First United States
Conference on
Municipal Solid
Waste Management
Solutions for the 90s
Proceedings
Volume II
June 13 -16, 1990
(Wednesday p.m. - Saturday p.m.)
Ramada Renaissance Tech World
Washington, D.C.
Sponsored by
The U.S. Environmental
Protection Agency
Office of Solid Waste
S-EPA
Printed on recycled paper
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RECYCLING AND
COMPOSTING
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ADVANCES IN COLLECTING PLASTICS
Janet Keller
RI Department of Environmental Management
Presentated at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
491
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Acknowledgment
Much of the material in this paper was presented at the
American Institute of Chemical Engineers Conference in San
Francisco in November 1990. Partial funding for the original
presentation and paper was provided by the Center for Plastics
Recycling Research at Rutgers University.
492
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ADVANCES IN COLLECTING PLASTICS
INTRODUCTION
Plastic soda bottles and milk jugs are increasingly common
components of municipal' recycling programs, and recyclers are
examining the feasibility of recycling different types of plastics
such as colored HDPE bottles and other rigid plastic bottles.
However, it is still unclear whether plastics, with their low
weight to volume ratios, are cost effective to recycle. Thus,
there has been much interest in methods to densify plastic
materials onboard recycling vehicles. This paper discusses
curbside collection costs, evaluates several on-truck systems for
densifying plastics and concludes that perforator compactor systems
warrant further study.
IMPACT OF PLASTICS ON RECYCLING SYSTEMS
The low density of plastics and the high number of serving
units involved can raise the costs of collecting, sorting and
processing plastics. And although plastic soda bottles and milk
jugs command relatively high prices on a per ton basis, they
contribute little to recycling program revenue due to their low
density. Plastic soda bottles and milk jugs account for only 4 per
cent of the weight while making up 36 per cent of the volume of
material collected in Rhode Island.
493
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Mixed rigid plastic bottles are present in most American
municipal waste streams in amounts equal to or slightly greater
than the amounts of plastic soda bottles and milk jugs. However,
revenue will be lower for this less desirable feedstock than for
soda and milk bottles. As discussed below, in certain cases,
adding plastic containers can raise collection costs by a
significant margin.
Revenue RI Recycling Facility
Four Months —
January 1990 through April 1990
Material Revenue % of Total $/Ton
newspaper
corrugated
clear glass
brown glass
green glass
pi milk j
pi soda b
mixed piste
tin metal
aluminum
other
$ 15,222.36
0.00
57,348.12
16,237.00
16,483.00
26,056.40
51,538.00
0.00
6,039.00
189,767.55
0.00
4.02
0.00
15.14
4.29
4.35
6.88
13.61
0.00
1.59
50.11
0.00
0.5-7
0.00
50-65
30-50
20-40
120-180
160-240
110-160
0-10
850-1000
NA
total
$378,691.43
100.00
494
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COLLECTION COSTS
The following discussion of collection costs is provided to provide
a context for understanding the potential of on-truck densification
for reducing costs.
The cost of putting a truck and driver on the road is the
largest component of recycling collection costs. The truck fleet
sizing model used in Rhode Island shows how various inputs
influence the size of the fleet and therefore the cost of the
program.
The model has three main parts: drive time, pickup time and
haul time. Of these, only pickup time and haul time are affected
by the amount and type of materials collected and therefore the
amount of plastic materials present. Drive time is independent of
these factors.
SIZING TRUCK FLEETS
units served housing density
I i
materials x volume road & traffic conditions
j, J, ' .
participation rate drive time
4:
truck cap. time/pickup
4- 4
# hauls pickup time
haul time
495
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The greater number of serving units and the increased volume
of plastics lead to more full boxes, which in turn can lead to more
setouts, requiring more pickups and possibly overtime. These
factors also mean additional time to make more hauls, requiring
more money to pay for overtime and increased operating and
maintenance costs (tires, fuel, repairs, etc.)- The greater volume
can mean that larger, more costly trucks are required to
accommodate plastics.
In most cases, the combined effect of all these factors
produces only marginal increases in costs for overtime and larger
trucks. However, in certain circumstances, such as when long hauls
are involved, the increased volume and greater number of serving
units means that an additional truck is required. In that case the
cost of adding plastic is high — about $65,000 per year (annual
cost to own and operate a dedicated recycling vehicle).
The cost of collecting recyclables is already high in
comparison to the cost of solid waste collection due to the lack
of compaction and the need to do at least one curbside sort to
separate paper from bottles and cans. The average cost of
collecting recyclables in Rhode Island is $70 to 85 per ton
compared to $35 to 40 per ton for solid waste even for efficient
recycling collection systems that use one operator, dedicated
recycling trucks in order to keep costs down.
496
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Collection Systems
Before looking at how compaction and augmentation devices
could work, a brief look at recyclables collection systems is in
order. Recycling trucks generally hold from 15 to 30 cubic yards.
Truck types include trailers and dedicated recycling trucks.
Manually loaded recycling trucks come in either low or high profile
versions, with low profile trucks being easier to load.
Semi-automatic trucks are easier to load than manual trucks
but are available only in high profile versions. Trucks come
equipped with from one to six compartments which may be fixed or
moveable. Moveable compartments are preferred because they allow
adjustments for differing mixes of materials.
Low Profile Recycling Truck
Semi-automatic Top Loading Recycling Truck
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Manual Truck
rrrrr rr
When a recycling facility is available, then the number of
curbside sorts and the time taken for sorting can be kept to a
minimum — one for paper, another for bottles and cans. If no
recycling facility is available, then further sorting by residents
and/or operators is necessary to prepare materials for market.
Some programs report up to six curbside sorts. Based on
information collected from programs around the country, it appears
that each additional sort after the first one would take four
additional seconds for the manual- truck and three and a half
additional seconds for the semi-automatic truck. (Don Fish, RIDEM,
June 1989.)
In programs without a recycling facility, densification may
be more feasible since additional sorting time will not be required
in order to separate materials for densification.
498
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DEKSIFICATION METHODS
Manufacturers and recyclers are trying to fit more
material in recycling trucks either by densifying material or
augmenting the space available. Numerous projects to develop on-
truck compactors or granulators, or to add space on recycling
trucks have been conducted in the last two years. Of these, eleven
were reviewed for this paper (see appendix). Most of the devices
did not work. However, several warrant further study. A general
discussion of each type of device and the advantages and
disadvantages of each are provided,
Methods for making room for plastics include granulation,
heavy compaction with or without perforation, light compaction, and
augmentation of space on trucks either by adding bubblebacks or by
adding wire baskets to the tops or sides of low profile vehicles.
Determining whether a device provides a benefit is a balancing
act. Do the gains from increased capacity or reduced pickup and
haul time outweigh the losses from the space taken up by the device
(one to two cubic yards for compactors or densifiers); the time
needed for extra sorting, and revenue lost due to increased glass
breakage? (Glass breakage increases when plastics are sorted and
placed in a separate compartment for densification, and the
cushioning effect of the plastics is lost.)
The degree to which a densifier provides a benefit also varies
according to certain program characteristics. The densifier will
499
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provide more benefit in programs that have smaller trucks, longer
hauls, more material that can be densified, and/or where the
residents or operators are already sorting materials.
In general on-board densification device have not worked
because the size reduction achieved is not enough to offset the
disadvantages: extra space consumed by the device itself, the time
x
required for feeding and cycling, the time needed for extra sorting
in programs that use recycling facilities, the extra cost of the
devices (from $4000 to 20000), and the increase in broken glass due
to loss of cushioning from the plastics when plastics are sorted
into the compaction chamber.
Granulators
Granulation is unworkable despite high size reduction ratios
(15:1) due to a host of specific problems in addition to those
cited above: high cost ($20,000 each); high contamination levels;
and frequent breakdowns. Moreover, granulators can be used with
only one resin at a time. Therefore in order to granulate soda
bottles, milk jugs and rigid plastic bottles, three granulators
would be needed at a cost of $20,000 each for a total cost of
$60,000 added to the initial cost of the vehicle (between $45 and
72K) .
Light Compactors
Light compactors, such as a sheet metal wedge installed under
the roof of a semi-automatic truck in Rhode Island, are inexpensive
5OO
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(less than $1000), and provided up to 20 percent size reduction in
stationary trials. They can handle mixed recyclables so they
require no extra sorting, and did not result in more broken glass
since plastics were not separated out. However, the size reduction
achieved in the stationary trials could not be replicated in field
studies.
Heavy Compactors
Heavy Compactors have yielded up to threefold size reductions
in field trials; up to fivefold reductions are theoretically
possible. And compactors can be used to densify both plastics and
aluminum. However, the disadvantages of heavy compaction are
daunting: relatively high cost ($4000 to 10000) ; time lost to
sort, feed and cycle (cycle time 8 — 15 seconds); and more broken
glass. Moreover, those compactors that do not perforate materials
have a fatal flaw — the plastic springs back to its original shape
once the material is ejected from the compaction chamber.
Nonetheless, heavy on-board compactors that employ perforation
deserve further study to determine whether higher levels of
densification can be achieved; whether the time required to feed
and cycle the devices can be reduced; and whether the time needed
for sorting is offset by the gains in capacity. A compaction
device that can be installed in a top loading semi-automatic truck
is under development by the Labrie Corporation. Lummus Corporation
is also conducting trials of a smaller, less expensive version of
its side loading compactor-perforator in Louisiana.
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wire Baskets
In the meantime, some recyclers are making do with wire
baskets attached to the sides and tops of low profile trucks or
with bubbleback trucks. Wire baskets can increase capacity by up
to 16 cubic yards at very low cost (about $1000).
The disadvantage of the baskets is the time required to sort
material. One company is developing a wire basket system to use on
high profile trucks as well as low profile vehicles. However, at
least one hauler reports mixed results in using wire baskets.
Flattening by Residents
Rhode Island is also experimenting with having homeowners
flatten material despite fears that participation and recovery
rates will drop when residents are asked to perform extra work in
order to recycle. A single observation of material collected in
West Warwick during a previous trial of homeowner flattening showed
that residents did flatten material and that approximately 30
percent of the soda bottles and 50 percent of the milk bottles were
flattened on arrival at the interim recycling facility. Flattening
rates were much lower for food and beverage cans.
CONCLUSION
If manufacturers can produce smaller, more powerful compactor-
perforators, with either larger, lower, feed hoppers for side
loading vehicles; or top loading models for semi-automatic trucks;
and provide fullness indicators so that drivers would know how
502
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often to cycle the devices, we may see real advances in plastics
collection technology.
503
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APPENDIX
Perforator —~ compactors
Labrie Equipment Company
302 Rue du Fleuve
Beaumont, Quebec
Canada GOR ICO
Contact: Dominique Dubois 418-837-3606
Prodeva Inc.
100 Jerry Drive
Jackson Center OH 45334-0817
Contact: Fred Bunke 513-596-6713
Tri-State Trucking Equipment
Contact: Neil Buckman 215-657-1583
Lummus Development Corporation
PO Box 2326
Columbus, GA 31902
Contact: James Renfroe
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COMPACTORS (without perforation at time of data collection in Fall
1989)
Impact Products
281 East Haven
New Lenox IL 60451
Contact: Tom Pawlak 815-485-1808
Rudco
Contact: Sal Marizio 609-692-1314
Nu-Way Occupational Rehabilitation Center (ORC)
Wisconsin
Contact: Ryan Squires, ORC
Bea Hoffman, Winona County MN
Jurek Manufacturing
2975 Soffel Avenue
Melrose Park IL 60160
Contact: Bill Rock 312-345-0200
Perkins Manufacturing Company (still under development, Fall 1989)
3220 West 31 Street
Chicago IL 60623
Contact: Richard Berman 312-927-0200
505
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GRANOLATORS
Shred-Tech Ltd.
PO Box 2526
Cambridge Ontario NIR 7G8
Contact: Vince Catania 519-621-3560
Foremost
Contact: Bill Turner 201-277-0700
506
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SOURCES
Richard Berman, Perkins Manufacturing Company
Neil Buckman, Tri-State Trucking Equipment
Fred Bunke, Prodera Incorporated
Gretchen Brewer,
Vince Catania, Shred-Tech Limited
Dominique Dubois, LaBrie Equipment Company
Rea Hoffman, Winona Country, MN
Tom Kimmerly, General Engineers, Company, Inc.
Sal Marizio, Rudco
Patti Moore, Moore Recycling Associates
Tom Pawlak, Impact Products
James Renfroe, Lummus Development Corporation
Bill Rock, Jurek Manufacturing Company
Richard Sherer, General Engineers Company, Inc.
John Snellen, Waste Management Incorporated
Ryan Squires, Nu-Way Occupational Rehabilitation Center, Wisconsin
Bill Turner, Foremost
507
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CO-MARKETING IN DUPAGE COUNTY, ILLINOIS
Miriam C. Foshay
Recycling Management, Inc.
Presented at the
First U.S. Congerence on Municipal Solid Waste Management
June 13-16,1990
509
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CO-MARKETING IN DUPAGE COUNTY, ILLINOIS
by
Miriam C. Foshay
Co-marketing to improve marketability is a method pioneered by Gary Olson and the New
Hampshire Resource Recovery Association. But co-marketing has been identified with rural situations
remote from markets. DuPage Cpounty's recycling centers are distinctly urban, part of the metropolitan
area of the nation's third largest city. The Chicago area has markets for every material. Yet co-marketing
is just as applicable here, although for slightly different reasons.
DuPage County currently has ten recycling centers. All but one of these is a small, severely
underfunded operation manned largely by volunteers. All are short on storage space and many do not
have a shelter or electric power. Brokers are available to help them market newspaper, glass, and
aluminum. But plastic presents a special problem: because it has such a low density, it requires a
tremendous amount of storage space, and it must be densifled to make it marketable.
The largest of the recycling centers is Napervillle Area Recycling Center in the southwest corner
of the county. NARC became involved in recycling high-density polyethylene (HOPE) in 1987 when the
State of Illinois provided grant money to help purchase a baler. The baler was quickly outgrown, and in
1988 NARC proposed to the County that in exchange for a grant to purchase a plastics granulator, NARC
would provide marketing services for HDPE for the county's recycling centers.
Since none of the other recycling centers had the volume or the space to justify the purchase of
this piece of equipment, this arrangement seemed ideal. The services NARC provides include:
o Supplying woven polyester bags with a 2.2 cubic yard capacity for storing the plastic,
o Transporting the bags of plastic in a truck with a 22-foot box to the center in Naperville;
o Sorting the plastic by color and granulating it;
o Shipping the granulated plastic to Eaglebrook Plastics in Chicago.
NARC charges the recycling centers S.04 per pound for supplying the bags and granulating the
plastic Transport costs S12 per hour for labor and payroll taxes and S1.2S per mile for use of the truck.
NARC has agreed to charge only to cover its direct costs and none of the overhead. These charges are
subtracted from the revenue paid to each recycling center from the sale of its HDPE.
510
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As a result of this program, plastics recycling in DuPage County has increased tremendously. As
of January, 1990, NARC was collecting 20 tons per month from participating centers. Recycling centers
in surrounding counties have also joined, in spite of the fact that transportation costs can exceed the
revenue from sale of plastic. The accompanying graphs show how volume has changed over time.
o
c_
35
30 -
0.
^-g acH
"5s
15 -
10 -
5 -
Total HDPE Marketed for All Centers
OcL 198* through Dec. 1989
77s
A
WamnilU Gl«
Blys
clear
VIII, V,'t*tm,mt
r.rk
colored
L»Gr..(c Wh««i»
Cd
C-
o
1 1
o
a.
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Total HDPE Co-marketednper Month
All Centers—Ocl 88-Decl9^
v
\
/.
0 N
EZ1 Clear
colored
511
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One interesting sidebar of the data we collected was a reading of the volume of colored HOPE
that can be captured by a recycling program. Not all programs advertised that colored HDPE was
accepted; most, however, accepted the colored HDPE that showed up at their doors. The following table
shows the percentage of colored HDPE collected by each center during the period from May through
December, 1989:
Center
Hinsdale
Villa Park
Westmont
Wood ridge
Wheaton
Naperville
La Grange Park
% of colored
HDPE in a
mixed-HDPE
waste stream
23.5%
10.9%
7.7%
8.0%
10.1%
23.6%
28.4%
Even in Naperville, where colored plastic has been collected for over a year, many recyclers don't realize
that their detergent bottles can be recycled, too. One must assume that the lower figures reflect
incomplete dissemination of knowledge that colored plastics can also be recycled. The higher figures,
then, would approach the maximum level of colored HDPE recovery. It would appear from this table that
colored HDPE constitutes one-quarter to perhaps as much as 30% of all household HDPE.
In addition to allowing small recycling centers to handle plastic economically, co-marketing has provided
us with power in the marketplace. NARC found that their granulator had a difficult time handling
colored plastics because the detergent residues would cause plastic flakes to adhere to the grinding
chamber, clogging the screen and requiring extensive cleanup. This problem was solved by increasing the
hole diameter of the screen from the standard 3/8" to 5/8", which also allowed faster processing of HDPE.
Our buyer, however, refused to accept this coarser product, so we found another market. At 30 tons of
plastic a month, we are a major supplier of post-consumer regrind, and it only took two shipments before
our original market ate crow and agreed to accept our 5/8" material.
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Co-marketing of materials is a technique with a number of advantages. It allows pooling of
resources to allow maximum use of the resources available. It gives power in the marketplace, allowing
more control over price and specifications. And it allows the recycling of materials which would
otherwise be uneconomical to handle.
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COMPOSTING OF HSU IN THE USA
Luis F. Diaz and Clarence G. Golueke
Cal Recovery Systems, Inc.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
515
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INTRODUCTION
The convening of this Conference is ample evidence of the public's
awareness of the magnitude of the solid waste managment problem and of the
challenge to do something about it. Nevertheless, at the risk of stres-
sing the obvious, we begin with a few words about the causes of the prob-
lem and the nature of the challenge so as to provide a setting for the
subject of our paper.
Three factors share responsibility for much of the problem and the
challenges. They are: 1) the continuing migration of the urban population
to the suburbs; 2) the unceasing generation of large quantities of wastes;
and 3) a serious shortage of professionals specifically capable of relying
upon alternatives other than the land for the disposal of municipal solid
waste (MSW). The shortage is critical for a rapidly increasing number of
municipalities, inasmuch as for them, landfilling is no longer a viable
alternative because of public pressure, cost, and intensification of re-
source conservation.
The nature and dimensions of the problem are such that each and every
solution proposed for it and adopted by the community must not only be
politically and environmentally acceptable, but also be economically fea-
sible. A solution that sufficiently meets these requirements is to sup-
plement sanitary landfilling with resource recovery (i.e., recycling).
One of the more important forms of resource recovery is biological stabil-
ization ("biostabilization"). Of the biostabilization methods, composting
has much to offer, and moreover has been demonstrated as being eco-
nomically feasible.
The main theme of our presentation is the past, present, and
projected status of composting as a means of biologically stabilizing MSW
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in the U.S.A. We close with a discussion of the status of yard, leaf, and
garden waste composting.
STATUS OF MSW COMPOSTING
Past
Chronologically, the status of composting MSW in the past can be
divided into the two periods: "Early" and "Intermediate" (or "Dormant").
Broadly speaking, the early period began in the 1940s and continued until
the onset of the intermediate period in the late 1960s. The intermediate
period continued until the onset of the present or modern period in the
mid-1970s. (The time frames are only approximate.)
Early Period
The compost record during this period would be best summarized by the
adjective "mixed." Thus, through research and development, great strides
were made in the advancement of understanding and knowledge of principles
and parameters of the compost process. The progress and accomplishments
were such as to raise composting from the status of an art to that of a
science.
In sharp contrast, the record compiled by composting, when used as an
option on a practical (municipal) scale in municipal solid waste manage-
ment, was far from impressive. A very likely reason for the mediocrity of
the early record was that at the time, composting was 3 to 4 decades
"ahead of its time." Open dumping was only beginning to give way to the
early and rather primitive versions of sanitary landfilling. Moreover,
the prevailing illusion at the time was that not only was an abundance of
land available for the disposal of wastes, but that the abundance would
continue into the dim, distant future. These and other factors (e.g.,
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public apathy towards resource recovery, little concern about the quality
of the environment) combined to render disposal via the land economically
much more attractive than composting. The situation was rendered almost
hopelessly grim by an unwarranted and certainly not-fulfilled expectation
of profits to be obtained from the sale of the compost product.
We conclude our discussion of the early status of composting with
brief descriptions of a few of the compost operations that attracted
attention at the time.
Sacramento. California
A refuse composting facility, operated as a demonstration facility
and based on the use of a "Dano" reactor was designed and built in
Sacramento in 1956. Having served its purpose, the facility was closed
after having been in operation for about five years.
The Sacramento facility was operated in the following manner: Un-
sorted (mixed) waste brought to the facility in conventional waste col-
lection vehicles was discharged onto a conveyor system. Noncompostable
items, along with recyclable items (e.g., bottles, rags, cardboard), were
removed manually. The non-compostable items were discarded. Ferrous
material was removed with the use of a magnetic drum. Refuse remaining
after the removal of objectionable items was primarily organic in nature.
This organic residue was passed through a shredder, in which it was size
reduced to a particle size that ranged from less than 1 inch to about 5
inches. The shredded material was discharged into a Dano reactor. Resi-
dence time in the reactor was on the order of 14 days. The final volume
of the composted refuse varied from 60% to 70% of that of the incoming raw
material. The Dano reactor used in the demonstration was much the same in
design and operation as the modern Dano reactor. The Dano reactor was a
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closed, horizontally oriented cylinder that had a 100-ton capacity and was
rotated at 0.8 rpm. The interior of the cylinder was equipped with vanes
to impart a tumbling motion to the rotating wastes. Air was introduced
into the cylinder to aerate the composting mass. Moisture content of the
material was adjusted by means of water jets distributed along the side of
the cylinder.
Chandler, Arizona
In the Chandler operation, a few oversize items and rags were grossly
sorted from the incoming refuse. Ferrous metals were removed by means of
an electromagnet (60% efficiency). The sorted refuse was shredded in a
hammermill equipped with coarse grates. Moisture content was adjusted by
adding either sewage sludge or water at the bottom of the primary elevator
conveyor.
The shredded material was transferred to outdoor concrete slabs,
where it was either piled into 4-ft high windrows that were about 6-ft
wide at the base, or was placed in bins formed of hardware cloth. During
the first 14 days ("active" stage), the material was aerated by way of
"turning," and moisture was added when required. The active stage was
followed by the "curing" stage (about 14 additional days). Apparently the
quality of the compost was adversely affected by the inefficiency of the
sorting process.
Phoenix. Arizona
The Phoenix refuse composting facility was owned and operated by the
Arizona Biochemical Company. The company had a contract with the city to
accept refuse for a tipping fee of $1.25 per ton for the first year and
for $1.10 per ton thereafter. Operation of the facility was begun in
1962.
519
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In the operation, refuse was manually sorted, followed by magnetic
separation. The sorted residue was shredded and then introduced into a
Dano drum. Two additional drums were expected to be put into operation
about 5 to 6 months after start-up. Unfortunately, after seven months of
operation the facility closed because of lack of financial support.
Johnson City. Tennessee
The construction and operation of the Johnson City compost facility
was a part of a joint project conducted by the U.S. EPA and the TVA. The
project was begun in 1967 and was terminated in 1971. The main objective
of the project was to evaluate the feasibility of windrow composting for
managing municipal solid waste. However, the scope of the study embraced
a wide range of investigations, among which were: 1) the composting of
mixtures of refuse and sewage sludge; 2) the evaluation of public health
problems; 3) an assessment of economic benefits from using compost for
agricultural, horticultural, or soil amendment purposes; and 4) the deter-
mination of permissible rates of compost loading on the soil.
The plant had a nominal capacity of 60 tons per day for an 8-hr
shift. Incoming wastes were sorted manually and ferrous materials were
removed by means of magnets. The sorted residue was either passed through
a hammermill or through a rasping machine. Moisture was adjusted to a
level of 50% to 60% by adding either water or sludge to the refuse. The
size reduced material was stacked into 4- to 4.5-ft windrows that were
about 9-ft wide at the base and as long as 230 feet. The material was
aerated 8 or more times using a turning machine. The active composting
period varied from 35 to 44 days. After composting, the material was
cured, dried, shredded, and screened.
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Other Facilities
Time and space permit only a brief mention of two other facilities,
namely, the 35-ton per day plant at Norman, Oklahoma and the 70 ton per
day plant (design capacity - 150 tons/day) at San Fernando, California.
Both employed the "Naturizer" system.
The two principal features of the Naturizer system were the "pul-
verator" and two vertical 3-tiered digesters. The pulverator was a large
diameter cylinder revolving slowly on a longitudinal axis with heavy bar
hammers. It was followed by a horizontal hammermill with studded shells.
Each digester consisted of 3 rectangular cells tiered one above the
other. Slowly moving slat bottoms advanced refuse from the receiving end
of the top cell to the discharge end. The discharged refuse was passed
through the middle cell and then through the bottom cell. At this stage,
the material was reground and then passed through a second tier of cells
(the second digester).
Intermediate (Dormant) Period
The intermediate period is appropriately termed "dormant," since at
the time, excepting by a dedicated few, composting was not regarded as
being a viable option in municipal solid waste management. Despite this
temporary loss of favor, the interest and research regarding composting as
a treatment method persisted. This persistence paved the way for compost-
ing to become the candidate of choice when a viable alternative to land-
filling and incineration had to be found for sewage sludge disposal in the
late 1970s.
PRESENT AND FUTURE STATUS
Toward the end of the 1970s, the situation, hitherto so unfavorable
to the compost option, began to change rapidly and drastically, to the
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extent that composting no longer was ahead of its time. On the contrary,
its time had come. The change began with sewage sludge, then progressed
to yard and garden debris, and now is making inroads on the entire organic
fraction of the municipal solid waste stream. The magnitude of the transi-
tion from the low status of MSW composting in the late 1960s and early
1970s is emphasized by the fact that now composting is one of the more
publicly accepted options for treating important components of the
municipal waste stream, namely, yard wastes and sewage sludge.
Several factors have and are combining to bring about the remarkable
rise in the status of composting to the level of being the popularly ac-
cepted option of choice for treating and disposing of organic municipal
waste. Although the importance of the favorable economic situation re-
sulting from the change in circumstances must not be overlooked, other
factors come into play. Those factors include landfill shortages, high
disposal fees, and legislation that prohibits the disposal of "unprocessed
waste." Those factors, combined with the federal and state regulatory
constraints imposed on the two principal competing options (sanitary land-
fill, incineration), and the higher costs of the two have substantially
raised the status of MSW composting. In addition, financial assistance
programs established in several states (e.g., Massachussetts, Minnesota,
Iowa) are also having a positive impact on the growth of MSW composting.
Not to be underestimated is the legislative impetus. Recently, sev-
eral states have enacted legislation in which priorities are established
regarding alternatives for managing solid wastes. Typically, the laws
assign top priorities to reduction of generation rates and volumes, ex-
pansion in recycling and composting, followed by incineration and land-
filling. If put into effect, new regulations recently proposed by the
522
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U.S. Environmental Protection Agency for landfills undoubtedly would raise
the cost of landfill ing. As it is, landfill costs are major incentives
for the strenuous efforts now being directed to the reduction of the
amount of wastes destined for land disposal. Composting has the advantage
of fitting well with many of the approaches to waste reduction and
recycling.
Potential Danger
A potential danger to the continued success of modern composting.is
in the uncritical attitude that could be an undesired offshoot of the
present interest in MSW composting. The interest could be so intense as
to engender an uncritical attitude; which in turn could lead to the selec-
tion of the composting option without having made a thorough analysis of
alternative options and their costs. The uncritical attitude could take
the form of failing to realize that composting MSW usually is an under-
taking, the complexity of which is a function of the extent and type of
separation required. Although manual separation can be and is success-
fully used for smaller operations, it is inadequate for coping with the
massive quantities of refuse that must be sorted in the larger opera-
tions. Mechanical processing must be incorporated in designs for dealing
with those quantitites. Consequently, with the exception of some particu-
larly unusual set of circumstances, a combination of manual and mechanical
sorting is the only practical means of accomplishing the degree of separa-
tion needed to render MSW a satisfactory feedstock for the compost pro-
cess. The importance of doing so rests on the fact that the quality of
the finished compost product depends heavily upon the effectiveness of the
separation process [3,4]. The problem is that providing a satisfactory
mechanical separation is a difficult task.
523
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Modern Status — Specifics
Operating Facilities
Judging from personal observations and information gained from dis-
cussions with their designers and operators, existing plants in the U.S.
generally are characterized by a relatively low throughput and capital
investment, and an over-simplification of design. Insufficient attention
is given to the segregation of organic from inorganic matter in the
refuse.
The status of MSW compost projects in the U.S. is summarized in Table
1. The location, capacity, year of establishement, and other pertinent
information regarding MSW composting plants in operation in the U.S. in
May, 1990 are listed in Table 2. The collective range of capacities was
from about 15 to 350 tons/day. The table further indicates that with its
capacity of 700 tons/day (design capacity - 1000 tons/day), the Wilmington
(Delaware) plant was much larger than the other four plants in operation.
The respective capacities of the latter four were only 15-20, 30, 50, and
65-70 tons/day. Moreover, the designs of the four were relatively simple
and had been made operational within the preceding two years.
Wilmington Facility -- The Wilmington facility is designed to process
about 1000 tons of municipal and commercial solid waste per day into ref-
use derived fuel and compost. It incorporates size reduction, air clas-
sification, magnetic separation, and screening to recover metals and
glass. This sorting set-up results in the production of about 250 tons of
highly organic residue each day. Sewage sludge (about 20% solids) is
added to this residue, and the resulting mixture is introduced into one of
four digesters, each of which has a holding capacity of 175 tons. Each
digester is equipped such that its contents can be mixed and aerated while
524
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Table 1. Summary of MSW Compost Projects
Status Number
Operation 7
Pilot 7
Design 17
Permit 8
Feasibility 21
Total 60
Source: BioCvcle and Cal Recovery Systems, Inc. [8]
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Table 2. Operational Municipal Solid Waste Composting Facilities in the U.S. (1990)
Location
Lake of the Woods, Minnesota
Fillmore County, Minnesota
en J
o> Portage, Wisconsin
St. Cloud, Minnesota
Sumter County, Florida
Wilmington, Delaware3)
Skamania County, Washington
Capacity
(tons/day)
5 to 10
15 to 20
30
50
65 to 70
-700
70
Year
Established
1989
1987
1986
1988
1988
1984
1988
Type of System
Windrow
Windrow
In-vessel/drum
In-vessel/drum
Windrow
In-vessel/silo
Windrow
Material
Added
..
--
Sewage sludge
Sewage sludge
--
Sewage sludge
Markets
None
None
None
None
None
Yes
Yes
a) This facility was designed to process about 1,000 TPD of MSW to recover RDF, glass, and metals. An organic
residue is mixed with sludge and composted in an in-vessel system.
-------
in the digester. At the completion of a 5-day retention period in the
digester, the material is removed and is stacked in a pile and is allowed
to mature for 30 to 45 days. The matured material is screened. By virtue
of a permit, the fines are used for horticulture. The rejects are mixed
with top soil in a 1:1 ratio, and the mixture is used for erosion control
at landfills.
Sumter County -- Since mid-1988, a windrow composting facility has
been in operation in Sumter County, Florida. According to the operators
of the facility, from 65 to 70 tons of residential waste and commercial
waste are processed at the facility each day.
In the operation, incoming waste is introduced into a unit designed
to open the bags and discharge the contents onto a conveyor belt. The
belt passes the contents by a magnetic device such that ferrous metals are
removed. Aluminum and some inerts are removed manually. The waste, now
free of ferrous and aluminum metals and some inerts, is size reduced to an
approximate 2 x 2 in. particle size. The size reduced material is stacked
in 6 ft high by 10 ft wide windrows and is dosed with a proprietary
bacterial inoculum. The operators claim that the compost is ready after
six weeks. The operators hope to market the product as soon as the
Florida Department of Environmental Regulation grants permission.
Market for the Compost Product
At present, information on product characteristics, expected quanti-
ties, and consistency of production is too uncertain and fragmentary to
permit a firm definition of the present and hoped-for market for the MSW
compost product. Apparently, no MSW composting facility is routinely
marketing its product. The absence of marketing is to be expected,
527
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inasmuch as most MSW compost facilities are as yet in the testing and
permitting stage.
The very little quantity of available MSW compost product makes it
difficult or even impossible to collect needed information. Moreover,
projections made on the basis of available information would be highly
uncertain. It is unlikely that the characteristics of the product
presently available would be the same as those of material routinely
produced after full production is reached.
HSW as a Bulking Agent
Refuse has many shortcomings that would make it less effective than
wood chips as a bulking agent in the composting of sewage sludge. How-
ever, the shortcomings can be lessened or even avoided by resorting to a
combination of careful preprocessing, avoidance of excessive moisture,
following suitable mixing, and aeration procedures.
Potential benefits from the use of MSW as a bulking agent could in-
clude significant cost savings, possible (but very unlikely) sale of the
co-compost product, and the utility of the product in soil reclamation.
The economic justification of the substitution of refuse for wood chips as
a bulking agent in sewage sludge composting obviously would be determined
by way of a careful analysis of the shortcomings of refuse versus the
benefits of using it as a substitute for wood chips [5].
Future
The future of the implementation of MSW facilities seems bright. If
it can be done successfully, the implementation would greatly lighten the
management and disposal burden. Composting lends itself to integration
into many material-recycling schemes -- including those that involve
incineration. For example, the use of suitably processed MSW as a bulking
528
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agent for composting sewage sludge (i.e., co-composting) would ease the
task of treating and disposing two major wastes.
Before the routine success of co-composting can be assured, certain
requirements must be met. Among the more important are these: 1) as-
suredly reliable mechanical equipment; 2) advancement of the knowledge and
understanding had by designers and system vendors; 3) means of removing or
counteracting the toxic content of the sludge fraction; and 4) development
of an outlet large enough to accommodate all or most of the resulting
co-compost product.
STATUS OF YARD WASTE, LEAF, AND PARK DEBRIS COMPOSTING
Unless otherwise specified, the term "yard waste" refers to the three
wastes collectively. The concept of reducing the size of the municipal
waste stream destined for treatment and disposal by separately treating
yard waste not only is becoming increasingly attractive, but also is being
implemented throughout the country. Moreover, the usual method of treat-
ment is composting.
Judging from information gained in various MSW characterization
studies, 5% to 30% (by weight) of the municipal solid waste stream may be
in the form of yard debris. Quantities of yard debris generated and its
resulting proportion of the MSW stream not unexpectedly vary seasonly, as
well as from region to region. Thus, generation is at its lowest during
the winter season in those parts of the country that have such a season,
and during the rainy season in the other parts. A precipitous influx of
leaves into the waste stream occurs in autumn in the temperate zone--- as
much as 95% of the MSW stream in some communities.
529
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Because of the relative ease with which yard waste can be diverted
from the landfill, hundreds of municipalities have established programs
for utilizing the waste. Additionally, the diversion is encouraged by
legislative measures. Some of the measures even prohibit the disposal of
yard debris in landfills: In 1988, the State of New Jersey banned the
disposal of leaves in landfills; other states include Minnesota,
Wisconsin, and Illinois.
Collection of Yard Waste
Because yard waste is an excellent substrate for the compost process,
the waste should not be permitted to be contaminated with other wastes,
especially not with undesirable wastes. Prevention can be accomplished
through appropriate collection strategies. For example, establish pub-
licized drop-off sites and institute curbside collection.
The use of drop-off sites is, perhaps, the simplest and least expen-
sive of the yard waste collection strategies. Large containers are placed
in one or more strategic locations, and the public is encouraged to de-
posit its yard waste in the containers. Some public officials regard the
dependence upon the public to both segregate the material and transport it
to the drop-off site as being a weakness of the strategy. Thus far,
public participation has been at a modest level.
Curbside collection has been more successful in terms of public
participation, Curbside collection is carried on in many ways. One way
is to impose a regulation that demands that the homeowner segregate and
place the yard waste at a designated collection point. For example, have
the yard waste piled curbside for either manual or mechanical collection.
An alternative is to have the homeowner use a container (can, box, or bag)
instead of simply piling the yard waste at the curb. The task of
530
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collecting the mass of leaves that accumulate in the autumn is accom-
plished in several communities through the use of vacuum trucks. However,
the cost of collecting leaves via vacuum can be more than $80/ton of
leaves collected.
Yard Haste Compost Technology
A few communities use an extremely low-technology approach that they
unjustifiably label "composting." Their so-called "composting" makes mini-
mal use, if any, of processing. The material is simply stacked in piles
as high as 10 to 20 ft, which are not disturbed over periods of longer
than 18 months. Because the wastes consist mostly of plant residues, and
of shrub and tree trimmings ranging from twigs to large branches, the
experience had by those communities has been far from satisfactory and has
been marred by the development of fire hazards during the dry season.
The windrow system is the one of choice for communities interested in
pursuing a satisfactory approach to composting yard waste. Aeration is
accomplished either by mechanical turning, by forced aeration, or by a
combination of the two. The general experience has been that forced
aeration leads to an excessive drying and cooling of the composting mass,
especially when the substrate consists largely of tree trimmings and dried
vegetation (leaves, straw). The very porous nature of the waste mass
permits a relatively unimpeded movement of air and diminishes the moisture
holding capacity of the windrowed mass as a whole. The lowered "water
holding capacity" is due to the rapid percolation of water to the bottom
and out of the windrow.
As with mixed yard wastes, a minimal approach is used by some com-
munities in the composting of leaves. Basically, the leaves are stacked
in piles and are allowed to decompose without being given further
531
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attention. Decomposition may take as long as 18 or more months, and
usually is accompanied by the development of unpleasant odors which are
especially pronounced on the rare occasions on which the mass is turned.
This approach is used in situations in which there is available land area.
A more positive approach is followed when available land is expen-
sive. The approach is the windrow method described for mixed yard waste
(i.e., aeration either by mechanical turning or by way of blowers). Mois-
ture content and other parameters are maintained at levels that permit
shortening the compost process to four or five weeks. The process may be
further optimized through the addition of nitrogen.
Equipment
The unsatisfactory performance of many yard waste compost operations
usually can be traced to the lack of a reliable shredder. A shredder has
an adequate capacity if it can size reduce fairly large branches and
brush, twigs, tree clippings, and other woody material to a particle size
small enough to permit easy manipulation and promote biological break-
down. Moreover, the shredder must be sufficiently sturdy to deal with
occasional contaminants such as rocks, bricks, and pieces of metal. An
indicator of an inadequate shredder is an accumulation of branches and
other woody debris. Eventually the accumulation reaches unmanageable
proportions, becomes unsightly, and could well constitute a serious fire
hazard. Other indicators are excessive downtime and high O&M costs.
Turning the piles in small operations can be adequately accomplished
by means of a front-end loader or a bulldozer equipped with a standard
blade. Exceptions might be the occasions when yard waste consists mostly
or exclusively of grass clippings. Because of the matting tendency of
grass clippings, a bulldozer or front-end loader might not be capable of
532
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dealing with the tendency of grass clippings to mat or form clumps. A
machine specifically designed for the turning would be needed for large
operations [6].
Moisture Problem
Neglect of moisture maintenance in the composting mass is an all too
common occurrence in yard waste compost operations. Insufficient moisture
can seriously inhibit the compost process and thereby lower the efficiency
of the operation. A more serious consequence is the intensification of
the fire hazard. The usual reason for the failing is the absence of an
accessible water source. The absence generally is due to the high cost of
providing the water source. Unfortunately, the high cost has no effect on
lowering the minimum moisture content required for satisfactory compost-
ing. Some communities confronted with such a dilemma resort to an alter-
native, but doubtfully acceptable, approach. They simply allow the piles
to remain undisturbed until the arrival of the rainy season, at which time
they start or resume the compost program, as the case may be.
The Yard Waste Compost Product
Yard waste compost operations in which the feedstock is consistently
free of objectionable contaminants, and the compost process is conducted
satisfactorily, almost invariably produce a product that simultaneously is
an excellent soil amendment and a partial source of fertilizer elements.
Properly screened, the product could be safely used in the more demanding
landscaping activities.
SUMMARY AND CONCLUSIONS
The many positive past and present developments in yard waste and MSW
composting warrant the objective conclusion that the current status of
533
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composting as a waste management and disposal alternative is quite
favorable in the United States.
The status of yard waste composting is steadily improving. Within
the span of the past five years, the yard waste compost activity in the
U.S. has expanded from a few scattered operations, to the hundreds of
known operations distributed throughout the nation. Despite the un-
fortunate tendency of some communities and developers to oversimplify the
operation to the extent that management disappears, the yard waste compost
movement will continue to grow unabated, particularly in the role of
diverting the waste from landfills.
MSW composting is experiencing a period of growth that, barring
unforeseen reverses, will continue for some time to come. The rate of
growth, although far slower than that of yard waste composting, neverthe-
less is respectable.
An unfortunate occurrence in MSW composting is the failure of most of
the present and planned MSW composting programs to include source separa-
tion. The failure very likely will prove to be a substantial impediment
to the attainment of design performance by the compost facility. Other
major impediments to the success of the MSW compost movement include: 1)
insufficient basic design data; 2) failure to establish standards for the
finished product; 3) insufficiency of experience on the part of many
designers, vendors, and clients; and 4) overly optimistic expectations
regarding markets and uses for the material [4,6,7].
REFERENCES
1. Anonymous, "Composting Saves Landfill Space," World Wastes.
28(12):29,31 (1985).
534
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2. Goldstein, N., "Steady Growth for Sludge Composting," BioCvcle.
29(10):27-36 (November-December 1988).
3. Savage, G.M., and L.F. Diaz, "Key Issues Concerning Waste Processing
Design," Proceedings of the 1986 ASME National Waste Processing
Conference. Denver, Colorado, June 1986.
4. Diaz, L.F., G.M. Savage, and C.G. Golueke, "Production of Refuse-
Derived Fuel from Municipal Solid Waste," presented at the 79th Air
Pollution Control Association Annual Meeting, Minneapolis, Minnesota,
June 1986.
5. Savage, G.M. and C.G. Golueke, "Major Cost Elements in Co-Compost-
ing," BioCvcle. 27(l):33-35 (January 1986).
6. Savage, G.M., et al_, Engineering Design Manual for Solid Waste
Reduction Equipment. Report by Cal Recovery Systems, Inc. under U.S.
EPA Contract No. 68-03-2972, 1982.
7. Diaz, L.F., G.M. Savage, and C.G. Golueke, Resource Recovery from
Municipal Solid Waste. Vol. I. Primary Processing. CRC Press, Inc.,
Boca Raton, Florida, 1982.
8. Goldstein, N., "Solid Waste Composting in the U.S.," BioCvcle.
30(H):32-37 (Novmeber 1989).
535
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THE COMPOSTING PLANTS IN MEXICO
A STATE OF THE ART
ARTURO DAVILA, M.Sc.
PRESIDENT OF THE MEXICAN SOCIETY FOR THE CONTROL
OF SOLID AND HAZARDOUS WASTES
PRESENTED AT THE
FIRST U.S. CONFERENCE ON MUNICIPAL SOLID WASTE MANAGEMENT
JUNE 13-16, 1990
537
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ABSTRACT
THE RECYCLING AND UTILIZATION OF MUNICIPAL SOLID WASTE IS AN
OLD PRACTICE IN MEXICO, SOME TIME AGO, THIS PRACTICE WAS
CARRIED ONLY BY SCAVENGERS IN THE DISPOSAL SITES, IN 1972,
HOWEVER, THE FIRST COMPOSTING PLANT IN MEXICO WAS BUILT IN THE
CITY OF GUADALAJARA, WITH swiss TECHNOLOGY,
PRESENTLY THERE ARE six COMPOSTING PLANTS, OF WHICH ONLY TWO
ARE IN OPERATION, ONE MORE WILL BEGIN OPERATION BY 1990, THE
TENDENCY TO PUT MORE OF THESE PLANTS IN OPERATION IS UNKNOWN,
BECAUSE IT DEPENDS ON ,POLITICAL DECISSIONS, RATHER THAN
TECHNICAL AND ECONOMICAL FACTORS, IN THIS RESPECT OUR
ASOCIATION IS PROMOTING A REAL EVALUATION OF PROJECTS BEFORE
GRANTING LOANS FOR THIS PURPOSE.
FOR THE PEOPLE WHO WORK IN THE FIELD OF CONTROL OF MUNICIPAL
SOLID WASTE, THE COMPOSTING PLANTS INSTALLED, DO NOT REPRESENT
A SOLUTION FOR RECYCLING IN MEXICO, WE ARE PRESENTLY WORKING
IN THE DEVELOPMENT OF NATIONAL TECHNOLOGY AND ALSO TRYING TO
STOP THE ACQUISITION OF CONVENTIONAL PLANTS WHICH MIGHT BE
USEFUL IN DEVELOPED COUNTRIES BUT NOT IN OUR COUNTRIES,
AS A RESULT WE CAN RESUME THE FOLLOWING RESULTS:
1.- THE PLANTS REPRESENTS A LOSS OF HARD CURRENCY
2.- THE PLANTS PRESENTS NO SOLUTION TO THE PROBLEM
3,- THERE is LACK OF EXPERIENCE OF PERSONNEL OPERATING THE
PLANTS
4.- THE PLANTS REPRESENTS TECHCNICAL AND ECONOMICAL PROBLEMS
538
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5,- THERE is A LOW DEMAND FOR THE COMPOST
6,- TOO WIDE VARIATIONS IN THE PRICES OF THE RECOVERED
MATERIALS COMPLICATE THE ADMINISTRATION OF THE PLANTS,
7,- LOW OR NO AVAILABILITY OF SPARE PARTS, MAKES MAINTENANCE
EXPENSIVE AND SLOW,
8,- SCAVENGING IN THE COLLECTION VEHICLES, MAKES THE WASTES
THAT ARRIVE TO THE PLANTS VERY POOR,
THIS PAPER PRESENTS THE PAST, PRESENT AND FUTURE OF THE
COMPOSTING AND RECYCLING PLANTS IN MEXICO, AND ANALIZES THE
MAIN TECHNICAL, POLITICAL, SOCIAL AND ECONOMICAL PROBLEMS THAT
HAVE OCCURED, AS WELL AS PRESENT CONDITIONS,
539
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I.- INTRODUCTION
HUMAN ACTIVITIES PRODUCE, AMONG OTHER THINGS, WASTES;
MAINLY GASES, LIQUIDS AND SOLIDS, IN GENERAL MAN'S CHOSEN
ENVIRONS HAVE A LIMITED CAPACITY TO ACCEPT, MODIFY AND
INTEGRATE THESE WASTES INTO ITS ECOSYSTEM WITHOUT CAUSING
MAJOR PROBLEMS, WHEN NATURE'S THRESHOLD LIMITS AND CAPACITY TO
ADAPT ARE EXCEEDED, IRREVERSIBLE ECOLOGICAL PROBLEMS ARE TO BE
EXPECTED, AND THE RESULTING ECOSYSTEMS MAY NOT BE AMIABLE TO
MANKIND SURVIVAL,
OUR SOCIETY IS A WASTEFUL ONE, MANUFACTURERS AND THE
MERCHANTS WRAP THEIR PRODUCTS WITH EXCESSIVE SUMPTUOUSNESS FOR
THE SOLE PURPOSE OF CALLING THE ATTENTION OF THE BUYER; IN
MANY INSTANCES THE WRAPPING MAY EXCEED THE VOLUME AND VALUE OF
THE PRODUCT BEING SOLD, THE FINAL DESTINATION AND PURPOSE OF
ALL THIS WRAPPING IS THE GARBAGE CAN, AND VERY LIKELYT OPEN
DUMPS.
IN ORDER TO TRY TO SOLVE THE INCREASING PROBLEM OF SOLID
WASTE, IN SOME PARTS OF MEXICO, MAINLY IN THE BIG CITIES, THE
AUTORITIES LOOK, AMONG OTHER THINGS, FOR RECYCLING AND
COMPOSTING PLANTS, IN 1972 THE FIRST COMPOSTING AND RECYCLING
PLANT IN THE COUNTRY WAS BUILT IN THE CITY OF GUADALAJARA;
AFTER THAT PLANT, FIVE MORE PLANTS WERE CONSTRUCTED AND ONE
MORE IS UNDER STUDY,
NOW, AFTER 18 YEARS, ONLY TWO PLANTS ARE WORKING WITH A
LOT OF PROBLEMS, THIS PAPER PRESENTS THE STATE OF THE ART OF
THE COMPOSTING AND RECYCLING PLANTS IN MEXICO, MAKING AN
EVALUATION OF THE TECHNICAL AND ECONOMICAL PROBLEMS THAT HAVE
OCURRED IN THE PAST 18 YEARS, IN ORDER TO ARRIVE TO SOME
CONCLUSIONS AND RECOMENDATIONS FOR DEVELOPING COUNTRIES.
540
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I HOPE THIS PAPER WILL BE OF HELP TO THOSE PEOPLE IN
POSITIONS WHERE DECISSIONS ARE TAKEN, SO THAT THEY BE VERY
CAREFUL WITH THE IMPORTED TECNOLOGIES OFFERED BY DEVELOPED
COUNTRIES,
II.- THE COMPOSTING PLANTS IN MEXICO
As I MENTIONED/ THERE ARE SIX COMPOSTING PLANTS IN MEXICO/
IN FIGURE NO,I/ THEIR LOCATION IS SHOWN,
THE PLANTS IN GUADALAJARA/ MONTERREY AND MEXICO CITY, HAVE
THE BULHER MlAG PROCESS, THE MEXICO CITY PLANT, HOWEVER, THE
FEEDLINE IS IN THE OPPOSITE DIRECTION AS IN THE OTHER TWO
PLANTS, ACAPULCO AND OAXACA HAVE A COPY OF THE SAME PROCESS
WITH LITTLE CHANGES BEFORE THE MILLS, THE LAST ONE IS LOCATED
IN TOLUCA, AND HAD A TOLLEMACHI PROCESS,
PRESENTLY/ ONLY THE GUADALAJARA AND MEXICO CITY PLANTS ARE
STILL WORKING,
IN THE VE.RY NEAR FUTURE/ POSSIBLY THIS YEAR/ A NEW
RECYCLING AND COMPOSTING PLANT WILL BE BUILT IN MERIDA,
YUCATAN, WITH A CREDIT OF THE WORLD BANK, IN THIS PART OF
MEXICO THERE IS NO COVER SOIL/ BECAUSE THE YUCATAN PENINSULA
IS CONSTITUTED BY CALCAROUS ROCK, As USUAL THE EXPECTATIVES
ARE FABULOUS/ AS BEFORE THE OPERATION OF THE OTHER PLANTS
BUILT/ HOWEVER/ I EXPECT THE SAME RESULTS AS IN THE OTHER
PLANTS,
THE PLANT'S PROCESSES CONSIST BASICALLY IN THE FOLLOWING
ACTIVITIES! FIRST THE COLECCTION VEHICLES DISCHARGE THE SOLID
541
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LOCATION OF THE COMPOSTING PLANTS
1r GUADALAJARA
2 .-MONTERREY
3r MEXICO, D.F.
4r TOLUCA
5 r ACAPULCO
6 r OAXACA
FIG No. 1
-------
WASTES IN STORAGE PITS/ LOCATED BETWEEN THE CONVEYORS THAT
FEED THE BELTS WHERE THE SALVAGE MATERIALS ARE SELECTED BY
SCAVENGERS MANUALY; AFTER THAT/ AND BEFORE GOING THROUGH THE
HAMMERMILLS THERE IS A MAGNETIC SEPARATOR/ AFTER THE MILL'S THE
WASTES ARE DEPOSITED IN A VIBRATING SCREEN/ IN ORDER TO
SEPERATE THE WASTE NOT SUITABLE FOR COMPOSTING/ WHICH CONSISTS
n
MAINLY OF PARTICLES GREATER THAN FOUR INCHES,
»
THE WASTES ARE THAN PASSED THROUGH THE SCREEN AND THE
DISTRIBUTION BRIDGE IN THE PRE'DIGESTI ON FIELD TO FORM
WINDROWS, AFTER THREE MONTHS THE COMPOST is FORMED BY AN
AEROBIC PROCESS, AFTER THAT/ AND DEPENDING ON THE MARKET,
THERE IS ANOTHER MILL FOR FINE MILLING TO GET COMPOST WITH
VERY GOOD PRESENTATION,
III.- SOLID WASTE CHARACTERISTIC IN MEXICO
IN MEXICO/ THE SOLID WASTE GENERATED VARIES/ BUT IT IS
POSSIBLE TO PUT IT INTO THREE MAIN GROUPS: ONE/ THE REGION IN
THE BORDER WITH THE UNITED STATES OF AMERICA, WITH ALMOST ONE
KILOGRAM PER CAPITA; THE CENTRAL PART OF THE COUNTRY WITH A
GENERATION PER CAPITA OF AROUND 650 GRAMS AND THE SOUTHEAST
WITH ABOUT 550 GRAMS PER CAPITA,
THE AVERAGE COMPOSITION IN THE SOLID WASTE GENERATED IN
MEXICO FOR THE THREE GROUPS IS PRESENTED IN TABLE No, I/ IN
THIS TABLE IT IS POSSIBLE TO SEE THE GREAT DIFERENCE IN THE
COMPOSITION OF THE SOLID WASTE GENERATED IN DEVELOPING
COUNTRIES AND IN DEVELOPING COUNTRIES, MAINLY THE ORGANIC
MATTER VARIES FROM 45 UP TO 60 PERCENT BY WEIGHT/ AND IT IS
ONLY POSIBLE TO GET 25 TO 30 PERCENT OF SALVAGE MATERIAL/ THE
543
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TABLE No, 1.- AVERAGE COMPOSITION OF THE MEXICAN REFUSE
RECUPERATED PERCENTAJE PERCENTAJE
MATERIAL BY WEIGHT OF RECOVERING
CARDBOARD 4.10 70
PAPER 9.63 45
COLOR GLASS 3.40 75
WHITE GLASS 4.25 71
CANS 2.52 60
FERROUS MATERIAL 0.76 60
NON FERROUS MATERIAL 0.60 40
TETRAPACK 1.66 50
BONES 0.80 50
PLASTIC FILM 3.42 55
RIGID PLASTIC 2,28 55
DIAPERS 3.66
RAGS 1.94 60
ORGANIC MATTER 44.70 60
OTHER 16.28
544
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REST IS MATERIAL WITH NO POSIBIL'ITY OF RECUPERATION BECAUSE OF
ITS CHARACTERISTICS OR THE DIFICULTY TO RECOVER THEM,
IV,- ANALYSIS AND EVALUATION OF THE RECYCLING AND COMPOSTING
PLANTS IN MEXICO,
THE MAIN PROBLEMS DETECTED IN THE DIFERENT PLANTS IN
MEXICO CAN BE RESUMED IN THE FOLLOWING:
4,1,- FEASIBILITY STUDIES
A,- POOR JUDGMENT IN DIFINING THE WASTE LOAD AND ITS
CHARACTERISTICS, INCLUDING THEIR SEASONAL QUALITATIVE
AND CUANTITATIVE CHANGES,
B,- THE INADEQUACY OF SAMPLING PROGRAMS USED HAVE RESULTED
IN AN UNREAL FORECAST OF THE RECOVERY POTENTIAL OF THE
SOLID WASTE,
C,- THE QUALITY, QUANTITY AND MARKETABILITY OF SALVAGE
MATERIALS WERE PREDICTED OUT OF THE SAMPLING PROGRAMS
WITH THE APPLICATION OF FICTITIOUS FACTORS OF
EFFICIENCY,
D.- THE FLUCTUATION'OF THE SECONDARY MATERIALS MARKET WAS
UNDERESTIMATED,
E.- NO ATTEMP WAS MADE TO CREATE A MARKET FOR THE COMPOST,
THE ASSUMPTION WAS THAT THIS WAS NOT AN ISSUE,
545
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F,- THE REDUCED MARKET AND VALUE OF WET OR DIRTY RECOVERED
MATERIALS WAS NO CONSIDERED IN THE REVENUE
PROJECTIONS,
G,~ THE GREAT IMPACT OF ON-ROUTE SCAVENGING -SPECIALLY
VALUABLE PRODUCTS AS CARDBOARD, GLASS BOTTLES AND
ALUMINIUM CANS- WASNOT CONSIDERED IN THE PROJECTIONS
OF RECLAMATION AND SALES OF SALVAGED MATERIALS,
H,~ AT THE FIRST PLANT, THE LACK OF EXPERIENCE WAS NOT
CONTEMPLATED/ THE PEOPLE GOT EXPERIENCE BY THEIR OWN
EFFORT AND VARIOUS COSTLY MISTAKES WERE MADE,
I,- THE OPENING OF IMPORTS FROM USA FOR USED COMPUTER
PAPER/ PAPER/ CARDBOARD AND METALS, LOWER THE PRICES
IN MEXICO FOR THIS TYPE OF SALVAGED MATERIALS,
j,- THE DECISSION TAKERS BELIVED ALL THE PLANT SALESMEN
SAID. EXPERIENCE SAYS THAT ALMOST ALL WAS FALSE,
K,~ NO COMERCIALIZATION PROGRAMS WERE MADE,
4,2,- COMPOST PLANT DESIGN
A,- THE STORAGE PITS WERE BUILT IN SUCH MANNER THAT IT IS
ALMOST IMPOSSIBLE TO MANTAIN THEM IN A GOOD AND
SANITARY CONDITION,
B,- IN THE MEXICO CITY COMPOSTING PLANT, THE ONLY WAY TO
FEED THE CONVEYORS IS BY THE CLAM CRANE, IF THIS IS
OUT OF WORK THE PLANT STOPS,
546
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c,- AFTER THE FIRST PLANT IN GUADALAJARA, VERY LITTLE
EXPERIENCIE WAS PUT IN THE CORRECTION OF THE DESIGN
DEFECTS OF THE PLANTS,
D,~ THE CLAM CRANE SYSTEM BEING USED TO FEED THE PLANTS
HAS PROVEN INEFFECTIVE AND UNRELIABLE,
E,- THE PITS FOR THE CONVEYOR THAT FEEDS THE SELECTION
AREA PRESENTS DEFICIENCIES FOR THE CHARACTERISTICS OF
THE MEXICAN WASTE/ AS THE WASTE TENDS TO FORM AN ARCH
AND IT IS ALMOST IMPOSSIBLE TO FEED,
F,- THE AUTOMATED FEED CONTROL SYSTEM ON THE FEEDER
CONVEYOR AND THE FEED CONTROL SYSTEM FOR THE SELECTION
BELT DON'T GIVE POSITIVE RESULTS FOR THE MEXICAN
REFUSE,
G,- THE BELT CONVEYOR IN THE SEPARATION AREA TENDS TO
BUCKLE, AND IS TOO WIDE FOR THE MANUAL SELECTION OF
MATERIALS,
H,~ THE SPEED OF THE CONVEYOR IN THE SELECTION AREA, AS
DELIVERED BY THE MANUFACTURER/ WAS TOO FAST FOR THE
SCAVENGERS TO PROPERLY SELECT RECYCLABLE MATERIALS,
I,- THE BELT IN THE SELECTION AREA DID NOT HAVE THE LENGTH
TO GIVE THE NECESARY TIME TO GET THE SALVAGE
MATERIALS,
j,- THE PLANT'S TWO VERTICAL HAMMERMILLS ARE A SOURCE OF
CONSTANT MAINTENANCE PROBLEMS AND VERY EXPENSIVE
REPAIR COSTS, THE HAMMERS WEAR OUT VERY QUICKLY DUE TO
THE HIGH ABRASSIVENESS OF MEXICAN REFUSE, AND HAVE TO
BE REPLACED OR REVITALIZED ALMOST EVERY SHIFT,
547
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K,- MECHANICAL FAILURES OF THE DISTRIBUTION BRIDGE IN THE
PRE-DIGESTION FIELD CAUSES THE CONDITIONED REFUSE TO
RUN OUT OF CONTROL MAKING IT DIFFICULT TO MANAGE,
L,~ THE FINE MILLING MILL IS TOO SMALL FOR THE PLANT'S
PRODUCTION.
4.3,- OPERATION
A,- THE PLANT, NOT BEING DESIGNED FOR MEXICAN REFUSE, IS
HARD TO MAINTAIN, GENERATING SEVERE OPERATION
PROBLEMS, MAINLY IN CONVEYOR BELTS AND HAMMERMILLS,
B,~ THE ABSENCE OF A PROGRAM OF INCENTIVES FOR THE PEOPLE
IN THE SEPARATION BELT, CAUSES LOW EFFICIENCIES IN THE
SEPARATION OF THE MATERIALS,
C,~ THE HANDLING OF RECOVERED MATERIALS WAS NOT DONE
EFFICIENTLY, LOWERING THE PRICE OF THE SALVAGED
MATERIALS (DUE TO MIXING), AND INCREASING THE COSTS OF
OPERATION.
D.- NOISE LEVELS ARE HIGH IN THE SEPARATION AREA, PARTIALY
DUE TO THE KNOCKING OF THE MATERIAL WITH THE STEEL
HOPPERS AND WHEN THEY FALL TO THE LOWER FLOOR, ALSO
BECAUSE THE LACK OF ISOLATION ON THE HAMMERMILLS.
E,- THE LACK OF LABORATORY FACILITIES PRECLUDES THE
ADEQUATE CONTROL OF THE COMPOSTING PROCESS, (EXCEPTION
MEXICO CITY).
548
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V,- CONCLUSIONS AND RECOMENDATIONS
5,1,- CONCLUSIONS
A,- THE COMPOSTING PLANTS IN MEXICO HAVE NOT HAD THE
SUCCESS SALESMEN CLAIM,
B,- THE PART RELATED WITH THE SEPARATION OF RECOVERABLE
MATERIAL OUT OF THE REFUSE SHOW THAT WE NEED MORE
RESEARCH AND DEVELOPMENT TO IMPROVE A SEMI MECHANIZED
SEPARATION MORE IN ACCORDANCE WITH THE CHARACTERISTICS
OF MEXICAN WASTES.
c,- THE USE OF COMPOST AS A SOIL IMPROVEMENT AGENT IN SOME
OF SOILS FOUND IN MEXICO HAS GIVEN GOOD RESULTS,
D,~ THE OFFER OF COMPOST IS GREATER THAN THE DEMAND,
E,- THE SEPARATION OF MATERIAL ON ROUTE IN THE COLLECTION
TRUCKS HAVE A SERIOUS IMPACT IN THE ECONOMY OF THE
PLANTS,
F,~ THE HAMMERMILLS HAVE SERIOUS MAITENANCE PROBLEMS DUE
TO THE GREAT CONTENT OF ORGANIC MATTER,
G,~ THE LACK OF MARKETS MECHANISMS OF COMPOST DERIVED IN A
FAILURE OF SALES.
H,- THE ADMINISTRATION BY MUNICIPALITIES HAS NOT BEEN
EFFICIENT,
549
-------
5,2,- RECOMENDATIONS
A,- THE DECISSION TO INSTALL COMPOSTING PLANTS MUST BE
ASSESED BY EXPERTS ON THE BASIS OF REALISTIC TECHNICAL
AND ECONOMICAL FEASIBILITY STUDIES, AND NOT BECAUSE OF
SALESMEN BLUFF AND POLITICAN's DECISSIONS,
B,- A TRAINING PROGRAM MUST BE PROVIDED BY THE
MANUFACTURER PRIOR TO STARTING PLANT OPERATION.
C.~ THE SALVAGED MATERIAL MUST BE SEPARATED AND CLEANED TO
GET BETTER PRICES IN SALES,
D,- THE COMPOST MUST BE PRODUCED ACCORDING TO DEMAND.
E,- A GOOD PROGRAM OF MAINTENANCE AND INCENTIVES FOR THE
PERSONNEL IS A MUST, THE EXPERIENCE OF OTHER PLANTS
EXISTING UNDER SIMILAR CONDITIONS MUST BE TAKEN INTO
ACCOUNT,
F,~ IF IT IS IMPOSSIBLE TO AVOID THE PRESELECCION ON THE
COLLECTION TRUCKS DUE TO LABOR UNION PRESSURES OR
OTHER FACTORS, THE ADMINISTRATION OF THE PLANT MUST
BUY THE PRESELECTED MATERIALS.
G,- ONLY FOR REMARKS, THE COMPOST is NOT A FERTILIZER, IT
IS ONLY A SOIL IMPROVEMENT AGENT,
H.- THE COMPOSTING PLANTS ARE NO PANACEA, NO ONE IN MEXICO
HAS HAD ECONOMICAL BENEFITS, AS NOT EVEN OPERATION
COSTS HAVE BEEN RECOVERED.
I.- THE RECYCLING PROGRAMS IN MEXICO ARE INCREASING,
550
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J,- THE ECOLOGICAL CULTURE IS GROWING INTO THE POPULATION,
THIS DEMANDS THAT PUBLIC OPINION BE INFORMED OF REAL
ALTERNATIVES TO SOLVE PROBLEMS/ IN ORDER TO AVOID
FUTURE FIASCOS,
K,- THE GROWTH OF ECOLOGICAL CULTURE MUST BE TAKEN
ADVANTAGE OF, IN ORDER TO INCREASE THE PARTICIPATION
OF PEOPLE IN RECYCLING PROGRAMS,
L,- THE PLANTS COULD BE MANAGED AS AN ENTERPRISE, IF THE
DESIGN IS IN ACCORDANCE WITH THE KIND OF REFUSE
GENERATED IN MEXICO AND WITH TECHNOLOGIES THAT ADAPT
TO THE SOCIAL AND ECONOMICAL CONDITIONS OF THE
COUNTRY,
551
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A CRITICAL EXAMINATION OF THE RELATIONSHIP
BETWEEN CONVENIENCE AND RECOVERY RATES
IN RESIDENTIAL RECYCLING PROGRAMS
Mack Rugg and Sanjay Kharod
Camp Dresser & McKee Inc.
Edison, New Jersey
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
553
-------
It is almost universally assumed that if participation in a recycling
program is made more convenient, a higher rate of recovery will result. In
fact, this "convenience assumption" is so compelling that people readily
accept it without asking for supporting evidence. It is not surprising,
therefore, that very little evidence of the validity of the convenience
assumption has been developed. What is surprising, perhaps, is that when
quantitative analysis of recovery rates is performed, some of the results
cast doubt on the validity of the convenience assumption rather than
confirming it.
BACKGROUND FDR THIS PAPER
During 1989 Camp Dresser & McKee was retained by Morris County, New
Jersey to evaluate the recycling system in the county and recommend County
initiatives to optimize the system. The authors of this paper had primary
responsibility for the technical aspects of the Morris County study. One
of the issues in the study was whether households served by a countywide
collection system should be required to set out each targeted material in
separate containers. Another issue was how often the materials should be
picked up. This paper grew out of the Morris County study.
Sorted materials set out in multiple containers generally cost more to
collect than commingled materials set out in a single container. However,
sorted materials are worth much more than commingled materials. The value
gained by having residents sort their recyclable materials may be
substantially greater than the additional cost of collecting sorted
materials. With respect to collection frequency, cost per ton generally
decreases as collection becomes less frequent. This is because more
material is picked up for the same distance travelled. Therefore, the most
economical recycling program could be one in which completely separated
materials are picked up infrequently.
A major question is whether people will participate in such a program.
In an attempt to answer this question, the experience of the municipal
recycling programs in Morris County was evaluated.
Morris County is an affluent suburban county in north-central New
Jersey with a population of just over 400,000 persons. Essentially all
residential solid waste generated in the county passes through two transfer
stations with identical tipping fees of approximately $120 per ton.
Therefore, the economic incentive to recycle is similar throughout the
county.
A broad range of recycling programs is found among the 39
municipalities of Morris County. Collection frequency ranges from monthly
to twice weekly. Some municipal programs that provide collection of
recyclables require complete separation of materials at the curb, including
clear, brown and green glass. Other municipal programs allow complete
commingling of materials. Still other programs provide no pickup, relying
on residents to bring recyclable materials to dropoff centers.
Residential recovery rates for aluminum beverage cans and glass food
and beverage containers achieved by the municipal recycling programs in the
county were examined. Commercial recycling was excluded from this analysis
because (1) more than one approach to source separation is used by the
554
-------
private haulers serving the commercial sector in many municipalities, and
(2) even if only one approach is used in the commercial sector, it may not
be the same approach used in the residential sector. Aluminum cans and
glass containers were chosen for analysis because they are collected in all
municipalities in the county. Newspaper is also collected in every
municipality, but was excluded from the analysis because it is kept
separate from glass and aluminum in all programs.
RECOVERY RATES USING DIFFERENT APPROACHES TO SOURCE SEPARATION
Table 1 shows the combined recovery rates for glass containers and
aluminum cans achieved by groups of Morris County municipalities in 1988
using different approaches to source separation. All averages shown in
this table and in the other tables in this paper are weighted by
population. Boonton Borough has been excluded because its reported per-
capita residential recycling rate for glass and aluminum is almost twice as
high as the second highest municipality in the county. This indicates that
the recycling rate for Boonton Borough is so strongly influenced by factors
other than its approach to source separation that its inclusion in the
analysis would make the results less meaningful. Mount Arlington and Mine
Hill have been excluded for the opposite reason: the recovery rates in
these municipalities are so low that they cannot be considered reflective
of the approach to source separation used.
Table 1 indicates that, on average, Morris County municipalities
providing curbside collection achieved approximately the same residential
recovery rate whether they required complete sorting, partial sorting, or
no sorting by residents. The municipalities providing dropoff centers but
no curbside collection achieved an average recovery rate approximately 20
percent lower than those providing curbside collection. As shown by the
"highest recovery rate" column, individual municipalities achieved high
recovery rates using all four approaches. The high standard deviations
reflect the great variability within source separation categories.
It has been suggested that people higher on the socio-economic scale
are more likely to participate in recycling programs, and may also be more
willing to keep the various recyclable materials separate. Therefore,
according to this argument, the success of municipal programs requiring
complete sorting of materials may be a reflection of the affluence of the
residents of the municipalities that have implemented those programs.
As shown by table 1, the municipalities in Morris County that required
complete sorting of glass and aluminum by residents in 1988 have an average
per-capita income approximately 10 percent higher than that of the
municipalities that allowed their residents to commingle glass and
aluminum. However, both groups of municipalities are highly affluent.
Residential recovery rates were also examined in Middlesex County, a
mixed urban, suburban and rural county in central New Jersey with an
average income per capita 20 percent lower than that in Morris County.
Table 2 shows the residential recovery rates achieved by groups of
Middlesex County municipalities in 1988 using three different approaches to
source separation: curbside pickup of commingled materials, curbside
pickup of sorted materials, and dropoff centers with no curbside pickup.
Piscataway and South Brunswick were excluded from this analysis because
555
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TABLE 1
COMBINED GLASS AND ALUMINUM RECOVERY RATES ACHIEVED IN MORRIS COUNTY
IN 1988 USING DIFFERENT APPROACHES TO SOURCE SEPARATION (a)
01
Cfl
0)
Approach to
source separation
Curbslde, commingled
Curbslde, semi-sorted (b)
Curbslde, sorted (c)
Drop-off center only
Number
of
munici-
palities
6
4
14
12
Population
represented
(1988
estimate)
122,103
37,595
165,560
79,698
Average
income
per capita
(1985)
$17,462
$12,840
$19,220
$18,733
Average
recovery
rate
(Ib/cap/yr)
49.4
53.3
50.1
41.2
Highest
recovery
w* a 4- £j
(lb/cap/yr)
79.3
76.7
86.4
91.3
Lowest
recovery
rate
(lb/cap/yr)
34.4
39.9
29.4
20.8
Standard
deviation
14.9
13.8
17.2
19.3
(a) From residential sources only. Boonton Borough, Mt. Arlington, and Mine Hill not included.
(b) Mixed glass separated from aluminum.
(c) Glass separated from aluminum and sorted by color.
Sources: For source separation methods and amounts recovered—Morris County Municipal Utilities Authority and
municipal officials. For population estimates, New Jersey Department of Labor. For per-capita income, U.S.
Bureau of the Census.
-------
TABLE 2
COMBINED GLASS AND ALUMINUM RECOVERY RATES ACHIEVED IN MIDDLESEX COUNTY
IN 1988 USING DIFFERENT APPROACHES TO SOURCE SEPARATION (a)
Ul
01
-3
Approach to
source separation
Curbside, commingled
Curbslde, sorted (b)
Drop-off center only
Number
of
munici-
palities
9
7
7
Population
represented
(1988
estimate)
400,438
111,010
72,203
Average
income
per capita
(1985)
$13,059
$13,380
$15,019
Average
recovery
rate
(Ib/cap/yr)
33.7
39.9
32.2
Highest
recovery
rate
(Ib/cap/yr)
54.5
68.2
76.3
Lowest
recovery
rate
(Ib/cap/yr)
12.5
28.4
5.9
Standard
deviation
14.3
12.7
21.9
(a) From non-commercial sources only. Piscataway and South Brunswick not included.
(b) In six programs, glass was separated from aluminum and sorted by color. In one program,
glass was mixed but separated from aluminum.
Sources: For source separation methods and amounts recovered—Middlesex County Department of Solid Waste Management
For population estimates, New Jersey Department of Labor. For per-capita income, U.S. Bureau of the Census.
-------
they each used two different approaches to source separation during
significant parts of the year. In addition, aluminum recovery by Cranbury
was excluded because it represents 19 percent of the aluminum recovered in
the county even though Cranbury has less than 0.5 percent of the county
population. This indicates that Cranbury's aluminum recycling is primarily
the result of factors other than its approach to source separation.
As indicated by table 2, the Middlesex County municipalities that
required their residents to sort glass and aluminum achieved a slightly
higher average recovery rate than the municipalities that allowed residents
to commingle these materials. As in Morris County, the municipal programs
that did not provide curbside collection achieved the lowest average
recovery rate. However, also as in Morris County, the highest of all the
municipal recovery rates was reported by a municipality not providing
curbside collection. The high standard deviations reflect the great
variability within each source separation category.
In Middlesex County, the average income per capita is essentially the
same for municipalities that required sorting in 1988 and for those that
allowed commingling. Therefore, the higher average recovery rate achieved
by the municipalities requiring sorting cannot be explained based on
greater affluence in these communities.
Per-capita income is substantially lower in Middlesex County.than in
Morris County, and the average recovery rates are also substantially lower.
However, it would be a mistake to conclude without further analysis that
the difference in recovery rates can be explained by the difference in
incomes. In Middlesex County, residential solid waste is disposed of in
two in-county landfills where the tipping fees are approximately half the
tipping fee at the Morris County transfer stations. Lacking a landfill of
their own, Morris County residents are particularly mindful of the need to
develop alternatives to landfill ing.
To the south and east of Middlesex County lies Monmouth County, a
suburban and rural area with an average per-capita income slightly higher
than Middlesex but still significantly lower than Morris. An analysis of
the recovery rates achieved in Monmouth County using different approaches
to source separation was performed by Scott McGrath when he was with the
Monmouth County Planning Board (Mr. McGrath is now with Gannett Fleming,
Inc., King of Prussia, Pennsylvania). McGrath identified four degrees of
separation required by municipalities providing curbside collection of
glass containers, aluminum cans, and tin cans:
• Complete commingling, a one-container system.
• Commingling of glass with separation of aluminum and tin
cans, a three-container system.
• Commingling of aluminum and tin cans with separation of
glass by color, a four-container system.
• Complete separation of aluminum and tin cans and glass by
color, a five-container system.
558
-------
In analyzing data from the second, third and fourth quarters of 1988,
McGrath found that the greater the number of containers required, the
higher was the average per-capita recovery rate. When all four approaches
to source separation were compared using analysis of variance, the
differences among the average recovery rates were not found to be
statistically significant. However, statistical analysis (a two-sample "Z"
test) indicated that the average recovery rate achieved by the
municipalities using the five-container system was significantly higher
than the combined average recovery rate achieved by the municipalities
using the other three approaches.
It should be noted that McGrath was able to exclude only a portion of
the materials recovered from commercial sources from his analysis.
Therefore, it is reasonable to assume that some of the material credited to
each source separation system was actually recovered through different
systems used by private haulers in the same municipalities.
The year 1988 was the first full year in which recycling programs were
fully implemented in a large number of New Jersey municipalities.
Therefore, data from 1989 and subsequent years will be very significant to
the issues addressed in this paper. However, data from 1989 are still
preliminary if they are available at all.
Table 3 shows the same information as table 1, but based on
preliminary Morris County data for 1989. The preliminary data show the
commingling municipalities with an average recovery rate approximately 11
percent higher than the municipalities requiring complete separation. The
average per-capita incomes for these two groups of municipalities are quite
similar. The very low numbers for commingling and complete sorting in the
"lowest recovery rate" column indicate that the data may be incomplete. As
in 1988, individual municipalities in each source separation category
achieved high recovery rates.
RECOVERY RATES WITH DIFFERENT COLLECTION FREQUENCIES
The second major convenience factor examined in the Morris County
study was frequency of pickup. Table 4 shows average recovery rates
achieved by groups of Morris County municipalities using different
collection frequencies. Zero collections per month indicates that a
dropoff center is available but no curbside collection is provided.
The pattern of recovery rates is very similar to that in table 1.
Municipalities providing curbside pickup achieved essentially the same
average recovery rates whether pickup was weekly, monthly, or in between.
Municipal programs with no curbside collection recovered approximately 20
percent less material. Again, the high standard deviations reflect the
great variability within categories. Curiously, the municipalities
providing only one pickup per month had the highest average per-capita
income.
Table 5 shows the same information for Middlesex County. Here, the
two municipalities providing weekly pickup achieved a substantially higher
average recovery rate than the municipalities in the other three
categories. These two municipalities also have a somewhat higher average
559
-------
TABLE 3
COMBINED GLASS AND ALUMINUM RECOVERY RATES ACHIEVED IN MORRIS COUNTY
IN 1989 USING DIFFERENT APPROACHES TO SOURCE SEPARATION (a)
Wl
8
•
Approach to
source separation
Curbslde, commingled
Curbslde, semi-sorted (b)
Curbslde, sorted (c)
Drop-off center only
Number
of
munici-
palities
10
2
17
7
Population
represented
(1988
estimate)
159,858
15,074
177,496
52,528
Average
income
per capita
(1985)
$16,798
$11,970
$17,764
$22,297
Average
recovery
rate
(Ib/cap/yr)
50.7
70.8
45.5
43.2
Highest
recovery
rate
(Ib/cap/yr)
88.7
83.9
93.6
84.1
Lowest
recovery
rate
(Ib/cap/yr)
17.2
69.8
8.9
29.6
Standard
deviation
19.6
7.0
20.4
18.7
(a) From residential sources only. Boonton Borough, Mt. Arlington, and Mine Hill not included.
(b) Mixed glass separated from aluminum.
(c) Glass separated from aluminum and sorted by color.
Sources: For source separation methods and amounts recovered—Morris County Municipal Utilities Authority.
For population estimates, New Jersey Department of Labor. For per-capita income, U.S. Bureau of the Census.
-------
TABLE 4
COMBINED GLASS AND ALUMINUM RECOVERY RATES ACHIEVED IN MORRIS COUNTY
IN 1988 USING DIFFERENT COLLECTION FREQUENCIES (a)
Ol
p
Collections
per
month
*
0"
1
2
4
Number
of
munici-
palities
12
13
4
7
Population
represented
(1988
estimate)
79,698
152,588
53,606
119,064
Average
income
per capita
(1985)
$18,733
$19,256
$16,249
$15,697
Average
recovery
rate
(Ib/cap/yr)
41.2
49.8
51.6
50.0
Highest
recovery
rate
(Ib/cap/yr)
91.3
76.4
76.7
86.4
Lowest
recovery
rate
(Ib/cap/yr)
20.8
29.4
39.9
32.2
Standard
deviation
19.3
15.3
13.2
18.6
(a) From residential 'sources only. Boonton Borough, Mt. Arlington, and Mine Hill not included.
« ! ect1?n f recluen<:jes and amounts recovered-Morris County Municipal Utilities Authority and
Buea of the Census P°Pulat1on estimates, New Jersey Department of Labor. HFor per-capita income; U.S.
-------
TABLE 5
COMBINED GLASS AND ALUMINUM RECOVERY RATES ACHIEVED IN MIDDLESEX COUNTY
IN 1988 USING DIFFERENT COLLECTION FREQUENCIES (a)
01
05
(0
Collections
per
month
0
1
2
4
Number
of
munici-
palities
6
4
11
2
Population
represented
(1988
estimate)
70,930
80,008
370,113
62,600
Average
Income
per capita
(1985)
$15,724
$12,353
$13,045
$14,540
Average
recovery
rate
(Ib/cap/yr)
32.3
39.5
31.7
49.3
Highest
recovery
rate
(Ib/cap/yr)
76.3
52.2
68.2
54.5
Lowest
recovery
rate
(Ib/cap/yr)
5.9
25.1
12.5
42.5
Standard
deviation
22.7
11.2
15.6
6.0
(a) From non-commercial sources only. Plscataway and South Brunswick not included.
Sources: For collection frequencies and amounts recovered—Middlesex County Department of Solid Waste Management.
For population estimates, New Jersey Department of Labor. For per-capita income, U.S. Bureau of the Census.
-------
per-capita income than the municipalities providing one and two pickups per
month.
Table 6, like table 3, is based on preliminary Morris County data from
1989. Frequency of pickup is still inversely proportional to average
.income, the opposite of the pattern in Middlesex County. The six
municipalities providing at least weekly pickup achieved higher average
recovery rates than the other groups of municipalities despite having lower
average incomes. Nonetheless, the most affluent group achieved a
comparable average recovery rate with only one pickup per month. This
group also included the municipality with the highest recovery-rate in the
county.
The standard deviations in tables 3 and 6 are particularly high
because of very low recovery rates for some municipalities. This is
probably an indication of incomplete data.
CONCLUDING DISCUSSION
The Morris County and Middlesex County data evaluated in this paper do
not indicate that allowing residents to commingle recyclable materials
increases recovery rates. The data contain a suggestion that frequent
pickup may tend to increase recovery rates, but are far from conclusive on
this point. Individual municipalities in Morris County have achieved high
recovery rates using a variety of approaches to source separation and the
full range of collection frequencies.
If there is a message for recycling planners in the data from Morris
and Middlesex counties, it is that they should give serious consideration
to the less convenient but more economical forms their programs could take.
Local, county, and regional officials should continue to design programs
that reflect the specific circumstances of the municipalities they serve.
They should not narrow their options by assuming that a recycling program
must be convenient to succeed.
563
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TABLE 6
COMBINED GLASS AND ALUMINUM RECOVERY RATES ACHIEVED IN MORRIS COUNTY
IN 1989 USING DIFFERENT COLLECTION FREQUENCIES (a)
Ul
2
Collections
per
month
0
1
2
4
8
Number
of
munici-
palities
5
17
8
5
1
Population
represented
(1988
estimate)
37,558
162,414
110,997
91,541
2,446
Average
Income
per capita
(1985)
$19,167
$19,523
$16,573
$15,096
$14,211
Average
recovery
rate
(Ib/cap/yr)
43.8
49.0
43.6
54.2
51.1
Highest
recovery
rate
(Ib/cap/yr)
84.1
93.6
75.6
88.7
51.1
Lowest
recovery
rate
(Ib/cap/yr)
29.6
11.0
8.9
35.0
51.1
Standard
deviation
19.0
20.5
19.1
22.1
0.0
(a) From residential sources only. Boonton Borough, Mt. Arlington, and Mine H111 not included.
Sources: For collection frequencies and amounts recovered—Morris County Municipal Utilities Authority.
For population estimates, New Jersey Department of Labor. For per-capita income, U.S. Bureau of the Census.
-------
CUYAHOGA FALLS, OHIO'S INTEGRATION OF RECYCLING
INTO SOLID WASTE COLLECTION
Patricia J. Smith
President, Waste Options
Presented at the the
First U.S. Conference on Municipal Solid Waste
June 13-16, 1990
565
-------
CUYAHOGA FALLS OHIO'S INTEGRATION OF RECYCLING
INTO SOLID WASTE COLLECTION
In Cuyahoga Falls, Ohio, like many other municipalities,
we are changing our solid waste system to minimize the impact
of skyrocketing disosal costs and to simultaneously protect
the environment.
At the cornerstone of our new solid waste system is a
voluntary, aggressive recycling comprehensive program that is
integrated with the City's regular solid waste collection
program.
Our successful recycling programs are not a panacea for
the problems associated with solid waste disposal, but are
ones that we can leave behind to make a better quality life
for future generations.
Over 70% of Cuyahoga Falls residents now participate in
recycling efforts and our City has diverted over 2,000 tons
of recyclables from the waste stream in one year's time. The
City has avoided paying over $70,000 in disposal costs!
In Cuyahoga Falls we don't want to be remembered as the
throw-away generation that left our children a legacy of over
indulgence and wasteful practices. But rather we have chosen
to be remembered as the residents who sacrificed short-
term convenience for long-term protection of the health and
environment of the future.
566
-------
OUTLINE
I. Overview of Solid Waste Dilemma
II. Discussion on landfill/waste-to-energy options
III. Reasons for integrating recycling into comprehensive
solid waste management plans
IV. Overview of successful, aggressive public
awareness/education campaign
a. media blitz; brochures, flyers, door-hangers
b. costumed characters; puppet shows
c. door-to-door efforts
d. school skits, assemblies, film strips, videos
e. recycling Olympics
567
-------
DESIGN OF MATERIALS RECOVERY FACILITIES (MRFs)
George M. Savage
Cal Recovery Systems, Inc.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16,1990
569
-------
Abstract
The explosion in the demand for materials recovery facilities (MRFs) is straining the
solid waste industry in terms of supplying reliable, efficient, and cost-effective recyclables
processing systems. The design of MRFs is discussed, including the design criteria for th«
facilities, the available equipment, and system performance. The topic is approached in a
broad context, addressing the processing of feedstocks in the form of singular recyclabte
components, of commingled recyclables, and of mixed municipal solid wastes.
570
-------
Introduction
The design of a materials recovery facility (MRP) follows a series of basic considera-
tions, which generally include the following:
1. Identifying the characteristics of the wastes to be processed.
2. Maximizing recovered product quality.
3. Maximizing diversion of wastes from landfill.
4. Utilizing proven system concepts.
5. Provision for receipt of municipal solid waste (MSW), based on the types and fre-
quency of vehicles delivering the material.
6. Utilizing manual labor for those operations where current automation technology is
lacking, unproven, or but marginally effective.
7. Establishing the throughput capacity, required availability, and desired redundancy
for the system.
Materials recovery facilities can be classified into two general types based on the
characteristics of the input municipal solid waste; namely source-separated or mixed.
Taken here, source-separated wastes refer to those that are collected in singular (i.e., seg-
regated) components or in commingled form (a mixture of several components, e.g., metal
and glass containers). Mixed wastes are not separated prior to collection and obviously
such a mixture contains numerous components.
Source-separated recyclables do not suffer from the higher degree of contamination
from food wastes and other contaminants exhibited by recyclables in mixed MSW. Thus,
571
-------
the percentage recovery of recyclables from source-separated wastes is substantially
greater than that from mixed wastes.
The following discussion considers first the design of a MRF for processing source-
separated materials. Subsequently, the design of a MRF for processing mixed MSW is
considered.
Source-Separated MSW
Process flow diagrams for a 120TPD materials recovery facility project are shown in
Figures 1 and 2, respectively, for a paper processing line and a container processing line.
Each of these flow diagrams is also a mass balance showing the tonnages of the various
recyclables as they enter and exit the system.
The process design in this example assumes that 25% of the available recyclables
arrive at the facility in pre-segregated, singular form (e.g., tin cans) and that the remaining
75% is commingled. Each of the flow diagrams shows provision for redundancy in receiv-
ing, sorting, and processing.
Breakage and contamination generally amount to approximately 7 to 10% of the in-
feed total. Glass breakage during collection and material handling at the facility results in
the loss of small particles of glass as residue, if markets for mixed colored cullet are not
available. Contamination must be removed within the ranges dictated by the market speci-
fications. Common contaminants include corrugated and magazines included with resi-
dential newspaper collections, and low-grade paper (such as envelopes with windows) in
commercial high-grade paper collections.
572
-------
FROM 54.9.
MIXED PftPER 1
COLLECTION
COMMINGLED
PAPER
tn
-j
GO
1.8
4.3
O.C.C.
NEWS
MAG.
t
REJECTS
7.32
REJECTS
SORTING STATION
0. C. C.
MAG.
NEWS
1 ' 52.29
O.C.C. | MAG.
SORTING STATION
HEWS
REJECTS
t
10.97
15.39
Figure 1. Paper Processing Line / Design Capacity = 75 TPD
75X CoHMingled Collection
25x Segregated Collection
-------
Oi
-3
2.62
REJECTS
SEGREGATED
GLASS
8.60
SORTING STATION
REJ. | GRN | AI1B | FLT | MXD
1
1
i
f
i
^
1 i
L J
' 1
L J
f 1
k .
1
L*
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k
REJ. I GRN | AMB I FLT I hXD j*T
SORTING STATION
0.10
I
GRANULATOR
LASS
CRUSHERS
7.8
»• AM
6.48
MXD
PRODUCTS
REJ.
SORTING STATION
PET
GRN CLR
HDPE
MILK N/M
ALUM.
1.48
ALUM,
.08 1.33 .81 Tl-21
EH d3 EH EU GAV LORDS
GRN CLR MILK N/M
PET HDPE
-------
Figure 3 is an example plan view of a facility matching the flow diagrams described
above. The facility is designed to provide a high level of redundancy, both in paper pro-
cessing and in container processing.
For the paper line, two receiving pits are shown and each line is capable of handling
either the maximum anticipated mixed paper waste or the maximum anticipated segregated
paper waste.
Similarly, for the container line, three receiving pits are shown. Two of the lines are
totally redundant, with each capable of handling either the maximum anticipated mixed
container waste or the maximum anticipated segregated container waste. The third line is
provided to handle segregated plastic and aluminum containers exclusively.
The tipping floor and product storage areas are sized for a minimum of one day's
storage of all materials.
This particular design provides for a facility with a minimum risk of downtime result-
ing from equipment failure. However, the provision of extensive redundancy is expensive.
Substantial economies may be realized by eliminating redundant processing capability and
operating on at least a two-shift basis. However, in any plant, machinery can and will break
down. In the case of a plant with little or no redundancy, plans must be in place regarding
how to meet anticipated breakdowns to minimize the effect of an outage.
Mixed MSW
Recyclable materials can be recovered in a mixed MSW processing facility. Such
materials recovery facilities segregate and recover the recyclable components from the het-
erogeneous-mixture MSW. As opposed to MRFs processing commingled and segregated
575
-------
r I
200'
CJl
-J
0)
CONTAINER
TIPPING
FLOOR
PAPER
TIPPING
FLOOR
ires
240'
II OFFICE
FE
t
RES 11
i
>UE
L
LCKR.fl
= I
GLASS
STORAGE
SORT IN6
PLATFORM
4O
FT
T
R
A
I
L
E
R
DENS IFIER
D D GAVLORDS
D D
BALER
BALER
FT
TRA1LERS
DOCK
LOADING
= 1. J
-------
components wherein 90% or more of the input materials are recovered in the form of mar-
ketable end-products, MRFs processing mixed MSW can recover approximately 10 to 20%
of the input in the form of marketable grades of metals, glass, plastics, and paper.
Additional resource recovery can be achieved by integrating into the facility design addi-
tional processing operations to recover refuse-derived fuel (RDF) or a compostable feed-
stock. These options for integration can increase the total diversion to within the range of
75 to 85% if markets for the other materials exist.
An example of a materials recovery facility design configured for the primary pur-
pose of processing and recovering recyclable materials from mixed municipal solid waste,
including ferrous, HOPE, PET, aluminum, and several grades of paper, is presented in
Figure 4. The processing capacity is assumed to be 50 TPH. The processing system in-
corporates both mechanical and manual separation processes in order to optimize the re-
covery of marketable secondary materials. The design recovers approximately 15% of the
input mixed waste in the form of marketable grades of recyclables.
Wastes are assumed delivered to the facility via transfer trailers or refuse collection
vehicles. A description of the facility design follows.
Wheel loaders and a picking crane are employed to remove large, heavy objects
and other nonprocessibles from the waste stream prior to the waste entering the process-
ing equipment.
Provision is made in the facility to segregate corrugated and other marketable waste
paper grades by wheel loader that arrive in loads of waste composed predominantly of pa-
per materials. When sufficient corrugated or other paper grades are removed on the tip
577
-------
CD
PRESORTED OCC « HQ
-t
INFEED
-t
CORRUGATED
NONPROCESSIBLE
HASTE
SORT
Fe
u
MPERF IN-
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a r
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ll
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^
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Fe
GLASS REJECTS
REJECTS
1. 4
1. 0
0. 4
41. 4
BALED
PRODUCTS
5. 8
-------
ping floor by wheel loader and accumulated, the materials are transported directly to a
baler, bypassing the mixed waste processing equipment.
Mixed MSW is introduced to a two-stage primary trommel, with the first stage under-
size material passing by a magnetic separator for ferrous extraction. The resulting process
residue is routed to the output residue stream.
The primary trommel second-stage unders pass through a magnetic separator,
where the ferrous is removed and conveyed to a sorting station. At the sorting station, fer-
rous from the trommel oversize material extracted by a magnetic separator joins the ferrous
extracted from the second-stage trommel unders. Ferrous cans are sorted from other fer-
rous and sent to a can processing subsystem to provide a product with minimal contami-
nation.
After passing through a magnetic separator, the primary trommel overs are con-
veyed to a second sorting station where HOPE, PET, aluminum, cardboard, and various
paper grades are manually separated. When sufficient quantities of these materials are ac-
cumulated, they are processed by one of two balers. The second baler serves as a compo-
nent of processing redundancy for the facility.
A third sorting station receives undersize from the second stage of the primary
trommel after ferrous removal. HOPE and PET containers are manually sorted at this sta-
tion, as well as aluminum and some high-grade paper. The remaining waste joins the
waste from the sorting station processing the trommel oversize stream.
Substantial manual sorting is utilized for segregation of plastics and aluminum be-
cause manual sorting is efficient for recovering the various plastic polymers and aluminum
beverage containers and because of the opportunity for employment development.
579
-------
Additionally, mechanical and electro-mechanical separation systems for plastic polymers
and aluminum materials are developmental for waste processing applications.
Process residues account for about 85% of the incoming solid waste. Much of the
process residues are combustible and biodegradable organic materials. These materials
require landfill disposal unless processed for energy recovery or converted to a com-
postable feedstock for subsequent composting. For example, if refuse-derived fuel recov-
ery is integrated with materials recovery, the residue stream could be reduced to 15 to 25%
of the input MSW.
Conclusions
The design of materials recovery facilities is dependent upon a number of consider-
ations. One key consideration in the selection of appropriate facility designs is the form of
the delivered feedstock, i.e., source-separated recyclables or mixed municipal solid waste.
A second key consideration is the level of recycling or waste diversion that is required.
Source separation programs (i.e., collection and processing) may achieve 20 to 30% diver-
sion, while mixed waste processing may be required if diversion goals are 30% or greater.
Of course, markets must be available for the recovered products in either case.
The impetus toward greater rates of waste diversion from landfills places a greater
burden on the designer to efficiently and cost-effectively process and recover additional
components of the waste stream. This paper has presented the rationale of process de-
sign and examples of facility designs to illustrate the variety of processing means available
to achieve waste diversion.
580
-------
THE DEVELOPING ROAD OF MATERIAL RECOVERY
FACILITIES IN MUNICIPAL SOLID
WASTE MANAGEMENT
Mitchell Kessler, Eastern Regional Director
Resource Integration Systems Ltd.
