DESIGN REPORT FOR A

REVISED PANEL CLOSURE SYSTEM

AT THE WASTE ISOLATION PILOT PLANT

Revision 1

October 2002

Prepared for:

Westinghouse TRU Solutions, LLC

P.O. Box 2078

Carlsbad, New Mexico 88221

Prepared by:

RockSol Consulting Group, Inc.

848 Yellow Pine Avenue

Boulder, Colorado 80304
DESIGN REPORT FOR A

REVISED PANEL CLOSURE SYSTEM

AT THE WASTE ISOLATION PILOT PLANT

Revision 1

October 2002

Any comments or questions regarding this report should be 

directed to the U.S. Department of Energy

Carlsbad Field Office

P.O. Box 3090

Carlsbad, New Mexico 88221

Or to Westinghouse TRU Solutions, LLC

P.O. Box 2078

Carlsbad, New Mexico 88221

This report was prepared for Westinghouse TRU Solutions, LLC by 

RockSol Consulting Group, Inc., under Purchase Order Number 3164.

ES-1 Rev. 1 10/3/2002

Executive Summary

Scope. RockSol Consulting Group, Inc., under contract to Westinghouse TRU Solutions, 

prepared a detailed design for a panel closure system for the Waste Isolation Pilot Plant (WIPP). 

Preparation of this detailed design of an operational-phase panel closure system is required to 

support the WIPP Hazardous Waste Facility Permit (HWFP). This report describes the detailed 

design for a panel closure system specific to the WIPP site. The recommended WIPP Panel 

Closure system (WPC) will adequately isolate the waste disposal panels from the active workings 

of the repository for the required design life of 35 years.

Purpose. This report provides detailed design and engineering specifications for the construction 

of the WPC. The WPC design will ensure a nominal operational life of 35 years. The design 

provides assurance that the mass release rate limits specified in the WIPP HWFP for the migration 

of volatile organic compounds (VOCs) will be met as specified in the relevant sections of the 

HWFP (e.g. Attachment N), for simplicity the point of compliance is referred to hereafter as E-300 

drift. The WPC will be located in the air-intake and air-exhaust drifts (Figure ES-1-1). The 

system components are designed to maintain their intended functional requirements under loads 

generated from salt creep and a postulated methane explosion. The proposed design complies 

with regulatory requirements promulgated by Mine Safety and Health Administration (MSHA). 

The design uses common construction practices according to existing standards.

Background. The engineering design considered expected subsurface conditions at the location 

of the WPC. The geology is predominantly halite with inter-bedded anhydrite at the repository 

horizon. During the operational period, the WPC will be subject to creep from the surrounding 

host rock. The salt strata at the repository horizon are known to contain only trace amounts of 

brine.

The HWFP provides information in Module IV on Geologic Repository Disposal. The VOCs of 

concern in Table IV.F.2.c of the HWFP include carbon tetrachloride, chlorobenzene, chloroform, 

1,1-dichloroethene, 1,2-dichloroethane, methylene chloride, 1,1,2,2-tetrachloroethane, toluene, 

and 1,1,1-trichloroethane. 

The primary intent of the WPC is to ensure that VOC releases are less than the regulatory limits 

specified in the HWFP. The E-300 drift mass release rate limit equals the E-300 drift 

concentration limit as specified in Table IV.F.2.c of the HWFP times the minimum ventilation rate 

of 260,000 ft3/min (7,362 m3/min) required by the HWFP. This value establishes the current 

design mass release rate limits for flow of VOCs of concern from the waste disposal areas. 
ES-2 Rev. 1 10/3/2002

Room 7

Room 6

Room 5

Room 4

Room 3

Room 2

Room 1

A

A

B B

D D Panel Closure C C

System Reserved

Area

UNDERGROUND WASTE

DISPOSAL PANEL

Air-Exhaust Drift

Section D-D

Air-Intake Drift

Section C-C

Panel-Access Drift

Section B-B

Disposal Room

Section A-A

TYPICAL EXCAVATION SECTIONS DISPOSAL HORIZON STRATIGRAPHY

Clay I

Anhydrite "a"

Clay H

Disposal

Horizon Envelope

Clay F

Orange

Marker Bed

Marker Bed 139

Clay E

Typical

Disposal Room

x x

x x x

x x

x x x x x x x x x x x x x x

x x x x x x x x x x x x x

x x x

x

x x x x x x x x x x x x x x

x x x x x

x x x x x

x

x

x x

x

x

x

x

x

x

x x x x x x x x x x x

x

x x x x x x x x

x x x x

x

x

x x

x

x

x

x

x

x

x

x

x

x

Anhydrite "b"

Clay G

Figure ES-1-1 Typical Panel Layout with Drift Cross Sections
ES-3 Rev. 1 10/3/2002

While no specific requirements exist for closing disposal areas under MSHA regulations, the 

intent of these regulations is to safely isolate abandoned areas from active workings using 

barricades of "substantial construction." A previous analysis (DOE, 1996a) examined the issue of 

methane gas generation from transuranic waste and the potential consequences of a postulated 

methane explosion in closed waste disposal areas.

To demonstrate compliance with the E-300 drift mass release rate limits for the individual VOCs 

of concern, two air-flow models were evaluated: (1) unrestricted flow and (2) restricted flow 

through the panel closure system. The unrestricted air-flow model is defined as a model in which 

the gas pressure that develops is at, or very near, atmospheric pressure such that no back pressure 

exists in the disposal areas. The restricted air-flow model is defined as a model in which a back 

pressure develops in a closed waste disposal panel due to the restriction of flow through the panel 

closure system and the surrounding disturbed rock zone. The analyses were based on an assumed 

approximate gas generation rate of 0.1 moles per drum per year due to microbial degradation, the 

expected volumetric closure rate due to salt creep, the expected headspace concentration for a 

series of nine VOCs of concern, and the expected air ventilation rate at the E-300 drift. The 

analyses showed that in both air-flow models the release rate of each VOC at the E-300 drift is 

significantly below the permit limit. In the restricted case the release is further reduced. 

Alternate Designs. Various concepts were developed for evaluation. These concepts 

intentionally covered a broad range. A design review committee was convened and was requested 

to rank the various alternatives. The design review committee carefully discussed all the 

alternatives, evaluated their potential performance, and recommended several of the concepts for 

further consideration. After further engineering evaluation and assessment, the explosion isolation 

wall with run of mine salt backfill was selected as the preferred alternative for the WPC. This 

alternative satisfies all performance specifications, is simple to construct, has a low impact on 

waste receipt, and is cost effective.

WIPP Panel Closure System. The WPC has two components: a 30-foot (9.1-meter) concrete 

block wall and a run of mine salt backfill. Figure ES-1-2 illustrates these design components. The 

construction methods and materials to be used to implement the design have been proven in 

previous mining and construction projects. No other special requirements for engineered 

components beyond the normal requirements for fire suppression and methane explosion or 

deflagration containment exist for the WPC during the operational period.
ES-4 Rev. 1 10/3/2002

Figure ES-1-2 Explosion Isolation Wall in Combination with the Run of Mine Salt Backfill
ES-5 Rev. 1 10/3/2002

Design Evaluation. The evaluation of this design was performed to investigate several key 

design issues. This design evaluation can be divided into two components: (1) the operational 

requirements of the system, and (2) the structural and material requirements of the system.

The conclusions reached from the evaluation addressing the operational requirements for the WPC 

design are as follows:

• The mass flow rate for different VOCs through the WPC (including flow through the 

disturbed rock zone [DRZ], the explosion isolation wall, and the run of mine salt backfill) 

were demonstrated to be at least two orders of magnitude below the limits specified in 

Table IV.F.2.c of the WIPP HWFP.

• The Monte Carlo Simulation Method was used to assess the uncertainty of VOCs headspace 

concentrations, gas generation rate, and panel volume closure rate on the mass flow rate of 

carbon tetrachloride. The time required to reach the steady-state mass flow rate of VOCs 

depends on the intrinsic permeability of the flow components. In some realizations in 

which the mass flow rate rises rapidly to the steady-state mass flow rate, the flow is 

essentially unrestricted. In most cases, however, the WPC offers some resistance to flow 

and mass flow rates develop more slowly. In all cases, the explosion isolation wall with the 

run of mine salt backfill complies with the mass flow rate limit at the E-300 drift. The 

maximum mass flow rate through WPC calculated by this analysis was more than an order 

of magnitude below the mass flow rate limits specified in Table IV.F.2.c of the WIPP 

HWFP.

• The dimensions selected for the passive design components of the WPC are conservative, 

and thus ensure that these components will not require routine maintenance during the 

operational life of 35 years.

The conclusions reached from the design evaluation addressing the structural and material 

requirements of the WPC are as follows:

• Thermal cracking due to heat of hydration effects does not apply to concrete blocks. 

• The salt strata at the repository horizon are known to contain only trace amounts of brine 

that will not degrade the main concrete block wall over the nominal operational life of 35 

years.

• Detailed axisymmetric FLAC models were developed to assess the state of stress in the 
ES-6 Rev. 1 10/3/2002

concrete block wall and surrounding rock due to creep closure of the salt. The length 

selected for the explosion isolation wall provides for a substantial margin of safety against 

structural failure.

• Stress analysis showed that the wall will withstand the forces of both creep closure and the 

postulated methane explosion. Further, at the likely time of a postulated explosion, the 

development of confining stress on the block wall would prevent fracturing around the 

block wall.

Design Components. Figure ES-1-2 illustrates the design components developed to satisfy the 

requirements for the WPC. The main barrier consists of a 30-foot (9.1-meter) long concrete block 

wall with construction joints. The concrete block wall design complies with MSHA requirements 

as it is made of incombustible materials of substantial construction. Surface treatment around the 

explosion isolation wall includes the removal of loose material to create a clean and regular 

surface for the construction of the block wall. The backfill consists of run of mine salt with a 

minimum length of 100 ft (30.5 m). Run of mine salt is a natural selection for backfill that is 

compatible with the environment. 

The performance of the WPC design was evaluated against the performance specifications 

established for the panel closure system. The WPC design complies with all aspects of the 

performance specifications established for the panel closure system.
i Rev. 1 10/3/2002

Table of Contents_____________________________________________

Executive Summary ....................................................................................... ES-1

List of Tables .................................................................................................. iii

List of Figures .................................................................................................. iv

List of Acronyms................................................................................................ v

1.0 Introduction ......................................................................................................................... 1-1

1.1 Scope......................................................................................................................... 1-1

1.2 Regulatory Requirements.......................................................................................... 1-3

1.2.1 Hazardous Waste Regulations..................................................................... 1-3

1.2.2 Mine Safety and Health Administration...................................................... 1-3

1.3 Report Organization.................................................................................................. 1-3

2.0 Design Descriptions............................................................................................................. 2-1

2.1 WPC Performance Specifications............................................................................. 2-1

2.2 Design Concept ......................................................................................................... 2-2

2.3 Design Components.................................................................................................. 2-2

2.3.1 Explosion Isolation Wall ............................................................................. 2-4

2.3.2 Backfill ........................................................................................................ 2-4

3.0 Design Evaluations.............................................................................................................. 3-1

3.1 Analyses Addressing Operational Requirements...................................................... 3-1

3.1.1 Air-Flow Analyses....................................................................................... 3-1

3.1.1.1 Evaluation Procedure.................................................................... 3-1

3.1.1.2 Modeling Results.......................................................................... 3-6

3.1.1.3 Conclusions .................................................................................. 3-7

3.1.2 Advection Evaluation .................................................................................. 3-7

3.1.2.1 Evaluation Procedure.................................................................... 3-7

3.1.2.2 Modeling Results........................................................................ 3-13

3.1.2.3 Conclusion.................................................................................. 3-15

3.1.3 Monte Carlo Simulation of VOC Release ................................................. 3-15

3.1.3.1 Evaluation Procedure.................................................................. 3-19

3.1.3.2 Modeling Results........................................................................ 3-20

3.2 Analyses Addressing Material and Structural Requirements.................................. 3-20

3.2.1 Material Compatibility Evaluation ............................................................ 3-20

3.2.2 Heat Generation......................................................................................... 3-22

3.2.3 Explosion Evaluations............................................................................... 3-22
ii Rev. 1 10/3/2002

3.2.4 Stress Analysis........................................................................................... 3-24

3.2.4.1 Block Wall Evaluation................................................................ 3-24

3.2.4.2 Run of Mine Salt Backfill Evaluation ........................................ 3-26

3.2.5 Fracture-Propagation Evaluation............................................................... 3-32

4.0 Design Calculations............................................................................................................. 4-1

5.0 Technical Specifications...................................................................................................... 5-1

6.0 Drawings.............................................................................................................................. 6-1

7.0 Conclusions ......................................................................................................................... 7-1

8.0 References ........................................................................................................................... 8-1

Appendix A - Derivation of Relationships for the Air-Flow Models

Appendix B - Calculations of Panel Volume Closure

Appendix C - FLAC Modeling of the WIPP Panel Closure System

Appendix D - Technical Specifications

Appendix E - Design Drawings
iii Rev. 1 10/3/2002

List of Tables_________________________________________________

Table 3-1 Intrinsic Permeability of Flow Components................................................................. 3-5

Table 3-2 Air Conductance Through System Components........................................................ 3-12

Table 3-3 Ranges of Intrinsic Permeabilities in the Monte Carlo Simulation Analysis............. 3-18

Table 5-1 Technical Specifications for the WIPP Panel Closure System..................................... 5-1

Table 6-1 WIPP Panel Closure System Drawings........................................................................ 6-1

Table 7-1 Compliance with Performance Specifications.............................................................. 7-3
iv Rev. 1 10/3/2002

List of Figures________________________________________________

Figure ES-1-1 Typical Panel Layout with Drift Cross Sections......................................ES-2

Figure ES-1-2 Explosion Isolation Wall in Combination with the Run of Mine Salt Backfill ..ES-4

Figure 1-1 Typical Panel Layout with Drift Cross Sections......................................................... 1-2

Figure 2-1 Explosion Isolation Wall in Combination with the Run of Mine Salt Backfill .......... 2-3

Figure 2-2 Explosion Isolation Wall............................................................................................. 2-5

Figure 3-1 Pressure Buildup with Time for a Single Panel .......................................................... 3-8

Figure 3-2 Migration Rates versus E-300 Drift Limit Values for the VOCs of Concern............. 3-9

Figure 3-3 Breakthrough Time for VOCs through Several Media ............................................. 3-14

Figure 3-4 Monte Carlo Simulation of Restricted Air-Flow Analysis........................................ 3-16

Figure 3-5 Mass Flow Rate for Carbon Tetrachloride................................................................ 3-21

Figure 3-6 Creep Plus Explosion Model Geometry and Boundary Conditions.......................... 3-25

Figure 3-7 Vertical (Radial) Stress Profile at Top of Block Wall During an Explosion Occurring 

10 Years after Emplacement..................................................................................... 3-27

Figure 3-8 Horizontal (Axial) Stress Profile at Top of Block Wall During an Explosion Occurring 

10 Years after Emplacement..................................................................................... 3-27

Figure 3-9 Vertical (Radial) Stress Contours in Block Wall During an Explosion Occurring 10 

Years after Emplacement.......................................................................................... 3-28

Figure 3-10 Horizontal (Axial) Stress Contours in Block Wall During an Explosion Occurring 10 

Years after Emplacement.......................................................................................... 3-28

Figure 3-11 Plasticity State in Block Wall at 35 Years .............................................................. 3-29

Figure 3-12 Vertical (Radial) Stress Profile at Top of Block Wall at 35 Years ......................... 3-29

Figure 3-13 Applied Forces on a Longitudinal Element of Backfill .......................................... 3-33

Figure 3-14 Dynamic Displacement versus Distance from Explosion Face............................... 3-33
v Rev. 1 10/3/2002

List of Acronyms_____________________________________________

atm atmosphere

CFR Code of Federal Regulations

cm centimeter(s)

CQC Contractor Quality Control

CQCP Contractor Quality Control Plan

DOE Department of Energy

DRZ Disturbed Rock Zone

ft foot (feet)

FLAC Fast Lagrangian Analysis of Continua

g gram(s)

HASP Health and Safety Plan

HWFP Hazardous Waste Facility Permit

K Kelvin

kg kilogram(s)

m meter(s)

mg milligram(s)

min minute(s)

MPa Mega Pascal(s)

MSHA Mine Safety and Health Administration

PCS Panel Closure System

ppm part(s) per million

psi pound(s) per square inch

QA/QC Quality Assurance/Quality Control

RCRA Resource Conservation and Recovery Act

s second(s)

SNL Sandia National Laboratories

TRU Transuranic

VOC(s) Volatile Organic Compound(s)

WIPP Waste Isolation Pilot Plant

WPC WIPP Panel Closure system

yr year(s)
1-1 Rev. 1 10/3/2002

1.0 Introduction

The Waste Isolation Pilot Plant (WIPP), a U.S. Department of Energy (DOE) facility located near 

Carlsbad, New Mexico, was established for the safe disposal of defense-generated transuranic 

(TRU) waste. The WIPP repository is approximately 2,150 feet (ft) (655 meters [m]) below the 

surface, in the Salado Formation.

One important aspect of repository operations at the WIPP is the activity associated with closure 

of waste disposal panels. Each panel consists of air-intake and air-exhaust drifts, panel-access 

drifts, and seven rooms (Figure 1-1). After completion of waste disposal activities in a panel, it 

will be closed at the same time that waste disposal may be occurring in the other panel(s). The 

closure of individual panels during the operational period will be accomplished in accordance with 

project-specific health, safety, and environmental performance criteria. 

The WIPP Panel Closure system (WPC) design is an explosion isolation wall with run of mine salt 

backfill. The original Panel Closure System (PCS) design was contained in DOE (1996a) and 

Appendix PCS of the WIPP Compliance Certification Application (CCA) (DOE, 1996b). A large 

portion of the design information contained in that appendix is applicable to the WPC design. 

This includes the application of the restricted and unrestricted flow models, heat transfer analyses, 

and analyses associated with the methane gas explosion. Throughout this document, the CCA 

appendix is referred to as Appendix PCS. 

1.1 Scope

This report provides analyses of the WPC design for effectiveness of the explosion isolation wall 

as a gas barrier; the structural adequacy of the explosion isolation wall; and the design description 

of the WPC for a nominal operational period of 35 years. The WPC design provides assurance 

that the limit for the migration of volatile organic compounds (VOCs) will be met as specified in 

the relevant sections of the HWFP (e.g. Attachment N), for simplicity the point of compliance is 

referred to hereafter as the E-300 drift. The WPC will be located in the air-intake and air-exhaust 

drifts to each panel (Figure 1-1). The WPC design maintains its intended functional requirements 

under loads generated from salt creep and a postulated methane explosion. The design complies 

with regulatory requirements promulgated by Mine Safety and Health Administration (MSHA).
1-2 Rev. 1 10/3/2002

Room 7

Room 6

Room 5

Room 4

Room 3

Room 2

Room 1

A

A

B B

D D Panel Closure C C

System Reserved

Area

UNDERGROUND WASTE

DISPOSAL PANEL

Air-Exhaust Drift

Section D-D

Air-Intake Drift

Section C-C

Panel-Access Drift

Section B-B

Disposal Room

Section A-A

TYPICAL EXCAVATION SECTIONS DISPOSAL HORIZON STRATIGRAPHY

Clay I

Anhydrite "a"

Clay H

Disposal

Horizon Envelope

Clay F

Orange

Marker Bed

Marker Bed 139

Clay E

Typical

Disposal Room

x x

x x x

x x

x x x x x x x x x x x x x x

x x x x x x x x x x x x x

x x x

x

x x x x x x x x x x x x x x

x x x x x

x x x x x

x

x

x x

x

x

x

x

x

x

x x x x x x x x x x x

x

x x x x x x x x

x x x x

x

x

x x

x

x

x

x

x

x

x

x

x

x

Anhydrite "b"

Clay G

Figure 1-1 Typical Panel Layout with Drift Cross Sections
1-3 Rev. 1 10/3/2002

1.2 Regulatory Requirements 

1.2.1 Hazardous Waste Regulations

The Closure Plan in the WIPP HWFP was prepared in accordance with the requirements of 

20.4.1.500 New Mexico Administrative Code (incorporating 40 Code of Federal Regulations §264 

Subparts G, I, and X). The WPC complies with the relevant portions of those requirements.

