vvEPA
echnology
I upport
rojeot
United States
Environmental Protection
Agency
Office of Solid Waste and
Emergency Response
Washington, DC 2046O
Office of Research and
Development
Washington, DC 2O4GO
Superfund
EPA/540/R-92/073
October 1992
Technical Guidance
Document
Construction Quality
Management for Remedial
Action and Remedial Design
Waste Containment Systems
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EPA/540/R-92/073
October 1992
Technical Guidance Document
CONSTRUCTION QUALITY MANAGEMENT FOR
REMEDIAL ACTION AND REMEDIAL DESIGN
WASTE CONTAINMENT SYSTEMS
by
Gregory N. Richardson
Hazen and Sawyer, P.C.
Raleigh, North Carolina 27607
Contract No. 68-CO-0068
Project Officer
Robert Landreth
Waste Minimization, Destruction & Disposal Research Division
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
Superfund Technical Support Center for Engineering and Treatment
Technology Innovation Office
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
Washington, D.C. 20460
In Cooperation With
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
^gg> Printed on Recycled Paper
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DISCLAIMER
The preparation of this document has been funded wholly by the United
States Environmental Protection Agency. It has been subjected to the Agency's
peer and administrative review, and has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
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FOREWORD
Today's rapidly developing and changing technologies and industrial
products and practices frequently carry with them the increased generation of solid
and hazardous wastes. These materials, if improperly dealt with, can threaten
both public health and the environment. Abandoned waste sites and accidental
releases of toxic and hazardous substances to the environment also have important
environmental and public health implications. The Risk Reduction Engineering
Laboratory assists in providing an authoritative and defensible engineering basis for
assessing and solving these problems. Its products support the policies, programs,
and regulations of the U.S. Environmental Protection Agency; the permitting and
other responsibilities of State and local governments; and the needs of both large
and small businesses in handling their wastes responsibility and economically.
This document provides design guidance on final cover systems for
hazardous waste landfills and surface impoundments. We believe that the final
cover, if properly designed and constructed, can provide long-term protection of
the unit from moisture infiltration due to precipitation. The cover system presented
herein is a multilayer design consisting of a vegetated top layer, drainage layer, and
low-permeability layer. Optional layers which may be required for site-specific
conditions are also discussed. Rationale is provided for the design parameters to
give designers and permit writers background information and an understanding of
cover systems.
This document is intended for use by organizations involved in permitting,
designing, and constructing hazardous and non-hazardous waste land disposal
facilities and in remediating uncontrolled hazardous waste sites.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
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ABSTRACT
This Technical Guidance Document is intended to augment the numerous
construction quality control and construction quality assurance (CQC and CQA)
documents that are available for materials associated with waste containment systems
developed for Superfund site remediation. In general, the manual is oriented to the
remediation project manager (RPM) who must administer these projects.
This document reviews the significant physical properties associated with the
construction materials used in waste containment designs and reviews the sampling
and acceptance strategies required for Construction Quality Management. The first
chapter reviews the minimum Federal regulatory requirements for waste containment
systems. Key elements of these systems are identified. The second chapter reviews
the key physical properties and conformance tests required to verify these properties.
The third chapter reviews sampling methods and acceptance criteria that are used to
verify key physical properties during construction.
IV
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TABLE OF CONTENTS
Page No.
DISCLAIMER ...." ii
FOREWORD ......' iii
ABSTRACT . , iv
LIST OF FIGURES . . . . . . . .viii
LIST OF TABLES ix
SECTION 1.0 Construction Quality Management
1.1 CQA/CQC Objectives 1-2
1.2 Regulatory Waste Containment Systems/Objectives ......... 1-5
Surface Impoundments (40 CFR 264 Subpart K) . 1-5
Waste Piles (40 CFR 264 Subpart L) . 1-5
Landfills (40 CFR 264 Subpart N) 1-9
On-site Waste Isolation (40 CFR 300 App.D) .......... 1-9
Caps 1-9
Horizontal Barriers .1-9
Vertical Barriers . 1-12
1.3 Components and Elements
in Waste Containment Systems 1-12
1.4 References 1-16
SECTION 2.0 Summary of Construction Elements and Key Properties
2.1 Hydraulic Barriers . 2-1
Geomembranes 2-1
Geomembrane Interlocking Panels 2-3
Grouts 2-4
Bentonite Products 2-4
Bentonite Amended Soil. 2-5
Geosynthetic Clay Liner (GCL) 2-5
Bentonite Slurries . 2-5
Concrete/Bentonite Slurry 2-6
Compacted Clay Liners (CCL) . . 2-6
v
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TABLE OF CONTENTS (continued)
Page No.
2.2 Hydraulic (Both Liquid and Gas)
Conveyances 2-7
Natural Drains and Collectors 2-7
Geosynthetic Drain/Collector 2-9
Plastic Pipe 2-9
Sumps 2-10
Pumps 2-10
2.3 Filters 2-11
Sand/Gravel Filter 2-11
Geotextile Filter 2-11
2.4 Erosion Control 2-13
Vegetation and Topsoil 2-13
Hardened Layer . . 2-15
Asphalt Cap 2-15
Concrete Cap 2-15
Rip-Rap Cap 2-16
2.5 Protective Layers 2-16
Biotic Layer 2-16
Geotextile 2-18
Soil Protective Layer 2-18
2.6 Earthwork 2-18
Structural Fill 2-20
Soil Bedding Layer 2-20
Geotextile or Geogrid Bedding Layer 2-20
2.7 References 2-20
VI
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TABLE OF CONTENTS
Table No.
Page No.
SECTION 3.0 Field Sampling Strategies
3.1 Delineating the Area or Lot Being Tested 3-2
3.2 Determining the Number of Sample Locations .............. 3-2
Sample Density Method . 3-2
Error of Sampling Method 3-4
Sequential Sampling 3-7
3.3 Selection of Sample Locations 3-9
100% Sampling 3-TO
Judgmental Sampling ......, . 3-11
Fixed Increment Sampling .'...' ' . 3-13
Random Sample Selection 3-14
Sample Random Sampling 3-15
Stratified Random Sampling 3-17
3.4 Acceptance/Rejection Criteria . 3-19
No Defects Criteria , . 3-19
Statistical Value Criteria 3-17
Maximum Number Defects Criteria 3-24
Assigned Variable Monitoring (Control Charts) 3-24
3.5 References 3-30
APPENDICES
A - Waste Containment Element Test Methods A-1
B - Standardized Test Methods-
Organization Address List B-1
C - Sample Specification for Geomembrane
with Sampling, Testing and Acceptance Criteria C-1
vii
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List of Figures
Fia. No.
Page No.
1-1 Surface Impoundment Used for Storage 1-6
1-2 Cover System for Surface Impoundment/Landfill Closure 1-7
1-3 Waste Pile Used for Interim Waste Storage 1-8
1-4 Landfill Used for Hazardous Waste Storage 1-10
1-5 Hardened Closure System 1-11
1-6 Vertical Barrier System '..'..' 1-13
3-1 Delineation and Measurement of Sample 3-3
3-2 Number of Samples - Error of Sampling Method 3-6
3-3 Number of Samples - Sequential Sampling 3-8
3-4 Geomembrane Panel and Seam Identification 3-12
3-5 Geomembrane Seam Repair Log 3-12
3-6 Normal Distribution of Data 3-20
3-7 Control Chart Table 3-27
3-8 Control Chart to Identify Outliers - Failure Ratio .' 3-28
3-9 Control Chart - Subgroup Sensitivity 3-29
VIII
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List of Tables
Table No.
Page No.
1-1 Waste Containment Components and Elements 1-15
2-1 Barrier System Element Testing/Inspection 2-2
2-2 Hydraulic Conveyance System Element Testing/Inspection 2-8
2-3 Filter System Element Testing/Inspection 2-12
2-4 Erosion Control Element Testing/Inspection 2-14
2-5 Protection Layer Element Testing/Inspection . . . 2-17
2-6 Earthwork Element Testing/Inspection 2-19
3-1 Examples - Sample Density Method 3-5
3-2 Portion of Random Number Table , . 3-16
3-3 Example of Random Sample Selection from 25 Items 3-18
3-5 Recommended Percentage of Low Test Results 3-22
3-6 Required Mean Test Value 3-23
3-7 Statistical Data - Clay Liner Dry Density 3-25
IX
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SECTION 1.0
Construction Quality Management
The purpose of this document is to define procedures that ensure construction materials and
practices used in waste containment installations meet the project specifications and the
requirements of related remedial settlement orders. The specific objectives are:
Define Construction Quality Management (CQM) and the responsibility of the
parties involved in the project
Define and list the waste containment systems described in 40 CFR 240 and
300
Identify components used to construct the waste containment systems
Identify the elements that are used to assemble these components and the key
properties of these elements that require testing in the field to measure the
quality of the construction
Present sampling methods to obtain unbiased representative samples from these
key elements
Present examples of how to implement these sampling methods on selected
elements.
This document is written for the design engineer responsible for preparation of project plans,
specifications, and the CQM program, and the EPA remedial project manager (RPM) charged
with implementing the CQM program. The document focuses on those factors most
susceptible to field construction problems. It is assumed that the materials to be used at each
site have been designed (thickness, type, etc.) and evaluated (EPA Method 9090, etc.) by
others. These elements are assumed to meet the applicable or relevant and appropriate
requirements (ARAR) for the site as determined in the remedial investigation and feasibility
studies (RI/FS) process under CERCLA (1).
CQM is defined as the pro-active planning, development and implementation of both
Construction Quality Assurance (CQA) and Construction Quality Control (CQC) throughout the
project. In order to ensure a functional and safe waste containment system, quality must be
present in all phases of the project, including:
1-1
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Pre-construction phase
conceptual design
design
preparation of project specifications
preparation of CQA/CQC documents
Construction phase
material property testing
installation testing
Post-Construction phase
care of installation until it goes into service
inspection and maintenance of the facility
operations
While COM must be included in every phase of the project and a system of testing and
oversight must be used throughout the project, the focus of this document is COM during the
construction phase of the development of a waste containment system.
1.1 CQA/CQC Objectives
Construction Quality Assurance (CQA) consists of a planned series of observations and tests to
ensure that the final product meets project specifications. CQA plans, specifications,
observations, and tests are used to provide quantitative criteria with which to accept the final
product.
On routine construction projects, CQA is normally the concern of the owner and is obtained
using an independent third party testing firm. For the waste containment applications covered
by this guide, the CQA program is also commonly a certification tool used by EPA to ensure
that the project is properly implemented. The independence of the third party inspection firm is
therefore of great Importance. This is particularly true when the owner is a corporation or
other legal entity that has under its corporate 'umbrella' the capacity to perform the CQA
activities. Although these CQA personnel may be registered professional engineers, there may
exist a perception of misrepresentation if the activity is not performed by an independent third
party.
The CQA officer should fully disclose any activities or relationships with the owner which may
impact his impartiality or objectivity. If such activities or relationships exist, the CQA officer
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should describe actions that have or can be taken to avoid, mitigate, or neutralize the
possibility they might affect the CQA officer's objectivity. Regulatory representatives can then
evaluate whether these mechanisms are sufficient to ensure an acceptable CQA product.
Construction Quality Control (CQC) is an ongoing process of measuring and controlling the
characteristics of the product in order to meet manufacturer's or project specifications. CQC is
a production tool that is employed by the manufacturer of materials and contractor installing
the materials at the site. CQA, by contrast, is a verification tool employed by the facility
owner or regulatory agency to ensure that the materials and installations meet project
specifications. CQC is performed independently of the CQA Plan. For example, while a
geomembrane liner installer will perform CQC testing of field seams, the CQA program will
require independent CQA testing of those same seams by a third party inspector.
The CQA/CQC plans are implemented through inspection activities which include visual
observations, field testing and measurements, laboratory testing and the evaluation of the test
data. Inspection activities are typically concerned with four separate functions:
Quality Control (QC) Inspection bv the Manufacturer provides an in-process measure of
the product quality and its conformance with the project plans and specifications.
Typically, the manufacturer will provide CQC test results to certify that the product
conforms to project plans and specifications.
Construction Quality Control (CQC) Inspection bv the Contractor provides an in-process
measure of construction quality and conformance with the project plans and
specifications. This allows the contractor to correct the construction process if the
quality of the product is not meeting the specifications and plans.
Construction Quality Assurance (CQA) Testing bv the Owner (Acceptance Inspection)
performed by the owner usually through the third party testing firm, provides a measure
of the final product quality and its conformance with project plans and specifications.
Due to the size and costs of a typical remedial action/remedial design (RA/RD) project,
rejection of the project at completion would be costly to all parties. Consequently,
CQA testing takes place throughout the construction process. This allows deficiencies
to be found and corrected before they become too large and costly. CQA represents an
important tool to EPA to ensure that the remediation is properly implemented.
Regulatory Inspection is often performed by a regulatory agency to ensure that the final
product conforms with all applicable codes and regulations. In some cases the
regulatory agency will use the CQA documentation and the as-built plans or 'record
drawings' to confirm compliance with the regulations.
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EPA Report 530-SW-86-031 (NTIS PB87-132825) entitled "Construction Quality Assurance for
Hazardous Waste and Land Disposal Facilities" sets forth key items that should be included in
the CQA/CQC Plan:
1) Responsibility and Authority - The responsibility and authority of the various
organizations and personnel involved in permitting, designing, and building the
facility should be described.
2) Personnel Qualifications - The qualifications of the CQA officers and supporting
CQA inspection personnel should be presented.
3) Inspection Activities - The observations and tests that will be used to ensure that
the construction or installation meets or exceeds all design criteria, plans, and
specifications for each component should be described.
4) Sampling strategies - The sampling activities, sample size, methods for determining
sample locations, frequency of sampling, acceptance and rejection criteria, and
methods for ensuring that corrective measures are implemented should be
presented.
5} Documentation - Reporting procedures for CQA activities should be described in
detail in the CQC/CQA plans.
The responsibility and authority of project organizations and personnel (item 1 above) are
included in the above EPA Report and will not be discussed here. Guidelines for the
qualification of personnel (item 2) are also included in the EPA report, but are being revised and
will be presented in an upcoming document. Currently, a program to certify CQA inspectors is
administered by the National Institute for Certification of Engineering Technicians (NICET).
Inspection activities for specific components of a waste containment system have been
presented in a variety of EPA papers and Technical Guidance Documents (TGDs) (2, 3, 4, 5, 6,
7) and will only be summarized in this report.
This guidance document begins with a brief overview of waste containment systems and
components along with the key physical properties that require monitoring during construction
and installation. A major focus of this document is the sampling strategies and acceptance
criteria which are used in the CQA plan (item 4). Suggested CQA documentation requirements
are provided in several EPA TGDs detailing waste containment components (8, 9, 10).
1-4
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1.2 Regulatory Waste Containment Systems and Objectives
Under current RCRA and CERCLA regulations, there are four distinct waste containment
systems: surface impoundments, waste piles, landfills, and on-site isolation. Each
containment system is built of components with distinct engineering functions, (e.g. moisture
barrier, reinforcement, drainage, etc). In turn, each component is composed of elements , i.e.,
individual materials or products, that have particular field inspection requirements. This
chapter provides a brief overview of the four waste containment systems and their major
components. Chapter 2 describes the elements and their respective CQA field testing
requirements. Chapter 3 reviews common field sampling strategies and acceptance criteria
and provide examples of their application.
Surface Impoundments
These are basins used to store or dispose of primarily liquid wastes. If the system is planned
to be removed after the operating life and the site cleaned of all contamination, then it is
considered a storage unit. If the waste is stabilized, the free liquid is removed, and the system
is closed and monitored, then it is a disposal unit. Surface impoundments can include liners,
leachate collection systems, leachate detection systems, and gas collection systems. If the
facility is designed as a disposal unit, then a closure system is necessary.
Under the Federal requirements for the design and operations for surface impoundments (40
CFR 264 subpart K, 264.220 to 264.231) and EPA's design, construction and operation
guidelines (Technical Resource Document 530-SW-91-054) (10), a surface impoundment must
include the components and elements shown on Figure 1-1. A typical cover profile used when
a surface impoundment is closed without waste removal is also shown on Figure 1 -2.
Waste Piles
These are structures in which waste can be treated and/or stored temporarily. A waste pile
system must have a similar bottom liner system as the surface impoundment but will not have
a final cover since it is only a temporary structure. However, waste piles must be covered by
a structure which keeps precipitation, wind and surface water run-on away from the waste.
Typically, these protective structures are simple metal buildings, although other protective
cover may be used. For example, a geomembrane can be used to cover the waste. The
various components and elements of waste piles as required by Federal regulations (40 CFR
264 subpart L, 264.250 to 264.259) are shown on Figure 1-3.
1-5
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GEOTEXTILES
RIPRAP ARMOR
SOIL PROTECTIVE
LAYER
SECONDARY
CONTAINMENT
DIKE
COMPACTED LOW-
PERMEABILITY SOIL
-LEAK COLLECTION LAYER
SURFACE IMPOUNDMENT COMPONENTS AND ELEMENTS
REFERENCES: 40 CFR 264, SUBPART K
TRD/EPA 530-SW-91-054
UNER SYSTEM CONSISTING OF ONE OR MORE OF THE
FOLLOWING:
COMPACTED SOIL LINER
BENTONITE MODIFIED ON-SITE SOILS
GEOSYNTHETIC CLAY UNER (GLC)
GEOMEMBRANE
LEACHATE COLLECTION SYSTEM or LEAK DETECTION SYSTEM
GRANULAR SOIL OR GEOSYNTHETIC DRAINAGE LAYER
PIPES.
SUMPS, AND
PUMPS
GAS VENTING SYSTEM IF ORGANIC SOILS ARE PRESENT BENEATH THE LINER
GRANULAR SOIL OR GEOSYNTHETIC DRAINAGE LAYER
VENT PIPES OR FLAPS
GEOTEXTILE FILTER TO PROTECT DRAINAGE LAYER
UNER PROTECTION COVER T0 PROTECT IT FROM CONSTRUCTION, WEATHER, AND
OPERATIONAL DAMAGE
SOIL OR GEOTEXTILE PROTECTIVE LAYER OVER LINER
STONE OR RIP-RAP ABOVE LIQUID LEVEL TO PREVENT EROSION AND DAMPEN WAVE ACTION
SURFACE WATER MANAGEMENT SYSTEM
DIVERSION DITCHES AND BERMS,
INLETS, PIPES, MANHOLES
AND RETENTION/DETENTION BASINS
VOLATILE ORGANIC COUMPOUND EMISSION CONTROL SYSTEM
COMPLETE ENCLOSURE, E.G. AIR BUBBLE
SURFACE BARRIER OR FLOATING COVER OF FOAM, OIL, OR GEOMEMBRANE
WIND DIVERSION FENCE
STABLE FOUNDATION " ~
GROUND-WATER MONITORING WELLS
LIQUID LEVEL CONTROL SYSTEM CONSISTING OF EITHER AN ACTIVE SYSTEM
USING PUMPS OR A PASSIVE SYSTEM USING A SPILLWAY
SECONDARY CONTAINMENT SYSTEM SURROUNDING ENTIRE SURFACE IMPOUNDMENT
FIGURE 1-1 SURFACE IMPOUNDMENT USED FOR STORAGE
1-6
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COBBLES/SOIL
TOP LAYER *
BIOTIC BARRIER
(COBBLES)
LOW-PERMEABILITY
GEOMEMBRANE/SOIL LAYER
J. 4
VEGETATION/SOIL \ .. .. .
TOP LAYER -J
GAS VENT 30 cm
BEDDING LAYER
(IF REQUIRED)
GEOTEXTILE FILTER
WASTE
(30 cm = appro*. 1ft)
MIN 30-m!l (0.76mm) GEOMEMBRANE
W/OVERLYING PROTECTIVE GEOTEXTILE
SURFACE IMPOUNDMENT AND LANDFILL COVER SYSTEM
REFERENCES: 40 CFR, SUBPART K
TRD/EPA 530-SW-91-054
PROTECTIVE COVER WITH VEGETATIVE OR HARDENED EROSION CONTROL SURFACE
VEGETATIVE LAYER OF TOPSOIL VEGETATION OR
HARDENED LAYER OF RIP-RAP, ASPHALT, OR CONCRETE,
PROTECTIVE SOIL LAYER
BIOTIC BARRIER TO LIMIT PENETRATION OF BURROWING ANIMALS AND TAP ROOTS
COBBLES, STONES OR HARDENED BARRIER SYSTEM
GEOTEXTILE FILTER TO CONTAIN ADJACENT SOILS
SURFACE WATER DRAINAGE LAYER
GRANULAR SOIL OR GEOSYNTHETIC DRAINAGE LAYER
GEOTEXTILE FILTER
LOW PERMEABILITY BARRIER CONSISTING OF ONE OR MORE OF THE FOLLOWING
COMPACTED SOIL' UNER
BENTONITE AMENDED ON-SITE SOILS
GEOSYNTHETIC CLAY LINER (GLC)
GEOMEMBRANE
GAS COLLECTION SYSTEM IF WASTE WILL GENERATE GAS
GRANULAR SOIL OR GEOSYNTHETIC DRAINAGE LAYER
VENT PIPES
GEOTEXTILE FILTER TO PROTECT DRAINAGE LAYER
BEDDING LAYER OVER WASTE TO PROVIDE STABLE WORKING PLATFORM
* ON-SITE SOIL
GEOTEXTILE FILTER TO PROTECT BEDDING LAYER
FIGURE 1-2 COVER SYSTEM FOR SURFACE IMPOUNDMENT/LANDFILL CLOSURE
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NOTE.* STRUCTURE CONSTRUCTED TO PROTECT WASTE FROM PERCIPITATION. SURFACE
RUN-ON, AND DISPERSAL BY WIND.
