SOMSOocIO 2027684

2027684

Exponent, Inc.

Expanded PipelineInvestigation Report,Sunrise Mountain LandfillClark County, Nevada

August 1,2003

ExponentFailure Analysis Associates'*

Expanded Pipeline Investigation Report,Sunrise Mountain LandfillClark County, Nevada

August 1,2003

Prepared for:

Mr. Alan GaddyRepublic Services of Southern Nevada770 East Sahara AvenueLas Vegas, NV 89104

Exponent320 GoddardSuite 200Irvine, CA 92618

telephone 949-341-6000facsimile 949-341-60^9www exponent com

Prepared by:

Douglas Hamilton, P.E.Senior Managing Engineer

Exponent, Inc.320 GoddardSuite 200Irvine, CA 92618

Jene E. Lyle, P.E.Senior Engineer

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Contents

Contents i

List of Figures Hi

List of Tables iv

Acronyms and Abbreviations v

Summary and Conclusions 1

1.0 Project Description 5

1.1 Background 5

1.2 Design Constraints 6

1.2.1 Design Stormwater Event 6

1.2.2 Pipeline Description 6

1.2.3 Design Criteria 7

1.3 Scope of Report 7

2.0 Field Investigation 8

2.1 Prior Investigations by Others 8

2.2 Exponent Investigations 8

2.3 Pipe Load Test Investigation 9

3.0 Surface and Subsurface Conditions 11

3.1 Introduction 11

3.2 Geologic Unit Descriptions 11

3.3 Refuse Thickness 12

4.0 Seismic Hazards 13

4.1 Ground Shaking Hazard 13

4.1.1 Probabilistic Approach 13

4.1.2 UBC Site Factor 14

4.1.3 IBC Site Factor 14

4.2 Design Earthquake Event " 15<

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4.3 Seismic Response of Refuse 15

4.3.1 Seismic Response 15

4.3.2 Wave Propagation Effects 16

4.3.3 Seismic Settlement Hazard 16

4.4 Seismic Rockfall Hazard 17

5.0 Other Design Considerations 18

5.1 Settlement of Refuse 18

5.2 Local Surface Drainage 20

5.3 Wind Loading 20

5.4 Temperature Fluctuations 20

5.5 Human Activity 21

6.0 Pipeline Material and Joint Alternatives 22

6.1 Pipeline Material Alternatives 22

6.1.1 High-Density Polyethylene (HOPE) 22

6.1.2 PVC Pipeline Material 24

6.1.3 Concrete 24

6.1.4 Steel 24

6.2 Selection of Pipeline Materials 25

7.0 Foundation Alternatives 26

7.1 Foundation Alternatives 26

7.1.1 Surface Installation with Soil Cover 26

7.1.2 Trench and Cover 26

7.1.3 Foundation Systems 26

7.2 Technical Comparison of Foundation Alternatives 28

8.0 References 31

Appendix A Previous Investigations along Pipeline Alignment

Appendix B Concrete Pipe Load Test Investigation

Appendix C Exponent Evaluation of Deep Pile Foundation and Grade Beam PipelineSupport Alternative

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List of Figures

Figure 1. Controlled Flow Plan Pipeline Alignment Map

Figure 2. Controlled Flow Plan Pipeline Geology Map

Figure 3. Seismic Hazard Curve (PHGA) for the Controlled Flow Plan Pipeline

Figure 4. Uniform Hazard Spectra (5% Damping), Rock Site Condition

Figure 5. Schematic Diagram Showing Pipeline Surface Installation with Soil Cover

Figure 6. Schematic Diagram Showing Cut and Cover Method of Pipeline Installation

Figure 7. Schematic Diagram Showing Deep Foundation System for Pipeline Support

Figure 8. Schematic Diagram Showing Ballast System for Pipeline Support

Figure 9. Schematic Diagram Showing Layout and Anchoring of HOPE Solid Wall Pipeline

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List of Tables

Table 1 Summary of Pipeline Material Cost Estimates 25

Table 2 Summary of Pipeline Material Attributes 25

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Acronyms and Abbreviations

FaAAHOPEPHGAEPARSSNRCPPGAARPUBCDBCUSGSDRIUFAWWAPVC

Failure Analysis AssociatesHigh-Density PolyethylenePeak Horizontal Ground AccelerationEnvironmental Protection AgencyRepublic Services of Southern NevadaReinforced Concrete PipePeak Ground AccelerationAnnual Return PeriodUniform Building CodeInternational Building CodeU.S. Geological SurveyDesert Research InstituteUltraviolet Solar RadiationAmerican Water Works AssociationPolyvinyl Chloride

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Summary and Conclusions

On January 24,2003 Exponent submitted a stormwater protection study which described the

Controlled Flow Plan. On March 20,2003 the United States Environmental Protection Agency

(EPA) Region 9 authorized Exponent to proceed with the design and plans that would

implement the Controlled Flow Plan. This Expanded Pipeline Investigation Report is prepared

and submitted to EPA as part of the implementation of the Controlled Flow Plan. The main

purpose of the Expanded Pipeline Investigation Report is for Exponent to evaluate pipeline

support techniques and material-type options, to address recent issues raised by EPA, and to

recommend the most technically feasible and cost effective option for pipeline support

techniques and pipeline material.

Pipeline Support

To fully respond to EPA's requests regarding pipeline issues, the Expanded Pipeline

Investigation Report examines the following pipeline support alternatives:

1. Burial of the pipeline in a trench on the landfill

2. Placing the pipeline on the landfill surface and burying it with a mound of soil

3. Support using a foundation system

a. Driven Pile Foundation System

b. Drilled Pier and Grade Beam System

c. Rock Ballast Support System

During a June 24, 2003 meeting in San Francisco, EPA requested that Republic Services of

Southern Nevada (RSSN) provide additional investigations on the pipeline element of the

Controlled Flow Plan based on research that EPA was then conducting. On June 27, 2003, EPA

issued a letter requesting that RSSN develop a pipeline alternative that provided support for the

pipeline in areas where it crosses buried waste materials. Attached to the June 27, 2003 letter

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was a "Technical Concern Memo" that mentioned three possible pipeline support methods:

burial of the pipeline in an excavated trench; covering the pipeline with soil on the landfill

surface; and supporting the pipeline on "piers." EPA's design concept of piers resting on

bedrock is termed a Driven Pile Foundation System.

This Expanded Pipeline Investigation Report, along with our January 24, 2003 Stormwater

Protection Plan report explains that one of the principles for the design of the Controlled Flow

Plan is to locate the pipeline above ground, in response to EPA's original concerns that a buried

pipeline might be more difficult to inspect for possible leaks. Therefore, the support techniques

of burying the pipeline in a trench or covering the pipeline with soil on the surface of the landfill

have both been evaluated but rejected in this investigation because the original concerns

expressed by EPA remain valid, and we did not identify any benefits that lessened or

outweighed those concerns.

During a previous meeting, which took place in Las Vegas, Nevada on February 26, 2003, EPA

discussed the possibility of installing a series of piers along the pipeline's route that would

penetrate the waste mass and rest on bedrock. At that meeting, Exponent explained that the

potential for significant landfill settlement along the selected pipeline route is minimal, and that

a Driven Pile Foundation System was not a viable design alternative for supporting the pipeline,

as it would adversely affect its long-term integrity. Additional analysis done for the Expanded

Pipeline Investigation reveals that that a Driven Pile Foundation System is not a viable design

approach for this situation because: 1) if additional settlement occurs, the piles remain at a fixed

vertical elevation ensuring that any possible settlement is expressed as differential settlement; 2)

if the waste mass experiences vertical settlement, the piers would be subject to differential

horizontal movement and could detach the piles from the pipeline; 3) this support system makes

long-term maintenance of the pipeline problematic; and 4) this system would be cost prohibitive

and difficult to construct.

Because it is our opinion that a Driven Pile Foundation System has such a high likelihood of

failure, the Expanded Pipeline Investigation Report develops and evaluates a revised alternative

called a Drilled Pier and Grade Beam System. This alternative is less likely to have long-term

structural failure because the piers are actually drilled into bedrock giving them resistance to

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potential lateral loading caused by buried waste materials. However, this investigation still

rejects the Drilled Pier and Grade Beam System for other technical reasons: 1) the seismic

design of the variable pier lengths and attachment methods for this system is a major

engineering undertaking that could delay project implementation for up to one year; 2) drilling

into bedrock would introduce significant amounts of water to the waste mass during

construction; 3) the interface between the piles and the waste material would create preferential

flow paths deep into the waste mass; 4) this system could be subject to potential horizontal

displacement; 5) this system would be difficult to maintain; and 6) this system is cost

prohibitive and difficult to construct.

Although the potential for settlement along the proposed pipeline route is minimal, the

Expanded Pipeline Investigation identifies a third support alternative, a Rock Ballast Support

System, which is more flexible and responsive to possible landfill settlement than the previous

two systems. This system involves placing a rock and gravel layer upon which the pipeline

would rest. The profile of the pipeline would be surveyed annually and, if there were differential

settlement, ballast would be placed or removed to adjust the pipeline's gradient. The Rock

Ballast Support system is a straightforward, proven technology that has been used for more than

a century in the railroad industry. Railroad ballast systems are used to maintain tight tolerances

in environments with extreme temperature ranges for challenging site conditions such as active

landslide areas, where the underlying soil is much less stable than could be realized at the

Sunrise Mountain Landfill. Because a Rock Ballast Support System is straightforward to design

and construct it can be periodically adjusted, if necessary, to maintain the pipeline gradient, and

it does not compromise the landfill cover by penetrating it like pier systems do. The Expanded

Pipeline Investigation Report concludes that a Rock Ballast Support System is clearly the most

suitable pipeline support method for the pipeline to be installed as part of the Controlled Flow

Plan at the Sunrise Mountain Landfill.