1.2.2 Mine Safety and Health Administration

Under 30 CFR 57 “barriers and stopping” must be constructed of noncombustible materials 

appropriate for the specific mine category and must be of "substantial construction." Substantial 

construction implies construction of such strength, material, and workmanship that the barrier 

could withstand air blasts, methane detonation or deflagration, blasting shock, and ground 

movement expected in the mining environment. The WPC complies with the relevant portions of 

those regulations.

1.3 Report Organization

This report presents evaluations of the WPC. Chapter 2 presents the description of the design. 

Chapter 3 presents the design evaluations addressing the gas barrier effectiveness of the explosion 

isolation wall and the structural adequacy of the explosion isolation wall. Chapter 4 presents the 

design calculations. Chapters 5 and 6 present the technical specifications, and drawings 

respectively. Chapter 7 presents the conclusions to the report.
2-1 Rev. 1 10/3/2002

2.0 Design Descriptions

This chapter describes how the concept for the WPC was developed and describes the explosion 

isolation wall and run of mine salt backfill components of the WPC.

2.1 WPC Performance Specifications

Original design criteria were presented in Table 7-1 of DOE (1996a) and were revised in 

Attachment I of the HWFP as issued. These criteria were reviewed for continued applicability and 

only one of the performance specifications was modified, as italicized in the following list. The 

WPC performance specifications are:

• The panel closure system design shall limit VOC migration from a closed panel consistent 

with the limits found in Table IV.F.2.c of the HWFP.

• The panel closure system shall consider potential flow of VOCs through the disturbed rock 

zone (DRZ) in addition to flow through closure components.

• The panel closure system shall perform its intended functions under loads generated by 

creep closure of the tunnels.

• The panel closure system shall perform its intended function under the conditions of a 

postulated methane explosion.

• The nominal operational life of the closure system is thirty-five (35) years.

• The panel closure system for each individual panel shall not require routine maintenance 

during its operational life.

• The panel closure system shall address the most severe ground conditions expected in the 

waste disposal area.

• The design class of the panel closure system shall be IIIb (which means that it is to be built 

to generally accepted national design and construction standards).

• The design and construction shall follow conventional mining practices.

• Structural analysis shall use data acquired from the WIPP underground.

• Materials shall be compatible with their emplacement environment and function.
2-2 Rev. 1 10/3/2002

• Treatment of surfaces in the closure areas shall be considered in the design.

• Thermal cracking of concrete shall be addressed.

• During construction, a Quality Assurance/Quality Control (QA/QC) program shall be 

established to verify material properties and construction practices.

• Construction of the panel closure system shall consider shaft and underground access and 

services for materials handling.

Various concepts were developed for evaluation. These concepts intentionally covered a broad 

range. For each of these concepts, the estimated conductance was calculated and a preliminary 

construction cost was estimated. These were intended only as aids to facilitate ranking during the 

selection process.

A design review committee was convened and was requested to rank the various alternatives. The 

design review committee carefully discussed all the alternatives, evaluated their potential 

performance, and recommended several of the concepts for further consideration. After further 

engineering evaluation and assessment, the explosion isolation wall with run of mine salt backfill 

was selected as the preferred alternative for the WPC. This alternative satisfies all performance 

specifications, is simple to construct, has a low impact on waste receipt, and is cost effective.

2.2 Design Concept

The selected design for WPC is a combination of a mortared concrete block wall and a run of mine 

salt backfill. Figure 2-1 illustrates these design components. The construction methods and 

materials used to implement the design are well proven in previous mining and construction 

projects. This configuration satisfies the E-300 drift mass flow rate limits for the flow of VOCs of 

concern out of the panel. The selected design will resist the temperature transients and methane 

explosion pressure as discussed in Sections 3.2.2 through 3.2.4. 

2.3 Design Components

The following subsections present system and components design features.
2-3 Rev. 1 10/3/2002

Figure 2-1 Explosion Isolation Wall in Combination with the Run of Mine Salt Backfill
2-4 Rev. 1 10/3/2002

2.3.1 Explosion Isolation Wall

The explosion isolation wall consists of a 30-foot (9.1-meter) long, mortared, solid block wall as 

shown in Figure 2-2. Detailed structural analyses have been performed (Section 3.2.4) to assess 

the development of stresses within the block wall. These analyses showed that a 30-foot 

(9.1-meter) long concrete block wall reduces the relative proportion of the compressive abutment 

zones near the ends of the wall to an acceptable level. Five construction joints were introduced to 

mitigate the axial tensile stresses, which develop in the wall due to salt creep. The construction 

joints also eliminate the effects of potential differential displacements along the axis of the wall. 

Since the construction joints are normal to the direction of VOCs flow out of the closed panel they 

have minimal impact on flow conductance of the wall. 

The blocks of the wall are 8x8x16 inches and have a minimum unconfined compressive strength 

equal to 5000 psi (34.5 MPa). The specifications include materials testing to verify material 

properties and construction practices. 

The concrete block wall design complies with MSHA requirements. It is made of incombustible 

materials and is of substantial construction. The block wall can also resist forces of a postulated 

methane explosion under creep load from the surrounding rocksalt as discussed in Section 3.2.4. 

The surrounding salt surfaces will be prepared to create a smooth, clean surface for the placement 

of bricks and mortar.

The explosion isolation wall with the run of mine salt backfill separates the active ventilated 

underground workings from the closed panels. The restricted flow analysis presented 

subsequently (Section 3.1.1) shows an adequate design margin for meeting VOC release limits. 

2.3.2 Backfill

The backfill consists of run of mine salt with a minimum length of 100 ft (30.5 m). Run of mine 

salt is a natural material for backfill that is completely compatible with the environment. In the 

absence of the block wall, run of mine salt backfill provides protection against a methane 

explosion. An analysis was conducted to assess the effect of methane gas explosion on the 

backfill. In this analysis, the explosion isolation wall was ignored and the run of mine salt backfill 

alone resisted the impact loading from the postulated methane explosion. The analysis showed 

that the backfill will absorb the explosion impact due to deflagration.
2-5 Rev. 1 10/3/2002

Figure 2-2 Explosion Isolation Wall
3-1 Rev. 1 10/3/2002

3.0 Design Evaluations

This chapter presents the evaluations that support the design of the WPC: (1) analyses addressing 

the operational requirements, and (2) analyses addressing the material and structural requirements. 

The first group includes air-flow analyses, an advection analysis, and an uncertainty analysis of 

air-flow. The second group includes material compatibility evaluation, heat generation, explosion 

evaluation, stress analysis and fracture-propagation evaluation.

3.1 Analyses Addressing Operational Requirements

To evaluate the effectiveness of the WPC, air-flow analyses were performed to examine the flow 

of VOCs through the WPC. The following sections address the air-flow analyses, the advection 

analysis, and air-flow uncertainty analysis. These analyses support the WPC design for both the 

overall protection of human health and the environment, and compliance at the E-300 drift as 

required by HWFP.

3.1.1 Air-Flow Analyses

The purpose of the air-flow analyses is to evaluate the flow of VOCs through the WPC. The 

effective intrinsic permeability of the WPC is evaluated and used as input to the air-flow model 

(DOE, 1996a) to assess VOC(s) flow performance.

In this study, two air-flow models are considered: (1) unrestricted flow, and (2) restricted flow 

through the panel closure system. The unrestricted air-flow model is defined as a model in which 

the gas pressure that develops is at, or very near, atmospheric pressure such that no back pressure 

exists in the disposal areas. The restricted air-flow model is defined as a model in which a back 

pressure develops in a closed waste disposal panel due to the restriction of flow through the panel 

closure system and the surrounding disturbed rock zone. The analyses are based on an assumed 

gas generation rate of 8,650 moles per panel per year (0.1 moles per drum per year [DOE, 1996a] 

for 86,500 drums per panel [HWFP]) due to microbial degradation, an average volumetric closure 

rate of 31,430 ft3 (890 m3) per year due to salt creep (Appendix B), the expected headspace 

concentration for nine VOCs (Appendix A), and the minimum mine ventilation rate of 260,000 

ft3/min (7,362 m3/min) required by HWFP at E-300 drift. 

3.1.1.1 Evaluation Procedure

In the restricted flow model, the gases in the waste-emplacement area are in part compressed in 

the void space within a panel and in part flow into the main return air. The restricted flow model 
3-2 Rev. 1 10/3/2002

is based on the following assumptions:

• Gases (including VOCs) within the void space will obey the Ideal Gas Law. The gases will 

be generated at a rate of 0.1 moles per drum per year (DOE, 1996a) and will be stored by an 

increase in gas pressure. The rate of pressure buildup will be so gradual that it occurs at 

constant temperature.

• Volumetric reduction due to creep will reduce the void space at a rate of 31,430 ft3 (890 m3) 

per year (Appendix B) and will result in pressurization.

• Flow of gas out of the panel will obey Darcy's Law under quasi steady-state conditions. 

Under quasi steady-state conditions, the air pressure within the WPC will change so 

gradually that the compressive storage of the air within the void space of the WPC could be 

neglected.

• Rates of gas generation, air outflow, and change in compressive storage will balance.

• Hydrodynamic dispersion through the barrier will be neglected.

• Analysis will consider the superposition of flow rates from individual panels according to 

the operating schedule for a nominal operational life of 35 years.

The air-flow under these assumptions follows a nonlinear system of two first-order ordinary 

differential equations. The model is characterized by molar gas generation and reduction in void 

volume that together result in an increase in air pressure.

The problem can be solved using the system of nonlinear ordinary differential equations as derived 

in Appendix A:

2

( )

V

dt

dV V n

p p

C

RT

p

g

R T

dt

dp

atm

r

⋅ −

−

− ⋅ ⋅

= ⋅ ⋅

g

(Equation 3-1)

g

atm

r

p p

C

R T

p

g

dt

dn −

⋅ ⋅

⋅

= − (Equation 3-2)

where
3-3 Rev. 1 10/3/2002

dt = Change in time (years)

R = Universal gas constant (atm . m3/(mole . K))

T = Absolute temperature (K)

n = Moles of gas in the panel

p = Pressure (atm)

patm = Atmospheric pressure (atm)

C = Conductance (m2/s) of the panel closure system = 

L

A

Ks⋅

Ks = Effective air conductivity of the panel closure system (m/s)

A = Cross sectional area of the panel closure system (m2)

L = Flow path length of the panel closure system (m)

g = Air density (kg/(m2 . s

2

))

gr = Gas generation rate (moles/yr)

V = Volume of the panel void space (m3)

dt

dV

= Panel volumetric closure rate (m3/yr)

dt

dp

= Panel pressure rate (atm/yr)

dt

dn

= Panel molar storage rate (mole/yr).

The above relationships are subject to the following initial conditions: (1) the pressure in the panel 

will be atmospheric; and (2) the moles of gas in the panel equal the moles of gas occupying the 

initial panel void volume at the temperature of the repository at the time of panel closure.
3-4 Rev. 1 10/3/2002

The effective air conductivity of the panel closure system ( Ks) can be expressed in terms of the 

effective intrinsic permeability of the panel closure system ( sk ) and the fluid properties of air as 

(Freeze and Cherry, 1979):

m

k r g

K

s

s

⋅ ⋅

= (Equation 3-3)

where 

r = Air mass density (kg/m3)

g = Acceleration due to gravity (m/s2

)

m = Absolute air viscosity (kg/(m . s))

The effective intrinsic permeability of the WPC ( sk ) can be evaluated by considering the intrinsic 

permeabilities of the various flow components over their respective areas, as presented in 

Table 3-1.

Permeability measurements in salt were summarized in the original design report (DOE, 1996a). 

These data show a zone of increased permeability (10-18 to 10-20 ft2 [10-19 m

2

 to 10-21 m

2

]) 3 to 42 

ft (1 to 14 m) from the excavation surface. Based on these observations, the calculations assumed 

that the cross-sectional area for flow through the DRZ and the WPC will equal nine times the airintake and air-exhaust drift area or that the DRZ extends out three radii from the center 

(DOE, 1996a).

As shown in Table 3-1, a distinction is made between “dilated salt”, and “fractured salt”. Dilated 

salt exhibits a higher permeability than intact salt due to relief of the lithostatic stresses, and this 

corresponds to the increased permeability zone observed by Case and Kelsall (1986). The more 

conservative value of 10-19 m

2

 is used here for the intrinsic permeability of dilated salt. The 

fractured salt refers to the highly fractured zone in the immediate vicinity of the openings.

The intrinsic permeability of the concrete block wall was estimated from the intrinsic 

permeabilities of the concrete blocks and the interface zone between the mortar and concrete 

blocks that is tributary to each block. A parallel system was used to calculate the intrinsic 

permeability of the concrete block wall from the intrinsic permeabilities of its flow components 

(concrete blocks and interface). It is assumed that the intrinsic permeability of mortar is the same 

as that of concrete block. For the concrete blocks an intrinsic permeability of ck = 1.0x10-19 m

2
3-5 Rev. 1 10/3/2002

(PCA, 2002) was used with a flow area of Ac = 8x16 in2 = 128 in2 = 0.083 m2. Further, the 

intrinsic permeability of the interface zone surrounding the concrete blocks was estimated using an 

interface zone aperture of 11 micron (Fernandez et al., 1994). For a smoothwall aperture of b, the 

interface zone intrinsic permeability is equal to b

2

/12 (Fernandez et al., 1994). For an aperture of 

b = 11x10-6 m, the interface zone intrinsic permeability of ik = 1x10-11 m

2

 is obtained. The area 

of the interface zone surrounding each concrete block is Ai = 2(16 in + 8 in) b = 1.34x10-5 m

2

. 

The intrinsic permeability of the concrete block wall can be calculated using Equation A-14 of 

Appendix A as follows: 

c i

c c i i

wall A A

k A k A

k

+

⋅ + ⋅

= (Equation 3-4)

This results in an intrinsic permeability of 1.64x10-15 m

2

 for the concrete block wall which is 

rounded to 2x10-15 m

2

. 

The run of mine salt backfill is placed in a loose state in the air-intake and air-exhaust drifts of 

each panel. Case et al. (1987) reports on an experiment on WIPP crushed salt that measured the 

relationship of hydraulic conductivities to porosity when subjected to confining pressure. The test 

results showed that the intrinsic permeability might equal 0.01 darcy (10-14m

2

) at 15 percent 

porosity. For high porosities from 35 to 40 percent, the test results showed that the intrinsic 

permeability might equal 102 darcy (10-10 m

2

). In the current analysis, an intrinsic permeability of 

10 darcy (10 –11 m

2

) was used. This is a reasonable value for the expected range of porosities. 

Table 3-1 Intrinsic Permeability of Flow Components

Intrinsic Permeability

Component ft2 m

2 References

Dilated salt 1x10-18 1x10-19 DOE, 1996a

Fractured salt 1x10-14 1x10-15 DOE, 1996a

Clay seams 1x10-16 1x10-17 DOE, 1996a

Marker Bed 139 1x10-15 1x10-16 DOE, 1996a

Interface zone 1x10-10 1x10-11 DOE, 1996a

Concrete block wall 2x10-14 2x10-15 Calculated

Run of mine salt 1x10-10 1x10-11 Case et al., 1987
3-6 Rev. 1 10/3/2002

Finally, for the clay seams, Marker Bed 139, and the interface zone between the concrete block 

wall and the surrounding rocksalt, the values from the previous design (DOE, 1996a) were used.

To calculate the void space volume of the panel (V ), the analysis assumed that the volume of the 

waste is equal to the total waste capacity of a panel (600,000 ft3 [16,990 m3]) (DOE, 1994) times 

the assumed average solid volume of the waste drums (23 percent) (IT, 1994). The analysis uses a 

solid waste volume equal to 138,000 ft3 (3,908 m3) for the panel and this volume remains constant 

during the operational life of the panel. 

The waste-emplacement capacity of a panel includes the seven rooms and the panel access drifts 

from Room 1 to Room 7. Field data from geotechnical engineering measurements were used to 

determine creep closure rates for 35 years as presented in Appendix B.

A model for unrestricted flow of VOCs was also developed to predict the mass flow rates of 

VOCs (Appendix A). The results of unrestricted flow analysis are used for comparison with the 

restricted flow case.

3.1.1.2 Modeling Results

The HWFP provides information in Module IV on Geologic Repository Disposal. Table IV.F.2.c 

of this module presents the E-300 drift concentration limits for VOCs of concern. These limits are 

shown on appropriate figures. The VOCs of concern in Table IV.F.2.c of the HWFP include 

carbon tetrachloride, chlorobenzene, chloroform, 1,1-dichloroethene, 1,2-dichloroethane, 

methylene chloride, 1,1,2,2-tetrachloroethane, toluene, and 1,1,1-trichloroethane.

The E-300 drift mass release rate limit equals the E-300 drift concentration limit as specified in 

Table IV.F.2.c of the HWFP times the minimum mine ventilation rate of 260,000 ft3/min (7,362 

m

3

/min) required by HWFP. This value establishes the current design mass release rate limits for 

flow of VOCs of concern from the waste disposal areas.

Comparisons are made of the expected mass release rate of VOCs of concern to the E-300 drift 

mass release rate limits. The calculation of the expected mass flow uses the product of (1) an 

estimate of the actual headspace concentrations for each of the VOCs of concern, and (2) an 

estimate of the actual gas flow rate from the restricted flow model as presented previously. 
3-7 Rev. 1 10/3/2002

The sources of information for the actual VOCs headspace concentrations (Appendix A) include 

Table A-2 of DOE (1996a), and the WIPP Waste Information System Headspace Gas 

Concentration Report (2002). The maximum values for actual mass concentrations from the two 

sources of information are used in the present analysis. 

Figure 3-1 shows the expected pressure buildup in a single panel after closure. The pressure 

within the panel builds up gradually due to the large compressibility of the panel void space 

relative to the air-flow rate out of the panel. The restricted air-flow rate also builds up gradually to 

a steady-state flow rate. 

Figure 3-2 presents the expected mass release rates for the VOCs of concern versus time for 

comparison to the E-300 drift mass release limits for the repository. In these analyses, the current 

panel closure schedule (Westinghouse, 2002) is considered, and the expected mass release rates 

from individual panels as they are closed are superimposed in time. The analyses show that in 

every case, the expected mass release rate from the repository is much lower than E-300 drift mass 

release rate limit for the VOCs of concern.

3.1.1.3 Conclusions

The air-flow model (DOE, 1996a) was used to predict the expected mass flow rate for VOCs of 

concern through a panel closure system consisting of a concrete block wall with run of mine salt 

backfill. The analysis suggests that VOC flow over the operational period will be at least two 

orders of magnitude below the HWFP limits established at the E-300 drift (Figure 3-2).

3.1.2 Advection Evaluation

The purpose of the advection evaluation is to assess contaminant transport time through various 

media. As panel pressure develops with time, gases will travel through the panel closure system. 

The restricted air-flow model considered that the VOC concentration front will instantaneously 

develop in the active underground workings and the gases would then flow by advection. The 

more detailed analysis presented below considers the flow distribution in different components. 