LEACHATE COLLECTION
AND PROTECTIVE
REMOVAL SYSTEM SOIL AND COVER
(opfonal)
GEOMEMBRANE
COMPACTED SOIL COMPONENT
OF BOTTOM COMPOSITE LINER
WASTE PILES FOR INTERIM HAZARDOUS WASTE STORAGE
REFERENCES: 40 CFR 264, SUBPART l_
264.250 TO 264.259
UNER SYSTEM CONSISTING OF ONE OR MORE OF THE FOLLOWING :
COMPACTED SOIL UNER
BENTONITE MODIFIED ON-SITE SOILS
GEOSYNTHETIC CLAY LINER (GLC)
GEOMEMBRANE
LEACHATE COLLECTION SYSTEM or LEAK DETECTION SYSTEM
GRANULAR SOIL OR GEOSYNTHETIC DRAINAGE LAYER
PIPES,
SUMPS, AND
PUMPS
GAS VENTING SYSTEM IF ORGANIC SOILS ARE PRESENT BENEATH THE LINER
GRANULAR SOIL OR GEOSYNTHETIC DRAINAGE LAYER
VENT PIPES OR FLAPS
GEOTEXTILE FILTER TO PROTECT DRAINAGE LAYER
UNER PROTECTION COVER T0 PROTECT IT FROM CONSTRUCTION, WEATHER, AND
uixc.r\ rf\wic.vxiiปjn wwvc.i\ OPERAT|ONAL DAMAGE
SOIL OR GEOTEXTILE PROTECTIVE LAYER OVER UNER
STONE OR RIP-RAP ABOVE LIQUID LEVEL TO PREVENT EROSION AND DAMPEN WAVE ACTION
SURFACE WATER MANAGEMENT SYSTEM
DIVERSION DITCHES AND BERMS,
INLETS, PIPES, MANHOLES
AND RETENTION/DETENTION BASINS
VOLATILE ORGANIC COUMPOUND EMISSION CONTROL SYSTEM
COMPLETE ENCLOSURE, E.G. AIR BUBBLE
SURFACE BARRIER OR FLOATING COVER OF FOAM, OIL, OR GEOMEMBRANE
WIND DIVERSION FENCE
STABLE FOUNDATION
GROUND-WATER MONITORING WELLS
LIQUID LEVEL CONTROL SYSTEM CONSISTING OF EITHER AN ACTIVE SYSTEM
USING PUMPS OR A PASSIVE SYSTEM USING A SPILLWAY
SECONDARY CONTAINMENT SYSTEM SURROUNDING ENTIRE SURFACE IMPOUNDMENT
FIGURE 1-3 WASTE PILE USED FOR INTERIM WASTE STORAGE
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Landfills
These are final disposal units for solid and hazardous wastes. Landfills have the same
components and elements as the surface impoundment disposal units. Under the requirements
for the design and operation of landfills (40 CFR 264 subpart N, 264.300 to 264.317) and the
design, construction and operations guidelines presented in EPA seminar publications (11, 12),
a landfill should include the components and elements shown on Figure 1-4.
On-Site Waste Isolation
Remedial actions to isolate uncontrolled releases of contaminates are described in 40 CFR 300
S}
"Appendix D - Appropriate Actions and Methods of Remediating Releases." Waste isolation
systems include caps built over waste to minimize infiltration of rainwater, and both horizontal
barriers under the waste and vertical barriers at the lateral extent of the waste to prevent
uncontrolled release of leachate (12, 13, 14). These are systems which are constructed on
remediation sites to isolate and allow for the treatment of an uncontained waste.
Caps -- "
Waste facility caps reduce water infiltration, control gas and odor emissions, improve the
aesthetics, and provide a stable surface over the waste. A composite barrier capping system
(Figure 1-2), is required for the closure of hazardous waste storage facilities (12, 13). A
hardened cap is typically required in an arid climates where a vegetative cover will not survive,
in urban areas where vegetation may be undesirable, or at industrial facilities where it would be
advantageous to continue using the site. The hardened cap integrates the vegetative layer,
protective layer (biotic) and drainage layer into one layer as shown in Figure 1-5. The hardened
cap can be constructed using "hard" elements, such as graded stone, asphalt, or concrete.
Note that the use of a hardened surface layer does not eliminate the need for the
geomembrane/clay moisture barrier components in the cap.
Horizontal Barriers
Horizontal barriers are installed below an existing waste mass to contain the waste and prevent
the movement of contaminate into the surrounding soil and water. Horizontal barriers are very
difficult to inspect due to the overlying waste.
Horizontal barrier techniques involve the injection of grout under the waste using one of the
following methods:
1-9
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PROTECTIVE
SOIL AND COVER
(optonal)
PRIMARY LEACHATE
COLLECTION AND
REMOVAL SYSTEM
TOP LINER
^ (GEOMEMBRANE)
\ (HAZARDOUS WASTE ONLY)
SECONDARY UHLlt. viA-m/r crnii
-COLLECTION AND 'ซ"ป NATIVE SOIL
REMOVAL SYSTEM FOUNDATION DRAIN PIPES-
(HAZARDOUS WASTE ONLY) GEOMEMBRANE COMPONENT,
OF COMPOSITE LINER
COMPACTED SOIL COMPONENT
OF BOTTOM COMPOSITE LINER
LANDFILLS - LONG-TERM HAZARDOUS WASTE DISPOSAL
REFERENCES: 40 CFR 264, SUBPART N
EPA 625/4-91-025, EPA 625/4-89-022
LINER SYSTEM CONSISTING OF ONE OR MORE OF THE FOLLOWING:
COMPACTED SOIL LINER
BENTONITE MODIFIED ON-SITE SOILS
GEOSYNTHETIC CLAY LINER (GLC)
GEOMEMBRANE
LEACHATE COLLECTION SYSTEM or LEAK DETECTION SYSTEM
GRANULAR SOIL OR GEOSYNTHETIC DRAINAGE LAYER
PIPES,
SUMPS. AND
PUMPS
GAS VENTING SYSTEM IF ORGANIC SOILS ARE PRESENT BENEATH THE LINER
GRANULAR SOIL OR GEOSYNTHETIC DRAINAGE LAYER
VENT PIPES OR FLAPS
GEOTEXTILE FILTER TO PROTECT DRAINAGE LAYER
LJNER PROTECTION COVER TO PROTECT IT FROM CONSTRUCTION, WEATHER, AND
unit-it r.v^ii-^.iw.i ^wi_ix 0pERAT)ONAL DAMAGE
SOIL OR GEOTEXTILE PROTECTIVE LAYER OVER LINER
STONE OR RIP-RAP ABOVE LIQUID LEVEL TO PREVENT EROSION AND DAMPEN WAVE ACTION
SURFACE WATER MANAGEMENT SYSTEM
DIVERSION DITCHES AND BERMS,
INLETS, PIPES, MANHOLES
AND RETENTION/DETENTION BASINS
WIND DISPERSAL CONTROL SYSTEM
COMPLETE ENCLOSURE, E.G. AIR BUBBLE
SURFACE BARRIER OF FOAM OR GEOMEMBRANE
WIND DISPERSION FENCES
STABLE FOUNDATION
GROUND-WATER MONITORING WELLS
LIQUID LEVEL CONTROL SYSTEM CONSISTING OF EITHER AN ACTIVE SYSTEM
USING PUMPS OR A PASSIVE SYSTEM USING A SPILLWAY
EM SURROUNDING ENTIRE SURFACE IMPOUNDMENT
SECONDARY CONTAINMENTS
FIGURE 1-4 LANDFILL USED FOR HAZARDOUS WASTE STORAGE
1-10
-------
3-4" (7.5-tO cm) Asphalt
paving (2 course)
Granular Drainage
Geomembrane
10% max slope
Bedding Layer
Waste
or glc
(a) Asphalt Cap
4" (10 cm) Concrete
(6x6 Wire Reinforced)"
Granular Drainage
Geomembrane
\0% max slope
Bedding Layer
t Waste ^.
* or glc
(b) Concrete Cap
4-6T (10-15 cm) Stone
Geotextlle Filter Cloth
Perimeter Drain
Stone
Granular Drainage
Geomembrane
max slope
Bedding Layer
ss Waste
* or glc :
(c) Graded Stone Cap
* or glc
(d) Multi - Media Cap
FIGURE 1-5 HARDENED CLOSURE SYSTEM
1-11
-------
vertical borings drilled through the waste and pressure injection or rotary jetting of
the grout beneath the waste,
horizontal borings drilled below the waste from trenches and pressure injection of
the grout beneath the waste,
block displacement method which surrounds the waste with a vertical grout wall
and then injects low pressure grout beneath the waste. The entire waste block is
raised in this process (15).
All of these methods require that the borings be spaced close enough together that the grout
bulbs or lenses overlap and form a continuous barrier. Verification of the overlap is critical but
very difficult. Potential inspection methods are limited to test excavations, exploratory borings,
and observed impact on ground water if the barrier is placed beneath the ground water table.
Vertical Barriers ~
Vertical barriers are wall-like systems used to isolate any contaminates that have leached from
the waste and that are moving laterally. To be effective, these barriers should intercept a
continuous impervious horizontal layer below the waste. This bottom layer can be a naturally
occurring layer such as an aquiclude, or a horizontal barrier. Several types of vertical barriers
are commonly used, including:
Slurry wall. A trench surrounding the waste, filled with a soil bentonite and/or
concrete-bentonite slurry.
Grout curtain. Grout is injected in a series of vertical columns that surround the
waste, creating a continuous curtain.
Geomembrane curtain. Interlocking geomembrane panels are placed in a vertical
trench surrounding the waste. In some cases the geomembrane is used in
conjunction with the slurry wall to form a composite liner system.
Schematics of grout curtains and geomembrane curtains are shown in Figure 1-6.
1.3 Components and Elements in Waste Containment Systems
The regulatory waste containment systems reviewed in Section 1.2 are constructed using a
small family of functional components. These functional components include:
1-12
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a. GROUT CURTAIN VERTICAL BARRIER
Geomembrane
Impervious
Stratum
Perforated Drain Pipe
b. GEOMEMBRANE VERTICAL BARRIER
FIGURE 1-6 VERTICAL BARRIER SYSTEMS
1-13
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Hydraulic Barriers
Hydraulic Conveyances
Filter Layers
Erosion Control Layers
Protective Layers
Earthwork
Each of these basic building blocks is in turn composed of distinct physical elements as listed
on Table 1-1. It is important to understand that project specifications and the construction
quality management program will focus on elements and not components. Thus project
specifications for a hydraulic barrier will provide guidance for clay or geomembrane properties
but will not identify functional properties of the overall hydraulic barrier. This document
therefore examines construction quality management at an elemental level.
1-14
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TABLE 1-1 WASTE CONTAINMENT COMPONENTS AND ELEMENTS
COMPONENT
Hydraulic Barriers
ELEMENTS
Hydraulic Conveyances
(Both Liquid and Gas Conveyance)
Filter Layers
Erosion Control Layers
Protective Layers
Earthwork
Geomembranes
Geomembrane Interlocking Panels
Grouts
Compacted Soil
Bentonite Products
! Soil-Bentonite Blends
Geosynthetic Clay Liner
, Bentonite Slurries
Concrete/Bentonite Slurry
Natural Sand/Gravel Drain/Collector
Geosynthetic Drain/Collector
Pipe
Sumps
Pumps
Sand/Gravel Filter
Geotextile
Stone and Rip-Rap
Vegetation and Topsoil
Geosynthetic Erosion Control Products
Hardened Layer
Biotic Layer
Geotextile
Soil Layer
Soil Foundation or Bedding Layer
Soil Embankments
Geotextile Separator
1-15
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1.4 References ,
1-1 - U.S. EPA. 1988. Guidance for Conducting Remedial Investigations and Feasibility
Studies under CERCLA, Interim Final, Office of Emergency and Remedial Response,
Washington, DC 20460.
f.
1-2 - U.S. EPA. 1984. Quality Assurance Handbook for Air Pollution Measurement
Systems: Volume 1 Principles. EPA 600/9-76/005, Environmental Monitoring
Systems Laboratory, Research Triangle Park, NC 27711.
1-3 - U.S. EPA. 1986. Construction Quality Assurance for Hazardous Waste Land
Disposal Facilities. Technical Guidance Document EPA 530-SW-86-031, Office of
Solid Waste and Emergency Response, Washington, DC 20460.
1-4 - U.S. EPA. 1987. Geosynthetic Design Guidance for Hazardous Waste Landfill Cells
and Surface Impoundments. EPA 625/4-89/022, Hazardous Waste Engineering
Research laboratory. Office of Research and Development, Cincinnati, OH 45268.
1-5 - U.S. EPA. 1989. Requirements for Hazardous Waste Landfill Design, Construction,
and Closure. Seminar Publication EPA 625/4-89/022, Center for Environmental
Research Information, Office of Research and Development, Cincinnati, OH 45268.
1-6 - U.S. EPA. 1991. Inspection Techniques for the Fabrication of Geomembrane Field
Seams. Technical Guidance Document EPA 530/SW-91/051, Risk Reduction
Engineering Laboratory, Cincinnati, OH 45268.
1-7 - U.S. EPA. 1989. The Fabrication of Polyethylene FML Field Seams. Technical
Guidance Document EPA 530/SW-89/069, Office of Solid Waste and Emergency
Response, Washington, DC 20460.
1-8 - U.S. EPA. 1988. Guide to Technical Resources for the Design of Land Disposal
Facilities. Technology Transfer Document EPA 625/6-88/018, Risk Reduction
Engineering Laboratory, Cincinnati, OH 45268.
1-9 - U.S. EPA. 1984. Permit Applicants' Guidance Manual for Hazardous Waste Land
Treatment, Storage, and Disposal Facilities - Final Draft. EPA 530 SW-84-004,
Office of Solid Waste and Emergency Response, Washington, DC 20460.
1-10 - U.S. EPA. 1983. Handbook for Evaluating Remedial Technology Plans, Municipal
Environmental Research Laboratory, Research and Development Document EPA-
600/2-83-076, Office of Research and Development, Cincinnati, OH 45268.
1-11 - U.S. EPA. 1991. Design, Construction, and Operation of Hazardous and Non-
Hazardous Waste Surface Impoundments. Technical Resource Document EPA
530/SW-91/054, Office of Research and Development, Washington, DC 20460.
1-12 - U.S. EPA. 1991. Design and Construction of RCRA/CERCLA Final Covers. Seminar
Publication EPA 625/4-91/025, Office of Research and Development, Washington,
DC 20460
1-13 - U.S. EPA. 1989. Final Covers on Hazardous Waste Landfills and Surface
Impoundments. Technical Guidance Document, EPA 530/SW-89/047, Risk
1-16
-------
Reduction Engineering Laboratory, Cincinnati, OH 45268.
1-14 - U.S. EPA. 1991. Conducting Remedial Investigations/Feasibility Studies for
CERCLA Municipal Landfill Sites. Technical Guidance Document EPA 540/P-
91/001, Office of Emergency Remedial Response, Washington, DC 20460.
1-15 - U.S. EPA. 1987. Block Displacement Method Field Demonstration and
Specifications, EPA 600/2-87/023, Risk Reduction Engineering Laboratory,
Cincinnati, OH 45268:
1-17
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-------
SECTION 2.0
Summary of Construction Elements and Key Properties
Construction elements are commonly used as pay units on construction projects and as such
are readily identified. For example, the contractor may be paid based on the square footage of
geomembrane installed or the cubic yardage of compacted clay, sand, etc. installed. Specific
references to these elements are made in the project specifications.
This chapter reviews the elements common to components used in waste containment
systems. Each element will have physical properties defined in the project specifications.
Some of these properties must be verified in the field as part of the construction quality
management program. However, many of the physical, mechanical and chemical properties
cannot be verified in the field. In these cases, the construction quality management program
must rely either on certification by the manufacturer or supplier that the material meets project
specifications or conformance testing by an independent laboratory. Key properties or
installation parameters that require verification and corresponding test methods are discussed
in this chapter. Standard test methods to quantify material properties are identified in
Appendix A.
2.1 Hydraulic Barriers
A site manager should realize that the performance of a barrier system can exceed the sum of
the elements that comprise it. A well constructed composite liner system, for example, will
have less infiltration than what is expected from independent evaluations of the clay liner and
geomembrane. Such synergistic interaction between elements is not accounted for in project
specifications or the construction quality management program. Table 2-1 identifies hydraulic
barrier systems and elements that require field testing.
Geomembranes
Geomembranes are used as low permeability barriers in both the bottom liners and caps of
waste containment systems. In a hazardous waste landfill, geomembranes can be used alone
as the upper or primary liner, and in conjunction with a low permeability soil layer to form the
lower or secondary composite liner. Manufacturers and fabricators of geomembranes are
responsible for the quality control of both the raw materials, such as plastic resin, and the
finished sheets. Their internal quality control (QC) incorporates routine testing of the polymer
and the finished product. Test results must be submitted with each lot of geomembranes
shipped to the site. In addition, certification must be presented with the geomembranes
2-1
-------
TAStEa-l
ELEMENT
Seomtmbnuu
Geomembrane
Interlocking Panels
Grouts
Bentonite Amended Soil
Also Bentonite Slurry)
Also Cement-Bentonite)
Geosynthetic Clay Uner
(GCq
Compacted Clay LJner
(CCL)
MATERIAL PHOPEHmES/POST-CONSTRUCTlON CARE
Poiymwpfopertiw:
Mett Flow Index
Cutjon Black Content
Carbon Black Dteperalon
- Environmental Stress Crack
Notched Constant Load Teat
Mechanical Properties
-Thickness
- Density
-Tensile Properties
Post Construction: Upon completion, the geomembrane should be
covered or weighted using sandbags to prevent damage from wind.
Additionally, the geomembrane Is vulnerable to construction and
weather related damaqe If left exposed.
* Polymer Properties of Geomembrane (As Above)
* Interlock Sealing Element
* Mechanical Properties of Geomembrane(As Above)
Post Construction: Verification of the Integrity of the Interlock
seal Is difficult No known field verification strategies
* Grout Material Properties:
-Viscosity of Grout
- Gradation of Sand
-Unit Weight
- Compresslve Strength
* Bentonite Material Properties: Bentonite Type,
Atterburg Limits, Percent Impurities
* Soil Properties: Grain Size Distribution
Atterburg Limits
* Bentonite Amended Soil: % Bentonite
Water Content
Post Construction: Same as Clay Below
* Bentonite Properties: Atterburg Limits, Type
Percent Impurities, Mass per Unit Area of Board
* Geotextile Properties: AOS, Trap Tear, Polymer
Post Construction: Protect from free water
* Clay Properties: Atterburg Limits
Grain Size Distribution
Moisture-Density Relationship
Maximum Clod Size < 2 Inch
Post Costructlon: Clay liners can be damaged from
either desslcation or freezing. Soil liner must be
protected from drying or freezing
TEST
ASTM 01238
ASTMD1603
ASTM 03015
ASTM D18S3(C)
GRIGMS
ASTM D751
ASTM 0783 (A -1)
ASTMD6380V)
As Above
Certification
As Above
ASTMD4016
Certification
ASTM D43SO
ASTM 04832
Certification
ASTM 0422
ASTM 04318
Methylene Blue
ASTM D4959
ASTM D4318
Certification
Certification
ASTM D4318
ASTM D422.
ASTMD1557orD698
Visual
NSTAUATON QUALITY VERIFICATION
Placement Considerations
PrtpvaQon of surface. EG. no sharp Hams, rocks, fftc
Stabto foundation
- Anchor trenches hava proper dimensions and location
Geomembrane panels placed per pant) placement drawing
Measure overlap of seams
'Seaming
- Adequate surface preparation; clean, dry, extent grinding
- Temperature, Pressure, Speed of Seaming
- Adequate curing time prior to testing (if applicable)
- Document start & step locations, crews, repairs and weather
- 100% Non-destructive seam testing: Air lance, Mechanical
Point Stress, Electric Spark, Vacuum Chamber, Dual Seam
- Destructive Seam Testing: PeellASTM 0413), Shear(ASTM D8B2)
or ASTM 03083 -1' Wide
* Placement Considerations
- Adequate depth of placement(s!urry trench or vibration)
- Interlock panels placed per panel location drawing
- Continuous seaming of Interlock seal
* Seaming
- Pressure of Interlock seaming element
Placement Considerations
- Spacing of drill pipe used to Inject grout
- Depth of drill pipe during injection
- Quantity of grout Injected
- Pressure of grout during injection
* Placement Consideration
- Thoroughness of blending, e.g. % Bentonite
(May require Pugg Mill or Asphalt Grinder for
a uniform mixture of soil and Bentonite)
* Placement Consideration
- Minimum 6-inch overlap of adjacent panels
- Subgrade free of rocks, ruts, ets. that could
penetrate board
- Stable foundation
* Placement Considerations
- Soil water content as specified
- Soil density as specified
- Water content adjustment not made 24-hr, prior to placement
- Sheepsfoot roller with fully penetrating feet
- Scarify between lifts
FIELD TEST
Visual
Proof Ron
Survey
Visual
Visual
Visual
Certification
Visual/Trial
Visual
Per Spec.