Pipeline Material and Joint Technique

The Expanded Pipeline Investigation Report evaluates the following pipeline materials and joint

techniques:

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1. High Density Polyethylene (HOPE)

a. Solid wall with fusion welded joints

b. Corrugated with gasketed bell and spigot joints

2. Polyvinyl Chloride (PVC) with gasketed bell and spigot joints

3. Reinforced Concrete with gasketed compression joints

4. Steel pipe with concrete corrosion protection lining and welded joints

The pipeline materials listed above were evaluated based on the ability of the pipeline support

system to accommodate possible differential settlement, avoiding localized stress concentrations

at the pipeline joints; and other design issues: durability, thermal expansion, ultraviolet light

(UV) protection, flexibility, and ease of maintenance. The investigation concludes that solid

wall HOPE pipe with fusion welded joints is the most suitable pipeline material for the pipeline

to be installed as part of the Controlled Flow Plan for the following reasons: its gradient can be

readily adjusted on the Rock Ballast Support System, if necessary, to respond to possible

settlement; its large wall thickness provides more UV protection and resistance to possible

gunfire than corrugated HOPE; the fusion welded joint avoids localized stress concentrations;

and this pipeline material is generally more flexible and easier to maintain than other materials.

A preliminary pipeline design is provided in this report for the recommended system. This

system includes a Rock Ballast Support System for the entire pipeline route with geogrid

reinforcement where the pipeline transitions from native soil to the landfill cover soil. The solid

wall HOPE pipeline will be laid out in a slight serpentine pattern to accommodate thermal

expansion. The pipeline will be anchored at a series of points along its route to provide stability

from seismic, wind, thermal, and hydrodynamic forces.

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1.0 Project Description

1.1 Background

Pursuant to an agreement with the United States Environmental Protection Agency (EPA)

Region 9, Republic Services of Southern Nevada (RSSN) is preparing design plans for the

construction of the Controlled Flow Plan to provide stormwater protection to the closed Sunrise

Mountain Landfill. This plan is described in Exponent's January 24, 2003 report entitled,

Stormwater Protection for the Proposed Sunrise Mountain Landfill, Clark County, Nevada.

Additional stormwater protection measures are proposed in Exponent's June 19,2003 report

entitled, Cover Plan, Sunrise Mountain Landfill, Clark County, Nevada.

One element of the Controlled Flow Plan is a pipeline designed to convey stormwater across the

surface of the closed landfill along its eastern margin, hi the Controlled Flow Plan, stormwater

originating from a 200-year event in the upper part of the watershed will be impounded behind

an earthfill detention dam located in the Northeast Canyon area (Figure 1). The pipeline is

designed to convey impounded water from the detention basin to a channel at the southeastern

margin of the landfill. The detention basin will be drained by the pipeline within a period of

approximately 24 hours after the 200-year design storm. Design alternatives for the stormwater

detention basin, dam, and outlet works are presented in Exponent's June 27, 2003 report

entitled, Geotechnical Engineering and Engineering Geologic Report, Proposed Stormwater

Detention Basin, Sunrise Mountain Landfill, Clark County, Nevada.

During a June 24, 2003 meeting in San Francisco, EPA requested that RSSN conduct additional

investigations on the pipeline element of the Controlled Flow Plan based on research that EPA

was then itself conducting. On June 27, 2003, EPA issued a letter requesting that RSSN

develop a pipeline alternative that provided support for the pipeline in areas where it crosses

buried waste materials. Attached to the June 27, 2003 letter was a "Technical Concern Memo"

that mentioned three possible pipeline support methods: burial of the pipeline in an excavated

trench; covering the pipeline with soil on the landfill surface; and supporting the pipeline on

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"piers." In a June 30, 2003 letter from Don Patterson, Esq., attorney for RSSN, a request was

made for additional information about EPA's concerns. In a July 18, 2003 letter, EPA declined

to provide supporting documentation for several concerns expressed in its "Technical Concern

Memorandum." The July 18, 2003 EPA letter stated that the June 27,2003 memo was basically

self-supporting, but also cited the American Water Works Association (AWWA) Manual M9,

Chapter 6, and conversations with unnamed individuals at several concrete pipe manufacturers

associations.

In an email dated July 18th from David Basinger of EPA Region 9 to Alan Gaddy of RSSN,

EPA acknowledged that it would accept the Expanded Pipeline Investigation Report as

compliance with the relevant parts of the Controlled Flow Plan schedule. No further information

on its pipeline research or requests for information have been received from EPA since its July

18,2003 letter and email.

1.2 Design Constraints

1.2.1 Design Stormwater Event

The pipeline for the Controlled Flow Plan will have a peak flow capacity of approximately 90

cubic feet per second. For the 200-year design storm event, the pipeline will flow for

approximately 24 hours after the design storm.

1.2.2 Pipeline Description

The proposed above-grade pipeline will have an inside diameter of approximately 34 inches and

a length of about 5,100 feet, of which 2,800 feet will cross over the Eastern Perimeter of the

landfill. The pipeline will extend an additional 400 feet under the dam embankment to the

detention basin's outlet structure. Figure 1 shows the approximate pipeline alignment.

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1.2.3 Design Criteria

The performance objectives of the pipeline system could potentially be accommodated by a

number of pipeline materials and foundation approaches. In this report, we evaluate a number

of criteria in order to identify the most suitable pipeline system for the Controlled Flow Plan.

These criteria include:

• The engineering characteristics of the refuse and geologic units along the alignment

• The seismic setting and potential seismic response of the refuse and geologic units

along the alignment

• The environmental setting of the pipeline alignment

• Efficiency of construction, inspection and maintenance of the pipeline system

• Avoiding construction activities that would compromise the waste mass

• The potential impacts of human activity

• Cost effectiveness

1.3 Scope of Report

This Expanded Pipeline Investigation Report summarizes Exponent's evaluation of design

alternatives for the pipeline portion of the Controlled Flow Plan. Our study includes:

• Summary of surface, subsurface and geologic conditions along the pipelinealignment

• Summary of seismic design considerations relevant to the pipeline

• Technical evaluation of other design considerations for the pipeline,including possible settlement, surface drainage, wind loading, effects of solarradiation, temperature fluctuations, and human activity

• Technical evaluation of pipeline material and pipe segment joiningalternatives

• Technical evaluation of foundation alternatives to provide support for thepipeline

• Evaluation of costs for different pipe materials, joint types, and pipelinesupport

• Description of recommended pipeline system

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2.0 Field Investigation

2.1 Prior Investigations by Others

SCS Engineers, Inc. (SCS) performed a number of field investigations at the closed Sunrise

Mountain Landfill, including the area covered by Figure 1. Among the data collected by SCS,

were a number of hollow-stem auger borings through refuse performed between January and

July, 2000 at EPA's direction. The locations of these borings are shown on Figure 1. Six of the

SCS borings (CB-7, CB-9, and CB-12 to CB-15) were performed in the Northeast Canyon area.

Logs of these borings are presented in Appendix B of our June 27, 2003 report. Logs of the

remaining four borings (CB-4, CB-6, CB-10 and CB-11) are provided in Appendix A of this

report.

Data from the SCS borings were combined with topographic survey data to derive the refuse

thickness contours that are shown on Figure 1. The refuse thickness contours reported on

Figure 1 are consistent with the data obtained from borings performed by Exponent in the area

of the dam investigation (Exponent, 2003c). Waste depths range from 5 feet to 25 feet along the

part of the pipeline alignment that crosses waste.

2.2 Exponent Investigations

Exponent has prepared three prior reports that contain information relevant to the current

investigation. Exponent (2003a) identifies the Controlled Flow Plan for stormwater protection

and contains engineering geologic observations of the slopes and drainages bounding the eastern

side of the Sunrise Mountain Landfill in the vicinity of the initially proposed pipeline alignment.

Exponent (2003b) is the Cover Plan which identifies final erosion and drainage improvements to

the landfill cover along the pipeline's proposed alignment. Exponent (2003c) reports the results

of an engineering geologic and geotechnical investigation for the proposed detention dam and

basin components of the Controlled Flow Plan. The proposed dam is located at the northern end

of the pipeline alignment. Figure 1 shows the locations of field investigations performed in the

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area of the proposed dam and detention basin. The logs of the borings, cores, test pits and

trenches performed by Exponent in the area of the dam and detention basin are reported in

Exponent (2003c).

2.3 Pipe Load Test Investigation

At the February 26, 2003 meeting, EPA suggested the possibility of using reinforced concrete

pipe (RCP) material rather than the originally proposed corrugated HOPE pipe in order to

provide additional durability and resistance to possible penetration by firearms. Exponent

conducted a pipe load investigation to determine whether the increased weight caused by

placing concrete pipeline material on the landfill surface would cause local consolidation and

settlement near the landfill surface. This section provides a brief summary of the load test

procedures and results. Details of the pipe load test investigation are provided in Appendix B.

Four 8-foot long, 42-inch diameter RCPs (each weighing approximately 6,880 pounds) were

individually placed along the proposed preliminary alignment of the pipeline on May 14, 2003.

A fifth pipe segment was placed in an area underlain by approximately 40 feet of refuse, which

is significantly more than the greatest thickness of refuse traversed by the preliminary pipeline

alignment, but is not directly on the alignment. The pipe test locations are shown on Figure 1.

The fifth pipe segment was filled with sacks of cement to increase its weight to approximately

9,130 Ibs to simulate a water-filled condition.

On May 15, 2003, string lines were installed at each pipe segment to allow measurement of

settlement prior to field survey control being established. On May 20, 2003, Horizon Surveys

(Horizon) set survey nails in the top of each pipe inlet and outlet, and placed four survey hubs

approximately 8 feet away from each pipe to monitor indications of ground movement. Horizon

monitored settlement of the RCPs on a weekly basis through July 3, 2003.

During the six-week survey period, minimal settlement was recorded at the pipe segments. At

locations RCP-1 and RCP-2 a maximum of 0.01 feet (0.12 inches) and 0.015 feet (0.18 inches)

were measured, respectively. The cement-weighted segment exhibited essentially no settlement.

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The differential leveling surveys show that pipe segments experienced no significant localized

settlement over the monitoring period.

