SAN DIEGO
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
DIRECT COSTS
Avg. Rate
1 . Labor w/Fringes
Haul to chute
loading room $3.31
Load chutes 3.66
Load compactor
Maintenance,
corrective and
preventive 4.92
Total Labor Costs
2. Bags to Transport Waste
White plastic
Total Supplies Cost
Avg.
Hrs./
Month
319
143
(no cost -
38
500
No./
Month
9,700
Avg.
Cost/
Month
$1,056
523
automatic
187
$1,766
Cost/
Month
$237
$237
Hrs./
Year
3,828
1,716
loading)
454
5,998
No./
Year
116,400
Cost/
Year
$12,671
6,281
2,224
$21,186
Cost/
Year
$2,849
$2,849
Total
Dollars
$21,186
$ 2,849
3. Total Utilities (Power & Control) Cost/Month Cost/Year
$560 $6,721 $ 6,721
TOTAL DIRECT COSTS
$30,756
-209-
-------
TABLE 32
COST
VETERANS ADMIKISTRAIIQK HOSE I'TAL. SAB DIEGO
PNEUMATIC SOLID WA&EE TRANSPORT SISIBd
SUMMARY OF ANNUAL COSTS
CAPITAL COSTS AMORTIZED: $ 70,850
DIRECT OPERATING COSTS:
Labor $21,186
Transport Bags 2,849
Utilities 6,721
Total $ 30,756
INDIRECT OPERATING COSTS:
Downtime $ 2,112
TOTAL COST PER YEAR; $103,718
TOTAL COST PER MONTH; $ 8,643
DEDUCTION OF FIXED CHARGES PER YEAR
ASSIGNED TO LAUSDRY TRANSPORT (54%);
Capital Costs $38,259
Utilities Costs 3,629
Maintenance Costs 1,201
Total Deductions $ 43,089
NET COST PER YEAR FOR WASTE TRANSPORT; $ 60,629
NET COST PER MONTH FOR WASTE TRANSPORT: $ 5,052
-210-
-------
COST ANALYSIS
VETERANS ADMIN 1STRAT ION HOSPITAL, SAN DIEGO
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
(Continued)
Total Pounds Transported per Month: 33,796
Total Cost per Pound
of Solid Waste Transported: $ 0.15
Total Cubic Feet Transported per Month: 16,701
Total Cost per Cubic Foot
of Solid Waste Transported: $ 0.30
Total Bags Transported per Month: 9,578
Total Cost per Bag
of Solid Waste Transported: $ 0.53
-211-
-------
Labor
TABLE 33
VETERANS ADMINISTRATION HOSPITAL. SAN QIEgQ
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
Coat/Hr. Hrs./Mo. Cost/Mo. HTS./YT, Cpst/Yr,
Totals
flck up bags,
lead cart, walk
to elevator $3.66 114 $417
Elevator time,
Including wait-
ing, loading,
and unloading 3.66 24 88
Walk from ele-
1,368 $5,007
288 1,054
vator & unload 3.66
Total Labor Costs
Ba$6 to Receive and Transport
No. /Month
Clear waste liner 36,000
Small red 6,500
Large red 4,400
Swall yellow 1,000
Large yellow 1,000
Large vinyl 3,300
Surgery, non-static 620
5
143
Waste
Cost /Month
$ 803
339
394
38
57
248
46
18 60
$523 1,716
No. /Year
432,000
78,000
52,800
12,000
12,000
39,600
7,440
220
$6,281
Cost /Year
§ 9,b35
4,064
4,726
459
688
2,970
555
$ 6,281
Total Supplies Costs
SL.925
$23,100
$23,100
Utilities
Elevator power,
2SHP x 0.746 x $0.015
K 12 hrs./day x 7 x 4.33
Cost/Month
§103
Cost/Year
$1,236
$ 1,236
-------
COST ANALYSIS
VETERANS ADMINISTRATION HOSPITAL. SAN DIEGO
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
(Continued)
Depreciation of Equipment
Elevator,
@ $60,000, 25-year life,
used 50% of the time
Carts,
2 rubber @ $200
2 O.K. aluminum @ $300
10-year life
Waste baskets, trash containers
@ $3.50, 5-year life
Total Depreciation Costs
Cost/Month
$100
3
5
211
$319
Cost/Year
$1,200
40
60
2.530
$3,830
$ 3,830
-213-
-------
TABLE 34
COST ANALYSIS
VETERASS ACTtlKlSTRATKffl HOSPIIA.L, SAN DIEGO
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
SUMMARY OF ANNUAL COSTS
Labor $ 6,281
Transport Bags 23,100
Utilities 1,236
Depreciation 3,830
TOTAL COST PER YEAR; $ 34,447
TOTAL COST PER MONTH: $ 2,871
Total Pounds Transported pet Month: 100,932
Cost per Pound
of Solid Waste Transported: $ 0.03
Total Cubic Feet Transported per Month: 30,856
Cost per Cubic Foot
of Solid Waste Transported: $ 0.09
Total Cart Trips per Month: 940
Cost per Cart Load of Solid Waste: $ 3.05
Cost per Bag Equivalent: $ 0.19
-214-
-------
TABLE 35
COST ANALYSIS
VETERANS ADMINISTRATION HOSPITAL, SAN DIEGO
END OF LINE SOL.
Avg.
Avg. Rate Hrs./
Labor w/ Fringes Month
Load incinerator $3.66 65
Incinerator ash
removal 3.66 40
Clean compactor
and bin 3.66 47
Clean compactor
and incinerator
areas 3.66 28
Maintenance ,
compactor and
incinerator 3.66 13
Total Labor Costs 193
Off -Site Hauling
3 tin>es per week. @ $80
Cleaning (Done in-house.
Total Hauling Costs
Amortization of Space
Incinerator room, 20-year life,
903 sq. ft. @ $52
Loading dock, 200 sq. ft. (.<• $52
Total Amortization Costs
Depreciation of Equipment
Incinerator, 10-year life
Compactor & 2 bins, 10-year life
ID WASTE HANDLING
Avg.
Cost/ Hrs./
Konth Year
?238 780
146 480
172 56-4
102 336
48 156
$706 2,316
$1,045
Included in labor,
$1,045
$470
104
$574
$595
58
Cost/
Year
$2,855
1,757
2,064
1,230
571
$8,477
$12,562
above . )
$12,562
$5,636
1,248
$6,884
$7,140
700
Total
Dollars
$ 8,477
$12,562
$ 6,884
Total Depreciation Costs
$653
$7,840
-215-
-------
GOS1 MAOSIS,
VETEBABS ADMIUI5TRATIQS HOSPITAL, SAE DIEGO
END OF LIKE SOLID, BASTE HANDJUSS.
(Continued)
Utilities
Incinerator
Co«f>actor
Total Utilities Costs
$20
Cost/
Year
$192
48
$240
Total
Dollars
240
-216-
-------
TABLE 36
COST ANALYSIS
VETERANS ADMINISTRATION HOSPITAL, SAN DIEGO
END OF LINE SOLID WASTE HANDLING
SUMMARY OF ANNUAL COSTS
Labor $ 8,477
Off-Site Hauling 12,562
Space 6,884
Equipment 7,840
Utilities 240
TOTAL COST PER YEAB $ 36,003
TOTAL COST PER MONTH $ 3,000
Total Incoming Pounds Handled per Month: 134,728
Cost per Incoming Pound Handled: $ 0.02
Total Incoming Cubic Feet Handled per Month: 47,557
Cost per Incoming Cubic Foot Handled: $ 0.06
Iota] Bags and Bag Equivalents Handled per Month: 24,618
Cost per Bag and Equivalent: $ 0.12
-217-
-------
TABLE 37
COST A8&LYS1S
VETE&AKS AfiMlNlSTRATlgS HOSPITAL. SAN DIEGO
SUMMARY OF TOTAL HOSPITAL SOLID WASTE COSTS
Per Annum
1. Labor:
Pneumatic System $21,186
Hand Hauled System 6,281
End of Line System 8j477
Total $35,944
Less Laundry % of
P/N Maintenance (54£) 1,201
Net Labor Cost $ 34,743
2. Transport Bagst
Pneumatic System $ 2,849
Hand Hauled System 23.100
Total Transport Bag Cost $ 25,949
3. Capital Costs;
P/N System & Space $70,650
End of Line Space 6,884
Total $77,734
Less Laundry % of
P/N Capita] (54%) 38»259
Net Capital Cost $ 39,475
4 Depreciation of Equipment:
Hand Hauled System $ 3,830
End of Line System 7,840
Total Depreciation $ 11,670
5. Off-Site Hauling Contract: $ 12,562
-------
CQS'i_ ANALYSIS
VETERANS ADMINISTRATION HOSPITAL. SAN DIEGO
SUMMARY OF TOTAL HOSPITAL SOLID WASTE COSTS
(Continued)
6. Utilities:
Per Annum
Pneumatic System $ 6,721
Hand Hauled System 1,236
End of Line System 240
Total $ 8,197
Less Laundry % of
P/N Utilities (54%) 3.629
Net Utilities Cost $ 4,568
7. Indirect Costs - Downtime of P/N System: $ 255
TOTAL NET COST PER YEAR: $129,222
TOTAL NET COST PER MONTH; $ 10,768
Total Pounds Disposed per Month: 134,728
Net Cost per Pound Disposed: $ 0.08
Total Cubic Feet Disposed per Month: 47,557
Net Ccst per Cubic Foot Disposed: $ 0.23
Total Bags and Bag Equivalents: 24,618
Net Cost per Bag and Equivalent: 0.44
Percent of Total Net Cost Attributable tc Pneumatic System: 54%
Percent of Total Net Cost Attributable to Hand Hauling: 46%
-219-
-------
TABLE 38
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL. LOS ANGELES
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
COSTS
Costs
Total
Construction
Costs
Total
Square
feet
Cost/
Square
Foot
Total
Cubic
Feet
Cost/
Cubic
Foot
$23,540,000
551,251 $42.70 5,952,520 $3.95
1. Area Costs
Laundry collector
Waste collector
Filter, attenuator,
and fan room
Control panel
Load stations (chute
rooms), total
Manholes
Totals
Square Feet
728
255
1,195
150
1,846
268
4,442
Value € $42.70
$ 31,085
10,889
51,027
6,405
78,824
11,444
§189,675
Total
$189,675
2. Volume Costs
. Ft.. Volume (g 20"P Value (3 $3.95
Horizontal
tubes , trash
Horizontal
tubes , linen
Air supply
piping
Vertical chutes
1,400
900
520
560
3,380
3,053
1,962
1,134
1,221
7,370
$12,059
7,750
4,479
4,823
$29,111
$ 29,111
^220-
-------
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL, LOS ANGELES
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
(Continued)
3. Cost of Pneumatic System - Equipment and Installation $425,000
TOTAL CAPITAL INVESTMENT FOR SPACE AND SYSTEM
TOTAL CAPITAL COST PER YEAR. 7% INTEREST, 20-YEAR LIFE
-221-
-------
TABLE 39
COST AKlU-YSIS
LCTtffiR JKIKG HOSPITAL, LOS AfiGELES
PNEUMATIC SOLJD
TRANSPORT SYSTEM
DIRECT COSTS
Avg. Rate
1. Labor y /fringes
Haul to chute
loading room
& load chutes $3.42
Load compactor
Maintenance,
corrective and
preventive 4.80
Total Labor Costa
2. Bags to Transport Waste
White plastic
Total Supplies Cost
3. Total Utilities (Powrer &
Avg.