3.1.2.1 Evaluation Procedure

The relative significance of each of the air-flow zones can be evaluated by studying flow 

conductance. The flow conductance through a parallel system is calculated as follows (Freeze and 

Cherry, 1979):
3-8 Rev. 1 10/3/2002

0.0

0.5

1.0

1.5

2.0

5 10 15 20 25 30 35

Time (years)

Pressure (atm)

Figure 3-1 Pressure Buildup with Time for a Single Panel
3-9 Rev. 1 10/3/2002

Carbon Tetrachloride

1.E-05

1.E-03

1.E-01

1.E+01

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

Chlorobenzene

1.E-07

1.E-05

1.E-03

1.E-01

1.E+01

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

Chloroform

1.E-06

1.E-04

1.E-02

1.E+00

1.E+02

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

1,1-Dichloroethene

1.E-07

1.E-05

1.E-03

1.E-01

1.E+01

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

1,2-Dichloroethane

1.E-08

1.E-06

1.E-04

1.E-02

1.E+00

1.E+02

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

Figure 3-2 Migration Rates versus E-300 Drift Limit Values for the VOCs of 

Concern

Restricted Flow Unrestricted Flow Limit at E-300 Drift
3-10 Rev. 1 10/3/2002

Methylene Chloride

1.E-05

1.E-03

1.E-01

1.E+01

1.E+03

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

1,1,2,2-Tetrachloroethane

1.E-07

1.E-05

1.E-03

1.E-01

1.E+01

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

Toluene

1.E-06

1.E-04

1.E-02

1.E+00

1.E+02

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

1,1,1-Trichloroethane

1.E-06

1.E-04

1.E-02

1.E+00

1.E+02

5 10 15 20 25 30 35

Time (years)

Mass Flow Rate (g/min)

Figure 3-2 (continued) Migration Rates versus E-300 Drift Limit Values for the 

VOCs of Concern

Restricted Flow Unrestricted Flow Limit at E-300 Drift
3-11 Rev. 1 10/3/2002

∑

⋅

=

i

i i

L

K A

C (Equation 3-5)

where

C = Flow conductance of the system (m2/s)

Ki = Air conductivity of the th i component (m/s)

Ai = Cross sectional area of the th i component (m2)

Li = Length of the th i component (m)

The conductance through the WPC will depend on the air conductivity and cross-sectional area of 

the flow components. Table 3-2 summarizes these values for each component. Since the 

conductance of run of mine salt is at least four orders of magnitude higher than that of any other 

component, the breakthrough of VOCs through run of mine salt occurs very rapidly. Therefore, in 

the advection analysis the effect of run of mine salt is neglected. The calculations show that flow 

through the block wall and fractured salt will dominate the conductance.

In Table 3-2, the flow area of the interface zone between the 14 ft x 21 ft concrete block wall and 

surrounding rocksalt is based on an interface zone aperture of b = 11x10-6 m (Fernandez et al., 

1994). This results in an interface flow area of Ai = 2(14 ft + 21 ft) b = 2.34x10-4 m

2

. For a 

smoothwall aperture of b, the interface zone intrinsic permeability is equal to b

2

/12 (Fernandez et 

al., 1994). For an aperture of b = 11x10-6 m, the interface zone intrinsic permeability of ik = 

1x10-11 m

2

 is obtained. The interface zone air conductivity can be calculated from Equation 3-3. 

Using the air density of g = r ⋅ g = 0.0735 lbf/ft3

 (11.55 kg /(m2 . s

2

)) and air viscosity of m = 

3.85x10-7 lbf s/ft2 (1.84x10-5 kg/(m . s)) (Lindeburg, 1986), the interface zone air conductivity is 

obtained equal to 6.26x10-6 m/s. 

The breakthrough of VOCs through the WPC under the assumption of advection will occur when 

the VOC front has traversed its length. The average linear velocity equals the Darcy flux divided 

by the effective porosity for the various flow components. The average linear velocity, neglecting 

compressibility effects of the gas, is given by (Freeze and Cherry, 1979):

⋅ ⋅g

⋅

=

n L

K p t p

V p t

e

i atm

i

avg

( ( ) - )

( ( )) (Equation 3-6)
3-12 Rev. 1 10/3/2002

where

i

avg V( p(t)) = Average linear velocity for the th i component (m/s)

Ki = Air conductivity of the th i component (m/s)

p(t) = Panel internal pressure as a function of time (atm)

patm = Atmospheric pressure (atm)

L = Length of the barrier (m)

g = Air density (kg/(m2 . s

2

))

ne = Effective porosity

The following assumptions were made in this advection model:

• The air-flow velocity will be constant along the panel closure system.

• The gases (including VOCs) within the void space will obey the Ideal Gas Law.

Table 3-2 Air Conductance Through System Components

Component Effective 

Porosity

Air Conductivity 

(m/s)

Approximate 

Cross-Sectional 

Area (m2)

Conductance per 

Unit Length

(m3/s)

Dilated salt10.001 6.26x10-14 170 1.0x10-11

Fractured salt10.040 6.26x10-10 16 1.0x10-8

Clay seams10.400 6.26x10-12 0.09 5.6x10-13

Marker Bed 13910.040 6.26x10-11 11 6.9x10-10

Interface21.000 6.26x10-62.34x10-41.5x10-9

Concrete block wall20.200 1.25x10-927 3.4x10-8

Run of mine salt30.440 6.26x10-627 1.7x10-4

1 DOE, 1996a

2 Calculated

3 Case et al., 1987
3-13 Rev. 1 10/3/2002

• The flow of air out of the panel will obey Darcy's law under quasi steady-state conditions. 

Under quasi steady-state conditions, the air pressure within the panel closure system will 

change so gradually that the compressive storage of air within the void space of the panel 

closure system will be neglected.

• The two-phase flow and interactions between air and brine will be neglected, although the 

re-saturation of salt would tend to reduce the flow of VOCs through the panel closure 

system.

The air-flow average linear velocity as a function of time was calculated for each component of 

the WPC using the maximum pressure determined from the air-flow model (DOE, 1996a). The 

breakthrough time for advective transport was then determined for each of the WPC components 

(fractured salt, MB 139, clay seams, and the explosion isolation wall).

3.1.2.2 Modeling Results

In the model presented for air-flow, the pressure varies as a function of time for flow through the 

WPC. This will result in a change in the average linear velocity as a function of time that was 

calculated for each of the various components (fractured salt, MB 139, clay seams, and the 

explosion isolation wall). 

Breakthrough times for a WPC due to advection were computed and are shown in Figure 3-3. The 

advection analysis suggests that for fractured salt and the mortared block wall, average linear 

velocities will be high due to high permeability, and low porosity, and that VOC breakthrough 

may occur within one to several years.

Previous analysis (DOE, 1996a) evaluated the effects of hydrodynamic dispersion on VOC 

transport through the WPC, using a one-dimensional dispersion model (Freeze and Cherry, 1979). 

This analysis showed that since breakthrough due to advection occurs rapidly through the 

dominant flow paths within several years, the effects of hydrodynamic dispersion are negligible. 

The analysis presented in this report also shows a similar rapid breakthrough through fractured salt 

in one to several years, as was the case in the previous analysis. 
3-14 Rev. 1 10/3/2002

1.E-03

1.E-01

1.E+01

1.E+03

1.E+05

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

Time (years)

Distance Traveled (m)

Fractured Salt

MB 139

Path Length

1.E-05

1.E-03

1.E-01

1.E+01

1.E+03

1.E+05

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

Time (years)

Distance Traveled (m)

Dilated Salt

Clay Seams

Block Wall

Path Length

Figure 3-3 Breakthrough Time for VOCs through Several Media
3-15 Rev. 1 10/3/2002

3.1.2.3 Conclusion

The restricted air-flow analysis of Section 3.1.1 showed that the mass flow rates of VOCs of 

concern will remain well below the HWFP required E-300 drift limit. The results of advection 

analysis suggest the appropriateness of the restricted flow model (DOE, 1996a) for the 

instantaneous breakthrough of VOCs. The advection analysis showed that for fractured salt and 

the mortared block wall, average linear velocities will be high due to high permeability, and low 

porosity, and that VOC breakthrough may occur within one to several years. While it may appear 

that this breakthrough time is short, the quantities involved are so small that, as was concluded in 

Section 3.1.1.3, VOC flow over the operational period will be at least two orders of magnitude 

below the HWFP required limit in the E-300 drift.

3.1.3 Monte Carlo Simulation of VOC Release

This section presents a Monte Carlo Simulation Analysis (Hahn and Shapiro 1967) for mass flow 

rate of carbon tetrachloride over 35 years of operation. Carbon tetrachloride is used as a surrogate 

for all VOCs of concern since it is likely to be present in the greatest concentration in a closed 

panel. In the Monte Carlo Simulation Method, uncertain input parameters are represented by 

separate probability distribution functions. Each of the uncertain input parameters is sampled to 

develop multiple realizations. It is assumed that the uncertain input parameters are independent of 

each other and that the covariance between the input parameters can be neglected. A deterministic 

function or model is then used to evaluate the output parameter (in this case, the mass flow rate of 

carbon tetrachloride) for each set of realization of input parameters. 

In an analysis of the flow of VOCs from a panel, a number of uncertain input parameters can be 

identified. For example, the concentration of VOCs can vary within and between panels, so the 

actual headspace concentration can be considered as uncertain input for calculation purposes. The 

migration of VOCs depends on the panel volumetric closure rate and the molar gas generation 

rate, both of which are uncertain parameters. Finally, in the case of restricted flow, the intrinsic 

permeabilities of the WPC (for both closure components and the surrounding disturbed rock zone) 

also are a source of uncertainty. 

In the current Monte Carlo Simulation, only the restricted flow of VOCs is considered. A 

schematic representation of the Monte Carlo Simulation for restricted flow analysis is shown in 

Figure 3-4. Each of the uncertain inputs is discussed in the following sections:

Headspace concentration: The VOC inventory perhaps represents the most significant source of 

uncertainty. WIPP receives waste from multiple facilities with multiple waste streams. Both the
3-16 Rev. 1 10/3/2002

Figure 3-4 Monte Carlo Simulation of Restricted Air-Flow Analysis

Intrinsic Permeability

Gas Generation Rate

Volume Closure Rate

Restricted 

Air Flow 

Analysis

Headspace Concentration

Output

Input

 VOCs Mass Flow Rate
3-17 Rev. 1 10/3/2002

unrestricted and restricted flow models assume that the headspace concentrations serve as a 

constant source of VOCs. This assumption is conservative because most containers only have 

trace quantities of VOCs, either trapped in the headspace or on the surfaces of the various waste 

components. It is likely that only a small number of waste containers have a significantly greater 

source of VOCs such as a solvent-soaked rag. Only this small number of waste containers have a 

realistic likelihood of maintaining a constant headspace VOC concentration as gas generation 

proceeds.

The current project baseline uses a headspace concentration of 3625.77 mg/m3 for carbon 

tetrachloride (DOE, 1996a). To account for the uncertainty, it is assumed that the headspace 

concentration for carbon tetrachloride ranges from 0 to 7250 mg/m3 with a uniform distribution.

Gas generation rate: The next uncertain parameter is the gas generation rate. The current project 

baseline uses a gas generation rate of 0.1 moles per drum per year. In the current uncertainty 

analysis it is assumed that the gas generation rate ranges from 0 to 0.2 moles per drum per year 

with a uniform distribution. The uniform distribution provides an estimate of variance that is 

higher than that for a normal distribution. It is therefore conservative to assume that the molar gas 

generation rate is uniformly distributed. 

Volumetric closure rate: Another uncertain parameter is the volumetric closure rate. In the 

original design the panel closure rate was based upon data from Panel 1. Since that time, Panel 2 

has been excavated, and data are available for assigning the uncertainty. The air-flow analysis 

presented in Section 3.1.1 used an average volumetric closure rate of 890 m3 (31,430 ft3) per year 

(Appendix B). For the purpose of uncertainty analysis, it is assumed that the volumetric closure 

rate is uniformly distributed between 600 (21,200) to 1200 m3 (42,400 ft3) per year. 

Intrinsic permeabilities: The remaining uncertain parameters are the intrinsic permeabilities of 

the various flow components. Log uniform distributions are used in this analysis for intrinsic 

permeabilities of various flow components. The ranges of intrinsic permeabilities selected for the 

Monte Carlo Simulation Analysis are presented in Table 3-3.

The intrinsic permeability of salt in the disturbed rock zone includes the intrinsic permeability of 

dilated salt and fractured salt. Within the first meter of most excavations, some fractures parallel 

to the drift are observed from boreholes at the midheight of the rib (DOE, 1995). In this region, 

the permeabilities are generally greater than at any other location in the salt. Between 3 and 6 ft 

(1 and 2 m) into the rib, permeabilities decrease to about 10-19 m

2

 and below; beyond 6 ft (2 m), 

the permeabilities rapidly decrease to the value associated with intact salt (10-22 m

2

). Based on 
3-18 Rev. 1 10/3/2002

these observations, the analysis assumes that the dilated salt has a range of intrinsic permeabilities 

from 10-20 to 10-17 m

2

. Also, the analysis assumes the fractured salt intrinsic permeability ranges 

from 10-17 to 10 -12 m

2

. Thus the combined range of the dilated salt and fractured salt values is 

exceptionally broad and covers the extreme range of values commonly used in various other 

WIPP-related assessments. 

Freeze and Cherry (1979, p. 29) present a range of intrinsic permeabilities for clay, which can be 

used to estimate values for the clay seams. The range selected here is from 10-19 to 10-16 m

2

. 

Single-phase brine and nitrogen permeabilities were measured in the laboratory for specimens of 

MB 139 taken from the underground workings at the WIPP (DOE, 1995). Permeabilities to gas 

ranged from approximately 1.8x10-19 to 2.5x10-17 m

2

, and the Klinkenberg-corrected equivalent 

liquid permeabilities ranged from 1.4x10-18 to 1.6x10-17 m

2

. Measured permeabilities to brine 

ranged from 4.4x10-20 to 9.7x10-17 m

2

. Based upon these values, the range of intrinsic 

permeability for the MB 139 is selected as from 1x10-20 to 1x10-16m

2

.

The intrinsic permeability for the interface zone between the concrete block wall and the 

surrounding rocksalt is estimated based on a smoothwall aperture range from b = 2 to b = 16 

microns (Fernandez et al., 1994). For a smoothwall aperture of b, the interface zone intrinsic 

permeability is equal to b

2

/12 (Fernandez et al., 1994). The results range from 3.33x10-13 to 

2.13x10-11m

2

 for the interface zone intrinsic permeability. 

Table 3-3 Ranges of Intrinsic Permeabilities in the Monte 

Carlo Simulation Analysis

Median Lower Value (m2) Upper Value (m2)

Dilated Salt 1.00x10-20 1.00x10-17

Fracture Salt 1.00x10-17 1.00x10-12

Clay Seams 1.00x10-19 1.00x10-16

Marker Bed 139 1.00x10-20 1.00x10-16

Interface Zone 3.33x10-13 2.13x10-11

Explosion Isolation Wall 1.00x10-171.00x10-13

Run of Mine Salt Backfill 1.00x10-14 1.00x10-10
3-19 Rev. 1 10/3/2002

The intrinsic permeability of the concrete block wall was estimated in Section 3.1.1.1 as 

2x10-15 m

2

. To account for uncertainty, a range of permeability of four orders of magnitude for 

the explosion isolation wall was selected from 10-17 m

2

 to 10-13 m

2

.

The run of mine salt backfill is placed in a loose state in the air-intake and air-exhaust drifts of 

each panel. Case et al. (1987) reports on an experiment on WIPP crushed salt that measured the 

relationship of hydraulic conductivities to porosity when subjected to confining pressure. The test 

results showed that the intrinsic permeability might equal 0.01 darcy (10-14m

2

) at 15 percent 

porosity. For high porosities from 35 to 40 percent, the test results showed that the intrinsic 

permeability might equal 102 darcy (10-10 m

2

). Therefore, the range of intrinsic permeability is 

selected from 10-14 m

2

 to 10 –10 m

2

. 

3.1.3.1 Evaluation Procedure

In order to combine information on assessing the mass flow rate of carbon tetrachloride from a 

single panel, MathConnex (MathSoft, Inc., 1999) was used. MathConnextm is an environment for 

visually integrating and linking applications and data sources to create heterogeneous 

computational systems. MathConnex provides a means of connecting MathCad and EXCEL files 

together in a network. In the MathConnex file entitled Monte Carlo Simulation for Restricted 

Flow, the uncertain parameters are implemented in four MathConnex components:

• Headspace Concentration of CCl4 is an EXCEL file that generates a random sample for the 

headspace concentration of carbon tetrachloride as discussed above. 

• Volumetric Closure Rate is an EXCEL file that generates a random sample of the panel 

volumetric closure rate as discussed above.

• Gas Generation Rate is an EXCEL file that generates a random sample of the gas generation 

rate as discussed above.

• Intrinsic Permeabilities is an EXCEL file that generates a random sample of the intrinsic 

permeabilities for each of the flow components as discussed above. 

For a single realization of the randomly sampled parameters, the outputs from each of these 

components is input to the MathCad file entitled Restricted Flow Model. The restricted flow 

model is used to develop a time history for the mass flow rate of CCl4 out of the panel. The output 

from the Restricted Flow Model is then input to an EXCEL file Monte Carlo Simulation. This file 

develops the time histories for multiple realizations of the input parameters. 
3-20 Rev. 1 10/3/2002

3.1.3.2 Modeling Results

A Monte Carlo Simulation was performed for the restricted flow analysis of VOCs. The results of 

this simulation for 40 different realizations are presented in Figure 3-5. The figure shows the 

variation of mass flow rate for carbon tetrachloride during the operational life of the WPC. The 

mass flow rate limit for CCl4 is calculated as the mass concentration limit at E-300 drift times the 

minimum underground ventilation flow rate of 260,000 ft3/min (7,362 m

3

/min) required by 

HWFP. 

In general, the magnitude of the unrestricted steady-state mass flow rate of CCl4 reflects the 

uncertainty in VOCs concentration rates, panel gas generation rate, and panel volumetric closure 

rate. The time required to reach the restricted steady-state VOC mass flow rate depends on the 

intrinsic permeability of the flow components. In some restricted realizations, the mass flow rate 

rises rapidly to the unrestricted steady-state mass flow rate, so the flow is essentially unrestricted. 

In the large majority of cases, however, the WPC offers some resistance to flow and the mass flow 

rates develop much more slowly. In all cases the WPC complies with the mass flow rate limit at 

the E-300 drift as required by HWFP.

3.2 Analyses Addressing Material and Structural Requirements

This section presents evaluations relating to the material and structural requirements for the WPC.

3.2.1 Material Compatibility Evaluation

The purpose of the material compatibility evaluations is to select suitable materials for the WPC. 

The materials must be chemically compatible with the host rock and brine without chemical 

degradation. This section presents information on brine-cement interactions at the locations of the 

WPC.

WIPP brines were initially studied when evidence of some minor concrete deterioration in the 

Waste Shaft key was noted (DOE, 1996a). The cause was geochemical alteration of the concrete 

shaft liner and shaft grout by the brine present at the Rustler-Salado contact. Chemical 

constituents detected in brine samples included both organic and inorganic compounds that 

probably originated from dissolution of the concrete liner and grout materials used in the shaft 

construction. The presence of large amounts of organics that likely originated from the chemical 

grout appeared to have complexed the calcium present in the brine, interfering with the inorganic 

chemistry of the naturally occurring brine. The brines in contact with the Waste Shaft key were
3-21 Rev. 1 10/3/2002

1.E-07

1.E-05

1.E-03

1.E-01

1.E+01

1.E+03

5 10 15 20 25 30 35

Time (Years)

CCl4 Mass Flow Rate (g/min)

Figure 3-5 Mass Flow Rate for Carbon Tetrachloride

E-300 Drift Mass Flow Rate Limit
3-22 Rev. 1 10/3/2002

also found to be significantly higher in both chlorides and magnesium than the Salado Formation 

brine. 

Several other studies investigated the effect of the high-magnesium brine interactions on various 

candidate barrier materials (DOE, 1996a). However, the original PCS design concluded that two 

extremely different service environments can be inferred between the Waste Shaft key and the 

underground repository horizon. 

The WPC consists of concrete block wall and run of mine salt backfill. Blocks will be pre-cast in 

a factory setting and no organic grout compounds are used in the design. The magnesium level in 

the brines is much lower at the repository horizon. Further, only trace amounts of brine would 

contact the explosion isolation wall over the operational period due to the relative impermeability 

of the surrounding halite. For these reasons, significant brine-cement interactions are not 

anticipated and the block walls will perform their function within this time period. Run of mine 

salt backfill is entirely compatible with the underground environment. 