Per Spec.
Visual
Visual
Visual
Visual
Visual
Visual
Bulk Measure
Visual
Methylene Blue
Visual
Visual
Proof Roll
ASTMD4959
ASTM D2922
Visual
IP
ro
-------
stating that the materials are in compliance with manufacturer's published information and/or
the project specifications.
A sample of each lot (production run) of geomembrane material that arrives at the site should
be taken. Tests on these samples should confirm that they have the same polymer properties
required by project specifications. This is known as conformance testing and should be
performed by an independent laboratory. A series of samples, instead of one, may be
necessary to provide all responsible parties with a sample. Testing of the geomembrane in the
field is typically limited to verification of membrane thickness, visual inspection for physical
defects, and a thorough testing of all field seams.
Non-Destructive Testing (NOT) of seams is required for the entire length of the seam. Such
testing is performed using the vacuum box test for single bonded seams or the pressurized air
channel test for those seams that have two lines of bonding separated by an air channel. The
vacuum box test applies a moderate vacuum to a seam previously wetted with soapy water.
Leaks are indicated by bubbles. The test must be repeated over the entire length of the seam.
The pressurized air channel test inflates the seam and checks for a loss of pressure. Samples
for destructive testing are commonly taken at a minimum of every 500 feet of seam, with at
least one sample taken per seam. Additionally, samples must be cut at least every four hours
or when seaming conditions change to provide samples for destructive testing and to monitor
variations in seam quality due to variations in operator or seaming equipment. The reader is
referred to the Technical Guidance Document EPA/530/SW-91/051 entitled "Inspection
Techniques for the Fabrication Geomembrane Field Seams. Specific test requirements may be
part of the Construction Quality Assurance Manual prepared for the project.
Geomembrane Interlocking Panels
Geomembrane interlocking panels are installed in vertical trenches to construct a low
permeability barrier. The panels consist of membrane panels that connect along their lengths
much like conventional steel sheet piles. The panels are pre-fabricated and assembled at the
site by locking the panels together and placing them into the trench.
Geomembrane interlocking panels have two physical elements; high density Polyethylene
(HOPE) panels with interlock fittings along their vertical edge, and a soft plastic sealing medium
within the interlock that provides a hydraulic seal to the interlock fittings. The HOPE interlock
closely resembles that used in conventional steel sheet files: A female channel on one panel
that engages a male edge of an adjacent panel. Field inspection of the HOPE panels and
hydraulic seal material is generally identical to that required for geomembrane materials. Field
testing of the geomembrane panels is typically limited to verification of panel thickness. The
interlock seal material is hydrophilic and swells in the presence of the groundwater to establish
a seal. The manufacturer should be required to provide certification of the long-term chemical
2-3
-------
stability of the hydraulic seal material when exposed to the site-specific contaminant.
Geomembrane interlocking panels can be installed in open trenches, slurry trenches, or vibrated
into sandy soils using a steel mandrel. Care must be taken to insure that the hydraulic
interlock and seal material properly seat along the entire length of the interlock channel. This
verification can be difficult in slurry wall and vibrated installations. The continuity of the
interlock is tested during installation of a new panel using a "runner". The runner consists of a
31/2 inch section of the female portion of the interlock that is secured to a rope. The runner
is installed ahead of the panel to be installed so that it is pushed down the interlock by the
panel being installed. The rope is knotted to show final installation depth. If the runner comes
to a halt before the full insertion depth is reached, the panel must be removed and redriven.
The hydraulic seal is marked in a similar manner and is not accepted if the seal advance depth
is less than 85% of the panel depth.
Grouts
The grout used in a waste containment system is usually a mixture of cement and bentonite.
Grouts are, however, available with silica, acrylate, urethane, and Portland cement binders.
Grout can be injected in horizontal or vertical borings using a variety of pressures. The
suppliers of the grout materials must provide material property data sheets and a certification
that the materials conform to their specifications. During the mixing of the grout, the
quantities of materials used in the mix should be measured and recorded. Once the grout is
mixed, it must be tested to confirm that it meets project specifications for viscosity (Marshal
funnel test), setting time, and strength.
Grout is pressure injected into the ground by specialty contractors. Field monitoring
requirements include documentation of the injection location, depth, pumping rate, and total
grout volume used (see Table 2-1).
Bentonite Products
Bentonite provides an effective moisture barrier. Available as either sodium bentonite mined in
several western states or a less active calcium bentonite from Georgia, commercial bentonite is
purchased in powder or pellet form. The permeability of bentonite ranges from 10~8 cm/sec for
calcium bentonite to as low as 10~10 cm/sec for sodium bentonite. Bentonite can be used by
itself to form a moisture barrier or blended with on-site soils to form an acceptable soil liner.
Bentonite is available from commercial suppliers who must provide a summary of the material
properties of the bentonite shipped to the project site and certification that the materials meet
their specifications.
2-4
-------
Bentonite Amended Soil--
When there is not an adequate supply of low permeability soil on site for the construction of a
soil barrier layer, a bentonite soil amendment can be used to lower the permeability of the on-
site soils. Typically, a 3 to 6% bentonite amendment by dry weight is sufficient to achieve a
permeability of 1 x 10"7 cm/sec using on-site soils. Sands, however, may require as much as
10 to 15% bentonite amendment. The percent bentonite required is evaluated in the laboratory
using site specific soils. Project specifications are then prepared to ensure that the soil and the
bentonite used in the field replicate that used in the laboratory. Once the bentonite is mixed
with the soil, it should be tested to evaluate the thoroughness of the mixing and the
concentration of the bentonite (12). A uniform mixing of bentonite is essential to the
performance of the soil-bentonite liner. This mixing may require a pug mill or asphalt pavement
surfacer to adequately blend the bentonite with on-site soils.
The installation methods and evaluation of the bentonite soil liner is the same as that for an
unamended clay liner. If the bentonite is mixed with the soil in place using a disk, careful visual
observation of the depth of mixing and the coverage of the bentonite over the liner area must
be made.
Geosynthetic Clay Liner (GCL)~
A GCL is essentially a pre-fabricated low permeability soil layer. The bentonite is usually
sandwiched between two geotextiles or adhered to a geomembrane. GCL's are manufactured
in 8 ft. and wider sheets and are shipped to the site in rolls. Typically the weight of bentonite
(or bentonite and adhesive) per square foot is specified and must be field verified.
The GCL barrier is installed by simply unrolling the sheets over a prepared subgrade. The
subgrade should be free of large rocks, ruts, and objects that could penetrate through the GCL.
Additionally, the subgrade must be stable, which can be checked by proof-rolling. Seaming of
the GCL barrier is typically limited to a minimum 6-inch overlap of adjacent sheets. The water
seal at the seam forms when the bentonite hydrates and "oozes" out from between the
geotextiles. Additional dry bentonite powder may be spread between the overlaps to improve
the seal.
Bentonite Slurries
Bentonite slurries are used in vertical barrier walls to displace the natural soils and construct a
low permeability barrier. Bentonite slurries are mixtures of 4 to 7% bentonite and water.
Quantities of materials used in the mix should be measured and recorded. After the mixing,
the bentonite slurry should be tested for gel strength using a Fann Viscometer. Typical gel
2-5
-------
strengths exceed 15 psf (240 kg/m2).
The bentonite slurry can be used "as is" to prevent the collapse of cut-off wall excavations or
blended with on-site soils to form a soil-bentonite slurry used in permanent barrier walls. The
soils should have 20-40% fines and are blended with the bentonite slurry until a paste is
formed. This paste should have the consistency of fresh mortar or concrete and flow easily.
Slurry uniformity is poor when dozers are used to blend the soil and bentonite. If dozers are
used, increased visual inspection and bentonite concentration testing may be required.
Concrete-Bentonite Slurries-
Concrete-bentonite slurries are used on sites where adequate soils to form soil-bentonite
slurries are not available or when increase strengths are needed. The concrete-bentonite
slurries are mixtures of approximately 18% concrete, 6% bentonite, and 76% water. The
concrete bentonite slurry is similar to the bentonite slurry above and the test methods used in
that section also apply to this material.
Because of the concrete, the concrete-bentonite slurry will hydrate and begin setting in 2-3
hours. The installation must be monitored to ensure that the slurry has not hydrated prior to
placement.
Compacted Clay Liners (CCL)
A CCL may be used as the primary moisture barrier in both waste liner and cover systems.
Achieving a low permeability in a clay liner requires a suitable clayey soil and proper
preparation and compaction of the soil. Test data (4,11) clearly demonstrate that the
permeability of a clay liner can be increased 100 to 1000 times if a single parameter in
preparation or compaction is neglected. Soil selected for use as a clay liner is specified using
soil plasticity (Atterburg Limits) and grain size distribution. Both parameters can be easily
monitored during actual field placement of the liner.
Construction of a clay liner requires proper soil preparation and correct compaction equipment
and technique. Soils used for clay liners should be processed to ensure that the soil water
content is as specified, the soil clods are no larger than 1 to 2 inches, and the maximum
particle size is less than required by the project specifications. For composite liners, the
maximum rock size in the last lift is frequently less than 1.0 inch (2.54 cm) to minimize
potential damage from rocks to the overlying geomembrane. Liner soil preparation is usually
done as the soil liner material is placed in a stockpile. Significant moisture adjustment should
not be attempted in the 24 hours preceding placement of the soil.
2-6
-------
Key construction guidelines for installing clay liners are related to both equipment and
operations. Compaction equipment must have feet that penetrate completely through a loose
layer of fill. Alternately, the loose lift thickness can be adjusted to maximize the efficiency of
the available compaction equipment. Compacted effort (compactor speed and number of
passes) should be consistent with the minimum effort established in a test strip. Additionally,
bonding between the layers of compacted clay must be enhanced by scarifying the surface of
the previous lift. The as-built clay liner must be tested to verify that it meets project
compaction criteria. This requires a field sampling program to measure soil moisture content
and density.
A clay liner is very susceptible to damage due to either desiccation or freezing. Clay liners left
exposed must be protected from desiccation using a surface sealant (acrylic sprays or light
membranes) or an additional layer of "sacrificial" soil. Soil cover also serves to prevent
freezing of the clay liner. Even a single cycle of freezing can significantly increase the
permeability of a clay liner. Testing a suspect soil liner for permeability requires either a large-
scale double-ring infiltrometer test or laboratory testing of undisturbed (UD) samples taken
from the soil liner.
2.2 Hydraulic Conveyances (Both Liquid and Gas)
Drainage layer components are designed to collect leachate beneath the waste or to collect gas
above the waste. Both functions require the drainage layer to be significantly more permeable
than the adjacent waste or soils. Thus filter systems, discussed in Section 2.3, are required
with all drainage systems. Newer geocomposite systems provide both the drainage media and
filter layer in a single commercial product. Field testing requirements for hydraulic conveyance
systems are presented on Table 2-2.
Natural Drains and Collectors
A sand or gravel drainage layer can be used as part of the leak detection component of a
waste containment system, as the primary drainage layer above the bottom liner, and as an
infiltrating storm water drain in the capping system. Soil drains provide a high permeability
medium into which liquids can easily drain to a network of collection pipes. The soil drain
usually consists of clean sand or gravel sorted to specific particle sizes by a quarry. In some
cases suitable sands or gravels are found on site, but this is unusual.
2-7
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TABLE2-2 HYDRAUUC CONVEYANCE SYSTEM ELEMENT TESTING/INSPECTION
ELEMENT
MATERIAL PROPERTIES/POST CONSTRUCTION CARE
FIELD TEST
NSTALLATION QUALITY VERIFICATION
FIELD TEST
Sand/Gravel/Drain
Collector
- Material Properties: Natural Water Content
Grain Size Distribution
Laboratory Hydraulic Conductivity
Moisture-Density Relationship
ASTM D2216
ASTMD422
ASTM D2434
ASTM D1557 or
ASTM D698
Post Construction: Natural drainage layers must be protected
from fines related to sedimentation
As Placed Properties
-Water Content
- In-Place Density
- Lift Thickness
* Visual observation of compactive effort as measured
by number of passes with a given compaction equipment
ASTMD2216
ASTMD2922
Visual
Visual
ieosynthetic Drain/
Collector
Material Properties: Weight persq. foot, transmissivity
under load, polymer properties (see geomembrane)
Certification
Post Construction: Geosynthetic drainage layers must be
protected from damage by direct trafficking of vehicles, and
movements caused by wind or man.
Placement Considerations
- Measure width of panel overlap
- Avoid folds, wrinkles, or damage to panels
- Provide temporary anchorage, e.g. sandbags
Visual
Visual
Visual
Pipes
00
- Material Properties: Polymer properties, pipe rating
- Mechanical Properties: Wall thickness and diameter
Certification
per ASTM D1248
Visual
Post Construction: Pipes must be protected from damage
by direct traffiking of vehicles, and movements prior to burial.
Placement Considerations
- Verify pipe perforations, placement, and connectors
in perforated pipe
- Verify location and grade of pipe
- Hydrostatic pressure test solid pipe joints
- Verify bedding material satisfies specifications
* Grain Size Distribution
In-Place Density _^
Visual
Survey
See Pipe Manual
'Butt Fushion'
Visual
ASTM D422
ASTM D2922
Sumps
- Material Properties: Polymer properties (see geomembrane)
- Mechanical Properties (prefabricated sump)
* Diameter and wall thickness
* Pipe penetrations per specs.
Certification
Visual
Visual
Placement Considerations
- Subgrade perpared free of rocks or sharp objects
- Bedding layer required for prefabricated sumps
- Verify location and grade of sump
* Seaming (see geomembrane)
Visual
Visual
Survey
Pumps
- Mechanical Properties
* Flow Rating
Certification
* Placement Considerations
- Installation per manufacturer's recommendation
Visual
Post Construction: Verify rated capacity with hydro test
-------
Drain materials are specified using a particle size distribution and samples should be taken for
laboratory grain size and permeability conformance testing. Soil drains typically require only
moderate to light compaction and the as-installed drain layer thickness should be verified.
Natural drainage layers must be protected by diversion berms or geotextiles from the
introduction of water borne fines from surface erosion of adjacent slopes.
Geosvnthetic Drains and Collectors
A geocomposite drain consists of a core material that provides a pathway for drainage and a
surrounding geotextile that prevents clogging of the core. Geocomposite drains can be used as
part of the leak detection component of a waste containment system, as the primary drainage
layer above the bottom liner, and as a lateral drain in the capping system. Similar to the soil
drain, a geocomposite drain provides a high transmissivity core through which liquids can easily
drain into a network of collection pipes. Geocomposite drains are pre-fabricated and come in
rolls or panels up to 300 ft. in length.
Geocomposite drains are available from suppliers who must certify that the materials supplied
meets the manufacturer's minimum specifications. The CQA officer must compare the
manufacturer's specifications with the project specifications. Laboratory conformance testing
should be performed on the drains under service conditions if differences exist between the
two specifications. The material delivered to the site should be inspected for general
compliance with project specifications and to check for damage during shipping.
Installation of the geocomposite drain requires no field testing. The drain should be inspected
to confirm that it is installed according to manufacturer's and project specifications. Overlaps
between adjacent roll ends or panels are particularly important with the proper overlap length,
orientation, and plastic ties used to bind the overlap. Geosynthetic drainage layers must be
protected from damage by vehicle traffic, wind or other disturbances. The layer should also be
protected from fines carried by surface erosion during construction.
Plastic Pipes
Both perforated collection and solid transmission pipes are used in the leak detection systems,
the primary leachate collection drain, the lateral drain in the cap, and to carry stormwater and
leachate away from the waste containment system. Collection and transmission pipes are
constructed from a variety of plastics and can be designed for gravity flow lines as well as low
or high pressure lines, depending upon the application.
Collection and transmission pipes are available from suppliers who must certify that the
materials meet manufacturer's specifications. The material delivered to the site should be
2-9
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inspected for general compliance with the project specifications and to check for damage
during shipping.
Installation of collection and transmission pipes should be field inspected to verify that the
location and grades of the pipe and joints, and the bedding material and backfill meet project
specifications. Perforated pipes require additional inspection of the perforations (hole diameter
and spacing) and pressure pipes require hydrostatic pressure testing (see Appendix A).
Sumps
Leachate sumps are located in both the primary leachate collection layer and the bottom/lower
leak detection layer. Sumps are located at low points in the liner and act as basins in which
the leachate can be collected. From the sumps, the leachate is either drained out of the waste
containment system by gravity or pumped out. The sumps can be a simple depression in the
composite liner or a pre-manufactured plastic basin that is set in the clay liner so that its top is
flush with the geomembrane liner. The geomembrane is fusion-welded to a flange on the
upper edge of the sump. Pre-manufactured sumps eliminate difficult-to-test field seams or
complex grading.
t
If leachate sumps are fabricated on site, then they will be made from the same materials as the
liner system, so certification of the liner materials will already have been provided. If the
leachate sumps are pre-fabricated then the supplier must certify that they meet project
specifications. The sumps delivered to the site should be inspected for general compliance
with the project specifications and any damage.
Sumps are the only area of a waste containment system that will continuously receive
leachate. As such, any defect in the sump may result in a continuous long-term leak. The
seams made at this location are difficult to test due to their short length and tight angles.
Destructive samples should be kept to a minimum due to the difficulty of repairs in the vicinity
of the sumps.
Pumps
The leachate can be drained by gravity from the waste containment system or it can be
pumped out the system using a submersible pump. The pumps used to move leachate are
manufactured for harsh environments and can be powered by electricity or compressed air.
Leachate pumps are available from suppliers who must certify the pumps meet the
manufacturer's specifications. The pumps should be inspected when delivered to the site to
confirm that they were not damaged during shipment.
2-10
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Installation of the pumps should be done in accordance with the manufacturer's instructions.
All electrical connections, power requirements, insulation, grounding, and piping should be
installed and used as specified by the manufacturer. These items should be inspected during
installation to verify that they follow the manufacturer's recommendations. The pump should
be tested, using water, to verify that it is working properly.
2.3 Filters
Filter layers must provide for long-term movement of water through the layer while at the same
time limit the movement of waste or soil particles across the layer. Too tight a filter will
quickly clog while too loose a filter will result in an excessive loss of solids through the filter.
Biological growth can also impact filter layer performance and is currently being studied by the
EPA. Field verified material properties and installation factors are given in Table 2-3.
Sand/Gravel Filter
A soil filter is used to prevent very fine soil and waste particles from entering into a drain,
accumulating, and eventually clogging the drain. Typically, soil filters consist of sand and/or
gravel which has been screened to a specified particle size. The sand/gravel filter should have
a particle size smaller than the drain particle but larger than the infiltrating particle. The filter
may consist of one layer or several successively graded layers depending upon the
performance objectives of the designer. A soil gradation requirement will be provided for each
sand/gravel filter layer in the project specifications.
The sand and gravel filter should be laboratory tested to ensure that the grain size distribution
meets the project specifications. Individual filter layers are also field tested to ensure that the
installed filters meet compaction and thickness specifications.
Geotextile Filter
A geotextile filter is used to prevent very fine soil and waste particles from entering into a
drain, accumulating and eventually clogging the drain. The geotextile filter is selected by the
designer based on its opening size and permittivity. Suppliers of geotextile filters must certify
that the materials meet the published manufacturer's specifications. Published manufacturer
specifications must also satisfy the specific geotextile specifications for the project.
Conformance testing of the geotextile is recommended for critical filter applications (see Table
2-3). The geotextile arrives on the site in rolls for installation. The material delivered to the
site should be inspected to ensure compliance with the project specifications and to check for
damage during shipping.
2-11
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TABEL2-3 FILTER SYSTEM ELEMENT TESTING/INSPECTION
ELEMENT
MATERIAL PROPERTIES/POST CONSTRUCTION CARE
FIELD TEST
INSTALLATION QUALITY VERIFICATION
FIELD TEST
Sand/Gravel Fitter
ro
ro
* Material Properties:
- Natural Water Content
- Grain Size Distribution
- Laboratory Hydraulic Conductivity
ASTM D4959
ASTM D422
ASTM D2434
* Placement Considerations
- Soil water content if specified
-Soil density if specified
-Lift thickness
- Verify compactive effort if density specified
Post Construction: Natural filter must be protected from
surface water sediments prior to burial
ASTM D4959
ASTM D2922
Visual
Visual
Geotextile Filter
* Polymer Properties: Density, Denier, Polymer Type, UV Stability
* Mechanical Properties:
- Weight per square yard
- Tensile Strength (grab tensile)
- Permittivity
-AOS
- Puncture Strength
Certification
Weigh
ASTM 4632
ASTM D4491
ASTM D4751
ASTM D4833
* Placement Considerations
- Verify overlap of geotextile panels
- Verify no folds or wrinkles exist
- Verify use of temporary anchorage if required
- Verify sewn seams
Visual
Visual
Visual
Visual
Post Construction: Protect geotextile from surface water
sediments and from wind or man caused movement
-------
The installation of the geotextile should be inspected to verify that panel overlap or sewn
seams meet manufacturer's requirements. Additionally, any folds or wrinkles or damage to the
panels must be eliminated and temporary restraint provided if necessary.