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3.0 Surface and Subsurface Conditions

3.1 Introduction

Our geologic assessment indicates that the proposed pipeline alignment crosses Hermit

Formation bedrock, refuse, and possibly (beneath the refuse) thin intervals of alluvium or

colluvium. Figure 2 shows the spatial distribution of geologic units along the pipeline

alignment. Brief descriptions of these geologic units crossed by the pipeline alignment are

provided below. Engineering geologic descriptions of other geologic units in the vicinity of the

Sunrise Mountain landfill (indicated on Figure 2) are provided in Exponent (2003a) and

Exponent (2003c).

3.2 Geologic Unit Descriptions

Hermit Formation (Ph)

Several portions of the pipeline alignment are located on surficial outcrops of the Hermit

Formation. The Hermit Formation is also interpreted to form the substrate beneath the refuse

along much of the pipeline alignment. Hermit Formation bedrock generally consists of reddish-

brown fine to medium grained sandy siltstone and silty sandstone. Locally, it contains intervals

of grayish-yellow to white cross-bedded sandstone. Beneath a slightly weathered surface, the

Hermit Formation is hard, as indicated by a resistance to drilling. Hollow-stem auger borings

performed for the dam investigation (which used an 8-inch diameter flight auger) generally

could not penetrate more than a few inches into the Hermit Formation before the auger bit was

destroyed.

Refuse (R)

This unit consists of refuse that is covered with a locally-derived cover layer. Refuse excavated

from the borings, performed for the dam investigation, consisted primarily of dry, miscellaneous

household waste. In most areas, the cover material consists of fine-grained compacted fill

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material derived from local alluvium and colluvium deposits. Portions of the landfill are

mantled with limestone gravel and cobbles for erosion protection. Based on the SCS and

Exponent borings, the refuse generally lies directly atop the Hermit Formation. Locally, a thin

layer of alluvium separates the refuse from the underlying Hermit Formation.

Alluvium (Qa) and Colluvium (Qcol)

Alluvium and colluvium partially mantle the base of the Eastern Ridge along the proposed

pipeline alignment. Alluvium and colluvium encountered during the dam investigation

consisted primarily of light brown, lightly to moderately cemented, sandy gravel, with

occasional limestone cobbles and boulders. Hollow-stem auger borings performed for the dam

investigation were advanced with difficulty through the alluvium and colluvium due to the

presence of this resistant limestone material.

3.3 Refuse Thickness

Figure 1 shows refuse thickness contours along the proposed pipeline alignment, based on work

by SCS Engineers. As shown on Figure 1, the refuse fills the preexisting valley to depths of as

much as 120 feet above the original ground surface beneath the south-central portion of the

landfill. Because the pipeline alignment is located along the eastern edge of the landfill, the

refuse beneath the pipeline alignment is typically 20 feet in thickness.

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4.0 Seismic Hazards

4.1 Ground Shaking Hazard

The Sunrise Mountain Landfill is located in a tectonically quiet portion of the Basin and Range.

No historic earthquakes larger than magnitude 5.0 have occurred within 100 miles of the site.

The local faults, though potentially capable of generating moderate to large seismic events,

accumulate stress so slowly that return times for major earthquakes on any of them is typically

on the order of 50,000 to 100,000 years or longer. The seismic groundshaking exposure of the

pipeline and appurtenant structures has been modeled using a probabilistic approach (see

below). Details of the historic seismicity and seismic source faults in the project vicinity are

provided in Exponent (2003c).

4.1.1 Probabilistic Approach

The probabilistic ground-shaking hazard for the pipeline was evaluated using nationwide data

compiled in the "Probabilistic Seismic Hazard Maps for California, Nevada and Utah" (Frankel,

et al., 1996; Frankel, et al, 2002) for a firm rock site classification. This site classification

corresponds to the geologic conditions at the landfill, wherein the shear-wave velocity averaged

over the top 100 feet is estimated to be about 2,500 feet per second (Exponent, 2003c).

The 2002 maps provide values for peak ground acceleration (PGA), as well as for 0.2 sec and

1.0 sec spectral acceleration (assuming 5% damping) corresponding to 475-year and 2,475-year

annual return periods (ARP). The 475-year average annual return period (ARP) is consistent

with the 1997 Uniform Building Code (UBC) for design of conventional structures.

The annual probability of exceeding a specific level of ground motion is shown on Figure 3.

The hazard curve shown in Figure 3 represents the contribution of several sources added to

obtain the total seismic hazard at the landfill. Based on the 2002 seismic hazard maps, the peak

horizontal ground acceleration (PHGA) at the landfill is estimated to be 0.12g for a 475-year

APR, and 0.25g for a 2,475-year APR.

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4.1.2 UBC Site Factor

According to Figure 16-2 of the 1997 UBC, the landfill is located in Zone 2B. Based on 1997

UBC Table 16-J, the soil profile for landfill is assumed to be type SB (rock sites), as discussed

above. The seismic source type is B (Table 16-U), based on the proximity of the Frenchman

Mountain fault to the landfill (Exponent, 2003c). Based on the soil profile and seismic source

type, we suggest the following coefficients for the pipeline:

Near-Source Factor Na

Near-Source Factor Nv

Seismic Coefficient Ca

Seismic Coefficient Cv

Not applicable toZone 2B

Not applicable toZone 2B

0.20

0.20

4.1.3 IBC Site Factor

According to Figures 1615 (1) and 1615 (2) of the IBC 2000, the Sunrise Mountain Landfill is

located in an area of Nevada in which the maximum earthquake ground motion for short period

response Ss is equal to 0.80g and for the long period response, Si is equal to 0.23 g (Exponent,

2003c). Based on the subsurface conditions at the landfill (see above), and Table 1615.1.1 of

the 2000 IBC, the Site Class Type is expected to be "B". Based on the soil profile and site

location we suggest the following coefficients for the pipeline:

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Maximum Considered Short-Period Spectral Response Ss

Maximum Considered Long-Period Spectral Response Si

Site Coefficient Fa

Site Coefficient Fv

Design Short-Period Spectral Response SDS

Design Long-Period Spectral Response SM

0.80

0.23

1.00

1.00

0.53

0.15

4.2 Design Earthquake Event

A design seismic response spectrum is necessary to evaluate the seismic stability of the pipeline.

Using the probabilistic approach, we recommend adopting a design acceleration spectrum

corresponding to a 2,475-year earthquake event (the same as for the dam). We have evaluated

the analysis and results by the USGS for this hazard level in their 1996 and 2002 studies. As

shown on Figure 4, we have compared those results with the IBC 2000 spectra for the site. Our

recommended seismic design spectrum completely envelops the 2002 USGS and IBC 2000

spectra. As shown on Figure 4, the recommended design spectra has a PHGA of 0.30g, a peak

spectral acceleration of 0.6g between periods of 0.08 and 0.32 sec, and a spectral acceleration of

0.09g at 2 seconds.

4.3 Seismic Response of Refuse

4.3.1 Seismic Response

In order to evaluate the pier alternative suggested by EPA, the lateral loads that could be caused

by buried waste shifting and pushing against the piers, needs to be addressed. The seismic

response of a buried waste mass is a function of several variables, including: dynamic refuse

properties, fill heights, site conditions, and earthquake motions (Bray, et al., 1998). Historically,

landfill covers have not been significantly damaged in earthquakes (USEPA, 1995). Two

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earthquakes in particular, the October 17, 1989 Loma Prieta earthquake (M = 7.1) that occurred

in the San Francisco area, and the January 17, 1994 Northridge earthquake (M = 6.7) that

occurred just north of Los Angeles, have provided much useful information on the seismic

performance of landfills.

Orr, et al. (1990) surveyed 10 landfills in areas impacted by the Loma Prieta earthquake. The

estimated PHGA at these sites ranged from 0.1 to 0.45 g (the PHGA for Sunrise Mountain

Landfill is 0.3g). Based on the results of their survey, Orr, et al. (1990) concluded that the

landfills were not significantly damaged in the earthquake. They found the most common type

of damage to be surficial cracking in the landfill side slopes. From their review of landfill gas

extraction systems, Orr, et al. (1990) concluded that flexible pipeline designs accommodate

seismic events better than other approaches.

Matasovic, et al. (1995) collected and analyzed information for twenty-two landfills within the

area impacted from the Northridge Earthquake. These landfills had estimated PHGA's ranging

from 0.07 to 0.51 g. Based on their work, Matasovic, et al. (1995) concluded that the landfills

performed well; the most common damage reported was cracking of cover soils at transitions

between refuse fills and natural ground. None of the studies reviewed analyzed potential loading

that could be caused by shifting materials within the waste column.

4.3.2 Wave Propagation Effects

Seismic waves traveling across the site during a potential earthquake event would transmit

energy to the pipeline. The final design of the pipeline support system will address possible

wave propagation effects.

4.3.3 Seismic Settlement Hazard

Seismic-induced settlement is a phenomenon that can affect certain natural soils such as loose

sand. However, seismic-induced vertical settlement has not been an issue at other landfills .

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The Mission Canyon Landfill in Los Angeles County was equipped with instrumentation to

measure vertical and horizontal movements of refuse (Coduto, 1990). These instruments were

in place when the Whittier Earthquake shook the site on October 1,1987. The earthquake had a

magnitude of 5.9 and occurred approximately 14 miles from the site. No significant vertical

movements were recorded during this event.

4.4 Seismic Rockfall Hazard

Rockfall is considered an unlikely seismic hazard to the pipeline because its alignment is

outside the reach of detached, rolling boulders originating on the Eastern Ridge.

