THE HYDROCARBON SPILL SCREENING MODEL (HSSM) 

VOLUME 1: USER'S GUIDE

by

James W. Weaver

Robert S. Kerr Environmental Research Laboratory

United States Environmental Protection Agency

Ada, Oklahoma 74820

Randall J. Charbeneau, John D. Tauxe

Department of Civil Engineering

The University of Texas at Austin 

Austin, Texas 78712

Bob K. Lien

Robert S. Kerr Environmental Research Laboratory

United States Environmental Protection Agency

Ada, Oklahoma 74820

and

Jacques B. Provost

Computer Sciences Corporation

Ada, Oklahoma 74820

Robert S. Kerr Environmental Research Laboratory

Office of Research and Development

U.S. Environmental Protection AgencyAda, Oklahoma 74820
ii

Disclaimer

The information in this document has been funded wholly or in part by the United States Environmental

Protection Agency, through direct support of the EPA authors, cooperative agreement CR-813080 to the

University of Texas at Austin, Contract 68-C8-0058 with Dynamac Corporation, and Contract 68-W1-0043 with

Computer Services Corporation. It has been subjected to the Agency's peer and administrative review, and it

has been approved for publication as an EPA document. Mention of trade names or commercial products does

not constitute endorsement or recommendation for use.

All research projects making conclusions or recommendations based on environmentally related

measurements and funded by the United States Environmental Protection Agency are required to participate

in the Agency Quality Assurance Program. This project did not involve environmentally related measurements

and did not involve a Quality Assurance Plan.

The computer program described within this report simulates the behavior of water-immiscible

contaminants (NAPLs: NonAqueous Phase Liquids) in idealized subsurface systems. The approaches

described are not suited for application to heterogeneous geological formations, nor are they applicable to any

other scenario other than that described herein. The model is intended to provide order-of-magnitude estimates

of contamination levels only. The full model has not been verified by comparison with either lab or field studies.

Therefore the EPA does not endorse the use of this computer program for any specific purpose. As in the case

of any subsurface investigation, the scientific and engineering judgement of the model user is of paramount

importance. Any model results should be subjected to thorough analysis. In this user's guide, typical values

are given for various parameters. These are provided for illustrative purposes only.

When available, the software described in this document is supplied on an "as-is" basis without

guarantee or warranty of any kind, expressed or implied. Neither the United States Government (United States

Environmental Protection Agency, Robert S. Kerr Environmental Research Laboratory), The University of Texas

at Austin, Computer Sciences Corporation, nor any of the authors accept any liability resulting from the use

of this code. 
iii

Foreward

EPA is charged by Congress to protect the Nation's land, air and water systems. Under a mandate of

national environmental laws focused on air and water quality, solid waste management and the control of toxic

substances, pesticides, noise and radiation, the Agency strives to formulate and implement actions which lead

to a compatible balance between human activities and the ability of natural systems to support and nurture life.

The Robert S. Kerr Environmental Research Laboratory is the Agency's center of expertise for

investigation of the soil and subsurface environment. Personnel at the Laboratory are responsible for

management of research programs to: (a) determine the fate, transport and transformation rates of pollutants

in the soil, the unsaturated and the saturated zones of the subsurface environment; (b) define the processes

to be used in characterizing the soil and subsurface environments as a receptor of pollutants; (c) develop

techniques for predicting the effect of pollutants on ground water, soil, and indigenous organisms; and (d)

define and demonstrate the applicability of using natural processes, indigenous to the soil and subsurface

environment, for the protection of this resource.

One of the most common, yet complex, class of subsurface contaminants are the light nonaqueous

phase liquids (LNAPLs). Although the LNAPL itself remains distinct from the subsurface water, chemical

constituents of the LNAPL can cause serious ground water contamination. Since a number of phenomena and

parameters interact to determine contaminant concentrations at the receptor points, models are needed to

estimate the impacts of LNAPL releases on ground water. This user's guide describes the Hydrocarbon Spill

Screening Model (HSSM) which is intended to simulate release of an LNAPL. The intent of the model is to

provide a practical tool which is easy to apply and runs rapidly on personal computers.

Clinton W. Hall, Director

Robert S. Kerr Environmental

Research Laboratory
iv

Abstract

This user's guide describes the Hydrocarbon Spill Screening Model (HSSM). The model is intended

for simulation of subsurface releases of light nonaqueous phase liquids (LNAPLs). The model consists of

separate modules for LNAPL flow through the vadose zone, spreading in the capillary fringe, and transport of

chemical constituents of the LNAPL in a water table aquifer. These modules are based on simplified

conceptualizations of the flow and transport phenomena which were used so that the resulting model would

be a practical, though approximate, tool. Both DOS and Windows interfaces are provided to create input data

sets, run the model, and graph the results. These interfaces simplify the procedures for running the model so

that the model user may focus on analysis of his/her problem of interest. To that end, guidance is given for

selecting parameter values and several utility programs are provided to calculate certain parameters. Typical

example problems, which begin with a general problem statement, show exactly how each parameter of the

model should be chosen. 
v

CONTENTS

Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Foreward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

List of Figures ......................................................................... viii

List of Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

List of Abbreviations and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii

Acknowledgment ....................................................................... xiii

Section 1 Introduction .................................................................... 1

1.1 The Meaning of the Name HSSM ................................................ 1

1.1.1 Hydrocarbon ......................................................... 1

1.1.2 Spill ............................................................... 2

1.1.3 Screening Model ..................................................... 2

1.2 Components of the Model ...................................................... 2

1.3 Obtaining a Copy of HSSM ..................................................... 6

Section 2 Assumptions Underlying HSSM ................................................... 8

2.1 Kinematic Oily Pollutant Transport (KOPT) ......................................... 8

2.2 OILENS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.3 Transient Source Gaussian Plume Model (TSGPLUME) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Section 3 HSSM Interface Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.1 Typographical Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Section 4 The MS-Windows Interface, HSSM-WIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.1 Microsoft Windows Interface Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.2 System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.3 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.3.1 Packing List of Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.3.2 Copying Files to the Hard Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.3.3 Adding HSSM to a Program Manager Group . . . . . . . . . . . . . . . . 21

4.4 Using HSSM-WIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4.4.1 Starting Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4.4.2 Menu Command Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.5 Use of HSSM-WIN Commands for Performing HSSM Simulations . . . . . . . 25

4.5.1 Creating New Input Data Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.5.2 Editing Existing Input Data Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.5.3 Running the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.5.4 Graphing the Model Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.5.5 Graphing Results From a Previous Simulation . . . . . . . . . . . . . . . 27

4.5.6 Printing a Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.5.7 Comparing Several Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.5.8 Copying a Graph to the Clipboard . . . . . . . . . . . . . . . . . . . . . . . . . 29
vi

4.5.9 Exiting HSSM-WIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

4.6 Editing and Creating HSSM Data Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

4.6.1 Using the Input File Editors - Common Techniques . . . . . . . . . . . 30

4.6.2 Required Units for HSSM Simulations . . . . . . . . . . . . . . . . . . . . . . 31

4.6.3 General Model Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

4.6.4 Hydrologic and Hydraulic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4.6.5 Hydrocarbon (NAPL) Phase Data . . . . . . . . . . . . . . . . . . . . . . . . . 41

4.6.6 Model Simulation Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

4.7 Running the KOPT, OILENS and TSGPLUME Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

4.8 Graphical Presentation of HSSM Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

4.8.1 Saturation Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

4.8.2 NAPL Lens Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4.8.3 Contaminant Mass Flux History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4.8.4 NAPL Radius History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4.8.5 NAPL Lens Contaminant Mass Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4.8.6 Receptor Concentration Histories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4.9 A Note on the Efficiency of Using the Windows Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4.10 Menu Command Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Section 5 Example Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.1 Problem 1: Gasoline Arrival Time at the Water Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.2 Problem 2: Transport of Gasoline Constituents in Ground Water to Receptor Locations . . 76

Section 6 Contents of the Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

6.1 HSSM-KO Output File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

6.2 HSSM-T Output File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Appendix 1 The MS-DOS Interface, HSSM-DOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

1.1 The HSSM-DOS Menu program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

1.2 Data Entry in PRE-HSSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

1.3 Computation by HSSM-KO and HSSM-T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

1.4 Graphing of Results in HSSM-PLT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

1.5 Quick Summary of the DOS Interface Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

1.6 System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

1.7 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

1.8 Using the PRE-HSSM Preprocessor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

1.8.1 Saving Data to a File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

1.8.2 PRE-HSSM Main Menu Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

1.8.3 Creating and Editing HSSM Data Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

1.9 Running the KOPT, OILENS and TSGPLUME Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

1.10 Plotting HSSM Results with HSSM-PLT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

1.10.1 Package Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

1.10.2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

1.11 Graphical Presentation of HSSM Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

Appendix 2 DOS Example Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

2.1 Gasoline Arrival Time at the Water Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

Appendix 3 Sources of Parameter Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

3.1 Soil Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

3.2 NAPL/Water Partition Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
vii

3.3 Estimation of the Maximum NAPL Saturation in the Lens . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

Appendix 4 Approximate Conversion of Capillary Pressure Curve Parameters . . . . . . . . . . . . . . . . . . . . 180

Appendix 5 The Soil Property Regression Utility (SOPROP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

Appendix 6 The RAOULT Utility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184

Appendix 7 The NTHICK Utility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

7.1 Procedure for Using NTHICK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190

7.2 Example NTHICK Calculation Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

Appendix 8 The REBUILD Utility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

Appendix 9 Dual Installation of the DOS and Windows Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

Appendix 10 Direct Editing of HSSM-KO Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Appendix 11 Direct Editing of HSSM-T Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198

Appendix 12 PRE-HSSM Input Data Templates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

Appendix 13 HSSM-WIN Input Data Templates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
viii

List of Figures

Figure 1 Schematic view of NAPL release ................................................... 3

Figure 2 Schematic view of idealized NAPL release that is used in HSSM ......................... 4

Figure 3 HSSM schematic showing the use of each module .................................... 6

Figure 4 HSSM release options ........................................................... 9

Figure 5 Comparison of sharp and spreading fronts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 6 Comparison between experimental data and the KOPT model . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 7 Lens configuration during thinning phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 8 Gaussian source configuration used in TSGPLUME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 9 Coordinate systems for the KOPT, OILENS and TSGPLUME Modules of HSSM . . . . . . . . . . . 14

Figure 10 Schematic representation of a TSGPLUME concentration history . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 11 Installing HSSM-WIN in a Program Manager group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 12 The initial HSSM-WIN screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 13 File Open dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 14 File Save As dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 15 Display Graphs dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 16 Comparison of Graphs from Two Different Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 17 HSSM-WIN graph pasted into PAINTBRUSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 18 An example of a data entry error message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 19 General Parameters dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 20 Hydrologic Parameters dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 21 Hydrocarbon Phase Parameters dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Figure 22 Model Simulation Data dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Figure 23 Typical saturation profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Figure 24 Typical NAPL lens profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Figure 25 Typical contaminant mass flux history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Figure 26 Typical NAPL lens radius history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Figure 27 Typical NAPL lens contaminant mass balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Figure 28 Typical receptor concentration histories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Figure 29 HSSM-WIN "Help" information in HSSMHELP.TXT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Figure 30 Problem 1 completed General Parameters dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Figure 31 Problem 1 completed Hydrologic Properties dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Figure 32 Problem 1 completed Hydrocarbon Phase Properties dialog box . . . . . . . . . . . . . . . . . . . . . . 71

Figure 33 Problem 1 completed Simulation Parameters dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Figure 34 The storage tank example saturation profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Figure 35 Storage tank facility example with increased conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Figure 36 Problem 2 completed General Parameters dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Figure 37 Problem 2 completed Hydrologic Properties dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Figure 38 Problem 2 completed Hydrocarbon Phase Properties dialog box . . . . . . . . . . . . . . . . . . . . . . 80

Figure 39 Problem 2 completed Simulation Control dialog box parameters . . . . . . . . . . . . . . . . . . . . . . . 83

Figure 40 Saturation profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Figure 41 The front position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Figure 42 Storage tank facility example with increased conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

Figure 43 Comparison of average capillary pressure curves with measured data . . . . . . . . . . . . . . . . . 171

Figure 44 Comparison of equivalent Brooks and Corey and van Genuchten parameters for sandy soil 181

Figure 45 Comparison of equivalent Brooks and Corey and van Genuchten parameters for sandy clay loam

soil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
ix

List of Symbols

Latin

A Area

a Aquifer vertical dispersivity v

B Bulk partition coefficient defined by equation (25)

B(T) Time varying function of concentration at boundary (equation (86))

b Aquifer saturated thickness

b Observation well thickness of NAPL o

C Nondimensional concentration (equation (81))

c, c Concentration of the constituent in the water phase w

c Maximum concentration m

c Concentration of the constituent in the NAPL phase o

c Constituent concentration in the NAPL in equilibrium with the soil o(soil)

c Constituent concentration in the released NAPL o(surf.)

c Sorbed phase concentration of the constituent s

c Initial water phase concentration of the constituent w(initial)

c Equilibrium constituent concentration for water in contact with the NAPL wo

D Nondimensional dispersion coefficient (equation (81))

D Formation free-product thickness o

D Longitudinal dispersion coefficient L

D Transverse horizontal dispersion coefficient T

D Vertical dispersion coefficient V

d Depth of the NAPL contaminated zone pz

E Constant defined by equation (93)

erf() Error function

erfc() Complementary error function

F OILENS NAPL source head function 1

F OILENS lens radius function 2

f n function to be solved for a general Runge-Kutta scheme n

th 

G Known constant that relates lens source heads and radii at different times

g Acceleration of gravity

H Sum of the NAPL head terms in KOPT; Total penetration depth of leachate in TSGPLUME

H Penetration depth due to vertical advection of water entering the aquifer adv

H Penetration depth due to vertical dispersion in the aquifer dis

H NAPL head at the NAPL front f

H NAPL head at the surface s

h Pressure head in KOPT (equation (16))

h Air-NAPL capillary pressure head cao

h Air-water capillary pressure head caw

h Capillary pressure head or capillary rise for the i-j fluid pair cij

h Air-NAPL entry head ceao

h Air-water entry head ceaw

h NAPL head at a given location o

h NAPL head in the lens below the source (Figure 16) os

h NAPL-water capillary pressure head ow

I Value of the integral in equation (56) d

I Rate of infiltration outside the facility r

J Advective flux

J Mass flux of the chemical constituent c

K Hydraulic conductivity
x

K Effective conductivity to fluid i ei

K Effective conductivity to NAPL eo

K Saturated conductivity to fluid i si

K Saturated conductivity to NAPL so

K Saturated conductivity to water sw

k Intrinsic permeability

k Soil/water partition coefficient d

k Fluid i/water partition coefficient i

k NAPL/water partition coefficient o

k Relative permeability to fluid i ri

k Relative permeability to water rw

k Relative permeability to NAPL ro

L Length (in direction of ground water flow) of a surface facility

L(y) Length of a chord of a circle

M Total constituent mass in the NAPL lens t

m Mass of constituent per unit volume c

m Mass flow rate

m Total constituent flux into the aquifer diss

m Mass loss rate to the aquifer (equation (48)) infil

m Ground water source term from the NAPL lens source

n Time level

p KOPT model parameter i

Q KOPT-determined NAPL inflow rate (Figure 16) KOPT

Q Loss rate of NAPL from source cylinder (Figure 16) loss

Q NAPL loss rate due to dissolution and trapping (equation (43)) out

Q Lateral flow from the source cylinder (Figure 16) radial

q Darcy velocity in aquifer below facility (equation (67))

q Flux of fluid i i

q NAPL flux o

q Water flux w

q Volume flux of infiltrating rainfall wi

R NAPL lens radius

R Retardation factor d

R NAPL source radius s

R Lens radius t

r Radius

S Residual air saturation ar

S Saturation of fluid i i

S Residual saturation of fluid i ir

S NAPL saturation o

S Maximum NAPL saturation in KOPT solution o(max)

S Residual NAPL saturation or

S Water saturation w

S Water saturation associated with the average annual recharge rate w(avg)

S Residual water saturation wr

SC First order sensitivity coefficient for the KOPT model i

T Nondimensional time (equation (81))

t Time 

t Time origin o

V Volume of source cylinder beneath the surface source (equation (90)) C

V NAPL volume in the spreading lens L

V NAPL volume incorporated into the soil in KOPT o

V Total lens volume (including LNAPL, water and soil) T

V Total lens volume (including LNAPL, water and soil) in the vadose zone vz
xi

V Total lens volume (including LNAPL, water and soil) in the saturated zone sz

v Seepage velocity in the aquifer 

W Width (across the direction of ground water flow) of a surface facility

w Variable of integration in equations (55) and (95)

w ,w Limits of integration in equation (95) R Rs

X Nondimensional x coordinate (equation (81))

x Distance from upgradient edge of NAPL lens

Y Nondimensional y coordinate (equation (81))

y ,y ,...,y 1 12 n through n independent variable st th

Z Nondimensional z coordinate (equation (81))

z Depth 

z Level of the air-NAPL interface ao

z Level of the air-water interface (water table) in the absence of NAPL aw

z Level of the NAPL-water interface ow

z Front depth in KOPT f

Greek

$ Density term in equation (36)