Presented at the
First U. S. Conference on Municipal Solid Waste Management
June 13 - June 16,1990
581
-------
TAKE ADVANTAGE OF ECONOMIES OF
SCALE:
- Collect large volumes from
various generators
- Increase processing efficiency
• PRODUCE LARGE VOLUMES OF HIGH
QUALITY, HIGH VALUE PROCESSED
MATERIALS
SECURE STABLE, LONG-TERM
MARKETS
582
-------
FACILITIES DESIGNED AND EQUIPPED TO
• ACCEPT COMMINGLED AND SOURCE-
SEPARATE RECYCLABLES
• ACCEPT RECYCLABLES FROM VARIOUS
GENERATORS
•SEPARATE AND/OR PROCESS
RECYCLABLES
• UPGRADE RECYCLABLES TO MEET
MARKET SPEC IFICATIONS
• MARKET PROCESSED MATERIALS
583
-------
SITE AVAILABILITY
VEHICLE ACCESS
INDUSTRIAL LOCATION
AESTHETICS
584
-------
> BUILDING
> PROCESSING CAPACITY
- Fibre
- Commingled Containers
•RECEIVE MATERIALS AS COLLECTED:
- Fibre
- Commingled Containers
- Source Separated
TIPPING AREAS
• PROCESSING LINES
> STORAGE
» SHIPPING
585
-------
PUBLICLY OWNED AND OPERATED
PUBLICLY OWNED AND
PRIVATELY OPERATED
PRIVATELY OWNED & OPERATED
586
-------
• RESPONSIBLITY &
ACCOUNTABILITY
RISK AND REVENUE
CONSTRAINTS &
OPPORTUNITIES
587
-------
LEGISLATIVE POLICY
- Mandatory Programs
- Taxes/Bans
- Deposit Laws
- Waste Management Hierarchy
MARKETS & PRICES
- Supply & Demand
- Import & Export
- Regional Marketing
- Procurement
TECHNOLpGICAL DEVELOPMENT
- Recyclability
- Rapid Evolution
- Mixed Waste Recycling
- Packaging
TRANSPORTATION & DISPOSAL
COST
- Tipping Fees
- Long Haul
- Environmental Impacts
588
-------
ECONOMIC FEASIBILITY OF RECYCLING IN THE MIDWEST:
RECYCLING ALTERNATIVES IN OKLAHOMA
Robert E. Deyle and Bernd F. Schade
University of Oklahoma
Science and Public Policy Program
Presented at the
First U.S. Conference on Municipal Solid Waste
U.S. Environmental Protection Agency
June 13-16, 1990
589
-------
Introduction
EPA's Agenda for Action proposes a national goal of
reducing municipal solid waste by 25 percent through source
reduction and recycling.1 This goal is reflected in recently
proposed amendments to the federal Resource Conservation and
Recovery Act (RCRA) ,2 but it is not yet clear how this goal
will be operationalized through federal mandates or incentives
to states or municipalities. It is likely, however, that the
costs of achieving such reductions could vary substantially
among regions of the country.
In most municipalities in the Northeast, the added costs
of recycling are more than balanced by recycling revenues and
the avoided costs of diverting wastes from landfills and
incinerators. Tipping fees in this region average $45 per ton
and range as high as $120 per ton.3 Outside the densely
populated eastern states, however, the cost-effectiveness of
recycling is less obvious. Average land disposal costs range
from $13 to $16 per ton in states such as California, Texas,
and Colorado, and suitable sites for additional landfills are
more plentiful.
If federal legislation requires all states to adopt a 25
percent waste reduction goal and mandate recycling programs at
the municipal level, political opposition could be substantial
in municipalities where a substantial increase in solid waste
management costs will result. If the federal law exempts
municipalities that can show that recycling is less cost-
effective than other means of solid waste management,
achieving a 25 percent waste reduction goal may be very
difficult. Under either approach, substantial financial
incentives may be necessary to offset some of the initial
costs of municipal recycling programs if waste reduction goals
are to be achieved at the national level.
This paper offers a basis for assessing how achievable
such a national goal might be in western and midwestern
states. We present the results of a comparative assessment of
the cost-effectiveness of curbside recycling and yard waste
composting versus current land disposal systems in four
communities in Oklahoma. The results also offer a means of
estimating the level of financial subsidy that might be
required as an incentive for promoting recycling in
communities where land disposal remains more cost-effective.
Analyses were also conducted of municipal recycling
options that rely on voluntary drop-off sites or buy-back
centers. These typically achieve very low diversion rates on
the order of 0.5 to 3.3 percent of the total municipal solid
waste stream. Results of these analyses are not discussed
here because of space limitations and the relatively low
impact they are likely to have on achieving waste reduction
590
-------
goals. For details, see Deyle and Schade (forthcoming).A
Methodology
This study uses 20-year "life cycle" costs, or net
present values, to compare the cost-effectiveness of curbside
recycling and yard waste composting with continued operation
of the current solid waste management system in each of the
four case communities.5 Community-specific data on current
solid waste management systems are analyzed along with data
from curbside recycling and yard waste composting programs in
other communities across the country. Values for many of the
cost and revenue variables extend over a substantial range.
Therefore, base analyses were conducted using mid-range
values, and sensitivity analyses were performed to assess the
effects of varying individual variables.
Case Study Communities
The case study communities were selected to represent the
range in conditions that characterize municipal solid waste
management in Oklahoma. As shown in Table I, they range in
size from the rural town of Fairview, with a population of
3,200, to Oklahoma City, the state's largest metropolitan
area. Land disposal costs range from less than $8.00 per ton
to about $12.50 per ton. Each of the communities has
municipal collection of residential solid waste, with the
exception of a portion of Oklahoma City that is served by a
private hauler. Three of the communities use commercial
landfills to dispose of their wastes. Fairview uses a
regional facility operated by a public authority.
The Recycling Scenarios
For each of the communities, the life cycle cost of
operating the existing municipal collection and land disposal
system over a 20-year period, beginning in 1990, is compared
with the life cycle costs of two recycling options:
(1) adding a municipal curbside recycling program to the
existing solid waste management system and processing the
recovered materials at a municipal materials recovery
facility (MRF), and
(2) adding a separate curbside collection program for yard
waste and composting the yard waste at a municipal
facility.
591
-------
Table I. Case study communities.
Name of community
Oklahoma City
Norman
Owasso
Fairviev
Population of the service area 447,850
Number of households in the
service area 130,000
Annual waste generation (tons) 428,000
Proportion of residential waste
in the total waste stream 41.6%
Salary of collection workers
including fringe benefits $20,400
($/year)
Average distance travelled per
collection vehicle (once weekly
pickup) (miles) 7,982
Number of garbage trucks used 33
Unit costs of waste collection $38.20
($/ton)
Remaining landfill capacity
(years) 12
Landfill ownership private
Average round trip time from a
waste generation district to the
processing facility (minutes) 45
Tipping fee in 1990 ($/ton)
(if private landfill) $7.69
Unit costs of waste disposal
($/ton)(if public landfill) $0.00
79,500
12,000
18,550 3,500
65,800 18,607
36.0%
35
24.1%
2,919 8,060
19 2
$81.78 $71.00
9 12
private private
10
$12.48 $12.00
3,200
1,308
3,276
71.01
$23,300 $16,433 $23,000
5,200
1
$27.84
$0.00
$0.00
public
50
$0.00
$8.79
592
-------
Twenty years was selected as the period of analysis to
account for the savings that will result by diverting wastes
from disposal and extending the capacity of a municipally-
owned landfill. The materials included in the curbside
recycling scenario are aluminum cans, glass containers, and
newspapers. Plastics and tin cans were excluded because of
the current lack of firm markets in this region. It is
assumed the curbside program involves weekly collection of
commingled materials using dedicated recycling vehicles
operated by a one-person crew. The city provides single
recycling containers to each household served by the
residential MSW collection system. Processing at the
municipally owned and operated MRF includes crushing of
aluminum cans and color-separated glass, and baling of
newspapers.
The composting scenario assumes that yard wastes,
including grass, leaves, and prunings, are picked up weekly on
a separate day from other household refuse using existing
packer trucks. Yard wastes are assumed to be placed at the
curb in plastic bags that must be opened manually prior to
composting. The composting operation is assumed to be a low-
technology system that uses a front-end loader to create and
turn windrows.
Life Cycle Cost Analysis
Life cycle cost analyses were conducted using a Lotus
program designed for the project. The life cycle cost of a
solid waste management system is the sum of the discounted net
annual costs over the period of analysis. The net annual
costs are the sum of the annualized capital and operating
costs minus revenues. Costs and revenues in years beyond the
base year are inflated using specific inflation rates for such
cost components as labor, vehicles, fuel, and utilities. The
formula for calculating life cycle cost can be represented as
follows:
LCC = S [A + PC * fl+c,)(n'1> - REV * fl+c..l
-------
The annualized capital costs (A) are the sum of costs to
retire the debt for initial capital expenditures and payments
to a reserve fund for replacing equipment. It was assumed
that municipalities issue general obligation bonds to pay for
the initial capital costs of recycling. For a more detailed
explanation of how these cost components were calculated, see
Schade and Deyle (in preparation).6
Cost Components
The individual cost components for a solid waste
management system include the following:
- MSW collection and transport
- MSW disposal
- curbside collection of recyclables or yard waste
- processing recyclables or composting yard waste
- revenues from recovered materials.
Cost components for the existing municipal solid waste
management system only include MSW collection and transport
and MSW disposal. The recycling and composting scenarios
include these costs, adjusted to account for the diversion of
materials into the recycling system, plus costs for curbside
collection of recyclables or yard waste, operation of the
processing or composting facility, and promotion of the
collection program. The recycling and composting systems also
include revenues from the sale of recovered materials.
The individual variables employed in the analysis are
listed in Table II. For some variables a range of values was
used, either because the values are subject to fluctuation
over time (for example market prices for recovered materials)
or because it was not possible to generate a single value from
the available data (for example the unit costs of operating a
MRF). Data on the solid waste management systems in the four
communities were obtained through interviews with municipal
officials. Data for the cost components of the recycling and
composting options were obtained through interviews with
private-sector recyclers, MRF operators, officials in
communities in Oklahoma and other states with existing
recycling and yard waste programs, and equipment vendors.
Some cost and operational data were derived from published
literature.7 For a detailed discussion of data sources see
Schade (1989) .8
594
-------
Table II. Life cycle cost variables.
Variable Description
Range
Waste Diversion Rate Factors
Residential waste composition
(% by weight)
Aluminum cans
Glass containers
Newspaper
Yard waste
Recycling rates (%)
Aluminum cans
Glass containers
Newspaper
Yard waste
Processing losses at the MRF (%)
Aluminum cans
Glass containers
Newspapers
1.1
7.7
9.0
7.7
3
10
15
70
3.9 %
12.9 %
15.0 %
19.3 %
7
32
58
95
5 %
30 %
5 %
MSW Collection Costs
Annual waste generation (tons)
Proportion of residential waste in
the municipal waste stream (%)
Unit costs of collection ($/ton)
Collection cost savings from recycling
(% of waste diversion rate)
Collection cost increase with separate
yard waste collection
community-specific1
community-specific
community-specific
0, 70, 90 %
0 - 25 %
MSW Disposal Costs
Private landfill: 1990 tipping fee
($/ton)
Public landfill: 1990 annualized
capital and operating costs ($)
community-specific
community-specific
See Table I.
595
-------
Table II.
continued
Variable Description
Range
Unit cost of disposal after
Subtitle D regulations in effect
($/ton)
$18 - $21/ton
Costs of Curbside Collection of Recvclables
Weekly set-out rate (%)
Density of recycled materials (tons per
cubic yard)
Aluminum cans
Glass containers
Newspaper
Public promotion costs ($ per
household per year)
Workhours per week (hours)
Break time per week (minutes)
Capacity of recycling truck
(cubic yards)
Price of recycling truck
Fuel consumption of recycling truck
(miles/gallon)
Diesel fuel price ($/gallon)
Maintenance costs for recycling truck
($/year)
Productivity of recycling
truck (stops passed per hour)
Useful life of recycling truck
(years)
Capacity of pickup truck-trailer
(cubic yards)
Price of pickup truck-trailer
Fuel consumption of pickup truck-
trailer (miles/gallon)
20 - 70
0.037 tons/cy
0.500 tons/cy
0.275 tons/cy
$0.75 - $1.50
40 hrs
150 min
15 cy
$37,000
3.8 mpg
$0.65/gal
$5/200/yr
85,100,165 stps/hr
9 yrs
14.25 cy
$11,000
18 mpg
596
-------
Table II.
continued
Variable Description
Range
Gasoline price ($/gallon)
Maintenance costs for pickup truck-
trailer ($/year)
Productivity of pickup truck-
trailer recycling vehicle
Useful life of pickup truck-
trailer (years)
Unloading time of recycling
vehicle (minutes per trip)
Price of recycling container
Useful life of recycling container
Bond term for recycling equipment
Processing of Recyclables
Unit capital costs ($ per ton
of daily capacity)
Unit costs of operation ($/ton)
Minimum MRF size (tons per day)
MRF design life (years)
Yard Waste Composting
Unit capital costs ($ per ton
of daily capacity)
Unit costs of operation ($/ton)
Minimum facility size (tons per day)
Debagging costs ($/bag)
Compost weight reduction (%)
$0.73/gal
$850/yr
69,78,113 stps/hr
9 yrs
10 min
$4.50
9 yrs
9 yrs
$10,000 - $38,500
$20 - $30/ton
5 tpd
10, 17, 25 yrs
$7,600 - $13,800
$3.60 - $22.50
7 tpd
$0.02 - $0.04
30 - 50%
597
-------
Table II. continued
Variable Description Range
Recovered Materials Revenues
Materials sales prices ($/ton)
Aluminum cans $ 800 - 1,514
Glass containers $ 70 - . 80
Newspaper $ 15 - 65
Compost $ 0 - 4
Financial Variables
Interest and discount rate 8.00, 8.25, 9.25 %
Inflation rate (gross national product) 3 - 4 %
Inflation rate (labor) 3.6 - 4.6 %
Inflation rate (vehicles and equipment) 2.4 - 3.4 %
Inflation rate (machinery and equipment) 3.0 - 4.0 %
Inflation rate (fuel and utilities) 3.7 - 4.7 %
Backup factor for labor 1.2
Overhead (percent of total annual costs) 15 %
598
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Waste Diversion Rates. The amount of waste that is
diverted from the waste stream through recycling is dependent
on three variables: (1) waste composition, (2) recycling
rates, and (3) processing losses at the MRF. Estimates of the
composition of residential waste were derived from recent
studies in Missouri and several other states in the absence of
data for any communities in Oklahoma. Recycling rates are
defined as the proportion of the total amount of a material in
the waste stream that is collected from the public. This
parameter is dependent on participation rates and recovery
rates, i.e. the percent of recyclables actually set at the
curb by a participating household. Processing losses at a MRF
result from contamination of a portion of the collected
materials and, in the case of glass, losses from breakage
during collecting and handling.
The amount of each material that is finally diverted from
the residential waste stream is calculated by multiplying the
total tonnage of residential waste by the proportion of the
commodity in the residential waste stream and the recycling
rate, and then subtracting the estimated processing loss. The
total waste diversion rate for the composite municipal solid
waste stream is calculated by dividing the tons of all
materials diverted from the waste stream by the total tonnage
of residential and commercial waste managed in the municipal
system.
MSW collection costs are the product of the total amount
of residential MSW generated in the service area and the unit
cost of collection. If a proportion of the waste is diverted
through recycling, the MSW collection costs may be reduced.
This collection cost savings is calculated as a proportion of
the waste diversion rate. Data from studies in Rhode Island
suggest that collection costs decrease in an amount ranging
from 70 to 90 percent of the diversion rate. A lower bound
of zero is included for a worst-case assumption. This may
apply in smaller communities where the net reduction in waste
volume is insufficient to eliminate at least one truck and
crew from the collection system. For yard waste collection
programs, there is typically a net increase in total MSW
collection costs, on the order of 8 to 25 percent, with the
addition of separate yard waste collection service. Under
optimal conditions, it may be possible to break even.
MSW disposal costs are calculated differently for private
and public landfills. For a private landfill, disposal costs
are the product of the tipping fee paid by the municipality
and the amount of residential waste disposed. No extension of
landfill capacity is assumed to result from recycling where
the landfill is privately owned. We assume that private
operators would compensate for reductions in waste disposal
from one source by seeking additional wastes from other
599
-------
sources, since their earnings are a function of the volumes of
waste they handle.
Where the community operates its own landfill, we assume
the annual operating costs are fixed and that recycling does
not result in immediate reductions in disposal costs.
However, reduced waste disposal is assumed to extend capacity,
thus postponing the higher unit costs of constructing and
operating a new landfill or landfill cell in compliance with
the more stringent standards to be imposed under the federal
Subtitle D regulations.11 The new landfill is also assumed to
be designed to handle a lower daily volume of waste that
reflects the waste diversion accomplished through recycling.
Costs for curbside collection of recyclables include
capital costs for collection vehicles and containers (for
commingled recyclables), payments to a reserve fund to replace
that equipment, labor, fuel, and vehicle maintenance costs,
and the costs of an ongoing public promotion program. The
number of dedicated recycling vehicles needed for the curbside
program is calculated using an iterative method described by
Garrison (1988).12 The tonnage of recyclables collected is a
function of the composition of the residential waste stream,
the recycling rate by residences within the service area, and
the density of individual materials.
The costs of yard waste collection were not calculated
separately since we assume that yard wastes are collected
using existing collection equipment and personnel under a
revised collection schedule. The net effect of a separate
yard waste collection program are reflected in a factor
described above under MSW collection costs: "collection cost
increase with separate yard waste collection."
The costs of processing recvclables or composting yard
waste include capital costs for land and construction of a MRF
or composting facility, initial equipment costs, equipment
replacement costs, and operating costs.
Revenue estimates from the sale of recovered newspaper,
color-sorted glass, and aluminum cans include ranges that
reflect markets for these commodities in Oklahoma during the
past three years. Prices are those paid by end-users, at the
MRF dock. Total revenues reflect the amount of recyclables
collected minus processing losses. Revenues from the sale of
composted yard waste range from zero to $8 per ton.
Commercial markets tend to be local because it is generally
not economical to transport compost long distances. In many
communities, composted yard waste is not sold commercially but
is used instead by the municipality as a substitute for soil
amendments that would otherwise be purchased by their parks or
highway departments. The revenue range includes the avoided
600
-------
cost of making such substitutions.
Analyses
For each of the four case study communities, three base
analyses were conducted: (1) no recycling, (2) curbside
recycling, and (3) curbside collection and composting of yard
waste. The no-recycling option reflects the current solid
waste management system. For variables in Table II with a
range of values, mid-points were used in the base analyses of
the recycling options; best and worst cases were defined to
reflect the highest possible range of variation. Sensitivity
analyses were conducted to test the impact of varying
individual variables.
For the two larger cities, Oklahoma City and Norman, the
curbside recycling collection vehicles were assumed to be 15-
cubic yard dedicated recycling trucks. Sensitivity analyses
were performed for each of these communities substituting a
14.25-cubic yard recycling trailer hauled by a pickup truck.
For the smaller communities of Fairview and Owasso, the base
analysis assumed use of a pickup truck-trailer collection
vehicle. In these two cases, only one collection vehicle is
needed to serve the community, and the decreased collection
efficiency of the truck-trailer system is offset by much lower
capital and maintenance costs. In the Fairview case, the
truck-trailer rig is assumed to be shared with other
municipalities in the regional solid waste management
authority. Fairview would only need to operate the vehicle
one day a week to collect recyclables from its 1,308
households.
The base analyses for Oklahoma City and Norman also
assumed that the municipality owns and operates the MRF for
processing recyclables. A minimum capacity of 5 tons per day
(tpd) was assumed based on interviews with MRF vendors. The
Fairview analysis assumes the MRF is regionally owned, with
Fairview responsible for 31 percent of the capital and
operating costs, which is equivalent to its proportion of the
wastes currently handled by the regional solid waste system.
A scenario was also analyzed where Fairview only used that
portion of a regional MRF that it actually would need for its
recyclables. Such an option would require extending the size
of the regional system to include other municipalities to
fully utilize the capacity of a 5-tpd MRF. A similar scenario
served as the base case- for Owasso, which operates its own
solid waste management system at present but would utilize
only about 18 percent of a 5-tpd MRF.
601
-------
Results
Diversion Rates
Waste diversion rates for the curbside recycling and yard
waste composting options depend on assumptions about waste
composition, recycling rates, and, in the case of curbs ide
recycling, processing losses at the MRF. The range in
potential diversion rates for the residential waste stream are
summarized in Table III. Total diversion rates for the
composite MSW stream will vary with the mix of residential and
commercial wastes managed by a municipal system. As shown in
Table I, the proportion of residential waste varies
substantially among the four communities studied, from 71
percent in Fairview to 24.1 percent in Owasso. As a result,
the total diversion rates for these four communities also vary
considerably as shown in Table IV.
Table III. Residential diversion rates.
Recycling
Option
curbs ide
composting
Best
Case
11.41%
44.07%
Base
Case
5.79%
30.96%
Worst
Case
1.85%
12.99%
combined
55.48%
36.75%
14.84%
Table IV. Composite diversion rate ranges.
Recycling
Option
curbs ide
composting
Best
Case
4.1 - 8.1%
10.6 - 31.2%
Base
Case
1.4 - 4.1%
7.5 - 22.0%
Worst
Case
0.5 -
3.1 -
1.
9.
3%
2%
combined
13.4 - 39.4% 8.9 - 26.1%
3.6 - 10.5%
602
-------
Cost Effectiveness
Comparison of the 20-year life cycle costs of the current
solid waste management systems and those for a curbside
recycling program suggests that curbside recycling would be
marginally cost-effective in the four communities under
conditions somewhat more favorable than the base cases.
Composting programs, however, represent a substantial increase
in costs except under the most optimistic assumptions.
Figure 1 portrays the life cycle cost differentials for
curbside recycling and yard waste collection and composting
for the four communities under the base-case assumptions. The
bars indicate the percent difference between no recycling and
the two recycling options. The curbside programs would entail
net increases of two to three percent in 20-year life cycle
costs for all but Fairview. If Fairview were able to
participate in a regional MRF system where it only paid for
the proportion of a 5-tpd MRF that it actually needed, it's
life cycle cost differential for curbside recycling would be
in the same range, 2.6 percent. The life cycle cost
differentials for yard waste collection and composting
programs are substantially higher, in the range of 11.5 to 13
percent.
Figures 2 and 3 show the range of possible life cycle
cost differentials for the best-case and worst-case scenarios
for a curbside collection program and a composting program in
the four communities. The best-case scenarios for both
recycling options yield lower life cycle costs than the
present solid waste management system for all four
communities, but the worst-case scenarios represent
substantial cost increases, especially for the composting
option. Tables V and VI list the assumptions used to define
the best and worst cases for the two recycling options.
In Table VII, a more conventional cost figure is used,
cost per household per month. These figures only show the
first-year net systems costs, so the effects of landfill
capacity savings and paying off initial bonds are not
reflected. Thus while the best-case scenarios for yard waste
composting all show a net reduction in life cycle costs,
first-year costs are only reduced for Norman and Owasso. For
the best-case curbside option, both the life cycle costs and
first-year net costs are lower for all four communities.
Under the best-case scenarios, all four communities would
save money from a combined curbside recycling and composting
program. The combined first-year net costs for the base-
caseanalyses of curbside recycling and yard waste composting
range from $1.50 to $2.00 per household. These costs are
within the range that municipalities in other parts of the
603
-------
14
of life cycle cost
12 -
10
8
6
4
2
Oklahoma City Norman Owasso Fairview
SB curbside recycling I I yard waste compost
Figure 1. Life cycle cost differentials compared to no recycling.
604
-------
20
15
10
5
0
-5
-10
-15
of life cycle cost
Oklahoma City Norman Owasso Fairview
!SiM worst case I I base case HH best case
Figure 2. LCC differentials - curbside compared to no recycling.
30
20
10
% of life cycle cost
-10
Oklahoma City Norman
worst case
Owasso
Fairview
base case
best case
Figure 3. LCC differentials - composting compared to no recycling.
605
-------
Table V. Best and worst case scenarios for curbside recycling.
Variable
Waste composition (propor-
tion of recyclables)
Recycling rates
Collection cost savings
Productivity of recycling
vehicle
Processing costs*
MRF design life
Materials sales prices
Best Case
high
high
high
high
low
long
high
Worst Case
low
low
low
low
high
short
low
Combined unit capital costs and operating costs.
Table VI. Best and worst case scenarios for composting.
Variable
Waste composition (propor-
tion of yard waste)
Recycling rates
Collection cost increase
Composting costs*
Debagging costs
Compost weight reduction
Compost sales prices
Best Case
high
high
low
low
low
low
high
Worst Case
low
low
high
high
high
high
low
Combined unit capital costs and operating costs.
6O6
-------
8
Table VII. First-year net costs In dollars per household per month compared to no recycling.
Oklahoma City
Program
Option
curb side
composting
Worst
Case
$0.83
1.84
Base
Case
$0.28
1.22
Best
Case
-$0.98
0.02
Worst
Case
$1.10
3.03
Norman
Base
Case
$0.25
1.69
Owasso
Best
Case
-$1.41
-0.29
Worst
Case
$0.89
3.27
Base
Case
$0.25
1.75
Best
Case
-$1.10
-0.43
Fairview
Worst
Case
$1.69
2.13
Base
Case
$0.55
1.44
Best
Case
-$1.00
0.38
combined
$2.67 $1.50 -$0.96 $4.13 $1.94 -$1.70 $4.16 $2.00 -$1.53 $3.82 $1.99 -$0.62
-------
country have been willing to pay for the noneconomic benefits
of recycling such as energy conservation, improved
environmental quality, and less waste of natural resources.
However, under the worst-case scenarios, combined costs would
range from $2.67 to $4.16 per household per month. It is
likely that cost increases of this magnitude would generate
political and public opposition in some communities.
Importance of Different Cost Components
Examination of the individual cost components for the
different systems shows that collection costs dominate the
outcomes for both the curbside and composting programs. Total
life cycle costs of curbside collection of recyclables account
for 45 to 68 percent of the total costs of a curbside
recycling program in the base cases. Costs of yard waste
collection are responsible for 60 to 80 percent of the costs
of a composting program under base-case assumptions.
Under best-case assumptions, the reduced costs of
collecting regular household waste compensate for the
increased costs of a separate curbside collection system for
recyclables in all of the communities except Fairview. In the
worst-case scenario, we assumed no savings in collecting MSW
which is more likely in the two smaller communities, and
possibly in Norman as well, since significant savings will
only occur where at least one truck and crew and can be
eliminated.
The best-case assumption for the composting option was
that the increased costs of a separate yard waste collection
are completely offset by the reduced costs of collecting the
remaining MSW from residences. In the worst-case scenario
there is a 25 percent increase in net collection costs.
Processing costs account for 23 to 29 percent of the
costs of a curbside recycling program in all of the
communities except Fairview. In Fairview, processing accounts
for 47 percent because of under-utilization of the city's
share of a 5-tpd MRF. If Fairview were able to participate in
a regional system where it only paid for the proportion of a
MRF that it actually required, processing costs would
represent a proportion of total costs comparable to that for
the other cities. In the base-case composting scenarios,
composting costs account for 19 to 36 percent of total program
costs.
Program promotion and public education costs are
relatively insignificant for both the curbside and composting
programs. They range from 8 to 10 percent for curbside
recycling and from 2 to 5 percent for composting programs.
6O8
-------
Revenues cover 31 to 40 percent of program life cycle
costs under the base-case scenarios for curbside recycling.
Under best-case assumptions, revenues equal or exceed costs
for curbside recycling in all of the communities except Owasso
where they cover about 84 percent of program costs. Revenues
are much lower for yard waste compost, covering only 2 to 13
percent of program costs under base-case assumptions ($4/ton).
Under best-case assumptions, the range increases to 6 to 12
percent, but under the worst-case scenarios we assume no
revenues are generated through compost sales or substitution
for soil amendments used by municipal agencies.
Sensitivity Analyses
In addition to assessing the effects of best-case and
worst-case assumptions, analyses were run to assess the impact
on life cycle costs of varying individual variables. The
range of variation in life cycle cost differentials associated
with the value ranges for the individual variables tested are
summarized in Table VIII for the two recycling options.
In the curbside recycling scenarios, results were most
sensitive to variation in recycling rates, collection cost
savings, set-out rate, waste composition, sales prices, and
processing costs. The relative sensitivity of the program
life cycle costs to individual factors varied among the
communities, primarily because of differences in the unit
costs of collecting MSW. Variations in processing costs had a
greater impact in Fairview because of its under-utilization of
a regional 5-tpd MRF.
In the yard waste composting scenarios, variations in
assumed collection cost increases and processing costs have
the greatest impacts on life cycle costs. This is due to
thegreater extent to which these costs overshadow the
potential revenues from compost sales or avoided costs from
compost use by the municipality or waste diversion.
Conclusions
Analysis of these four communities in Oklahoma
demonstrates that in many municipalities recycling programs
must be extended to commercial wastes as well as residential
wastes to achieve a 25 percent reduction in MSW through
recycling. This study also indicates that curbside recycling
programs will probably require some increase in total solid
waste management service fees, although these increases are
within a range that has been politically acceptable in many
communities throughout the nation. The additional costs of
609
-------
Table VIII. Range of variation in life cycle cost differentials
for individual variables.
Variable
Waste composition
Recycling rates
Materials sales prices
Collection cost savings
Collection cost increase
Processing costs
Debagging costs
Compost weight reduction
MRF lifetime
Set-out rate
Truck productivity
Collection vehicle type
Landfill lifetime
Landfill ownership
Discount/interest rate
Inflation rates
Recycling
Curbs ide
3-5%
6-7%
2-5%
3-4%
n/a
1-6%
n/a
n/a
0-2%
3-6%
2-3%
1-2%
0-1%
0-1%
<1%
<1%
Option
Composting
0-1%
<1%
1-2%
n/a
15-21%
7-12%
<1%
<1%
n/a
n/a
n/a
n/a
<1%
2-3%
<1%
<1%
610
-------
yard waste collection and composting may entail a substantial
increase in waste management costs, especially if combined
with the costs of a curbside recycling program in an effort to
achieve a 25 percent recycling goal.
Because solid waste disposal costs are considerably lower
in this region of the country, the life cycle costs of
recycling or composting are primarily determined by collection
and processing costs. The reduced savings that can be
realized from the avoided costs of waste diversion and
extended landfill capacity also make net costs for recycling
options more vulnerable to shifts in markets for recovered
materials. Net costs are also more sensitive to such factors
as waste composition and variables that affect net recycling
rates including participation rates, recovery rates, and set-
out rates.
Assessing the cost-effectiveness of recycling in
communities such as those analyzed here will, therefore,
require very careful examination of opportunities to minimize
collection costs and maximize savings from diverting wastes
from the regular MSW collection and disposal systems.
Particular care must be given to assessing potential markets,
and continued effort will be required to maintain high
participation and recovery rates through ongoing public
education programs. In smaller communities, such as Owasso
and Fairview, regional processing facilities, and in some
cases, shared collection equipment, may be essential to making
curbside recycling and composting programs as nearly cost-
effective as possible. Communities of this size, i.e. less
than 15,000, account for 25 percent of the total population in
Oklahoma and 33 percent of the population living in
incorporated municipalities. Another 23 percent of the total
population of the state lives in unincorporated areas where
curbside collection is not currently provided and where
recycling would most likely require use of drop-off centers.
The marginal cost-effectiveness of these recycling
options suggests that financial subsidies from states or the
federal government may be required to overcome political
opposition to the increased costs of municipal recycling
programs. Some measure of willingness to pay is needed to
assess the cost thresholds beyond which communities are not
willing to go for the less tangible benefits of recycling.
The computer program designed for this project has the
capability to assess the impacts of public grants on first-
year net costs and life cycle costs. We expect to conduct
such an analysis in the near future.
611
-------
Acknowledgements
Support for this work was provided from the federal Exxon
Oil Overcharge Settlement Fund through a contract administered
by the Oklahoma State Department of Commerce.
References
1. The Solid Waste Dilemma; An Agenda for Action. United
States Environmental Protection Agency, Washington, DC,
1989.
2. K. Meade, "Recycling bill aims for 25%-50%, calls for
•hard look1 at waste," Recycling Times 1(8): 1; K. Meade,
"RCRA draft highlights recycling," Recycling Times 1(14):
3 (1989).
3. C.L. Petit, "Tip fees up more than 30% in annual NSWMA
survey," Waste Age 20: 101 (1989).
4. R.E. Deyle and B.F. Schade, Municipal buy-back recycling:
economic feasibility in Oklahoma, Proceedings ASTSWMO
1990 National Solid Waste Forum on Integrated Municipal
Waste Management. Association of State and Territorial
Solid Waste Management Officials, Washington, DC,
forthcoming.
5. S.H. Russell, Resource Recovery Economics. Marcel Dekker,
New York, 1982.
6. B.F. Schade and R.E. Deyle, "Recycling in the land of
plenty: the cost effectiveness of curbside programs in
Oklahoma," in preparation.
7. See for example The BioCycle Guide to Collecting.
Processing, and Marketing Recyclables. BioCycle Journal
of Waste Recycling, JG Press, Emmaus, PA, 1990; 1990-91
Materials Recovery and Recycling Yearbook. Governmental
Advisory Associates, New York, NY, 1990; A.C. Taylor and
R.M. Kashmanian, Yard Waste Composting A Study of Eight
Programs. U.S. Environmental Protection Agency,
Washington, DC, 1988; Management Strategies for Landscape
Waste. Illinois Department of Energy and Natural
Resources, Springfield, ILL, 1989.
8. B.F. Schade, Solid Waste Management and Recycling in
Oklahoma: An Economic Analysis, master's thesis,
University of Oklahoma, 1989, p.106-130.
612
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9. R.E. Deyle, T.E. James, T.M. Coffman, N.N. Hanks, G.
Lawn-Day, D. Penn, B.F. Schade. Solid Waste Management
and Recycling in Oklahoma. Univ. of Oklahoma, Norman, OK,
in preparation.
10. Collection Cost Savings Study. Resource Integration
Systems, Inc., Toronto, Ont., 1988.
11. Camp Dresser and McKee, Inc., Economic Impact Study of
Landfill Regulations (R88-7). Illinois Dept. of Energy
and Natural Resources, Office of Research and Planning,
Springfield, IL, 1990; E. Cowhey Sheliga, Browning
Ferris Industries, Inc., personal communication, November
20, 1989; R.T. Glebs, "Subtitle D: How Will it Affect
Landfills?" Waste Alternatives 1: 56-64 (1988); E. Knox,
Laidlaw Waste Systems, Inc., personal communication,
November 13, 1988; G. McDonald, USA Waste Services,
Inc., personal communication, November 13, 1988;
National Solid Waste Management Association, How Much
Will a State-of-the-Art Landfill Cost?. NSWMA,
Washington, DC, 1988.
12. R. Garrison, "Curbside Collection Service: Estimating
Equipment Needs," Resource Recycling 7: 30-32 (1988).
613
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I 0 1990
FEDERAL FACILITIES RECYCLING
Gail Miller Wray, Moderator
EPA Recycling Coordinator
Jim Nelson
Assistant General Council, Toxic Substances Branch
Elaine Suraino
Coordinator, Toxic Chemical Assesment Desk
Ruth Yender
Environmental Protection Specialist
I. EPA's Success
A. Sierra Club's Acceptable Six—EPA singled out for
praise (Washington Post, New York Times).
B. Federal Executive January issue.
C. Federal Times issue.
II. EPA Recycling staff
A. Office of Solid Waste—Muncipal Solid Waste Office
1. Policy
2. Public/Community Outreach
B. Office of Administration and Resources Management -
Facilities Management and Services Division.
1. Administration of Internal Recycling program.
2. Assistance to Federal Agencies.
C. Recycling Workgroup
1. Advisory
2. Actual working arm of program
D. AA Coordinators
1. Monitoring
>
III. EPA logistics (detailed on blue handout)
A. 8000 employees
B. Three buildings
C. 1.2 million square feet
615
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IV. EPA program history
A. "Use it Again Sam!"—1977 campaign.
1. Failure of 1970's movement
a. Markets
b. Slow technological movement and procurement
problems
2. Sluggish continuation of program throughout
1980s.
a. GAO Report (GAO/GGD-90-3)
1. Source preparation
2. Procurement Guidelines
B. Resurgence of concern—1988
1. Recycling Workgroup
2. Agency Coordinator
3. August Kick-off
V. EPA Waste Stream Analysis
A. Conducted to survey contents of recyclables in waste
stream. Concrete figures are needed to entice vendor
interest. (Overhead 1)
1. Composite of EPA's three HQ building sites
a. Paper by far the largest is 73 % (weight).
b. Glass comes in 2nd at 11% (weight).
[Overhead 2 is a more visual representation of these
numbers]
2. [Overhead 3] details EPA's 1988 disposal and
recycling figures.
3. [Overhead 4] details FY 1989's—you can see the
tremendous growth in our paper collection program.
4. [Overhead 5] gives current FY 1990 statistics, we
are currently 77% of last years collection figures
(this does include the lower grades of paper).
VI. EPA's Program
A. Methods of Collection
1. EPA Region 5 has a box latched onto the side of
their waste bins.
2. EPA Region 7 developed the two-sort grey boxes.
3. EPA-HQ continued with the cardboard box.
B. Expansion of HQ Paper program
l. Three sorts
a. High grade
b. Low grade
c. Newspaper
816
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2. HQ adopted the Region 7 grey box—rationale.
a. small
b. asthetically pleasing
c. large enough for clear labeling
d. desire to remove "recycle" image away from
"garbage" image
3. HQ organized "central collections bins"
a. Rational for choosing plastic bins.
1. durability
2. strength
3. Health and safety of Labor/Services
personnel.
4. Location of storage
a. Gaylords
1. Size
b. Building and Fire codes
5. Marketing of recyclables
a. Paper—General Services Administration
b. Glass—
c. Aluminum—
C. Methods of Procurement
1. In-House Printing
2. Agency policy
a. Transmittal on Submission all contractor reports
on recycled paper (1/24/90).
3. Working with the Joint Committee on Printing (JCP),
the General Services Administration (GSA), and the
Government Printing Office (GPO).
VII. Expansion to include Glass and metals (D. C. Solid Waste
Management and Multi-Material Recycling Act of 1988).
A. Igloos (provided by Glass Packaging Institute and
D. C. Council of Churches).
B. Aluminum In-house program.
VIII. Recycle—
A. Education
B. Collection
C. Marketing
D. Procurement
E. Monitoring and Evaluation
Visual Aids: Overhead graphs
3-part grey boxes
1 red bin
Handouts: EPA In-House Handout (Blue)
OARM Recycling Update (White w/blue ink)
617
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FINANCING A RECYCLING PROGRAM:
LANDFILL DIVERSION CREDITS
by Miriam Foshay
Recycling Management, Inc.
Presented at the
s
First U.S. Conference on Municipal Solid Waste Management
June 13-16,1990
619
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FINANCING A RECYCLING PROGRAM:
LANDFILL DIVERSION CREDITS
Miriam Foshay
Whenever a municipality is analyzing the cost of a recycling or composting
program, one of the factors it must consider is the amount of money saved by diverting
waste from the landfill. This saving is called a "diversion credit," and it can often be a
significant amount of money. If the municipality is providing both refuse and recycling
services with its own staff, then the city recovers this money directly. But very few cities
work this way. Most either contract with a private hauler (who may or may not also
handle the recycling or yard waste collection) or the citizens themselves contract with
several different haulers. How, then, can a municipality recover the savings that comes
from diverting waste from the landfill?
The City of Naperville solved this problem in a unique way. Refuse collection is
handled by a single hauler in an exclusive contract with the city. When Naperville signed
its last five-year contract with its hauler, the local recycling center was beginning a pilot
curbside collection of recyclable materials. Written into the contract was a clause
requiring that after a period of one year, the hauler, the recycling center, and the city
would negotiate a rebate from the hauler based upon the volume of material diverted
from the landfill by the recycling center.1
In this case, the refuse hauler acquires savings in many areas when waste is
diverted from his program. Every ton of material not collected by his trucks saves him
tipping fees at the landfill, but there are other savings as well: he makes fewer trips to
11 The text of the contract reads:
39. PILOT CURBSIDE COLLECTION PROGRAM
It is understood between the City and Contractor that the City has entered into an agreement
with the Naperville Area Recycling Center (NARC) in which NARC will conduct a Pilot
Curbside Collection Program for collection of recyclable solid waste materials from certain areas
of Naperville. Contractor agrees to cooperate and assist the City and NARC to evaluate the Pilot
Program, and, if renewed or extended, the Contractor agrees to negotiate in good faith with the
City to determine a reasonable reduction in the cost per stop per month charge in Section 14
hereof.
620
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the landfill, saving labor and vehicle costs; and he spends less time collecting trash,
saving labor costs. The negotiation between the City of Naperville, its refuse hauler, and
Naperville Area Recycling Center (NARC) yielded a three-part formula to calculate
each of these cost savings.
Before we could develop a formula for a credit, we had to establish equivalent
values. For instance, refuse is measured in compacted cubic yards, but recyclable
materials are measured in tons. How many tons of recyclables equals one compacted
cubic yard of trash? For lack of a better measure, we agreed upon the value of three
compacted cubic yards to one ton which is used by the local landfill. In fact, this value
would depend upon what materials are collected: newspaper, one of the densest items,
might have a density of 3-4.5 cu yd/T, but plastic and corrugated have a much lower
density.^ This and other equivalency assumptions we made are listed in Table 1.
Table 1
ASSUMPTIONS
1 ton = 3 compacted cubic yards = 12 loose cubic yards
one garbage truck = 25 compacted cubic yards
time to load one loose cu yd = 135 seconds
Tipping fees saved. Having established that one ton of recyclables equals three
cubic yards of refuse, we can easily calculate tipping fees saved:
Sj = 3 x (tipping fee/cu yd)
where Sj is savings per ton of recyclables collected. As the tipping fee changes, the
value of Si also adjusts.
2Franklin Associates has just completed a study comparing density of materials in the landfill which
should be available soon from The Council for Solid Waste Solutions.
621
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Trips to landfill saved. In order to calculate trips to the landfill saved, one must
know the volume of a garbage truck. The hauler's trucks all have a rated capacity of 25
cubic yards. Therefore, using the 3 cu yd = 1T formula, every 8.33 T of recyclables
collected would save one trip to the landfill.
But what is a trip to the landfill worth? There are two factors to be considered:
labor saved
truck expenses saved
Labor saved depends upon the average round trip time to drive to the landfill plus the
average time to unload times the driver's wage plus payroll taxes. In this calculation,
benefits were excluded because the refuse company maintained that the benefits paid
did not depend upon the number of hours worked, so shaving a few hours of driving time
would save hourly wages but not benefit costs. In fact, the recycling program has grown
so much that the refuse company's labor requirements have been reduced by nearly two
full-time employees, which certainly produces a savings in benefits paid.
Truck expenses saved relate directly to how far the truck must drive in one round
trip to the landfill. Truck costs include fuel, oil and maintenance only. Depreciation and
insurance costs were not included, because the truck accrues depreciation and requires
insurance whether it is driven full-time or not. In fact, the recycling program currently
replaces the need for two garbage trucks, reducing the capital outlay required of the
refuse hauler.
The savings for each truckload which does not go to the landfill (S2a) can be
calculated as follows:
$2a - [(driving time saved)x(hourly wage + taxes + benefits)]
+ [(RT distance)x(truck cost/mi)]
In order to get savings per ton (instead of per truckload), this number must be divided by
8.33 T/truckload:
622
-------
S2 = S2a/8.33 T/truckload
Trips to landfill saved (82) adjusts as labor and fuel costs change.
Collection time saved was the most difficult figure to calculate. The hauler must
drive by every house whether the homeowner puts out trash or not; therefore, there is no
savings in vehicle costs. Is there a savings if the homeowner only puts out one bag
instead of two? Will the homeowner put out trash less often if he recycles? We finally
agreed to calculate how much time it took to load each bag of trash.
First of all, the hauler collects loose material, not compacted. How many loose
cubic yards equal one ton? We established that a garbage truck compacts its load to
one-fourth of the original volume. Therefore:
1 ton = 3 compacted cubic yards = 12 loose cubic yards
If we assume that the typical set-out consists of full 30-gallon plastic bags, then every 6.5
bags equals one loose cubic yard. It takes about 20 seconds to load each 30-gallon bag,
or 135 seconds per loose cubic yard. This amounts to about one-half hour per ton or
four hours to load one 25-yd packer truck.
As above, marginal labor costs including benefits were not included in the
calculation; but since the labor savings amounts to two full-time employees, these costs
should have been included. Collection time saved (83) can be written as follows:
83 = (12 loose cu yd/T) x 135 sec x (labor cost/hrl
3600 sec/hr
As for trips to landfill saved (82), collection time saved varies with labor costs.
Items not covered. NARC collects certain items that the refuse hauler did not
include in his contract: used motor oil and white goods. Analysis of NARC's loads
revealed that these two classes comprised 1.6% of the total collection by weight.
.Therefore, the total tonnage collected by NARC had to be reduced by 1.6%.
623
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The total savings accrued by the waste hauler (and payable to the City) can be
calculated by summing the above savings per ton and multiplying by the tonnage of
recyclables collected, adjusted for oil and white goods not included in the contract:
Total savings = (tons of recyclables collected) x Fa x (Sj + 82 + 83)
where Fa is the adjustment factor for items not covered.
Currently, tipping fees are $6.55/cu yd and the City receives about S35/T from its
waste hauler in landfill diversion credits. If this figure were adjusted for density of
materials, vehicle depreciation and benefits, it could be much higher.
In Illinois and elsewhere, cities are negotiating with haulers not for a single trash
collection but often for three separate collections: yard waste, recyclable materials, and
refuse. Whether they choose to contract with a single hauler to handle all three services
or with separate haulers, city officials should bear in mind the savings that a refuse firm
realizes when some of the material it formerly collected is diverted from the landfill.
This landmark contract negotiated by the City of Naperville establishes a precedent
which should help other cities to establish a similar credit from their waste hauler.
624
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INNOVATIVE COMMERCIAL & APARTMENT
RECYCLING PROGRAMS
Craig H. Benton
Planning Director
Sound Resource Management Group, Inc.
7220 Ledroit Court SW, Seattle, Washington 98136 • 206/281-5952
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13 -16,1990
625
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City of Tukwila Recycling Pilot Project Summary
INTRODUCTION
This report summarizes activities undertaken by Sound Resource Management Group. Inc. (SRMG) in
planning, developing, implementing and evaluating a Recycling Pilot Project for the City of Tukwila,
Washington. The pilot project, conducted from June to August, 1989, was intended mainly to gather data
on commercial and apartment recycling within Tukwila, and to test the ability of Tukwila's primary solid
waste hauling firm to provide recycling services. A secondary purpose was to assess the feasibility of
operating a commingled system in which all recyclables are placed into one container for collection.
This document presents results of the quantities of materials recycled during the project, assesses participa-
tion levels, and analyzes costs and savings. It concludes with a discussion of some of the challenges the
City of Tukwila will likely face in implementing a full-scale recycling program.
ACTIVITIES
Summarized below are the activities SRMG completed to implement Tukwila's pilot recycling project
Planning
• Developed project plan.
• Selected the following two multi-family complexes and four commercial areas as pilot participants:
1. San Juan Apartments, 6250 S. 153rd Street
2. Canyon Estates Condominiums, 15138 65th Ave. S.
3. Small Retail Mall, 16828 South Center Parkway
4. Office Building, Southcenter Plaza, 14900 Interurban Ave S.
5. Gateway Corporate Center, 12886 Interurban Ave. S.
6. Small Manufacturer, Racon, Inc., 12128 Interurban Ave. S.
Development
• Obtained cooperation of property managers and owners.
• Negotiated pilot program terms with Sea-Tac Disposal Company, Inc. (Sea-Tac).
• Designed collection system (type of equipment, and size and location of containers).
• Developed instructional brochures and container labels.
Implementing
• Coordinated timing and placement of collection containers.
« Distributed instructional brochures to participants twice in the first month of the 3-month project.
Tukwia RecyeSng Pilot Project Summary
626
-------
• Distributed deskside boxes to commercial participants.
• Coordinated activities with janitors when necessary.
• Modified a hand can for hauling cardboard for an office building tenant
• Wrote and distributed a news release to local and regional newspapers.
Monitoring & Evaluation
• Monitored garbage and recycling bins on a weekly basis. If excessive amounts of recyclables were
found in the garbage bin, or if the recycling bin was contaminated with trash, then the appropriate
business tenants or employees were revisited, talked to, and issued another instruction flyer.
• Photographed project and used pictures in a presentation to the Tukwila City Council.
• Developed and distributed a flyer, thank-you note and feedback form to participants.
• Produced a display map showing pilot project locations.
• Summarized data and findings (in this report).
WEIGHT, VOLUME & COMPOSITION OF COLLECTED MATERIALS
The table below (Fig. 1) summarizes the volume reduction achieved by each pilot project participant and
for the project as a whole. The first column lists the pilot participants. The second column totals the weekly
garbage capacity of each participant by volume. The third and fourth columns list the size and hence the
designed weekly capacity for collecting recyclables. The fifth column estimates an average fullness factor
for each participant's recycling containers, based on Sea-Tac's collection route summary forms. The sixth
column lists the actual volume reduction each participant achieved, which was derived by multiplying the
design capacity by the fullness factor. The last column translates the actual volume of recovered waste (in
cubic yards) into a percentage figure that represents a volume reduction value.
Volume Reduction Summary for Pilot Recycling Project
Fig. 1
Project
Participant
San Juan Apts.
Canyon Estates Condos
Retail Mall
Southcenter Office Plaza
Racon Manufacturing
Gateway Corporate Ctr.
Total
Average
Garbage
Capacity/Week
CUBIC YDS.
12
60
21
24
16
28
161
—
Recyclables
Capacity/Week
CU.YDS.
4
10
6
8
2
8
38
—
%
33
16
28
33
12.5
28.6
100
24
Fullness
Factor*
%
50
50
75
100.
75
75
—
—
Actual Volume
Reduction
CU.YDS.
2
5
4
8
1.5
6
26.5
—
%
16.6
8.3
19.0
33.3
9.3
21.5
100
16.5
; Based on Sea-Tac Disposal collection route summary forms.
627
Sound Resource Management Group. Inc.
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Recyclables Collected by Tukwila's Pilot Recycling Project
Fig. 2
Collection
Date
6/20
6/27
7/4
7/11
7/18
7/25
8/1
8/8
8/15
8/22
• 8/29
Total
Average
Pounds
Collected
1,310
1.600
1,640
1.750
1,240
2,230
2,020
2.150
2,490
2,880
4,950
24,260
2,205
Lbs/CuYd
34.5
42.1
43.2
46.0
32.6
58.7
53.2
56.6
65.5
75.8
130.2
—
58.0
% Reduction
in Weight
6.76
8.26
8.46
9.03
6.40
11.51
10.42
11.01
12.85
14.86
25.55
—
11.4
Note: Percent Reduction in Weight is based on
19.375 Ibs/week of solid waste generated by the
six pilot participants. This figure was arrived at by
multiplying 155 cubic yards of solid waste collec-
tion capacity by 125 Ibs/cubic yard (supplied by
Sea-Tac as an average industry figure for volume-
to-weight conversion).
The table and
chart above (Fig. 2)
shows the amounts of recy-
clables collected each week from
the six project participants. The data was
taken from the forms Sea-Tac Disposal devel-
oped and used to record the amounts of recyclables
collected from each participant as well as by the project as a
whole. In summary, a total of 12 tons of recyclables was collected
during the entire project, amounting to an average of just over one ton
per week, and representing an average solid waste stream weight reduction of
11 percent. Weekly tonnage increased from week to week but varied slightly due to a
mix-up in collection on July 18. The unusually large amount collected in the final week
was due to the fact that all deskside boxes from offices were collected and emptied.
Tukwila Recycling Pilot Project Summary
628
-------
The pilot project was designed to reduce solid waste volumes by 24 percent. In fact, because not all
recycling containers were full when they were collected, the pilot project actually reduced solid waste
volumes by approximately 16.5 percent
In summary, paper of some sort constituted about three-quarters of all material collected during the pilot
project This was especially true for the commercial participants, whose recovered materials included a
significant fraction of cardboard and mixed paper. The multi-family project recovered a mix of materials,
including cardboard, newspaper, glass containers, cans and plastic bottles.
COST/SAVINGS ANALYSIS
Sea-Tac Disposal completed a cost/savings analysis for each of the six pilot participants. (Attached to the
original report were copies of Sea-Toe's work sheets.) Their analysis indicated:
1. The cost of garbage service for each participant prior to the recycling pilot project.
2. The cost of the level of service offered during the pilot project
3. The cost of service that accounted for the reduction in garbage service as a result of the amount of
materials recycled during the pilot
Generally, solid waste collection costs increase when recycling services are added because additional con-
tainers and pick-ups are needed to collect the recyclables. But recycling can decrease disposal costs. A
break-even point occurs when savings from not having to pay for disposal equals the extra cost of provid-
ing recycling services. From Sea-Tac's data it can be estimated that the break-even point for recycling
services occurs when about 30 percent of the waste collected is recycled by volume. In other words, if an
apartment or business recycles less than 30 percent of its waste, the added recycling service will cost more
than the savings in dump fees, resulting in added costs. If a business or apartment complex recycles more
than 30 percent then the recycling program will cost less than the savings in dump fees, resulting in a net
savings. This break-even point can decrease if recycling containers are substituted for garbage containers.
PARTICIPATION RATES
Exact numerical participation rates are difficult to estimate for this project because apartment and business
tenants shared a common recycling collection container, rather than each business or residential unit having
its own container (as is basically the case with, for instance, single-family residential curbside collection
programs). Participation rates in this project are therefore categorized as "low," "medium" and "high."
Participation rates were evaluated using the following criteria:
• How full the recycling containers and garbage dumpsters were over the pilot project period.
• What materials were in the recycling container and garbage dumpsters. If large amounts of
recyclables were found in garbage dumpsters, then participation in the recycling program was low.
Conversely, if very few recyclables were found in the garbage, participation was high.
Sound Resource Management Group, Inc.
629
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• Regular visits to business and multi-family complexes. By visiting participants, SRMG personnel
could determine if businesses were using their deskside boxes and whether apartment managers
were working with their tenants. Personnel inquired about "how the participants felt the program
was going." then used the feedback to make changes to encourage and sustain participation.
The following chart (Fig. 3) indicates the participation rate associated with each project participant:
Recycling Participation Rates Fig. 3
Location
1. Office Building
2. Racon, Inc.
3. San Juan Apartments
4. Small Retail Mall
5. Gateway Corporate Center
6. Canyon Estates Condominiums
Participation
high
high
medium
medium
medium
low
1
'///////////////////M^^^
In general, participation by multi-family residents was lower than participation by commercial employees.
The overall low participation rates for multi-family dwellers may be explained by the following factors:
• They did not receive as much personalized one-on-one attention by SRMG personnel as did the
commercial participants.
• They did not receive a collection container for use inside their apartment units (the commercial
participants received deskside boxes to collect office paper).
• Apartment dwellers have little financial incentive to reduce waste because their garbage fees are
typically included in their rent.
The point about apartment dwellers and financial incentives deserves further discussion. The pilot project
tested recycling in both an apartment and a condominium. In apartments, utilities are usually included in
the rent. In condominiums, most people own their units, and utilities (i.e., solid waste, water and sewer) are
included in an additional maintenance fee. It would seem logical that condominium dwellers or owners
would have a greater financial incentive to reduce and recycle than apartment dwellers. However, the pilot
project results indicate that there was less participation from the condominium dwellers than the apartment
participants. Thus, financial incentives alone are apparently not enough to get people to participate.
Manager involvement is an essential element to obtaining high participation rates.
Participation in the commercial projects was generally high because:
• Convenient deskside boxes for collecting office paper were provided to commercial participants.
• Janitors were often used to empty the deskside boxes and place the materials into the recycling bin.
This made the recycling program even more convenient for some commercial participants.
• The materials, mostly office paper and cardboard, were easy to separate at the source.
• In some cases, the commercial participants had a financial incentive to reduce. This was the case
with Racon, which paid its own solid waste collection bills.
Tukwila Recycling Piiot Protect Summary
630
-------
Participation in the commercial projects was good overall, but there were also some low spots. Some man-
agers did not want to bother their employees with separating materials, since it was not part of their "jobs."
Others did not like the "big, unsightly" deskside boxes. Some participants ignored instructions for collec-
tion. For example, many businesses would not break down their cardboard because "it took too much
time." Unfortunately, the unflattened cardboard also filled the collection containers rapidly, at times
discouraging others from participating. Once this problem was identified and SRMG staff revisited partici-
pants, most cardboard was broken down by participants so that more materials could be collected.
SUMMARY: FUTURE CHALLENGES
Listed below are some of the challenges the City of Tukwila will face as it develops and implements a
citywide recycling program for apartment dwellers and businesses:
• Overcoming current throw-away attitudes and habits.
• Motivating renters and business tenants to participate even in the absence of a direct financial
incentive. Or, developing a mechanism that provides a financial incentive for renters to recycle.
• Making people aware of the solid waste disposal problem and about how to contribute to less cosdy
and more environmentally sound ways of managing waste instead of burying it in landfills.
• Working with the large number of actors or decisionmakers in apartment and commercial projects.
For the commercial locations, cooperation from the property owners, building managers, janitors
and business tenants is necessary for the project to be successful. This is opposed to working with
just renters or owners of single-family homes who might participate in a curbside recycling
collection program. For apartments, cooperation from the owner, manager and tenants is vital for
the project to have any significant impact
• Integrating legislative, educational and technical assistance activities with a citywide collection
program to maximize participation and waste reduction.
PROMOTIONAL MATERIALS
The following pages contain reduced images of promotional materials developed for this project, including:
• The pilot project collection container label and instruction sticker.
• Instructional flyer that was handed out to all project participants. (Not shown are all variations
which had different site maps and slightly different text)
• Participant thank-you note and response card.
Sound Resource Management Group. Inc.
-------
RECYCLING
ONLY
Fig. 4: Collection container identification label. Red on white vinyl. (36' x 18")
Commercial
Recycling
Service
Recycling Bin Instructions
PteOM put only tto Mowing W*d md*riol* into th« recycling collection container.
tyou ho»» CTiy <3J9*torv about r«cycQ off^r riaj«««ji not fat«d >*•*•.
o> carryng ytxr wcyctaD*!. cai you Cx*dng mcrv^M or S*o-Toc Otootd.
ALL PAPER CARDBOARD CLASS METALS PLASTICS
torwnow* al
toad
toMHtmon
» Slyn^ovn cux md
DQ NOT put the following materials Into the recycling collection bin:
Liquids • Food Waste • Waxed Paper Products • Fabrics • Wood • Styrafoam
Fig. 5: Collection container instruction label. Red on white vinyl. (15* x 10")
Tukwila Recycling Pilot Project Summary
632
-------
W bated. •» vdl •• •
(Xl*« map
Oudc (mud
SISOTiSt
I
I
• PIT
hoU hu»nh>u» >ue. csD the Sade-Kxc County
Dcpvtnmt c< Public Hutth Hm4» Uae •> ICT-sa
CITY" OF TLTKW7LA
PHOT RECYCLING PROGRAM
Owner1! Guide
Apartment &
Commercial
Pilot Recycling
Project
T
fir rmj *JTHnata > jilmitrt m
0«K uffl »ffer raey
•ucrf ronmngtedl racydofeit mottrtolj
uMOi iteyvt nOMcd to bun «r bojx Mo a
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x • F«Ww • Wood • Stra
Fig. 6: Instruction flyer delivered to all pilot program participants: outside (top); inside (bottom). Six
versions printed. Black on blue paper. (11" x 8-1/2*)
633
Sound Resource Management Group. Inc.
-------
•out) aVaaiaMrad, or MM my comma/is you on.
(WJon*j-
c/rr OF TC/KWILA
HLOT RECYCLING PROGRAM
D**i Pi« PTOIKI Partcpam.
The City of Tukwb would »• to
thank you lor pancpimg n our
3-montn p*x racyctng protect w«
v»ra aw* to iMm • futeantial
amount atmut racydng in our dry.
and am gong to be uuig ths ntor-
mxnon to maw o*oa«xts nan yaar
about now to ntaoran racyding nio
our tutura iokd wasia mmagatnam
Tna racyang cantamrfs) that ow*
instakM at your location wil t»
ramovK]«tn» and of August, and
your gart>ag« vanno* «n8 ratum to
•hat t wa» bBlora Bin preset
began Houwvvr. ( you oouU *« to
contnua racychnrj. you may can
1 -80O-R£CYd£ to Und out wtwra
Bwn ar» ncyotng opporlundM in
yourama-
Snowaty.
Th« City of Tukw«a
THAWS POR PMTKtPXnNG!
Fig. 7: Thank-you note and response card: front (right); back (left). Black on yellow paper.
(5-1 /2'x 8-1/2")
Tukwila Recycling Pilot Project Summary
634-
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INTEGRATING CURBSIDE COLLECTION COST-EFFECTIVELY
Ronald A. Perkins
Waste Control Systems, Inc.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
635
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INTEGRATING CURBSIDE COLLECTION COST-EFFECTIVELY
Ronald A. Perkins
Waste Control Systems, Inc.
INTRODUCTION
Municipal officials nationwide are confronted with increasing competition for limited tax
dollars. Recycling advocates should not take for granted that taxpayers will always look upon
curbside collection programs as sacred and untouchable. (Although environmentally uncon-
scionable, solid waste management programs can exist without recycling.) Thus, those of us who
are responsible for the design and operation of curbside collection systems must continuously
search for more cost-effective ways to do our jobs. This presentation purports to provide the
audience with some proven techniques to achieve the objective of integrating collection of
recyclables cost-effectively into existing refuse collection systems.
The ideas promulgated here are based upon the presenter's successful operation of curbside
programs over the past five years. "Success" here is measured by waste reduction achieved and
program cost; in this case 23-31 percent reduction and a positive economic impact on the total
solid waste management program. The particulars associated with these programs are set forth
in Table 1.
636
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PURPOSE OF PRESENTATION
1. Identify aspects of system design critical for cost-effectiveness.
• Political and municipal administrative support.
• Maximum convenience for residents within limits established by market con-
straints.
• Integrate operational plan to maximize positive economic impact on total solid
waste system.
• Identify optimal equipment/crew size, policies and collection frequency using
simulation models.
• Adjust refuse collection system resource requirements (equipment/labor) to reap
rewards of refuse volume reduction.
• Monitor refuse/recyclables ratio and adjust resources accordingly.
• Provide feedback to public for positive reinforcement.
2. Provide useful tips/based upon "real world" operational experience.
• Give strong consideration to collecting corrugated; high volume/weight ratio
positively impacts refuse density and landfill space usage. (There's more than you
think!)
• Whenever practically possible consider collecting one material (either source
separated or commingled) at a time to allow utilization of conventional refuse
collection equipment. This increases collection rate and ability to swap trucks from
recycling to refuse routes.
637
-------
• Collection of a single material at a time also totally eliminates problem of under
utilizing full capacity of truck which occurs in multi-material collection when one
bin typically fills before other.
• Simulation models can be used to accurately estimate collection rates and corre-
sponding crew and equipment requirements.
• Do NOT believe equipment salesmen; visit existing systems for truth/problems.
• Investment in equipment operator training is well worth it. The biggest budget item
in collection of recyclables is labor; therefore state of the art equipment (stand up
dual drive; mechanical loading) is worth the investment.
3. Stimulate program planners to give sincere open minded consideration to com-
peting ideas, policies and techniques and TRUTH.
• Can materials be added/deleted which will have a net positive impact on total
system costs?
• Are our collection vehicles consuming more energy than they are ostensibly saving
due to too frequent collection?
• Can we justify making collection of recycling a "jobs" program?
• What are the true costs of my program?
• Could the program be operated more cost-effectively by municipal crews or private
contractors?
• Are our publicized participation (% of households), productivity (households
serviced/hr), and diversion (% of municipal waste stream) rates truthful?
638
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CONCLUSIONS
Curbside programs can be implemented at no extra cost to a municipality if
properly integrated into existing solid waste management systems.
Unbending adherence to the goal of minimizing labor is essential to attain program
cost-effectiveness.
Everything else being equal, commingled programs will achieve higher waste
reduction rates than those "inconveniencing" residents by required "separation
work".
Program designers and managers must remain totally open minded to new ideas,
policies and techniques which will increase program impact and reduce program
cost.
639
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TABLE 1.
Recyclable Material Curbside Collection Program
Operated by
Waste Control Systems, Inc.
Population
Households
Program Cost
Material Collected
Annual Tonnage
Cost per ton collected
Collection Frequency
Average Participation
E. Longmeadow
13,000
4,000
60,770
Mixed paper
1,000
Bottles/cans
285
_ _
$47.29
Once/4wks
90-95%
Municipality
Longmeadow
16,000
5,200
80,040
Newspaper
1,300
Corrugated
260
- .
$51.31
Once/2wks
90-95%
Montague
8,000
2,600
41,600
Newspaper
416
Corrugated
• 80
Clear Glass
80
$61.54
Weekly
50-60%
Waste Stream Reduction
31%
23.5%
17%
P.RTEducation Budget
<$500
<$500
<$200
Enforcement
Recycling coordinator
Mandatory
No
Mandatory
No
Voluntary
No
Collection Equipment
Sideload packer
RH drive
17 cu. yd.
Sideload packer
RH drive
17 cu. yd.
Specialized recycle truck
RH drive
31 cu. yd.
Collection Crew Size
640
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"INVOLVING THE CORPORATE CITIZEN IN RECYCLING"
By Dale Gubbels
Resource Integration Systems, Ltd.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
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With rare exception, communities rushing to implement
recycling programs immediately set out to target the residential
sector. There are several explanations, but I suspect a major reason
is that we have been conditioned to accept that people are the root
cause of the garbage problem and therefore, we must seek them out
in their burrows to make them recycle. Of course, ultimately it is
the individual who must be taught to recycle, but I think the issue ~
and thus our responses to solve the problem ~ require us to
scrutinize in what capacity and exactly where individuals are
contributing to the waste stream. Given that perspective,
government ~ local, state and federal ~ would be better advised to
first target the corporate citizen before targeting citizens in their
homes.
There are numerous reasons for this suggestion. An important
one surely is that the American workforce generates a lot of waste.
I'll come back to that in a second, but I want to stress that an even
more compelling justification is that unless the private sector adopts
packaging and product design parameters which adhere to the
hierarchy of resource conservation, those objectives will never be
achieved fully.
I think anyone who has dealt with the problems of finding
markets for the recyclables they collected, or has had to cope with
contamination restrictions which result in belying any claims that a
material is recyclable, will agree with that view. Therefore I won't
dwell on why we should target the private sector in recycling
programs, but rather I prefer to relate some examples as to how
governments can and have accomplished that goal.
But first, referring back to the waste reduction potential by
focusing on nonresidential wastes, our experience at RIS is that most
communities will find that 40 percent and higher of what enters
their local waste disposal systems comes from the
commercial/industrial sector. This can include offices, stores,
institutions, factories and construction demolition wastes.
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Let me give you a little personal perspective on that point. For
Earth Day, our office participated in a contest with RIS's other three
offices to see which one could achieve the greatest landfill diversion
rate. We weighed all of our office's trash - there were 14 of us ~
for a week. We practice waste reduction and reuse strategies ~
such as copying all internal forms and communiques on the backs of
discarded documents, making scratch pads from used paper,
providing mugs rather than disposal cups and using a cloth towel
linen service for rest rooms ~ so I suspected our numbers were not
typical.
With these practices, we generated a per person weekly
generation rate of 3.12 Ibs, a weekly total of 43.7 Ibs. That compares
quite favorably with the National Solid Waste Management
Association's typical office estimate of 1 Ib. per 100 square feet per
day. Based on our office square footage and NSWMA's estimate, we
would generate 100 pounds of garbage per day.
Of our office's waste stream, a little less than half -- 17 Ibs. -
was high grade paper. Low grade paper, corrugated and
commingled recyclable containers accounted for another 12.5 Ibs.
Kitchen wastes were another 8.7 Ibs. Because we have markets and
an on site compost bin, we were able to divert all of the above,
leaving 5.5 Ibs. of mixed waste for an overall waste diversion rate of
87.4%. I should add that we won the competition.
But not all businesses are likely to be as psyched for waste
diversion as a recycling consulting firm. But with the right types of
incentives and direction provided by the local waste authorities — in
some cases, shoves and heavy sticks — the business community will
respond very favorably to waste diversion.
Actually, I think the communities which have developed
commercial recycling programs are usually pleasantly surprised at
how well received recycling is by businesses. In fact, one of the
major reasons I believe they should be targeted before tackling the
residential sector is that commercial recycling can be much easier to
implement.
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Most businesses will gladly cooperate with recycling programs;
the savings from avoided disposal costs alone are very tangible
incentives, plus firms can enhance their public image and employees'
morale. Allow me to share a few anecdotal examples.
Broome County in south central New York has established a 44
percent waste reduction goal by 1992. One of the first things it did
to achieve that goal was to raise its landfill tipping fees which had
been supported in part by the general tax base and also did not
include provisions for closing and monitoring the site. Consequently,
the fees went from $12 to $38 per ton. A three hundred percent
disposal fee increase got a lot of people's attention.
One person's whose attention was grabbed immediately was
the grounds manager for a local factory. His annual disposal costs
could have easily increased by $160,000. To this gentlemen's and
his company's credit, he had contacted us to help develop a recycling
strategy prior to even learning of the county's intentions.
The next thing the county did was to pass an ordinance
banning certain materials from the landfill, beginning in December
this year. The materials include:
• suitable paper products
• recyclable metal, plastic and glass food and beverage
containers
• large appliances
• yard wastes, including leaves, grass clippings and brush
• demolition debris
• tires
• wet and dry cell batteries.
The disposal ban may not necessarily mean that these
materials must be recycled at the source by the generator. For some
materials, such as tires and demolition debris, the generator may
simply pay a premium above the tipping fee at a disposal facility for
certain discarded materials that the county may later attempt to
recycle.
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The legislation covers the commercial/institutional sector as
well as the residential sector. Since commercial/institutional solid
waste constitutes approximately half of the county's total solid waste,
the waste disposal practices of this sector will be targeted, and
companies can expect to encounter greater scrutiny. The county is
anticipating an "adjustment and education" period of one year,
during which time violations will not be subject to enforcement and
penalties.
The county has hired a staff person to work directly with small
businesses to help them locate markets and meet the new
requirements. It has also contracted with us to hold a workshop
this fall for further technical assistance.
The city of San Jose, California, was one of the first
municipalities to hire a full-time staffer to provide technical
assistance to local businesses. The city provides a free inspection —
or waste audit -- to businesses. These onsite visits are a very
practical and cost effective means to motivate businesses to recycle.
States, also offer advise and information to businesses for little or no
charge. Rhode Island is a very good example, and I will touch on it
again in regards to its legislation requiring businesses to recycle.
One means for encouraging a win-win situation for businesses
and local waste authorities intent on waste reduction would be for
the authority to sponsor a loan program whereby it would pay the
up front costs for any business wishing to implement a recycling
program. Balers, carts, crushers -- consulting services ~ would be
just a few examples of some of the types of expenses eligible for
coverage.
The repayment for these loans could be accomplished by
adding the charge to the businesses tipping fee. Where private
haulers provide collection, the waste authority could compensate the
private haulers for serving as the collection agency by giving them a
small percentage for facilitating the transactions.
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Once the recycling effort is up and running, the business should
experience a drop in its disposal fees. That savings would be
applied towards the repayment of the loan.
The initial seed money for starting the loan program could be a
number of sources:
• a tipping fee surcharge to finance recycling programs
• state grants (not just recycling or solid waste, but economic
development and energy agencies' monies should similarly
be sought)
. • foundations
• bonds
• businesses and trade groups themselves
• banks and lending institutions.
The latter ones may strike some as bordering on the ridiculous:
why would banks want to help fund recycling programs?
For sound economic reasons I assure you. If a business can
show that it will reduce its operating costs by recycling and reducing
its wastes, why wouldn't a bank consider putting up some of the
money? If the local landfill authority agrees to collect payments
and assist in finding markets for participating businesses, it seems
plausible that given such assurances for repayment, the lending
industry would see the merits of providing gap measure funding.
I mentioned Rhode Island's legislation. It requires that
businesses with 250 or more employees develop recycling plans for
the state's approval. Maine has similar legislation, but in Rhode
Island, the state also will serve as the market of last resort. That is
to say if a hauler can't find ways to market the office paper, OCC and
other recyclables targeted by the state, the materials can be disposed
of at the state's Materials Recovery Facility in Johnstown. To date, no
commercial wastes have had to go to the facility.
Let's focus again on what local jurisdictions can do, because, in
spite of what many may think, this level of government can garner
significant contributions and support from the private sector for
solving the solid waste problem.
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Since markets are the foundations stones of any recycling
program, local jurisdictions should diligently pursue strategies which
identify and strengthen outlets for their collected materials. Again,
the private sector should be viewed as partners in that effort.
We generally recommend to our clients that they form a
market development committee whose members would include
representatives from both private and public sectors. Their charge
would be to review and continually recommend measures designed
to increase the recyclability and marketability of the area's waste
stream. Both area government and private sector practices should be
reviewed by the committee.
Deanna Ruffer will address the importance of involving local
recycling firms in a community recycling plan, but my focus includes
those businesses not necessarily involved in the solid waste industry.
Prime candidates for serving on the committee are local
brokers and end users of recyclables, but I think it just as important
to include the large and small generators of solid wastes, bankers,
and public relations firms and any other business that has a genuine
interest to help find or improve local markets.
I alluded earlier to one reason why these firms would want to
get involved ~ enhanced company efficiency — but then there are
important considerations.
In these days of heightened public concern for the
environment, everyone seems to be jumping on the recycling
bandwagon. Let's face it, the environment help sell soup to nuts. I
don't think we need to dwell on why the private sector is getting
involved; I think we should just be thankful that they are.
Some examples of the objectives, questions and issues which
the committee should address include:
• Reviews of government procurement practices.
Is stationery printed on recycled paper? Are public parks using
compost? Can the bids that are let for road construction projects
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require the use of reclaimed asphalt, glassphalt, rubberized
asphalt, and cellulose mulches and compost for right of way re-
sodding? Do bid specifications for traffic signs and barriers
require the use recycled plastics? Do county-sponsored energy
assistance programs encourage the use of cellulose insulation?
Can the bid for printing of public notices specify that they be
printed on recycled paper?
Encourage local businesses to use recycled products.
Could area manufacturers replace primary resources with
secondary resources (recyclables) in any of their operations?
Examples include modest low-tech efforts such as using shredded
mixed paper or reclaimed plastic "peanuts" for packaging,
retrofitting equipment — e.g., plastic injection molders — to use
recycled resins.
I think we too often forget that recyclables are resources and that
our local businesses themselves use resources. An inventory of
their needs and your community's ability to fill those needs with
its reclaimed resources is a natural. In Broome County, a local
landscaper set up a composting operation to handle its yard
waste. It soon began helping other businesses by accepting their
food processing residues.
Work with economic development agencies to encourage market
development opportunities.
Chamber of commerces, local, regional and state economic
agencies, utility companies and business associations are all
potential allies. Do they understand that your community's
recycling program will be "mining" resources which industries
need? Perhaps these agencies would sponsor market research
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efforts for various troublesome materials, such as tires or used
oil.
Financial Commitment
These efforts need not be costly. For example, advising
vendors of one's preferences for recycled items may in and of itself
lead to options for purchasing less expensive products. Some
agencies have found in their review of procurement practices that
bid specifications required all products be made of "virgin materials."
This stipulation often reflects outdated prejudices based on
misinformation.
Further support for using recycled products can be shown by
stipulating that procurement agents purchase recycled items even
when their costs exceed that of virgin products made. Five to 10
percent price preferences are used by several jurisdictions. One way
to give such products preference, but demonstrate fiscal
responsibility, is to dedicate the revenues from office paper recycling
programs to offset the price difference for using recycled paper.
The purchasing power of governments and businesses can be
applied even more directly to secure markets for their recyclables.
For example, oil suppliers for the county's vehicles could be required
to accept the county's used oil. Similar stipulations could be made
for asphalt removed as part of road work and construction
demolition/ Several of the firms we developed recycling plans for
adopted this recommendation, with excellent results. One client in
particular found that its vendor not only willing to start hauling back
its empty plastic spools, but it could rebate our client since the
vendor was allowed to reuse the item.
The voluntary nature of your local committee assures that the
only tangible costs for the effort would be administration costs for
coordinating the committee's meetings.
I should point out another major reason for businesses to want
to get involved locally in this issue, and it ties back to the point
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concerning the design for recyclability. Industry is getting involved
in recycling like never before for fear that they may otherwise be
banned from the marketplace.
Contra Costa County, California has a plastics recycling
committee, the members of which include representatives of Proctor
and Gamble, Del Monte, the Council for Solid Waste Solutions and
Dow. These businesses are highly visible in the area and they are all
good corporate citizens, but I don't think anyone is so naive to think
that the county's review of legislation to limit non-recyclable
materials did not motivate these firms to action.
I am not recommending that communities threaten anyone
with bans, fines, taxes or any other punitive actions. Far from it.
Gaining attention with bans is one thing, but I think there are only so
many times you can throw a brick through a window before you are
labeled a vandal. I think industry has gotten the message to get
involved in recycling. Now society needs to develop constructive
ways to channel industry's involvement.
Some positive examples for how companies might collectively
get involved exist already. In the Northeast, the Coalition of
Northeast Governors' Source Reduction Council created last
September is an excellent example. Representatives of major
industry and nonprofit organizations has joined with CONEG, a nine
state regional group of governors, to focus on the means to reduce,
minimize, return, reuse, refill and recycle packaging.
Across our border to the north, the Ontario Multi-material
Recycling Industries, OMMRI, is a program funded solely by the
private sector to help Ontario achieve its 50% waste diversion goal by
2000. OMMRI's initial members are Ontario Soft Drink Association,
the Grocery Products Manufactures, the Ontario Printing Papers
Users Group, the Packaging Association, the Council of Grocery
Distributors and the Society of the Plastics Industry (all of Canada).
Its goal is to take a proactive, cooperative stance with the
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government to achieve the opportunity to recycle for 80% of all
Ontario households by 1995.
It intends to invest $45 million over the next five years,
making this money available to local municipalities on a matching
grant basis.
A similar group has formed in Europe ~ the European
Recycling and Recovery Association. It is studying the OMRRI
system as its model of operation.
Back in this country, such cooperative coalitions have been
slow, to develop, but the makings of such efforts are there. Witness
EPA's and the National Recycling Coalition's formation of the
Recycling Advisory Council. While its purpose is advisory, I have
hopes that, because this group involves major CEOs and top
environmental and public sector leaders, it can be the genesis for
much more tangible support for recycling than the advisory role it
has currently adopted. If not the RAC itself, surely it will be
exposed to the idea for a broad, multi-faceted and multi-material
coalition of industries which works for a common goal to bring about
sensible recycling, and resource conservation policies.
If the RAC doesn't discuss this idea, perhaps you can put it on
the first agenda of your local business and industry recycling
committee.
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LOCAL GOVERNMENT RECYCLING PROGRAM DESIGN
INTEGRATING EXISTING RECYCLERS
Deanna L. Ruffer and Susan Schaefer
Roy F. Weston, Inc.
6021 Live Oak Parkway
Norcross, Georgia 30093
404/448-0644
Presented at
First U. S. Conference on Municipal Solid Waste Management
June 13-16, 1990
653
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Abstract
Markets are essential partners with local governments in recycling programs. While
local governments typically focus on determining what markets exist, too often, the
existing capability of local recyclers has been overlooked. As a result, recycling
programs are designed and, in many instances, material recovery facilities constructed
when they may not be needed, costing both time and money, and ultimately competing
for the materials that have kept private recyclers in business for many years.
While typically it will be unlikely that existing firms will be providing the materials
collection services needed for many local government recycling programs, the
consideration of existing recyclers to address processing requirements of the recycling
programs can be crucial to the successful, fast track development of recycling programs.
Local recyclers can, if considered, be valuable partners with local governments and
provide an important component to successful municipal recycling and composting
programs while at the same time saving the municipality capital costs and
implementation time.
This paper focuses on the questions about capacity, capabilities, and project interest to
consider when assessing local recyclers. Discussion is given to approaches to use in
"winning" the support and cooperation of private recyclers given a natural reticence to
share business information. Ways to begin fostering relationships between local
governments and recyclers early on in the program planning and definition process is
examined. An outline of practical information to request in an RFP which gives
preference to existing local recyclers yet seeks certain guarantees of service is presented
based on experience with both local governments and processors. Contract provisions
with a single processor processing materials from multiple programs and multiple
jurisdictions (i.e., curbside, drop-off, commercial, etc.) and equitable treatments of
multiple recyclers is discussed.
All of these ideas are brought together in an innovative approach of demonstrated
success. Benefits can include relative ease and timeliness of implementation, low capital
costs, relative ease to manage, program flexibility and a spirit of cooperation with the
private sector and local business community. All of these are crucial to the success of
local government recycling and composting programs in an integrated approach to solid
waste management.
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Local Government Recycling Program Design
Integrating Existing Recyclers
I. Introduction
n. Private Sector - The backbone of recycling efforts
A. Family Affair
B. "Brokers" "Dealers" and "Processors"
C. Independent Entrepreneurs
1. A strength
2. A weakness
III. Local Government - The new kid on the "recycling" block.
A. Mandates, Goals and Policies
B. The Results
1. Surveys
2. Curbside, MRFs, etc.
3. Markets?
IV. The "fit" with private sector.
A. Services Needed
B. Government Partnerships
C. Contractual Requirements
D. Costs and Implementation
V. Identifying Capabilities
A. What to look for
/
B. How to get information, support and cooperation
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Local Government Recycling Program Design
Integrating Existing Recyclers
C. Realistic Assessments
D. Fostering relationships early
E. Public-private partnership foundation building
VI. Contracting for Services
A. Structuring the procurement
1. Separation of responsibilities
collection
processing
material/revenue
2. Preferential criteria without sacrificing
reliability
cost of service
B. Providing for
1. Security
2. Control
3. Flexibility
C. Monitoring provision of service
VII. Benefits/Weakness
A. Entrepreneurial spirit/reticence to share information
1. During information gathering
2. During procurement
3. During contract
B. Ease and timeliness of implementation
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Local Government Recycling Program Design
Integrating Existing Recyclers
C. Costs
D. Program Restrictions/Flexibility
E. Spirit of Cooperation
F. Responsibilities matched to capabilities
VIII. Conclusions
A. Not for everyone - but should be considered by all
B. Needs to be thoroughly thought out and contractually defined
C. Integration/partnership "attitude" is critical to success
D. Early identification of capabilities 'and program monitoring are critical to
success
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MAKING IT WORK: TRENDS FOR HANDLING LANDSCAPE WASTE IN ILLINOIS
by
Deborah Havenar and Allen Bonini,
Illinois Department of Energy and Natural Resources (DENR)
325 West Adams, Room 300, Springfield, IL 62704
(Session: Recycling and Composting - Composting/Yard Waste)
In Illinois, landscape waste is generated at an estimated annual rate of
nearly 2.8 million tons. By law, landscape waste, which includes leaves,
grass clippings and brush, must be diverted from landfill disposal by July 1,
1990. Management alternatives to be in compliance under this new law include
composting and agricultural use.
The Illinois Department of Energy & Natural Resources has taken the lead in
providing technical and financial assistance necessary to carry out composting
programs in communities throughout Illinois. To date, over 100 local and
regional landscape waste programs are well on their way in an effort to meet
the landscape waste challenge.
Close to $5 million will be used to assist these programs through grants which
can be used for equipment to collect landscape waste separately from refuse
and also for compost facility equipment that process landscape waste into
finished compost. Emphasis is placed on funding those programs which provide
a comprehensive approach to managing yard waste - collection, composting and
marketing.
Valuable information can be obtained from funding composting programs. Trends
can be identified in all aspects of the composting process. Among the trends
are collection schemes in a rural setting vs. a metropolitan area. Also,
which composting technology - high, medium, or low - is most appropriate for a
particular area? Finally, what are the most viable markets for the finished
compost - giveaway programs vs. bag & sell programs; residential markets vs.
commercial markets?
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MARKET DEVELOPMENT AND BUYING RECYCLED PRODUCTS;
PROSPECTS FOR THE 1990s
Richard Keller
Northeast Maryland Waste Disposal Authority
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
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MARKET DEVELOPMENT AND BUYING RECYCLED
PRODUCTS: PROSPECTS FOR THE 1990's
RICHARD KELLER, PROJECT MANAGER
NORTHEAST MARYLAND WASTE DISPOSAL AUTHORITY
Recycling involves three distinct steps: collection, manufacturing and
use. These steps are represented by the three arrows in the traditional
recycling symbol. The three arrows must be in balance if we are to fully
realize recycling's potential for waste management, energy conservation and
resource conservation. Merely collecting recyclables is not recycling.
Recycling does not occur until a product made from recycled materials is
actually used by a final consumer.
In order for the United States to achieve maximum recycling in the
1990's, state and local governments must make sure that markets are
available to absorb the new supplies. For some materials, markets will
naturally grow as new supplies become available. For other materials, the
public and private sector must work together to promote growth in
industries that can rely on secondary materials in their production
processes.
State and local governments must be concerned about existing and future
markets for recyclable materials. We must take steps now to plan for
future markets.
One of the most important roles that public officials can play in market
development is to ensure that materials collected are clean, separated and
662
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meet industry specifications. They should also let potential markets know
about the timing and availability of new supplies.
There are a wide variety of market development tools available to public
and private agencies to increase the markets for recyclables. The majority
of these tools are activities that must be undertaken by the state and
local economic development agencies. Recycling must be understood as an
economic activity, not as an environmental activity.
The National Recycling Coalition has recently adopted a policy regarding
market development. The policy emphasizes the importance of reliable
markets and the need for public / private cooperation to expand markets.
The policy includes the following market development instruments:
* material processing facilities;
* contracts between suppliers and manufacturers;
* economic development programs (including financial assistance and
assistance with facility siting and permit review);
* regional cooperative brokerage and transportation management
programs;
* preferential procurement of recycled products;
* information and research programs (such as information
clearinghouses, and public, private and university R&D consortia)
to develop new recycled products and expand the use of recovered
materials in existing products;
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* investments in transportation infrastructure and marketing
programs to facilitate increased use of recovered materials
domestically and overseas;
* reassessment of material and product standards and specifications
and consumer and business education programs to expand demand for
recycled products;
* revisions in the tax codes, including differential packaging or
materials taxes that favor recycled materials; and
* additional market development instruments as innovation and change
within the recycling industry require.
PROCUREMENT OF RECYCLED PRODUCTS
According to the National Institute of Governmental Purchasing, ~
government purchases represent approximately 20-21% of the Gross National
Product (GNP). This breaks down to 7-8% federal and 12-13% state and
local. Governments also have an important role in influencing private
purchases, both through leadership by example and through their standards
and specifications. Thus, government can influence private groups, from
non-profits to Fortune 500 companies, to use recycled products.
At the federal level, the U.S. Environmental Protection Agency (EPA) has
published five guidelines (paper and paper products, rerefined oil, retread
tires, building insulation products and fly ash in cement and concrete) to
provide guidance to federal agencies, and state and local agencies and
contractors using appropriated federal funds. The guidelines include
664
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information on specifications, minimum content standards, and
recommendations on establishing a procurement program. EPA is also
examining the feasibility of guidelines for building and construction
materials, rubber products, asphalt rubber and yard waste compost.
Information on the guidelines and federal implementation can be obtained by
contacting the EPA guideline hotline at (703) 941-4452.
At the state and local level, the National Recycling Coalition has
identified 38 states, the District of Columbia and 16 local governments
that favor recycled products. The 37 states and the District of Columbia
represent approximately 221 million Americans, or about 90% of the U.S.
population. Just 3 years ago, only 13 states (representing 46% of the
population) had been identified. These programs include general statements
favoring recycled products, goals, set-asides, price preferences,
specification review and other methods to favor recycled products.
Regional efforts are also beginning, such as those by the Northeast
Recycling Council, the Metropolitan Washington Council of Governments and
the States of Minnesota and Wisconsin.
KEY ELEMENTS IN BUYING RECYCLED PRODUCTS
In order to establish a good program for buying recycled products,
organizations should include the following elements:
* commitment to buy;
* review purchasing specifications;
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* common definitions and percentages;
* variety of products;
* testing products;
* phased-in program;
* price incentives;
* cooperation between solid waste and purchasing officials;
* cooperation among manufacturers, vendors and users
* cooperative purchasing;
* data collection;
* waste reduction and recyclability;
* source separation to ensure adequate supplies.
CONCLUSION
Market forces alone are not sufficient to create adequate demand for
recyclable materials. Government recycling programs must include efforts
by economic development agencies, procurement agencies, and the private
sector to create markets for recyclable materials.
Richard Keller is a Project Manager with the Northeast Maryland Waste
Disposal Authority. He is also Vice-Chairman of the Program Committee and
Chair of the Market Development Subcommittee for the National Recycling
Coalition. He has been involved in promoting programs for recycled
products since 1975. He is a frequent author and lecturer on procurement
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and market development. Mr. Keller also manages the Coalition's peer match
efforts. He can be reached at (301) 333-2730.
1083.RK
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MUNICIPAL SOLID WASTE COMPOSTING IN WEST GERMANY
THREE CASE STUDIES
Henry R. Boucher, Principal Engineer
Camp Dresser & McKee Inc.
Edison, New Jersey
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
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MUNICIPAL SOLID WASTE COMPOSTING IN WEST GERMANY
THREE CASE STUDIES
Henry R. Boucher, Principal Engineer
Camp Dresser & McKee Inc.
Edison, New Jersey
This is a presentation of a fact-finding tour in 1989 of three muni-
cipal solid waste (MSW) composting plants in West Germany. The three
plants visited process between 80 and 200 tons a day of mixed municipal
solid waste (residential waste only at one plant), producing three basic
output streams: compost, recyclables, and residue. The tour pointed out a
number of important factors to consider when evaluating a solid waste
composting plant, including composition of the incoming waste, recovery of
non-compostable recyclables, end uses of the compost product, and residue
and reject disposal.
The three solid waste composting plants visited are located in
Duisburg, Aurich, and Bad Kreuznach, West Germany. All three plants employ
the DANO drum in the composting process. We now look at each one.
DUISBURG, WEST GERMANY, COMPOSTING PLANT
In operation since 1958, the Duisburg composting plant is a 2-drum
system which for the last four years has been composting domestic MSW from
a select area of the City of Duisburg comprised of about 95,000 residents
in single-family and two-family dwellings with relatively large gardens.
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The input waste is collected in 120 liter (32 gallon) and 240 liter (63
gallon) containers only. 17,000 to 20,000 tons per year are processed.
The plant is operated Monday-Friday with one 8-hour shift. The labor force
is 9.
To keep heavy metal concentrations down, household-only MSW is com-
posted. The rest of the City of Duisburg's (pop. 550,000) solid waste is
incinerated. Plant management noted that the composting plant was but one
part of the city's overall municipal waste management system, whose primary
purpose is not necessarily to produce compost but to process a portion of
the city's waste.
From November through January, the plant stops composting household
refuse and composts the leaves collected throughout the city (about 19,000
cubic yards per year, or about 9,400 tons).
Other wastes processed at the plant are stable manures from the city
zoo and a slaughterhouse (about 1100 tons per year) and grass clippings.
Because the service area has small lawns and because backyard composting is
widely practiced, the quantity of grass clippings is small (about 2200 tons
per year).
The plant is situated near residential areas, an in-city location. A
sewage treatment plant also exists on the site.
Plant management noted that their main emphasis is on marketing the
compost. Major markets for the compost are farmers, nurseries, and as a
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bio-filter for odor control at other waste treatment plants (about 60 to 70
percent of the compost is marketed as a biofilter). To maintain market-
ability, much time is spent on process adjustments to ensure that the com-
post products suit their markets. Storage space equivalent to two years'
processing capacity is available onsite. In the years selling compost
products made from household MSV, plant management reports that there has
never been a time When composting was stopped due to lack of sales.
It should be noted that this plant processes household refuse only;
wastes from commercial sources such as corrugated cardboard, office paper,
mixed paper are not composted here. Plant management said the DANO drum
can process cardboard and other larger pieces but would do so not to
produce compost but to pretreat the material for incineration (homogenizing
step). This issue relates to collection container size. Limiting con-
tainer size has been found to be important to successful composting opera-
tions because waste from larger containers (e.g., 300 gallons) contains
more bulky material which lowers the overall organic content and dictates
more sorting before the drum.
Process Description
Incoming waste is weighed and is conveyed past a magnetic separator. A
hand-picking operation then removes relatively large and/or non-decompos-
able items such as bottles, tin cans, and plastic bags.
After hand-picking, the waste is conveyed into the 3.5 m x 26 m DANO
drum. Residence time is 36 hours. Recently, according to plant manage-
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ment, sludge has ceased being added to the waste because of concern for
dioxins in the compost. To replace sludge, nitrogen is added to the waste
(the source of nitrogen being added is discarded fire extinguisher
contents).
After the drum the waste passes through two screens, a 16 mm (coarse)
and a 8 mm (fine) screen.
The fresh compost is stored in an aerated static pile curing area. The
source of air for the aeration system is plant air including the drum.
Air passing through the compost is cleansed of odors while maintaining the
piles in an aerobic condition. After 3 weeks of curing, the compost is
transferred to storage. In storage, augur holes are drilled into the
compost piles to create a stack effect and eliminate the need for turning
the piles over.
Mass Balance
For 100 tpd in 5 tpd is removed in pre-sorting. 95 tpd into the DANO
drum plus 28.5 tpd water addition at 30% minus 28.5 tpd decomposition loss
equals 95 tpd out of drum after 36 hours. 38 tpd of rejects from the 16 mm
screen leaves 57 tpd to go to compost curing.
Processing cost is approximately $28/ton (including residue disposal).
Compost revenue is about $5/ton. (1989 figures).
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Comments
o The plant is both a research and testing facility and a
component of the city's solid waste management system.
o The success of the plant in producing marketable compost is
due to: (1) a pre-selected waste stream (household waste
characterized by little bulky waste, high organic content,
little cardboard, office paper and other paper products); (2)
constant efforts by plant management to adjust process so that
compost produced remains marketable; (3) and the marketing and
composting expertise of the plant manager.
AURICH, VEST GERMANY, COMPOSTING PLANT
The Aurich plant, which is located in rural northern Germany, is a
materials recovery and composting plant serving a population of 175,000.
Current throughput is 50,000 tons per year. The labor force is 20. Site
size is about 5 acres.
Process Description
MSW from residential, commercial and institutional sources is processed
by the plant. Incoming MSW is deposited on a tipping floor and pushed onto
a conveyor. The waste is conveyed past a magnetic separator to the hand-
sorting area. Here ferrous and non-ferrous metals, glass, mixed paper,
light plastics, rubber/leather/textiles and household hazardous waste con-
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tainers are manually sorted. Except for the rubber/leather/textiles and
household hazardous vaste fractions, the hand-sorted materials are
recycled. A rotating screen before the DANO drum removes over 100 mm
material (about 15% of input) as reject.
After the drum, the material is separated into over and under 20 mm
fractions. The under 20 mm material is further separated into under 8 mm
and 8-20 mm fractions (fine and coarse compost). About 25 percent of the
input waste is 20 to 100 mm size and about 50 percent of the input waste is
less than 20 mm.
The compost is stored for 2 months and then put on an aeration slab for
filtering.
