company during the last year from the Home Farm. Of the 2,276 hogs sold,
the Commission says only 11 were condemned by the United States
Government Meat Inspectors, an average of only 0.48 per cent. of one per
cent., which average is much lower than it is on hogs shipped in from
the West to the same packing house. It further says: “The feeding
method, however, has been practised with success in many cities,
especially those in New England, for many years. The great difference of
opinion is explained by the efficiency with which the sanitary
conditions at the farm are maintained.” It emphasizes the fact that
farms must be kept clean and in a sanitary manner, and that this method
of garbage disposal requires careful and intelligent supervision, as is
the case with any other method of disposal. No method of disposal will
run itself.
Following are comments received regarding this particular plan of
disposal:
Health Officer C. C. Slemons, of Grand Rapids, Michigan, says: “From
observation I am of the opinion that one of these farms (municipal
piggery), properly conducted, is a paying proposition, but I do not
think to the extent of paying for collection. From my observation I
would be rather skeptical of a city going into this business. It is a
business that needs very close supervision and unless a person is
financially interested in it I doubt very much if the experiment would
pay.”
Mayor Fred. W. Keller, South Bend, Indiana: “Some of this work was done
several years ago. However, there was some objection on the part of
taxpayers to it being hauled out of the city with municipal teams. It
should be fairly profitable, but the farm and hogs should be owned by
the city or the garbage disposed of to the concern that does own the
hogs and farm and this done by receiving competitive bids. I make this
latter suggestion in order to avoid criticism by taxpayers.”
Lawrence, Massachusetts, reports: “Those who have looked into this
question contend that the city swill can be utilized to support a
municipal piggery at considerable profit.”
In a recent report, the Iowa State College says of this method of
disposal: “The only advantage which may be stated in favor of this
method is that it probably costs less, under existing conditions about
most of our cities, than any other available method.”
In one of its annual reports, the Massachusetts State Board of Health
says: “It is objectionable and unsanitary in the extreme, as health
authorities are constantly pointing out. Prominent among the objections
to this method are the great nuisance it usually creates and the
uncertainty of its operation.” The Board says epidemics among pigs
create the uncertainty of operation. It also says that they are breeding
places for flies and rats.
The Chicago Waste Commission’s comment on this method is that it is not
applicable or desirable in a large city, except under inspection and for
restricted private collection.
The _New York Medical Journal_ reported that the garbage collected by
Grand Rapids, at cost of $26,320, is taken by a contractor who last year
paid 45 cents per ton and fed to hogs. It says that over 10,000 hogs are
sold yearly at a value of $135,000 and that 2,400 tons of fertilizer are
produced at a value of about $36,000.
Samuel A. Greeley, Sanitary Expert, says that 75 pigs are required to
dispose of a ton of garbage per day. The equipment at the farm
prescribed by him is: Tracks and cars for distributing the garbage along
concrete feeding platforms; substantial and well-kept sleeping and
warming pens; tanks for sterilizing garbage; apparatus for vaccinating
pigs against cholera; a means of disposing of unconsumed garbage by
burial or incineration and plenty of washing facilities. He further
says: “There should be some method of sorting the garbage before feeding
it to pigs so that the stale garbage may be discarded and buried or
burned. Some places disinfect it by boiling in large caldrons before
feeding. In such cases the cooked garbage is commonly used only as a
base for the feed given to pigs. The method is a most profitable one and
warrants consideration in small cities where isolated farm sites are
available.”
Dumping on Land
It is the consensus of opinion in all reports and of all experts that
this method is objectionable especially where there is a large quantity
to be disposed of. A long haul is necessitated by the location of the
dumps at a remote distance where the decomposition of any part of the
refuse will not be offensive to neighboring property owners. When the
garbage is deposited in sufficient quantity offensive odors due to
fermentation and decomposition may create a nuisance. Unless special
attention is given to the treatment of these dumps, this method will not
be found desirable. A thorough mixing of garbage with ashes and rubbish
will prevent the nuisance and the fires that are otherwise liable to
occur, creating odors and nuisance from the smoke and unconsumed gases.