) M Constituent mass loss from NAPL lens during a time step L

) V Volume of free product (LNAPL) that becomes trapped in a time step L

) V Change in total lens volume (LNAPL, water and soil) R

* m(y) Increment of mass flux into the aquifer

, Brooks and Corey relative permeability exponent

0 Porosity

7 Nondimensional effective decay coefficient in TSGPLUME (equation (81))

8 Brooks and Corey capillary pressure exponent; Decay coefficient in TSGPLUME

8 Effective decay coefficient in TSGPLUME *

μ Dynamic viscosity of fluid i i

μ Dynamic viscosity of the NAPL o

Db Bulk density

D Density of fluid i i

Do Density of NAPL

D Density of water w

F Standard deviation

Faw Water surface tension

Fo ao ,F NAPL surface tension

Fow NAPL-water interfacial tension

2 Volumetric NAPL content o

2orv Volumetric residual NAPL content in the vadose zone

2 Volumetric residual NAPL content in the aquifer ors
xii

List of Abbreviations and Acronyms

CSMoS Center for Subsurface Modeling Support

HSSM Hydrocarbon Spill Screening Model

HSSM-KO Computer code that implements KOPT and OILENS 

HSSM-T Computer code that implements TSGPLUME

KOPT Kinematic Oily Pollutant Transport (vadose zone portion of HSSM)

LNAPL Lighter-that-water nonaqueous phase liquid

NAPL Nonaqueous phase liquid

OILENS HSSM Module for NAPL lens motion and chemical dissolution into the aquifer

RSKERL Robert S. Kerr Environmental Research Laboratory

TSGPLUME Transient source gaussian plume model (aquifer module of HSSM)

USEPA United States Environmental Protection Agency
xiii

Acknowledgment

The authors express their appreciation to Susan Roberts-Shultz for the original development of

OILENS, to Mike Johnson for the original development of TSGPLUME, to Donald Collings for developing the

DOS preprocessor, to Mark Lee for developing the REBUILD and DOS menu programs, to Julia Mead and

Sarah Hendrickson for repeated testing of HSSM test data sets; and to Dr. Jeffrey A. Johnson, Dr. Varadhan

Ravi and Rick Bowers for extensive beta testing.
1 [Section 1 Introduction]

Section 1 Introduction

When fluids that are immiscible with water (the so-called nonaqueous phase liquids or NAPLs) are

released in the subsurface, they remain distinct fluids, flowing separately from the water phase. Fluids less

dense than water (LNAPLs) migrate downward through the vadose zone, but upon reaching the water table,

tend to form lenses on top of the aquifer. Generally, the fluids are composed of complex mixtures of individual

chemicals, so that aquifer contamination results from the dissolution of various constituents of the LNAPL. This

document describes a screening model called the Hydrocarbon Spill Screening Model (HSSM) for estimating

the impacts of this type of pollutant on water table aquifers. The model is based on approximate treatments

of flow through the vadose zone, LNAPL spreading along the water table, and miscible transport of a single

chemical constituent of the LNAPL through a water table aquifer to various receptor points. Emergency

response, initial phases of site investigation, facilities siting, and underground storage tank programs are

potential areas for use of HSSM.

The user's guide is organized into sections that describe the assumptions underlying the model, the

required input data and the mechanics of running the model. Separate MS-DOS and MS-Windows interfaces

are provided for the model. Each interface has the capability to enter and edit input data sets, run the model,

and display graphs of the results. The advantages and disadvantages of each interface are briefly described

in order to aid the user in selecting the appropriate interface for his/her hardware and software configuration.

Following the description of the interfaces, several example problems are presented that illustrate the steps

necessary for setting up and running the model. 

1.1 The Meaning of the Name HSSM

Each word in the name of the model is used below as a point-of-departure for a discussion of some

issues related to use of the model. Specific information on the model's parameter values and directions for use

of the model are given in later sections.

1.1.1 Hydrocarbon

In HSSM, the LNAPL (or hydrocarbon) is assumed to be composed of two components. The first

component is the LNAPL itself, which is a liquid that is separate from and does not mix with the subsurface

water. The model contains a set of equations for tracking the motion of the LNAPL phase. Several of the

results and graphs produced by the model depict the distribution of the LNAPL phase. The second component

is referred to as a chemical constituent of the LNAPL, because typical LNAPLs are composed of many

individual chemicals. HSSM tracks the transport of one of these chemicals. Since the chemical constituent

may dissolve into the subsurface water, it can be transported by the groundwater and contaminate down

gradient receptor points. For example, HSSM may be used to simulate a gasoline release. Benzene could be

the chemical constituent of interest. All of the rest of the chemicals composing the gasoline would be treated

as being part of the LNAPL. When the impact of another constituent of gasoline, say toluene, needed to be

determined, the chemical constituent would be the toluene. In this way, HSSM could be run for several of the

important chemical constituents of the LNAPL. The model user could develop a feel for the behavior of the

different chemicals by comparing the results.

HSSM is designed for LNAPLs. It is not suitable for denser-than-water NAPLs (DNAPLs) as the NAPL

is assumed to "float" on the water table. The vadose zone module of HSSM (Section 2.1) could, however, be

used for a DNAPL, as the qualitative behavior of that module is not affected by fluid density. 
[Section 1 Introduction] 2

1.1.2 Spill 

Spillis used as a generic term for a release of LNAPL. The release may be a spill, leak or other event

which allows the LNAPL to enter the subsurface. In HSSM some details of the release must be known as they

are required for input to the model. These details may include the beginning and ending times of the release,

the rate of release of the LNAPL or the ponding depth of the LNAPL at the surface. 

1.1.3 Screening Model

Screening models may include a variety of chemical and hydrological processes, but usually do not

include subsurface heterogeneity. Most screening models are in the form of analytical solutions of their

governing equations. Simplifications must usually be made in order to get these analytical solutions. As a

result, computer implementations of screening models use only relatively small amounts of computer time.

In general, screening models can be used to estimate the impacts of contamination, given their assumptions.

The HSSM is a screening model; it includes a number of chemical and hydrologic phenomena, assumes

subsurface homogeneity, executes rapidly on PCs, and excludes some phenomena. For example, if gasoline

is spilled, HSSM may be used to give a rough estimate of ground water concentrations of constituents of the

gasoline. The model is intended only to give order-of-magnitude results, because a number of potentially

important processes are treated in the model in an approximate manner or are ignored entirely. Also, one

would not expect to calibrate the model by adjusting the spatial distributions of the parameters, as heterogeneity

is not included in the model.

 

If simulation of complex heterogeneous sites is needed or other approximations made in HSSM are

unacceptable, then a more inclusive model, such as the MOFAT code developed at Virginia Polytechnic

Institute (Kuppusamy et al., 1987); the SWANFLOW code developed by Geotrans, Inc. (Faust, 1985); the

MAGNUS code developed by Hydrogeologic, Inc. (Huyakorn and Kool, 1992); or the VALOR code developed

by The Electric Power Research Institute (Abriola et al., 1992) should be used instead of, or in addition to,

HSSM. Potential users of HSSM should pay close attention to the following discussion of the assumptions and

limitations of the model, so that they may make an informed decision on the use of the model.

1.2 Components of the Model

Figure 1 shows a typical release of a LNAPL pollutant at the ground surface. The LNAPL flows

downward through the vadose zone due to gravity and capillary forces. The LNAPL is deflected from its

downward path by geologic heterogeneities it encounters on its way toward the water table. Infiltrating rainwater

may push the LNAPL down faster than it would move on its own. Once in the vicinity of the water table, the

LNAPL floats in the capillary fringe since it is a nonwetting phase that is less dense than water. Fluctuation of

the water table due to natural causes or wells may create a smear zone containing trapped LNAPL. Contact

with the ground water or infiltrating recharge water causes the chemical constituents of the LNAPL to dissolve,

resulting in aquifer contamination. The constituents may be leached at different rates due to their diverse

properties. Depending on their volatility, the constituents also partition into the vadose zone air. 

Once in the aquifer, limited mixing leaves the constituents in a relatively narrow band near the top of

the aquifer. These constituents are transported by advection and dispersion through the aquifer. The aquifer,

like the vadose zone, is heterogeneous and flow may follow preferential pathways. 
3 [Section 1 Introduction]

Figure 1 Schematic view of NAPL release

The HSSM is based on a simplified conceptualization of a LNAPL release. Figure 2 shows the

geometry assumed for HSSM, which is a simplified version of the scenario described in Figure 1. Within

HSSM, the LNAPL follows a one-dimensional path from the surface to the water table. Properties of the

subsurface are taken as being uniform. The LNAPL is composed of two components: one is the LNAPL phase

and the other is the chemical constituent of interest. At the water table, the LNAPL spreads radially, which

implies that the regional gradient has no effect on the flow of the LNAPL. Dissolution of the chemical

constituent obeys local equilibrium partitioning, but is driven by the flowing ground water and recharge water

reaching the water table. The chemical constituent is transported by advection and dispersion to multiple

receptor points in the uniform aquifer. Further details on these assumptions are given below.

The model is composed of three modules, based on the simplified conceptualization presented above.

All of the modules are in the form of semi-analytical solutions of the governing equations, so the modules of

HSSM do not use discretization of the flow domain nor iterative solution techniques. These approximations are

designed to execute rapidly. The conceptual basis of the modules are discussed in the following paragraphs.

The mathematical details of the modules are found in The Hydrocarbon Spill Screening Model (HSSM)

Volume 2: Theoretical Background (Charbeneau et al., 1994). 

The model is intended to address the problem of LNAPL flow and transport from the ground surface

to a water table aquifer. Assuming that the principle interest lies with water quality, an emphasis of the model

is the determination of the NAPL lens size and the mass flux of contaminants into the aquifer. These quantities

define the source condition for aquifer contamination and must be based upon multiphase flow phenomena

in the vadose zone. The first two modules of HSSM address the vadose zone flow and transport of the LNAPL.

These two are the Kinematic Oily Pollutant Transport (KOPT) and OILENS modules. KOPT and OILENS are

combined into one computer code, HSSM-KO, which provides a time-variable source condition for the aquifer

model.
[Section 1 Introduction] 4

Figure 2 Schematic view of idealized NAPL release that is used in HSSM

A chemical constituent dissolved in both the LNAPL and water phases is tracked by KOPT and

OILENS. Once that chemical constituent reaches the water table, it contaminates the aquifer by contact with

the recharge water and by dissolution from the LNAPL lens. Thus, the third part of the model is transported

through the aquifer of one chemical constituent of the LNAPL. Notably, the mass flux from OILENS is time

varying, so that the aquifer model must be capable of simulating a time varying source condition. In keeping

with the level of approximation used in KOPT and OILENS, one suitable choice is the Transient Source

Gaussian Plume (TSGPLUME) model, which uses an analytical solution of the advection-dispersion equation.

TSGPLUME uses different numerical techniques than KOPT and OILENS; so it is not incorporated within

HSSM-KO, but rather is implemented in the computer code HSSM-T. The 

TSGPLUME model takes the dissolution mass flux from the OILENS module of HSSM-KO and calculates the

expected concentrations at a number of down gradient receptor points. 

Table 1 summarizes the component modules of the HSSM. Note that the names KOPT, OILENS and

TSGPLUME refer to the mathematical models, while HSSM-KO and HSSM-T refer to the computer

implementations of the models. 
5 [Section 1 Introduction]

 Table 1 Implementation of HSSM modules

Subsurface Region Mathematical Computer Code

Model

Vadose zone KOPT HSSM-KO

Water table OILENS HSSM-KO

Aquifer TSGPLUME HSSM-T
[Section 1 Introduction] 6

Figure 3 HSSM schematic showing the use of each module

The portion of the subsurface covered by each module of HSSM is shown in Figure 3. In the model

scenario, the contamination is introduced as an LNAPL which flows from near the surface to the water table.

This portion of the contamination event is modeled by KOPT and OILENS, as indicated on the figure. Through

contact with the infiltrating recharge and the groundwater, chemical constituents of the NAPL dissolve and

contaminate the aquifer. Transport of one chemical constituent of the NAPL is simulated by TSGPLUME.

1.3 Obtaining a Copy of HSSM 

HSSM is available from the Center for Subsurface Modeling Support (CSMoS) at the Robert S. Kerr

Environmental Research Laboratory (RSKERL). CSMoS distributes software and documentation free-ofcharge through a diskette exchange program and provides technical support for the codes they distribute. To

obtain the HSSM software and user documentation send a letter of request along with two high density 3.5"

formatted diskettes to the following address:

Center for Subsurface Modeling Support

Robert S. Kerr Environmental Research Laboratory

United States Environmental Protection Agency

P.O. Box 1198

Ada, Oklahoma 74820

Voice: 405-436-8586

FAX: 405-436-8529

Please indicate if the DOS or Windows version is needed. If both interfaces are needed, enclose three

formatted diskettes.

The complete HSSM package consists of the documents

9 The Hydrocarbon Spill Screening Model (HSSM) Volume 1: User's Guide,

9 The Hydrocarbon Spill Screening Model (HSSM) Volume 2: Theoretical Background and Source 

Codes,
7 [Section 1 Introduction]

and the two high density 3.5" diskettes. The diskettes contain: 

For Windows:

9 diskette HSSM-1-w The Windows Interface, HSSM-WIN

For DOS:

9 diskette HSSM-1-d The DOS Interface, HSSM-DOS 

For Windows and DOS:

9 diskette HSSM-2 Example Problems

HSSM and the user documentation are in the public domain. They may be freely distributed or copied by

anyone.
[Section 2 Assumptions and Limitations] 8

Section 2 Assumptions Underlying HSSM

The following paragraphs discuss the conceptual basis of KOPT, OILENS and TSGPLUME. This

discussion is intended to give a clear understanding of the assumptions and limitations of each module of

HSSM.

2.1 Kinematic Oily Pollutant Transport (KOPT)

The Kinematic Oily Pollutant Transport (KOPT) model simulates flow of the LNAPL phase and

transport of a chemical constituent of the LNAPL from the surface to the water table. The LNAPL is assumed

to be released at or below the ground surface in sufficient quantity to form a fluid phase that is distinct from the

water. As a result, the amount of LNAPL released is far greater than that which would give only contamination

dissolved in the water phase. The flow system is idealized as consisting of a circular source region overlying

a water table aquifer at specified depth. Although the actual flow in the vadose zone is three-dimensional, the

KOPT model treats flow and transport through the vadose zone as one-dimensional. Lateral spreading of

contaminants by capillary forces is neglected, as is spreading due to heterogeneity, since the soil is assumed

to be of uniform composition. For situations where the NAPL is released over a relatively large area, the actual

flow is nearly one-dimensional in the center. For contaminant sources that are of small areal extent, the lateral

transport of contaminants may be significant. By treating the flow as one-dimensional, however, the modeling

is conservative as all of the pollutant is assumed to move downward and contribute to aquifer contamination.

In actuality, some may be left behind due to entrapment by layering or lateral spreading. 

The spill of the LNAPL phase may be simulated in three ways (Figure 4): 

 The release of an LNAPL may occur at a known flux for a specified duration. This situation would

occur if a known volume of LNAPL was released during a certain time period. The LNAPL volume

divided by the duration and area of release determines the release rate, q . If the LNAPL flux exceeds o

the maximum effective LNAPL conductivity, K , some of the LNAPL will run off at the surface. eo

 A known volume of LNAPL may be placed over a specified depth interval, d . When the simulation pl

begins the LNAPL may begin to flow out of the specified zone, if the LNAPL retention capacity of the

soil is exceeded.

 The last option is the specification of a constant depth of ponded LNAPL for a certain duration. This

case represents a slowly leaking tank or a leaking tank within an embankment. In either of these

situations, the ponded depth of NAPL is estimated or known. Two options are available for this

boundary condition. In the first, the ponding abruptly goes to zero at the end of the ponding period.