Quantities and Marketing
For 50,000 tons per year input, compost production is 25,000 tons per
year. 12,500 tons per year of 8 mm (fine) compost is sold in bulk to
nurseries and landscapers ($10-157ton) and 12,500 tons per year of 20 mm
(coarse) compost is sold in bulk to landscapers for soil loosening and
conditioning. A small amount is mixed with peat (necessary to meet heavy
metal limits) and sold in bags to area consumers. The plant has long-term
contracts for coarse compost sales. Sludge addition has been reduced from
40 tpd to 5 tpd because of heavy metal concerns.
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Economics
Overall cost (incl. capitalization, transportation, collection, pro-
cessing and residue disposal) is about $30-38 per ton. Average revenues
are less than $5/ton. The construction cost (1982) was about $7 million.
Bad Kreuznach, Vest Germany, Composting Plant
Located in an industrial sector of the city of Bad Kreuznach, the new
DANO composting plant in Bad Kreuznach went into operation in 1987 and was
designed to operate as a continuous, highly mechanized facility with
several hand-sorting stations for separation of recyclables prior to com-
posting. However, at the time of the plant visit, numerous plant mechan-
isms were not operating and the plant process train was not functioning as
originally designed.
The plant employs a single 4.25 meter x 40 meter DANO drum with a
design capacity of 220 tons per day. The service area population is
145,000. The facility is publicly owned but privately operated. MSW from
residential and commercial sources is processed.
Process Description
MSW is deposited on an enclosed tipping floor where the material is
pushed onto a steel plate conveyor. The waste is separated by a trommel
screen into two sizes: under and over 15 mm. The under 15 mm material is
sent directly to landfill (about 18 percent by weight of incoming
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material). This step was implemented because it was thought that the
smaller particles were largely responsible for high heavy metal concen-
trations. This has since been found not to be true and government
permission is being sought to eliminate this step since a significant
amount of compostable material exists in the under 15 mm fraction. The
over 15 mm MSW is then conveyed past a magnetic separator and then past 3
hand sorters who manually remove glass, large pieces and plastic. (The
original design called for separating the over 110 mm fraction from the 15
to 110 mm fraction. Each fraction was to go to separate manual sorting
stations, plastics, paper and cardboard hand sorting on the over 110 mm
line and glass sorting on the 15 to 110 mm line). At the time of the
plant visit there was only one sorting line with three sorters manually
removing large objects from the waste stream.
After the sorting and magnetic separation, the waste enters the DANO
drum. Residence time is 24 hours. At the end of the drum, a rotating 80
mm screen separates the material into over and under 80 mm fractions. The
over 80 mm material is landfilled. The under 80 mm material passes through
another screen which produces under and over 18 mm fractions. The over 18
mm fraction is landfilled. The under 18 mm fraction is conveyed to a
ballistic separator, a device for removing hard material (glass, metal,
etc.) from the compost. The ballistic separator was down on the day of the
tour and had not worked well in the past (40£ efficiency of separation of
hard material). The under 18 mm material represents the final product
which is transported to the storage area for three months of storage. A
short curing step on aerated slabs is not practiced. Storage area onsite
is inadequate; as a result compost piles are 3 meters high instead of the
recommended 2 meters.
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One third of the input becomes compost; another third is landfilled;
and the remaining third consists of decomposition loss and metal and glass
recyclables.
Operating cost is about $33/ton; capital cost vas about $16 million.
The labor force numbers 18.
The compost product was relatively coarse (18 mm) and the product
contained bits and pieces of metals, glass, plastic, etc.
The Bad Kreuznach operation is basically designed for the unique market
it has always had—an erosion control product for the German vineyards (the
plant is in a wine-growing region), sold for about $5/ton. For this end
use 100% pathogen removal is not required. The product is not approved,
nor aesthetically suitable, for household use. To produce clean salable
metal, the over 110 mm material removed by the magnetic separator must be
re-sent past the magnetic separator. Sorted glass has been difficult to
recycle because of high broken glass content.
Findings and Conclusions Based on the Three Plants
o Compost marketing is the most important challenge for plant
operators. (One operator reported that the majority of his
time is spent on product marketing).
o The Vest German solid waste undergoing composting exhibited
important differences from typical Northeast U.S. waste.
Based on observations, the following differences were noted:
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Less newspaper
Fewer aluminum cans and glass bottles
Substantially less paper and plastic packaging material
Little bulky waste
Less junk mail
More food waste (no kitchen food disposers)
Little corrugated and office paper in compost plant waste
streams
o On average, forty to fifty percent, by weight, of material entering
the plants was screened out be landfilled or incinerated.
o Since the DANO composting plants visited in V. Germany are pro-
cessing a different waste stream than typical U.S. MSW, caution
should be exercised about transferring the results achieved at
these Vest German plants to the U.S. situation.
o The hand-sorting materials recovery process was not producing
a large, high quality recyclables stream. Substantial amounts
of recyclables were not being removed by the sorting step
before the drum.
o Odors were not a major nuisance during the plant visits.
Odor controls such as biofilters are used to control odors.
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o Provisions for leachate control vere not evident at the
plants.
o Substantial site area is devoted to compost storage.
(337/LH)
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SUMMARY
CONFERENCE ON MUNICIPAL SOLID WASTE
NEW JERSEY MARKET DEVELOPMENT PROGRAMS
BUSINESS RECYCLING LOANS
Business recycling loans, ranging from a minimum of $50,000 to a
maximum of $500,000 or higher for certain projects that are deemed
necessary by the Department, are available to qualified businesses. The
maximum term of the loan is 10 years at fixed rate of 3 points below the
prime rate. A minimum 10 percent equity contribution of the total cost
of the project is required from the businesses.
New Jersey businesses which collect, separate, process and convert
post-consumer waste materials into new or marketable products are
eligible for these loans. Recyclable materials include: paper, metal,
glass,-plastics, textiles, tires, food waste, motor oil. leaves, wood and
wood products, asphalt, brick and concrete.
RECYCLING EQUIPMENT TAX CREDIT CERTIFICATIONS
The Recycling Act provides for the availability of a 50 percent tax
credit to corporations operating in New Jersey that purchase recycling
equipment. The recycling equipment tax credit is applied directly
(dollar for dollar) against the NJ State Corporate Business Tax. To be
eligible:
1. Recyclable materials must be post-consumer in origin;
2. Recycling equipment must be purchased as of October 1, 1987, or
thereafter, and used exclusively in NJ;
3. Equipment purchased must be certified as eligible by the
Department; and
4. Not more than 20 percent of the total tax credit can be applied
in any one year.
STATE PROCUREMENT OF RECYCLED PAPER AND PAPER PRODUCTS
The Recycling Act required that not less that 45 percent of the
dollar amount of paper and paper products purchased by the State after
July 1, 1989 be spent for recycled products. Priority purchasing must be
given to products with the highest post-consumer material content. In
1988, 59 percent of State expenditures for paper and paper products were
for recycled products. State expenditures for paper prorincts containing
50 percent recycled content or more was $1,997,641.43.
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RECOVERY AND RECYCLING OF
POST-CONSUMER PLASTIC FILM
John B. Nutter
American Recovery Corporation
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13 - 16, 1990
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RECOVERY AND RECYCLING OF POST-CONSUMER PLASTIC FILM
INTRODUCTION
One of the most visible issues in the world of MSW management is the need to
recycle plastics. Programs to collect plastic bottles are proliferating rapidly and several
facilities for reprocessing these bottles have been built. However, the recycling opportunity
that is being neglected in the push to recycle plastics is the potential to also recycle plastic
film.
Plastic film production is currently much higher than plastic bottle production -
approximately 7.2 billion Ibs./yr compared to around 4.5 billion Ibs./yr. Essentially all of this
film is discarded after a single use, significantly adding to the volume of MSW. This paper
presents a brief summary of how much film is being produced, current recycling efforts,
processes available for recycling post-consumer film, and barriers to increased recycling.
PLASTIC FILM PRODUCTION AND USE
Domestic consumption of plastic resins in 1987 was around 44 billion pounds, and
approximately 16 percent of this was used in manufacturing film. As shown in Figure 1, film
production is dominated by low density polyethylene (LDPE) and linear low density
polyethylene (LLDPE), which account for over three-fourths of the film produced.
Consequently, the discussion of film recycling must focus primarily on LDPE and LLDPE
(which are referred to as LDPE in the balance of the discussion).
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Figure 2 illustrates how LDPE film is used. Half of this film is used for packaging,
which includes non-food (industrial liners, shipping sacks, etc.) and food (produce, bread,
etc.) applications. Trash bags, at 19 percent of total consumption, represent the next largest
category followed by shrink or stretch film at 10 percent. The remaining film is used for
construction, agriculture, or other non-packaging applications.
FILM RECYCLING
Film recycling rates are highest for scraps generated in manufacturing processes,
which are also known as "home" or "prompt" scrap. While nearly 100 percent of this scrap
is recycled in many facilities, it is estimated that overall recycling rate is only 60 to 80
percent. Factors influencing how much a processor recycles include whether coatings are
used in the manufacturing process, how much space is available to store scraps, whether the
film is laminated to other materials, and equipment capabilities.
Recycling of post-consumer film scrap, in contrast, is very low. This is particularly
true if it is dirty or if the supply contains a mixture of different resins. It is estimated that
the average recycling rates for film discarded by large users (i.e., large industrial or
commercial firms and agricultural sources) is between 5 and 20 percent, but the rates for
small firms and individuals is under 1 percent. Note that at present most of the post-
consumer film that is recovered for recycling is exported rather than processed in the U.S.
Recyclers of post-consumer plastic film are most interested in low density and high
density polyethylene. When the film is used to produce mixed plastic products (e.g., lumber,
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playground or parks equipment, pallets, traffic control barriers), the polyethylene serves
largely as the "glue" that holds the mix together. In these applications, a small amount of
dry dirt or other types of resins are generally acceptable.
To generate a higher value product from the recycled film, it must be cleansed to
remove dirt, organic material, and other types of resins such as polypropylene and PVC.
The resulting clean blend of recovered LDPE and HDPE can be used to manufacture film
products (for trash bags, agricultural, construction use) or extrusions (pipe, conduit, gutters,
etc.). The balance of this discussion will focus on these higher value applications.
RECYCLING PROCESS
The five basic steps in the recycling process used to generate high value plastic resin
are:
o Collecting the material
Purchase bundles or bales of film from high-volume generators or
materials recovery facilities (MRFs)
Extract it from the mixed waste stream
o Cleaning and Separating
Wash to remove dirt, product residues, paper scraps, organic material,
and other contaminants
Separate the materials by resin type and possibly color
Dry the cleaned material
o Melting - to generate a liquid, homogeneous material in an extruder
o Filtering — which may be required to remove contaminants missed in washing
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o Pelletizing - to produce cleaned pellets for blending or direct use
While most users prefer pelletized resin, it may be possible to bypass the melting,
homogenizing, and filtering steps if the feedstock is only lightly contaminated. In these
cases, the clean shredded scrap would be fed directly to the end users extrusion system in
which the final screening would occur.
AVAILABLE SYSTEMS
Several manufacturers offer systems for processing post-consumer film and several
systems are in operation in Europe. In addition, several firms are processing post-consumer
film in the U.S. or have announced plans to do so. Figure 3 lists a few of the leading.
equipment vendors and processors.
While the systems produced by these firms are largely similar, they do differ in some
significant ways. The first of these is the film collection method. All of the manufacturers
can process baled film, but only Sorain Cecchini can extract film from the mixed waste
stream1. The second way they vary is in the use of proprietary equipment. Each process
includes some proprietary components, most commonly in the areas of washing, separating
different types of resins, drying, and filtering.
In practice, all manufacturers configure their systems to meet the specific
requirements of each application. For instance, a line dedicated to processing only lightly
1 A brief Description of the Sorain Cecchini technology which can recover plastic film
from mixed municipal waste is enclosed as attachment 1.
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contaminated commercial/industrial scrap may not require a heavy duty washing and filtering
systems.
BARRIERS TO POST-CONSUMER FILM PROCESSING
The most significant remaining barriers to expanded recycling of post consumer film
plastics are:
o Lack of domestic processing capacity — only a few firms are processing (or
plan to process) post-consumer film, and most of these will only process
relatively clean scrap.
o Fluctuating resin prices and demand -- as illustrated in Figure 4, virgin resin
prices (and corresponding recycled resin prices) have fluctuated considerably
over the last several years.
o Cleaning cost — to produce material that can replace virgin resin, it is
necessary to remove:
Dirt and grit - soil, metals, glass, ceramic.
Organic material — food wastes, paper.
Other contaminants such as adhesives, coatings, labels and non-
polyethylene plastics.
o High collection cost
If selling directly to brokers/processors, users with low generation rales
must provide considerable space to store the material until a large
enough volume is generated.
Equipment required to extract film from mixed MSW.
o Need for a stable supply of feedstock — the value of the product will be
higher if fluctuations in composition and availability can be eliminated.
o Potential contamination with photo- or bio-degradable materials - which is
cause for rejection by most users.
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CONCLUSIONS
The capability to regenerate film-grade resin from post consumer plastic film exists
and has been fully demonstrated. Given that plastics is a significant contributor to the
growing solid waste disposal problem, it is essential that U.S. efforts to recycle plastic film
be expanded. Recommendations for increasing recycling of film include:
o Construct facilities to recover and reprocess post-consumer film -- existing
capacity is limited and most facilities are only processing clean film.
o Stop production of bio- or photo-degradable films
o Establish purchasing preferences for products containing recycled plastics
o Expand public education efforts - to increase awareness of the potential to
recycle film
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Figure 1
Plastic Film Production
1988 Total -7.2 Billion Lbs.
Source: 1989 Facts & Figures of the Plastics Industry
Figure 2
LOPE Film Uses
Source: 1989 Facts & Figures of the Plastics Industry
Construction/"
Agriculture
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Figure 3
Him Regeneration from
Dirty Scrap
Equipment Vendors
Sorain Cecchini
American Leistritz
Extruder Corp.
Herbold Granulators USA
Transplastek
Domestics Processors
Union Carbide*
Mobil
Polysource (AKW)*
Sonoco Graham*
Selected small
Processors
'Planned but not yet operating
Figure 4
Resin Price Trends
Source: Plastics World, Composite index for
PE, PS, PP,and PVC
1987
1988
1989
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ATTACHMENT 1
SUMMARY DESCRIPTION OF
SORA1N SOLID WASTE RECYCLING TECHNOLOGIES
INTRODUCTION
American Recovery Corporation's Sorain technologies have a proven track record in solving
the problems associated with waste handling, processing and disposal Sorain has been involved hi
the field of Municipal Solid Waste (MSW) management for over 45 years. Development of the
Sorain MSW processing and recycling systems began in the early 1960s and the first facility using
this technology was placed in service hi 1964. Sorain presently owns and operates municipal waste
collection equipment, street cleaning equipment, transfer stations, composting facilities and one of
the largest landfills in Europe (Rome) with a daily capacity of 4000-5000 metric tons per day. The
knowledge obtained through actual operating experience has played a key role in the development
of the current state of the an Sorain technologies.
DESCRIPTION
The proven Sorain systems are capable of processing waste materials from residential,
commercial and light industrial sources. Each facility is specifically designed to meet the customer's
requirements, based on the following parameters:
Waste composition
Materials to be recovered
Availability of a domestic or international market for the recovered materials
Current cost of alternative disposal methods
All Sorain processing plants require a waste receiving area and the primary processing
system, while the recovery systems are determined by the site-specific parameters described above.
Should the site have the ability, both physically and economically, to support a full-scale
Sorain facility, the plant would have the following processing and recovery systems:
Waste Receiving
Primary Processing System
Plastic Film (Polyethylene) Recovery
Corrugated Recovery
Newsprint Recovery
Mixed Paper Recovery
Office/Computer Paper Recovery
Aluminum Recovery
Ferrous Recovery
Organic Materials Recovery
Combustible Material Recovery
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In addition, the following processing and refining lines could be installed:
Fully automated Composting Systems for the composting of the mixed organic
fraction and/or yard waste.
Plastics Regeneration Systems for the processing of the Low Density Polyethylene
(LDPE) and High Density Polyethylene (HDPE) plastics into LDPE and HOPE
plastic pellets.
Ferrous Refining System for cleaning and densifying the recovered ferrous materials
Aluminum System for densifying the recovered aluminum materials.
Baling System for the recovered paper materials.
The recovered components and products listed above can be recycled and used in the
following manner:
Newsprint, mixed paper, office, computer and corrugated materials as feedstock for
the paper industry.
Plastic pellets for the production of plastic trash bags, pipe, conduit or molded
objects
Compost material as a soil conditioner in parks and gardens
Ferrous metals in the steel industry
Aluminum material in the aluminum industry
PROCESS DESCRIPTION
WASTE RECEIVING AREA
Municipal waste can be brought to the facility by truck or rail. It is weighed as it
enters the facility, and then proceeds to the tipping area. The tipping area can consist of
either a conventional tipping floor or a pit.
When a tipping floor is used the material is handled and moved to the infeed
conveyor with the use of front end loaders. A tipping floor director is responsible for
instructing the truck drivers where to place their loads and for initial screening and
inspection of the load for non-processible materials. The front end loader operator then
moves the processible waste over to the infeed area of the primary processing system and
directs the non-processible material to the reject area for landfill disposal.
When a pit is used the material is segregated by the pit's overhead grapple crane
operator. Reject material is directed by the grapple crane operator to a reject area and
the processible waste is placed in the infeed area for subsequent loading into the primary
processing system.
PRIMARY PROCESSING SYSTEM
The primary processing system is the basis for each Sorain facility. This system
takes the raw waste from the receiving area and processes it for subsequent material
recovery. The system is modular, with each module capable of processing 50 short tons of
waste per hour.
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The infeed conveyor delivers the processible material to the bag breaker. The bag
breaker, a patented and time proven device, has the function of opening up the waste
containers and of providing preliminary sizing of large pieces of cardboard and other bulky
items. This sizing function, and the method by which it is accomplished, allows easier
recovery of the recyclable materials, without the contamination experienced with shredding
systems.
The waste material leaving the bag breaker is then mechanically sorted by its physical
characteristics (size and weight) using a patented self-cleaning trommel and patented air
classifier. This mechanical sorting operation concentrates materials into specific materials
streams which allow for subsequent material recovery.
FERROUS RECOVERY AND REFINING SYSTEMS
Ferrous is recovered using a magnetic conveyor system. Raw ferrous material
recovered from MSW by magnetic separation contains a degree of contamination which can
affect the marketability of the recovered material Therefore a Sorain ferrous cleanup
system is recommended for refining this raw material into a quality product. This system
economically cleans the raw ferrous and produces a high grade product, with a nominal 2
inch diameter, that is clean of paper, plastics and other contaminants.
ALUMINUM RECOVERY SYSTEM
Aluminum is recovered using either hand picking or a fully mechanical eddy current
system. Recovered aluminum enjoys one of the highest recovered materials marketing
prices. The recovered material is densified or baled for market
PLASTICS RECOVERY AND REFINING SYSTEM
Plastic film, Low Density Polyethylene (LDPE) is mechanically recovered from the
waste stream using unique, patented equipment and can. then be processed by the plastics
refining system. The patented refining system will shred, wash, dry, extrude and filter the
recovered Low Density Polyethylene material into a high grade plastic pellet. The pellets
produced by the process are of such a high grade that they can be refilmed into new plastic
trash bags. The plastics refining system can also be configured to allow the direct infeed
of agricultural and other industrial film plastic into the plastics washing line without first
sending it through the primary processing equipment High Density Polyethylene (HDPE)
can also be processed separately to produce HDPE pellets. The system produces a nominal
1/4 inch pellet which can be marketed in either bagged or bulk form.
Sorain also has experience in the use of this recovered Low Density Polyethylene
plastic in the manufacture of new plastic bags, piping and conduit Sorain currently owns
and operates separate plastic bag and pipe production facilities located in Pomezia, Italy.
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PAPER RECOVERY SYSTEM
Paper is usually recovered in the form of corrugated, newsprint and/or mixed paper.
Newsprint and corrugated paper recovery is accomplished by hand picking, after initial
mechanical processing has concentrated the paper material Mixed paper is recovered by
mechanical process. These products are then baled and marketed. Sorain can also provide
a paper pulping system if a market exists for a pulped product
PREPARED FUEL SYSTEM
The system can be configured to produce a fuel product which can be burned in
mass burn, Refuse Derived Fuel (RDF), kilns or fluidized bed boilers for steam and/or
energy production. The type of burner used will determine the processing system's
configuration. Fuel heating values can be controlled through the process to accommodate
the very specific fuel properties required for the type of combustion method used. Sorain
also has experience with the production of palletized and semi-densified fuel products.
COMPOSTING SYSTEM
The composting system is a self-contained process which can accept organic material
separated from the MSW by the primary processing system or from direct outside sources
such as segregated yard wastes. The current Sorain composting system (fourth generation)
represents over twenty years of research and operating experience with MSW composting,
and is covered by two patents. The composting process takes 28 days, and the bed reaches
a temperature of over 150° F during that period. This provides a material that is clean of
bacteria. The material leaving the composting bed is sent through a final refining process
where glass, small plastic and paper fragments, and other contaminants are removed.
The composting system is computer controlled and can be operated with a minimum
of staffing. This system provides for significant weight and volume reduction of the amount
of material entering the landfill The compost material can be used for landscaping or can
be enhanced with chemicals for use as a fertilizer and soil conditioner.
DENSIFICATION SYSTEM
Depending on the final processing system configuration, a densification system can
be installed to enhance the volume reduction capabilities of the facility. After material
recovery, the remaining material is processed through a densifier, which provides a
significant reduction in volume of the reject material to be landfilled.
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STIMULATING MARKETS FOR RECYCLED PRODUCTS
Joan Bradford, Manager
Education Section
Illinois Department of Energy & Natural Resources
Office of Solid Waste & Renewable Resources
Presented at
The First U.S. Conference on Municipal Solid Waste Management
"Solutions for the 90's"
June 16, 1990
Washington, D.C.
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It is government's responsibility to set an example for the public
and private sectors by purchasing recycled products. The most important
point to remember is that the demand for recycled products is what drives
the markets for the materials being recovered. Not enough attention is
given to the market issue. This morning I will describe some of the
successes we have experienced in Illinois regarding recycled products.
Our accomplishments are the result of a lot of hard work, research,
and substantial staff commitment. Following is an overview of our
activities. Central Management Services (CMS), Illinois' administrative
agency, is purchasing recycled bond paper, tissue and toweling, corrugated
and has an open contract for FSC stock forms. The 1989 Illinois income
tax booklets, 1990 state phone directory, and budget books are all printed
on recycled paper. Illinois is working on incorporating USEPA standards
into our state definition for recycled paper. Illinois is the only
midwestern state represented on the ASTM project to develop national state
purchasing standards. The Illinois Department of Transportation will be
testing recycled plastic products manufactured by OuPont. Our education
outreach includes planning a technical workshop for state purchasing
personnel on buying recycled paper and paper products. We will be
developing a corporate waste reduction program for Illinois companies. In
Illinois, as elsewhere, increasing attention is being directed to source
reduction. As you can see, our efforts are varied. Our approach has been
to identify opportunity and need, then pursuing a results oriented
strategy.
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I. We are here today to better understand and to stimulate demand for
products made from recycled materials. Increasing volumes of
discarded waste material, coupled with increased efforts to recover
recyclables mean there must be increased demand for products made
from these materials.
II. Legislation is traditionally passed in response to a problem. Solid
waste is clearly one of those public policy issues that has received
substantial attention in Illinois and elsewhere. Illinois law
provides the basis and framework upon which our solid waste programs
have been developed.
A. Illinois Solid Waste Management Act of 1986
1. Established hierarchy of disposal options:
waste reduction, recycling, incineration, landfill ing.
2. Called for recycling market development efforts by ENR.
This mandate is the basis for our market development
efforts which includes "buy recycled" programs.
B. The past couple of legislative sessions in Illinois set a record
in the number of bills introduced to address the issue of solid
waste, many of them controversial and most don't become law.
However, this activity clearly points to the fact that solid
waste is a major public policy issue.
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III. I'll briefly describe the procurement legislation that has passed and
become law.
HB 1085 (PA 86-452) While not procurement legislation, this law
will provide for eventual availability of products or fuel sources derived
from tires. It calls for the recycling and development of markets for
tire-based products and provides financial assistance. (The funding
source is a 50£ increase in vehicle titles, deposited into the Used Tire
Management Fund beginning Jan. 1, 1990.)
HB 1692 (PA 86-777) Amends the Solid Waste Planning & Recycling
Act. As part of the planning process, requires counties to develop
programs for promoting the use of products made from recycled materials to
county businesses, newspapers and local governments. (The law states that
recycling goals mandated in the county plan are subject to viable markets.)
HB 2326 (PA 86-246) Amends Purchasing and State Printing Contracts
Act. Requires buying and using recyclable paper whenever possible,
including not using colored paper that is not recyclable.
HB 3389 (PA 85-1196) requires all state agencies to maximize the use
of recycled paper products. The total volume of recycled paper is to be
10% by June 1989 (that goal was exceeded with a 13% level), 25% by June
1992, and 40% by June 1996. Procurement consideration is to be given
products with the highest percentage of post-consumer waste material. It
requires the use of compost on state owned lands where feasible. (Another
law bans landscape waste from being deposited in landfills as of July 1,
1990).
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This summary does not include legislation under consideration this
session, which ends June 30, 1990.
VI. Regardless of any laws, buying recycled products and examining ways
to reduce the amount of solid waste we generate in our offices and
schools is gaining increasing momentum:
A. Government, at all levels needs to set an example: federal,
state and local government; school districts, colleges and
universities. Private businesses have a major role to play as
well. There are 3 reasons why we should do this.
1. This combined buying.power is substantial and will make the
difference in making recycling programs successful.
2. We cannot expect to establish recycling (collection)
programs in our government offices, colleges and
universities or company offices without looking at ways to
close the recycling loop by purchasing recycled products.
3. Our vision is short-sighted if we look only at office
paper, i.e., fine and writing grade papers in our
procurement policies. Certainly that is a noble pursuit
and a very visible display of our recycling ethic. But we
must not stop there. There are other recycled products to
consider as well.
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B. Common myths for not buying recycled:
1. Recycled products don't exist
2. Too few sources
3. Quality is inferior
4. Costs are too high
I have observed that lack of information is a major deterrent.
C. Some action and explanation is in order to dispel! the above
myths.
1. Recycled products do exist, refer to the Recycled Products
Guide available on an annual subscription basis from
American Recycling Markets. Product listings are free.
2. Too few sources? This may be the case for some products,
but competition has been increasing. Many companies are
monitoring state procurement laws and general buying trends
to assess how serious we are in buying recycled.
3. The quality is not inferior. True, for some recycled
papers, the brightness may not be as high as virgin paper
for example. The question is, do some of the standards
need to be modified?
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The benefits, I believe, outweigh the faults. For recycled
paper and other recycled products, it is the end use, the
application that we need to address. If products serve the
intended use, are readily available from reliable vendors and at
a reasonable cost, then buy them.
Regarding cost, some recycled products are less expensive, last
longer or reduce our landfill disposal costs. Life cycle
costing (or full cost accounting) is not receiving the attention
it should. In fact, we are working with the Illinois Department
of Conservation where they will do a life cycle costing analysis
on recycled plastic lumber used to build park benches, outdoor
toilets and boat docks. Funding is provided through our market
development program.
VII,, Lack of information is one of the biggest barriers to the problem.
Some ways to overcome this:
1. Statewide recycled product procurement sessions. We sponsored
the first one during the Spring of 1989 in Illinois with 250
state and local government procurement officials attending along
with recycled product vendors who had the opportunity to display
their products. Other states have since duplicated that program.
2. Subscribe to the Recycled Products Guide and if you have the
funds, make it available to procurement officials.
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3. Target potential high volume purchasers of recycled products and
conduct a testing program for the products, which we have done
in Illinois State Government. We tested continuous computer
stock forms made from recycled newsprint by an Illinois mill,
FSC. We have also tested recycled fine and writing grade
paper. The intent of the testing program is to help overcome
institutional barriers.
4. Target agencies and organizations that indicate a strong
interest in buying recycled. Remember, it only takes one
individual to get something started. If you can identify that
individual and provide assistance, you are well on your way to
success.
5. Get testimonials from users of recycled products and publicize
heavily.
6. Conduct a promotional campaign that ties in with Recycling Week,
for example. Last fall we co-sponsored a Fall Recycled Paper
Promotional which included presentations at various state
government subcabinet meetings. Agency directors were given a
hands-on experience, trying to guess which paper sample was
recycled. We also provided information on appropriate
applications of recycled paper for each agency and how to buy
it. We coordinated the promotional with the Governor's Office
and Central Management Services.
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VIII Recycling Market Development Program.
Low interest loans are available for:
1. Manufacturing operations that utilize recycled material in the
production of new products. It is important to stimulate
markets for the increasing volumes of materials being collected
which will result in useful products for purchase.
2. Marketing of recycled products
Grants and loans are available for:
3. Procurement and testing of recycled products. We are providing
funds to the Illinois Department of .Conservation for the
purchase of recycled plastic lumber. The Department will
construct picnic benches, boat docks and outdoor privies. They
will then test them for their resistance to animal destruction.
If the project proves successful, they will expand the project
and save substantial man hours in annual repairs and
replacements.
Closing the loop—government procurement plays a critical role in
this public policy issue.
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Your participation here today can make a difference. You can be part
of the driving force to make recycling, "buying recycled" and buying for
source reduction part of the mainstream, the norm in our purchasing
decisions.
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UK MARKET BARRIERS AND OPPORTUNITIES FOR RECYCLING MATERIALS
FROM DOMESTIC WASTE
John Barton
Warren Spring Laboratory
Introduction
As a manufacturing country with limited indigenous material resources,
the UK has always had a thriving reclamation industry geared to recovery values
from wastes whenever economically feasible.
However, reclamation activities have tended to centre on arisings from
the industrial, trade and commercial sectors rather than the waste materials
discarded by the householder. Where materials from domestic wastes have been
recovered, this has largely been due to the efforts of charity and voluntary
groups (eg scout collecting paper, clothes sent to Oxfam) rather than a
systematic or integrated approach to place recycling as a fundamental element in
the management of domestic refuse.
Obviously there have been exceptions to this general picture, the UK has
a number of nationally available recycling schemes, eg bottle banks for glass,
and many local authorities (eg Leeds Save Waste and Prosper) have developed
facilities for the public. In addition a limited number of pilot collection
schemes (eg Sheffield recycling city) have been implemented to study separate
collection of recyclables directly from households. However, at the present
time, not more than 5% of dustbin type household waste finds its way back into
the recycling loop through these activities.
Once in the dustbin and collected as mixed waste, some of the waste
management treatment systems recover values, eg energy from mass burn
incineration plant and fuel and materials (mainly metal, some compost) from
waste sorting/refuse derived fuel plant. Again less than 5% of mixed waste is
so treated, the remainder is either incinerated without energy recovery (8%) or
landfilled (87%).
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Frankly, in today's world this is simply not good enough. Whilst there
are technical/financial/geographic factors which go some way to explain the
current position, few .would argue that the UK was making best use of resources
or that recycling levels from the domestic waste were at optimum levels in
broader economic/environmental terms.
Neither is this situation acceptable politically, a point clearly
recognised in the summer of 89 when our Prime Minister commended a target of 50%
recovery of recyclables on domestic waste by the end of this decade. This
target calls for a dramatic change in attitude and direction for the wastes
management industry, for industries concerned with converting scrap to reusable
and marketable products and the purchase of these products at the manufacturing,
retail and consumer levels.
In the UK, our Department of Industry has the leading, co-ordinating role
in material resources and recycling but obviously our Environment Department,
with responsibility for local authorities, wastes management and environmental
quality has a major role in terms of unlocking the gate. Essentially the task
is to transform the dilute, diverse and widely dispersed state materials are
found at the household level to the concentrated, high volume and high quality
flows needed for industry to effectively reuse these materials as feedstock to
the processes and products required by the economy.
In order to assess the requirements needed for a rapid expansion of
recycling in the UK to meet the Prime Minister's target, DTI and DoE initiated
the UK strategy group for recycling. This group was drawn together from across
the various sectors and included local and central government, the voluntary
sector, environmental groups, the reclamation and primary industries, retailers,
fillers/bottlers, trade 'organisations, economists and leading academics and
researchers working in the environmental and recycling field.
The remit for the group was clear; for each main commodity in domestic
refuse, eg paper, plastics, textiles etc, review the current practices, identify
barriers, propose solutions for overcoming the barriers and arrive at commodity
recycling targets considered achievable over the next decade. The group's
recommendations were then to be forwarded to Ministers in order to inform their
thinking and policies, with particular reference to the new Environment White
Paper due to be published this Autumn (1990).
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The Potential
To assist the strategy group in their task. Warren Spring Laboratory, the
UK's government owned Environmental Technology Agency, prepared a series of
'fact sheet1 reports covering the main commodities. As most will be aware,
'facts' in the waste and reclamation industries are not easy to come by. Not
only are weight and compositional flows frequently estimated rather than
measured, but definitions of what constitutes 'domestic waste1 are many and data
from the reclamation and primary industries frequently fail to differentiate
sufficiently with regard to the source of 'recycled' feedstocks and materials.
Despite these problems, by considering commodity production and use data
and comparing these with the limited but specific weight and compositional data
for domestic wastes available from research institutes such as Harren Spring, a
broad picture of the loss of potentially recoverable materials was drawn up. A
waste generation figure of approximately 600 kg per houeshold per year for
dustbin waste was used (ie excluding large items such as fridges, cookers,
furniture and garden wastes which are normally collected/delivered for disposal
separately). This equates to -16 million tonnes* per year for the UK as a
whole.
The 'typical* composition of UK dustbin waste was known and furthermore
estimates could be made of the quality and contamination levels associated with
the materials. These are reported elsewhere1 and, excluding options such as
energy and compost recovery, it was estimated that some 40% of the UK dustbin
could in theory be recovered as a 'clean recyclable1 material. How this
'amount' compares with UK consumption, production and current scrap use for each
commodity is very illuminating. Table 1 provides the estimates and a number of
simple points can be noted.
* For some commodities, UK consumption significantly differs from
production, eg UK imports over half her paper and board materials from
abroad.
note, weight as received, ie with associated moisture content of -30%, dry
weight -11 million tonnes.
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TABLE 1. - UK Scrap Use and Potential Effect of Recovering Clean Recyclables from Domestic Refuse
UK Consumption UK Production Current Scrap* Export of Potential*** Current Scrap
tonnes tonnes tonnes Scrap Available from Use as % of
x 10f x 10» Use tonnes Domestic Refuse Production
x 10* x 10* tonnes x 10s
Paper and 9.97 4.32 2.45 0.42 2.5 - 3.0 57
Board
Steel/iron 15.86 20.36 8.86** 3.61 0.8 - 1.0 44
Aluminium 0.53 0.41 0.13 0.11 0.09 - 0.11 32
Glass (containers) 1.75 1.73 0.28 <.01 0.6 - 0.8 16
Plastics 3.25 1.91 0.15 <.01 0.3 - 0.4 8
Factor Increase
Resulting from
Recovery of
Domestic Recyclable
x 2.2
x 1.1
x 1.8
x 4.8
x 6
* includes imported scrap
** includes in-house scrap (not post consumer)
*** 'clean recyclable' estimate
-------
* Some industries, eg paper, steel and aluminium, are well aquainted
with using scrap materials (albeit mainly from non domestic sectors),
other industries, particularly plastics, are not.
* The size of the production industry has a direct bearing on home
market capacity to reuse scrap but for higher value materials, UK also
exports scrap and provides a market for scrap collected abroad.
* For all commodities other than steel, the effect of recovering
recyclables from domestic waste significantly increases amount
currently available/used. For paper and aluminium by a factor of 2,
for glass and plastics by 4 to 6 times.
If nothing else, these data clearly illustrate that even at 50% recovery
of recyclables, major infrastructure changes are needed within UK industry to
accommodate such flows and a major impact on import/export of commodities would
result. When it is also considered that in addition to current scrap flows,
unrecovered potential exists in other non domestic but similar waste streams
(particularly commercial and retail trade sectors) then the need for
direction/co-ordination and promotion at a national level is readily apparent.
Switching on the system cannot occur overnight, the barriers and problems need
thorough analysis and positive action.
In the above comments the definition 'recyclable' has so far only been
applied to materials, the majority of domestic refuse is not suited to reuse as
a commodity. For these residues treatment plant for composting, fuel and energy
recovery will be additional tools for recovering values from domestic refuse.
Such process guarantee significant weight and volume reductions and ensure the
remaining solid residues'are stabilised prior to landfilling. Thus the effect
of upstream materials recycling and the requirements for more widespread use of
such systems were also topics covered by the strategy group. However it is
beyond the scope of this paper to comment in detail on the role of such
systems.
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The Problem
Although the initial report by Warren Spring identified many of the
market barriers to reuse, the experts on the recycling groups provided a more
focused view of the issues as well as new or amended information based on more
recent development either within the UK or abroad.
Common to all commodities was the issue of collecting materials in
merchantable quality and quantities at an affordable cost. Industry viewed an
assured supply as an essential prerequisite to investing in the transport and
processing capacity infrastructure required to reuse the materials, irrespective
of the need to resolve the technical and marketing problem they would encounter
in completing the recycling loop. Local authorities, with the statutory duty
for providing the householder with a cost effective waste disposal system, were
clearly anxious to ensure that revenues and avoided disposal costs would fully
justify instituting the collection systems that might be required.
Both were well aware that although the traditional 'bring systems' such
as bottle banks and paper igloos were affordable due to reliance on the public
to bear the cost of first stage separation and concentration, they were also
unlikely to achieve the high recovery rates across the full spectrum of material
types. They were also clear that in terms of existing UK waste collection and
disposal costs, collection at the household, in simple cash terms, did not look
attractive for all but a small number of authorities. However, putting the
financial issues to one side, as these were critically dependent on
environmental standards and costs of disposal which were undoubtedly increasing,
for most materials the groups agreed that household based collection systems for
recyclables were the practical way forward and set about considering the
technical and market barriers to reuse.
At this point the issues and problems facing the various commodities
began to become much more industry specific. Table 2 attempts to group and list
the issues for each commodity in broader terms and provide a star rating in
terms of priority/seriousness of the problem. Low start ratings indicate
relatively few problem, high star ratings indicate more severe difficulties were
anticipated. Considering the headings used;
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TABLE 2. - Barriers to High Recycling Rates for the Recyclables in Domestic Refuse
Identification Collection UK Technical Problems UK Market Non UK
or Grading Storage Production in Reprocessing for Reclaimed Market
Handling Capacity Material
Commodity
Paper and
Board
Ferrous metal
Aluminium
Glass
Plastics
** * ** * ** **
* *
* * * *
* * ** * ** ***
*** ** *** ** ** **
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* Identification or grading problems are concerned with the preliminary
stage of achieving a recognised merchantable quality, for example
there are 11 different grades of waste paper, most household waste is
of lower fibre quality and to maximise reuse and revenues, quite
strict sorting and grading is required, hence a two star rating.
* Collection/storage/handling problems are concerned with achieving
merchantable quantities, plastics with very low bulk densities and low
weight arisings per polymer type per household have more problems than
most.
* DK production capacity covers scale of new plant investment needed to
process the reclaimed material and experience of the industry in
building such plant.
* Technical problems in reprocessing reflect industries expertise at
reusing such scrap arising and includes problems such as degradation,
achieving high specification, residual contamination build up.
* Market for products made with reclaim reflects perceived consumer
resistance to recycled material, degree of change necessary in
purchasing perference, institutional or health and safety barriers.
* Non UK market options indicate degree to which a commodity is traded
on the international markets, for example, high star rating indicate
market undeveloped due to low value.
In this paper I will take only one material, glass, to illustrate the
type of problems highlighted by the working groups.
Glass is excellent example because, on the surface at least, most people
would consider it to be one of the most easily recyclable; it is easy to
identify, containers are simple in construction with only limited amounts of
'other' materials associated with them, glass melts and can be reformed with
minimal degradation of physical/chemical properties and the industry worldwide
has plenty of experience in using post consumer cullet, in fact a number of
countries in Europe achieved 50% recycling rates last year.
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For the UK. the recycling rate was 17% in 1989 and, although the rate is
currently running at -22%, some significant problems are on the horizon.
From Table 1 it can be noted that 'consumption1 of glass is broadly in
line with 'production' at about 1.7 million tonnes, however UK production is 69%
by weight clear glass, 16% by weight green and 15% by weight brown or amber
whereas the cullet collected from bottle banks, fillers and waste from float
glass production (total -310,000 tonne in 1989) was 25% clear, 37% green, 6%
amber and 32% mixed (mainly green and amber). This difference in colour balance
reflects export/import of filled containers, predominantly clear for UK products
abroad (eg whisky, gin) mainly green for imported products (eg wine, lager).
This is compounded by higher returns of bottles (mainly coloured) as opposed to
jars (mainly clear). Obviously the existence of mixed colour collection
(usually from commercial premises but also for many bottle bank systems operated
for the public) does not help as this mixed glass can only be used in green
glass production. Amber glass is less tolerant than green to other colours (due
to chemical incompatibility with green and clear) and for clear glass, colour
contamination must be strictly controlled. The net effect of the colour
imbalance problem can be seen by considering the amount of cullet used for each
colour, last year clear glass production contained only 10%, amber glass less
than 10% whereas green glass made in the UK already contains in excess of 50%
cullet.
While improvements in colour separation at the collection point and
better returns of jars will enable overall recycling rate of perhaps 35% to be
achieved, rates beyond this will require measures such as export of coloured
cullet or changes in colour purchasing policy by UK fillers (eg bottling more
production in green, particularly for export). Even at current recovery rates,
the distribution of glass making capacity in the UK, particularly the existence
of only one green glass furnace in the South East (the most populated area of
the country) is starting to require long haul transportation of green cullet to
Northern furnaces and hence is reducing the financial incentive for recovery.
Given their own high recycling rates, the likelihood of our European
neighbours having excess capacity to accept green cullet is very low (though
perhaps, not as low as expecting French red wines to be bottled in clear glass!)
and thus I suspect a significant change in colour purchasing and marketing
policy will be needed by UK fillers if UK glass recycling rates are to match or
exceed the 50% level.
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The recycling strategy group also identified a number of other problems,
some technical, some institutional, some economic but concluded that these were
all surmountable given the commitment. However it was not just a 'collection1
and a 'glass industry problem', all sectors of the economy needed to adjust and
change to ensure success.
Routes to Success
The last section gave a broad overview of the problems illustrating the
different nature of these problems for the different commodities, particularly
in the technical and market areas. Furthermore, as for any other country, the
UK has her own specific issues to resolve.
Of major importance is the lack of financial incentive; for the
collection of recyclables the methods that ensure the highest recovery rates, eg
separate collection at the household for the main commodities, are the most
expensive. Experience to date in the UK suggests costs of £50 to £150 per tonne
of recyclable material collected and sorted and these data are not in variance
with reported experience abroad, what is in variance with reported costs abroad
are the avoided disposal costs of implementing such a scheme. For most of the
UK transport and disposal costs are less than £15 per tonne for domestic refuse
(albeit rising fast). These are much lower than the £50-£100/tonne quoted for
some parts of the USA or the £30-£60 tonne for many parts of Germany. Obviously
there are some savings to be made by reduced collection costs for the residual
refuse (typically 70% remains for collection) but clearly markets and revenues
from the sale of the materials collected are very important for a household
based scheme to be financially viable in the UK. For 'recyclables' separately
collected from the household, it can be estimated that the maximum theoretical
revenue, assuming materials meet merchantable quality, would be between £30 and
£40 per tonne.
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A compositional breakdown of the 'tonne* and merchant prices are as
follows:
Commodity
Paper and board
Plastics
Glass
Ferrous
Aluminium
TOTAL
Weight
kg
515
70
280
120
15
1000
Estimated Price
£/tonne
15-25
25-75
20-30
20-30
600-800
-
Revenue
£
7.70-12.90
1.75- 5.30
5.60- 8.40
2.40- 3.60
9.00-12.00
26 -A2
Clearly paper, glass and aluminium provide the main revenue sources and
stable markets and prices for these materials are a minimum requirement. If too
rapid an introduction of collect schemes is attempted without corresponding
development of the industrial capacity to use the materials the effect of the
inevitable price reductions, possibly to negative levels if materials have to be
put onto world markets or simply dumped/stored, will leave the collection scheme
unviable unless/until disposal costs savings rise significantly above current
levels. While it can be argued that this situation can be tolerated for a
period if it ensured/stimulated industrial capacity to use caught up with
supply, it is obviously better to co-ordinate and balance supply and demand for
these commodities as far as possible. It was to this end that many of the
recommendations and suggestions were targetted over and above the specific
commodity based requirements or the general need to ensure careful evaluation
and development of collection systems to identify where improved efficiency and
cost reductions could be realised.
The following list gives some of the more general conclusions and ideas
suggested by the strategy group, some were widely held, some had only minority
support.
* Waste collection and disposal cost saving must be fully credited to
the recycling system.
* Detailed and comprehensive recycling plans must form an integral
feature in waste management plans drawn up by the responsible local
authority body.
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* Purchasing policies, particularly in the public sector, should be
geared to buying products with a high recycled material content.
* Review and elimination of unreasonable specification requirements
which prevent use of reclaimed materials - adequate for the purpose
definitions needed.
* Consideration to be given to assisting investment in industrial
processing capacity designed to accept reclaimed materials (eg tax
breaks, grants).
* Consideration be given to supporting 'buffer stocks' to assist in
stabilising markets/prices.
* Consideration to using differential taxes for virgin as opposed to
recycled materials.
* Consideration of legislation/regulation targetted to assist recycling
eg mandatory facility provision for collection, minimum recycled
content for certain products.
* Use of deposit systems for certain products to ensure return.
In this paper I do not intend to make predictions with regard to actions
that might be taken or how and with what impact such actions might be
implemented. The proposals do however illustrate a recognition that existing
market forces alone were not considered sufficient to achieve the high recycling
levels considered necessary in a world acutely conscious of the environmental
degradation and resource depletion problems caused be waste. On the other hand
following the experience of undertaking and being involved in the studies, few
were arguing for blanket mandatory measures or blanket and arbitory targets.
There was a general recognition that these could well result in a net
resource/environmental losses. It is a simple truth that attempting to achieve
'IOCS' efficiency in one element of a chain inevitably leads to inefficiencies
elsewhere. It is generally accepted that the major environmental problems faced
by the world today illustrate the failings of trying to maximise material wealth
at the expense of sustainable development. Similarly, recycling is but one
element in the effective use of materials and energy starting with primary
extraction of materials and ending in ultimate disposal of waste. Furthermore,
TIB
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household waste is but one potential source of such materials and little benefit
would be achieved if they merely displaced materials recovered from other waste
sources. Recycling has been an undervalued element in that chain for many years
but this does not mean that optimum recycling rates in environmental and
resource terms are the same for different materials or products, the same for
different localities or countries, the same over time. Bearing this in mind,
there was no doubt that the overall conclusion was that positive action to
significantly increase recycling rates from domestic waste could and should be
taken.
The recycling strategy group has gone some way in the process of
formulating action plans, for many sub divisions within a given commodity (eg
newsprint within the broad heading paper and board, plastic bottles within
plastics) and for some commodities in total (eg glass containers, ferrous and
aluminium can stock) recycling levels in excess of 50% recovery and reuse from
households were deemed eminently achievable within a 5 to 10 year time frame.
Identifying the problems in achieving these levels provide the basis for
effective action to resolve them, not an acceptance of the status quo. For
materials still discarded to household refuse, methods of treatment and recovery
of energy and other waste derived products (eg composts, aggregates) will still
have a significant, and for the UK, growing role to play in reducing the weight,
volume and environmental impact of domestic refuse disposal.
The UK Government has a vital role to play in setting the framework for
this to happen, but it is society as a whole, business and consumers which has
to be involved and committed to ensuring recycling of materials and energy from
domestic waste takes its proper place in an integrated and structural approach
to resource conservation and wastes management.
1. Barton, J.R. Recycling for Packaging; Source Separation or Centralised
Treatment.
IWM Seminar "Packaging and Waste Management and the
Consumer" 4 October 1989, London.
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THE USE OF INCENTIVES IN SOLID WASTE PLANNING;
SEATTLE AS A CASE STUDY
Diana H. Gale, Director
Seattle Solid Waste Utility
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
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Over the past three years, Seattle has redesigned its solid
waste system. The system was redesigned to be based on the
local and state hierarchy of planning goals which make waste
reduction first priority, then recycling, then use of
incineration or landfill. In redesigning its waste system,
decision makers wanted to concentrate on providing voluntary
programs and taking advantage of incentives in order to change
customer behavior. This paper will describe the types of
incentives that were used to convert the vast majority of
Seattle customers to a recycling-based solid waste collection
system.
OVERVIEW OF SEATTLE'S PROGRAMS
Seattle's Solid Waste Utility (SWU) is an enterprise fund which
means that it is run like a small business and revenues from
rates and other sources cover all expenses. Programs are not
supported by the City's general fund. Having a rate structure
has been a benefit to the Utility in designing programs because
it has been possible to give customers an economic signal to
encourage changes in behavior. The SWU is responsible for
collection and transfer of waste. Currently Seattle hauls its
waste 30 miles to a county landfill. Seattle had two landfills
which are now closed and being cleaned up as Superfund sites.
Seattle has a population of 490,000 and a collection base of
150,000 customer units. Our transfer stations accept resi-
dential and commercial self-haul waste. In addition, the
commercial haulers collect 225,000 commercial tons per year
which are taken to private transfer stations. These tonnages
have been dropping dramatically as a result of a total set of
solid waste programs. The SWU is a division of the Engineering
Department with an annual budget of $60 million for operations
and an additional $5-10 million for capital expenses depending
on what aspect of the landfill is currently under construction.
As a result of a comprehensive planning process in 1988, the
City made a decision to establish a goal of 60% for recycling by
1998. In order to achieve this overall goal, specific goals
were established fpr a series of City recycling programs.
Curbside recycling was to achieve 7.8%; the self-haul dump-and-
pick program, a reduction of 4.8%; curbside yard waste, a
reduction of 4.8%; apartment recycling, a reduction of 2.4%;
source reduction programs, a reduction of 1%; and backyard
composting a reduction of 2%. In addition, in order to achieve
the 60% recycling, the City had to hold on to the 24% private
recycling which had been going on previous to the time curbside
recycling was initiated; and, has to achieve an additional 10%
of new commercial sector recycling.
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When decision makers were reviewing options for achieving levels
of recycling reduction, a decision was made first to try volun-
tary programs. If voluntary programs did not succeed, then the
City was willing to move to mandatory programs. The decision to
try voluntary first came primarily because the City does charge
rates for garbage collection. The City's rate structure is
volume-based, which means the more garbage you produce the more
you pay. People have an option of choosing a mini-can for
weekly garbage pickup service for $10.70 per month or they can
go up to a three-can service (a 90-gallon container) that would
cost $31.75 a month. The types of incentives that the City
considered in trying to change public behavior were: giving
customers a choice, making programs convenient, and giving an
economic signal that by changing behavior customers could save
money.
The use of incentives seems to be working. Now, two years after
having started its curbside recycling program, Seattle has 80%
of its customers voluntarily signed up for recycling. 62% are
signed up for yard waste collection services. Seattle is
currently recycling 36% of its wastestream, and last year the
tonnage to the landfill was reduced by 22% from the previous
year. Programs that have already been initiated are 76% of the
way to achieving their 1998 levels.
TYPES OF INCENTIVES
A. Choice
Both the rate structure and the service structure of the
Seattle system were designed around the belief that
customers -would be happier if they could select their own
services and, therefore, set their own bill. The premise
behind the integrated garbage collection and recycling
service is that by having volume-based rates customers are
encouraged to have less garbage. Therefore, if other
services such as recycling and yard waste which divert
tonnage out of the garbage can are provided at a low or
reduced cost price, customers will select those services.
If fact, the system has worked. Seattle now has 86% of its
customers on one can or less of garbage pickup a week.
Over 80% of those customers are using recycling services
regularly; over 62% are using yard waste set-out service
regularly.
For the garbage system, customers are given a choice of the
size can they will use. The types of choices they have are
a'mini-can (20 gallon), one-can (30-gallon), two-can (60-
gallon), three-cans (90-gallon). As they increase the size
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of their can the cost of their weekly pickup increases.
Another choice customers have in customizing their garbage
service is to decide if they want curb/alley or backyard
service. Previous to 1989, the entire City of Seattle was
on backyard pickup service. In 1989, with the new rate
structure and garbage system, customers were encouraged to
move to the curb or alley, but were offered backyard
service. However, backyard service is offered at a 40%
premium. The effect of this choice is that 97% of the
customers have chosen curb/alley service.
For the yard waste program, starting in 1989, the City
required separation of yard waste out of the garbage can.
In other words, you were no longer allowed to put any of
your yard waste into your garbage can. However, there were
three different methods customers could use to divert their
yard waste. First they were offered a curbside pickup
service where yard waste would be picked up regularly at
their home at the curb. Secondly, they could take yard
waste at a reduced fee to the transfer station. Thirdly,
they could compost yard waste in the backyard. The City
offers a backyard compost program where it will deliver a
customer a free compost bin and give an hour of free
instruction in effective methods of composting. In
addition, customers still have options for managing their
yard waste such as choosing a gardener or cementing their
entire yard in order not to have yard waste. Our recent
garbage composition analyses are indicating that now less
than 1% of waste left in a garbage can is yard debris. A
year ago yard waste was up to 20% of the waste in a garbage
can.
Seattle, working with the region, has also developed a
comprehensive household hazardous waste management plan.
At the same time that household hazardous wastes are banned
from the garbage can, options are being planned for
disposing of those wastes. The region started with a
number of roundups. A roundup is a one day collection
where all household hazardous wastes are collected at
centralized sites. Now the region is moving to having
permanent sites in reasonable locations, and mobile
collection vehicles that can move from site to site.
Seattle currently has one household hazardous waste
collection site and is siting a second one. Household
hazardous waste materials are collected at the transfer
station at a subsidized fee in order to encourage people to
bring their materials to that site.
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The theory in a waste reduction/recycling based concept of
solid waste management is that for all elements of the
waste stream you provide customers with a way to manage
that waste other than place it in the garbage stream.
Consequently, the City has spawned a number of programs to
handle specific elements of the waste stream. Again, the
purpose of these programs is to give customers a choice.
We believe that if customers have a choice they will make
the right decision about how to dispose of a material.
Bulky items (such as white goods — refrigerators, stoves,
etc.) can be picked up at the curb for a small fee. They
may also be delivered to the transfer station. At the
transfer station mercury switches or capacitors are removed
from white goods so they can be recycled for metal. In
addition at the transfer stations, customers can deliver
mattresses, waste oil, wood waste, lawn mowers, cardboard,
motor oil. All of these items can be delivered free to the
transfer station where they are sold as recyclables.
B. Convenience
A second major belief in an incentive-based system is that
for customers to change behavior programs need to be easy
and convenient. We believe that if programs are designed
to be "user friendly" more people will participate. For
the curbside recycling program, this means that we provide
all customers with bins and we give frequent pickup of
those bins. Bins were all delivered to a customer's door
with a packet of information on how to use the materials.
For garbage collection all customers were provided wheeled
containers for curb service. The belief was that if it was
easy to manage a wheeled container, people would not object
to wheeling it to the curb. To encourage participation in
the compost program, customers are given a free compost bin
and a free hour of education. Yard waste programs were
designed so that people could put materials out on the curb
in plastic bags knowing that that was the preferred method
customers already have of disposing of yard waste. Seattle
is now reconsidering the use of plastic bags and looking
for possible alternatives, one of which would be providing
customers for a wheeled bin that would be used for yard
waste.
One fear of having high garbage rates was that there would
be an increase in litter and illegal dumping. In response
to this concern, the City instituted a comprehensive series
of neighborhood cleanup programs. The City has a Conserva-
tion Corps which is staffed by at-risk, older teenagers who
need to develop job skills. The Conservation Corps runs
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the neighborhood cleanup programs. All neighborhoods in
the City are scheduled for cleanup. On the appointed day,
customers can leave items on the curb where they will be
picked up and dumped free in the transfer stations. By
having free neighborhood cleanup days, customers are
encouraged to save materials for that day and not to litter
or dump.
C. Economics
1. Rates/Fees
The linchpin of Seattle's entire recycling and waste
reduction program is a volume-base rate structure.
The underlying belief of such a rate structure is that
customers will change behavior more rapidly and more
substantially if they save money from the changes.
Seattle instituted volume-based rates in 1980. At
that time the basic garbage pickup rate was low and
the difference between one, two or three can was
minor. In 1986 and 1987, Seattle customer had two
rate increases which brought rates up more than 82%.
At that point, the differential between can sizes
became greater and behavior began to shift dramatical-
ly. Now customers have a choice of a small mini-can
(20 gallons) for $10.70 per month; 1-can (30 gallons)
for $13.75 a month; 2-cans (60 gallons) at $22.75 a
month; 3-cans (90 gallons) at $31.75 a month. This
steeply inverted rate structure combined with
diversion options for citizens has led to 86% of the
City being oh one can or less of garbage pickup.
Seattle is now experimenting with the idea of charging
"garbage by the pound." The concept is that customers
would have cans that are bar-coded with their name and
billing address; the bar-coding could be read by a
laser scanner on a garbage truck and the can would be
weighed and then dumped. Billing would be done by the
weight of the garbage in the can. The idea behind
this concept is to encourage those customers who can
further reduce their waste to do so because they would
be charged only for the amount of garbage in the can.
Other aspects of the volume-based rate system are that
people are encouraged to select curb/alley collection.
Therefore, even though they are offered a service of
backyard collection, they are charged a 40% premium
for that backyard service. Customers who are handi-
capped or elderly and unable to get a container to the
curb are allowed backyard collection at curbside
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rates. Low income and elderly customers are given a
rate break. Another aspect of the volume-based system
is that waste reduction and diversion methods —
recycling and yard waste — are provided free or at a
low cost. In Seattle recycling is free and yard
waste pickup is charged at the rate of $2 per month
for nearly unlimited curbside pickup.
At the transfer station the concept of encouraging
customers to separate recyclable waste is carried out
in the fee structure. The fee for dumping clean yard
waste is reduced from the normal dumping fee, recycl-
ing is free, and charitable groups receive a special
low-cost dumping rate. Finally, the household
hazardous waste dropoff is a subsidized rate. The
City is considering moving to free dumping of hazard-
ous waste to encourage further separation of hazardous
wastes from the waste stream.
Another program in Seattle using economic incentives
to encourage behavior change is a battery deposit
program. Whenever a person purchases a new automotive
battery, a special fee is charged for disposal of that
battery. If the customer brings back an old battery,
the fee is eliminated. For the commercial sector,
economic incentives include a lower rate for the
collection of recyclables than for garbage. However,
the rate differential is not great enough at this time
to encourage the kind of behavior change desired. The
City is working with the Utilities and Transportation
Commission (UTC) to provide a more steeply inverted
rate structure for commercial collection.
2. Incentive Grant Programs
The City has initiated a number of grant programs to
gather ideas or to encourage creativity. The belief
is that creativity and involvement in problem solving
are fostered by encouraging agencies and individuals
through grant programs. The City's school recycling
program is based on a competitive grant process.
Elementary schools compete for grants of $5000 to
design waste reduction/recycling programs for their
individual schools. They are given a series of
bonuses for achieving certain levels of recycling.
Once they achieve a level of 7 pounds per student and
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faculty, they are eligible for special funds for field
trips. They also receive bonuses for PTSA involvement
in order to encourage parents and teachers to be
involved in the recycling programs.
Another experimental program started by the City is
called the Environmental Allowance Program (EAP) . The
EAP program was designed to be a research and develop-
ment program to get private sector involvement in
.solving problems. One idea that developed from this
program is to develop a latex paint recycling program.
Recyclable latex paint is separated at the household
hazardous waste shed from non-recyclable paint and
after processing and mixing is turned into an indus-
trial grade reusable paint. The EAP has experimented
with co-composting of sludge and solid waste, with
methods of cleaning glass used for recycling, with
public information on issues such as use of cloth vs
disposable diapers, and currently is involved in
setting up a commercial audit program. Some of the
programs originally designed by the EAP have then
become integrated into regular solid waste
programming.
The same concept was used to encourage City depart-
ments to begin new recycling and waste reduction
behaviors. Departments competed for grant funding for
projects to initiate recycling and waste reduction
programs. The Parks Department as a result of this
program is starting to compost garden materials; the
Seattle Center (similar to a large central urban park)
is experimenting with methods of collecting recycl-
ables on outside grounds. Departments have also
bought compactors and capital intensive pieces of
equipment necessary for recycling cardboard or other
materials.
3. Mitigation
One of the unique problems that Seattle had in design-
ing its programs was to retain existing levels of
private recycling that had been going on in the City
before the curbside programs began. Retaining those
high levels of private recycling is highly cost effec-
tive for the City because people entered into those
recycling behaviors at no cost to the City. In an
effort to keep private recyclers in business, the City
tried to work on effective ways to maintain existing
recycling through mitigation programs. One initiative
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is to publicize small recyclers1 activities and to
provide them with grants to do market research. A
second type of mitigation is to find new program areas
that can be saved for smaller recyclers. The City
designed an apartment recycling program geared to be
provided by existing recyclers. However, the diver-
sion credit price that was offered in the program was
too low and the private recyclers chose not to partic-
ipate. Mitigation has not been entirely successful in
Seattle and a number of private recyclers have gone
out of business. However, Seattle is still working on
ways to maintain and support existing recyclers in
business.
CONCLUSIONS
The use of incentives has been an important element underlying
Seattle's waste reduction/recycling programs. Clearly, giving
people economic incentives to change their behavior is the most
effective way of getting change. The fact that Seattle charges
a rate for garbage has turned out to be an unusual benefit in
the design of its solid waste programs. Although the most
influential method of changing behavior has been providing
economic incentives, giving customers choice and making programs
convenient have also been important additives to a volume-based
structure. Peer pressure and environmental ethic are the
"frosting on the cake" that encourage people to make good
environmental decisions, but by themselves will not affect the
vast majority of the public. Finally, the fact that programs
are voluntary and people are given the choice to select the
services they want to meet their own solid waste disposal needs
(and, thereby, to customize their bill) seems to have contrib-
uted to customer satisfaction with programs. By using
incentives Seattle has been able to rely on voluntary programs
and is well on its way to achieving its 60% goal for waste
reduction and recycling of its waste stream.
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VARIABLE RATES IN SOLID WASTE: APPROACHES FOR
PROVIDING INCENTIVES FOR RECYCLING AND WASTE REDUCTION AND
A MORE EFFICIENT SOLID WASTE SYSTEM
Lisa A. Skumatz, Ph.D.
Synergic Resources Corporation
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
731
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VARIABLE RATES IN SOLID WASTE: APPROACHES FOR
PROVIDING INCENTIVES FOR RECYCLING AND WASTE REDUCTION AND
A MORE EFFICIENT SOLID WASTE SYSTEM
Lisa A. Skumatz, Ph.D.
Synergic Resources Corporation1
THE WASTE DISPOSAL CRISIS
Landfill space is becoming a major nationwide crisis. Almost 40% of
respondents to a recent survey conducted by the American Public Works
Association indicated that their landfill space would run out within 5 years.2 In
addition, this survey indicated that 74% were currently doing nothing to reduce
solid waste volume. There is a nationwide disposal crisis, and it is affecting
jurisdictions that are large and small, urban and rural, all across the nation.
Locally, the crisis can manifest itself in rapidly increasing disposal tipping fees,
in the need to haul waste hundreds of miles for disposal, in mandatory
recycling programs, in struggles to comply with changing landfill standards, in
public opposition to the siting of needed new disposal facilities, or in barges
filled with waste with no place to dock.
What can jurisdictions do to solve this crisis? Traditional options include:
o building a new landfill,
o building an incinerator in hopes of extending the life of existing landfills.
o more recently, jurisdictions have begun imposing mandatory recycling
programs.
Many jurisdictions are facing very significant economic investments in either
closing landfills, building new ones, or building incinerators. And the out-of-
1 This work was partially funded by grants from the Environmental Protection
Agency. The work was conducted by the author while employed at the Seattle
Solid Waste Utility.
2 Solid Waste Collection & Disposal: 1987. by American Public Works Association
(APWA), 1987.
732
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pocket costs of these huge investments don't include the significant problems of
siting, changing regulations, public pressure, and long lead times.
IS THERE ANOTHER SOLUTION?
The problem would be reduced if residents could be induced to reduce waste,
increase recycling, and do a number of other "good things". However, there are
many citizens who simply will not react to the crisis unless there is an
economic, or "pocketbook", reason to do so.
In most parts of the country, garbage is removed once or twice a week with
the revenues coming from one of two places:
o from a portion of the property tax, or
o from fixed bills for unlimited pickup (bills that do not vary with respect
to the amount of garbage taken away.)
Neither of these methods gives residents any incentive to reduce their waste.
In fact, with the property tax method, residents never even see a bill, and
generally have no idea how much it costs to remove their garbage every week.
Areas with these methods of payment have often had to resort to mandatory
recycling programs in order to try to reduce their amount of garbage.
Residents in several jurisdictions around the country have come to
recognize that you can achieve remarkable successes in recycling
and waste reduction without any mandatory features through one
simple measure: volume-based garbage rates.
WHAT ARE VOLUME-BASED RATES?
In volume-based rates, the level of payment varies with a measure of the
volume of waste disposed. Customers who use more service pay a higher rate,
and those who use less pay less. There are several possible volume-based rate
designs which provide the same principles ~ customers putting out more waste
pay higher fees. Seattle uses a subscribed variable can system. Several other
jurisdictions use a pre-paid bag system. Briefly, a variable can system involves
having customers select subscription levels based on the number of cans of
garbage they need to dispose of each week. The jurisdiction usually offers
subscription levels in standard 30-gallon increments (one can, two cans, etc.).
Seattle and Olympia, Washington also offer smaller service levels that hold 19
and 10 gallons respectively as a reward for small waste generators. Higher
service levels are charged higher rates.
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Jurisdictions that employ a bag system charge a fee for each "official" bag that
includes the cost of disposal.3 Under a bag or tag system customers purchase
special garbage bags (or tags) from the jurisdiction or from outlets at a price
that includes the cost of disposal. The more bags of waste they put out, the
more they must pay.
The key under both these systems is that the amount that customers pay
increases significantly as they use higher levels of service. Customers are not
limited in what they may dispose, but they are required to pay for what they
use.
VOLUME-BASED RATES ARE AN EFFECTIVE RECYCLING It
Average Cans Subscribed
1981-1989
Volume-based rates have
proven to be an
extremely effective
recycling incentive.
Since Seattle's
introduction of variable
can rates in 1981,
Seattle's customers,
eager to reduce their bi-
monthly garbage bills,
have reduced the
average number of cans
subscribed from 3.5
down to just over 1
can. And the recycling
percentage (in terms of
actual tons of waste
diverted, not just
participation rates) was over 24% before the introduction of any City-sponsored
recycling programs.
Volume-based rates have also contributed to the quick success of Seattle's city-
operated recycling programs, which provide customers a convenient opportunity
to reduce subscription levels by recycling materials they might otherwise have
1986
WMU Utility
Figure 1
3 The charge usually includes at least the cost of disposal. Some jurisdictions also
include a share of the system's fixed costs.
734
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thrown away. The City has achieved an amazing 75% sign-up rate in its
curb/alley recycling program. More important than sign-up statistics, however,
is the amount of waste diverted by the program. The program currently
collects about 3,500
tons per month, or an
average of 63 pounds
per participating
household. Over 60%
of Seattle's customers
subscribe to the City's
new yardwaste
collection and
composting program.
This year alone, the
curbside program is
expected to divert about
27,000 tons of
residential waste to a
composting facility.
SEATTLE SOLID WASTE TONNAGE, 1987-1989
Monthly Residential Tonnage
TONS {Thousands)
JAN FE8 MAR APR MAY JUN JUL AUQ SEP OCT NOV DEC
MONTH
• 1987 Tons
•1988 Tons
1989 Tons
Figure 2
In addition, based on an
analysis of numerous factors, the Utility has determined that the introduction of
variable can rates has helped slow the growth of disposed tonnage. There have
been two factors assisting this result. First, the level of Seattle's rates increased
to a point at which customers took notice. In addition, the rate structure
provides clear rewards for reducing waste. The steep rate structure adopted at
the beginning of 1989 has been particularly effective in achieving this goal.
Customers can achieve real savings on their garbage bills by participating in
this program, and Seattle's customers understand and take advantage of this.
Incentive-based rate design goes hand-in-hand with recycling and waste-
reduction programs, and is a critical part of integrated solid waste management.
In Seattle, the combination of rate incentives and additional recycling and
diversion programs has allowed Seattle to decrease the amount of waste it
brings to the landfill by 24% compared with 1988 levels (see Figure 2).
Similar and dramatic reductions in landfilled tonnage have also been noted at
jurisdictions that have instituted bag systems. Perkasie, Pennsylvania for
instance, noted a 35-45% decline in tonnage brought to its transfer stations
after the introduction of their bag system and recycling program.
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WHAT OTHER BENEFITS DO VOLUME-BASED RATES OFFER?
Volume based rates can benefit a community in a number of
ways:
o Customers receive an incentive to reduce disposal.
o The rates are fair.
o Incentives support recycling programs.
o Mandatory recycling can be delayed or avoided altogether.
o Fees make customers aware of the environmental
consequences of their actions.
This system gives customers a very clear reward for reducing the amount of
waste that they dispose of: they pay a distinctly lower bill. An additional
benefit of the system is that it does not favor any particular method of reducing
waste. Other benefits of volume-based rates include:
Volume based rates are fair -- customers who dispose of similar amounts
of waste pay similar amounts of money. Those who dispose of less, pay
less. Customers get control over the bill they pay. In addition, the rates
reward all methods of reducing waste including waste reduction and
recycling.
Implementation of any City-sponsored recycling programs will be much
more successful with these rate incentives in place. The combination of
variable rates and convenient recycling programs makes for a much more
integrated garbage system, and gives customers good alternatives and
choices.
Customers get a chance to show what they can do through voluntary
rate-induced waste reduction. Your programs need not be mandatory
and therefore your enforcement burden can be reduced, and you may
still invoke mandatory programs later if you don't achieve the goals you
need.
This method gives customers a better idea of the actual cost of disposing
of waste and provides a better relationship between customer behavior
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and rates. Masking the cost of garbage service all these years has made
the cost associated with new landfills and incinerators particularly hard
to justify to customers in some areas. It is difficult to condemn
customers for making unwanted choices in their waste disposal behavior
if they are not given the information (generally costs of disposal) to
make intelligent choices. Customer education is key to getting customers
to work with the system.
o Pricing garbage services in this manner puts solid waste on an equal
footing with the way water and electricity services are priced.
Customers pay based on the amount of service they use, and have
economic reasons to conserve.
o Using volume-based rates to reduce waste is quicker to implement than
building new capital facilities to handle additional waste. The rates
provide an environmentally sound alternative and can be implemented in
a variety of situations. In addition, they integrate well with programs
and can help lead to lower long-run system costs.
WHAT DO WE GAIN?
From a city management perspective, volume based garbage
rates can gain the City:
o Time to site new disposal facilities.
o More options in terms of recycling vs. disposal investment
o Support of low volume dumpers and recycling groups
Volume-based (specifically, variable-can) rates, and the additional awareness of
the solid waste issue that they have brought, have allowed Seattle to seriously
propose a set of non-mandatory programs that will bring it to an aggressive
60% recycling goal by the year 1996. Rate design is an integral part of this
program. Seattle considers its volume-based rates its most effective recycling
program. It can be yours too!
In addition, implementing volume-based rates is quicker than building new
capital facilities. Even if capital facilities are also needed, volume-based rates
may help buy extra time, and accustom customers to the idea of paying on the
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basis of service provided. Implementing variable can rates (and recycling
programs) can help win support for additional disposal facilities because
customers may recognize that the jurisdiction has made a good faith effort to
avoid siting additional disposal capacity and is taking an integrated planning
approach to the issue.
Volume-based rates can be implemented to reward voluntary reduction of waste
by customers. The jurisdiction can still hold out mandatory measures as a
threat if customers do not achieve the needed goals voluntarily. However,
allowing customer choice and emphasizing voluntary programs often produce
less ill-will than proceeding without giving customers a chance to "show what
they can do".
Volume-based rates can produce a closer relationship between the costs and
revenues for a solid waste jurisdiction. Rather than a rate system that
generates revenues that do not vary with the amount of waste disposed,
charging volume-based rates will tend to generate higher revenues for
customers that cost more to serve.
Finally, volume-based rates are fair, provide excellent recycling incentives, are
environmentally sound, and can help slow or even reverse growth in tonnage
disposed.
WHO CAN IT WORK FOR?
Because the economic concepts underlying volume-based rates are universal, a
volume-based rate structure can help a wide variety of jurisdictions, including
those:
o with collection performed by contract, franchise, municipal, or private
arrangements,
o that cover large, medium, or small numbers of customers, and
o in any part of the country.
Whether variable can rates make sense depends on an assessment of specific
circumstances, including those related to cost, timing, and political factors.
ICTS WHETHER IT WILL WORK IN OUR
Although costs are obviously a key factor, there are a number of other
situations that help make adoption of a volume-based rate system simpler and
738
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more politically appealing:
o Hauling contracts, franchises, rates, or billing systems are up for a
change.
o The jurisdiction faces any of a wide array of landfill or disposal
problems, including a shortage of landfill space, high tipping fees,
changing landfill regulations, or public opposition or other difficulty
siting new landfill or disposal options.
o Jurisdictions in which the community wants to create recycling incentives
to increase participation in an established or planned recycling program
or satisfy local recycling advocates.
o The existing system is perceived as unfair and encourages abuse.
o The jurisdiction is running out of tax authority and can use the
establishment of separate rates to free up tax revenues.
o Medium to larger jurisdictions may have some advantages in being able
to spread implementation and fixed costs over more customers.
It may also be helpful if the solid waste jurisdiction is legally established as an
entity that must cover its costs via fees, e.g. a utility or enterprise fund.
Although the factors mentioned above can make adoption of volume based
rates simpler, none are essential. A volume based rate system may be
appropriate anywhere.
WILL IT PAY/CAN WE AFFORD IT?
The question is whether you can afford not to do it!
Continuing to landfill is becoming more and more expensive, especially if the
true costs of landfilling are considered (that means including costs of closing,
difficulties of replacement of the landfill, etc.). Extending the life of existing
landfills pushes the closure (and siting) costs out to later years, and means real
dollar savings now that can be invested in recycling programs, etc. with actual
benefits to the solid waste jurisdiction and its customers.
The final judgment of whether the new system will pay depends on a
comparison of the costs vs. the savings of the new system.
739
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The types of costs that will be incurred with the
implementation of volume based rates may include:
o Contractual changes
o Public information, outreach, and PR
o Billing system changes
o Cost of designing the rate system
o Staffing increases, especially in customer service and field
inspection crews.
The operation of a solid waste system funded with volume based rates is almost
certain to be more expensive than a flat fee or tax-funded system. Thorough
planning involves examining potential cost increases and compare them with
potential savings.
Savings resulting from the change may include:
o Savings on current disposal costs
o Savings from extension of the life of existing disposal sites
o Savings in crews and overtime at transfer, hauling, and
disposal facilities
o Improved utilization (and improved economies of scale)
of recycling programs.
The "benefits" described above are often referred to as "avoided cost". Avoided
cost refers to money that does not have to be paid as a result of some activity.
Considering avoided cost allows a complete comparison of alternative
investments, and allows planners to design their least-cost system.
Using avoided cost analysis in 1988, Seattle found that the status quo system
(landfilling at a local site) was more expensive than investing in very aggressive
740
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and expensive recycling programs, and long-hauling the remaining waste to an
alternate site.
Local factors affecting cost-effectiveness may include:
o Costs and lifetimes of specific landfill or disposal alternatives
o Access to and strength of regional recycling markets
o How rural vs. urban the collection area is - distance between
stops, distance to landfill, distance to recycling markets
o The portion of collection cost that varies with volume of waste
collected.
ISNT IT A LOT OF TROUBLE TO IMPLEMENT?
A volume-based system is more complicated than some alternative rate systems.
However, the steps involved in implementation are manageable. They include:
o Determining whether state law empowers your agency to bill for solid
waste on the basis of volume.
o Establishing an ordinance that makes solid waste service, or at least
charges, mandatory
o Establishing an ordinance that bans (and penalizes) illegal dumping and
burning of waste
o Establishing the solid waste entity as an enterprise fund (not essential,
but can be helpful)
o Assuring that there are convenient recycling alternatives (public or
private)
o Creating a sensible system of rates on the basis of system costs and
desired changes in disposal behavior.
o Extensive public education/information efforts
o Preparation for some changes within the solid waste agency, including
increased staff in some areas (particularly billing and customer service),
changed responsibilities for some employees, and a possible refocusing of
the services that the utility offers.
Of course, establishing local political support is a key ingredient in the process.
Some obstacles to successful implementation are peculiar to individual volume
based systems. For example, variable can rates can require a complex billing
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system, and pre-paid bags or tags may require a retail distribution system.
WHAT LEGAL POWERS DO I NEED TO WORRY ABOUT?
New recycling and landfill legislation has helped make a volume-based rate
system an appealing option in many states. Existing law can affect the level of
difficulty associated with a move to a volume-based rate system.
The legal powers necessary for a solid waste agency to charge for refuse
collection on the basis of volume generally either already exist or can be
created through a local ordinance, if the local political climate permits. Some
states may limit local agencies' power. Unfortunately, therefore, legal questions
must be answered on a state-by-state basis.
Several legal situations can affect the ease with which a volume-based billing
system can be implemented. Ideally, a jurisdiction considering such a change
would have the following powers:
Legal Powers Needed:
o Power to bill or set/approve rates
o Flexibility to perform non-traditional services
o Power to prevent illegal dumping.
o Power to bill (municipal or contract system) or to set (or approve) rates
for refuse franchisee. This power must include some means of enforcing
payment of bills. The power to make refuse service mandatory can also
be helpful.
o Flexibility to perform services other than traditional collection and
disposal of refuse. Laws that strictly limit ways in which refuse system
funds must be spent can complicate recycling efforts. Limited recycling
options can affect the desirability of a volume-based rate system.
o Power to prevent illegal dumping. Although the solid waste agency will
probably not enforce illegal dumping laws itself, there must be a strong
penalty for disposing of waste outside the system.
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The powers listed above are generally available to jurisdictions that currently
provide refuse service. Flow control may also be needed for a smoother
system.
WONT IT CAUSE A LOT OF PROBLEMS?
Changing from fixed fees for unlimited pickup, or from a system where fees are
collected via taxes may not be a simple, problem-free process. However, most
of the potential problems are manageable, especially if you expect them.
Communities considering implementing volume based rates
should be prepared to address several of the following
problems:
o Confusion with the new system
o Resistance from customers who are not used to paying
bills or who are unwilling to change behavior
o Illegal dumping or burning of waste
o Enforcement of the system
o Complaints by the poor
o Contractual or legal limitations on the flexibility of the
solid waste agency
o Change in the responsibilities of your agency and staff
oNeed for increased staff (some temporary increases for
analytical tasks, and longer term increases needed in
customer service, etc.)
CAN THESE PROBLEMS BE HANDLED?
The answer is that the problems can be significantly reduced -- if you anticipate
them and prepare for them.
Customer Confusion and Resistance: Working with the press and preparing
mailers can help customers understand the reasons for the change, can help
with resistance to behavioral changes, and can help explain the new system.
Initial stories about local problems related to solid waste, and about solutions
that have worked in other jurisdictions, can help increase understanding of
solid waste issues. Repeated mailers, television spots and bus cards can be
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helpful in reinforcing the new behavior.
Illegal Dumping and Burning: Some increase in illegal dumping and burning
can sometimes be associated with variable can rates. Making sure that there
are convenient opportunities for customers to recycle waste and imposing
regulations that provide penalties for illegal dumping are helpful. Requiring a
minimum level of service and minimum fee for all households can help reduce
the problem. In addition, getting a public attitude change that says illegal
dumping isn't socially acceptable (like the recent changes in the social
perception of drunk driving) can go a very long way in mitigating problems of
illegal dumping and burning.
While many areas have had trouble with illegal dumping in response to sharp
increases in refuse rates, Seattle does not appear to have experienced a
significant problem with illegal dumping or burning of waste. Other large cities
have had problems. However, it is difficult to get a very accurate or
quantitative handle on the problem. Seattle does not have a comprehensive
program to pick up illegally-dumped waste. Rather, some incomplete
information is provided by street cleaning crews, and are subject to
complicating effects from seasonal labor availability and other problems. Also
complicating the problem is the fact that waste can easily be dumped across
jurisdictional lines, and burning can be difficult to detect or trace to its source.
There are several factors that may contribute to Seattle's relatively small
problem in this area: 1) there are few vacant lots in the City, 2) the
Northwest has a strong environmental ethic, 3) the areas has many private
recyclers, city programs, and other legitimate ways to reduce the amount of
waste that needs to be disposed, and 4) volume-based rates are not new to the
area, so customers have had time to modify their behavior.
Enforcement: Enforcement may or may not be needed. For many years,
Seattle's Solid Waste Utility relied on an honor system for enforcement of
service levels. Although it is clear that some customers put out more waste
than they were paying for, on-site inspections indicated that the levels of abuse
were not high, and were in fact, offsetting.
Seattle's new collection system is much simpler to enforce. The contractors
provided 'official' semi-automated toters sized to the subscription level paid for.
This system greatly simplified enforcement, because any waste that is not in the
official toter is not paid for and is generally not collected, unless it has a pre-
paid sticker on it. A decision on enforcement in a particular jurisdiction may
be able to be deferred until after the system is in place for a while. However,
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provisions for enforcement should be included in any contracts, etc.
Low Income Assistance: Because an economic incentive to reduce waste
disposal below a minimum level can lead to illegal dumping, volume-based
rates require the introduction of mandatory charges. These separate and
discrete charges can be a burden to low income customers. However,
establishing special rates for low income citizens, or building "lifeline"
components into the rates will mitigate the impact of mandatory rates on
customers with fixed or low incomes. Some jurisdictions offer carry-out service
for curbside rates.
Staffing Considerations: In-house problems can be reduced if management
prepares staff for changes in emphasis of the job, for instance realignment of
staff toward recycling efforts and away from traditional collection and disposal.
Management also need to prepare staff for growth in some areas in particular,
some of which will involve permanent increases and some more temporary.
Management may be able to cope with some of the burden in areas with
temporary workload through the use of temporary labor, or with loans of
municipal employees or staff from other sister agencies, or with consultants.
Although these steps take planning, they can set the stage for a very effective
solid waste system.
AREN'T THERE OTHER RATE OPTIONS OUT THERE THAT ARE JUST AS
GOOD?
No. Volume-based4 rates are equitable and provide better incentives than rate
designs that do not vary the charge with some measure of the amount of
service provided. They provide customers with choices, integrate well with new
recycling and yardwaste programs, encourage participation in recycling
programs without making them mandatory, and can lead to an extension of the
life of existing landfill space.
As a comparison, many jurisdictions are considering offering recycling credits,
which reduce garbage bills for people who participate in recycling. While
credits may be better than nothing, they are not the best alternative because
the amount of the credit is fixed, and does not give customers an incentive to
4 Another experimental alternative, a weight-based rate system, is discussed later in
this paper.
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recycle more. In addition, credits for participating in "official" recycling
programs do not encourage careful buying in the first place (many jurisdictions'
first priority for waste reduction), backyard composting, re-use, or recycling
through private firms.
WHAT ADDITIONAL CONSIDERATIONS ARE INVOLVED IN RATE DESIGN?
System Design Decisions
o Choice of Bag/Tag vs. o Charges for Recycling or
Variable Can System Diversion Programs
o Subscription vs. Usage o Rates for Multi-family
o Steepness of Rates Buildings
o Payments for "Extras" o Rates for Compacted Waste
o Curbside vs. Backyard o Alternatives for Low
Differentials Income Households
Choice of Variable Can vs. Bag/Sticker Systems: The selection of the type of
volume-based rate system will depend on the evaluation of the tradeoffs of
several factors in the context of the jurisdiction's situation, including:
o Equity
o Simplicity, implementation considerations, and cost, and
o Revenue Stability.
There are pros and cons for each of these systems, and jurisdictions need to
weigh their particular needs.
A 'variable can'-based system may be a good option for areas using semi-
automated toters, areas with problems of animals or rapid spoilage, or places
already using a can system where customers may already own their own cans.
Variable can rates also show customers the full cost of disposal in one bill.
Can systems may provide more stable revenues than bag systems, and may be
easier to forecast. Especially important is the fact that variable can rates also
allow a great deal of flexibility in the pricing increments between can
subscription levels. The jurisdiction can implement rates that provide very
aggressive recycling/waste reduction incentives with this system.
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However, a variable can system has fairly high implementation costs,
particularly because of the complexity of the billing system needs. A fairly
complex computer system is needed that will keep track of each customer's
selected subscription level, and will calculate bills accordingly. In addition,
customer service costs may be higher, and some confusion on the part of
customers is fairly likely because subscription levels will need to be selected.
Bags or pre-paid stickers generally charge for smaller increments of waste than
a variable can system, letting customers pay more precisely for the amount of
service they use. This provides a better link between customer behavior and
the bill they pay, and allows a better waste reduction/recycling incentive. In
addition, the purchase of the bags may provide a more immediate price signal
to customers. The billing system is much simpler, and customer questions and
confusion can be lower than with a variable can system. Enforcement may also
be simpler. Although bags are generally easier for collection staff to dump,
allowing the bags or stickered waste to be placed inside cans may help alleviate
animal problems where that is a difficulty.
Selection Between Variable Can and Bag/Tag System
Variable Can System Bag/Tag System
o Full cost on bill o More usage-based
o Relatively stable revenues o Immediate price signal
o Flexibility in pricing o Limited flexibility in
incremental 'can* levels pricing incremental bags
o Relatively high billing, o Fairly easy to implement
customer service, and enforce- and enforce
ment implementation costs
A bag or tag system will require the jurisdiction to set up a distribution system
for pre-paid garbage indicators, but allows the jurisdiction to avoid the cost of
a billing system.5 The jurisdiction must also establish and communicate (and
presumably enforce) clear limits on the size of items that may have stickers
5 Seattle employs a combined approach - a "can" based system, with special stickers
for occasional "extras". These stickers, or 'Trash Tags" may be purchased from the
Utility or at retail outlets like 7-Eleven and grocery stores.
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attached. However, a bag system limits the agency to equal price differentials
no matter how many bags are put out by a household. This restricts the
jurisdiction from charging increasingly higher rates for additional waste.6
If the jurisdiction attempts to charge for all the costs of disposal through the
price of the bag, it runs the risk of not recovering the system's fixed costs. It
may be more prudent to charge for the fixed cost of the collection/disposal
system through a separate charge to customers, and keep the cost of the bags
closer to the Variable' cost of the system (generally disposal). In this latter
case, the "fixed" portion of the system costs would be recovered through a
"customer charge" on a regular periodic bill, or through a tax mechanism7.
Then bags or stickers could be purchased for an additional fee that would
reflect the "variable cost" of the system, and would show customers a savings if
they dispose of less waste (use fewer bags or stickers). Charging separately for
the fixed portion of the collection/disposal system assures that the fixed costs
of the system will be recovered, and the system will remain solvent.
Attempting to charge for all costs on the price of bags can lead to revenue
instability and potential financial insolvency.
Choice of Subscription vs. Usage-based system: The best incentives are
provided by systems that charge customers based closely on the actual amount
of waste disposed. In this way, the customer's behavior is more directly
associated with the amount paid. However, such a system requires either
recording the number of items at each pick-up, or requires the use of pre-paid
bag or stickers.
Pre-paid bag or sticker systems are a good option, especially in that they may
offer charges based on smaller increments of waste and make it easier for
customers to vary the amount of waste they put out. However, the system
must allow for the recovery of fixed costs in some manner, perhaps through an
additional "customer charge".
Subscription systems may provide an incentive to completely fill up the cans or
bags paid for, and may decrease the recycling incentive. However, subscription
systems can also work to remind customers to reduce to that subscription level
6 This can be mitigated to some degree if the household is issued a fixed number
of bags per year at a certain rate, but then additional bags are available at a
higher rate.
7 The jurisdiction could charge this customer charge through its existing revenue
mechanism.
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on weeks when waste might be higher. Subscription systems are often easier
to implement than systems that require the recording of items for each pick-up,
and provide revenue stability. Providing the option for pre-paid stickers or bags
in conjunction with subscription systems can improve the flexibility of the
system for customers with occasional higher garbage levels, and may reduce the
risk of illegal dumping.
Steepness of the Rate Structure: The steeper the extra charge for additional
waste, the greater the incentive to recycle. Jurisdictions may wish to steer
clear of excessively steep rates for two reasons, however:
1. An increased incentive to dump illegally.
2. Volatility of revenues.
Fixed costs of the system are incurred no matter what level of waste is
disposed. Because the revenues for higher levels of waste are generally less
certain (and indeed, through recycling, etc. you are trying to reduce these
higher levels of waste), many of these fixed costs must be recovered through
the customer charge or integrated into the "first-can" rate to assure the agency's
financial solvency. The more of these costs that are put on the first service
level, the less steep will be the rates.
Selecting the steepness of the rates requires balancing:
Increased recycling/waste reduction incentives
vs.
Increased incentives for illegal dumping
and revenue uncertainty
In addition, pure cost-of-service pricing would not necessarily justify steeply
increasing rates. This can be a difficult trade-off. This situation can arise for
several reasons. One of the largest costs of providing solid waste service is
getting the trucks and labor to the house, a cost that will not vary much with
how much waste is put out for collection. In addition, many landfills are not
priced at a level that reflects the full cost of providing service.8 This will tend
8 Many jurisdictions do not charge appropriately for all the costs associated with
adding tonnage to a landfill. Costs that are often undervalued or omitted include
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to reduce the steepness of the rate structure because a large component of the
variable cost (the landfill fee) is underpriced compared to the long-term fully-
inclusive price of disposal.
Seattle instituted rates that are higher than cost-of-service for higher
subscription levels, and this approach was favored by the Utility, policy-makers,
and citizen groups. The amount of excess funds that were projected to be
collected from customers subscribing to higher can levels were used to reduce
the rates for lower can levels. This approach allowed Seattle to enhance its
waste reduction and recycling incentive in two ways: first, by implementing an
enhanced 'penalty* for large amounts of waste; and second, by increasing the
'reward' for disposing of small waste volumes.9
Payments for "extras": "Extras" are cans or bags of waste that customers dispose
of in excess of their subscription levels. Under a subscription or variable can
approach, a system of payment for extras must be established to allow honest
customers to dispose of occasional extra garbage without illegal dumping.
Care must be taken to assure than the price of one "extra" is greater than one-
fourth the cost of an additional permanent monthly service level (with weekly
service, or four pickups in the month). This becomes more complicated if the
dollar differentials between service levels are not constant across service levels,
and if the differentials vary for curbside vs. backyard service.
Differentials for Curbside vs. Backyard Service: Generally, backyard or carry-
out service is more expensive to provide than curbside or alley service.
Allowing customers to select — and pay for — the service arrangement of their
choice can save your system money and provide more service options to
customers. The savings may help pay for the switch to volume-based rates.
Jurisdictions currently show a wide range of differentials for these service
differences. Some charge only cost-of-service differentials (perhaps 10%).
Others charge as much as four times as much for backyard service. Seattle
charges 40% more for backyard service, and found that over 95% of customers
selected curb/alley service. Allowing customers to choose the service type gives
ultimate landfill closure costs and the cost of siting a replacement landfill.
9 However, care must be taken in implementing this 'enhancement'. Recall that the
revenues for higher subscription levels are less certain, while subscriptions at lower
can levels are very certain. As the subsidy increases, the agency increases the
chances it will not recover the fixed revenues needed to run the system.
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them control over the size of their bills and continues the principle of providing
a direct relationship between customer behavior and the size of bill.
Charges for Recycling or Diversion Programs: One controversial area is
whether jurisdictions should charge separately for recycling or diversion
programs. If these services are provided, but not separately charged, the costs
will be included in the basic garbage rates. Not charging may enhance
incentives to sign up for these programs.
However, there are strong arguments that this may not be an equitable system.
Customers who do not use the program are charged. Although the jurisdiction
may seek to penalize customers who do not use the City's programs and do not
recycle or work to reduce their garbage, it is less clear that they would want to
extend those penalties to customers who reduce their garbage through private
recyclers or who reduce waste through careful purchasing or re-use. If the
charge for recycling programs is included in the basic customer charge, then the
likelihood of recovering the program costs is high, but these inequities are
exacerbated. If the charges are put on higher subscription levels, the- penalties
are directed more accurately at customers who dispose of a great deal of waste,
but the program costs are less likely to be recovered, affecting financial
stability.
Indeed, as the solid
waste jurisdiction is
more successful in
diverting waste from the
landfill disposal stream
to recycling and
diversion programs, it
reduces the revenue
base (number of cans or
bags) over which to
spread recycling costs,
so the extra cost per
unit must increase. The
result could be a system
in which, as people
recycle more, they pay
higher and higher garbage
RELATIONSHIP BETWEEN DISPOSAL
PRIORITIES AND RATE INCENTIVES
Increasing
Priority
Waste Reduction. Careful
^ ' Buying, and Composting
Private Recycling
City-sponsored Recycling
and Waste Diversion Program
Garbage to Landfill or
Incinerators
NO CHARGE
HIGHEST RATE
Increasing
Rate*
Well-designed Rates can Induce Customer Behavior
That Reflects Waste Disposal Priorities
fees.
To avoid finding itself in this situation, the jurisdiction should consider charging
a separate (but relatively lower) fee for City-sponsored recycling, yardwaste
collection/composting, and diversion programs. The fee may not recover all the
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costs of the programs, but should provide an incentive for taking care of the
waste through careful purchasing (so that the waste is never produced in the
first place), private recycling programs, or other ways to remove the waste
from the city's waste and recycling system.10 As the job of the solid waste
jurisdiction changes from one of solely disposing of waste to an integrated
system of waste disposal as well as waste diversion and recycling, it may be
appropriate to charge customers some portions of the cost of these additional
services, since a fee-for-service approach provides greater long-term financial
stability and gives customers greater control over their bills. However, that
doesn't mean it is inappropriate to provide some level of subsidy to these
programs from garbage revenues. This approach reinforces the waste disposal
priorities that have been adopted in most jurisdictions.
Seattle provides a curbside recycling program for no additional charge,11 but
charges a $2.00 monthly subscription fee for the City's weekly curbside
yardwaste collection and composting program. This charge is considerably
below the $9.00 charged for an additional subscription level.
Rates for Multi-family Buildings: Rate options for multi-family buildings can be
complex for any utility, but may be especially so for solid waste service. The
problems include:
o The tenant, or garbage-producer, is often not the bill-payer, so the rate
incentives are diluted and indirect.
o Garbage is usually disposed of in a joint area, so tenants may not feel
responsible if they over-dispose of waste because of the problem of
determining which tenant is responsible.
o Rate equity can be difficult to maintain if two different systems (cans or
bags; vs. dumpsters) are available.
o Maintaining equity between multi-family and single-family rates as well
as between large and small multi-family buildings can be complex.
o The fact that some costs may be properly allocated on a building basis
(e.g. the stopping of a garbage truck), some on a household basis (e.g.
landfill closure), and some on a volume-basis (e.g. disposal) makes
designing rates for multi-family applications much more complex than for
single-family buildings.
This approach may also mitigate the amount of harm to any existing private
recycling enterprises, and the potential for political fallout.
11 The cost of the recycling programs and planning are covered through the garbage
fees.
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o Offering a high degree of choice in subscription levels may complicate
both billing and enforcement.
It would be possible to bill multi-family buildings on a fixed-fee basis (either
per-building, or perhaps more fairly, per-household). However, that approach
would eliminate any possibility of providing signals to either the property
owner or the tenants that reducing waste is a benefit.