Mrs./
Month
534
(no cost -
71
605
No./
Month
16,004
Control)
Awg.
Cost/
Month
•••••••••^^
$1,326
automatic
341
$2,167
Cost/
Month
$392
$392
Hrs . /
Year
6,408
leading)
852
7,2bO
No./
Year
Cost/
Year
$21,915
4,090
$26,005
Cost/
Year
Total
Dollars
$26,005
192,048 $4,700
Cost/Moath
$868
$4,700
Cost/Year
$10,416
$ 4,700
$10,416
TOTAL DIRECT COSTS
$41,121
-222-
-------
TABLE 40
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL. LOS ANGELES
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
OF ANNUAL COSTS
CAPITAL COSTS AMORTIZED; $ 77,254
DIRECT OPERATING COSTS;
Labor $2o,GG5
Transport Ba&s 4,700
Utilities 10,416
Total $ 41,121
INDI32CT OPERATING COSTS:
Downtime $ 821
TOTAL COST PER YEAR: $119,196
TOTAL COST PER MONTH; $ 9,933
DEDUCTION OF FIXED CHARGES PER YEAR
ASSIGNED TO LAUNDRY TRANSPORT (44%);
Capital Costs $33,992
Utilities Costs 4,583
Maintenance Costs 1,800
Total Deductions $ 40,375
X::T COST PER YEAR FOX WASTE TRANSPORT: $ 78,821
ALT COST PER MONTH FOR 'WASTE TRANSPORT; $ 6,568
23-
-------
COST ANALYSIS
MARTIN LUTHER KIKG HOSPITAL. LOS ANGELES
PNEUMATIC SOLID WASTE TRANSPORT SYSTEM
(Continued)
Total Pounds Transported per Month: 67,228
Total Cost per Pound
of Solid Waste Transported: $ 0.10
Total Cubic Feet Transported per Month: 30,552
Total Cost per Cubic Foot
of Solid Waste Transported: $ 0.22
Total Bags Transported per Month: 16,004
Total Cost per Bag
of Solid Waste Transported: $ 0.41
-224-
-------
TABLE 41
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL, LUS ANGELES
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
Labor
Cost/Hr. llrs./Mo. Cost/Mo. Hrs./Yr. Cost/Yr.
Totals
Pick up bags,
load cart, walk
to elevator
Elevator t ime,
including wait-
ing, loading,
$3.42
332
$1,135 3,984
$13,625
and unloading
Walk from ele-
vator & unload
Total Labor
Bags to Receive
Black plastic
Large clear
Waste liners
Red isolation
3.42
3.42
Costs
and Transport
No. /Month
7,000
15,000
20,000
1,600
73
11
416 $1
Waste
Cost/Month
$ 400
518
240
84
250 876
38 132
,423 4,992
No. /Year
84,000
180,000
240,000
19,200
2,996
451
$17,073
Cost /Year
$ 4,800
6,216
2,880
1,008
$17,073
Total Supplies Costs
$1,242
$14,904
$14,904
Utilities
Cost/Month
Cost/Year
Elevator power,
25HP x 0.746 x $0.015
x 4.8 hrs./day x 7 x 4.33
$.41
$492
492
-225-
-------
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL, LOS ANGELES
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
(Continued)
Depreciation o£ Equipment
Elevator,
@ $60,000, 25-year life,
used 20Z of the time
Carts,
8 § $200, 10-year life
Waste baskets,trash containers
0 $3.50, 5-year life
Total Depreciation Costs
Coat/Month
$ 40
13
207
$260
Cost/Year
$ 480
160
2,485
$3,125 $ 3,125
-------
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL, LOS ANGELES
HAND HAULED SOLID WASTE TRANSPORT SYSTEM
SUMMARY OF ANNUAL COSTS
Labor $17,073
Transport Bags 14,904
Utilities 492
Depreciation 3,125
TOTAL COST PER YEAR: $35,594
TOTAL COST PER MONTH: $ 2,966
Total Pounds Transported per Month: 44,253
Cost per Pound
of Solid Waste Transported: $ 0.07
Total Cubic Feet Transported per Mcnth: 5,456
Cost per Cubic Foot
of Solid Waste Transported: $ 0.54
Total Cart Trips per Month: 485
Cost per Cart Load of Solid Waste: $ 6.12
Cost per Bag Equivalent: $ 0.38
- ' "> 7—
-------
TABLE 43
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL, LOS ANGELES
END OF
Avg. Rate
Labor w/Fringes
Load incinerator $3.42
Incinerator ash
removal 3 . 42
Clean compactor
and bin 3.42
Clean compactor
and incinerator
areas 3.42
Maintenance,
compactor and
incinerator 4.80
Total Labor Costs
Off-Site Hauling
Approximately
2 times per week @ $48
Cleaning
Total Hauling Costs
Amortization of Space
Incinerator pad, 20-year life
900 sq. ft. @ $15.50
Loading dock, 20-year life,
600 sq. ft. @ $18.00
Total Amortisation Casts
Pjgr eclat ion of Equipment
Incinerator , 10-year Life
Compactor, 10-year life
Total Depreciation Costs
LINE SOLID WASTE HANDLING
Avg. Avg_.
Hrs./ Cost/ Hrs./
Month Month Year
32 $109 384
«»0 137 480
4? 161 564
21 72 25:
13 62 156
153 $541 1,836
$411
(Included in labor above)
$411
»
$ 38
45
$103
$574
58
£632
Cost/
Year
$1,313
1 , 642
1,929
862
749
$6,492
$4,926
$4,926
$ 698
540
$1,238
$6,890
700
$7,590
Total
Dollars
$ 6,492
$ 4,926
$ 1,238
$ 7,590
-228-
-------
COST ANALYSIS
MARTIN LUTHKR KING HOSPITAL, LOS ANGELES
END OF LINK SOLID WASTE HANDLING
(Continued)
Avg.