3.2.2 Heat Generation

The WPC uses concrete blocks for explosion isolation wall. The concrete blocks will be pre-cast 

and cured in a factory setting. They will then be transported to the site and taken underground as 

convenient. Note that for these small blocks (8x8x16 inches), the volume to surface ratio is 

smaller than for large monolithic emplacements of concrete. Thus the temperature rise due to the 

heat of hydration can be dissipated without the development of tensile strains within the blocks 

before emplacement. Quality control testing of the blocks will assure strength and serviceability. 

Therefore cement heat generation is not an issue for the WPC.

3.2.3 Explosion Evaluations

The evaluation of the postulated methane explosion consists of evaluating the pressure and 

thermal effects of such an explosion on the explosion isolation wall. A methane explosion would 

generate an initial pressure transient that would impinge on the explosion isolation wall. 

Subsequently, temperature would rise in the panel as well as in the explosion isolation wall.

Two analyses are necessary to evaluate methane-explosion effects: (1) effect of explosion 

pressure, and (2) effect of explosion heat. After an explosion, the explosion isolation wall would 

be subjected to short-term dynamic loading. The design pressure can be calculated as the 

maximum pressure times the dynamic load factor (Biggs, 1964). The dynamic load factor will 
3-23 Rev. 1 10/3/2002

depend on the shape of the pressure-time transient. An explosion will result in a transient pressure 

pulse that will rise instantaneously and then drop gradually. 

The second effect requires a thermal analysis with a heat-transfer model. The results of the heat 

transfer model calculations (DOE, 1996a) are valid under the postulated explosion. The heat 

transfer model under the postulated explosion within the panel considered the heat balance 

between the gas and the walls of the panel for a stoichiometric mixture of methane. The rate at 

which the gas temperature will rise within the panel depends on (1) the number of moles of 

methane, (2) the specific heat capacity of the gas and the heat transfer to the salt and the walls 

through radiation, (3) convection along the vertical and horizontal surfaces, and (4) conduction 

within the salt and walls. The thermal analysis result (DOE, 1996a) showed that the elevated 

temperature due to explosion would propagate a maximum of 6 inches (15 cm) through the wall.

In the event of a hydrocarbon explosion either (1) deflagration will result in a rapid rise of 

pressure, with no transition to a detonation, or (2) a detonation wave front will propagate as a 

supersonic shockwave. The transition to a detonation is a function of two parameters: (1) the 

methane concentration at the time of the explosion, and (2) the ability for a wave front to form. In 

underground excavations, the latter condition typically requires a reasonably long passage through 

which the combustion wave travels and transforms to a detonation. The probability of occurrence 

of a detonation in an air-gas mixture also depends strongly upon the type of air-gas mixture. In 

the case of WIPP, the open passages above the waste stack will reduce in size due to creep closure 

so it is unlikely that a long passage with open geometry will exist. As a result the occurrence of 

detonation in underground excavation at WIPP is very unlikely. Therefore this analysis will only 

consider deflagration.

The peak explosive pressure arising from a deflagration is about eight times (DOE, 1996a) the 

ambient pressure at the time of explosion. The ambient pressure at the time of explosion depends 

on panel volume reduction rate, gas flow rate from WPC, and gas generation rate. In the current 

analysis the ambient pressure will reach a steady value of 1.41 atmosphere in a short time after 

panel closure. This results in a peak explosion pressure of 164 psi (1.14 MPa).

The dynamic load factor will depend on the natural frequency of the explosion isolation wall. The 

value for the dynamic load factor approaches a maximum value of 2, with increased natural 

frequency for a variety of exponential curves (DOE, 1996a). Based upon this loading, the block 

wall will be subjected to an equivalent uniform pressure of 328 psi (2.28 MPa). The result of the 

stress analysis is presented in the next section.
3-24 Rev. 1 10/3/2002

3.2.4 Stress Analysis

The purpose of the stress analysis was to evaluate the interaction of the block wall and run of mine 

salt backfill of the WPC with the surrounding salt. Stresses are expected to develop in the block 

wall component due to continued creep closure of the air-intake and air-exhaust drifts after 

installation of the block wall. Stresses are also expected to develop in the run of mine backfill, 

although at a very much slower rate than in the block wall. It is also shown that each component 

can individually withstand the postulated methane explosion.

3.2.4.1 Block Wall Evaluation

Detailed two-dimensional axisymmetric representations of the WPC were developed using the 

FLAC (Itasca, 2000) computer code. The properties used in these models are presented in 

Appendix C.

FLAC has been used since 1991 to model underground excavations at the WIPP. FLAC is a twodimensional explicit finite difference code that simulates the behavior of rock and soil-like 

structures. The WIPP Reference Creep Law is built into the code and has been verified against the 

WIPP Second Benchmark Problem (Kreig, 1984). The following sections describe the geometry 

and boundary conditions of the models used in the FLAC analysis.

Model Development. A detailed axisymmetric model was developed to investigate the barrier 

under creep loading and combined creep and explosion loading. The geometry of this model is 

shown in Figure 3-6. There are five construction joints in this case, which are spaced evenly in the 

block wall. The construction joints have no cohesion (see Appendix C). The concrete is modeled 

as a Mohr-Coulomb material with a tension cut-off. Three cases were run with different loading 

and strength properties as called for by the ACI Ultimate Strength Design Method (ACI 318-02):

1.4 W

1.2 W + 1.6 E

0.9 W + 1.6 E

where W and E denote the dead load (far-field stress) and explosion load, respectively. All three 

cases used a strength reduction factor of 0.8. In addition to these three cases, a service load case 
3-25 Rev. 1 10/3/2002

concrete

5 m

Figure 3-6 Creep Plus Explosion Model Geometry and Boundary Conditions
3-26 Rev. 1 10/3/2002

was run with all loading and strength properties set to their nominal values. In all cases with an 

explosion load, the explosive force was applied instantaneously, equilibrium was reached, and 

then the force was removed.

Modeling Results. The results from the ultimate strength design cases showed that while some 

compressive failure occurs near the ends of the block wall, the wall maintains a sizable intact 

confined core in every case, thus validating the design. Only the results from the service load case 

are presented here. Profiles of the stress in the block wall caused by an explosion after ten years 

of creep loading are shown in Figure 3-7 and Figure 3-8. The vertical (radial) loading is not 

significantly changed, while the axial loading is actually improved since the stress goes slightly 

compressive rather than tensile. Figure 3-9 and Figure 3-10 show contours of stress in the wall 

and in the rock during the explosion. Figure 3-11 shows the plasticity state in the wall at 35 years. 

This figure shows a limited tensile fracture zone near the rocksalt-concrete interface. Like the 

construction joints, these fractures are normal to the direction of the VOC flow through the WPC 

and have minimal impact on the flow conductance. Figure 3-12 shows a vertical stress profile in 

the block wall at 35 years, the required design life. These figures show that the block wall will 

perform its required function throughout the nominal operational design life. 

3.2.4.2 Run of Mine Salt Backfill Evaluation

The run of mine salt backfill also provides a barrier to resist explosion pressure. To show the 

effectiveness of the salt backfill as an explosion barrier, a simple analytical model was developed. 

The following simplifying assumptions were made to conduct a conservative analysis.

• The run of mine backfill was subjected to all of the explosion loading.

• The explosion pressure is assumed to reach the maximum value of 1.14 MPa 

(Section 3-2-3) instantly and remains constant with negligible decay.

• The confining pressures on the salt backfill due to creep closure of the surrounding rocksalt 

are ignored.

• The geometric and material dampings are ignored.

• The only resistance mechanism is the frictional contact between backfill and rocksalt.

• Backfill material is assumed to be elastic.
3-27 Rev. 1 10/3/2002

Explosion to Right

-24

-22

-20

-18

-16

-14

-12

-10

-5 -4 -3 -2 -1 0 1 2 3 4 5

Distance from center of barrier (m)

Sxx at top of wall (MPa)

Sxx at 10 yr

Sxx Explosion at 10 yr

Figure 3-7 Vertical (Radial) Stress Profile at Top of Block Wall During an Explosion 

Occurring 10 Years after Emplacement

Explosion to Right

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

-5 -4 -3 -2 -1 0 1 2 3 4 5

Distance from center of barrier (m)

Sxx at top of wall (MPa)

Syy at 10 yr

Syy Explosion at 10 yr

Figure 3-8 Horizontal (Axial) Stress Profile at Top of Block Wall During an 

Explosion Occurring 10 Years after Emplacement
3-28 Rev. 1 10/3/2002

Figure 3-9 Vertical (Radial) Stress Contours in Block Wall During an Explosion 

Occurring 10 Years after Emplacement

Figure 3-10 Horizontal (Axial) Stress Contours in Block Wall During an Explosion 

Occurring 10 Years after Emplacement
3-29 Rev. 1 10/3/2002

Figure 3-11 Plasticity State in Block Wall at 35 Years

-35

-30

-25

-20

-15

-10

-5 -4 -3 -2 -1 0 1 2 3 4 5

Distance from center of barrier (m)

Sxx at top of wall (MPa)

Sxx 30 years after wall installed

Figure 3-12 Vertical (Radial) Stress Profile at Top of Block Wall at 35 Years
3-30 Rev. 1 10/3/2002

The strain-stress relations for a general three-dimensional body can be written as (Fung, 1965):



















= − −

= − −

= − −

E E E

E E E

E E E

z x y

z

x z

y

y

x y z

x

s

u

s

u

s

e

s

u

s

u

s

e

s

u

s

u

s

e

(Equation 3-7)

where s x

, s yand s z are the normal stress components in the x , y and z directions, 

respectively, x

e , ye and ze are the corresponding normal strain components, and E and n are 

the Young’s modulus and Poisson’s ratio respectively. 

By taking the x axis as the longitudinal axis along the salt backfill (0 < x < ∞) and setting 

y

e = ze = 0, Equation 3-7 reduces to the following one-dimensional form:

( )

E

K

x

x o

s

e = 1− 2u (Equation 3-8)

where

u

u

−

=

1

Ko

By substituting Equation 3-8 into the one-dimensional strain-displacement relation of du dx xe = /

and defining s x = − p one obtains:

( )

E

p

K

dx

du

= − 1− 2u o(Equation 3-9)

where u = u(x,t) is the axial displacement along the x axis at time t . 

The applied forces on a longitudinal backfill element of length dx are shown in Figure 3-13. 

Equilibrium of these forces along the x axis results in:

A dx p dp A K p Q dx

t

u

p A r + + + m o

∂

∂

= ( )

2

2

(u, x, t > 0) (Equation 3-10)
3-31 Rev. 1 10/3/2002

in which:

r = mass density

m = coefficient of friction

A = cross-sectional area of backfill

Q = perimeter of backfill in cross section

A dx

t

u

2

2

∂

∂

r = inertia force

K p Q dx m o = friction force along the perimeter of backfill

Using Equation 3-9, Equation 3-10 can be further simplified as:

2 0

2

2

2

2

2

2 =

∂

∂

+

∂

∂

−

∂

∂

x

u

C

t

u

x

u

C l (u, x, t > 0) (Equation 3-11)

where

(1 2 ) Ko

E

C

r − u

=

A

Ko Q

2

m

l =

Equation 3-11 is subjected to zero displacement and velocity as initial conditions. Also, from 

Equation 3-9, the following boundary condition is applied:

( )

( )

1 2

(0, ) P t

E

K

t

x

u − u o = −

∂

∂

(Equation 3-12)

where P(t) is the explosion pressure at the explosion face. By ignoring the reflected wave effect 

from the far end of the backfill, Equation 3-11 is solved using the central finite difference method. 

The elastic parameters for run of mine salt ( E = 20.1 MPa, u = 0.25) were adopted from Callahan 

and DeVries (1991). A conservative value of 25 degrees similar to loose silt or silty sand (Bowls, 

1982) was used for the friction angle of run of mine salt.
3-32 Rev. 1 10/3/2002

Figure 3-14 shows the result of the analysis. Based on this figure, the displacement of the salt at 

the explosion face is 13.8 inches (0.350 m) when the maximum displacement at the opposite end 

is about 0.4 inches (0.01 m). This verifies that the run of mine salt backfill performs as an 

effective explosion barrier.

3.2.5 Fracture-Propagation Evaluation

The fracture-propagation studies evaluate the potential for fracture propagation, using the results 

of previous analyses. The results of the thermal analysis suggest that elevated temperatures within 

an explosion isolation wall and salt will be a localized phenomenon. During an explosion two 

phenomena could affect the potential fracturing of the salt: (1) the expansion of the explosion 

products into existing fractures, and (2) the potential reflection of sonic waves off free surfaces 

around the barrier. The fractures in the roof and floor could be affected by the expansion of the 

gas products on the order of 164 psi (1.14 MPa), which decay rapidly with time and attenuate with 

distance. Around the wall, the confining stress on the order of 2,100 psi (15 MPa) will develop. 

Horizontal fracture propagation could occur around the barrier only if the internal gas pressure 

exceeds confining pressure. Because the peak internal pressure from deflagration is less than ten 

percent of the confining pressure, fractures would not propagate through or around the main wall.

Following an explosion, the wall would be subject to sonic waves that would impinge on the wall. 

As the sonic wave encounters a contrast in wall stiffness, a portion of the sonic wave would be 

refracted, and a portion would be reflected (Jaeger and Cook, 1972). This would result in minor 

tensile spalling of the isolation wall. The salt backfill causes a partial wave transmission and 

damping which in turn reduces the reflected tensile wave. At the time of a potential explosion, the 

development of confining stress relative to the explosion pressure would prevent fracturing around 

the block wall. The block wall can safely withstand the pressure from the postulated methane gas 

explosion.
3-33 Rev. 1 10/3/2002

Figure 3-13 Applied Forces on a Longitudinal Element of Backfill

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0 5 10 15 20 25 30

Distance from Explosion Face (m)

Displacement (m)

Explosion 

Face

Run of 

Mine Salt

Figure 3-14 Dynamic Displacement versus Distance from Explosion Face

Inertia Force

Friction Force

p p+dp

dx
4-1 Rev. 1 10/3/2002

4.0 Design Calculations

All calculations were performed in accordance with the RockSol Consulting Group, Inc., Quality 

Assurance Program and comply with Westinghouse TRU Solutions requirements. The 

documentation for the codes and calculations, as well as related documents such as verification 

and validation tests, constitute quality records and are maintained in accordance with WIPP 

procedures. 

The bases for all calculations are presented in Chapter 3 and Appendices A, B, and C. All 

software for the design calculations have been documented, verified and validated in accordance 

with the RockSol Consulting Group, Inc. Quality Assurance Program. This program complies 

with the requirements of the Westinghouse TRU Solutions QA Program.
5-1 Rev. 1 10/3/2002

5.0 Technical Specifications

The specifications are in the engineering file room at the WIPP and are the property of 

Westinghouse. These specifications are included as an attachment in Appendix D and are 

summarized in Table 5-1.

Table 5-1 Technical Specifications for the WIPP Panel Closure System

Division 1 - General Requirements

Section 01010 Summary of Work

Section 01090 Reference Standards

Section 01400 Contractor Quality Control

Section 01600 Material and Equipment

Division 2 - Site Work

Section 02010 Mobilization and Demobilization

Section 02222 Excavation

Division 3 - Masonry

Section 03100 Mortar

Section 03300 Unit Masonry System

Section 03400 Masonry Explosion Isolation Structure

Division 4 - Salt Backfill

Section 04100 Salt Backfill
6-1 Rev. 1 10/3/2002

6.0 Drawings

The Drawings (Appendix E) are in the engineering file room at the WIPP and are summarized in 

Table 6-1.

Table 6-1 WIPP Panel Closure System Drawings

Drawing Number Title

110-CD001 Panel closure system, title sheet

110-CD002 Panel closure system, underground waste disposal panel 

110-CD003 Panel closure system, construction details
7-1 Rev. 1 10/3/2002

7.0 Conclusions

This chapter presents the conclusions for the detailed design activities for the WPC. Table 7-1

shows the performance specifications for the WPC and the compliance of the design with the 

performance specifications. The design configuration and essential features for the WPC include 

an explosion isolation wall constructed of 5000 psi (34.5 MPa) unconfined compressive strength 

blocks that is 30 ft (9.1 m) long, and a run of mine salt backfill section that is 100 ft (30.5 m) long. 

Surface treatment around the explosion isolation wall includes the removal of loose material to 

create a clean, regular surface for construction of the block wall.

The design is presented in this report as performance specifications, a series of calculations, and 

engineering Drawings and Specifications. Structural analyses used to select the design length and 

other design features are based upon data acquired from the WIPP underground. The Drawings 

illustrate and describe the construction and details for the system. The Specifications cover the 

general requirements of the system, quality assurance and quality control, site work, masonry, and 

run of mine salt backfill. Information on the proposed construction method is also presented. The 

WPC can be built to generally-accepted national design and construction standards.

The design complies with all aspects of the design basis established for the WPC. The design can 

be constructed in the underground environment with no special requirements at the WIPP. To 

investigate several key design issues and to implement the design, design evaluations were 

performed. The conclusions reached from the evaluations are as follows:

• The mass flow rates for different VOCs through the WPC (including flow through the DRZ, 

the explosion isolation wall, and run of mine salt backfill) are substantially below the limits 

established in the HWFP for the E-300 drift.

• The Monte Carlo Simulation Method was used to assess the uncertainty of VOCs headspace 

concentrations, gas generation rates, and panel volume closure rates on the mass flow rate 

of carbon tetrachloride. The time required to reach the steady-state mass flow rate of 

carbon tetrachloride depends on the intrinsic permeability of the flow components. In some 

realizations the mass flow rate rises rapidly to the steady-state mass flow rate and the flow 

is essentially unrestricted. In most cases, however, the WPC offers resistance to flow, and 

mass flow rates would develop more slowly. In all cases, the explosion isolation wall with 

the run of mine salt backfill complies with the mass flow rate limit at the E-300 drift.

• The passive design components of the WPC do not require routine maintenance during the 
7-2 Rev. 1 10/3/2002

nominal operational life of 35 years.

• Thermal cracking due to heat of hydration effects does not apply to concrete blocks. 

• The trace amounts of brine from the salt at the repository horizon would not degrade the 

main concrete barrier for at least 35 years.

• Detailed axisymmetric models were developed to assess the state of stress in the block wall 

and surrounding rock due to creep closure of the salt. The length selected for the explosion 

isolation wall provides for a substantial margin of safety against structural failure due to 

creep loading. 

• Stress analysis shows that the wall will withstand both the forces of creep and the postulated 

methane explosion. Further, at the time of a potential explosion, the development of 

confining stress would prevent fracturing around the block wall.

• The heat-transfer analysis in the previous PCS design (DOE, 1996a) showed that elevated 

temperatures would occur within the salt and the explosion isolation wall; however, the 

elevated temperatures will be isolated by the PCS. Temperature gradients will not 

significantly affect the stability of the wall.

• The WPC provides for flexibility over the 35-year operational life in construction 

scheduling and construction material transportation and therefore minimizes the effect on 

waste receipt. 

In addition to the design requirements presented above, the design includes a QA/QC program to 

verify material properties and construction practices. The existing shafts and underground access 

can accommodate the construction of the WPC.
7-3 Rev. 1 10/3/2002

Table 7-1 Compliance with Performance Specifications

Requirement

Design 

Report 

Section

Compliance 

with 

Requirement

Notes on Compliance

The panel closure system design shall limit VOC migration 

from a closed panel consistent with the limits found in Table 

IV.F.2.c of the HWFP.

3.1

Complies

Gas-flow modeling shows that the VOC flow is substantially 

less than the E-300 drift limit specified in the HWFP.

The panel closure system shall consider potential flow of 

VOCs through the disturbed rock zone (DRZ) in addition to 

flow through closure components.

3.1

Complies

Restricted gas-flow model considers flow through the DRZ.

The panel closure system shall perform its intended functions 

under loads generated by creep closure of the tunnels.

3.2.4 Complies Stress analyses and design calculations show that the WPC 

performs as intended under creep closure.

The panel closure system shall perform its intended function 

under the conditions of a postulated methane explosion.

3.2.3

3.2.4

3.2.5

Complies

The methane explosion studies, fracture propagation studies, 

and supporting design calculations show that the WPC 

performs as intended.

The nominal operational life of the closure system is thirty-five 

(35) years.