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5.0 Other Design Considerations

5.1 Settlement of Refuse

There are three generally recognized mechanisms for consolidation of buried waste in landfills

that could result in vertical settlement of the landfill cover. These mechanisms are:

1) compression of waste due to loads applied by construction equipment and by the weight of

additional waste placed above it; 2) secondary compression or creep caused by the long-term

effects of gravity; and 3) biological decomposition of buried waste materials (Marques et al.,

2003). The Sunrise Mountain Landfill has been closed since 1993, so it is likely that

consolidation due to compression effects has already taken place. Secondary compression is

negligible in magnitude compared to the other components (Park, et al., 2002). Consolidation of

waste materials due to biological decay can result in actual landfill settlement only if biological

decay is an active process within the waste mass. Both EPA's June 27, 2003 "Technical

Concern Memo" and Exponent's exploratory borings done in April and May 2003 confirm that

biodegradable buried waste material has not undergone significant decay at the Sunrise

Mountain Landfill. As discussed in the Exponent Cover Plan Report (Exponent, 2003b), the

main reason for the absence of significant biological decay is that an inconsequential amount of

water flux is occurring through the existing cover into the waste mass. This is due to the low

rainfall and high evaporation rates that are characteristic of the Las Vegas, Nevada area

(Exponent, 2003b).

Our review indicates that the rate of biological decomposition of landfill refuse generally

decreases over time and that the total amount of consolidation of the waste mass due to

biological decomposition can range from 18% to 24% for landfills where biodegradation is an

active process (Coduto et al. 1990). Biological decomposition at the Sunrise Mountain Landfill

is occurring at a very slow rate. Little biodegradation was observed in the refuse encountered in

Exponent's borings in the Northeast Canyon area, which contains some of the oldest refuse at

the site (some of it potentially having been in place for over 50 years, SCS, 2001). After the

OC10290 001 GOTO 0803 RDH3 18

implementation of the proposed Cover Plan, the potential for water flux into the landfill would

be reduced thus slowing down biodegradation rates even further.

The actual rate of vertical landfill settlement can be estimated using available on-site settlement

monitoring data. The existing gabion structure, which was built in 1994, is located on

approximately 60 feet of refuse. A survey performed by SCS Engineers in 1999 indicates this

structure experienced settlement of between 0.1 and 0.3 feet compared to as-built survey data. A

net settlement of 0.3 feet between 1994 and 1999 over 60 feet of refuse translates to an annual

vertical strain of about 0.1 percent and a settlement rate of less than % inch per year.

There are 5 settlement monuments on-site that were surveyed in July 2002 and July 2003.

Monument SM3 recorded the greatest amount of settlement between the survey dates, totaling

0.45 ft. SM3 has approximately 100 feet of refuse beneath it, thus the observed settlement

represents an annual vertical strain of about 0.45 percent. Assuming this maximum strain is

applicable to areas along the pipeline route which are situated on approximately 20 feet of

refuse, this translates to a maximum vertical settlement of approximately 0.09 feet, or slightly

more than 1 inch on an annual basis. Because this maximum rate of observed settlement can be

expected to decrease exponentially over time, it could take a decade or two in order for

biodegradation of the waste mass to achieve onlyl foot of vertical settlement along the pipeline

alignment. Even if 1 foot of settlement occurred non-uniformly, it would be straightforward to

maintain a uniform pipeline alignment under these conditions.

The slow rate of overall biologic decomposition at the Sunrise Mountain Landfill is an indicator

of negligible water flux into the waste mass. Any decrease in the amount of moisture entering

the landfill would further decrease the settlement rate. Annual maintenance measures that

would ordinarily be performed for the landfill's surface would satisfactorily achieve positive

drainage for the final cover and would also aid in maintaining a positive flow line gradient for

the pipeline, assuming that it rests on the surface of the landfill.

OC102&0 001 GOTO 0803 RDH3 19

5.2 Local Surface Drainage

The proposed pipeline alignment encounters minor sheetflow surface drainage conditions along

its length. Immediately downstream of the detention basin embankment, the proposed pipeline

alignment is located on a graded bench adjacent to the existing Northeast Canyon Channel

(see Figure 1). Instead of terminating the pipeline at the entrance to the existing channel

(Channel No. 1), the alignment then bends to the east across the landfill and extends to the south

along the base of the Eastern Ridge. Carrying the pipeline across the eastern perimeter of the

landfill accommodates EPA's concern that no additional water flow through the existing

channel.

Final design details for the surface drainage along the pipeline alignment will depend on the

implementation of the Cover Plan. Exponent will supplement this report as necessary based on

EPA's comments and eventual actions related to implementation of the Cover Plan.

5.3 Wind Loading

Final design of the adopted pipeline system will include measures to resist potential movement

of the pipeline by wind.

5.4 Temperature Fluctuations

The Desert Research Institute operates a series of weather stations throughout the western

United States. Historical temperature data was reviewed from the weather station at the Las

Vegas McCarran Airport. The period of coverage was February 1, 1937 to December 31, 2002.

For the period of record, the daily maximum temperature was 117 degrees Fahrenheit and the

daily minimum temperature was 8 degrees Fahrenheit (DRI, 2003). The adopted pipeline

system will be designed to accommodate these temperature fluctuations.

OC10290 001 GOTO 0803 ROH3 20

5.5 Human Activity

Currently, there are several miles of exposed pipelines on grade at the Sunrise Mountain

Landfill. These pipelines are used for gas extraction. The main entrance to the Sunrise Mountain

Landfill is gated and there are trenches hindering vehicle access around the main gate. There is a

full-time attendant present at the landfill office during daytime hours and security patrols who

monitor conditions at night. To date there have been no recorded incidents of vandals shooting

weapons at the existing above ground pipelines. If major vandalism did occur at the site, it is

likely that such an event would be identified and the damage repaired quickly in the normal

course of operation because there is and will be a full-time presence at the site. Additionally, the

relative rarity of extreme storm events in this area makes it highly unlikely that such damage

would not be identified and repaired before the occurrence of such a storm event.

OC10290 001 GOTO 0803 RDH3 21

6.0 Pipeline Material and Joint Alternatives

6.1 Pipeline Material Alternatives

Several potential pipeline materials and their respective joint alternatives are evaluated in this

report. Key criteria include: durability, thermal expansion, UV resistance, pipeline support

system, and the ability to provide maintenance that would accommodate the possibility of some

landfill settlement.

EPA's reference to AWWA Manual M9, Chapter 6 in its July 18, 2003 letter has been addressed

in our discussion of reinforced concrete pipes below in Section 6.1.3. However, this citation

applies to continuously pressurized water delivery pipe networks that are used for domestic

water delivery systems. The AWWA Manual referenced by EPA is not applicable to the

proposed stormwater pipeline at the Sunrise Mountain Landfill because it is a gravity flow,

stormwater discharge pipeline, rather than a pressurized domestic water pipeline. The AWWA

Manual M9 recommendations cited by EPA are also not applicable to the flexible pipeline

systems which are addressed here.

6.1.1 High-Density Polyethylene (HOPE)

6.1.1.1 Solid Wall Pipe

Solid wall HOPE pipes can be used above and below ground. For this specific application a

carbon black HDPE pipe with an outside diameter of 36 inches and a wall thickness of 1.1

inches is considered. Each pipe segment would be joined via a butt fusion weld that provides a

continuous leak-proof connection between adjacent pipe segments. The pipe weighs

approximately 50 pounds per linear foot and costs approximately $88 per linear foot for the

material and installation.

OC10290 001 GOTO 0803 RDH3 22

Black carbon HDPE has excellent UV resistance and is recommended and warrantied for above-

ground use by the manufacturer. The material's flexibility allows the pipe to accommodate

horizontal and vertical movement as well as allowing regular maintenance adjustments in

gradient adjustment over time.

The potential linear thermal expansion of HDPE can be accommodated in the design of the

pipeline system. HDPE material has a low elastic modulus such that, under equivalent

conditions, the thermal stresses in HDPE pipe are significantly smaller than in steel or concrete

pipe. Hence, solid wall HDPE pipelines are typically installed in situations where flexibility is

important. The pipeline is laid out in a serpentine manner, such that the thermal elongation

between each anchor point is mitigated by the lateral deflection of the pipeline. This method of

installation requires concrete cradle attachment points to stabilize and constrain the pipeline

from wind and hydrodynamic loads. Expected wind loads, thermal expansion and topographic

features determine the spacing of the attachment points. Our preliminary design concludes that

the attachment points for this system would have to be spaced approximately every 350 feet. A

HDPE pipeline would be attached to the concrete attachment points using stainless steel clamps.

6.1.1.2 Corrugated HDPE with Smooth Interior

An alternative lightweight HDPE option is corrugated pipe with a smooth interior wall. A 36-

inch inside diameter pipe would weigh approximately 20 Ibs per linear foot. The material and

installation cost is approximately $61 per linear foot.

The thinner wall of the corrugated pipe results in the development of lower thermal forces than

the solid wall HDPE pipe. As a result, this pipe design could be laid out straight and would not

need concrete attachment points or thrust blocks for restraint against thermal expansion. Each

pipe is joined via a reduced spigot and bell design and sealed with a gasket.

The pipe's resistance to UV is provided by the addition of more than 2% carbon black.

Although this additive provides excellent UV protection, the thinner walls of the thin corrugated

pipe may not provide the same life expectancy against UV radiation as the thicker solid wall

HDPE pipe described previously.

OC10290 001 GOTO 0803 RDH3 23

6.1.2 PVC Pipeline Material

Polyvinyl chloride (PVC) pipes are commonly used in below-ground and above-ground

applications for municipal water distribution services and for irrigation. PVC pipes are typically

joined via a bell and spigot joint sealed with a gasket. However, PVC pipes are susceptible to

UV radiation and are thus not suited for long-term above ground installation. A pipeline using

PVC material will not be further evaluated in this investigation.

6.1.3 Concrete

The reinforced concrete pipe (RCP) would have an inner diameter of 36 inches, a wall thickness

of 4 inches and would weigh approximately 600 Ibs per linear foot. Each pipe segment would

be approximately 8 feet long and joined with a compression rubber gasket. The RCP pipeline

will cost approximately $79 per linear foot.