Although it may seem difficult, there are at least two possible volume-based
approaches that may be practical in multi-family buildings:
1) A bag or tag system, with a per-household customer charge,12 or
2) A variable can subscription approach.
Either system could be set up so that the owner is generally charged based on
the volume generated per complex. However, the former system has the
possibility of passing some of the direct incentives to the tenants. A per-
household charge could be assessed through a bill or through the property
taxes. Then all the waste that is in official pre-paid bags or that is tagged with
pre-paid stickers would be picked up. Presumably tenants could be made
responsible for paying for the bags. This system would tend to get some of the
waste reduction incentives inherent in the rates to the waste producers.
However, realistically, some buildings may need enforcement efforts to try to
reduce the amount of waste that is disposed in unofficial bags or waste that is
not tagged. This may be a problem, and the relevant ordinances may need to
make the landlord ultimately responsible for paying for this waste.
A variable can system is another alternative. Seattle's system of multi-family
variable can rates is complex and imperfect. The City's billing system maintains
records of the number of apartment units in each multi-family building and
requires the building owner to select a subscription level.13 The multi-family
rates are charged with a structure that is identical to the single family rates for
12 The customer charge would probably be billed to the building owner.
13 The system gives owners two options. They may either sign up for a number of
cans that is equal to or larger than the number of units in the building (a five-
plex may sign up for five, six, seven, etc. cans). Alternatively, the entire building
may sign up for the mini-can service (that same five-plex would pay for and
receive five mini-cans of service per week).
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each apartment unit.14,15 The system is veiy complex and inflexible. However,
the biggest weakness of this system is the fact that if one tenant is a strong
recycler, he/she cannot generally reap the benefits of that behavior - the
system is unable to get the recycling incentive directly to the tenant.
Some non-rate options may need to be employed. Passing an "opportunity to
recycle" ordinance requiring each complex to provide a convenient recycling
opportunity may assist in increasing recycling by these customers.
• Rates for Compacted Cans or Dumpsters: There may be a case for charging
differential rates depending on whether waste is compacted or not. If landfill
charges are weight-based, this may be especially appropriate.16 However, in
many cases, compacted waste may not incur extra disposal charges, and
therefore may be priced the same as uncompacted waste.
In cases where a differential is appropriate, practical considerations may make
it impossible17 to charge additional amounts for compacted waste in cans, but
may allow additional charges for compacted dumpsters. This is the case in
Seattle. The Utility pays per-ton fees for landfill disposal and the Utility
charges an additional fee for compacted dumpsters, which brings dumpster rates
closer to cost of service. Seattle deals with compacted cans through a weight
limit, which allows the City to deny pick-up to gross weight-limit violators.
Alternatives for Low Income Households: When mandatory fees are required,
social concerns may make special rates for classes of low income customers
appropriate. The jurisdiction may want to consider:
o alternate eligibility criteria ~ all low income, low income with children,
low income elderly or handicapped, medical eligibilities, etc.
14 Prior to 1989, Seattle charged multi-family rates lower than those charged to
single-family households to account for savings related to fewer stops and the
'clustering' of cans. However, the most recent analysis showed these savings were
very low and the lower rate was eliminated.
15 Therefore, a five-plex building subscribed to six cans would pay for five full one-
can subscriptions (including five customer charges) plus one additional can rate.
16 However, for the most part, transfer and hauling costs may vary more on the basis
of volume more than weight.
17 Weight-based rate systems, discussed later in this paper, may eventually eliminate
this problem.
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o the effect of alternate rates on billing system cost and efficiency
o how to determine eligibility.
o whether the rates should be lower throughout all volume-levels or
whether discounts should be truncated after a "basic" level of service.
o whether aid should take the form of lower rates, special services (such as
free backyard collection), or emergency funds.
o which classes should pay for the rate subsidy, and which rate subsidy
design is most equitable to all customers.
BUT VOLUME BASED RATES ARENT PERFECT. ARE THEY?
No. Metered systems, or systems that allow customers to pay for the exact
amount18 of waste they dispose, would be better. Systems based on smaller
increments of waste are better, and could provide recycling incentives that are
more volume-sensitive. In addition, the more immediate the payment, the more
reinforcement provided. A more immediate payment for solid waste service
provides a stronger message to customers.
However, trade-offs with ease of implementation and understandability must be
made. Workable compromises include Seattle's system of subscribed cans
augmented (for flexibility) with pre-paid stickers, or the pre-paid bag systems
used in other jurisdictions.
ARE THERE BETTER METHODS AROUND THE CORNER?
One of the major objectives of variable rates is to establish a link between a
customer's solid waste disposal choices and the bill that the customer pays.
This is the key to providing an incentive to reduce the amount of waste
disposed through waste reduction and recycling. Variable rates systems, unlike
tax methods or systems with fixed bills for unlimited service, provide these
incentives.
The volume-based methods of variable garbage rates discussed above are in
place now in a number of communities. However, volume-based rates have
some weaknesses.
/
o Existing variable can rate systems charge on the basis of subscription,
not usage. Under a variable can system, if a customer uses less than the
18 and even type of waste
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subscribed level of service in a particular week, that customer sees no
savings reflected on the bill. The variable can system is not geared to
the actual amount of service used by the customer.
Customers are charged on too large an increment of service. With either
variable can or bag/tag systems, one of the problems is that the
increments on which customers are charged are generally quite large —
either a "can" or a "bag" of waste. In order for customers to save money
on their bill, they must reduce or recycle a full can or bag of waste. If
customers have waste that even partially fills a service level, they have
every incentive to fill it up because they will be pay for that entire
service level.
Both types of systems can be inconvenient. On the customer's part, they
must decide on a "normal" subscription level, and make calls for changes.
They must purchase and have on hand an adequate supplies of bags or
tags. The solid waste jurisdiction may need large inventories of cans of
different sizes, and have a network for providing bags or tags as needed.
Some modifications to the current volume-based methods could be considered.
Variable can systems could be modified with a variety of smaller can sizes -
half cans, quarter cans, etc. A variety of bag sizes could be introduced.
However, this would not solve the inconvenience problems that exist, and
would not necessarily provide the flexibility needed to maximize the waste
reduction and recycling incentives.
However, with grant funding from the Environmental Protection Agency,
experimental work is currently being done to test the feasibility of an
innovative new idea in garbage rates -- a field-test called "Garbage by the
Pound".
WHAT IS "GARBAGE BY THE POUND"?
The concept behind the Garbage by the Pound experiment is to test whether it
would be feasible to introduce a system that would charge customers by the
amount of solid waste service they use based on the pounds of waste disposed.
The project is designed to test the mechanical, operational, and customer-
related feasibility of a solid waste collection system that would weigh customer
cans and charge on the basis of the weight of waste removed. This system
would be flexible for the customer and the collection system, and would
decrease the size of the increments by which customers are charged for solid
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waste service. Special cans or bags would not be needed. Requests for service
level changes would no longer need to be coordinated. This approach is closer
to "metered garbage service", bringing the delivery and charges for solid waste
services into closer alignment with that provided for other utilities like
electricity, gas, and water. Charging by the pounds of waste actually disposed
each week would dramatically improve the link between behavior and bill, and
thereby improve the customer's waste reduction and recycling incentives. And
although it is true that landfills do not fill up because they are too heavy, and
many jurisdictions pay for disposal based on a volume measure (cubic yards), a
weight-based approach shows particular promise because: 1) quick measures of
small volume measure increments would be difficult to implement and may
require judgment on the part of the field staff, and 2) technologies to
accurately measure small increments of weight are convenient to use, well-
accepted, and proven in the marketplace (scales).
The objective of the project is to do a field test of a system of this type to
begin to determine whether such a system might be feasible. This project has
several major tasks.
o Identify and install weighing/scanning equipment. The preferred system
would simplify or minimize changes to current collection procedures.
More complex collection procedures would lead to higher long-term labor
costs for collection and adversely affect the cost-benefit analysis. The
initial system that was considered was a truck-mounted automatic
scanning device to read bar-codes on the individual garbage cans, with
the weight for each can automatically recorded, to be downloaded into a
billing computer. This automatic approach would minimize the
collection system changes, requiring generally one step to register the
weight.
o Field test the system on customer routes. This includes modifying the
installed system as operational or mechanical difficulties are found. A
three-month field test was envisioned.
o Customer studies. Customers on the selected routes will receive bi-
weekly statements that summarize for them the amount of waste they
disposed. This phase of the project includes an evaluation of customer
behavior pre- and post-to see if the dummy bills caused them to reduce
waste, evaluating a survey to determine effectiveness of the approach
based on socio-demographic and behavioral factors, and to elicit feedback
on the system.
o Estimate costs and benefits of the system. This part of the project
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includes an evaluation of the system costs, accuracy, time/convenience,
learning skill, reliability and durability, results regarding collection and
system changes, effectiveness, payback, and tradeoffs.
o Dissemination of results. The results of this EPA-sponsored project will
be fully available. If the approach is successful, it is hoped that private
industry (truck and scale companies) will work to further develop and
enhance the technology on a larger-scale basis.
HOW FAR ALONG IS THE PROJECT?
At this point, the project has selected one technology and is doing preliminary
field testing.
Scale: The scale technology being evaluated is a small industrial crane scale.
A crane scale is primarily a hook and load cell suspended at the back of the
truck. The barrels are hung on the hook manually by their handles. The
system is based on available technology, can be installed so that it minimizes
the external attachments that could be damaged by ground or alley clearance
problems, weighs consistently on grades and inclines, and fits easily into the
current collection system. During later stages of the project, we are examining
the feasibility of retrofitting the cart dumper to weigh the barrels during semi-
automated dumping. This technology would be less labor intensive and may be
more applicable to systems in other jurisdictions.
Scanner: It has proved infeasible to have a truck-mounted automatic scanning
system because no rugged technology is currently available. Instead, the
project is using a bar code system that uses a 'rugged-ized' hand-held module
(that is mounted in a bracket on the truck) and requires the use of a manually-
activated "gun" to read the bar code. This two-step process (hanging the can
plus activating the "gun") is still simple, but may not be efficient from a labor
point of view. The project will be evaluating whether the "gun" bar code
reader can be mounted in a holster and the programming modified so that the
system can automatically read the bar codes on the cans. Although radio
frequency may provide a quicker data collection method, installation and
purchase cost have been prohibitive for the field test. This technology may
show promise for full scale implementation.
Logger: Data storage during collection is in the portable data collection unit.
Data from both the bar code scanner and the scale are stored here, and
uploaded and downloaded to a PC for updating the customer file and preparing
the biweekly customer reports.
The field test is expected to continue throughout the summer, with a report
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due in early fall. Information on the project will be available at its conclusion.
Preliminary information certainly demonstrates the equity benefits of the project
in that there was considerable variation in the amount of waste currently being
disposed in similar-sized containers -- one test run showed variations between
10 and 63 pounds of waste in identical 32-gallon cans!
Although this is an experimental project, it is hoped that in the long run, a
system can be developed that is practical and flexible for use in the variety of
solid waste collection services. Such an approach has the capability to be more
equitable than current approaches and to provide significantly unproved waste
reduction and recycling incentives.
SUMMARY
Many solid waste jurisdictions are facing tough challenges. Landfill space is
becoming a problem, and jurisdictions need ways to reduce the amount of
waste going to increasingly expensive disposal facilities. Expensive recycling
programs are being under-utilized. Variable rates give an economic incentive
for customers to reduce the waste they dispose of, and provide incentives for
recycling and waste reduction.
Variable rate systems are fair and effective, and provide a number of other
advantages, including:
o they can be implemented in a variety of situations
o the rates can be implemented relatively quickly
• o variable rates can lead to system savings, and
o they integrate well with other programs, increase participation in
recycling programs, and reinforce waste-reducing behavior.
There is no doubt that, from a variety of perspectives, many jurisdictions could
benefit from replacing their current fixed-rate systems with volume-based rates.
Variable rate systems work, and make a great deal of sense from a system
perspective. A variable can rate structure has proven to be one of Seattle's
most effective recycling programs, and bag systems have proven to be very
effective in a variety of smaller communities. The rates are a vital part of the
Seattle's integrated solid waste system, and have allowed that Utility to set an
aggressive, but achievable. 60% recycling goal. Seattle's customers have
responded well to a rate structure that gives them alternatives and control, and
they have responded with high levels of private recycling, very high
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participation levels in City-sponsored programs, significant reductions in service
levels, and significant decreases in the waste brought to landfills. Customers
have become an integral part of the solid waste system.
For further information, contact:
Lisa A. Skumatz, Ph.D.
Synergic Resources Corporation
1511 Third Avenue, Suite 1018
Seattle, Washington 98101
(206) 624-8508
To order a copy of the Variable Rate Manual,
contact:
Winnie Hooker
EPA Region 10, HW072
1200 Sixth Avenue, 7th floor
Seattle, Washington 98101
(206) 442-6640
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ZONING FOR RECYCLING
Patricia H. Moore
Moore Recycling Associates
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16,1990
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ZONING FOR RECYCLING
INTRODUCTION
Solid waste disposal is becoming an increasing problem throughout North
America. As a result of rising costs for waste disposal, there has been an increase
in the number of waste reduction and recycling facilities. Increasingly, these
facilities are running into barriers to their development in the form of local
zoning ordinances which often do not address recycling facilities or, when they
do address them, it is in very narrow terms.
HISTORY OF ZONING
The U.S. Supreme Court approved the concept of zoning in 1926 with Euclid v.
Ambler Realty Co. (272 U.S. 365), and has since upheld zoning unless it was
arbitrary or denied the owners all reasonable use of their property. According to
Alexandra Dawson, in Landuse and The Law. "Every state now has a zoning act
or a zoning enabling act authorizing cities, towns or counties to adopt zoning
codes". Zoning was originally used as a tool to protect the "highest and best use,11
normally single family homes, from less desirable uses (multi-family dwellings
or industry), which might lower property values. Thus, from its inception
zoning was not used to create a comprehensive land-use pattern which could
make the best use of natural, economic and social resources, but to protect the
aesthetics and property values of neighborhoods.
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Concern about the denial of all reasonable use of property, known as "the taking
issue" has led to the institutionalization of a variety of options for property
owners who want to pursue a use for which their property is not zoned. The
most common option is the variance which allows a local board to vary the
zoning when it would create a hardship to the owner, thus denying the owner
use of his or her property. The variance has come under considerable criticism
because of its misuse. It is often used when better solutions, such as reclassifying
the use, may prove to be a lengthy process or cause political difficulties.
RECYCLING CENTERS AND ZONING
Recycling is quickly becoming an integral part of solid waste management. As ?.
rapidly expanding industry its relationship to land-use is still unclear. Public
officials, planners and politicians are becoming aware that there is an increasing
need for recycling facilities and that there are many sizes and types of recycling-
operations. Yet most local governments still do not have provisions in their
zoning ordinances for the proper siting of the various types of recycling facilities.
In many cases all recycling centers are classified as salvage yards which are
traditionally zoned as light industry. While this may be appropriate for large
processing centers, which have little contact with the general public, it is highly
undesirable for a buy-back center which is set-up to provide the public a
convenient location to bring such recyclable materials as aluminum cans, glass
bottles, newspaper and plastic bottles. In addition, as waste processing becomes
more sophisticated, there is growing concern over the definition of a recycling
center versus a solid waste facility.
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CAN PAK RECYCLING INC
Can Pak Recycing, Inc. is an example of a business which encountered a zoning
problem. Can Pak Recycling, Inc. tried to set up a buy-back center in an old two
bay gas station/convenience store, in Del City, OK. Del City is a middle-class
bedroom community near Oklahoma City with a population of around 30,000.
The local zoning ordinance, voted into effect in March, 1987 after a three year
study, considers all permanent recycling operations as salvage yards classified as
light industry.
Can Pak, Inc. operates buy back centers nationwide, though it primarily operates
in the west, midwest and southeast. It is a subsidiary of IMS Recycling Servicss
of San Diego CA. Oklahoma City area manager Jim Jenkins, oversees two
successful buy-back centers currently operating in nearby Norman and Nicoma,
OK, as well as a central processing facility in Oklahoma City. He hopes to open
several more satellite facilities (buy-back centers) which will be serviced by the
Oklahoma City processing facility.
The proposed site, in Del City was located in a Cl zone (commercial zone), in a
residential neighborhood on a corner lot of a major east/west thoroughfare, East
Reno Street, a section line road1. Mr. Jenkins expected about 25 to 30 cars per day
would bring material to the center, with the busiest days being Mondays and
1 The term "section line" refers to the division of the area into 640 acre parcels when the territory
was first homesteaded. The borders of these sections have naturally become major travel routes.
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Saturdays. Can Pak's goal was for the facility to bring in 4000 Ibs./week of
aluminum cans. According to Mr. Jenkins, there was plenty of parking to
accommodate the expected flow of traffic.
A successful buy-back center needs to be convenient and attractive. Consumers
generally don't want to go out of their way or to traditional areas (industrial
zones), to recycle their bottles, cans and paper. Participation is much higher if the
public can recycle materials as easily as they buy goods at their local convenience
store. It is important for the facility to be neat, clean and attractive to the general
public. Mr. Jenkins explained that as well as being concerned about the esthetics
of their facilities, Can Pak uses low noise aluminum can densifiers to avoid
disturbing the neighbors.
Mr. Pat Salvator, Regional Director of Can Pak Recycling Inc., explained that the
facility was given both the electrical permit and building permit but when they
tried to get an occupancy permit they were denied due to the zoning discrepancy.
Mr. Jenkins questioned the City Planner about why two buy-back operations, run
by Reynolds Aluminum, consisting of tractor trailers parked in privately owned
parking lots in a commercial zone, had no trouble getting permits. The City
Planner knew nothing about the Reynolds trailers, which were operating wi:h
the permission of the parking lot owners but without any City permits. The City
Planner felt this brought up some "question of the legality" of the Reynolds
operations and an "investigation" was launched. According to the Chief
Inspector of Code Enforcement for Del City, the decision was to grant 90-aay
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outdoor use permits, as they would for a parking lot tent sale, though the matter
has not been settled.
Mr. Jenkins, after he "tried everything else", determined that Can Pak's only
option was to try to have the lot rezoned as light industrial. Because of the
wording of the zoning ordinance there were no grounds for a variance and no
"permit by right" exists in the ordinance, so reclassifying the use or rezoning
became the only possible solutions if Can Pak wanted to keep the buy-back center
at the proposed location. Reclassifying is a much lengthier procedure than
rezoning. As a result, Can Pak filed to have the lot rezoned to light industrial.
To rezone, all abutting property owners have to be notified and a public hearing
must take place. Although there were no objections from the public at the
meeting, Can Pak had to withdraw their request for rezoning because the light
industrial zone requires a minimum one acre lot size. The lot in question was
.29 acres. Frustrated, Mr. Jenkins noted "we are trying to get the public and public
officials to understand that we're not a junkyard", though he admits it will be a
"long drawn-out process" because "nobody has figured out what procedures to
use to get away from the junkyard image."
Ironically, everyone involved, including Del City officials and Can Pak
employees, understands the value of having the recycling facility in Del City. It
is simply that the zoning code has not allowed for a buy-back recycling center ir.
the use classifications.
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CALIFORNIA'S SOLUTION (AND THE SOLUTION'S PROBLEMS)
In recognition of the zoning barriers for commercial recycling centers and in
response to the enactment of the 1986 California Beverage Container Recycling
and Litter Reduction Act (AB 2020), the State of California has developed a
model local zoning ordinance for beverage container recycling.
AB 2020 states that there must be a certified recycling facility in every
convenience zone defined as: within 1 /2 mile of a supermarket with $2 million
or more in annual sales. According to Tania Lipshutz of the California
Department of Conservation, Division of Recycling, this resulted in the
establishment and permitting of approximately 2,000 new recycling centers
within one year, as well as processing facilities to support them.
The Act permits local governments to adopt rules and regulations governing ;>.e
operation of mobile recycling units or reverse vending machines. AB-2C20
prohibits any agency from denying permits for the operation of mobile recycling
units or reverse vending machines which have the permission of the property
owner and are located on property zoned for commercial or industrial use
within a convenience zone, unless the agency specifically finds that the
individual facility would be detrimental to the public health, safety and well
being. AB-2020 does not address the permitting of other larger recycling facilities
or facilities outside of the convenience zones though the model zoning
ordinance does.
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Ms. Lipshutz notes in her paper Zoning and Planning for Recvcline, presented to
the 1988 National Recycling Congress; "the Division [of Recycling] found that
elements of existing zoning ordinances hampered the permitting of even these
small recycling centers, zoning ordinance amendments were often necessary,
since the ordinances often included:
• Treatment of any type of recycling center as a junkyard, and therefore,
restricting them to heavy industrial zones;
• Prohibition of outdoor activities or outdoor storage in commercial or
manufacturing zones;
• Limited procedural options, requiring extensive and expensive use
permits and architectural review for large permanent recycling cenrers
and small donation centers alike; and,
• Prohibition of any activity not specifically allowed in the zoning
ordinance."
The model ordinance divides recycling centers into five categories: 1) Reverse
Vending Machines, 2) Small Collection Facilities, 3) Large Collection Facilities, 4)
Small Processing Facilities and 5) Large Processing Facilities. The ordinance
defines the recycling terms used, determines the permits needed (see figure 1),
and sets criteria and standards for each of the categories of recycling facilities.
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Figure 1
Type of Facility
Reverse Vending
Machine(s)
Small Collection
Large Collection
Zones Permitted
All Commercial
All Industrial
All Commercial
All Industrial
C-l
Other Commercial
Industrial
Permit Required
Administrative (or by right)
Administrative
Minor Use
Site Development
Site Development
Alternative
Permit
Minor Use
Minor Use
Minor Use
Minor Use
Light Processing
Heavy Processing
Heavy Commercial
All Industrial
Light Industrial
Heavy Industrial
Conditional Use
Minor Use
Conditional Use
Site Development
Conditional Use
Conditional Use
Source: California Beverage Container Recycling - Local Government Guide
f1
In reviewing the ordinance there are two potential problems that could arise if it
is adopted. The first is the definition of a processing facility versus a collection
facility. The distinction made in the model ordinance is the use of power driven
equipment. The ordinance fails to recognize that the use of volume reduction
equipment is necessary for most collection facilities to ship material cost
effectively. This is especially true for materials that have a high volume to
weight ratio such as plastic bottles and aluminum cans, which are costly to ship
without some densification.
One possible solution would be to include performance specifications in the
zoning law to protect neighbors from unwanted noise and (as mentioned in the
model ordinance) unsightly operations.
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The second potential problem is the definition of recyclable material: "Recyclable
material is reusable material including but not limited to metals, glass, plastic
and paper, which are intended for reuse [emphasis mine], remanufacture, or
reconstitution for the purpose of using the altered form. Recyclable material
does not include refuse or hazardous materials." This definition may be a
problem because, as landfill tipping fees rise, the recovery of materials is
becoming more sophisticated and the distinction between recyclables and refuse
is becoming less obvious. Without a clear definition of what constitutes
"recyclable" material there is the potential for the permitting of recycling centers
which in reality are waste transfer stations or facilities which are stockpiling
materials "intended for reuse" but for which there is no market.3
One solution could be to specify designated materials as being "recyclable" but
this may have the unwanted effect of discouraging the development of new
recycling technologies.
NEW JERSEVS SOLUTION (AND THE SOLUTION'S PROBLEMS)
The New Jersey Department of Environmental Protection (NJDEP) is curreniiy
struggling with the problem of defining a recycling center. Under New Jersey's
law, solid waste facilities are exempt from local zoning laws and recycling centers
are considered solid waste facilities. However, recycling centers do not have to
go through the rigorous Environmental Impact Statement (EIS) process and are
not regulated by the State. The only requirement is that recycling facilities musi
3 Many state and local statutes cover this problem by specifying a time limit for storage.
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be in the County Solid Waste Plan. This has led to a few facilities taking
advantage of the system and calling themselves recycling centers when they are
actually waste transfer stations as well as recycling centers.
As per N.J.S.A. 13:lE-99.34 " no recycling center shall receive, store, process or
transfer any waste material other than source separated nonputrescible or source
separated commingled nonputrescible metal, glass, paper, or plastic containers,
and corrugated and other cardboard without the prior approval of the
Department." With the increasing profits to be made handling solid waste ir is a
difficult law to enforce.
The problem became headline news in New Jersey when on August 7,1989, a fire
at Hub Recycling & Scrap Co. buckled a portion of Interstate 78 in Newark. Hub,
which had declared bankruptcy in 1987, built up 30-foot piles of debris, most c: it
on neighboring property, using the recycling center as a front for an illegal
landfill.
Prior to the Hub fire, Senators Contillo, Costa, and Ambrosio introduced an act
amending the New Jersey Statewide Mandatory Source Separation and Recycling
Act to "facilitate the growth and development of commercial recycling activities
in this State." The bill, which has been accelerated through the legislative
process since the Hub fire, attempts to set definitions to distinguish between
regulated solid waste facilities which also engage in recycling activities (termed
by the bill as "recycling facilities") and unregulated facilities which are strictly
commercial recycling operations (termed by the bill as "recycling centers"). In
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addition, the bill requires the, newly defined recycling centers to be licensed by
the DEP. The revenues from the fees collected are to be used by the DEP to
support enforcement, including the periodic inspection of licensed recycling
centers to ensure that they are not accepting solid waste.
The definitions for recycling operations are very clear:
"Recycling center" means any facility, including a scrap processing
facility, and designed and operated solely for receiving, storing,
processing and transferring source separated, nonputrescible or
source separated commingled nonputrescible metal, glass, paper,
wood, rubber, plastic and plastic containers, and corrugated and
other cardboard, or other recyclable materials approved by the
department, and licensed under the provisions of section 5 of P.L.
1988, c. (now before the Legislature as this bill);
"Recycling facility" means any transfer station or other solid waste
facility at which putrestible or nonputrescible solid waste is accepted
for disposal or transfer and at which recyclable materials are
separated or processed from solid waste onsite for the purposes of
recycling:
Originally, the bill was not well received because it placed an additional burden
on the operators of legitimate recycling centers but, due to the Hub fire, it becarr.
dear that such legislation was needed.
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SUMMARY
As the volume of waste and cost of solid waste management increases the
viability of more extensive recycling and waste reduction activities will also
increase and decisions to determine the best land-use options will become more
complicated.
It is important for all public officials, like those in California and New Jersey, to
recognize that these issues exist. We must begin to address them by using the
available tools. One of these tools, zoning, will be extremely useful for attracting
the kind of private sector initiatives necessary to help solve our growing solid
waste problem. With zoning which encourages recycling operations of all types,
a city, town or region can expect to see an increase in commercial recycling
activities which will mean an increase in jobs, a boost for the local economy £r.d
a reduction in the amount of solid waste needing disposal
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COMBUSTION
-------
CHALLENGE OF COMPLIANCE
WITH EPA'S NEW MUNICIPAL
WASTE COMBUSTION REGULATION - MDDTJLAR FACILITY
PASCAGOTJLA, MISSISSIPPI
Lloyd J. Corapton
President
Comptcn Engineering, P.A.
Pascagoula, Mississippi
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
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I. ABSTRACT
The Pascagoula Energy Recovery T^acility is a typical european
style ness-bum excess air facility. It houses two (2) solid waste 75
ton/day modular units capable of producing an average of 151 million
pounds of steam per year. The steam generated is sold to Morton
International, a nearby chemical plant. Although the facility is owned
by the City of Pascagoula, it is considered a regional plant. The
plant is located in the adjoining City of Moss Point and receives solid
waste from Pascagoula and Moss Point as well as over 50% of Jackson
County.
The plant, the first and only facility of its kind in
Mississippi, has been in operation since 1985, has since incinerated
over 180,000 tons of solid waste and generated over 800 million pounds
of steam. Attachments to this paper are furnished containing
additional information on this system.
This paper is presented to discuss the impact of the USEPA
Proposed Environmental Guidelines, particularly their effects on small
scale modular facilities.
II. INTRODUCTION
The topics discussed in this paper are in response to the
proposed rules of Emission Guidelines for municipal waste combustors
including: controlling emissions from existing municipal waste
combustions (MWC) and recent USEPA notices relative to pending ash
disposal legislation. The overall goal of these guidelines is to
reduce air emission pollutants by 90%.
We have attempted to discuss each of the proposed regulations and
compare them with existing performance based on current test data. Vfe
have also estimated the cost of the improvements required to meet the
new standards.
In generally, the following topics are discussed:
MWC Emissions
Materials Separation
MWC Ash Disposal
III. MWC EMISSIONS
Based on the proposed guidelines, the emission requirements are
divided into several categories:
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Best Demonstrated Technology
MWC Organics
NWT Metals
M3W Acid Gases
Coirbustion Control
Certification and Operation Training
1. Rest Demonstrated Technology
According to the guidelines for small scale facilities, the best
demonstrated technology requires (1) good combustion and (2) an
electrostatic precipitator. We believe the Pascagoula plant basically
fits these guidelines, therefore, capital or operation cost increases
are not expected.
2. MV
-------
tons/day.
5. Combustion Control
The CO emissions at the facility have been tested at less than
100 ppmv. The exact CO content of the flue gas has not been accurately
determined. However, since the unit operates en excess air with a flue
gas O2 content of 15%, the proposed CO limit should be easy to achieve.
The proposed flue gas temperature limit of 450 degrees F or less
is consistent with present operations at the facility. The temperature
is measured upstream of the PM control device.
We object to the proposed continuous monitoring locations. The
guidelines require testing for the flue gas CO level at the inlet to
the electrostatic precipitator. We feel the location should be
dovnstream of the device since upstream measurements result in
increased maintenance. Additionally, a continuous load weight
measuring device at the MWC was installed as part of the original
design. We found this equipment inpossible to maintain as well as
inaccurate in measurement.
We believe daily monitoring of the waste via mass balances (total
in minus bypass and oversized bulky waste) will provide sufficient
records.
Regarding continuous temperature monitoring, the facility
maintains adequate temperature records since this information is
imperative for proper operation of a steam plant.
We estimate the cost for installing the added monitoring system
(including the opacity meter) at $ 100,000. The annual operating cost
is approximately $ 5,000/year.
6. Certification and Operator Training
We support the requirement for certification by the American
Society of Mechanical Engineers (ASME) for the Chief Facility Operator
and Shift Supervisor. The facility presently is under contract to a
private operating firm which monitors their owi certification program.
Standardization to the ASME regulations would assure the City that
operators possess adequate "knowledge of conbustion and power
generation. It is possible that operation certification will cost the
City an initial cost of $ 10,000 and an annual labor cost of $
30,000/year.
TV. MATERIAL SEPARATION
The proposed 25% reduction will have an adverse effect en the
facility. This will result in a tonnage reduction from 36,000 to
Page 3
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27,000 tans/year. For the purpose of evaluation, we have assumed that
50% of the glass, metals and plastics are recycled, 10% of the garden
wastes are composted and 25% of the paper waste is recycled. The BIU
loss plus the reduction of disposal fees result in a 25% revenue loss.
This would increase the tipping fee from $ 17.40/ton to over $
26.00/ton (over $ 240,000 annual increase). Since two private
landfills will charge approximately $ 18.00 per ton for hauling and
disposal, the increased cost will more than likely make the facility
non-competitive.
We have reviewed two material separation methods (1) curbside or
source separation and (2) separation at the plant. There are potential
financial benefits for the facility for separation at the plant en site
separation will maintain waste volume at current levels and provide
income from material sales. These benefits, however, do not offset the
added cost of plant modification and operation and maintenance. In our
opinion, therefore, curbside separation is the only viable option.
Unless consistent markets can provide sufficient income to offset
costs, it is doubtful that communities around Pascagoula will continue
to support the facility. These communities will more than likely elect
to utilize the less expensive option of landfilling.
We support the material separation and recycling options, they
are viable in larger populated areas with limited disposal
alternatives. In Mississippi, however, the markets for recycled
materials are scarce, and the County may not produce a sufficient
volume to entice long-term agreements.
We believe that incineration is a form of solid waste reduction
and at least the reduction programs be site specific in areas where (1)
the costs are not prohibited, (2) the waste volume is significant to
entice markets, and (3) the reduction requirements are applied only to
landfills or incineration which are not producing an energy by-product.
An energy recovery system is a form of recycling by reducing fossil
fuel requirements and conserving energy for future generations. We
feel the requirements should at least be delayed until sufficient
markets for recycled materials have been established to offset the cost
of material separation and handling.
V. MWZ ASH DISPOSAL
Presently, the Pascagoula facility deposits the ash from the
facility in a monofill. The site was constructed in 1988, specifically
for ash, by a private contractor. The facility includes grcundwater
monitoring wells and leachate collection. The monofill is located in
an area having over 40 feet of clay liner and so far has been
successfully operating. Tests have been performed to quantify the
dioxin/furan content. The results indicate the dioxin and furan levels
are 0.107 ppb, well below the maximum allowable concentration of 1.0
Page 4
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Additionally, the ash is tested for heavy metals (EP toxicity)
both at the plant and at the ash disposal site. Based on over 100
samples, no metals above the maximum concentration have been
encountered. The tests performed are based on composite ash samples
from the following locations in the facility:
Bottom Ash 93.5%
Undergrate 5.28%
Post Combustion Units 0.03%
ESP Fly Ash 1.06%
Future legislation may impose additional requirements on ash from
the facility. We feel that only the fly ash should be regulated. -The
remaining should be approved for use as road fill, cinder block
manufacturing, etc. We recommend test programs be widely initiated to
demonstrate the uses of ash. Based en cur experience at the ash
landfill, we have found that ash is an excellent road base material and
may have a high market potential in South Mississippi due to the lack
of conventional fill materials.
Although regulations have not been completely developed, we
understand that the EP toxicity test will be modified with additional
testing required. If annual .tests are required to measure the
dioxin/furan contents, we estimate an added cost of $ 30,000/year.
VI. SUMMARY AND COSJCLUSICN
Overall, small scale facilities such as the Pascagoula Plant
should have no major problems meeting the majority of the proposed
emission -regulations. The additional testing and monitoring
requirements, however, will add substantially to the operation and
maintenance costs at the facility. If a material separation program is
mandated, the cost increase will be even more significant.
Summarizing, the added costs at the facility are:
Estimated Cost Increase
Based on Proposed Regulations
Item Capital Annual $/Ton (1)
Demonstrated Technology -0- -0-
Organic Emissions -0- ? 30,000
Metal Emissions -0- 10,000
Acid Control -0- -0-
Combustion Control $ 100,000 5,000
Certification 10,000 30,000
Material Separation -0- 240,000
Page 5
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Subtotal $ 110,000 $ 315,000 11.66
Annual Cost of Capital (2) 16,000 0.59
Total Annual Increase $ 331,000 12.26
Existing Fee 17.43
Adjusted $ 29.69/Ton 29.69
% Increase 70%
(1) Based en 27,000 tons/day from existing 36,000 tons/day.
(2) 8% interest - 10 year payout.
In comparison, landfill costs also have had changes in
regulations resulting in increased disposal costs. To control these
added costs, regionalized landfills have been developed charging from
$ 12 - $ 15/tcn. As recycling or material separation becomes
mandatory, landfill costs will also increase.
Material separation and recycling most be cost effective based on
the sale of recyclables. This requires market development (presently
in progress) and regionalized recycling centers. Until such time as
consistent markets for recycled materials are developed, it is my
opinion that material separation will increase disposal cost at all
facilities and compound the communities economic problems.
The challenges that that each public official mist meet are:
1. Finding the most cost effective nethod of meeting the
environmental regulations of solid waste disposal.
and 2. Determining the most acceptable method to the public.
Most decisions regarding solid waste are based solely on
economics and public opinion. If the public is willing to increase
their taxes and/or user fees, the waste streams will be dramatically
reduced. If not, this problem will continue and all waste in our
region will be landfilled.
To assist the communities in these decisions, the USEPA and the
State Taivircnment Quality Departments mast work with site specific
requirements based on each community's environmental problems. In
areas like Mississippi, the most abundant resource is land. In
counties directly north of the Coast, land is available for $ 300.00
per acre. Since these regions are sparsely populated, landfills in
most cases can be easily sited. A dramatic increase in environmental
regulations may force future disposal in Mississippi to be landfills at
the expense of resource recovery.
Page 6
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Additionally, air pollution limits should be considered based on
location and existing conditions, not blanket requirements for all. A
2000 ton per day facility in downtown New York City should be required
to meet more stringent regulations than a 250 ton per day plant in Moss
Point, Mississippi (population 19,000).
Finally, we must combat environmentalists vho express their opinion
without the basis of fact. The general public responds to issues
emotionally and tend to sway political decisions. As a point in fact,
our facility was recently attacked by a major Washington based
Environmental Coalition as generating a "cloud of death" due to
dioxin/furans. Since we had already conducted tests to demonstrate
compliance, we contacted the individuals to determine their source of
information. Their source was data en ten "similar" facilities, with
less than one half of these showing problems. The Pascagoula Facility
was included without basis of fact.
Divircnmental protection is an issue facing all the population.
We feel it would be in everyones best interest for our community
leaders, environmental leaders, local and state government officials,
and technical experts to work together to help solve the problems we
face. Through their combined cooperation, they can find solutions
based on fact and community concern.
Page 7
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CHARACTERIZATION OF MUNICIPAL WASTE
COMBUSTION ASHES AND LEACHATES
RESULTS OF TWO FIELD STUDIES
HAIA K. ROFFMAN
AWD TECHNOLOGIES, INC.
ABSTRACT
Incineration of MSW has become an important alternative to the
land disposal of MSW. Incineration is an effective means of
reducing the volume of MSW and can provide an important source
of energy. Ash from the combustion of household waste has
been excluded from regulations under Subtitle C of RCRA, which
regulated disposal of hazardous wastes. However, in some
instances testing the residues from municipal waste
incinerators by the Extraction Procedure (EP) Toxicity test
is being required to determine if these residues would be
classified as hazardous waste and, therefore, subjected to
disposal regulations under Subtitle C. Ashes from MWC
facilities, on occasion, have exhibited hazardous waste
characteristics as determined by the EP Toxicity test. The
debate regarding the representativeness and the validity of
this test and the relation of these results to actual
leachates from ash disposal facilities has not been settled.
For this reason, EPA and CORRE have cosponsored a study
designed to enhance the data base on the characteristics of
MWC ashes, laboratory extracts of MWC ashes, and leachates
from MWC ash disposal facilities. Ash samples were collected
from 5 MWC facilities and leachate samples were collected from
the companion ash disposal sites. These ash and leachate
samples were analyzed for the Appendix IX semivolatile
compounds, polychlorinated dibenzo-p-dioxins/polychlorinated
dibenzofurans (PCDDs/PCDFs), metals for which Federal primary
and secondary drinking water standards exist, and several
miscellaneous conventional compounds. The ash samples were
also subjected to six laboratory extraction procedures and the
extracts were then analyzed for the same compounds as the ash
samples. All sampling, laboratory preparation, and laboratory
analysis followed stringent quality assurance/quality control
(QA/QC) procedures.
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A major environmental concern regarding the effects of ash-
monofill leachates is the long-term changes in the
composition of such leachates. To address this concern, EPA
has committed to study such effects at the Woodburn Ash-
Monofill located in Marion County, Oregon. To date, the EPA
selected monofill was visited three times during the past two
years. Ash, leachate, and soil samples were collected and
subjected to the same testing and QA/QC procedures as the
CORRE/EPA study samples.
The major findings of these two studies are described in this
paper.
INTRODUCTION
This paper provides a summary of the findings provided in a
recent report which has been prepared for the United States
Environmental Protection Agency (EPA) and the Coalition on
Resource Recovery and the Environment (CORRE). EPA and CORRE
have cosponsored this study to enhance the data base on the
characteristics of MWC ashes, laboratory extracts of MWC
ashes, and leachates from MWC ash disposal facilities.
The Coalition on Resource Recovery and the Environment (CORRE)
was established to provide credible information about resource
recovery and associated environmental issues to the public and
to public officials. In providing information, CORRE takes
no position as to the appropriateness of one technology
compared to others. CORRE recognizes that successful waste
management is an integrated utilization of many technologies
which taken as a whole, are best selected by an informed
public and informed public officials.
Incineration of municipal solid waste (MSW) has become an
important waste disposal alternative because it provides an
effective means of reducing the volume of MSW as well as an
important source of energy recovery. Currently, 10 percent
of the United States MSW is incinerated. Based on the number
of municipal waste combustion (MWC) facilities being planned
across the country, this percentage is expected to increase
to 16-25 percent by the year 2000.
As incineration of MSW has increased in recent years, so has
concern over its management. To resolve the many legal and
technical issues surrounding ash, Congress is considering
several legislative initiatives that would classify municipal
waste combustion (MWC) ash as a special waste under Subtitle D
of the Resource Conservation and Recovery Act (RCRA) and
require the Environmental Protection Agency (EPA) to develop
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special management standards for the full life cycle of ash.
In anticipation of Congressional action, EPA and the Coalition
on Resource Recovery and the Environment (CORRE) cosponsored
this study to characterize ash and to gain a better
understanding of how it behaves in the environment.
To provide long term ash, leachate, and soil characterization
data, EPA committed to a long-term (several years) study at
an EPA selected ash-monofill. EPA selected the Woodburn Ash-
Monofill located in Marion County, Oregon. To date, this
disposal facility was sampled three times.
DESCRIPTION OF THE CORRE/EPA STUDY
Combined bottom and fly ash samples were collected from five
mass-burn MWC facilities and leachate samples were collected
from the companion ash disposal sites.
The facilities sampled were selected by CORRE to meet the
following criteria:
o The facilities were to be state-of-the-art facilities
equipped with a variety of pollution control
equipment.
o The facilities were to be located in different regions
of the United states;
o The companion ash disposal facilities were to be
equipped with leachate collection systems or some
means of collecting leachate samples.
The identities of the facilities are being held in confidence.
The ash and leachate samples collected were analyzed for the
Appendix IX semivolatile compounds, polychlorinated
dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs),
metals for which Federal primary and secondary drinking water
standards exist, and several miscellaneous conventional
compounds. In addition, the ash samples were analyzed for
major components in the form of oxides.
The ash samples were also subjected to six laboratory
extraction procedures and the extracts were then analyzed for
the same compounds as the original ash samples. The following
six extraction procedures were used during this study:
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o Acid Number 1 (EP-TOX)
o Acid Number 2 (TCLP Fluid No. 1)
o Acid Number 3 (TCLP Fluid No. 2)
o Deionized Water (Method SW-924), also known as the
Monofill Waste Extraction Procedure (MWEP)
o CO2 saturated deionized water
o Simulated acid rain (SAR)
These extraction procedures have been used separately by a
variety of researchers on MWC ashes but never have all six
procedures been used on the same MWC ashes. This was intended
to compare the analytical results of the extracts from all six
procedures with each other and with leachate collected from
the ash disposal sites used by the MWC facilities.
All sampling, laboratory preparation, and laboratory analysis
followed stringent EPA quality assurance/quality control
(QA/QC) procedures. The detection limits of the analytical
methods used were well below present levels of human,
environmental, or regulatory concerns.
The EPA publication "Interim Procedures for Estimating Risk
Associated with Exposures to Mixtures of Chlorinated
Dibenzo-p-Dioxins and Dibenzofurans (CDDs and CDFs)" was used
to evaluate the dioxin data. These procedures use Toxicity
Equivalency Factors (TEFs) to express the concentrations of
the different isomers and homologs as an equivalent amount of
2,3,7,8-Tetrachloro Dibenzo-p-Dioxin (2,3,7,8-TCDD). The
Toxicity Equivalents, as calculated by using the TEFs, are
then totaled and compared to the Centers for Disease Control
(CDC) recommended upper level of 2,3,7,8-TCDD Toxicity
Equivalency of 1 part per billion in residential soil.
The major features of the five MWC facilities and ash sites
sampled are provided in Table 1, and Table 2 respectively.
Pertinent information on the operating conditions of the MWC
facilities, as well as information about the air pollution
control equipment used is also provided in Table 1.
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CORRE/EPA STUDY RESULTS AND CONCLUSIONS
Major findings of and conclusions drawn from the results
obtained from the sampled ash, natural leachates, and
laboratory extracts are summarized in the paragraphs which
follow.
Ash Analysis Results
Of the five ash samples (one from each facility) analyzed for
the Appendix IX semi volatile compounds, four samples contained
bis(2-ethylhexyl)phthalate, three contained di-n-butyl
phthalate, and one contained di-n-octyl phthalate. Two PAHs,
phenanthrene and fluoranthene, were detected in only one of
the five ash samples. These semi-volatile compounds were
detected in the parts per billion (ppb) range.
The results for the ash samples analyzed for PCDDs/PCDFs are
presented in Table 3. This table also includes the calculated
Toxicity Equivalents (TE) for each homolog of PCDD/PCDF. The
data indicate that PCDDs/PCDFs were found at extremely low
levels in each of the ash samples. The Total TE for each ash
sample was well below the Centers for Disease Control (CDC)
recommended Toxicity Equivalency limit of 1 part per billion
2,3,7,8-TCDD in residential soil.
All 25 of the ash samples (five daily composites from each
facility) were analyzed for the metals listed on the primary
and secondary drinking water standards as well as for the
oxides of five major ash components. Although, the results
from these analyses indicate that the ash is heterogeneous,
this heterogenicity appears to have been reduced by the care
taken when compositing the ash samples during this study.
Data from this study showed less variability than comparable
data in the literature.
Metals showing the widest range of concentrations among
samples collected at each facility included barium (ZB) ;
cadmium (ZB); chromium (ZD, ZE) ; copper (ZA, ZB, ZC) ; lead
(ZD) ; manganese (ZA, ZC) ; mercury (ZE); zinc (ZB, ZD, ZE) ; and
silicon dioxide (ZA).
Metals showing the widest variation of concentrations between
the facilities included barium (results for Facility ZC are
lower than the results for the other facilities) ; iron
(results for each facility vary from all of the other
facilities) ; lead (results for Facility ZD are higher than the
results for the other facilities); mercury (results for
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Facilities ZC and ZD are lower than the results for the other
facilities); sodium (results for Facilities ZD and ZE are
lower than the results for the other facilities); calcium
oxide (the results for Facilities ZA and ZB are higher than
the results for the other facilities); and silicon dioxide
(the results for Facility ZC are higher than the results for
the other facilities).
Some additional findings of the ash sampling and analyses are
as follows:
o The ashes are alkaline with the pH ranging from 10.36
to 11.85.
o The ashes are rich in chlorides and sulfates. The
total soluble solids in the ashes varied from 6,440 to
65,800 ppm.
o The ashes contained unburnt total organic carbon (TOC)
ranging from 4,060 ppm (0.4 percent) to 53,200 ppm
(5.32 percent).
Leachate Analysis Results
Only four Appendix IX semivolatile compounds were found in the
leachates. Benzoic acid was found in two leachate samples
collected at one site. Phenol, 3-methylphenol, and
4-methylphenol were found in the leachate samples from another
site. All of these compounds were detected at very low levels
(2-73 ppb).
PCDDs/PCDFs of the higher chlorinated homologs were found in
the leachate from one site only. This indicates that
PCDDs/PCDFs do not readily leach out of the ash. The low
levels found in the leachates of the one site probably
originated from the solids found within the leachate samples
because these samples were not filtered nor centrifuged prior
to analysis.
The metal content in the leachate samples did not exceed the
EP Toxicity Maximum Allowable Limits established for the eight
metals in Section 261.24 of 40 CFR 261. Indeed, the data
indicate that although the leachates are not used as a source
of potable water, they are close to being acceptable as such
as far as the metals are concerned.
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The major constituents in the leachate samples was salt. The
main salt constituents in these leachates were chloride,
sulfate, and sodium. Additional observations on the leachate
analyses were:
o Sulfate values ranged from 14.4 mg/L to 5,080 mg/L,
while Total Dissolved Solids (TDS) ranged from
924 mg/L to 41,000 mg/L.
o The field pH values ranged from 5.2 to 7.4.
o Ammonia (4.18-77.4 mg/L) and nitrate (0.01-0.45 mg/L)
were present in almost all leachate samples.
o Total Organic Carbon values ranged from 10.6 to
420 ppm.
Ash Extracts Analysis Results
The data obtained during the metals analyses of the ash
extracts indicate, in general, that the extracts from the EP
Toxicity, the TCLP 1, and the TCLP 2 extraction procedures
have higher metals content than the extracts from the
deionized water (SW-924), the saturated CO2 solution, and the
Simulated Acid Rain (SAR) extraction procedures.
The EP Toxicity Maximum Allowable Limits for lead and cadmium
were frequently exceeded by the extracts from the EP Toxicity,
TCLP 1, and TCLP 2 extraction procedures. One of the extracts
from the EP Toxicity extraction procedure also exceeded the
EP Toxicity Maximum Allowable Limit for mercury.
None of the extracts from the deionized water (SW-924), the
saturated CO2 solution, and the Simulated Acid Rain (SAR)
extraction procedures exceeded the EP Toxicity Maximum
Allowable Limits. In addition, all of the extracts from these
three extraction procedures also met the Primary arid Secondary
Drinking Water Standards for metals.
Table 4 compares the range of concentrations of the metals
analyses of the ash extracts with the range of concentrations
for leachate as reported in the literature and the range of
concentrations for the leachates as determined in this study.
For the facilities sampled during this study, the data in
Table 4 indicate that the extracts from the deionized water
(SW-924), the saturated CO2 solution, and the SAR extraction
procedures simulated the concentrations for lead and cadmium
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in the field leachates better than the extracts from the other
three extraction procedures.
Additional observations are:
o Of the five composite samples of the deionized water
(SW-924) extracts analyzed for the Appendix IX
semivolatile compounds (one from each facility), only
one sample contained low levels of benzoic acid
(0.130 ppm).
o None of the extracts contained PCDDs/PCDFs. These
data confirm the findings of the actual field leachate
samples that PCDDs/PCDFs are not leached from the ash.
DESCRIPTION OF THE LONG TERM STUDY
The Woodburn Ash-Monofill, located in Marion County, Oregon,
was selected by EPA as suitable to provide the needed long-
term characterization data of leachates generated from the
monofill, of the ashes aging in the monofill and of the
surrounding soils potentially affected by airborne dust from
the ash-monof ill.
As part of the EPA commitment to study these long term
effects, EPA sponsored the first year study (1988) during
which two sampling trips were conducted and the results were
summarized in the report entitled: Municipal Waste Combustion
Ash and Leachate Characterization. Monofill-Baseline Year.
which was published in August of 1989. EPA also sponsored the
second year study, which took place in 1989 and which resulted
in a report entitled: Municipal Waste Combustion Ash and
Leachate. Monofill - Second Year Study and was published in
January of 1990.
The soil, ash, and leachate samples collected during the past
two years were subjected to the same chemical analytical
testing as outlined previously for the CORRE/EPA study. All
sampling and analytical procedures were subjected to the same
EPA required QA/QC protocols as the CORRE/EPA study.
LONG-TERM STUDY RESULTS AND CONCLUSIONS
Major findings of and conclusion drawn from the results
obtained from the samples collected during the past two years
(three trips) from the Woodburn Ash-Monofill are summarized
in the paragraphs which follow.
784
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Ash Analysis Results
As expected, the ash samples contained metals and low levels
of phenolic and phthalate compounds.
The ash samples also contained low levels of dioxins.
However, the 2,3,7,8-TCDD toxicity equivalency of these
samples, calculated following EPA prescribed procedures, did
not reach the center for Disease Control (CDC) recommended
limit for residential soils of 1 ppb.
Leachate Analysis Results
The major constituent in the leachate samples, collected from
this site, is salt. This agrees with data available from
other sites. The total dissolved solids (TDS) levels ranged
from approximately one-third to somewhat higher than the
levels found in sea water. The main salt constituents in
these leachates were chloride, sulfate, and sodium.
The leachate samples contained elevated concentrations of
total organic carbon (TOC) and ammonia-nitrogen. The presence
of these constituents indicates that uncombusted organic
matter remains in the ash and anaerobic biodegradation may be
occurring.
As expected, the leachate samples also contained metals.
However, all metal concentrations in all leachate samples were
below the EP-toxicity maximum allowable limits.
The leachate samples were essentially free of dioxins and the
leachates contained essentially no semivolatile compounds on
the Appendix IX list.
Soil Analysis Results
To date, the soils in the vicinity of the Woodburn Ash-
Monofill have not been affected by the airblown ash dust from
the monofill. The soil samples were essentially free of
dioxins and semivolatile compounds on the Appendix IX list.
The soil samples did not contain metal levels beyond the
levels found in the site background sample. Those soil
samples collected from locations close to roads, which are
785
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subject to vehicular emission effects, contained somewhat
higher lead levels than the site background sample and the
rest of the soil samples.
The soil samples collected from locations close to roads also
contained somewhat higher levels of dioxins. The levels of
2,3,7,8-TCDD toxicity equivalency in all soil samples were
below one part per billion, which is the level recommended by
the CDC for residential soils.
FUTURE LONG TERM STUDY OBJECTIVES
Studies to be conducted in years to come at this site will
provide data on time trends for the ash, the leachates, and
the soils. Some data gaps may be closed, and answers to
important questions regarding the heterogenicity of the ashes,
the varying levels of TDS in the leachates, and the
verification of the existence of anaerobic conditions in ash
monofills may be obtained.
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ENVIRONMENTAL AUDITING OF RESOURCE RECOVERY FACILITY
DINESH C. Patel
Department of Environmental Protection, State of New Jersey
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
787
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Modern society today is the product of constantly advancing
technology. Technological progress is responsible for our overall living
standard and also for pollution and waste. Ihe production of waste
material is an inherent part of natural processes, but nature, in its
wisdom, reuses whatever it produces, from fallen leaves to manures and
carcases, all things which live, and all the substances which their body
exceret, are subject to decay, a process which transforms organic waste in
to nourishment for new life. Mankind has disrupted this natural cycle
through the sheer volume of its waste production and introduction of new
substances which do not breakdown and may poison the environment.
Concerns for the environment are not limited to deterimental effects
of pollution, but also include recovery and utilization of resources now
reconized as finite. It was determined that'energy contents of all the
municipal waste generated in U.S. is equivalent to 50 million tons of
coal. Number of resource recovery facilities continues to increases
rapidly in response to growing shortage of landfill space. Resource
recovery facility (Waste to Energy) reduces the amount of material to be
disposed of by 75 to 80% and hense increases the landfill lifespan; and
steam generated by recovering heat of combution can be utilized to
generate electricity.
The resource recovery facility must not only meet the solid waste
788
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needs of local community, but must also comply with applicable
environmental regulations, be acceptable to public and be compatible with
the environment. Failure to recognize these four aspects of facility
development can result into a filed project. Facility owner or operator
has a responsibility to inspect such facility at regular interval to make
sure that the facility continue to meet all air, water and solid waste
regulations. In order to perform an effective compliance inspection of
resource recovery facility the inspector must be famililar with all
aspects of facility operation and the regulations which applys to it.
This protocol is designed to provide sufficient information to carry out
compliance inspection of Resource Recovery Facility.
What is Resource Recovery Facility?
The primary objective of the resource recovery facility is to capture
the energy released by combustion of solid waste and to reduce the volume
of solid waste to be landfilled. The figure shows schematic of resource
recovery facility:
Trucks enter in the receiving area and unload directly in to refuse
pit. The refuse pit is sized to hold 4 to 7 days worth of trash. Crane
operator working from the overhead cabin control the grapple to move waste
from refuse pit to the feeding hopper. From the feeding hopper waste is
pushed by a ram feeder in to combustion chamber. Here, temperature
greater than 2000 F turn garbage in to ash. Primary and secondary
combustion air from the pit is blown in, below and above the grates
789
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respectively to fuel the combution process in a furnance and to maintain
negative pressure over the pit to prevent dust escape and to reduce the
odor. Excess combustion of all volatiles while still in the combution
chamber. Heat of combustion will be recovered in a boiler thereby
producing superheated steam, which will be used to drive a turbine to
generate electricity. The flue gases from the boiler will preheat the
boiler feed water and then passes through the spray/wetscrubber and
baghouse to control acid gases and to separate fly ash and then discharged
to atmosphere through a stack. Ash remaining in a combustion chamber and
boiler will be removed by a ram discharger and then conveyed to a storage
area. After determining characteristics of ash it will be dumped in a
appropriate landfill.
AUDITING:
All facility should establish self auditing procedure to assure that
compliance with all applicable envirormental laws and regulations is
maintained. Advanced preparation should remove nearly all of the
potential surprises, and assure that your facility is not exposed to
serious legal risk because of non-compliance with environmental rules and
regulations.
An environmental auditing of an operating resource recovery facility
should be a thorough examination of a facility's operating records and
790
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environmental practices, gather informations about its compliance with
federal state and local regulations and to identify non-compliance with
environmental regulations for follow-up corrective action. Following
comprehensive checklist may vary for each facility depending upon specific
permit conditions for respective facility.
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HflttRGNMBHAL COMPLIANCE INSPECTION PEPORT
A. General Information:
Name of the fadlilty:
Facility I.D. number :
Facility Address :
Facility Manager & :
Phone Number
Date of Inspection :
Inspected By :
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B. Incoming and outgoing wastes:
Conditions
Y N
1. Are only permitted waste being accepted at this facility?
(Permitted waste ID # 10, 13, 23, 25)
2. Are all wastes being accepted according to the approved
delivery schedule
3. Are all traffice control signs and/or measures implemented
to provide, orderly vehicle movement?
4. Are only registered vehicles being permitted to off load
their wastes at this facility • .
5. Are all incoming vehicles equipped with functional exhaust
silencer system?
6. Is all waste being delivered to this facility at a rate that
will not exceed the facility's capacity to store and/or process
the wastes? (Processing Rate 12 Tone/hr, Storage 800 Tone)
7. Is there a continuous visual monitoring of all incoming wastes
for unauthorized waste material?
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Y N
8. Are all unauthorized wastes pulled out from the waste stream,
and segragate and stored in a secured manner?
9. Are spot checks being performed by facility personnel in
accordance with the approved operation and maintenance
manual?
10. Have all noise control conditions been implemented?
a. All ash haulage vehicles and ferrous metal transfer
trailer, parking, connecting and disconnecting are to be
conducted within the ash storage building.
b. All ash and ferrous metal revocery being performed within
the ash loading building with doors closed during loading
operation.
c. All vehicles should equipped with functional exhaust
silencer system.
11. Is the operation of the facility in accordance with following
conditions?
794
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N
a. Odor associated with solid waste should not be dectected
off site.
b. The tipping floor entrance and exit doors should remain
closed at all times other than normal operation hours.
c. Air drawn off from the refuse bunker and tipping area
should be used in combustion process.
12. Are non-processible waste materials, process residues and
recovered ferrous metals handled and stored according to the
following:
a. Non-processible waste, process residues and recovered
ferrous metals are to be stored within the confines of
an enclosed facility at all times.
b. All ash residue and recovered ferrous metals from the ash
are to be stored within the ash load-out building and ash
storage building.
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N
13. Are all trailer/roll offs containers being loaded solely
within the ash loadout building in a controlled manner to
prevent dusting, leakage, and spillage?
14. Are all trailer/roll offs containers for ash labeled properly
for tracking outside of the ash load-out building?
C. Operational and Maintenance Requirements:
1. Is the operation of the facility meeting the approved
processing rates? (12 tons/hr or 108 million BTO/hr)
2. Are all systems and related equipments kept in proper
operating order at all times?
3. Are all Emission conditions of Air pollution control
permit being maintained?
a. So2 (Sulfur Dioxide)
The 3 hour average concentration of So2 in the stack gas
from a unit must be less than 20% of the average concentration
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N
of So2 at the inlet to the acid gas control equipment for
that unit. However the concentration of So2 can never
exceed 100 ppmv on a dry basis corrected to 7% oxygen.
b. HCL (Hydrogen Chloride)
For any one hour period the average conce. of HCL in the
stack gas of each unit shall not exceed 50 ppmv on a dry
basis corrected to 7% oxygen or 10% of the HCL concentration
at the inlet to the acid gas control equipment.
c. CO (Carbon Monoxide)
For any one hour period the average concen. of CO in the
stack gas of each unit shall not exceed 400 ppmv on a dry
basis corrected to 7% oxygen. However, the 4 day moving
average concen. of CO in the stack gas should not exceed
100 ppmv on a dry basis corrected to 7% oxygen.
d. No2 (Nitrogen Dioxide)
For any 3 hour period the average concen. of No2 in the
stack gas of each unit shall not exceed 350 ppmv on a dry
basis corrected to 7% oxygen.
797
-------
N
e. Oxygen:
The conoen. of oxygen in the flue gas at the boiler exit
of each unit must be no less than 6% by volume measured
on a dry basis.
f. Non Methane Hydrocarbon's as Methane
For any 3 hour period the average concen. of non-methane
hydrocarbon in the stack gas shall not exceed 43 ppmv on a
dry basis corrected to 7% oxygen.
g. Opacity:
The opacity of the emission from each unit must not exceed
20%. Note: an exception to the 20% limit' is if opacity
did not exceed 20% for more then 3 minutes, during a period
of 30 consecutive minutes. However, it never exceeded 40%.
4. Boiler operating parameters are in accordance with
following Air Pollution control permit conditions?
798
-------
Y N
a. Within one hour after the waste has been introduced
in the boiler the temp, one second downstream of the secondary
air injection area may not be less than 1500 degree Farenheit.
b. No waste being introduced into a boiler unless the temp.
0.3 seconds downstream of the secondary air injection area is
greater than 1500 degrees.
c. The temp, one second downstream of the secondary air
injection area may not be less than 1600 degree at least 90%
of the time waste is being incinerated.
d. Permanent temp, sensors located in the combustion chamber
and at the inlet of the boiler convection section will be
correlated to read the required temp. 0.3 and 1 second
downstream, of the secondary air injection area.
e. Auxiliary burners must be able to operate automatically
if the temp, one second downstream of the secondary air
injection area drops below 1550 degree while waste is being
incinerated.
5. All emission control equipments are in line while waste
is being incinerated?
799
-------
N
a. At no time baghouse be bypassed while waste is being
incinerated unless the temp, of the flue gas entering the
baghouse exceeds 475 degrees or falls below 130 degrees in
which case the waste charging to the affected unit will cease.
b. If the temp, of 1500 degree is not maintained one
second downstream of the secondary air injection area,
waste should not be charged to the affected unit.
c. If 6% oxygen by volume can not be maintained at the boiler
exit, waste should not be charged to the affected unit.
d. During periods the scrubber is down because of a
malfunction, and if for any 3 hour period the average concen.
of So2 in the stack gas for the unit exceeds 250 ppmv on a dry
basis corrected to 7% oxygen, cessation of waste to the affected
unit is required.
6. Are provisions being implemented according to the approved
NJPDES - DWW/DSW section of the permit?
a. Whenever any activities result in a discharge of toxic
pollutants, into the surface or ground waters, the incidents
are to be reported when occure or believed to occur.
800
-------
Y N
b. All effluent limitations and monitoring requirements
should be implemented.
c. All general requirements of DGW and DSW should be
implemented. (Physical inspection on weekly basis)
7. Are provisions being implemented according to the water
allocation diversion?
8. Are following conditions of the approved 0 & M manual being
implemented?
a. Inspections of all major aspects of the facility in
which adverse environmental or health consequences are
possible, should be performed on daily basis.
b. Preventive maintenance are to be performed according to
potential equipment deterioration or malfunction.
c. In the case of any emergency all the facility personnel
should follow the contigency plan contained in the 0 & M manual.
801
-------
Y N
9. Are routine housekeeping and maintenance procedures being
implemented within the facility to prevent accumulation of
dust and debris?
a. Tipping floor is to be cleaned at least once a day.
b. All facility floors/ traps, sumps or catchment basins
maintained free of obstruction to facilitate effluent drainage.
c. Facility grounds are to be maintained in a manner free of
litter and debris.
d. All incoming wastes, facility processed wastes and
effluents stored in a bunker, basin, pitss, sumps or other
containment vessels are to be kept at a level that prevent
spillage or overflow.
10. is all facility exterior facing maintained in a manner
keeping with the original design?
11. Is a qualified applicator of pesticides directing an
effective vermint control program?
802
-------
N
12. is all fly ash that has been processed through the fly
ash conditioning units being properly wetted so it remains
in the wetted state throughout the rest of the residue
processing and or transportation of the ash?
13. Is all water discharge to the river at a temp, not more
than 20 degree greater when it was withrawn from the river?
(If facility's process water is supplied by a river)
14. Are the approved sampling and analysis requirements being
implemented?
a. All samples are to bollected from the approved location.
b. All daily samples are to be composited into a monthly
sample and to be analyzed using EPA Toxidty Test.
15. Are all operational records being recorded on a daily and
monthly basis and have the required monthly summaries and/or
tallies been submitted to the proper agencies
803
-------
D. Safety and Boergency Procedure:
1. Are all security equipment and systems in proper operating
conditions?
2. If there is a turbine/generator trip condition was waste
processing operations reduced accordingly to reflect the
reduction in the boiler thermal load?
3. Are fire detection and protection systems kept operable at
all times?
4. Are all occupational safety and health (OSHA) standards
being implemented in the operation of the facility?
5. Are only facility personnel and authorized visitors allowed
on site?
Y N
804
-------
E. Files and Records:
1. Are following documents and records are maintained all the
times at the facility?
a. Operating Permits and supporting documents
b. Process Flowsheets
c. Emergency Action Plan and Notification procedure
d. Operating Log
e. Maintenance Records
f. Periodic reports filed with regulatory agencies
g. Permit exceedences reports
h. Storage and disposal records
i. Emissions inventories
j. Sampling records and description of analytical method
Y = In Compliance
N - Not in Compliance
805
-------
F. Inspection Consents:
Inspector's Signature Facility Representative's
Signature
8O6
-------
THE FINANCIAL IMPACT OF THE EMISSIONS GUIDELINES
ON AKRON, OHIO'S RECYCLE ENERGY SYSTEM
Ray Kapper
Service Director
City of Akron, Ohio
and
Robert L. Johnson
Project Manager
wTe Corporation
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
807
-------
INDEX
SECTION PAGE
Local Capital Comparison 1
Total Cost 2
Incinerator Ash 3
Recycling 4
Particulate & Acid Gas 5
Organics 6
Cost Impact 7
Tipping Fee Distribution @ $72 Per Ton 8
Curb Service Fee Dollars Per Month 9
808
-------
LOCAL CAPITAL
COMPARISON
TRANSPORT. (BH)
DEBT 8ER. (6.67%)
PUB. FACTE8 (4.87%)
OTHER (1.88%)
PUBLIC UTLmES (39.3S)
EPA QUDELME8 (40%)
The Recycle Energy System is
located in downtown Akron, Ohio. The
facility serves the residents of the City
of Akron as well as several surrounding
communities. The R.E.S. is owned by the
City of Akron and is currently, and has
been for the last three years, operated
under contract by wTe Corporation of
Ohio.
The facility, completed in 1979 at a
cost of 65 Million Dollars, currently
receives and combusts 1,000 tons per day
of residential and commercial solid
waste. It has taken 10 years for the
facility to achieve its design capacities.
After struggling with low production
rates caused primarily by the fuel
delivery system, the City was forced to
invest 2.5 Million Dollars to replace the
pneumatic conveyor system with a more
conventional belt conveyor system.
Safety problems also developed and
numerous fires and explosions caused
damage which required additional
capital investment and expensive
repairs. In addition, operating revenues
did not cover operating costs requiring
heavy City subsidies and the diversion
of limited funds from other much
needed municipal improvements.
Only within the last three years has
the facility begun to operate safely and
continuously providing steam, hot and
chilled water, as well as tipping services,
on a continuous basis to its customers.
Just as the facility has begun to provide
the services for which it was originally
designed, the City finds itself facing
another new challenge as has been posed
by the recent Source Emissions
Guidelines and the pending Draft Ash
Management Guidance (U.S. EPA March
1988).
For the purpose of this paper, we
have included a brief discussion on
incinerator ash management. The U.S.
EPA Draft Ash Management Guidance,
if enacted, will also have a significant
cost impact on municipal solid waste
combustors. We believe it is important
for communities to consider the
aggregate effect of recent EPA
activities.
809
-------
TOTAL COST
),914,139
Rtoyolng (28.1%)
(10.7%)
Air (20.9%)
The City of Akron, along with many
other mid-western cities, struggles with
a declining industry base and increasing
costs. Akron locally funds
approximately 90 Million Dollars in
capital improvement projects per year.
With the new Source Emissions
Guidelines, initial estimates are that
Akron will be required to fund a 40
Million Dollar capital investment. Our
initial estimate for incinerator ash
disposal is 20 Million Dollars which
suggests that Akron will face a total
capital investment of .60 Million Dollars.
This would represent approximately 40%
of a total 150 Million Dollar capital
program. This new potential financial
burden is selective in that it only affects
those communities who have been
progressive and forward thinking and
have already funded municipal waste
combustion facilities to address growing
solid waste problems.
Most citizens
environment. We
importance of
support a clean
all understand the
preserving the
environment in which we live for
ourselves and future generations. The
challenge is how to accomplish these
goals in a logical and equitable manner
and provide the best use of funds for
long-term solutions.
To the layman, the Emissions
Guidelines only requires new equipment
which is intended to better clean smoke
from the combustion of municipal solid
waste, but this is only one part of the
Guidelines. There is also a section
which deals with recycling. It is the
combination of these elements that
makes the Guidelines costly; not only in
terms of capital expense, but also in
annual operating expenses. When Ash
Management is included, the total cost is
devastating.
For the Akron Recycle Energy
System, of the 60 Million Dollar total
capital investment estimated for the new
Emissions Guidelines and Draft Ash
Management Guidance, the largest single
cost would be new ash management
requirements, followed by the
810
-------
INCINERATOR ASH
$20,884,148
Rtoyoflng (29.1%)
(10.7H)
Air (2S.»%)
(34.3*)
requirement to remove recyclables.
It is unclear to what extent the
recycling requirement will affect clean
air, but without discussion as to whether
or not recycling actually impacts clean
air, even the remaining components
carry a heavy financial burden for
existing facilities in consideration of the
relatively small number of such
facilities and their significant
importance to solid waste management.
Before we discuss the impact of the
EPA's new Source Emissions Guidelines^
we must pause to consider current
thinking regarding incinerator ash.
One of the most hotly contested
issues of recent years has been the
method of disposal of incinerator ash.
The two extreme view points are:
I) incinerator ash is a hazardous waste
and should be disposed of in
hazardous waste landfills, and
2) incinerator ash is not a waste at all,
but can be reused as road bases and
other types of soil stabilizers.
The question is whether or not ash
will leach heavy metals under landfill
conditions. Under current regulations,
the test which is used to determine the
teachability of heavy metals from
incinerator ash is the extraction
procedure toxicity test. Several studies
suggest that this particular test unfairly
represents the actual teachability of
heavy metals from incinerator ash. A
recent study, prepared jointly by the
EPA and CORRE (Coalition On
Resource Recovery And The
Environment), suggests that in actual
landfill conditions, leachate from
incinerator ash is very close to primary
drinking water standards. If these
findings are true, rules requiring special
treatment and handling are unnecessary.
Despite the fact that a growing amount
of data indicates that incinerator ash
should be considered a useful material,
the EPA continues to suggest that ash be
landfilled in a monofill constructed to
811
-------
iECYCLING
£17,727,854
(29.1H)
Organic* (10.714)
Air (25.9%)
Ash (S4.SS)
current landfill standards. At present,
very few such landfills exist.
It will be difficult for communities
which had the foresight to build
incinerators to comply with the more
stringent Source Emissions Guidelines,
but at the same time to require these
incinerators to either locate or construct
a specialized landfill for the disposal of
ash in light of current knowledge seems
excessive.
For a City the size of Akron,
estimates indicate that the capital
investment required for the construction
of a incinerator ash landfill alone will
represent 34.4%, or approximately 21
Million Dollars of the total 60 Million
Dollar investment.
Ash Management and recycling
together represent over 60% of the total
capital cost. The requirement to recycle
25% of the input to the Akron facility
represents approximately 18 Million
Dollars of the 60 Million Dollar total
capital investment.
Recycling is a very popular issue
and it appears that the requirement of
recycling is being written into all new
legislation. In Ohio, Akron, along with
most other communities, is already
struggling with the development of
effective City-wide recycling programs.
Ohio has been required to do this as a
result of State House Bill 592 which was
signed into law in June of 1988. The
State of Ohio has elected to include
recycling as one component of a
comprehensive solid waste management
plan.
The new Emissions Guidelines
assumes that the removal of recyclables
will remove pollutants from the air.
Although in some cases this may be true,
there is little comprehensive and
conclusive data to support this approach.
Recycling is a solid waste management
issue and communities all across the
United States will eventually recycle a
significant percentage of their solid
waste stream. Front-end processing at
municipal waste combustors is only one
option and communities should be free
812
-------
P ARTICULATE Be ACID GAS
$15,773,737
RMycBng (Z9.1S)
Orgiriea (tt.T*)
Mr (2BAH)
Art (SX.3%)
to elect or develop those options which
work best and provide the best cost
benefit.
In Akron, the Recycle Energy
System is a waste-to-energy facility, thus
those recyclables which are combusted
and provide an energy contribution are
being recycled. During the next few
years, as markets develop for recycled
materials, combustion may be the most
economical alternative.
Another major component of
emissions regulations requiring extensive
capital investment is paniculate and
acid gas control. Paniculate emissions
are being regulated to approximately
one half of the allowance that existed at
the time of construction of the Akron
Recycle Energy System. Acid gases,
such as hydrochloric acid and sulfur
dioxide, were not considered and thus
not regulated at that time. The result is
that Akron will be required to replace
all existing air emissions control
equipment. It is estimated that this
requirement will cost approximately 15.8
Million Dollars and will require the
installation of lime injection equipment
and new fabric filters to replace the
existing precipitators. This represents
26% of the total investment.
Because Akron has its own landfill,
the City will also experience a
significant side effect of the proposed
Best Available Control Technology. The
current strategy to control acid gases
proposes the injection of lime into the
gas stream, thus transferring an air
pollution problem into a solid waste
problem. For every 22 pounds of sulfur
dioxide that is removed from the flue
gas stream, the facility will generate an
additional 2,000 pounds of solid waste
which must be landfilled. Aside from
the economic impact of the installation
of new equipment, a community such as
Akron will also suffer serious landfill
life depletion whether speaking in terms
of existing landfills or new landfills
specifically designed to accept
incinerator ash.
Organic toxin control represents
813
-------
OEGAN1CS
$6,528,400
RMydng (2B.TK)
Orgariet (10.7%)
Air (28.eS)
Art (844%)
another element of the capita!
investment at approximately 6.5 Million
Dollars. The new Guidelines propose
that dioxins and furans can be
controlled in the combustion process.
The assumption is that improved mixing
of the RDF with combustion air will
create higher combustion temperatures
and destroy dioxins and furans within
the furnace. These are newly discovered
elements in the exhaust gas stream, and
existing facilities, in many cases, were
not designed or constructed with this
type of control in mind. For the City of
Akron, this involves the entire fuel feed
system as well as the overfire air system.
Major changes, including the
replacement of fans and fuel feeders,
will be required in order to comply.
The level which is being proposed
for a large facility is 250 nanograms per
standard cubic meter. In consideration
of the fact that these are newly
discovered elements, control technologies
have not been fully proven, and the EPA
has not fully developed a cost benefit
for such a stringent level of control, this
requirement, at this time, may not
represent the best use for scarce
resources. To retrofit a 10-year old
facility such as the Akron Recycle
Energy System to a level of technology
commonly known as "Best Available
Control Technology" will require
significant investment in new controls,
fuel delivery equipment, fabric filters,
lime handling equipment and front-end
separation equipment.
After the initial capital investment,
the financial burden does not end. The
estimated annual operating cost for all
of the new equipment, as well as a new
landfill, is approximately 8 Million
Dollars a year. This will represent an
increase of approximately 60% over
current operating costs.
Akron, not unlike other
communities across the United States
that have invested in incinerators and
waste-to-energy facilities, has found it
necessary to subsidize the facility since
its start-up in 1979. This substantial
increase in operating cost could lead to
-------
COST IMPACT
UTLITE8 & FUEL (T7.1S)
AOMM A MAN. (3.42%)
OPERATIONS (424%)
AIR (37.2%)
additional local subsidies throughout the
remaining life of the facility.
The current solid waste management
crisis has only come to light as a result
of the dwindling number of landfills.
Aside from the accelerated rate of
landfill closures, more stringent rules
for siting and permitting has rendered
this process time consuming and
expensive resulting in few new landfills
being opened. The new Emissions
Guidelines place a heavy burden on
those few communities which have
already constructed incinerators and
could result in a similar scenario for
municipal solid waste combustors. With
landfills and incinerators being
legislated out of existence, the entire
effort towards integrated solid waste
management could be defeated at great
expense to the economic welfare of the
nation.
Just how significant is a 8 Million
Dollar increase in the operating cost of a
facility such as the Akron Recycle
Energy System. The current annual
operating budget for the facility is
approximately 14 Million Dollars. If the
estimated 8 Million Dollars required to
comply with the new Emissions
Guidelines and possible new Ash
Management Guidance is included, the
new operating budget will be
approximately 22 Million Dollars per
year. When compared with the other
major components of the cost of
operation, the additional cost represents
approximately 37% of the total cost,
second only to the total cost of all labor
and material consumed at the facility on
an annual basis.
With a 14 Million Dollar annual
operating cost, the facility is required to
set its tipping fee at $42 per ton in order
to approach break even. This is
substantially above tipping fees charged
by surrounding landfills, and thus it is
difficult to acquire the amounts of
waste necessary to meet steam demand.
The Akron plant operates as a
utility providing steam "on demand" to
critical businesses and hospitals in the
815
-------
TIPPING FEE DISTRIBUTION
@ $72.00 PER TON
UTIUTJE8 4 FUEL (T7.1SJ
ADMM I, MAN. (8.42%)
OPERATIONS (4&3K)
CLEAN AIR (37.2H)
downtown Akron area and is forced to
burn expensive natural gas when MSW is
not available which defeats the purpose
of the facility and unnecessarily
consumes precious, non-renewal natural
resources. Of the $42/ton tipping fee,
67% of the fee dollar goes to labor and
materials required to operate the
facility.
On an annual basis, the Akron
Recycle Energy System requires
approximately 250,000 tons of municipal
solid waste in order to meet its steam
requirement. The City of Akron
provides only 50% of this requirement.
Once the operating cost has been
increased by 8 Million Dollars, a tipping
fee of $72 per ton will be required in
order to break even.
At $72 per ton, waste haulers who
are not required to use the facility will
have a strong incentive to take their
waste to local landfills, thus more
quickly using up an already rapidly
dwindling waste management resource
and leaving Akron with a shortage of
the required fuel to meet its steam
demand.
The new requirements represent
approximately 37% of the $72 tipping
fee provided that the Guidelines are
enacted as proposed.
Finally, we must consider the
impact upon the citizens of the City of
Akron. The Akron Recycle Energy
System processes 1,000 tons per day of
municipal solid waste. Approximately
500 tons is collected from the City of
Akron's residents. If we distribute a $72
per ton disposal cost to those households
in Akron which are required to use the
facility, it will increase their curb
service fee by approximately 70%.
This represents an increase of $5 per
household per month, or $60 per year.
This agrees with the EPA's projections
of an average increase of $58 per year
per household. This is a local increase
which will affect communities currently
incinerating their solid waste much more
than others not currently incinerating.
816
-------
CURB SERVICE FEE
DOLLARS PER MONTH
DOLLARS
«TO A CLEAN AM
The purpose of the Emissions
Guidelines is to reduce airborne
pollutants which is to the benefit of all
of the citizens of the United States, but
it appears that during the initial years
the heaviest burden of cost will fall
upon those communities which already
operate municipal waste combustors.
Ohio's House Bill 592 required the
establishment of solid waste
management districts and charged those
districts with the responsibility of
establishing a ten-year waste
management plan. The key component
missing from the Emissions Guidelines is
an analysis of its impact upon
comprehensive solid waste management.
817
-------
FLEXIBLE AND ENFORCEABLE
RESOURCE RECOVERY
PERFORMANCE GUARANTEES FOR MASS BURN PROJECTS
Trudy Richter Gasteazoro
Richardson, Richter & Associates, Inc.
Public Projects Advisors
John W. Matton
ABB Resource Recovery Systems
Combustion Engineering, Inc.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
819
-------
ABSTRACT
Resource Recovery Service Agreements typically contain performance
guarantees that require the vendor/operator to process a guaranteed
quantity of waste over a given period of time and to produce a guaranteed
quantity of energy from that waste, based on a specified energy content.
The community/owner, on the other hand, typically guarantees to deliver,
within set time frames, a minimum quantity of municipal solid waste. The
vendor's processing and energy guarantees are conditioned upon the
community meeting its delivery commitment.
In order to establish both parties' guarantees, certain assumptions
normally have to be made about the weekly, monthly and yearly amounts of
waste available to be delivered and its average composition, and therefore,
energy value. The accuracy of these agreed upon assumptions has a direct
effect on the validity and enforceability of these long-term guarantees.
However, communities frequently do not have accurate databases for
establishing these assumption. In addition, the resource recovery industry
recognizes that waste composition, energy value and waste quantity will
change over time. To protect both the vendor and the community during the
typical twenty-year term of a Service Agreement, flexible yet accurate
guarantees are essential.
This paper describes a guarantee structure that gives the community
flexibility when establishing its waste delivery schedule and waste
820
-------
composition by permitting greater variations in waste stream quantity and
energy value without relieving the vendor of its waste processing and
energy production guarantees.
Introduction
A major problem facing most drafters of Resource Recovery Service
Agreements is how to structure a set of performance guarantees that provide
the community/owner with the maximum benefits of high unit availability and
performance while protecting the vendor/operator from wide variations in
waste stream quantity or energy value. Typically, the weekly quantity of
waste in a community will vary by 20% over the course of the year and the
energy value can range from 3800 Btu/lb to 6000 Btu/lb. Communities are,
therefore, faced with the difficult decision of whether to design for
average conditions or peak conditions.
While resulting in some bypassing of waste, a design based on average
daily waste flow and energy value results in the facility operating at
maximum efficiency during the most frequent operating conditions. A
facility design based on peak conditions results in frequent operations at
partial load and inefficient energy generation. If the community decides
to design for peak conditions, it then faces the problem of insuring that
the facility operates as efficiently as possible during periods of low
waste flow or low energy value. If annual performance guarantees are used,
what typically results is either very conservative performance guarantees
821
-------
which do not adequately protect the community against inefficient
operation, or guarantees which are very difficult for the community to
enforce.
Most Resource Recovery Service Agreements attempt to avoid this
problem by assuming that over an extended period of time, such as an
operating year, conditions will average out. In addition, the contracts
generally provide for retesting the facility if the community or the vendor
suspects that these "average conditions" assumptions are no longer valid.
In reality, any failure by the vendor to meet its annual guarantees of
waste throughput and energy, which could possibly result in damages to the
community, may well be unenforceable not only because the community cannot
establish what the energy value of the waste was, but also because the
community may not have consistently met its weekly or monthly delivery
guarantees.
Guarantee interpretation and enforcement problems are particularly
difficult when a community sizes a project to its existing or future waste
processing needs in addition to allowing for the seasonal variation of
waste quantities. For such communities, there is little possibility of
averaging out waste flow and energy value or making up for lost capacity
during peak waste flow periods.
This paper proposes a solution for communities to assure flexible yet
enforceable performance guarantees. To accomplish this, both processing
and energy guarantees are developed and monitored separately in such a way
that the community is assured of efficient operations even during periods
of considerable deviation from the facility design condition.
822
-------
Processing Guarantee
As stated earlier, many Resource Recovery facilities are designed to
process the daily tonnage at some specified heating value. However, the
amount of waste generated in a community, as well as its heating value,
will vary from day to day and from month to month. In addition, allowances
have to be made for scheduled and unscheduled plant maintenance during the
year. There is also a problem in determining the exact amount of waste
that is being processed. It is a simple process to accurately measure the
amount of waste received by a facility, but it is very difficult to
instantaneously measure on a continuous basis how much material is actually
being loaded into the boilers. In most communities the waste profile
cannot be exactly matched by the facility's processing profile, which leads
to either bypassing of waste or under-utilization of the facility. In a
situation where the facility will be under-utilized during portions of the
year, a monthly processing guarantee protects the community better than an
annual guarantee.
It is suggested that the following processing guarantee structure be
used. First, a monthly processing target is established based on the
facility's daily throughput rating and the number of days in the month.
For example, the target for a 1000 ton per day (TPD) plant for the month of
June, would be 30,000 tons. Secondly, using this target, allowances are
made for scheduled and unscheduled maintenance during the month. For
example, for a two boiler plant with an 85% availability guarantee, there
823
-------
would be 2628 boiler-hours (8760 hr/yr x 0.15 x 2) allowed for maintenance
during the year. It is suggested that 30% to 50% (depending on the
operator's normal maintenance procedures) of these hours be allocated to
scheduled maintenance to be agreed upon by the vendor and the community at
the beginning of each operating year to coincide with the expected low
waste flow periods. Once set, the vendor must use scheduled maintenance
hours in a given month or lose them. The remaining maintenance hours are
then available to the operator for use as he deems necessary for
unscheduled maintenance during the year. For a 1000 TPD plant with two
boilers this would result in a maintenance allowance of 20.83 tons for each
hour of boiler downtime.
1000 TPD _^_ 24 hrs. = 20.83 TPH/boiler
"^™"^^^~P •
2
For our example, assume that there were five days of scheduled
maintenance for one boiler during the month and there were three days used
for one bailer for unscheduled maintenance. The monthly processing
guarantee for June would then become:
30,000 - (5 x 24 x 20.83) - (3 x 24 x 20.83) =26,000 tons
Once the vendor uses his allotment for scheduled and unscheduled
maintenance during the year, any outages beyond this do not result in a
reduction in his monthly processing guarantee.
824
-------
To determine if the vendor has met his guarantee, it is recommended
that the plant's truck scales be used to determine the amount of waste
delivered to the plant during the month and how much nonprocessible waste
such as white goods, or unacceptable waste, etc., is bypassed around the
boilers. The quantity of waste in the pit or on the tipping floor is then
estimated at the beginning and the end of each month to determine any
change in pit inventory. Assuming a six day pit storage capacity and a +
10% measurement accuracy on the quantity of waste in the pit, the amount of
waste actually processed during the month can be determined to within + 2%.
Monthly penalties or bonuses can then be assessed based on whether the
vendor has met or exceeded the monthly processing guarantee. Using the
June examples above, if the vendor exceeded its processing commitment of
26,000 tons, it may be entitled to a fee for processing excess waste. In
contrast, by failing to process 26,000 tons, the vendor may be liable for
costs of landfilling waste it should have processed as well as lost energy
revenues or other damages. However, it is recommended, that there be a
yearly reconciliation of these penalties and bonuses based on the yearly
throughput guarantee, i.e., at year end if the vendor has met his yearly
throughput guarantee, then the monthly penalties are rescinded. If the
vendor has not met its yearly throughput guarantee, then any monthly
bonuses would be refunded.
Developing a processing guarantee similar to the one outlined above
solves only half of the community's concern, that of processing a
guaranteed amount of waste and decreasing the community's dependence on
825
-------
limited landfill space. Just as critical to the community is efficient
facility operations, which assures energy revenues at a guaranteed level to
offset the facility's costs.
ENERGY GUARANTEE
Most Resource Recovery operating contracts require the vendor to
guarantee the net energy production capability of the facility. Usually,
both a short-term (acceptance test) guarantee and an annual guarantee are
required. Actual energy production is dependent upon many variables
including waste heating value, boiler load, and operating efficiency.
Energy guarantees are normally made based on a reference waste composition
and heating value; a factor which neither the vendor nor the community can
control. During acceptance testing, the facility can be operated at full
load and careful calculations can be made of the quantity and heating value
of waste processed. Therefore, an accurate comparison of guaranteed and
actual energy production can be made.
An annual energy guarantee based on a reference waste composition is
difficult to enforce because there is no realistic method of measuring
heating value over long periods of time. In addition, the boilers and
turbine will not always operate at full load and therefore, design
efficiency. These variations make any annual energy guarantee very
difficult to monitor and enforce.
826
-------
The primary concern of the community should be that the facility is
operated efficiently at all times, under all conditions of waste flow and
energy value. Efficient operation provides comfort to communities relying
heavily on energy revenues when setting service fees and guaranteeing debt
service payments. If efficient operation can be demonstrated on an ongoing
basis, then the community is assured that the maximum amount of energy is
being extracted from the waste, and the maximum energy revenue is being
generated by the facility.
The best way to determine if the vendor is operating the facility
efficiently is to continuously measure key operating parameters. To verify
energy guarantees, these operating parameters must be equated to energy
production. Before outlining the proposed guarantee structure, a brief
electrical energy production primer is helpful.
When waste is burned in the boilers, heat is absorbed by boiler water
which is then converted into steam. For a specific facility design, the
amount of steam produced is primarily dependent on the heating value of the
waste, the waste feed rate, and boiler cleanliness. The steam is piped to
a turbine-generator where its energy is used to generate electricity. The
amount of electricity produced by the turbine-generator is primarily
dependent on the steam flow and ambient air conditions;
The best measure of whether a boiler is operating efficiently is the
temperature of the flue gas leaving the boiler. If this temperature is
higher than the design point, energy is being wasted. If this temperature
is lower than the design point, the boiler is being operated more
827
-------
efficiently than predicted. The guarantee structure presented uses the
boiler economizer exit gas temperature to determine if the boiler is being
operated efficiently. The net electricity generated per pound of steam is
used to determine if the turbine-generator and auxiliaries are being
operated efficiently.
The proposed performance guarantee structure uses three performance
curves and the monitoring of five operational parameters. The first curve
shows boiler economizer exit gas temperatures as a function of boiler steam
flow. The second curve shows the impact of differential boiler exit gas
temperature on boiler efficiency. The third curve shows net electrical
generation as a function of steam flow and ambient air temperature. To
protect the community, these curves should be made a part of the vendor's
bid proposal and compared to other vendor's curves to insure that they
fairly represent the facility's guaranteed operating performance. The five
parameters which are continuously measured are boiler steam flow, boiler
economizer exit gas temperature, turbine steam flow, ambient air
temperature, and net electrical generation. If the facility uses a wet
cooling tower, humidity must also be measured and incorporated into the net
electrical generation curve.
In order to determine if the facility is producing the guaranteed
electrical output, the following calculation is made hourly by the
facility's computer.
Step 1 - For each of the boilers, use Curve 1 to determine the theoretical
boiler exit gas temperature.
828
-------
Step 2 - -Calculate the boiler exit gas temperature differential by
subtracting theoretical boiler exit gas temperature from the
actual measured boiler exit gas temperature.
Step 3 - Using Curve 2, determine the boiler efficiency adjustment factor
for each boiler.
Step 4 - Calculate an adjusted boiler steam flow by multiplying the actual
boiler steam flows by the associated boiler efficiency adjustment
factors. Sum the adjusted boiler steam flows to calculate an
adjusted turbine steam flow.
Step 5 - Using Curve 3, determine a guaranteed net electrical production
using the adjusted turbine steam flow and the measured ambient
air temperature.
Step 6 - Calculate an electrical production deviation by subtracting the
•actual measured electrical production from the adjusted net
electrical production (Step 5).
If the vendor has produced more energy than guaranteed, the deviation
will be positive. If less energy than guaranteed is produced, the
deviation will be negative. For every hour in the month that energy is
829
-------
produced, the deviations can be summed to calculate a monthly net
electrical production deviation, which represents, in kilowatt-hours, the
excess or shortfall in energy generation.
The following example illustrates how this procedure would work in
practice. As stated earlier, the five operating parameters that are
measured continuously are boiler steam flow, boiler economizer exit gas
temperature, turbine steam flow, ambient air temperature, and net
electrical production.
For our example, assume that there are two boilers and the measured
parameters are as follows:
Boiler 1:
steam flow
exit gas temp.
95,000 Ibs/hr
452°F
Boiler 2:
steam flow
exit gas temp.
75,000 Ibs/hr
434°F
Turbine steam flow
Ambient air temp.
Net electrical production
170,000 Ibs/hr
70°F
14,200 KW
830
-------
Step 1:
From Curve 1, the theoretical boiler economizer exit gas temperatures
are:
Boiler 1 : 442°F
Boiler 2 : 414°F
Step 2:
The boiler exit gas temperature differentials are then:
Boiler 1 : + 10°F
Boiler 2 : + 20°F
Step 3:
Using Curve 2 the boiler efficiency adjustment factors are:
Boiler 1 : 1.005
Boiler 2 : 1.011
831
-------
CURVE 1
4€0
EXTT RUE GAS TEWPERWURE -
in
3
ft
M4
i
UJ
350
55 65 75 85 95
BOILER STEAM FLOW (X 1000 LBS/HR)-W«
105
01
CO
oa
-------
CURVE 2
7EUP. DIFFERENTIAL ADJUSTMENT FACTOR
^ ^ M
}
I i '
i
* t
»
\
• \
i
• •
i
i-
-j--
!
I
t
"\ 1
1J03
1J02
5
*^
I i
CO
CO
00
-tOO -«0 -60 -MO -;
80 100
To(actual) - To(Curve 1) (Degrees)
-------
CURVE 3
GUARANTEE: -
w g
3 S
Lkl
14.
ADJUSTED TURBINE ST&U FTJDW - Wig
( X 1000 LBS/XR)
100-7
00
225
-------
Step 4:
The adjusted boiler steam flows and the adjusted turbine steam flow is
then:
Boiler 1 : 95,000 x 1.005 = 95,475 Ibs/hr
Boiler 2 : 75,000 x 1.011 = 75,825 Ibs/hr
Turbine : 171,300 Ibs/hr
Step 5:
Using Curve 3 with an ambient air temperature of 70°F the guarantee net
electrical production at the adjusted turbine steam flow of 171,300 Ibs/hr
is:
Net electrical production: 14,700 KW
Step 6:
The electrical production deviation for the hour is then:
Net electrical production deviation = 14,200 - 14,700 = - 500 KW
835
-------
The vendor then would be penalized 500 KWH In its energy guarantee for this
hour.
This process is repeated automatically every hour by the facility's
computer and the differentials between the guaranteed net electrical
production and the measured electrical output are summed to compute monthly
and/or yearly bonuses or damages.
Summary
The above set of performance guarantees can be used to provide a
guarantee structure that meets the primary needs of the community of a
contracted quantity of waste being processed efficiently. These guarantees
are clear and easy to administer and enforce. Although no set of
guarantees can be completely rigorous and cover all eventualities, the
approach presented allows for a wide range of plant operations, waste flow,
and energy value while maintaining an acceptable level of validity and
enforceability.
836
-------
IMPLEMENTATION OF GUIDELINES FOR AIR EMISSIONS
FROM EXISTING MUNICIPAL WASTE COMBUSTORS
David F. Painter
U.S. EPA
Presented at the
First U.S. Conference on Municipal Solid
Waste Management
June 13-16,1990
837
-------
Implementation of Guidelines for Air Emissions
from Existing Municipal Waste Combustors
Summary
This presentation provides an overview of proposed guidelines for air
emission limits for existing municipal waste combustors as they were proposed
in the Federal Register (54 FR 52209). The overview is followed by a summary
of public comments on the proposal. The remainder of the presentation covers
the practical aspects of implementing the guidelines. Topics covered include
timetables and assignment of responsibilities during the implementation
process. Also legislative proposals under consideration at the time of the
presentation will be reviewed in the context of how they might impact the
current implementation procedures.