3.1

3.2

Complies Gas-flow modeling and stress analyses shows satisfactory 

performance for 35 years.

The panel closure system for each individual panel shall not 

require routine maintenance during its operational life.

2.2 Complies Passive design components require no routine maintenance.

The panel closure system shall address the most severe ground 

conditions expected in the waste disposal area.

3.1

3.2

Complies Design is based upon flow and structural analyses of the 

most severe ground conditions.

The design class of the panel closure system shall be IIIb 

(which means that it is to be built to generally accepted 

national design and construction standards).

2.3

Complies

The construction sequence for the design followed 

conventional mining practices.

The design and construction shall follow conventional mining 

practices.

2.2

2.3 Complies

The specifications include normal construction practices used 

in the underground at WIPP and according to the most 

current mortar and concrete block specifications.
7-4 Rev. 1 10/3/2002

Table 7-1 (Continued) Compliance with Performance Specifications

Requirement

Design 

Report 

Section

Compliance 

with 

Requirement

Notes on Compliance

Structural analysis shall use data acquired from the WIPP 

underground.

3.2.4

Complies

The structural analysis uses properties that model creep 

closure for stress analyses from data acquired in the WIPP 

Geotechnical Monitoring Program.

Materials shall be compatible with their emplacement 

environment and function.

3.2.1 Complies The material compatibility studies showed no degradation of 

materials and no need for surface treatment.

Treatment of surfaces in the closure areas shall be considered 

in the design.

Appendix D Complies Design specifications address surface treatment

Thermal cracking of concrete shall be addressed. 3.2.2 Complies Thermal cracking due to heat of hydration effects do not 

apply to concrete blocks.

During construction, a Quality Assurance/Quality Control 

(QA/QC) program shall be established to verify material 

properties and construction practices.

Appendix D

Complies

The specifications include materials testing to verify material 

properties and construction practices.

Construction of the panel closure system shall consider shaft 

and underground access and services for materials handling.

Appendix D Complies The specifications allow construction within the capacities of 

underground access.
8-1 Rev. 1 10/3/2002

8.0 References

American Concrete Institute (ACI), 2002, "Building Code Requirements for Structural Concrete 

and Commentaries," ACI 318-02, American Concrete Institute, Farmington Hills, Michigan.

American Concrete Institute (ACI), 2002, "Building Code Requirements for Masonry Structures & 

Specification for Masonry Structures & Commentaries," ACI 530.1-02, American Concrete 

Institute, Farmington Hills, Michigan.

American Society for Testing and Materials (ASTM), 2002, "Standard Practice for Laboratories 

Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Laboratory 

Evaluation," ASTM C 1077-02, American Society for Testing and Materials, West Conshohocken, 

Pennsylvania.

American Society for Testing and Materials (ASTM), 2002, "Standard Practice for Agencies 

Performing Nondestructive Testing," ASTM E 543-02, American Society for Testing and 

Materials, West Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 2002, "Standard Specification for Aggregate 

for Masonry Mortar," ASTM C 144-02, American Society for Testing and Materials, West 

Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 2002, "Standard Specification for Portland 

Cement," ASTM C 150-02, American Society for Testing and Materials, West Conshohocken, 

Pennsylvania.

American Society for Testing and Materials (ASTM), 2002, "Standard Test Method for 

Compressive Strength of Masonry Prisms," ASTM C 1314-02a, American Society for Testing and 

Materials, West Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 2002, "Standard Test Method for 

Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry," 

ASTM C 780-02, American Society for Testing and Materials, West Conshohocken, Pennsylvania

American Society for Testing and Materials (ASTM), 2002, "Standard Test Methods for Sampling 

and Testing Concrete Masonry Units and Related Units," ASTM C 140-02, American Society for 

Testing and Materials, West Conshohocken, Pennsylvania.
8-2 Rev. 1 10/3/2002

American Society for Testing and Materials (ASTM), 2001, "Standard Practice for Accreditation 

of Testing Agencies for Unit Masonry," ASTM C 1093-95, American Society for Testing and 

Materials, West Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 2001, "Standard Specification for Extended 

Life Mortar for Unit Masonry," ASTM C 1142-95, American Society for Testing and Materials, 

West Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 2001, "Standard Specification for Concrete 

Brick," ASTM C 55-01a, American Society for Testing and Materials, West Conshohocken, 

Pennsylvania.

American Society for Testing and Materials (ASTM), 2001, "Standard Specification for Agencies 

Engaged in the Testing and/or Inspection of Materials Used in Construction," ASTM E 329-01a, 

American Society for Testing and Materials, West Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 2001, "Standard Specification for Mortar 

for Unit Masonry," ASTM C 270-01a, American Society for Testing and Materials, West 

Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 2001, "Standard Specification for Masonry 

Cement," ASTM C 91-01, American Society for Testing and Materials," West Conshohocken, 

Pennsylvania. 

American Society for Testing and Materials (ASTM), 2000, "Standard Specification for ReadyMixed Concrete," ASTM C 94-00, American Society for Testing and Materials, West 

Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 1997, "Standard Specification for Hydrated 

Lime for Masonry Purposes," ASTM C 207-91, American Society for Testing and Materials, West 

Conshohocken, Pennsylvania.

American Society for Testing and Materials (ASTM), 1994, "Standard Guide for General Criteria 

Used for Evaluating Laboratory Competence," ASTM E 548-94, American Society for Testing and 

Materials, West Conshohocken, Pennsylvania. 

Biggs, J., 1964, Introduction to Structural Dynamics, McGraw Hill, New York, New York.
8-3 Rev. 1 10/3/2002

Bowles, E., 1982, Foundation Analysis and Design, McGraw-Hill, New York, New York.

Callahan, G. D., and K. L. DeVries, 1991, "Analyses of Backfilled Transuranic Wastes Disposal 

Rooms," SAND91-7052, Sandia National Laboratories, Albuquerque, New Mexico.

Case, J. B., and P. C. Kelsall, 1986, "Shaft-Seal Modeling and Analysis of the Small Scale Seal 

Performance Tests at the Waste Isolation Pilot Plant," IT Corporation, Albuquerque, New Mexico.

Case, J. B., P. C. Kelsall, and J. L. Withiam, 1987, "Laboratory Investigation of Crushed Salt 

Consolidation," Rock Mechanics: Proceedings of the 28th US Symposium, Edited by: I. W. Farmer,

J. J. K. Daemen, C. S. Desai, C. E. Glass, and S. P. Neuman, Tucson, Arizona, pp189-196.

Daemen, J. J. K., J. C. Stormont, N. I. Colburn, D. L. South, S. A. Dischler, K. Fuenkajorn, W. 

Greer, G. S. Adisoma, D. E. Miles, B. Kousari, and J. Bertucca, 1983, "Rock Mass Sealing 

Experimental Assessment of Borehole Plug Performance," NUREG/CR3483, University of 

Arizona, Tucson Arizona.

Fernandez, J. A., J. B. Case, C. A. Givens, and B. C. Camey, 1994, "A Strategy to Seal 

Exploratory Boreholes in Unsaturated Tuff," SAND93-1184, Sandia National Laboratories, 

Albuquerque, New Mexico.

Freeze, A., and J. Cherry, 1979, Groundwater, Prentice Hall, Inc., Englewood Cliffs, New Jersey.

Fung, Y. C., 1965, Foundations of Solid Mechanics, Prentice-Hall, Inc., Englewood Cliffs, New 

Jersey.

Hahn, G. J., and S. S. Shapiro, 1967, Statistical Models in Engineering, John Wiley & Sons, New 

York, New York.

IT Corporation (IT), 1994, "Backfill Engineering Analysis Report," report prepared for 

Westinghouse Electric Corporation, Carlsbad, New Mexico.

Itasca Consulting Group, Inc. (Itasca), 2000, "FLAC User's Manual," Itasca Consulting Group, 

Inc., Minneapolis, Minnesota.

Jaeger, J. C., and N. G. W. Cook, 1972, Fundamentals of Rock Mechanics, John Wiley and Sons, 

New York, New York.
8-4 Rev. 1 10/3/2002

Krieg, R. D., 1984, "Reference Stratigraphy and Rock Properties for the Waste Isolation Pilot 

Plant," SAND83-1908, Sandia National Laboratories, Albuquerque, New Mexico.

Lindeburg, M. R., 1986, Civil Engineering Reference Manual, Professional Publications, Inc.

MathSoft, 1999, Mathcad 2000 User’s Guide, MathSoft, Inc., Cambridge Massachusetts.

Mine Safety and Health Administration (MSHA), 2002, "Safety Standards for Methane in Metal 

and Nonmetal Mines," Title 30, Code of Federal Regulations (CFR), Part 57 (30 CFR 57),

U.S. Department of Labor, Mine Safety and Health Administration, Washington, D.C.

New Mexico Environment Department, 2000, "Adoption of 40 CFR Part 264," Title 20 

(Environmental Protection) of the New Mexico Administrative Code, Chapter 4 (Hazardous 

Waste), Part 1 (Hazardous Waste Management), New Mexico Hazardous and Radioactive 

Materials Bureau, Santa Fe, New Mexico.

Portland Cement Association (PCA), 2002, "Fundamentals of Concrete, " ISO54, Portland Cement 

Association, Skokie, Illinois.

U.S. Department of Energy (DOE), 1996a, "Detailed Design Report for an Operational Phase 

Panel Closure System," DOE/WIPP 96-2150, U.S. Department of Energy, WIPP Project Office, 

Carlsbad, New Mexico.

U.S. Department of Energy (DOE), 1996b, "WIPP Compliance Certification Application 40 CFR 

191 Subpart B and C." CD-ROM Version prepared by the Carlsbad Technical Assistance 

Contractor, Roy F. Weston, Carlsbad, New Mexico.

U.S. Department of Energy (DOE), 1995, "Conceptual Design for Operational Phase Panel 

Closure Systems," DOE-WIPP-95-2057, U.S. Department of Energy, WIPP Project Office, 

Carlsbad, New Mexico.

U.S. Department of Energy (DOE), 1994, "Panel 1 Utilization Plan." WIPP/WID-94-2027, 

Westinghouse Electric Corporation, Carlsbad, New Mexico.

U.S. Environmental Protection Agency (EPA), 2001, "Standards for Owners and Operators of 

Hazardous Waste Treatment, Storage, and Disposal Facilities," Title 40 (Protection of 

Environment) of the Code of Federal Regulations, Part 264, U.S. Government Printing Office.
8-5 Rev. 1 10/3/2002

WIPP Waste Information System, 2002, "Headspace Gas Concentration Report," Report RP0430, 

4/25/2002.

WIPP Hazardous Waste Facility Permit, NM 4890139088-TSDF, Aug. 31, 2001, Module IV -

Geologic Repository Disposal.

Westinghouse TRU Solutions, 2002, "Mining/Emplacement Schedule," June 1st 2002 update.
APPENDIX A

DERIVATION OF RELATIONSHIPS FOR THE

AIR-FLOW MODELS
A-1 Rev. 1 10/3/2002

APPENDIX A

DERIVATION OF RELATIONSHIPS FOR THE

AIR-FLOW MODELS

A.1.0 Introduction

This appendix presents the derivation of unrestricted and restricted air-flow models used to 

determine the performance of the panel closure system. These derivations were used in the 

analyses in Section 3.1 to determine gas flow from a panel. These analyses provide an estimate 

of the volume of gas that might flow through the panel closure systems at the Waste Isolation 

Pilot Plant (WIPP).

A.2.0 Model for Unrestricted Flow of VOCs

A model for the unrestricted flow of volatile organic compounds (VOCs) was developed to 

predict the mass flow rates of VOCs and to compare these mass flow rates with the design 

migration limits for VOCs. Over time, a mixture of gases containing VOCs flows from each 

waste container. It is assumed for the unrestricted flow model that the headspace concentrations 

serve as a constant source of VOCs. This assumption is conservative because most containers 

only have trace quantities of VOCs, either trapped in the headspace or on the surfaces of the 

various waste components. It is likely that only a small number of waste containers have a 

significantly greater source of VOCs such as a solvent-soaked rag. Only this small number of 

waste containers have a realistic likelihood of maintaining a constant headspace VOC 

concentration as gas generation proceeds.

The VOCs originating from the waste containers can migrate from the panel due to volumetric 

creep closure of the panel void space and to gas generation due to microbial degradation of the 

waste. Because flow is unrestricted, the VOCs migrate under a pressure of one atmosphere. 

Other assumptions in the unrestricted flow model are as follows:

• Any gases released into the mine atmosphere would be reduced in concentration by the 

minimum ventilation rate of 260,000 ft3/min (7,362 m3/min) required by HWFP at E-300 

drift. The mass flow rate of individual VOCs from individual panels following their 

closure is summed to determine the mass flow rate of VOCs at E-300 drift.

• The analysis uses the schedule for closure of individual panels (Westinghouse, 2002) as 

illustrated in Table A-1 during the operational life of the panel closure system.
A-2 Rev. 1 10/3/2002

• Open panels of waste are not considered as a source contributing to the emissions of 

VOCs.

Considering only advection in the migration of VOCs, the mass-balance relationship is 

(DOE, 1996):

Cp Qp CE300 QE300 ⋅ = ⋅ (Equation A-1)

where

Cp = Headspace concentration for an individual VOC

Qp = Flow rate of VOCs from the panel

CE300 = Concentration of VOCs at the E-300 drift

QE300 = Underground ventilation flow rate at the E-300 drift

Table A-2 presents the maximum headspace concentrations for different VOCs of concern. The 

total flow rate of VOCs from the panel can be obtained as follows (DOE, 1996):

Qp = Qgr + Qc(Equation A-2)

where

Qgr = Volumetric flow rate due to gas generation

Qc = Volumetric flow rate due to panel volumetric closure

The volumetric flow rate due to gas generation is calculated as the gas generation rate (0.1 moles 

per drum per year) times the number of drums within a panel times the specific volume under 

atmospheric pressure. The VOCs concentrations at the E-300 drift must be restricted to the 

limits found in Table IV.F.2.c of the HWFP, which are shown in Table A-3.
A-3 Rev. 1 10/3/2002

Table A-1 Schedule for Panel Closure

(After Westinghouse, 2002)

Panel # Closure time (years)

1 5.11

2 6.15

3 7.36

4 9.39

5 11.93

6 14.55

7 17.38

8 23.18

9 28.98

10 35.00

Table A-2 Maximum Headspace Concentrations for VOCs

(After DOE, 1996, and WIPP Waste Information System Headspace Gas 

Concentration Report, 2002)

Compound

Maximum Headspace 

Concentration (milligrams 

per cubic meter)

Carbon Tetrachloride 3625.77

Chlorobenzene 63.99

Chloroform 76.79

1,1-Dichloroethene 48.68

Methylene Chloride 3387.03

1,1,2,2-Tetrachloroethane 69.65

Toluene 105.51

1,2-Dichloroethane 1.24

1,1,1-Trichloroethane 145.75
A-4 Rev. 1 10/3/2002

Table A-3 VOC Concentrations of Concern 

(After Table IV.F.2.c of the HWFP. This list of VOCs is the same as the list of 

VOCs in the previous design (DOE, 1996a) except for 1,2-dichloroethane and 

1,1,1-trichloroethane.)

Compound

Drift E-300 Concentration 

Limit (micrograms per cubic 

meter)

Carbon Tetrachloride 1050

Chlorobenzene 1015

Chloroform 890

1,1-Dichloroethene 410

Methylene Chloride 6700

1,1,2,2-Tetrachloroethane 350

Toluene 715

1,2-Dichloroethane 175

1,1,1-Trichloroethane 3200
A-5 Rev. 1 10/3/2002

A.3.0 Model for Restricted Flow of VOCs

The assumptions for the restricted air-flow model are as follows:

• Gases (including VOCs) within the void space will obey the Ideal Gas Law. The gases 

will be generated at a rate of 0.1 moles per drum per year and will be stored by an increase 

in gas pressure. The rate of pressure buildup will be so gradual that it occurs at constant 

temperature.

• Volumetric reduction due to creep will reduce the void space at a rate of 31,430 ft3 (890 

m

3

) per year (Appendix B) and will result in pressurization.

• Flow of gas out of the panel will obey Darcy's Law under quasi steady-state conditions. 

Under quasi steady-state conditions, the air pressure within the panel closure system will 

change so gradually that the compressive storage of the air within the void space of the 

panel closure system could be neglected.

• Rates of gas generation, air outflow, and change in compressive storage will balance.

• Hydrodynamic dispersion through the barrier will be neglected.

• Analysis will consider the superposition of flow rates from individual panels according to 

the operating schedule for a nominal operational life of 35 years.

After panel closure, the volume, moles of gas, and pressure change as functions of time. The 

Ideal Gas Law (Hiller and Herber, 1960) is written as:

V

n R T

p

⋅ ⋅

= (Equation A-3)

where

p = Pressure in the panel

n = Moles of gas in the panel

R = Universal gas constant

T = Absolute temperature

V = Volume of the panel void space
A-6 Rev. 1 10/3/2002

Differentiating Equation A-3 with respect to time t and using the chain rule results in:

2 V

dt

dV V n

dt

dn

R T

dt

dp ⋅ − ⋅

= ⋅ ⋅ (Equation A-4)

The rate at which gas enters the panel minus the rate that gas leaves the panel must equal the 

change in moles stored. Therefore, the mass-balance relationship can be written as follows 

(DOE, 1996):

g

atm

r s

p p

L

A

K

R T

p

g

dt

dn −

⋅ ⋅ ⋅

⋅

= − (Equation A-5)

where

gr = Panel gas generation rate

patm = Atmospheric pressure

g = Air density

Ks = Effective panel closure system conductivity

A = Cross-sectional area

L = Length of flow path

Conductance (C) can be defined as follows:

L

A

C Ks = ⋅ (Equation A-6)

Substituting into the ordinary differential equations, the following relations can be obtained:

2

( )

V

dt

dV V n

p p

C

R T

p

g

R T

dt

dp

atm

r

⋅ − ⋅

−

⋅ ⋅

⋅

−

= ⋅ ⋅

g

(Equation A-7)

g

atm

r

p p

C

R T

p

g

dt

dn −

⋅ ⋅

⋅

= − (Equation A-8)
A-7 Rev. 1 10/3/2002

These two first-order coupled ordinary differential equations can be solved by a simple explicit 

finite difference technique as follows:

t

V

dt

dV V n

p p

C

R T

p

g

p p R T

j

j j atm

r

j j

⋅Δ

⋅ − ⋅

−

⋅ ⋅

⋅

−

= + ⋅ ⋅

−

− −

− 2

1

1 1

1

( )

g

(Equation A-9)

t

p p

C

R T

p

n n g

j j atm

j j r

⋅Δ

−

⋅ ⋅

⋅

= + −

− −

−

( )

1 1

1

g

(Equation A-10)

where

p j, n j = the pressure and moles of gas at the current time step

p j−1, n j−1 = the pressure and moles of gas at the previous time step

The initial conditions for the ordinary differential equations include: (1) the initial pressure 

equals atmospheric pressure; and (2) the initial moles of gas can be determined by the Ideal Gas 

Law at initial volume and pressure. Further note that the volume can be approximated as a linear 

function of time:

V (t) =a ⋅t + b (Equation A-11)

where

a = Slope of the volume-time relationship

b = Intercept of volume-time relationship

t = Time

These expressions can be substituted into the above explicit finite difference relationships, and 

the pressure and molar air-flow rates can be determined as functions of time.