6.1.4 Steel

Steel pipes are commonly used for pressurized systems but could be adapted for gravity

stormwater drainage. This type of pipeline material has an internal layer of cement to protect the

steel from corrosion. For gravity flows, internal pressures are negligible, such that the wall

thickness is determined by the spacing of the pipe's support points. Assuming a 50 foot

spacing, a 36 inch inner diameter steel pipe could be made of 10-gage steel (wall thickness of

approximately 0.1435 inches) and have a cement lining with a wall thickness of 0.375 inch.

This would result in an approximate weight of 100 Ibs per linear foot.

For external corrosion protection, the exterior of the pipe would have to be sandblasted, then

painted with a primer and a UV-tolerant topcoat. Each pipe segment would be welded on the

job site and the cement liner gap at the weld would be mortared over. A steel pipeline would

cost approximately $203 per linear foot for material and construction.

OC10290 00: GOTO 0803 RDH3 24

6.2 Selection of Pipeline Materials

Several potential pipeline materials and their respective joint alternatives are evaluated in this

Expanded Pipeline Investigation Report. The selected pipeline material should be the one that

best meets the major concerns and design criteria important to the successful function of the

proposed pipeline. Table 1 shows a summary of the cost estimates for each of the pipeline

materials. Table 2 shows a relative comparison of the attributes of each of the pipeline materials.

Table 1 Summary of Pipeline Material Cost Estimates

Category

Pipe Material and JoiningPipe AnchorsGravel Foundation & PipeHandling

Total CostToal Unit Cost

UnitIfea

If

It

Solid HDPE36" OD

Qty

5100

22

5100

UnitCost$55

$5,000

$11

Total$280,500$110,000

$56,100

$446,600$88

Corrugated HDPE36" ID

Qty

51001275

5100

UnitCost

$40$50

$8

Total$204 000$63750

$40,800

$308,550$61

Reinforced Concrete36" ID

Qty5100

1275

5100

UnitCost$46$80

$13

Total

$234,600$102,000

$66,300

$402,900$79

Lined Steel Pipe37.875" OD

Qty

5100255

5100

UnitCost$90

$2,000

$13

Total$459,000$510,000

$66 300

$1,035,300$203

Table 2 Summary of Pipeline Material Attributes /

Pipe materialHDPE (solid wall)HDPE (Corrugated)PVCReinforced ConcreteSteel (CML&C)

Joint TypeButt- fused weldedGasketed bell & spigotGasketed bell & spigotGasketed bell & spigotWelded

ss>fRulfn}High

Moderate"" Lo$?

Cow

UVResistanceHigh CModerateLowHigh CHigh

Joint GasketLife

55^ CLowLowGooo^> x~m t-

Resistarice toFirearms

Hig2££> fLowLowffigrb (ffign

Construction^Difficulty

Moderatg3cLowLow"ModeraT&N /raoDsrate-'

Thermal.Ejpansierf

HighModeratetSv^J C"Cow

\Maintenance/(Adjustment

DifficultyLow) CTowModerateHigrp <[Moderate

StressIntensityat Joints

No7KT>LowKjfv^rale^

Moderate^None

The pipeline material that best meets the selection criteria is a solid wall HDPE pipeline. This

material has high flexibility; high UV resistance; high resistance to firearms; it is

straightforward to construct a pipeline with adequate thermal expansion accommodation; it is

easy to maintain; and has no stress intensity problems at the pipeline joints. One of the major

benefits of solid wall HDPE material is that, because the pipe joints are fusion welded, the

possibility of pipeline leakage is virtually eliminated.

OC10290 001 GOTO 0803 RDH3 25

7.0 Foundation Alternatives

7.1 Foundation Alternatives

7.1.1 Surface Installation with Soil Cover

A potential alternative for providing pipeline support is to place it on a suitable bedding material

layer directly on the ground surface, anchored with soil fill spaced along the alignment for

lateral support. Additional fill would be placed in areas of potential increases in stress (i.e., pipe

bends and changes in elevation). This is a common method for supporting HDPE pipelines for

landfill gas control across the surface of landfills. A schematic diagram of this alternative is

provided in Figure 5.

7.1.2 Trench and Cover

The trench and cover method is a second possible method for supporting the pipeline. In this

option, a trench would be excavated within the refuse that would extend to the underlying

bedrock. Soil would be placed in the excavation to bring it to pipeline grade. The pipe would

be placed in the trench and the trench backfilled with additional soil to the ground surface. A

schematic cross-section of this alternative is shown in Figure 6.

7.1.3 Foundation Systems

Foundation systems fall into two general categories: pier support and shallow support. A

complete evaluation and description of pier support options for support of the pipeline is

presented in Appendix C. A general description of pipeline foundation systems is presented

here.

OC10290 001 GOTO 0803 RDH3 26

7.1.3.1 Driven Pile Foundation System

This foundation system is the one originally suggested by EPA at the February 26, 2003

meeting. Piles are long, slender structural members that are prefabricated and driven into the

ground to dense soil or bedrock. Different pile materials are available (steel, timber and

concrete) for use in different settings. For the Sunrise Mountain Landfill, piles would be driven

through the refuse and come to rest on the underlying bedrock. The driven piles would be

subject to movement by lateral loads from potential shifting of buried waste. Therefore this

alternative is very likely to result in a structural failure, hi time, potential lateral loads caused by

waste consolidation could cause the pipeline to detach from the top of the piles.

Because we believe that a Driven Pile Foundation System has such a high likelihood of failure,

we have developed and evaluated a revised alternative called a Drilled Pier and Grade Beam

foundation. This alternative is less likely to experience long-term structural failure than the

Driven Pile Foundation System. Nevertheless, we have rejected the Drilled Pier and Grade

Beam foundation alternative for other reasons as discussed below.

7.1.3.2 Drilled Pier and Grade Beam System

Drilled piers are foundations that are constructed of concrete and reinforcing steel that is cast-in-

place in a shaft excavated with a drill rig. Within the limitation of common drilling equipment,

drilled pier shafts typically have diameters up to 72 inches and lengths up to 80 feet. Individual

foundation points can be supported by individual drilled piers, or by multiple piers connected

using a pier cap. A concrete grade beam or other supporting structure would be required to

continuously support the pipeline between foundation points. A schematic of this option is

presented in Figure 7. Appendix C provides a detailed discussion of this alternative. Based on

our preliminary analysis, the cost of the Drilled Pier and Grade Beam foundation is

approximately $4,972,000 not including the pipeline material.

OC10290 001 GOTO 0803 RDH327

7.1.3.3 Rock Ballast Support System

Another option under consideration is to construct the pipeline upon a foundation of rock and

gravel ballast material. Since the middle of the 19th Century, railroad lines have been supported

on foundations of adjustable ballast. These rail systems span thousands of miles in extreme

temperatures and have to remain within tight tolerances to keep a locomotive from derailing.

The proposed ballast layer beneath the pipeline would be a minimum of 6 inches thick, hi the

event that settlement of the landfill surface does occur, this system would allow the pipeline

grade to be adjusted as required by raising the pipeline with a forklift or jacking system and

adjusting the amount of ballast beneath the pipeline. The ballast would also permit surface

drainage to pass through it without significant flow resistance. A schematic drawing of this

option is presented in Figure 8.

To provide additional protection against differential settlement, the basic ballast configuration

shown in Figure 8 would be augmented using geo-grid reinforcement at key transitions between

natural soil and the soil cover over buried waste material. Geo-grid adds tensile and shear

strength to the soil substrate and will act to reduce possible surface manifestations of differential

settlement in treated areas. The geo-grid would be placed within a layer of engineered fill

beneath the ballast layer.

7.2 Technical Comparison of Foundation Alternatives

EPA has recently indicated that RSSN should include an alternative that accommodates the

potential for differential settlement, and allow the pipeline to be easily inspected for leaks.

Because of this latter concern, burying the pipeline will not be further considered as a viable

option.

There are fatal technical flaws associated with the implementation of a Driven Pile Foundation

System. These arises primarily because the piles would rest on the underlying bedrock and

would not be able to resist lateral loads. A Driven Pile Foundation System is not a feasible

option at the Sunrise Mountain landfill for the following reasons: 1) if settlement occurs, the

piles remain at a fixed vertical elevation ensuring that any possible settlement is expressed as

OC10290 001 GOTO 0803 RDH3 28

differential settlement; 2) if the waste mass experiences vertical settlement, the piers would be

subject to differential horizontal movement and could detach the piles from the pipeline; 3) this

support system makes long-term maintenance of the pipeline problematic; and 4) this system is

cost prohibitive and difficult to construct.

Also, piles cannot be driven into the Hermit Formation substrate due to its high material

strength. Although the design issues are formidable, and perhaps insurmountable, piers can be

installed into the bedrock by drilling into the rock. In response to EPA suggested foundation,

Exponent has developed the Drilled Pier and Grade Beam alternative. This alternative is less

likely to have long-term structural failure because the piers are actually drilled into bedrock

giving them resistance to potential lateral loading caused by buried waste materials. However,

this investigation still rejects the Drilled Pier and Grade Beam System for other technical

reasons: 1) the seismic design of the variable pier lengths and attachment methods for this

system is a major engineering undertaking that could delay project implementation for up to one

year; 2) drilling into bedrock would introduce significant amounts of water to the waste mass

during construction; 3) the interface between the piles and the waste material would create

preferential flow paths deep into the waste mass; 4) this system could be subject to potential

horizontal displacement; 5) this system would be difficult to maintain; and 6) this system is cost

prohibitive and difficult to construct.

In contrast, the Rock Ballast Support System, illustrated in Figure 8, addresses all of the

relevant design considerations for the pipeline system. The ballast provides a buffer against

differential settlement loads being applied directly to the pipeline (as would be the case in laying

the pipe directly on the surface of the landfill). The ballast system also allows the effects of

differential settlement to be rapidly and easily accommodated by adding or removing ballast

from the affected area. The ballast system permits ready inspection of the pipeline. The ballast

can also be shaped to cradle the pipe for lateral support and still accommodate movements due

to thermal expansion. The ballast system also readily accommodates surface drainage.

