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Flashcards in Solid Waste and Soil Science Deck (89):

Americans dump how many pounds of refuse into landfills every year?

12-15 billion pounds


The average American produces __ lbs of refuse a day

6 lbs


Domestic solid waste is made up of organic and inorganic materials. What are the terms used for these categories and how are they different?

Organics - garbage - material decomposes

Inorganics - Rubbish - Material does not break down by decomposition


In the solid waste field, garbage and rubbish combined is referred to as _________________



One of the biggest problems with refuse is ___________ because while it is organic it does not break down easily due to cellulose



Decomposition in landfills is primarily a (aerobic or anaerobic) process

anaerobic process primarily


Carbohydrates in the landfill are broken down into ________ and ___________ and odor is typically (present or absent

alcohol and organic acids

odors are absent


_________ containing compounds produce strong odors when decomposing



The key to a successful landfill is to control the _______________ because when they decompose their products can support insect, rodent, and bird populations

organic wastes


What are the three methods in which refuse can be buried or placed on the surface

Trench method
Area method
Valley or Ravine method


What is the trench method

aka: cut and fill method

Typically used on level terrain. Trenches are dug, solid waste fills trenches and dirt is placed on top. The trench is then compacted.


What is the area method

Refuse is dumped on the side of a slope and then covered with dirt. Continues into the slope is leveled.

Most common in the united states.


What is the valley or ravine method?

Refuse is dumped in the depression of a valley or ravine. Fill dirt is added and the area is compacted and built up.

Often used in large cities.

Can later be built upon as a golf course or park. No buildings due to settling 10-30%


What are Class I - 3 landfill types

class 1 - hazmat accepted
class 2 - low level hazmat accepted
class 3 - no hazmat accepted


What is the soil of choice for landfills and why?

Sandy loam - a mixture of compactible soil and sand which allows for good compacting characteristics but also good seepage for filtration.


What are 4 factors to consider when evaluating a potential site for a landfill?

1. factors of ground water contamination
2. location and accessibility. type of terrain (level of sloped)
3. soil availability for cover and compaction.
4. average direction of prevailing winds (must not affect nearby communities)


What is a daily cover?

6'' of material, typically earthen material such as soil which is compacted to help prevent fly larvae and other reactions between the waste and the air.

Laid over the deposited waste everyday.


What is an alternative daily cover? ADC

A material other than earthen material used as a daily cover.

Typically waste derived materials such as mixed paper sludge or tire derived aggregate.


What is the final cover?

24'' - a multilayered system of various materials which are primarily used to reduce the amount of storm water that will enter a landfill after closing.

Proper final cover systems will also minimize the surface water on the liner system, resist erosion due to wind or runoff, control the migrations of landfill gases, and improve aesthetics


Name 5 layers that are part of the final cover layer

top soil layer composed of nutrient rich soil

protective layer to reduce the effects of freeze/thaw

drainage layer which moves storm water

barrier layer

grading layer.


What is the ideal slope/percent/degrees for a landfill?

1:2, 50%, 26degrees (33' 54'')


What is the ideal slope/percent/degrees for the final closing of a landfill?

1:3, 33%, 18degrees (26' 06'')


The first 4 to 60 days a landfill is in (aerobic or anaerobic) state?

aerobic state


After 60 days a landfill is in what state?

anaerobic state


How often do landfills get inspected?

Once a month typically


What is containerization

An old technique no longer used where toxic chemicals were buried over absorptive materials (paper, rags etc.)


Define leachate

Any liquid waste that comes out of a landfill.


What are the various sources of leachate?

Rain water seepage
Liquid intentionally dumped at the landfill


What is the paint filter test?

Tests liquids for their viscosity and will dictate if the liquid waste can be accepted by the landfill for disposal


Define composting

Natural process of plant nutrient recycling. Plant materials such as grass and leaves are broken down by bacterial decay (saprophytic bacteria) in the compost resulting in nutrients being deposited back into the soil for use by other plants.


Name what happens in the 3 cycles of the decaying process in composting

first stage - bacteria degrade compost
second stage - fungus, mold, protozoans further break down plant life
third stage - insects such as millipedes, beetles and earthworms complete the cycle.


What can the end product of composting be used for?

It can be mixed with soil to yield more fertile soil for growing plants


Currently, 40-50% of waste to the landfills is ___________

yard waste


In the beginning of composting the heaps have temperatures between _____ and ______ which benefit the process how?

Between 140F and 160F

Help keep fly breeding to a minimum by killing off fly larvae


Is it advised to add foods grains and animal waste to a compost? why or why not?

No. Stick to yard waste only, green plants such as grass and leaves. Foods and grains hinder bacterial action, attract rodents, flies, and cause bad odors.


Why should the compost heap be turned frequently?

To promote aeration. Anaerobic composting should be avoided because it requires a longer time and has more odors.


Sufficient ________ should be maintained while composting. Also, adding new _________ helps keep the bacterial action going.

sufficient moistures
new plant materials


What is humus?

The end product of composting. It's a "soil conditioner" not a fertilizer.


How does humus work as a soil conditioner?

By keeping the soil oxygenated and loose for water flow and absorption.


How much of a reduction in volume can be achieved by composting?

40 to 60%


What are windrows?

The term used for rows of compost piles that are positioned to allow air to flow through and promote the aerobic decomposition


Which method of waste disposal has been around the longest?



In a hospital, biohazards should be incinerated at what temperature?



