Municipal Solid WastesMunicipal Solid Wastes

CE 326 Principles of CE 326 Principles of Environmental EngineeringEnvironmental Engineering

February 2, 2007February 2, 2007Tim Ellis, Ph.D., P.E.Tim Ellis, Ph.D., P.E.

What is a solid wasteWhat is a solid waste

all wastes from human and animal all wastes from human and animal activities that are normally solid or activities that are normally solid or semisemi--solid and are discarded solid and are discarded (includes municipal, industrial, and (includes municipal, industrial, and hazardous wastes).hazardous wastes).

What is Solid Waste Management?What is Solid Waste Management?

activities involved with theactivities involved with the•• reduction of generation,reduction of generation,•• collectioncollection

What is Solid Waste Management?What is Solid Waste Management?storage, storage, transportation, transportation, processing, and processing, and disposal of solid disposal of solid wastes.wastes.

Trash to energyTrash to energy

What is Solid Waste Management?What is Solid Waste Management?

solid waste solid waste management management concerns concerns •• public health, public health, •• environment, environment, •• economics, economics, •• conservation, conservation, •• aesthetics, and aesthetics, and •• other environmental other environmental

considerations.considerations.

What is Integrated Solid Waste Management?What is Integrated Solid Waste Management?

Source ReductionRecycle and Reuse

Treatment

Disposal

Activities designed to meet the hierarchy of MSW management objectives

Waste Generation

Waste handling, separation, storage, and processing at the source:

•shredding, baling•separation for recycling

Collection

Transfer Station

Processing Facility•recycling

•resource recovery•incineration•composting

Ultimate Disposal•landfill

Quantities of Solid Waste ProducedQuantities of Solid Waste Produced

total production is approximately = 246 total production is approximately = 246 million tons/yr (decrease of 1.6 M tons million tons/yr (decrease of 1.6 M tons from 2004)from 2004)average solid waste generated per person average solid waste generated per person = 4.5 lbs/day= 4.5 lbs/daytotal production = 675,000 tons/daytotal production = 675,000 tons/day•• density = 150 lbs/yddensity = 150 lbs/yd33

•• if placed in 3 foot layer, it would cover 8M sq. if placed in 3 foot layer, it would cover 8M sq. ydsyds..

•• 2 2 ½½ sq. milessq. miles•• if placed in 1 cu. ft. stacks, it would rise if placed in 1 cu. ft. stacks, it would rise

40,800 miles high40,800 miles high

One yearOne year’’s worth of solid waste s worth of solid waste from a single householdfrom a single household

Second Priority following Source Reduction is Second Priority following Source Reduction is Recycling and Reuse.Recycling and Reuse.

28% recycling rate in 1999 (64 M tons) vs. 32% in 28% recycling rate in 1999 (64 M tons) vs. 32% in 2005 (58.4 M tons MSW + 20.6 M tons compost)2005 (58.4 M tons MSW + 20.6 M tons compost)9,300 curbside recycling programs in 1998 vs. 9,300 curbside recycling programs in 1998 vs. 8,550 in 20058,550 in 20053,800 yard trimmings and composting programs in 3,800 yard trimmings and composting programs in 1997 vs. 3,470 in 20051997 vs. 3,470 in 2005combusted for energy recoverycombusted for energy recovery•• 2.7 M tons 19802.7 M tons 1980•• 29.7 M tons 199029.7 M tons 1990•• 33.4 M tons (13.6%) 200533.4 M tons (13.6%) 2005

Least Favorable MSW Least Favorable MSW Management Activity: Ultimate Management Activity: Ultimate Disposal (e.g., landfills)Disposal (e.g., landfills)•• Number of landfills in U.S. continues to Number of landfills in U.S. continues to

decrease from about 8,000 in 1988 to decrease from about 8,000 in 1988 to about 3,500 todayabout 3,500 today

Landfills must:Landfills must:•• keep out regulated hazardous wasteskeep out regulated hazardous wastes•• apply a daily coverapply a daily cover•• control disease vector populations control disease vector populations

(rodents, flies, mosquitoes, etc.)(rodents, flies, mosquitoes, etc.)•• monitor methane gasmonitor methane gas•• restrict public accessrestrict public access•• control storm control storm wwaterwwater runrun--on and runon and run--offoff•• protect surface water from pollutants andprotect surface water from pollutants and•• keep appropriate recordskeep appropriate records

Design StandardsDesign Standards•• Landfills must be designed to ensure Landfills must be designed to ensure

drinking water standards are not drinking water standards are not exceeded in ground water. exceeded in ground water.