OC10290 001 GOTO 0803 RDH3 29

Exponent's proposal for providing additional pipeline support is to place the pipeline on a layer

of rock and gravel ballast that can be adjusted to accommodate for possible long-term settlement

of the landfill surface (Figure 9). Surface water off the eastern slope would be allowed to sheet

flow to the pipeline and then pass through drainage culverts and/or filter through the rock

bedding to continue its westerly movement to the top deck channel (Channel No.l). There are

four locations along the eastern perimeter where the flow from the eastern slope is sufficiently

concentrated as to require a defined crossing location (swale). At these four locations, drainage

crossing points will be designed into the Rock Ballast Support System.

OC10290 001 GOTO 0803 RDH3 30

8.0 References

Bray, J.D. and Rathje, E.J., 1998. Earthquake-Induced Displacements of Solid-Waste Landfills:

Journal of Geotechnical and Geoenvironmental Engineering, p. 242-253.

Coduto, D.P. and Huitric, R., 1990. Monitoring Landfill Movements Using Precise Instruments:

Geotechnics of Waste Fills - Theory and Practice, ASTM STP 1070, American Society for

Testing and Materials, Philadelphia, p. 358-370.

Desert Research Institute (DRI), 2003. Western Regional Climate Center,

http://www.wrcc.dri.edu/.

Dunn, J., 1995. Design and Construction of Foundations Compatible with Solid Wastes:

Proceedings of the 1995 Conference of the Geotechnical Engineering Division of ASCE,

Special Publication No. 53, p. 139-159.

Exponent, Inc., 2003a. Stormwater Protection for the Sunrise Mountain Landfill, Clark County,

Nevada: unpublished consultant's report, 27 p. (January 24).

Exponent, Inc., 2003b. Cover Plan for the Sunrise Mountain Landfill, Clark County, Nevada:

unpublished consultant's report, 27 p. (June 19).

Exponent, Inc., 2003c. Geotechnical Engineering and Engineering Geologic Report, Proposed

Stormwater Detention Basin, Sunrise Mountain Landfill, Clark County, Nevada: unpublished

consultant's report, 59 p. (June 27).

Frankel, A.D., Mueller, C.S., Barnhard, T., Perkins, D.M., Leyendecker, E.V., Dickman, N.,

Hanson, S., and Hopper, M., 1996. National Seismic Hazard Maps, June 1996, Documentation:

U.S. Geological Survey Open-File Report 96-532 ,100 p.

Frankel, A.D., Petersen, M.D., Mueller, C.S., Haller, K.M., Wheeler, R.L., Leyendecker, E.V.,

Wesson, R.L., Harmsen, S.C., Cramer, C.H., Perkins, D.M., and Rukstales, K.S., 2002.

OC10290 001 GOTO 0803 RDH331

Documentation for the 2002 update of the National Seismic Hazard Maps: United States

Geological Survey, Open-File Report 02-420.

Marques, A.C.M., Filz, G.M., and Vilar, O.M., 2003. Composite Compressibility Model for

Municipal Solid Waste, Journal of Geotechnical and Geoenvironmental Engineering, vol. 129,

no. 4, p. 372-378.

Matasovic, N., Kavazanjian, E., Jr., Augello, A.J., Bray, J.D., and Seed, R.B., 1995. Solid

Waste Landfill Damage Caused by 17 January 1994 Northridge Earthquake: in: Woods, Mary

C., and Seiple, Ray W., Eds., The Northridge, California Earthquake of 17 January 1994,

California Department of Conservation, Division of Mines and Geology Special Publication No.

116, Sacramento, California, pp. 43-51.

Orr, W.R., and Finch, M.O., 1990. Solid Waste Landfill Performance During the Loma Prieta

Earthquake: Geotechnics of Waste Fills - Theory and Practice, ASTM STP 1070, American

Society for Testing and Materials, Philadelphia.

Park, H.I. and Lee, S.R., 2002. Long-Term Settlement Behavior of MSW Landfills with

Various Fill Ages. Waste Management & Research, vol. 20, no. 3, p. 259, June.

Pierce, J., 2001. Commercial Development of Closed Landfills: Case Studies and

Technical/Regulatory Issues: Solid Waste Association of North America Sixth Annual Landfill

Symposium, San Diego, California, June 18, p. 227.

Pischer, D. and Parisi, F., 2002. Home Depot Builds Atop and Old Oregon Landfill, Long-term

Benefits Outweigh Challenges of Building on a Brownfield: Environmental Outlook, July 25,

http://vvww.dic.com/news/en/] 1135649.html.

SCS Engineers (SCS), 2001. February 2001 Draft, Final Historic Assessment Report, Sunrise

Mountain Landfill - Las Vegas, Nevada. February 13.

OC10290 001 GOTO 0803 RDH3 32

Taylor, A., 1998. Award Winning Foundation Built Over Landfill: Lowney Associates,

http://www.lowney.com/press 'news.shtml.

United States Environmental Protection Agency (USEPA), 1995. RCRA Subtitle D (258)

Seismic Design Guidance for Municipal Solid Waste Landfill Facilities, April.

OC10290 001 GOTO 0803 RDH3 33

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Figure 5: Schematic Diagram Showing Pipeline SurfaceInstallation with periodic anchoring Soil Cover

Figure 6: Schematic Diagram Showing Cut and CoverMethod of Pipeline Installation

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PLAN

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TYPICAL SPACING

200 TO 400 FEET

GROUND SURFACE

36 inch HDPE (Solid Wall)

ANCHOR STRAP

BALLAST

CONCRETE ANCHOR

SECTION

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Schematic Diagram Showing Layout andAnchoring for HDPE Solid Wall Pipeline

Sunrise Mountain Landfill Date: 08/01/03

Figure9

Appendix A

Previous Investigations

Appendix A: Previous Investigations

SCS Engineers, Inc. (SCS) performed several field investigations at the Sunrise Mountain

Landfill, including the area covered by Figure A of the main text. This Appendix contains the

logs of SCS borings CB-4, CB-6, CB-10 and CB-11, which were provided to Exponent by

Republic Services of Southern Nevada, Inc. The SCS borings reported herein were performed

between January and July, 2000.

OC10290 001 GOTO 0703 RDH1 A-l

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JOB NUMBER: 109900701

REMARKS Borehole was logged from auger cuttings Location N 18206E 15057

Description

(0 - 3 5 ft } Light brown, Silty medium to fine SAND and GRAVEL,dry

(3 5 - 33 ft ) Waste, paper, light brown, dty

(5 ft ) Dark brown/Hack

(7 ft ) Very black gravel

(1 0 - 1 5 ft ) Black, paper, metal, wood, "fluff", slight odor, dry

(15 - 20 ft } Black, paper, metal, wood, "fluff", cloth, slight odor, dry

(20 - 25 ft ) Black, well decomposed debns and waste, majority ewood and paper, slight odor, slightly moist

Comment

Cover 3 5 ft thick

Air Monitoring at 5 ftCH4 LEL = 0%CH4 ppm = 0CH4 VOL = not recordedO2 VOL = 20 9%H2S ppm = 00

CO ppm = not recorded

(15 ft ) No change in air monitonngreadings

Air Monitoring at 18ftCH4ppm = 120(18 ft ) No change in other air monitonngreadings

Moderate to strong odor 20 to 30 ft

Drillmg Company GES

Drilling Method HSA

Logged By J. Watkins_>

Date Started 1/17/00 Time Started 10:15 pm 1

Date Ended 1/17/00 Time Ended 11:10 pm

Boring Depth 38 ft

I

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SCS ENGINEERS

^en ,4zonhaSSaSU'le1°5B BORING NUMBER: CB-4 Page 2 of 2

Sunrise Mountain LandfillClark County, Nevada

JOB NUMBER- 1099007.01

Depth

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Description

(30 - 35 ft ) Black, wood and paper debns, moderate odor, slightlymoist

(33 ft) Some gravel coming up(33 - 38 ft) Red Sandstone BEDROCK

(33 - 34 ft) Light brown to reddish SAND

End bormg at 38 ft

Comment

(30 ft ) No change m air monitonngreadings

Air Monitoring at 33 ftCH4 ppm = 40No change in other air monitoringreadings (33 ft)

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1 S C S ENGINEERS ^ •gJTgidk rii MJIslthtiittihfaB2702 North 44th street. Su.te lose BORING NUMBER: CB-6 Page 1 of 2Phoenix, Arizona 85008 °

Sunrise Mountain LandfillClark County, Nevada

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JOB NUMBER: 1099007.01

REMARKS Borehole was logged from auger cuttings Location N18971E16086

Description

(0 - 3 ft ) Light brown, Sandy SILT, dry

(3 - 30 ft ) Waste, dark gray, rags, plastic, wire, paper, etc , moist

(10 ft ) Waste, metal, rags, plastic, paper, medical waste, dark gray,most, strong odor

(14 ft ) Stiff, wood, medical waste, paper, plastic, dary gray, moist,strong odor

(24 - 25 ft ) Soft, moist (it appears like a layer of cover soil)

Comment

Air monitoring readings taken by time asopposed to depth for this confirmationboringAir Monitoring at 10 00 A MCH4 LEL = not recordedCH4 ppm = 0CH4 VOL = not recordedO2 VOL = 20 9%H2S ppm = 0CO ppm = not recorded

Air Monitoring at 10 15 A MCH4 LEL = not recordedCH4 ppm = 60CH4 VOL = not recorded02 VOL = 20 8%H2S ppm = 0CO ppm = not recorded

Air Monitoring at 10 30 A MCH4 LEL = not recordedCH4 ppm = 0CH4 VOL = not recordedO2 VOL = 20.8%H2S ppm = 0CO ppm = not recorded

Drilling Company GES

iDrilling Method HSA

Logged By A. Ramos

Date Started 1/28/00 Time Started 10:00 am

Date Ended 1/28/00 Time Ended 11:00 am

Boring Depth 30 ft.