2.4 Erosion Control
Final cover systems on waste containment systems must be designed to limit the infiltration of
surface water while at the same time require only limited maintenance for an extended period
of time. Maintenance on such cover systems is significantly influenced by the degree of
erosion that is allowed. For example, the EPA suggests that erosion be limited to less than 2
tons of soil per acre per year. The selection of a final cover system may also be influenced by
the end use of the cover, e.g. park, or climatic conditions, e.g. lack of rain. Field inspection
requirements for erosion control systems are presented on Table 2-4.
Vegetation and Topsoil
Surface vegetation may be the most economical erosion control system in those regions where
rainfall exceeds evapo-transpiration. The vegetation will typically be a native grass tolerant of
local climatic conditions. It should also limit spontaneous vegetation by non-desirable plants,
germinate rapidly, and be compatible with the cap profile. Vegetation having exceptionally
aggressive tap roots should be avoided.
Vegetation is usually bid on a cost per acre basis with a minimum weight of seed per acre
specified. The seed placement cost should include required soil preparation (tilling, fertilizers,
etc.), hydromulching, and any additional short-term erosion control required until the vegetation
is established. Suppliers of fertilizer and seeds must certify that the fertilizer and seed meet
project specifications. Placement of the seeds should be made in accordance with the
supplier's instructions. The application rate, time of year, soil preparation, hydromulching, and
watering schedule should be observed and documented.
Topsoil is used to support the growth of the vegetation on the cap and other locations that
require vegetation. The topsoil is usually obtained on site from a stockpile cut from the
construction area or from a nearby borrow area. Project specifications are typically vague
regarding topsoil properties, but the organic content of the topsoil should be at least 3 to 5
percent, to support plant growth. Field monitoring is commonly limited to verification of the
final layer thickness.
2-13
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TABLE 2-4 EROSION CONTROL ELEMENT TESTING/INSPECTION
ELEMENT
Vegetation
Topsoil
Asphalt Cap
Concrete Cap
Rip-rap Cap
MATERIAL PROPERTIES/POST-CONSTRUCTION CARE
* General Properties: Seed Blend, % Weed, etc,.
Post Construction: Watering schedule must be maintained,
protect from erosion and traffic prior to full growth.
* General Properties: (if given in project specifications)
- Natural Water Content
- Grain Size Distribution
- Soil PH
- Organic Content, and
- Nutrient Content
Post Construction: Protect from surface erosion prior
to crop development
* Asphalt Mixture Properties
- Percent Asphalt
- Grain Size Distribution of Aggregate (if specified)
- Compressive Strength
Typically use certification by batch plant
* Concrete Mixture Properties
- Measure temperature of the mix
- Determine how long truck has been on road
- Slump test
- Test for amount of entrained air in concrete
- Make test cylinders for compression strength testing
- Obtain batch ticket for each truck
- Inspect Rebar
* General Properties
- Rock Size Distribution
FIELD TEST
Certify
ASTM D4959
ASTM D422
ASTM D4972
ASTMC311
ASTM D915
ASTMD422
ASTM D1074
ASTM C143
ASTM C231
ASTM C31
ASTM C39
Visual
ASTM D422
INSTALLLATION QUALITY VERIFICATION
* Placement Considerations
- Time of placement per specs
- Soil preparation per specs or seed supplier
- Hydromulchlng per specs or seed supplier
- Watering schedule per specs or seed supplier
* Placement Considerations
-Lift Thickness
- Water Content (if specified)
- Density (if specified)
- Surface Preparation (if specified)
* Placement Considerations
- Verify thickness of asphalt being placed
- Verify weather is acceptable during placement
- Density of asphalt (field test)
- Ensure continuity of joints start of each day
- Verify temperature of asphalt during placement
* Placement Considerations
- Observe placement to ensure that aggregate is not
separated from fines in the concrete mix
- Verify vibration of concrete to remove voids
- Measure location of construction and expansion joints
- Observe application rate of curing compound applied
over fresh concrete surface
* Placement Considerations
- Verify lift thickness
- Check that geotextile is beneath rip-rap specified
- Observe placement of stone to confirm maximum
drop height and 'rolling' of stones
FIELD TEST
Visual
Visual
Visual
Visual
Visual
ASTM D4959
ASTM D2922
Visual
Visual
Visual
ASTM 2950
Visual
Visual
Visual
Visual
Visual
Visual
Visual
Visual
Visual
-------
Hardened Layers
Hardened covers provide an alternative to vegetative systems in arid regions that lack
sufficient natural moisture. Additionally, hardened systems have been used to provide traffic
and parking areas after closure of the waste containment facility. Asphalt and concrete
hardened covers are normally limited to slopes less than 10 degrees.
Asphalt Cap
An asphalt cap can be used to protect a capping system and provide a potentially usable area
over a waste containment system (e.g. a parking lot). The asphalt cap can replace the
vegetation, topsoil, drainage layer, and the biotic layer in the cap. In this application, the
asphalt layer must provide the erosion resistance of the vegetation/topsoil, the lateral flow
capacity of the drainage layer, and the protection of the biotic layer. The porous asphalt layer
consists of an asphalt pavement system similar to that used in roadway construction. The
asphalt supplier must certify that the materials meet the project specifications. Asphalt
delivered to the site should be inspected for general compliance with these specifications. The
temperature of the delivered asphalt mix should be measured and the batch ticket for each
truck load should be filed for future reference.
During installation, the thickness, temperature, and density of the asphalt should be measured.
Additionally, the weather must be monitored to avoid rain or cold temperatures that would hurt
asphalt placement.
Concrete Cap--
Like asphalt, a concrete cap can protect a capping system and provide a potentially usable area
over a waste containment system (e.g. a parking lot). The concrete cap replaces the
vegetation, topsoil, drainage layer and the biotic layer in the cap. The concrete layer is similar
to that used in roadway construction. Concrete suppliers must certify that the concrete meets
project specifications.
The concrete delivered to the site should be inspected to determine how long the trucks have
been on the road and if the concrete can be used. Material properties identified in the project
specifications should be verified (see sample specifications in Table 2-4). The foundation
below the concrete should be inspected for levelness, strength and the presence of water.
The concrete pour should be observed to verify that the aggregate is not separated from the
fines in the concrete mix, and that the construction and expansion joints are properly located.
The application rate of a curing compound over the concrete surface should be measured.
2-15
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Rip-Rap Cap ~
Rip-rap consists of natural stones ranging in size from approximately 1 inch to stones that
weigh hundreds of pounds. Layers of these stones provide a significant impediment to wind
and water related erosion. Rip-rap layers are commonly underlain with a geotextile filter to
limit potential erosion of underlying fines. Field testing is typically limited to verifying that the
delivered rip-rap meets project specifications for particle size.
The installation should be monitored to verify that thickness of the rip-rap layer meets project
specifications. Placement of stone or rip-rap should be monitored to ensure that drop heights
are limited. An underlying geotextile should be inspected for damage due to stone placement.
When larger stones (> 60 pounds) are placed over a geotextile fabric, drop height stone is
commonly limited to 18 inches (45 cm). Alternately, a soil layer of 6 inches (15 cm) can be
placed over the geotextile to provide a cushion and protect it from damage during rip-rap
placement.
2.5 Protective Layers
Waste containment systems and covers frequently include layers that are intended to protect
functional layers. Outer protective layers include the surface erosion control layers discussed
above (section 2.4). This section discusses interior protective layers that function even after
they are buried within the system. While some of the protective functions may be short-term
or seasonal, e.g. a protective soil layer placed over a liner to protect it from freezing, most
protective functions are long-term and are essential to the success of the waste containment
system. Table 2-5 presents field tests that should be conducted to ensure material integrity
and installation quality of protective layers.
Biotic Barrier
A Biotic barrier is used in the cap of a waste containment system to prevent small burrowing
animals and plant roots from penetrating the drainage layer or the low permeability barrier. The
biotic barrier usually consists of a 3 foot (1 m) thick layer of stone or cobbles. Vegetative
intrusion can also be limited by herbicide impregnated geotextiles that provide time release
protection. Field inspection is typically limited to verifying that the stone particle size and layer
thickness meet project specifications.
2-16
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TABLE 2-5 PROTECTIVE LAYER ELEMENT TESTING/INSPECTION
ELEMENT
Biotic Barrier
Geotextile
Soil Protective Layer
MATERIAL PROPERTIES/POST CONSTRUCTION CARE
* Mechanical Properties
- Grain Size Distribution
Post Construction: Protect from stormwater sediments
* Polymer Properties: Density, Denier
* Mechanical Properties: Per project specifications
- Mass per Unit Area
-Thickness
Post Construction: Protect from wind damage
* Material Properties
- Natural Water Content
- Grain Size Distribution
Post Construction: Protect layer from surface water
erosion and dessication ,
FIELD TEST
ASTM D422
Certification
Measure
ASTM D4959
ASTM D422
INSTALLATION QUALITY VERIFICATION
* Placement Considerations
- Verify lift thickness
- Verify specified soil/geotextile beneath ston
- Observe placement of stone per specs
* Placement Considerations
- Verify overlap of adjacent rolls
- Eliminate fold or wrinkles during installation
- Provide temporary anchorage per specs.
* Placement Considerations
- Water Content
- In-place Density
- Lift Thickness
- Visual Observation of Compaction Effort
FIELD TEST
Visual
Visual
Visual
Visual
Visual
Visual
ASTM D4959
ASTM D2922
Visual
Visual
-------
Qeotextile Protective Layer
A protective layer over the bottom liner, leachate detection layer and the primary leachate
collection layer is required to protect these components from damage during construction and
waste placement. The geotextile protective layer is normally a nonwoven material selected
according to its unit weight (ounces/yard2). The heavier the nonwoven material, the more
cushion it provides. Suppliers of geotextile protective layer materials must certify that the
geotextile meets the manufacturer's specifications.
The geotextile arrives on the site in rolls for installation. The material delivered to the site
should be inspected for general compliance with project specifications and damage from
shipping.
Soil Protective Layer
A soil protective layer over the liner, leachate detection layer and the primary leachate
collection layer is required to protect these components from damage during waste placement
and from the extremes in the weather. The soil should be selected for its resistance to
erosion, strength, and stability on the side slopes of the waste containment system. Typically,
an on-site soil can be used as the protective layer. The soil should be laboratory tested to
verify that they meet the project specifications. Typical soil protective layer specification
considerations are given in Table 2-5.
Special attention should be given to the installation of a soil protective layer over a
geomembrane liner. Such installations require less rigorous compaction specifications for the
first lift to avoid damaging the geomembrane during compaction.
2.6 Earthworks
Construction or closure of waste containment systems typically requires construction of
earthen containment structures, such as dikes and berms, and the development of stable
working benches (surfaces) over weak wastes or contaminated soils. Due to cost restrictions,
earth work is usually done with either on-site or local soils. In view of the diverse nature of
this material, close monitoring during construction is often necessary to achieve design
conditions. Weak or soft spots in compacted soil are commonly detected by proof-rolling using
a loaded dump truck. Any soil experiencing excessive rutting should be recompacted or
excavated and replaced. Common field tests of earthwork are shown on Table 2-6.
2-18
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TABLE 2-6 EARTHWORK ELEMENT TESTING/INSPECTION
ELEMENT
Structural Fill
Soil Bedding Layer
Geotextile/Geogrid
Bedding Layer
MATERIAL PROPERTIES/POST CONSTRUCTION CARE
* Mechanical Properties
- Natural Water Content
- Grain Size Distribution
- Moisture Density-Relationship
- Atterburg Limits
Post Construction: Protect layer from surface water erosion
* Mechanical Properties
- Natural Water Content
- Grain Size Distribution
* Polymer Properties
* Mechanical Properties
- Weight per square yard
- Strength
-Wide-Width Strength
FIELD TEST
ASTM D4959
ASTM D422
ASTM D1 557/698
ASTMD4318
ASTM D4959
ASTM D422
Certification
Measure
ASTM D4632
ASTM D4595
INSTALLATION QUALITY VERIFICATION
* Placement Considerations
- Soil water content as specified
- Soil density as specified
- Lift thickness verified
* Placement Considerations
- Soil water content as specified
- Soil density as specified
- Lift thickness verified
- Verify final grade
* Placement Considerations
- Verify overlap of adjacent rolls
- Eliminate fold or wrinkles during installation
- Provide temporary anchorage if required
FIELD TEST
ASTM D4959
ASTM D2922
Visual
ASTM D4959
ASTM D2922
Visual
Survey
Visual
Visual
Visual
ro
CO
-------
Structural Fill
A structural fill is designed to support its own weight and that of any overlying systems
without experiencing excessive deformation. Such fills are typically placed to develop a
minimum shear strength or compressibility as assumed in design. Laboratory shear strength or
compaction tests, made prior to construction, are used to establish acceptable
moisture/density requirements for such fills.
Fill soils must be inspected at the site to ensure that they are suitable and have low plasticity
(i.e., plasticity index <10) and no large stones ซ6 inches). Compacted soils should be tested
to verify that they achieve the minimum dry density established by the project specifications.
Soil Bedding Layer
A soil bedding layer is used to level the waste surface immediately below the cap. The
bedding layer provides a smooth and stable working surface for the construction of the cap
and is usually made from an on-site soil with good strength properties. Other than proof-rolling
and measuring the final grade, little field testing is performed on bedding soils.
Geotextile or Geoqrid Bedding Layer
A geotextile or geogrid bedding layer is used to level the waste surface and bridge any voids
immediately below the cap. Additionally, the bedding layer provides a smooth and stable
working surface for the construction of the cap. The geotextile or geogrid must have high
tensile strength and be puncture resistant. Suppliers of geosynthetic bedding materials must
certify that the materials supplied meet the manufacturer's specifications. The geosynthetics,
which are delivered to the site in rolls, should be inspected to ensure general compliance with
the project specifications and to check for damage.
The installation is usually monitored to confirm that geotextile or geogrid overlaps meet the
manufacturer's specifications. Six (6) inch (15 cm) overlaps are common. Conformance
testing of the geotextiles or geogrids can be performed as indicated in Table 2-6.
2.7 References
2-1
2-2
U.S. EPA. 1991. Design and Construction of RCRA/CERCLA Final Covers. Seminar
Publication EPA 625/4-91/025, Office of Research and Development, Washington,
DC 20460.
U.S. EPA. 1991. Design, Construction, and Operation of Hazardous and Non-
2-20
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2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
Hazardous Waste Surface Impoundments. Technical Resource Document EPA
530/SW-91/054, Office of Research and Development, Washington, DC 20460.
U.S. EPA. 1989. The Fabrication pf Polyethylene FML Field Seams. Technical
Guidance Document EPA 530/SW-89/069, Office of Solid Waste and Emergency
Response, Washington, DC 20460. (Superseded by REF 2-5)
U.S. EPA. 1989. Requirements for Hazardous Waste Landfill Design, Construction,
and Closure. Seminar Publication EPA 625/4-89/022, Center for Environmental
Research Information, Office of Research and Development, Cincinnati, OH 45268.
U.S. EPA. 1991. Inspection Techniques for the Fabrication of Geomembrane Field
Seams. Technical Guidance Document EPA 530/SW-91/051, Risk Reduction
Engineering Laboratory, Cincinnati, OH 45268.
U.S. EPA. 1987. Geosynthetic Design Guidance for Hazardous Waste Landfill Cells
and Surface Impoundments. EPA/600-S2-87/097, Hazardous Waste Engineering
Research Laboratory, Office of Research and Development, Cincinnati, OH, 45268.
Koerner, R.M., Designing with Geosvnthetics. Prentice-Hall, Englewood Cliffs, NJ,
1990.
Standards for Specifying Construction of Airports, Advisory Circular 150/5370-
10A, U.S. Department of Transportation, Federal Aviation Administration,
Washington, DC, 2/17/89.
ACI Manual of Concrete Practice, Part 2, Construction Practices and Inspection
Pavements, Detroit, Michigan 48219, 1984.
Annual Book of ASTM Standards, American Society for Testing and Materials
Philadelphia, PA 19103, 1990.
Elsbury, B.R., et al., "Lessons Learned from Compacted Clay Liners," J.
Geotechnical Engineering, ASCE, November 1990, 1641-1660.
U.S. EPA. 1987. Construction Quality Control and Post-Construction Performance
Verification for Gilson Road Hazardous Waste Site Cutoff Wall. EPA/600/2-
87/065.
2-21
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SECTION 3.0
Field Sampling Strategies
Key elements of a waste containment system should be sampled and tested to verify that the
materials meet project specifications and that they are being installed in accordance with the
design drawings. Sample tests can also be used to monitor the construction process, predict
trends in the quality of the installation, and detect sub-quality construction trends. A field
sampling strategy in its simplest form can be implemented by "randomly" picking out a half
dozen or so samples for testing, and accepting the area or lot if all the tests fall within the
limits of the project specifications. A "lot" is a clearly defined production unit such as a given
days batch of grout or a clearly identified production run of a geosynthetic product. While this
may be an appropriate sampling plan in some cases, the risks associated with this plan should
be known before implementing it. If factors such as sample size, sample location, and
acceptance criteria are not correctly applied, the test results may not represent the quality of
the area or lot being tested.
A sampling plan, whether it is implemented in the field or in a manufacturing plant, has several
distinct parts:
1) Delineation of the sample area:
2)
3)
Determination of the number of samples bv one of the following methods:
a) Following the project specifications;
b) Using the Sample Density Method, which specifies a minimum number of tests
per unit length, area or volume;
c) Using an Error of Sampling Method, such as ASTM E-122;
d) Using Sequential Sampling;
Selection of the sample locations by one of the following methods:
a) Include every potential sample location -- Census or one-hundred percent
(100%) sampling of the area or lot;
b) Select locations using the judgement of the project inspector - Judgmental
Sampling;
Include every "nth" potential sample location starting with a randomly selected
starting location corresponding to a randomly selected number less than "n".
(For example, select every 10th location starting with the 9th location, ie.
locations corresponding to 9, 19, 29, etc.) - Fixed Increment Sampling;
Selecting sample locations completely at random using a random number
generator ~ Strict Random Selection;
Subdividing the test area into logical subareas and randomly selecting locations
within each subarea ~ Stratified Random Selection;
0
d)
e)
3-1
-------
4} Obtaining and testing the samples using the appropriate methods;
5) Acceptance or rejection of the area or lot based on either:
a) comparison of the sample statistics (mean, variance, etc. of the test values)
with the limits presented in the project specifications;
b) comparison of the sample statistics with pre-determined limits calculated to
keep the construction process in control.
6) Development of a remedial action plan to change the construction process if the
quality of the construction declines
7) A clear method of historical documentation so that all of the original records,
including the sample locations, test results, and the analysis of the test results
(sample statistics), are available for project certification or future litigation.
3.1 Delineating the Area or Lot Being Tested
The area or lot being tested must be divided into potential test locations that can be clearly
identified at a later time. The test area or lot should therefore be tied to an easily identified
fixed reference point such as a manhole or the crest of a slope (see Figure 3-1 a). Distance
from the fixed location to the sample can be measured along a linear axis or using a pair of
coordinate axes. For most sample selection schemes it is necessary that a numbering system
be used to reference the potential sample locations or items. For example, samples from a
geomembrane seam are referenced by measuring distance along the seam. Destructive testing
of pipe, however may require samples of a specific length (e.g. 3.feet). The pipe can be
marked off in 3-foot intervals with each segment given a number that identifies the sample
(see Figure 3-1 b). In delineating an area for sampling, a coordinate pair of axes must be used
instead of a single axis. The sample locations can be delineated by distance measurements
along both axes, or by assigning numbers to sample areas corresponding to subdivisions of an
overall grid (see Figure 3-1 c). Each sample should be marked or tagged to provide clear
documentation of the test location.
3.2 Determining the Number of Sample Locations
The number of sample locations required for testing a given element is normally included in the
project specifications. Sometimes, specifications for sample locations determine the number of
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samples, e.g. every 't' section of a seam in a flexible membrane liner must be tested. Apart
from these instances, three methods sample density, error of sampling, sequential sampling -
- are used to determine the number of samples to be tested.
Sample Density Method
The sample density method specifies the minimum number of sample locations per unit of
measure (sample density) for a given element. This method is popular with regulatory agencies
since it is readily applied and verified. It can be applied to linear systems (e.g. seams), surface
areas (e.g. geomembranes), and volumes (e.g. grout). Table 3-1 shows typical sampling
densities for all three of these element types. Note that sampling densities can be given in
either area or volume units. For example, clay liner testing can be specified as number of
tests/acre fill or number of tests/volume of fill. Common sampling densities for waste
containment elements are presented in Appendix A.
Error of Sampling Method
The error of sampling method is used to determine the number of test samples required to
represent the quality of the entire area or lot with an acceptable sampling error. The sampling
error is defined as the maximum allowable difference between the sample estimate of lot or
area quality and the measure of quality that would be determined by 100% sampling.
Calculation of the number of tests needed to estimate the proportion of defective areas of a
soil liner, using ASTM E-122, is shown in Figure 3-2.