838
-------
MINIMIZATION OF TRACE METAL LEACHINGS IN SEAWATER
FROM STABILIZED MSW INCINERATION ASH
Chih-Shin Shieh
and
Yung-Liung Wei
Department of Chemical and Environmental Engineering
Florida Institute of Technology
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
839
-------
MINIMIZATION OF TRACE METAL LEACHINGS IN SEAWATER
FROM STABILIZED MSW INCINERATION ASH
Chih-Shin Shieh
and
Yung-Liung Wei
Department of Chemical and Environmental Engineering
Florida Institute of Technology
Melbourne, Florida 32901
ABSTRACT
Municipal solid waste (MSW) incineration ash has been
stabilized into a non-friable solid block form which can be
used as construction material in marine environment. Studies
were conducted on full-size (5 cm x 15 cm) blocks and also on
ground samples of stabilized ash blocks to demonstrate that
trace metals are retained inside the stabilized MSW ash block
and that leaching of trace metals from MSW ash is minimized by
the stabilization process. Results show that release of Cu
and Cd from the stabilized ash block is insignificant,
occurring only in the initial three days after the submersion
in seawater. Lead was found to not be released from the
stabilized ash block in seawater. Leaching of Cu, Cd, and Pb
from loose MSW ash was significantly reduced by stabilization
process. Retention of Cu, Cd, and Pb inside the stabilized
MSW ash blocks is due to the combination of physical
enclosement and chemical binding.
84O
-------
INTRODUCTION
Incineration of municipal solid waste (MSW) is currently
the main alternative to landfill disposal of the bulk solid
waste. Incineration of the wastes may generate toxic
substances both in gaseous and solid forms [1-2]. MSW
incineration ash is the solid residue that remains when the
wastes is burned in an incinerator. The ash is enriched in
trace metals and contaminants of environmental concern [3-6].
The physical and chemical properties of incineration ash vary
with source of MSW being burned and operational procedures
used at individual incinerator facilities [7-8]. Incineration
results in a reduction in volume of MSW by about 90 percent
and a reduction in weight by 75 percent. Production of MSW
incineration ash will continue to increase because more MSW
incinerator will be built to solve the problem of managing the
increasing quantities of MSW due to rapid growth. It is
estimated that 19 million tons of ash will be generated in the
U.S. by the year 2000 [9]. Methodologies for ash management
have to be developed, including ash utilization. The
methodologies mu'st be environmentally acceptable to reduce the
burden on an already shrinking land space for landfills.
Reuse of the ashes should be considered. Ash recycling,
if demonstrated environmentally acceptable, represents an
alternative to ash disposal with potential economic and social
benefits. For its safe and beneficial use, ash must be
physically and chemically characterized and the treated ash
841
-------
products must not create damage to the environment and pose no
problem to human health.
Stabilization of the friable ash materials into non-
friable solid forms is one of the potential methods for ash
reuse. For over a decade, studies have been conducted to
demonstrate that the stabilized ash products can be used as
artificial reef materials in the ocean [10]. Wastes applied
using the methodology include coal ash, flue-gas
desulfurization (FGD) sludge [11], oil ash [12], dewatered
sewage sludge [13], and metal processing waste [14]. To
demonstrate the suitability of using the stabilized ash
materials for reef application at sea, studies conducted have
included comprehensive engineering, chemical, and biological
investigations. Generally, laboratory evaluations are first
conducted, followed by a field demonstration and monitoring
before the methodology is adopted for managing ashes.
In this paper, the laboratory evaluation of metal
leaching from both loose and stabilized MSW ash is presented.
The goal of the study was to demonstrate the effectiveness of
stabilization in reducing metal leachings from MSW ash in
seawater. The results are useful for the assessment of the
fate of trace metal in MSW ash after the stabilized ash block
becomes debris at sea.
842
-------
METHODOLOGY
Ash Stabilization
The methodology of ash stabilization has been described
elsewhere [10]. In brief, the process begins with the mixing
of the ashes with water and chemical additives, such as lime
and cement. The mixture is then fabricated into block forms
using conventional concrete block technology. The blocks are
then cured at a constant temperature for a period of time so
that a solid product is produced. From a series of mix
designs, an optimum mix is selected based on the development
of compressive strength and its chemical characteristics.
Factors in determining the effectiveness of stabilization are
ash-additives ratio, particle size distribution of the ashes,
water content of the mix, and curing condition. The
production of an optimum mix is the result of a unique
combination of these factors.
MSW incineration ash used in this study are fly ash,
scrubber ash, and bottom ash. Three types of stabilized ash
blocks were produced, i.e., 100% bottom ash (block B), 70%
bottom ash + 30% scrubber ash (block BS) , and 60% bottom ash +
40% fly ash (block BF). Desirable amounts of cement and water
were added to each type of mix. Lime was only used in the
formation of block BF.
Elemental analysis
Analysis of elemental composition in MSW ash samples was
conducted by analyzing hydrofluoric/boric acid digests of the
843
-------
ashes using the method reported by Silbennan and Fisher [15].
Approximately, 500 g of the starting materials were dried and
ground to fine powder using a porcelain mortar and pestle, and
then oven dried again at 105"C. About 0.5 g samples of the
dried materials were placed into 125-ml Nalgene plastic
bottles followed by the addition of 10 ml of distilled-
deionized water and 10 ml of concentrated hydrofluoric acid.
The samples were shaken mechanically for 24 hr and then 80 ml
of saturated boric acid solution were added. The samples were
again agitated for 24 hours, followed by ultrasonication for
one hour. The digests were filtered through a 0.45 /im
MilliporeR filter paper and then analyzed for major and trace
elements using atomic absorption spectrophotometer (AAS)
equipped with Zeeman background correction.
Seawater Tank Leaching Study
Metal leachings from the stabilized ash blocks into
surrounding seawater was examined following the method used by
Duedall et al. [16]. A solid cylinder of stabilized ash
sample was suspended with monofilament line inside
polyethylene tanks containing 2 liters of filtered seawater.
Each tank was placed on a magnetic stirrer to generate a
constant motion to the seawater. A 0.45.jra membrane filter
was placed over an opening in the cover of the tank to ensure
aeration. The tank water was replaced with fresh seawater
after the initial 3-day period, and then was replaced at two-
week intervals for the remainder of the leaching period. The
844
-------
water samples were taken at the interval of 1, 2, 3, 6, 9 and
12 days in the initial 12-day period, then weekly sampled for
6 weeks and biweekly sampled for 8 weeks. Collected water
samples were filtered through a 0.45 urn MilliporeR filter,
acidified to pH 2 using UltrexR nitric acid, and stored for
later analysis by AAS.
Ash—Seawater Leaching Study
To evaluate the effectiveness of stabilization on
reducing element release from MSW ash exposed to seawater, a
series of leaching experiments were conducted on the loose ash
and ground stabilized ash blocks. The powdered stabilized ash
samples were dried at 105°C and then were passed through a
series of sieves to form different size fractions ranging from
< 250 /zm to > 1000 /im. Samples of each size fraction were
placed in plastic (LPE) bottles containing seawater to form
1:1000 (wt/vol) mixtures; the mixture was placed on the shaker
to allow the reaction to occur at an interval of 0.5, 2, 8,
24, and 48 hrs, respectively. At the end of the leaching
period, the aqueous phase was collected by filtering the
mixture through a 0.45 /am MilliporeR filter. The filtered
solution was then analyzed for selected elements.
Three replicate samples of the study materials were
analyzed. Matrix modifiers, i.e., NH4NO3 and (NH4)2HPO4, were
used for the analysis of Cu, Cd, and Pb in seawater samples.
National Institute of Standard and Technology (NIST) Standard
Reference Material (SRM) 1633a fly ash and NIST SRM
845
-------
Multielement Mix Solutions (3171 and 3172) were analyzed in
order to determine the completeness of digestion of the ashes,
the accuracy of the analytical methods, and to provide quality
assurance of the analysis.
RESULTS AND DISCUSSION
Results of elemental analysis on the ash samples prior to
stabilization are shown in Table 1. These data are considered
average value of the ash used in the study. In general, the
range for elemental variation in MSW incineration ash is very
large due to the nature of the waste stream and operational
conditions in the incinerator. The batch of ash samples
collected is assumed to be well-mixed as a result of sample
collection and of transportation. Data shown in Table 1
indicate that Ca, Si, and Al are enriched in all ash samples,
including fly, scrubber, and bottom ash. These ashes may thus
have pozzolanic characteristics which is a preferred property
for stabilization.
Cadmium, Pb, and Zn were found to be enriched in fly ash
indicating fly ash is the ash of concern environmentally.
Enrichment of Cd in fly ash is expected because Cd is
vaporized by incineration and is recondensed on the fly ash
particles during the cooling of the off-gases [17]. The
distribution of Zn is different from that predicted [17] and
may be due to the operation condition at the incinerator.
846
-------
Table 1. Elemental concentrations in MSW incineration ash
(N = 6) .
Element
Al (%)
Si (%)
Ca (%)
Mg (%)
Fe (%)
Zn (%)
Pb (Mg g"1)
Cu (Mg g )
Ni (Mg g"])
cd (Mg g' )
Cr fixer cr )
Fly Ash
4.6
15
6.8
1.1
1.1
4.2
5500
810
120
380
155
Scrubber Ash
6.5
19
8.6
1.8
3.4
0.4
1200
1100
250
30
403
Bottom Ash
2.8
22
7.'7
0.9
6.8
0.4
1700
2100
160
24
201
Table 2 shows the results of tank leaching studies on
stabilized MSW ash blocks. The detected concentrations in
test solution were less than 5 /ig IT1 for Cu and less than 1
L"1 for Cd. Lead was not detected in the solution. The
results indicate that leaching of Cu, Cd, and Pb from
stabilized MSW ash blocks in seawater is insignificant. The
initial leaching for Cu and Cd occurs at the surface of the
block which is in direct contact with seawater. Previous
studies on stabilized energy waste blocks [18] also showed
that interaction of the stabilized blocks with seawater after
the emplacement at. sea occurred mainly at the surface of the
block.
847
-------
Table 2. Leaching of Cu, Cd, and Pb (/ig L"1)
stabilized MSW ash blocks in seawater.
Stabilized
Time
fdav)
1
2
3
6
9
12
19
CU
3.58
4.08
2.81
n.d.
n.d.2
n.d.
n.d.
B1
Cd
0.24
0.16
n.d.
n.d.
n.d.
n.d.
n.d.
Pb
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
Cu
2.35
1.56
n.d.
n.d.
n.d.
n.d.
n.d.
from
MSW Ash Block
BF1
Cd
0.15
0.42
n.d.
n.d.
n.d.
n.d.
n.d.
Pb
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
Cu
1.21
3.23
1.91
n.d.
n.d.
n.d.
n.d.
BS1
Cd
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
Pb
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
Block B represents 100% bottom ash; BF represents 60%
bottom ash and 40% fly ash; BS represents 70% bottom ash
and 40% scrubber ash.
n.d. represents not detectable.
Detection limit for Cd is 0.1 fig L"1; for Cu is 1 ng L"1;
for Pb is 1 ng L"1.
As mentioned above, application of the stabilized ash
block in marine environment requires a demonstration that the
materials are environmentally acceptable. Data shown in Table
2 indicate that trace metals, such as Cu, Cd, and Pb, are
retained inside the block which has a good physical integrity.
One question may be raised dealing with the fate of these
metals if the block is cracked or turned into debris after
placement into the ocean. Investigation of this concern can
be achieved by examining the release of metals from ground ash
848
-------
blocks. Table 3 shows the percent leaching of Cu, Cd, and Pb
from both the powdered stabilized MSW ash blocks and loose
ash. Without stabilization, Cd was nearly depleted from fly
ash after placement into seawater, while only about 10% of Cd
was released from loose bottom ash after it was in contact
with seawater for 48 hours. Stabilization of the ash by
mixing 60% of bottom ash with 40% of fly ash results in a very
significant reduction in Cd leaching.
Table 3. Percent leaching <%) of Cu, Cd, and Pb from
loose MSW ash and powdered stabilized ash block.
Time
(hr)
0.5
2
8
24
48
Flv Ash
Cd
97
98
83
94
91
Cu
2.9
1.8
2.1
1.6
1.6
Pb
0.39
0.32
0.30
0.25
0.23
Bottom Ash
Cd
2
5
11
13
14
Cu
0.34
0.54
1.06
1..42
1.64
Pb
0.49
0>29
0.34
0.63
0.30
Cd
1.0
1.6
-
2.6
2.7
Block BF
Cu
0.13
n.s.
n.s.
n.s.
n.s.
Pb
n.s.
n.s.
n.s.
n.s.
n.s.
1. Block BF represents the mix containing 60% bottom ash and
40% fly ash.
2. n.s. represents not significant; the value is less than
0.01%.
For Pb and Cu, only small percentage was released from
the ashes into seawater. This is still of concern because
high concentration of Pb and Cu are found in most of MSW
ashes. Stabilization process also significantly minimizes the
leaching of Pb and Cu in seawater.
849
-------
Research conducted is for a worst case, i.e., assuming
the stabilized MSW ash blocks become cracked leading to debris
soon after the emplacement at sea. However cracking is
improbable based on previous engineering investigations which
have shown that stabilized ash blocks made from coal fly ash
and FGD sludge residue have maintained their physical
integrity in the ocean at least 10 years [19].
To understand the mechanism of the stabilization process on
retaining trace metals in the stabilized blocks, studies were
conducted on ground block samples of varying sizes fraction.
The results are shown in Table 4; leaching of Cd increased as
the particle size decreased indicating that physical
enclosement may be the major mechanism for retaining Cd within
the block matrix. Leaching of Cu showed little influence from
particle size indicating that retention of Cu is mainly by
chemical bindings.
Table 4. Leaching of Cu and Cd from ground stabilized ash
block (BS) in seawater.
Particle Size
(um)
< 250
250-500
500-1000
> 1000
Cu
(ua L"1)
6.80±0.14
3.80±1.10
7.87±0.25
9.5012.70
Cd
(ua L~1)
0.47±0.07
0.26±0.12
0.1210.05
0.1410.02
850
-------
CONCLUSIONS
Stabilization has significantly minimized leaching of Cu,
Cd, and Pb from MSW incineration ash. Copper, Cd, and Pb are
retained inside the stabilized MSW ash block. Retention of Cd
is mainly due to physical enclosement while Cu is retained by
chemical bindings. The study indicates that the stabilized
MSW ash block is chemical stable in seawater. Application of
this material in marine environment should be further
considered and investigated.
ACKNOWLEDGMENTS
We thank Dr. Iver W. Duedall for reviewing the paper and
valuable suggestions. We also thank H. Emma Yoo for preparing
digest samples for elemental analysis. This work was funded
by HDR Engineering, Inc.
REFERENCES
1. Neal, H. A. and J. R. Schubel. Solid Waste Management
and the Environment - The Mounting Garbage and Trash
Crisis. Prentice-Hall, Inc., New Jersey, 239 pp., 1987.
2. Frame, G. B. "Air Pollution Control Systems for
Municipal Solid Waste Incinerators", Journal of Air
Pollution Control Association. 38, 1081-1087, 1988.
3. Greenberg, R.R., W.' H. Zoller, and G. E. Gordon.
"Composition and Size Distribution of Particles Released
in Refuse Incineration", Environmental Science and
Technology. 12, 566-573, 1978.
4. Law, S. L. and G. E. Gordon. "Sources of Metals in
Municipal Incinerator Emissions", Environmental Science
and Technology. 13, 432-438.
851
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5. Eraser, J. L. and K. R. Lum. "Availability of Elements
of Environmental Importance in Incinerated Sludge Ash",
Environmental Science and Technology. 17, 52—54, 1983.
6. Denison, R. A. "Municipal Solid Waste Incineration in
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Governmental Refuse Collection and Disposal Association
26th Annual International Solid Waste Exposition. 22-25
August 1988, Baltimore, Maryland, 16 pp. 1988.
7. Sawell, S. E. and T. W. Constable. "The National
Incinerator Testing and Evaluation Program:
Characterization of Residues from a Mass Burning
Incinerator. In: 10th Canadian Waste Management
Conference. Winnipeg, Manitoba, October 1988
8. Stewart S. L. "MSW Incinerator Ash Management", In:
Municipal Solid Waste Technology Conference. San Diego,
California, January 30 - February 1, 1989
9. National Research Council. "Monitoring Particulate
Wastes in the Oceans, The Panel on Particulate Waste in
the Oceans", Marine Board, NRC-NAS: Washington, D.C., pp.
176 -i- appendix. 1988.
10. Shieh, C. S., I. W. Duedall, E. H. Kalajian, and F. J.
Roethel. "Energy Waste Stabilization Technology for Use
in Artificial Reef Construction", In: Emerging
Technologies in Hazardous Waste Management. ACS symposium
series 422, Chapter 19, American Chemical Society,
Washington, D.C., 328-344, 1990.
11. Woodhead, P. M. J., J. H. Parker, and I. W. Duedall.
"The Use of By-Products from Coal Combustion for
Artificial Reef Construction", In: Artificial Reefs.
Marine and Freshwater Applications. F. M. D'ltri (Ed.),
Lewis Publishers, Inc., Chelsea, Michigan, pp. 265-292,
1985.
12. Shieh, C. S., I. W. Duedall, E. H. Kalajian, and J. R.
Wilcox. "Stabilization of Oil Ash for Artificial Reefs:
An Alternative to the Disposal of Oil Ash Waste", The
Environmental Professional. 11, 64-70, 1988.
13. Shieh, C. S. and F. J. Roethel. "Physical and Chemical
Behavior of Stabilized Sewage Sludge Blocks in Seawater",
Environmental Science and Technology. 23, 121-125, 1989.
14. Lechich, A. F. and F. J. Roethel. "Marine Disposal of
Stabilized Metal Processing Waste", Journal Water
Pollution Control Federation. 60, 93-99, 1988.
852
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15. Silberman, D. and G. L. Fisher. "Room Temperature
Dissolution of Coal Fly Ash for Trace Metal Analysis by
Atomic Absorption", Analytical Chemistry. 106, 299-307,
1979.
16. Duedall, I. W., J. S. Buyer, M. G. Heaton, S. A. Oakley,
A. Okubo, R. Dayal, M. Tatro, F. Roethel, R. J. Wilke,
and J. P. Hershey, "Diffusion of Calcium and Sulphate
Ions in Stabilized Coal Wastes", In: Wastes in the Ocean.
Vol. 1, Industrial and Sewage Wastes in the Ocean, I. W.
Duedall, B. H. Ketchum, P. K. Park, and D. R. Kester
(Eds.), Wiley-Interscience, New York, pp. 375-395. 1983.
17. Brenner, P. H. and H. Monch. "The Flux of Metals Through
Municipal Solid Waste Incinerators", Waste Management &
Research. 4, 105-119, 1986.
18. Stabilized Oil Ash Reef Program, Final Report, to be
submitted to Florida Powder and Light, Juno Beach,
Florida, (in preparation).
19. Hans van der Sloot, personal communication; Coal Waste
Artificial Reef Program - a visit after ten years.
853
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PROPOSED AIR POLLUTION EMISSION RULES
FOR MUNICIPAL WASTE COMBUSTION FACILITIES
Walter H. Stevenson and Michael G. Johnston
Emission Standards Division
U. S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
INTRODUCTION
The EPA proposed regulations for municipal waste combustors
(MWC's) on December 20, 1989. The regulations include (1)
performance standards under Section lll(b) of the Clean Air Act
(CAA) for new, modified, or reconstructed MWC's and (2) emission
guidelines for the States to use to develop control requirements
for existing MWC's under Section lll(d).
This paper will summarize the proposed air emission
standards and guidelines, as well as the bases for the prescribed
emission limits. The schedule for the remainder of the
regulations development will also be discussed.
REGULATORY APPROACH
The EPA has chosen to regulate MWC's under Section 111 of
the CAA
(52 FR 25339). The Administrator determined that MWC's would be
regulated under Section 111 because the range of health and
welfare effects and the range and uncertainties of estimated
cancer risks did not warrant listing of MWC emissions as a
hazardous air pollutant under Section 112. Section 112 also
could not be used to address particular constituents of MWC
emissions including lead and hydrogen chloride (HC1). Finally,
the development of emission guidelines under Section lll(d) would
permit a more thorough evaluation of existing MWC's at the State
level than would be possible with a general rulemaking at the
Federal level under Section 112.
The implementation of Section 111 involves several steps
commencing with the selection and characterization of the source
category to be regulated. The source category is characterized
in terms of types, numbers, and sizes of facilities and an
emissions evaluation. The applicability of the standards is
established by defining affected facilities. Under Section 111,
the Agency must then identify the best demonstrated technology
(BDT), which is defined as the best system of continuous emission
reduction that has been adequately demonstrated taking into
account costs and other environmental and energy impacts.
Regulations development under Section 111 also requires the
selection of the pollutants to be regulated from the particular
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source categry. Finally, the EPA must select the format for the
standard and establish the numerical emission limits for the
pollutants which will be regulated.
The proposed MWC standards address air emissions from new
and existing sources. Air emission limits for new sources are
proposed under Section lll(b) for the criteria pollutant nitrogen
oxides (NOX), and a designated pollutant. A designated pollutant
is a pollutant which is not listed as a hazardous air pollutant
under Section 112 of the CAA or is not a criteria pollutant under
Sections 108-110.
The designated pollutant selected for regulation under this
standard is the collection of compounds emitted by MWC's referred
to as "MWC emissions." "MWC emissions" are categorized into
three general subclasses of pollutants: MWC organics, in
particular dioxins and furans; MWC metals, the condensible metals
associated with particulate matter (PM) emissions from MWC's; and
MWC acid gases, specifically sulfur dioxide
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that over 90 percent of new capacity will be attributed to large
facilities, and the dramatic increase in costs associated with
emissions control for new, small facilities.
The proposed NSPS for large, new MWC facilities would
require an emission limit of 5 to 30 ng/dscm for total tetra-
through octa-chlorinated dibenzo-p-dioxins and dibenzofurans for
the control of MWC organics. MWC metals would be controlled by
an emission limit on PM of 0.015 gr/dscf. This level of PM
control would result in greater than 97 percent control of all
MWC metals with the exception of mercury. The level of PM
emissions would be monitored continuously by the use of an
opacity monitor at the stack and a 10 percent opacity limit,
based on a 6-minute average, would apply. MWC acid gases would
be reduced through emission limits for both HC1 and S02-
Emission limits of 95 percent reduction or 25 ppmv for HC1, and
85 percent reduction or 30 ppmv for SO2 are proposed. Compliance
with the HC1 emission limit would be demonstrated using proposed
EPA Method 26 (54 £E 52190). The SO2 emissions would be
continuously monitored.
The emission limits for large facilities are based on the
application of good combustion practices (GCP) and a spray
dryer/fabric filter (SD/FF). In addition to "MWC emissions"
control, large, new combustors would also be limited to 120 to
200 ppm of NOX based on the application of selective non-
catalytic reduction technology. Continuous monitoring of NOy
would also be required.
For small, new MWC facilities, the proposed maximum emission
level of dioxin/furan emissions is 75 ng/dscm. The PM emission
limit is identical to that for large facilities. The level of
acid gas reductions required is 80 percent or 25 ppm for HCl and
50 percent or 30 ppm for SO2- These proposed emission limits are
based on the application of GCP and duct sorbent injection (DSI)
followed by an electrostatic precipitator (ESP) or FF.
Annual emissions testing would be required for all new
MWC's. However, if a small, new MWC is in compliance with the
standards for three consecutive annual tests, the facility may
skip the next two annual tests. If the next test demonstrates
compliance, the facility may again skip the next two years.
Therefore, at a minimum, a small MWC must conduct emissions
testing at least once every three years.
EMISSION GUIDELINES fEGI FOR EXISTING SOURCES
The emission guidelines for "MWC emissions" from existing
MWC sources are proposed pursuant to .Section lll(d). Emission
guidelines and compliance times are described in the proposal and
are to be used by States in developing State regulations for the
control of existing MWC facilities. The intent of the proposed
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guideline is to compel State regulation of MWC's through the
application of the best demonstrated technology.
The proposed emission guidelines for existing facilities are
outlined in Table 2. The guidelines are subdivided into three
subcategories of facilities based on plant capacity: small
facilities, up to 250 tpd; large facilities, between 250 and
2200 tpd; and regional facilities with capacities greater than
2200 tpd.
The proposed guidelines for existing, small facilities would
require the application of good combustion control for the
control of MWC organic emissions and an ESP upgrade for
particulate control for the reduction of MWC metals. Total
tetra- through octa-chlorinated dibenzo-p-dioxin and dibenzo-
furan emissions would be limited to 500 ng/dscm. Particulate
emissions would be limited to 0.03 gr/dscf.
The emission guidelines for existing, large MWC facilities
would require additional control of organic emissions as well as
the control of acid gas emissions. The proposed guidelines would
require the application of GCP and dry sorbent injection into the
furnace or the duct for the control of MWC acid gases followed by
an ESP or FF. Dioxin and furan emissions would be limited to
125 ng/dscm while PM would be limited to 0.03 gr/dscf. MWC acid
gases would be controlled through a 50 percent reduction of both
HC1 and SC>2 or an emission limit of 25 ppmv and 30 ppmv,
respectively.
The proposed guidelines for regional MWC facilities are
based on the application of GCP and a SD/FF. The emission limits
are identical to those discussed above for large, new MWC
facilities except that NOX control would not be required for
existing MWC's.
The proposed emission guidelines in most cases would be
expected to result in compliance with State standards within
3 years of adoption. However, longer compliance times may be
required for those facilities requiring extensive retrofit and
schedule adjustment would be considered.
Annual testing would be required for all existing MWC
facilities. However, if a facility shows compliance with the
emission guidelines for three consecutive annual tests, they will
be permitted to skip the next two annual tests. If they again
demonstrate compliance in the third year following their last
test, they may skip another two years. In any circumstance, each
existing facility will be tested a minimum of once every 3 years.
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MATERIALS SEPARATTQN
The proposed MWC standards would require that all municipal
solid waste (MSW) to undergo preprocessing prior to combustion.
This preprocessing is defined as the removal of 25 percent or
more by weight from the MSW of the following components: paper
and paperboard; ferrous metals; nonferrous metals; glass;
plastics; household batteries; and yard wastes.However, no more
than 10 percent of the total 25 percent can be attributed to the
yard waste component. This materials separation requirement
would apply to all MWC facilities, existing and new. The
proposed standards would also preclude the combustion of lead
acid vehicle batteries and require the removal of household
batteries.
The materials separation requirement may be met by an on-
site mechanical or manual separation program or an off-site
community separation program, or a combination thereof. If an
off-site or community program is implemented to comply with the
requirements, a plan describing the separation program and the
compliance demonstration methods would be submitted to the EPA or
the State agency for approval. Compliance with the proposed
materials separation requirements would be demonstrated based on
the calendar year average of measurements of the total weight of
MSW received, the weight of MSW combusted, and the weight of
materials separated.
Demonstration of compliance with the materials separation
requirement would not be required until the end of the second
full calendar year after initiation of the materials separation
program. A report of the percent materials separation achieved
would be submitted after the first full calendar year of
operation to determine the progress toward meeting the
requirement. However, this report would not be used to determine
compliance. The second and subsequent annual report would be
used to determine compliance.
A new MWC facility must have a separation program in place
at the initial start-up of the facility. However, for new
facilities which commence construction between proposal and
promulgation, a materials separation program would not have to be
implemented until December 31, 1992, or at initial start-up,
whichever is later. Demonstration of compliance with the
materials separation requirement would not be required until
December 1994, or at the end of the second full calendar year
after start-up.
The proposed emission guidelines for existing MWC facilities
would require the implementation of a materials separation
program by December 31, 1992. Recordkeeping and reporting
requirements would be identical to those for new facilities.
Therefore, the first annual report would be due December 31,
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1993. However, this interim report would not be used for
compliance purposes. The initial demonstration of compliance
would occur the following year with the submittal of the
December 31, 1994 report.
Removal of lead-acid vehicle batteries would result in a
reduction of lead emissions from MWC's. Household battery
separation is proposed to effect reductions in mercury emissions
from MWC's. Add-on control systems have proven to be ineffective
in achieving consistently high removals of mercury from MWC flue
gas. Since much of the mercury in MSW is in the form of
batteries, EPA is proposing separation of batteries from the
waste stream as a means of reducing MWC mercury emissions. The
EPA continues to study this issue.
Finally, the proposed materials separation reguirements
include a provision whereby the EPA would grant a facility a
permit to combust separated, combustible materials if no markets
exist for the material. A recycling market would be considered
to be unavailable if, after separating the material and searching
for a market for 120 days, the MWC operator could demonstrate to
EPA that either no recycler will take the material or that-the
cost of recycling is egual to or exceeds the cost of landfilling.
However, the materials separation reguirement would remain in
place even where a combustion permit has been granted. This will
assure stability in the materials separation program. The
combustion permit would be effective for one year, but is
renewable on an annual basis.
COMBUSTIOK CONTROL REQUIREMENT
The proposed MWC standards would establish combustor
operating practices for both existing and new sources. Good
combustion practices (GCP) involve the proper design,
construction, operation, and maintenance of an MWC. The
implementation of GCP would result in a reduction of MWC organic
emissions by promoting their destruction. These practices would
include limits on carbon monoxide (CO), combustor load, and the
flue gas temperature at the control device outlet as outlined in
Table 3.
Techniques employed to minimize CO are similar to those
required for the effective destruction of organics. Therefore, a
CO emission limit is proposed for the various combustor types.
For modular starved air and modular excess air types of MWC's,
the CO emission limit would be 50 ppmv (at 7 percent O2 on a
block 4-hour average basis). For mass burn waterwall, mass burn
refractory, and fluidized-bed types of MWC's, the CO emission
limit would be 100 ppmv (at 7 percent O2 on a block 4-hour
average basis). For mass burn rotary waterwall,
refuse-dervied fuel (RDF), and coal/RDF co-fired MWC's, the CO
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emission limit would be 150 ppmv (at 7 percent O, on a block 4-
hour average basis).
Combustor load also affects MWC organic emissions. At
combustor loads exceeding maximum capacity, the potential for PM
carryover increases and residence times decrease leading to an
increase in organic emissions. Municipal waste combustors would
not be allowed to operate above 100 percent of their maximum
capacity as demonstrated during compliance testing (1-hour
average basis). Municipal waste combustors that do not generate
steam would be exempt from maximum load level requirements
because these types of MWC's cannot feasibly measure load level.
The proposed standards would require all MWC's to maintain a
flue gas temperature of 230*C (450*F) or less (4-hour block
average) at the PM control device inlet. The purpose of this
requirement is to prevent post-combustion formation of dioxins
and furans.
Operator training is considered by EPA to be an integral
part of the implementation of GCP. The proposed GCP would
therefore require American Society of Mechanical Engineers (ASME)
certification of the chief facility operator and shift
supervisors. In addition, a training manual must be developed
for the remaining MWC personnel who occupy positions associated
with the combustion process. The training manual should focus on
the various components of the combustion process and how they
impact performance and emissions. The manual should also specify
remedial measures that are effective during process upsets and
startups and shutdowns.
SCHEDULE
The remaining schedule calls -for promulgation of the new
source performance standards and emission guidelines in December
1990. The States will then be required to develop and submit a
plan implementing the guidelines. Approximately 9 months is
expected to be necessary for State plan submittals. The EPA must
prescribe a plan for a particular State if that State fails to
meet the deadline or submits an unsatisfactory plan. The EPA
will approve State emission standards which meet the emission
guidelines through the application of the best systems of
continuous emission reduction which are reasonable available.
For health-related pollutants, as is the case for "MWC
emissions". State emission standards must ordinarily be at least
as stringent as the emission guidelines. However, where
justified due to the unreasonableness of application, relief may
be granted on a case-by-case basis.
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TABLE 1. MHC EMISSION LIMITS FOR
NEW FACILITIES3
Plant Capacity, tpd
MWC Metals, gr/dscf (as PM)
MHC Organ ics, ng/Nm3 (as CDD/CDF)
MWC Acid Gases
HC1, % Reduction0
S02, % Reduction01
NOX, ppmv
NEW
<250
0.015
75
(250)D
80
50
none
FACILITIES
>250
0.015
5-30
95
85
120-200
a Corrected to 7% 02
b Value indicated for RDF facilities
c Indicated percent reduction or less than 25 ppmv.
" Indicated percent reduction or less than 30 ppmv.
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TABLE 2. MWC EMISSION GUIDELINES FOR
EXISTING FACILITIES9
Plant Capacity, tpd
MWC Metals, gr/dscf (as PM)
MWC Organics, ng/Nm3 (as CDD/CDF)
MWC Acid Gases
HC1, % Red.c
S02, % Red.d
NOX, ppmv
EXISTING FACILITIES
<250
0.030
500 ,
(1000)*
>250 to 2200 >2200
0.030
125
(250)t
0.015
5-30
none
none
none
50
50
none
95
85
none
a Corrected to 7% 02.
b Value indicated for RDF facilities.
c Indicated percent reduction or less than 25ppmv.
Indicated percent reduction or less than 30 ppmv.
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TABLE 3. GOOD COMBUSTION PRACTICES
LIMITS
POLLUTANT OR PARAMETER
LIMIT
MAXIMUM LOAD LEVEL
MAXIMUM TEMPERATURE AT PM
CONTROL DEVICE INLET
100% OF DEMONSTRATED CAPACITY
230'C (450*F)
CO Emissions:
Modular MWCs
Mass burn waterwall
Mass burn refractory
Fluidized bed combustor
Mass burn rotary water wall
RDF spreader stoker
Coal/RDF co-fired
50 ppmv
100 ppmv
100 ppmv
100 ppmv
150 ppmv
150 ppmv
150 ppmv
OPERATOR CERTIFICATION AND
TRAINING
ALL OPERATORS CERTIFIED BY ASME;
TRAINING MANUAL AND TRAINING FOR
OTHER PERSONNEL
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SALES OF ELECTRIC POWER USING MUNICIPAL SOLID WASTE
Freddi L. Greenberg*
Attorney at Law
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13 - 16, 1990
*Freddi L. Greenberg is an attorney who practices in the area of
energy and public utility law. She has represented clients in
connection with regulatory and contract matters concerning
electric generating projects in 15 states. Ms. Greenberg
maintains offices in Evanston and Chicago, Illinois.
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SALES OF ELECTRIC POWER USING MUNICIPAL SOLID WASTE
FREDDI L. GREENBERG
ATTORNEY AT LAW
Introduction
My topic today is "Sales of Electric Power Using Municipal
Solid Waste." I have divided the topic into four parts.
First, I will discuss the current state of non-utility
generation in the United States. Then I will turn to state and
federal regulatory issues which you should be aware of in
connection with electric generating projects. Third, I'll
mention some of the more important contract issues you will see
in your negotiations with utilities. I'll close with a couple
of practical suggestions to keep in mind when you are
developing a project. I will use the term municipal solid
waste, or "MSW", to refer to both landfill gas and municipal
solid waste.
Overview of Power Sales Opportunities
Let's begin by looking at where we are today compared to
where we were five or ten years ago. One of the most important
changes in the electric utility industry during the last ten
years has been the development of an active and growing
independent power industry. A primary reason for this change
is that Congress passed the Public Utility Regulatory Policies
Act or ("PURPA") in 1978. PURPA requires utilities to purchase
electricity from non-utility generating facilities using
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certain technologies. These include facilities fueled by MSW
and are known as "qualifying facilities" or "QF's".
During the early and middle 1980's most utilities
purchased power from qualifying facilities and other non-
utility generators with great reluctance. This was because
utilities preferred to build their own generating plants so
those plants would be included in rate base. Utilities also
questioned the reliability of non-utility generation.
Today many utilities are actively seeking bids for
generating capacity — from qualifying facilities and from non-
utility generators which do not qualify under PURPA and which
cannot force utilities to buy their power. This is because, in
recent years, many utilities have had difficulty including the
cost of their own generating plants in rate base. They may
have had cost overruns or they may have found that they did not
need all of their new capacity once it was built. In these
cases, utility shareholders, rather than ratepayers, have had
to bear all or part of the cost of a new plant. As a result,
utilities are more reluctant than before to bear, the risks of
building new capacity.
At the same time, non-utility generation has been around
for a while and has been proven to be reliable. Utilities who
have dealt with these generators have acknowledged their
reliability in situations such as last year's San Francisco
earthquake. For these reasons, I think you will find that
utilities which need new generating capacity are increasingly
867
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willing to buy your power. In addition, many economists
suggest that electric utilities in the United States have
underforecast load growth during the '90's, so opportunities to
sell capacity to utilities may increase during the next several
years.
There is another side to this story which you should also
be aware of. Regulatory and economic barriers which
discouraged non-utility generation which did not qualify under
PURPA have been reduced. As a result, there is interest in
this area by large developers, including non-regulated utility
subsidiaries. Generally the projects are increasing in size,
with capacities as high as several hundred megawatts.
As I mentioned, utilities are turning to competitive
bidding when they need new capacity. What this means to you is
that there will be more competition when you try to sell
capacity to a utility and that your larger competitors may have
a price advantage due to the economies of scale. In spite of
this competition, I am optimistic about the future of
generating projects fueled by MSW for three reasons.
First, a project like yours may be ideal where a utility
is of the old school and has not wanted to deal with qualifying
facilities, despite the legal obligation to do so. Your
projects typically will be small enough so they will not be
viewed as threats to the utility's rate base. The utility may
be happy to sign a contract with you, so it can point to your
contract when larger developers complain that the utility is
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discouraging the development of QF's.
Second, the national concern about the environment and
waste disposal has led some states to pass laws which encourage
non-utility generation fueled by landfill gas and MSW. Two of
those states are Illinois and Michigan. In Illinois the
standard rate available to a qualifying facility is less than 2
cents/kwh. Where the qualifying facility is fueled by MSW,
Illinois law requires that the utility purchase power at a rate
equal to the rate paid to that utility by the city or county
where the facility is located. (Such facilities must be
qualifying facilities under PURPA and must be certified by the
Illinois Commerce Commission.) This can be as high as 6 or 7
cents a kilowatt hour. The utility receives a tax credit for
the difference between the two rates. The generating facility
must repay the difference between the two rates to the state
after it has been in operation for ten or twenty yea'rs,
depending upon the type of project. The end result is an
interest-free loan which enhances the project's cash flow in
the early years.
Michigan has taken a slightly different approach. Under
the Michigan law, utilities must pay the highest legal rate for
energy and capacity purchased from MSW facilities even if the
utility goes out for bids and is able to purchase capacity from
other sources at a lower rate. In both states, purchases from
MSW facilities are not counted in determining whether a utility
has exceeded its permitted capacity reserve margins.
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The third reason I am optimistic about MSW fueled
generation is that utilities do not want to be overly dependent
on generation which burns a single type of fuel. They seek
fuel diversity in order to limit the impact of outages due to
interruptions in fuel supply. Landfill gas and MSW enhance
utility fuel diversity. For example, if a utility is heavily
dependent on natural gas, your projects will be attractive
because, unlike natural gas, your fuel supply will not be
affected by outages or curtailments of transporting pipelines.
This advantage is significant because, if you bid to sell
capacity to a utility, most of your competitors will be
projects fueled by natural gas.
In evaluating a seller's fuel supply when it buys
generating capacity, a utility also will want to see a firm
fuel contract for the term of the power sale contract. Here
again, your projects have the edge over natural gas in the
current gas market. This is because, at the present time, it
is almost impossible to sign a contract for a firm, long term
supply of natural gas at a reasonable price. In contrast, it
is generally possible to line up a supply of MSW on a firm
basis. Your ability to present a strong fuel supply contract
will help sell your project to a utility.
Federal Regulatory Issues
Now that I have given you a look at where we are today, I
want to turn to some of the state and federal regulatory issues
you will face in connection with your generating facility. As
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I mentioned earlier, PURPA requires that utilities purchase
electricity generated by qualifying facilities which burn MSW.
Under PURPA, a qualifying facility is entitled to received a
rate equal to the purchasing utility's avoided cost. The
avoided cost is the cost to the utility if it had generated the
same amount of power itself instead of buying it from the
qualifying facility. If the utility needs additional
generating capacity, the avoided cost must include a component
to compensate the qualifying facility for the fact that the
power purchase has allowed the utility to avoid or to defer
building new capacity. The actual method of calculating
avoided cost is determined at the state level and will vary
from one utility to another.
Besides a guaranteed market for their power, there are
three other important benefits available to facilities which
qualify under PURPA. First, qualifying facilities and their
parent companies are exempt from regulation by the Securities
and Exchange Commission under the Public Utility Holding
Companies Act. Second, utilities are required to provide
backup power to qualifying facilities at cost-based, non-
discriminatory rates. Backup power is the catch-all term for
any power the qualifying facility is unable to supply for its
own use. With an MSW project, you are most likely to need
utility service for startup after an outage. Third, PURPA
exempts most qualifying facilities from regulation as utilities
at the state and federal levels. Facilities larger than 30
871
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megawatts are subject to regulation by the Federal Energy
Regulatory Commission (FERC) and must make certain filings
before commencing operation.
The benefits of PURPA are available to MSW fueled
facilities which meet the following three criteria:
1. First, the generating facility must have a generating
capacity no greater than 80 megawatts. This should
include most MSW fueled facilities.
2. Second, a utility may not own more than a 50 percent
equity interest in the facility; and
3. Third, the facility must be fueled primarily by MSW.
This means that use of natural gas or other fossil fuels
cannot exceed 25 percent of the total energy input in a
calendar year. More importantly, fossil fuels can be used only
for certain purposes specified in PURPA or otherwise permitted
by the FERC, the federal agency which administers PURPA. You
cannot simply oversize your facility in relation to your
projected supply of fuel and burn fossil fuel 25 percent of the
time, unless your usage falls within the permitted uses.
Once you know that your facility meets these criteria, the next
step is to qualify the facility with the FERC. This can be
done in one of two ways. First, the owner or operator of the
facility can self-certify by filing a Notice of Qualifying
Status with the FERC. The second alternative is to ask the
FERC to issue an order certifying that the facility qualifies
under PURPA. From a legal standpoint, both approaches achieve
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the sane result, although there may be practical reasons to
seek an FERC order instead of self-certifying.
Besides defining qualifying facilities, the FERC rules
address various other aspects of PURPA. For example, the rules
define those times when, for operational reasons, a utility is
not required to purchase power from a qualifying facility. I
will not discuss those rules here other than to say that you
should become familiar with them.
Non-utility generating facilities which do not qualify
under PURPA are commonly known as independent power producers
or "IPPs". If your facility is an IPP, you will have
/
opportunities to respond to bids for capacity by some
utilities, although utilities are not required to buy your
power. You will have to seek certain authorizations and
waivers from the FERC, and the Public Utility Holding Companies
Act may affect the ownership structure of your project. The
regulatory climate is becoming increasingly favorable to IPPs,
so inability to qualify under PURPA should not necessarily
deter you from developing a project.
State Regulatory Issues
Now I'm going to turn to the state regulatory scene.
Because the FERC regulations are implemented at the state
level, you will have to look to your state public utility
commission after you qualify your facility with the FERC, if
you plan to sell power to an investor-owned utility. For
municipal utilities, the situation varies by state. - Often
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there is no state regulation, so you will have to look to the
FERC if you want to enforce your rights under PURPA.
As you have seen, the basic issues of who qualifies under
PURPA and the benefits available under PURPA are federal
questions. State public utility commissions administer PURPA
insofar as rates paid to qualifying facilities, rates utilities
may charge for backup power, utility interconnection charges,
and most other aspects of the relationship between the utility
and the qualifying facility. All of these items must meet the
standards set out in the federal rules, but you will find that
each state has its own interpretation of those rules. For that
reason, it is essential that you become familiar with the PURPA
rules of your state commission before you approach a utility
about buying your power.
As you know, a utility is required to pay a rate for your
power which is equal to its avoided cost. That rate will
either be set or approved by the state commission. Typically,
the rate will include an energy payment for each kilowatt hour
of electricity delivered. The energy payment generally
reflects the utility's costs for fuel and for operating and
maintenance expenses. The capacity component also may be paid
on a kilowatt hour basis. More commonly, however, the capacity
component is a monthly payment per kilowatt of capacity.
During the last several years, utility avoided costs have
decreased in most areas of the country. One major exception is
the northeast, where utilities need generating capacity. Where
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we saw avoided costs as high as eight or ten cents/kilowatt
hour six or eight years ago, many people consider four cents an
attractive rate today. Where utilities do not need capacity,
avoided costs may be 2 cents or less, which can make it very
difficult to support a project, unless the state has passed
legislation similar to the Illinois law I mentioned earlier.
You will find that many utilities have a tariff in place
which includes a standard rate to be paid for purchases of
energy (and sometimes capacity) from qualifying facilities.
However, you should keep in mind that you are not limited to
the tariff rate. Instead of the tariff, you may negotiate a
rate with the utility for the purchase of your power. This
rate must reflect the utility's avoided cost over the life of
your contract, as it exists when the power is sold, or as
projected when the contract is signed. There are many ways to
design such a rate. For this reason, you may want to use the
services of a rate consultant to be sure that any non-tariff
rate you propose is designed in a way which is acceptable to
the state commission.
Besides setting the power purchase rate, the state
commission sets the rate which you pay to buy backup power from
the utility. This rate can be significant because it can
include a demand component which you must pay every month
whether or not you use backup power that month. The demand
component may be based on your maximum usage of power during
the year. Here as with avoided cost, you may be able to
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propose a negotiated rate, subject to approval of the state
commission.
There are also several indirect ways in which the state
commission will affect your project. The commission's
determinations of utility need for generating capacity, type of
new capacity, and timing of capacity additions all impact your
ability to sell power to utilities regulated by the Commission.
In addition, the state public utility commission may prescribe
standard contracts for power purchases by utilities. State
commissions also may adopt generic rules which will affect your
project.
In each of these situations you can intervene before the
commission, individually or as part of a group with similar
interests. Whether or not you decide to invest the time and
money to fully participate in a commission proceeding, your
very presence as an intervenor will remind the commission, and
its staff, that there are interests to consider other than
utility interests.
Your state commission also can be helpful if you reach an
impasse in negotiating with the utility, either before or after
a contract is signed. In most states you can reguest that the
commission resolve your dispute with the utility. Sometimes
commission staff will mediate a dispute and you can reach a
reasonable settlement without filing a formal complaint.
As I mentioned, many utilities are turning to competitive
bidding if they need capacity. This is because they generally
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have offers to buy more capacity than they need. At the
present time, there is a trend toward greater consideration of
non-price factors in selecting a winning bid. Here, fuel
diversity and environmental concerns may favor MSW projects.
Some bidding schemes may include a set-aside which provides
that a certain block of capacity must be purchased from
generating facilities burning fuels such as MSW.
Bidding schemes are generally approved by the state
commission. A bidding scheme may be proposed by a utility or
may grow out of a generic rulemaking. As a participant in this
process, you will have yet another opportunity to develop a
s
climate in your state which is favorable to MSW projects.
Contract Issues
Now I am going to turn from the regulatory arena to your
power sale contract with the utility. I want to mention some
of the major contract terms which you should be aware of in
your negotiations.
I have already discussed avoided cost and backup power
rates so I won't mention them again here. Some other contract
provisions which will have a strong impact on the economics of
your project include these five:
1. "Regulatory out" clauses,
2. Dispatchability reguirements,
3. Cost of interconnection facilities,
4. Cost of upgrades on the utility's system, and
5. Performance standards.
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First, a "regulatory out" clause is a contract provision
which allows the utility to reduce its payments to you or to
seek a refund of past payments if it cannot pass those payments
on to its customers. Utilities often want the right to use
this "regulatory out" at any time during the contract term.
The risk of having this provision in a contract can be reduced
if you request that your state commission approve the utility's
passthrough of its payments to you for the life of the
contract, before the contract term begins. Whether or not you
achieve this goal, you may want the right to terminate the
contract rather than receive a lower rate for the remainder of
the contract term.
Second, a utility may require the ability to dispatch your
plant. That means the utility can tell you to shut your plant
down in certain situations. Sometimes the utility will want
the ability to automatically back off your generation by
computer. In negotiating this provision, you will want to
specify those times when you will be reguired to shut down,
including a maximum number of hours each year. You should not
be required to back off your generation where the utility
would not back off its own plant of equivalent size and type.
Even if you are asked to back off your generation, you should
continue to receive capacity payments. You will probably end
up losing the energy payments in such cases.
The third and fourth contract terms are at issue because
PURPA requires that you pay for additional equipment and
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facilities required by the utility to enable the utility to
receive your power. This includes interconnection facilities
which are required so that you may begin delivering power to
the utility. You may also be asked to bear the cost of
upgrades required by the utility at the interconnection or on
its transmission system during the term of your contract.
In both cases, it is important that your contract specify
your maximum financial obligation for each of these items.
Otherwise you will have signed a blank check for the utility to
cash. With regard to upgrades, you may also want the right to
terminate the contract rather than incur substantial cost
/
toward the end of the contract term. You should also require
that the utility provide a detailed explanation of its actual
costs for interconnection facilities and subsequent upgrades.
Fifth and last, if you are selling capacity to a utility,
the utility will specify a level at which you must generate.
For example, you may be required to generate at 75 percent of
nameplate capacity on an annual basis. This is called a
capacity factor. If you do not meet this level of performance,
your capacity payments will be reduced. In setting the
capacity factor, you must be realistic as to how well your
plant can perform. You should also be sure that your plant is
not expected to perform any better than an equivalent utility-
owned plant.
Conclusion
In the remaining few minutes, I want to offer a couple of
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practical suggestions which may be of help to you. First, I
want to stress the opportunities for input into actions by your
state legislature and your state public utility commission.
They have to be educated about the value of MSW fueled
generation. Many experts believe that one half of the
generating capacity needed in this country by the year 2000
will be supplied by non-utility operators. This will create a
window of opportunity for you, particularly if your industry
joins together to market MSW fueled generating projects.
Second, it is important that you keep up on regulatory
developments in this area. These developments may suggest a
new approach which you had not considered in connection with
your project. For example, the FERC has recently issued
several orders which permit qualifying facilities to own
electric transmission and interconnection facilities. There
are two situations where you may want to own these facilities.
The first is where a utility quotes a prohibitive charge for
interconnection facilities. You may be able to construct some
of those facilities at a lower cost. In the second situation,
you may find that a neighboring utility will pay more for your
power than your local utility. Your local utility may not
agree to wheel or transmit your power to the second utility.
In that situation, you should consider building a line to
deliver your own power to the second utility.
If utility rates won't support your project, consider
selling your power directly to a large consumer. You may risk
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becoming subject to regulation at the state level, but there
may be ways to minimize that risk. In this situation, consider
involving the purchaser in your facility's ownership or seeking
an order exempting your project from state regulation. The key
is to be aware of all your options as the environment changes
and to think creatively.
That concludes my prepared remarks. Thank you for your
attention. I will be happy to answer any questions you may
have.
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THE UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
MUNICIPAL WASTE COMBUSTION RESIDUE
SOLIDIFICATION/STABILIZATION EVALUATION PROGRAM
Carlton C. Wiles
Risk Reduction Engineering Laboratory
United States Environmental Protection Agency
Cincinnati, Ohio 45268
David S. Kosson
Rutgers, The State University of New Jersey
Piscataway, New Jersey
Teresa Holmes
United States Army Corps of Engineers
Waterways Experiment Station
Vicksburg, Mississippi
Presented at the
First United States Conference on Municipal Solid Waste Management
June 13-16, 1990
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THE UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
MUNICIPAL WASTE COMBUSTION RESIDUE
SOLIDIFICATION/STABILIZATION PROGRAM
ABSTRACT
Vendors of solidification/stabilization (S/S) and other technologies are
cooperating with the U.S. Environmental Protection Agency's (U.S. EPA's)
Office of Research and Development (ORD), Risk Reduction Engineering
Laboratory to demonstrate and evaluate the performance of the technologies to
treat residues from the combustion of municipal solid waste (MSW).
Solidification/stabilization is being emphasized in the current program. This
technology may enhance the environmental performance of the residues when
disposed in the land, when used as road bed aggregate, as building blocks, and
in the marine environment as reefs or shore erosion control barriers.
The program includes four S/S process types: cement, silicate, cement kiln
dust and a phosphate based process. Residue types being evaluated are fly
ash, bottom ash and combined residues. An array of chemical leaching tests and
physical tests are being conducted to characterize the untreated and treated
residues.
The S/S evaluation program is the first part of ORD's Municipal Solid
Waste Innovative Technology Evaluation (MITE) program.
INTRODUCTION
During the past two years there has been a significant concern expressed
about the management of the residues from the combustion of municipal solid
waste. Much of this concern has centered on the fact that when the residues
are subjected to the Extraction Procedure for Toxicity (EP tox) and the
Toxicity Characteristics Leaching Procedure (TCLP) they will fail for lead and
cadmium a significant portion of the time. This occurs more often for the fly
ash, less for the combined fly ash and bottom ash, and least often for the
bottom ash alone. Because of this, a controversy exists as to whether or not
the residues should be considered and regulated as a hazardous waste or
exempted because they originated from burning municipal solid waste. Several
states are requiring that these residues be disposed into landfills with
designs and operating procedures as, or more, stringent than those for
hazardous waste. Municipal Waste Combustion (MWC) ash characteristics are
extremely variable as is the leachate-from these ashes. Ranges of metal
concentrations observed in bottom and fly ashes from many sources are
presented in Table p1'. Detailed descriptions of the chemical and physical
characteristics of MWC residues are available^'-*'^'-' L
Because of the growing concern about the residues and anticipating the
need for appropriate treatment techniques, the Office of Research and
Development designed and implemented a program to evaluate the use of
solidification/stabilization technologies for treating the residues. The
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program was formally announced on September 19, 1989. Originally known as the
U.S. EPA MWC Ash Solidification/Stabilization Evaluation Program, it is now
the Municipal Innovative Technology Evaluation program (MITE). This paper
presents the design and status of the current program.
THE MITE PROGRAM
The MITE program is an Office of Research and Development (ORD) program
designed to conduct demonstrations of technologies for managing municipal
solid waste. The objective is to encourage development and use of innovative
technology for municipal solid waste management. The program is patterned
after the Superfund Innovative Technology Evaluation program (SITE). It is,
therefore, a cooperative program in which the technology developer and/or
vendor pays the cost of conducting the demonstration. U.S. EPA pays the cost
of testing and evaluation, including analytical cost. U.S. EPA will report
the results of the evaluations in an unbiased manner, thus providing a means
for assisting municipalities and others to better evaluate and select
technologies more appropriate for their given situation.
The current program is demonstrating and evaluating alternatives for the
treatment of residues from the combustion of municipal waste. While it is
uncertain if treatment will be required prior to disposal, it is most likely
that treatment will be necessary for any utilization option. Solidification/-
Stabilization (S/S) technology was selected for initial evaluations !;3sed upon
experience and knowledge of the technology for treating hazardous waste and
experimental studies on solidifying municipal waste combustion (MWC)
residues^6'. Solidification/Stabilization (S/S), in general terms, is a
technology where one uses additives or processes to transform a waste into a
more manageable form or less toxic form by physically and/or chemically
immobilizing the waste constituents. Most commonly used additives include
combinations of hydraulic cements, lime, pozzalons, gypsum, silicates and
similar materials. Other types of binders, such as epoxies, polyesters,
asphalts, etc. have also been used, but not routinely. More detailed
descriptions of S/S technology are available* '. The program objective is to
provide a credrble data base on the effectiveness of S/S technology for
treating the residues.
Preliminary design of this program was completed by the U.S. EPA. Because
U.S. EPA believed it important to have results completely unbiased and as
scientifically credible as possible, a panel of international experts was
assembled to provide oversight to the program. This Technical Advisory Panel
(TAP) consists of experts from academva, industry, state and federal
governments, and environmental groups.
PROGRAM ORGANIZATION AND DESIGN
Organization - The program involves the participation of several different
organizations with separate roles. The Risk Reduction Engineering Laboratory
(RREL) is managing and directing the program. The TAP is providing valuable
peer review, oversight and technical design. This service is donated. Staff
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at the U.S. Army Corps of Engineers Waterways Experiment Station (WES) are
coordinating and observing the demonstrations at WES facilities located in
Vicksburgh, Mississippi. WES is also responsible for performing the physical
testing and some of the extraction/leaching tests. A Versar laboratory
experienced in MWC residue analysis is performing the majority of the
analytical work. Specialized analyses, testing and modeling is being
performed by the University of Illinois and the Netherlands Energy Research
Center. Rutgers University in conjunction with the Mew Jersey Institute of
Technology is assisting in the coordination of the various activities and
participants. Vendors are participating by providing valuable time and money.
Tests and Analyses - The program was conceived by U.S. EPA and the basic
design was based on the testing and evaluations performed on hazardous and
other waste treated by solidification/stabilization technologies in various
research and evaluation programs of U.S. EPA. At the request of U.S. EPA, the
TAP reviewed and modified this preliminary design. The tests and analytical
protocols included in the program are provided in Tables 2, 3, 4, 5, 6 and 7.
The purpose for conducting the test and analysis listed is also included.
Methods listed in the Tables are either approved U.S. EPA or ASTM methods.
Ash Types Tested - Residue selected for testing was limited to that
collected from a modern state-of-art waste to energy facility (i.e., high burn
out, lime scrubber with fabric filter, etc.). There were several reasons for
limiting the number of residues included in the program. The prime objective
is to evaluate solidification/stabilization for treating the residues, rather
than determine how characteristics of different residues may affect the
performance of the technology. In addition the apparent variability of MWC
residues is becoming less of an issue, especially with the newer combustion
facilities. Proper sampling and analysis, changes in air pollution controls
and similar factors will play more important roles in the variability of
residues. The program currently includes four different S/S process types
plus one control. Because of the extensive list of tests being performed, the
analytical cost for the program is the major U.S. EPA expense. For each
additional source of residue added these costs must be duplicated. This would
have reduced the number of processes which could be evaluated to an
unacceptable number. The program is also developing and evaluating testing
protocols that can be used to evaluate selected S/S processes on different
residues if required in the future.
These considerations quickly led to the conclusion that the program would
test the residue from only one facility. The residue types are the fly ash
(including the scrubber residue), the'bottom ash and the combined ash. The
MWC facility samples has the following process sequence: (i).primary
combustor with vibratory grates, (ii) secondary combustion chamber, (iii)
boiler and economizer (iv) dry scrubber with lime, and (v) particulate
recovery using baghouses (fabric filters). Bottom ash sampled was quenched
after exiting from the combustion grates. Fly ash sampled was mixed residuals
from the scrubber and baghouses. The fly ash was screened to pass a 0.5 inch
square mesh. The bottom ash and combined ash were screened to pass a 2 inch
square mesh at the MWC facility. Materials not passing through the 2 inch
886
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mesh were rejected. After shipment to the WES, each ash type was dried to
less than 10% moisture, crushed and screened to pass a 0.5 inch mesh
(nominally 3/8 inch after clogging), and homogenized.
Processes Selected - Process types selected in the program are cement
based, silicate based, cement kiln dust and phosphate based. A non-vendor
cement process is being performed by experienced staff of WES and U.S. EPA in
Vicksburg, MS.
Process selection was competitive based upon evaluation of proposals
submitted by parties interested in participating. A formal Request For
Participation was issued by U.S. EPA which provided information required
to respond. Under direction of U.S. EPA, the TAP developed evaluation
criteria which was used to make final selections.
Twenty-one responses were received and evaluated. The responses were
.divided into 11 S/S processes, 6 vitrification processes and 4 other
miscellaneous processes. Rased upon the evaluation criteria, the S/S process
proposals were judged to be superior. In order not to select similar S/S
process types {e.g., two cement based) with the limited resources available,
the decision was made to select the best proposal out of the different types
available. The vitrification process proposals were generally incomplete and
failed to address some major issues. This, in conjunction with the potential
high quantities of residues required for most of these processes, resulted in
the decision not to select one for evaluation. Alternatives for evaluating
vitrification processes are being pursued. Proposals in the other
miscellaneous category were not acceptable and were rejected.
During the request for participation, evaluation and selection process,
provisions were made for maintaining confidentiality of information so marked
by the responders.
Following is a brief description of each of the processes selected.
Cement Based Process - This process involves the addition of polymeric
adsorbents to a slurry of MWC ash prior to the addition of Portland cement.
The final product is soil-like rather than monolithic.
Silicate based process - This is a patented process using soluble
silicates as an additive with cement. The additives are used to promote
several types of reactions with the polyvalent metal present to produce
insoluble metal compounds, gel structures, and promote hydrolysis, hydration
and neutralization reactions. The process immobilizes heavy metals through
reactions involving complex silicates. The final product is clay-like
material.
*
CKD process - This is a patented process involving mixing the MWC ashes
with quality controlled waste pozzolans and water. Good quality control on
the reagents is required because they are secondary materials derived from
processing other materials. Therefore, the pozzolanic characteristics
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critical to the process are subject to change. The finished product is
similar to moist soil, but hardens to a concrete-like mass within several
days.
Phosphate process - A water soluble phosphate is used in this patented
process to convert lead and cadmium to insoluble forms. The process is
designed such that fly ash is mixed with lime, then this material can be mixed
with the bottom ash and the mixture treated with a source of water soluble
phosphate. The process does not alter the physical state of the ash.
DEMONSTRATIONS
Process - The procedures for conducting the demonstrations were
established so that the process vendors could review data from
characterizations of the various ash prior to the demonstration. Samples of
the ashes were also furnished to the vendors so that they have the opportunity
to pretest their process prior to the demonstration. This permitted them to
make modifications if desired. Vendors were responsible for providing any
specialized equipment or ingredients required. Each agreed to permit
observation by U.S. EPA selected observers if it was necessary to conduct the
demonstration at the vendor's facilities. Otherwise the demonstrations were
to be conducted at a U.S. EPA selected facility and observed by U.S. EPA
designated staff.
During the process demonstration, each vendor was requested to carry out
three replicate batches for each ash type. A total of between 50 and 100
gallons of each ash type is being treated for each process. Numerous molds
and samples are prepared from these batches. All molds and sample containers
are provided by WES and U.S. EPA. Each vendor provides enough process
additives for analysis and archiving. Most equipment and laboratory
facilities required for the demonstrations are provided by WES.
Scale - The processes are being demonstrated at bench scale. Reasons for
this include the technologies being tested, resources required for full scale
demonstrations and the desire to include as many different processes as
possible within available resources. The program plan was to conduct a full
scale field demonstration of a selected process if deemed necessary. Because
of the nature of S/S technologies, U.S. EPA and the TAP believed that bench
scale demonstrations were adequate to prove if the technology is an effective
treatment for MWC residues. Sufficient experience is available for conducting
the engineering and design required for scaling to a specific situation.
Furthermore, the bench scale permitted much more detailed testing to be
completed and thus more exploration of the basic mechanisms involved in the
process. This in turn will assist in the determination of expected long-term
behavior. A drawback with this scale however, is the difficulty in sampling
and variability associated with bottom ashes.
Schedule - At this writing three of the process demonstrations have been
completed. Barring unexpected difficulty all will be completed by mid-May.
Because of curing times (i.e., 28 days) and other test requirements the
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physical testing, chemical testing and analytical procedures will not be
completed until mid-October. The final report is expected by the end of
December 1990.
Future MITE Demonstrations - It is planned that future MITE demonstration
candidates will be solicited by notice in the Commerce Business Daily, through
appropriate MSW trade organizations, interested developers and similar means.
At this time, emphasis for these demonstrations is expected to be on processes
.for recovering marketable products from the MSW stream. Resources of 1000K
have currently been allocated in FY'91 for MITE.
RESULTS AND CONCLUSIONS
Results from the various physical and chemical tests are not available at
this writing. Statements and conclusions concerning process performance are
therefore not possible. The final report will provide the results from all
the testing and will provide a sound basis for determining the effectiveness
of S/S techniques to treat MWC residues. The results will also provide
information on the most useful testing protocols for evaluating, selecting and
designing the S/S process for treating MWC ash.
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TABLE 1. Ranges of Total and teachable Metals
in United States MSW Combustor Ash
as Determined by Researchers^'
Com- Bottom Ash
pound
mg/kg
Pb
Cd
As
Cr
Ba
Ni
CU
31 -
0.81
0.8
13 -
47 -
MD(1
40 -
36,600
- 100
- 50
1,500
2000
.5) - 12,910
10,700
Bottom Ash
Leachate
mg/1
0.02 - 34
0.018 - 3.94
MD(O.OOl) - 0.122
ND(0.007) - 0.46
0.27 - 6.3
0.241 - 2.03
0.039 - 1.19
Fly Ash
mg/kg
2.0 - 25,000
5 - 2,210
4.8 - 750
21 - 1,900
88-9000
Nn(1.5) - 3,600
187 - 2,300
Fly Ash
Leachate
mg/1
0.019
0.025
ND(0.
0.006
0.67
0.09
0.033
- 53.35
- 100
001 - 0.858)
- 0.135
- 22.8
- 2.90
- 10.6
NO = Not Detectable; () = Detection Limit
TABLE 2. Chemical Analysis Performed on
Treated and Untreated Ash
Assay
Method
Purpose
Total Extractable Metals
Dioxins/Furans
pH, Anions, Total
Available Dissolved
Solids, and Ammonia
Loss on Ignition
Chemical Oxygen
Demand
Total Organic Carbon
3050, 6010
8280
9045, 300.0,
160.1, 350.2
209D
508A
See Metals Analysis List
(Table 6)
Community Concern
(Untreated Only)
Salts and Ionic Species
Residual Organic Matter
(typ. 2-5S) and Water of
Hydration
Reduced Inorganic and
Organic Matter
Residual Organic Matter
890
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TABLE 3. Physical Tests Conducted on
Treated and Untreated Ash
Physical Test
Purpose
Moisture Content
Loss on Ignition
Modified Proctor Density
Bulk Density
Particle Size Distribution
Cone Penetrometer
Pozzolanic Activity*
Porosity/Surface Area
Permeability
Unconfined Compressive
Strength (UCS)
UCS after Immersion
Freeze/Thaw**
Wet/Dry**
Useful general data
Residual/Organic Matter and
Hydrated Water
Compressibility
Volume and Similar Physical Changes
Potential Use as Aggregate
Curing Rate and Hardness
Untreated S/S Potential
Potential for Liquid-Solid Contact
and Diffusion Effects
Resistance to FUO Transmission;
Assist in determining contaminant
Release Mechanisms
Load Bearing Capacity
Hydration Effects and Swelling
Physical Weathering Effects
Physical Weathering Effects
* Untreated Ash Only
** Treated Ash Only
891
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TABLE 4. Leaching Tests for Treated
and Untreated Ash
Leach Test
Purpose
TCLP (1 extract)
Distilled Water Leach Test
(4 extracts)
Acid Neutralization
Capacity (10 extracts)
Monolith Leach Test
(7 extracts)
Static pH 0 pH = 4.0
with HNO, Li quid:Sol id
Ratio is 100:1 .
Regulatory Leach Test
Extended Extraction in a Well-Mixed
System without Acid
Buffering Capacity of Solid and pH
Dependence of Metals Release
Estimate Potential Release Rates
Through Diffusion
Total Species Available for Release
Under "Worst Case" Scenario
TABLE 5. Chemical Analysis Performed on
Leach Test Extracts
Assay
Method
Purpose
Metals
Chemical Oxygen
Demand (COD)
Total Suspended Solids
Total Dissolved Solids
PH
3020
508A
160.2*
160.1
150.1
See Metals Analysis List
(Table 6)
Surrogate for Leachable
Organic Species
Physical Erosion of Solid
Leachable Total Salts
* Monolith leach test only (ANSI 16.1)
892
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TABLE 6. List of Metals
Subjected to Analysis
Metal
Aluminum
Antimony
Arsenic
Barium
Beryll ium
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Lithium
Potassium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Selenium
Sodium
Sil icon
Silver
Strontium
Thorium
Tin
Ti tanium
Vanadium
Zi nc
Untreated
Ash (
ICP or AA
X
—
X
X
X
X
X
X
X
X
X
—
—
X
X
X
X
X
X
and Treated
Solid)
Neutron
Activation
X
X
X
X
—
___
- —
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Extracts
ICP or AA
X
X
X
X
X
X
X
X
X
X
X
X
—
X
X
X
X
X
X
X
X
X
X
X
X
X
X
893
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TABLE 7. Additional Metals Analysis
Using Neutron Activation
Untreated and Treated Ash (Solid)
Neutron
Metal Activat"ion~0nly
Cesium X
Dysprosium X
Ga 11 i urn X
Hafnium X
Indium X
Rubidium X
Scandium X
Uranium X
894
-------
References
1. Wiles, C. C. "Characterization and teachability of Raw and Solidified
U.S.A. Municipal Solid Waste Combustion Residues" ISWA 86 Proceedings of
the 5th International Solid Waste Conference, Copenhagen, Denmark.
September 1988.
2. U.S. EPA (Environmental Protection Agency) Characterization of MWC Ashes
and Leachates from MSW Landfills, Monofills and Co-Disposal Sites.
EPA 530-SW-87-028A, Office of Solid Waste. October 1987.
3. U.S. EPA (Environmental Protection Agency) Addendum to Characterization of
HWC Ashes and Leachates from MSW Landfills, Monofills and Co-Disposal
Sites, Office of Solid Waste, June 1988.
4. J. L. Ontiveros, T. L. Clapp and D. S. Kosson. "Physical Properties and
Chemical Species Distributions Within Municipal Waste Combustor Ashes."
In Environmental Progress, Vol. 8, No. 3, pp 200-206, August 1989.
5. H. A. van der Sloot, et. al. "Leaching Characteristics of Incinerator
Residues and Potential for Modification of Leaching." In Proceedings of
the International Conference on Municipal Waste Combustion, Vol. 1,
p 2B-1, April 1989. / •
6. D. R. Jackson, "Evaluation of Solidified Residue from Municipal Solid
Waste Combustors." U.S. Environmental Protection Agency, EPA/600/S2-
89/018, February 1990.
7. Wiles, Carlton C., "A Review of Solidification/Stabilization Technology."
Journal of Hazardous Materials, 14:5-21, 1987.
895
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"UTILIZATION APPLICATIONS OF RESOURCE RECOVERY RESIDUE"
8Y = Dr. Richard W. Goodwin, P. E.
ENVIRONMENTAL ENGINEERING CONSULTANT
14 RAMAPO LANE; UPPER SADDLE RIVER, NEW JERSEY 074!
PHONE: 201-034-D8SS; FAX: 201-034-5S82
Presented at the
First U.S. Conference on Municipal Solid Waste Management
Washington, D.C.; June 13-16, 1090
897
-------
"UTILIZATION APPLICATIONS OF RESOURCE RECOVERY RESIDUE"
BY: Dr. Richard W. Goodwin, P.E.
ENVIRONMENTAL ENGINEERING CONSULTANT
14 RAMAPO LANE; UPPER SADDLE RIVER, NEW JERSEY 07458
PKONE: 201-934-9866; FAX: 201-934-5682
Presented at the
First U.S. Conference on Municipal Solid Waste Management
Washington, D.C.; June 13-16, 1990
INTRODUCTION
In 1989 MSW ash will amount to between 2.8-5.5 million tons and its
annual generation rate is expected to increase two to five depending
on how many facilities arc built (1). The manner in which these resi-
dues arc regulated impact the Waste-to-Encrgy Industry. Such regula-
tion, however, varies by state and with proposed federal legislation.
Attempting to regulate and legislate MSW ashes without a technical
appreciation may be one reason for such diversity. This paper provides
and cost-effective ash disposal and utilization.
o In-Plant Ash Fundamentals
The ash generated from Mass Burn MSW systems is composed primarily of
Bottom Ash [EAJ (75-85 weight*} and FA (15-25 weight*}. The ash gene-
rated from Refuse Derived Fuel [RDF] reflects a higher FA (40 weight*}
to BA (60 weight*} distribution; due to RDF's suspension firing.
A typical Flue Gas Cleaning [FGC] system consists of reacting the
incinerator flue gas with lime (usually in an absorption vessel) fol-
lowed by particulatc removal (bag house or electro-static prccipitatcr}
While these systems arc designed to remove Acid Gases and particulatc,
they increase the waste generation rate due to the product of reaction
products and unrcactcd lime. The AGC waste is composed of Fly Ash [FA]
and Dry Flue Gas Cleaning (i.e. Scrubber Residue [SR]) Reaction
Products. Equipped with a FGC system, the combination of BA, FA, and
SR amounts to 1/4 to 1/3 of the weight of the MSW feedstock.
Depending upon the design of the Ash Handling system the FA/SR waste
may be combined with the BA. Since the BA is quenched, the resultant
blend will contain water. This mixture of ash and FGC wastes arc con-
veyed to a disposal site. This Combined Ash [CA] may be thixctropic
mud-like and contains considerable lime. Its solids content should be
maintained to ensure optimal transportability characteristics i.e. (a)
prevention of fugitive dusting; (b) elimination of spillage; (c) pre-
vention of prc-maturc set-up reaction. Typically, the transportation
solids content could range from SO-DC1 to satisfy these criteria.
In view of the industry-wide trend toward installation of dry lime Air
Pollution Control [APC] to remove such acid gases as S02, KC1 etc. and
in light of the USEPA's proposed air emissions requirements of MSW
898
-------
incinerators (2), this paper's discussion of MSW ash emphasizes the
presence of unrcaetcd lime reagent. Engineering properties arc discus-
sed to provide a basis for utilizing the ash. Due to the controversy
and previous misconceptions surrounding MSW ash, however, its environ-
mental characteristics should be considered.
c Environmental Considerations of MSW Ash
Recent field studies of MSW ash landfills strongly supports the rela-
tively benign characteristics of this ash.
MUS {3} states that "the leachatcs ... arc close to being acceptable
for drinking water use, as far as the metals arc concerned". Soth the
public and regulatory community have focused on the results of labora-
tory tests (e.g. EP Tox, TCLP) to predict MSW ashes' leaching. These
tests, however, do not reflect field leachatcs results; "leachate from
the disposal sites tested out below the level that those two tests
deem hazardous" (4).
Although EP Tox results have shown excessive levels of- Pb and Cd, the
presence of unrcactcd lime (from the APC system) could account for
significant reductions of such constituents (5). The author has con-
tended that such ash should be deemed.pozzolanic and recognized by
regulatory authorities (5). Recently some state regulatory agencies
have recognized this behavior and incorporated it within their
classification of MSW ash landfills. The California Dcpt. of Health
Services concluded that MSW "... ash possesses intrinsic physical and
chemical properties rendering it insignificant as a hazard to human
health and safety, livestock, and wildlife". The "intrinsic property"
is the formation of a "lime/pozzclan mixture" so that when "compacted
(the) ash forms a hard, non-credible surface" (7).
o Low Empirical Solubilities of MSW Ash
Rather than regarding the presence of lime inducing pozzolanic beha-
vior as a benefit (to reduce the ashes' potential leachate}, some
regulators have postulated that the lime could dclctericusly affect
underlying clay liners (5). The following summarises the leachate and
raw pH data:
Lime-based APC ESP Only
ASH LEACHATE ASH LEACHATE
pH 11.68 - 11.85 5.7 - 7.4 11.58 - 11.32 S.9
10.Ql - 11.67 6.5
The significant pH drop from raw ash levels to leachate values arc
explained by considering the inherent pozzolanic behavior of lime-
based MSW ash. As CaC enters into the pozzcianic reaction it is no
longer available as a soluble component and is not detected in the
leachate. The alkaline pH of the non-lime based ash and its similar
reduction of leachate also may be explained by considering the pozzc-
ianic chemistry. CaO reacts with A1203, Fc203, and Si02 to form pozzo-
lanic end-products (8). MSW Ash inherently reflects an alkaline pH;
Water Leach testing of Hcnncpin Energy Resource Company's Bottom Ash
pH = 9.2 - 9.3 .(9). The reduction of soluble alkalinity (water leach
899
-------
pH) in ashes from Resource Recovery Facilities with and without lime-
based APC could be due to consumption of pczzolanic rcactants.
TABLE 1: POZZOLANIC RSACTANTS - LSACHATS PH
W/ Lime APC W/0 Lime APC
% A1203 [A] 7.39 - 10.30 5.93 - 13.00
% Fc203 [F] 3.90 - 18.15 5.73 - 10.64
% Si02 [S] 19.00 - 43.80 32.00 - 62.90
% CaO [C] 15.10 - 25.70 9.70 - 12.00
% A + S -!- F 32.76 - 65.85 50.83 - 77.65
[A -!- S + F]/ C 1.27 - 3.63 4.24 - 8.01
pH - Ash 10.91 - 11.85 10.35 - 11.82
pH _ Wat. Lcach-Int. 11.78-12.48 9.97-10.70
pH - Wat. Leach-Fin. 11.12-12.48 10.28-10.60
pK - Field Leach 6.50-7.40 8.90 - N.A.
NOTE: N.A. = Not Available
Table 1 depicts that both types of ashes lie within the pozzoianic
requirements (ASTM 618) and that the ratio of pczzclanic rcactants
lies within the range of analogous clean coal technology rcsiducs(10) .
The lower field leach pH's (6.5 - 7.4) compared to raw pK (10.28 -
12.48) and initial water leach pK (9.97 - 12.48) suggest a reaction.
This reaction, however, may not be a neutralization mechanism since
the final water leach pH of 10.28 - 12.48 predicts soluble alkalinity.
Realizing the final water leach pK is much higher than the field leach
pK, infers the reduction of soluble alkalinity due to a dissipativc
reaction. This reaction could represent the CaO combining with the
other pozzoianic constituents. Lacking gco-tcchnical engineering data
from the NUS study prevents a more definitive explanation. Nonetheless,
all the data indicates that the actual field pH's of MSW do not reflect
their initial basic alkalinitics and that only slight solubilization
of alkaline constituents occur in nature.
ASK UTILIZATION AS NATURAL LINER
The Waste-to-Encrgy facility's primary concern regarding MSW ash
involves yielding a transportable material. This ash, however, upon
exiting the mechanical conveying system, awaiting transport to a land-
fill, may be subject to regulatory testing and should be subject to
proper Disposal Site Management. This paper offers data demonstrating
the concrete-like behavior of MSW ash and incorporates such results
into Ash Management Principles to ensure set-up. Regulatory agencies
should review this technical information and allow the application of
basic Civil Engineering and Concrete Chemistry to be reflected within
Sample Preparation Procedures and Testing.
Achieving the Inherent Concrete-like Behavior
Table 2 compares the author's derived mincralogical content of MSW
ashes (Mass Burn and RDF) to Portland Cement. The comparative similar-
9OO
-------
itics suggest that solubilization of MSW Combined Ash [CA] (i.e. BA,
FA, and SR) should react in a concrctc-likc manner. The author's prior
work has discussed this potential behavior of MSW ash (due to its
favorable mineral composition) and of the relatively high lime content
of MSW ash (due to higher stoichiojnetrics and no recycle) (9). RDF
ash, also, reflects a higher lime content than Mass Burn Residues.
This theoretical basis provides a framework for considering Heavy Metal
Reduction and enhancement of gcotechnical properties. Achieving such
behavior depends upon solubilizing the free, available lime and
attaining optimal compaction.
TABLE 2: CHEMICAL COMPARISON TO PORTLAND CEMENT
Composition of Portland Cement MSW Ash
Component Cement Clinker Mass Burn RDF
Si02
A1203
Fc203
CaO
13-24
4-3
1.5-4.5
62-57
21.7-23.3
5.0-5.3
0.2-2.6
57.7-70.8
24
6
3
37
37
4
C
w
43
Laboratory work has revealed an inverse trend relationship between (a)
Percent Solids/Water of Solubilisation and (b Mean and Particle Size
Distribution. To achieve a Gcotechnical Property (i.e. strength, per-
meability), reflecting set-up conditions, more water of solubilization
was required for a recipe with finer Particle Size Distribution. A
possible explanation for this relationship is that the smaller sized
particles exhibit a greater surface area; thus requiring mere water of
solubilization within the voids to promote the pczzolanic or set-up
behavior.
Effect of Water of Solubilization on Set-up Time
Not only docs the introduction of additional water of solubilizaticn
facilitate attaining concrete-like behavior but optimizing the % Water
of Solubilization reduces the set-up time. When highly reactive Com-
bined Ash (i.e. Bottom and Fly Ash with Scrubber Residue) was tested
at two different Percent Solids the following permeabilities and cur-
ing times were determined.
S Solids Permeability {after 120 Krs) Permeability (after 23 days)
75 2.5 X 10 EXP-7 cm/sec 1.31 X 10 EXP-S cm/sec
30 2.3 X 10 EXP-5 cm/sec 1.02 X 10 EXP-S cm/sec
Achieving the significantly lower permeabilities (i.e. two orders of
magnitude reduction) at the early cure time (120 Hours), when more
water was present in the sample, suggests that adding water of solubi-
lization accelerates the reaction. An aqueous phase is more quickly
established for the chemical constituents to react. Since 28 day per-
meabilities were essentially the same for both Percent Solids samples,
the reactions were completed for these ashes of equivalent composition.
fWhcn more water is available for solubilization of reactive constitu-
ents, reaction time is reduced and a harder, less permeable material
produced.
9O1
-------
Field Demonstration of In-Situ Permeability
Such encouraging laboratory results justified a field dcmcnst ration. A
field program, designed to demonstrate the viability of low-cost in-
situ. chemical treatment achieving liner-like permeabilities, was ini-
tiated at an older Mass Burn facility. Ash from this facility, not
equipped with a FGC system, represented an opportunity to demonstrate
the cost-effective methodology of in-situ addition of Portland Cement
and of lime [CaO] to non-chemical ly reactive MSW ash. Field Curing
occurred during worst-case winter conditions. A detailed description
of this study has been reported by Forrester and Goodwin (11).
Test Patches were formed from non-reactive Combined Ash [CA] . Portland
Cement [PC], 6-10 % by weight, and Lime [CaC] , 6-75K by weight, were
added in-situ to separate patches. Optimum waters of sclubilization
were attained to promote chemical reaction.
The permeabilities derived from the Field Demonstration Test Patches
are compared to the results of a Laboratory Study. The Laboratory
Study reflects PC dosages ranging from 6-9% and CaO dosages from 3-6%
{by weight) . Ashes used in the Laboratory Program were composite sam-
pled from a newer Mass Burn facility, equipped with a FGC system con-
tributing unrcactcd CaO to the Combined Ash [CA]. Permeability results
of the field and laboratory programs arc reported in Table 3. The
variation of in-situ and laboratory permeabilities reflect typical
field and lab testing differences (12).
vsr^'M^4"r%M.T -?lr^»\ Or<*»^<^i^T«v*^'»
AAW AW »• W ___ A JUg^W / *^W C*W W .A W*A«J
Bottom Ash [BA] should not contain free available CaO, since it is
collected upstream of the FGC system. Combined Ash [CA] studied
in the laboratory represents the combination of BA with the separately
collected FA and SR. Since the CA studied in the field did not reflect
liaac contribution from a FGC system, the laboratory BA should repre-
sent a similar composition. Table 3 reports that older non-reactive CA
+ 0% exhibited a laboratory permeability of 1.0 X BXP-5 era/sec; prac-
tically equivalent to raw laboratory studied BA permeability of 1.8 X
EXP-5 cm/sec. Thus, the CaO Test Patch CA permeability results can be
compared to Lab Program results for CA with and without CaO addition.
These latter ashes were obtained from a newer facility reflecting
significant inherent CaO due to high stoichicmctry of the FGC system.
The Test Patch Program (Table 3) reports permeability results from
6.4 X EXP-6 cm/sec to 2.3 X EXP-S cm/sec. The one to three orders
of magnitude permeability reduction in the presence of free CaO sug-
gests concrete-like behavior. The raw, but reactive, CA permeability
of 5.5 X EXP-6 cm/sec could reflect the presence of excess lime con-
tributed from the operating FGC system. Upon the addition of lime to
reactive CA, permeabilities ranging from 4.2 X EXP-5 cm/sec to 8.1 X
EXP-7 cjn/scc were achieved. These permeabilities agree with field
measurements . Both sets of results demonstrate at least an order of
magnitude reduction of permeability; suggesting the presence of a
lime-based concrete-like reaction.
902
-------
Effect of Adding Portland Cement
Adding Portland Cement [PC] tc non-reactive Test Patch CA reduced the
permeability by two to four orders of magnitude. The field in-situ and
cored permeabilities ranged from 7.5 X EXP-7 cm/sec to 2.8 X EXP-9
cm/sec. The permeabilities, obtained from the laboratory study of BA
with similar PC dosages, ranged from 1.5 X EXP-7 cm/sec to 1.7 X EXP
10-8 cm/sec. Thus, the addition of 6-10ft Portland Cement added to non-
reactive MSW ash attained permeabilities varying from slightly greater
to at least an order of magnitude less than the liner requirement of 1
X EXP-7 cm/sec.
TABLE 3; PERMEABILITY COMPARISON FIELD AND LABORATORY PROGRAM
Field Program Permeability Results
Dosage In-Situ and Cores
CA + Oft 1.9 X EXP-5 cm/sec
CA 6 - lOftPC 7.5 X EXP-7 to 2.8 X EXP-9 cm/sec
CA 6 - 7 ftCaO 6.4 X EXP-6 to 2.3 X SXP-8 cm/sec
Laboratory Program Permeability Results
Ash Additive (ft) Permeability
BA
BA
CA
CA
0
-------
Standards [DWS], but indicate one to two orders of magnitude lower Cd
and Pb than reported by the EP Toxicity tests (15). Such discrepancy
between field and lab data questions the EP Tcxicity test to realisti-
cally predict the concrete-like behavior of MSW ash. Furthermore,
comparing the leachatc/runcff pH of 6.7 to CA's inherent pH of 12-13
suggests a 'set-up' reaction. The resultant monolith precludes surface
soiubilizaticn of chemical specie. Based upon the operating results
presented, the MSW ash from Resource Recovery systems, equipped with
Flue Gas Cleaning, when properly managed in an engineering fashion,
will achieve liner-like low permeable characteristics and leachatc/
runoff approximating primary DWS.
TABLE 4: LSACHATE RUNOFF COLLECTION RESULTS
PARAMETER CONCENTRATION (mq/1) PRIMARY DWS (ng/I)
Cadmium [Cd] 0.022 0.010
Lead [Pb] 0.007 0.050
0.005 [Proposed]
pH 5.7 6-9
ROAD CONSTRUCTION APPLICATIONS
In the past, MSW residues have been utilized for road construction
(15). Incinerator ash has been tested at a few road construction
c* 4-^
Phila, PA (1075) 50 Acceptable
Co, PA (1975) 50 Acceptable
Karrisburg
PA (1976) 100 Excellent (Fused Residue)
Conclusions derived from this work can be summarized as: (a) Loss On
Ignition [LOI] < 10% - eliminate organics; (b) achieve ASTM specifica-
tions; (c) limit application to 50£ ash and 50% residue; and (d) mini-
mize fine particle component i.e. eliminate Fly Ash [FA].
BA has been used in Europe and Japan for road construction. These
studies addressed not only the technical suitability issues as a road
construction material, but they discussed such environmental factors
as leachatc, fugitivity, runoff, etc..
Analogous Chemical Comparison
Table 5 compares the Chemical Composition of MSW ash to Oil Shale Ash
and to Portland Cement (Cement and Clinker) . Between 4-8% gypsum was
added to Oil Shale Ash to coniprcssivc strength reaching 23 MPa (4100
psi) (17). By analogous comparison, Table 5 suggests that approximate-
ly 15% lime should also be added to the MSW ash; assuming a dry lime
scrubber. Based on this oil shale analogy, the resultant material
would satisfy the specified (ASTM C-593) minimum comprcssivc strength
904
-------
(600 psi) (4100 kPa) for a pczzclaii. Although lime addition also may
be required to achieve parity with Portland Cement, based upon the
chemical comparison a high potential exists for utilization of MSW ash
as a ccmcntiticus by-product. Adding 10% Portland Cement to ash,
without Acid Gas Cleaning Reaction Products and from an operating Mass
Burn facility, yielded ccasprcssivc strengths exceeding 1000 psi (18).
TABLE 5: CHEMICAL COMPAPsISON TO ANALOGOUS MATERIALS
COMPONENT-5SWT OIL SHALE ASK RESIDUE/APC WASTE
Mass Burn RDF
Si02
A1203
Fc2C3
CaO
20
S
4
50
24
6
3
•31
W A
37
4
c
43
Composition
Component
Si02
A1203
FC203
CaO
of Portland
Cement
18-24
4-8
1.5-4.5
62-67
Cement
Clinker
O 1 *7_OO
tm J. . A «• U .
W . »rf ~" »^ •
0.2-2.
67.7-70.
8
3
6
8
Mass
24
6
3
37
MSW Ash
Burn RDF
37
4
e
43
Particle Size Restrictions
In addition to chemical composition, potential end-uses require speci-
fic particle size distribution. Table 6A depicts the size distribution
of Bottom Ash and Fly Ash; representative of a 240 TPD (218 Metric
ton/day) Mass Burn facility. A comparison of these distributions shew
potential uses of Bottom Ash as Coarse Highway Aggregate (ASTM D 448}
and of Fly Ash as Fine Cement Aggregate (ASTM C33). In both cases,
additional segregation would be required to achieve conformity to size
distribution requirements. Incorporating such segregation could yield
approximately 75% of the Bottom Ash as suitable for Coarse Highway
Aggregate and 25% of the Fly Ash as suitable for Fine Cement Aggregate.
Separating (i.e. screening) coarser (>3/8" to 3/4") material from
Bottom Ash improves the Combined Ash characteristics and enhances
recycle potential of the coarser residues. CBR's of non-reactive ash
achieved approximately 40%;i.e. suggesting that six (6) inches could
be used in a pavement sub-base (10).
As indicated by Table 6B, the FA size distribution favors consideration
as Soil Aggregate, for paving application (ASTM 1241). The combined
Mass Burn Ash also conforms to Soil Aggregate, for paving application
(ASTM 1241). Such uses may not require additional size segregation.
905
-------
TASLE SA: POTENTIAL USES OF KSM ASH - ADDITIONAL SEGREGATION
OQTTQJII £cu £c COARSE AGGREGATE - HIGHWAY CONSTRUCTION FLY ASH AS FINE AGGREGATE - CEMENT
nGSS uuPPi
Sieve Sirs ASTM (0 44S) Sottoa Ash
iSPCSHw iTnSP
2 Inch (50 an} 100
1.5 In.(37.5 as) 35-100
--k tic ~-^
n c T. Mi c _-\
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i^uut. ww. nwt* r»WM ft^ Ovi4. f»w\rfni.wn«4. wvwun»/fc.f
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n
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insr fercent Finer
mn i t.-k ten -~\ inn
iww i. A 1 1 w 1 1 y w w 111 lit y iww
74 1 Inch (25 as) 75-S5
en n ?o i- 'n c ~-\
-------
c Types of Sanitary Landfill Cover
Bottom Ash [BA] is proposed to be used as cover material for a MSW
Landfill. Three (3) cover applications arc considered: (1) Daily
Cover; (2) Side Cell Intermediate Cover; and (3) Interim Final Cover.
Daily cover is usually applied at the end of working day at six inch
thicknesses. Intermediate cover is applied in six inch lifts to a
thickness of one foot when the working area will be inactive for one
to three months. Interim cover pertains to the material which becomes
a component of the final cover of the landfill. Interim cover is applied
in six inch lifts to a two feet thickness. Table 7A describes the
three types of Sanitary Landfill Cover:
TABLE 7A: TYPES OF SANITARY LANDFILL COVER
Cover Type
Thickness
Exposure
Application Rate
Comment
Daily S inch
Intermediate 1 foot
Daily/Weekly
30-00 Days between
Compacted Daily
6" cover lifts
Interim
2 feet
MSW lifts
Within one week of
C»-% *W*V^ "^ <"^ ^* ^^*^f*l*«
Sy ili^ V4\j- ^ v, *u\ V* \ 1
Cover Lift
6" cover lifts
Cover Lift
wi ^AA^jTi v^no WQC«C
c Technical Requirements Cover Material
Traditional cover material range from using sand as Daily Cover, sandy
clay as Intermediate Cover, and clay/silt as Interim Cover. The
engineering requirements for each type of cover material may be
categorized according to its permeability and/or particle size
distribution. Table 7 B summarizes such criteria:
TABLE 7B: ENGINEERING CRITERIA SANITARY LANDFILL COVER
Cover Type Permeability Size
Daily
10 E-3 cm/sec
Cover Type
Pcrmcab i1i ty
100& < 3 inches
Max 25% < No. 100 Sieve
Max 1035 < No. 200 Sieve (NJ)
Max 5% < No. 200 Sieve (NY)
•j 3.ZC
Intermediate
Interim
10 E-4 to 10 E-5
cm/sec
Same as Intermediate
9O7
-------
o Substitution of Resource Recovery Bottom Ash
Previous work in New England using Coal Ash as Sanitary Landfill Covers
offers the prospect for using Resource Recovery Bottom Ash in the same
applications (20). Based upon prior work Bottom Ash conforms to the
Particle Size Requirements (21). Although the typical Bottom Ash exhi-
bits a Permeability of about 10 E-5 cm/sec, such values were obtained
at 95% modified proctor compaction. By applying a Standard Proctor
compactivc effort of 85% the resultant permeability should be increased
approaching the Daily Cover requirement. The Bottom Ash generated from
a 2000 TPD Mass Burn Resource Recovery facility will satisfy the daily,
intermediate and interim cover requirements of a Sanitary Landfill
servicing approximately 100,000 people. In the Mid-Atlantic region,
final capping, composed of Bcntcnitc Clay, costs $160/CY (f.o.b.) or
approximately $300/CY (delivered) (22),
o Daily and Interim Sanitary Landfill Cover
Sweden has applied slag or bottom ash as an interim cover for several
years. Daily and interim cover is applied to prevent dusting, control
vermin, and provide for some passage of moisture to the buried MSW. As
a general guideline, New Jersey suggests a Particle Size Distribution
of < 3 inches to a maximum of 10% passing a No. 200 sieve. New York
limits the percentage of fines to 5% passing a No. 200 sieve. NJ and
New Hampshire recommend a maximum permeability of 10-3 cm/sec for
daily cover. NH allows a lower permeability of 10-5 cm/sec for interim
cover. MSW Bottom Ash conforms to such requirements.
c Effect Upon Lcachatc and Biological Activity Rates
McEnroe and Schrocdcr (23) have shown that the Leakage or Lcachatc
Rate through the Drain Layer is directly related to its degree and
depth of saturation. Since BA exhibits permeability of approximately
10 E-4 to 10 E-5 cm/sec and typical daily and intermediate cover
material's permeability ranges as low as 10 E-3 cm/sec, the amount and
depth of saturation will be reduced. Hence the underlying head and
Lcachatc or Leakage Rate [QLJ is reduced. Therefore, the rate of flow
from underlying cells and eventually to the final liner is reduced.
Using less permeable BA as Daily and Intermediate Cover hydraulically
reduces the leachatc/leakage flow rate.
Moisture content of MSW is directly related to biological activity in
terms of Gas Production and Consolidation/Settlement Rates (24). Since
the saturation and transfer rate of leachatc would be reduced, due to
the presence of less permeable BA, both gas and settlement rates should
be reduced - reaching an equilibrium or steady-state condition. By
controlling these rates both safety and cracking issues arc mitigated.
c Effect Upon Lcachatc Quality
Gray (25) demonstrated the improvement of MSW leachatc quality upon
passage through a layer of coal/wood ash. Both organic and heavy metal
contaminants were observed. One-third reductions of BOD and COD were
observed; while Cd and Pb were reduced by 31-100%. A compositional and
physical analogy has been developed between coalfired ash and MSW ash
(26). BA's surface area is approximately 2 sq. cm./gm (27) and typifies
9O8
-------
Granular Activated Carbon [GAG]. GAG media removes organics via adsorp-
tion. BA's alkaline pK [> 9] should mitigate the growth of deleterious
microorganisms. The mechanisms of adsorption and biological inhibition
could account for the expected reductions of crganics and heavy metal
contaminants.