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(26 ft ) Waste, paper wood, plastic, dark gray cuttings, strong odor

(30 0 ft ) Drill bit has red dirt, also the hammer has red dirt, appearsto be red BEDROCK

End bormg at 30 ft

-

Comment

Air Monitoring at 10 45 A MCH4 LEL = not recordedCH4 ppm = 0CH4 VOL = not recordedO2 VOL = 20 9%H2S ppm = 0CO ppm = not recorded

—

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ISCS ENGINEERS M CONFIRMATION BORING LOG

fhlTA^Sf"''6 "** BORING NUMBER: CB-1 0 Page 1 of 1

Sunrise Mountain LandfillClark County, Nevada

Depth

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JOB NUMBER: 1099007.01REMARKS Location N19270. E16052

Description

(0 1 5 ft ) GRAVEL with Silty SAND, red, native to area placed ascover matenal, dry, no odor al 8 in

(1 5 - 16 ft ) Waste, dry, consisting of paper, wood, and plastic

Light odor

(10 ft ) Waste, dry, wood, plastic, and glass

(1 6 - 1 8 ft ) Red, Silty SAND with Gravel, loosely compacted, somewaste mixed in, couldVe been interim cover, light odor

(18 - 24 ft ) Dry municipal waste, plastic, wood, and glass

(20 ft ) Municipal waste, dry, wood, paper, plastic, metal, and glass

(24 - 24 5 ft ) Contact with Silty SAND, consolidated (BEDROCK')bndboringat245ti

Comment

Air Moratonng at 8 mCH4 La = 0%CH4 ppm = not recordedCH4 VOL = not recordedO2 VOL =20 9%H2S ppm = 00CO ppm = 00

Air Morotortng at 5 ftCH4La = 0%CH4 ppm = not recordedCH4 VOL = not recordedO2 VOL =20 9%H2S ppm =00CO ppm = 00

Air Monitoring at 16-17 ftCH4La=0%CH4 ppm = not recordedCH4 VOL = not recordedO9 VOI — Of\ Q°/\J£. VvJL — tU a /o

H2S ppm = 00CO ppm = 00

_

Drilling Company West Haz-Mat

Drilling Method Geoprobe

Logged By D. ReeveV- j

Date Started 7/7/00 Time Started 8:00 am

Date Ended 7/7/00 Time Ended 8:35 am

Boring Depth 24.5 ft

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Sunrise Mountain Landfill JOB NUMBER: 1099007.01Clark County, Nevada REMARKS Location Naoiss, eieoss

Depth

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6-

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Description

(0 1 n ) Dry, red, Silty SAND with Gravel and some Cobbles, covermaterial, no odor at 7 in

(1 - 28 5 ft) Waste

(2 ft ) Municipal waste with paper, wood, and glass

(10 ft } Dry, municipal waste consisting of wood, paper, plastic,some metal and glass

(15 n } No odor

(20 ft ) Dry. municipal waste consisting of paper, wood, glass, andplastic

(24 and 25 5 n ) No odor

Comment

Air Monitoring at 7 inCH4 LEL = 0%CH4 ppm = not recordedCH4 VOL = not recordedO2 VOL = 20 9%H2S ppm = 00CO ppm = 00

Air Monitoring at 15ft-CH4 LEL = 0%CH4 ppm = not recordedCH4 VOL = not recordedO2 VOL = 20 9%H2S ppm = 00CO ppm = 00

Air Monitoring at 24-25 5 ftCH4 LEL = 0%CH4 ppm = not recordedCH4 VOL = not recordedO2 VOL = 20 9%H2S ppm = 00CO ppm = 00

Dnlling Company WestHaz-Mat Date Started 7/6/00 Time Started 1:15 pm

Drilling Method Geoprobe * Date Ended 7/6/00 Time Ended 2:1 Opm

Logged By D. Reeve Boring Depth. 29 ft

III

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PhS:x°tizonaSS8SUile "** BORING NUMBER: CB-1 1 Page 2 o. 2

Sunrise Mountain Landfill JOB NUMBER: 1099007.01Clark County, NevadaDepth

w

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- 28

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; 32-

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Description

(28.5 - 29 ft.) Silty SAND (red), consolidated, free of municipalwaste, bedrockEnd of boring at 29 ft.

**

Comment

--

r

Appendix B

Concrete Pipe Load TestInvestigation

www.C-LineProducts.comStyle #70568 1-888-860-9120

UNSCANNABLE MEDIA

To use the unscannable media document(s),contact the Superfund Records Center.

Unscannable media - parent

Appendix C

Exponent's Evaluation ofDrilled Pier with Grade BeamSupport System for thePipeline

Appendix C: Exponent's Evaluation of Drilled Pier withGrade Beam Support System for the Pipeline

Introduction

In a letter and a "Technical Concern Memorandum" dated June 27, 2003, the United States

Environmental Protection Agency (EPA) Region 9 raised concerns regarding the proposed

pipeline of the Controlled Flow Plan which would protect the Sunrise Mountain Landfill from

stormwater. This Appendix evaluates the use of drilled pier foundations for support of the

pipeline over the landfill. The following sections describe types of foundation systems, deep

foundation types and uses; a deep foundation system to support the pipeline, and difficulties

associated with the use of a deep foundation system.

Foundation Systems

Foundation systems can be divided into two general categories - shallow foundations and deep

foundations. Shallow foundations have been used successfully to support facilities at landfills

elsewhere. Shallow foundations include ballast systems, conventional spread footings,

reinforced concrete mats, and column footings tied together with a system of grade beams.

Shallow foundations are typically used to support infrequently loaded structures (i.e., wood

framed construction, rail systems, etc.) that are resistant to differential settlements. Deep

foundations are typically used to support structures that are continuously or more heavily loaded

(i.e., commercial buildings, factories, etc.) and are less resistant to differential settlements.

However, Dunn (1995) indicates that many structures can be constructed on shallow

foundations if there is the abiliu to adjust the foundation levelness.

OC10290 001 GOTO 0803 RDH3 p i

Description of Deep Foundation Systems

Deep foundations transmit surface loads to dense soil or bedrock at depths significantly below

the ground surface. Deep foundations are typically used instead of shallow footings in a variety

of circumstances. These include conditions where surficial soils are too weak to support a

shallow foundation, instances where a shallow foundation would be subject to scour, situations

where a foundation must pass through water, in cases when large uplift and/or large lateral

capacity is required, or when future excavation is planned adjacent to the foundation that could

undermine its structural integrity, hi the current application, EPA's suggested intent is to

support the pipeline on a deep foundation system extending to bedrock beneath the landfill to

mitigate the alleged effects of possible refuse settlement under the pipeline alignment.

Deep foundation systems fall into two general categories, driven piles and drilled piers. Piles

are long, slender structural members that are prefabricated and driven into the ground to dense

soil or bedrock. Piles can be constructed of steel, timber, or concrete and typically range in

diameter from 6 to 36 inches. Pile lengths range from approximately 20 feet to over 150 feet.

The type of pile used in a particular application is typically selected on the basis of applied

loads, required diameter, required length, local availability of materials, chemical compatibility,

and anticipated driving conditions (some piles cannot tolerate hard driving). Piles can be driven

alone or in groups connected through the use of a concrete pile cap or grade beam.

Steel piles are typically used in situations where a large capacity pile is required, hard driving

conditions are expected, the subsurface is non-corrosive, and large tensile forces (i.e., uplift) are

anticipated. Timber piles are typically used to support low to medium loads because they

cannot sustain high driving stresses. Precast concrete piles are typically used in situations where

load transfer occurs through skin friction (rather than through end bearing capacity) because it is

difficult to adjust their length by splicing or cutting. Hence, they have much greater utility in

conditions where a uniform pile length is desirable (such as a deep, uniform supporting

stratum).

Drilled piers or cast-in-place piles are similar to piles, but instead of being driven into the

ground, they are njade of concrete that is cast in a shaft excavated with a drill rig. Typical

OC10290 001 GOTO 0803 RDH3 p ~

drilling rigs are capable of drilling shafts up to 72 inches diameter and 80 feet deep. Typical

drilling bits include:

• Flight augers (typically used in most soils and soft rock)

• Bucket augers (useful in loose sands)

• Core barrels (cuts a circular slot creating a removable cylindrical core, useful

in hard rock, but requires the use of water or drilling fluid to remove cuttings)

• Multiroller bits (used in hard rock, but requires the use of water or drilling

fluid to advance the auger)

hi addition to providing vertical support, deep foundation systems that are anchored sufficiently

into a sound support stratum also provide resistance to lateral loads resulting from earthquakes,

wind loads, hydro-dynamic forces, or lateral soil movement from differential settlement.

Drilled Pier and Grade Beam Foundation Alternative

A drilled pier and grade beam foundation system for the pipeline would lead to the

accommodation of the lateral loads (i.e., seismic, wind, and lateral movement of the landfill)

and downdrag loads resulting from settlement of refuse. Firm Hermit Formation bedrock

underlies the refuse at the Sunrise Mountain Landfill. Based on the strength properties of the

Hermit Formation obtained during the dam investigation, any attempt to drive a steel, timber, or

concrete pile into this material would likely result in severe damage to the pile tip or buckling of

the pile. The method to construct a functional deep foundation system in this setting is to use a

system of drilled piers that penetrates the Hermit Formation bedrock.

A drilled pier system could support the pipe loads individually or through a group connected by

a pier cap or grade beam. Pier diameters could range from approximately 36 inches to 48

inches, depending on the possible lateral load requirements. At a minimum, the drilled piers

would penetrate at least 10 feet into solid, unweathered bedrock. A bucket auger or flight auger

would be requiredtto drill through the refuse material and a multiroller bit or core barrel would

OC10290 001 GOTO 0803 ROH3 C-3

be required to drill into bedrock. The shaft would need to be cased through the refuse to prevent

the sidewalls from caving, and water or drilling fluid would be required to advance the auger

when drilling into bedrock. For end-bearing shafts, it is common practice to inspect the bottom

of the excavation to verify that the concrete-bedrock contact is sufficiently free of loose material

to transmit the expected loads to bedrock.