Cost/ Cost/ Total
Utilities Month Year Dollars
Incinerator $16 $192
Compactor 4_ 48
Total Utilities Costs $20 $240 $ 240
-229-
-------
TABLE 44
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL, LOS ANGELES
END CF LINE SOLID WASTE HANDLING
SUMMARY OF ANNUAL COSTS
Labor $ 6,492
Off-Site hauling 4,926
Space 1,238
Equipment 7,590
Utilities 240
TOTAL COST PER YEAR $ 20,486
TOTAL COST PER MONTH $ 1,707
Total Incoming Pounds Handled per Month 111,480
Cost per Incoming Pound Handled: $ 0.02
Total Incoming Cubic Feet Handled per Month: 36,008
Cost per Incoming Cubic Feet Handled: $ 0.05
Total Bags and Bag Equivalents Handled per Month: 23,763
Cost per Bag and Equivalent: $ 0.07
-230-
-------
TABLE 45
COST ANALYSIS
MARTIN LUTHEK KING HOSPITAL. LOS ANGELES
SUMMARY OF TOTAL HOSPITAL SOLID WASTE COSTS
Per Annum
1. Labor:
Pneumatic System $26,005
Hand Hauled System 17,073
Find of Line System 6,492
Total $49,570
Less Laundry % of
P/N Maintenance (44,") 1,800
Net Labor Cost $ 47,770
2. Transport bags:
Pneumatic System $ 4,700
Hand Hauled System 14,904
Total Transport Bag Cost $ 19,604
3. Capital Costs:
P/N System & Space $77,254
End of Line Space 1,238
Total $78,492
Less Laundry % of
P/N Capital (44%) 33,992
Net Capital Cost $ 44,500
4 Depreciation of Equipment:
Hand Hauled System $ 3,125
End of Line System 7,590
Total Depreciation $ 10,715
5. Off-Site Hauling Contract: $ 4,926
-231-
-------
COST ANALYSIS
MARTIN LUTHER KING HOSPITAL, LOS ANGELES
SUMMARY OF TOTAL HOSPITAL SOLID WASTE COSTS
(Continued)
6. Utilities:
Per Annum
Pneumatic System $10,416
Hand Hauled System 49.2
End of Line Systen 240
Total 311,148
Less Laundry % of
P/N Utilities (44%) 4.583
Net Utilities Cost $ 6,565
7. Indirect Costs - Downtime of P/N System; $ 821
TOTAL NET COST PER YfcAJR; $134,901
TOTAL NET COST PER MONTH: $ 11,242
Total Pounds Disposed per Mouth 111,480
Net Cost per Pound Disposed: $ 0.10
Total Cubic Feet Disposed per Month: 36,008
Net Cost per Cubic Foot Disposed: $ 0.31
Total Bags and Bag Equivalents: 23,763
Net Cost per Bag and Equivalent: $ 0.47
Percent of Total Net Cost Attributable to Pneumatic System: 68%
Percent of Total Net Cost Attributable to Hand Hauling: 32%
-232-
-------
!:- ECONOMIC FEASIBILITY OF
PNEUMATIC SOLID WASTE TRANSPORT SYSTEMS
The term economic feasibility infers a comparison between available meth-
ods. To be feasible, a system must save labor or money over alternative ways
of performing the same task; over a given time period the investment in the
system, combined with the direct and indirect operating costs, must be self
liquidating from the dollars that are saved. while other systems are possible
(and are available) for solid waste transport, the basic comparison that should
first be made is against hand hauling, involving carts, hallways, and elevators
to move the waste, as this is the most common method used in hospitals. The
basic determination must be made as t.o whether installation of the automated
system saves hand labor and to what degree.
In reviewing the figures from the previous chapters, it can be seen that
all three hospitals transport waste by both the pneumatic system and by hand
carts, and in varying proportions, depending on their management system. In
each hospital the hand hauled waste is transported at a lower cost per pound
than the pneumatically transported material. The differences on a per cubic
foot or volume basis are not as clear cut, varying from lower in cost to higher
for the carted material.
Comparisons of costs by weight are more valid than by cube, as the bulk.
of the hand carted material consists of empty cartons with extremely large
bulk. If they were slit or compressed on the floors to bring cube and weight
to relatively the same ratio as the pneumatically transported wastes, compari-
sons on a cube basis would be more realistic.
TABLE 46 CQS1 OF TRANSPORTING WASTE
ITEM
Avg. pounds/day
$ cost per pound
Avg. cubic feet/day
$ cost per cu. ft.
ST. MARY'S
DULUTH
PNEUMATIC tlAND
TUBE CART ED
882 1,391
0.13 0.06
382 185
0.30 0.41
V . A . MART IN LUTHER KING
SAN DIEGO LOS ANGELES
PNEUMATIC HAND PNEUMATIC HAND
TUBE CARTED TUBE CARTED
1,115 3,330 2,218 1,460
0.15 0.03 0.10 0.07
557 1,018 1,008 180
0.30 0.09 0.22 0.54
33-
-------
Several factors contribute to the higher cost per pound for the waste
transported by the pneumatic systera.
The first, and most obvious, is the high net cost of the space occupied
and the installed price of the pneumatic system equipment and its necessary
utility lines. With total installed costs amortized from $36,548 to $77,254
per year, the annual use percentage devoted to solid waste transport amortizes
from $7,310 to $32,591 to $43,262 for the three hospitals.
Secondly, while these are automated systems, they are not completely auto-
matic. They require labor to load and, in one case, unload the system. They
also require extensive labor for preventive and corrective maintenance. These
labor factors require supervision and they involve other overhead, including
fringe benefits.
Thirdly, each pneumatic system involves the cost of purchasing special
bags to transport the waste, and the cost of utilities to supply power and run
control circuits. Should they be "down" for maintenance work, they incur extra
costs to transport waste by other methods.
Added together, all these costs directly attributable to the pneumatic
systems range from $41,383 to $60,629 to $78,821 per year for the three hospi-
tals.
Figuring an average wage for a "typical" waste handler in a hospital at
$3.30 per hour, with fringes and overhead (or an average of $6,900 per year in
1973), the pneumatic system installed and operating annual costs for waste trans-
port alone are the equivalent of the wages of from 6 to 8.7 to 11.4 full time
positions for manual waste handling in the three hospitals. To these must be
added the costs of the proportion of waste that is manually transported.
To determine the legitimate economic feasibility of the three systems, it
is necessary to determine whether each can save what proportion of this labor
p«r year.
The percent of total cost of solid waste transport attributable to the
pneumatic system varied from 54 to 68 percent, yet the percent of the total
weight handled by the systems ranged from only 25 percent to a high of 60 per-
cent. Assuming a hospital elects to use an automated pneumatic transport sys-
tem, then it must do so to the point where virtually no waste is transported
-234-
-------
outside the system. No hospital, no matter how large, can justify automation
(at the installed costs of the past five years) unless it is used to the maxi-
mum extent possible.
All three survey hospitals had low utilization rates. All felt that this
is caused by limitations in the system. Basically this comes down to the load-
ing patterns and methods they had developed. The reasons for these do not ap-
pear completely valid.
Research by the survey team in other institutions with similar systems
has revealed that all waste of all types can be sent through a pneumatic sys-
tem with virtually no breakage problems, or plugging of the system, if the
system is designed and installed correctly; if the unit loads are properly
assembled and sized; if the transport bags are purchased to adequate specifi-
cations.
From a review of the make-up of the waste transported by hand, it is seen
that the bulk of it is toe large to enter the pneumatic system. This situation
applies to a large percentage of the over 75 hospitals that have installed
pneumatic tubes for waste transport. Very few have installed portable volume
reduction and compacting equipment on the floors (ahead of the chute stations)
to eliminate this problem. There appears no valid reason for this situation
to continue.
Assuming each of the three surveyed hospitals elected to send all its
wastes through the pneumatic system, and to spend the necessary additional
labor or equipment dollars for floor volume reduction to achieve this, the
cost figures for transport that were developed in the previous chapter would
be considerably reduced.
The high capital cost for space and the installed equipment would now be
spread over four times the total weight of waste at V.A. Hospital; almost three
times at St. Mary's; and a 40 percent increase at Martin Luther King. This
would obviously considerably reduce the cost per pound from the fixed charges.
Utility costs and downtime coats, based on. the way the systems are operated,
would remain about the same as they are for the present partial utilization.
Maintenance labor would also remain as a constant. Operating labor would rise
at a different rate in each hospital, due to the differences in the systems and
-235-
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chute loading methods. Transport bags would rise virtually in proportion
to the added waste being transported through the system. The following figures
reveal these revised costs:
ST. MARY'S V.A. MARTIN
DULUTH SAN DIEGO LUTHER KING
Lbs. total waste transported/month 68,894 134,728 111,480
MONTHLY COSTS
Capital cost, net 609 2,716 3,605
Labor, operating, and maintenance 2,828 1,831 2,381
Transport bags 2,660 782 470
Utilities 102 258 486
Downtime 21 176 68
TOTAL MONTHLY COSTS 6,220 5,763 7,010
COST PER POUND 0.09 0.04 0.06
It will be seen that these figures approach the per pound costs presently being
incurred in each hospital for hand carting wastes.
In addition, each of the three hospitals Is underloading the waste trans-
port bags by almost 60 percent on a weight basis. Further, if the bags were
actually mechanically sized and compacted before chute loading, bag costs and
chute loading costs could be reduced by up to 75 percent in two of the hospi-
tals including amortizing the cost of the floor compactors. These changes would
mean monthly savings to the three hospitals and per pound transport costs as follows:
NET SAVINGS REVISED MONTHLY TRANSPORT
PER MONTH COST, NET COST PER LB.
St. Mary's Hospital $1,993 $4,227 0.061
Veterans Administration Hospital 701 5,062 0.037
Martin Luther King Hospital 654 6,356 0.057
In the case of St. Mary's and the Veterans Administration, these figures are
only slightly higher than their present per pound costs for hand carting wastes;
in the case of Martin Luther King, the figure is lower.
If all the wastes had to be hand transported, would the costs compare to,
-236-
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be lower, or exceed the costs attainable from using the pneumatic system to
the full extent? The revised pneumatic system costs are the equivalent of
7.3 full time positions in St. Mary's, 8.8 at the Veterans Administration, and
10.4 at Martin Luther King. Table 47 shows costs for hand hauling all waste.