•• Landfills must be designed with a Landfills must be designed with a composite liner made of synthetic composite liner made of synthetic material covering a twomaterial covering a two--foot clay liner.foot clay liner.

GroundGround--water water Monitoring and Monitoring and Corrective ActionCorrective Action•• All landfills must have All landfills must have

monitoring wells to monitoring wells to detect any detect any groundwater groundwater contamination. contamination.

•• if groundif ground--water is water is contaminated, the contaminated, the owner/operator is owner/operator is required to clean it up required to clean it up to acceptable to acceptable standards to protect standards to protect human health and the human health and the environment.environment.

Closure and PostClosure and Post--Closure CareClosure Care•• When a landfill stops accepting waste it When a landfill stops accepting waste it

must be covered to keep any liquid must be covered to keep any liquid away from the buried waste. away from the buried waste.

•• Once the landfill is closed, the Once the landfill is closed, the owner/operator is responsible for owner/operator is responsible for

maintaining the final cover, maintaining the final cover, monitoring ground water and methane gas, monitoring ground water and methane gas, and continuing and continuing leachateleachate management for 30 management for 30 years.years.

Financial AssuranceFinancial Assurance•• Landfill owners/operators must show that they have Landfill owners/operators must show that they have

financial mechanisms to cover the costs of closure, postfinancial mechanisms to cover the costs of closure, post--closure care, and any needed cleanups from releases. closure care, and any needed cleanups from releases.

•• Financial mechanisms can include surety bonds, letters Financial mechanisms can include surety bonds, letters of credit, insurance, or guarantees, among others. of credit, insurance, or guarantees, among others.

•• The majority of landfills are small (less than 20 tons of The majority of landfills are small (less than 20 tons of municipal solid waste per day) and some may qualify for municipal solid waste per day) and some may qualify for an exemption from the design standards, groundan exemption from the design standards, ground--water water monitoring, and corrective action requirements. To monitoring, and corrective action requirements. To qualify for an exemption, a small landfill must not be qualify for an exemption, a small landfill must not be causing groundcausing ground--water contamination, and must be water contamination, and must be located in either a very dry climate or a very remote located in either a very dry climate or a very remote location.location.

Parts of a Solid Waste Landfill:Parts of a Solid Waste Landfill:

Liner:Liner:•• CompositeComposite

30 mil flexible membrane liner30 mil flexible membrane liner22’’ thick clay liner with permeability (K) less than thick clay liner with permeability (K) less than or equal to 10or equal to 10--77 cm/scm/s

LeachateLeachate: : •• liquid generated from MSWliquid generated from MSW•• Must keep less than 1Must keep less than 1’’ (30 (30

cm) depth in landfillcm) depth in landfill

LCRS:LCRS:•• LeachateLeachate collection and collection and

recovery systemrecovery system

Cell:Cell:•• MSW placed in landfill in one MSW placed in landfill in one

dayday

Daily Cover:Daily Cover:•• Soil placed over MSW each Soil placed over MSW each

daydaytypically 4typically 4--66””

Lift:Lift:•• One layer of cellsOne layer of cells

•• Final Lift:Final Lift:•• Last layer of cellsLast layer of cells

Final CoverFinal Cover•• Final lift + capFinal lift + cap

CapCap•• Liner with Liner with

permeability less permeability less than or equal to than or equal to bottom linerbottom liner

•• Drainage for Drainage for surface watersurface water

•• Gas collectionGas collection