The number of samples required by ASTM E-122 is a function of the importance of the element
being tested (K), the allowable difference between actual and indicated quality (E), and an
estimate of the actual number of defects in the area or lot (P). Calculations for a minimum
number of tests for a clay liner are shown on Figure 3-2. Since a clay liner is a very critical
element of a waste containment system, the K factor is 3. The allowable difference between
the actual quality and the sample estimate of quality is set at 5 percent or P = 0.05. An
estimate of the actual number of defective tests in a given lot or area (P) requires some prior
knowledge of similar applications which may require reviewing past records. This estimate can
be adjusted as the project progresses to reflect actual site experience.
A minimum of 171 tests must be performed on the example clay liner to satisfy our assumed
requirements. Note that ASTM E-122 does not incorporate the size of area or lot. In the case
of a two foot thick clay liner, the test density (yd3/test) is a function of the size of the liner as
shown in Figure 3-2. Thus the 171 tests reflect approximately 1 test per 300 cubic yards of
clay for a 15 acre site and 1 test per 500 cubic yards for a 25 acre site. Common sampling
densities for clay liners range from 1 test per 250 to 500 cubic yards of clay (see Appendix A).
3-4
-------
TABLE 3-1 EXAMPLES - SAMPLE DENSITY METHOD
ELEMENT/SYSTEM TYPE PARAMETER
Geomembrane/Linear DT Seam Test
Clay Liner/Area
Clay Liner/Volume
Grout/Volume
Density
Density
Slump
TEST METHOD
ASTMD413
ASTMD3083
ASTMD2922
or
ASTMD2937
ASTMD2922
or
ASTMD2937
ASTMC143
MINIMUM
TESTING FREQUENCY*
17500 Ft. Seam
5/acre/6" lift
1 /500 YD3
1 /500 YD3
For landfill liners - the minimum testing frequency may be decreased (e.g. 1/1000 ft of-
seam) for caps or temporary applications as required. .
3-5
-------
REFERENCE: ASTM E-122 ERROR OF SAMPLING METHOD
DEFINE NUMBER OF TESTS (n) TABLE - k FACTOR
n - (K/Ef P(1-P)
WHERE P * ESTIMATE OF THE FRACTION OF
DEFECTIVE TESTS PER UNIT
E - MAXIMUM ALLOWABLE DIFFERENCE.
BETWEEN THE ESTIMATES OF QUALITY
FROM n SAMPLES AND 100%
TESTING
K = A FACTOR CORRESPONDING TO THE
PROBABILITY THAT THE SAMPLING
ERROR WILL EXCEED E. (SEE
TABLE)
K PROBABILITY OF . IMPORTANTCE OF
ERROR EXCEEDING E ELEMENT
3 0.003(3 in 1000)
2.58 0.01 (10 in 1000)
2 0.045(45 in 1000)
1.96 0.05 (5 in 100)
1.64 0.10 (10 in 100)
VERY CRITICAL
CRITICAL
NOT CRITICAL
EXAMPLE APPLICATION
DEFINE NUMBER OF MOISTURE/DENSITY TESTS FOR SOIL LINER
ASSUMPTIONS:
p = 5% ={>5 OUT OF 100 TESTS ARE DEFECTIVE
E = 5% ==> ALLOWABLE DIFFERENCE = ฑ5%
K = 3 ==> VERY CRITICAL ELEMENT
60O
CO
n = (3/0.05) 0.05 (1-0.05) = 171 TESTS
500
.400
NOTE: ACTUAL TEST DENSITY IS A FUNCTION Q
OF VOLUME OF SOIL LINER, e.g. fe
15 ACRE SITE WITH 2 ft. LINER "
300
200
10O
7!
./ I
/ I
I
t 11 i
TEST DENSITY = 48642
= 248 YD/'TEST
0 5 -10 15 20 25
ACRES
FIGURE 3-2 NUMBER OF SAMPLESHERROR OF SAMPLING METHOD
3-6
-------
Sequential Sampling
The Sequential Sampling scheme is designed to minimize the required sample number when the
quality of the area or lot is either exceptionally good or very poor. Most sampling plans require
a fixed sample size (determined prior to construction) which is independent of the results
observed at the first sample locations. Sequential sampling uses the results of the tests as
they are conducted to adjust the number of samples required and the acceptance criteria.
Areas or lots with high or low quality require a smaller number of tests than those with
marginal quality. Note that the sequential sampling method defines both the number of
samples and the acceptance criteria which depend on the results of earlier sample test results.
A sequential sampling plan requires that after each sample location, or small group of locations,
is evaluated that one of three decisions is made about the test area or lot from which the
sample(s) was(were) taken:
ซ The test area is accepted
The test area is rejected
The evidence is not sufficient to make a decision without an
unacceptable risk of error
These three decisions are illustrated by the three regions on the chart shown on Figure 3-3. If
the last decision is made, more sample locations must be selected and evaluated. This process
is continued until the test area is accepted or rejected or a limit on the number of test is
reached e.g. all. Typically a graph as shown in Figure 3-3 is used to implement this sampling
scheme. , .
Four variables must be determined to implement this sampling plan. These variables include:
P, = acceptable proportion of defective sample locations in
a test area;
P2 = unacceptable proportion of defective sample locations
in a test area;
6 = the probability of rejecting an acceptable test area, (the
, ,-.. quality of the test area is acceptable but the sample
results indicate that it is unacceptable);
IS = the probability of accepting an unacceptable test area.
(the quality of the test area is unacceptable but the
sample results indicate that it is acceptable).
These values, which are selected by the person designing the sampling plan, should reflect the
desired precision of the test results, the importance of the tested element and the cost and
delays due to sampling and testing. The consequences of a wrong decision are key
3-7
-------
REFERENCES (6,7,8)
DEFINE ACCEPTANCE CRITERIA
P, = % DEFECTS ACCEPTABLE
P2 = % DEFECTS UNACCEPTABLE
8 = % PROBABILITY OF REJECTING A TEST
AREA WITH QUALITY GREATER THAN 1=
$ = % PROBABILITY OF ACCEPTING A TEST
AREA WITH QUALITY LESS THAN Pz
DEFINE ACCEPTANCE/REJECTION CHART
A = log((!i/R)*((100-F?)/(100-l?)))
h, = log((100-<5)//?)/A
h2=
S = log((100-R)/(100-|3))/A = SLOPE
EXAMPLE APPLICATION
DEFINE ACCEPTANCE CRITICAL FOR DRY
DENSITY OF STRUCTURAL FILL.
ASSUMPTIONS:
P=5 l==10 5=10 (3 =20
A = log((10/5)*((100-5))/(100-10))) = 0.32
h, - log((100-10)/20)/A = 2.04
h,=* log((100-20)/10)/A = 2.82
S = log((100-5)/(100-10))/A = 0.07
/. MINIMUM OF 40 TESTS
T
REJECT THE TEST AREA
TOTAL NUMBER OF TESTS
8
2--
4--
REJECT THE TEST AREA
0 10 20 ^&T 4"0 50 60 70
,L NUMBER OF TESTS
FIGURE 3-3 NUMBER OF SAMPLES-SEQUENTIAL SAMPLING
3-8
-------
consideration when selecting these values or limits. If the constraints are too rigid, the
required sample size (number) will be so large that the associated costs are prohibitive. Hence
it is necessary to tradeoff up-front costs for sampling, the costs of redoing a lot rejected in
error (the sample gave misleading results indicating a good lot was defective), and the costs of
failing to detect a faulty lot until much time has passed. If the cost of rejecting good material
is high then 6 should be small. If on the other hand acceptance of inferior material is high, the
typical situation for environmental materials, then fc should be small.
An application of sequential sampling acceptance criteria to structural fill is given in Figure 3-3.
Structural fill is an element that, while important, is less critical to the success of a waste
containment system than such elements as clay or geomembrane barriers. Hence in this
situation the decision maker may be willing to tolerate more defects (larger P, and P2) and be
less concerned about incorrect decisions (larger 6 and B). If so, the number of required
samples will be less than for materials which are more critical to the success of a fill. The
importance of an element is reflected in the selection of the four variables required to define
the acceptance chart.
Example (Figure 3-3)
The percent defects in an unacceptable fill (P2) is assumed to be 10%. This is twice as
tolerant as the criteria used in the previous example for clay liner material. The percent defects
in an acceptable area (P,) was selected as the mean of the acceptance range ซ10%).
Percent probabilities for accepting a defective test area (IS) or rejecting an acceptable test area
(6) are selected in the example to reflect the lower importance of the structural fill. For a
critical element, B will be smaller and 6 could be larger since it is more important that a
defective critical element not be accepted.
A minimum of 40 density tests must be performed to get acceptance of the structural fill using
the sequential sampling chart developed above. If no defective density tests occur in these
forty (40) tests, then the structural fill is accepted. If two (2) or more defective locations are
found the lot is rejected. If one (1) defective location is found then additional sample locations
must be selected and evaluated. Testing must continue until the chart indicates that the lot is
acceptable or must be rejected.
3.3 Selection of Sample Locations
Field sampling strategies for selecting a single sample location may follow several sample
location criteria. This is particularly true for critical elements such as the seams of
geomembrane liners. The protocol for locating test samples on seams includes all of the
following criteria:
r 3-9
-------
For Non-Destructive Testing
For Destructive Testing
100% Testing
1 per 500 Feet (Incremental)
Judgmental
Minimum 1 per seam (Stratified)
Thus the sample location strategies presented in this section may be combined for a given
element.
100% Sampling
In theory, determining the true quality of a product would require sampling the entire product --
which is known as 100 percent sampling. Although non-destructive testing methods can be
used to sample and test all of the product or test area, this requires a significant investment of
time and capital. For these reasons, a 100% sampling plan is used only to test the most
critical elements in waste containment structures; the seams in the synthetic liners used in
landfills, waste piles and waste ponds. Because a defect in the seam will allow a release of
waste, 100% testing is considered necessary-
Since a 100% sampling plan is rigorous, the sampling and testing program should be designed
to minimize inspector fatigue. A sufficient number of testing crew breaks and shift changes
should be used to avoid errors in the sampling and testing program.
The 100% Sampling Plan:
Step 1 Develop a means of delineation and measurement that can be used to determine
the sample locations over the entire test area. Since this a 100% sampling plan,
the delineation will not be used for sample selection but will serve to ensure that
all locations are tested and to locate any defective locations.
Step 2 Test the entire area or lot using a non-destructive test method (see Appendix A).
Careful documentation must be made of the starting and stopping locations,
material batch numbers, installation crews, and other variables that may affect the
testing results. Compare the results of testing to the project specifications. All
areas that do not meet the project specifications will be rejected and removed or
repaired (and re-tested).
Example -- Installation of a 60-mil HPDE geomembrane liner. The 100% Sampling Plan would
be implemented as follows:
3-10
-------
Step 1 Develop a geomembrane panel and seam identification plan similar to that shown
on Figure 3-4. This is commonly based on the panel installation drawing provided
by the liner installer.
Step 2 Test all seams using the vacuum box test for extruded seams or the pressurized air
channel test (GRI-GM6) for double hot wedge seams (see Reference 3-9).
Locations of seam defects are identified by both their seam number and distance
from a given end of the seam, e.g. north or west ends being zero. All test failures
and observed visual defects are entered into a repair log similar to Figure 3-5.
Note that repair logs such as presented in Figure 3-5 may include observations of problems
that may not be considered failure based on vacuum box or pressurized air channel tests. This
includes data related to seam preparation such as the cleanliness of the seam, excessive
grinding (both depth and breadth), and panel preparations. Such observations may be based on
the inspector's judgement, discussed in the next section, and serve as an appropriate
supplement for critical installations.
Judgmental Sampling
Judgmental sampling relies on the experience and judgement of a facility inspector to select
the location and/or number of samples to be tested. The inspector may attempt to
approximate random selection in his location choices or he/she may deliberately select areas
that have been subject to failures in the past i.e., worst case locations. Sometimes a
combination of approaches may be appropriate to establish mean values and outer test value
limits (see below). The results of this subjective sampling approach may be biased. The major
deficiency of this approach is that there is no way to statistically test for bias or to derive
statistical estimates of the properties of the sampled area. Statistical principles are based on
the assumption that potential sample units ("locations" in the context of this discussion) have
a known probability of being included in a sample.
Although judgmental sampling is not suitable for a large sampling program, it may be useful
and even necessary in some cases. For example, when testing a very small area or lot, a
judgmental approach may provide better estimates of area or lot quality than other selection
methods. Additionally, if the testing procedure is very expensive, it may not be feasible to test
enough sample locations to predict with acceptable confidence the quality of an area or lot. A
judgmental sampling plan can select a "worst case" location to provide an estimated best or
worst case limit for the test area. Such worst case sampling applications include looking for
excessively wet soil, excessive sump in grout, and others given in Appendix A.
"3-11
-------
PANEL AND SEAM IDENTIFICATION PLAN
\
\
A
A
4.
TOE OF SLOPE
(T)
I-
-T
f-
\
O - PANEL NUMBER
A - SEAM NUMBER
Figure 3-4 Panel and Seam identification Plan
GEOMEMBRANE REPAIR LOG
Date
Seam
Panels
Location
Material
Type
Description of Damage
Type of
Repair
Repair Test
Type
Tested
By
Figure 3-5 Geomembrane Seam Repair Log
3-12
-------
A Judgmental Sampling Plan:
Step 1 Delineate the sample locations over the entire test area.
Step 2 Determine the number of samples required for the test area. One of the following
methods are usually used:
a. The inspector uses his judgment to select the number of samples.
b. A minimum sample density is typically required in the project specifications.
For example, the project specifications may specify that a field test be made
every 2000 square feet of soil placed in each lift.
StepS Use judgment to select the test locations in each lift.
Step 4 Sample and test the selected locations.
Step 5 Compare the testing results with the project specifications. All areas that do not
meet the project specifications will be rejected and removed or repaired (and re-
tested). .
Fixed Increment Sampling
The fixed increment sampling method uses a randomly selected starting location and a fixed
interval between each consecutive sampling, location. This method is straight forward and
easy to implement in the field. However, the inspector must ensure that the sampling interval
does not skip over critical parts of the installation. For example, in the destructive sampling of
geomembrane seams, the fixed increment should not be so large that all side slopes are
missed. In situations like this it is normally better to use multiple independent sampling
schemes. Areas with less potential problems could be represented by a relatively small number
of sample locations, whereas critical, areas could be represented by a relatively large number of
sample locations. Typically the actual sample size is larger for large areas (non critical areas)
than for small areas (critical areas), but the sampling frequency (proportion of potential
locations that are sampled) for the former will be less than for the latter. The same type of
sampling plan (fixed increment, randomly selected, 100 percent sampling, etc.) or different
plans can be used for the different types (non critical and critical) of areas; For example fixed
increment sampling could be used for the bottom seams and random sampling for the side
slope seams.
To implement a fixed increment sampling plan to represent an area, or material, the area must
be separated into equally sized sampling locations that can be uniquely, identified. One
approach is to overlay the area with a rectangular grid and number the grid sections
sequentially using a serpentine approach. Sample locations are selected from the columns of
3-13
-------
the grid starting at the top of the first column and continuing to the top of each successive
column. The process is similar to reading the columns of a newspaper; an article is read by
starting at the top of the first column and proceeding to the bottom before moving to the top
of the next column. Two dimensional coordinates could be used as an alternative.
If the starting location for the fixed sampling scheme is randomly selected, traditional sample
statistics (means, variances, etc.) are commonly used to estimate the quality of the sampled
area(s). If the starting location is selected by judgement, calculation of sample statistics to
estimate properties of the sampled area is questionable.
A Fixed Increment Sampling Plan:
Step 1
Step 2
Step 3
Step 4
Step 5
Delineate the sample locations over the entire test area.
Determine the number of samples and tests required using either the error of
sampling method or the sample density method.
Select a starting point either by judgment or by a random selection process.
If the sample density method is used, then a test sample must be taken for each
unit of measure that is made from the starting point. For example if 1 sample is to
be selected every 200 feet, then the unit of measure is 200. Hence the first
sample location is selected from the first 200 feet and 1 sample location is
selected from each successive 200 feet of material. If the number of samples is
determined using error of sampling, the interval is determined by dividing the total
size of test area by the number of samples plus one. For example, if a seam in a
geomembrane is 1000 feet long and the number of tests required is calculated as
4, the interval will be 200 feet (1000 * 5). The starting point "n" should be
randomly selected inside the first interval (200 feet) and the remaining samples
selected at 200 feet intervals, ie. "n" + 200, "n"+400, ---.
Compare the test results to the project specifications. All areas that do not meet
the project specifications will be rejected and removed or repaired (and re-tested).
Random Sample Selection
In order to use sample statistics to estimate area characteristics, test locations should be
randomly selected. Random sampling requires that every potential sample location must have
a known probability (typically equal for all locations) of selection. Situations where an
inspector looks over an area and selects test locations can not be accurately described as
3-14
-------
"random" selection. Two typical methods of random sample selection that are applicable to
waste containment system quality control and quality assurance are simple random sampling
and stratified random sampling. The total number of required samples is based on a
consideration of the maximum acceptable error rate and the level of acceptable risks for
rejecting good material and accepting bad material. The procedures for determining sample
size follow those described in sections entitled "error of sampling" and "sample density
method."
Simple Random Sampling -- All potential test locations of the area, or lot, being evaluated have
an known (usually equal) chance of being selected under a simple random sampling plan.
Typically an area is divided into equal sized locations which are assigned unique number
identifiers. Random numbers are used to select identifiers and hence locations for testing. The
source of random numbers is a random number generator, which is available on most
computers, or a random number table. If a random number table such as Table 3-2 is used,
select the first number less than, or equal to, the total number of potential sample locations by
closing your eyes and pointing to any point on the Table. If the number which is pointed to is
larger than the total number of locations take the next number (below, next to, or above) that
is less than or equal to the total number of locations. Record the initially selected number and
the series of numbers less than or equal to the total number of locations directly above or
below this number. Once the bottom of the column is reached, the next number can be
selected at the top of the next column. If numbers are repeated, select additional numbers
from the Table. Continue selection of numbers until the required number of sample locations
are identified. Once the numbers are selected, the last number in the series should be marked
and becomes the starting point for selecting additional samples, if needed.
The Error of Sampling Method is used to determine the appropriate number of test locations to
be included in the simple random sample.
3-15
-------
Table 3-2 Portion of Random Number Table
83
74
12
6
30
25
90
27
12
77
2
83
57
28
32
93
54
42
63
64
71
78
18
54
45
69
67
59
8
16
27
74
47
1
96
71
64
54
72
78
43
19
26
46
94
72
26
36
87
53
16
98
25
69
98
98
74
73
20
46
33
3
52
5
37
98
7
43
30
64
96
41
58
7
90
1
42
60
98
87
35
40
10
17
15
7
1
74
54
89
84
13
64
19
63
83
48
21
79
23
51
42
89
53
31
49
47
89
25
87
96
80
10
10
20
30
2
34
53
73
95
2
96
94
17
93
16
21
14
42
80
74
50
65
2
22
76
64
6
45
84
78
26
42
15
46
18
7
69
24
34
54
70
70
19
75
84
96
9
41
35
51
96
39
56
63
83
42
10
53
22
97
83
27
91
38
85
50
80
14
22
28
34
25
71
52
57
88
2
87
3
52
0
41
87
47
26
22
47
56
83
29
10
29
87
34
15
20
84
42
48
89
32
78
27
76
68
35
81
29
43
72
70
86
61
46
58
19
6
4
75
95
98
50
6
74
84
22
77
43
52
22
42
14
15
39
89
73
92
95
37
26
57
63
46
62
18
69
16
40
34
71
35
65
10
0
26
27
25
57
67
56
87
44
21
34
44
29
47
41
72
31
31
6
7
89
95
91
30
93
61
35
89
74
54
82
16
57
83
47
8
27
73
77
55
46
17
91
17 84
98 76
7 34
85 43
86 81
33 29
62 52
44 55
7 70
60 30
11 36
74 80
34 98
71 38
17 5
68 56
72 13
27 58
77 37
92 91
26 99
86 15
89 28
19 57
77 83
67 66
85 63
87 16
Notes: 1. Range of random numbers is 1 to 100.
2. 00 in table equals 100.
3. The shaded number is starting point in the example.
4. Table of random numbers generated on personal computer.
3-16
-------
Table 3-3 shows a case in which five (5) sample locations are to be selected out of a total of
25 possible locations. Since numbers greater than 25 will not correspond to an existing
location, the random numbers chosen from Table 3-2 that are greater than 25 are discarded.
The sample locations chosen in this example are 25, 10, 20, 2, and 17.
Stratified Random Sampling - Some elements of a waste containment system, such as soil lifts
in a clay liner, have a clear repetitive organization. In these cases, it may be advantageous to
take a random sample of locations from each of the repetitive units - this is known as
stratified random sampling. That is, the lot of items are divided into sublets (or strata) and an
independent random sample of locations are selected from each sublet. In some situations
certain subareas of a larger area may be particularly critical to the overall performance of a site.
For example side seams may be more likely to leak than those in the bottom. In these
situations it is very appropriate to sample a larger proportion of side seam locations than
bottom seam locations. Within each sub area a simple random sample of test locations is
randomly sampled. The other use of stratified sampling is to insure that no subarea of a site is
missed by an evaluation program. While a random sample of a large area may miss some
subarea (stratum), a stratified random sampling plan is guaranteed to test each one.