A4.0 Effective Intrinsic Permeability of a Parallel System

The effective flow conductance for a parallel system consisting of n flow components can be 

obtained in terms of the conductances of its flow components as follows (Freeze and 

Cherry, 1979):
A-8 Rev. 1 10/3/2002

∑

=

=

n

i

Ct Ci

1

(Equation A-12)

where

Ct = Total flow conductance of the system 

Ci = Flow conductance of the th i component 

Based on the definition of flow conductance (Equation A-6), Equation A-12 can be rewritten as:

∑

=

=

n

i

i

i

t

t

L

A

K

L

A

K

1

(Equation A-13)

or

t

n

i

i i

t

A

K A

K

∑

=

=

1

(Equation A-14)

where

Kt = Effective conductivity of the system 

Ai = Cross-sectional area of the th i component

At = Total cross-sectional area of the system (∑

=

n

i

Ai

1

)

L = Length of flow path

A5.0 Effective Intrinsic Permeability of a Series System

The effective flow conductance for a series system consisting of n flow components can be 

obtained in terms of the conductances of its flow components as follows (Freeze and 

Cherry, 1979):

∑

=

=

n

i

Ct 1Ci

1 1

(Equation A-15)
A-9 Rev. 1 10/3/2002

where

Ct = Total flow conductance of the system 

Ci = Flow conductance of the th i component 

Based on the definition of flow conductance (Equation A-6), Equation A-15 can be rewritten as 

follows:

∑

=

=

n

i

i

i

t

t

K A

L

K A

L

1

(Equation A-16)

or

∑

=

=

n

i

i

i

t

t

K

L

L

K

1

(Equation A-17)

where

Kt = Effective conductivity of the system 

Li = Length of flow path for th i component

Lt = Total length of flow path (∑

=

n

i

Li

1

)

A = Cross-sectional area of the flow path

A6.0 References

Freeze, A., and J. Cherry, 1979, Groundwater, Prentice Hall, Inc., Englewood Cliffs, New 

Jersey.

Hiller, L., and R. Herber, 1960, Principles of Chemistry, McGraw-Hill Book Company, New 

York.

U.S. Department of Energy (DOE), 1996, "Detailed Design Report for an Operational Phase 

Panel Closure System," DOE/WIPP 96-2150, U.S. Department of Energy, WIPP Project Office, 

Carlsbad, New Mexico.
A-10 Rev. 1 10/3/2002

Westinghouse TRU Solutions, 2002, "Mining/Emplacement Schedule," June 1st 2002 update.

WIPP Hazardous Waste Facility Permit, NM 4890139088-TSDF, Aug. 31, 2001, Module IV -

Geologic Repository Disposal.

WIPP Waste Information System, 2002, "Headspace Gas Concentration Report", Report 

RP0430, 4/25/2002.
APPENDIX B

CALCULATIONS OF PANEL VOLUME CLOSURE
B-1 Rev. 1 10/3/2002

APPENDIX B

CALCULATIONS OF PANEL VOLUME CLOSURE

B.1.0 Introduction

This appendix presents the closure mechanisms and supporting calculations for panel volumetric 

closure for the analysis of gas pressurization within a closed panel at the WIPP. The volume 

reduction is due to the panel volume change from viscoplastic creep closure of the walls, roof, 

and floor. As the walls, roof, and floor of the excavations converge, the total volume of the 

panel decreases. The volumetric closure of a panel is the result of several different mechanisms 

working simultaneously. These mechanisms include:

• Viscoplastic creep of the salt toward the excavation

• Fracturing in the roof and floor caused by the deviatoric stresses around the excavation

• Bed separation at the clay seams in the roof and the floor.

The combination of these three mechanisms causes the observed convergence rates in Panels 1 

and 2. Of these mechanisms, only creep of the salt reduces the total volume of the panel and 

pore space in the surrounding disturbed rock zone (DRZ). Fracturing in the roof and floor and 

bed separation transfer the void volume within the excavation to the DRZ. This void volume 

within the DRZ is assumed to be interconnected with the open excavation. Therefore the total 

reduction in volume within the panel, based simply on room closure, overestimates the effective 

reduction in void volume. However, quantifying the amount of interconnected void space within 

the DRZ would require a much more detailed analysis. Using the total volume change calculated 

from the room closure measurements is therefore considered conservative.

Other assumptions made in this calculation are:

• The volumetric closure rates are constant after panel closure.

• The waste in the panel provides no significant resistance to creep closure during the initial 

35 years.

• The air volume is the total volume of the excavations minus the solid volume of the waste 

in drums or other waste packages. The solid volume is estimated to be 3,908 m3

(138,000 ft3) (DOE, 1996).
B-2 Rev. 1 10/3/2002

• The closure rate of each room in the panels equals the closure rate at the mid-width and 

mid-height of the room.

• The length of each room or drift is constant. To simplify the calculations, only the width 

and height change with creep closure.

B.2.0 Panel Volume Change Calculation

The panel volume change calculation is performed in steps. First, the initial panel volume is 

calculated, then the room and drift closure rates are calculated, and finally the panel volumetric 

closure rate is determined. Because the closure rates and the closure history in Panel 2 are 

different than Panel 1, the volume calculations for each panel are done separately. Following is a 

detailed description of each part of the calculation for Panel 1 and then for Panel 2.

B.2.1 Panel 1 Volume Change Calculation

B.2.1.1 Initial Panel Volume

The initial panel volume is determined immediately after completion of excavation. The total 

volume is calculated by summing the individual room and drift volumes within the panel. These 

volumes are based on the as-built dimensions of the excavated rooms and drifts in Panel 1 

(DOE, 1993). Table B-1 presents the room and drift dimensions and the calculated volume of 

each room and drift. The total initial volume of Panel 1 is 47,757 m

3

 (1,686,500 ft3).

The total solid volume of the waste in a filled panel is 3,908 m3 (138,000 ft3) (DOE, 1996). 

Subtracting the waste volume from the total panel volume gives the total initial void volume 

(43,850 m

3

 [1,548,500 ft3]) in the panel.

B.2.1.2 Closure Rates

Using convergence data from Panel 1 the average closure rates of the rooms and drifts are 

determined. Closure rates within the rooms and drifts are higher in the first five years after 

excavation. When Panel 2 mining began, closure rates in Panel 1 increased about 30% on 

average. Therefore, three distinct time periods are considered: 0 to 5 years, 6 to 13 years, and 

beyond 13 years. The roof-to-floor and wall-to-wall closure rates for each of the rooms and 

drifts are presented in Table B-2.

Because data from the east end of S1600 are not available for the Panel 2 mining period, the 

rates beyond five years for this area are assumed to be the same as in the west end of S1600 in 

the panel. 
B-3 Rev. 1 10/3/2002

Table B-1 Initial Room and Drift Dimensions and Volume of Panel 1

Room or Drift

Initial 

Width

(m)

Initial 

Height

(m)

Initial 

Length

(m)

Initial 

Volume

(m3)

Room 1 10.06 3.96 91.44 3644

Room 2 10.06 3.96 91.44 3644

Room 3 10.06 3.96 91.44 3644

Room 4 10.06 3.96 91.44 3644

Room 5 10.06 3.96 91.44 3644

Room 6 10.06 3.96 91.44 3644

Room 7 10.06 4.27 91.44 3925

S1950: Room 1 to Room 7 10.06 4.27 258.5 11094

S1950: Access to Room 1 6.10 3.96 12.18 294

S1600: Room 1 to Room 5 10.06 3.96 174.7 6961

S1600: Room 5 to Room 7 10.06 4.27 79.86 3428

S1600: Access to Room 1 4.27 3.66 12.18 190

Total Initial Panel Volume 47757

Table B-2 Panel 1 Room and Drift Closure Rates

Vertical Closure Rates Horizontal Closure Rates

Room or Drift 0 to 5 

Years 

(cm/yr)

6 to 13 

Years 

(cm/yr)

> 13 

Years 

(cm/yr)

0 to 5 

Years 

(cm/yr)

6 to 13 

Years 

(cm/yr)

> 13 

Years 

(cm/yr)

Room 1 9.736 6.234 7.130 6.81 3.138 4.006

Room 2 9.736 6.303 6.057 6.81 3.688 4.446

Room 3 9.736 5.493 6.743 6.81 4.067 5.665

Room 4 9.736 5.441 6.496 6.81 3.831 4.496

Room 5 9.736 5.345 6.495 6.81 3.836 4.879

Room 6 9.736 5.305 6.933 6.81 2.913 3.976

Room 7 9.736 5.687 6.642 6.81 3.579 4.578

S1950: Room 1 to Room 7 9.736 5.513 11.594 6.81 3.370 5.612

S1950: Access to Room 1 5.878 4.436 6.490 5.09 2.674 4.079

S1600: Room 5 to Room 7 9.736 5.064 6.054 6.81 3.212 3.935

S1600: Room 1 to Room 5 9.736 5.064 6.054 6.81 3.212 3.935

S1600: Access to Room 1 3.478 1.753 1.938 4.01 1.954 2.157
B-4 Rev. 1 10/3/2002

B.2.1.3 Volumetric Panel Closure Rate

Using the closure rates from Table B-2, the dimensions of the rooms and drifts in Panel 1 can be 

calculated at the end of each progressive year or for subsequent years using the following 

equations:

Dt = D0 −C5at five years

( ) t Cssb D = D0 −C5 − t − 5 for years six to thirteen

( ) t ssb Cssa D = D0 −C5 −8C − t −13 for years > thirteen

where:

t = Number of years since excavation

Dt = Magnitude of the dimension (height or width) after year t

D0 = Original magnitude of the dimension

C5 = Total convergence in the direction of the dimension after the first five years

Cssb = Steady-state convergence rate of the dimension before Panel 2 mining

Cssa = Steady-state convergence rate of the dimension after Panel 2 mining

The dimension cannot go below zero. The length is assumed to remain constant. The volume is 

then calculated as:

Vt = Ht⋅Wt⋅ L

where:

Vt = Volume of a section after year t

Ht = Height of a section after year t

Wt = Width of a section after year t

L = Length of a section (constant)

The total volume for the panel is calculated by summing the volumes of the individual sections 

as follows:
B-5 Rev. 1 10/3/2002

∑

=

= −

n

i

VPt Vt i Vw

1

( )

where:

VPt = Volume of the entire panel, less the volume of the waste, after year t

n = Number of sections

Vw = Volume of the solids in the waste

The volume versus time for Panel 1 is shown graphically in Figure B-1 and in tabular form in 

Table B-3. The average annual volume loss was found to be 790 cubic meters (27900 ft3) per 

year.

B.2.2 Panel 2 Volume Change Calculation

The calculation of volume change for Panel 2 differs slightly from that of Panel 1, primarily 

because only about two years’ data is available to date from Panel 2. Panel 2 was subdivided 

slightly differently than Panel 1 due to its different instrument layout.

B.2.2.1 Initial Panel 2 Volume

Table B-4 presents the room and drift initial dimensions and the calculated initial volume of each 

room and drift. The total initial volume of Panel 2 is 46,166 m3 (1,630,300 ft3). Subtracting the 

waste volume from the total panel volume gives the total initial void volume (42,258 m3

[1,492,300 ft3]) in the panel.

B.2.2.2 Panel 2 Closure Rates

Using convergence data from Panel 2, the average closure rates of the rooms and drifts are 

determined. Due to the relatively short time since excavation in Panel 2, two rate periods were 

used: 0 to 1 years and beyond 1 year. This assumes that the rate calculated for the second year 

after excavation is the long-term steady-state rate. Because it usually takes about two years to 

reach steady-state, the values used here are likely to overestimate the long-term rates. The 

roof-to-floor and wall-to-wall closure rates for each of the rooms and drifts are presented in 

Table B-5.
B-6 Rev. 1 10/3/2002

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35 40 45 50

Time (years)

Panel Volume (1000xm3)

Figure B-1 Panel 1 Volume versus Time
B-7 Rev. 1 10/3/2002

Table B-3 Panel 1 Volume

Year

Volume

(m3)

Year

(cont’d)

Volume

(m3)

0 43849.77 28 16599.56

5 36744.52 29 15724.08

6 35980.50 30 14857.13

7 35220.91 31 13998.73

8 34465.74 32 13148.86

9 33715.00 33 12307.53

10 32968.69 34 11474.74

11 32226.81 35 10650.49

12 31489.35 36 9834.775

13 30756.33 37 9027.598

14 29752.78 38 8228.958

15 28757.76 39 7438.857

16 27771.29 40 6657.294

17 26793.35 41 5884.269

18 25823.95 42 5166.191

19 24863.09 43 4642.604

20 23910.77 44 4124.191

21 22966.99 45 3610.953

22 22031.74 46 3102.889

23 21105.03 47 2599.999

24 20186.86 48 2102.285

25 19277.23 49 1609.744

26 18376.13 50 1122.378

27 17483.58
B-8 Rev. 1 10/3/2002

Table B-4 Initial Room and Drift Dimensions and Volume of Panel 2

Room or Drift

Initial

Width

(m)

Initial

Height

(m)

Initial

Length

(m)

Initial

Volume

(m3)

Room 1 10.06 3.96 91.44 3643

Room 2 10.06 3.96 91.44 3643

Room 3 10.06 3.96 91.44 3643

Room 4 10.06 3.96 91.44 3643

Room 5 10.06 3.96 91.44 3643

Room 6 10.06 3.96 91.44 3643

Room 7 10.06 3.96 91.44 3643

S2180: Room 1 to west rib Room 2 10.06 3.96 40.54 1615

S2520: Room 1 10.06 3.96 10.06 401

S2180: Room 2 to mid Room 3/4 pillar 10.06 3.96 65.84 2623

S2520: East rib of Room 1 to mid Room 2/3 pillar 10.06 3.96 55.78 2222

S2520: Mid Room 2/3 pillar to mid Room 3/4 pillar 10.06 3.96 40.54 1615

S2180: Mid Room 3/4 pillar to east rib Room 4 10.06 3.96 25.30 1008

S2520: Mid Room 3/4 pillar mid Room 5/6 pillar 10.06 3.96 81.08 3230

S2180: East rib Room 4 to mid Room 5/6 pillar 10.06 3.96 55.78 2222

S2520: Mid Room 5/6 pillar to east rib Room 6 10.06 3.96 25.30 1008

S2180: Mid Room 5/6 pillar to Room 7 10.06 3.96 65.84 2623

S2520: East rib Room 6 to Room 7 10.06 3.96 40.54 1615

S2180: Access to west rib Room 1 4.27 3.66 12.18 190

S2520: Access to west rib Room 1 6.10 3.96 12.18 294

Total Initial Panel Volume 46,166
B-9 Rev. 1 10/3/2002

Table B-5 Panel 2 Room and Drift Closure Rates

Vertical

Closure Rates

Horizontal Closure 

Rates

Room or Drift 0 to 1 

Years 

(cm/yr)

> 1 

Years 

(cm/yr)

0 to 1 

Years 

(cm/yr)

> 1 

Years 

(cm/yr)

Room 1 17.19 9.375 12.14 6.246

Room 2 10.14 9.375 14.85 6.113

Room 3 17.51 8.432 15.39 5.957

Room 4 20.19 8.923 16.74 6.341

Room 5 18.41 7.855 14.98 5.495

Room 6 12.21 7.672 14.08 5.488

Room 7 13.10 8.548 11.33 5.106

S2180: Room 1 to west rib Room 2 19.25 8.723 6.19 6.323

S2520: Room 1 11.66 7.633 15.78 5.562

S2180: Room 2 to mid-Room 3/4 pillar 21.37 9.473 6.19 6.323

S2520: East rib of Room 1 to mid Room 2/3 pillar 25.26 9.458 15.78 5.562

S2520: Mid Room 2/3 pillar to Mid Room 3/4 pillar 22.13 8.806 15.68 5.797

S2180: Mid Room 3/4 pillar to east rib Room 4 24.30 10.756 13.91 6.323

S2520: Mid Room 3/4 pillar mid Room 5/6 pillar 20.44 8.406 15.68 5.797

S2180: East rib Room 4 to mid Room 5/6 pillar 18.10 9.463 13.91 6.323

S2520: Mid Room 5/6 pillar to east rib Room 6 12.75 8.189 10.60 4.666

S2180: Mid Room 5/6 pillar to Room 7 12.08 7.065 12.20 4.832

S2520: East rib Room 6 to Room 7 11.36 6.624 10.60 4.666

S2180: Access to west rib Room 1 6.92 4.266 7.12 4.358

S2520: Access to west rib Room 1 7.39 5.102 11.06 5.804
B-10 Rev. 1 10/3/2002

B.2.2.3 Volumetric Panel Closure Rate

Using the closure rates from Table B-4, the dimensions of the rooms and drifts in Panel 2 can be 

calculated at the end of each progressive year or for subsequent years using the following 

equations:

Dt = D0 −C1after the first year

Dt = D0 −C1 −C2after the second year

( ) t Css D = D0 −C1 −C2 − t − 2 for years > two

where:

t = Number of years since excavation

Dt = Magnitude of the dimension (height or width) after year t

D0 = Original magnitude of the dimension

C1 = Total convergence in the direction of the dimension after the first year

C2 = Total convergence in the direction of the dimension during the second year

Css = Steady-state convergence rate of the dimension

The volume is then calculated as for Panel 1 (Section B.2.1.3). The volume versus time for 

Panel 2 is shown graphically in Figure B-2 and in tabular form in Table B-6. The average annual 

volume loss was found to be 989 m3 (34,930 ft3) per year.

B.2.3 Average Volumetric Panel Closure Rate

In the current analyses, the volume closure rate is taken as the average of the volume closure 

rates of Panels 1 and 2 that is 890 m3 (31,430 ft3) per year. Also, the void volume of Panel 2 

(42,258 m

3

) is taken as typical of all panels.

B.3.0 References

U.S. Department of Energy (DOE), 1996, "Detailed Design Report for an Operational Phase 

Panel Closure System," DOE/WIPP 96-2150, U.S. Department of Energy, WIPP Project Office, 

Carlsbad, New Mexico.
B-11 Rev. 1 10/3/2002

U.S. Department of Energy (DOE), 1993, “Geotechnical Analysis Report, July 1991 through 

June 1992,” DOE-WIPP 93-019, U.S. Department of Energy, Washington D.C.
B-12 Rev. 1 10/3/2002

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35 40 45 50

Time (years)

Panel Volume (1000xm3)

Figure B-2 Panel 2 Volume versus Time
B-13 Rev. 1 10/3/2002

Table B-6 Panel 2 Volume

Year

Volume

(m3)

Year

(cont’d)

Volume

(m3)

0 42,258 21 17,232

1 39,706 22 16,229

2 38,487 23 15,237

3 37,264 24 14,257

4 36,053 25 13,289

5 34,853 26 12,332

6 33,665 27 11,387

7 32,489 28 10,453

8 31,324 29 9,531

9 30,170 30 8,620

10 29,029 31 7,721

11 27,898 32 6,834

12 26,780 33 5,958

13 25,672 34 5,094

14 24,577 35 4,241

15 23,493 36 3,409

16 22,420 37 2,600

17 21,360 38 1,803

18 20,310 39 1,016

19 19,272 40 241

20 18,246
APPENDIX C

FLAC MODELING OF THE WIPP PANEL CLOSURE SYSTEM
C-1 Rev. 1 10/3/2002

APPENDIX C

FLAC MODELING OF THE WIPP PANEL CLOSURE SYSTEM

Numerical modeling is considered here for quantifying the interaction of block wall with the 

surrounding rocksalt. A series of models were developed to evaluate the interaction of the panel 

closure system with the surrounding salt. This appendix discusses the code used and describes 

the material constitutive models used in the stress analysis.

All calculations were performed in accordance with the RockSol Consulting Group, Inc., Quality 

Assurance Program and comply with Westinghouse TRU Solutions requirements. These 

constitute quality records and are maintained in accordance with WIPP procedures. These 

records include verification and validation documents.

C.1.0 FLAC Code

FLAC software has been used for numerical modeling of the underground excavations at the 

Waste Isolation Pilot Plant (WIPP) since 1991. FLAC (Itasca, 2000) is a finite difference code 

that simulates the behavior of rock and soil-like structures. The WIPP Reference Creep Law is 

built into FLAC. The version of FLAC (Version 4.00) used for the panel closure system 

modeling has been verified against the WIPP Second Benchmark Problem (Krieg, 1984).

C.2.0 Material Constitutive Models

The material properties associated with the material constitutive models are given in Tables C-1 

through C-3. These are standard properties used in a wide variety of previous WIPP 

geotechnical FLAC modeling. The halite properties are based on Krieg (1984). The MohrCoulomb model was used for block wall and its properties were calculated using Atkinson et al. 

(1989) and Ahmed and Drysdale (1988) and ACI 530.1-95. The block wall has a minimum 

compressive strength of 5000 psi (34.5 MPa) (Appendix D).