A report of the Iowa State College states that dumps where ashes and
rubbish and other refuse are deposited are not only unattractive in
appearance, but are detrimental to the health of those living in the
immediate vicinity, and as a city grows, it usually becomes increasingly
difficult to find locations where these dumps can be maintained without
incurring the objections of those living in the neighborhood.
The _Scientific American_ says this method “is one that cannot be
defended either from an æsthetic or sanitary standpoint. The dumps
become an ideal breeding place for flies.”
Dumping in Large Bodies of Water
Only a few cities use this method. In most places where it has been
tried, it has been prohibited because the material is washed on the
neighboring shores.
Disposal by Sanitary Fill
This method is practised by some cities, among them Seattle, Davenport,
and New Orleans, which report its success. It is given more serious
consideration than heretofore by several large cities. The method is
different than that of burial, in that it is carried on by filling
excavations, vacant low lying ground and natural ravines.
The garbage, rubbish and ashes are dumped and then mixed with sufficient
earth to insure oxidation and thorough digestion of the decomposable
wastes. The activity of the bacteria of the soil breaks down and
mineralizes the organic matter and when there is sufficient oxygen, i.
e. air, no putrefaction or other odors result. Success depends upon the
following treatment:
(1) The garbage must not be buried so deep that bacterial activity is
reduced.
(2) The garbage must not be spread in a thick layer on the surface of
the ground.
(3) The ground must be sufficiently open and drained so that air can
penetrate to a sufficient depth.
(4) The garbage must not overload the soil, but must be sufficiently
diluted with earth, ashes and rubbish, so that putrefaction may take
place, due to the presence of an ample supply of air in the pores of the
soil.
The Chicago Waste Commission believes that this method “has been
demonstrated to be not only sanitary, free from nuisance when properly
carried out, but economical as well.” Incidentally, adds the Worcester
Commission, it adds valuable taxable property from which the city
subsequently derives an income.
At Davenport, 1.3 cubic yards of materials are required per ton of
garbage and the total cost of upkeep, including rent of land, labor,
etc., was 50 cents per ton. The garbage is received and buried by one
foreman and three men in summer and one foreman and one man in winter.
The city by this method is creating a valuable river front.
New Orleans seeds its dumping grounds as soon as a sufficient filled
area is available, and later trims and plants the land for use as small
parks and play grounds.
The Health Commissioner of Seattle, in a letter to the _Municipal
Engineering Journal_, describes the system and results as follows:
“This method of filling works very satisfactorily in this climate, but I
believe it necessary to include all waste materials, as ashes, boxes,
tin cans, etc. These all assist oxygenation and nitrification. I do not
believe pure garbage can be handled in this way.
“We also find that it is best to keep as little of the face of the fill
exposed as possible. It is always best to keep a man constantly on the
job, whose duty it is to rake down to the bottom of the fill all boxes,
rough materials, etc., thus leaving the ashes to form a covering on top.
When this is not sufficient, we cover with a layer of earth about five
inches thick.
“The success lies in the proper mixtures of waste materials, and next
the fill must be properly covered to protect from flies. Chemicals can
also be used to protect it. This covering also prevents the slight sour
odor of fresh garbage and by keeping out the sunlight, at the same time
encourages bacterial growth by increasing the warmth inside the fill.
People residing within one hundred feet of these fills make no
complaint, but the public has to be educated when you first adopt this
method. We aim to fill city property, as ravines, swampy lands or docks
on the lake or salt water front.
“Our laboratory findings show that the process is simply one of slow
incineration by nature, instead of the expensive method of burning by
incinerators, and at the same time help prove that there is nothing
detrimental to public health in these fills.