MSW ASK AS RAW MATERIAL SUBSTITUTE - PORTLAND CEMENT MANUFACTURE
MSW ash reflects a mineralogy similar to Portland Cement Clinker. ASTM
C618 Cement Product Specification requires that the total of Si02 -*-
Fc203 + A12O3 contain a minimum range of 50 - 70% by weight. ASTM,
however, docs not provide a specification for Raw Material Portland
Cement Manufacture. Table S compares the mineralogy of MSW residues to
Cement Clinker and to conventional and advanced S02 conversion and/or
coal combustion.
TABLE S; RAW MATERIAL SUBSTITUTE - PORTLAND CEMENT
Percent by Weight
A1203 CaO Fc203 Si02 LOI sg.m/gn
COAL-FIRED FLY ASK 25 1 12 . 54 5 0.55
DRY FGD FLY ASH 9 25 4 21 4 6.85
LFI FLY ASK 17 38 12 16 11 4.25
AFBC FLY ASH 15 23 19 15 13 23.9
MSW ASK 5 37 3 24 <10 0.38
CEMENT CLINKER 6 62 4 22 5 N.A.
(max)
NOTE: Dry Flue Gas Dcsulfurization (FGD) Fly Ash = Calcium Based Spray
Dryer Adsorption Applied to Coal-fired Plants
LFI = Limestone Furnace Injection; Limestone (CaC03) injected
into coal-fired burners e.g. Limestone Injection Multi-Burner [LIMB]
AFBC = Atmospheric Fluidizcd Bed Combustion
Only 7% of the conventional coal combustion ash is used for Portland
Cement manufacture. Such a low utilization may be attributed to a
relatively low CaO content in conventionally fired ash compared to
residues from advanced S02 conversion and/or coal combustion systems.
Dry FGD, LFI, and AFBC reflects Clean Coal Technology in terms of
advanced S02 conversion and/or combustion. Portland Cement represents
their high potential utilization option (10). Given the favorable
mineralogy and compatible surface area of MSW residues relative to
typical raw materials and analogous ashes, up to approximately 71%
substitution could be expected. Based on a typical 2000 TPD Mass Burn
Resource Recovery facility generating 500 TPD of residue and assuming
a 71% substitution, one cement plant could accommodate all of the ash
from five such plants.
909
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o Chlorides
Typically a maximum Chloride concentration of 4% by weight can be
tolerated in Portland Cement Manufacture. In some instances, MSW resi-
dues may exceed such limitations. Based upon the author's experience
the chloride levels can be reduced through preprocessing.
o Unburnt Carbon - Excess Organics
In addition to Chlorides affecting the ccmcntitious reaction, excess
organics (i.e. unburnt Carbon) reflects another impurity of concern.
ASTM C518 requires a maximum of 6& LOI. Typically a newly designed
Mass Burn facility will yield residues of LOI < 1.0 %. Warren County
exhibited LOI's between 2.6 - 3.85 during their start-up and shake-
down phases (1988/1989). After retrofitting an improved combustion
efficiency design Wcstchcstcr County consistently demonstrated LOI's
of < 0.5%.
o Potential Air Emissions
Cement Kilns typically exhibit a nominal firing temperature of 2600
dcg F - having a flame temperature of 3400 - 3500 dcg F. At such tem-
peratures, the emission contribution from MSW ash substitution should
be < 10 ppm.
c Concrete Admixtures using MSW Ash-derived Portland Cement
Based upon the coal combustion analogy, the following represents
potential Concrete Admixture menus incorporating MSW Ash as a Raw
Material substitute in Portland Cement Manufacture.
Preliminary Concrete Blends - Replacement
Cement Cement-Fine Aggregate
COMPONENT WEIGHT PERCENT WEIGHT PERCENT
Incinerator Ash - based
Portland Cement 14 14
Fine Aggregate 34 32
Coarse Aggregate 46 43
Water 6 11
IMPURITIES
Since the conceptual considerations appear encouraging, research and
development efforts arc justified. Such efforts should include the
possible adverse effect of soluble impurities. Table 9 reports consti-
tuent/impurities based on ASTM Product Specification. To ensure end-
user acceptance and product conformity, further testing of MSW residue:
according to ASTM procedures arc recommended.
910
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TABLE 9; POTENTIAL IMPURITIES - MSW ASH
MSW ASH
Constituent w/ Lime APC w/o Lintc APC Limit ASTM Spec
A + F + S (£) 32.76 - 66.35 50.83 - 77.65 50-70 C 613
Sulfur as S03 0.06-0.51 0.14-0.36
(Total - £}
3.0 - 5.0 C 595
Sulfur as S03
(Soluble - 35) ND - 0.05 0.02-0,04
Sodium as Na20 1.59-2.97 1.59-2.57
(Total - «)
1.5 C 613
Sodium as Na2O
(Soluble - %) 0.02 - 0.06 0.01 - 0.05
Water Soluble
Fraction {%) 0.64 - 6.53 1.12 - 3.55 10.0 C 593
NOTE: ND = Non-Detectable
C 518 = Standard Specification for Fly Ash and Raw or Calcined Natural
Pozzolans for Use as Mineral Admixtures in Portland Cement
C 595 = Standard Specification for Blended Hydraulic Cements
C 593 = Standard Specification for Fly Ash and Other Pczzcians for Use
with Lime
In addition a practical chloride limitation of 4% by weight should be
considered; based upon extrapolation from the NUS Study a soluble
chloride concentration of 0.0034 - 0.034 & has been derived. Therefore,
these derivative soluble impurities in MSW ash appear to satisfy ASTM
allowable concentrations.
BY PRODUCT UTILIZATION CONCEPT - ECONOMICS
Establishing a scenario for By-Product Utilization would reduce dispo-
sal costs and offer the potential for revenue from the sales of the
Waste Material. Demonstrating the concrete-like characteristics of MSW
Ash and its suitability as a self-liner, suggest applying this paper's
engineering principles to utilization concepts. A close approximation
to Portland Cement has been shown by Tables 2, 8 and 9. Obtaining By-
Product Properties may be accomplished by seeding the MSW with Stan-
dard Additives. Table 10 tabulates the Chemical Additive Unit Costs
used in developing a Stabilization Treatment Cost Matrix. This matrix
was based upon a typical Mass Burn facility:
o 1500 Ton/Day Capacity
o 500 Ton/Day Total Ash
o BA = 85% by weight = 425 Ton/Day
o CA = 15% by weight = 75 Ton/Day
o 300 Operating Days per Year
911
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This matrix indicates that adding commercially available additives
to MSW ash would only increase Operating Cost by $ 1.60/tcn of MSW Ash
to $4.20/ton of MSW Ash.
TABLE 10: STABILIZATION COST ANALYSIS OF COMMERCIAL ADDITIVES
UNIT ADDITIVE COSTS
Chemical Additive $/Ton Comment
Portland Cement [PC] 75
CaO (Pebble Lime) 60
Lime Kiln Dust [LKD] 12 50% reactive
Cement Kiln Dust [CKD] 12 50% reactive
Coal-Fired Fly Ash [CFFA] 3
Gypsum [CaS04.2H20] 45 Purity = 87-90%
By applying the principles of optimizing (a) Particle Size Distribution,
(b) % Water of Sclubilization, (c) Chemical Additive Dosage, and (d)
Degree of Compaction or Dcnsification, a conceptual Utilization System
is preliminarily engineered. Table 11 presents a conservative budgetary
estimate for a Utilization Plant augmented to a resource recovery
facility. The Unit Process Cost of $32 per ton of ash (about $1I/ton
of MSW) is 1/3 to 1/2 the cost of ash monofill disposal in NJ. Rather
than expend resources to discard MSW Ash, the Waste-tc-Encrgy field
(private and public sector) is urged to implement By-Product concepts.
TABLE 11; COST COMPARISON: BY-PRODUCT UTILIZATION VS. DISPOSAL
Capital Equipment Investment = $ 5 . 5 MM
«n«. •*- •;•»-«+••«'•*** rr>UT?. 1 nv /»»». «a in v^^f — <• n r» MM /v»«
W^ C .Ai 4**A v ^ «^AA ^ X^AXA; • Awu/jf*k v~^w A^«^J — v '•'•*•' i'i*'A/ A ^
tno-l — c on /T^*-,
^ w« j — V w/ A «^«A
Operation £ Maintenance = 35 %
C *-»»•» ^ -4 »^ f<
V^AA <>. ^4*
oo
New Jersey Resource Recovery Ash Mcncfill
UNIT DISPOSAL COST = $ 75 to 110 Per Ash Ton
By implementing the above Utilization Concept, savings of $12 to $16
per ton of MSW could be realized. Just donating the processed
ash could save millions of dollars per year.
SUMMARY
Ashes from both Mass Burn and RDF MSW incinerator systems reflect
chemical composition suggesting inherent pozzolanic behavior. These
ashes were generated from Resource Recovery facilities equipped with
Flue Gas Cleaning Systems. The high stoichicmctrics of such systems
produce considerable excess lime which promotes pozzolanic or ccncrci
like behavior. The principles of proper Site Management, including
adding the optimum water of solubilization and attaining optimal ccm-
912
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paction, have yielded permeability coefficients between 10 X EXP-7
ens/sec to 10 X EXP-9 cm/sec, after 14-23 days curing. Empirical Confir-
mation of achieving Lev,* Permeabilities and High Lcachatc Quality have
been Demonstrated. Collected Undcrdrain Lcachatc, from an active Ash/
Scrubber Residue Moncfill approximated Drinking Water Quality for
Inorganic and Organic specie and the resultant pH of 5.7 reflect low
solubility and in-situ permeability { *^ lUf 4*4_A^1*^i'*4>*«^ «•** **r j **v* ^4v%*^l ^^•*\v%vs-«v%^>v
Vt£«£SX W^^^ilAtdt W !•» .A. Jf V ^ ^* *. W / ^-» A • A A. A t.AAW *'* -i *-* tt \m ^ IAAA W.LW .kW^^WAAf ± .LAA^ni.^ W «**£>£/ ^ **^ f
composed of Bcntonitc Clay, costs $150/CY (f.o.b.) or approximately
$300/CY delivered. The deficiency of Portland Cement Raw Materials
(shale, clay, limestone) in Wastc-tc-Encrgy intensive regions (New
England, Mid-Atlantic and south eastern seaboard) provides a receptive
and economically-driven scenario for MSW substitution.
Chemical Comparisons suggest adding approximately 15% lime (for Port-
land Cement) and 4-S& gypsum (for an ASTM pczzclan). Based on Particle
Size Distribution of MSW Ash, segregation could yield approximately
758J of the Bottom Ash (suitable for Coarse Highway Aggregate) and 25%
of the Fly Ash (suitable for Fine Cement Aggregate). Segregation,
however, would not be required for cither MSW Fly and Combined Ash for
direct use as Soil Aggregate, for paving application.
This paper postulates that using Bottom Ash [BA] as interim/final
cover material would better control the passage of water and encourage
attaining a bio-kinetic stabilization within the landfill before plac-
ing final impermeable capping. As discussed the intermediate layers of
BA and MSW would transmit a reduced hydraulic rate to the bottom liner
and would reduce respective saturation and moisture contents. The BA
generated from a 2000 TPD Mass Burn Resource Recovery facility will
satisfy the daily, intermediate and interim cover requirements of a'
Sanitary Landfill servicing approximately 100,000 people.
Given the favorable mineralogy and compatible surface area of MSW
residues relative to typical raw materials and analogous ashes, up to
913
-------
approximately 71% substitution for traditional Portland Cement Raw
Material could be expected. Based on a typical 2000 TPD Mass Burn
Resource Recovery facility generating 500 TPD of residue and assuming
a 71% substitution, one cement plant could accommodate all of the ash
from five such plants. Based upon derivative soluble impurities, MSW
ash appears to satisfy ASTM allowable concentrations.
AUTHOR'S RESTRICTION
THIS DOCUMENT IS NOT TO BE QUOTED, CITED, REFERRED TO, PUBLISHED OR
COPIED WITHOUT THE EXPRESS WRITTEN CONSENT OF THE AUTHOR.
REFERENCES
1. Office of Technology Assessment [OTA]; Facing America's Trash: What
Next for Municipal Solid Waste? Dec. 19S9.
2. CORRE Newsletter; Volume Three, No. 12; Dec 19S9
3. NUS Corp.; Characterization of Municipal Waste Combustion Ash. Ash
Extracts, and Lcachatcs; USEPA Contract No. 68-01-7310; Feb. 1990}
4. Resource Recovery Focus; "Study Shows Real Combustion Ash Less
Toxic Than Lab Test Results"; Vol.2, No. 1; Winter 1990.
5. "Managing Ash From Municipal Waste Incinerators"; Center for Risk
Management Resources for the Future; Nov. 1983.
S.Goodwin, R.W.; "Residues from Wastc-to-Encrgy Systems"; comments
submitted to USEPA pursuant to proposed amendment Subtitle C of RCRA
[40 CFR Parts 251, 271 and 302]; 7/31/86.
7. California Dcpt. Health Services; "Classification of Stanislaus
Waste Energy Company Facility Ash"; 2/8/90.
8. Goodwin, R.W.; Schuctzcnducbcl, W.G.; "Residues from Mass Burn
Systems: Testing, Disposal and Utilization Issues"; Proceedings
of the NYS Legislative Commission's Solid Waste Management and
Materials Policy Conference; NYC Hilton Hotel; Feb. 11-14, 1987.
9. W. Schuctzcnducbcl; Personal Communication; Blcunt Energy Resource
Corp.; 4/24/90.
10. Goodwin, R.W.; "Engineering Evaluation: Residues From Clean Coal
Technology"; POWER; August, 1990.
11. Forrester, K. E. and Goodwin, R.W.; "Engineering Management of
MSW Ashes: Field Empirical Observations of Concrete-like Characteris-
tics"; Proceedings USEPA International Conference of Municipal
Waste Combustion: Hollywood, FL.; April 11-14, 1989.
12. Zimmie, T.F. and Riggs, C.O. (editors); ASTM Publ. No. 745; Perme-
ability and Groundwatcr Transport; pages 55-58.
13. Goodwin, R.W.; "MSW Ash: Liability or Asset"; presented at the
McGraw Hill's Wastc-to-Encrgy '88: The Integrated Market Conference;
{Oct. 3-4, 1988; L'enfant Plaza Hotel; Washington, D.C.)
14. Forrester, K.E.; "State-cf-thc-Art in Thermal Recycling Facil-
ity Ash Residue Handling, Reuse, Landfill Design and Management";
presented MSW Technology Confer.; San Diego, CA; 1/30 - 2/1, 1989.
15. Goodwin, R.W.; "Utilizing MSW Ashes as Monofill Liner"; Proceedings
1989 National Solid Wastes Forum on Integrated Waste Management;
Association of State and Territorial Solid Waste Management Officials;
Grcsvenor Hotel; Lake Bucna Vista, FL; July 17-19, 1989.
16. Resource Recovery Report; Proceedings MSW Ash Utilization Confer-
ence: Oct. 13-14, 1988; Pcnn Tower Hotel; Phila, Pa.
17. A. Bcntur and T. Grinbcrg; "Modification of the Cementing Properties
of Oil Shale Ash"; Ceramic Bulletin; Vol. 63, No.2, 1984; Pgs. 290-300.
914
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REFERENCES
18. Goodwin, R.W.; "Pczzolanie Behavior of MSW Residues"; presented at
Northwest Center for Professional Education Conference - "New Develop-
ments Incinerator Ash Disposal"; {NYC Hilton; Apr. 26, 19SS)
19. Poran, C.J. and Ahtchi-Ali, F. ; "Properties of Solid Waste
Incinerator Ash"; Journal of Gcotcchnical Engineering; ASCE; Vol. 115,
No. 8; Aug. 1D80; Pgs. 1118 - 1133.
20. Click, H.B.; "Coal Ash Use as an Economical Cover at Sanitary
Landfills"; Proceedings of the 7th International Ash Utilization Sym-
posium; May, 1985
21. Goodwin, R.W. ; "Ash from Refuse Incineration Systems: Testing,
Disposal and Utilization Issues"; presented at MASS-APCA 33rd Technical
Conference and Exhibition: Air Pollutants from Incineration and
Resource Recovery; Nov. 3-6, 1987; Atlantic City, NJ.
22. D. Gallagher, Burdc Associates; Personal Communications; 10/5/89.
23. McEnroe, B.M. and Schrocdcr, P.R.; "Lcachatc Collection in Landfills
Steady Case"; J. Snvir. Engr. Div.; ASCE; 1988, 114 (5); 1052-1062.
24. DcWaiic, F.E.; ct. al.; "Gas Production from Solid Waste Landfills";
J. Envir. Engr. Div.; ASCE; 1978, 104 (EE3); 415-432.
25. Gray, M.N.; Rock, C.A.; and Pcpin, R.G.; "Predicting Landfill
Leachatc with Biomass Boiler Ash"; J. Envir. Sngr. Div.; ASCE; 1988,
114 (2); 465-470.
25. Goodwin, R.W.; "Coal and Incinerator Ash in Pczzclanie Reaction
Applications"; presented at MSW Ash Utilization Conference
by Resource Recovery Report; Oct. 13-14, 1988; Tower Hotel
27. Forrester, K.; Whcclabratcr Tech.; Personal Communication; 10/5/89.
sponsored
Phila, Pa.
915
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VITRIFICATION OF
MUNICIPAL SOLID WASTE COMBUSTOR ASH
Ray S. Richards? and Gary F. Bennetts
aAssociated Technical Consultants, Toledo, Ohio.
t>Professor; University of Toledo; Toledo, Ohio.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13- 16, 1990
917
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Vitrification of Municipal Solid Waste Combustor Ash
Ray S. Richards and Gary F. Bennett
Introduction
Nationally there is a concern for pollution that may be caused by the
land disposal of solid and hazardous waste. Consequently, using the
authority given to them by RCRA, the USEPA is severely limiting land
disposal of hazardous waste. If land disposal is to be permitted, then
the disposer will probably be required to detoxify or to immobilize his
waste to the greatest extent possible. This requirement may well
apply to municipal waste combustor ash (MWC ash) For ash resulting
from the combustion of municipal solid waste , vitrification represents
immobilization of the toxic metals to the maximum extent possible .
Why Vitrification
The vitrification process produces a glass-like, non-leachable
material by melting municipal waste combustor (MWC) ash. This
process is not encapsulation! The ash feed materials are no longer in
their original form. Their physical and chemical form have been
changed. This process is similar to dissolving sugar in coffee; the
sugar crystals are gone and the flavor is changed. The glass exiting the
melter is usually a homogeneous material but some compositions can
partially crystalize on cooling. Both glasses and crystalline materials
can be very inert and unleachable.
There are at least two benefits in this process.
1. Reduction in volume
2. Delisting
-Very large reduction in surface area
(leaching surface).
-Production of chemically inert glass
MWC fiy ash densities have been measured^') at 0.37 to 0.73
gms/cm3 and bottom ashes were measured at 0.82 to 1.04 gms/cm3
Typical commercial glass densities are 2.6 gms/cnv
918
-------
Thus, there is a significant reduction in volume to be gained by
vitrification.
The surface area of the fly ash that may be exposed to leaching is
large. Moreover the toxic materials are deposited on the surface of the
particles. The vitrification process combines all of these surfaces into
a coarse non-leachable aggregate of minimum volume and surface area.
Occasionally MWC ashes exceed EP Tox and TCLP limits by modest
amounts (2). The dissolution of the toxic, materials on the surface of
the ash into the glass and the multiple orders of magnitude reduction in
surface area almost guarantee that any glass produced as a result of
vitrification will pass the required hazardous waste toxicity tests.
While the non-leachability of vitrified ash has not been certified by
innumerable tests, glass technologists have little doubt that non-
leachability can easily be achieved as it has been in the nuclear
industry.
Vitrification of high level nuclear waste hss been under study for
over 20 years. The leaching standards are much more strict than those
faced by MWC ash and acceptable levels of leach resistance have been
attained for nuclear waste.
There are concerns for the durability of other disposal methods.
Structural grade concrete bridges and roads may not last 20 years due
to freeze-thaw winter cycles. "Waste material" aggregate with
uncontrolled chemistry would be even more suspect. In contrast, our
Toledo Museum of Art has glass objects recovered from burial sites
thousands of years old which are in excellent condition.
Vitrification is the answer to municipal waste combustor ash
disposal.
Demonstrated Capability
Several companies are actively pursuing vitrification as a method of
MWC ash treatment. The following is a partial list of these companies.
Argonne National Laboratories
Argonne, IL
Penberthy Electromelt International. Inc.
Seattle, WA
919
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Westinghouse Electric Corp., Environmental System Dept.
Madison, PA
U.S. Environmental
Ml. Laurel, NJ
Vortec Corp.
Collegeville, PA
Geosafe Corp.
Kirkland, WA
Inorganic Recycling
Worthington, OH
Associated Technical Consultants in affiliation with Glasstech, Inc.
Toledo, OH
Gas Versus Electric Melting.
Commercial gas fired gl?ss melting furnaces, which might be
considered for MWC ash vitrification, utilize more than A million BTUs
of natural gas energy and generate over A tons of exhaust gasses for
each ton of glass produced. These figures are for very large, efficient
furnaces. The furnaces have large heat recovery systems and bag
houses for dust collection and require a great deal of capital
investment.
Smaller gas fired melters, called unit melters, are also available
without energy recovery systems. There is a significant increase in
fuel consumption for these furnaces over the larger units.
For more modest capacity melters, such as those appropriate for
MWC ash, electric melting is a better choice than gas fired melters.
Electric melters are smaller and cost less than a gas fired furnace of
the same capacity. While electric melters are efficient, they use an
energy source that normally costs over three times as much as natural
gas on a per ton melted basis. However, in MWC co-generation
facilities, the electric costs can be more attractive.
92O
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Special Applicability of Vitrification to MWC Ash
MWC facilities with co-generation of electricity capability present
a unique opportunity to utilize electric melting for vitrification
because their electric costs can be very reasonable. Some of the new
electric melter designs lend themselves to very rapid on-off operation.
This operational advantage will allow utilization of off-peak power.
It also is fortunate that most of the major oxide constituents of the
ash stream are good glass formers. Table 1 shows the weight percent
of the major components in the fly ash. One equipment supplier
recommends modest additions of cullet (scrap glass) to the ash feed
streams to adjust the melt chemistry for reasons described later.
Fly Ash versus Bottom Ash
Fly ash and bottom ash have different compositions and toxicities.
Many papers^-6) have been written on the chemical and physical
distribution of toxic metals in MWC ash. It is generally agreed that the
fly ash contains a larger portion of most of the toxic elements than
does bottom ash.
A typical waste-to-energy incinerator of 600 tons/day capacity will
produce approximately 150 tons per day of total ash. Of this total,
about 20%, or 30 tons per day, will be fly ash .
The high surface area of the fly ash, the distribution of the toxic
elements on the surface of the fly ash, and the lower weight of fly ash
per ton of waste as compared to bottom ash make it the waste stream
of most toxic concern and the most likely candidate for vitrification.
Table 2 shows the toxic metals present in the ash.
Typical Electric Vitrifying Units
Electric glass melters which are used for bottle, window, and
specialty glass around the world are available in a wide range of sizes.
In electric glass melting, molybdenum electrodes are inserted into the
molten glass and current is passed through the glass to heat it. There
are two different melter designs: cold top and hot top.
The cold top design is a refractory box which is open on top, full of
molten glass, with a layer of raw materials floating on top of the melt.
921
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This layer insulates the furnace top and is replaced as batch melts
away. There is a drain hole located elsewhere in the furnace which
removes the melted glass.
The second design is a fully enclosed furnace and uses some gas
firing or electric heating elements above the melt in addition to the
electrodes in the melt. This is called a hot top design.
Arc furnaces, typical of those used in steel melting, also have been
used for ash vitrification^) . Since steel making involves slag or glass
on top of the molten steel, it is reasonable to consider these units for
ash vitrification. Herb Hollander, Wyomissing, PA, is Chairman of an
ASME program which is evaluating the arc melting furnace for ash
vitrification. Arc furnsces operate with very high temperature zones
and can melt any residual metallic components in the ash. The plan is
to process both fly and .bottom ash with removal of the molten metallic
fraction from the bottom of the furnace.
Stir-ttelter™
Associated Technics! Consultants (ATC) and Glasstech, Inc. are
developing a highly stirred, electric melter (Stir-Mel ter™). This newly
designed electric melter will be used to melt MWC ash late this
summer. The work is being carried out by ATC with support from the
State of Ohio under an Edison Seed Fund Grant to the University of
Toledo. Glasstech, Inc. will manufacture and market the new Stir-
Nelter™furnaces. These furnaces are smaller than other electric
furnaces with the same capacity and are more easily sealed against
vapor loss than other furnace designs.
This new furnace is a small eletric melting unit with a high speed
stirrer to circulate the melt rapidly. This provides rapid melting rates
and uniform operating temperatures. The small size minimizes energy
consumption. They operate within a very narrow and tightly controlled
temperature range and thus allow significant control over chemical
reactions in the melting process. The Stir-Melters™ respond to
temperature and load changes quickly and can be idled or returned to
full production in minutes. In this regard, they are the most flexible of
the electric melters described.
922
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Operating Cost Considerations
The operating cost of an electric melter is highly dependent on the
actual cost of the 450 to 550 Kwh required to melt each ton of ash.
More energy may be required if high levels of additional materials are
added to the ash stream. Off peak power at co-generating facilities
should be very reasonable.
A second cost factor is the need for other materials to be added to
the ash feed stream. There can be several reasons for doing this. One
is to lower the melting point of the ash stream to make melting easier.
Another is to balance the chemistry to get a good durable product
(high leach resistance). While optimum glass chemistry has not been
determined and will vary from location to location, it seems reasonable
that the cost of additions to the feed stream will be modest.
The cost of vitrification was described in general terms above.
Exact costs depend upon size, electricity costs, and several chemical
factors which have not yet been resolved. Based on an in-house, off-
peak electricity cost of 2 cents/Kwh, it is our estimate that
vitrification direct costs will be between $50 and $60/ton of glass
output. One must remember that fly ash contains significant levels of
carbon and volatiles and that some additional materials may have to be
added to the ash stream. Our estimate is that 1 ton of fly ash will
produce 1.0 to 1.2 tons of glass.
Lastly, when more sophisticated end products are being
manufactured from the glass stream, there will be additions to
maintain a consistent chemical composition of the glass despite
seasonal variations in the ash stream . This will be discussed later.
Capital Costs
Approximations of capital costs for electric melters are not reliable
because of the large variations from site to site. The type of melter
selected will affect the plant space requirements, the ventilation and
exhaust gas processing needs. Mass burn incinerators will have
different types and quantities of ash than incinerators burning refuse
derived fuel. The incinerator combustion system will heavily affect
the percent of fly ash to total ash as well as the residual carbon
content.
923
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As a starting point, a furnace for vitrifying ash in the size range of
50 tons per day might cost from $ 1,750,000 to $2,500,000. If only fly
ash were being vitrified the capacity required for a mid-size
incinerator would be substantially less, although the cost per ton of
capacity would be somewhat greater. Beyond this, the requirements of
the individual site would need to be appraised.
Vitrification Concerns
The research currently underway at Associated Technical
Consultants addresses several of the chemistry problems inherent in
the vitrification of MWC ash. Although glass is known as the universal
solvent, readily incorporating lead, zinc, chromium, and selenium,
several toxic species can partially vaporize in addition to dissolving in
the melt. Consequently, air pollution control of the furnace effluent
will have to be considered. This is a problem that is routinely
addressed in commercial glass melting.
Fly ash can contain significant amounts of carbon. This can lead to
the reduction of some metal oxides to their metallic state and the
glass melting temperature is high enough to cause boiling of some of
these metals. For some tightly closed furnace designs, this is not a
difficult problem and the vapors can be condensed in fairly simple
systems. The concentrated condensate then can be recycled as a metal
source.
One groupie) reports the following data that illustrate the volatility
of two heavy metals:
Fly Ash Vitrified Glass
Cadmium 1000-2000 ppm 10 ppm
Lead 5000 " 100 "
In this case, the cadmium probably left the furnace in the exhaust gas
stream. The lead can either be lost to the exhaust stream or found as
metallic lead in the bottom of the furnace. The chlorides and sulfates
in the ash also may combine with some metal species which then
volatilize.
924
-------
From the perspective of a glass technologist, the extreme
variability of the ash stream chemistry makes melting control difficult
and yields a low quality glass output. For example, the concentration of
silica (SiOz) varies between 0 to 57% as shown in Table 1. At the low
end of silica concentration, sand will have to be added to the melt.
Other species such as chromium are locked in the glass structure
and are also in a non-toxic valence state.
By-Products
There have been proposals too numerous to detail on potential uses
for MWC ash as it comes from the combustor. Construction aggregate
uses predominate and ash is utilized for aggregate in many countries.
Bottom ash which has been sized and washed may be suitable for this
application. This aggregate is a relatively low value product. The
result is small cash return instead of an expense. Several other similar
uses have been proposed. There have been fewer uses suggested for fly
ash.
We at ATC-Glssstech feel that there are other products which can be
made from the vitrified ash stream that would have a higher value than
aggregate. However, these future higher value products, and indeed
some of the ones presently being discussed, will require that the glass
properties and thus its composition be under better control. This
control feature is not incorporated in current MWC installations. To
accomplish better ash chemistry control, stock piling and blending or
chemical sampling followed by corrective additions will be needed.
Long range developments will probably trend in this direction.
Summary:
Given the public concern for the potential impact of toxic chemicals
in the leachate on ground water, there is resistance to siting of land
fills. We feel that vitrifying of fly ash to produce a virtually non-
leaching product will enhance landfill acceptance or alternative uses.
In addition, discontinuing the present practice of mixing the potentially
hazardous fly ash with the bottom ash also should enhance the
acceptance of bottom ash for land fill or other uses.
925
-------
We feel that the Stir-Melter™ can effectively and economically
vitrify fly ash. Currently we are on a research and development
program to scale up a lab melter to a commercial melting unit.
Additional work will be conducted on producing higher value products
from the vitrified ash.
As we look to the future, it is our belief that production of useful
products from this vitrified ash can produce an economic benefit,
secure a concomitant reduction in disposal costs and lead to a
reduction of land disposal.
REFERENCES
1 J. L. Ontiveros, T. L. Clapp, and D. S. Kosson, "Physical Properties
and Chemical Species Distribution within Municipal Waste
Combustor Ashes," Environmental Progress, Vol 8, No. 3, 1989, 200
-206.
2 T. J. Clapp, J. F. Mageell, R. C. Ahlert, and D. S. Kosson, "Municipal
Solid Waste Composition and the Behavior of Metals in Incinerator
Ashes," Environmental Progress V7, No. 1, 1988, 22-30.
3 Cundari, "Laboratory Evaluation of Expected Leachate Quality from a
Resource Recovery Ashfill," Ash Disposal Workshop Proceedings.
A EPA, "Characterization of MWC Ashes and Leachates from MSW
Landfills, Monofills, and /Co-Disposal Sites," EPA 530-SW-87-028A,
Oct 1987.
5 Hjelmer, "Swedish Study", ref. unknown, data from Victor Pearson,
Argonne National Laboratories.
6 L. Penberthy, Personal communication, "Philadelphia Incinerator
Data"
7 T. Furukawa, E. Inagaki, S. Shimura, "Application of Electric Arc
Heating for Melting Treatment of Sewage and Municipal Incinerator
Residue," XI Congreso Internacional de Electrotermia, Malaga,
Espana, 1988.
926
-------
8 Russel Cepko, Westinghouse Elec. Corp; Environmental Systems Div.
Persona! Communication.
927
-------
TABLE 1 ASH COMPOSITION
Si02
CaO
A 1203
{§ F6203
CD
Na20
Ti02
MgO
K20
P205
_ ^*
ZnO
nun
WESTCHESTER (2
TOTAL ASH
RANGE
40.3-46.8
11.3-15.4
10.5-16.3
8.0-19,2
3.1-4.2
1.5-2.1
2.4-4.2
1.4-3.4
1.0-1.4
5) E.P.A.(4)
FLY ASH
RANGE
0.3-57
2-38
0.9-33.2
0.1-12
1.3-6,7
T-7.0
0.33-3,5
1.3-8.0
0.7-2.1
OTR 1 Q
,OO I :T
0 09-9. Q
SWEDISH (5)
RANGE
31.6-63.6
9.4-15.5
11.5-20.6
2.0-5.7
2.9-5.7
0.5-2.1
2.0-4.6
2.6-7.2
1.2-2.5
PHILADELPI-
32.8
13.1
21.9
2.0
9.3
2.2
2.2
10.9
2 2
/L. >£-
1.1
-------
TABLE
RANGES OF CONCENTRATIONS OF INORGANIC CONSTITUENTS
IN FLY ASH, COMBINED ASH. AND BOTTOM ASH
FROM MUNICIPAL WASTE INCINERATORS IN ng'g (ppm)
Parameter
Arsenic
Barium
Cadmium
Chromium
Lead
[Mercury
Selenium
Silver
Aluminum
Antimony
Beryllium
Bismuth
Boron
Bromine
Calcium
Cesium
Cobalt
Copper
Iron
Lithium
Magnesium
Manganese
Molybdenum
Fly Ash
15-750
88-9,000
< 5-2,2 10
21-1.900
200-26.600
0.9-35
0.48-15.6 -
ND-700
5,300-176.000
139-760
ND-<4
36-<100
35-5.654
21-250
13,960-270,000
2.100-12,000
2.3-1.670
187-2,380
900-87.000
7.9-34
2.150-21.000
171-8,500
9.2-700
Nickel | 9.9-1,966
Combined Bottom
and Fly Ash
2.9-50
79-2.700
0.18-100
12-1.500
31-36.600
005-17.5
0.10-50
0.05-93.4
5.000-60,000
<120-<260
ND.1-2.4
24-174
4.100-85,000
1.7-91
40-5,900
690-133.500
6.9-37
700-16.000
14-3.130
2.4-290
13-12.910
Bottom Ash
1.3-24.6
47-2.000
1.1-46
13-520
110-5.000
ND-1.9
ND-2.5
ND-38
5.400-53.400
ND-<0.44
ND
£5
5,900-69.500
3-62
80-10,700
1,000-133.500
7-19
880-10.100
50-3.100
29
9-226
929
-------
TABLE 2
RANGES OF CONCENTRATIONS OF INORGANIC CONSTITUENTS
IN FLY ASH, COMBINED ASH, AND BOTTOM ASH
FROM MUNICIPAL WASTE INCINERATORS IN pg'g (ppm)
PAGE TWO
Parameter
Phosphorus
sotas$ium
Silicon
Sodium
Strontium
Tin
Titanium
Vanadium
Yttrium
Zinc
Gold
Chloride
Country
Fly Ash
2,900-9,300
11,000-65,800
1.783-266,000
9.780-49.500
98-1,100
300-12.500
< 50-42,000
22-166
2-380
2.800-152.000
0.16-100
1.160-11,200
USA. Canada
Combined Bottom
and Fly Ash
290-5,000
290-12,000
1,100-33,300
12-640
13-380
1.000-28.000
13-150
0.55-8.3
92-46.000
USA
Bottom Ash
3,400-17.800
920-13,133
1.333-188.300
1,800-33.300
81-240
40-800
3,067-11.400
53
200-12.400
USA, Canada
ND - Not detected at the detection limit
Blank - Not reported, not analyzed for
Source: Literature (Volume IV) and Versar Study (Volume V)
930
-------
CONVERSION OF MSW INCINERATION ASH INTO CONSTRUCTION AGGREGATE
MEETING FEDERAL DRINKING WATER STANDARDS
Frederick H. Gustin, P.E.
Hugh P. Shannonhouse
Municipal Services Corporation
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13 - 16, 1990
917-A
-------
Conversion of MSW Incineration Ash Into Construction Aggregate
Meeting Federal Drinking Water Standards
by F.H. Gustin 1 and
H.P. Shannonhouse 2
Introduction
Opponents to municipal solid waste incineration cite two
major concerns with incineration. The first is the question
of ash quality and the presence of contaminants. The second
is flue gas emissions. This paper describes the program
developed by Municipal Services Corporation (MSC) to address
the first problem. The air quality control system industry
has addressed the second.
A recent estimate by the Leading Edge Report, as reported
in the June, 1990 issue of Solid Waste & Power Magazine,
indicates that the number of waste-to-energy plants in the
U.S. is expected to double by the year 2000, to about 350
plants. Total incineration capacity will reach approximately
250,000 tons of solid waste per day.
Frederick H. Gustin, P.E. is a Senior Project Engineer
with Municipal Services Corporation, 777 Franklin Road,
Marietta, Georgia 30067
Hugh P. Shannonhouse is President of Municipal Services
Corporation, a USPCI, Inc. subsidiary. USPCI, Inc. is a
wholly-owned subsidiary of the Union Pacific Corporation,
Bethlehem, PA.
-------
The number of plants in operation will increase by about
6.7 percent annually, while the annual throughput capability
will increase by 12 percent.
Along with an increase in incineration capacity, there
will be a corresponding increase in ash production. If a 75%
reduction in weight is assumed when municipal solid waste is
incinerated, the 250,000 tons of solid waste per day will
result in 62,500 tons of ash per day, or almost 23 million
tons of ash per year.
On the other hand, the number of permitted landfills in
the U.S. is expected to decrease. According to the EPA, there
«
are presently approximately 6000 solid waste landfills in
operation in the U.S. More than half of these existing
landfills will reach their capacities within the next six
years. Stricter federal and state standards, Superfund, and a
reluctance on the part of the general public to allow new
landfills to be built in the vicinity of populated areas all
play roles in the decline of the number of landfills that will
be in operation in the near future.
In addition, a general trend has developed for the
recycling and reuse of heretofore unusable industrial by-
products. Such materials as paper mill sludge, foundry sand,
Page 2
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municipal sewage sludge, and power plant coal fly ash and
bottom ash have all found beneficial and environmentally
benign uses over the past several decades.
It is for these reasons that Municipal Services
Corporation has decided to pursue the opportunity of recycling
MSW incinerator ash.
The MSC Program
The Municipal Services Corporation (MSC) program consists
of contracting for removal of 100% of the MSW incinerator ash
production from a waste-to-energy plant. The ash is
•
transported to another facility owned and operated by MSC
where metals are removed and the ash is converted into a
construction-grade aggregate material which can be used for
road construction or a variety of other uses. A small
percentage of the ash is unprocessible and requires by-pass
disposal.
The ash is first processed to remove metals and unburnt
paper and to produce a more consistent particle size. It is
then "chemically fixed" using K-20 3, which is a patented
3 Patented - U.S. Patent Office. The K-20 Lead-in-Soil
Contaminant Control System is a product of Lopat
Enterprises, Inc., Wannamassa, N.J.
Page 3
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product using a potassium silicate formula that causes heavy
metals to form metal silicates, thus permanently reducing
their solubility and therefore mobility in the environment.
The chemically-fixed ash is then mixed with other proprietary
ingredients and pelletized into smooth round pebbles ranging
in size from approximately 1/8 to 3/4 inch in diameter.
Following a curing period to provide for optimum strength
gain, the aggregate can be used in road construction or
elsewhere as permitted by the state environmental protection
agency.
Ferrous metals and mixed non-ferrous metals are
relatively clean and can be sold to scrap metal dealers, steel
mills, and foundries.
MSC has been awarded contracts by two counties in
Minnesota: Hennepin County, which encompasses the City of
Minneapolis, and Dakota County, just to the south of
Minneapolis. MSC will provide MSW incinerator ash recycling
services, including disposal of unprocessible residues, for up
to 90,000 tons per year of ash from the Hennepin County
incinerator and another 60,000 tons per year of ash from the
Dakota County incinerator.
Page 4
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Environmental Testing of MSC Synthetic Aggregate
In order for MSC to market the synthetic aggregate for
use in highway construction and elsewhere, it must first pass
stringent testing for both environmental safety and physical
performance characteristics.
During the course of product development, MSC has
subjected the synthetic aggregate to the following tests to
ensure environmental safety:
* Extraction Procedure Toxicitv Method 1310. or EP-Tox,
which was the standard EPA test by which a waste was
judged hazardous or non-hazardous. EPA has recently
dropped this test in favor of the TCLP test.
* Toxicitv Characteristic Leaching Procedure Method 1311.
or TCLP, which is similar to EP-Tox, but for which
results are more readily replicated from laboratory to
laboratory.
* Multiple Extraction Procedure. Method 1320. or MEP, which
is an indication of the stability of a material in the
environment over many years. The test is commonly
referred to as the "Thousand Year Leach Test."
Page 5
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* To a limited extent, MSC has tested for 2,3,7,8-TCDD and
2,3,7,8-TCDF, Method 8270. To date, these compounds have
not been detected in the aggregate.
Tables 1-3 show the results of environmental testing
performed by National Analytical Laboratories of Tulsa,
Oklahoma, on samples submitted by MSC.
Table 1 consists of a compilation of results of TCLP
analyses of nine samples of raw combined MSW incinerator ash
that MSC is presently working with in its Research and
Development Facility near Atlanta, Georgia. As expected, the
— •
variability of the ash is quite high.
Table 2 depicts the results of TCLP analyses on samples
of synthetic aggregate obtained from six consecutive batches
made at the MSC R&D Facility. Each batch varies slightly in
terms of mix design or treatment. Results were consistently
in the range of federal drinking water standards.
Also tested for leachability of heavy metals using the
TCLP were fines that passed through a No. 100 mesh when
samples of aggregate were screened. These results are shown
Page 6
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in Table 3. As was the case with the aggregate, results were
consistently in the range of federal drinking water standards.
Physical Testing of MSC Synthetic Aggregate
In addition to meeting strict environmental standards,
the MSC synthetic aggregate has been developed with the
objective of meeting the physical standards necessary to
withstand heavy traffic and harsh climatological conditions.
As MSC has been working towards the use of its aggregate in a
demonstration project in the State of Minnesota,
specifications in use by the Minnesota Department of
Transportation (MnDOT) have been used as the standard for
physical performance of the material.
The MnDOT battery of tests consists of the following:
* Los Angeles Abrasion Test fAASHTO T96) - a measure of the
aggregate's hardness and durability in relation to its
resistance to abrasion.
* Soundness by Use of Magnesium Sulfate (AASHTO T104) - a
determinant of the aggregate's resistance to chemical
attack, primarily road salt. To a certain extent, it is
also a measure of resistance to freezing and thawing.
Page 7
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* Freeze-Thaw fMnDOT procedure) - an indicator of the
aggregate's durability when exposed to a series of rapid
freezing and thawing cycles. The MnDOT procedure
consists of 16 rapid cycles of freezing and thawing of
the aggregate in a 0.5% solution of methyl alcohol in
water.
* Absorptivity - another indicator of freeze-thaw
durability, it is necessary in order to determine the
amount of excess asphalt required in a bituminous paving
mix to compensate for quantities absorbed by the
aggregate.
* Specific Gravity - A measure of particle density, it is
used for calculating bituminous paving mix proportions.
* Sieve Analysis (AASHTO T27) - different paving mixes
require varying particle size distributions. The MSC
synthetic aggregate is deficient in fine material (the
MnDOT BA-1 bituminous aggregate specification requires 2-
8% minus No. 200 mesh fines) , but this is easily
compensated for at the asphalt batch plant using fine
material from other sources, if needed.
Page 8
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Typical results showing ranges of values obtained using
the above test procedures are depicted in Table 4.
Minnesota Demonstration Project
The Minnesota Pollution Control Agency (MPCA) has drafted
a permit to authorize MSC and Hennepin County to jointly
conduct an MSW ash utilization demonstration project. The
permit is currently on 30-day public notice and it is
anticipated that it will be issued in July of this year.
The demonstration project will consist of the use of
approximately 80 to 100 tons of MSC synthetic aggregate as a
partial replacement for natural aggregate in a 2" thick
overlay of bituminous pavement. The synthetic aggregate will
be incorporated into the asphalt at a fixed rate, which will
be determined based on physical and environmental laboratory
testing.
The test strip will consist of paving approximately 1000
feet of roadway containing the synthetic aggregate and
approximately 1000 feet of standard roadway using only natural
aggregate. The natural aggregate roadway will be used as a
control for comparing data obtained from the physical,
Page 9
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chemical and environmental testing program that has been
developed in conjunction with the demonstration.
The synthetic aggregate was produced at the MSC Research
and Development Facility located near Atlanta, Georgia. It is
presently in the curing period before samples are shipped to
Minneapolis for testing by Braun Environmental Laboratories
and Braun Engineering Testing, subsidiaries of The Braun
Companies. Braun is an independent testing agency that has
been certified by the State of Minnesota.
The synthetic aggregate was produced from combined MSW
ash from the Hennepin Energy Resources Company facility (HERC)
in Minneapolis. Prior to transporting the ash to Georgia in
trucks, representative samples of the ash in each truck were
obtained for testing purposes. Four samples of the ash will
be analyzed using the TCLP for an extensive list of parameters
contained in Table 5.
In addition to TCLP analysis of the raw combined ash, the
TCLP will be performed on four samples of the synthetic
aggregate, the asphalt cement, the natural aggregate, and
samples of the synthetic aggregate that have been crushed into
powder.
Page 10
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The ash will also be subjected to analyses for dioxins
and furans using EPA Method 8290. This list of compounds is
contained in Tables 7 and 8.
Prior to construction of the roadway, a mineralogical
evaluation of the synthetic aggregate and of the crushed
synthetic aggregate will be performed.
Physical testing of the synthetic and natural aggregates
will be performed using the list of MnDOT procedures
previously discussed in this paper, in addition to physical
testing of the asphalt cement and the bituminous pavement
mixtures.
Braun will conduct trial mix design testing using
different proportions of synthetic and natural aggregates to
determine an optimum mix design. The optimum mix design will
then be subjected to a series of physical bituminous tests,
the most important of which will be the Cold Water Abrasion
Test.
The Cold Water Abrasion Test is used to determine the
durability of compacted bituminous mixtures and as an aid in
identifying mixtures that may have a tendency to strip or
unravel. The test consists of subjecting 6 cylinders of the
Page 11
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mixture to 1000 revolutions in the Deval Testing Machine using
cold water as a liquid medium. The amount of material lost
from the cylinders through abrasion is then calculated and
reported as abrasion loss percentage.
For purposes of this demonstration, acidic water (pH <5),
alkaline water (pH >9), and brine solution will be used as
media in addition to conventional tap water. The liquid and
particulates obtained from this series of tests will then be
analyzed for the short list of the eight RCRA heavy metals as
shown in Table 6.
Additionally, the following tests will be run on four
samples of the bituminous mix containing the synthetic
aggregate and four samples of the bituminous mix containing
the natural aggregate. These include:
* TCLP for the parameters listed in Table 5.
* Multiple Extraction Procedure using the TCLP for the
parameters listed in Table 5.
-/
* ASTM Water Leach Test (ASTM 1312) for the parameters
listed in Table 5.
Page 12
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All laboratory tests will be performed and the results
will be submitted to the MPCA for review and approval prior to
proceeding with construction in late August, 1990.
During construction, samples of the asphalt cement and
the bituminous mixture will be obtained from the bituminous
plant and tested. Results will be compared to those obtained
previously in the laboratory for verification.
Within 30 days of placement, core samples will be
obtained from both the synthetic aggregate roadway and the
control strip and tested for mineralogical composition as
previously described. ASTM Water Leach and TCLP testing will
•
be performed on the cores for the parameters in Table 5.
The test strip will be monitored for a period of five
years after construction. Each year, four core samples of the
test strip and the control will be obtained and subjected to
the TCLP and ASTM Water Leach Tests. In addition, an annual
analysis of the mineralogical composition will be performed to
detect any changes in the aggregate or in the pavement
structure due to changes in the aggregate.
Two high volume air samplers will be placed near the
roadway to detect if any of the materials contained in the ash
Page 13
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become airborne due to roadway wear. Soil samples will also
be obtained annually. Air and soil samples will be analyzed
for the list of parameters in Table 5. Background samples of
both air and soil will be obtained prior to construction.
A plan is presently being developed to evaluate the
quality of run-off and airborne emissions entering the
environment from normal wear and tear on the synthetic
aggregate roadway. The evaluation will use the data collected
from the physical and environmental testing conducted in this
project in a program of mathematical analyses and computer
modeling.
An additional 15 to 20 tons of the synthetic aggregate
will be trucked to Minneapolis and stockpiled outdoors on a
lined area. Samples of any air emissions and surface water
runoff from the stockpile will be collected and analyzed for
the list of parameters in Table 5.
After the synthetic aggregate roadway has been in place
for two years, results of testing will be reviewed by the
MPCA. The MPCA will then make the determination as to the
feasibility of proceeding with a full-scale ash processing
plant that will have the capability of processing up to
150,000 tons of MSW ash per year.
Page 14
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A permit application for construction and operation of
the ash processing plant, to be known as the Metropolitan
Resource Utilization Center (MRUC), has been submitted to the
MPCA.
Based on information and data generated during the course
of this project, a report will be prepared that can be
utilized in the preparation of a Health Risk Assessment for
the general use of the MSC synthetic aggregate in the state
of Minnesota. This report will be used during the preparation
of an Environmental Impact Statement (EIS) for the purposes of
evaluating any potential fugitive dust emissions from
•
synthetic aggregate roadways and the effects of any emissions
on the environment and human health.
MSC has volunteered to prepare the EIS on the full-scale
synthetic aggregate production plant that has been proposed as
well as potential utilization applications of the synthetic
aggregate product, in order to confirm the environmental
safety of the process. The Minnesota Pollution Control Agency
is the responsible governmental unit for scoping and managing
the EIS.
Page 15
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Results obtained during the course of this year's
demonstration project will be used not only in the preparation
of the EIS, but in the development of standards and
regulations for the use of MSW ash in the state of Minnesota
as well.
It is expected that the Minnesota demonstration project
and the EIS will result in what could be the most
comprehensive evaluation of MSW ash utilization to this date.
It is through this plan that Municipal Services Corporation
intends to lead the way in safely recycling the residues from
the combustion of municipal solid waste. This will extend the
lifetimes of landfill disposal sites by many years, thereby
helping to solve a pressing problem for incinerator operators
and municipal governments throughout the United States, as
well as safely returning a valuable natural resource to
commerce and industry.
Page 16
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Table 1
Results Of Toxicity Characteristic Leaching
Procedure (TCLP) Performed On Nine
Samples Of Combined MSW Incinerator Ash
National Analytical Laboratories
(All Units In mg/1)
Parameter
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Low
Value
<0.1
<0.01
<0. 01
<0.01
<0.1
<0. 0005
<0.1
<0.01
High
Value
<0.1
0.52
1.24
0. 36
19.1
0.0028
<0.1
0.02
Average
Value
<0. 1
0.31
0.60
0.09
5. 12
0. 0006
<0. 1
<0.1
Det.
Limit
0. 1
0.01
0.01
0. 01
0. 1
0.0005
"0.1
0.01
Note:
When results indicated parameter levels
below detection limits, one-half of the
detection limit was used for calculation
of the Average Value.
Page 17
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Table 2
Results of TCLP Analyses
Performed on MSC Synthetic Aggregate
National Analytical Laboratories
(All Units in mg/1)
Batch Number
Parameter
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Parameter
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
P-66
__
1. 28
—
—
0.004
--
—
— —
P-69
0.006
0.68
—
__
0.007
--
— —
— —
P-67
0.004
0.92
—
—
0.007
--
--
— —
Batch Number
P-70
0.005
0.57
—
0.01
0.007
--
—
— —
P-68
0. 003
0.78
--
—
0.004
--
--
— —
P-71
0.005
0.79
—
0.01
0.005
--
—
~ ~
Det.
Limit
0.002
0.01
0.01
0.01
0.002
0.0005
0.005
0.01
Det.
Limit
0.002
0. 01
0.01
0.01
0.002
0.0005
0.005
0.01
DWS
0.05
1. 00
0.01
0.05
0.05
0.002
0.01
0.05
•
DWS
0. 05
1.00
0.01
0. 05
0.05
0. 002
0. 01
0.05
Note: -- = Below Detection Limit
Page 18
-------
Table 3
Results of TCLP Analyses Performed On
Minus No. 100 Sieve Dust From
MSC Synthetic Aggregate
National Analytical Laboratories
(All Units in mg/1)
Batch Number
Parameter
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
P-53A
DUST
0.008
0.65
—
0.06
0.008
— —
— —
P-54B
DUST
0.70
—
0. 06
0. 01
Mi W
— —
P-58A
DUST
0.003
0.64
—
0.02
0.021
«. ..
•"• —
P-58B
DUST
..
0. 41
--
0.06
0.007
— —
. ...
Det.
Limit
0.002
0.01
0.01
0.01
0.002
0. 0005
0.005
0. 01
DWS
0. 05
1.00
0. 01
0. 05
0. 05
0. 002
0.01
0. 05
Note: — = Below Detection Limit
Page 19
-------
Table 4
Typical Results Of Physical Testing
Of MSC Synthetic Aggregate
Range Of Values MnDOT ,
Test For MSC Aggregate Requirement
L.A. Abrasion 25-35% Loss <40% Loss at
500 Revolutions
Soundness By MgSO4 5-10% Loss <15% Loss at
5 Cycles
Freeze-Thaw 3-18% Loss <12% Loss at
16 Cycles
Absorptivity 12-16% Not Specified
Bulk Specific Gravity 1.8-1.9 Not Specified
Sieve Analysis May be varied through Varies by
production techniques Application
Note: Physical testing performed at Law Engineering, Atlanta,
GA, and the MSC Research and Development Facility.
Page 20
-------
Table 5
List Of Parameters For Analysis
Minnesota Demonstration Project
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chloride
Cobalt
Copper
Chromium
Iron
Lead
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Nitrate + Nitrite
Phosphorous
Potassium
Selenium
Silicon
Silver
Sodium
Strontium
Sulfur (Sulfate-S)
Thallium
Tin
Titanium
Zinc
Table 6
Short List Of Parameters For Analysis
Minnesota Demonstration Project
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Page 21
-------
Table 7
List Of Dioxin Compounds For Analysis
Minnesota Demonstration Project
Polychlorinated Dibenzodioxins
Total Monochlorodibenzodioxin
Total Dichlorodibenzodioxin
Total Trichlorodibenzodioxin
2,3.7,8-Tetrachlorodibenzodioxin
Total Tetrachlorodibenzodioxin
1,2,3,7,8-Pentachlorodibenzodioxin
Total Pentachlorodibenzodioxin
1,2,3,4,7,8-Hexachlorodibenzodioxin
1,2,3,6,7,8-Hexachlorodibenzodioxin
1.2,3,7,8,9-Hexachlorodibenzodioxin
Total Hexachlorodibenzodioxin
1,2,3.4,6,7,8-Heptachlorodibenzodioxin
Total Heptachlorodibenzodioxin
Octachlorodibenzodioxin
Page 22
-------
Table 8
List Of Furan Compounds For Analysis
Minnesota Demonstration Project
Polychlorinated Dibenzofurans
Total Monochlorodibenzofuran
Total Dichlorodibenzofuran
Total Trichlorodibenzofuran
2,3,7,8-Tetrachlorodibenzofuran
Total Tetrachlorodibenzofuran
1.2,3,7,8-Pentachlorodibenzofuran
2,3,4.7,8-Pentachlorodibenzofuran
Total Pentachlorodibenzofuran
1, 2. 3, 4. 7, 8-Hexachlorodibenzofuran
1,2,3,6,7.8-Hexachlorodibenzofuran
2,3.4,6,7,8-Hexachlorodibenzofuran
1,2,3,7,8,9-Hexachlorodibenzofuran
Total Hexachlorodibenzofuran
1, 2, 3, 4, 6, 7, 8-Heptachlorodibenzofuran
1, 2, 3, 4, 7, 8. 9-Heptachlorodibenzofuran
Total Heptachlorodibenzofuran
Octachlorodibenzofuran
Total Mono-Octachlorodibenzofuran
Page 23
-------
LAND DISPOSAL
-------
COMMUNICATION, COMMUNITY PARTICIPATION AND WASTE MANAGEMENT
An Examination of Public Opinion, Citizen Participation,
Education and Communication Strategy in the Siting Process
Cynthia-Lou Coleman and Clifford W. Scherer
Department of Communication
Cornell University
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
931
-------
Communication, Community Participation and Waste .Management*
It just isn't enough for managers in the field of waste
siting to be good scientists, engineers or technicians.
Today's administrators better know how to effectively manage
staff, practice community relations, interpret public opinion,
arbitrate disputes, converse with news reporters, and plan
effective communication strategies.
The classic model of siting communication, top-down and
one-way, is outmoded. Yet some agencies continue to promote
such dated strategies only to find costly delays or even
abandonment of the project. Why do such methods no longer
work?
A review of waste siting case studies and journal
articles reveals that unsuccessful siting campaigns have in
common several, important factors — factors which are
*(Development of this paper was made possible by a special
grant from the Cornell University College of Agriculture and
Life Sciences.)
932
-------
critical to the success or failure of a siting strategy:
public opinion, citizen participation, continuing education,
and communication strategy. And while no one can guarantee a
successful outcome, those who have written about successful
outcomes agree that when these four factors are fused into a
workable plan, citizens are more willing to discuss siting
options.
This paper examines the literature and case studies on
siting of solid waste, hazardous and low-level radioactive
waste facilities. While we recognize that each type of siting
has its own unique problems in terms of public perception and
operation management, the issues of participation, public
opinion, education and strategies provide a common foundation
to all of the situations we have studied.
Public Opinion and the Perception of Risk
The attitudes which Americans have about the environment
serves as the backdrop to our examination of public opinion.
That Americans care deeply about the environment is well-
933
-------
documented in opinion polls. Cambridge Reports, for example,
notes that pro-environmental sentiment is pervasive among
American people, who were "somewhat abstract and aesthetic"
in their concerns about the environment 15 to 20 years ago.
Today, however, attitudes "grow out of deeply felt and
personal worries about human health and safety." Furthermore,
environmental threats are highly correlated with whether
people see problems as a threat to personal health and safety
(Cambridge Reports, 1988).
Not only have environmental concerns taken a prominent
position on the public agenda — the power to influence and
shape opinion in the environmental arena has grown
concurrently. The nuclear power industry is one example cited
frequently in the literature. American perceptions concerning
the health and safety surrounding nuclear power have become
increasingly salient, particularly after such newsmaking
events as Three Mile Island and Chernobyl. Californians, for
example, have rallied effectively in halting the reopening of
nuclear power facilities (Sussman, 1988).
Such attitudes extend beyond the realm of nuclear energy:
planners of radioactive, hazardous, toxic, and solid waste
934
-------
facilities also report considerable opposition to land use
siting.
The general public feeling of environmentalism, coupled
with self-interest, are important variables in the public
opinion-land use siting equation. When self-interest is
present, wrote Hadley Cantril in 1944, opinion is not easily
changed. And it is this self-interest which has a demonstrable
effect on attitudes (Newsom and Scott, 1985).
The issue of self-interest becomes critical when the
benefits of locating a waste repository are weighed against
the costs. Payne and Williams (1985) report that "Citizens
feel they are paying high costs (in perceived risks) for
benefits they do not receive in the same proportion." In
discussing benefit versus cost to the community, case study
writers agree that host communities bear a greater burden of
cost than accrued benefits. Moreover, host communities and lay
publics perceive "costs" as including unacceptable health and
safety risks.
935
-------
Risk Perception
Studies of risk perception by Slovic, Fischhoff and
Lichtenstein illustrate that the public's perception of risk
differs from scientific, quantifiable risks. For example, the
lay public overestimates exotic or catastrophic risks (deaths
due to nuclear power) while underestimating everyday risks
(deaths due to automobile accidents.) The issue of self-
interest also affects perception of risks... some types of
risks associated with greater reward or benefits are more
readily acceptable to publics.
Scientists and experts have difficulty dealing with what
they consider the lay public's inaccurate assessment of risk,
which is reflected in the case studies of siting failures. For
example, members of the New York siting commission, after
meeting with area residents over a low-level radioactive waste
site, were troubled by the vehement public response. One
commissioner called the reaction "hysterical" while another
said opposition would diminish "once people hear the message
that there's no hazard to the environment." Opposition did not
diminish, and local citizens to date have been effective in
936
-------
stymieing the siting process (Coleman, 1989).
Experts, like the New York commissioners, relied on the
traditional model of scientific persuasion, which involves
trying to convince publics that their attitudes about risk are
unfounded. Communication and risk scholars generally concur
that this technique doesn't work. Instead of persuading
publics of the low (actual) health risks of sitings, some
pragmatists have recommended offering compensation packages
to host communities. Zeiss, who studied 21 facility siting
attempts, reports that, due to the imbalance of cost over
benefit, compensation alone is not enough to cinch a siting
agreement. Zeiss proposes a package which includes
compensation and reduction of perceived community "costs" or
losses.
Another central aspect of risk perception is the issue
of voluntary and involuntary control. Slovic, Fischhoff and
Lichtenstein, 1987, note that acceptability of risk depends
on such factors as catastrophic potential, uncertainty,
familiarity and voluntariness. The literature supports the
notion that, when communities believe they have no voice in
the siting process, projects are doomed to fail. "Community
937
-------
control," write Matheny and Williams (1985), is a key element
in achieving acceptance.
The issue of community control is more than attitudinal,
however. According to researchers, community participation,
which leads to the perception of control, serves as a linchpin
in the siting process.
Citizen Participation
Common to much of the siting literature is the notion
that community publics play a vital role in land use siting.
But, judging from case studies, public input is either ignored
or invited too late in the siting process.
Planners need to examine siting "in a radically new way,"
suggests Edeburn, 1988. She calls on government agencies to
redirect their communication focus away from ratification to
input. "The public's role should be defined clearly,
preferably by citizens and officials together." Involvement
in the planning process, Edeburn adds, "leads to greater
understanding of, and appropriate reactions to, environmental,
health and economic risks." other experts agree. In writing
about knowledge versus NIMBY (Not in My Backyard) , Matheny and
938
-------
Williams make a strong case for involving the Florida public
at the decision-making level, noting that "it's largely a
matter of community participation in management" and that
residents and facility operators need to share in the
decisions about the disposal of wastes. Involving the public
at this level, the authors note, may not reduce risks, but
will shift the perception of risk "from an involuntary to a
voluntary consciousness."
Blackburn and Reed, 1985, take the example one step
further, suggesting that increased involvement by citizens in
the siting process leads to acceptance of the project. In
their study of a low-level radioactive waste facility siting
in Texas, the authors report that planners established avenues
for community comment early in the siting process. The purpose
of these meetings was not to reach consensus but to promote
11 free-flowing question and answer sessions," allowing planners
to hear concerns first-hand. Formation of citizen committees,
funding of surveys, and sponsorship of visits to disposal
sites paved the way for community involvement.
Abrams and Primack, 1980, suggest that timing is
important in citizen input. When comments are invited too
939
-------
early, "plans are vague," and if participation is requested
too late, the public perceives the project as a fait accompli.
Moreover, agencies are unfamiliar with how to involve citizens
throughout the process. "Often agencies don't know how to
maintain citizen input."
One solution borrowed from marketers, is segmentation of
publics. Abrams and Primack offer a blueprint of typical
publics, including local elected officials, business owners,
opinion leaders, scientists, special interest groups, etc. By
segmenting publics into special groups, planners greatly
increase their ability to understand audience needs while
identifying specific channels to each special publics.
Albrecht and Thompson, 1988, have examined the issue of
special publics more closely. In their paper on attitudes in
repository sitings, they note that citizens find meaning in
a community frame of reference. If researchers develop methods
to examine deep social values which people attach to their
communities, planners can build a more complete composite of
community concerns. It's not enough to interpret attitudes and
public opinion; planners need to understand against the
community influences and norms which influence beliefs and
940
-------
behaviors.
Three central themes appear in the literature concerning
involvement of publics in the siting process: reaching
consensus, willingness to negotiate, and segmentation of
publics.
Planners should resist trying to reach consensus on
issues, according to Payne and Williams. In their article on
conflict and public communication, the authors make a case for
incorporating citizen input to reduce long-term strife. And
while it may seem antithetical to waste managers, conflict has
a positive consequence, the authors report. "Managers should
not become discouraged... conflict is normal."
Another benefit to opening dialogue between planners and
citizens, according to Vincenti (1985), is that planners
thereby send signals to the public that they value the input -
- assuming planners take comments to heart. "Citizen
involvement must be more than just names on a register" and
public groups must be willing to spend time examining issues,
not just time sounding off, warns Vincenti.
One way to gain the most from citizen input is
segmentation of publics. Although this is best accomplished
941
-------
on a case-by-case basis, publics are typically divided into
these types of groups: concerned local citizens; involved
citizens (teachers, business owners, other professionals);
environmentalist groups; opinion leaders (official and
unofficial); news media; elected officials and
representatives; appointed officials; city, county and
regional planners; myriad government agencies involved in the
planning process; scientists, university professors and
experts; etc.
A critical public is the group of local officials,
whether appointed or elected. Blackburn and Reed note that
involvement of these key people in projects can greatly help
the siting process. New York planners bore the wrath of local
officials when the news media learned about low-level site
selection prior to local citizens and local officials. Because
they were snubbed in the siting process, local decision-makers
vowed to fight the state agencies.
Payne, 1984, notes that involvement of community groups
is more manageable than hammering out solutions with
individuals. Groups can bring concerns and priorities into
focus better than individuals. By segmenting publics,
942
-------
discovering their concerns and suggestions, and getting a
range of opinions, planners can get a better handle on salient
issues.
Involving the public, however, does not guarantee the
success of an unwanted landfill siting facility. Jubak, 1982,
points out that "Public participation can make a difference
in people's attitudes. It can raise the level of trust by
providing good information and a chance to get answers to
genuine worries. Trust is absolutely vital to siting a
facility." Yet, having an informed public does not necessarily
translate to successful siting. Matheny and Williams caution
that raising awareness may also "encourage the NIMBY syndrome"
and that "too much public involvement leads to rejection of
proposed sites." The authors suggest complementing public
involvement with a public education program in an effort to
gain acceptance of community sitings. We believe that public
education must happen prior to any specific siting activity.
Public Education
Matheny and Williams propose that the combination of
citizen involvement and education "is necessary for legitimate
943
-------
decision-making." Participation isn't enough without
enlightened decisions, they add. In California, for example,
a grassroots educational campaign paved the way toward public
acceptance of a low-level radioactive facility. Pasternak,
1985, notes that the state's well-planned campaign, which
focused heavily on targeted groups, "had a positive impact on
local government officials, leaders of the business community,
journalists, and other citizens in potentially affected
regions of the state." Public and private organizations joined
together to establish specific, concrete objectives in siting
a facility and educating California publics on radioactive
uses and disposal. The organization hosted a speakers bureau,
conferences and field inspection trips to acguaint publics
with disposal information. The League of Women Voters and
other groups sponsored public forums in several locations, and
lobby
In other education programs, Texas officials changed
their opinions following site visits to waste facilities; in
Pennsylvania, strategists worked directly with the news media
in developing a series of news programs on radioactive waste,
while communicating with concerned individuals via direct mail
944
-------
and by sponsoring programs for officials and leaders in 42 of
the state's 67 counties; and a state-wide education program
in Florida included promotion of "Amnesty Days," an event
which allowed citizens, small businesses, schools and local
governments to have small quantities of hazardous wastes
collected free of charge, bringing the siting issue into focus
for targeted publics and the news media.
Waste siting authors concur that special events,
educational programs, and targeted news stories must directly
tie in with forums which allow for public discussions. And
researchers also agree that communication must be truly two-
way and symmetric, to allow for give-and-take on both sides
of the waste siting issue. If these essential components —
public education, citizen participation, and an understanding
of public opinion and risk — are not well-grounded in the
siting management, communication strategies will fall short
of meeting the requisite goals.
945
-------
Communication Strategy
As we suggested earlier, planners who report successful
sitings borrow from the marketing, public relations and
strategy areas in designing effective communication
strategies.
Unfortunately, and too often, strategies rely on
techniques, rather than broad-based research and public input,
in developing effective strategies.
Working with news media, for example, is problematic for
many managers and planners. While the news media may provide
an effective and powerful source of informing publics, the
public media cannot be controlled by waste planners. The
controversial nature of siting does, however, guarantee
placement of such issues on the news media agenda, and it's
likely that the siting opposition will be adroit at obtaining
media coverage. Unfortunately, planners often lack the skills
to carry their messages to the news media, and resist or
refuse opportunities to present their case to reporters. In
the example of New York's Cortland County, siting opponents
effectively set the media agenda through a series of well-
946
-------
timed and targeted protests and recurring demonstrations.
Siting officials were less available and less willing to
discuss issues publicly with members of the press. Officials
were on the defensive, and their public posture in the press
reinforced this.
Waste facility managers can be more effective in their
relations with the news media, but are reminded that good
press relations are no substitute for dealing with targeted
publics face-to-face. In an article about the "new
environmental ism," Lukaszewski, 1989, points out that "Success
means keeping your own interests on the agenda." Reporters
generally want to explain both sides of controversy to their
audiences, but managers must take the initiative in addressing
concerns via the public press. "Start early, speak often, and
don't let*the other side get away with framing the issue for
the media," Lukaszewski counsels. Vincenti notes that
"Government cannot rely on news media to educate the plblic
on issues that may be controversial."
The issue, therefore, becomes one of information versus
education. While the news media may inform publics concerning
events, waste managers need to take over the reins for public
947
-------
education — and •this is best done prior to controversy
erupting on television or in the newspaper.
Communication strategists and public relations
practitioners can provide numerous, proven techniques for
channeling messages and information to audiences... public
service announcements, feature articles, special newsletters,
brochures, television talk shows, slide presentations — but
the literature supports the view that interpersonal
communication — face-to-face interaction with host community
publics — is the sine qua non of successful siting.
Recommendations
Local government officials are faced with a difficult and
unique situation. On one side is the need to make efficient
decisions in the best long-term interest of the community. In
the past that meant making the site selection, holding a
public hearing to discuss the decision with a few concerned
members of the community, and then proceeding with site
development. Today, however, the public is less trustful of
government and science and technology. Today the public
questions decisions more, and demands to be involve in
948
-------
decision-making. And while a full discussion of the issues
with members of the public and involvement of the public in
decision-making may appear to be inefficient, it is often not
only the best, but the only way communities can make effective
decisions on some issues.
Three recommendation emerge from this study.
1. Utilize community expertise. Treat the public as an
equal partner in decision-making. Encouraging and actively
using citizens advisory and study groups bring the public into
the decision-making process. It also helps focus attention on
the real issues and real risks involved in the siting of waste
management facilities. Focus should be on citizens who have
special expertise: the local cooperative extension agent or
educator may help develop an educational plan for the
community; a communication specialist at the local college or
university may help design an overall communication strategy;
local business owners may help develop a speakers bureau of
volunteers to talk with organizations about various aspects
of the program, etc.
2. Develop a team oriented approach. No one individual
or group can manage all the aspects of a community risk
949
-------
situation. Recognize and believe that others can contribute
valuable ideas to the discussion.
3. Keep the process open to the public. Even the hint of
secret decisions can destroy credibility and create an
adversarial feeling in the community. Every effort must be
made to make members of the community feel that "this is our
problem, we must make the decision."
4. Be proactive in your communication efforts. Take your
concerns to the public as soon as you can. Don't wait for the
final study or more information. Be honest — if you don't
know, say so and explain why.
950
-------
Bibliography
Abrams, N. E. and J. R. Primack. "Helping the Public Decide: The
Case of Radioactive Waste Management." Environment; April
1980.
Albrecht, S. L. and J. G. Thompson. "The Place of Attitudes and
Perceptions in Social Impact Assessment." Society and Natural
Resources; 1988.
Blackburn, T. W. and J. B. Reed. "Local Government Participation
in the Siting of a Low-Level Radioative Waste Disposal
Facility: The Texas Experience." Roy G. Post, editor. Waste
Isolation in the US, Technical Programs and Public
Participation. 1985.
Brem, S. and A.L. Rydant. "Not in My Backyard: Siting a Regional
Solid Waste Landfill." Studies in New England Geography,
Number 4; October 1988.
Coleman, C-L. "What Policy Makers Can Learn from Public
Relations Practitioners." Public Relations Quarterly; Winter
1989-90.
Davis, C. "Perceptions of Hazarous Waste Policy Issues Among
Public and Private Sector Administrators." Western Political
Quarterly; 1985.
Edeburn, M. "Getting the Nod for Waste Disposal." American
City & County; November 1988.
Fitzpatrick, T. B., editor. "How Environmental Concerns Affect
Consumer Behavior," Canbridge Reports, 1988.
Forester, J. "Mediated Negotiation: Neither Panacea nor Hand
Maiden" (A Review of L. Susskind et al., "Resolving
Environmental Regulatory Disputes"; December 1984.
951
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Forester, J. "Planning in the Face of Conflict: Negotiation and
Mediation Strategies in Local Land Use Regulation." APA
Journal; Summer 1987.
Furuseth, O. J.; M. S. Johnson. "Neighbourhood Attitudes Towards
a Sanitary Landfill: a North Carolina Study."
Applied Geography; 1988.
Heiman, M. K. "Not in Anybody's Backyard: The Grassroots
Challenge to Hazardous Waste Facility Location." 85th Annual
Meeting of the Association of American Geographers; 1989.
Jubak, J. "The Struggle Over Siting." Environmental Action;
February 1982.
Lukaszewski, J. E. "Is Your Company Ready for the New Activism?"
New Jersey Bell Journal; Winter 1989-90.
Marks, N. S. "Citizen Enforcement of Environmental Laws."
Environment; June 1987.
Matheny, A. R. and B. A. Williams. "Knowledge vs. NIMBY:
Assessing Florida's Strategy for Siting Hazardous Waste
Disposal Facilities." Policy Studies Journal; September 1985.
Newsom, D. and A. Scott, "This is PR," Wadsworth Publishing
Company, Belmont, California, third edition, 1985.
Pasternak, A. D. "California's Response to the Low-Level
Radioactive Waste Policy Act of 1980: Policy and Progress."
Roy G. Post, editor. Waste Isolation in the US, Technical
Programs and Public Participation. 1985.
Payne, B.A. and R.G. Williams. "Conflict, Public Communication, and
Radioactive Waste Management." Roy G. Post, editor. Waste
Isolation in the US, Technical Programs and Public
Participation. 1985.
Payne, B. A. "Estimating and Coping with Public Response to
Radioactive Waste Repository Siting." Waste Management '84;
1984.
952
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Pojasek, R. B.; M. Lefkoff. "Stepping Beyond Public
Communications." Roy G. Post, editor. Waste Management 85.
Slovic, P., B. Fischhoff and S. Liechtenstein. "Behavioral Decision
Theory Perspectives on Protective Behavior." Taking Care:
Understanding and Encouraging Self-Protective Behavior; 1987.
Sussman, B. "What Americans Really Think," Pantheon Books, New
York, 1988.
Vincenti, J. R. "A Perm State Continuing Education Program on
Low-Level Radioactive Waste Disposal and Management: Lessons
Learned." Roy G. Post, editor. Waste Isolation in the US,
Technical Programs and Public Participation. 1985.
Willard, D. E. and M. M. Swenson. "Why Not in Your Backyard:
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Conference on Hazardous Waste Facility Siting; June 1982.
953
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"CONSIDERATIONS IN THE DESIGN OF LINERS
FOR MUNICIPAL SOLID WASTE LANDFILLS"
Charles D. Miller, P.E.
Rogers, Golden & Halpern
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 14-16, 1990
955
-------
INTRODUCTION
Landfill containment systems consist of liners in combination with a
system for withdrawal and treatment of landfill leachates. Residues from
the treatment of leachate are returned to the landfill. In the idealized
landfill, liners are impermeable and treatment of leachate insures that no
contaminants are released to the environment. In practice, impermeable
liners do not exist. Consequently, the landfill developer is faced with a
variety of landfill design alternatives that offer a trade-off between cost
and containment efficiency.
Conventional landfill liners consist of layers of clay or synthetic
membrane intended to impede the release of leachate. Composite liners
include a clay layer overlain by a synthetic membrane (See Figure 1).
Different liner types vary greatly in their capacity to contain leachate and
in their cost of construction. In choosing a containment system suited to
his specific needs and conditions, the landfill developer should evaluate
the degree of containment required to prevent significant contamination of
soil or groundwater.
CONTAINMENT
Impermeable liners do not exist. Normal migration of leachate through a
liner as anticipated by the designer is termed "permeance" to distinguish it
from "leakage", which is the product of imperfections or damage sustained by
the liner.
Most conventional liners are designed with leachate collection systems
that will limit the depth of leachate over top of the liner to about one
foot. Under these conditions, a carefully constructed liner consisting of a
two-foot layer of remolded clay with an in-place permeability of
956
052/040690
-------
FIGURE 1
LINER TYPES
Single Single
Clay Synthetic f Composite^
<••••••••**••••• •**
.••••*»•••••*•• ••*
^//S/f//,
RGH
957
-------
1 x 20"^ CM/SEC will sustain a permeance of about 16,000 gallons of
leachate per year per acre (GPY/AC). Flaws in the clay liner resulting from
poor compaction, desiccation or fissuring may result in leakage flow which
is much higher.
By contrast, a liner consisting of a 40 mil (.0035 foot) layer of
synthetic membrane should permit no more than 100 GPY/AC of permeance when
the maximum depth of leachate on top of the liner is one foot (See Figure
17
2). This permeance rate is based on a hydraulic permeability of 1 x 10"1Z
CM/SEC for a typical synthetic liner material. Liner permeabilities are
difficult to measure and may be significantly lower in many cases. The
superior containment properties of synthetic membrane liners are partially
offset by the vulnerability of these materials to damage during
construction. For membrane liners constructed over a subbase consisting of
soil with a permeability of 1 x 10"5 CM/SEC, only eight penny-sized holes
per acre are required to reduce the containment efficiency to that of a
two-foot layer of clay (K.W. Brown et al. Quantification of Leak Rates
through Holes in Landfill Liners. 1987. EPA/600/S2-87/062). Moreover, only
16 holes the size of a pinhead may be just as damaging. The task of
constructing synthetic liners to eliminate such tiny imperfections is
daunting. In practice, some damage to liners during construction must be
anticipated.
LEAK MINIMIZATION
Leakage flow is the result of imperfections in a liner. As previously
discussed, leakage can occur in liners constructed of either clay or
synthetic membrane materials. The rate of leakage flow is directly
proportional to:
1) depth of leachate over the liner
2) size of the imperfection
3) permeability of the underlying subbase (membrane liners only)
958
052/040690
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FIGURE 2
LINER PERMEANCE
r
2'
Clay
41
Clay
40 mil PVC (.0035')
16.000 GPY
AC
8.000 GPY
AC
100 GPY
AC
Note: EPA "De minimus" rate = 300 GPY/AC RGH
* Not Leakage
959
Rogvn, OoUtenftHalpvrn
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Of course, the first line of defense against leakage is the careful
construction and inspection of the liner system. Quality assurance programs
for liner construction should be rigorous and well documented. Detailed
construction specifications and extensive testing of in-place liners are
essential to eliminate problems associated with bad materials, poor
workmanship, or accidental damage to liners.
Effective methods of reducing leakage include reduction in the depth of
the leachate on top of the liner. This can be accomplished by either
utilizing a more permeable drainage medium, or by reducing the spacing of
leachate withdrawal conduits. New products that incorporate geotextiles and
plastic grids offer relatively inexpensive methods of improving the
effectiveness of leachate collection systems.
An alternative method of reducing leachate leakage is to construct a
double liner. The double liner incorporates two liners of identical design,
with one immediately overlying the other. Double synthetic membrane or
double clay liners are commonly found in current landfill designs. Since
leakage through the upper or primary liner will be a small fraction of total
leachate generated, the depth of leachate over the lower or secondary liner
will always be much less than that over the primary Liner. The potential of
leakage from the combined system is thus proportionately decreased. The
effectiveness of double liners is further enhanced by the probability that a
flaw in the secondary liner will not directly underlie a flaw producing a
leak in the primary Liner. In practice, a ten-fold improvement in overall
containment efficiency of double Liners compared to single Liners can be
anticipated.
The influence of puncture diameter in synthetic membrane liners is much
less important than the permeability of the subbase in determining the
importance of leakage flow. Decreasing the diameter of a puncture by an
order of magnitude will only cut leakage flow in half. By comparison, an
order of magnitude reduction in subbase permeability, without any reduction
in puncture size, will reduce leakage flow by an order of magnitude also
(K.W. Brown et al. Quantification of Leak Rates through Holes in Landfill
Liners. 1987. EPA/600/S2-87/062. This suggests a method of compensating
052/040690
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for the vulnerability of synthetic membrane liners to leakage related to
small perforations which may escape detection. By utilizing a low
permeability subbase in combination with a synthetic membrane liner, a liner
with containment efficiency and reliability that is superior to both clay or
synthetic liners can be achieved. This is the composite liner.
Figures 3 and 4 illustrate the effectiveness of different strategies for
the reduction of leachate leakage. The optimal strategy for a landfill
developer will depend upon the local costs of construction. However, the
adoption of composite liner designs will in most cases produce the greatest
improvement in containment efficiency per dollar spent. Composite liners
are most attractive in localities where clay is relatively inexpensive.
HYBRID LINER DESIGNS
Hybrid liners, first cousins of double liners, have gained acceptance in
various designs. Like double liners, hybrid liners are composed of two
liners with one system directly overlying the other. However, in hybrid
designs the two liners are constructed of different materials and have
inherently different containment efficiencies.
There are two philosophies of hybrid liner designs. The first approach
is to place the liner with the greatest containment efficiency on top.
Examples are synthetic-over-clay liner and composite-over-synthetic liner.
In these designs, it is typical to describe the upper drainage layer that
overlies the upper liner as the leachate collection system, and the lower
- drainage layer that occupies the space between the upper and lower liners as
the "witness" or "leak detection" system. The implication is that the
"witness" layer is intended to verify that the containment system is
working. Since all liners have a normal permeance flow, this approach
introduces the possibility that the detection of normal leachate flow in the
"witness" section will be misinterpreted by regulatory or third party
observers as a liner failure. Since the lower liner is acknowledged to have
961
052/040690
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FIGURE 3
EQUIVALENT LEAKAGE
MINIMIZATION STRATEGIES
(Reduction of Leakage Flow by 90%)
Synthetic Liner:
_ 4 . 4 _ ,
Containment Enhancement
Synthetic
Double Single *
Synthetic Composite
* Sublayer permeability lower than native soil by one order of magnitude
962
Bogan, GeJdnt ft HoJp*
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FIGURE 4
EQUIVALENT LEAKAGE
MINIMIZATION STRATEGIES
(Reduction of Leakage Flow by 90%)
Clay Liner: Containment Enhancement
,10t
i I
t
Double
Clay
* Reduction in leakage flow typically exceeds 90%
Single *
Composite
963
Begw*. «old»n It Ho»p«n
-------
a lower containment efficiency, it also difficult for the landfill operator
to argue that leachate observed in the "witness" system does not constitute
a threat to the environment.
The alternative approach in hybrid liner design is to place the liner
with the greatest containment efficiency on the bottom. The most common
example of this type is the synthetic-over-composite liner design. In
effect, this a double synthetic liner constructed over a clay subgrade
layer. In this configuration, like the double liner design, it is natural
to regard the lower liner as an integral part of the leachate containment
system. The lower drainage layer, which lies between the upper and lower
liners, is properly described as a "secondary leachate collection" system.
Leachate observed in the "secondary leachate collection" system does not
reflect a failure of the containment system and is anticipated in the
provision of an amplified secondary liner.
ELIMINATING WEAK POINTS
The leachate containment strategy for a landfill extends beyond the
selection of a liner type. The overall design must be examined to minimize
weak, failure-prone elements. Among the most important considerations is
the design of the leachate collection system. Most conventional designs
require that piping associated with the leachate collections system
penetrate the liner at three points (See Figure 5). The advantages of these
designs is that the leachate flows by gravity to the treatment works.
However, penetrations are difficult to seal reliably and are prone to damage
associated with settlement of the landfill and its foundation. Potential
problems associated with penetrations can be minimized by reducing the
number of penetrations, providing for local monitoring of penetrations,
adding secondary containment at penetrations, and by making penetrations
more accessible to repair in the event of a leak. The single penetration
design, illustrated in Figure 5, satisfies these requirements.
Alternatively, all penetrations can be eliminated by the introduction of
on-liner sump pumps.
052/040690 964
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The vulnerability of synthetic membrane liners to damage during
construction has been well documented. The most common cause of liner
perforation, other than negligent construction practices by the installer,
is the puncture or abrasion of liners by coarse rock fragments in granular
liner subbase or cover material. Recent research by the EPA (D.L. Lane, et
al. Loading Point Failure Analysis of Geosynthetic Liner Materials. 1988,
CER1-88-20. Proceedings of USEPA 14th Annual Research Symposium,
Cincinnati, Ohio.) has shown that all liner materials are vulnerable to this
sort of damage. However, by providing a geotextile sheathing for the liner,
puncture and abrasion resistance can be significantly improved.
Furthermore, the use of geotextiles is much more effective in improving
puncture resistance than is increasing liner thickness. The landfill
developer should consider the potential improvement in containment
efficiency that can be obtained at the cost of incorporating geotextiles in
the liner design.
Construction-related and post-construction damage to liners can also be
minimized by eliminating hard or brittle materials from the leachate
containment and collection system. Among these are brittle plastic pipes
and steel or concrete manholes and sumps. The entire containment and
collection system should be engineered to deform without failure due to
yield, puncture, or misalignment. To the extent possible, plastics used in
the construction of the liner should be compatible so that penetrations,
extensions, and connections can be sealed with confidence.
QUALITY CONTROL
The reliability of any containment system depends upon the quality of
the construction All landfill construction projects should incorporate a
detailed construction specification coupled with rigorous inspection and
documentation. Synthetic liners are the easiest of the liner types to
inspect, but also the most prone to damage during construction. Landfill
052/040690
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developers should insist upon the testing of 100 percent of all liner
seams. In addition, destructive testing of randomly selected coupons of the
seams should be conducted. Where double or hybrid liners are installed and
the base of the landfill is gently sloping, pond testing of the liner prior
to acceptance should also be considered.
Clay liners are more difficult to inspect, since small inhomogeneities
in a clay layer may escape a gridded sample coring and testing program.
Furthermore, flaws associated with dehydration or variation in moisture
content may be difficult to identify. Consequently, a very rigid
construction specification, including frequent measurement of clay
composition, moisture content, and compacted density is the best protection
against poor liner performance.
LANDFILL FAILURES
The only accepted evidence for liner failure is the measurable release
of contaminants into the environment. This usually is associated with the
detection of degradation of groundwater or surface water resources by a
network of monitoring wells and stream sampling points. The observation of
leachate in "witness" or "secondary leachate collection" systems does not
indicate a failure of the landfill's containment system. A certain amount
of permeance and leakage flow into these systems should be anticipated as a
normal feature of any liner design. However, unexpectedly large leachate
leaks in the upper liner should be regarded as indicating potentially
significant flaws or damage to the system as a whole and should be
investigated by expanding and intensifying monitoring functions. It is one
of the responsibilities of the landfill designer to establish realistic
estimates of line permeance and leakage against which containment permeance
can be judged.
966
052/M0690
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FIGURE 5
PENETRATION DESIGNS
No Penetration
Design with Pumping
Three Penetration
Design (gravity)
e-
Single Penetration
Design (gravity)
ROH
967
Degws. Gold*n * Holpwn
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CONTROLLED LANDFILLS - A SYSTEMATIC APPROACH TO
SOLID WASTE DISPOSAL
by
Frederick G. Pohland
Department of Civil Engineering
University of Pittsburgh
Pittsburgh, PA 15261
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
969
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Introduction
Landfills are and will likely continue to be the most frequently
employed method for disposal of solid wastes. Unfortunately, landfills have
not been managed well in the past, and that lack of good management has
resulted in problems with leachate and gas migration and adverse
environmental impacts. As a consequence, the continued use of landfills has
become a major societal issue which has often stifled or delayed the
development of new solid waste disposal systems. Yet these same concerns
have led to a variety of technological developments, ranging from landfills
designed and operated for total containment and isolation to controlled
disposal. Therefore, the choice of technology applied today is often
dependent on not only designer preference, but a desire to accommodate public
perception, economic constraints, and regulatory inertia. In the final
analysis, the relative priority and effectiveness of integration of each of
these elements determines which landfill management option is selected and
successfully implemented.
This presentation provides a review and summary of the nature of
landfills as potential generator sources of leachate and gas, and couples
this with a discussion of the relative merits of available techniques for
containment, control and treatment. It begins with a brief perspective of
the nature and characteristics of landfill leachate and gas, and the factors
affecting their magnitude and intensity. This is followed by a discussion of
the principles of controlled landfill stabilization as provided by in situ
leachate management with leachate containment, collection and recycle.
Finally, options for ultimate disposal or utilization of leachate and gas are
addressed, including discharge to municipal wastewater treatment systems,
land application, and energy recovery.
General Perspective
The development of rational, economically sound and publicly acceptable
approaches to landfill disposal of solid wastes involves the recognition that
a given landfill potentially will affect and be affected by prevailing site-
97O
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specific hydrologic and geologic conditions that must be understood in order
to minimize human health and environmental risks. The environmental
consequences of leachate and gas formation and potential migration, and their
dependence on the availability of moisture from external sources as well as
from associated waste decomposition, are of particular importance.
Therefore, leachate and gas generation must be controlled to transform
landfill behavior from a realm of uncertainty to one of predictability.
Such predictability is enhanced by understanding the causes for changes
in the magnitude and intensity of leachate and gas production as the landfill
matures and progresses through a sequence of microbially-mediated phases
toward stabilization. Operational control over the release of waste
constituents is possible either through the preselection or conditioning of
the source waste, or by management of the rates of generation and transfer of
waste constituents to the principal transport media (leachate and gas). The
latter approach appears to be a more logical choice in the case of municipal
landfills, whereas the former, perhaps coupled with features of the latter,
would seem more attractive for codisposal landfills receiving inputs of both
municipal and industrial wastes or where source separation or recycle are
practiced.
Based upon an understanding of the processes determining leachate and
gas characteristics, management of generation and transfer rates can be
implemented by controlling the moisture regime within the landfill. Without
moisture, a principal transport medium will not exist and the conversions and
interactions determining leachate and gas production and quality, as well as
the overall progress of waste stabilization, will be suppressed. Such "dry"
landfills, whether induced by climatic conditions or impervious containment
systems (liners and caps), may reduce the rate, amount and intensity of
leachate and gas generation, but may also extend the intrinsic reactivity
and, therefore, the environmental impact uncertainty into perpetuity. In
contrast, the availability of sufficient moisture, either accompanying the
waste or permitted to accumulate under controlled conditions during
971
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operations, may be used to advantage to: accelerate the inherent processes
producing and converting leachable constituents; extract waste constituents
and reaction products from the waste mass; dilute out inhibitory and/or
refractory; distribute microbial seed, nutrients or buffer capacity necessary
for viable microbial activity; and, transport residuals for ultimate
treatment or disposal. Because of the attendant acceleration of the
microbially-mediated conversion of the waste constituents and the contracted
time for stabilization of the readily available organic substrates, rates and
amounts of gas production are concomitantly increased, thereby encouraging
energy recovery and utilization. Such "wet" landfills create opportunities
for innovative design and operation as a controlled biochemical systems which
enhances predictability and minimizes long-term liabilities after closure.
Implicit in this latter management concept are requirements for
containment and ultimate removal, disposal or utilization of the leachate and
gas residuals. Current technology provides a sufficiency of techniques for
containment with natural or fabricated liners and for leachate and gas
management with collection, distribution and treatment systems. Ultimate
disposal requires an inspection of the sensitivity of the eventual
environmental receptor, whether it be the land, water or air. With
prevailing regulatory constraints and implementation of state-of-the-art
technology, all of these potential receptors may require some degree of
residual pretreatment before ultimate disposal of leachate or gas is
acceptable. Such pretreatment can be best provided by either on-site or off-
site engineered systems that have the flexibility to accommodate the
predicted and actual changes in leachate and gas characteristics.
Characterization of Landfill Stabilization
As indicated previously, most landfills progress through a series of
rather predictable stages or phases of stabilization, the longevity and
significance of which are determined by local conditions and the operational
strategies being applied either externally or internally. Fortunately, these
phases can be detected and monitored by leachate and gas analyses which are
972
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physically, chemically and biologically interrelated.
To direct the choice of analyses to be employed to characterize a
particular phase of stabilization, it is necessary to recognize that a
landfill exists throughout most of its active life as an anaerobic
microbially-mediated process. This process is analogous in principle to an
anaerobic batch digester, with limited inputs or outputs except for the solid
waste originally deposited and the moisture which may have gained access by
infiltration, and the eventual leachate and gas production and their possible
migration. In a sense, therefore, landfills become large, long-term,
anaerobic leach-bed reactors consisting of compartments or cells that
progress through the various stabilization phases at different rates and
somewhat independently, unless influenced by operational control or connected
by an absence of confining barriers. If connected, the principal transport
media (leachate and gas) tend to merge and dampen oscillations in
characteristics, yielding a combined and temporally-averaged leachate and gas
quality for the contiguous cells.
Phases of Landfill Stabilization. Using the anaerobic process analogy,
and recognizing that the functional retention times for landfills extend over
periods of years rather than days, it is possible to describe landfill
stabilization on the basis of certain performance-related and time-dependent
descriptors. Accordingly, most landfills experience a lag or initial
adjustment phase which persists until sufficient moisture has accumulated to
encourage the development of a viable and abundant microbial community. The
evidence of this adjustment phase is first apparent with the initial
production of gas (mainly carbon dioxide), possibly accompanied by elevated
temperatures due to incipient aerobic conditions. The existence and relative
persistence of elevated temperature serves to catalyze the initial microbial
activity, but ordinary is short-lived, depending on the insulating conditions
prevailing within the landfill system and the opportunity for dissipation of
heat. This lag phase becomes more evident when leachate is formed and
released after "indicated field capacity" is reached. Thereafter, further
973
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incremental saturation of the waste mass with moisture and the concomitant
distribution of nutrients will promote the development of an active anaerobic
and interdependent microbial consortia of acid-forming and me thane-forming
bacteria in each compartment of the landfill. The evidence of this consortia
will be manifested in the changes in magnitude and intensity of various
indicator parameters used for leachate and gas characterization. As readily
available supporting substrates are exhausted, these changes become
diminished and the associated indicator parameters will reflect an approach
to stabilized conditions. Accordingly, five sequential stabilization phases
can be described in this manner and include: Initial Adjustment (Phase I);
Transition (Phase II); Acid Formation (Phase III); Methane Fermentation
(Phase IV); and, Final Maturation (Phase V).
Since this sequential development is a natural landfill phenomenon, all
of these phases are encountered at one time or another in landfills receiving
municipal solid waste, provided that the associated microbially-mediated
conversion processes have a sufficiency of moisture and nutrients and are not
inhibited. As indicated previously, because the manifestations of these
phases often overlap within a landfill setting, it has become customary to
characterize them in a combined fashion. This has tended to obscure and
limit a mechanistic understanding of landfill behavior and the corresponding
potential for the operational control necessary for process optimization.
Moreover, no landfill has a single "age", but rather a family of different
ages associated with the various landfill cells as they evolve toward final
maturation.
The rate of evolution through the phases of stabilization, as
determined by leachate and gas analyses, will vary depending not only on
waste characteristics, but on the physical, chemical and microbial conditions
established within each cell with time. For example, low pH conditions
established during acid formation (Phase III) may delay or preclude the onset
of active methane fermentation (Phase IV), inhibition or retardation of
microbial activity may be induced by the presence of toxic substances, and
974
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high physical compaction or the use of impermeable intermediate and final
covers may restrict the movement and accessibility of moisture and essential
nutrients. Collectively, these constraints could decrease or neutralize the
in situ mechanisms of attenuation and assimilation responsible for
stabilization of the waste constituents, prolong the time required for
ultimate stabilization to occur, and extend the period and uncertainty of
environmental liability after site closure.