In the second, the ponded depth decreases gradually at the end of the ponding period. 
9 [Section 2 Assumptions and Limitations]

IFigure 4 HSSM release options

LNAPL phase flow is assumed to occur within the soil which contains a uniform amount of water. In

KOPT, the amount of each fluid is expressed as saturation, S, which is defined as the fraction of the pore space

filled by a given fluid. The water saturation corresponds to the average annual recharge rate or a specified

water saturation. By using this approach, the temporal effects of climate are neglected. Justification of this

approach comes from the fact that in uniform soils the soil moisture profile shows little variation except near

the surface (Charbeneau and Asgian, 1991). Many data are required to simulate the time record of rainfall

events to develop the non-uniform and time-variable soil moisture profile. The level of effort involved is not

consistent with the intended purpose of the model as a screening methodology. Weaver (1991) presented

model results which illustrate the effects of rainfalls on in-place LNAPLs. This work showed that when

simulating fuels such as gasoline, the LNAPL often reaches the water table rapidly. So simulation of long

sequences of rainfalls may be of little use, if the objective of the modeling is to estimate the gasoline's arrival

time at the water table.

In accordance with common soil science practice (Richards, 1931), the effect of the air flow on the

LNAPL phase transport is neglected in KOPT. The presence of the water and air phases is incorporated by

the use of a non-hysteretic, three-phase, relative permeability model. This model is a reasonable approximation

of the pore-scale phenomena occurring in three-phase flow, but the actual nature of these relationships is a

major cause of uncertainty in this and most other multiphase flow models. The model uses measured

properties of the soil (capillary pressure curve parameters) to approximate the relative permeability. The model

does not include transport in fractures or macropores.
[Section 2 Assumptions and Limitations] 10

Figure 5 Comparison of sharp and spreading fronts

Figure 6 Comparison between experimental data and the KOPT model

Efficiency is achieved in running the model primarily by neglecting the effects of the capillary gradient
11 [Section 2 Assumptions and Limitations]

on most aspects of the flow. This causes the governing equations to become hyperbolic equations, which can

be solved by the generalized method of characteristics (Charbeneau et al., 1994). One major effect of this

assumption on the simulation results is that the leading edge of the LNAPL moving into the soil is idealized as

a sharp front (Figure 5). Some laboratory experiments in uniform sand packings (Reible et al.,1990) show soil

NAPL profiles which have nearly sharp fronts. Similar results have been found in flow visualization

experiments conducted in nearly uniform sands at the Robert S. Kerr Environmental Research Laboratory

(RSKERL) and reported in Weaver et al. (1993). Figure 6 shows an experimental result for a gasoline release

into a uniform sand. Independently measured parameter values were used to simulate the experiment. It is

clear that KOPT is able to simulate the main qualitative features of the flow, because the shape of the simulated

NAPL front matches that of the experimental data. Quantitative agreement was obtained by adjusting

parameter values within their measured ranges. The details of a similar experiment are presented in Volume

2 of the HSSM documentation (Charbeneau et al., 1994). 

Since the capillary gradient has a dramatic impact on the infiltration capacity of the soil, the approximate

Green-Ampt model (Green and Ampt, 1911) is used to estimate the infiltration capacity during the application

of the LNAPL phase. This gives an improved estimate of flux in the soil, given a flux or constant head ponding

condition at the surface. 

In KOPT and OILENS, the LNAPL is treated as a two-component mixture. The LNAPL itself is

assumed to be soluble in water and sorbing. Due to the effects of the recharge water and contact with the

ground water, the LNAPL may be dissolved. This may be significant for highly soluble LNAPL phases. The

LNAPL's transport properties (density, viscosity, capillary pressure, relative permeability), however, are

assumed to be unchanging. The second component is the chemical constituent which can partition between

the LNAPL phase, water phase and the soil. This constituent of the LNAPL is considered the primary

contaminant of interest. Concentrations of this constituent are reported in the model output and graphed by

the post-processors.

A kinematic approach is used by KOPT for transport of the chemical constituent, which results in a

model that neglects dispersion. The chemical motion is assumed to be caused by the advection of water and

LNAPL only. Hydrophobic contaminants that reside primarily in the LNAPL phase will largely be transport with

the LNAPL. The chemical constituent, which is the second component of the LNAPL phase discussed above,

is assumed to partition between the NAPL, water and soil according to equilibrium, linear partitioning

relationships. The constituent mass flux into the aquifer comes from recharge water that is contaminated by

contact with the lens and from dissolution that occurs as ground water flows under the lens. The concentration

of the chemical in the aquifer is limited by its effective mixture solubility, which is less than its pure phase

solubility in water.

2.2 OILENS

If a large enough volume of hydrocarbon is released, then the LNAPL reaches the water table.

Typically this occurs in a relatively short time for LNAPLs, like gasoline, that have low viscosities. The OILENS

module simulates radial spreading of the LNAPL phase at the water table and dissolution of the chemical

constituent. If sufficient head is available, the water table is displaced downward; lateral spreading begins; and

the OILENS portion of the model is triggered. OILENS is based on three major approximations. First, the

LNAPL spreading is purely radial, which implies that the slope of the regional ground water table is small

enough to be unimportant for the lens motion. Second, the thickness is determined by buoyancy alone

(Ghyben-Herzberg relations). Third, the shape of the lens is given by the Dupuit assumptions, where flow is

assumed horizontal and the gradient is approximated by the change in head over a horizontal distance. These

three assumptions lead to an efficient formulation of the model, which is reflected in its low computational

requirements. 

The lens thickness in the formation and the lens radius both increase during the initial phase of
[Section 2 Assumptions and Limitations] 12

spreading (Figure 2). The height of the lens depends on the LNAPL phase density and viscosity, the release

characteristics, and the saturated hydraulic conductivity of the system. For example, in a given porous medium,

diesel fuel would tend to form taller lenses than gasoline because of its higher viscosity. Initially the lenses build

up height because the LNAPL enters the lens at a higher rate than it moves radially. Later, after the source rate

declines, the lens thins while continuing to spread laterally. Residual hydrocarbon is left both above and below

the actively spreading lens during this period (Figure 7). The thickness calculated by OILENS is an averaged

thickness of the LNAPL in the formation (Appendix 3.3, Schwille, 1967) and is not necessarily directly related

to the thicknesses observed in observation wells (Kemblowski and Chiang, 1990).

Figure 7 Lens configuration during thinning phase
13 [Section 2 Assumptions and Limitations]

Figure 8 Gaussian source configuration used in TSGPLUME

2.3 Transient Source Gaussian Plume Model (TSGPLUME) 

Aquifer transport of the chemical constituent is simulated by the Transient Source Gaussian Plume

Model (TSGPLUME) which uses a two-dimensional vertically averaged analytical solution of the advectiondispersion equation. Two important considerations are the boundary condition for the aquifer and the

assumptions used in applying the two-dimensional planar model. 

The boundary conditions are placed at the down gradient edge of the lens and take the form of a

Gaussian concentration distribution with the peak directly down gradient of the center of the lens (Figure 8).

The peak concentration of the Gaussian distribution adjusts through time so that the simulated mass flux from

the lens equals that going into the aquifer. The width of the Gaussian distribution remains constant and is taken

so that four standard deviations are equal to a representative diameter of the lens. Although the size of the lens

varies with time, a constant diameter is used in TSGPLUME for the aquifer source condition. A reasonable

choice for the lens diameter is the diameter that occurs when the mass flux into the aquifer is a maximum. This

choice assures that the peak mass flux into the aquifer occurs through an appropriately-sized lens. 

Although the aquifer model is two-dimensional in the horizontal plane, complete mixing of the chemical

over the aquifer thickness is neither necessary nor assumed a priori. Vertical mixing is represented by the depth

of penetration of the plume into the aquifer and is calculated from the amount of vertical dispersion beneath

the lens plus the advective flow due to infiltration through the lens, following the approach of Huyakorn et al.

(1982). If the calculated penetration depth exceeds the aquifer thickness, then the plume fully penetrates the

aquifer; and the model allows for dilution of the plume by diffuse recharge. If the penetration depth is less than

the aquifer thickness, then the plume thickness is taken as the penetration depth. In the latter case, recharge

simply pushes the plume deeper and the penetration thickness remains constant. 
[Section 2 Assumptions and Limitations] 14

Figure 9 Coordinate systems for the KOPT, OILENS and TSGPLUME Modules of HSSM

Figure 9 shows the coordinate systems for all three modules of the HSSM model. For KOPT and

OILENS, the source of contamination is assumed to be a circle of radius, R , located at the ground surface. s

The coordinate origin is located at the center of the source. X is the down gradient direction, and Y is the

transverse horizontal direction. The Z axis points downward, so that the depth is equal to the Z coordinate

value. In TSGPLUME, the source of contamination is assumed to be a circle of radius R , located at the water T

table. The size of the source is taken as a radius calculated in the OILENS module. The coordinate origin

(X ,Y ) is assumed to be at the down gradient edge of the source of contamination. The T T HSSM-T

implementation of TSGPLUME adjusts the X coordinates used by HSSM-KO to the X values needed by T

TSGPLUME (X = X - R ). T T The coordinates written in the output and plot files are the coordinates used by

KOPT and OILENS (X,Y,Z).

In TSGPLUME, the water flow is assumed to be one-dimensional, so advection of the contaminant is

simulated only in the longitudinal (X ) ground direction. The constituent may be transported by dispersion, T

however, both longitudinally (X ) T T and transversely (Y ). As with many analytical solutions, the aquifer is

assumed uniform. The mass flux into the aquifer varies with time, and the concentration history at the receptor

point is determined by integration of the constant input solution and the variable mass flux distribution into the

aquifer.
15 [Section 2 Assumptions and Limitations]

Figure 10 Schematic representation of a TSGPLUME concentration history

The results from TSGPLUME are concentration histories at user-specified receptor points. At these

points, the model calculates the aqueous phase concentration of the contaminant beginning at the time at

which the concentration first rises above a threshold value (time A on Figure 10 ). This time is determined by

a search algorithm which uses the analytical solution to determine the earliest time at which the concentration

is above the threshold. Typically the threshold value is set to 1 ppb by the model user. Calculation of the

receptor concentration continues at intervals of )t, as set by the user. The time interval is shortened at time

B to a small value in order to capture the peak concentration. If necessary, the step is further shortened in

order to make sure that the peak is found. Once the concentration is reduced below the peak (time C), the time

step increases gradually to again equal the original )t. Calculation continues until the concentration drops

below the threshold (time D).
[Section 3 Interface Options] 16

Section 3 HSSM Interface Options

Two interfaces are provided to assist the user in running the HSSM. The first interface was developed

for the Microsoft Windows operating system. This interface consists of the windows interface program, HSSMWIN, and the two simulation programs: HSSM-KO and HSSM-T. HSSM-WIN is used to create and edit input

data sets, execute HSSM-KO and HSSM-T, and plot the model results. The windows interface is described

in Section 4, titled "The MS-Windows Interface, HSSM-WIN." 

 Table 2 Comparison of MS-DOS and MS-Windows Interfaces

Interface Advantages Disadvantages

DOS 1. The fastest performance of model 1. The DOS preprocessor is interactive

calculations is achieved (for any given but not graphical.

computer) under the DOS interface.

2. DOS interface can run on a machine

with limited processing power and

limited RAM. The code will execute,

albeit slowly, on a 286 machine with 640

kiloBytes of RAM.

Windows 1. A single shell program performs all 1. The calculations performed by

necessary functions of the model. HSSM-KO and HSSM-T are slower

under the Windows interface due to

Windows overhead.

2. Data are entered directly on graphical 2. Requires a machine with enough

screens. processing power and memory to run

Windows effectively. Typically this

would be a 386 or higher with at least 4

megaBytes of RAM.

3. Simultaneous display of all model 3. Requires a certain level of expertise

output. with Windows.

4. Simultaneous display of output from 4. More system memory is consumed

simulations with different parameter by Windows than by DOS.

values.

5. Ability to cut and paste to other

Windows applications. 

The second interface was developed for the MS-DOS operating system. In this case the interface

consists of four programs: PRE-HSSM, HSSM-KO, HSSM-T, and HSSM-PLT. PRE-HSSM is used to create

and edit input data files; HSSM-KO and HSSM-T perform the model calculations, and HSSM-PLT is used to

plot and output the model results. The four programs can be run individually or the HSSM-DOS program can

be used as a simple menu system. The DOS interface is described in Appendix 1 "The MS-DOS Interface,

HSSM-DOS." 
17 [Section 3 Interface Options]

Each of the interfaces can be used to create and edit input data files, run the model, and plot the

results. The Microsoft Windows interface allows extensive manipulation of the model output, concurrent display

of all of the main outputs of the model, and concurrent display of results from several simulations. To aid in

selecting a user interface, Table 2 describes some advantages and disadvantages of each interface. Detailed

information on running the HSSM under each of the interfaces is given in the respective section or appendix.

Each contains the same information on estimation of the model parameter values, so that the user has the

parameter information available where its input procedures are described.

Three utility programs are provided to simplify calculation of values of certain input parameters. The

utilities, which are listed in Table 3, are referenced as necessary where the parameter values are described.

 Background information and instructions for running the utilities are provided in appendices. 

Table 3 HSSM Data Calculation Utilities

Parameter(s) Utility Program Name

Soil Hydraulic Properties SOPROP

Equilibrium NAPL/water partition coefficients RAOULT

Average NAPL saturation for OILENS NTHICK

 

3.1 Typographical Conventions

The typographical conventions shown in Table 4 are used throughout the user's guide.

Table 4 Typographical Conventions

Type style Use

PROGRAM Program names are written in capitals. For example: HSSM-WIN, HSSM-DOS,

HSSM-KO, and HSSM-T.

new term Italic type usually signals a new term. 

KEYBOARD Small capitals are used to identify the names of keys on the keyboard like CTRL, F1,

or ESC.

FILE.DAT Filenames appear in this typeface. Specific references to the program files also use

this typeface, for example: HSSM-KO.EXE refers to the file which contains the

HSSM-KO program.

COMMAND Commands entered at the DOS prompt and ASCII messages written to the screen

by DOS programs.
[Section 4 The MS-Windows Interface] 18

Section 4 The MS-Windows Interface, HSSM-WIN

The MS-Windows interface, HSSM-WIN, provides a convenient interface for creating and editing data files,

running HSSM, visualizing the output from several runs at one time, and exporting graphics into other Windows

applications. This interface was developed from the ShowFlow Modeling Interface developed at the University

of Texas at Austin (Tauxe, 1990) and is described in this section of the user's guide.

4.1 Microsoft Windows Interface Overview

The main functions of the interface are outlined in Table 5. Necessary details are provided in the sections

noted in the table.

Table 5 Outline of the HSSM-WIN Interface

Interface Function Section References

1. Installation of HSSM-WIN 4.2 and 4.3

2. Operation of the HSSM-WIN Interface, 4.4

Summary of Interface Commands

3. Creation of Data Sets 4.5

4. Editing of Input Parameters 4.6.1 and 

4.6.3 to 4.6.6

5. Running HSSM-KO and HSSM-T 4.5.3, 4.7

6. Graphing HSSM Results 4.5.4

7. Interpretation of HSSM Graphs 4.8

8. HSSM Output File Contents 6

The general procedure for using HSSM-WIN follows. After installing HSSM-WIN, a data set must be

created by selecting the HSSM-WIN "Edit" menu item (Section 4.5). HSSM-WIN contains four data editing

screens (called dialog boxes) that are used in succession to create the complete input data sets for HSSM-KO

and HSSM-T (Sections 4.6.1 and 4.6.3 to 4.6.6). Once the user is satisfied with the data set, then the data are

saved to a new file name or an existing file may be overwritten. This file name is loaded into HSSM-WIN's

memory and will be used when the simulation is performed.

HSSM-KO and HSSM-T are executed from the Windows interface. Since HSSM-KO and HSSM-T are

independent programs, they must be run in succession to complete the entire simulation. Section 4.7 describes

the execution of these programs. Once each has finished, a DOS window remains on screen that the user must

close before proceeding. This feature is provided because it is important to see the screen messages that are

written by the programs. (Windows would normally close the DOS window immediately upon completion of

the programs and the user would not be able to see the final set of messages.)

When a simulation is completed, the results may be graphed with the HSSM-WIN Graph menu item. Six
19 [Section 4 The MS-Windows Interface]

graphs can be displayed by the interface, and the user may select those he/she would like to view (Section

4.5.4). HSSM-WIN allows copying of graphs to other Windows applications (Section 4.5.8), simultaneous

display of results from multiple simulations (Section 4.5.7), and printing of the graphs (Section 4.5.6). 

4.2 System Requirements

HSSM-WIN is an application written for the Microsoft Windows graphical environment. To use the

Windows interface the user should be generally familiar with personal computers, DOS, Windows, and the

HSSM model. Users are advised to learn various features of Windows, as many of the capabilities of HSSMWIN require knowledge of Windows functions. There are several requirements for your system: 

HARDWARE:

9 For 386 enhanced mode, a personal computer with the Intel 80386 processor (or higher) and 2

megabytes (MB) or more of memory (640K conventional memory and at least 1024K of extended

memory).