“We have eleven fills distributed over our city, thus making short
hauls, and these are taken care of by eleven laborers disposing of
approximately three hundred and fifty tons per day by this method alone,
while one incinerator with about an equal payroll will only dispose of
sixty to seventy-five tons per day, running twenty-four hours. A fill
increases the value of property, while the refuse from our incinerator
has to be hauled away at an added cost.”
After spreading, there is applied to the garbage an antiseptic spray of
crude carbolic acid, rosin and caustic soda to kill eggs and larvæ of
flies, mosquitoes and other insects that might breed.
Burial
Garbage may be buried by putting it in shallow trenches and covering
with the excavation from the trenches for the next day’s deposit, or by
plowing under. It digests and is thoroughly taken up by or oxidized by
the action of the soil. Experience has shown that for open soil 1.5
acres are required to handle each daily ton of garbage for one year, the
same soil being in shape to re-use after two years. For heavy soils and
those containing clay, about three acres are required and this can be
used again after three years.
The Worcester Commission reports that cities which have buried by
plowing have experienced more than occasional nuisance. Milwaukee and
Columbus successfully disposed of their garbage by burying in trenches,
before they constructed disposal plants. Milwaukee paid forty cents a
ton to dispose of its garbage by this method.
A summary of the opinions indicates that disposal by burying when
properly conducted and when the point of disposal is suitably located
gives no cause for objection from a sanitary standpoint. The principal
objections are the extremely long haul, the amount of land necessary and
no direct income. In small communities this method is entirely
satisfactory. It is usually not applicable to large communities.
Disposal Plants
There are two methods of disposing of garbage in plants—incineration and
reduction. There is a wide diversity of opinion among experts and city
officials as to which is the better from a sanitary and financial
standpoint. There is, however, nearly universal opinion upon the
following:
1. That the revenue from the by-products of municipally owned and
operated plants will not pay the combined cost of collection and
disposal.
2. That with only a few exceptions the revenue from the by-products of
municipally owned plants does not pay the cost of disposal.
3. That the price received by cities from contractors is, with very few
exceptions, not sufficient to pay the cost of collection.
4. That the disposal of garbage by the reduction process is uneconomical
for a city with a population of less than 100,000. Some experts increase
the size to 150,000 and one to 200,000.
5. That incineration is better than reduction for a city with a
population less than 100,000.
The reduction in the per capita production of garbage, due to less
wastage of food in the American home since the war, may make it
necessary in the future to increase the size of the city which can
profitably employ the reduction method, or should use the reduction
method.
In the report of the Chicago Waste Commission, some general rules are
laid down for the design of a disposal works, irrespective of method. It
says that the design should permit the plant to be operated as a whole,
or in part, so that each part can be operated as an independent unit.
This will permit one or more parts to receive attention and be repaired
during the season when the minimum quantity of refuse is to be disposed
of. The details of the plant should be such as to permit cleanliness at
all times and hosing and washing so as not to permit garbage dust or
dirt to accumulate, flies to breed and material to decompose. All
material, so far as possible, should be enclosed during the process of
disposal, and the odors eliminated or confined or deodorized. The
handling of material in the plants, so far as possible, should be
eliminated, where mechanical means can economically be adopted. Special
attention should be paid to ventilation and the elimination of dust
where men are required to work.
The odors or nuisances caused from disposal plants will usually arise
from one or more of the following sources: Garbage or refuse, incomplete
combustion or combustion temperatures not sufficient to eliminate odors,
congestion of carts in one locality and creation of dust. The odors
arising from raw garbage which are found in all plants are mostly local
and will not create a nuisance a short distance from the point of
handling and the housing of equipment used in hauling.
A method of determining the kind of a plant to be built and operated
which will meet with local conditions is described as follows by Rudolph
Herring, sanitary engineer.
“Locate suitable central points where incinerators can be built
convenient for reception of refuse and delivery of steam and clinker.