Indicator Parameters. A variety of indicator parameters may be used
to detect and describe the presence, intensity and longevity of the phases of
landfill stabilization. Many of these apply for the analysis of leachate and
whether physical, chemical or biological, each has a particular utility and
significance in terms of monitoring and control. For instance, of those
parameters included in Table 1, pH and ORP are physical parameters indicative
of acid-base and oxidation-reduction conditions, respectively, and important
in evaluating the acid formation and methane fermentation phases (Phases III
and IV); COD and BOD5 are chemical and biological parameters, respectively,
but are both indicative of relative leachate strength and biodegradability;
and, nitrogen and phosphorus are chemical parameters important in the
determination of nutrient sufficiency and condition (aerobic/anaerobic) of a
particular phase. Similar importance can be assigned to the other parameters
such as alkalinity (buffer capacity), heavy metals (potential inhibition),
conductivity (ionic strength/activity effects), chlorides (tracer/migration
potential), sulfates and sulfides (oxidation condition/precipitation
potential), and coliforms and viruses (potential health implications).
Ranges in intensity and concentration of these indicator parameters
will vary throughout each phase of stabilization, again dependent on the
principal function of the phase as defined, the physical influence of
dilution or washout, and the continuing flux of moisture. Relative moisture
availability during leaching will tend to affect concentrations, and will
influence the total mass potentially leached. It will also influence
reaction opportunity and intensity and thereby lead to either accelerated or
975
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diminished microbially-mediated transformations. Unfortunately, dilution
effects are often poorly measured or recorded, leading to variances in
interpretation when analyses are based upon concentration alone.
Nevertheless, it is possible to provide general ranges of intensity and
concentration of the various indicator parameters throughout the landfill
phases when leachate (and gas) is available for analysis. Although reported
in more detail elsewhere (Pohland and Harper, 1985), the general pattern is
presented in Figure 1 which serves to demonstrate the linkage between a few
important indicator parameters and the phases of landfill stabilization.
As illustrated in Figure 1, the initial lag or adjustment phase (Phase
I) is eventually followed by: a transition from aerobic to anoxic or
anaerobic conditions with increasing production of leachate (Phase II) ,
active acid (TVA) formation with high leachate strength (COD), low pH, and
mobilization of ionic species (Phase III); methane fermentation with high gas
production and quality, reduced leachate strength (COD and TVA), increased
pH, low ORP and enhanced complexation and reduction of ionic species (Phase
IV); and, final maturation (Phase V) when nutrients may become limiting, more
difficult to degrade substrates are utilized, gas production decreases
dramatically, and poststabilization conditions are established. .
Accelerated Landfill Stabilization
The progress of landfill stabilization and concomitant attenuation and
assimilation of waste constituents can be accelerated by the elimination of
the constraints indicated previously and by optimizing operational features.
One technique to accomplish this goal is to nurture the microbially-mediated
conversion process by leachate containment, collections and recycle as
originally conceived and demonstrated by Pohland (1975, 1980), and
subsequently extended to include codisposal with both inorganic and organic
priority pollutants (Pohland et al.. 1985; Pohland and Gould, 1986; Graven
and Pohland, 1987). Indeed, recent surveys (Pohland and Harper, 1985; EPA,
1988) have indicated rather widespread application of the technique, with
over 200 landfills sites in the Unites States now practicing some form of
976
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leachate recirculation.
The inherent advantages of accelerated landfill stabilization by
leachate and gas management over conventional landfill practice can be
demonstrated by selected results of laboratory simulations. Accordingly,
laboratory-scale landfill cells, consisting of identical 208-L containers
were filled with shredded (10-15 cm) municipal solid waste (MSW). The cells
were operated with and without leachate recycle as indicated schematically in
Figure 2. After loading each cell with a total of 54.6 kg (dry) shredded
MSW with an indicated density of 482 kg/m3, distilled and deionized water was
added to attain indicated field capacity, and measurements on resultant
leachate and gas production were commenced.
In terms of mass concentrations of leachate COD and TVA accumulated or
released (Figure 3) and associated gas production and quality (Figures 4 and
5), it is apparent that accelerated stabilization and conversion of readily
available substrates to intermediate volatile acids and gas occurred rapidly
in the recycle cell, but slowly and only to a limited extent in the single
pass cell. In fact, considerably more of the available substrate measured by
leachate COD and TVA was converted to gas by in situ processes in the recycle
cell (Figure 5), whereas the major portion of these leachate constituents
were routinely discharged as washout from the single pass cell without
equivalent gas production. Such a release of high-strength leachate without
further treatment would be unacceptable in practice, thereby incurring the
additional costs and operational uncertainties of separate treatment.
Moreover, the opportunities for potential gas recovery as an energy source
without separate treatment are lost.
In addition to a lack of conversion of the organic constituents in the
leachate from the single pass cell, greater amounts of inorganic species were
released routinely with time. This is demonstrated by the data in Table 2
where the low pH condition, consequenced by the abundance of organic acids
and lower buffer capacity (alkalinity) of the single pass leachate, confirmed
the progressive washout of constituents and the absence of viable methane
977
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fermentation (Phase IV). The time for stabilization was thereby prolonged
beyond that required with leachate recycle, and is analogous to circumstances
at conventional landfills where extended periods of time (decades) are
required for such stabilization to be completed. Moreover, with leachate
recycle, many of the heavy metals were removed in situ, leached constituents
were contained within the system (unless converted to gas), and the quantity
of leachate accumulated and managed was reduced to that required for recycle
and to accommodate associated mass loading considerations. Accordingly,
leachate recycle should be operationally discontinued and the leachate pool
removed for ultimate disposal at controlled landfills when accelerated
stabilization of the readily available organic substrates has been completed
at the end of Phase IV. Such physical removal of the leachate also deprives
the landfill of the principal transport medium as well as the moisture and
nutrients necessary for continued conversion of more resistant waste
substrates. As a consequence, active biological activity dramatically
declines, and the landfill becomes essentially dormant.
The data in Table 2 also may be used to reflect the relative
acceptability of the respective leachates for ultimate discharge either to an
existing sewerage/waste treatment or land disposal system. It is apparent
that the single pass leachate would require additional organic removal by
pretreatment before ultimate discharge, whereas the recycled leachate could
be discharged without such pretreatment other than by dilution or possible
ammonia removal. In this latter case, physical removal of the residual
leachate from the landfill and discharge either to a publicly owned treatment
works (POTW) or management by land spreading (irrigation) would be
appropriate technology after Phase IV of in situ stabilization had been
completed. As indicated in Table 3, similar leachate management practices
already are being applied at full-scale landfill sites.
When compared to conventional landfill practices, a number of options
are available for leachate and gas management either as produced at the
landfill during operations and maintenance or prior to ultimate disposal.
978
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Before final discharge onto land or into a POTW, landfill leachate may
require polishing by biological and/or physical-chemical methods after either
on-site or in situ treatment. It is also widely recognized that the quantity
and quality of landfill gas essentially determines when it may be captured
and treated for possible beneficial use. The more leachate treatment
accomplished within the landfill before final discharge, the less polishing
treatment required. Moreover, if such in situ treatment is accelerated
through leachate recycle, the opportunities for energy recovery from the
associated gas production are greatly enhanced, whether the gas is used
directly or pretreated to pipe line quality.
Future Prospects and Conclusions
Leachate recirculation is being more routinely considered as a landfill
management option, and its advantages in terms of comparative costs and
enhanced predictability will likely promote more frequent implementation in
future. The arguments against such implementation are largely due to a lack
of understanding of the technology required for successful application, and
of the environmental setting within which the method is applicable. In
locations where the infiltration of moisture and leachate production are
inevitable, leachate collection and controlled recycle becomes particularly
attractive. As more operating data and experience becomes available, these
issues will be clearer and better resolved, and controlled stabilization with
leachate management will also be more readily accepted as a technically and
environmentally sound solid waste management option. Therefore, development
of future controlled stabilization landfills will more effectively harness
the potent in situ attenuating and assimilating capacities of landfills and
will link these directly to energy recovery. Elements of design, operation
and maintenance necessary to accommodate such controlled stabilization will
include:
979
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o engineered containment with fabricated liner, cover, and
confining barrier systems (natural or synthetic or both) to
facilitate leachate and gas management;
o appurtenances for leachate and gas collection, management and
ultimate disposition, including drains, filters,
collection/distribution systems, wells, vents, pumps and energy
recovery systems; and,
o integrated solid waste disposal and operating schedules to
permit sequential cell construction and operation, controlled
segregation, leachate and gas management, closure, and final use
implementation.
In the final analysis, such an integrated approach to control and regulation
of landfill stabilization will not only provide greater assurances against
adverse environmental impacts, but will enhance opportunities for resource
recovery and allay public concerns about landfills and their essential role
in municipal solid waste management.
REFERENCES
POHLAND, F.G. (1975) "Accelerated Solid Waste Stabilization and Leachate
Treatment by Leachate Recycle Through Sanitary Landfills". Progress in Water
Technology, Vol. 7, 3/4, pp. 753-765.
POHLAND, F.G. (1980) "Leachate Recycle as Landfill Management Option".
Journal Environmental Engineering Division, ASCE, Vol. 106, EEC, pp. 1057-
1069.
POHLAND, F.G. (1988) "Accelerated Anaerobic Conversion of Solid Waste in
Controlled Landfills". Proceedings IAWPRC Asian Workshop on Anaerobic
Treatment, pp. (16) 1-10.
980
-------
POHLAND, F.G. and HARPER, S.R. (1985) "Critical Review and Summary of
Leachate and Gas Production from Landfills". PB. 86-240 181/AS, NILS,
Springfield, VA 22161, 182 pp.
U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA). (1988) "Report to Congress Solid
Waste Disposal in the United States", Vol. II, EPA/530-SW-88-011B, Chapter 4.
981
-------
TABLE 1. Landfill Leachate and Gas Indicator Parameters
Parameter Identity
Utility
Physical
pH*
ORP*
Conductivity
Temperature*
Chemical
COD*, TOC
TKN*. NH3-N*. P04-P*
TVA*. SCVS, N03-N
TS*. Chloride*
Total Alkalinity*
Alkali/Alkaline Earth Metals*
Heavy Metals*
Gas (02, CH4, C02, H2, N2)*
Biological
BOD5*
Total/Fecal Coliforms
Fecal Streptococci
Viruses
Pure/Enrichment Cultures
acid-base indicator
oxidation-reduction indicator
ionic strength/activity indicator
reaction indicator
biodegradability indicators
nutrient indicators
stabilization phase indicators
dilution/environmental tracer
buffer capacity indicator
toxicity/environmental fate indicators
toxicity/stabilization phase indicators
stabilization phase indicators
biodegradability indicator
potential health hazard indicator
potential health hazard indicator
potential health hazard indicator
stabilization phase indicator
*Parameters frequently used for evaluation.
982
-------
Table 2. Comparative Characteristics of Leachates from the Single Pass and
Recycle Cells after Completion of Accelerated Stabilization
Parameter
Single Pass Cell
Recycle Cell
Chemical Oxygen Demand (COD) , mg/L
Total Volatile Acid (TVA) ,
mg/L as CHjCOOH
PH
ORP, mV Ec
Total Alkalinity, mg/L as CaC03
Conductivity, (imhos
Cadmium, mg/L
Calcium, mg/L
Chromium , mg/L
Copper , mg/L
Iron, mg/L
Lead , mg/L
Magne s ium , mg/L
Manganese , mg/L
Nickel, mg/L
Potassium, mg/L
Sodium , mg/L
Zinc , mg/L
o- Phosphate, mg/L P
Ammonia, mg/L N
Sulf ide , mg/L
6222
4670
5.3
-198
1829
1475
0.05
13
0.1
0.1
298
0.3
5.9
4.0
0.04
1.6
5.6
0.3
0.1
1-6
0.06
2006
133
7.1
-232
3222
4084
0.05
316
0.1
0.1
1.2
0.3
25.2
0.1
'0.1
266
913
1.8
0.1
105
0.3
Table 3. Landfill Leachate Management Practices and Operating Status in the United
States
Number of Landfills
Leachate Management Practice
Closed
Active
Relative
Planned Costs
Recirculate by Spraying
Recirculate by Injection
Recirculate by Other Means
Land Spreading
Truck to POTW
Discharge to Sewer to POTW
Other or Unknown Off -Site Treatment
On- Site Biological Treatment
On- Site Chemical/Physical Treatment
40
10
11
15
48
53
5
41
34
158
36
34
84
76
118
21
102
61
185
16
22
60
245
135
23
108
60
L
L
L
L/M
M/H
M
-
H
H
Source of Landfill Data: EPA, 1988 (Some facilities use more than one practice.)
Relative Costs: L (Low), M (Moderate), H (High); includes capital and operating/
maintenance costs.
983
-------
PHASE IV
METHANE FERMENTATION
Figure 1. Changes in Selected Indicator Parameters during
the Phases of Landfill Stabilization
984
-------
IMI
IJ)
Jtfif
III TtUfCIUTUtC
Itl US eOLLCCniM MMCT
IS) LtVtLIH* MTTLt
141 US RCLCUC «H.Vt
Itl wan MOTION POUT
(•I Lt«M»TC OMIN PIPC/
UUPLIM POUT '
IT I LticMATc ncscnvoiK
COUALI2ATION 0A9 UNC
(II US COU.CCTIOH UN(
isi UACMATC Ktxmmim
(KM LCMHITf KCCTCLC PUMP
mi V«/O»P HcuimiH* pmw
lid LfMMATC MCTCLC LIMC
TO us tuicn
Figure 2. Operational Features and Configuration of
Simulated Landfill Cells
985
-------
5000
COO. SINGLE
PRSS CELL
TVH. SINGLE
PflSS CELL
TVR.
COD. RECYCLE
CELL
RECYCLE
CELL
0 50 100 150 200 250 300 350 400 450
TIME, DRYS
Figure 3. Mass Accumulations and Releases of Leachate COD
and TVA during Single Pass and Recycle Operations
SINGLE PRSS
CELL
240 260 280 300 320 340 360 380 400 420 440
TIME. DF1YS
Figure A. Comparative Accumulated Gas Production during
Single Pass and Recycle Operations
986
-------
0
RECYCLE
CELL
SINGLE PRSS
CELL
240 260 280 300 320 340 360 380 400 420 44Q
TIME. UflYS
240 260 230 300 320 340 360 380 400 420 440
TIME. DflYS
Figure 5. Changes in Gas Production and Quality during
Single Pass and Recycle Operations
987
-------
DESIGN AND CONSTRUCTION
OF
SOLID WASTE CONTAINMENT SYSTEMS
by
Steven D. Menoff, P.E.
Vice President: - Engineering
Chambers Development Company, Inc.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
989
-------
INTRODUCTION
The past decade has witnessed an ever increasing emphasis on
the implementation of technical advances in the design and
construction of solid waste disposal facilities. Driven both by
public outcry and regulatory requirements, this direction has
been to minimize the potential environmental impacts of disposal
sites by enhancing the integrity of their containment systems.
Concurrently, the reduction in available landfill airspace and
the difficulty in siting and permitting new disposal facilities
has significantly increased the value of existing and permitted
airspace as an asset. These two trends have caused landfill
designers and developers to reassess existing technology and
evaluate new materials and design methodologies in an effort to
improve the performance of these facilities while maximizing
their disposal capacity.
Traditionally, natural or processed soils have been the
materials used to construct landfill liner, cover and leachate
collection systems. However, increasingly stringent regulatory
standards for both barrier and drainage layer performance have
led the solid waste industry to utilize synthetic products in
coordination with, or in place of, natural materials. If
properly designed and installed, synthetics can improve both
containment and drainage, resulting in a more environmentally
sound facility. Increases in available airspace, without
sacrificing facility performance, can be realized when synthetics
are substituted for all or a portion of relatively thicker layers
of natural materials. Consistency of material and relative ease
of installation are additional factors that have made synthetic
components a staple of current landfill design.
This paper reviews the regulatory history and assesses
current practice in the utilization of natural and synthetic
materials for the design and construction of containment systems
for solid waste disposal.
REGUIATORY BACKGROUND
Containment technology and design methodology for solid
waste disposal facilities over the past five years has followed
in the wake of Resource Conservation and Recovery Act (RCRA)
requirements for hazardous waste disposal facilities. Under
Subtitle C of RCRA, the United States Environmental Protection
Agency (USEPA) promulgated initial regulations on 19 May 1980
that established criteria for disposal facility liner and
leachate collection systems. RCRA was reauthorized and amended
on 8 November 1984 by the Hazardous and Solid Waste Amendments
Act (HSWA), which implemented even more stringent technical
990
-------
standards, the most significant of which was the requirement for
all hazardous waste facilities to have double liner systems.
In order to implement the facility standards mandated by
RCRA and define performance standards, USEPA has employed a
sequence of Minimum Technology Guidance (MTG) documents. The
initial MTG document, issued in July 1982, required a single
synthetic liner and "strongly recommended" a composite
synthetic-clay liner. As a result of the HSWA requirement for
double liner systems, USEPA issued an MTG document on 19 December
1984 specifying a synthetic primary liner and a composite
synthetic-soil or soil secondary liner and introducing the
requirement for a formal construction quality assurance plan for
each disposal unit. The 1984 MTG was updated with 24 May 1985
and April 1987 documents. This guidance, the most current,
increased the minimum permeability requirement of the primary
leachate collection system from 1 x 10 cm/sec to 1 x 10 cm/sec
and extended this criteria to the secondary leachate collection
system. It also increased the soil component of the secondary
composite liner from two to three feet of 1 x 10 cm/sec clay.
The 1985 MTG document allowed for the use of composite primary
liners. In October 1985, USEPA issued the first draft of the
construction quality assurance requirements originally outlined
in the 1984 MTG document. In addition, a July 1989 technical
guidance document refined the final cover system requirements
defined in the 1982 MTG document.
While federal solid waste regulations, to be promulgated
under Subtitle D of RCRA, are still in internal USEPA review,
many states have enacted solid waste regulations as stringent or
more stringent than what is required by Subtitle C. Several
states require double synthetic liner systems and a number even
require double composite liner systems. Even in states where
regulations call for minimal design requirements, some facility
owners have implemented containment systems based on Subtitle C
MTG in order to improve the environmental integrity of their
facilities and protect themselves from long term liability.
CONTAINMENT SYSTEMS
From both a concerned public and regulatory perspective,
three issues are raised by the land disposal of solid waste.
These are the containment of the waste and the control of its
by-products, leachate and landfill gas. No single material or
layer can adequately perform these functions. It is only through
the design of a multiple component containment system that an
environmentally "secure" facility can be developed. Equal
emphasis must be placed on both cover and liner systems in order
to minimize the accumulation and accelerate the removal of
liquids in the landfill. The components of a complete
containment system are illustrated in Figure l.
991
-------
FIGURE 1
MUNICIPAL SOLID WASTE CONTAINMENT SYSTEM
• LANDFILL
GAS
EXTRACTION
WELL
LEACHATE
REMOVAL AND
TRANSPORT
SYSTEM
CO
CO
N
FINAL
COVER
SYSTEM
LEACHATE
TREATMENT
OR
PRETREATMENT
SYSTEM
MUNICIPAL
SOLID
WASTE
LANDFILL
GAS
RECOVERY
PLANT
AND/OR
FLARE
UPGRAOIF.NT
GROUNOWATER
MONITORING
WELL
LINER AND LEACHATE
COLLECTION SYSTEM
V
DOWNGRADIENT-
GROUNDWATER
MONITORING
WELL
GROUNDWATER
TABLE
-------
The technical basis for the multi-layer containment system,
in its many variations and alternative configurations, is to
minimize liquid detention time on the barrier layers by
expediting its - removal through highly transmissive drainage
layers. The relative difference in the transmissive properties
of the barrier and drainage layers is therefore a major
consideration in the design of an effective containment system.
For this reason, composite barrier layers utilizing both
synthetic and natural materials benefit from the qualities of
both - the lower permeability and low lateral flow resistance of
a synthetic supported by the self-healing and attenuative
properties of a natural soil.
Synthetic and natural materials are used in four basic
applications in the liner and cover portions of a containment
system. The two primary functions are to provide a barrier and
drainage. The two support functions are to provide interface
layers, such as filters or protective cushions, and to provide
reinforcement.
The landfill designer must consider a number of criteria in
developing the most effective containment system for a specific
facility. The appropriate regulatory requirements are clearly
the foremost consideration. However, there are others which
impact each specific design. Where airspace is at a premium,
synthetics can be utilized to design an effective containment
system while reducing the need for thicker soil layers. The
availability of natural materials is also a consideration. The
economics of containment system components as compared to
airspace may also impact the configuration for a specific
facility. For example, synthetic drainage layers such as geonets
see more frequent use as increasingly stringent transmissivity
requirements dictate the use of highly processed, potentially
difficult to obtain, and often very expensive granular soils.
Utilizing the advantages of both natural and synthetic
materials, a number of liner and cover systems can be developed
to satisfy the various regulatory requirements and environmental
concerns which need to be addressed in the design of any solid
waste disposal facility. Figure 2 illustrates some of the more
frequently seen multi-layer liner and cover systems.
DESIGN CONSIDERATIONS
As discussed above, various natural and synthetic materials
are used to perform the four functions - barrier, drainage,
interface and reinforcement - of a solid waste containment
system. The component layers are used either individually or in
993
-------
FIGURE 2
SOD. DRAINAGE LAYER
SOIL UNER (IN-STTU OR COMPACTED)
SINGLE SOIL LINER
SELECT REFUSE OR SOIL PROTECTIVE LAYER
"•"•'•"."."•"•\\\".".~.\\".\\\".\\\\^ _ ,- CEOTEXT1LE FILTER
XXXXXXXXXXXXXXXX)0( - CEONET ORA.NACE LAYER
SINGLE SOIL LINER
SOL DRAINAGE AND PROTECTIVE LAYER
CEOTEXT1LE CUSHION
CEOUEUBRANE UNER
CEOTEXTtLE CUSHION
COMPACTED SUBCRADE
SINGLE GEOMEMBRANE LINER
SOU. DRAINAGE AND/OR PROTECTIVE LAYER
_.. ..... .•.•.•.•.•.V.'.V.'.'.V/.V. ^_ CEOTDCT1LE H1.TER
XXXXXXXXXXXXXXXX>&^~GEONET
CEOMEMBRANE UNER
CEOTEXT1LE CUSHION
COMPACTED SUBGRADE
SINGLE GEOMEMBRANE LINER
994
-------
FIGURE 2
(CONTINUED)
SOIL DRAINAGE AND PROTECTIVE LAYER
CEOTEXTILE CUSHION
GEOMEMBRANE UNER
SINGLE COMPOSITE LINER
.•.•.•.V.V.V.V.V.V.V.V.V.'.V.V.V.V.V.'.V.' y SOIL DRAINAGE AND/OR PROTECTIVE LAYER
V.V.V.'.'.V.'.V.V.'.V.V.V.'.V.'.'.'.V.'.'.'.V.'. y— GEOTEXTILE FILTER
xxxxxxxxxxxxxxxx>a— GEONCT D(WNACE
^- CEOMEMBRANE UNER
SINGLE COMPOSITE LINER
SOIL DRAINAGE AND PROTECTIVE LAYER
GEOTEXTILE CUSHION
GEOMEUBRANE UNER
SOIL DRAINAGE LAYER
GEOMEMBRANE UNER
CEOTEXT1LE CUSHION
COMPACTED SUBGRADE
DOUBLE GEOMEMBRANE LINER
SOIL DRAINAGE AND PROTECTIVE LAYER
GEOTEXTILE CUSHION
GEOMEMBRANE UNER
XXXXXXXXXXXXXXXXXX -
- - . - GEOMEMBRANE UNER
~^ CEOTEXT1LE CUSHION
COMPACTED SUBGRADE
DOUBLE GEOMEMBRANE LINER
995
-------
FIGURE 2
(CONTINUED)
V.V.V.V/V.V.V.V •.•.•.•.•/.•!•'•!•'"'•'•'•'•'•'•'•'•' y - SOIL DRA1NACE AND/OR PROTECTIVE 1AYER
y.v///.v/.v.'.y.v.v.'.'.v.v.%'.v.v.'.v.v. _ ^_ GEOTEXTILE FILTER
xxxxxxxxxxxxxxxxxx —
XXXXXXXXXXXXXXXXXK - OE:ONET DRAINAGE LAYER
—: —V- CEOMEMBRANE UNER
GEOTEXT1LE CUSHION
COMPACTED SUBGRADE
DOUBLE GEOMEMBRANE LINER
SOIL DRAINAGE AND/OR PROTECTIVE LAYER
GEOTEXTILE FILTER
xxxxxxxxxxxxxxxxxx—
„ " GEOMEMBRANE UNER
Y////7/S////////////////?^ BENTONtTE MATTING
XXXXXXXXXXXXXXXXXX CEDNET DRAINAGE LAYER
~" GEOMEMBRANE UNER
GEOTEXT1LE CUSHION
COMPACTED SUBGRADE
DOUBLE GEOMEMBRANE LINER
WITH COMPOSITE PRIMARY LINER
V-V.V.V.V-V-V-VAV-" • • •••••••-•-• - • _s SOIL DRAINAGE AND/OR PROTECTIVE LAYER
v////////.y.v.v.v.V.V.'.V.v.v.v.y.y/. ^ CEOTCXTILE FILTER
xxxxxxxxxxxxxxxxxx—
y//////////
XXXXXXXXXXXXXXXXXX CEONET DRAINAGE LAYER
///////////// ^~ GEOMEMBRANE UNER
/////// ////// S01L
DOU3LE COMPOSITE UNER
SOIL DRAINAGE AND/OR PROTECTIVE LAYER
__ _ __ GEOTEXT1LE FILTER
XXXXXXXXXXXXXXXXX
SEOMEMBRANE UNER
BENTONrTE MATTING
///////////// GEOMEMBRANE UNER
////////////r—S01L
DOUBLE COMPOSITE UNER
996
-------
FIGURE 2
^CONTINUED)
SOIL COVER AND VEGETATIVE LAYER
DAILY AND INTERMEDIATE COVER
WASTE
i i i i l i i i i
SOIL FINAL COVER
SOIL COVER AND VEGETATIVE LAYER
CEOUEMBRANE CAP
.—; —— GEOTEXTILE CUSHION
DAILY AND INTERMEDIATE LAYER
WASTE
GEOMEMBRANE FINAL COVER
SOIL COVER AND VEGETATIVE LAYER
GEOTEXTILE FILTER
_
XX)0
-------
combination with each other to meet the required design criteria
and performance standards. These component layers are generally
described as follows:
Soil Barrier Layer
• Synthetic Barrier Layer
• Soil Drainage Layer
0 Synthetic Drainage Layer
Interface Layers
Synthetic Reinforcement and Stabilization Layer
A description of the general characteristics of the materials
that comprise these components and the design considerations
associated with each is presented below.
Soil Barrier Layer
Traditionally, naturally occurring or processed clay soils
have been used as liners to prevent leachate migration and as
• final cover to prevent stormwater infiltration. Both in-situ and
compacted clays have been used for liners. Typically, in-situ
and compacted clays have been used for liners. Typically,
in-situ clay liners have-been ten feet thick with coefficients of
permeability of 1 x 10 cm/sec or less. Compacted clay liners,
because of their consistency and uniformity, have usually been
thinner (three to five feet) and resulted in permeabilities an
order of magnitude less than in-situ clay. While many states
still allow the use of clay liners for municipal waste disposal,
the trend has been to utilize clay in conjunction with a
synthetic to construct a composite liner system.
In-situ clay liners require extensive geotechnical testing
programs to verify their thickness and consistency. Continuous
and discontinuous pockets of relatively high permeability granular
materials are often encountered in natural clay deposits. To
assure that these types of materials are not in contact with
leachate, the uppermost three feet of an in-situ liner should be
excavated and compacted.
Compacted clay liners should be placed and compacted at a
moisture content slightly wet of optimum. Since clay liners are
constructed in nine to twelve-inch thick lifts, the surface of
998
-------
each lift should be scarified prior to placement of the
subsequent lift in order to achieve a homogenous liner and prevent
lateral pathways for leachate migration.
Either in-situ or compacted, soil liners occupy valuable
landfill airspace. When used with a synthetic, the thickness of
clay required is substantially reduced. Eighteen inches of
compacted clay underlying a synthetic liner provides an effective
composite barrier. The surface of clay liners are only as smooth
and consistent as construction equipment can make them. As a
result, leachate can pond in localized low spots and infiltrate
into the soil liner. Used with a synthetic, the self-healing and
attenuative capacities of clay are exposed to a significantly
lower volume of leachate and can function effectively with a
thinner layer.
An innovative method of gaining the benefits of a clay liner
without sacrificing airspace has been developed over the past
five years. Bentonite matting consists of dry bentonite between
two geotextile layers. While this matting is only a quarter of
an inch in thickness, it consists of at least one pound of
bentonite per square foot and testing has demonstrated its
effectiveness in plugging a leak in an adjacent synthetic liner.
—9
The bentonite can achieve permeabilities of 1 xlO cm/sec or
less when hydrated. Reduction in sheer strength and frictional
characteristics when hydrated make the placement of bentonite
matting within a containment system a stability concern that
should be evaluated by the landfill designer. An alternative
application would be to place the bentonite matting beneath a
clay liner in lieu of a portion of the required clay liner
thickness. Stability is less of a concern in this applicaiton.
It is imperative that construction be staged so that the
bentonite matting be covered immediately by the next adjacent
layer in order to prevent it from being exposed to inclement
weather.
Vegetative soil layers in final cover systems also serve to
reduce infiltration along with low permeability barrier layers.
Soils capable of establishing strong vegetative cover increase
surface water runoff and decrease infiltration and resulting
leachate generation.
Synthetic Barrier Layer
Compatibility with waste and leachate, physical properties
and seamability are the major considerations when selecting a
geomembrane for use as a barrier layer in a liner or final cover
system. Leachate compatibility will become a secondary concern
in the design of a cover. For a liner system, however, the
999
-------
geomembrane will be exposed to leachate for many years. As a
result, it is critical that immersion testing such as the USEPA
9090 protocol be performed with the anticipated leachate as part
of the geomembrane selection process. A wide range of
geomembranes - polyvinyl chloride (PVC), chlorosulfonated
polyethylene (CSPE or "Hypalon"), high density polyethylene
(HDPE), and numerous others - have been utilized in solid waste
containment applications. At the present time, however, it is
the consensus of both the disposal industry and the regulatory
community that HDPE is the best available product for this use.
Testing has shown that HDPE has the widest range of chemical
compatibility of geomembranes on the market and that it is
virtually unaffected by municipal solid waste leachate. A
specific gravity of 0.93 or greater is generally specified for
HDPE resin to be used for geomembrane manufacture. A carbon
black content of two to three percent is required to protect HDPE
geomembrane from degradation resulting from exposure to
ultraviolet light.
Physical properties of a geomembrane may require special
consideration during design and installation. It is important
that the design engineer consider the construction and operating
conditions to which the geomembrane will be exposed. Conditions
the designer must address include anchoring, tensile stresses
developed over long slopes, dynamic loads resulting from
equipment operation, functional interface with adjacent
materials, and the effects of settlement and subsidence.
While HDPE has the best overall leachate compatibility, its
physical properties are difficult to design with and require
site-specific evaluation. It has a high coefficient of thermal
expansion which makes the placement of adjacent layers difficult
under extreme weather conditions. In the 60 mil or greater
thicknesses used in landfill applications, HDPE can be inflexible
and difficult to work with in the field. Stress cracking is also
a concern, although mainly in liquid impoundments. HDPE has a
relatively hard manufactured surface which results in low
interface friction angles. Design of HDPE must be limited to
within its ten percent elastic yield point, beyond which
permanent deformation will occur.
Soil Drainage Layer
Granular soils such as sand and gravel have been utilized
for leachate collection and detection and for surface water above
and gas diversion below the final cover barrier layer in solid
waste landfills. Because granular leachate collection layers are
at least one foot thick, they also provide protection for the
underlying barrier layer from drainage during waste placement.
100O
-------
There are a number of concerns that must be addressed when
iesigning a granular leachate collection layer. Design standards
jver the past five years have seen the permeability_requirements
for leachate collection layers increase from 1 x 10~ cm/sec to 1
zn/sec. The objective has been to allow no more than one foot of
Leachate head buildup on the liner. This criteria has virtually
eliminated sand from consideration. Even gravel and crushed
stone must be washed and free of fines in order to perform
satisfactorily. As a result, granular leachate collection zones
:an be costly in a number of ways. They consume airspace, are
aften difficult to locate, and in many instances require
expensive processing prior to use.
Another concern is compatibility with leachate. In many
areas, the available granular soils are derived from limestone.
Testing has shown that limestone-based materials react with
municipal solid waste leachate to form a precipitate which can
eventually clog the collection zone. An effective design
guideline has been to avoid materials having a calcium carbonate
content in excess of ten to fifteen percent. This limitation
also makes acceptable granular soils difficult to obtain and,
resultingly, very expensive.
The designer should evaluate the interface of granular
drainage layers with both clay and synthetic liners. With clays,
the potential for fines to migrate into the drainage zone needs
to be considered. A soil or geotextile filter layer may be
required for the containment system to function as designed.
With a geomembrane, the concern is to protect the liner from
damage during construction and operations. It is generally good
practice to use a nonwoven geotextile as a cushion above the
synthetic liner to protect it from angularities in the drainage
stone. At least eighteen inches of soil should be placed above
the geomembrane prior to operating equipment above it. While the
full eighteen inches does not need to satisfy the permeability
criteria, it is often designed to do so.
Other design issues that must be addressed are the stability
of granular soil on side slopes, clogging of the soil by
biological activity and sediment deposition and physical and
drainage interaction of the soil with the embedded pipe network.
Removing leachate • from the landfill is the first step in
maintaining an effective containment system. To achieve this,
composite collection systems consisting of granular soils,
geotextile filters and geonets may be an alternative for the
design engineer.
Synthetic Drainage Layer
Both geotextiles and geonets can be used as drainage layers
1001
-------
within containment systems. However, the much higher
transmissivities of geonets have made them the synthetic of
choice for most drainage applications. Geonets can be used in
leachate collection and detection and final cover systems in
place of, or in conjunction with, natural soil layers.
Geonets being considered for use as drainage layers should
be subjected to carefully controlled laboratory testing to
determine the material's transmissivity and its response to
overburden loading. Laboratory tests should carefully model the
anticipated field conditions and include the materials which will
be placed adjacent to the drainage layer, realistic overburden
loads, and be conducted under a range of hydraulic gradients
(usually less than 1.0). The overburden loads applied should be
increased incrementally to at least the maximum overburden load
anticipated in the field. If possible, testing should be
performed with applied overburden pressures which exceed the
maximum anticipated pressures by at least 50% to check that
significant transmissivity reduction will not take place if
overloading does occur. Transmissivity reductions may be the
result of material compression, strand rollover, or the intrusion
of adjacent materials into the drainage channels.
Variations in drainage layer transmissivity are, in part, a
function of the components of the drainage system and the
immediately adjacent materials. Typical observed variations for
drainage systems utilizing geonets are outlined in Table 1. The
transmissivity values shown are for extruded geonets
approximately 0.2 inches thick, nonwoven geotextiles and cohesive
soils.
Transmissivity tests described above are generally performed
at various load increments, with these loads being applied for a
time duration ranging typically from less than one hour up to 24
hours. Limited testing has been performed on samples subjected
to static loads with longer durations. Testing performed on
geonet samples that have been loaded for almost two years
indicates only slight transmissivty reductions after one day.
Other factors which may impact the long term performance of
the drainage layer are its creep characteristics, response to
elevated temperatures, and the potential for biological or
mechanical clogging. Laboratory studies and field monitoring to
evaluate the long-term effects of these factors have only begun
recently. A conservative design approach is recommended until
conclusive results are available.
Synthetic drainage materials exhibit preferential drainage
directions which should be taken into account during design and
construction. Geonets exhibit a wide range of directional
drainage behavior. Some geonets have transmissivity anisotropies
1002
-------
TABLE 1
GEONET DRAINAGE SYSTEM TRANSMISSIVITIES
o
o
Drainage System
Configuration
geomembrane
geonet
geomembrane
soil
geotextlle
geonet
geomembrane
soil
geotextlie
geonet
ge9text11e
soil
Typical Transmlssivity
010,000psf. 1=1.0
1 x 10~3M2/sec
5 x 10"4M2/sec
1 x 10~4M2/sec
Granular Material
Equivalency
12" 0 k=3xlO"1cm/sec
12" 0 k=1.5xlO~1cm/sec
12" @ k=3xlO"2cm/sec
-------
that are insignificant and require no special construction
considerations. Others have drainage preferences that are nearly
unidirectional and the use of such products may require
significant design consideration and careful construction control
to be effective. In general, overall transmissivity behavior can
be significantly effected by the orientation of the strands which
compose the geonet.
Compatibility with leachate is also a consideration for
synthetic drainage layers. Like geomembrane barrier layers,
geonets will be subjected to leachate contact for many years.
Therefore, geonets should undergo testing to verify compatibility
with the anticipated leachate composition. As a result, most
geonet products are manufactured from HDPE resin.
Interface Layers
In order for the materials utilized for the primary
functions - barriers and drainage - in a containment system to
perform as designed, "interface" layers are often required.
Interface functions include filtration, separation and protection
and can be performed by either natural or synthetic materials.
As is the case for barriers and drainage layers, synthetics have
the advantage of accomplishing the same function while occupying
less space than natural materials.
Filters must be provided to maintain the integrity of the
leachate collection zones. In designing either an aggregate or
geotextile filter, the criteria conforms to traditional
geotechnical engineering practice. The filter layer must provide
adequate vertical drainage (referred to as permittivity) to the
lateral flow zone; prevent piping of the overlying soils; and
provide durability against chemical and biological degradation.
While the use of non-carbonate aggregates or polyester or
polypropylene geotextiles should provide protection from leachate
attack, the effects of biological growth on filter performance is
only now being investigated by researchers. Industry experience
indicates that nonwoven geotextiles are generally superior in
performance to woven geotextiles, particularly when fine-grained
soils are being filtered.
Cushion layers are generally required to protect synthetic
liners from the relatively large granular soils required to meet
current transmissivity requirements. When synthetic liners first
came into general use, a thin layer of sand was placed both above
and below the geomembrane in order to provide protection. This
practice prevented the construction of effective composite
liners. It also hindered the rapid removal of leachate from the
top of the liner by allowing a relatively low permeability (fine
sand compared to clean gravel) zone immediately above the
geomembrane. Nonwoven geotextiles, generally at least twelve to
1004
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sixteen ounces per square yard, have proven effective in
protecting HOPE and other geomembranes. Thickness and bulk
density are the material characteristics required for an
effective cushion. A laboratory testing program incorporating
the actual containment system configuration and anticipated
overburden loads should be performed in order to evaluate a
specific design.
Synthetic Reinforcement and Stabilization Layers
Synthetic reinforcement layers, known as geogrids, can be
used to support containment systems constructed over normally
unsuitable foundation soils and existing waste materials in
"overfill" or "piggyback" landfills. The necessity for this
aplication increases along with the difficulty in siting and
permitting new disposal facilities and the resulting need to
expand or maximize the utilization of existing facilities.
Geogrids are placed during the construction of the subgrade soils
to provide tensile reinforcement to counter the effects of
anticipated deflection, subsidence and differential settlement.
Another application for geogrids in containment systems is
to stabilize the placement of protective soil cover on side
slopes. The natural characteristics of the granular materials
generally used for protective cover often limit the length of
slope which can be covered at a given time. Incorporating
geogrids in the design can allow for the placement of a greater
amount of protective cover at a given time, facilitating
construction and operations.
As with all synthetic components, geogrids must be
compatible with leachate and resist chemical attack. Most
geogrid products currently used in landfill applications are
manufactured from polyethylene resins.
Stability
During both construction and operation of a disposal
facility, the frictional characteristics of the containment
system components can be of significant importance. Stability
considerations control the integrity of below-grade and
above-grade slopes and govern the sequence of landfill
operations. Published data suggest that synthetic interfaces
have lower friction angles and are therefore more critical than
natural soil or soil/synthetic interfaces. Geonets and
geotextiles are often situated adjacent to geomembranes in a
variety of applications. Because laboratory data indicate
relatively low friction angles for these interfaces, the
stability of the entire disposal facility may be dependent on an
accurate analysis and design of these components. Conservative
1005
-------
friction angle values or site-specific test results should always
be used as a basis for design.
Leachate Compatibility
Discussions concerning compatibility with leachate are
generally directed at the geomembrane component of a liner
system. However, in order to function as designed, it is
critical that all components of the containment system be
evaluated for compatibility. All of the synthetic components can
be immersed in the anticipated leachate and tested for physical
property retention at various time intervals in a similar
protocol to USEPA 9090 for geomembranes. Both USEPA and the
American Society for Testing and Materials (ASTM) are currently
developing specific protocols for immersion testing for gepnets,
geotextiles and other synthetics. Soil barrier and drainage
layers can be evaluated by using leachate to perform permeability
and transmissivity tests, respectively. USEPA 9100 outlines the
protocol for clay liners.
CONSTRUCTION CONSIDERATIONS
The translation of an engineering design to a constructed
facility is always an area requiring careful monitoring and
observation. However, it becomes extremely critical when the
facility is a solid waste containment system the integrity of
which is paramount to protecting the environment and public
health. In order to achieve the most secure facility possible,
the development and implementation of both stringent construction
specifications and a comprehensive construction quality assurance
program become imperative.
In order to develop and implement a quality assurance
program, it is first necessary to define what is meant by the
term "quality assurance" and how it is related to the activities
encompassed by the term "quality control". These terms are often
used interchangeably, resulting in a misinterpretation and lack
of clarity in the intent of each term. Quality control can be
defined as the measures taken by a contractor to determine if the
work performed is in compliance with the project specifications
and contract requirements. Quality assurance refers to the
measures taken by the facility owner using an independent
engineer to determine if the work performed by the contractor
complies with project specifications and contract requirements.
Quality assurance, then, is the assessment of the contractor's
performance by the facility owner's third party representative.
1006
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Quality Control
Since the synthetic and natural materials to be used in the
landfill containment system have been specified by the design
engineer based on laboratory testing, it is critical that the
materials used in the construction of the landfill have identical
properties as those tested in the laboratory. Particularly for
synthetics where critical properties can vary significantly even
if manufacturing processes are varied only slightly, it is
necessary that good quality control be exercised during
manufacturing or processing. Samples should be taken on a
regular basis during manufacturing and tested to evaluate
relevant properties. The manufacturer should maintain detailed
quality control documentation and be able to provide
certification of the quality of each roll of material produced.
It is advisable to use only thoroughly tested products from
manufacturers who have a record of consistently producing a
quality product and to carefully review their quality control
procedures with them prior to running the product for a specific
site. Any supplier who hesitates to fully cooperate with all
quality control efforts or is unwilling to produce historical
quality control records should be disqualified from consideration
for the project.
For natural materials, the line between quality control and
quality assurance testing becomes more difficult to distinguish.
It is necessary to sample and test a clay liner or granular
drainage stone at its source in order to define its properties.
The soil must be in the condition in which it will be actually
utilized in construction, such as a processed clay or washed
stone. In this way, the properties determined as part of the
quality control program will be the basis of assessment for the
quality assurance program during construction.
Quality Assurance
The principal objective of a construction quality assurance
program is to minimize potential problems by achieving the best
installation possible. To reach this goal, the quality assurance
program must provide for the utilization of uniform standards and
practices; the verification of compliance with material
specifications, installation and testing procedures, and
applicable regulatory requirements; and a defined route to
obtaining as-built documentation and certification that the
project was constructed in accordance with the specifications.
An effective quality assurance plan must define how it will
achieve its stated objectives. It will need to provide an
explanation of the qualifications, roles, responsibilities,
1007
-------
authority and interaction of all parties involved. It must
identify and describe all quality assurance activities and
procedures and allow for well thought out in-field decisions by
identifying actions to be followed when a problem occurs and by
providing the basis for problem resolution. A preconstruction
meeting, involving all parties, is required at the outset of the
project to clearly outline the site-specific quality assurance
plan, construction procedures and lines of communication to be
adhered to during the course of the project. A basic outline for
a construction quality assurance plan is presented on Table 2.
In addition to the quality exercised by the manufacturer
during production, conformance testing should be performed on
samples taken from the rolls of synthetics delivered to the site.
Samples should be taken at a predetermined interval (typically,
one per 100,000 ft2) and the tests performed will depend on the
type of synthetic being used. These tests should indicate
whether or not the materials delivered to the site have the same
properties as the designer intended. Conformance testing is the
primary way in which the quality assurance program is applied to
manufacturing of the synthetics. An additional step which should
be taken either on a regular basis or for major jobs is to
perform an inspection of the manufacturing facility. At a
minimum, a plant inspection should be an integral part of the
prequalification of any manufacturer.
The handling, storage, and transportation of the synthetics
should be carefully controlled so that they are not damaged
between the manufacturing plant and their delivery to the site.
The importance of this intermediate handling should be stressed
to all parties involved. All rolls of synthetics delivered to
the site should be visually inspected for possible damage. All
damaged rolls should be rejected. Synthetics used for drainage
or filter applications, such as geonets or geotextiles, must be
kept clean and free of debris . which might impact their
performance in the containment system. These materials must be
stored in a dry, covered area prior to installation. If this is
not done, extensive cleaning may be required at a minimum and
rejection of the rolls may be necessary in the worst case.
Careful attention must be paid to installation requirements
including placement, orientation, and joining techniques. In
general, geotextiles should be sewn and geonets overlapped and
tied. Geonet ties should not contain any metal and should be of
a contrasting color to the geonet to allow for easy inspection.
Typically, geonets are overlapped a minimum of four inches and
ties spaced on the order of five feet along slopes, two feet
across slopes, and six inches in anchor trenches. It is also
important that the installation procedures (placing, cutting, and
joining) performed for each synthetic not be allow to adversely
impact the performance of adjacent synthetics.
1O08
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TABLE 2
CONSTRUCTION QUALITY ASSURANCE PROGRAM
0 OUALZFZCATIONS AND RESPONSIBILITIES OF PARTIES
t CHAIN-OF-COMMAND, MEETINGS AND REPORTING STRUCTURE
• SOIL COMPONENTS OF CONTAINMENT SYSTEM
" PRE-CONSTRUCTION TESTING OF SOIL SOURCES
" TEST FILL CONSTRUCTION AND TESTING
' CONSTRUCTION TESTING FOR MATERIAL EVALUATION
" CONSTRUCTION TESTING FOR PERFORMANCE PROPERTIES
• GEOSYNTHETIC COMPONENTS OF CONTAINMENT SYSTEM
* MANUFACTURING
* FABRICATION
• HANDLING, STORAGE AND TRANSPORTATION
* INSTALLATION
* CONSTRUCTION WITH OTHER MATERIALS
• DOCUMENTATION AND CERTIFICATION
1009
-------
All geomembrane seams must be visually observed during the
installation process. In addition, seams must be evaluated
through non-destructive and destructive testing. Extrusion seams
can be non-destructively assessed for continuity using a vacuum
box or a spark tester. Fusion and extrusion seams between the
geomembranes can be split to create a channel in the center of
the seam. In this instance, the seam can be non-destructively
evaluated for continuity with air pressure testing through the
seam channel. The parameters for non-destructive testing must be
defined in the quality assurance plan. Destructive evaluation
includes shear and peel testing for both fusion and extrusion
seams. The quality assurance plan must outline a program for
destructive testing, including the frequency of sampling, sample
size, in-field and laboratory testing, criteria for acceptance
and rejection, and corrective measures when necessary.
Quality assurance procedures should be developed to ensure
that the installation of adjacent materials does not result in
any damage to the synthetics. It is always necessary to place
soil cover prior to allowing any equipment traffic on areas
covered with synthetics. The thickness of soil cover may range
from one to three feet, depending on the type of equipment to be
used. In general, at least eighteen inches of protective soil
should be placed prior to initiating disposal activities within a
synthetically-lined landfill.
Quality assurance measures for soil liner components are
based on the need to perform tests representative of actual field
conditions while not damaging the actual compacted liner. One
approach is to do all destructive (sample removal for laboratory
testing) and in-situ (field permeability) testing on a "test
fill" constructed with the identical equipment and methods as the
actual liner. In this way, the compacted liner will only need
to be tested to verify that it is in the same condition (density,
moisture content) as the test fill to confirm its performance
properties. In-situ permeability testing on a 1 x 10 cm/sec or
less clay liner can take several months to perform. The use of a
test fill can prevent construction delays and prolonged exposure
and resulting damage to the liner. Scarification and bonding
between lifts and maintaining correct moisture are other clay
liner construction concerns to be addressed by the quality
assurance program.
As a result of having implemented a comprehensive quality
assurance plan, it will be possible for the independent engineer
to certify the installation and for the facility owner to accept
the final product. The third party engineer should prepare a
final certification report at the conclusion of the project.
This report should include, at a minimum, an outline of the
project, the quality assurance methods used, the test results,
and the as-built documentation and drawings. This report will
101O
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serve as a basis for the formal acceptance of the final product
by the facility owner and, where required, by the regulatory
agency.•
SUMMARY
The design and construction of solid waste containment
systems incorporating natural and synthetic components have been
discussed in this paper. Since the utilization of synthetics in
conjunction with or in lieu of natural soils is relatively new,
it is important that designs be* based as much as possible on
carefully modeled laboratory testing and verified by field
observation and testing. Significant design considerations
included stability and interlayer frictional characteristics,
transmissivity, filter characteristics and compatibility with
waste and leachate. However, design is only one of the issues
that must be addressed when dealing with synthetics. By far the
most important part of a successful installation is the
implementation of a comprehensive quality control and quality
assurance program during manufacturing and construction. The
importance of this aspect for a solid waste disposal facility
cannot be overstated.
It is anticipated that in the future synthetics will find
increased use in a variety of functions at solid waste landfills.
This increased use will be driven by technical criteria directed
at designing and constructing more secure containment facilities
and minimizing environmental impacts as well as by economic and
site life considerations. In some cases, synthetic materials can
offer significant advantages over the use of natural materials.
The proven performance and widespread acceptance of these
products dictate that they be routinely considered in conjunction
with natural components during the conceptual design phase of
solid waste containment systems for all new disposal facilities.
1011
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REFERENCES
1. Bell, J.R., "Design and Construction Using Geosynthetics,"
ASCE Continuing Education, 1989.
2. Giroud, J.P., Geotextile and Geomembrane Definitions.
Properties and Design. IFAI, St. Paul, Minnesota, 1984.
3. Koerner, R.M., Designing with Geosynthetics. 2nd Edition,
Prentice-Hall, Englewood Cliffs, New Jersey, 1990.
4. Koerner, R.M., "Solid Waste Containment Systems Using
Geosynthetics," Chicago Geotechnical Lecture Series, 1990.
5. Koerner, R.M. and Bove, J.A., "Lateral Drainage Designs
Using Geotextiles and Geocomposites," Geotextile Testing and
the Design Engineer, ASTM STP 952, 1987.
6. Lundell, C.M. and Menoff, S.D., "The Use of Geosynthetics as
Drainage Media at Solid Waste Landfills," NSWMA Waste Tech
Proceedings. Boston, Massachusetts, 1988.
7. Lundell, C.M. and Menoff, S.D., "The Design and Construction
of Landfill Containment Systems with Geosynthetic
Components," Geosynthetics '89 Proceedings. San Diego,
California, 1989.
8. Menoff, S.D., Stenborg, J.W. and Rodgers, M.J., "The Use of
Geotextiles in Waste Containment Facilities," ACS Hi-Tech
Textiles Symposium. Miami, Florida, 1989.
9. Richardson, G.N. and Koerner, R.M., Geosynthetic Design
Guidance for Hazardous Waste Cells and Surface Impoundments.
USEPA-GRI Publication, Philadelphia, Pennsylvania, 1987.
10. Richardson, G.N., and Koerner, R.M., "Design of Geosynthetic
Systems for Waste Disposal," ASCE Conference on Geotechnical
Practice for Waste Disposal. Ann Arbor, Michigan, 1987.
11. Schubert, W.R., "Bentonite Matting in Composite Lining
Systems," ASCE Conference on Geotechnical Practice for Waste
Disposal. Ann 'Arbor, Michigan, 1987.
12. Slocumb, R.C., Demeny, D.D. and Christopher, B. R., "Creep
Characteristics of Drainage Nets," Proceedings of the Ninth
Annual Madison Waste Conference. Madison, Wisconsin, 1986.
13. USEPA, Reguirements for Hazardous Waste Landfill Design.
Construction and Closure. Cincinnati, Ohio, 1989.
14. Vardy, P., "Impact of Current Regulations on Geotechnical
Practice," ASCE Conference on Geotechnical Practice for
Waste Disposal. Ann Arbor, Michigan, 1987.
1O12
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AN ENVIRONMENTAL ASSESSMENT OF RECOVERING
METHANE FROM MUNICIPAL SOLID WASTE BY
REFCOM ANAEROBIC DIGESTION PROCESS
Philip R. O'Leary, Ph.D.
Department of Engineering Professional Development
College of Engineering
and
James C. Converse, Ph.D.
Department of Agricultural Engineering
College of Agricultural and Life Sciences
University of Wisconsin-Madison
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
1013
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AN ENVIRONMENTAL ASSESSMENT OF RECOVERING
METHANE FROM MUNICIPAL SOLID WASTE BY
ANAEROBIC DIGESTION
Abstract
The full scale development of the RefCoM process which
produces biogas or synthetic natural gas (SNG) by anaerobic
digestion of municipal solid waste (MSW) is evaluated. This
technology would be utilized in lieu of incineration or directly
landfilling waste. An environmental assessment describing the
principal impacts associated with operating the MSW anaerobic
digestion process is presented. Variations in process
configurations provide for SNG or electricity production and
digester residue incineration, composting, or landfilling. Four
RefCoM process configurations are compared to the conventional
solid waste disposal alternatives of mass burn incineration and
landfilling. Value analysis techniques indicate that the RefCoM
process was preferred to mass burn incineration or direct
landfilling of MSW.
1014
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I. Introduction
New methods and processes are being sought to cope with the
ever increasing quantities of municipal solid waste (MSW).
Approaches include source reduction, recycling, waste processing
and separation, energy recovery, and better sanitary landfilling
methods. One such approach, the RefCoM process, produces
biogas by anaerobic digestion of municipal solid waste. This
technology would be utilized in lieu of incineration or directly
landfilling a portion of the waste.
II. The Anaerobic Digestion Process
A group of obligately anaerobic bacteria will, in the
absence of O2, consume various types of organic wastes producing
methane, a major component of natural gas, carbon dioxide, and
water (Stanier, et al., 1965). The speed, and degree to which
the digestion process is completed will depend on the bacterial
community, nutrient balance, temperature, and the specific
nature of the waste material. This process occurs naturally in
many places and, in addition, has been extensively used to break
down organic wastes in the sewage treatment process.
1015
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Laboratory scale experiments to anaerobically process
municipal solid waste and sewage sludge were described by
Pfeffer (Pfeffer, 1974; Pfeffer and Khalique, 1976; Pfeffer and
Liebman, 1976). A single stage anaerobic digestion unit was
tested. The experimental unit was operated over a temperature
range of 35 to 60 degrees C and 4 to 30 days detention time.
Volatile solids destruction ranged from 16 to 52 percent. Based
on Pfeffer's work, operation of a 100 ton per day pilot plant
located in Pompano Beach, Florida, began in 1978 (Mooij and
Pfeffer, 1986) . Based on the results of the pilot plant test,
Isaacson, et al., (1987) estimated the necessary waste
processing fee for various combinations of natural gas,
electricity prices and concluded that the RefCoM process has
"significant commercial potential."
III. RefCoM Configurations Evaluated
Alternative RefCoM process configurations were compared to the
conventional solid waste disposal technologies of mass burn"
incineration and landfilling. The four alternative processes
were:
1. RefCoM synthetic natural gas production with residue
incineration (REFCOM SNG/INC), see Figures 1-3;
2. RefCoM biogas and electric production with residue
incineration (REFCOM ELEC/INC), see Figures 4 and 5;
1016
-------
Figure 1. RefCoM SNG / Incineration Process Diagram
atmosphere
solid
waste
synthetic natural gas
production module
(see Figure 3)
incinerator
feed
solid waste
incinerator
I landfill gas
j electric
generator
digestion
process
nutrients
ncnerator
, by-pass
WWTP
chemicals
wet trommel water
mix tank water
boiler makeup water
cooling tower makeup water
Waste Water Treatment Plant i
-------
Figure 2. RefCoM Waste Preparation Module Process Flow Diagram
solid
waste
5
waste
storage
wai
prepar
mod
by-p
te
ation
ule
ass
\
*. shredder to magnetic disc
^ anrtHUCr ^ separator ^ ^'W>
i '
disc screen \-
, , T
•^ ' 1 air stoncr p^l 1 disc screen
t
air
1 classifier
?
i
?
*~ wet
trommel
i '
ferrous
H magnetic
separator
f
1
P— ' — -•-
gas production waste preparation module underflow
module by-pass
i
i
water
te. aluminum ^ f •
^ "'""" — m*- alumini
separator
Hfa
JJ O ^ i™,ir.n
gas production
module feed
-------
Figure 3. RefCoM Synthetic Natural Gas Production Module Process Diagram
digestion process
nutrients
I
waste
preparation
module
mix lank
feed
synthetic
natural
gas
digester
flaring
kdigester
\ gas
leaks
gas
seperator
condensate
digester
underground
leaks
gas separator
permeate
boiler
residue
incinerator
water
steam turbine
condensate
-------
Figure 4. RefCoM Electric / Incineration Process Diagram
atmosphere
solid
waste
storage
by-
pass
mix
tank
feed
O
CO
O
waste preparation module
(sec Figure 2)
J_
JJ
gas production waste preparation
module by-pass module underflow
M
biogas gas turbine
electric generator
APCchemicals M APT!
biogas production
module
(see Figure 2)
digestion
process
nutrients
landfill gas I
electric I
generator
*- wet trummel water
»- mix tank water
*• boiler makeup water
*• cooling tower makeup water ,
6 r Waste Water Treatment Plant i ! i
-------
Figure 5. RefCoM Biogas Module Process Diagram
waste
preparation
module
digestion process
nutrients ... , mix tank
feed
=• ? digester
1 8°^
I leaks
digester Ut ^»— i -x^
i — % ' ' ' ' flaring \ ^_
| | L \ digester
mix 1
biogas gas
turbine
..... ^^ !-_!!--
dcwarererf
residue ._,
i
tank i 1 ¥
t ^ /
p\ yv I— ' '
i,,.ni r W 1^
w
/// -
' exchanger ' • rcsidue
0 press
t/igester
underground
leaks
incinerator
waste water
-------
3. RefCoM SNG production with residue composting
(REFCOM SNG/COM), see Figure 6;
4. RefCoM SNG production with residue landfilling
(REFCOM SNG/LF), see Figure 7.
The conventional mass burn incineration system and the sanitary
landfill are depicted in Figures 8 and 9.
Each configuration has the same waste preparation module
which shreds and separates waste into degradable and non-
degradable fractions plus aluminum and ferrous metals. The
degradable fraction is directed to the gas production module
while the non-degradable portion is landfilled.
The gas production module has a mixing tank where water and
possibly nutrients are added. The slurry is then pumped into an
air tight tank where the material is continuously stirred,
maintained at a constant temperature, and allowed to decompose
anaerobically. The product gas, a 55-45 percent mixture of
methane and carbon dioxide, is collected from the digester. In
the SNG configuration the CO2 is removed and the resulting
methane rich gas is pumped into a natural gas pipeline. With
the REFCOM ELEC/INC configuration, the gas is not purified and
instead powers a turbine/electric generator unit.
1022
-------
Figure 6. RefCoM SNG / Composting Process Diagram
atmosphere
O
N
CO
solid
waste
[storage
by-
pass
mix
tank
feed
J.
waste preparation module
(See Figure 2)
jL_L
gas production
module by-pass
waste preparation
module underflow
APC chemicals
synthetic natural gas
production module
(See Figure 3)
digestion
process
nutrients
lAPCl I CJoi
4 " *
I synthetic natural gas (SNG)
boilerl
incinerator
feed
waste
gas incinerator
digester residue
waste water
*- wet trommel water
*• mix tank water
*• boiler makeup water
•> cooling tower makeup wafer
WWTP
chemicals
ferrous \
aluminum
landfill gas
electric
generator
compost land
spreading
Waste Water Treatment Plant i
run-
off
-------
Figure 7. RefCoM SNG / Landfilling Process Diagram
atmosphere
solid
waste
r
-*~{sjorage (-»•
mj
tai
stion
ess
ients
aaxx wa
jt
i*
•d
•• .
ste prcparali<
(See Figu
j
^
re 2) j
| | , ^hl
gas production waste preparation \
module by-pass module underflow j synthetic natural gas (SNG)
synthetic natura
production mo
(See Figure 2
i
i
APC chemicals y •
lAPCl 1 Ch^
Igas
dule
0
1 *i
• i
gas
*• incinerator
incinerator
i digester residde
i ,
v*5*C nFQtCf | ^
*~ wet trummel water "."T ,
cwffucaw
+* mix tank water fiilr"
»• Ao/ter makeup water \^~J~
I,
leachate
1
ferrous
aluminum
landfill gas
electric
generator
^ i
' III 1 " UU^i
^1 > I x>^
sanitary ] •
landfill J
f
>o-
•u
electricity
r
electric
service
-
». cooling tower makeup water
Waste Water Treatment Plant
-------
Figure 8. Mass Burn Incineration System Process Diagram
atmosphere
O
to
01
air pollution
control chemicals
electricity \
electric
generator j
I solid waste
' incinerator
incinerator
feed
incinerator
by-pass
landfill gas
1 electric
sanitary
landfill
WWTP
chemicals
boiler makeup water
cooling tower makeup water
Waste Water Treatment Plant
-------
Figure 9. Landfill Process Diagram
o
to
0)
atmosphere
landfill gas
electric
generator
Waste Water Treatment Plant
-------
IV. Comparison Procedure
A mass flow model estimated the quantity of gases and
liquid wastes which will be released to the environment by each
configuration and alternative waste disposal system under
consideration. In addition, the amount of land permanently
occupied by the landfill alternative and the landfills
associated with the RefCoM process and the mass burn incinerator
was projected.
The comparison used a systems approach where each RefCoM
configuration and alternative disposal method has the same
function. Within the system boundaries, landfills received
RefCoM and incineration residues, and a waste water treatment
plant received landfill leachates. Emissions and effluents from
the original production and manufacturing of natural gas,
electricity, aluminum and iron were estimated to account for the
environmental discharges avoided when the RefCoM process has
SNG, electric energy, and recovered metals as products.
Each RefCoM process configuration and the alternative mass
burn and landfill systems were assumed to be designed to
comparable technical and regulatory standards. The standard
selected represents United States Environmental Protection
Agency "new source performance" and, if not defined, "best
implemented control technology."
1027
-------
Air emissions from the RefCoM process residue incinerator
and mass burn incinerator were characterized from stack test
data at three new incinerators which have advanced air pollution
control technology. Landfill gas emissions which are
characterized by California and Wisconsin stack tests. Liquid
discharges from the landfills were predicted with the U.S. EPA
HELP Model. Air and water emissions from natural gas, electric,
aluminum and iron production were estimated from U.S. EPA new
source standards and emission factors studies.
The purpose for predicting the emission, effluent, and land
use quantities for the RefCoM process and mass burn and
landfilling alternatives was to make comparisons and draw
conclusions regarding the best system, environmentally. A more
stringent test was provided by comparing the RefCoM process to
mass burn incineration and landfills which are designed to the
latest standards. Undoubtedly, the RefCoM process will reduce
reliance on landfills, many of which comply with only minimal
standards. Assuming stringent environmental standards for
natural gas, electric, aluminum and iron production further
strengthened the test.
Residue from the anaerobic digester is dewatered and two
configurations, REFCOM SNG/INC and REFCOM ELEC/INC, incinerate
this residue. The REFCOM SNG/COM configuration assumes the
residue is composted and spread on land. The residue is
landfilled with the REFCOM SNG/LF configuration.
1O28
-------
V. . Predicted Results
The results of this predictive and characterization work
are summarized in Table 1. Emissions, effluents,and land use
from the systems are separated into three locational categories:
1. On-site: occurring at the RefCoM process
facility or mass burn incinerator;
2. Off-site: associated with the ash and sanitary
landfills, waste water treatment plant and the
vehicles hauling solid waste, ash and sludge;
3. Remote: resulting from electric power generation
and natural gas, aluminum, and iron production.
From Table 1, it is not possible to deem one system
inherently better than the rest. To make this judgement, a
value analysis was conducted. Four people with broad
environmental backgrounds provided their subjective assessment
of the relative importance of the emissions, effluents, and land
use along with locational judgements. The four people were:
1. -a former local government official
2. an environmental attorney/educator
3. an energy management engineer
4. a state official
These subjective importance weighting factors, when applied to
the estimates in Table 1, give the results in Table 2. The
1029
-------
S
Table 1. Predicted Performance of Four MSW Anaerobic Digestion Process
Configurations/ Mass Burn Incinerator, and Sanitary Landfill.
SOLID WASTE RECEIVED (tons/yr)
RECOVERED RESOURCES
Ferrous (tons/yr)
Aluminum (tons/yr)
SNG Production Rate (SCF/yr)
Total Electric Generation (MWH/yr)
ON-SITE AIR EMISSIONS
particulate (tons/yr)
S02 (tons/yr)
NOx (tons/yr)
PCCD (tons/yr)
C02 (tons/yr)
OFF-SITE AIR EMISSIONS
particulate (tons/yr)
S02 (tons/yr)
NOx (tons/yr)
vinyl chloride (tons/yr)
C02 (tons/yr)
OFF-SITE DISCHARGE TO GROUNDWATER
leachate leakage (tons/yr)
OFF-SITE SURFACE WATER EFFLUENTS
WWTP effluent (tons/yr)
OFF-SITE PERMANENT LAND USE
landfill area (acres/yr)
REMOTE AIR EMISSIONS
particulate (tons/yr)
S02 (tons/yr)
NOx (tons/yr)
C02 (tons/yr)
REFCOM
SNG/INC
104000
5860
311.2
3.6E+08
5552
1.956
21
103
2.1E-07
53270
1.24
10.4
2.68
0.0369
31432
5044
25684
0.902
5.9469
240.4
120.33
44126
REFCOM
ELEC/INC
104000
58.60
311.2
0
50579
2.681
36.28
178
3.6E-07
72883
1.245
10.5
2.7
0.0369
31473
5051
26514
0.922
0.0389
117 .8
1.14
1150
REFCOM
SNG /COM
104000
5860
311.2
3.4E+08
-7411
0.298
4.03
19.7
4.0E-08
8455
1.293
13.6
3.14
0.0369
66585
5004
20513
0.776
8.8094
314.1
155.01
56875
REFCOM
SNG/LF
104000
5860
311.2
3.4E+08
-5714
0.298
4.03
19.7
4.0E-08
8455
2.433
16.5
4.81
0.0686
66406
8435
34499
1.306
8.5516
305
150.48
55211
MASS
BURN
104000
0
0
0
36791
3.477
48.43
237.5
4.8E-07
93978
0.94
11.4
2.45
0.027
21467
2704
37954
1.062
21.5398
262.6
79.49
30087
LANDFILL
104000
0
0
0
6032.284
0
0
0
O.OE+00
0
4.555
24.7
8.25
0.1231
125840
16593
67636
2.564
27.1278
458.9
177.81
66142
-------
Table 2. Value Analysis Ranking of Four MSW Anaerobic Digestion Process
Configurations, Mass Burn Incinerator and Sanitary Landfill
FORMER LOCAL OFFICIAL
VALUE
RANK
ENVIRONMENTAL ATTORNEY/EDUCATOR
VALUE
RANK
ENERGY MANAGEMENT ENGINEER
VALUE
RANK
STATE OFFICIAL
VALUE
RANK
MEAN VALUE
RANK
REFCOM
5NG/INC
0.8555
2
0.7431
2
0.7656
3
0.5894
3
0.7384
2
REFCOM
E LEG/ INC
0,7615
4
0,7027
4
0.7837
1
0.6169
2
0.7162
3
REFCOM
SNG/COM
0.9176
1
0.8195
1
0.7698
2
0.6191
1
0.7815
1
REFCOM
SNG/LF
0.8391
3
0.7095
3
0.6581
4
0.5329
4
0.6849
4
.MASS
BURN
0.5694
5
0.5913
5
0.5981
5
0.5190
5
0.5695
5
LANDFILL
0.4555
6
0.2805
6
0.1808
6
0.2952
6
0.3030
6
NOTE: Possible value ranges are from 0-1 with 1 being best
-------
RefCoM process ranking is always higher than the mass burn or
sanitary landfill rankings.
Sensitivity analysis showed that less than optimum RefCoM
process performance does not change the ranking. Changes in MSW
management such as source separation of newspaper, yard waste
and aluminum and ferrous metals also do not impact the ranking.
Sensitivity testing of the value analysis weighting factors
shows that even when the local air emissions weighting is
doubled, the same ranking of RefCoM relative to mass burn and
landfilling is maintained.
VI. Conclusions
This study concludes:
1. There is less environmental impact as measured by
emissions, effluents, and landfill area resulting from
the RefCoM process than:
a. mass burn incineration;
b. sanitary landfilling.
2. The above conclusions are sustained even if source
• separation, suchas recycling of newspapers, yard
wastes, aluminum or ferrous metals, significantly
changes the nature of the waste stream;
3. The REFCOM SNG/COM configuration compares favorably
with the other RefCoM processes but should be given a
site specific evaluation to confirm this result. In
1032
-------
particular, the land spreading of composted residue
which contains quantities of plastics, glass, and
metal needs site specific evaluation.
Acknowledgement
This study was funded by a grant from Renewable Energy
Systems, Inc., Palos Park, Illinois. The support and guidance
of Peter Benson, President,, is gratefully appreciated.
1033
-------
REFERENCES
Isaacson, Ron, John Pfeffer, Peter Mooij, and Jim Geselbracht,
1987. "RefCoM - Technical Status, Economics and Market,"
paper presented at the Conference on Energy from Biomass
and Wastes XI, Orlando, Florida, March 16-20.
Mooij, H.P. and J. Pfeffer, 1986. "RefCoM Equipment Research
and Development Program 1976-1986, Final Report,"
DOE/CS/20038-T20.
O'Leary, Philip R., 1989. "RefCoM Environmental Assessment,
Final Report," University of Wisconsin-Madison.
Pfeffer, John T., 1974. "Temperature Effects on Anaerobic
Fermentation of Domestic Refuse," Biotechnology and
Bioengineering, Vol. XVI, pp. 771-787.
Pfeffer, John T. and Khalique A. Khan, 1976. "Microbial
Production of Methane from Municipal Refuse", Biotechnology
and Bioengineering, Vol. XVIII, pp. 1179-1191.
Pfeffer, John T. and Jon C. Liebman, 1976. "Energy from Refuse
by Bioconversion, Fermentation and Residue Disposal
Processes," .Resource Recovery and Conservation, pp. 295-
313.
Stanier, Roger Y., Michael Doudoroff and Edward A. Adelberg,
1965. The Microbial World, 2d ed. Englewood Cliffs:
Prentice-Hall, Inc.
1034
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LANDFILL REMEDIATION
GREGORY N. RICHARDSON, PH.D., P.E.
WESTINGHOUSE - EGS
PRESENTED AT THE
FIRST U.S. CONFERENCE ON MUNICIPAL SOLID WASTE MANAGEMENT
JUNE 13-16
1O35
-------
Introduction
Contemporary waste containment cells rely on a layered
system of soil liners, synthetic liners, and liquid collection
layers to prevent the migration of leachate generated in the
waste to the surrounding subgrade. Such systems have been in
common usage for 10 years in RCRA related waste containment
cells, but are just now achieving similiar usage in municipal
solid waste (MSW) waste containment facilities. This paper
discusses three landfill failures and the remediation efforts
being performed. The waste category and type of failure for the
three cases are as follows:
1 - MSW Landfill, General Foundation Failure,
2 - Industrial Landfill, Sidewall Failure, and
3 - CERCLA Closure, Cap Stability Failure.
The MSW case will illustrate the need for design review of
daily landfill operations. The remaining cases deal with
stability problems inherent in the multi-layered lining systems.
Case 1 - MSW Landfill. Maine
In mid-August 1989, a 500,000m3 landslide occurred at a
commercially operated landfill in central Maine. The landfill
material consisted of municipal solid waste (MSW) that rested on
a thick deposit of marine clay-silt which provided a natural
barrier to leachate seepage.
The movement lasted about 15 seconds. During the slide,
huge vertical crevices formed in the landfill. Trash dropped 6
1O36
-------
to 9 meters into scarps formed in the underlying clay as the
soil slid out from underneath the landfill. The landslide
occurred following a 10 day period when over 125 mm of rain
fell. During the slide, 6 large crevices opened up in the trash
pile. Some of the crevices were 15 meters wide and up to 9
meters deep. Soil was disturbed by the landslide up to 100
meters beyond the original toe of the landfill. Due to
remolding, some of the clay lost 90% of its original undrained
shear strength. At some locations, the remolded clay and silt
flowed over undisturbed soil at a shallow depth. Analysis of
the slide indicated that a rotational failure first occurred
under the original landfill slope. The rotation left steep
unsupported slopes within the trash pile and the underlying clay
and silt. Blocks of trash and clay then followed the direction
of the initial movement.
While the marine clay and silt offers an ideal natural
barrier to the seepage of leachate, the strength of the soil
limits the weight of fill which may be placed on top of it. As
the landfill expanded, monitoring wells were installed and
laboratory tests on soils were run. Some of the monitoring
wells included field vane shear tests (ASTM D2573-72) and 76mm
Shelby tube sampling. Laboratory testing included
classification, strength, and consolidation testing. Figure 1
shows typical laboratory Atterberg and consolidation test data,
as well as vane shear data, for the marine clays and silts.
Using the vane shear data and what was thought to be a
1037
-------
reasonable value for the density of the landfill, a height
limitation of 17 meters was placed on the existing MSW landfill
in mid-1986. With fill above that level, it was calculated that
the factor of safety against a slope failure would be below 1.25
for short term conditions and that was not acceptable.
Laboratory testing subsequent to the landslide and back-
calculations from the slide itself have shown that the field
vane test values were in fact considerably lower than the shear
strengths developed in the clay-silt.
However, another factor that strongly influenced the
stability of the landfill slopes was the density of the landfill
material. In the early stages of the operation, the owner had
little historical on-site data to indicate the landfill density.
Consequently, a density that seemed appropriate, based on the
appearance of the fill was used. A value of 590 kg/m3 (1000
Ib/cy) was estimated and this value seemed to be corroborated by
historical information. In retrospect, it should have been
recognized that landfill technology was changing. More
compactive effort was being applied in an effort to squeeze
greater amounts of trash into limited landfill space. In
addition, more daily cover material (sand and gravel) was being
added to control odor, birds and blowing trash. These factors
all contributed to a much higher density than originally
anticipated and used in the stability analyses that were
originally performed.
By mid-1987, weight and volume data was available to
1038
-------
indicate the density of the trash and cover was on the order of
1250 kg/m3 (2125 Ib/cy) . At that time, the height of the
landfill was nearing 12 meters. The reader will recall that an
earlier 17 meter height limitation was based on an analysis that
used a landfill density of 590 kg/m3. Without strength increases
in the clay, the computed factor of safety against a slope
failure would have been less than 1 with the height at 17
meters. Considering clay strength increase, the minimum
calculated factor of the landfill slopes was approximately 1.25
with the height at 12 meters and the density at 1250 kg/m3.
As an additional tool to monitor the stability of the slopes
while the fill height was gradually being increased, slope
inclinometers were installed on three sides of the MSW landfill.
Those were the east, south and north sides. The owner
recommended against placing the inclinometers on the west side.
The company reasoned that since expansion to the west was
thought to be imminent, inclinometers in that area would quickly
be in the way of new landfill construction. In hind sight, it
was to the west that the inclinometers would have been most
useful. As discussed below, slopes in that direction ultimately
failed because of the expansion construction activities.
From•late 1987 to early 1988 to early 1989, the height of
the MSW landfill was gradually increased to about 18 meters.
Biweekly readings on the inclinometers indicated a maximum
lateral movement of 19mm per year. This rate was judged to be
high, but acceptable.
1039
-------
In early 1989, a re-analysis of the landfill slope stability
was performed. The re-analysis used the latest height and
density information, and extrapolated strength data from the
field van shear data. The re-analysis indicated that the safety
factor for the landfill slopes was very close to 1. To increase
the safety factor, the owner decided to step back the slope at
the present fill height and add a berm where possible around the
landfill. Berms were built on the east and south sides of the
landfill to add counter weight to the slopes. Waste piles to
the north and south also provided buttressing in those
directions. Again, however, the owner was reluctant to add a
stabilizing berm on the west side of the landfill due to planned
westerly expansion.
Construction began on the westerly expansion in the late
Spring of 1989. Trees cleared, the topsoil was stripped from
the clay and silt, and all weathered soil was removed below the
topsoil. Some of the weathered soil was mined for cover
material for other landfills. Since digging into the clay and
silt would also increase the capacity of the landfill, the plans
called for the removal of 2 to 2.5 meters of soil in the
expansion area. Because the new area was to be lined and the
original area was not, a leachate collection trench was dug
adjacent to the toe of the old landfill.
In hind sight, it was probably obvious that removing strong
soil at the toe, which was supporting the existing landfill
1040
-------
slope, and then cutting a leachate collection trench deeper into
the ground at the toe, were not prudent steps to take.
Following a 10 day period when over 125mm of rain fell, the
landslide occurred.
To permit more accurate back-calculation of the clay and
silt shear strengths under the landfill just before the slide,
the owner performed a dozen large-scale density tests and 6
direct shear tests in the trash. Each density test involved
digging about 8 m3 of trash out of the fill cross sectioning the
excavation to measure its volume, and then weighing the
excavated material. The results of the density tests indicated
an average density of 1534 kg/m3 (2600 Id/cy). Those values
compare reasonably well with the overall density calculated from
1989 tipping data, truckloads of cover material hauled to the
site and volume change computed from different
photogrammetrically produced topographic maps (1503 kg/m3) .
To measure the shear strength of the trash, the owner
constructed a 1.5m2 square shear box. The box was loaded with
large concrete blocks to vary the normal force in the test.
Figure 2 provided a summary of the results.
Summary...The predicted stability failure at this MSW landfill
demonstrates the need for ongoing engineering review of the
operations of such facilities. Additionally, the measured
density of the MSW greatly exceeded that predicted by general
historical data. Thus, as even greater efforts are being
1041
-------
expended to maximize airspace utilization, the designer must
improve such design assumptions. Design of a new MSW lined cell
is proceeding for this facility. Future stability will be
ensured by limiting the depth of waste and slope of the working
face. These limits are being established using slope stability
analyses using the measured waste densities and shear strengths.
Case 2 Industrial Landfill. Ohio
During the construction of an industrial landfill in Ohio,
a layer of cover soil being placed over the synthetic liner
collapsed. This collapse resulted in much of the synthetic
liner being dragged to the base of the sideslope. The design
profile of the sidewall liner system is shown on Figure 3. As
is commonly the case, the sidewall liner system was the product
of both state regulatory demands and the designers original
intent. Interestingly, the failure occurred between the HOPE
liner and the lower slit-film woven geotextile.
Just such a failure had concerned the design engineer.
Early calculations indicated that the cover soil would be
marginally stable if the slope length was less than 79 feet. To
provide a greater margin of safety, the designer required that
no more than 15 feet of cover soil be placed in advance of the
waste.
As construction progressed, concern was expressed regarding
the ability of heavy equipment to operate on the dredge spoils
to be placed within the cell. Fearing the future inability to
1O42
-------
advance the cover soil protecting the liner, a field decision
was made to place the entire cover layer. A sliding failure
occurred as placement of the cover soil neared completion and
prior to placement of waste in the cell.
Post failure laboratory testing indicated that the
coefficient of friction between the HDPE liner and the slit-film
woven geotextile was approximately 9-degrees. This confirmed
that the weight of the cover soil was carried by tension in the
upper geotextile and the liner, by the frictional components
between the layers, and by the compressive strength of the cover
layer itself. An analysis was performed to estimate the minimum
cover soil cohesion required to maintain a minimum factor-of-
safety against sliding of 1.0. Figure 4 shows the results of
this analysis and the range of cohesion values actually obtained
from samples of the cover soil. The cause of the failure became
evident when field surveys indicated that slope lengths exceeded
120-feet.
Remediation of the sideslopes involved replacement of the
smooth HDPE liner with textured HOPE, and the use of nonwoven
geotextiles. Both measures dramatically increased the interface
friction angles between the geotextiles and the liner. This
successfully reduced the load being carried within the plane of
the cover soil. Additionally, note that the geonet drainage
layer was bonded to the geotextiles bounding it. This was
necessary to prevent placing the geonet in tension.
1043
-------
Case 3 - CERCLA Cover. Connecticut
In a CERCLA closure common to the northeast, sludges
generated from the closure of settling lagoons at an electro
plating operation were to be consolidated within the footprint
of the original lagoons and secured with an impermeable cover.
While no specific regulatory criteria exists for CERCLA covers,
EPA has generally assumed that RCRA Minimum Technology Guidance
provides a reasonable minimum cover profile. This results in
a cover that contains the following layered systems:
• Low-Permeability Barrier Layer,
• Drainage Layer, and a
• Protective Layer.
The design profile for this cover and the slope toe drainage
detail are shown on Figure 5.
The low-permeability barrier was an effective composite
formed by the 30-mil PVC geomembrane and the bentonite mat.
However, the bentonite mat has an upper surface composed of a
woven polypropylene geotextile. As in the previous case study,
the coefficient of friction between a geotextile and a smooth
geomembrane typically ranges from 9-12 degrees. Thus the cap
profile constructed on the design 3H:1V slopes would either be
unstable or would rely on the tensile strength of the filter
fabric and the geomembrane.
Just prior to letting bid documents, a geogrid was added to
the cover profile. The geogrid was placed immediately above the
filter fabric and was intended to.carry the weight of the
1044
-------
overlying cover soil. While incorporated into the project
specifications, the engineer did not modify the drawings to
indicate the proper placement of the geogrid. Fortunately, the
small size of the cap, < 1/2 acre, allowed the geogrid to be run
continuously across the breadth of the cap.
While no failure occurred in this cap, the success was due
to the small size of the cap and not to the technical ability of
the designer. No stability calculations had been performed and
no geogrid installation guidelines were prepared.
Interestingly, the EPA review process did not detect these
omissions.
Summary
The rate of failures within waste containment systems is
increasing. This increase rate can be directly traced to the
following factors:
The need for the design engineer to establish operational
guidelines that ensure the stability of the facility as
waste is being placed, and
Sliding instabilities generated when two geosynthetic
materials are used in contact on slopes.
Both designers and regulatory reviewers must ensure that
stability calculations are prepared for construction profiles,
operational conditions, and closure profiles. Such stability
calculations should be used to establish operational guidelines
for placement of waste within the waste containment system.
1045
-------
a
I
3
I
s
0.7 -
&B -
O** •
03
OJt
0.1
1.9 -
1.8 •
1.7 •
1.8 •
1 J •
1.4 •
U •
1.2 •
1.1 •
1 •
0.« •
O.* <
O.7
-------
£
o
5T
(0
tn
in
Q)
^
55
i.
n
o>
£
lO
0.5-
0.4-
0.3 -
0.2-
0.1 -
—i—
0.2
—i—
0.3
0.1 0.2 0.3 0.4
Normal Stress, Kg/sq.cm.
Figure 2 - MSW Direct Shear Test Results
Figure 3 Failed CERCLA Liner System - Case 2
1047
-------
u
a
/-
o
b)
1000
dl
Ceo
AD
£,e>
fto
100 izo
Figure 4 Cover Soil Shear Strength vs
Stable Slope Length - Case 2
12" TRAP ROCK
e't
FILTER FABRIC
f_ PVC ITfEMBRANE
BENTONITE MAT
'—GEOTEXTILE CUSHION
12 i
Figure 5 Initial CERCLA Cover System - Case 3
1O48
-------
CASE STUDY:
LBACHATB CONTAINMENT IN AM OLD LANDFILL
SPRINGFIELD ROAD LANDFILL - HENRICO COUNTY, VIRGINIA
DONALD O. NUTTALL, P.B.
DRAPER ADEN ASSOCIATES
4136 INNSLAKE DRIVE
GLEN ALLEN, VIRGINIA 23060
804-270-7675
Presented at the
First U. 8. Conference on Municipal Solid Waste
Jane 13-16, 1990
1049
-------
SPRINGFIELD ROAD LANDFILL
LEACHATE REMEDIATION PROJECT
INTRODUCTION
New regulations and new facilities have held our
attention and much of the limelight in recent months and
years. Many states, with their eyes set on the future, are
implementing tougher regulations for a new generation of
environmentally sound landfills. But what of the old
facilities/ the ones already in the ground. They have
received little attention though many regulations require
remedial action to control offsite leachate migration or
documented groundwater pollution.
A great deal has been written and said about liner
systems, leachate management systems and the other features
of a modern landfill. But we hear little about how to deal
with the older sites which are going to be with us for years
to come.
This paper will explain how a corrective action project
was planned, designed and implemented at an existing landfill
in central Virginia. The landfill is a municipal solid waste
landfill located in Henrico County Virginia, a suburban
community of Richmond, Virginia.
1050
-------
In 1985, efforts began to plan for an expansion of the
landfill. As part of that process, a detailed geotechnical
Investigation was made of the landfill. During that
investigation it was discovered that there may have been
problems with contamination of a major drainage feature*
called Rooty Branch which flowed between the two main fill
areas of the landfill. These indications caused concern that
there might also be leachate entering Aliens Branch and the
Chickahominy River which form the west and north boundary of
the site. (The general configuration of the site is shown on
Figure 1).
With these concerns in mind, the first step was to review
in detail the available data on the site ground water and
surface water quality. In addition the depth and direction of
groundwater flow and the surface of the bedrock underlying
the site were mapped. This revealed that the landfill was
situated on a thin soil overburden over a granitic bedrock.
In some places, the depth to bedrock was as shallow as 5
feet.
Review of the data indicated that the flow of ground
water was along the bedrock surface toward Rooty Branch. The
flow ran under the existing landfill sections known as the
1051
-------
?00
o
CJl
to
1-295
DRAPER-ADEN ASSOCIATES, INC.
Sf-RlfJGriELO ROAf LAN'DFILL
MASTER PLAN-EXISTING SITE PLAN
8304
OR* WING
-------
western and eastern fills. There was no flow toward Aliens
Branch or the Chickahominy River which bordered the site.
Flow in the northeast and northwest direction was blocked by
rock ridges. The slope of the bedrock was found to be toward
Rooty Branch, this meant that the leachate flow could be
confined and possibly intercepted at Rooty Branch.
Analysis of the ground water and surface water data
confirmed the analysis of the hydrogeologic situation. The
levels of indicator parameters in Rooty Branch were generally
higher than in the other water courses. (Figures 3,4 and 5
/
illustrate selected readings for Chlorides, Iron and TDS in
Rooty Branch). The initial indications led to the conclusion
that leachate from the landfill was entering Rooty Branch.
Based on the results of the initial investigation the
decision was made to find a way to prevent the contaminants
from leaving the landfill and entering Rooty Branch. The next
step in the process was the determination of the best method
of achieving that goal.
The alternatives considered were (1) rerouting of Rooty
"Branch, (2) the lining of the creek and (3) the hydraulic
isolation of the creek in its existing location. Relocation
of the creek was eliminated from consideration first, due to
1053
-------
its high cost, the amount of landfill space which would have
baen lost and the potential for creating pathways for
leachate movement since significant blasting of the bedrock
would have been required.
The second option, lining of the creek, would have
separated the surface water from the ground water but would
not have done anything to prevent movement into the
groundwater. The alternative of hydraulically isolating the
creek appeared to meet the goal of controlling release of
contaminants into the Rooty Branch drainage course, with few
negative effects.
Several methods were considered to achieve this
isolation. They included the Installation of concrete or
sheetpiling walls down to bedrock; trench drains around the
landfill and slurry walls. In the end, the alternative
selected was to straighten the meandering course of Rooty
Branch, Install perforated drains along the toe of the
Existing landfill to intercept any leachate leaving the
landfill and to Install a soil bentonite slurry wall down to
bedrock in the area between the creek and the perforated
drains. In this way any leachate leaving the landfill and
flowing toward the creek would be intercepted and diverted by
the drains to a pump station which would pump the leachate to
a regional wastewater treatment system. The slurry wall
1054
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would act as a barrier to isolate the creek from the
landfill. (Figure 2 illustrates the concept in schematic
form).
SYSTEM DKSIGH
Design of the features of this project presented several
challenges. How could a bentonite slurry be installed in
ground which was known to contain contaminants? Where were
the limits of the landfill so the drains could be placed
properly? How could the slurry wall be protected from the
traffic and construction activities associated with landfills
and how would it fit into the final closure configuration of
the landfill? How could this system best fit into the overall
landfill design? Could some elements of this system be used
in conjunction with other parts of the leachate collection
system for the existing and future landfill disposal areas?
The final configuration achieved answers to many of these
questions. To reduce the effects of the known contaminants in
the ground where the slurry wall was to be installed, the
excavated soil was removed and not used for slurry backfill
mix as is common practice. Clean soil was imported for use in
the backfill mix. A bentonite which is listed as contaminant
resistant was specified. The water source for the slurry
1O55
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REFUSE FILL
A\\\\\
/v\\\\\\x\\\
BENTONITE
SLURRY WALL
LEACHATE COLLECTORS
HYDRAULIC ISOLATION OF ROOTY BRANCH
FIGURE 2
-------
mixture was tested and approved. Use of the water in Rooty
Branch itself was not permitted.
The configuration of the drain and slurry wall system was
based on information gathered from the operating personnel
who actually built the landfill and from test pits dug to
confirm the limits of fill. The geotechnical mapping of the
landfill gave information to guide decisions on the depth of
the drains and slurry wall.
The slurry wall was designed to tie into the shallow
bedrock on either side of Rooty Branch at both ends of the
project. This was done to help achieve isolation by tying the
slurry wall into the bedrock ridges which isolated the other
parts of the site. Protection from desiccation, erosion and
traffic was achieved by an 18 inch soil cap over the wall at
the ground surface.
The trench drains are designed to be incorporated into
the overall landfill leachate collection system. The trench
drains act as the gravity connection between the leachate
collection system on the eastern side of the landfill and the
main pump station. The trench drains also connect the
leachate collection system from the landfill expansion area
1057
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to the main pump station. All collected leachate is pumped to
a regional wastewater treatment facility.
The final phase in this project will come when the old
fill areas have been finally capped out and closed. This
measure will have the most dramatic affect on leachate
reduction. The landfill is still in operation and final
capping will not be in place for several years.
CONSTRUCTION
Construction of the improved channel of Rooty Branch, the
trench drains and the slurry wall took place during the fall
of 1987 and the spring of 1988. Though the construction went
smoothly, there were two problems which were of particular
note because they potentially could have affected the project
goals.
The trench drains were to have been installed down to the
rock surface. The rock surface was found to be more irregular
than was expected. It became necessary to resort to some
minor blasting to achieve the required grades to make the
drains work properly. Rock was excavated as much as possible
with heavy backhoes. Only blasting which was absolutely
necessary was allowed and then only with light charges. This
1058
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Was done to minimize the chance of fracturing the rock and
creating new pathways for leachate migration.
The installation of the slurry wall presented one problem
which required field correction. Bench scale tests were
performed to determine the appropriate bentonite content for
the soil/bentonite backfill of the slurry wall when onsite
soils were used for the mixture. Field mixtures revealed a
problem with workability not found on the laboratory scale.
The soil/bentonite mixture would not flow into the trench. In
fact, the mixture acted much like a wet clay and was very
cohesive. Additional lab tests found that the cohesive fines
in the mixture were creating this situation. It was decided
to add additional coarse material in the form of sand to the
mixture to create the proper slump and flow characteristics.
SYSTEM EFFECTIVENESS
The effectiveness of the system is still being evaluated.
The presence of contaminants in the soil between the slurry
wall and the creek make evaluation by sampling the creek
somewhat difficult. However there are some encouraging trends
being observed. The level of contaminants in Rooty Branch has
been steadily downward. (Figures 3,4 and 5 indicate the
downward trend). Continued flushing of the soils between the
1O59
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creek and slurry wall will undoubtedly help in reducing the
contaminant level.
A reduction in contaminants began before the
installation of the slurry wall. It is believed this can be
attributed to several factors. One was the exceptionally dry
year preceding the construction which limited leachate
generation. A second was the temporary capping of the eastern
fill when daily fill operations moved to an adjacent area.
Finally, the removal of much of the contaminant laden soil
from Rooty Branch as it was being straightened is considered
to have contributed to the decrease.
One notable example of the effectiveness of the project
has been detected in the landfill groundwater monitoring
program. One of the site monitoring wells is located in the
area which lies between the slurry wall and Rooty Branch. The
well traditionally have contaminant levels similar to the
creek. Since the installation of the project, the well has
been dry, indicating no flow from the landfill to the creek.
CONCLUSIONS
The design of any project to isolate and control leachate
from an old landfill requires a detailed understanding of the
1060
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o
p
ROOTY BRANCH SURFACE WATER DATA
CHLORIDES - FIGURE 3
(mg/l)
100
75
25
i I I I 1 1 1 L
On Site
3/86 6/8610/862/87 6/8710/874/88 9/88 1/89 4/89 8/87
Sampling Event
-------
5
8
ROOTY BRANCH SURFACE WATER DATA
IRON - FIGURE 4
(mg/l)
12
10
o __
I I t I I I
On Site
2/BB 6/86 10/86 2/87 6/87 10/87 4/88 9/88 1/89 4/89 B/89
Sampling Event
-------
ROOTY BRANCH SURFACE WATER DATA
TDS - FIGURE 5
Concentration (mg/l)
500
400
300
O
0)
CO
200
100
On Site
3/86 6/8610/863/87 6/8710/874/88 9/88 1/89 4/89 8/88
Sampling Events
-------
hydrologic and geologic setting of the entire site. Once such
an understanding has been established, a variety of
alternatives should be evaluated, the goals of the
alternatives should be the isolation of the source of
contaminants collection of the contaminants and reduction of
leachate generation. This project has attempted to meet the
first two goals. Final closure and capping of the site will
address the final goal.
1064
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MANAGING OUR SOLID WASTES:
DEVELOPING AN EFFECTIVE SITING FRAMEWORK
Michael J. Regan
Research Triangle Institute
R. Gregory Michaels
U.S. Environmental Protection Agency, OPPE
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16,1990
1O65
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Managing Our Solid Wastes:
Developing an Effective Siting Framework
Introduction
The conflict over solid waste management continues to escalate in many parts of the
country and is likely to be a pressing public policy issue throughout the 1990's. Even
with increased source reduction, recycling, and composting, new waste disposal facilities
will be needed to manage our growing waste stream. Finding new sites, however,
promises to be extraordinarily difficult.
Efforts to site new landfills and waste-to-energy facilities, and even recycling transfer
stations, have been met with mounting opposition from community groups. Much
attention has been paid to the so-called NIMBY (not in my backyard) syndrome which
portrays local residents as emotional opponents of new facilities while often ignoring the
complexity of the underlying issues. In most cases there is a fundamental disagreement
among different groups and individuals over whether the facility is needed, if it is safe, if
the siting decision is fair, and/or who should make the decision.
Rethinking the Traditional Siting Process
In the traditional siting process—sometimes called the Decide, Announce, Defend
model—decision-making power is concentrated in the hands of a few, key local
government officials. Communication is often limited to legal requirements for technical
information (such as environmental impact studies) and a mandatory public hearing. The
general public is not confronted until key risk management decisions already have been
made, at which time they are presented with a fait d'accompli. At this point, the level of
public opposition becomes intense and both sides become polarized. Although the
traditional siting process has been modified, the basic tenets of an exclusionary siting
process persist to this day.