For standard mode, a personal computer with the Intel 80286 processor (or higher) and 1 megabyte

or more of memory (640K conventional memory and at least 256K extended memory).

For real mode, a personal computer with the Intel 8086 or 8088 processor (or higher) and 640K

conventional memory. Windows 3.1 and later do not support real mode.

9 A hard disk and at least one floppy disk drive.

9 A video monitor supported by Windows (EGA or better resolution).

9 A printer supported by Windows.

9 A mouse that is supported by Windows is strongly recommended.

The amount of system memory available under Windows may be checked by opening a DOS window and

typing the DOS MEM command. The amount of memory available for running a DOS application will be

displayed. This amount must exceed the approximately 400 kbytes required by HSSM-KO. If sufficient

memory is not available under Windows, HSSM-KO and HSSM-T may be run under DOS and the results later

plotted by HSSM-WIN. 

SOFTWARE:

9 Microsoft Windows version 3.0 or later.

9 Windows requires MS-DOS or PC-DOS version 3.1 or later. 

4.3 Installation

4.3.1 Packing List of Files

Table 6 shows the files that are found on the HSSM-WIN distribution diskette, HSSM-1-w.
[Section 4 The MS-Windows Interface] 20

Table 6 Packing list of files for the HSSM Windows interface

File Purpose

HSSM-WIN.EXE The Windows interface program

HSSM-KO.EXE The KOPT and OILENS modules of HSSM

HSSM-T.EXE The TSGPLUME module of HSSM

HSSM-KO.PIF A Windows program information file (pif) for HSSM-KO.EXE

HSSM-T.PIF A Windows program information file (pif) for HSSM-T.EXE

REBUILD.EXE A recovery program for interrupted simulations

REBUILD.PIF A Windows program information file (pif) for REBUILD.EXE

HSSMHELP.WRI The HSSM-WIN help file, which can be read by Windows WRITE (the word

processor bundled with Windows). 

README.TXT This file contains information on changes which have occurred since the

writing of the user's guide.

RAOULT.EXE Utility to perform Raoult's Law Calculation

RAOULT.DAT Default data set for the RAOULT utility

SOPROP.EXE Utility to estimate soil properties with Rawls and Brakensiek's (1985)

regression equations.

NTHICK.EXE Utility to estimate NAPL thickness at the water table

SYSTEM\COMMDLG.DL Windows dynamic link library provided for users of Windows 3.0

L

Several example problems, including those presented in Section 5, are distributed on diskette HSSM-2. Be

sure to back up these files on other diskettes and to write-protect the distribution diskettes.

4.3.2 Copying Files to the Hard Drive

This section describes the installation of HSSM-WIN from DOS, which is the simplest installation

procedure. Check the README.TXT file for information on automated installation procedures which are under

development as of this writing. Experienced users of Windows can install the program using Window's File

Manager. For further information on File Manager, consult your Windows reference materials. 

After backing up the HSSM-1-w diskette, create a sub-directory for the model by entering the DOS

command:

MKDIR C:\HSSM

where HSSM is the name of the HSSM-WIN subdirectory. With the HSSM-1-w diskette in drive A, copy all of

the files from the diskette to the HSSM directory on the hard drive by entering:

COPY A:\*.* C:\HSSM
21 [Section 4 The MS-Windows Interface]

(The HSSM-1-w diskette may be in another drive, say B, by entering "B:" rather than "A:" in the previous

command.) The example problems and output files contained on diskette HSSM-2 should be installed into a

separate directory. Create the example problem directory by entering:

MKDIR C:\HSSM\EXAMPLE

The files are copied to this directory by entering:

COPY A:\*.* C:\HSSM\EXAMPLE

Subdirectories can and should be created for each HSSM simulation. For example, to create a directory

PROJECT1, enter the command:

MKDIR C:\HSSM\PROJECT1

By selecting the PROJECT1 subdirectory when using HSSM, all the input and output files for the simulation will

be in C:\HSSM\PROJECT1. 

Users of Windows 3.0 will also need to copy the dynamic link library COMMDLG.DLL from the SYSTEM

subdirectory on the distribution diskette to the SYSTEM subdirectory of their windows directory on the hard disk

by entering:

COPY A:\SYSTEM\COMMDLG.DLL C:\WINDOWS\SYSTEM

Windows 3.1 users already have this file. The user will now likely wish to add HSSM-WIN to a program

manager group as described in the next section.

4.3.3 Adding HSSM to a Program Manager Group

The HSSM-WIN program should be added to a Program Manager group so that HSSM-WIN can be

executed by clicking on its icon. Two procedures are given for this operation:

 With both the File Manager and Program Manager occupying different places on the screen as in Figure

11, simply drag the file name HSSM-WIN.EXE to the desired Program Manager group, where it will appear

as an icon. 

 Alternatively, you may use the "File" "New" command of Windows to specify a new program group and item.

For the program group:

Select the Program Group radio button

Click on the "OK" button

Enter HSSM as the Description

Click on the "OK" button

For the program item:

Select the Program Item radio button

Click on the "OK" button

Enter HSSM as the Description

Enter C:\HSSM\HSSM-WIN.EXE as the Command line

Enter C:\HSSM as the Working Directory

Click on the "OK" button
[Section 4 The MS-Windows Interface] 22

Figure 11 Installing HSSM-WIN in a Program Manager group

Once HSSM-WIN has been successfully loaded onto your system, you must check the CONFIG.SYS file.

The HSSM-KO program opens a number of temporary files and CONFIG.SYS must be configured so that a

sufficient number of files may be opened. The CONFIG.SYS on your system needs to include the line

FILES = 30

(A number greater than thirty will also work.) After modifying CONFIG.SYS you must reboot your system to

allow the change to take effect. Installation of both the Windows and DOS interfaces on one computer is

discussed in Appendix 9.

4.4 Using HSSM-WIN

4.4.1 Starting Up

Like other Windows applications, HSSM-WIN will appear in a Program Manager group as an icon, and

can be started simply by double clicking with the mouse cursor on the icon.

HSSM-WIN can also be started from Windows' File Manager by double-clicking on the file named

HSSM-WIN.EXE with the mouse pointer. If you do not have a mouse, choose "Run..." from the "File" menu

(ALT+F followed by R) and enter "C:\HSSM\HSSM-WIN.EXE" in the prompt box. The screen will clear and the

main window of HSSM-WIN will appear. 
23 [Section 4 The MS-Windows Interface]

Figure 12 The initial HSSM-WIN screen

A variety of menu options appears

in the menu bar along the top of the

HSSM-WIN window (Figure 12). These

menu options are headings for related

operations which will appear in a pulldown menu below each menu item.

For more information on using the

standard Windows interface consult

your Windows documentation.

When HSSM-WIN first appears on

the screen, some menu items are

written in a different color, or disabled.

This means that those commands are

not available at this time, since no data

nor parameters have yet been loaded into the program. For example, the Save and Graph commands are

disabled since no data yet exist to save or graph. The available options include File Open and Edit, to open an

existing input file or edit one from scratch. Once data have been loaded, all of the menu options become

available.

4.4.2 Menu Command Summary

Table 7 contains a listing of all HSSM-WIN commands. Every HSSM-WIN command is either

 a menu option of the main menu bar (column headings 1 to 6 of Table 7, see Figure 12), 

 listed in a pull-down menu (entries in columns 1 to 6 of Table 7), or 

 listed in the system menu (entries in column 7 of Table 7). 

(The system menu is accessed by clicking on the icon in the upper left corner of the window or by pressing

ALT + SPACEBAR on the keyboard). Some of the commands are followed by an ellipsis (...), which means that

more information is requested before executing. A menu item in HSSM-WIN may have one letter underlined,

or it may be followed by an accelerator (such as "Graph Results Ctrl+G"). These are shortcut codes for the

keyboard. The user who is familiar with the program may find that the keyboard is often faster than the mouse.

 A description of each command is presented in Section 4.10 
[Section 4 The MS-Windows Interface] 24

Table 7 HSSM-WIN Command Summary

File Edit Model Graph Window Help System 

(1) (2) (3) (4) (5) (6) Menu

(7)

(a) New General Run Graph Cascade Read Help Restore

Data... HSSM-KO Results... File

(b) Open... Hydrologic Run HSSM-T Copy Tile About HSSM... Size

Data... Graph

(c) Save Hydrocarbon Run Print Arrange About Move

Phase Data... REBUILD Graph Icons HSSM-WIN..

(d) Save Model Close Close All Minimize

as ... Simulation Graph

Data...

(e) T Check Fonts (list of Maximize

File times graphs)

(f) Exit Close

HSSM-WIN

(g) Switch

to...
25 [Section 4 The MS-Windows Interface]

4.5 Use of HSSM-WIN Commands for Performing HSSM Simulations

The following sections give the specific procedures for running HSSM Simulations using HSSM-WIN

commands. HSSM-WIN menu options are referred to by the column number and row letter in Table 7. For

example, the Open option of menu bar item File is designated 1.b.

4.5.1 Creating New Input Data Sets

 Clear any existing data and file names by selecting "New" from the "File" menu (1.a). This step

can be skipped if no files have been used previously in the current HSSM-WIN session. 

 Call the Input File Editor by choosing "Edit" (2) from the HSSM-WIN menu (or use the accelerator

Ctrl+E).

 Enter data in each of the four Input File Editors (2.a through 2.d) as described in the Sections 4.6.3 to

4.6.6, and click on "OK" (ENTER) to exit the editor.

 Save the file with the "Save" command from the "File" menu (1.c). When asked for a new file name,

enter a name of up to eight characters. There is no need to add the .DAT extension, as HSSM-WIN

will do this. 

4.5.2 Editing Existing Input Data Sets

 Open an existing input file for editing by following the procedure given below:

Choose the "Open..." option from the "File" menu (1.b). The Open Files dialog box will 

list the relevant file names in the default directory, as shown in Figure 13.

Figure 13 File Open dialog box

 Scroll through the list of names using the scroll bar with the mouse.

If the name of the desired file is listed here, double-click on the name to open it. (With 

the keyboard, type the name in the box and choose ENTER to open the file. If you decide not to
[Section 4 The MS-Windows Interface] 26

open a file, choose ESC to cancel.)

 Call the Input File Editor by choosing "Edit" (2) from the HSSM-WIN menu (or use the accelerator

Ctrl+E).

 Enter data in each of the four Input File Editors (2.a through 2.d) as described in the Sections 4.6.3 to

4.6.6, and click on "OK" (ENTER) to exit the editor.

 Save the file. 

9 If you want to overwrite the original file, simply choose the "Save" option from the "File"

menu (1.c).

9 If you want to select a new name with the "SaveAs" command from the HSSM-WIN "File"

menu (1.d). When asked for a new file name, enter a name of up to eight characters. There

is no need to add the .DAT extension, as HSSM-WIN will do this. 

Figure 14 File Save As dialog box

4.5.3 Running the Model

Choose "Model" (3) to perform the two parts of the HSSM calculations. 

 HSSM-KO is executed by selecting "Run HSSM-KO " (3.a). HSSM-KO reads the entire input

data file and performs the KOPT and OILENS simulations. HSSM-KO then produces a separate

input data file for HSSM-T, which contains some of the HSSM-KO input data and some of the

HSSM-KO results that are needed by HSSM-T. 

 After the successful completion of HSSM-KO, the second step is to run HSSM-T, by selecting

"Run HSSM-T" (3.b). These two programs are DOS programs, so Windows must create DOS

processes in order to run these codes. Section 4.7 shows the screen messages produced when

HSSM-KO and HSSM-T are executed. 

NOTE: If the parameters for TSGPLUME (HSSM-T) need to be changed after HSSM-KO has been

executed, the data set must be edited and HSSM-KO must be run again.

 
27 [Section 4 The MS-Windows Interface]

4.5.4 Graphing the Model Results

 To generate graphs of the data, choose "Graph" (4) and "Graph Results..." (4.a) to get the Display

Graphs dialog box (Figure 15).

Figure 15 Display Graphs dialog box

 Choose which graphs to make by clicking on the check boxes. An "X" in the box means that it has

been selected. To do this from the keyboard, press the TAB key to move the highlight to the desired

checkbox and SPACEBAR to turn the check on or off.

 Choose "OK" to draw the graphs.

 To close a graph, choose "Close" from the graph window's system menu, or (4.d) double-click with

the mouse on the system menu icon in the upper left corner of the graph window. Closing

unneeded graphs makes more room in memory for other graphs or programs.

4.5.5 Graphing Results From a Previous Simulation

 Load the data set by selecting "Open" from the "File" menu (1.b). 

 To generate graphs of the data, choose "Graph" (4) and "Graph Results..." (4.a) to get the graph

dialog box. 

 Choose which graphs to make by clicking on the check boxes. An "X" in the box means that it has

been selected. To do this from the keyboard, press the TAB key to move the highlight to the desired

checkbox and SPACEBAR to turn the check on or off.

 Choose "OK" to draw the graphs.

 To close a graph, choose "Close" from the graph window's system menu, or (4.d) double-click

with the mouse on the system menu icon in the upper left corner of the graph window. Closing

unneeded graphs makes more room in memory for other graphs or programs.
[Section 4 The MS-Windows Interface] 28

4.5.6 Printing a Graph

 Generate a graph as described above.

 From the "Graph" menu, choose the "Print Graph" (4.c) option.

 After a few seconds, a message reading "Sending graph to print manager" will appear, with the option

to cancel the print job. Unless the job is to be canceled, wait until the message disappears. This

means that the image has been sent on its way, and HSSM-WIN is ready to continue.

NOTE: Small graphs will print relatively quickly, but larger images will take longer. A full-page graph

may take several minutes, depending on the sophistication of the printer and printer driver software

and on availability of free memory and hard disk space.

4.5.7 Comparing Several Simulations

 Edit or create an input file, run the simulation, and graph the results. If the simulations have already

been run and the plot files exist, then load the file name with "Open" and "File" (1.b), and choose

the "Graph" command to display the graphs (4.a). Using the Minimize command, reduce each of

the graphs to an icon. The icons will be displayed along the bottom of the HSSM-WIN window. Do

this for the simulations you wish to compare.

 Restore the graphs which you wish to compare by either double-clicking on the icon or selecting from

the graphs listed in the "Window" pull-down menu (5.e). You may choose as many graphs as you

wish.

 Use the "Tile" command under the "Window" menu (5.b) to redraw the graphs as in Figure 16.

 If you desire, the graph windows may be resized to match scales by "dragging" the corners or sides

with the mouse or by using the Move and Size commands from the graph window's system menu

(7.c and 7.d).

 To view the parameter values for a particular run, open the file in question and view the data using the

Input File Editors (2.a through 2.d).
29 [Section 4 The MS-Windows Interface]

Figure 16 Comparison of Graphs from Two Different Simulations

NOTE: Each graph on the screen consumes up to a few KB of memory which are freed on closing the

graph window. With several graphs and/or other applications running, HSSM-WIN or Windows may

determine that there is not enough free memory or resources to create another graph. In this case,

the user will be asked to terminate something to create more room in memory.

4.5.8 Copying a Graph to the Clipboard

Windows programs have the ability to transfer screen images directly from one Windows application to

another. For example, an HSSM-WIN graph can be copied into a word processor document. The Windows

Clipboard is used as an intermediate storage point for such transfers.

 Generate a graph as described above.

 From the "Graph" menu (4), choose the "Copy Graph" option (4.b). This copies the graph to the

Clipboard in a bitmapped format and replaces any previous Clipboard data.

 To see the contents of the Clipboard at any time, run the Clipboard program.

 To paste the graph into another application, find the "Paste" command in that application's menu, if

available. It should be listed under the "Edit" pull-down menu. Figure 17 shows an HSSM-WIN

graph pasted into PAINTBRUSH.

 Bitmaps copied to the Clipboard can be saved as *.CLP files as well, so that graphs may be kept for

later use.
[Section 4 The MS-Windows Interface] 30

Figure 17 HSSM-WIN graph pasted into PAINTBRUSH

4.5.9 Exiting HSSM-WIN

HSSM-Win can be exited by selecting the "File" and "Exit HSSM-WIN" (1.f). The program may also

be exited by double-clicking on the system menu in the upper left corner (equivalent to selecting 7.f

). If any work has not been saved, HSSM-WIN will alert the user to save it before the program

closes down.

4.6 Editing and Creating HSSM Data Sets

The following sections describe all the required parameters for HSSM. The sections also provide

guidance on how to determine appropriate values of the parameters. For convenience, blank templates of

each of these screens are provided in Appendix 13. These templates are useful for assembling data sets and

may be copied for repeated use. Experienced users of the model may wish to edit their data sets directly;

Appendix 10 shows the structure of the HSSM-KO and HSSM-T input data files. 