A Random Sampling Plan:
The procedure below follows a strict random sampling plan. If a stratified random sampling
plan is used, this procedure is applied to each stratum. The number of samples taken from
each stratum is based on the anticipated variability of the test results within each stratum,
desired overall precision of test results, etc. A survey sampling reference or knowledgeable
statistician should be consulted to learn more about the weighing procedures used to calculate
strata sample sizes, computer overall sample statistics, etc.
Step 1 Delineate potential sample locations over the entire test area (See Section 3.1).
Step 2 Determine the number of samples using either the error of sampling method or the
density test method.
Step 3 Select sample locations at random using a random number table or a random
number generator.
Step 4 Collect test material from the randomly selected locations and perform the required
tests.
Step 5 Compare the test results to the project specifications. Any areas that do not meet
the project specifications will be rejected and removed or repaired (and retested).
3-17
-------
TABLE 3-3 EXAMPLE OF RANDOM SAMPLE SELECTION OF 5 LOCATIONS FROM AN AREA
CONSISTING OF 25 LOCATIONS
Item No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Random No.
31
49
47
89
25
87
96
80
10
10
20
30
2
34
53
73
95
2
96
94
17
Disposition
discard! > 25)
discard(>25)
discard(>25)
discard(>25)
select
discard(>25)
discard(>25)
discard(>25)
select
discard(duplicate)
select
discard(>25)
select
delete(>25)
discard(>25)
discard(>25)
discard(>25)
discard(duplicate)
discard(>25)
discard(>25)
select
3-18
-------
3.4 Acceptance/Rejection Criteria
With the exception of the sequential sampling method discussed in Section 3.2, at this point
no criteria for acceptance or rejection of a lot or area has been established. Sampling
frequency, sample locations, and acceptance/rejection for individual tests have been discussed.
This section deals with criteria for accepting or rejecting a lot or area (e.g. a given lift of fill on
the basis of a test series).
No Defects Criteria
The no defects criteria is straightforward. If any test value falls outside the limits in the project
specifications, that area will be rejected and either replaced or repaired and then re-tested.
This criteria is typically applied to the 100% and judgmental sampling methods.
Statistical Value Criteria
Comparison of the sample statistics such as the mean, range, standard deviation, and variance,
to those specified in the project specifications can be used to accept or reject the area being
tested. Statistical value criteria assumes that sample test statistics will follow a known
probability distribution; most people are familiar with the normal distribution curve as shown in
Figure 3-6. This assumed distribution of sample statistics is used to establish an upper limit on
the number or proportion of defective tests that can be accepted in a sample of location test
results. It has been shown that the means of samples containing at least 30 items (locations
in the context of this presentation) are usually normally distributed. As shown on the above
figure of the normal distribution, if the acceptance range is defined as the mean ฑ one
standard deviation, then 15.9% of the sample test results will be below and 15.9% above the
criteria (total defective samples are 31.8%). Expanding the acceptance criteria to mean ฑ two
standard deviations reduces the proportion of sample locations that fall outside the acceptable
range to 4.6% (2.3% above and 2.3% below criteria). Acceptance criteria can be selected to
reflect the critical nature of the element being tested. While not as easily applied as the no
defect method, the statistical criteria method recognizes that the quality of some installations
and materials is not impacted significantly when individual test samples fall outside specified
limits. An example of this can be seen in the concrete industry in the acceptance of concrete
at construction sites (5). Here the average compressive strength of the concrete tests must be
greater than a minimum code value that is a function of the design strength and the standard
deviation of the field tests.
In some cases project specifications provide statistical limits. For example they might specify
that the mean permeability of ten soil samples shall not be less than 10.5E-7. Typically,
project specifications only provide acceptance limits. For example the soil permeability shall
not exceed 10E-7. Many times these acceptance limits can be used to estimate upper or lower
cut-off values for the sample statistic of concern (mean, variance, etc.); if the sample statistic
(mean, variance, etc.) is above or below the estimated cut-off values, the test area is rejected.
The following illustrates an approach for estimating the lower cut-off value for the sample
mean of a particular test measurement based on lower acceptance limits:
Step 1 Determine from (project specifications) the minimum and/or maximum value of the
test results considered acceptable.
3-19
-------
UJ
ACCEPTABLE NUMBER OF
LOW TESTS OR DEFECTS
2.3%
0.1%
V)
a
5
UJ
a
a
eg
<
a
I
to
99.74% ALL RESULTS FALL WITHIN
2.2%
01
z
o
UJ
a
a
a:
<
a
CM
3 S.D.'S OF THE MEAN
95.44% WITHIN 2 S.D.'S
13.6%
68.27% WITHIN
NORMAL CURVE
UNACCEPTABLE IF
THE NUMBER OF
DEFECTS FALLS
ABOVE 1 S.D.
FROM THE MEAN,
15.9%
TEST VALUES
NOTE: ACCEPTABLE AND UNACCEPTABLE VALUES ARE ILLUSTRATIVE OF THE
EXAMPLE IN THE TEXT. DIFFERENT VALUES MAY REQUIRE FOR
DIFFERENT APPLICATIONS.
Figure 3-6 Normal Distribution of Data
3-20
-------
Step 2
Step 3
Step 4
Determine the importance of the characteristic being tested to the function of the
whole system (liner or other component). Table 3-5 can be used to relate relative
importance to the acceptable percentage of test results that are below or above
the acceptable levels.. An element is considered very critical to the function of the
whole system if its failure creates a failure of the whole system. For example,
failure in the seams of a geomembrane liner in a waste containment system can
not be tolerated. Conversely, a soil liner that is constructed in several individual
lifts can tolerate some below specification test values because multiple layers are
applied.
Calculate sample statistics.
the following formulae:
The mean and standard deviation are calculated using
Mean:
x = (1/n)*I x.
Standard Deviation:
(3-2)
s = sqrt[(1/(n-1)*I
(3-3)
where x = the sample mean,
n = the number of sample locations
x, = the individual sample test result
i = the number of the sample
s = sample standard deviation
Compute statistical cut-off values. Assuming the test statistic of concern (mean)
is normally distributed (distribution of means follows a bell shaped curve) use Table
3-5 to select the maximum percentage of locations that can be tolerated with test
results that are less than the acceptance limits. This percentage should then be
used in Table 3-6 to select the lower statistical cut-off value for the sample mean;
this value is the minimum acceptable sample mean that will ensure that the
percentage of locations with measurements less than the lower acceptable limit (as
required in the project specifications) is not greater than desired.
If the sample mean of the test data falls below the calculated lower statistical cut-off value,
the area being tested is rejected. It must be replaced or repaired and then re-tested.
3-21
-------
TABLE 3-5 RECOMMENDED PERCENTAGE OF LOW TEST RESULTS
Importance of the Element to the
Function of the Whole System
Recommended Percentage of
Low Test Results (Probability)
Values below the lower limit
can not be tolerated
0.13 (1.3 in 1000)
Element is critical to the
function of the system
1.1 (11 in 1000)
Element is not critical to
the function of the system
10.1 (1 in 10)
3-22
-------
TABLE 3-6 LOWER STATISTICAL CUT-OFF VALUE FOR THE SAMPLE MEAN
Minimum
Sample Mean
Percentage
of Measurements Less
than the Lower Limit
LL + O.OOs
LL + 0.10s
LL + 0.20s
50.0
46.0
42.1
LL + 0.30s
LL + 0.40s
LL + 0.50s
38.2
34.5
30.9
LL + 0.60s
LL + 0.70s
LL + 0.80s
27.4
24.2
21.2
LL + 0.90s
LL + 1.00s
LL + 1.10s
LL + 1.20s
LL + 1.28s
LL + 1.30s
LL + 1 .40s
LL + 1.50s
LL + 1.60s
LL + 1.70s
LL + 1.80s
LL + 1.90s
18.2
15.9
13.6
11.5
10.0 *
9.7
8.1
6.7
5.5
4.5
3.6
2.9
LL + 2.00s
LL + 2.10s
LL + 2.20s
2.3
1.8
1.4
LL + 2.30s
LL + 2.40s
LL + 2.50s
1.1
0.8
0.6
LL + 2.60s
LL + 2.70s
LL + 2.80s
0.45
0.35
0.25
LL + 2.90s
LL + 3.00s
0.19
0.13 *
LL = lower acceptance limit of the test values as specified in the project
specifications
s = sample standard deviation
3^23
-------
Example - Determine and apply the statistical limit approach to the soil liner data given in
Table 3-7. This data was obtained from a clay liner constructed in five lifts with 20 density
tests performed per lift. Project specifications require a minimum density of 92 PCF (1.47
t/m3).
From Table 3-5, the recommended percentage of low test results is given as 1.1. This leads to
a required mean value (see Table 3-6) of 92 PCF plus 2.3 standard deviations. For the data on
Table 3-7, the mean of the sample soil density measurements must exceed the statistical cut-
off value of 115 PCF (1.84 t/m3). The Sample means for the individual lifts range from 102.1
to 106.6 so that all fail. Likewise since the overall sample mean is 104.1 the liner as a whole
also fails. The installed liner is therefore not acceptable based on this criteria.
Maximum Number of Defects Criteria
Project specifications may set a fixed number of allowable defects. A defect is considered a
test value that falls outside the limits set in the project specifications. The maximum number
of defects criteria is straightforward in its application. No area will be accepted if the number
of the test results that fall outside of the testing limits is larger than the specified number. If
the maximum number is exceeded, the area will be rejected and either replaced or repaired and
re-tested. A common example of this criteria occurs in the destructive testing of
geomembrane seams. At each test location, five peel and shear (see Appendix A) tests will be
performed on coupons obtained from the seam. Typical project specifications will allow for a
maximum of 1 coupon test failure for peel or shear. This method is similar to the statistical
limit criteria insofar as a maximum number of defects are defined. The difference is that this
method simply specifies a fixed number of defects while the statistical limit criteria method
uses a number that is derived from the standard deviation of the data.
Assignable Variable Monitoring (Control Charts)
The above sample acceptance methods are not used to determine the source of test failures.
The failure of a given test may be the result of random or assigned variations. While random
variations cannot be predicted statistically, assignable variations are those that can be
statistically traced to a specific field activity or material. For example, assignable variations
related to the seaming of geomembranes may include different seaming crews, daily
temperature variations, fatigue of seaming crews (related to time of testing or temperature),
specific welding machines, etc. Assignable variable monitoring provides a means of
distinguishing assigned variation in test results from random variations. This allows the relative
quality of the element produced by all field crews, machines, etc. to be compared. This
method is used to monitor data from one of the previously discussed statistically-based
sampling plans. It allows the CQA manager to either increase the frequency of testing during
periods of excessive failures or to identify thos'e variables common to the sample groups
experiencing excessive problems.
A graphical approach to explore the assignable variable monitoring method begins by plotting a
'control chart' for the assigned variables being monitored. The basic tabular procedure for
making a control chart is shown on Table 3-7. Note that control charts can be constructed
after all testing is completed or can be maintained during the actual testing. The latter
provides the greatest opportunity to detect. Fortunately, this process is very easily adapted to
spread sheets commonly available on personal computers. The graphics approach provides
valuable clues about assignable variability. To test whether the observed trends are the result
3-24
-------
TABLE 3-7 STATISTICAL DATA - SOIL LINER DRY DENSITIES
- Soil Liner - 5 Lifts, 20 Tests/Lift (1 per 250 cy)
Clay Liner - Field Dry Densities (pcf)
Sample no.
1
2
3
4
5
6
7.
8
9
10
11
12
13
14
15
16
17
18
19
20
MEAN
STD. DEV.
RANGE
LifM
112
96
93
100
100
103
72
134
112
106
112
112
112
93
87
103
84
109
102
106
102.4
13.1
62
Lift 2
109
96
93
103
106
106
103
103
112
109
118
116
121
109
114
99
87
92
111
98
105
9.2
34
LiftS
106
106
100
103
115
96
112
112
109
112
109
121
103
112
97
97
103
87
89
103
104.6
8.6
34
Lift 4
103
100
93
100
115
103
100
109
75
126
106
118
82
109
106
103
103
92
96
103
102.1
11.4
51
Lift5
100
93
100
109
109
103
96
112
96
121
118
109
109
114
106
109
103
109
114
101
106.6
7.5
28
Total Mean =
Minimum Dry
1 pcf = .0128
104.1 Total
Density (Specs) '=
kg/cubic meter
Std. Dev. 10.0
= 92 pcf
Total Range = 62
= Day Breaks
3-25
-------
of random fluctuations in data or can be attributed to specific causes requires more rigorous
statistical techniques such as analysis of variance. Numerous books are available to aid in
designing studies to test for assignable variability. The other alternative is to consult with a
knowledgeable statistician.
Identification of Outliers - The control chart calculated using Table 3.7 defines all data within
3 standard deviations of the mean. This means that 99.74% of statistically meaningful data
should be within these bounds. Data points that are outside of the control chart bounds are
considered outliers. Such outliers are assumed to be caused by assigned or random variations.
Other more rigorous techniques for outlier detection are described in various several statistical
text books.
A table of daily test pass/fail data is provided on Figure 3-7 to illustrate the use of a control
chart to identify outliers. The tabulated control chart for this data is plotted as shown on
Figure 3-8. This plotted control chart displays the running portion of failed tests along with the
upper control limits (UCL). The plot shown gives the ratio of failed seam tests to total seam
tests and therefore does not use a lower control limit, since no failure is the goal. Both the.
upper control limit and control chart can be calculated for the total sample of locations or as
moving statistics of sub-samples. Statistics can be calculated for each day's measurements
and plotted. Note that the moving test statistics can miss outliers based on the final available
data base.
Obviously the focus in quality assurance is minimizing the cases where the UCL is exceeded.
A detailed evaluation of the assigned variables (e.g. seaming crews, cold vs. hot days) for the
days the UCL is exceeded will provide incite into specific assigned variables which need close
scrutiny and may require additional controls or replacement. This will allow the site manager
to detect and mitigate potential problems before they become significant.
Influence of Subgroup Definition ~ The control chart plotted on Figure 3-8 is based on
subgroups defined by all tests performed on a given day. Alternate subgroups could include all
tests performed on a given compacted soil lifts, seams by crew, etc. Subgroup definition using
assigned variables may aid in the detection of trends hidden by larger subgroups. For example,
control charts for the data presented on Table 3-7 are developed using subgroups defined by
day-of-test and lift number. These control charts are shown on Figure 3-9 and clearly
demonstrate how the selection of the subgroup can be used to highlight defective work. When
testing days defines the subgroups, there are clearly three unacceptable days with several
other days approaching the upper control limit. Conversely, the data appears acceptable when
individual lifts are used to define the subgroups. The subgroups must be defined as small as
practical to determine the influence of assignable variables.
3-26
-------
(1)
Subgroup
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
totals
OK ^
Subgroup
Size
(3)
Subgroup
Defectives
O)
p-(3)+(2)
(5)
sqrtof (2)
(6)
c + (6)
(7)
LCL= Pbar-(6)
(8)
UCL=Pbar+(6)
COLUMN DEFINITIONS
(1) Subgroup Number: Convienent sample grouping, e.g. tests in a given day
(2) Subgroup Size: Number of tests in sample group, e.g. # tests on a given day
(3) Subgroup Failures: Number of tests that fail in subgroup
(4) Ratio of Failures in Subgroup
(5) Square Root of Subgroup Size
(6)C = 3*sqrt(p*(1-p))
(7) Lower Control Limit = Pbar - (6)
(8) Upper Control Limit = Pbar + (6)
* where Pbar = total number fail - total number of tests (26-360=.072)
Figure 3-7 Tabulated Control Chart
3-27
-------
1
UJ
1
2
1
en
i=
g
1
a.
'ABULATED CONTROL CHART FOR DT SEAM TESTS
(D
(2)
(3)
(4)
(5)
BASED ON TOTAL SAMPLE GROUP
SUBGROUP
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3.5 References
3-1 - U.S. EPA. 1984. Permit Applicants'Guidance Manual for Hazardous Waste Land
Treatment, Storage, and Disposal Facilities - Final Draft. EPA 530 SW-84-004,
Office of Solid Waste and Emergency Response, Washington, DC 20460.
3-2 - U.S. EPA. 1984. Quality Assurance Handbook for Air Pollution Measurement
Systems: Volume 1 Principles. EPA-600/9-76-005, Environmental Monitoring
Systems Laboratory, Research Triangle Park, NC 27711.
3-3 - Wahls, H.E., et al. The Compaction of Soil and Rock Materials for Highway
Purposes, Bureau of Public Roads, Washington, DC, August 1966.
3-4 - Annual Book of ASTM Standards, American Society for Testing and Materials,
Philadelphia, PA 19103, 1990.
3-5 - ACI Manual of Concrete Practice, Part 2, Construction Practices and Inspection
Pavements, Detroit, Michigan 48219, 1984.
3-6 - Pyzdek. Thomas. (1989). What Every Engineer Should Know About Quality Control,
ASQC Quality Press, Milwaukee, Wisconsin.
3-7 - Department of Defense (1964), Sampling Procedures and Tables for Inspection By
Attributes, MIL-STD-105, Naual Publications and Forms Center.
3-8 - ASQC (1978), Terms and Symbols for Acceptance Sampling, ANSI/ASQC AZ.
3-9 - U.S EPA 1991. Technical Guidance Document: Inspection Techniques for the
Fabrication of Geomembrane Field Seams. EPA/530/SW-91/051, Office of Solid
Waste and Emergency Response, Washington, D.C. 20460.
3-30
-------
APPENDIX A - WASTE CONTAINMENT ELEMENT FIELD SAMPLE PLANS & TEST METHODS
COMPONENT
Hydraulic
Barriers
ELEMENT
Geomembrane
Geomembrane
nterlocking Panel
Grouts
Soil-Bentonite
Bentonite Board
Sentonite Slurries
Concrete-Bentonlte
KEY PROPERTY
Subgrade
Anchor Trench
Sheet Placement
Overlap of Sheets
Cleanliness of Seam
Extent of Grinding
Surface Defects
Sheet Placement
Interlock Fit
Trench Depth
Viscosity
Unit Weight
Slump
Compressive Strength
Spacing of Pipes
Depth of Pipe
Quantity Injected
Pressure of Injection
proportions of Mix
Uniformity of Mix
Depth of Mixture
Concentration of
Bentonite
Sheet Placement
Overlap of Sheet
Sheet Defects
Weight Bentonite
Viscosity
Unit Weight
Gradation
rench Location
Trench Depth
Time For Hydration
Viscosity
Unit Weight
Gradation
Trench Location
'rench Depth
ime for Hydration
Cement Content
CQA/CQOTEST
Visual
Visual
Visual
Measurement
Visual
Measurement
Visual
Non Destructive Seam Testlna of the
Air Lance
Mechanical Point
Electric Spark
Pressurized Dual Seam
Vacuum Chamber
Ultrasonic Shadow
Ultrasonic Pulse Echo
Destructive Testinq of the Seams
Peel Adhesion
Bond Seam Strength
Scrim Reinforced
Rubber Geomembrane
All Others ;
Visual
Visual
Measurement
Viscosity of Grouts
Density of Slurry
Slump Test
Comp Strength Test
Measure
uleasure
Measure
Measure
Measure/Calculate
he Weights
Visual
Measurement
Methylene Blue Test
Visual
Visual
Visual
Weight
Viscosity of Grouts
Density of Slurry
Sand Content Test
Measurement
Measurement
Measurement
Viscosity of Grouts
tensity of Slurry
Sand Content Test
Measurement
Measurement
Measurement
Cement Content
SAMPLING PLAN
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
>
Fixed Inc./Judgemental
Fixed Inc./Judgemental
=lxed inc./Judgemental
Fixed Inc./Judgemental
rixed inc./Judgementai
100%
100%
rixed Inc./Judgemental
:ixed Inc./Judgementa!