C.3.0 References

Ahmed, H. and R. G. Drysdale, 1988, “Flexural Tensile Strength of Concrete Block Masonry,” 

ASCE Journal of Structural Engineering, pp 50-66.

Atkinson, R. H., B. P. Amadei, S. Saeb, and S. Sture, 1989, “Response to Masonry Bed Joints in 

Direct Shear,” ASCE Journal of Structural Engineering, pp 2276-2296.
C-2 Rev. 1 10/3/2002

Itasca Consulting Group, Inc. (Itasca), 2000, “FLAC User’s Guide,” Itasca Consulting Group, 

Inc., Minneapolis, Minnesota.

Krieg, R. D., 1984, “Reference Stratigraphy and Rock Properties for the Waste Isolation Pilot 

Plant,” SAND83-1908, Sandia National Laboratories, Albuquerque, New Mexico.

Table C-1 Halite Material Properties

Property Value

Bulk modulus (GPa) 20.7

Shear modulus (GPa) 12.4

Density (km/m3) 2,300

Activation energy (cal/mol) 12,000

A 4.56

B 127

D (Pa-n/s) 5.79x10-36

n 4.9

Universal Gas constant (cal/(mol . K)) 1.987

Critical strain rate (1/s) 5.39x10-08

Table C-2 Concrete Material Properties

Property Value

Bulk modulus (GPa) 11.6

Shear modulus (GPa) 9.0

Density (kg/m3) 2,300

Friction angle (degrees) 35

Cohesion (MPa) 9.1

Tension cut-off (MPa) 1.2
C-3 Rev. 1 10/3/2002

Table C-3 Clay Seam, Rock/Concrete Contact, and 

Construction Joint Material Properties

Property Value

Normal stiffness (Pa/m) 1.0x1012

Shear stiffness (Pa/m) 5.0x1010

Cohesion (Pa) 0.0

Friction (degrees) 30
APPENDIX D

TECHNICAL SPECIFICATIONS
01010-1 Rev. 1 10/3/2002

SECTION 01010 

SUMMARY OF WORK

PART 1 - GENERAL

1.1 Scope

This section includes:

• Scope of Work

• Definitions and Abbreviations

• List of Drawings

• Work by Others

• Contractor’s Use of Site

• Contractor’s Use of Facilities

• Work Sequence

• Work Plan

• Health and Safety Plan (HASP)

• Contractor Quality Control Plan (CQCP)

• Submittals

1.2 Scope of Work

The Contractor shall furnish all labor, materials, equipment and tools to construct two (2) panel 

closure systems. The closure system consists of an explosion isolation wall and run of mine salt 

backfill, one of each to be installed in the air-intake drift and the air-exhaust drift of a waste 

disposal panel, as shown on the Drawings and described in these Specifications. Unless 

otherwise agreed by Westinghouse, the Contractor shall use Westinghouse supplied equipment 

underground. Such use shall be coordinated with Westinghouse and may include the use of 

Westinghouse qualified operators.

The scope of work shall include but not necessarily be limited to the following units of work:

• Develop work plan, health and safety plan (HASP) and contractors quality control plan 

(CQCP)

• Prepare and submit all plans requiring approval

• Mobilize to site

• Coordinate construction with WIPP operations
01010-2 Rev. 1 10/3/2002

• Perform the following for the air-intake entry and the air-exhaust entry:

- Prepare the surfaces for the explosion isolation wall

- Construct the explosion isolation wall

- Place run of mine salt material

• Clean up construction areas in underground and above ground

• Submit all required record documents

• Demobilize from site

1.3 Definitions and Abbreviations

Definitions

Concrete masonry units—Concrete blocks used for construction of the explosion isolation wall.

Creep—Viscoplastic deformation of salt under deviatoric stress.

Explosion isolation wall—A mortared concrete block wall adjacent to the panel waste disposal 

area that can sustain the pressure and temperature transients of a methane explosion.

Methane explosion—A postulated deflagration caused by methane gas at an explosive level.

Partial closure—The process of rendering a part of the hazardous waste management unit in the 

underground repository inactive and closed according to approved facility closure plans. 

Volatile Organic Compound (VOC) —Any VOC with Hazardous Waste Facility Permit 

emission limits.

Westinghouse—Westinghouse TRU Solutions, LLC as the construction management authority. 
01010-3 Rev. 1 10/3/2002

Abbreviations/Acronyms

ACI American Concrete Institute

ANSI American National Standards Institute

ASTM American Society for Testing and Materials

CFR Code of Federal Regulations

CQCP Contractor Quality Control Plan

DOE U.S. Department of Energy

DWG Drawing

EPA U.S. Environmental Protection Agency

HASP Health And Safety Plan

JHA Job Hazard Analysis

LHD Load Haul Dump

LLC Limited Liability Corporation

MSHA U.S. Mine Safety and Health Administration

RCRA Resource Conservation and Recovery Act

USACE U.S. Army Corps of Engineers

VOC Volatile Organic Compound

WIPP Waste Isolation Pilot Plant

1.4 List of Drawings

The following Drawings are made apart of this Specification:

DWG 110-CD001 Panel closure system, title sheet

DWG 110-CD002 Panel closure system, underground waste disposal panel configuration

DWG 110-CD003 Panel closure system, construction details
01010-4 Rev. 1 10/3/2002

1.5 Work by Others

Survey

All survey work to locate, control, confirm, and complete the work will be performed by 

Westinghouse. All survey work for record purposes will be performed by Westinghouse. The 

Contractor shall be responsible for developing the concrete block wall to fit the excavation.

Other

Westinghouse may elect to perform certain portions, or all, of the work. The work performed by 

the Westinghouse will be defined prior to the contract. Unless otherwise agreed by 

Westinghouse, the Contractor shall use underground equipment furnished by Westinghouse for 

construction of the explosion isolation walls and placement of the run of mine salt. Underground 

mining personnel who are qualified for the operation of such underground construction 

equipment may be made available to the Contractor. The use of Westinghouse equipment shall 

be coordinated with Westinghouse. 

1.6 Contractor's Use of Site

Site Conditions

The site is located near Carlsbad, New Mexico, as shown on the Drawings. The underground 

arrangements and location of the WIPP waste disposal panels are shown on the Drawings. The 

work is to construct the explosion isolation walls and place run of mine salt in the air-intake and 

air-exhaust drifts of one of the panels upon completion of the disposal phase of that panel. The 

waste disposal panels are located approximately 2,150 ft (655 m) below the ground surface. The 

Contractor shall visit the site and become familiar with the site and site conditions prior to 

preparing his bid proposal.

Contractor's Use of Site

Areas at the ground surface will be designated for the Contractor's use in assembling and storing 

his equipment and materials. The Contractor shall utilize only those areas designated.

Limited space within the underground area will be designated for the Contractor's use for storage 

of material and setup of equipment.
01010-5 Rev. 1 10/3/2002

Coordination of Contractor's Work

The Contractor is advised that on-going waste emplacement and excavation operations will be 

conducted throughout the period of construction of the panel closure system. These operations 

have priority over the Contractor's work. The Contractor shall coordinate his construction 

operations with that of the waste emplacement and mining operations. All coordination shall be 

through Westinghouse.

1.7 Contractor's Use of Facilities

Existing facilities at the site available for use by the Contractor are:

• Waste shaft conveyance

• Salt skip hoist

• 460 volt AC, 3 phase power

• Water (underground, at waste shaft only) (above ground, at location designated by 

Westinghouse)

Additional information on these facilities is presented in Section 02010.

1.8 Work Sequence

Work Sequence shall be as shown on the Drawings and as directed by Westinghouse.

1.9 Work Plan

The Contractor shall prepare a Work Plan fully describing his proposed construction operation. 

The work plan shall define all proposed equipment and methods. Westinghouse shall approve 

the Work Plan and no work shall be performed prior to approval of the Work Plan.

1.10 Health and Safety Plan (HASP)

The Contractor shall obtain, review, and agree to applicable portions of the existing WIPP Safety 

Manual, WP 12-1. The Contractor shall prepare a project-specific HASP taking into account all 

applicable sections of the WIPP Safety Manual. All personnel shall be qualified to work 

underground. All personnel operating heavy construction equipment shall be qualified to operate 

such equipment. The Contractor shall also perform a Job Hazard Analysis (JHA) in accordance 

with WP 12-111. Westinghouse shall approve the HASP and JHA and no work shall be 

performed prior to approval of the HASP and JHA. 
01010-6 Rev. 1 10/3/2002

1.11 Contractor Quality Control Plan (CQCP)

The Contractor shall prepare a CQCP identifying all personnel and procedures necessary to 

produce an end product, which complies with the contract requirements. The CQCP shall 

comply with all Westinghouse requirements, including operator training and qualification; and 

Section 01400, Contractor Quality Control, of this Specification. Westinghouse shall approve 

the CQCP and no work shall be performed prior to approval of the CQCP.

1.12 Submittals

Submittals shall be in accordance with Westinghouse Submittal Procedures and as required by 

the individual Specifications.

PART 2 - PRODUCTS

Not used

PART 3 - EXECUTION

Not used

End of section
01090-1 Rev. 1 10/3/2002

SECTION 01090

REFERENCE STANDARDS

PART 1 - GENERAL

1.1 Scope

This section includes:

• Provision of Reference Standards at Site

• Acronyms used in Contract Documents for Reference Standards

1.2 Quality Assurance

For products or workmanship specified by association, trade, or Federal Standards, the 

Contractor shall comply with requirements of the standard, except when more rigid requirements 

are specified or are required by applicable codes. 

Conform to reference by date of issue current on the date of the owner-contractor agreement.

The Contractor shall obtain, at his own expense, a copy of the standards referenced in the 

individual Specification sections and shall maintain that copy at the jobsite until completion and 

acceptance of the work. 

Should specified Reference Standards conflict with the contract documents, the Contractor shall 

request clarification from Westinghouse before proceeding.

1.3 Schedule of References

Various publications referenced in other sections of the Specifications establish requirements for 

the work. These references are identified by document number and title. The addresses of the 

organizations responsible for these publications are listed below.

ACI ACI International 

P.O. Box 9094

Farmington Hills, MI 48333

Ph: 248-848-3700
01090-2 Rev. 1 10/3/2002

ANSI American National Standards Institute

25 West 43rd St.

New York NY 10036 

Ph: 212-642-4900

Fax: 212-398-0023

ASTM ASTM International

100 Barr Harbor Drive 

P.O. Box C700, West Conshohocken,

Pennsylvania, USA 19428-2959 

Ph: 610-832-9585 

Fax: 610-832-9555

CFR Code of Federal Regulations

Government Printing Office 

P.O. Box 371954, Pittsburgh, PA 15250-7954

Ph: 202-512-1800

Fax: 202-512-2250

EPA Environmental Protection Agency 

Public Information Center 

401 M St., SW 

Washington, DC 20460 

Ph: 202-260-2080

Fax: 202-260-6257

FTM-STD Federal Test Method Standards

Standardization Documents Order Desk

Bldg. 4D

700 Robbins Ave.

Philadelphia, PA 19111-5094

Ph: 215-697-2179

Fax: 215-697-2978
01090-3 Rev. 1 10/3/2002

NIST National Institute of Standards and Technology

100 Bureau Drive, Stop 3460

Gaithersburg, MD 20899-3460

Ph: 301-975-6478

Fax: 301-975-8295

NRMCA National Ready-Mixed Concrete Association

900 Spring St

Silver Spring, MD 20910

Ph: 301-587-1400

Fax: 301-585-4219

NTIS National Technical Information Service 

U.S. Department of Commerce 

Springfield, VA 22161 

Ph: 703- 605-6000

Fax: 703-321-8547

PCA Portland Cement Association 

5420 Old Orchard Road 

Skokie, IL 60077

Ph: 847-966-6200

Fax: 847-966-8389

End of section
01400-1 Rev. 1 10/3/2002

SECTION 01400 

CONTRACTOR QUALITY CONTROL

PART 1 - GENERAL

1.1 Scope

This section includes:

• Contractor Quality Control Plan (CQCP)

• Reference Standards

• Quality Assurance

• Tolerances

• Testing Services

• Inspection Services

• Submittals

1.2 Related Sections

• 01090 - Reference Standards

• 01600 - Material and Equipment

• 02222 - Excavation

• 03100 - Mortar

• 03300 - Unit Masonry System

• 03400 - Masonry Explosion Isolation Structure

• 04100 - Salt Backfill

1.3 Contractor Quality Control Plan (CQCP)

The Contractor shall prepare a Contractor Quality Control Plan (CQCP), as described in Part 3. 

No work shall be performed prior to Westinghouse approval of the CQCP. 

1.4 Reference Standards

Refer to individual Specification sections for standards referenced therein, and to Section 01090, 

Reference Standards, for general listing.

Standards referenced in this section are as follows:

ASTM C 1077-02 Standard Practice for Laboratories Testing Concrete and Concrete 

Aggregates for Use in Construction and Criteria for Laboratory Evaluation
01400-2 Rev. 1 10/3/2002

ASTM C 1093-95 Standard Practice for Accreditation of Testing Agencies for Unit Masonry

ASTM E 329-01a Standard Specification for Agencies Engaged in the Testing and/or 

Inspection of Materials Used in Construction

ASTM E 543-02 Standard Practice for Agencies Performing Nondestructive Testing

ASTM E 548-94 Standard Guide for General Criteria Used for Evaluating Laboratory 

Competence

1.5 Quality Assurance

The Contractor shall:

• Monitor suppliers, manufacturers, products, services, site conditions, and workmanship to 

produce work of specified quality

• Comply with specified standards as minimum quality for the work except where more 

stringent tolerances, codes, or specified requirements indicate higher standards or more 

precise workmanship

• Perform work with qualified persons to produce required and specified quality

1.6 Tolerances

The Contractor shall:

• Monitor excavation, fabrication, and tolerances in order to produce acceptable work. The 

Contractor shall not permit tolerances to accumulate.

1.7 Testing Services

Unless otherwise agreed by Westinghouse, the Contractor shall employ an independent firm 

qualified to perform the testing services and other services specified in the individual 

Specification sections, and as may otherwise be required by Westinghouse. Testing and source 

quality control may occur on or off the project site.

The testing laboratory shall comply with applicable sections of the Reference Standards and shall 

be authorized to operate in the State of New Mexico.

Testing equipment shall be calibrated at reasonable intervals traceable to either the National 

Institute of Standards and Technology or accepted values of natural physical constants.
01400-3 Rev. 1 10/3/2002

1.8 Inspection Services

The Contractor may employ an independent firm to perform inspection services as a supplement 

to the Contractor's quality control as specified in the individual Specification sections, and as 

may be required by Westinghouse. Inspection may occur on or off the project site.

The inspection firm shall comply with applicable sections of the Reference Standards.

1.9 Submittals

The Contractor shall submit a CQCP as described herein.

Prior to start of work, the Contractor shall submit for approval, the testing laboratory name, 

address, telephone number and name of responsible officer of the firm as well as a copy of the 

testing laboratory compliance with the reference ASTM standards and a copy of report of 

laboratory facilities inspection made by Materials Reference Laboratory of National Institute of 

Standards and Technology with memorandum of remedies of any deficiencies reported by the 

inspection.

The Contractor shall submit the names and qualifications of personnel proposed to perform the 

required inspections, along with their individual qualifications and certifications. Once approved 

by Westinghouse these personnel shall be available as may be required to promptly and 

efficiently complete the work.

PART 2 - PRODUCTS

Not used

PART 3 - EXECUTION

3.1 General

The Contractor is responsible for quality control and shall establish and maintain an effective 

quality control system. The quality control system shall consist of plans, procedures, and 

organization necessary to produce an end product which complies with the contract 

requirements. The system shall cover all construction operations, both on site and off site, and 

shall be keyed to the proposed construction sequence. The project superintendent will be held 

responsible for the quality of work on the job. The project superintendent in this context is the 

individual with the responsibility for the overall management of the project including quality and 

production.
01400-4 Rev. 1 10/3/2002

3.2 Contractor Quality Control Plan

3.2.1 General

The Contractor shall supply, not later than 30 days after receipt of notice to proceed, the 

Contractor Quality Control Plan (CQCP) which implements the requirements of the Contract. 

The CQCP shall identify personnel, procedures, control, instructions, tests, records, and forms to 

be used. Construction shall not begin until the CQCP is approved by Westinghouse.

3.2.2 Content of the CQCP

The CQCP shall cover all construction operations, both on site and off site, including work by 

subcontractors, fabricators, suppliers, and purchasing agents and shall include, as a minimum, 

the following items:

• A description of the quality control organization, including a chart showing lines of 

authority and acknowledgment that the Contractor Quality Control (CQC) staff shall 

implement the control system for all aspects of the work specified.

• The name, qualifications (in resume format), duties, responsibilities, and authorities of 

each person assigned a CQC function.

• A description of CQCP responsibilities and a delegation of authority to adequately 

perform the functions described in the CQCP, including authority to stop work.

• Procedures for scheduling, reviewing, certifying, and managing submittals, including

those of subcontractors, off site fabricators, suppliers, and purchasing agents. These 

procedures shall be in accordance with Westinghouse Submittal Procedures.

• Control, verification, and acceptance testing procedures as may be necessary to ensure that 

the work is completed to the requirements of the Drawings and Specifications.

• Procedures for tracking deficiencies from identification, through acceptable corrective 

action, to verification that identified deficiencies have been corrected.

• Reporting procedures, including proposed reporting formulas.

3.2.3 Acceptance of Plan

Acceptance of the Contractor's plan is conditional. Westinghouse reserves the right to require 

the Contractor to make changes in his CQCP and operations, including removal of personnel, if 

necessary, to obtain the quality specified.

3.2.4 Notification of Changes

After acceptance of the CQCP, the Contractor shall notify Westinghouse in writing of any 

proposed change. Proposed changes are subject to acceptance by Westinghouse.
01400-5 Rev. 1 10/3/2002

3.3. Tests

3.3.1 Testing Procedure

The Contractor shall perform specified or required tests to verify that control measures are 

adequate to complete the work to contract requirements. Upon request, the Contractor shall 

furnish, at his own expense, duplicate samples of test specimens for testing by Westinghouse. 

The Contractor shall perform, as necessary, the following activities and permanently record the 

results:

• Verify that testing procedures comply with contract requirements.

• Verify that facilities and testing equipment are available and comply with testing 

standards.

• Check test instrument calibration data against certified standards.

• Verify that recording forms and test identification control number system, including all of 

the test documentation requirements, have been prepared.

• Record the results of all tests taken, both passing and failing. Specification paragraph 

reference, location where tests were taken, and the sequential control number identifying 

the test will be given. If approved by Westinghouse, actual test reports may be submitted 

later with a reference to the test number and date taken. An information copy of tests 

performed by an off site or commercial test facility will be provided directly to 

Westinghouse.

3.4 Testing Laboratory

The testing laboratory shall provide qualified personnel to perform specified sampling and 

testing of products in accordance with specified standards, and the requirements of Contract 

Documents.

Reports indicating results of tests, and compliance or noncompliance with the contract 

documents will be submitted in accordance with Westinghouse submittal procedures. Testing by 

an independent firm does not relieve the Contractor of the responsibility to perform the work to 

the contract requirements.

3.5 Inspection Services

The inspection firm shall provide qualified personnel to perform specified inspection of products 

in accordance with specified standards. 
01400-6 Rev. 1 10/3/2002

Reports indicating results of the inspection and compliance or noncompliance with the contract 

documents will be submitted in accordance with Westinghouse submittal procedures.

Inspection by the independent firm does not relieve the Contractor of the responsibility to 

perform the work to the contract requirements.

3.6 Completion Inspection

3.6.1 Pre-Final Inspection

At appropriate times and at the completion of all work, the Contractor shall conduct an 

inspection of the work and develop a punch list of items which do not conform to the Drawings 

and Specifications. The Contractor shall then notify Westinghouse that the work is ready for 

inspection. Westinghouse will perform this inspection to verify that the work is satisfactory and 

appropriately complete. A final punch list will be developed as a result of this inspection. The 

Contractor shall ensure that all items on this list are corrected and notify Westinghouse so that a 

final inspection can be scheduled. Any items noted on the final inspection shall be corrected in a 

timely manner. These inspections and any deficiency corrections required by this paragraph will 

be accomplished within the time slated for completion of the entire work. 