After proper incineration what percent of solid residual ash can be expected?



What can solid ash from incineration be used for?

To enrich soil


What are two advantages to incineration?

Does not require a large space like a landfill does

Large volume reduction of waste


Why are most backyard incinerators banned?

Because they emit a lot of smoke and pollution into the atmosphere. They are hard to control and maintain the optimal burning temperature.


What are the three elements that must be provided for smokeless incineration and describe each element.

Time - need enough to drive out moisture

Temperature - must be high enough (1500 to 1800F) to maintain ignition and burning of the waste

Turbulence - Proper mixing of combustible gases and oxygen is needed for even and hot incineration.


What is a the batch process?

A process in smokeless incineration where waste is burned in batches rather than as a continuous operation.


Why must the batch process be used in smokeless incineration?

So that high temperatures are maintained and smoke is prevented.


What are liequid chemical scrubbers used for?

In smokeless incineration they are used to control the quality of exhaust. They filter the exhaust air. The problem is disposing of the liquid because it is hazardous.


Name the 6 soil types from sand to clay

sandy loam
silt loam
clay loam


What kind of feel does silt have?

floury or talcum powder feel when dry
sticky when wet


soil that "slicks out" when rubbed between your fingers probably has a fair amount of __________



What kind of particles are said to be gritty?



Sand characteristics

individual grains seen and felt readily

squeezed when dry - falls apart
squeezed when moist - forms a cast that crumbles when handled


Sandy loam characteristics

mostly sand with a little silt and clay

squeezed when dry - falls apart
squeezed when moist - forms a cast that holds with careful handling


Loam characteristics

even mixture of different sizes of sand silt and clay

squeezed when dry - forms a cast that can be carefully handled
squeezed when moist - forms a cast that can be freely handled

slightly plastic
slightly gritty yet smooth


Silt loam characteristics

large quantities of silt, moderate amount of sand, small amount of clay

squeezed when dry or moist - forms a cast that can be handled freely

when dry appears cloddy but lumps are easily broken

will not press out into a smooth ribbon


Clay loam characteristics

a fine textured soil

squeezed when wet and moist - forms a cast that can be handled very freely

will form a ribbon that breaks easily

breaks into clods or clumps that are hard when dry


Clay characteristics

fine textured soil.

breaks into very hard clods or clumps when dry.

very plastic and sticky when wet.

forms a smooth ribbon


What does a red/brown soil color indicate

good water absorption (good perc test results)


What does a blue or black soil color indicate

slower water absorption (poor perc test results)


What is mottled soil and what does it indicate

blotchy colors - indicates not very good water absorption


What are the 6 types of soil structures and how do they filter water?

granular and single grain - filter water quickly
prismatic and blocky - filter moderately
massive and platy - do not filter well


Landfills must be ______ft from lakes and streams



Landfills must be _____ft from human habitation (communities)



Citing landfill sites should be for a duration of at least ___ to ___ years

30 to 40 years


Waste hauling times and route are (more/less) important than community location

more important


Refuse pick up is usually ___ per week in temperate climates and is based on what?

once per week.

based on fly breeding cycle and climate


What are transfer stations?

Stations where hauled waste is unloaded and temporarily stored until another vehicle takes it to the landfill. Use when distances for individual haulers is too far.


Are open dumps legal in the united states?



What is source reduction?

Preventing waste at the source


What is recycling?

collection, processing, or remanufacturing of materials for reuse.

more broadly referred to as "resource recovery"


What does the "in-vessel process" refer to

a method of composting that is highly sophisticated.


What are waste-to-energy plants

plants that capture the heat of combustion in the form of electricity or steam


What are two types of waste-to-energy plants

mass burn facilities

refuse-derived fuel plants


What are mass burn facilities

unsegregated wastes feed the furnace to harvest energy from combustion


What is refuse-derived fuel plants

non-combustibles are first removed and remaining wastes are shredded to produced pelletized fuel that can be used in boilers.


What are cells in landfills?

They are the basic building blocks of sanitary landfills. Each day a cell is created.

The formation of a cell is the equivalent one rise to two runs resulting in a 50% grade


What is a lift in a landfill?

Adjacent cells are called a lift. The entire landfill is a series of lifts


landfill gases, CH4, CO2 and H2S are produced as (aerobic/anaerobic) byproducts?

What should their percentages be?

anaerobic byproducts

CH4 65%
CO2 35%
H2S less than 1%


Liner systems of landfills are usually what material?

typically clay or synthetic


An oxygen concentration meter has a typical detection range of ____%

0-25 %


Combustible gas indicators measure the ____________ and will alarm at _____%

LEL (lower explosive limit)

Will alarm at 20% of the LEL


The grinding of garbage is an acceptable method of______

garbage disposal
volume reduction
wet oxidation
energy recover

garbage disposal


A solid waste manager is trying to reduce lead in the solid waste stream. What should be targeted in the municipal waste stream as a major contributor of lead to the environment?

fluorescent light tubes
lead acid batteries
household batteries
rechargeable batteries

lead acid batteries


All of the following are considered advantages of using the "shredded solid waste" landfill method except which?

it does not cause odors
it may require daily earth cover
it will readily absorb precipitation
it reduces insect breeding

it will readily absorb precipitation


The best sanitary landfill method for a location with rolling terrain would be:

low-area method
valley or ravine area method
trench method
area or ramp method

area or ramp method