Reviewing all the generation points of waste at each of the three hospi-
tals; the. weights and volumes generated; the hours of the day and frequency
that transport must take place to equal the efficiency of removal of the
pneumatic system; and the equipment that must be used; the cost figures shown
on the following page would result from a complete hand transport system, using
hallways and elevators, in each of the three surveyed hospitals.
Once the basis for comparison has been established in this matter, it is
then possible to finally establish the differences in cost between transport-
ing waste pneumatically and transporting waste completely by hand. These cost
differences are then true monthly or annual savings as a result of installing
the pneumatic system. Table 48 on page. 240 shows these differences and hence
savings, as a result of installing a pneumatic system in each of the three hos-
pitals, but with two major differences from the way the systems are currently
I/eing utilized. The first figures show the operating costs and savings of the
pneumatic system utilized to the full extent, transporting all waste in the
building with none being hand hauled. The second group of figures shows the
costs reduced even further and the savings consequently increased by loading
each transport bag to the fullest extent in order to reduce the number of bags
and hence the chute loading and waiting time labor, as well as the cost of
transport bags.
Despite these impressive annual savings as a result of full utilization
of the chute system, only in the case of the second alternate method can a
recapture of investment be obtained. In the case of St. Mary's, the time
period of 5-3/4 years shows that their system could be feasible from an econ-
omic standpoint. In the case of the V.A. Hospital and Martin Luther King,
with payoffs as long as 49 and 58 years respectively, the time period to re-
capture, the investment at 7 percent interest is so extensive that in all prob-
ability the system would be worn out halfway through the investment life.
It should be noted that if no interest were charged on the investment,
-237-
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TABLE 47
ECONOMIC FEASIBILITY
MONTHLY COST TO HAND HAUL ALL HOSPITAL SOLID WASTE
ST. MARY'S
HOSPITAL
V.A.
HOSPITAL
M. L. KING
HOSPITAL
Avg. no. of cart trips (to equal floor clearing (§
hourly rate of present pneumatic system)
1. LABOR;
Empty waste containers, load carts, walk to
elevator, elevator time (including waiting),
walk to compactor, load compactor, return to
elevator, elevator time (including waiting),
walk to next pick-up point
2. BAGS TO RECEIVE AND TRANSPORT WASTE:
3. UTILITIES:
Elevator power, 25HP x 0.746 x $0.015
x hours used per month
4. DEPRECIATION OF EQUIPMENT:
Elevator @ $60,000, 25-year life,
x period used
Carts, 10-year life
Trash containers, 5-year life
Total costs per month
Number of pounds per month
Cost per pound
121
Hrs/Mo Cost/Mo
1,359 $4,340
Cost/Mo
$1,644
114
173
9
73
$6,358
68,894
0.09
170
Hrs/Mo Cost/Mo
1,355 $4,525
Co at /Mo
$2,162
188
258
24
211
$7,368
134,728
0.05
180
Hrs/Mo Cost/Mo
1,871 $6,225
Cost /Mo
$1,634
143
226
39
207
$8,474
111,480
0.08
N.
Ou
oo
-------
recapturing of investment could take place in under 20 years. However, in
today's money market it is felt that this is an unreasonable approach from an
accounting practice and that such capital investments should be amortized at
least at 7 percent interest, when the prime rate has risen to 10 percent.
A review of amortization investment tables reveals an interesting fact.
It clearly shows the upper limits of capital investment that can be made in
the equipment and the occupied space for automated systems in any hospital.
factored against varying amounts of savings per year.
If savings of $26,000 per year are to be realized from the installation
of a system and a 7 percent interest rate is used for amortizing the equipment
and occupied space, the maximum capital investment cannot exceed $270,000 if
the investment is to be recaptured within 20 years through savings. If the
realized savings fall to $18,000 per year, the upper limit on a capital in-
vestment,with 7 percent interest for the money, falls to $170,000 if the in-
vestment is to be amortized within this same 20 year period.
This clearly indicates that not only do pneumatic waste handling systems
have to be utilized for both waste and laundry handling (regardless of the de-
sign of the system) but that they must be utilized to the fullest, possible ex-
tent in order to save maximum labor; and most important that to be economi-
cally feasible the upper limits of investment in equipment and space are much
lower than hospitals have been expending in installing such systems. Whether
the desired operational results can be achieved under the inflationary condi-
tions of 1974 through pneumatic transport systems costing much less than those
that have been installed so far remains to be seen. Probably increased vendor
competition, better designs, better hospital management practices, and improved
system construction will achieve these results during the coming years. It
would appear that unless these goals are achieved such systems will be one
more example of adding to increased hospital costs without proven economic
feasibility.
-239-
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TABLE 48
t-
o
ECONOMIC FEASIBILITY
OF THE PNEUMATIC TRANSPORT SYSTEMS
1.
2.
3.
4.
5.
6.
7.
8.
9.
Monthly costs with full utilization
of the pneumatic system
Revised monthly costs by maximum
reduction of bags transported
Monthly costs of hand transporting
total waste output
Monthly savings - line 1 over line 3
Annual savings - line 1 over line 3
Monthly savings - line 2 over line 3
Annual savings - 1 ine 2 over line 3
Revised proportion of capital system
investment for waste under full
utilization
Years to recapture waste use proportion
of amortized capital investment in the
pneumatic system; @ 7% interest.
through savings line 1 /line 3
through savings line 2 /line 3
ST. MARY'S
HOSPITAL
$6,220
4,227
6 , 358
138
1,656
2,131
25,572
118,780
infinity
5-3/4
V.A.
HOSPITAL
$5,763
5,062
7,368
1,605
19,200
2,306
27,672
419,195
infinity
49
M. L. KING
HOSPITAL
$7,010
6,356
8,474
1,464
17,568
2,118
25,416
392,709
infinity
58
-------
12 . SYSTEM RATINGS AND COMPARATIVE ANALYSES
The principal automated systems to which a pneumatic tube transport system
may be compared are:
1.) Selective, vertical-horizortal conveyor systems with tote boxes moving
the waste.
2.) Automated cart systems, either run from an overhead rail, or from a
strip or guide in the flocr or adjacent baseboard.
3.) Wet pulping systems in which the waste is ground, mixed with water,
and pumped through relatively small tubes to an extractor where ap-
proximately 50 percent of the water Is removed. The damp pulp residue
is then further handled.
4.) Grinding systems (the typical home kitchen-type disposal) in which the
waste is ground and dumped directly into the sewer system from point
of generation. (These may be installed throughout all sections of the
building, or merely zoned in the lower levels and the waste moved to
the zone receiver by manual horizontal methods combined, [or not combined]
with gravity chutes.)
5.) Other pneumatic waste systems. In this study, all three systems are of
a different type: (a) full vacuum, single bag loading; (b) full vacuum,
multiple bag loading; and (c) gravity to vacuum, multiple bag loading.
In addition, comparisons must be made with the more conventional or "hand
removal" systems, either hand movement by cart for both horizontal and vertical
transfer, or the combinations of hand horizontal movement on the floors with
gravity chutes handling the vertical movement, coupled with hand movement at the
bottom of the gravity chutes to a central collection point.
Due to the very few hospitals that use automated methods other than pneumatic
tube systems, it was determined that, the comparative analyses in this study should
be limited to:
a.) Comparisons and ratings between the three types of pneumatic tube sys-
tems themselves, and
b.) Comparisons between the pneumatic tube systems and the hand transport
-241-
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systems that most (over 98 percent) of American hospitals employ.
In a study of this type, the final desired result is to assist architects,
engineers, consultants, and users in selecting the "best" system for a partic-
ular project that may arise in the future. In short, to develop guidelines
and "rate" such systems from several denominators.
In the Technical and Economic Analysis, we have identified many problems
in solid waste management in general, and in pneumatic transport systems in
particular. These range from architectural, design, mechanical, and opera- .
tioUal deficiencies of the structure and physical equipment, to human opera-
tional, maintenance, and training problems, through problems in cost justifi-
cation and economic feasibility. We have identified many environmental prob-
lems that affect the health and safety of the hospital personnel and possibly
of the community.
In most previous comparative ratings of solid waste management systems,
primary emphasis has been placed on economic considerations. These ratings
usually compare systems based only upon how much the equipment costs to pur-
chase, install, operate, and maintain. While economic considerations are im-
portant to hospital administrations, particularly in these days of rising
costs, systems economics is only part of the picture.
Equally important are the improved environmental factors to be attained
by both the hospital and the community. The spread of aerosols, atmospheric
cross contamination, and other pollution, are reduced or increased in varying
degrees by each different system. Fire and other safety hazards are reduced
or increased depending on the equipment used and how it operates.
A major purpose for automating solid waste management is to reduce the
spread of infection, accidents, and illnesses, thus providing advantages to
patients, staff, and visitors. There are certain esthetic advantages which
may be attained by reason of improved sanitation and a reduction in the number
of sometimes noisy waste carts moving through the corridors. These consider-
ations must also be taken into account in rating different systems and their
success in achieving these goals, since the higher cost to achieve them may
the® be justifiable.