:lxed Inc./Judgemental
:ixed Inc./Judgemental
Stratified Random
100%
100%
100%
100%
tendom
00%
Random
tandom
00%
00%
00%
:ixed Increment
Fixed Increment
:ixed Increment
:ixed Increment
00%
00%
00%
:ixed Increment
ixed Increment
:ixed Increment
00%
00%
00%
Random
SAMPLING FREQUENCY
500ft
500ft
500ft
500 ft
SOOft
1 /Batch
1/Batch
1/Batch
1/Batch
500 cy
/Lot
/Batch
/Batch
/Batch
50 cy
50 cy
50 cy
50 cy
STANDARD TEST METHOD
N/A
N/A
N/A
N/A
N/A
N/A
ASTM D4437
N/A
N/A
N/A
ASTM D4437
GRI GM1-86
ASTM D4437
ASTMD413
ASTM D751
ASTMD816
ASTM D882
ASTM D838
N/A
N/A
N/A
ASTM D4016
ASTM D4380
ASTM C143
ASTM D4832
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
ASTMD4016
ASTM D4380
ASTM D4381
N/A
N/A
N/A
ASTMD4016
STM D 4380
ASTM D4381
N/A
N/A
N/A
STMD2901
A-l
-------
COMPONENT
HydwuKc
Convtyuiea
ELEMENT
ClayUnor
Sand/Gravel
Drain/Collector
Geosyntliotlc
Drain/Collector
Plpo
Sumps
Pumps
KEY PROPERTY
Visual Classification
Clod Size
Water Content
(one only)
Plasticity of Soil
Gradation of Soil
Organic Content
Maximum Density
Hydraulic Conductivity
tn-PIace Density
In-Place Hydraulic
Conductivity
Lift Thickness
Bond Between Lifts
Stripping of Topsoll
From Subgrade
Elevations of Finished
Grade
Water Content
Gradation of Soil
Hydraulic Conductivity
Lilt Thickness
Overlap of Panels
Folds or Wrinkles
Temporary Anchorage
Placement
Location
Grade
Continuity of Joints
Subgrade
Anchor Trench
Sheet Placement
Overlap of Sheets
Cleanllnes of Seam
Extent of Grinding
Mounting &
Electrical Connection
CQA/CQCTEST
Visual Identification
of soils
Measurement
Water Content-Oven
Water Content-Micro
Plasticity Index Test
Gradation Test
Organic Content Test
Proctor Test
Lab HydrCond Test
Density Test
Nuclear
Sleeve
Balloon
Drive-Cylinder '
Infiltrometer
Measurement
Visual
Visual
Surveying
Water Content-Oven
Water Content-Micro
Gradation Test
Lab Hydr Cond Test
Measurement
Measurement
Visual Observation
Visual Observation
Visual Observation
Surveying
Surveying
Pressure Test
Visual Observation
Visual Observation
Visual Observation
Measurement
Visual Observation
Measurement
Non Destructive Testing of the Seams
Air Lance
Mechanical Point
Electric Spark
Preslzed Dual Seam
Vacuum Chamber
Ultrasonic Shadow
Ultrasonic Pulse Echo
Destructive Testlnq of the Seams
Peel Adhesion
Bond Seam Strength
Scrim Reinforced
Rubber Geomembrane
All Others
Visual Observation
SAMPLING PLAN
Fixed Increment
Random
Random
Random
Random
Random
Judgemental
Judgemental
Random
(Select One)
Stratified Random
Stratified Random
Stratified Random
Stratified Random
Judgemental
Random
100%
100%
N/A
Random
Random
Random
Random
Random
Random
100%
100%'
100%
N/A
N/A
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
Judgemental
Judgemental
Judgemental
Judgemental
Judgemental
100% .
SAMPLING FREQUENCY
1500cy
500 cy
1500cy
1500 cy
5000 cy
1 0,000 cy
500 cy
500cy .
500 cy
500 cy
10000 cy
1500 cy
5000 cy
3000 cy
1/Seam ' .
1/Seam
1/Seam
1/Seam
1/Seam
STANDARD TEST METHOD
' ' ,'
ASTM D4083
N/A
ASTMD2216
ASTM D4643
ASTM D4318
ASTM D422
ASTM D2974
ASTMD698orD1557
ASTM D2922
ASTM D4564
ASTM D2167
ASTM D2837
N/A
N/A '
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
ASTM D4437
N/A
N/A
N/A
ASTM D4437
GRI GM1-86
ASTM D4437
ASTM D413
ASTM D816B
ASTM D882(mod)
ASTM D638
N/A
A-2
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COMPONENT
Filters
Erosion Control
Protective Layer
ELEMENT
Sand/Gravel
Filter
Geotextile
Stone & Rip-rap
Vegetation &
Topsoil
Hardened Layer
Asphalt Layer
Concrete
Biotic Layer
Geotextile
Soil Layer
1 - - .
f:. ' -
KEY PROPERTY
Water Content
Gradation of Soil ,
Hydraulic Conductivity
Lift Thickness
Overlap of Panels
Folds or Wrinkles
Temporary Anchorage
Size of Stone
Lift Thickness
Presence of Geotextile
Application Rate
Watering Schedule
Water Content
Gradation of Soil
Soil pH
Lift Thickness
Grade
Organic Content
Thickness of Asphalt
Continuity of Joints
Temperature of Cone.
Slump
Entrained Air
Test Cylinders
Compressive Strength
Subgrade
:ormwork ,
Size of Stone
Lift Thickness
Presence of Geotextile ,
Overlap of Panels
Folds or Wrinkles
Temporary Anchorage
Visual Classification
Water Content '
one only)
elasticity of Soil
Gradation of Soil
Maximum Density
lydraullc Conductivity
n-Place Density
.ift Thickness
Elevations of Finished
Grade
CQQA/CQCTEST
Water Content-Oven
Water Content-Micro
Gradation Test
Lab Hydr Cond Test
Measurement
Measurement
Visual Observation
Visual Observation
Measurement
Gradation
Measurement
Visual Observation
Measurement
Measurement
Water Content-Oven
Water Content-Micro
Gradation Test
Soil pH Test
Measurement
Surveying
Measurement
Measurement
Visual Observation
Measurement
Slump Test
Air Content
Making Cylinders
Corap Strength Test
Visual Observation
Visual Observation
Measurement
Gradation
i/leasurement
Visual Observation
Measurement
Visual Observation
Visual Observation
Visual Identification
of Soils
Water Content-Oven
Water Content-Micro
Plasticity Index Test
Gradation Test
Proctor Test
Lab Hydr Cond Testfif req'd)
Density Test
Juclear
Sleeve
3alloon
Drive-Cylinder
Measurement
Surveying
SAMPLING PLAN
Random
Random '
Random
Random
Random
100%
100%
400%
Random
Random
Random
100%
Fixed Increment
N/A
Random
Random
Random
Random
Random
N/A
Random
Random
Random
Fixed Increment
Fixed Increment
Fixed Increment
:ixed Increment
Random
100%
100%
Random
Random
landom '
10Q% '
100%
100%
100%
Fixed Increment
Random
Random
Random , ,
Random
udgemental
tendom
select one)
Stratified Random
Stratified Random
Stratified Random
Stratified Random
Random
N/A
SAMPLING FREQUENCY
1500cy
1500 cy
1500 cy.
3000 cy
10000 oy
3000 cy
3000 cy
2 per acre
1 per acre
3000 cy
3000 cy
5000 cy
5000 oy
5000 cy
000 cy
5000 cy
0,000 cy
500 cy
500 cy
500 cy
500 cy
STADARD TEST METHOD
ASTMD2216
ASTM D4643
ASTM D422
N/A
N/A
N/A
N/A
N/A
ASTM D422
N/A
N/A
N/A
N/A
ASTMD2216
ASTM D46.43
ASTM D422
N/A .
N/A
ASTM C3 11
N/A
N/A
ASTM C143
ASTM C231
ASTM C31
ASTM C39
N/A
N/A
N/A
N/A
ASTM D422
N/A
N/A
N/A
N/A
N/A
ASTM D4083
ASTM D2216
ASTM D4643
ASTM D4318
ASTM D422
ASTM D698
std/D1S57/mod)
ASTMD2922
ASTM D4564
ASTM 021 67
ASTMD2937
N/A
N/A
A-3
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COMPONENT
iMthwwk
ELEMENT
Foundation
Soil Embankment
Sol Bedding
Geotextile
Separator
KEY PROPERTY
'roof-Rolling
Visual Classification
Water Content
Plasticity of Soil
Gradation of Soli
Maximum Density
Hydraulic Conductivity
n-Place Density
Uft Thickness
Elevations of Finished
Grade
Visual Classification
Water Content
Plasticity of Soil
Gradation of Soil
Maximum Density
In-Place Density
Uft Thickness
Elevations of Finished
Grade
Visual Classification
Water Content
Plasticity of Soil
Gradation of Soil
Maximum Density
Hydraulic Conductivity
livPlace Density
Lift Thickness
Elevations of Rnished
Grade
Overlap of Panels
Folds or Wrinkles
Temporary Anchorage
CQA/CQC TEST
Visual Observation
Visual Identification
of Soils
Water Content-Oven
Water Content-Micro
Plasticity Index Test
Gradation of Soli
Proctor Test
Lab Hydr Cond Test
Density Test
Nuclear
Sand Cone
Sleeve
Balloon
Drive-Cylinder
Measurement
Surveying
Visual Identification
of Soils
Water Content-Oven
Water Content-Micro
Plasticity Index Test
Gradation of Soil
Proctor Test
Density Test
Nuclear
Sand Cone
Sleeve
Balloon
Drive-Cylinder
Measurement
Surveying
Visual Identification
of Soils
Water Content-Oven
Water Content-Micro
Plasticity Index Test
Gradation of Soil
Proctor Test
Lab Hydr Cond Test
Density Test
Nuclear
Sand Cone
Sleeve
Balloon
Drive-Cylinder
Measurement
Surveying
Measurement
visual Observation
Visual Observation
SAMPLING PLAN
100%
Fixed Increment
Random
Random
Random
Random
Judgemental
Random
(select one)
Stratified Random
Stratified Random
Stratified Random
Stratified Random
Stratified Random
Random
N/A
Fixed Increment
Random
Random
Random
Random
Judgemental
(select one)
Stratified Random
Stratified Random
Stratified Random
Stratified Random
Stratified Random
Random
N/A
Fixed Increment
Random
Random
Random
Random
Judgemental
Random
(select one)
Stratified Random
Stratified Random
Stratified Random
Stratified Random
Stratified Random
Random
N/A
100%
100%
100%
SAMPLING FREQUENCY
'
3000 cy
1500 cy
1000 cy
3000 cy
3000 cy
10,000 cy
1SOO cy
1500cy
1500 cy i
1500cy
1500 cy
3000 cy
1500 cy
1000cy
3000 cy
3000 cy
1 0,000 cy
1500 cy
1500cy
1500 cy
1500 cy '
1500cy
3000 cy
1500cy
1000cy
3000 cy
3000 cy
10,000 cy
1500 cy
1500 cy
1500cy
1500 cy
1500 cy
'
STANDARD TEST METHOD
N/A
ASTM D4083
ASTM D2216
ASTM D4643
ASTM D4318
ASTM D422
ASTM D698(std)
ASTMD1557(mod)
ASTM D2922
ASTM D1556
ASTM P45B4
ASTM D2167
ASTM D2937
N/A
N/A
ASTM D4083
ASTMD2216
ASTM D4643
ASTM D4318
ASTM D422
ASTM D69S(std)
ASTM D1557(mod)
ASTM D2922
ASTM D1558
ASTM D4564
ASTM ,02167
ASTM D2937
N/A
N/A
ASTM D4083
ASTM D2216
ASTM D4843
ASTM D4318
ASTM D422
ASTM D698(std)
ASTM D1557(mod)
ASTM D2922
ASTM D1556
ASTM D4564
ASTM D2167
ASTM D2937
N/A
N/A
N/A
N/A
N/A
A-4
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APPENDIX B STANDARDIZED TEST METHODS
ORGANIZATION ADDRESS
American Society for Testing of Materials (ASTM)
1916 Race Street
Philadelphia, PA 19103
(215) 299-5400
Geosynthetic Research Institute (GRI)
Drexel University
West Wing - Rush Building #10
Philadelphia, PA 19104
(215) 895-2343
Plastics Pipe Institute
355 Lexington Avenue
New York, NY 10017
(212) 351-5420
Asphalt Institute
Asphalt Institute Building
College Park, MD 20740
(301) 656-5824
American Concrete Institute
Box 19150
Detroit, Ml 48219
(313) 532-2600
Portland Cement Association
5420 Old Orchard Road
Skokie, IL 60077
(708) 966-6200
National Sanitation Foundation
3475 Plymouth Road
Ann Arbor, Ml 48106
(313) 769-8010
B-l
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APPENDIX C
SAMPLE SPECIFICATIONS FOR A 60 MIL GEOMEMBRANE LINER
WITH SAMPLING, TESTING AND ACCEPTANCE CRITERIA
Scope of Work
The General Contractor shall furnish all labor, material and equipment to install
geomembrane including all necessary and incidental items as detailed or required
to complete the installation in accordance with the Contract Drawings and these
Contract Specifications. The General Contractor shall be responsible for timely
submittals to the Engineer as required in this Contract Specifications.
The anchor trench shall be excavated, maintained and backfilled by the General
Contractor.
B.
Material
The material for the Geomembrane shall be an approved High Density
Polyethylene (HOPE) geomembrane in strict accordance with the Contract
Drawings and these Contract Specifications. The geomembrane shall be
approved by the Engineer and the County prior to Contract award.
The Manufacturer of the geomembrane described herein shall have previously
demonstrated his ability to produce the required geomembrane by having
successfully manufactured a minimum of ten million square feet of High Density
Polyethylene geomembrane for hydraulic containment purposes. The General
Contractor shall provide a certification to the above requirements.
Material for the geomembrane shall include pure High Density Polyethylene and
carbon black, added for ultraviolet radiation resistance, and a maximum of 1
percent of other additives by weight. The geomembrane shall be manufactured
of new, first quality products designed, manufactured and furnished by means
consistent with National Sanitation Foundation (NSF) Standards. The
geomembrane manufacturer shall have demonstrated, by successful prior use,
that said material is suitable and dependable for such purposes.
The High Density Polyethylene used in the manufacture of the geomembrane
shall be of high molecular weight and in accordance with the physical property
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5.
requirements of the Contract Specifications. The geomembrane shall be
produced so as to be free of holes, blisters, undispersed raw materials or any
sign of contamination by foreign matter. Any such defect shall be repaired as
approved by the Engineer. The Engineer may reject all or portions of units (or
rolls) of geomembrane if significant quantities of production flaws are observed.
The physical properties of the geomembrane shall be as described on Table 1 at
the end of this Contract Specifications.
The geomembrane producer shall submit a certification and supporting test data
stating that each resin used for geomembrane production meets or exceeds the
environmental stress cracking criteria outlined below.
5.1 The resin shall exhibit a ductile/brittle transition time of greater than 100
hours using the Notched Constant Load Test (GRI - GM5 Condition A).
The transition shall occur at a stress less than 35% of the geomembrane
yield stress as determined using ASTM D638.
6. A written certification shall be provided by the geomembrane manufacturer
stating the producer, product designation, lot or batch number, and production
date of all resin used in manufacture of all HOPE materials shipped to the site.
6.1 This certification shall be submitted to the Engineer by the Geomembrane
Contractor prior to or coincident with shipment of the geomembrane.
Geomembrane shall not be accepted or approved unless all required
certifications have been received by the Engineer.
7. Thickness of the finished Geomembrane shall be -4% to +10% of the nominal
thickness value specified.
8. The outside of each roll shall identify product designation, the thickness of the
sheet, panel number, if applicable, the length and width of each roll and
manufacturer's batch or lot number.
8.1 Labels or marking shall be located so that each roll of geomembrane can
be identified by examining the roll or core edges. Markings or labels shall
be weather proof.
9. No factory seaming of HOPE Geomembrane panels shall be accepted.
10. All compound ingredients (raw material) for HOPE geomembrane shall be
randomly sampled and tested by the Geomembrane Manufacturer. A test result
summary shall be furnished to the Engineer to assure compliance with the
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material requirements of this specification item. The sampling frequency and
testing procedures shall comply with the requirements as outlined in Table 1 of
these Contract Specifications. A copy of the testing program, including
frequency of tests per quantity of raw material and test method procedures,
shall be submitted to the Engineer with the General Contractor bid. The
summary of test results reflecting actual test frequency shall be furnished to the
Engineer prior to or coincident with shipment of the geomembrane to the project
site.
11. During production, the HOPE geomembrane manufacturer shall sample and test
the manufactured sheet in accordance with applicable ASTM Standards. The
minimum sampling frequency, testing procedures, and sheet physical properties,
shall comply with the requirements as outlined in Table 1 of these Contract
Specifications.
12. The General Contractor shall submit a certification stating the percent of
reclaimed polymer, by weight, that was incorporated into production of the lots
or batches of geomembrane delivered to the project site. Reclaimed polymer
shall not exceed 2% by weight for geomembrane or extrudate.
12.1 At the option of the County, the Engineer may inspect the geomembrane
manufacturing process on a full-time basis. The inspection program
includes conformance sampling as required. The geomembrane
manufacturer shall submit a production schedule to the County if
requested and cooperate with the County during plant inspection.
13. The General Contractor shall submit a certification to the Engineer, prior to
installation, that all HOPE geomembrane manufactured for the project has been
produced in accordance with these specifications, and that a Quality Control
' testing program, in accordance with the Contract Specifications and approved
by the Engineer, has been in effect, and that all required tests have been
performed.
14. The certified summary of all raw material and sheet material tests including
testing frequency and test methods used shall be issued to the Engineer prior to
geomembrane delivery. No HOPE geomembrane shall be installed until the
Engineer has reviewed the certified test summary and determined the
geomembrane delivered is acceptable for use. Records, including test data, shall
be maintained by the geomembrane manufacturer for one year and shall be
made available upon request.
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15. The General Contractor shall submit Quality Control Certificates reviewed and
signed by the responsible representative of the geomembrane manufacturer. A
Quality Control Certificate shall be submitted to the Engineer for each roll of
geomembrane delivered to the project site prior to installation. Any roll not
represented by a completed Quality Control Certificate shall not be approved for
installation by the Engineer.
16. Quality assurance conformance testing of the geomembrane shall be performed
by the Engineer and paid for by the County. Conformance sampling shall be
completed at a minimum frequency of one sample every 100,000 square feet of
geomembrane delivered and at least one sample per lot or batch as directed by
the Engineer.
16.1 Conformance testing of the geomembrane shall include but not be limited
to the following properties:
16.1.1 Density, ASTM D792
16.1.2 Melt Flow Index,' ASTM D1238
16.1.3 Thickness, ASTM D1593
16.1.4 Tensile Properties, ASTM D638
16.1.5 Tear Resistance, ASTM D1004
16.1.6 Carbon Black Content, ASTM D1603
16.1.7 Carbon Black Dispersion, ASTM D3015
16.2 The Engineer may revise the test methods used for determination of
conformance properties to allow for use of improved methods.
17. All geomembrane conformance test data as well as geomembrane manufacturer
Quality Control testing shall meet or exceed requirements outlined in Table 1 of
these Contract Specifications prior to installation. Any materials that do not
conform to these requirements shall be retested or rejected at the direction of
the Engineer.
17.1 Geomembrane that is rejected shall be removed from the project site and
replaced at General Contractor's cost. Sampling and conformance
testing of geomembrane supplied as replacement for rejected material
shall be performed by the Engineer at the General Contractor's cost.
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C. Installation - Geomembrane Preparation arid Placement
1. The Geomembrane Contractor must be approved by the Engineer and the
County prior to Contract award. General Contractor qualifications shall be
submitted for approval with the Geomembrane Contractor's bid, certifying he
has installed a minimum of five million square feet of HOPE geomembrane for
hydraulic containment purposes.
1.1 The General Contractor shall be responsible for timely submittals to the
Engineer and the County.
2. Approximately two weeks prior to arrival at the job site, the Geomembrane
Contractor shall provide personnel resumes demonstrating compliance with the
following requirements:
2.1 A minimum of one field superintendent per shift shall be designated by
the Geomembrane Contractor and approved by the Engineer and the
County. Each field superintendent shall have a minimum of one year of
field experience in installing HOPE geomembranes. Any change or
replacement of superintendents during the project must be approved in
advance by the Engineer and the County.
2.2 Each seaming crew shall have a designated foreman. Said foreman must
have a minimum one year HOPE geomembrane installation experience
and must work continuously with the seaming crew.
3. The Geomembrane Contractor shall submit for the Engineer's approval,
approximately two weeks prior to geomembrane shipment, six full sets of field
erection drawings showing geomembrane panel layout with proposed length and
, width, number and position of all geomembrane panels and indicating the
location of all field welds. Field welds shall have a distinct identification system.
Erection drawings shall also show complete details for field seaming and repairs,
anchoring the geomembrane at the perimeter of the installation area, joining to
structures, and attachments to other penetrations as required.
4. Prior to scheduled geomembrane installation, the General Contractor, Engineer
and General Contractor shall be required to attend a pre-construction meeting at
the project site. This meeting shall be scheduled by the County after receipt of
field erection drawings.
4.1 The General Contractor shall be represented by both the project field
superintendent and the project manager.
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8.
4.2 At the pre-construction meeting, site safety and rules of operation,
quality assurance, scheduling and methods of installation shall be
discussed. The General Contractor and Engineer shall at this time agree
to the required welding, testing and repair procedures.
A daily field record shall be maintained by the General Contractor of actual
placement of each panel, noting the condition of subgrade, weather, seaming
parameters, panel numbers placed, seams welded, samples taken and tests run.
A copy of each day's field record shall be submitted to the Engineer or his
representative no later than the following work day.
The surfaces that are to receive the geomembrane shall be prepared in
accordance with the Contract Drawings and Contract Specifications. Once the
subgrade has been approved by the Engineer, any additional surface preparation
that the General Contractor feels necessary to meet the requirements of the
Contract Specifications, shall be the responsibility of the General Contractor.
The General Contractor shall install geomembrane only on approved subgrade
that has been approved in writing by the General Contractor and the Engineer.
6.1
6.2
The geomembrane shall be placed only on subgrade that is free from
rutting or other evidence of damage caused by vehicle traffic, erosion or
other causes. Subgrade surface requirements, including allowances for
desiccation cracking shall be as outlined in other applicable section of
these Contract Specifications.
Areas exhibiting deficient subgrade surface shall be reported to the
Engineer and the County for repair.