4.6.1 Using the Input File Editors - Common Techniques

The following are instructions for using the Editor for the input data screens (called dialog boxes). Each

of the dialog boxes requires the usage of the features described below.
31 [Section 4 The MS-Windows Interface]

Figure 18 An example of a data entry error message

 The Input File Editor dialog boxes are HSSM-WIN's method of editing the input file for the models.

They are displayed by choosing the "Edit" and one of the data options from HSSM-WIN's menu.

This section discusses general techniques for navigating around and editing data in these dialog

boxes, that are illustrated in Figure 19 to Figure 22.

 Standard Windows methods for selecting and editing text are adopted by HSSM-WIN:

To select an entire word or numeric entry, simply double-click on the entry with the mouse or drag

the mouse (holding down the button) across the desired selection. Selected text appears in reverse

video. Any typing done now will replace the selected text. If you do not want to replace the text but

rather edit it, use the mouse or the arrow keys to position the cursor in the box. The DELETE key will

delete to the right of the cursor, and the BACKSPACE key to the left. 

 Move to the other text fields beside each parameter description with either the mouse or the TAB key.

(To move backwards, use SHIFT + TAB.) Edit the contents of each window as desired. 

 Radio buttons F are used to choose among mutually exclusive options which appear in various dialog

boxes. Depending on the choice made, some entry fields may be disabled or enabled as

appropriate. Radio buttons are chosen by either clicking with the mouse, or using the 8 and 9 keys

to move and the SPACEBAR to select.

 Check boxes G are used to enable or disable non-exclusive options. These are also selected with the

SPACEBAR.

 Accept the new values by choosing the "OK"

pushbutton (ENTER). "Cancel" (ESC) will

abandon any changes made. 

The Hydrologic Parameters, Hydrocarbon

Phase Parameters and Simulation

Parameters dialog boxes contain a check box

titled "Enable range checking." This box is

normally checked and causes HSSM-WIN to

check each parameter to assure that it is within allowable limits. Each field will be tested for illegal

characters or out-of-range values, in which case an error message will appear as in Figure 18.

After acknowledging this message with "OK," the user will have the opportunity to edit the offending

field where HSSM-WIN has moved the prompt. Disabling the range checking option causes HSSMWIN not to check the parameter values. 

 After exiting the editing dialog box, the changes are in HSSM-WIN's memory, but they are not yet

saved to a file. Use the "Save" or "SaveAs" commands to save them.

NOTE: To view the underlying graphs while assigning values to the parameters, the Editing window (like

any other) can be almost entirely moved off the screen by dragging its title bar. 

4.6.2 Required Units for HSSM Simulations

The following units are used in HSSM and are listed with their usage and abbreviation. Care must be

taken to assure that all input parameters are converted to this set of units. As a reminder, the required units

are listed with each parameter discussed below.
[Section 4 The MS-Windows Interface] 32

Table 8 Required Units for HSSM Simulations

Quantity Unit

Time day

Depth meter

Dynamic Viscosity centipoise

Density grams/cubic centimeter

Surface Tension dyne/centimeter

Concentration milligrams/liter

Soil-Water Partition liters/kilogram

Coefficient

Dispersivity meters

Various dimensionless

4.6.3 General Model Parameters

The General Parameters dialog box (Figure 19) contains titles, printing switches, module switches,

and file names.
33 [Section 4 The MS-Windows Interface]

Figure 19 General Parameters dialog box

Run Titles

A three-line run title is used by HSSM-WIN. These text strings are included in all of the output and

plot files. The first line is also used as a graph title. If the graph is too small to plot, the graph

window contains only the three title lines.

Printing switches

G Create output files

If this switch is chosen, output files will be generated by the models. The normal situation is

to choose this option.

F Echo print data only

F Run Models

This switch tells the model either to run and create plot files, or only to echo the input data.

Echo printing, to check the input file, is recommended before making the simulation run.

Module switches

G Run KOPT

Run the KOPT module of HSSM-KO. KOPT simulates the infiltration of the NAPL through the

vadose zone. KOPT must be run in order to run OILENS or TSGPLUME.
[Section 4 The MS-Windows Interface] 34

Figure 20 Hydrologic Parameters dialog box

G Run OILENS

Run the OILENS module of HSSM-KO, to simulate the motion and dissolution of the

hydrocarbon lens at the water table. OILENS requires that KOPT also be run.

G Write TSGPLUME input file

Write the TSGPLUME (HSSM-T) input data file when the HSSM-KO program is run. This

option must be selected if HSSM-T is to be run. HSSM-T, which simulates transport of

the chemical constituent in the aquifer, is run using the "Run HSSM-T" command, only

after HSSM-KO has run.

File names

HSSM requires the use of a specific set of files for producing output and plot files. These names

can not be edited, but are included for the user's information as they will appear in the indicated

directory after running the model. The names change automatically whenever the file is saved

under a new name. The names and purposes of the files are listed in section 4.7.

4.6.4 Hydrologic and Hydraulic Data

The Hydrologic Parameters dialog box (Figure 20) lists hydrologic and hydraulic data for the

model.
Kew ' Ksw krw

35 [Section 4 The MS-Windows Interface]

(1)

HYDROLOGIC PROPERTIES

Water dynamic viscosity, μ (cp) w

Enter the dynamic viscosity of water in centipoise (cp). At 20EC the viscosity of pure water is 1.0 cp.

Water density, Dw (g/cm )3

Enter the density of water in g/cm . At 20EC the density of pure water is 1 g/cm . 3 3

Water surface tension, F (dyne/cm) aw

Enter the water/air surface tension in dyne/cm. At 20EC the surface tension of pure water is 72.8

dyne/cm. A lower value, say 65 dyne/cm, may be appropriate for soils and/or contaminated sites.

Maximum relative permeability to water, k , during infiltration rw(max)

Enter the maximum water relative permeability during infiltration. Since air is normally trapped

during infiltration, the effective hydraulic conductivity of the soil will be less than the saturated

conductivity. The relationship between effective conductivity to water, K , and saturated conductivity ew

to water, K is given by sw

where k is called rw the relative permeability to water. The relative permeability equals zero

when the saturation is at or below residual, and equals one when the porous medium is

completely saturated with water.

To account for trapping of the air phase, the maximum effective conductivity is restricted by the

value set for k . Typical values range rw(max) from 0.4 to 0.6 (Bouwer 1966); 0.5 is often used

(e.g., Brakensiek et al., 1981). The maximum water saturation is then determined from the

k function that is used by HSSM. The remainder of the pore space is assumed to be filled rw

with trapped air. The water saturation calculated from k is rw(max) then discarded, as only the

trapped air saturation is used by the model.

Recharge

Check the type of recharge condition desired. Recharge can as either by specifying a recharge rate

or as a vadose zone residual water saturation. 

F Average annual recharge rate, q (m/d) w

Choose this option to specify a recharge flux.

F Saturation, Sw(max)

Choose this option to specify a constant water saturation in the pore space. 
2.74 × 10&4 m

d ' 10 cmyr

m

100 cm

yr

365 d

[Section 4 The MS-Windows Interface] 36

(2)

When annual recharge is chosen for the recharge input:

The value entered is the average annual recharge rate. For example, with an annual recharge

rate of 10 cm/yr the value entered is:

HSSM-KO calculates the water saturation (fraction of the pore space that is filled

with water) from the recharge rate. Large recharge rates may cause the available

pore space to be completely filled with water, allowing no NAPL to infiltrate. If

such conditions are encountered an error message is written to the screen.

When saturation is chosen for the recharge input:

If 35% of the pore space is filled by water, then 0.35 is entered here. Using the

other set of units: if the volumetric moisture content is 0.14 and the porosity is 0.40,

then the equivalent saturation of 0.35 is entered here.

Typically the moisture content at or above the field capacity would be used here,

after converting to saturation. The relationship between volumetric moisture

content, 2w w ww , porosity, 0, and saturation, S , is given by 2 = 0S . From the

saturation input, HSSM-KO calculates the associated water flux.

Capillary Pressure Curve Model

F Brooks and Corey

F van Genuchten

Choose the capillary pressure model to be used in HSSM calculations. Further information on the

selection of the model parameters is given in Appendix 3.1 "Soil Properties." Either Brooks and

Corey or van Genuchten model parameters may be used. The appendix contains typical parameter

values for each of these models. Although the HSSM is designed to use the Brooks and Corey

model, van Genuchten model parameters may be entered as input. The van Genuchten model

parameters are converted to approximately equivalent Brooks and Corey model parameters by a

procedure developed by Lenhard et al. (1989). Only the parameters highlighted for the chosen

model need be entered.
Sw&Swr

1&Swr

' hce

hc

8

2w & 2wr

2m & 2wr

' 1

1 % (" hc )

n m

37 [Section 4 The MS-Windows Interface]

(3)

(4)

For the Brooks and Corey Model:

The Brooks and Corey (1964) model equation which describes the relationship between

saturation S and capillary head h is w c given by

where the residual water saturation, S , the air entry head, h , and the pore size distribution index, wr ce

8, are fitting parameters.

Brooks & Corey's 8

The parameter 8 is called the pore size distribution index, and is determined by either fitting the

Brooks and Corey model to the water/air capillary pressure curve P (S ) by a procedure outlined by c w

Brooks and Corey (1964), or by non-linear curve fitting (e.g., van Genuchten et al., 1991).

Brooks & Corey's Air entry head, h (m) ce

Enter the absolute value of the air entry head in meters. This value is determined as a parameter

from the water/air capillary pressure curve (see item on Brooks and Corey's 8, above.)

Residual water saturation, S wr

Enter the residual water saturation, which is determined from the measured capillary pressure curve

(see item on Brooks and Corey's 8, above.)

For the van Genuchten Model:

NOTE: selecting the van Genuchten model causes HSSM to calculate approximately

equivalent Brooks and Corey model parameters as described in Appendix 4.

van Genuchten's model is defined by

where

2 = volumetric water content w
Sw & Swr

1 & Swr

[Section 4 The MS-Windows Interface] 38

(5)

h = capillary head with units of m c

2 = volumetric residual water content wr

2m = volumetric maximum water content

" = a parameter with units of m-1

n = a parameter

 m = a parameter (taken as a simple function of n)

For HSSM the reduced water content term (the left hand side of van Genuchten's model)

is taken to be equal to 

where the maximum water saturation, 2m, has been equated with the porosity. The parameters

of van Genuchten's model can be fitted to measured data by using a fitting program like RETC

(van Genuchten et al., 1991).

Residual water saturation, S wr

Enter the residual water saturation, which is determined from the measured capillary pressure curve.

van Genuchten's "

Enter the value of van Genuchten's parameter " in units of m . -1

van Genuchten's n

Enter the value of van Genuchten's parameter n.

POROUS MEDIUM PROPERTIES

Saturated vertical hydraulic conductivity, K (m/d) s

Enter the value of the saturated vertical water phase hydraulic conductivity, K , in meters per day. s

Saturated hydraulic conductivity is one of the most important parameters of the model. Estimation

of this parameter is described in Appendix 3.1 "Soil Properties." This appendix contains data from

two tabulations of soil properties. 
Db ' Ds (1 & 0)

39 [Section 4 The MS-Windows Interface]

(6)

Ratio of horizontal to vertical hydraulic conductivity

Enter the ratio of the horizontal saturated water phase conductivity to the saturated vertical water

phase hydraulic conductivity. Anisotropy is not treated directly in HSSM, rather the model uses the

product of the ratio RKS and the saturated vertical conductivity, K , to s determine the hydraulic

conductivity of the aquifer. This later conductivity is also used for determining the effective

conductivity to the NAPL for the lens spreading. The relationships between the conductivities are

summarized in Table 9.

Table 9 Summary of Hydraulic Conductivity Relationships

Model and Region Hydraulic Conductivity HSSM Variables

Used 

Vadose zone (KOPT) Vertical Ks

NAPL lens (OILENS) Horizontal K *RKS s

Aquifer (TSGPLUME) Horizontal K *RKS s

Porosity, 0

Enter the porosity, 0, of the aquifer.

Bulk density, D (g/cm ) b

3

Enter the bulk density of the soil in g/cm . Porosity, 0, and bulk density, D are related by 3

b 

where Ds is the solids density. The density of quartz is approximately 2.65 g/cm . The values 3

for porosity and bulk density must be related by equation (6).

Aquifer saturated thickness (m)

Enter the saturated thickness of the aquifer in meters.

Depth to water table (m)

Enter the depth to the water table from the release point in meters. The release point is usually at

the ground surface.
capillary

thickness

parameter

' smear zone thickness × residual NAPL saturation

maximum NAPL saturation in lens

DL ' AL v

DT ' AT v

DV ' AV v

[Section 4 The MS-Windows Interface] 40

(7)

(8)

Capillary thickness parameter (m)

The capillary thickness parameter gives the model a thickness which must build up in the capillary

fringe before spreading of the NAPL occurs. Typically, a value of 0.01m should be entered for this

parameter. This results in a small thickness of NAPL that is built up before spreading begins. 

The capillary thickness parameter can also be used to incorporate the effect of water table

fluctuation on the lens radius. Water table fluctuation can cause trapping of NAPL throughout a

smear zone, and the trapped NAPL is not available for radial spreading. To include this effect, the

capillary thickness parameter should be calculated by

The smear zone thickness should be taken as the maximum water table fluctuation. The residual

NAPL saturation and maximum NAPL saturation in the lens are described under the Hydrocarbon

Phase Data dialog box (Section 4.6.5).

Ground water gradient (m/m)

Enter the ground water gradient. Typical maximum natural gradients range from 0.005 to 0.02.

Since pumping wells are not allowed in TSGPLUME, natural gradients should be used here.

Aquifer Dispersivities A , A , A (m): Longitudinal, Horizontal Transverse, Vertical Transverse. LTV

Enter the longitudinal, horizontal transverse and vertical transverse dispersivities in meters. 

The dispersivities are defined by

where D , D , and D are the longitudinal, horizontal transverse, and vertical transverse dispersion LT V

coefficients; A , A , and A are likewise the longitudinal, hor LT V izontal transverse, and vertical transverse

dispersivities; and v is the seepage velocity in the mean flow direction.

Dispersive mixing in aquifers results from solute transport through heterogeneous porous media.

As the contaminant plume spreads it "experiences" more heterogeneity and the apparent dispersion

coefficient increases. Thus the dispersion coefficients, D , D and D are not fundamental LT V

parameters, but exhibit scale dependence.

Gelhar et al. (1992) recently reviewed dispersivities determined at 59 sites and considered the

reliability of the dispersion coefficients. They concluded that there are no highly reliable longitudinal

dispersion coefficients at scales greater than 300m. Notably, at a given scale, dispersivities have

been found to vary by 2 to 3 orders of magnitude, although the lower values are more reliable.
41 [Section 4 The MS-Windows Interface]

Figure 21 Hydrocarbon Phase Parameters dialog box

Based on these data, horizontal transverse dispersivities are typically from 1/3 to almost 3 orders-ofmagnitude lower than longitudinal dispersivities. Vertical transverse dispersivities are typically

(although based on a very limited data set) 1-2 orders-of-magnitude lower than horizontal transverse

dispersivities. The very low values of vertical transverse dispersivities reflect roughly horizontal

stratification of sedimentary materials. 

4.6.5 Hydrocarbon (NAPL) Phase Data

The Hydrocarbon (NAPL) Phase Parameters dialog box (Figure 21) contains data concerning the

nature of the spilled hydrocarbon and one constituent of interest.

HYDROCARBON PHASE PROPERTIES

NAPL density, D (g/cm ) o

3

Enter the NAPL phase density in g/cm . For OILENS simulations, the NAPL density must be less 3

than that of water. Densities greater than water may be used if no OILENS simulation is performed.

Some typical NAPL densities are given in Table 10.
EAPI ' 141.5

sp.gr.

& 131.5

Kso ' Ksw

μw

μo

Do

Dw

[Section 4 The MS-Windows Interface] 42

(9)

(10)

Hydrocarbon densities are sometimes expressed by the degrees API (Perry and Chilton, 1973) scale

adopted by the American Petroleum Institute. Degrees API is defined by

where sp.gr. is the specific of the NAPL measured at 70E F divided by the specific gravity of water

measured at 60E F. The degrees API scale runs from 0.0 to 100.0 and covers a range of specific

gravities from 1.076 to 0.6112.

NAPL dynamic viscosity, μ (cp) o

Enter the NAPL phase viscosity in centipoise. Typical NAPL viscosities are given in Table 10.