In comparing the available pneumatic systems, it is essential to break
-------
down the comparable elements oi importance to the following:
Economics
Total capital costs
Total direct costs
Total indirect costs
Cost per pound transported
Cost per cubic foot
transported
Cost per bag transported
Technical Design
Ease and safety of loading
Qualifications required di
loading personnel
Speed of loading and
clearing floors
Strength and size of
chutes and tubes
Completeness and interfacing
of components
Environmeiital Acceptability
Sound levels
Odor levels
Bacterial contamination
Housekeeping practices
User Acceptability
Safety
Physical hazards
Fire hazards
Contamination hazards
Reliabilit>
Machinery
Personnel
Maintainability
Corrective maintenance
Preventive maintenance and
inspections
Flexibility for Modification
Potential for Expansion
Comparisons between systems must be based on both qualitative and quanti-
tative factors. Some are arrived at by value judgements and qualified obser-
vations; some by value judgements of the results of interviews with hospital
personnel; some by hard engineering data and physical measurements. Others
are based on actual audits of labor expended, of equipment and other costs,
and by physical testing.
The pneumatic transport systems of the three survey hospitals were com-
pared against one another on an element by element basis. A combined numeri-
cal and narrative rating was assigned each element. Under this, a system was
judged "best," "next best," or "least best" for that element. The "best" sys-
tem element was assigned a rating of 3, the "next best" a rating of 2, and the
"least best" a rating of 1. For example, in the element of economics, the
system with the lowest cost per pcund to transport solid waste by pneumatic
-------
tube was rated 3, the system with the highest cost was rated 1, and the re-
maining system was rated 2. In the event two or more systems were judged to
be equal, they were assigned the same rating number and then the next lower
number was omitted from the ratings. For example, if systems A and B were
equally low in cost, they both would be given a rating of 3 and the remaining
system a rating of 1. This same rationale was followed for the other elements
of importance.
The matrix on the following pages presents the results of the solid waste
transport systems comparisons.
-244-
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PNEUMATIC SYSTEMS COMPARISON MATRIX
i
^
.t-
-------
OF
IMPORTANCE
HOSPIT2AL
MARTIN
KING
ST. MARY'S
HOSPITAL
.TECHNICAL
DESIGN (Cont.)
Qualifications
required of
loading
personnel
Speed of
loading and
clearing
floors
Strength and
si/;e of
chutes and
tubes
Completeness
and inter-
facing of
components
Training critical due to
operation of diverter
valves. Uses special
personnel.
Rating 1
Requires 462 hours per
month to clear floors
and load chutes. Time
to clear floors far ex-
ceeds loading time.
1.66 minutes per cubic
foot to clear floors
and load.
Hating 2
Chute aad tube diameter
16", 20-igauge metal.
This is borderline as a
minimum diameter and
wall thickness.
Rating 1
System is enclosed and
complete with air gap at
compactor, which dis-
charges directly into a
large bin for hauling.
Bin relatively accessible
for truck pick-up.
Value judgement rating 2
Systeir capable of com-
plete random loading
without operator train-
ing.
Rating 3
Requires 534 hours per
month to clear floors
and load chutes. Time
to clear floors far ex-
ceeds loading time.
1.05 minutes per cubic
foot to clear floors
and load.
Rating 3
Tube diameter 20", 14-
gauge in vertical grav-
ity chutes. Horizontal
vacuum tubes 20" dia-
meter, 3/16" wall thick-
ness .
.Rating 3
System is enclosed and
complete through compac-
tor, which discharges
directly into a large
bin for hauling. Bin
easily accessible to
truck.
Value judgement rating 3
Minimal training mostly
concerned with type
waste authorized and
size of chute.
Rating 2
Requires 441 hours per
month to clear floors
and load chutes. Time
to clear floors slightly
less than loading time.
2.29 minutes per cubic
foot to clear floors
and load.
Rating 1
Chute and tube diameter
Ib", 20-gauge metal.
This is border lint; as a
minimum diameter and
wall thickness.
Rating 1
System is enclosed only
to collector, then hand
hauled outside to com-
pactor, which is located
at an undersized loading
dock.
Value judgement rating 1
-------
ELEMENT OF
IMPORTANCE
V.A.
HOSPITAL
MARTIN LUTHER
KING HOSPITAL
ST. MARY'S
HOSPITAL
i
h.
TECHNICAL
DESIGN (Cent.)
Efficiency of
fan & filter
installation
Et fic iency uf
control
circultrv
Excellent design of posi-
tive displacement single
fan with well engineered
vibration pad. 2 micron
Rollomatic filter to pro-
tect fan and prevent es-
cape of organisms in the
exhaust air. Well en-
gineered safety system
to prevent fan damage due
to high vacuum caused by
tube plugging.
Rat ing 3
Control panel located in
interstitullar space and
difficult to reach quick-
ly in emergency. No
trouble shooting panel
in Engineer's office.
Rating 1
Excellent design of posi-
tive displacement dual
fans together with aux-
iliary fan to maintain
negative pressure in
chutes. Cycling of fans
to ensure maximum per-
formance. Well engineer-
ed vibration pads. 2
micron bag filter to pro-
tect fan and prevent es-
cape of organisms in ex-
haust air. Well engi-
neered safety system to
prevent high vacuum
Rating 3
Excellent trouble shoot-
ing and control panel in-
stalled in fan room.
However, no monitoring
panel in Chief Engineer's
office.
Rating 3
Fan is open materials
handling type. Vibration
mounting and fan to motor
coupling is border line,
No pre or post fan filter
to protect either fan
blades or the environ-
ment. High vacuum safety
system is slow acting.
Motor mount damage al-
ready experienced due to
fan blade imbalance.
Rating 1
Vendor circuitry was over-
simplified. Hospital en-
gineer developed and lo-
cated in main engineering
office an excellent con-
trol and monitoring panel.
Rating 3
Total rating
points
21
10
-------
ELEMENT OF
IMPORTANCE
V.A.
HOSPITAL
MARTIN LUTHER
KING HOSPITAL
ST. MARY'S
HOSPITAL
i
I-J
ENVIRONMENTAL
ACCEPTABILITY
Sound levels Predominantly low fre-
quency sound. Average
maximums ranged from 68-
77 dB(A) with overall
average of 65 dB(A) in
corridors. Maximum aver-
age sound in system was
inside fan room at
95 dBU).
Rating 1
Odor levels Strongest odor at collec-
tor. One load station
had Code 4 odor. 93£ of
all locations had Code 3
or leas.
Rating 2
Bacteriological No pathogenic bacteria
contamination were found inside the
hospital.
Rating 3
Housekeeping
practices
Many cross-over problems.
Ruptured bags, loose
trash.
Value judgement rating 2
Predominantly low fre-
quency sound. Average
maximums ranged from 59-
63 dB(A) with overall
average of 60 dB(A) in
corridors. Maximum aver-
age sound in system was
inside collector/compactor
rooc at 98 dB(A).
Rating 3
Strongest odor at collec-
tor. One load station
had Code 4 odor. 86% of
all locations had Code 3
oe less. Cede 4 odor
close to private property,
Rating 1
Pathogens were observed
but were well below dan-
ger level.
Rating 3
Bag breakage on slide
valve, which had not been
properly cleaned. Evi-
dence of unauthorized and
unsanitary waste in
system.
Value judgement rating 2
Predominantly low fre-
quency sound. Average
ruaximums ranged from 60-
69 dB(A) with overall
average of 62 dB(A) in
corridors. Maximum aver-
age sound in system was
inside fan room at
104 dB(A).
Rating 2
Strongest odor at com-
pactor. No load station
had Code 4 odor. 93% of
all locations had Code 3
or less.
Rating 3
No hazardous bacteria
were found.
Rating 3
No broken bags, litter,
dust observed. Bag
breakage solved by use
of nylon bags.
Value judgement rating 3
Total rating
points
11
-------
ELEMENT OF
IMPORTANCE
V.A.
HOSPITAL
MARTIN LUTHER
KING HOSPITAL
ST. MARY'S
HOSPITAL
USER
ACCEPTABILITY
ro
-C-
Total rating
points
SAFETY
Physical
hazards
Fire hazards
25.1% of total waste
moved by tube. Trust-
ability factor low. Di-
verter valve and person-
nel problems cause laun-
dry to go to compactor,
waste to laundry room.
Many of staff feel they
are serving the system
rather than the system
serving thera.
Value judgement rating 1
Hazardous condition in
key lock loading due to
vacuum pull on chute
door. No unsafe or haz-
ardous conditions for
maintenance staff except
high noise level in fan
room.
Value judgement rating 1
Meets NFPA Code for tube
size. Has fusible link
fire dampers but these
occasionally cause bag
ripping. No indication
of fire in system.
60.3% of total waste
moved by tube. Trust-
ability factor high.
Loading is relatively
easy and fast, causes
few problems. Staff
generally was pleased
with system.
38.8% of total waste
moved by tube. Trust-
ability factor medium.
System slow, requires
much waiting to load.
Many of staff feel they
could clear floors faster
by hand. Some staff also
feel tube too small.
Value judgement rating 3 Value judgement rating 2
Possible hazardous con-
dition exists for main-
tenance staff in slide
valve rooms. High noise
level in fan room. No
unsafe consitions for
operating staff.
No unsafe or hazardous
conditions for operating
or maintenance staff ex-
cept high noise level in
fan room.