Estimate annual cost, including fixed charges and operation, as follows:
First, of wagons and other means of collecting from house to works all
garbage, ashes and rubbish combined; and, second, of the works for
incineration. The sum of these two estimated costs will give probable
annual cost of entire plant from origin to finish. This sum must then be
credited with the annual value of steam and clinker. The result will be
the net annual cost to the city of collecting and finally disposing of
the above parts of general refuse.
“A. Locate suitable place where reduction process can be carried on
economically and conveniently for reception of garbage and delivery of
products, with a capacity to serve, if practicable, the entire city.
Estimate annual cost, including fixed charges and operation, as follows:
First, of wagons and other means of collecting the garbage from house to
works; second, works for reduction. The sum of these two estimated costs
will be the probable annual cost to the city of the collection and
reduction of the garbage. This sum must be credited with annual value of
products of reduction, as derived from sale of oils, grease and
fertilizers. The result will be the net cost, perhaps profit, of
disposing of city garbage.
“B. Locate suitable central point where incinerator can be built, which
will be convenient for the reception of ashes and rubbish and the
delivery of steam and clinker. Estimate annual cost, including fixed
charges of operation as above of the collection and works for disposal
of ashes and rubbish, if these are to be incinerated together.
“If only rubbish is to be collected and delivered for incineration, then
there should be added the cost of collection and final disposal of ashes
by dumping. This cost should again be credited with annual value of
steam and clinker and perhaps of land-making by dumping of ashes.
“By adding results of A and B, we obtain the total net cost to a city of
collecting and finally disposing of the above parts of general refuse. A
comparison between these estimates of cost, of both collection and
incineration of garbage, ashes and rubbish as one project and of both
collection and reduction of garbage and the collection and incineration
of rubbish and dumping of ashes as the other project, will indicate the
most economical method in the city for which these cost estimates have
been made. It is necessary to analyze carefully local conditions to
determine the most economical method.”
Incineration
Two kinds of plants are used for this method of disposal—crematories and
destructors. Many destructors are in operation in America, but of the
crematories which have been built, many have been abandoned. Heat for
destruction must be obtained not only from the garbage itself, but also
from ashes and other combustible waste. It is here that the difference
between destructors and crematories enters. In the former, heat is
obtained from the refuse itself; in the latter, garbage is burned at the
expense of coal, wood or oil. It seems to be the prevailing opinion that
in order to make incineration a success the material must be burned at a
high temperature and rapid rate of combustion.
Morse claims that destructors require twenty per cent. less area of
ground, cost fifteen per cent. more for boiler and machinery; that the
construction is more durable; no addition of fuel; that the gases of
combustion are consumed, and that this method has by-products of clinker
and power and destroys all combustible refuse; and that the net cost of
operation is less per ton.
Crematories, Morse says, require more ground and more time for disposal,
but cost less. They are less durable, require addition of fuel, gases
are incompletely destroyed, cannot develop power, the residue has no
value and they can burn only garbage and rubbish. The gross cost of
operation is a trifle less, but the net cost is more.
Tests of garbage crematories in Ohio, according to the State Board of
Health, show that “the plants as operated fail usually to dispose of the
garbage at a temperature high enough to avoid the production of odors.”
This, says J. T. Fetherston, Commissioner of Street Cleaning of New York
City, is significant and conclusive.
Regarding mixed refuse destruction, Fetherston says: “Three features may
be noted: No added fuel is required, steam power is produced and quite a
residue (clinker) results. Compared with tests of garbage crematories
the average destructor temperatures in connection with the gas analyses
indicate freedom from odor due to unconsumed gas. Thus the mixed refuse
type of plant corrects the inherent defects of the garbage crematory.”
The cost of incineration plants depends upon the garbage to be handled.
The various incinerator companies usually estimate the capacity of the
plant at about one ton per 1,000 population.
Reports show that disposal by incineration in Ohio is confined to cities
of from 20,000 to 80,000 population, and that its success has been
confined to the very large and to the rather small cities of the
country. Some assert that it is applicable in the very large cities only
when the collection systems are suitable to provide for the burning of
mixed refuse. In small cities it is the custom to cremate the garbage
alone, the other classes of waste being dumped or buried.