1066
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Each of the statements below highlight an important dimension of the facility siting
problem and each presents public officials with a different set of challenges.
1) The siting problem is not simply a technical one—it is social, economic, and
political. Public opposition to landfills or incinerators is not always generated by the
same siting issue, nor is opposition limited to any single issue in a given case. For
example, public officials might face conflict over estimates of public health risks, equity
in site choices, property value impacts, and the distribution of benefits and burden among
community residents. All of these concerns influence an individuals sense of risk from a
new facility. The solution to the problem must reflect the nature of the problem—a
technical solution simply will not work.
2) The public fears and mistrusts technical information and the people who
communicate it. As with many risk management problems, the credibility of technical
information has been a major battleground in siting disputes because of a history of
inappropriate use, scientific uncertainty, and communication barriers. For example, a
hydrogeological study might be legitimately disputed by an independent expert. In other
cases, participants might manipulate the use of information in the communication process
to achieve particular ends. Also, many lay people find technical studies
incomprehensible because of technical jargon.
The role of technical information remains critical to making good public policy. But,
members of the public are making decisions based on incomplete information or
information that is difficult to process. Both citizens and officials need good, relevant
information to make better decisions about the key controversial issues.
3) Many citizens have lost confidence in the decision-making process for solid waste
management and now demand greater access and involvement. Citizens object to the
1O67
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process by which land use decisions have been made in the past. They are concerned
about past facility mismanagement, the credibility of public officials, and the growing
pressures on the environment from our society. Members of the public have
demonstrated that they will not sit by while important waste management decisions are
being made. An effective siting process must be able to incorporate public concerns into
the siting decision.
A Comprehensive Siting Strategy
Each siting effort requires a strategy tailored to the specific needs and concerns of the
community. Nevertheless, experience from other successful siting suggests that effective
public involvement should be the centerpiece of a comprehensive siting strategy that also
includes risk communication, mitigation, and evaluation activities. This siting strategy is
presented in an EPA publication, Sites for Our Solid Waste: A Guidebook for Effective
Public Involvement (1990).
Public Participation
Public participation can bring trust and credibility back to the siting process but is not
a guarantee for success. Citizen advisory committees, public meetings, and workshops,
among others, have proven successful in both resolving conflicts and producing effective
waste management policies. Note, however, that the success of the program does not
depend on the number of meetings held, rather the quality of the implementation. Public
participation is not just window dressing—token participation often backfires by fueling
fears and mistrust. Instead, effective public participation requires integrating public
concerns and values at every stage of the siting process.
In particular, officials should take steps to understand the various groups and interests
in the community as well as develop a public participation plan that outlines the activities
that will be conducted, their sequence and timing, and responsibility for carrying out each
1068
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activity. A comprehensive public participation program is a sizeable effort that requires
careful planning and a significant commitment of time and staff. But the alternative may
be to go through a prolonged, divisive, and expensive siting process and still find yourself
at square one.
Risk Communication
The term risk communication has different meanings for different people, often
depending on their individual or institutional goals. Many officials restrict its meaning to
the dissemination of scientific information to the public by official sources. For example,
the Department of Health might want to translate findings from hydrogeological studies
into a fact sheet for homeowners.
The National Research Council (1989) recently noted that risk communication is
more than simply designing and communicating risk messages to the public; it is a two-
way process that provides government, industry, and individual decision makers with the
information they need to make risk management decisions. For example, the siting
proposal might win support from nearby residents if they take steps to mitigate negative
impacts.
Public officials should be aware, however, that communication programs are complex
endeavors with many pitfalls. For example, conflicting perceptions of risk among
individuals make it difficult to develop effective risk messages. The news media have
difficulty reporting scientific risk estimates. And, communicators must decide whether
they will simply inform the public's judgment or attempt to manipulate behavior. Many
resources exist to help officials understand the complexities of communicating about
potential risks to public health.
Risk communicators should also establish a set of policies and procedures that ensure
that risk messages are both accurate and credible, such as getting participation in the
study plan, providing technical assistance to the public, and presenting technical
1O69
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information in understandable language. These steps will not remove all challenges, but
by taking them you reduce the chances of opponents gaining political support by
questioning the technical adequacy of studies.
Mitigating Negative Impacts
Some public policy issues in local communities, no matter how sensitive to the
concerns of residents, are bound to have negative consequences for a few people. It is
necessary, however, to find more immediate and direct means of mitigating these
negative impacts. Mitigation might take any one of three forms: direct compensation,
more advanced technical safeguards, or more extensive environmental monitoring. For
example, a community in New England restricted the number of trips made by non-local
haulers to a regional landfill. In a Florida community, a property value guarantee has
been made to nearby homeowners.
It is important to note that people view health and safety in terms of safe and unsafe.
If they perceive a facility is safe, then it is possible to talk about other issues. If they..
perceive a project poses a genuine risk to health or safety, then everything else is non-
negotiable.
Evaluating Effectiveness
Evaluation can improve the management of the complex planning and
implementation activities. Project leaders find themselves making important decisions
throughout the siting process based on their judgment of the effectiveness of specific
siting activities. This type of "intuitive" evaluation is often hindered by preconceived
ideas about what people want, as well as the frantic pace of everyday life at the office.
By evaluating the effectiveness of your siting strategy, you are trying to learn which
activities are working, which activities need improvement, and which siting issues have
107O
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not been addressed. Evaluation tools can help provide important feedback to decision-
makers in a timely, cost-effective way.
Conclusion
The trash problem in the United States has no easy answers, and the conflict
surrounding the siting of solid waste facilities will be with us for many years. Just as the
issues and challenges facing public officials and citizens have changed over the last two
decades, we should also expect new issues and new challenges to emerge in the coming .
years.
The siting strategy presented in this paper is not a recipe for success. It tries to
overcome some of the obvious deficiencies in the traditional siting process while
providing a flexible framework for tailoring the strategy to the particular needs and issues
of different communities. Experiences from around the country suggest that solutions to
the waste management problem, and the siting impasse in particular, will require a
cooperative effort among public officials, waste management professionals,
environmental advocates, and private citizens.
1071
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Sources
Krimsky, Sheldon and Alonzo Plough, Environmental Hazards: Communicating Risks As
a Social Process, Auburn House Publishing Co., Dover MA, (1988).
National Research Council, Improving Risk Communication, National Academy Press,
Washington, DC, (1989).
O'Hare, Michael; Lawrence Bacow; and Debra Sanderson, Facility Siting and Public
Opposition, Van Nostrand Reinhold Company, New York, (1983).
U.S. Environmental Protection Agency £itesfor Our Solid Waste: A Guidebook for
Effective Public Involvement, Washington, DC, (1990).
U.S. Environmental Protection Agency Decision-Makers Guide to Solid Waste
Management, Washington, DC, (1989).
1072
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MIDWAY LANDFILL
Bruce D. Jones, P.E.
Seattle Solid Waste Utility
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
1O73
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MIDWAY LANDFILL
Background
The Midway Landfill/ a 60-acre site approximately 15 miles
south of Seattle, was used as a gravel pit from 1945 to 1966
(see figure 1) . In 1966 the City of Seattle began using it as
a landfill for nonputrescible waste (such as demolition debris,
woody wastes, and yard clippings). The landfill is bounded on
the east and west by major north-south highways (Interstate 5
and Pacific Highway South, respectively). Residential
neighborhoods are clustered to the east and south of the
landfill; commercial businesses and light industries are on the
west, and a mobile home park, drive-in theater, and some
undeveloped property are to the north. The City stopped
disposing of waste at the landfill in 1983.
Landfill Gas Migration
The landfill was initially brought to public and regulatory
attention in 1985 by the discovery of subsurface gas
infiltrating nearby structures. Residents were evacuated from
their homes in several cases due to concerns about the
concentration of combustible gasses accumulating in the houses.
This occurred in late 1985 and early 1986. The City of Seattle
and the Washington Department of Ecology installed gas
extraction wells in the affected neighborhoods and gas migration
control wells on the perimeter of the landfill.
1074
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Midway Landfill HI — City ot Seattle
HlGHLINE
COMMUNITY
COLLEGE
PARKSIDE
ELEMENTARY
SCHOOL
SUNNYCREST
ELEMENTARY
SCHOOL
SCALE IN FEET
n_ri
500 l.OOii
1075
Figure 1
Location Map
-------
In 1986, the Environmental Protection Agency placed the
Midway Landfill on the National Priorities List. A Remedial
Investigation/Feasibility Study (RI/FS) was begun and completion
is expected late this year. The RI was an intensive effort by
the City of Seattle to investigate the landfill's actual or
potential impact on human health and the environment. The
investigation covered surface water, ground water, soils,
landfill gas and ambient air. The RI found that the gas
extraction system stopped the off-site migration of gas, removed
the gas from the structures and created a permanent system to
prevent future gas migration.
Good Neighbor Program
During the period of time when gas migration was occurring
and homes were being evacuated, property values were dropping
drastically. While the City was working to control the gas
migration, it established a Good Neighbor Program to maintain
property values. The program allowed home owners to sell their
home at a Fair Market Value established by the average of two
appraisals. The homeowner and the City of Seattle each obtained
an appraisal and the two were averaged to determine the Fair
Market Value (FMV). The City could subsidize the purchase by
another party to insure the seller received the FMV or the City
could purchase the house for that amount and continue to market
it. The program ended after 10 homes were sold at FMV which
took about two years. During the program, 269 homes were sold
through the program and the City purchased 165 of them.
1076
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After selling all but one of the homes, the net cost to the City
for the program is approximately $5 million including all
related management costs, real estate commissions, house repairs
and price subsidies.
Ground and Surface Water
The next most serious concern of the RI was the potential
for groundwater contamination by leachate from the landfill
because of the large amounts of water known to enter the
landfill by various means, including direct infiltration of
precipitation, infiltration of runoff from surrounding property,
and inflow from stormwater drains. During additional leachate
sampling conducted as part of a treatability study for the FS,
an oil was found floating on the aqueous phase leachate. The
oil was found to be contaminated with polychlorinated biphenols
(PCB's). A program was instituted to install 9 additional wells
in the landfill to help determine the extent of the contaminated
oil. Once the extent was determined to be isolated pockets,
pumping began to remove the material before completion of all of
the surface water management projects and the cap resulted in
dewatering of the landfill. only a small amount of oil was
recovered, approximately 100 gallons, and recharge of the wells
with oil has been minimal.
A surface water management plan was prepared that would
minimize the generation of leachate from surface water.
1077
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The plan included a pumping station to eliminate a stormwater
discharge into the landfill, a 10 million gallon detention pond
to store water from the pumping station, the landfill surface
and some areas surrounding the landfill, and a pipeline to carry
the stormwater to a creek approximately one mile to the west.
No evidence was found during the RI of off-site transport of
contaminants in surface water runoff from the landfill.
Ambient Air
Ambient air quality in the vicinity of the Midway Landfill
was not found to be measurably different from typical urban air.
The air moving across the site did not appear to show any
consistent increase in contaminant concentrations that could be
attributed to the landfill. Widespread low levels of
contaminants in ambient air appear to be coming from off-site
sources, including vehicle emissions from 1-5 directly east of
the landfill boundary.
Final Cover
Currently, the cap for the site is under construction (a
cross-section of the cap design is shown in Figure 2) . It
includes a base cover of low permeability material placed during
excavation of the detention pond in 1988. This material varies
in depth from 2 to 20 feet and provides the general grade
necessary to carry surface runoff to the detention pond. A foot
of clay is being placed on top of the existing subgrade.
1078
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MIDWAY LANDFILL COVER
vegetation/soil
top layer"
geotextile filter-
50-mil FML-
low-permeability
FML/soil layer"
waste
topsoil mix
• a X •• " »• :
! sand
e . .- c ". .' o '
«» :
o e€
1 foot
1 foot
geonet
drainage layer
1 foot
2 to 18 feet
NOT TO SCALE
Figure 2
1079
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The next layer is a 50 mil layer of high density polyethylene.
Then a synthetic geonet material is placed for a drainage layer
and covered by a filter fabric. It is then covered with one
foot of sand and one foot of topsoil and seeded.
Costs
The overall cost of all of the work at Midway is over $50
million. A breakdown of the costs is shown in Table 1.
TABLE 1
PROJECT ELEMENT COST ESTIMATE (MILLIONS)
Preliminary Engineering
Environmental Impact Statement $ 3.1
Remedial Investigation/Feasibility Study $ 5.7
Good Neighbor Program $ 5.2
Claims/litigation $ 12.3
Right-Of-Way $ 1.3
Surface Water $ 9.0
Gas Control ' $ 6.0
Final Cover $ 9.1
Staff Costs $ 1.2
TOTAL $ 52.9
1080
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CLOSURE OF THE CITY OF BOYNTON BEACH LANDFILL
USING VERY LOW DENSITY POLYETHYLENE (VLDPE)
Robert Mackey
Post, Buckley, Schuh & Jernigan, Inc.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13- 16, 1990
1081
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CLOSURE OF THE CITY OF BOYNTON BEACH LANDFILL
USING VERY LOW DENSITY POLYETHYLENE (VLDPE)
INTRODUCTION:
During the 1980's, Palm Beach County Solid Waste Authority has gradually taken
over the responsibility from most municipalities within it's jurisdiction for the disposal
of their solid waste. Previous to that period, each municipality within Palm Beach
County was responsible for disposal of its own solid waste.
The City of Boynton Beach obtained a 40-acre site in 1958 from Palm Beach
County for use as a landfill. This site was utilized through 1976 as an open landfill
that accepted most types of waste, ranging from septic sludge to typical household
refuse. It was a common practice in the past, for municipalities in this area to dispose
of their waste in abandoned sand borrow or rock pits. It was believed that the City
of Boynton Beach was no different in this aspect. Information contained in files
retained by the City, the Palm Beach County Health Department (PBCHD), and
the Florida Department of Environmental Regulation (FDER) alludes to this type
of disposal of refuse below the water table in the southern end of the 40-acre site.
The southern and western boundaries of the 40-acre site are dilineated by canals:
Equalizing Canal 3 (E-3) defines the western boundary and Lateral Canal 20 (L-20)
defines the southern boundary (See Section 2.2). These canals are part of the local
Lake Worth Drainage District (LWDD). The City of Boynton Beach Municipal Golf
Course lies to the west of the site beyond the E-3. A residential development, called
Le Chalet, has been constructed south of the site, and is serviced by a public water
supply system. The land east of the site was a fish farm from the early 1960s until
it was sold in early 1985. This land was bought by a developer who has cleared and
1O82
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and developed it for a residential development called Arbor Glen, which is also on
public water.
The area north and northeast of the old landfill site has, since the early 1960s,
witnessed an increase in the number of private residences. The first residence was
the Brandywine Horse Ranch, located on Palm Way. Today there are well over 50
private residences in the area north of the site and west of Haverhill Road Extension.
No public water supply system or wastewater collection system serves this area.
Therefore, each residence has its own private water supply well and septic tank.
The creation of Chapter 17-7 of the Florida Administrative Code (FAC) in October
1974 established a permitting process for the use of sanitary landfills in the State
of Florida. To obtain enough time to conform with the rules and regulations of
Chapter 17-7, the City of Boynton Beach applied in January 1975 for a temporary
operating permit for the continued use of its sanitary landfill. On March 12, 1975,
FDER issued a permit to the City, which was valid until March 7, 1976.
At the time, the staff of the City of Boynton Beach prepared a report including
all of the information required by FDER for the operation of a sanitary landfill.
This report was submitted to FDER in December 1975, and is believed to have been
the first submitted under the new Chapter 17-7 rules and regulations. This report
did not, however, fulfill the requirement for a hydrogeologic study of the strata
underlying the site, and the City requested an extension of its temporary operating
permit through July 1977. The FDER granted two extentions: the first, carried
the City through from March 1976 to March 1977; the second overlapped the first
and was only for the six-month period from January through June 1977. The disposal
of sewage sludge at the site was-discontinued in December 1976.
The City of Boynton Beach initially took steps to get the necessary hydrogeological
data so it could still utilize its sanitary landfill. But, on May 19, 1977, the City
1083
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notified the FDER by letter that the site was no longer going to be used as a sanitary
landfill because the City could not comply with the regulation that disallowed the
operation of a sanitary landfill within 1,000 feet of a water supply well. The City
also expressed concern to FDER about the private residential wells located north
of the site, if the sanitary landfill should continue operation. Thirteen private water
supply wells already lay immediately north of the landfill, and this number was
increasing as more homes were being built in that area.
The City continued using the site as an 8-acre trash-composting faciltiy on the
northern half of the site and obtained permits for its operation until July 1, 1983.
The remaining waste material that was not permitted at the trash composting facility
was sent to the nearby Lantana Sanitary Landfill.
With the operating permit for the trash facility due to expire in July 1983, the
PBSHD sent a letter to the City on February 27, 1983 outlining the reasons for
performing a hydrogeologic investigation at the landfill site. These reasons were
as follows:
0 Past practices of disposing of putrescible waste into the water table
0 Numerous depressional areas on top of the landfill
0 Inadequate final cover material for the proper closure of the landfill
0 An increase in the level of pesticides in the monitoring wells
0 Groundwater sample analyses showing a general deterioration of water quality
at the landfill, specifically for iron, chemical oxygen demand (COD), total
dissolved solids (TDS) and chloride
0 Numerous private homes to the east and north of the landfill, using private
wells for potable water supply
The FDER requires that all inoperative landfills be properly closed to reduce
potential pollution problems. Moreover, prior to the development of a closure plan,
1084
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a hydrogeological investigation should be conducted, since the results of the
investigation predicate the closure design for the landfill.
In early 1984, the City of Boynton Beach decided to close the old landfill at the
site rather than reactivate the trash facility. It then requested proposals from
engineering consultants to conduct a hydrogeologic survey of the site and develop
a closure plan, with the intention of creating a 9-hole golf course that would
eventually be connected to the City's Municipal Golf Course, west of the site.
HYDROGEOLOGICAL STUDY & CLOSURE PLAN:
Post, Buckley, Schuh and Jernigan, Inc. (PBS&J) was selected as consulting engineers
by the City to conduct a hydrogeological investigation and to develop a closure plan
for the old landfill. Jammal and Associates was selected to conduct the soil-boring
program and drill the monitor wells installed in the first phase of the drilling program.
The Testing Laboratory of the Palm Beaches was selected to drill the additional
monitor wells that were installed in the second phase of the drilling program. This
report was submitted to the City of Boynton Beach in May 1986, and then revised
and resubmitted in November, 1986.
The purpose of the hydrogeological report was to gather into a single reference
all the required and relevant data that will assist in the understanding of the local
hydrogeology, to describe the field work conducted at the site, and to analyze the
collected data and interpret the effect of the landfill on the surficial aquifer system
and the nearby private water supply wells. The report presented all the information
required to permit the design of a closure plan and, in so doing, described the existing
hydrologic conditions at the site, the quality of the groundwater, and the potential
threat, if any, of further contamination.
The results of the water quality analyses indicated that a leachate plume underlying
the site is made up of two areas of high contamination: one in the northeast corner
1O85
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and the other in the central area of the site. For iron and lead, the contaminant
center in the northeast corner was a horse manure pile. Dead and decaying vegetative
matter in the marsh area and the organic matter from the horse manure pile together
affected the water quality in the upper zone of the surficial aquifer system in the
northeast corner and north of the site. The high levels of various metals, such as
iron, lead, strontium, etc., identified in the central area of the site were not at
the time considered to be a public health hazard, because of the semiconfining layer
underlying the area in which they were found. The volatile organic compounds
identified in various monitor wells at the site were also not considered to present
a public health hazard. The high chloroform levels found in Monitor Well 13 were
believed to be a localized occurrence resulting from an earlier well chlorination.
The monitor wells to the north of the landfill indicated that the contaminant plume
had not expanded beyond the northern boundary of the site. Therefore, the report
recommended that the City of Boynton Beach establish a quarterly water quality
sampling program to monitor any movements in the contaminant plume. The water
quality sampling program would monitor quarterly the leachate indicator parameters.
It was believed that the rainfall that recharged the upper zone of the surficial
aquifer system in the area of the landfill leaches through the landfill mound and
replenishes the piezometric mound. Although it moved slowly, the groundwater
flow from this piezometric mound flowed away from the landfill site. Therefore,
it was recommended that the City of Boynton Beach proceed with landfill closure
to eliminate the infiltration of the rainfall through the landfill. The closure of the
landfill would also greatly reduce, if not eliminate, the piezometric head differential
between the upper and lower zones of the surficial aquifer system, which could induce
contaminated water into the lower zone.
As directed by the City of Boynton Beach, PBS&J proceeded to develop closure
1O86
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plans for the 40-acre landfill site. As part of the closure plans, PBS&J had to meet
three major objectives of the closure design:
0 Meet FDER Closure Rules
0 Meet South Florida Water Management District (SFWMD) Regulations
0 Design the closure for the end use of a 9-hole golf course
The FDER Closure Rules require the landfill closure plan to develop a landfill
gas management plan, a groundwater monitoring plan, a landfill cap design and a
stormwater management plan. Since the landfill was nearly 30 years old and tests
for methane presence proved negative, the landfill gas management plan required
only the placement of landfill gas monitoring wells along the perimeter of the site
and within the landfill mound itself. The Groundwater Monitoring Plan had utilized
the previously submitted hydrogeological report to develop the monitoring plan for
the site. The Stormwater Management Plan had to be developed and approved by
the SFWMD. The ability to meet the SFWMD requirements and develop the required
landfill closure design offered PBS&J's greatest challenge.
Like most old landfills, the City of Boynton Beach had utilized almost the entire
40-acre site for its landfill operation. The marsh area in the northeast corner of
the site was the only area which was believed not to contain buried refuse. The
SFWMD requires all stormwater runoff from a site to be retained in a ponding area
before discharge into an open water way. This stormwater management rule required
the construction of dry retention basins on the landfill site. The FDER requires
that all buried waste must be covered by a clay or synthetic liner or removed from
the ground in areas which are not covered. The need to meet the SFWMD and FDER
rules and still design the site to be utilized as a golf course required close coordination
of PBS&J's Solid Waste Division, PBS&J's Land Development Division and the golf
course designer of Von Hagge & Devlin, Inc.
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The closure plan was eventually developed which took into account all the design
requirements. The plan required a contractor to excavate out buried refuse from
various areas of the landfill in order for a dry retention area to be constructed of
sufficient size to retain the rainfall volume from a 25-year storm effecting a 40-acre
site. A berm was designed around the entire site to direct the stormwater to the
dry retention areas. An outfall structure was also designed to allow a maximum
discharge of 10 cfs. All excavated refuse was required to be placed on top of the
mound and covered by either a 20-mil PVC or HDPE synthetic liner system. The
closure design took into account the end-use of a 9-hole golf course to be developed
at a later date by the City of Boynton Beach.
The Closure Plan was approved by FDER in late 1988 and construction started
in mid-spring of 1989.
LANDFILL CLOSURE CONSTRUCTION:
The City of Boynton Beach awarded the closure construction contract to Ranger
Construction of Boynton Beach with Gundle Lining Corporation as the subcontractor
to install the synthetic liner. The contract had an additional requirement that
stipulated that the contractor could not perform any work after dark. Since the
landfill had become a sensitive issue over the years, it was hoped that this requirement
would help relieve any new public relation problems. Before construction started,
Gundle Lining Corporation requested that they be allowed to use their new 20-mil
very low density polyethylene (VLDPE) instead of contracted 20-mil HDPE. Gundle
Lining Corporation promoted the VLSPW's greater flexibility and percent elongation
(900% @ break) as better product for landfill caps. Gundle also gave assurances
that the VLDPE would meet contract specifications and not cause the City of Boynton
Beach any additional cost. After a review of the material, PBS&J and the City
of Boynton Beach approved the use of the VLDPE for the landfill closure.
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Once the contractor started clearing and grubbing the, by now overgrown, 40-acre
site, several problems became apparent. These problems encompassed not only
assumptions of the closure design but also public relations with the residents of
Arbor Glenn Estates. It appears that the residents of Arbor Glenn Estates, (especially
the owners of properties which abut the landfill) had no idea that they lived next
door to an old landfill. The property owners informed the City that they had been
told that the neighboring property (the landfill site), was to be developed into a
golf course, and they had paid a higher price for their land for that privilege. The
City of Boynton Beach and PBS&J had to quickly arrange a meeting with the residents
of Arbor Glenn to inform them of the history of the landfill site and to update them
on present construction activities. Obviously, this public relations problem greatly
sensitized the already sensitive issue which the landfill had become over the past
years.
The clearing and grubbing of the site had also uncovered some problems which
effected the design of the closure, to save the City of Boynton Beach the cost
of clearing the landfill prior to the design phase of the project, PBS&J based the
design on boring logs and an aerial topographical map. It was felt that this information
was adequate to determine the depth of cover material and the extent of landfill
mound. Once the landfill was cleared, it was quickly determined that very little
on-site cover material was present and more than the estimated off-site clean fill
would be required brought in to make up the difference. Also, not all the buried
waste was in the mounded areas. It appears that pits had been dug where waste
was placed up to the natural ground elevation.
Changes in design required the contractor to perform more excavation and
backfilling and also stipulated that part of two dry retention areas needed to be
lined. These design changes were coordinated with FDER and SFWMD and approval
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given before the installation of the liner began.
One area of the 40-acre landfill site which exemplifies the past procedures for
disposing of waste, was along the L-20 canal in the very southern portion of the
site. The Lake Worth Drainage District (LWDD) operates and maintains both the
E-3 and L-20 canals which run along side the landfill. The LWDD maintains these
canals through the use of 30-foot wide easements that run along the canals on the
landfill property. Through the clearing of the landfill, it was discovered that waste
was buried within the southern LWDD easement. The most cost effective method
of handling this problem would have been to cover the area with a synthetic liner.
But, the LWDD requested that all waste buried within their easement be removed
and clean fill placed and compacted. The dimension of this excavation was
approximately 1000 feet long by 20 feet wide and ranged from 4 to 6 feet deep.
This problem area alone cost the City of Boynton Beach an estimated quarter million
dollars or an additional twenty-five percent of the original contracted cost.
The last area which required additional earthwork was along the property line
adjacent to Arbor Glenn Estates. Arbor Glenn was platted to allow drainage from
the back of the properties to the road in front. However, the actual construction
of Arbor Glenn allowed the backyards of these adjacent properties to drain onto
the landfill site. To relieve this problem, the City of Boynton Beach and PBS&J
met with the residents and submitted to them for their approval, a design to allow
drainage along a former swale. Ranger Construction regraded the property owners
backyards to produce a swale, seeded and mulched the regraded area and replaced
a small drainage culvert to the L-20 canal at no additional cost to the client or
residents of Arbor Glenn Estates. This cooperative effort between Ranger
Construction, City of Boynton Beach and PBS&J helped many small public relation
problems from developing into time consuming, troublesome headaches.
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LINER INSTALLATION:
Gundle Lining Corporation had developed their new 20-mil VLDPE liner system
in hopes of competing with the 20-mil PVC market. Unlike 20-mil high density
polyethylene (HDPE), 20-mil VLDPE exhibits the flexibility of PVC liner without
PVC's UV sensitivity and bio-degradability problems. This landfill closure was Gundle's
first attempt to install VLDPE in the State of Florida and on a sandy sub-base.
Due to construction schedule, Gundle had the additional misfortune of having to
install the liner system during the very hot Florida summer. Liner installation was
expected to have some problems since Gundle's 20-mil VLDPE was still considered
to be product in the development stage. However, the scope and diversity of the
problems encountered required Gundle Lining Corp., the City of Boynton Beach,
and PBS&J to develop alternative installation and testing procedures to insure a
•
quality synthetic cap. Problems which occurred in the VLDPE placement and their
corresponding solutions are described in the following text:
VLDPE could not be welded using Gundle's double-wedge welding system. Because
of the thickness and heat sensitivity of the VLDPE, any small misalignment of the
liner through the double-wedge system caused a burn through the liner or the failure
of one or both of the weld tracts to meet contract specifications. This problem
was resolved by changing to a single wedge welding system.
The VLDPE also had a limited time span during the day in which it was possible
to be welded. This was because the summer heat caused the liner material to be
so flexible that it increased the potential for burn through. This initially limited
Gundle to early morning and evening welding. Once the single wedge system was
developed and produced the high quality seams required by PBS&J, the City of Boynton
Beach released the contractor from the daylight work only requirement. Gundle
was then able to weld the liner at a faster rate with fewer burn throughs during
the cooler evenings.
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The sand sub-base also created a temporary problem with the welding system.
The VLDPE liner appeared to develop an oily surface when heated by the sun. This
oily surface attracted sand and had a tendency to clog the lower rollers of the Gundle
welding system. In the evening, the liner collected moisture underneath which also
attracted sand. This problem was easily relieved by an extensive cleaning of the
liner by Gundle's personnel and by keeping the liner off the ground with the use of
a skid pad under the seam.
The most critical aspect of the VLDPE installation which required a revaluation
of the liner was the quality assurance testing of the seams. In short, Gundle's VLDPE
could not meet the contract specifications for peel and shear testing using the
standards established for either 20-mil HOPE or 20-mil PVC. It became apparent
that the VLDPE really could not be compared to those standards because it was
an entirely different type of material. At the time, no current ASTM test procedures
or National Sanitation Foundation (NSF) No. 54 test standards existed for VLDPE.
Through the combined efforts of Gundle Lining Corp., Richard Charron of GeoSyntec
(geosynthetic testing laboratories) and PBS&J, new test standards were developed
to adequately determine the seam quality. These standards are listed in the Table
below:
Comparision of Testing Standards 20-mil Liner
20-mil HOPE 20-mil PVC 20-mil VLDPE
Shear Test 36# (Yield) 36.8# (Break) 30# (Break)
Peel Test FTB 10# or FTB 20# or FTB
FTB = Film Tearing Bond
Once the above described problems were resolved, the liner installation ran very
smoothly. After completion of the liner installation, PBS&J felt the VLDPE system
did meet the design and quality assurance requirements for this landfill closure.
A great deal was learned about the properties and installation procedures for VLDPE
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by both Gundle Lining Corporation and PBS&J.
SUMMARY:
The City of Boynton Beach has a closed landfill facility designed for possible end-use
as a golf course. Additional expenditures will be needed by the City to upgrade
the final closure to an official golf course after any settlement occurs in the following
years. This project was brought to its successful conslusion through the fore thought
of the City officials. Unlike many communities, who wished the problems of their
old landfill would go away, the City of Boynton Beach came to realize that a
successful conclusion could be found only by taking the responsibility and working
through all of the problems.
It could be said that the closure of the Boynton Beach Landfill exhibited many
of the same problems in which many municipalities face in dealing with their old
landfills. The City of Boynton Beach took on the responsibility for their landfill
early in attempting to meet the Florida Regulations. In so doing, the City of Boynton
Beach has become one of the few communities in the State of Florida to close their
landfill without the need for FDER to issue a Consent Order requiring its closure.
In addition, each aspect of the hydrogeological assessment and landfill closure took
the public welfare into account. In order to keep public relation problems to a
minimum, the City of Boynton Beach, at all times tried to keep the public informed
of the progress and/or problems associated with the landfill closure. Be assured
that further work at the Boynton Beach Landfill will still need to be done. Continued
groundwater monitoring, general maintenance and repair to any eroded area's will
be required by the City until an undetermined time in the future. But, finally, the
potential risks to human health associated with this old landfill should be coming
to an end.
******
1092a
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PUENTE HILLS ENERGY RECOVERY FROM GAS (PERG) FACILITY
by John Eppich, John Cosulich, and Hsin-Hsin Hsu Wong
Los Angeles County Sanitation District
presented at the
First United States Conference on Municipal Solid Wastes
Solution for the 90's
Sponsored by the
United States Environmental Protection Agency
at
Washington, D.C.
June 13 - 16, 1990
1O93
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Puente Hills Energy Recovery from Gas (PERG) Facility
by John Eppich, John Cosullch, and Hstn-Hsin Hsu Wong
Los Angeles County Sanitation Districts
Abstract
The Puente Hills Energy Recovery from Gas Facility (Facility) utilizes landfill gas as a fuel
and is currently generating 50 MW gross of electricity. The Facility is located at the Puente
Hills Landfill in Whittier, California. The landfill is owned and operated by the Los Angeles
County Sanitation Districts. The Puente Hills Landfill has over 45 million tons in place and
is currently receiving refuse at the rate of 72,000 tons per week. Because of the size and the
extensive gas collection system in place, approximately 24,000 scfm of landfill gas is collected
and burned at the PERG facility and the flaring station. The average heating value of the
landfill gas is 420 BTU/scf.
The Facility, which has been operating since November, 1986, consists of two steam
generators each firing 10,300 scfm of landfill gas. Each unit produces 210,000 Ibs. of steam per
hour at 1350 psig and 1000°F. The steam is used to drive the turbine generator and produce
approximately 50,000 kilowatts of electricity. Several technologies were investigated prior to
selecting the rankine cycle, the most common technology used for power generation in the
United States. The other technologies included reciprocating engines, gas turbines, and
combined cycle gas turbines. The factors involved in the selection were air emissions,
construction costs, ease of operation, and efficiency. A significant factor in the final decision
was the large size of the facility.
Because of the financial and time constraints, the contractor for the Facility was required
to bid a fixed price project based on preliminary design requirements and performance
1094
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specifications which were prepared by the Sanitation Districts. Payment to the contractor
consists of 60 monthly lease payments which commenced 30 days after the project had
completed construction and successfully passed the performance test requirements. In this
manner, the Sanitation Districts was able to make payments for the Facility out of the revenues
derived from the sale of electricity to the nearby utility, Southern California Edison.
The emissions from the Facility had to meet strict requirements from the South Coast Air
Quality Management District. The emissions from the plant are well below those numbers
required by the Air District due to several emission control strategies required of the
equipment as part of the Performance Specifications.
This Facility has successfully demonstrated that landfill gas can be combusted in boilers,
reduce air emissions, and provide significant economic advantages to the owner.
Introduction
The Los Angeles County Sanitation Districts (Districts) own and operate both the Puente
Hills Landfill and the PERG Facility. The Districts are a special purpose organization created
by the California State Legislature for the management of solid wastes and for water pollution
control, and are governed by a Board of Directors consisting of elected representatives of the
cities and unincorporated areas which the Districts serve. The Districts currently manage over
21,000 tons of solid waste per day at four major landfills and process a total of over 500 million
gallons per day of wastewater at 11 major wastewater treatment and water reclamation plants.
The Puente Hills Energy Recovery from Gas (PERG) Facility, a 50 megawatt (gross)
landfill gas to energy facility, commenced operation in November, 1986. PERG is currently
generating its design capacity of 46 MW net. During the first three years of operation, the
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availability of the Facility exceeded 92%. This is to report the operational information on this
Facility including availability, emissions, and landfill gas characteristics and collection. A
schematic of the landfill gas collection system and PERG is shown in Figure 1.
PERG PROCESS SOCMATC
Figure I - Schematic of the Puente Hills Landfill Gas Collection System and the Encr& Recovery from Gas Facility
Puente Hills Landfill
The Puente Hills Landfill, formerly a small private operation, was purchased by the Districts
in 1970. The landfill is a California Class in site, permitted to accept non-hazardous solid
wastes. Currently, 72,000 tons per week is landQlled at Puente Hills. Over 45 million tons
have been placed at the Puente Hills Landfill.
The Puente Hills Landfill consists of 1,365 acres including both the active fill and buffer
areas. The active area of the landfill is approximately 550 acres. The maximum depth of the
landfill is approximately 500 feet
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Landfill Gas Generation
Landfill gas is produced by naturally occurring biological decomposition of the organic
fraction of refuse. The current gas collection rate is approximately 24,000 standard cubic feet
per minute of landfill gas.
When refuse is landfilled, much of the organic fraction of the refuse will be converted to
landfill gas over a period of 10 to 40 years. The rate of conversion depends on many factors
including moisture content, refuse composition, nutrients, buffer capacity, refuse compaction,
and temperature.
The Districts project the landfill gas generation using a first order exponential decay model
with a half life of approximately 20 years. Several other models for landfill gas generation are
also used in the industry. The Districts estimate that approximately two cubic feet of methane
is produced for every pound of refuse landfilled at the Puente Hills landfill.
Anaerobic production of landfill gas is approximately 60-65% methane and 35-40% carbon
dioxide. If oxygen is drawn into the landfill by the gas collection system, aerobic decomposition
of the refuse, or composting will occur. Composting produces carbon dioxide and water and
raises the temperature of the landfill. However, it is necessary to draw limited quantities of
air into the landfill for proper odor control. Accordingly, the landfill gas collection system is
monitored to minimize the amount of composting and to control odors.
Landfill Gas Collection System
An extensive landfill gas collection system has been operated at Puente Hills Landfill since
1981. The gas collection system operation is optimized for odor control, power production is
a secondary goal. The gas collection system consists of two major types of collection systems,
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vertical wells and horizontal trenches and includes over 40 miles of collection and header pipes.
The primary purpose of the gas collection system is to control landfill gas and thus prevent
odors and sub-surface migration.
Over 400 wells have been drilled in the front face of the landfill for odor control. The
wells are monitored on a biweekly basis for temperature and methane content A throttling
valve on each well is used to control the tested parameters. A slight closure in the throttling
valve results in decreasing the temperature and the oxygen, and increasing the methane content.
A typical well detail is shown in Figure 2.
The trench system is constructed directly in the refuse on the operating deck of the landfill.
The trenches are installed in four decks of the landfill with collection pipes approximately 260
feet apart. A new trench system is installed on the top of the landfill approximately 60 feet
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in elevation. The trench system installed to date consists of over 18 miles of landfill gas piping.
A typical trench detail is shown in Figure 3.
12V CORRUGATED-7
STEEL PIPE /
A rr — » _^, f
>_LL. ; " ^ ^—~
L_j :
2-0' 2'-o"
LAP
LAP
i i
J
10 • O
Y"1- — ~~*~J
IKbNgH i
WIDTH
LANDFILL
GAS
f$£~ n •«
nr^r, J ««
T ir^ i
^—15"* CORRUGATED
STEEL PIPE
Figure 3 - Landfill Gas Trench Detail
Landfill gas delivered to the PERG Facility is approximately 42% methane, 35% CO2, 3%
Oz, 15% N* and 5% H20 (all by volume). The landfill gas is normally at 100% relative
humidity or saturated when it comes out of the landfill. Accordingly, condensate traps are
located at all low points in the gas collection system.
The overall gas collection system at the Puente Hills Landfill is designed in a "loop" around
the perimeter of the landfill. This allows the remainder of the collection system to be
operational when part of the system is out of service for maintenance.
The entire landfill gas collection system is under a vacuum to insure odorous gases do not
escape in case of leaks in the piping. Occasionally, expansion joints or other components of
the landfill gas system will fail. The most common cause of failures is differential settlement.
The heating value of the landfill gas is monitored continuously by a calorimeter. Sharp
decreases in methane content of the landfill gas generally indicate a breakage in the collection
piping.
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Technology Selection
Several technologies to convert the landfill gas to electricity were investigated by the
Districts. These technologies include reciprocating engines, gas turbines (simple and combined
cycle), and the rankine cycle. The study concluded that the most common technology used for
electrical power generation in the United States, the rankine cycle was best suited for the
Puente Hills Landfill The selection criteria included energy conversion efficiency, air emissions
ease of operation, and construction cost as shown in Table 1.
RECIPROCATING GAS COMBINED
CRITERIA ENGINES TURBINE CYCLE
AIR EMISSIONS 1 3 3
NET POWER 4 35
EASE OF
OPERATION 2 32
B TU CONTENT 2 44
CONSTRUCTION
COST 3 43
TOTAL POINTS 12 17 17
STEAM
TURBINE
5
4
3
5
4
21
Table I Selection Criteria Used to Evaluate Alumaave Landfill Gas to Entry
Technologies for a SO MW Project
The rankine cycle's gas fired boiler with multiple control strategies, offered the ability to
achieve very low air emissions, lower than any other of the technologies. Reciprocating engines
had the highest emissions.
The combined cycle offered the highest net power, but at increased complexity and cost,
1100
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which outweighed the value of the added power.
The "BTU Content" criteria included the ability to effectively operate on a low BTU
content fuel which is subject to sudden variations. The landfill is constantly settling.
Differential settlement often results in line separations and sudden decreases in BTU content.
Two gas turbines are also currently operating at Puente Hills Landfill: a Solar Centaur
(2650 kw) and a NATCO KG-2 (1250 kw). These gas turbines have been operated
intermittently since 1983 when landGll gas is available. The gas turbines have operated
successfully. The Districts consider gas turbines a viable technology for smaller landfills.
PERG Specifications
In order to assure a competitive bid and quality construction, the Districts prepared detailed
Performance Specifications for bid to pre-qualified engineering contractors. The Performance
Specifications included detailed specifications on major equipment and general construction
specifications. Also, included in the Performance Specifications were the design, redundancy,
and access requirements for all major equipment and systems. An equipment summary is
provided in Appendix 1.
Bids were evaluated by calculating the net present worth of the 60 monthly payments and
the residual value purchase to the bid opening using 1% per month discount rate. Net power
from the Facility was included as an evaluated credit of $2,500 per kilowatt to encourage
energy efficient designs. However, the Performance Specifications included limitations on the
cycle complexity for ease of operation and reliability, and several mandatory emission control
methods to achieve the stringent air emission limitations.
The Performance Specifications included redundancy requirements on most rotating
1101
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equipment for reliability. The only mechanical equipment without redundancy are the boilers
and steam turbine.
The successful bid by Schneider, Inc. included a steam turbine by Fuji Electric. The steam
turbine heat rate is 8,545 BTU/kwhr (9.01 MJ/kwhr). The boiler efficiency is over 83% based
on the higher heating value of the landfill gas. The parasitic load of the plant is approximately
8% of gross. The overall Facility's net heat rate based on the higher heating value is
approximately 11,000 BTU/kwhr (11.6 MJTkwhr).
Performance requirements included ASME performance test codes for steam turbines,
boilers, and deaerator. The turnkey contractor was also required to demonstrate that the boiler
could achieve the stringent limitations imposed on the project by the local air quality
management district. Another requirements was to demonstrate the Facility could be operated
reliably, which consisted of an 85% availability requirement for a 30 day period before the
Districts accepted the Facility.
Project Schedule
A primary concern was to implement a project as quickly as possible to utilize the landfill
gas. Project implementation, from conceptual design to commercial operation was accomplished
in less than three years. Conceptual design was started in early 1984. Applications for air
permits were filed in May, 1984 and final permits were received in April, 1985. The contract
was awarded to the turnkey contractor in March, 1985. Commercial operation was achieved
in November, 1986.
The turnkey method of procurement was selected since it offered considerable time savings
over other procurement methods. The turnkey contractor was required to design and construct
1102
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the Facility in 16 months. This tight schedule mandated a substantial overlap of the design and
construction phases of the work.
Air Emissions
Air emissions are a critical issue in Los Angeles County. From a regulatory standpoint the
South Coast Air Quality Management District (SCAQMD), requires that all landfill gas be
collected and flared. When the permit was filed, the emissions from the flares provided the
baseline emissions level
The Performance Specifications included several requirements to assure the stringent
emission levels could be achieved, including derating the boilers, flue gas recirculation, low" NO,
burners, limiting the air preheat, and provisions for Thermal DeNO, (a proprietary Exxon
process). However, tests on Thermal DeNO, demonstrated Thermal DeNO, did not effectively
reduce NO, at the" low inlet NO, levels. Subsequently, the ammonia injection piping was
removed. The air pollution control and NO, reduction methods are shown in Figure 4.
DERATED BOLER
LOW
NTENSITY
FLAME
CONVECTION
SECTION
AIR
PREHEATER
STACK
ECONOMIZER
THERMAL OiNOx
LFG
FLUE GAS RECIRCULATION
PERG NOX CONTROL
Figure 4 - Schematic of the PERG Boiler NO, Reduction Methods
The boiler burners are low NO, burners supplied by Coen. The burners, are the dual air
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zone type (Coen Model Number DAZ 42), with adjustable inner and outer scrolls which may
be controlled to adjust the flame shape turbulence. The scrolls direct the gases in opposite
rotating directions. Increasing the opposing spin increase turbulence and results in a shorter
more turbulent flame.
The NOX control strategies including the low NO, burners, oversized boilers, and flue gas
recirculation have resulted in very low emissions of less than 24 ppmv NO, (3% O:, dry) or
approximately 0.03 lbs/10* BTU. Flue gas recirculation has proven to be an effective method
of reducing NO, emissions by approximately 60%.
A comparison of the PERG boiler emissions to the flare emissions is given in Figure 5.
This Ggure shows the boilers provide substantially lower NOD HC, and CO emissions.
TOO
600
500
400
2 300
200
100
2222
NOx CO
I 1 FLARES £2 BOILERS
HC
Figure 5 - Emission Comparison between the Flares and Boilers at the Puente Hills Landfill
11O4
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Using Landfill Gas as a Fuel
The operations problems at PERG have for the most part been the result of failures with
equipment common with a natural gas fired power plant The availability to date has been
92% for the first three years of operation.
Any operational problems which could be attributed to landfill gas may be caused by the
moisture, or by the chlorine and sulfur compounds in the landfill gas, or by the variability in
the landfill gas quality. The landfill gas is essentially saturated when it is collected from the
landfill.
Landfill gas is a relatively clean fuel. The landfill gas from the Puente Hills landfill
contains 30 to 80 ppmv each of chlorinated and sulfur compounds. This compares favorably
with coal which may contain between 100 and 1,000 times more sulfur and chlorine.
The landfill gas collection at the Puente Hills Landfill includes more than 40 miles of
collection and header piping. The piping, being located in a landfill is subject to both
differential settlement and vehicle damage. Differential settlement within the landfill is the
most prevalent cause of failure. Differential settlement causes failures by over stressing flexible
joints in the landfill gas piping. Periodic inspection of the landfill piping has limited major
failures caused by differential settlement.
Normally there is a slight diurnal variation in the landfill gas with the landfill gas quality
causing the BTU content to be lower at night. This may be the result of thermal expansion
of the PVC collection piping during the day resulting in lower air infiltration into the above
ground piping. The air infiltration may occur at cracks in the flexible joints.
The problem that arises from the power plant standpoint is the variability in the BTU
1105
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content of the landfill gas. Normally the Puente Hills landfill gas varies from 410 to 440
BTU/scf. However, in the case of a piping failure, the BTU content may drop to below 200
BTU/scf. This may result in flame stability problems in the boiler.
Flame stability in the boilers is a potential problem, especially using a high flue gas
recirculation rate. The pilot flame for startup is fueled by propane. Prior to successfully
completing lightoff on landfill gas, the minimum fire settings had to increase in terms of firing
rate and excess air had to be decreased. This is due to the nature of the landfill gas fuel.
Since landfill gas has less than half the BTU content of natural gas, the flame burns cooler.
This results in occasional burner safety management trips when the flame scanner (Fireye) fails
to sense the flame.
The chlorine and sulfur in the landfill gas make the gas and its condensate corrosive. Since
the landfill gas is saturated and the ambient temperature is below the dewpoint of the landfill
gas, moisture condenses along the pipe walls. This condensation, or condensate has a pH
between 2 and 3. Carbon steel corrodes quickly at this pH. Accordingly, the Districts use 304
stainless steel for both landfill gas and condensate piping.
Landfill gas is generally low in particulate matter. However, when new collection piping
is placed in service or in upset conditions a large amount of particulate matter or moisture can
be passed through the landfill gas piping. Witch hat strainers are located at the inlet of the
landfill gas blowers to protect the blowers from particulate matter. A knockout drum protects
the blowers from slugs of water.
Occasionally a condensate trap which normally removes the condensate from low points in
the landfill gas collection system fails. This results in the partial or complete plugging of the
1106
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associated piping until the water condensate is removed. Partial plugging of the landfill gas
pipe in the collection system is detected at the energy station by oscillating landfill gas
pressures. When all the condensate traps are functioning properly, the landfill gas pressure is
very stable.
Availability
A summary of factors affecting availability during the first three years of operation is given
in Table 2. The most trouble prone pieces of equipment during the first three years of
operation were boilers. The largest factor was the forced draft fan motors which both failed
during rainstorms. Enclosures around the motors have precluded subsequent failures. The
other factors which significantly affected boiler availability were: a faulty electronics board in
the burner management system; binding of the forced draft fan dampers; bearing failures at the
air preheater rotor (hot end) and the forced draft fan; and the flue gas recirculation fan related
problems. A boiler feed pump suction bypass from the fifth heater feedwater line was installed
to reduce the NPSH transient due to a sudden load decrease. The original forced draft fan
damper was replaced with an external greased ball bearing inlet vane damper.
Item Number of Outages Total Downtime (hrs")
Boiler 67 768
Steam Turbine 6 35
Landfill Gas System 10 59
Electrical 12 135
Instrumentation 13 83
Utilities 17 118
Other Mechanical Equipment 5 23
Annual Maintenance Outage 3 1,051
Total 133 2,272
Table 2 - PERG Outage Summary for 1987, 1988, and 1989
11O7
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The Fuji steam turbine proved to be a reliable piece of equipment during the first three
years of operation. However, during the scheduled warranty inspection at the end of the three
year warranty period, the following items were discovered and repaired:
1. Erosion/corrosion noted at the trailing edge of the 33rd stage of stationary blades.
2. Severe seal fin damages (both moving and stationary blades).
3. Erosion/corrosion noted at the stationary blade seal fin bases at 31st and 32nd stage.
The scheduled maintenance outage was extended for these unexpected repairs by
approximately three weeks.
The landfill gas collection system caused 10 outages in the first three years of operation.
Five outages were the result of sharp drops in the landfill gas methane content. There were
two scheduled outages for landfill gas piping modifications. Two outages were caused by
landfill gas blower failures. One outage was caused by air preheater fouling which required
water washing due to an excessive pressure drop. The deposits were analyzed and determined
to be silica, iron, chlorine, and sulfur in descending order of concentration.
There were 12 electrical failures in the first three years of operation. Three electrical
failures were in the uninterruptible power supply system. Three main breaker trips resulted
from electrical fault in the circulating water pump motor. Three outages were resulted from
trips in the 4160 volts transformer. Three scheduled outages totaling 70 hours were resulted
from correcting the overheating in the Southern California Edison metering (12KV) cubicle.
Seven instrumentation trips occurred due primarily to faulty vibration signals. Subsequently,
the vibration switches were changes to alarms rather than trip. Six outages resulted from faulty
instrumentation signals. Water leaks through connecting conduit to one of the outdoor process
11O8
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control unit cabinets resulted in 24 hours of down time.
Two different utility power sources are required for the operation of PERG. One
electrical service provides the electric power for the landfill gas collection blowers and the
water booster station. The other electrical service provides both the generated and parasitic
power for PERG. Seventeen outages resulted from interruptions in service or disturbances
resulting in the opening of the main breaker by protective relays for a total of 118 hours of
downtime.
Outages due to other mechanical equipment such as pumps and compressors were limited
to 23 hours due to redundancies and automatic standby controls.
Annual maintenances were typically scheduled in May approximately one month before the
four summer months when power sold at a higher rate.
Economics
The project capital costs, including design, construction, and interest during construction
was approximately $33,000,000 for the entire Facility. On a unit cost basis this is equivalent
to $650 per kilowatt of installed capacity. The District structured the project financing to allow
the electrical revenues from the project to pay for the project capital costs.
Project revenues are derived from the sale of electricity to Southern California Edison.
The gross revenues were $90,688,900 for the first three years of operation in accordance with
the power purchase agreement with Southern California Edison. Each of the 60 monthly lease
payments is $726,000, and the average routine monthly operations and maintenance expenses
were $319,000. The cost for the FGR fan modification and a major turbine and boiler
overhaul was $1,200,000.
1109
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Operating Costs
The operating costs for PERG were estimated at $300,000 per month. The average
operating costs for the first three years of operation was $319,000 per month. A breakdown
of the operating expenses is provided in Table 3.
Expenses $/Month
Payroll
Materials
Chemicals
Water
Electricity
Services
Insurance
Other
Total
138,000
49,000
13,000
16,000
35,000
20,000
18,000
30.000
319,000
Table 3 - PERG Operating Expenses
Conclusion
The PERG Facility demonstrates that a large scale landfill gas to energy facility can
combust landfill gas (a waste product), reduce air emissions, and provide significant economic
benefits.
1110
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Appendix 1
PERG FACT SHEET
Owner and Operator
Turnkey Contractor
Engineer (Detailed Design)
Boilers
Number
Manufacturer
Steam Capacity (each), Ibs/hr (kg/hr)
Steam Pressure, PSIG (MPa)
Steam Temperature, °F (°C)
Configuration
Erection
Burners
Air Preheater (Ljungstrom type)
Stack Gas Temperature, °F (°C)
Efficiency (as bid)
Steam Turbine/Generator
Manufacturer
Capacity
Blading
Number of Stages
Extractions
Condensing Pressure, 'Hg'(kPa)
Heat Rate (as bid)
Condenser
Manufacturer
Surface Area, ft2(m2)
Feedwater Heaters
Manufacturer
Stages
Cooling Tower
Manufacturer
Heat Rejection, 10'BTU/hr (MJ/hr)
Superstructure
Fill Material
Fans
Control System
Supplier
Type
Model
Los Angeles County
Sanitation Districts
Schneider, Inc.
Energy Systems Associates
2
Zurn
264,000 (120,000)
1350 (9.4)
1000 (538)
XT Type
Field
Coen
Combustion Engineering
260 (127)
83%
Fuji
50,000 kw
Reaction
35
6
2 (6.8)
8545 BTU/kwhr
(9.01 MJykwhr)
Graham
38,000 (3532)
Struther-Wells
5
BAC-Pritchard
272 (286)
Concrete
PVC
150 hp, 2 speed
Bailey Control
Distributed
Network 90
mi
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STABILIZED FOAM AS LANDFILL DAILY COVER
A.J. Gasper
3M Company
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
Abstract
This paper is concerned with the use of stabilized foam to provide
daily cover in sanitary waste landfills. The paper will discuss the
problems faced by landfill operators in using soil and other materials
as daily cover and the inherent advantages and needs associated with
the use of stabilized foam. In addition the paper will discuss the
experiences of 3M as a material and equipment supplier of stabilized
foam synthetic daily cover. The paper will highlight the equipment
and foam technology used to produce the the foam cover and also the
experiences of 3M and its customers in getting the product approved
for use in various localities. The paper will discuss the facilities
required on the site to use the product efficiently and also some of the
training and service provided to landfill operators to take advantage
of this technology.
1113
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3M-WMA Presentation text (ref. slides)
I. Introduction
A. Problem Statement
The generation of waste in the U.S. is accelerating and the available
technologies to deal with the problem are limited. In particular,
landfills have been the traditional approach to disposing of
municipal waste but they are filling up at an alarming rate and the
siting of new landfills is very difficult There has been a decrease of
about 8000 permitted landfills from 1987 to 1990 in the United
States. One of the factors leading to the limited life of existing
landfills is the use of soil as daily cover material. When soil is used
as daily cover there are several associated problems:
1 - Soil consumes valuable air space.
2 - The availability of soil to a local site may be poor
and if that is the case, soil cover may be costly.
3 - Application of soil cover is quite labor intensive
and can be susceptible to adverse weather
conditions.
4 - Soil may cause unwanted lateral movement of
leachate and gas.
B. Need:
Performance criteria for daily coven
1 - Control litter
2 - Control odors on the workface
3- Control Vectors
4 - Provide a fire barrier against hot loads,
spontaneous combustion and surface
ignition
5 - Provide a disincentive to scavenging and
1114
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other undesired activity on the landfill
6 - Provide a barrier to excessive water
infiltration which could create excessive
leachate.
7 - Provide a degree of acceptible esthetics for
the landfill relative to neighbors and
passersby.
C. Non - Soil Alternative Daily Cover material:
There have been a variety of materials which have
been used as alternative daily cover material to soil.
Generally all have had deficiencies.
Flyash, incinerator ash and bottom ash have been
tried in some locals as daily cover material. These all are
considered unacceptable from the standpoint of heavy metal
content and dust problems.
Industrial and municipal waste streams such as
waste water sludge, paper sludge, tire chips, foundry sand,
wood chips and shredder fluff have all been used occasionally
as daily cover material. Contamination of by heavy metals,
PCBs together with materials which cause bad air emissions
are generally associated with materials of this type. An
additional problem with sludges is that they can inhibit the
maneuverability of landfill equipment.
-------
There have been several attempts at using geotextiles as daily
cover material. Although they appear to satisfy some of the
basic criteria for cover such as litter control and esthetics, the
geotextiles in use suffer from several important aspects
relative to daily cover requirements. They can be very
difficult to install especially in windy conditions and
inclement weather. They are porous to rain and therefore can
create significant problems with leachate. The geotextiles are
flammable and if they are reused they can cause problems
with air emissions and exposure of workers to refuse
residues.
D. Solution:
An excellent approach has been to use stabilized foams which
are designed as daily cover material. These materials are
engineered to meet the basic performance requirements of
daily cover in conserving valuable air space while providing
increased revenue to the landfill operator.
Two such materials sold by the 3M Company will be
discussed further.
II. Description of foam materials
3M produces two types of foam materials for use as synthetic daily cover
(SDC) on municipal landfills. The materials are: 3M Foamat™ SDC and
3M SaniFoam™ SDC. Each type of foam can substitute for soil cover in
daily applications. In both cases, foam is produced by combining water, air,
an aqueous surfactant solution and a stabilizing resin. This combination of
materials exits from a spray nozzle to give the desired foam material on
the landfill surface. Equipment has been developed to apply the materials
in an efficient and effective manner through either pull-behind spray bar
1116
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units or hand-held spray devices.
While both foam systems are effective replacements for soil as daily cover,
they are based on different polymeric resin systems and have different
physical appearance. They also require different equipment and handling
procedures. We will describe the systems one at a time.
3M Foamat SDC ~ There are two components (in addition to water and
air) which make up this system. FC-9400 polyurethane resin and FC-9401,
the surfactant/catalyst solution. This system has been designed for use with
the Foamat foam Cart. The resin is provided in a closed-head 55 gal drum
and material is pumped directly from the container. The FC-9401 is
provided as a concentrate in closed-head 5 gal. pails and is diluted with
water for use.
The gellation rate of the foam is controlled by the concentration of foamer
used. The recommended range of foamer solution per hundred gallons of
water may range from 10 to 16 gal. depending on such things as
temperature and water hardness. FC-9400 will react with ambient
moisture on prolonged exposure, but has greater than 1 year shelf-life
when stored in its original container in relatively dry conditions at
temperatures less than 100°F.
The FC-9401 foamer is a concentrated solution of the active ingredients in
water. When the Foamat™ system is used/ the foam is dispensed from
each of the six nozzles at a rate of 10 gal/min. The foam expansion is
typically 20-25. The six nozzles will give a spray width of 12-15 ft and when
the cart is pulled over the workface at 1.0 to 1.5 ft/sec., the foam depth is
about 3-4 inches. This foam depth is adequate to cover moderate to well-
compacted refuse.
1117
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Environmental Information:
Extensive environmental testing has been done to review the potential
impact of the foam products on the landfill and surrounding environment
as well as to monitor the effectiveness of the product for its intended use.
Leachate testing has shown that very little material leaches from cured
foam and that which does has no adverse environmental impact. Animal
testing has also shown the material to be non-hazardous. The results of
this testing are available to interested persons. With regard to product
utility, tests have shown the product to be effective in controlling litter,
odors and vectors. Other tests have shown that the material provides
protection against the infiltration of rainwater into the refuse and that this
synthetic daily cover is non-flammable and does not add to the inherent
fire hazard of the landfill. These are very important considerations when
using a daily cover material. Again, specific information on methods and
results can be made available.
The Foamat™ Cart is designed to be towed with normal landfill
equipment such as a D-6 to D-8 Caterpillar. In daily operation, the unit is
filled and prepped in the morning and foaming is done in the afternoon.
Experience has shown that a properly maintained cart requires about 1-2
hrsVday for filling, cleaning and general maintenance. The equipment has
several built-in features for ease of use. These include a drum hoist to
change barrels of FC-9400, an hydraulic jack to aid in moving and handling
the cart and a bottom-fill system to mix in FC-9401. Foaming and flushing
are controlled by the driver of the tow vehicle and in many cases the
operation involves only one person. Experience has shown that it takes
about 20-30 min. to cover a workface of 15,000 sq.ft. This is normally
quicker than it would take to cover a similar area with soil at the end of
each workday .The foam cover does not require removal the next morning
and compacts under the next day's waste, thus saving valuable landfill air
space.
-------
The major difference between Foamat™ and SaniFoam™ SDC from the
standpoint of the user tends to be esthetics. The Foamat® material forms a
dense transparent membrane as the water in the foam evaporates.
Although this membrane continues to function effectively as daily cover,
some landfill operators and inspectors prefer a higher level of opacity of
the foam cover. For those operators the SaniFoam™ SDC is the preferred
product
The following information describes the 3M SaniFoam™ SDC system
including materials and equipment There are many similarities between
the foam systems particularly hi terms of their use. The major differences
are related to the type of polymeric resin employed to produce the foam
and also some differences in the type of equipment used to apply the foam.
The main components of the SaniFoam™ SDC system are FC-4200 resin
and the FC-4201 foamer solution.
FC-4200 is a solution of a urea-formaldehyde prepolymer. This material is a
very low viscosity/ water-soluble resin which when combined with FC-4201
forms a highly crosslinked matrix which provides the foam stabilization.
FC-4200 is supplied normally in 55 gal. closed head drums which is
pumped from the drum into the resin tank on the application equipment
without dilution. At large user sites, the FC-4200 is supplied and stored in
bulk containers. The resin is pumped directly from the storage container
into the foam trailer. The FC-4200 has a shelf life of approximately 90 days.
FC-4201 is a foamer solution for FC-4200. This material generates the foam
structure and is acidic and catalyzes the FC-4200 crosslinking process. The
FC-4201 is normally supplied in 55 gal drums and is diluted at the rate of
twenty to one one with water in the foamer tank.
A "drum set" which is one drum of resin and 2.5 gal of foamer will cover
1119
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about 2000 sq.ft. with 1-2 inches of foam. The strength and opacity of the
SaniFoam™ SDC system provides for very effective cover.
Many tests have been done to verify the environmental compatibility of
the SaniFoam system. Levels of free formaldehyde, are extremely low in
the cured resin solution and the foam. The extraction tests show that there
is almost no detectable level of any of the SaniFoam resin components
present in the leachate. The foamer material which is a special surfactant
is very biodegradable and compatible with the landfill environment. Tests
for system efficacy have shown that the SaniFoam blanket provides
excellent protection as daily cover on the landfill. As the material dries, it
maintains its original appearance and this feature is desired by many of the
landfill operators. Details of the test methods and results on this product to
determine environmental suitability can be made available to interested
parties.
There is a wide choice of equipment available to users of the 3M
SaniFoam™ SDC system. The equipment ranges from relatively small and
portable handline units to large, pull-behind spray bar trailers for high-
volume landfills. All of the units work on the same principle to produce
stabilized foam. The aqueous FC-4201 foamer solution is pumped or forced
by compressed air through a bead chamber where it is combined with air to
produce foam. The foam is then delivered to the nozzle where it is mixed
with the stabilizing resin before ejection to the surface. The material begins
to cure to produce the stabilized foam immediately and its stabilization is
normally complete within 10 min. The stabilized foam is a fluffy white
material which is flexible and has good adhesion to all surfaces on the
landfill including vertical surfaces. In a typical landfill application when a
pull behind unit is used, touchup is done if necessary by using a hand line
available on all SaniFoam™ SDC equipment. Many users find it
advantageous to use the hand line simultaneously with the spray bar. All
application units have a hot water flush system to clean the nozzles after
1120
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use. They also have enclosures for the resin and foamer tanks in order to
allow use of the equipment in cold weather. 3M provides technical service
assistance to users of all equipment from startup through normal
application.
III. Regulatory concerns:
The use of foam for daily cover falls under the jurisdiction of
regulatory agencies at the state and local level. The specific
regulations differ from locality to locality. Normally, approval to
evaluate and/or use foam as synthetic daily cover comes only after
negotiations with several agencies. Typically, the local agencies have
required a testing period hi order to evaluate the product for
efficacy and environmental impact and equivalency to soil in
meeting the performance criteria.
It is extremely important that regulatory agencies be apprised by the
suppliers of the daily cover alternate products about the benefits
and disadvantages of their cover material relative to traditional
soil. This is true because there are occasions where landfill
economics and operational practices might compel an operator to
use an inappropriate material such as a fabric or sludge simply
because there is a perception that the workface is covered adequately
with little thought given to the long range engineering
implications such as impact on leachate quality and quantity and air
emissions upon removal together with the inherent fire hazards on
the landfill.
Reputable providers of cover material should have the same
concerns that are expressed by regulators.
Regulators should expect that providers of alternative cover
materials have the type of documentation that indicates the efficacy
of the product to meet or exceed the requirements of daily cover for
-------
landfills while having overall environmental acceptance for
landfill use.
IV. Landfill Requirements
The landfill is required to have certain facilities in order to
effectively use the stabilized foam systems. Normally a landfill will
already have these facilities in place. Occasionally, a landfill is
required to invest in additional facilities. The major requirements
are:
— Adequate water supply to fill the unit efficiently— about
10 gpm minimum
— Inside storage of foam materials and equipment in cold
weather to prevent freezing.
— An area suitable for daily preparation and routine
maintenance of the unit.
As indicated, 3M provides all training ,materials and service to assure high
quality, dependable daily cover for the applicator.
V. Actual landfill experience
The use of stabilized foam as alternative daily cover has been
studied and approved on landfills both in this country and in
Europe. Several slides demonstrating the use of the stabilized foam
materials will be shown at the time this paper is presented.
In the majority of cases, evaluation of the installation and
performance of the stabilized foam cover was done by an
independent consulting engineering firm. Their reports will be
highlighted in this section of the presentation.
1122
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A STUDY OH LEACHATE TREATMENT BY MEANS OF FENTON METHOD
Sue-Huai Gau, Ph.D.
Associate Professor
Department of Civil Engineering
Taakang University
Taipei, Taiwan. R.O.C.
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13-16, 1990
1123
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A STUDY ON LEACHATE TREATMENT BY MEANS OF FENTDN METHOD
ABSTRACT
During the sanitary landfill period, the COD value of
leachate can usually exceed 10,000 or 20,000 »g/l. After
aerobic or anaerobic biological treatment, however, the
residual COD is still up to thousands and the effluent remains
dark brown. In convention, COD and color are removed by
chemical coagulation followed by carbon adsorption. But, even
if a huge coagulant dosage is used, the COD removal efficiency
is very low and there will be a lot of sludge to be handled.
The Fenton method, a chemical oxidation," applies hydrogen
peroxide as an oxidizing agent whose reaction is accelerated by
ferrous sulfate. It has been proved that the Fenton method can
break some recalcitrant organics effectively. This method is
thus employed to treat the leachate after the activated sludge
treatment, in order to find out the proper chemical dosage and
operation conditions.
The results are: (1) It achieves lower COD and clearer
supernatant than the coagulation method does. (2) The best
ratio of H.Ot to FeSO is between 0.5 and 0.8. (3) To reach 70X
COD removal efficiency (the final COD value 400-500 mg/1), it
needs 0.3-0.5 g H.Ot/g COD removed, and the more HtOt dosage is
added, the better COD can be removed. (4) The proper final pH
is between 3 and 4.
1124
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1. Introduction
Nowadays the landfill of a considerably large quantity of
refuse entails problems of leachate. Generally, biological
treatment is utilized to lower the concentration of organics in
refuse leachate. But the ability of biological treatment is
limited, especially when confronted with the low biodegradable
organics. After the phase of biological treatment, it is thus
necessary to proceed to chemical coagulation in addition to the
operation of filtration and/or adsorption, so that the treated
water quality may reach the effluent standards. However,
chemical coagulation is not good enough for dissolved COD
removal: it will produce a great deal of chemical sludge to be
handled.tlj This study employs the Fenton method to solve the
problems of refuse leachate that has undergone activated sludge
treatment, such as the low biodegradable organics which caused
high COD and color.
The Fenton method, a chemical oxidation, uses hydrogen
peroxide as an oxidizing agent whose reaction is accelereated
by Fe**. In 1860, Schonbein found that the oxidation of iodide
ion by means of hydrogen peroxide is markedly accelerated by
iron salts. And. in 1894, Fenton discovered that a mixture of
a ferrous salt and hydrogen peroxide could oxidize many
hydroxylic organic compounds, and that the mixture possessed
potent oxidizing properties not present in the separate
reagents.1"1 Hereafter the Fenton method has been explored on
and off.
1125
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2. Background
Hydrogen peroxide was found by Thenard in 1818 and
Manufactured for industry at the end of the nineteenth century.
During World War II, because it became the liquid fuel to
promote equipment, its production was rapidly increased. The
•elting point of hydrogen peroxide is at -0.41"C, liquid at
normal temperature, and its boiling-point at 150.2"C . At 25 "C ,
it becomes viscous liquid with density of 1.4425 g/ml, and can
be mixed up with water. On the market, its mixing rate is from
3X to 90X, weak acid, and the specific conductivity is 5xlO~T
ohm"tcm"1. The reaction of hydrogen peroxide itself is very
slow. To accelerate the ability of hydrogen peroxide, it needs
metal ions such as Fe. Cu. V. Cr and Hn, or materials with
rough surface such as zeolite and activated carbon, high pH and
radiation ( short-wave ultraviolet rays ). t33 The common
oxidizing agents used for chemical treatment of refuse leachate
include ozone, chlorine, hypoch1 orite, hydrogen peroxide, and
so on. The installation of ozone costs much and cannot remove
COD in an efficient way. Both chlorine and hypochlorite have
weak oxidation and may bring forth halogenated compounds.
By contrast, hydrogen peroxide is cheaper, safe. and without
bad consequences. When combined with Fe2*, the oxidation
of hydrogen peroxide will be strengthened. Some experiments
have indicated that the Fenton method is effective on
the decomposition of ABS, phenol, etc.143 Besides, in Japan
1126
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the study of various organic compounds applies the Fenton
method under the following conditions:
H.O./COD = 1.0. H.O./FeSO* = 5.0 dole rate), PH = 4, and one
hour's reacting time. COD removal efficiency for alcohols,
acids, aldehydes, and ketones are 30-40X, 30-50*. 30-50*. and
10-40*. respectively. As for dicarboxylic acid, COD removal is
around 60*, for some unsaturated compounds up to 90*. and for
the decomposition of aromatic compounds is from 70% to 90*.£83
Some documents have proved that through the Fenton method TOC
removal can be more than 75* for low biodegradable organics,
such as Urea resin, dibromsa 1 ici 1, POENPE (n = 15).t63 Further,
Takashi Korenaga employs the Fenton method to treat the
photographic wastewater, whose COD removal is decreased from
62.300 mg/1 to 291 mg/1 and treatment efficiency is as high as
99.5*.tT:i
The mechanism of the Fenton method is as follows:1"1
Fe"* + H.Oa -» (FeOH)"* + -OH -» Fea* * -OH + OH' (1)
•OH + Fe"* -> (FeOH)"* -» Fe3* + OH" (2)
•OH + H.O, -> H.O * -O.H (3)
•O.H <- -> -Of' + H* (4)
•0»- + H.Oa -> 0. + -OH * OH' (5)
Fe3* * H.Oa -» Fe"* + -O.H * H* <8)
Fe3* * -0." -» Fe8* + 0. (7)
( i ) When H.O. < 1Q-*H and the initial concentration of
Fe" is low, the main reaction formulas are (1) and (2).
1J27
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(ii ) Vith the increasing proportion of H«0« to Fe1*, -OH
radical will strengthen its competence to lay aside Fonula
(2). It results in -0«H radical, that is, the reaction of (4),
(5) and (7).
•Q.H -> -Ot- * H* (4)
•0.- * H.Oa -» 0, + -OH + OH' (5)
Fe" + -0.- -» Fe1* + 0. (7)
The above reaction will release Oxygen to increase the
dissolved oxygen in vastevater.
(iii) Vhen the organic lonoiers exist.
•OH * CHt= CHX -> HO-CH.-CHX --- polyiers
or -OH + RH -» H.O * R-
R- * CH.=CHX -> R-CH.-CHX
R-CH.-CHX * CH.=CHX -> R-CH.-CHX-CH,.CHX --- polyaers
the polyierization occurs.
(iv ) Vhen there exist the organics, the reaction is as
the following:
H»A * -OH -» HA- + H.O
HA- * Fe" -» HA' + Fe"
HA* * OH' -> HAOH (priiary product)
HAOH * -OH -> HOA- * HiO
HOA- * Fe" -» Fe" * H* * AO (secondary product)
( v ) When oxygen exists, the reaction of the organics is
as follows:
1128
-------
H,A + -OH_-» HA- + H,0
HA- + 0, -» HAD.
HAD, * Fe"* + H* -> HAO.H + Fe3*
HAD, + H.A -> HAO»H + HA•
HAO.H + Fe»* -» HOA- + Fe3* + OH'
HOA- * H.A -> HAOH + HA •
HOA- + H* + Fea+ -» HAOH + Fe3*
In the reaction process, the free radicals of -OH
consisting of unpaired electrons are full of activating and
oxidizing ability. The oxidation is even stronger than that of
ozone, and can decompose high aolecualr weight organics into
low aolecules. Thus, as has been confirmed, after applying the
Fenton nethod, BOD is increased and the proportion of BOD to
COD raises.£'3 Such a deconposition can reiove the color and
COD of the low biodegradable organics. Besides the free
radicals of -OH and -O.H, Fe'* is oxidized into Fe3* and
Fe(OH)**, which results in coagulation and, plus the organic
•onoiers. polymerization. To sum up, the Fenton method retains
the double effect of oxidation and coagulation.
Judging from the above functioning structure, in the
reaction process the Fenton method will not produce troublesome
matters. Vith the adding of reagents, this method does not
increase the total solids and chemical sludge, while chemical
coagulants Ala(S04.)s and Ca(OH)« do. Neither does it encounter
such problems as the hardness of Ca(OH)a may augment and the
1129
-------
chloride of FeCls increases.c*a According to these contrasts,
the Fenton method can avoid producing troublesome Matters in
effluent. Though the adding of Fea* can increase the amount
of iron ion in the system, during the reaction process the
ferrous ion is gradually oxidized into Fe3*, coagulated and
removed as precipitate. Moreover, the sedimentary sludge
containing a great deal of iron ion may be recovered and
utilized again by acidification,c*3 and the retaining hydrogen
peroxide will react little by little to increase dissolved
oxygen in wastewater. From these viewpoints, the Fenton Method
is economical as well as efficient.
3. Methods
The saiple for our experiment is the leachate fro« the
sanitary landfill site of Futekeng in Taipei City, which was
opened on August 29, 1985. A semi-aerobic method was designed
as the disposing means but. after a short period, it turned out
to be anaerobic. The landfill area is 37 hectares, and its
capacity is estimated to be 8 million cu metres. The site is
paved with HDPE liners and has a 1eachate-co1lecting system.
Up to now, it has practised landfill for five years. The waste
organics are decomposed by micro-organism within the landfill
layers. Of the leachate, COD is lowered from the highest amount
45,700 mg/1 to the present amount between 3,000 and 4,000 mg/1:
BOD decreases from 39,520 to 1,000 or so; the concentration of
ammonia nitrogen is raised from 550 mg/1 to 2.500mg/l; pH rises
1130
-------
above 8.0; and a great quantity of methane gas is produced. It
shows that the acid fermentation stage is transformed into the
•ethane generation stage. The way of treating leachate is an
extended activated sludge process, followed by chemical
coagulation. Nevertheless, as the landfill period lengthens,
the color matters of the recalcitrant organics in the leachate
can not be effectively removed by activated sludge process.
Though BOD of effluent may decrease to be below 100 mg/1, COD
is still as high as 2,000 mg/1 and visibility is bad, between 4
and 7 cm. When FeCl9 is used as a coagulant, it needs reagents
of 1,200 mg/1 to reach the visibility of 37 cm, sludge volume
300 ml/1. COD removal efficiency BOX (l,273mg/l). If the amount
of FeCls is increased, visibility will be worse and COD cannot
be improved.1101 Contrasting the advantages of the Fenton
method with the defects of the usual coagulatns in chemical.
coagulation, this study has carried out some preliminary
experiments and proved the distinguished efficiency of the
Fenton method.1111 Thus, we continued to explore further the
wastewater with COD and color that cannot be removed by
biological treatment.
The above-mentioned preliminary experiments have studied
the operating conditions of pH, the mixing time, the
sedimentation time, and the relationship between visibility and
transmittance. and found out the proper scope of operation. The
management conditions adopted by this paper are as follows:
(1) pH control is at 6.0.
1131
-------
tfhen FeSO* = 1,000 ig/1 and H.O. = 750 ag/1. the treated
water will be under perfect control if pH < 7.7 or pH > 12.
when the concentration of FeSO is lowered. in the beginning
pH control must be under 6. Therefore this study decides the
initial pH control to be 6.0.
(2) Transaittance testing adopted wave length is 656 na.
Use Spectrophotoaeter to detect the absorbance of saaples
and treated water from 400 ni to 700 na. A peak appears around
656 na, so the wave is fixed at 656 na.
(3) The rapid aixing tiae of the experiaent is 10 a in.
Coapare COD of the experiaent during the rapid aixing tiae
froa 10 ain to 60 Bin. After the reacting tiae lasts for 10
ainutes. COD of the treating solution does not show auch
change. Thus the reaction is fixed at 10 Bin.
(4) Substitute transaittance for visibility.
To analyze visibility needs the treated saaple aore than
200 al. while transaittance analysis takes only 10 al. To save
the saaple. the relationship between transaittance and
visibility should be first exaained. Vhen transaittance is over
SOX. visibi 1 ity can reach above 15 ca: if over 90%. acre than
25 ca.
4. Results and Discussions
(1) Effects of the concentration of FeS04 :
According to Figure 1, when the dosage of HsCU is fixed at
500 ag/1. that of FeSO is increased (H.Oi/FeSO* decreased) and
COD reaoval rises. When HiOs/FeS04 = 0.59, COD reaoval is at
1132
-------
its best. When H«0B/FeS04 is lowered to less than 0.45, that
is, the adding of FeS04 reashes more than 1,100 mg/1, COD
removal decreases and remains in a stable state. Then the
adding of FeSQ^. should be confined in a proper scope. If
exceeding the range, the treatment effect will be worse.
Judging from the above reaction control, when the concentration
of Fe3* is too high the chain reaction will be restrained, and
that is similar to the phenomenon of chemical coagulation.
(2) Effects of the dosage of H«0a:
Fix the dosage of FeSO at 750 mg/1. According to Figure
2, COD removal is raised as the dosage of HaOg is increased.
It shows that the oxidation of organics is in direct proportion
to the dosage of HaO«.
(3) The dosage of H«0« and FeS04 and their effects on COD
remova 1 :
According to Figures 1 and 2, the suitable proportions
are 0.59 and 0.73, by which the dosage of H»0» and FeS04 is
changed. In figures 3 and 4. when HaO«/FeS04= 0.59, it needs at
least 0.23 g H«0./g COD removed; hereupon, COD removal reaches
only 45X. If the dosage is added UP to 0.367 g H.0«/g COD
removed. COD removal can reach 70.5X. But, afterwards COD
removal does not speed up with the adding of H«0». This point
may be named the most economical point of adding reagents
When H»0»/FeS04 = 0.73, at the most economical point the needed
amount of HaO« is 0.522 g.
1133
-------
According to the most economical point of adding reagents,
the dosage of FeSO has great effect on COD removal. When
HtO./FeS04 = 0.59, it needs only 0.367 g H»0»/g COD removed;
if H»Ot/FeS04 = 0.73, it needs 0.522 g. Therefore, the more
dosage of FeS04 is added, the less amount of H.Oa is needed.
The Fenton method becomes more economical.
(4) Effects of oxidation reduction potential:
Compare the ORP curve with COD removal. When the rising
of COD removal becomes slov and even, so does the ORP. as shown
in Figures 5 and 6. The testing of ORP may be regarded as the
guide of treatment. As for this point, it needs further survey.
(5) The dosage effects of the final pH value:
As the dosage of FeSQ^ and HiOi is increased. pH is
decreased. The more dosage of FeSO^ is added. the more quickly
pH drops. In Figures 5 and 6. the test of pH stops when the
dosage of H»0i is up to more than 1.500 mg/1. because the high
concentration of dissolved oxygen reveals the violent reaction.
To protect the pH electrodes from damage, the test of pH is
ommitted.
(6) Effects of dissolved oxygen:
When the dosage of HiOi is under 1.000 mg/1, there is not
much change in dissolved oxygen (less than 10 mg/1). When the
adding of H*0i is up to 3,000 mg/1. the dissolved oxygen will
rapidly increase and reach 40 mg/1. It is discovered that when
the dissolved oxygen begins to drop, the most economical point
1134
-------
of COD reaoval is obtained. In other words, when COD removal
becomes most effective, HaOa is exhausted by organics and
cannot be transformed into DO. But, when COD removal
efficiency rs not high, the remaining HaOa is transformed into
DO and becomes a waste. The DO value can thus be used to judge
the treating efficiency. Then, the DO , ORP and pH values
are guides for the Fenton method.
(7) The effects of HaO> on COD:
HaOi is an oxidizing agent, whose remaining dosage, if
much, will interfere COD and makes the COD testing value higher
than the actual. It is reported that HaOa can be removed by
KMnO*,t63 but the equivalent point is hard to recognize and
the organics will be oxidized by the overdosed oxidant
simultaneously. So, it is not a reasonable method. The
interference caused by HaOa is not yet solved. However, it is
understood that COD value of the sample is less than the tested
one.
(8) Effects on transmittance:
The Fenton method is good at color removal. When the
dosage of H.O. is 300 mg/1 and that of FeSO* is 508 mg/1 or
411 mg/1, transmittance is above 90S!. When using Fed, and
alum, though their high concentration can achieve the wonderful
effect of decolorization. they cannot remove COD effectively.
The Fenton method, due to its double effect of coagulation and
chemical oxidation, can reach the COD removal efficiency more
1135
-------
than 70X.
(9) Effects of the final pH control on the Fenton method:
Figure 7 shows the initial pH fixed at 6, and the
relationship between the final pH and the transmittance of
supernantent obtained when the concentration of HaO* and FeSOn.
is changed. Froi the Figure, it is discovered that when the
final pH is below 4.5. transmittance can reach above 92%.
Figure 8 indicateds the effect of the final pH on COD removal.
tfhen the final pH is less than 4, COD removal can be more than
60X: if lowered to 3.33, COD removal can be above 70%.
According to these two figures, suppose the initial pH control
is adjusted by acid to be 6. and the final pH, decreased by
the Fenton agent . reaches 3.33. COD removal will be more than
70X, and transiittance above 92X. The actual experiment has
proved the effect, shown in Figure 9. In Figure 9, the
management conditions are: initial pH is 6, the concentration
of FeSO» is 600 mg/1 and 800 mg/1, respectively, that of H»0»
is changed, and the reacting time is 10 minutes, in order that
the final pH is less than 4. Under these conditions, the
transiittance of the treated water can reach above 92X. As
for the COD removal, if FeSO* = 600 mg/1. the final pH = 3.42.
and H.O. = 900 mg/1. it can exceed 71.4X: if FeSO* = 800 mg/1.
the final pH = 3.33. and H.Oi = 780 mg/1, it can be 70.6X.
In this experiment. the final pH control can make sure the
definite COD removal efficiency. (It should be noticed as well
1136
-------
that the initial pH is fixed at 6. If it is 5, 4, or 3, the
effect of COD reioval will not be certain; as Table 1 shows.)
It is clear that though the final pH is important, -the adding
of FeSO* and HiO« is also a pivotal point.
5. Conclusion
(1) Vhen the Fenton method is employed to treat the
leachate that contains low biodegradable organics after
biological treatment, the concentration of FeSOo. plays an
important role on COD reioval. Vhen the concentration of FeSCU
is too low, even if that of HiO» is high, the COD renoval
effect is not good. Besides, the cost of H»0« is higher than
that of FeSO*. To be econonical, the proper dosage of FeSO*
should be first tested with the siall amount of HaOa, and later
add the dosage of H«0« according to the COD reioval rate.
(2) Vhen H.O./FeSO*. = 0.59. the anount of H.O, required
to reiove COD per g is between 0.3 g and 0.5 g; if H«0«/FeSOit =
0.73, the required aiount is fro« 0.4 g to 0.6 g.
(3) In search of the «ost suitable dosage. ORP and
dissolved oxygen can be the references.
(4) The initial pH control is very important. For our
study of the leachate, the initial pH control is froa 6 to 4,
and the final pH is between 3 and 4.
(5) The quantity of sludge resulting froi the Fenton
•ethod is related to the dosage of H»0». In general, the
sludge is 1/4 of the total voluae. If the dosage of H.Ot is
1137
-------
increased, the sludge decreases. Nevertheless, if the dosage
of HtOt is too high and the retention time of sludge is too
long, the reaction within the sludge will accu»ulate a lot of
bubbles to lake the sludge float.
6. Acknowledgments:
The author is grateful to the National Science Council of the
Republic of China for the grants to this study. The author also
wishes to thank his student Fang-Shu Chang, a candidate for MS,
for her executing the experiments of this study.
7. References?
(1) S. Ho . W. C. Boyle and R. K. Ham. "Chemical Treatment
of Leachates from Sanitary Landfills." Journal VPCF 46.7
(1974):1776-1797.
(2) Baxendale. J. H. "Decomposition of Hydrogen Peroxide
by Catalysis in Homogeneous Aqueous Solution. " Advances in
Catalysis and Related Subjects: Volume IV. V. G. Frankengurg,
E. K. Rideal, etc., ed. New York: Academic Press, 1952.
(3) Vindholz, Hartha, ed. The Merck Index: An Encyclopedia
of Chemicals, Drugs, and Biologicals. New Jersey: Merck, 1983.
P.697.
(4) Eisenhauer, H. R. " Chemical Removal of ABS from
Wastewater Effluents." Journal WPCF 37 (1965):1567. And his
"Oxidation of Phenolic Wastes." Journal WPCF 36 (1964).
(5) # ft, K if . Nongnuch Jaksirinont and Jt l£ i§j & . "Fenton £C
ii£«L*:IB#eD
-------
18.207 (august 1981):20-29.
(6) &%-m, tt±3§5fc, etc. " X#JR&W«i4bgftS*0Jft
S." PPM (March 1984): 25-36.
(7) Takashi KORENAGA, Fuaiaki TAKEUCHJ, etc. " Oxidation
of Photographic Waste Waters by Fenton's Reaction." 7ft It B M if
% 12.4 (1989) :233-238.
(8) Khan, Tagui. M. M. Martell, and Arthur Earl.
HoBogeneous Catalysis by Metal Complexes. New York: Acadcaic P,
1974.
*aft*fl>*Rffi| fc ^ (0«* ." PPM (Oct. 1986) :50-63.
(io) flp^tt, etc. Mi-n§ffi^fis^^{ii7k^^«a^w
®mm&&&ya Wtt-g . Taipei: 1989, PP. 255-267.
(11) «£[«. 51^^. "&FENTON&*aS£fc#»»2
*." mHSglBS^^lif »^ . Taipei: 1989, PP. 269-280.
1139
-------
*D.O
»—'70.C -
o
E
o
o
O t».c -
O
BO.O
73.0 -
u
>
o
E
Q
O to.o
O
H202/FeS04 (H202=500mg/l)
H202/FeS04 (FeS04=750mg/l)
Figure 1. Diverse dosage of FeSQ* VS ODD rooval. Figure 2. Diverse dosage of H«0« VS COD reioval.
i-aa.o
COD(ss)
1DO.O
COD(??
2.5000
'occ,» iooto jooc.s
H202 (mg/l) H202/FeS04=0.59
O.CCOC
iooe.0 :ooc.o jooc.c-
H202 (mg/l) H202/FeS04=0.73
Figure 3. Under the condition H.O,/FeSQ* = 0.59 Figure 4. Under the condition H.Oi/FeSO* = 0.73
the required dosage of HtOt to reaove the required dosage of H,0. to reaove
000 per g and ODD re»val efficiency. COD per g and COD reaoval efficiency.
114O
-------
80.0 -
BOO.O
o:
ORP DO. pH*COD(s)
1000.0 -10O.C 10.0 r'00.0
40.0 -
20.0 -
-4.0 p '0.0
E
£-20.0
L o.o *- o.o
00 100C.O zooe.u jv
H202 (mg/l) H202/FeS04=0.59
Figure 5. With the chang of dosage, the relationship between COD and
TRANS., ORP. DO.. and the final pH value, respectivly.
( H»0»/FeSO» = 0.59 )
100.0
so.o -
t/)
z
<
•X.
ORP DO. pH*COD(%)
1000.0 -100.0 r-10.0 100.0
-«0.0
Ifl.O 1-0.0 ^0.0 '-O.O
a°O'o ,0000 ' ' ' ' :oeb.o Joob.o
H202 (mg/l) H202/FeS04=0.73
Figure 6. With the chang of dosage, the relationship between COD and
TRANS., ORP, DO., and the final pH value, respectivly.
( H«0»/FeSO» = 0.73 )
1141
-------
o
E
-------
-
-
-
-
-
(A 1
cz
*- • 1
-
-
-
-
2.C
0
V
2.50
,
3.C
9
0
*
1 5
*i
**
*
t*
**
*
J.50
4.C
0
J
4.50
pH
Figure 9. Under the control of the final pH,
pH value VS transmittance.
Table 1. The control of initial and final pH values
influences COD removal and transmittance.
H.O.,
6nq/l)
450
600
705
750
825
900
345
510
645
705
780
FeSO.
(mg/1)
600
600
600
600
600
600
800
800
800
800
800
inital
PH
4
4.5
5
5
5.5
6
4
4.5
5
5.5
6
final
PH
3.26
3.33
3.36
3.33
3.35
3.42
3.30
3.33
3.33
3.33
3.33
TRANS.
%
94.1
96.4
97.1
97.0
97.1
97.2
94.0
95.5
96.9
97.1
97.7
COD
removal
63.7
67.8
70.2
70.3
68.7
71.4
55.5
59.7
68.5
68.0
70.6
1143
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URBAN LANDFILL SITING STUDIES: A CASE HISTORY
Thomas Kusterer
Montgomery County (Maryland) Government
Department of Environmental Protection
Presented at the
First U.S. Conference on Municipal Solid Waste Management
June 13 - 16, 1990
1145
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Otto von Bismarck, the 19th Century "Iron Chancellor" of Germany, said
there are two things people should never have to see being made: sausages and
laws. A third, and current, "never" could also be added: deciding a landfill
site for a metropolitan area. As Bismarck suggested for the first two, none
of these processes are "picture pretty." And in the case of landfill siting,
there probably isn't a less attractive but critically key issue facing
urbanized areas.
Montgomery County (Maryland) needs a new landfill to serve its 700,000
plus residents. The county completed a 15 month, $525,000 landfill site study
that led to selection of one site by the County Council in April. The site
will undergo detailed engineering studies and work leading to a sanitary
landfill permit. The Council also chose one backup site if significant
problems arise at the selected site during the permit application phase - the
county can quickly switch to developing the backup site. The earliest
projected opening for the new landfill is autumn 1993.
We faced a number of challenges during the study - some conventional,
others not so. These challenges included:
o landfill siting in a high growth county
o land use limitations
o public opposition
o relative scarcity of sites
As with any challenge, there were opportunties, including:
o involvement by elected officials
o mitigation of land use limitations
o public participation
o a balanced approach to the study
WASTE MANAGEMENT PROGRAM
If this conference were held 199 years ago, we'd be sitting in Montgomery
County. The Maryland legislature ceded 36 square miles of the county for the
1146
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new nation's capital in 1791. The county's population, as well as its
geographic area, has changed over time. While I was writing this paper, the
nation observed the 125th anniversary of the end of the War between the
States. Since several skirmishes were fought in Montgomery, I was curious
about the county's population then. Montgomery had about 20,000 residents in
1865 - in 1965, there were about 420,000 residents. From 1965 to present, the
county has grown to about 715,000 residents. A recent report by the Greater
Washington Research Center showed the Washington area to be the second fastest
population growth area in the country. Montgomery led all local jurisdictions
in the area, adding about 23,000 residents between 1987 and 1988. From its
current population of 715,000, Montgomery is projected to grow to 820,000
residents in the year 2000.
All of these people generate appreciable amounts of municipal solid waste
- about 650,000 tons of it in 1989. Using normal compaction rates, this
yearly waste, spread over a football field, would rise more than 700 feet. As
a comparative reference, the Washington Monument is 555 feet high. Estimates
suagest that even at modest growth rates, the County will top one million tons
of municipal waste produced in the year 2000.
How to manage this waste becomes the crux. Montgomery has an ambitious
integrated solid waste management plan consisting of
o source reduction and recycling,
o combustion, and
o landfill ing,
in that order of preference.
The county's mandated goal is to recycle 27* of its waste stream by 1992;
we currently recycle about 133,. Recycling progress is evidenced by the
county's successful newspaper recycling program; pilot programs for commingled
recyclables and yard wastes, leading to phased countywide curbside pickup of
recyclables starting this summer; construction of a Materials Processing
Facility for recyclables, expected to begin operation in spring 1991; and a
nationally recognized program for composting leaves, grass clippings and
sludge.
1147
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The county and its agent have selected a vendor to construct an 1800 ton
per day resource recovery facility. The facility is slated to produce about
40 MH of electricity while reducing the amount of landfill waste by over 7Q%.
We received our approval of a Prevention of Significant Deterioration Source
for the facility in April, 1990.
None of these accomplishments, however, dispels the need for
landfilling. Landfills are necessary for the disposal of non-recyclables and
for disposal of recovery facility ash. In fact, having a landfill is a key
element to help secure financing for the recovery facility.
The county currently has one municipal landfill, which began operations
in 1982. It had a projected life of 15 years, but reached original estimated
capacity in 1989. We got a permit modification to serve disposal needs until
August 1990; we then got a permit for a long-term expansion, relying on
vertical growth capacity at the site, in February 1990. The projected 23 year
expansion hinges on successful recycling and an on-line resource recovery
facility; if these elements don't fall in place, we're facing only six or
seven useful years.
STUDY HISTORY
When the County Executive and County Council hammered out the integrated
waste management plan I noted, they indicated that county government must
conduct an urgent site search, land acquisition and site development program
to find and prepare a new landfill site. The goal of this program was to open
a new landfill as soon as possible so that the current landfill could close.
Part of this stemmed from a political commitment elected officials made; part
of it stemmed from good planning practices seeking a disposal site in a
non-crisis atmosphere; and part of it stemmed to avoid past history. The
current study marks the county's third effort in the last 15 years to site a
landfill. Each effort met typical siting constraints - costs, technical and
environmental issues, and public concerns - but each effort became more
difficult because the county was rapidly losing sites large enough and
environmentally suitable for a landfill given our rapid urbanization. Between
1148
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1978, when the study began leading to the existing landfill, and 1985, 13 of
the 22 potential sanitary landfill sites identified in the 1978 study were
developed.
Similar circumstances occurred during the current study. One of the
sites considered is pegged for residential development; another site is
adjacent to a high density development. Even within county government, there
were competing interests for the candidate sites. A county agency proposed a
golf course on one site. Another agency plans to locate a new detention
center on a study site.
Sites for the current study were chosen from those identified in previous
county landfill studies. We chose this approach to save time, money, and to
hone in on those areas that had been identified as environmentally suitable
for a landfill. This process provided a stock of possible sites, resulting in
16 sites for study. In addition, 26 criteria to rate the sites were
developed. For practical purposes, these criteria fel |