3.6.2 Final Acceptance Inspection

The final acceptance inspection will be formally scheduled by Westinghouse based upon notice

from the Contractor. This notice will be given to Westinghouse at least 14 days prior to the final 

acceptance inspection. The Contractor shall assure that all specific items previously identified as 

unacceptable, along with all remaining work performed under the contract, will be complete and 

acceptable by the date scheduled for the final acceptance inspection.

3.7 Documentation

The Contractor shall maintain current records providing factual evidence that required quality 

control activities and/or tests have been performed. These records shall include the work of 

subcontractors and suppliers and shall be on an acceptable form approved by Westinghouse.

3.8 Notification of Noncompliance

Westinghouse will notify the Contractor of any noncompliance with the foregoing requirements. 

The Contractor shall take immediate corrective action after receipt of such notice. Such notice, 

when delivered to the Contractor at the worksite, shall be deemed sufficient for the purpose of 

notification. If the Contractor fails or refuses to comply promptly, Westinghouse may issue an 

order stopping all or part of the work until satisfactory corrective action has been taken. No part 
01400-7 Rev. 1 10/3/2002

of the time lost due to such stop orders shall be made the subject of claim for extension of time 

or for excess costs or damages by the Contractor.

End of section
01600-1 Rev. 1 10/3/2002

SECTION 01600

MATERIAL AND EQUIPMENT

PART 1 - GENERAL

1.1 Scope

This section includes:

• Equipment

• Products

• Transportation and Handling

• Storage and Protection

• Substitutions

1.2 Related Sections

• 01010 - Summary of Work

• 01400 - Contractor Quality Control

• 02010 - Mobilization and Demobilization

• 02222 - Excavation

• 03100 - Mortar

• 03300 - Unit Masonry System

• 03400 - Masonry Explosion Isolation Structure

• 04100 - Salt Backfill

1.3 Equipment

The Contractor shall specify his proposed equipment in the Work Plan. Power equipment for use 

underground shall be either electrical or diesel engine driven. All diesel engine equipment shall 

be certified for use underground at the WIPP site. 

1.4 Products

The Contractor shall specify in the Work Plan, or in subsequently required submittals, the 

proposed products including, but not limited to, the mortar mix and its components, masonry 

blocks, and run of mine salt. The proposed products shall be supported by laboratory test results 

as required by the Specifications. All products shall be subject to approval by Westinghouse.
01600-2 Rev. 1 10/3/2002

1.5 Transportation and Handling

The Contractor shall:

• Transport and handle products in accordance with manufacturer's instructions.

• Promptly inspect shipments to ensure that products comply with requirements, quantities 

are correct, and products are undamaged.

• Provide equipment and personnel to handle products by methods to prevent soiling, 

disfigurement, or damage.

1.6 Storage and Protection

The Contractor shall:

• Store and protect products in accordance with manufacturers' instructions.

• Store with seals and labels intact and legible.

• Store sensitive products in weather tight, climate controlled, enclosures in an environment 

favorable to product.

• Provide ventilation to prevent condensation and degradation of products.

• Store loose granular materials on solid flat surfaces in a well-drained area and prevent 

mixing with foreign matter.

• Provide equipment and personnel to store products by methods to prevent soiling, 

disfigurement, or damage.

• Arrange storage of products to permit access for inspection and periodically inspect to 

verify products are undamaged and are maintained in acceptable condition.

1.7 Substitutions

1.7.1 Equipment Substitutions

The Contractor may substitute equipment for that proposed in the Work Plan subject to 

Westinghouse approval. 

1.7.2 Product Substitutions

The Contractor may not substitute products after the proposed products have been approved by 

Westinghouse unless he can demonstrate that the supplier/source of that product no longer exists 

in which case he shall submit alternate products with lab test results to Westinghouse for 

approval. In the case that product is a component in a mix, the Contractor shall perform mix 

testing using that component and submit laboratory test results.
01600-3 Rev. 1 10/3/2002

PART 2 – PRODUCTS

Not used

PART 3 - EXECUTION

Not used

End of section
02010-1 Rev. 1 10/3/2002

SECTION 02010

MOBILIZATION AND DEMOBILIZATION

PART 1 - GENERAL

1.1 Scope

This section includes:

• Mobilization of Equipment and Facilities to Site

• Contractor Use of Site

• Use of Existing Facilities

• Demobilization of Equipment and Facilities

• Site Cleanup

1.2 Related Sections

• 01010 - Summary of Work

• 01600 - Material and Equipment

PART 2 - PRODUCTS

Not used

PART 3 - EXECUTION

3.1 Mobilization of Equipment and Facilities to Site

Upon authorization to proceed, the Contractor shall mobilize his equipment and facilities to the 

jobsite. Equipment and facilities shall be as specified and as defined in the Contractor's Work 

Plan.

Westinghouse will provide utilities at designated locations. The Contractor shall be responsible 

for all hookups and tie-ins required for his operations.

The Contractor shall be responsible for providing his own office, storage, and sanitary facilities.

Areas will be designated for the Contractor's use in the underground area in the vicinity of the 

panel closure system installation. These areas are limited.
02010-2 Rev. 1 10/3/2002

3.2 Contractor Use of Site

The Contractor shall use only those areas specifically designated for his use by Westinghouse. 

The Contractor shall limit his on-site travel to the specific routes required for performance of his 

work, and designated by Westinghouse.

3.3 Use of Existing Facilities

Existing facilities available for use by the Contractor are:

• Waste shaft conveyance

• Salt skip hoist

• 460 Volt AC, 3 phase power

• Water underground at waste shaft only 

• Water on surface at location designated by Westinghouse

The Contractor shall arrange for use of the facilities with Westinghouse and coordinate his 

actions and requirements with ongoing Westinghouse operations.

Use of water in the underground will be restricted. No washout or cleanup will be permitted in 

the underground except as designated by Westinghouse. Above ground washout or cleanup of 

equipment will be allowed in the areas designated by Westinghouse.

The Contractor is cautioned to be aware of the physical dimensions of the waste conveyance and 

the air lock.

The Contractor shall be responsible for any damage incurred by the existing site facilities as a 

result of his operations. Any damage shall be reported immediately to Westinghouse and 

repaired at the Contractor's cost.

3.4 Demobilization of Equipment and Facilities

At completion of this work, the Contractor shall demobilize his equipment and facilities from the 

job site. All Contractor's equipment and materials shall be removed and all disturbed areas 

restored. Utilities shall be removed to their connection points unless otherwise directed by 

Westinghouse.

3.5 Site Cleanup

At conclusion of the work, the Contractor shall remove all trash, waste, debris, excess

construction materials, and restore the affected areas to their prior condition, to the satisfaction of 
02010-3 Rev. 1 10/3/2002

Westinghouse. A final inspection will be conducted by Westinghouse and the Contractor before 

final payment is approved.

End of section
02222-1 Rev. 1 10/3/2002

SECTION 02222

EXCAVATION

PART 1 - GENERAL

1.1 Scope

This section includes:

• Excavation for surface preparation and leveling of surrounding areas for explosion 

isolation wall

• Disposition of excavated materials

• Field measurement and survey

1.2 Related Sections

• 01010 - Summary of Work

• 01600 - Material and Equipment

• 03400 - Masonry Explosion Isolation Structure

1.3 Reference Documents

Krieg, R. D., 1984, “Reference Stratigraphy and Rock Properties for the Waste Isolation Pilot 

Plant,” SAND83-1908, Sandia National Laboratories, Albuquerque, New Mexico.

1.4 Field Measurements and Survey

All survey required for performance of the work will be provided by Westinghouse. 

PART 2 - PRODUCTS

Not used

PART 3 - EXECUTION

3.1 Excavation for Surface Preparation and Leveling of Surrounding Areas for Explosion 

Isolation Wall

The Contractor shall excavate and prepare the surface around the entire perimeter of the 

explosion isolation walls by removing all loose material, generally squaring the excavation 

cross-section, and cleaning all rock surfaces. The surface preparation of the floor shall produce a 

surface suitable for placing the first course of block in the explosion isolation walls. Excavation 

may be performed by either mechanical or manual means. Use of explosives is prohibited. 
02222-2 Rev. 1 10/3/2002

3.2 Disposition of Excavated Materials

The Contractor shall dispose of all excavated materials as directed by Westinghouse.

3.3 Field Measurements and Survey

All survey required for performance of the work will be provided by Westinghouse. The 

Contractor shall protect all survey control points, benchmarks, etc., from damage by his 

operations. Westinghouse will verify that the Contractor has excavated to the required lines and 

grades. No block work is to be erected until approved by Westinghouse.

End of section
03100-1 Rev. 1 10/3/2002

SECTION 03100

MORTAR

PART 1 - GENERAL

1.1 Scope

This section includes:

• Mortar for Explosion Isolation Wall.

1.2 Related Sections

• 01010 - Summary of Work

• 01400 - Contractor Quality Control

• 01600 - Material and Equipment

• 03300 - Unit Masonry System

• 03400 - Masonry Explosion Isolation Structure

1.3 References

ASTM C 91-01 Standard Specification for Masonry Cement

ASTM C 144-02 Standard Specification for Aggregate for Masonry Mortar

ASTM C 150-02 Standard Specification for Portland Cement

ASTM C 207-91 Standard Specification for Hydrated Lime for Masonry Purposes

ASTM C 270-01a Standard Specification for Mortar for Unit Masonry

ASTM C 780-02 Standard Test Method for Preconstruction and Construction Evaluation of 

Mortars for Plain and Reinforced Unit Masonry

ASTM C 1142-95 Standard Specification for Extended Life Mortar for Unit Masonry

ASTM C 94-00 Standard Specification for Ready-Mixed Concrete

1.4 Submittals for Review and Approval

The Contractor shall submit the followings 30 days prior to the initiation of work at the site:

• Design mix.

• Certified laboratory tests for the proposed design mix, indicating conformance of mortar 

to property requirements of ASTM C 270, and test and evaluation reports to ASTM C 780.
03100-2 Rev. 1 10/3/2002

The mix shall not be used until approved by Westinghouse.

1.5 Submittals at Completion

The Contractor shall submit certified laboratory test results for the construction testing of mortar 

mix.

1.6 Quality Assurance

The Contractor shall:

• Perform work in accordance with the Contractor's Quality Control Plan and referenced 

ASTM standards.

• Acquire cement, aggregate, and component materials from the same source throughout the 

work.

1.7 Delivery Storage Handling

The Contractor shall maintain packaged materials clean, dry and protected against dampness, 

freezing and foreign matter.

PART 2 - PRODUCTS

2.1 Mortar Mix

The Contractor shall provide mortar for explosion isolation walls, which shall conform with 

ASTM C 270 type M, using the property specification 3,000 psi at 28 days as the minimum 

requirement. The Contractor shall provide the mortar design mix to achieve the minimum 

compressive strength requirement for masonry structure as specified in Section 03400. 

Aggregate for mortar shall conform to ASTM C 144. 

2.2 Water

Water used in mixing concrete shall be of potable quality, free of injurious amounts of oil, acid, 

alkali, organic matter, or other deleterious substances. Water shall conform to the provisions in 

ASTM C 94, and in addition, shall conform to the following:

• PH not less than 6.0 or greater than 8.0

• Carbonates and/or bicarbonates of sodium and potassium: 1000 ppm maximum

• Chloride ions (Cl): 250 ppm maximum

• Sulfate ions (SO4): 1000 ppm maximum

• Iron content: 0.3 ppm maximum

• Total solids: 2000 ppm maximum
03100-3 Rev. 1 10/3/2002

The source of water is to be indicated and certified copies of test data from an approved 

laboratory confirming that the water to be used meets the above requirements shall be submitted 

for approval with the trial mix data.

The supply of materials as defined in the design mix shall remain the same throughout the job.

PART 3 - EXECUTION

3.1 General

The Contractor shall furnish all labor, materials, equipment, and tools to perform all operations

in connection with supplying and mixing mortar for constructing the explosion isolation walls.

The Contractor shall fully describe his proposed mortar mixing operation, including proposed

equipment and materials in the Work Plan.

3.2 Mortar Mixing

Mortar shall be machine-mixed with sufficient water for a period of time not less than three 

minutes or more than ten minutes to achieve satisfactory workability. Maintain sand uniformly 

damp immediately before the mixing process. If water is lost by evaporation, retemper only 

within one and one half hours of mixing. Use mortar within two hours of mixing. Mortar which 

has hardened or stiffened due to hydration of the cement shall not be used. 

3.3 Installation

The Contractor shall install mortar to the requirements of Section 03300 Unit Masonry System.

3.4 Field Quality Control

The Contractor shall provide a Quality Control Inspector to perform all sampling and testing to 

confirm that the mortar mix conforms to the proposed mix properties developed in the design 

mix.

Construction testing of mortar mix shall be in accordance with ASTM C 780 for compression 

strength. Four prism specimens shall be taken for each 50 ft3 of mortar or fraction thereof placed 

each day.

End of section
03300-1 Rev. 1 10/3/2002

SECTION 03300

UNIT MASONRY SYSTEM

PART 1 – GENERAL

1.1 Scope

This section includes:

• Concrete Masonry Units

1.2 Related Sections

• 01010 Summary of Work

• 01400 Contractor Quality Control

• 01600 Material and Equipment

• 03100 Mortar

• 03400 Masonry Explosion Isolation Structure

1.3 References

ASTM C 55-01a Standard Specification for Concrete Brick

ASTM C 140-02 Standard Test Methods for Sampling and Testing Concrete Masonry Units 

and Related Units

1.4 Submittals for Revision and Approval

The Contractor shall submit for approval the following 30 days prior to initiation of the work at 

the site.

• Certified laboratory test results for the proposed solid masonry units.

1.5 Quality Assurance

The Contractor shall perform the work in accordance with the CQCP.

PART 2 - PRODUCTS

2.1 Concrete Masonry Units

Concrete masonry units shall be solid (no cavities or cores), load-bearing, high-strength 

individual units having a minimum compressive strength of 5000 psi. Concrete masonry units 

shall be tested in accordance with ASTM C 140. All other aspects of the concrete masonry units 

shall comply with ASTM C 55, Type I Moisture Controlled.
03300-2 Rev. 1 10/3/2002

Nominal modular size shall be 8x8x16 inches, or as otherwise approved by Westinghouse.

Concrete brick shall comply with ASTM C 55, Grade N, Type I (moisture controlled) but having 

a minimum compressive strength of 5500 psi (Avg. 3 units) or 5000 psi for individual unit.

2.2 Mortar

Mortar shall be as specified in Section 03100 Mortar.

PART 3 - EXECUTION

Not used

End of section
03400-1 Rev. 1 10/3/2002

SECTION 03400

MASONRY EXPLOSION ISOLATION STRUCTURE

PART 1 - GENERAL

1.1 Scope

This section includes:

• Masonry Explosion Isolation Structure

1.2 Related Sections

• 01010 Summary of Work

• 01400 Contractor Quality Control

• 01600 Material and Equipment

• 03100 Mortar

• 03300 Unit Masonry Structure

1.3 References

ASTM C 1314-02a Standard Test Method for Compressive Strength of Masonry Prism

ACI 530.1-02 Specification for Masonry Structures

1.4 Submittals for Revision and Approval

The Contractor shall submit for approval the following 30 days prior to initiation of the work at 

the site.

• Certified laboratory test results for compressive strength of masonry by the prism method 

for a set of five masonry prisms. Materials used for the construction of the prisms shall be 

taken from those to be used in the construction of the explosion isolation wall. The 

minimum compressive strengths of the tests shall exceed f’m as required in 1.6.

1.5 Quality Assurance

The Contractor shall perform the work in accordance with the CQCP.
03400-2 Rev. 1 10/3/2002

1.6 Compressive Strength of Masonry

Compressive strength of masonry in each masonry wythe shall exceed 5000 psi (f’m=5000 psi). 

The unconfined compressive strength shall be determined by prism test method in accordance 

with ASTM C 1314 and ACI 530.1. 

PART 2 - PRODUCTS

2.1 Concrete Masonry Units

Concrete masonry units shall be as specified in Section 03300 Unit Masonry System. Concrete 

masonry units shall not be wetted unless otherwise approved by Westinghouse. 

2.2 Mortar

Mortar shall be as specified in Section 03100 Mortar.

PART 3 - EXECUTION

3.1 General

The Contractor shall furnish all labor, material, equipment and tools to perform all operations of 

installing Unit Masonry Explosion Isolation Walls as shown on the Drawings.

The Contractor shall request that Westinghouse inspect and approve all surfaces before 

beginning any masonry work.

3.2 Installation

The Contractor shall install the explosion isolation walls using concrete masonry units as 

specified above. Masonry units shall be installed with 3/8-inch mortar joints with full mortar 

bedding and full head joints. The mortar shall be sufficiently plastic and units shall be placed 

with sufficient pressure to extrude mortar from the joint and produce a tight joint. Deep 

furrowing which produces voids shall not be used. The initial bed joint thickness shall not be 

less than 1/4 inch or more than 1 inch, subsequent bed joints shall be not less than 1/4 inch or 

more than 5/8 inch in thickness. 

Masonry units shall be installed in running bond with headers every third course. Masonry units 

shall be mortared tight to the ribs and the back wall to provide a seal all around the explosion 

isolation wall. All surfaces shall be clean and free of deleterious materials.

Cut concrete blocks may be used as required to minimize the dimensional fit-up at the top or 

sides of the isolation walls. All interfaces between the explosion isolation wall and the rock 
03400-3 Rev. 1 10/3/2002

surfaces shall be completely mortared to provide full contact between the rock surfaces and the 

block wall.

Construction joints shall be left as shown on the Drawings. Construction joints shall be left open 

and unfilled.

3.3 Field Quality Control

The Contractor shall provide a Quality Control Inspector to inspect the installation of the Unit 

Masonry Explosion Isolation Walls. Inspection and testing of the mortar shall be in accordance 

with Section 03100 Mortar. Inspection and testing of masonry units are in accordance with 

Section 03300. A prism test in accordance with Part 1.6 of Section 03400 shall be performed for 

each 2000 ft3 of block wall. 

End of section
04100-1 Rev. 1 10/3/2002

SECTION 04100

SALT BACKFILL

PART 1 - GENERAL

1.1 Scope

This section includes:

• Salt Backfill Placement

1.2 Related Sections

• 01010 Summary of Work

• 01400 Contractor Quality Control

• 01600 Material and Equipment

1.3 Submittals for Revision and Approval

The backfill emplacement method, dust control plan and other safety related material shall be 

approved by Westinghouse.

1.4 Quality Assurance

The Contractor shall perform the work in accordance with the CQCP.

PART 2 - PRODUCTS

2.1 Salt Backfill Material

The salt backfill is run of mine salt and requires no grading or compaction. The salt backfill shall 

be free of organic material.

PART 3 - EXECUTION

3.1 General

The Contractor shall furnish all labor, material, equipment and tools to handle and place the salt 

backfill. 

The Contractor shall use underground equipment and underground mine personnel as required in 

Part 1.5 Work by Others in Section 01010 Summary of Work. Westinghouse will supply run of 

mine salt. The Contractor shall make suitable arrangements for transporting and placing the run 

of mine salt.
04100-2 Rev. 1 10/3/2002

3.2 Installation

Run of mine salt shall be transported to the panel closure area after the construction of explosion 

isolation wall has been completed. Salt will be pushed against the explosion isolation wall until 

the entire opening is filled over the length and angle of layback as shown on Drawings. The salt 

may be left at the angle of repose or some lower slope, but shall not be less than 1 (rise) to 2 

(run). There should be no gap left between backfill and roof or sidewalls. Hand placement can 

be used to fill all the voids if necessary. Backfill may be emplaced in layers to facilitate the 

construction.

3.3 Field Quality Control

The Contractor shall provide a Quality Control Inspector to inspect the emplacement of backfill. 
APPENDIX E

DESIGN DRAWINGS