The cost of construction, reports show, ranges from $600 to $1,000 per
ton capacity. The Worcester Special Waste Commission says that “from a
calculation based on some 30 incinerators it has been found that the
cost per ton daily capacity varies from $250 to $1,000, the average
being between $600 and $700.”
The by-products are clinker and the steam generated.
Robert W. Wylde claims that the cost of operating destructors “is in a
great measure offset and frequently quite overbalanced by the revenue”
from the sale of steam and clinker. One hundred tons of refuse burned
during 16 hours a day produces 800 engine H. P. Clinker from 100 tons
might amount to 30 tons per day and would bring $1.00 a ton in many
localities. Another expert says that one pound of refuse has been found
to produce one-half to one and three-fourths pounds of steam. The value
of refuse as a fuel is estimated by one expert to be 49 cents per ton.
The Chicago Waste Commission’s report points out, “that experience in
connection with the development of power from refuse furnaces
demonstrates that it is not easy to find an available use whereby the
power can be utilized regularly as produced and the furnace operated
continuously. In the majority of plants constructed, it has not been
possible to utilize all the power available, and in most cases the use
is limited to the operation of the plant. When power developed is used
in lighting and power stations, the demand only comes during a part of
the day. Supplementary coal-fired boilers are usually found in
connection with destructor-electric lighting stations, or else the
destructor is much larger than would be required to deal with the refuse
alone. The power produced from refuse furnaces will be best utilized by
some local industry, such as ice-making plants or electro-chemical
plants, which require continuous operation. When power is used in
connection with pumping plants, it is found good practise to operate the
refuse plant only as an auxiliary to the power plant of the pumping
station. The saving that results or credit that can be given the
destructor plant will amount to the value of the fuel equal to that
which it requires to produce the amount of steam developed and used. The
fluctuating amount of power developed in most cases can be depended upon
only for the average minimum production. In selecting a site for a
refuse disposal plant from which power is developed it is not always
profitable to utilize the power where the demand is not constant and
where the demand would be constant, suitable sites are not always
available.”
William M. Venable, sanitary engineer, believes that if a city has a
steam power plant, it will pay, but it will not pay to build one for
that purpose.
In a suburb of Montreal, the refuse destructor is constructed in
connection with a municipal electric light power station and power is
used in generating electricity for lighting purposes. The plant is
operated only during the time when lighting load is in demand, and the
material as delivered is stored during the day and burned at night. Only
a part of the power is furnished by the refuse furnaces, the remainder
being obtained from a coal-fired boiler plant.
In Savannah, Georgia, the water works boilers are kept in service, with
banked fires, to use in case of shortage of garbage.
The following are some of the reports from cities which receive a
revenue from by-products:
Minneapolis: The steam generated lights and heats hospital and workhouse
buildings, also lights 31 miles of streets. Estimated annual revenue,
heat $6,293.89; light $1,080.62; street lights ($60 per arc) $4,657.48;
total, $12,031.99.
Borough of Richmond, New York City: West New Brighton incinerator uses
clinker in manufacture of brick by mixing cement with ground clinker.
New Orleans, La.: Plans perfected to light streets and public buildings.
Claimed that from 500 tons of garbage daily 30,000,000 K. W. can be
generated a year.
Savannah, Georgia: Ninety-five per cent. of coal fuel previously used at
pumping station is now saved by destructor. To operate water works
pumping station it cost $81.90 per day. To operate the station and
destructor it costs $46.50 per day, or a difference of $12,921 per year,
this being 10 per cent. of the cost of the plant. This is expected to
provide for repairs and amortization charges. Besides, the city has all
of its refuse disposed of without cost at a central point and in a
sanitary manner with freedom from nuisance. The clinker is used for road
building and is estimated to have a value equal to the cost of hauling
it from the plant.