Value judgement rating 2 Value judgement rating 3
Value judgement rating 2
Exceeds NFPA Code for
tube size. Has fusible
link fire dampers but
these occasionally cause
bag ripping. No indica-
tion of fire in system.
No hopper in load chute
might contribute to chute
fires as could trash on
slide valve.
Value judgement rating 3
Meets NFPA Code for tube
size. Has fusible link
fire dampers but these
occasionally cause bag
ripping. No indication
of fire in system. Fan
room is marginal due to
lint conditions.
Value judgement rating 1
-------
ELEMENT OF
IMPORTANCE
V.A.
HOSPITAL
MARTIN LUTHER
KING HOSPITAL
ST. MARY'S
HOSPITAL
SAFETY (Cont.)
Contamination
hazards to
patients and
staff
Only non-pathogenic fo-
mites were found inside
hospital.
Value judgement rating 3
Small colony of krebsi-
ella found on laundry
floor. Not considered
hazardous to patients or
staff.
Value judgement rating 3
Only non-pathogenic fo-
mites were found inside
hospital.
Value judgement rating 3
Total rating
points
RELIABILITY
Machinery
Ul
O
I
Shutdowns tor as long as
30 days occurred. Many
problems with diverter
valves which required in-
stallation of new valves.
Original square collec-
tor required replacement
to reduce bag breakage.
Travel timers required
replacement several times.
No serious problems with
electrical or hydraulic
systems. Quick acting
relief valve ahead of fan
operates efficiently.
Highest amount of down-
time of all three systems
Waste bin under collec-
tor, not supplied by sys-
tem vendor, has sloping
sides which tend to
bridge and slow the drop
to the compactor. Air
valves and loading chute
door locks have required
occasional replacement.
Filter ahead of fan most
sophisticated of all
three, giving 100% pro-
tection. No serious
problems with electrical
or hydraulic systems.
Lowest amount of down-
time.
Value judgement rating 1 Value judgement rating 3
Originally had excessive
vacuum and vibration due
to bag plugs. Caused
damage to tubes, fittings,
and mounting hangers. Ex-
perienced tube collapses
and eeam ruptures. 20-
gauge metal in bends and
tube is on light side.
Lack of filter ahead of
fan has caused an un-
balanced condition and
vibration sufficient to
crack fan motor base.
Originally had freezing
weather problems with
roof dampers. Corrected
by air drying units. No
serious problems with
electrical or hydraulic
systems. Relief valve
ahead of fan least so-
phisticated Relatively
low amount of downtime.
Value judgement rating 2
-------
ELEMENTS OF
IMPORTANCE
V.A.
HOSPITAL
MARTIN LUTHER
KING HOSPITAL
ST. MARY'S
HOSPITAL
RELIABILITY (Cent.)
Personnel
Has experienced plugging
from improper loading.
This should be easy to
control since only desig-
nated people load chutes.
Has experienced cross-
over problems but this is
due mostly to faulty di-
verters rather than per-
sonnel.
Value judgement rating 1
Has experienced plugging
from improper loading.
This should be easy tc
control since only desig-
nated people load chutes.
Has experienced cross-
over problems due 100% to
operator carelessness.
Has experienced plugging
from improper loading.
This is difficult to con-
trol since many people
load chutes. Has experi-
enced cross-over problems
due 100% to operator
carelessness.
Value judgement rating 3 Value judgement rating
i
r .j
Total rating
points
MAINTAINABILITY
Corrective
train tenance
Highest amount of correc-
tive maintenance required
on this single tube sys-
tem (454 hours yearly
average). Most of this
was devoted to replace-
ment of system components
such as collectors and
diverters to decrease
number of bags breaking
and system plug ups.
Least amount of correc-
tive maintenance required
on this heavy wall two-
tube system (171 hours
yearly average). Bulk of
this was devoted to cor-
recting situations in
linen collector room and
valve rooms where vacuum
pulled plaster from
walls due to inadequate
venting.
Value judgement rating 1 Value judgement rating 3
Very close to highest
amount ot corrective main-
tenance required on this
light wall two-tube system
(424 hours yearly average).
Most of this devoted to
correcting damage to tubes,
fittings, and hangers
caused by high vacuum and
excessive vibration. Most
problems due to plug ups
resulting in replacement
of collapsed tubes and
riveting ruptured seams.
Value judgement rating 2
-------
ELEMENT OF
IMPORTANCE
V.A.
HOSPITAL
MARTIN LUTHEF
KING HOSPITAL
ST. MARY'S
HOSPITAL
i
r _
MAINTAINABILITY (Cont.)
Preventive
maintenance
and
inspections
Total rating
points
FLEXIBILITY
FOR
MODIFICATION
Devotes yearly average of
813 total hours for pre-
ventive maintenance and
inspections combined.
Part of a man's full time
is assigned on call to
continuously check system
operation. Most preven-
tive maintenance devoted
tc lubrication, clean and
changing filters, clean-
ing compactor.
VaJue judgement rating 1
Devotes yearly average of
240 hours to preventive
maintenance and 441 hours
to inspections, or 681
total hours to this cata-
gory. Most preventive
maintenance spent on lub-
rication, cleaning fil-
ters, cleaning compactor.
Devotes yearly average of
284 hours for preventive
maintenance and none tc
inspection of the system.
Most preventive mainten-
ance spent on lubrication,
cleaning dust from fan
blades, and cleaning lint
screens.
Value judgement rating 3 Value judgement rating 2
The prime modification
here could be the addi-
tion of automated "end
of the line" equipment.
Hospital is presently
modifying its system to
add a general purpose
incinerator.
This system could be
modified for automated
"end of the line" equip-
ment. Are currently
considering reduction
equipment to replace
compactor.
Value judgement rating 2 Value judgement rating 3
This system should have a
direct loading arrangement
from the collector to the
compactor to avoid possi-
ble contamination prob-
lems and to save labor.
Because of hospital limit-
ed dock facilities, will
require additional struc-
tural changes.
Value judgement rating 1
Total rating
points
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ELEMENT OF
IMPORTANCE
V.A.
HOSPITAL
MARTIN LUTHER
KING HOSPITAL
ST. MARY'S
HOSPITAL
POTENTIAL FOR
EXPANSION
Total rating
points
Not only must all expan-
sion piping be under a
vacuum to expand this
system, with much higher
fan and filter capacity,
but the electrics and
control system of a sin-
gle tube system are the
most complex of all
systems.
Value judgement rating 1
A gravity to vacuum sys-
tem is basically simpler
to expand than others.
If a wing is added to the
hospital, a relatively
simple vertical chute
could be added in the new
wing with a single hori-
zontal tube under vacuum
running to it. Addition-
al fan capacity would be
minimal.
Value judgement rating 3
To expand a full vacuum
system requires both ad-
ditional vertical chutes
and horizontal tubes, all
of which must be under a
vacuum, thus requiring
much larger fans and fil-
ters. Further, the elec-
trics of this type system
are more complex than
gravity to vacuum.
Value judgement rating 2
TOTAL RATING
1'UINTS FOR
ALL ELEMENTS
59
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As stated at the beginning of this chapter, comparisons were made be-
tween the pneumatic tube systems and the more conventional hand transport sys-
tems used by most hospitals in the United States today. The comparisons are
presented as a composite of the three pneumatic systems as compared to a com-
posite of three hand transport systems with the capability of hauling all
solid waste from the three hospitals. Where the rating elements could be
quantified, they are presented as individual values for each system, and the
average value among all the systems. In the case of narrative rating elements,
the descriptions cover the essential features of all systems in the three hos-
pitals and the ratings are assigned on the basis of value judgements.
In making this type comparison, different elements of importance must be
used than were used in comparisons between the three pneumatic systems, since
some elements are unique to pneumatic systems and are not applicable to hand
transport systems. The comparable elements of importance for this portion of
the analysis were broken down to the following:
Economics Interfacing of Components
Total costs per month Reliability
Total costs per peund Maintainability
transported User Acceptability
Total costs per cubic Environmental Acceptability
foot transported Safety
Total costs per bag Sound levels
transported Odor levels
Qualifications Required of Contamination
Transport Personnel Housekeeping practices
Speed of Clearing Floors
Certain assumptions, based on observations, were made in rating the cost
elements. First, a hand hauled cart will hold, on the average, Ib bags of
waste. The bags to receive and transport waste were actually costed out.
The cost of utilities, and depreciation of elevators, carts, and trash con-
tainers were factored. Labor includes time to empty waste containers, load
carts, walk to elevator, elevator time (including waiting), walk to compac-
tor, load compactor, return to elevator, elevator time (including waiting),
1)4-
-------
and walk to next pick-up point. The cost figures for the pneumatic systems
are based on net cost assigned to hauling waste only. A rating system of 2
for "best" and 1 for "least" is used here in a comparable manner to the 3-
point system used in the comparisons between pneumatic systems.
The matrix on the following pages presents the results of the comparisons
between the composite of the three pneumatic systems and the composite of the
three manual systems.