The densities and viscosities of the NAPL and water phases are used by HSSM-KO to estimate the

saturated hydraulic conductivity to the NAPL phase, K , by so

where K is the saturated hydraulic conductivity to water, μ and μ are the water and oil viscosities, sw w o

and D and D are the respective densities. w o

 Table 10 NAPL Densities and Viscosities at 20EC

Liquid Density Viscosity

g/cm Cp 3

Methylene Chloride 1.33 0.426

TCE 1.47 0.566

PCE 1.60 0.900

Gasoline 0.75 0.45

Carbon Tetrachloride 1.59 0.970

Water 1.00 1.00

No. 2 Fuel Oil 0.87 5.9

Transmission Fluid 0.89 80

Aroclor 1254 1.51 2050
43 [Section 4 The MS-Windows Interface]

Hydrocarbon (NAPL) solubility (mg/L)

Enter the NAPL water solubility in mg/L. This coefficient represents the solubility of all of the NAPL

constituents, except the chemical constituent that is simulated. The solubility of the chemical

constituent is entered separately. Further, this value is only used by the model in a substantial way

if one particular ending criterion is used. Therefore the value of the NAPL solubility is not a critical

parameter. 

The value of NAPL solubility must be greater than zero if the OILENS Simulation ending criterion

(see below) is set to  "NAPL lens spreading stops." Bauman (1989) estimated that the typical

solubility of gasoline is on the order of 50 to 200 mg/L. 

Aquifer residual NAPL saturation, Sors

Enter the residual NAPL phase saturation in the aquifer. See notes below for the vadose zone

residual NAPL saturation.

Vadose zone residual NAPL saturation, Sorv

Enter the residual NAPL phase saturation for the vadose zone. By definition, the NAPL phase does

not flow at saturations less than or equal to residual. In this model, the residual NAPL saturation

is assumed to be a known constant. Ideally, this would be obtained by measuring the NAPL/air

capillary pressure curve in the presence of the amount of water filling a portion of the pore space.

Treating the residual NAPL saturation as a constant is acknowledged to be an assumption, as in

actuality the NAPL residual saturation may vary with the hydraulic gradient and with time as the

NAPL weathers (Wilson and Conrad, 1984.) Typically the residual NAPL saturation in the vadose

zone is less than that for the aquifer (with the same media properties). Typical hydrocarbon residual

saturations vary from 0.10 to 0.20 in the vadose zone, and from 0.15 to 0.50 in the saturated zone

(Mercer and Cohen, 1990). These values correspond more closely to "specific retention", as the

term is used in ground water hydrology, rather than true residuals at large capillary pressure values.

Soil/water partition coefficient (L/kg)

Enter the linear equilibrium partitioning coefficient between the soil and the water phase

concentrations (c and c ) of the hydrocarbon phase. Like the solubility of the NAPL phase, listed s w

above, this parameter is not critical. This coefficient is used for estimating the partitioning of the

dissolved fractions of the NAPL (i.e., all of the NAPL chemicals except the chemical constituent of

interest). For further information on partitioning see the discussion below for the constituent

soil/water partition coefficient.

NAPL surface tension, F (dyne/cm) ao

Enter the NAPL surface tension in dyne/cm. Table 11 shows typical surface tension values for

several petroleum products
Cb ' fb Dg

Cb (g/cm 3 ) ' 1.14%

100 (0.73 g/cm 3

) ' 0.0083g/cm 3

[Section 4 The MS-Windows Interface] 44

(11)

(12)

Table 11 Surface tensions of several fuels

(Wu and Hottel, 1991)

Liquid Surface tension

(dyne/cm)

gasoline 26

kerosene 25-30

gas oil 25-30

lubricating fractions 34

fuel oils 29-32

DISSOLVED CONSTITUENT PROPERTIES

G Dissolved constituent exists

Check this box if calculations are to be performed for a dissolved constituent. Normally, for full

HSSM transport simulation to a receptor point this will be checked.

Initial constituent concentration in the NAPL, c (mg/L) o(ini)

Enter the initial concentration of dissolved chemical in the NAPL phase in mg/L. HSSM idealizes

the multiphase/multicomponent system as consisting of a NAPL phase that contains some small

fraction of a dissolved constituent. The dissolved constituent can partition between the fluids and

the solid. The concentration of the chemical in the NAPL is entered here. For example, benzene

composes 1.14% by mass of the idealized gasoline mixture used by Baehr & Corapcioglu (1987).

The initial benzene (the chemical constituent) concentration in gasoline (the NAPL or "oil") is given

by

where C is the concentration of benzene in the gasoline, f is the mass fraction of benzene b b

in gasoline, Dg is the density of the gasoline. Therefore

Converting the gasoline concentration to the required units gives
Cb (mg/L ) ' Cb (g/cm 3 ) 1000 cm 3

L

1000 mg

g ' 8300mg/L

co ' Ko cw

cs ' Kd cw

Kd ' f

o c Ko c

45 [Section 4 The MS-Windows Interface]

(13)

(14)

(15)

(16)

NAPL/water partition coefficient, Ko

Enter the linear equilibrium partitioning coefficient between the NAPL and the water phase

concentrations of the chemical constituent. By definition

where K is the dimensionless partition coefficient between the NAPL phase (c ) and water phase o o

(c ) concentrations of the chemical constituent. The partitioning between the NAPL phase and the w

water phase depends on the composition of the NAPL. Estimation of K is discussed in Appendix o

3.2 "NAPL/Water Partition Coefficient." A utility program for performing the necessary calculations,

called RAOULT, is described in Appendix 6.

Soil/water partition coefficient, K (L/kg) d

Enter the linear equilibrium partitioning coefficient in liters per kilogram between the soil and the

water phase concentrations (c and c ) of the constituent. By definition s w

where K is the partition coefficient in liters per d kilogram between the solid (c ) and water phase s 

concentrations (c ). K is commonly estimated from the fraction organic carbon of the media, f , w d oc

and the organic carbon partition coefficient, K as oc

(44) in Appendix 3 lists K values for several hydrocarbons. oc

Constituent solubility, s (mg/L) k

Enter the chemical constituent water solubility in mg/L. The solubility entered here is the "pure

component" solubility which is tabulated in several sources (i.e., Mercer et al., 1990; Sims et al.,

1991; USEPA, 1990). Several values are given in Table 98. The solubility is used by HSSM to limit

the water phase concentration. Appropriately chosen K o values (which imply maximum water phase

concentrations much less than the pure phase solubilities) make this parameter redundant for

NAPLs composed of mixtures of chemicals.
[Section 4 The MS-Windows Interface] 46

G Constituent half-life in aquifer (d)

Enter the half-life of the constituent in the aquifer and check the box. If the box is not checked,

HSSM-WIN passes a very large value to the model, causing there to be no decay in the TSGPLUME

model. This value is used only by the TSGPLUME model.

HYDROCARBON (NAPL) RELEASE

The Hydrocarbon Release box defines, in part, the boundary condition for the simulation. Four

options are provided for specifying the way in which the NAPL enters the subsurface. Not all of the

release parameters are needed for each release option; the necessary parameters for the selected

option are highlighted by HSSM-WIN for entry of the specific values.

Release Options

F Specified flux

Specifies a constant flux of NAPL, corresponding to a known rate of application of NAPL to the

ground surface for a specified time interval. Excess NAPL is assumed to run off at the surface.

F Specified volume/area

Specifies a volume per unit area of NAPL applied over a certain depth. This results in a fixed

volume applied instantaneously, corresponding to a land treatment system or a landfill.

F Constant head ponding

Specifies constant head ponding for a specified duration. The ponding depth abruptly goes

to zero at the end of the release. This condition is used to simulate a hydrocarbon tank rupture

which is contained within a berm, for example.

F Variable ponding after a period of constant head ponding

Specifies constant head ponding for a specified duration, followed by a gradual decrease to

zero head as the NAPL infiltrates.

Release Parameters

NAPL flux, q (m/d) o

Enter the constant NAPL flux in meters per day. NAPL phase fluxes in excess of the maximum

effective oil phase conductivity are assumed to run off.

Beginning time (d)

Enter the beginning time of the NAPL release in days. Usually this is zero.

Ending time (d)

Enter the ending time of the NAPL release in days or the ending time of constant head

ponding.
47 [Section 4 The MS-Windows Interface]

Figure 22 Model Simulation Data dialog box

Ponding depth, H (m) s

Enter the depth of constant head ponding in meters.

Oil volume/area (m /m ) or (m) 3 2

Enter the volume of the NAPL phase per unit surface area that is placed in either a land

treatment facility or a landfill.

Lower depth of NAPL zone (m)

Enter the depth of the bottom of the contaminated zone in meters.

4.6.6 Model Simulation Data

The Model Simulation Parameters dialog box (Figure 22) contains data controlling the simulations, such

as beginning and ending times, numbers and locations of wells, etc.
[Section 4 The MS-Windows Interface] 48

SIMULATION CONTROL PARAMETERS

Radius of oil lens source, R (m) s

Enter the radius of the contaminant source in meters. When no OILENS simulation is desired (Run

OILENS is not selected on the General Model Parameters dialog box), a per unit area simulation

can be performed by entering 0.5642 as the radius of the source. The resulting source area is 1.0

m .2

Radius multiplication factor

A value of 1.001 is suggested for the radius multiplication factor (RMF). The RMF is used to multiply

the source radius for starting the OILENS model. This is necessary since the OILENS equations are

singular at the source radius. Starting the simulation at a small distance from the true radius avoids

this singularity. This procedure does, however, introduce a mass balance error into the solution, so

the minimum value of RMF which permits the simulation to proceed should be used. At no time

should the RMF exceed 1.1. When the singularity is encountered, the OILENS model will display

the error message

OILENS SINGULARITY ENCOUNTERED, INCREASE RMF. 

The RMF should then be increased, and the simulation retried.

Maximum NAPL saturation in the NAPL lens, So(max)

Enter the saturation of the NAPL phase in the lens. In HSSM, the lens is idealized as a uniformly

saturated lens, although in actuality the NAPL saturation varies within the lens. The thickness of the

lens in HSSM represents the ratio of the volume of the lens to its area. Estimation of the NAPL lens

saturation is discussed in Appendix 3.3, and a utility called NTHICK for performing the necessary

calculation is described in Appendix 7.

Simulation ending time (d)

Enter the simulation ending time in days. This must always be specified, even though other stopping

options are available and may override the maximum simulation time.

Maximum solution time step (d)

Enter the maximum solution time step in days. This should be set as high as possible, although

internal error correction routines will often limit the actual size of the step taken. Values of up to 25

days are usually acceptable. Overly large step sizes may introduce mass balance errors in the

model results.

Minimum time between printed time steps and mass balance checks (d)

Enter the minimum time between printed time steps in days. Although the model uses a variable

time step ordinary differential equation solver, at times during the simulation HSSM takes very small

steps. Results from these steps are of little use and dramatically increase the size of the output

files. This parameter prevents the output of every solution step and should be set to 0.1 or 0.25

days. This parameter does not affect the simulation itself, but only the information that is output.
49 [Section 4 The MS-Windows Interface]

 For most chemicals leaching out of the lens, after the peak mass flux into the aquifer has passed,

there is a relatively long period of time where the mass flux into the aquifer slowly declines. During

this time period, the user-set minimum time between printed time steps may be overridden in order

to reduce the size of the output and plot files. An additional criterion is added that the mass flux

must change by at least 1.0 percent for the results to be output. This feature cannot be overridden

by the user.

 

OILENS simulation ending criterion

The OILENS Simulation ending criterion determines how the HSSM-KO simulation terminates.

Because it is not possible to predict when certain events in the simulation will occur, several of the

options cause the simulation to end only after the event of interest has occurred. In these cases the

user-specified ending time is overridden and the simulation continues until the event occurs. 

NOTE: The fourth option, "Contaminant leached from lens" must be chosen in

order to use the HSSM-T model.

 User-specified time

Stop at the simulation ending time specified above.

 NAPL lens spreading stops

Stop the simulation when the NAPL lens stops spreading. If no NAPL lens forms before the

specified ending time, then the simulation stops at the specified ending time. If a lens does

form, the ending time is overridden and the simulation continues until the NAPL lens stops

spreading. When the NAPL phase solubility is near zero, it is possible that, in the model, the

lens motion may never stop, since kinematic theory predicts that an infinite amount of time is

required for all of the NAPL to pass a given depth. The NAPL trickles into the lens throughout

the simulation, and NAPL lens motion stops when the flux into the lens drops below the NAPL

dissolution flux into the aquifer. If the NAPL solubility is zero and no chemical constituent is

simulated, no NAPL is dissolved and the motion may continue indefinitely. To avoid this

problem, a non-zero NAPL solubility (see Hydrocarbon Phase Parameters) is required for this

situation.

 Maximum contaminant mass flux into aquifer

Stop the simulation when the maximum chemical constituent flux into the aquifer occurs. If

no NAPL lens forms before the specified ending time, the simulation stops at the specified

ending time. If a lens forms, the ending time is overridden and the simulation continues until

the maximum mass flux occurs.

 Contaminant leached from lens drops below a given fraction of the total mass in the lens

Stop the simulation when the contaminant mass in the NAPL lens drops below a specified

fraction of the maximum contaminant mass that has been contained within the lens during the

entire simulation. The fraction is specified by the user. If no NAPL lens forms before the userspecified ending time (above), the simulation stops at the specified ending time.

Fraction of mass remaining

Enter the mass factor stopping criterion for the above ending criterion  "Contaminant leached

from lens". Two percent (0.02) or less should be used for this factor.

TSGPLUME MODEL PARAMETERS
[Section 4 The MS-Windows Interface] 50

The following parameter values are used by the TSGPLUME model only.

Percent maximum contaminant radius (%)

Enter the percentage of the maximum contaminant radius which is to be used in the TSGPLUME

simulation, which requires a constant radius for the input mass flux. 

Since the radius of the NAPL lens changes continuously during part of the simulation, it may not be

possible to preselect an appropriate lens radius for the TSGPLUME module. It is desirable,

however, to match the radius of the lens to the peak mass flux into the aquifer. Thus TSGPLUME

simulation can use the radius which occurs at the time of the maximum mass flux. With this

approach the peak mass flux is not overly diluted due to a large lens radius. (Nor is it "condensed"

due to an overly small radius). The lens radius which occurs at the time of the maximum mass flux

is automatically selected if 101 is entered for the percent maximum contaminant radius. Thus, the

recommended value of this parameter is 101. It may be desirable for users to determine the effect

of varying the size of the source on the aquifer concentrations.

Minimum output concentration (mg/L)

Enter the minimum concentration (mg/L) for TSGPLUME to include in the output. Concentrations

below this value will be reported as zero. A nonzero value of this parameter is required for proper

execution of the TSGPLUME module. Typically, a concentration of 0.001 mg/L is suitable for the

minimum concentration. 

Beginning time (d)

Enter the beginning time in days for the TSGPLUME simulation. See note below.

Ending time (d)

Enter the ending time in days for the TSGPLUME simulation. See note below.

Time increment (d)

Enter the time increment in days for TSGPLUME output between the beginning and ending times

specified above. Typically 50 or 100 days is adequate for the time increment.

NOTE: Before running the model, it is not possible to guess precisely when the

contaminant arrives at or passes a given receptor point. HSSM-T will override the user

supplied beginning and ending times which allows the model to produce smooth concentration

histories at the receptor point. Particular effort is expended in HSSM-T to calculate when the

contaminant first arrives at the receptor point and when the peak concentration arrives. The

duration of mass flux into the aquifer is used to determine a proposed time increment for

HSSM-T output. If one hundredth of the mass flux input duration is greater than the user

specified time increment the user is prompted to increase the time increment:

*** TSGPLUME RECOMMENDS CHANGING THE TIME INCREMENT

*** FROM 0.5000 DAYS TO 98.60 DAYS

*** ACCEPT THE CHANGE ? (Y OR N)

HSSM-T is making the user an offer that shouldn't be refused, at least for an

initial simulation. If the resulting concentration history curve is not smooth enough, the user

may reduce the time increment for HSSM-T to produce a finer spacing in time.
51 [Section 4 The MS-Windows Interface]

If the user does not accept the change, he/she is prompted to decide between

the original time increment or to enter a new time increment.

NAPL LENS PROFILES

Number of profiles

Enter the number of KOPT saturation vs depth profiles (Saturation Profiles graph) and OILENS

lens thickness vs. radius profiles (NAPL Lens Profiles graph). Both are produced at the specified

times along with mass balance approximations. Up to ten profiles are allowed.

Time of profiles

Enter up to ten profile times in days. The number of entries will be automatically truncated to match

the value of Number of profiles above.

RECEPTOR LOCATIONS

These values are used by the TSGPLUME model only.