Difficulties Associated with a Drilled Pier Supported Pipeline

There are several difficult design issues associated with the use of a pipeline supported with

drilled shafts that support the exploration of other foundation options. These issues include:

• Resistance of loads

• Downdrag loads

• Constructability

• Corrosion

• Environmental protection

• Surface drainage considerations

• Inappropriate use of drilled piers in landfills

These issues are discussed in the following sections.

Resistance of Loads

From the perspective of load resistance, the use of a drilled pier foundation to support the

pipeline at the Sunrise Mountain Landfill presents two major difficulties, resistance to lateral

movement of the landfill and resistance to seismic forces. Lateral movement occurs because the

waste is located in a valley with inclined sidewalls and varying refuse thickness. The amount of

settlement is greatest in the center of the valley, where the refuse thickness is largest, and least

OC10290 001 GOTO 0803 RDH3 C-4

near the valley sidewalls where the refuse is at its thinnest. Because the amount of refuse

settlement is proportional to the thickness and the refuse composition is not homogeneous, an

uneven settlement profile results. This uneven settlement profile causes lateral stresses to

develop between the center and edges of the valley. This is represented schematically in Figure

C-l. When sufficient settlement has occurred, these lateral stresses overcome the resisting

forces of the refuse and the refuse and movement occurs.

Evidence for ongoing lateral movement of the landfill is provided by the presence of tension

cracks at the bedrock-waste interface along the Eastern Perimeter, where the waste is "pulling"

away from the canyon wall. The amount of lateral movement that occurs depends upon the total

amount of settlement, the inclination of the landfill-rock contact, and the shear strength of the

refuse. The amount of lateral movement and the resulting lateral loads are difficult to quantify

because of the uncertainty in the controlling parameters. However, the amount of lateral

movement could range from a few inches to a few feet. A large structural section would likely

be required to resist these forces, the magnitudes of which are difficult to quantify.

The second difficulty with supporting lateral loads is seismic design as represented

schematically in Figure C-2. Due to the various depths to bedrock along the pipeline alignment,

shaft lengths ranging from 10 to 25 feet would be necessary. These different shaft lengths have

different natural periods, so in a seismic event they would behave quite differently, causing

large loads to be introduced into the pipeline due to the differential shaking. In order to

complete the design of a foundation system that would elevate the pipeline an average of 5 feet

above the landfill cover, it would result in a delay of up to one year in the completion of the

stormwater protection plan for the landfill.

Downdrag Loads

Downdrag loads are imposed on the deep foundation system when refuse settlement exceeds the

downward movement of the foundation, as is expected to be the case for this project. These

downdrag loads are very difficult to assess without expensive large-scale pull out tests, and their

estimation is complicated by the prolonged time frame over which refuse settlement occurs at

OC10290.001 GOTO 0803 R0H3 p <-

landfills. Dunn (1995) indicates that in certain instances downdrag loads can be sufficiently

large that the entire capacity of the foundation may be required to resist them. These downdrag

loads are also referred to as negative skin friction and impose uplift forces on the foundation and

tensile stresses within the pier, which require more rebar (and therefore additional cost) to resist.

To resist these uplift forces, the foundation has to be designed with sufficient uplift capacity,

which occurs from the dead weight of the foundation and the friction between the side of the

foundation and supporting material (bedrock).

Constructability

The construction of drilled pier foundations that penetrate the landfill is a complex and difficult

construction problem. If the waste material collapses as the piers are drilled, then steel casing

would have to be inserted in order to prevent this.

Another issue is that the use of a drilling fluid would be necessary, and even in a cased hole,

would introduce significant amounts of water into the landfill. The introduction of this much

water into the waste mass could speed biodegradation and thus promote biodegradation and

possible settlement, and potentially could set the stage for a leachate release to groundwater.

Lastly, the base of the drilled pier must be inspected prior to pouring concrete to assure that the

drilled pier rests on competent material. Sending a person down the hole, even while cased,

increases the risk of exposure to landfill gas, leachate, and poses a confined space risk.

Corrosion

The decay of refuse typically results in an environment that is corrosive to concrete. Landfill

environments are typically high in acids and sulfates, which corrode concrete. Special

mitigation methods are required to protect concrete from corrosion in a subsurface landfill

environment.

Potential mitigation methods for concrete include:

OC1C290 001 GOTO 0803 RDH3 p r

• Use of Type II or V cement

• Increase concrete cover over steel reinforcement

• Increase the strength of the mix

• Design mix with low water permeability and high density

• Epoxy coat steel reinforcement

While several mitigation methods are provided, a special concrete mix would be required to

construct a foundation system that would survive the specialized conditions of a landfill.

Similar concerns exist for driven steel piles, for which cathodic protection or encasement would

be required, again significantly increasing construction costs.

Environmental Protection

The use of a drilled pier through a landfill compromises the integrity of the final cover. Drilling

into the bedrock provides additional avenues for landfill gas and leachate to migrate into the

vadose zone. Further, the waste-pier interface provides an avenue for the escape of landfill gas

and infiltration of surface water. Large voids would develop adjacent to the pier that would be

created from slow lateral movement (creep) of the refuse as described above, as well as in

response to seismically-induced vibration of the piers.

Surface Drainage Considerations

The construction of a deep foundation system consisting of drilled piers linked together with a

concrete grade beam could adversely affect surface drainage. A schematic diagram of the

Drilled Pier and Grade Beam support system is shown in Figure 7 of the main report. The

interface between the buried waste materials and the pier would create a preferential flow path

for surface water drainage to penetrate deep into the waste mass.

OC10290 001 GOTO 0803 RDH3 p -,

Drilled Piers are not Used in Landfills

The technical literature was searched for case histories involving the use of deep foundations in

landfills to determine if drilled piers are commonly used to support structures over a landfill.

Exponent could not identify any situation where a deep pier foundation was used to support a

stormwater drainage pipeline that crossed a landfill. Our research did find, however that two

Home Depot stores were constructed over landfills using driven pile foundations. These efforts

were part of Brownfield Development Projects (Pischer et al, 2002 and Taylor, 1998). One

Home Depot was supported by steel H-piles driven through approximately 135 feet of refuse, to

penetrate approximately 10 feet into the underlying sand deposits. Taylor (1998) indicates that

they chose a pile foundation so refuse would not have to be hauled off and the amount of

methane gas released would be minimized. The second Home Depot store was supported by

closed end steel pipe piles driven through approximately 30 to 40 feet of refuse (Pischer et al.,

2002). Both of these cases involve the installation of driven piles through waste into sand and

are therefore not comparable to the Sunrise Mountain Landfill condition where the waste is

underlain by bedrock.

Pierce (2001) summarizes the development of several closed landfills. Three of the landfills

were developed into commercial buildings that were supported on steel or concrete piles. The

other five developments that Pierce (2001) describes were supported on shallow foundations,

but none were supported on drilled piers. Dunn (1995) indicates that driven piles are nearly

always used in landfills to support larger structures. The reasons he provides are:

• Refuse is prone to caving and casing must be used during drilling (which

increases construction costs)

• Large volumes of refuse are generated during drilling (which must be

disposed of)

• Refuse that comes out of old landfills may contain high concentrations of

toxic substances

OC10290 001 GOTO 0803 RDH3 ,-, o\-,-O

• Excavated refuse may present a health and safety concern to construction

personnel

Excavated refuse may present an odor nuisance

An estimate of probable cost for the Drilled Pier and Grade Beam support system is

attached to this appendix.

References

Dunn, J., 1995. Design and Construction of Foundations Compatible with Solid Wastes:

Proceedings of the 1995 Conference of the Geotechnical Engineering Division of ASCE,

Special Publication No. 53, p. 139-159.

Pierce, J., 2001. Commercial Development of Closed Landfills: Case Studies and

Technical/Regulatory Issues: Solid Waste Association of North America Sixth Annual Landfill

Symposium, San Diego, California, June 18, p. 227.

Pischer, D. and Parisi, F., 2002. Home Depot Builds Atop an Old Oregon Landfill, Long-term

Benefits Outweigh Challenges of Building on a Brownfield: Environmental Outlook, July 25,

http://www.dic.com/ncws/cn/l 1135649.html.

Taylor, A., 1998. Award Winning Foundation Built Over Landfill: Lowney Associates,

http: //www.lou ncy.com/prcss/ncws.shtml.

OC10290 001 GOTO 0803 RDH3 C-9

Ground Surface after Settlement

Original Ground Surface

refuse settlement

Figure C-l: Lateral Movement of Waste Fills

Pipeline will experience complexcompression, tension, and shear forcesin response to out-of-phase movement

of adjacent piers

Short pier resonates withshort period in response toground motions

Bedrock

Long pierresonates with longperiod in responseto ground motions

Figure C-2: Seismic Excitation of Deep Foundation System

Exponent Inc 320 Goddard Suite 200 Irvine CA 92618

Sunrise Mountain LandfillEstimate of Probable Construction Costs for the Drilled Pier & Grade Beam Support System

ItemNo. Description Quantity Unit Unit Cost Cost

12345

Pier DrillingReinforced Concrete pile capReinforced Concrete PierGrade BeamWaste removal from drilled holeSubtotalEngineering/ ContingenciesTotal Probable Construction Cost

130130

1,3504,500

900

25%-t-/-

eaeacycycy

$15,60000$550 00$40000$300 00

$1750

$2,028,000 00$71,50000

$540,000 00$1,350,00000

$15,75000$4,005,250 00

$966.700 00$4,971,950.00

Unit costs shown are an opinion of probable cost Actual costs may vary due to local availability of material,actual quantities rather than estimated quantities of material required, time of year of construction,and other variables beyond our control

Waste removal costs assume no hazardous material handling is required

OC10290 001 GOTO 0803 RDH3 C-12

T ilOri PTlt PrOJ6C* NameL^^f-^f ICC

Failure Analysis Associates* Author -J, £- , £-V <-^~

Project Number

Date ~Jlt-'^P3 Page / of JL

-J&7~ ('*-{

TV P.

QMS 10 _ c Exponent 2003

OC10290 001 GOTO 0803 RDH3C-13