OUTLINE









Definitions
Examples of Landfills in the Valley
Construction on Landfills
Materials Placement in Landfills
Developments on Landfills – why develop landfills ??
Concerns Associated with Development on Landfills
Landfill Materials Investigation
Remediation of Construction and Demolition (C&D) Landfills
Example Projects
DEFINITIONS

MSW Landfill
 C&D Materials
 Inert Debris Landfill
EXAMPLES OF LANDFILLS IN THE VALLEY

C&D Landfills
– Mostly Along the Salt River, Aqua Fria, Gila River &
–
–
–
–
Santa Cruz River
Created Generally by Mining of Aggregates for Concrete,
Asphalt, and Base Course Materials
Pits Left Behind are Backfilled with MSW or C&D
24th St Vulcan Materials, 28th St ( Dean Thomas
Property), Salt River Pima Maricopa Dobson Plant
Tempe Market Place
EXAMPLES OF LANDFILLS IN THE VALLEY
 MSW Landfills
–
–
–
–
Queen Creek Landfill
27th Ave Landfill
Tempe Municipal Landfill
Northwest Regional Landfill, and Others
 Inert Debris Landfills
–
–
–
–
–
Salt River Materials Group Dobson Plant
28th Street Landfill
24th Street Landfill
Cotton Lane Landfill
Estrella Pit
MATERILAS PLACEMENT IN LANDFILLS






No Compaction During C&D Disposals
No Processing is Completed
Creates Nesting of Large Particles
Blind Spots around Odd Shaped Particles
Organics
MSW Decomposes, Develops Settlement, LFG &
Leachate
MATERILAS PLACEMENT IN LANDFILLS
DEVELOPMENTS ON THE LANDFILLS

Install Recreational Facilities
 Low Load Bearing Structures on Compacted MSW,
e.g. Distribution Center
 Heavier Structures on MSW should be on Deep
Foundations
 Industrial and Commercial Developments on C&D
CONCERNS ASSOCIATED WITH LANDFILL
MATERIALS








Large Settlement
Uneven/Differential Settlements
Unpredictable – No Model Available on Stability
Compaction by Itself
Biodegradation
Piping, Internal Erosion and Raveling
Gas (LFG) and Leachate Production, Accumulation
& Contamination of Air and Ground Water
Organics in C&D Takes Too Long to Decompose
LANDFILL MATERIAL INVESTIGATION
SOLUTIONS TO PROBLEMS FOR C&D
LANDFILLS

Deep Dynamic Compaction (DDC) for Inert
Debris Landfills
 Compaction Grout
 Vibrofloatation (Not Common)
 Remove and Reconstruct w/ Engineered
Fill/Debris
Deep Dynamic
Compaction (DDC)
Tempe Market Place
SOLUTIONS TO PROBLEMS FOR C&D
LANDFILLS
Deep Dynamic Compaction (DDC):
– Effective up to 30’-35’
– 30-ton Load Drop from 80-90 feet Height, Multiple
Times
– Imparts approx. 150 ton-ft/sq.ft. Equivalent to 150%
of Standard Proctor Compaction up to 25 Foot Depth
– Evaluate Performance
– Can’t Take Care of all Piping and Raveling
2000
4000
Deep Dynamic Compaction
24th Street and Salt River– Vibration Monitoring
Performance Evaluation
with Plate Load Test
Exam p le Pr o je ct , L o ad T e s t # 1
A ST M D 1194- 94
0.00
A verag e D ef o rm at io n , ( in ch ) .
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0
50
100
L o ad , ( Kip s )
150
200
SOLUTIONS TO PROBLEMS FOR C&D
Debris Fill Specifications
–
–
–
–
–
Anything as long as Inert Debris
2 to 3 feet Lift Thickness
Compaction with 10 to 15 ton Equipment
3 to 4 Passes with 20 to 30 hertz vibration
30 to 60 Gallons/Cu.Yd. Water
Debris Fill Specifications
EXAMPLE PROJECTS
Tempe Market Place
28th Street and Salt River
24th Street and Salt River
14th Street and River View Drive
Tempe Market Place – Before Development
Tempe Market Place – During Stabilization
Tempe Market Place – After Development
24th Street & Salt River
CONCLUDING REMARKS
 Environmental Benefits
 Aesthetic Improvement
 Monetary Value Added
 Land Use
 Positive Economic Impact
 Catalyst
 Stops Illegal Dumping