Number of wells

Enter the number of wells (a maximum of six) for which TSGPLUME is to calculate concentration

vs time for the Well Concentrations graph.

Locations of wells

Enter up to six well locations, as X and Y coordinates in meters. X is the directed along the

longitudinal axis of the plume (the direction of groundwater flow) and Y is directed transversely to

the X axis. The origin of the coordinate system is located at the center of the source (see Figure

9). The number of entries will be truncated depending on the value of Number of wells above.
[Section 4 The MS-Windows Interface] 52

4.7 Running the KOPT, OILENS and TSGPLUME Modules

This section describes the operation of the HSSM-KO and HSSM-T modules. These programs are the

heart of the simulation model. Both of the modules are DOS programs which are executed by selecting HSSMWIN menu items. Once an input data file has been created the HSSM-KO module is executed by selecting the

"Run HSSM-KO" menu item (3a on Table 7) Table 12 shows the first screen that appears when HSSM-KO is

executed. This screen identifies the model and the authors. Pressing return displays the disclaimer screen

(Table 13) . Carefully note the disclaimer messages. Sound scientific and engineering judgement is required

when applying models and the user is responsible for the application of the model.

 

 Table 12 Introductory HSSM-KO Screen

 ***************************************************

 * *

 * HSSM *

 * *

 * HYDROCARBON SPILL SCREENING MODEL *

 * *

 * INCLUDING THE KOPT, OILENS AND TSGPLUME MODELS *

 * *

 * JAMES W. WEAVER *

 * UNITED STATES ENVIRONMENTAL PROTECTION AGENCY *

 * R.S. KERR ENVIRONMENTAL RESEARCH LABORATORY *

 * ADA, OKLAHOMA 74820 *

 * *

 * INCLUDING OILENS--HYDROCARBON MOVEMENT ON THE *

 * WATER TABLE *

 * RANDALL CHARBENEAU, SUSAN SHULTZ, MIKE JOHNSON *

 * ENVIRONMENTAL AND WATER RESOURCES ENGINEERING *

 * THE UNIVERSITY OF TEXAS AT AUSTIN *

 * *

 * VERSION 1.00 *

 ***************************************************

Table 13 Disclaimer Screen

 ***************************************************

 * WARNING: *

 * THIS PROGRAM SIMULATES IDEALIZED BEHAVIOR OF *

 * OILY-PHASE CONTAMINANTS IN IDEALIZED POROUS *

 * MEDIA, AND IS NOT INTENDED FOR APPLICATION TO *

 * HETEROGENEOUS SITES. *

 * THE MODEL RESULTS HAVE NOT BEEN VERIFIED BY *

 * EITHER LAB OR FIELD STUDIES. *

 * READ USER GUIDE FOR FURTHER INFORMATION BEFORE *

 * ATTEMPTING TO USE THIS PROGRAM. *

 * NEITHER THE AUTHORS, THE UNIVERSITY OF TEXAS, *

 * NOR THE UNITED STATES GOVERNMENT ACCEPTS ANY *
53 [Section 4 The MS-Windows Interface]

A list of the file names used by HSSM-KO and HSSM-T is displayed in Table 14. 

Table 14 Output File Names and Run Options

OUTPUT AND PLOT FILE NAMES:

HSSM-KO INPUT DATA FILE BENZENE.DAT

HSSM-KO OUTPUT BENZENE.HSS

HSSM-KO PLOT 1 BENZENE.PL1 

HSSM-KO PLOT 2 BENZENE.PL2

HSSM-KO PLOT 3 BENZENE.PL3

HSSM-T INPUT DATA FILE BENZENE.PMI

HSSM-T OUTPUT BENZENE.TSG

HSSM-T PLOT BENZENE.PMP

TO RUN HSSM-KO ENTER <RETURN>

TO EXIT ENTER 1 

The names must follow a strict naming convention for the TSGPLUME module (HSSM-T) and the postprocessors to function properly. Table 15 gives the required file names. For the user's convenience the correct

file names are generated automatically by either of the interfaces. These should not be modified by the user.

 As summarized in Table 15, there are eight files associated with each simulation, all with the same prefix

(eight characters or fewer) but different extensions (three characters). *.DAT identifies a data file, which is

edited by HSSM-WIN or PRE-HSSM and read by the HSSM-KO program as an input file. The HSSM-KO

module generates up to five other files: *.HSS, *.PL1, *.PL2, *.PL3 and *.PMI. The plot files, *.PL1, *.PL2, and

*.PL3 contain data which HSSM-WIN or HSSM-PLT uses to generate graphs, and the output file, *.HSS,

contains neatly formatted and labelled data for reference. HSSM-KO optionally produces the *.PMI file, an

input file for the HSSM-T program. HSSM-T itself produces two similar files: *.PMP (a plot file), and *.TSG (a

formatted text file).
[Section 4 The MS-Windows Interface] 54

Table 15 Files Used by the HSSM interfaces

Extension Created by Used by Purpose

.DAT HSSM-WIN or HSSM-KO data input

PRE-HSSM

.PMI HSSM-KO HSSM-T data input

.HSS HSSM-KO the user text output

.TSG HSSM-T the user text output

.PL1 HSSM-KO HSSM-WIN or data for plotting

HSSM-PLT

.PL2 HSSM-KO HSSM-WIN or data for plotting

HSSM-PLT

.PL3 HSSM-KO HSSM-WIN or data for plotting

HSSM-PLT

.PMP HSSM-T HSSM-WIN or data for plotting

HSSM-PLT

As indicated in Table 14 the user may either run HSSM-KO or exit the program. Upon beginning a simulation

the model writes messages to the screen as the computations proceed. These allow the simulation to be

tracked by the user. Table 16 contains a typical set of screen messages for a simulation.
55 [Section 4 The MS-Windows Interface]

Table 16 Typical HSSM-KO Screen Messages

 *** DATA INPUT 

 *** DATA INITIALIZATION 

 *** SIMULATION BEGINNING 

 *** OIL INFILTRATION 

 *** OIL REDISTRIBUTION 

 *** CHEMICAL REACHES WATER TABLE 

 *** OIL LENS FORMS 

 *** PROFILING AT 15.00 DAYS 

 *** PROFILING AT 30.00 DAYS 

 *** PROFILING AT 90.00 DAYS 

 *** PROFILING AT 130.00 DAYS 

 *** PROFILING AT 175.00 DAYS 

 *** SIMULATION END 

 *** POST PROCESSING 

 *** CREATING OUTPUT FILE:

 *** BENZENE.HSS

 *** PROCESSING PLOT FILE CONTENTS

 *** REPACKING FILE 18

 *** REPACKING FILE 19

 *** CREATING KOPT/OILENS PLOT FILE:

 *** BENZENE.PL1

 *** CREATING KOPT/OILENS PLOT FILE:

 *** BENZENE.PL2

 *** CREATING KOPT/OILENS PLOT FILE:

 *** BENZENE.PL3

 *** CREATING TSGPLUME DATA FILE:

 *** BENZENE.PMI

 *** HSSM END 

Upon completing the HSSM-KO simulation, the DOS window remains open so that any error messages

stay on the screen. The window is closed by clicking on its system menu (upper left hand corner) and selecting

exit. 

The HSSM-T implementation of TSGPLUME is designed to be used with HSSM-KO. If the data set for

HSSM-KO has switches set appropriately, and if the dissolved chemical of interest reaches the water table

(either through the formation of a NAPL lens or by the leaching from an immobilized NAPL body in the vadose

zone), then an input data set for TSGPLUME is created by running HSSM-KO. The necessary flags and

conditions for TSGPLUME data file generation are summarized in Table 17. These parameters are described

in detail in the Section 4.6.6.
[Section 4 The MS-Windows Interface] 56

Table 17 HSSM-KO Data Switches for the Creation of TSGPLUME

 (HSSM-T) input Data Files

Condition or switch Dialog box Effect

: Create output files General Output and plot files produced

: Run KOPT General KOPT module is run

: Run OILENS General OILENS module is run

: Dissolved constituent exists Hydrocarbon Chemical constituent is included in the

Phase simulation.

: Write HSSM-T input file General Attempt to create the TSGPLUME

(HSSM-T.EXE) input data.

OILENS Simulation ending criterion Simulation End HSSM-KO.EXE simulation when a

¤ Contaminant leached from lens Parameters small fraction of chemical constituent

remains in the oil lens.

"large" Simulation ending time Simulation Allow sufficient simulation time for

Parameters chemical to reach the water table before

ending simulation.

Once HSSM-KO has run and produced an HSSM-T input data file, HSSM-T can be executed by selecting the

Run HSSM-T menu item (3b on Table 7). When HSSM-T executes, screen messages appear as shown in

Table 18. After pressing return, the file names for the simulation appear as indicated in Table 19.

Table 18 Introductory HSSM-T Screen

 ***************************************************

 * *

 * TSGPLUME *

 * *

 * TRANSIENT SOURCE GAUSSIAN PLUME MODEL * 

 * *

 * *

 * MIKE JOHNSON *

 * RANDALL CHARBENEAU *

 * THE UNIVERSITY OF TEXAS AT AUSTIN *

 * *

 * JIM WEAVER *

 * ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY*

 * UNITED STATES ENVIRONMENTAL PROTECTION AGENCY *

 * *

 * VERSION 1.00 *

 ***************************************************

 
57 [Section 4 The MS-Windows Interface]

 Table 19 HSSM-T Output File Names and Run Options

OUTPUT AND PLOT FILE NAMES:

HSSM-KO INPUT DATA FILE BENZENE.DAT

HSSM-KO OUTPUT BENZENE.HSS

HSSM-T INPUT BENZENE.PMI

HSSM-T OUTPUT BENZENE.TSG

HSSM-T PLOT BENZENE.PMP

TO RUN TSGPLUME ENTER <RETURN>

TO EXIT ENTER 1

When HSSM-T executes, a set of messages is written to the screen (Table 20). These messages inform the

user on the progress of the simulation. The example shown has only one receptor location; when more

receptors are used, more messages like these are produced.
[Section 4 The MS-Windows Interface] 58

Table 20 Typical HSSM-T Screen Messages 

 *** DATA INPUT 

 *** DATA INITIALIZATION 

 *** CALCULATING FLOATING POINT PRECISION

 ***

 *** COMPUTATION BEGINNING FOR RECEPTOR 1

 *** CALCULATING THE TOE TIME OF THE HISTORY

 *** SEARCH ALGORITHM COMPLETED IN 6 ITERATIONS

 *** COMPUTATION AT 18.18 DAYS COMPLETED

 *** COMPUTATION AT 18.44 DAYS COMPLETED

 *** COMPUTATION AT 33.41 DAYS COMPLETED

 *** COMPUTATION AT 48.38 DAYS COMPLETED

 *** COMPUTATION AT 63.35 DAYS COMPLETED

 *** COMPUTATION AT 78.32 DAYS COMPLETED

 *** COMPUTATION AT 83.32 DAYS COMPLETED

 *** COMPUTATION AT 88.32 DAYS COMPLETED

 *** COMPUTATION AT 93.32 DAYS COMPLETED

 *** COMPUTATION AT 98.32 DAYS COMPLETED

 *** COMPUTATION AT 103.3 DAYS COMPLETED

 *** COMPUTATION AT 108.3 DAYS COMPLETED

 

 {other similar messages omitted}

 

 *** COMPUTATION AT 553.3 DAYS COMPLETED

 *** COMPUTATION AT 603.3 DAYS COMPLETED

 *** COMPUTATION AT 653.3 DAYS COMPLETED

 *** COMPUTATION AT 703.3 DAYS COMPLETED

 *** COMPUTATION AT 753.3 DAYS COMPLETED

 *** COMPUTATION AT 803.3 DAYS COMPLETED

 *** COMPUTATION AT 853.3 DAYS COMPLETED

 ***

 *** OUTPUT FILE: 

 *** BENZENE1.TSG 

 *** PLOT FILE: 

 *** BENZENE1.PMP 

 *** TSGPLUME END 

Upon completing the HSSM-T simulation, the DOS window remains open so that any error messages stay

on the screen. The window is closed by clicking on its system menu (upper left hand corner) and selecting exit.
59 [Section 4 The MS-Windows Interface]

4.8 Graphical Presentation of HSSM Output

Six graphs can be automatically generated from a successful HSSM simulation. These graphs provide

a visual summary of the simulation results and include information from each of the three modules of HSSM.

Table 21 gives information on each of the graphs provided.

Table 21 HSSM Graphics

Title HSSM Module Description

Saturation Profiles KOPT Vadose Zone Liquid Saturations from the Surface

to the Water Table

NAPL Lens Profiles OILENS Cross-section of the NAPL lens on the water table

NAPL Lens Radius OILENS History of the radius of the NAPL lens and the

History effective radius of the contaminant

Contaminant Mass OILENS History of the mass flux from the NAPL lens to the

Flux History aquifer

NAPL Lens OILENS History of the mass in the NAPL lens

Contaminant Mass

Balance

Receptor TSGPLUME History of the contaminant concentrations at the

Concentration Histories receptor points

Each of the graphics is described in the following sections along with an example figure.

4.8.1 Saturation Profiles

The saturation profiles (Figure 23) represent the simulated distribution of fluids in the vadose zone.

The cross-hatched region on the left represents the assumed uniform water saturation. Plotted between the

water saturation and "1.0" are the NAPL profiles. The profiles are created at the profile times selected by the

user before running the model. The profile times are listed on the lower right of the figure. The times

correspond to the profiles plotted from right to left (i.e., the outermost profile corresponds to the earliest time).

The profiles may not turn out to be plotted at advantageous times for display of the results. The user may wish

to rerun the model with modified times in order to produce a desired sequence of profiles. 
[Section 4 The MS-Windows Interface] 60

4.8.2 NAPL Lens Profiles

The lens profile graph (Figure 24) illustrates the configuration of the lens at the profile times selected

by the user. The graph illustrates the configuration of the lens in the vicinity of the water table (vertical axis).

The water table is indicated by the horizontal line. The horizontal axis shows the lens radius beginning at the

source (radius = 0.0) out to some distance beyond the edge of the lens. The vertical line from the top to the

lens indicates contamination in the vadose zone due to the source. The saturation profiles give the time

variation of saturation within this region. The lens shaped body shows the configuration of the actively

spreading NAPL. The hatched areas (which are barely visible in this example) indicate the region of the

vadose and saturated zones where there is residual NAPL. These regions develop as the NAPL lens builds

and then decays. To step through the sequence of lens profiles, click on the arrow buttons at the upper left

of the graph.

4.8.3 Contaminant Mass Flux History

The contaminant mass flux history (Figure 25) shows the mass flux of contaminant into the aquifer as a

function of time. This mass flux is used as the input boundary condition to HSSM-T. As the NAPL lens forms,

the mass flux to the aquifer increases rapidly, due to the increasing radius of the NAPL lens. If the source is

cut off, as occurs in this example, the mass flux to the aquifer declines because of leaching of the contaminant

into the aquifer. Typically, the mass flux shows a "tailing" effect. In fact, if this graph does not show decline of

the mass flux into the aquifer, then the input mass flux to HSSM-T has been truncated and the HSSM-T results

are likely in error.

4.8.4 NAPL Radius History 

The NAPL lens radius history shows the radius of the lens as a function of time (Figure 26). The lens

radius increases rapidly as the gasoline enters the lens. Later the lens tends toward a limiting radius. 

4.8.5 NAPL Lens Contaminant Mass Balance

The NAPL lens contaminant mass balance (Figure 27) shows the mass of contaminant contained within

the NAPL lens as a function of time. The graph also plots the cumulative mass of contaminant which has been

dissolved into the ground water from the lens. As the mass contained within the lens declines, the cumulative

mass dissolved increases proportionately.
61 [Section 4 The MS-Windows Interface]

Figure 23 Typical saturation profiles Figure 24 Typical NAPL lens profile

Figure 25 Typical contaminant mass flux history Figure 26 Typical NAPL lens radius history
[Section 4 The MS-Windows Interface] 62

Figure 27 Typical NAPL lens contaminant mass balance Figure 28 Typical receptor concentration histories

4.8.6 Receptor Concentration Histories

The receptor concentration histories (Figure 28) show the predicted concentrations at the user-selected

receptor points. Concentrations above the specified threshold are plotted as a function of time for each

receptor location. Care should be taken to identify the threshold value input to the model in order to assure that

the value has not been set too high and as a result truncated concentration histories are plotted in this graph.