-255-
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ELEMENT OF IMPORTANCE
PNLUMAIIC VS. HAND SYSTEMS COMPARISON MATRIX
PNEUMATIC SYSTEM HAND SYSTEM
i
ro
CT-
I
ECONOMICS
Total individual costs
per month
Average value
Rating
Total individual costs
per pound
Average value
Rating
Total individual costs
per cubic foot
Average value
Rating
Total individual costs
per bag
Average value
Rating
$3,449 to $5,052 to $6,568
$5,023
2
$ 0.10 to $ 0.13 to $ 0.15
$ 0.13
1
$ 0.22 to $ 0.30 to $ 0.30
$ 0.27
$ 0.41 to $ U.53 to $ U.77
* 0.57
1
$6,358 to $7,368 to $8,474
$7,400
1
$ 0.05 to $ 0.08 to $ 0.09
$ 0.07
$ 0.16 to $ 0.24 to $ 0.37
$ 0.26
2
$ 0.30 to $ 0.36 to $ 0.54
$ 0.40
Total rating points
QUALIFICATIONS REQUIRED
OF TRANSPORT PERSONNEL
Rating
7
Requires minimal training to
learn routine of making rounds
and unlocking chute door, or
randomly loading an unlocked
chute.
Requires considerable training
and experience to learn routine
and accomplish rounds efficiently
and without interference.
SPEED OF LOADING AND
CLEARING FLOORS
Average value
Rating
Waste bags can be cleared from
patient and ancillary areas much
faster than by cart. Requires
441 hours to 462 hours to 534
hours per month to clear floors
and load chutes.
479 hours
Carts are bulky yet handle per
hour much less waste in vertical
transport than chutes. Requires
1,355 hours to 1,359 hours to 1,871
hours per month to clear floors,
haul to compactor, and return.
1,528 hours
1
-------
ELEMENT OF IMPORTANCE
PNEUMATIC SYSTEM
HAND SYSTEM
INTERFACING OF
COMPONENTS
Rating
RELIABILITY
Hating
MAINTAINABILITY
Individual values
Average values
Rating
Systems are enclosed and complete
with an air gap at compactor, ex-
cept one which is complete to
compactor, then hand hauled to
compactor.
2
System is completely open to the
compactor, except that waste is
encapsulated in plastic bags.
All systems experience plugging
and shut downs, one system down
for as long as 30 days. Lack of
fan air filter in one system has
caused dust build-up and vibra-
tions in fan sufficient to crack
motor mount. 20-gauge metal in
some tubes is borderline, con-
tributing to tube collapse.
1
Averages 171 hours to 424 hours
to 454 hours per year for correc-
tive maintenance. Averages 284
hours to 681 hours to 813 hours
per year for preventive mainten-
ance and routine inspections.
One system has no routine inspec-
tions.
Corrective, 350 hours
Preventive and inspections, 593
1
Reliability affected only by
availability of personnel to
push carts and operation of one
elevator.
Requires cleaning of carts plus
routine inspections and main-
tenance of elevator at 150 hours
per year.
150 hours
2
-------
ELEMENT OF IMPORTANCE
PNEUMATIC SYSTEM
HAND SYSTEM
USER ACCEPTABILITY
i
i ^
Iwf
ex
Value judgement rating
ENVIRONMENTAL
ACCKI'TA^JLITY
Sound levels
Average values
Rating
Odor levels
Value judgement rating
Contamination
Value judgement rating
Trustability factor is low for two
systems, relatively nigh fcr the
third. Low factor due to slowness
of system in one case, requiring
much waiting time to load, and in
the other due to many cast-s of
waste and laundry nags crossing
over. High factor due to easy and
fast loading,
1
Trustability factor medium to
high since the system will work
Esthetic value rating meciuin.
Creates tratfic problems and
noise in the corridors.
Average roaximums ranged from 63
dB(A) to 69 dB(A) to 77 dB(A) in
corridors outside chute loading
rooms. Overall average value per
hospital ranged fruin 60 db(.A) to
62 dB(A) to b5 dB(A) in the corri-
dors outside chute loading rooms.
Maximum level 70dB(A)
Average level o2 d!3(A)
Odor, if any, as measured in cor-
ridors, coming from chute loading
rooms, is low but when present is
persistent.
1
No dangerous contamination noted
inside hospitals attributable to
pneumatic systems. The risk is
lower inside patient areas.
2
Averages 5-10 dB(A) above sound
of chute loading stations, meas-
ured in corridors.
Maximum level 77dti(A)
Average level o9 dB(A)
1
Odor, i! any, coming from a
waste cart is transient. (This
assumes all waste is transported
in tied or sealed bags.)
2
The risk is higher due to exposed
conditions in carts and longer
contact of bags witii carts.
-------
ELEMENT OF IMPORTANCE
-NEUMA1IC
HAND
ENVIRONMENTAL
ACCEPTABILITY
Housekeeping practices
Value judgement rating
Total rating points
SAFETY
Value judgement ratinp.
TOTAL kATlNi; FOINTS
FOR ALL ELEMENTS
Bag breakage and waste spread
vithiti pneumatic system is con-
fined. Negative pressure leads
odory and contamination to fan
and filter.
brec?ka&e in cart loading and
within carts can spread aerosols
through Hospital corridors.
Theoretically carts should be
cleaned after each trip if
breakage or leakage occurs.
1
No hazardous or unsafe conditions
were found, except high noise
levels in all fan rooms and, in
or,e hospital, a physically haz-
ardous condition to n.aintenance
personnel in slidf valve roorc.
Potential safety hazard to
pedestrians and wheel chair
patients in corridors and
elevators.
21
COMPARISON RATING SUMMARY
PNEUMATIC VS. PNEUMATIC
V.A. M.L.KINC ST. MARY'S
HOSPITAL HOSPITAL HOSPITAL
PNEUMATIC VS.
PNEUMATIC
SYSTEM
HAND
HAND
SYSTEM
Overall total rating
points
59
41
21
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SUMMARY OF SYSTEMS RATINGS AND COMPARISONS
As stated earlier in this chapter, the previous comparisons and ratings
were based on both quantitative and qualitative factors. Some were.based on
audit of cost and labor figures, measurements and physical testing, and some
by value judgments based on qualified observations, past experience, and
interviews on site. Based on this, it is our conclusion that, after comparing
and evaluating the three pneumatic systems with one another, the heavy-wall,
two-tube, gravity to vacuum system at Martin Luther Ring is the "best" system,
even though it is the most expensive. The thin-wall, two-tube, full vacuum
systems at St. Mary's Hospital was judged to be "second best," when compared
and evaluated with the other penumatic systems. The thin-wall, single-tube,
full varuuc system at Veterans Administration Hospital was judged "third best"
when compared and evaluated with the other pneumatic systems.
The composite of the three pneumatic systems, compared to the composite
cf three hand systems, was judged slightly "better" overall, even though
they rated lower in the economic factors. This is due primarily to the higher
ratings of the pneumatic systems in environmental factors and speed and clear-
ing cf floors.
The pneumatic solid waste handling systerj at Martin Luther King Hospital
was significantly more expensive to install than the other two pneumatic
systems. It thus appears that this is a case of higher installation cost
being justifiable in order to achieve other advantages and help meet the goals
of improving the internal environment of the institution.
-260-
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A GLOSSARY OF TERMS APPLICABLE TO SOLID WASTE MANAGEMENT
IN
HEALTH CARE FACILITIES
AN DIAL ViASTE - Waste generated from animal care or use; including secre-
tions, tissue, remains, droppings, bedding for cages (such as sawdust, etc.).
BAGGING - The deposition of solid waste in a paper or plastic bag for
storage or transport.
BIODEGRADABLE - Waste material which is capable of being broken down by
bacteria into basic elements. Most organic waste, such as food remains and
paper, is biodegradable.
BIOLOGICAL WASTES - Waste contaminated with or made up of animal or plant
tissue, secretions, remains, droppings, or other elements.
CHARGE - The quantity of solid waste introduced into a furnace at one
time.
CHEMICAL WASTES - Any cnemical or mixture cf chemicals which require
special consideration for disposal.
CLASSIFICATION - To arrange or sort waste materials into uniform cate-
gories or classes. Usually implies accurate grading by organic, inorganic,
size, weight, color, or shape, etc.
COLLECTION - The act of removing solid waste from a storage point.
COLLECTION CENTER - A place or facility designed to accept waste materials
from individuals or mechanical devices (such as conveyors, carts, or transport
tubes). The term can also be used to mean a central receiving point for waste
material collected by a government cr private agency.
COMBUSTIBLES - Various materials in the waste stream which are burnable.
In general, these are organic in nature: paper, plastics, wood, and food
wastes.
COMPACTOR - Any power driven mecnanicaj. equipment designed to compress
and thereby reduce the volume of waste materials.
-------
CONTAINERIZE - The deposition of sclid waste into metal, plastic, or
other containers for storage or transport.
CONTAMINATED WASTES - Waste which has been soiled, stained, corrupted, or
infected by contact, association, or use.
DISINFECTION - Killing of infectious agents outside the body by chemical
or physical means directly applied.
DISPOSABLE - A product intended for single or limited use before being
discarded.
DISPOSAL - The orderly process of discarding useless or unwanted material.
DUMP - An open land site where waste materials are burned, left to decom-
pose, rust, or simply remain. Ln most localities, dumps are being phased out
because of the problems which they cause, such as water pollution, creation of
unsanitary conditions, and general unsightliness. Some dumps are left burning
as waste is accumulated. This practice does not lend itself to control, and,
therefore, very little of the waste is actually consumed by fire. The burning
also generates obnoxious smoke, fumes, and ash particles.