It is imperative to keep surface water runoff from beneath the geomembrane at
all tim es during installation. The General Contractor's panel placement, seam
welding technique, placement and welding schedule shall minimize or eliminate
the potential for accumulation of water beneath the geomembrane. Any water
found ponded beneath the geomembrane after the geomembrane has been
installed shall be removed by the General Contractor at no cost to the County as
directed by the Engineer. Any soil subgrade beneath installed geomembrane
that has become excessively moist, soft, or unsuitable to perform its intended
function shall be removed and replaced by the General Contractor, as directed
by the Engineer, at the General Contractor's expense.
Under no circumstances shall any construction or vehicular traffic be allowed to
drive over the exposed geomembrane. Geomembrane showing evidence of
traffic shall be inspected by the General Contractor and Engineer to determine
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damage, if any. At the direction of the Engineer, any such material shall be
tested, rejected or repaired at no cost to the County.
9. Extreme care shall be taken by personnel while handling unwrapping,
transporting, positioning, and seaming the geomembrane. The Engineer shall
have the option of inspecting all geomembrane panels, prior to final placement,
to assure that all defects or damages are identified for repair. This shall not
replace final inspection by the General Contractor after installation is complete.
Damage to geomembrane incurred during delivery, storage, or installation shall
be repaired or replaced at General Contractor expense.
9.1 Geomembrane shall be stored in a suitable area designated by the
County. Geomembrane delivered on pallets or with folds or creases of
any kind shall be rejected and removed from the site.
9.2 Geomembrane shall be protected during storage so that roll labels remain
in-tact and readable. Any roll of geomembrane that has no label or
where the label is damaged or otherwise illegible may be rejected by the
Engineer.
10. The General Contractor shall provide temporary anchorage of the geomembrane
during installation in a manner approved by the Engineer. Any geomembrane
exhibiting damage from wind or other causes shall be removed by the General
Contractor at no cost to the County.
11. The General Contractor shall be responsible for excavation and maintenance of
the geomembrane anchor trench as well as backfilling of the anchor trench.
11.1 The anchor trench shall be "daylighted" to allow drainage while the
trench is open. The General Contractor shall be responsible for
preventing surface water runoff from accumulating beneath or over top
of geomembrane while the anchor trench is open.
12. The geomembrane shall be installed so as to eliminate "trampolining" of the
geomembrane at the toe of slopes at temperatures as low as 0ฐF. If
trampolining is observed, the Engineer shall direct required repair in affected
areas to be performed by the General Contractor at General Contractor's
expense.
13. Extrusion or fusion welds of adjacent panels shall extend continuously along the
full length of panels and into the geomembrane anchor trench.
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14. The General Contractor shall place the geomembrane in such a manner that no
seams exist in any sump bottom, or, as applicable, within 5 ft. laterally of
sidewall riser pipe locations.
15. The General Contractor shall place and seam geomembrane panels in order to
assure adequate, well distributed slack exists to account for expansion or
contraction of the geomembrane. For this purpose, the General Contractor may
use a working range of liner temperatures from 0 to 150ฐF to determine the
required techniques.
15.1 In critical areas such as sidewalls, sumps, and corners, the General
Contractor may propose slack control techniques for approval by the
Engineer.
16. Seams shall be oriented in a direction parallel to the line of maximum subgrade
slope and shall be placed in a manner that minimizes the number and length of
field seams.
17. For geomembranes placed on slopes, the panels shall be placed such that the
"upstream" panel forms the upper panel and overlaps the "downstream" panel in
order to minimize infiltration potential.
18. All longitudinal seams shall be at least 10 ft. from the toe of the sideslope,
except in the sump area as directed by the Engineer.
D.
Installation - Production Seaming of Geomembrane
All seaming, sealing and welding material shall be of a type or types
recommended by the Geomembrane Manufacturer and shall be delivered in the
original sealed containers, each with an indelible label bearing the brand name,
manufacturer's batch or lot number, and complete directions as to proper
storage.
No production seaming shall commence until trial seaming, as outlined in section
of these Contract Specifications, is successfully completed and approved by the
Engineer.
The Engineer and the County, in conjunction with the General Contractor, shall
establish site-specific limits of weather conditions -including, but not limited to,
temperature, humidity, precipitation and wind speed and direction - within
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which geomembrane panel placement and seaming can be conducted. In the
absence of site-specific criteria, the following limitations shall apply:
3.1 No seaming shall be conducted in the presence of precipitation, such as
rain, snow, sleet, dew or fog, in or below the seam area.
3.2 No seaming shall be conducted in the presence of high winds, when dirt
or debris is blown into seam areas, or when seam temperatures cannot
be adequately monitored and controlled.
3.3 Seaming shall not be conducted when ambient temperature falls below
35 ฐF unless approved by the Engineer. In order for seaming to be
approved, the General Contractor shall be required, at a minimum, to
perform an additional trial seam to demonstrate conformance with these
Contract Specifications. The Engineer reserves the right to require
additional destructive searn testing when seaming is conducted at
ambient temperatures below 35ฐF.
3.3.1 The General Contractor shall be prepared to pre-heat the seam
area prior to production seaming in accordance with the
Geomembrane Manufacturer recommendations.
3.4 Seaming shall not be conducted when ambient temperature exceeds
104ฐF unless approved by the Engineer. Criteria for demonstration of
conformance shall be outlined by the Engineer.
For purposes of monitoring production geomembrane seaming, ambient
temperature shall be monitored by the Engineer. Ambient temperature shall be
recorded at multiple locations along the seam at a distance of 6-inches above
the geomembrane surface.
Lap joints shall be used to weld panels of HOPE geomembrane together in the
field. A minimum overlap of 3-inches shall be used. Seams shall be fusion or
extrusion-welded and as prescribed by the Geomembrane Manufacturer and
approved by the Engineer. For production seaming of geomembrane panels,
fusion seaming is the preferred method. Panels shall be held in position in a
manner approved by the Engineer, to prevent movement during welding, and to
maintain a "flat" lap of panels. The weld area shall be prepared to provide a
suitable surface for adherence to panels to be welded. The weld area shall be
free of dirt, dust, moisture, or other foreign material, and the cleaning process
shall be approved by the Engineer. The weld shall be applied as soon as is
practical after preparation and cleaning is completed. No glue or tape shall be
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used to temporarily hold panels together before welding. No solvents shall be
used to clean panels prior to welding.
6. Temporary bonding of geomembrane panels or patches to be extrusion welded
may be completed using hot air equipment, such as a "Leister". Overheating of
the geomembrane during temporary bonding shall result in rejection of the seam
or patch in question and repair as directed by the Engineer.
7. All Geomembrane panels placed shall be seamed on the same day that they are
placed except where explicitly approved by the Engineer.
8. No folds, wrinkles, or "fish-mouths" shall be allowed within the seam area.
Where wrinkles or folds occur, the material shall be cut, overlapped, and a patch
shall be applied. During wrinkle or fold repairs, adjacent geomembrane may not
necessarily be required to meet the 3-inch minimum overlap, if approved by the
Engineer.
9. Engineer shall observe areas to be prepared by grinding, where applicable, to
assure that excessive grinding does not occur and that the upper sheet is
properly beveled, where applicable.
9.1 Grinding shall be considered to be excessive when the sheet is deeply
scored or when abrasion is evident more than 1 /4-inch outside the
completed extrusion weld area. The Engineer may require repair of such
areas, which may include removal and replacement of the affected
geomembrane.
10. The General Contractor shall not cause excessive overheating of the
geomembrane. Excessive overheating shall be defined as any of the following:
10.1 Application of seaming temperatures or seaming rates that result in
visible warping or deformation of the bottom surface of the lower
geomembrane in the seam area.
10.2 Seaming over an existing weld ("piggybacking"), except for seam cross
tee patches over fusion seams,
10.3 Seaming using temperatures in excess of the manufacturer's
recommended seaming temperature as defined at the pre-construction
meeting.
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11. Application of a bead of extrudate over damaged geomembrane (bead repairs)
shall be prohibited, except where explicitly approved by the Engineer in advance.
11.1 Surface defects, small tears, punctures, etc. shall be repaired using a
patch with a minimum size of 12 inches by 12 inches and having
rounded edges.
12. Fusion seams shall not be repaired by placing extrusion welds directly over
previously seamed areas. Seam end tabs for fusion seams shall not be removed
by cutting or tearing.
12.1 Under no circumstances shall seams be placed over existing seams for
1 repair purposes unless the affected area is less than 5 ft. in length and is
approved by the Engineer in advance.
12.2 Fusion seams shall be repaired by using a patch or cap strip approved by
the Engineer.
13. The Engineer may require repair or replacement of any area where excessive
grinding, overheating, or unacceptable preparation, seaming or testing
techniques are observed. Such repair or replacement may be required even if
samples removed from affected ares pass destructive peel or shear testing.
13.1 All required repairs shall be completed by the General Contractor at no
expense to the County.
14. Any geomembrane area showing damage due to excessive scuffing, puncture or
distress from any cause, shall, as directed by the Engineer, be replaced or
repaired.
15. All patches for repair of the geomembrane shall have rounded corners such that
the repair may be completed with a continuous extrusion weld.
16. Each extrusion welding machine shall be purged of old extrudate prior to the
start of each weld run. The extruders used shall be capable of continuously
monitoring and controlling the temperatures of the extrudate and the zone of
contact (nozzle), to assure compliance with these Contract Specifications and
General Contractor field welding recommendations.
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E.
Geomembrane Seaming - Test Welds and Test Weld Sampling
The General Contractor shall be responsible for performing field testing of all
test welds. The General Contractor shall submit for Engineer's review and
approval at the time of bid submittal, a test weld quality control testing
program. The General Contractor shall modify the quality control testing
program to! comply with the Engineer's requirements for testing, sampling and
resampling of test welds.
Test welds shall be performed for each welder whenever any of the following
conditions occur: (1) shift start-up, (2) "cold" restart of the welder, (3) change
in welding technician, (4) significant change in ambient temperatures, or (5) as
required by the Engineer.
Test welds shall at least 5-ft in length and be conducted using the same
personnel, equipment and seaming parameters as will be used during production
seaming.
Sampling of the test weld shall be conducted from the center two-thirds of the
seam length once an appropriate cooling period has passed.
The General Contractor shall obtain duplicate "preweld" test samples, suitable
for testing. One sample shall be kept by the General Contractor for testing at
the project site in the presence of the Engineer. The duplicate sample shall be
furnished to the Engineer for the project record and/or possible future testing.
The duplicate sample shall be marked with date, time, ambient temperature,
welder, weather conditions, and welding parameters (heat, rate of travel, etc.).
Specimens tested by the General Contractor shall be marked and stored on the
project site for inspection by the County or the Engineer.
Test results acceptable to the Engineer shall be obtained prior to performing any
installation production welding. This may require resampling completed test
seams or repeating the trial seam process. The results of tests shall be noted in
the General Contractor's "preweld" test summary log or daily diary and a copy
furnished to the Engineer not later than the next work day.
The trial seam test specimens shall be tested in peel in accordance with the
approved quality control testing program. A minimum of three specimens shall
be tested for each trial seam. Qualification criteria for all destructive prewelding
testing shall be the Film Tear Bond (FTB) criteria. The failure of the seam
specimen shall be in the parent sheet, not the weld. Under certain conditions, a
partial disbond observed during peel testing of 20% of the weld width or less,
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may be accepted by the Engineer. Testing of additional specimens shall be
performed as required by the Engineer. A failure within the weld area as
designated by the Engineer shall constitute disqualification and require a new
trial seam test of the welding equipment, as directed'by the Engineer.
7.1 For double hot wedge type seams, both seams shall be tested for all field
and laboratory destructive testing.
F.
Geomembrane Seaming - Production Seam Testing
The General Contractor shall be responsible for completing nondestructive
testing of the entire length (100%) of all field seams, including cap strips, and
verifying that all seams are watertight. The testing method shall be a vacuum
test, air-pressure test, or approved equal. The test procedure shall be described
in writing by the General Contractor and submitted with the bid and approved by
the Engineer prior to installation. Upon completion of the vacuum testing, air-
pressure test, or approved equal, a written report shall be submitted to the
Engineer by the General Contractor certifying that all seams were tested.
1.1 Seams or portions of seams that cannot be nondestructively tested due
to access constraints or other reasons may be required to be covered
with a cap-strip as required by the Engineer.
The Engineer shall approve procedures proposed by the General Contractor for
nondestructive testing of geomembrane seams including, but not limited to, the
following items:
2.1 Vacuum Test (as required) ;
2.1.1 Test device
2.1.2 Vacuum pressure .
2.1.3 Vacuum duration at each location
2.2 Air Pressure Testing (as required)
2.2.1 Maximum pressure
2.2.2 Test duration
2.2.3 Maximum allowable pressure drop
2.2.4 Allowance for geomembrane expansion or contraction during
pressure testing
2.2.5 Retesting procedures ,; ,: ;:
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3. Where practical, the General Contractor or Engineer shall sample the ends of
production seams at the panel ends. Field destructive testing for these samples
shall be performed on-site by the General Contractor using the test method and
approval criteria outlined in Paragraph E.7 for test weld samples.
3.1 If the end samples do not exhibit acceptable failures, the Engineer may
require that the General Contractor sample additional locations on the
same seam and/or adjacent seams for laboratory destructive testing.
4. The General Contractor shall obtain duplicate samples of production welds
suitable for destructive testing. The samples shall be obtained at a rate of one
pair (sample and duplicate) per 500 linear feet of welded seam. Additional
samples shall be removed by the General Contractor from areas of questionable
integrity, as directed by the Engineer. The Engineer shall be responsible for
destructive testing one of the sample pairs as described in Paragraph F.5. The
duplicate sample shall be furnished to the Engineer for the project record and/or
possible future testing. These samples shall be obtained from locations as
directed by the Enginee'r and shall be repaired by the addition of a patch to the
sampling location. Each sample size shall not be less than 12 inches by 24
inches with the longer dimension measured parallel to the seam. The seam shall
be in the center of the sample parallel to the longer dimension of the sample.
The seam repair at destructive test sample location shall be nondestructively
tested by the General Contractor to verify its integrity.
4.1 An additional duplicate sample may be retained for testing by the General
Contractor. This testing, if performed, shall be completed at no cost to
the County.
5. The weld in the destructive sample shall be laboratory tested in peel (ASTM
D413) and shear (ASTM D3083). Qualification criteria for all destructive seam
testing shall be the Film Tear Bond (FTB) as well as load criteria outlined below.
The failure of the seam specimen shall be in the parent sheet, not the weld.
Under certain conditions, a partial disbond observed during peel testing of 10%
of the weld width or less, may be accepted by the Engineer. A failure within the
weld area as designated by the Engineer shall require resampling and retesting,
as directed by the Engineer.
5.1 Five specimens from each laboratory destructive test sample shall be
tested for Bonded Seam Strength using ASTM D3083 as modified in NSF
Standard Number 54 using 1-inch wide by 6-inch long die cut specimens
and a strain rate of 2-inches per minute. The load at failure shall be at
least 90 percent of the yield strength (in pounds per inch width) of the
C-14
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parent geomembrane. Failures exhibited in areas prepared by grinding
outside of the extruded areas of extrusion seams may require resampling
and retesting.
5.2 At least five specimens from each laboratory destructive test sample
shall be tested for Peel Adhesion using ASTM D413 as modified in NSF
Standard Number 54 using a minimum of 1 -inch wide by 6-inch long die
cut specimens and a strain rate of 2-inches per minute. The load at
failure shall be 60 percent of the yield strength of the parent
geomembrane (in pounds per inch width) or greater. Strain at failure
shall be at least 30 percent.
5.3 In order for the destructive sample to be considered qualified at least
four of the five peel and four of the five shear specimens shall meet all
load, strain and FTB criteria. If any specimens fail, the Engineer may test
additional specimens in order to determine seam conformance. The
Engineer shall determine conformance of each sample in cases of
dispute. ,
6. Destructive laboratory conformance testing shall be the responsibility of the.
Engineer, and associated costs shall be performed at County expense. The
.General Contractor shall be responsible for all sampling and repair of sample
locations for laboratory and field destructive testing.
7. Should the test results of any destructive test samples removed from production
welds not meet the conformance criteria outlined in these Contract
Specifications, the Engineer may require that additional samples be taken from
welds performed during the same work shift as the failing weld sample. If a
destructive sample fails to meet the physical properties required by the Contract
Specifications, the General Contractor shall obtain additional test samples a
distance of approximately 10-feet in both directions from the original sample for
laboratory destructive testing. All resampling, repairing, and retesting shall be
the responsibility of the General Contractor and shall be performed at the
General Contractor's expense. Depending on the results of these retests, the
Engineer shall approve the repair procedure.
7.1 In order to be considered qualified, each failed destructive seam sample
shall be bounded by two passing destructive seam, samples.
Alternatively, the entire length of the seam in question may be repaired
by placement of a cap strip.
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8. The Engineer or the County may require additional random samples be taken for
destructive testing in areas that visually appear defective and/or not in
accordance with these Contract Specifications. Testing of these samples shall
be completed by the Engineer, but obtaining the samples and repairing the
sample areas shall be the responsibility of the General Contractor.
9. A final visual examination of all welds and in-place geomembrane shall be
completed by the Engineer. The General Contractor shall repair,in accordance
with these Contract Specifications, any area designated by the Engineer as not
in accordance with the Contract Specifications. The General Contractor shall be
responsible for cleaning, sweeping, or other measures necessary to provide a
thoroughly visible geomembrane surface for the Engineer's inspection. The
Engineer's inspection shall be performed following a complete inspection and
approval by the General Contractor's foreman or designated quality control
technician.
Warranty
The General Contractor shall guarantee the integrity within the realm of the
limitations of the General Contractor's responsibility of the installed
geomembrane for its intended use, from material or installation defects, for a
period of two years from the date of acceptance.
Such written warranty shall provide for the total and complete repair and/or
replacement of any defect or defective areas of geomembrane upon written
notification and demonstration by the County of the specific nonconformance of
the geomembrane or installation with the Contract Specifications. Such defects
or nonconformance shall be repaired and/or replaced expeditiously, at no cost to
the County.
The General Contractor shall be responsible for obtaining any necessary
guarantees or certifications from the Geomembrane Manufacturer and
submitting them to the Engineer and Company prior to acceptance of the
installed geomembrane.
H.
Measurement and Payment
1. Payment for work covered shall be on the basis of the Unit Price Bid for
Geomembrane, per square foot in-place including material and installation.
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2. Installed quantities shall be determined by the Engineer. Said areas shall be the
actual area of lined surface, including the required rubsheets, cap sheets, and
geomembrane placed in the anchor trench. This quantity shall not include
overlap at seams, cap strip repairs or other repair areas.
3. Payment for geomembrane material shall be made following appropriate storage
on site and following approval of all required certification submittals in
accordance with these Contract Documents.
4. Delivery date of the geomembrane to the jobsite shall be approved by the
County prior to shipment. The General Contractor shall be responsible for
unloading and stockpiling materials at time of delivery and in areas approved by
the Engineer and the County.
5. Payment for geomembrane installation shall be based upon approved installation
quantities through regular progress payments and in accordance with these
Contract Specifications.
6. Final payment for geomembrane material and installation shall be withheld by
the County until all required documents have been submitted to the Engineer by
the General Contractor.
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TABLE 1
REQUIRED PHYSICAL PROPERTIES OF 60 MIL HOPE GEOMEMBRAIME'1'
PROPERTY (UNITS)
Thickness (mils)
Density, (g/cc)
Melt Index (g/10min)
Carbon Black Content (%)
Carbon Black Dispersion (Grade)
Minimum Tensile Properties,
each direction
1 . Tensile Stress @ Yield (Ib/in.)
2. Tensile Stress @ Break (Ib/in.)
3. Elongation @ Yield (%)
4. Elongation @ Break (%)
Tear Resistance (pounds)
Brittleness Temperature (deg F)
Notched Constant Load Test
Environmental Stress Crack
TESTING FREQUENCY
each roll
each roll
one per lot or batch
(railcar)
each roll
each roll
each roll
test in each principal
sheet direction
each roll
one per lot
one per resin
one per lot
TEST METHOD121
ASTM D751
ASTM D792, Method
A-1
ASTM D1238,
condition 190/2.16
ASTM D1603
ASTM D3015
ASTM D638, type IV,
specimen @ 2 ipm
ASTM D1004, die C
ASTM D746,
Procedure B
GRI GM 5
ASTM D1693,
Condition C
MIN/MAX VALUES
57-66
0.935 min
1 .0 max
2.00 - 3.00
A1 (3)
1 20 min
180 min
10 min
600 min
40 min
-40ฐ F no failures
Transition time >100
hours at < 35% of
yield stress
0 failures @ 1000
hours
NOTE (1): The required physical properties specified herein may be revised by the Engineer to reflect new or revised
test methods or to conform with improvements on the current state-of-the practice.
NOTE (2): Number of specimens per test established in applicable test method unless otherwise noted.
NOTE (3): Grading Observation Standard to be agreed upon between manufacturer and Engineer.
U.S.GOVERNMENTPRINTlNGOFnCEsisga -6fe -003*0052
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United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
Ptease make all necessary changes on the below label,
detach or copy, and return to the address in the upper
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If you do not wish to receive these reports CHECK HERE D;
detach, or copy this cover, and return to the address in the
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EPA
PERMIT No. G-35
EPA/540/R-92/073
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