ECOLOGY - The science that deals with the interrelationships of organisms
and their living and non-living surroundings.
ECOSYSTEM - The interdependence of organisms and their surroundings.
EMISSIONS (GASEOUS) - Waste gases released into the atmosphere as the
product of combustion.
ENVIRONMENT - The air, the water, and the earth, sometimes called the
biosphere. Alternatively, homes, institutions, and other places of residence
or work.
ENVIRONMENTAL SYSTEM - The interaction of an organism or group of organ-
isms with its natural and tuanmade surroundings.
FOMITE - Inanimate objects such as clothing, dishes, toys, books, that
may be contaminated with infectious agents and serve in their transmission.
FOOD WASTE - Animal and vegetable waste resulting from the handling,
storage, sale, preparation, cooking, and serving of food; commonly called
garbage.
GARBAGE - Waste materials which are likely to decompose or putrefy. Usu-
ally contain food wastes from a kitchen, restuarant, grocery store, slaughter
house, or food processing plant.
- /-I -II-
-------
GRINDING - The mechanical pulverization of solid waste.
HAUL DISTANCE - (1) The distance, a collection vehicle travels from its
last pickup stop to the solid waste transfer station, processing facility, or
sanitary landfill. (2) The distance a vehicle travels from a solid waste
transfer station or processing facility to a point of final disposal. (3) The
distance that cover material must be transported from an excavation or stock-
pile to the working face of a sanitary landfill.
HAUL TIME - The elapsed or cumulative time spent transporting solid waste
between two specific locations.
HAZARDOUS WASTE - The waste from a hazardous material: which is any ele-
ment, compound, or combination thereof, that is flammable, corrosive, deton-
able, toxic, radioactive, an oxidizer, an etiological agent, or is highly re-
active, and that because of handling, storing, processing, packaging, or trans-
porting may have detrimental effects upon operating and emergency personnel,
equipment, the workplace, or the environment. Waste which requires special
handling to avoid illness or injury tc persons, or damage to property.
INCINERATION - The controlled process by which solid, liquid, or gaseous
combustible wastes are burned and changed into gases and the residue produced
contains little or no combustible material.
INCINERATOR - An engineered apparatus used to burn waste substances and
in which all the factors of combustion—temperature, retention time, turbu-
lence, and combustion air—can be controlled.
INCINERATOR RATED CAPACITY - The number of tons of solid waste that can
be processed at an incinerator per 2A-hrur period when specified criteria pre-
vail. Alternatively, the pounds per hour that can be burned.
INFECTED PERSON - Infected persons include both individuals with manifest
disease and those with inapparent infection.
INFECTION - The entry and development or multiplication of an infectious
agent in the body of mar. or animal. Infection is not synonymous with infec-
tious disease; the result may be inapparent cr manifest. The presence of liv-
ing infectious agents on exterior surfaces of the body or upon articles of ap-
parel or soiled articles is not infection, but contamination of such surfaces
and articles.
- -111-
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INFECTIOUS AGENT - An organism, mainly microorganisms (bacterium, proto-
zoan, spirochete, fungus, virus, rickettsia, bedsonia, or other) but including
helminths, capable of producing infection or infectious disease.
INFECTIOUS DISEASE - A disease of man or animal resulting from an infection.
INFECTIOUS WASTE - Waste originating from the diagnosis, care, or treatment
of a person or animal which has been, or may have been, exposed to a contagious
or infectious disease.
INSTITy'ri_ONAL__WA_STE - Waste originating from educational, health care, re-
search, and similar institutions.
ISOLATION WASTE - Waste originating from the diagnosis, care, or treatment
of a patient placed in isolation because o£ a known or suspected infectious
disease.
JUNK - Unprocessed materials suitable for reuse or recycling.
LABORATORY WASTE - Waste generated through the activities of the laboratory
which may be innocuous, hazardous, or infectious, solids, or liquids.
MANUAL SEPARATION - The separation of waste materials by hand. Sometimes
called hand picking, manual separation is done in the home or office by keeping
garbage separate from newspapers, or in a recovery plant by picking out large
cardboard or metal objects.
MANURE - Primarily the excreta of animals; may contain some spilled feed
or bedding.
MEDICALLY CONTAMINATED WASTE - Waste originating from activities associated
with patient diagnosis, care, or treatment. Also medical waste.
MILLED REFUSE - Solid waste that has been mechanically reduced in size by
the grinding, or pulverizing, or bannering action of an attrition mill, "hogg,"
or dry grinder.
MOISTURE CONTENT (SOLID WASTE) - The weight loss (expressed in percent)
when a sample of solid waste is dried to a constant weight at a temperature of
100 C to 105 C.
OPEN BURKING - Uncontrolled burning of wastes in the open or in an open
dump.
PATHOGEN - An organism capable of producing disease.
-------
PATHOGENIC WASTE - Waste contaminated with an organism capable of produc-
ing disease.
PATHOLOGICAL WASTE - Tissues, parts, and organs of humans and animals.
PNEUMATIC COLLECTION (SOLID WASTE) - A mechanical system for conveying
solid waste through transport pipes. When the system is in operation, a vacuum
is developed and a high velocity air stream is drawn through pipes. Waste,
which is dropped into this moving air stream, is carried to a collection point.
POLLUTION - The condition caused by the presence in the environment of
substances of such character and in such quantities that the quality of the
environment is impaired or rendered offensive to life.
POLYVINYL CHLORIDE (PVC) - A common plastic material that releases hydro-
chloric acid when burned.
PYROLYSIS - The chemical decomposition of a material by heat in the ab-
sence of oxygen.
RADIOACTIVE WASTE - Waste contaminated with a substance which emits ion-
izing radiation.
RECLAMATION - The restoration to a better or more useful state, such as
land reclamation by sanitary landfilling, or the obtaining of useful materials
from solid waste.
RECOVERY - The process of obtaining materials or energy resources from
solid waste. Synonyms: Extraction, Reclamation, Salvage.
RECYCLING - The process by which waste materials are transformed into new
products in such a manner that the original products may lose their identity.
REFUSE - A generally used term for solid waste materials.
RESIDUE - Material that remains after gases, liquids, or solids have been
removed.
REUSE - The use of a waste material or product more than once. For ex-
ample, a soft drink bottle is reused when it is returned to the bottling com-
pany and refilled.
RUBBISH - A general tenu for solid waste—excluding food waste and ashes—
taken from residences, commercial establishments, and institutions.
SALVAGE - The utilization of waste materials.
-------
SANITARY LANDFILL - A site where solid waste is disposed using sanitary
landfilling techniques.
SANITATION - The control of all the factors in man's physical environment
that exercise or can exercise a deleterious effect on his physical development,
health, and survival.
SCRAP - Waste material which is usually segregated and suitable for re-
covery or reclamation.
SEPARATION - The systematic division of solid waste into designated cate-
gories; e.g. removing glass containers, metal cans, etc. from general waste.
SHREDDER - A mechanical device used to break up waste materials into small-
er pieces. The pieces are usually in the form of irregularly shaped strips.
SOLID WASTE - Useless, unwanted, or discarded material with insufficient
liquid content to be free flowing.
SOLID WASTE DENSITY - The number obtained by dividing the weight of solid
waste by its volume.
SOLID WASTE MANAGEMENT - The purposeful, systematic control of the gener-
ation, storage, collection, transport, separation, processing, recycling, re-
covery, and disposal of solid wastes.
SOURCE OF INFECTION - The thing, person, object, or substance from which
an infectious agent passes immediately to a host.
SPECIAL WASTE - Waste that requires extraordinary management.
STERILIZATION - The destruction, by chemical or physical means, of a
microorganism's ability to reproduce; to render something barren.
STORAGE^ - The interim containment of solid waste, in an approved manner,
after generation and prior to ultimate disposal.
SURGICAL AND AUTOPSY WASTE - Waste that includes tissue, limbs, organs,
placentas, and similar types of materials.
TOXIC WASTE - Waste contaminated with any substance which has the capacity
to produce personal injury or illness to man through ingestion, inhalation, or
absorption.
TRANSFER STATION - A site at which solid waste is concentrated and then
taken to a collection center of a processing facility.
TRANSPORT - The movement of solid waste subsequent to collection.
- p. -VI-
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TRASH - (Same as Rubbish) - A general term for solid waste—excluding
food waste and ashes—taken from residences, commercial establishments, and
institutions.
VOLUME REDUCTION - To process waste materials so as to decrease the amount
of space the materials occupy. Complete conventional incineration can reduce
volume by 90 percent while high temperature incineration achieves as much as
98 percent. Compaction systems can also reduce volume by 50 to 80 percent.
WASTE - The useless, unwanted, or discarded materials resulting from nor-
mal community activities, including solids, liquids, and gases.
WASTE GENERATION - The act or process of producing solid waste,
WASTE PROCESSING - An operation such as shredding, compaction, composting,
and incineration, in which the physical or chemical properties of wastes are
changed.
WET PULPING - The mechanical size reduction of solid wastes that have been
wetted to soften the water absorbing constituents (such as paper and cardboard).
/9 -vii-
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