4.9 A Note on the Efficiency of Using the Windows Interface

The computational modules of HSSM (HSSM-KO and HSSM-T) execute more rapidly under DOS than

they do under Windows. Within Windows, the HSSM-KO and HSSM-T models run faster as a full screen

process than in a DOS window. In some cases, the most time-efficient way to use the Windows interface is to

use HSSM-WIN as a preprocessor to create several input data files, then exit HSSM-WIN and run HSSM-KO

and HSSM-T under DOS (Appendix 1.9). The commands for running HSSM-KO and HSSM-T from DOS are

HSSM-KO name.dat

HSSM-T name.pmi

where name.dat is the input data set created by HSSM-WIN and name.pmi is the HSSM-T input data file

created by running HSSM-KO. The results can be viewed by reentering HSSM-WIN and plotting graphs of the

results.
63 [Section 4 The MS-Windows Interface]

4.10 Menu Command Reference

This section lists each HSSM-WIN command an briefly describes its action. The italicized number and

letter refer to the columns and rows of Table 7, respectively.

File (1)

The File menu lists commands for manipulating files, and includes the option to Exit HSSM-WIN.

New (1.a)

New clears the memory of parameters and file names, restoring HSSM-WIN to its startup state. 

Open... (1.b)

The Open dialog box (Figure 13) is used to open a data file. This file contains the input data for the

model programs. Once opened by HSSM-WIN, the data are available for editing or saving under

a new name. 

Save (1.c)

Save will save the current parameter settings in the current file, which is displayed in HSSM-WIN's

caption bar. 

Save As... (1.d)

The Save As dialog box (Figure 14) will prompt for an alternate file name under which to save the

current settings. When entering the name, it is sufficient to enter only the prefix (the first eight or

fewer characters). HSSM-WIN will tack on the appropriate extension if you have not.

Check File Times (1.e)

This selection checks the file creation or modification times to prevent HSSM-T from being executed

with an outdated input file. Normally, if an HSSM-KO input data file has been modified, HSSM-T

should not be run before HSSM-KO has been run or rerun.

W h e n this selection is activated, HSSM-T is prevented from being

executed if the HSSM-KO input data file has a later date/time than the HSSM-T input data file.

Plotting files are also checked to see if they predate the data input files, in which case the user is

prompted to rerun the model. Sometimes, as when files are moved from one directory to another,

the user may wish to override this safety feature. 

Exit HSSM-WIN (1.f)

This selection is used to terminate HSSM-WIN and clear the screen of all graphs.

Edit (2)

General Data (2.a) is used to set various model switches and to select titles for the graphs.

Hydrologic Data (2.b) is used to input hydrologic and hydraulic variables.

Hydrocarbon Phase Data (2.c) is used to choose parameters related to the NAPL phase and the

chemical constituent.
[Section 4 The MS-Windows Interface] 64

Model Simulation Data (2.d) is used to input options which control the simulations by HSSM-KO and

HSSM-T.

Information about the meaning and appropriate values for each item in the data entry dialog boxes is given

in Sections 4.6.3 through 4.6.6. 

Model (3)

Run HSSM-KO (3.a)

 Causes HSSM-KO to execute under using the current HSSM-KO input data

file.

Run HSSM-T (3.b)

Causes HSSM-T to execute using the current HSSM-T input data file.

Run REBUILD (3.c)

Causes REBUILD to execute and attempt to recover temporary files from an interrupted or

unsuccessful run.

Graph (4)

The Display Graphs (4.a) dialog box (Figure 15) will prompt the user for which graphs to generate and

will draw them on the screen. 

In the event that no oil lens has formed or the TSGPLUME model was not run, some graphs will not be

available for display, and their checkboxes will be empty. Attempting to select these boxes will produce

a message about their unavailability. For example, in Figure 15 the Receptor Well Concentrations are

not available.

Copy Graph (4.b) copies the contents of the graph window, in its current size and configuration, to the

Windows Clipboard, a data storage facility available to all Windows applications. Once copied to the

Clipboard, the graph can be transferred to other applications such as PAINTBRUSH or WRITE using the

"Paste" command within those applications. Nothing can be pasted into HSSM-WIN, but the graphs can

be exported as bitmaps this way.

Print Graph (4.d) prints a copy of the graph on the printer that Windows currently recognizes. (Choice

of printers is available through the Windows Control Panel). HSSM-WIN attempts to make an actual size

copy of the graph window on the printed page, so what appears in the graph window is what will appear

on paper. Small graphs print fairly quickly (several seconds), but larger ones will take longer since there

are more points to transfer. A full-screen graph will be scaled down to fit on the page, and may take

several minutes, depending on the sophistication of the printer.

HSSM-WIN's print function does not support plotters or daisy-wheel printers, since they cannot print

bitmaps.

Close Graph (4.e) closes the currently selected graph. Graphs may also be closed

by double clicking on their system menus.

Fonts (4.f) allows the selection of alternative fonts for lettering the HSSM graphics. 

Various fonts may be chosen for the graph title, axis labels, and legends. The default option returns all

graph text to the default font.
65 [Section 4 The MS-Windows Interface]

Window (5)

Cascade (5.a)

Arranges the graph windows in a cascaded formation.

Tile (5.b)

Arranges the graph windows in a tiled formation.

Arrange Icons (5.c)

Neatly rearranges the graph icons. The spacing of these icons is determined by the setting in the

Desktop applet in control panel.

Close All (5.d)

Closes all of the graph windows and removes them from memory.

Help (6)

Read Help File (6.a)

The Help file, HSSMHELP.WRI, can be read using WRITE, the standard file editor which comes

bundled with Windows. Figure 29 shows a sample of this Help file. 

About HSSM and About HSSM-WIN (6.b and 6.c)

The "About" dialog boxes provide information pertaining to the origins of the programs.

The System Menu (7)

The system menu, common to all windows programs, is accessed by clicking on the spacebar icon in the

upper left corner of the window or by typing ALT + SPACEBAR from the keyboard. In addition to choosing

various modes of display of the window, the program may also be terminated. 
[Section 4 The MS-Windows Interface] 66

Figure 29 HSSM-WIN "Help" information in HSSMHELP.TXT
67 [Section 5 Example Problems]

Section 5 Example Problems

In this section, two example problems are presented along with HSSM input data sets and graphic of the

results. The complete set of input and output files is distributed on the HSSM-2 diskette. The intent of these

examples is to provide guidance in application of the model to similar problems. Each begins with a brief

description of the problem including some values of model parameters which are assumed to be well-known.

The examples then proceed with a discussion of the specific rationale used for the selection of each parameter

of the model. The parameters are listed in the order that they appear in the Windows interface. 

5.1 Problem 1: Gasoline Arrival Time at the Water Table

An emergency response and monitoring plan is being prepared for an above-ground storage tank facility.

 An estimate is needed of how long it would take gasoline to reach the water table and what monitoring

frequency would be required to detect a leak before gasoline reaches the water table. The soil has been

classified as a sandy clay loam soil. In this example, the water table lies at a depth of 5.0 meters. All of the

parameters for the model run are saved in the file X1STF.DAT. HSSM-WIN can be used to page through the

input parameters as the example is studied. The file may be loaded and viewed according to the instructions

in section 4.5.2 "Creating and Editing Input Data Sets."

This problem needs the use of the KOPT module with no dissolved contaminant. A "per unit area"

simulation should be performed because only the transport time through the vadose zone is required. Of all

the input data required for the model, only the following parameters are required for the "KOPT only"

simulation. HSSM-WIN places necessary zeros in the data file for the unused parameters. The presentation

of the input data follows the order of the four HSSM-WIN input data dialog boxes. 

The first of the boxes, "General Model Parameters," contains the run title, printing switches, module

switches and the file names. For this example, the run title is

Gasoline Release from an Aboveground Storage Tank Fac.

Gasoline Arrival Time at the Water Table

KOPT Simulation Only

The "create output files" switch is checked in order to write the output files. For the first attempt at running a

new data set, it is recommended to echo print the input data only and check the parameter values by reading

the *.HSS output file. Only the Run KOPT module switch is checked as only KOPT is needed to estimate the

gasoline arrival time at the water table. The output file names are automatically generated by the interface

and shown in the FILE names area of the dialog box. The file name used for this simulation is X1STF.DAT.

The completed dialog box appears as shown in Figure 30.
[Section 5 Example Problems] 68

Figure 30 Problem 1 completed General Parameters dialog box

The second dialog box, "Hydrologic Parameters" contains the hydrologic and soil properties. 

Hydrologic Properties

The parameters shown in Table 22 are used for the Hydrologic Properties. Standard fluid properties are

used for the water phase. During infiltration, some of the air in the pore space is not displaced by either the

water or the NAPL. It is assumed that during infiltration the maximum hydraulic conductivity to water is one-half

of the saturated hydraulic conductivity. From this assumption, HSSM automatically determines the amount of

air trapped in the pore space. 
Ks ' 270 02

h 2

ce

82

(8 % 1) (8 % 2) ' 8.68 x 10&4 cm/s

69 [Section 5 Example Problems]

(17)

 

Table 22 Problem 1 Hydrologic Properties

Parameter Rationale Value

Water Phase Viscosity, μ Standard value 1.0 cp w

Water Phase Density, Dw Standard value 1.0 g/cm3

Water Phase Surface Tension, Assumed 65.0 dyne/cm

Faw

Maximum Relative Permeability Assumed 0.5

During Infiltration, krw(max)

Recharge Input Type Specify Saturation

Water Saturation, S Specified water saturation 0.35 w(max)

Capillary Pressure Curve Model and Porous Medium Properties

The porous medium properties are estimated from Brakensiek et al.'s soil parameter tabulation for the

Brooks and Corey model. The values shown in Table 23 are taken from the tabulation reproduced in Appendix

3.1.

Table 23 Problem 1 Porous Medium Properties

Parameter Value

Brooks and Corey's Pore Size 0.368

Distribution Index, 8

Air Entry Head, hce 46.3 cm

Residual Water Content, 2wr 0.075

Porosity, 0 0.406

The residual water saturation that is required by HSSM is calculated by dividing the residual water content by

the porosity to get 0.18 (0.075/0.406).

The hydraulic conductivity in cm/s of the system is then estimated from (Brakensiek et al., 1981)

where the air entry head is in centimeters. The value is then converted to the units of meters per day by

multiplying by 864 to give a K of 0.75 m/d. s From the basic soil property information, the following parameters
[Section 5 Example Problems] 70

are determined (Table 24). The completed dialog box is shown in Figure 31. Note that in all of the dialog

boxes for Problem 1 range checking is disabled. This is shown by the open check box (9) below the file name.

Range checking must be disabled for KOPT only simulations, because many of the input parameters default

to normally-disallowed zeros. 

Figure 31 Problem 1 completed Hydrologic Properties dialog box

Table 24 Problem 1 Hydraulic Conductivity and Capillary Pressure Curve Parameters

Parameter Rationale Value

Ratio of Horizontal to Arbitrary value as this parameter is not used in 5.0

Vertical Conductivity KOPT

Porosity, 0 From Brakensiek et al. 1981 Tabulation 0.406

Depth to Water Table Arbitrary value as only KOPT is used 10.0 m

Hydrocarbon Phase Parameters

Table 25 shows the NAPL fluid property values that are entered in Figure 32. These are intended to

represent gasoline. 
71 [Section 5 Example Problems]

Table 25 Problem 1 Hydrocarbon (NAPL) Phase Properties

Parameter Rationale Value

NAPL Phase Density, Do Typical value for gasoline 0.74 g/cm3

NAPL Phase Viscosity, μ Typical value for gasoline 0.45 cp o

Residual NAPL Saturation Estimated 0.10

(vadose zone), Sorv

NAPL Surface Tension, Fao Estimated 35.0

dyne/cm

Hydrocarbon Release

The hydrocarbon (NAPL) release scenario is chosen by selecting the radio button for constant head

ponding (Figure 32). The beginning time, ending time and ponding depth are entered to define the release.

The release is assumed to begin at 0.0 days and end at 1.0 day. During this interval the ponding depth is

assumed to remain constant at 0.05 m (5 cm).

Figure 32 Problem 1 completed Hydrocarbon Phase Properties dialog box
[Section 5 Example Problems] 72

Simulation Parameters

The remaining parameters are shown in the Simulation Parameters dialog box (Figure 33). These define

the source area, time stepping, profile times and ending criterion as indicated in Table 26.

Table 26 Problem 1 Simulation Control Parameters

Parameter Rationale Value

Radius of the NAPL Source, R A "per unit area" simulation is desired, the value 0.5642 m s

0.5642 results in a 1.0 m source area 2

Simulation Ending Time Simulate the release for 25 days, since gasoline is a 25 days

low viscosity fluid and can reach the water table

relatively rapidly in a permeable media.

Maximum Solution Time Step Use a relatively small value, because only 25 days 0.1 day

are simulated

Minimum Time Between Printed Use a value smaller that the minimum solution time 0.05 day

Time Steps step.

Five profiles times are used for the simulation. The times should be small, since the gasoline is expected

to reach the water table relatively rapidly. Use times of 0.25, 0.5, 1.0, 2.0 and 5.0 days (6, 12, 24, 48 and 60

hours). HSSM-WIN requires at least one groundwater receptor be indicated. Here the receptor is arbitrarily

located at (0.0,0.0).

Figure 33 Problem 1 completed Simulation Parameters dialog box
73 [Section 5 Example Problems]

Problem 1 Model Results

The model is executed by entering the command

HSSM-KO X1STF.DAT

The saturation profiles from the simulation are shown in Figure 34. These profiles were drawn with the

HSSM-PLT program. The depth of the sharp front increases with time and the first three profiles show uniform

NAPL saturations. The last two profiles show varying NAPL saturations, because they occur at 48 and 60

hours which both are past the end of the release (24 hours). 

With complete confidence in the accuracy of the input data, it could be assumed that the gasoline never

reaches the water table. Most of the model parameters used in this example have been estimated from

published tabulations. Rather than accepting the results of one simulation as being authoritative, several

simulations should be run in order to get some feel for the effects of parameter variability. If the hydraulic

conductivity was in fact 10 times greater than the average value of 0.75 m/d, the gasoline would flow deeper

into the subsurface. Because of the constant head ponding condition assumed for this case, the gasoline would

also flow faster. The constant head ponding condition does not specify the volume of gasoline which enters

the soil; it only indicates that enough gasoline is supplied to maintain the 0.05 m ponding depth for one day.

Figure 35 shows the NAPL front position when the hydraulic conductivity is 7.5 m/d. By 25 days, the gasoline

would reach 24 meters deep, if not for the water table 5.0 meters deep. From the X2STF.HSS file, the depth

of 5 meters was reached within 9.8 hours. 

This example has focussed on the role of the hydraulic conductivity in determining the depth of the

gasoline. The effect of variation in other parameters can likewise be demonstrated. Some of the other

uncertain parameters are the assumed release condition, moisture content, and capillary pressure parameters.
[Section 5 Example Problems] 74

Figure 34 The storage tank example saturation profiles
75 [Section 5 Example Problems]

Figure 35 Storage tank facility example with increased conductivity
[Section 5 Example Problems] 76

5.2 Problem 2: Transport of Gasoline Constituents in Ground Water to Receptor

Locations

During a one-day period, 1500 gallons of gasoline leak from a tank surrounded by a circular berm of 2.0

meter radius. Benzene is believed to compose 1.15% by mass of the gasoline. The benzene concentration

in the ground water at locations 25, 50, 75, 100, 125 and 150 meters away are needed to assess the impact

of the spill. The soil is believed to be predominantly sand in the vicinity of the spill. The aquifer is 10 meters

below the ground surface, and its saturated thickness is 15 meters.

Complete information for the site is not available so many of the HSSM parameters must be estimated.

 In the absence of better information, parameter values will be estimated from tabulations from the literature.

 The data set for this example will be organized according to the 4 dialog boxes for entering data in HSSM-WIN.

The parameters for this example are found in the file X2BT.DAT, which is found on the HSSM-WIN distribution

diskette. The file may be loaded and viewed according to the instructions in section 4.5.2 "Creating and Editing

Input Data Sets."

The first of the boxes, "General Model Parameters," contains the run title, printing switches, module

switches and the file names. For this example, the run title is

Benzene transport from 1500 gal gasoline release

Benzene 1.15% by mass of gasoline

sandy soil from Carsel and Parrish Data set

The "create output files" switch is checked in order to write the output files. For the first attempt at running a

new data set, it is recommended to echo print the input data only and check the parameter values by reading

the *.HSS output file. Each of the Module switches is checked, because all three of the HSSM modules are

needed for estimating the receptor concentrations. At this point the names are of no concern as they are

added automatically when the file is saved. The file name used for this simulation is X2BT.DAT. The

completed dialog box appears as shown in Figure 36.
77 [Section 5 Example Problems]

Figure 36 Problem 2 completed General Parameters dialog box

The second dialog box, "Hydrologic Parameters" contains the hydrologic and soil properties. 

Hydrologic Properties

Standard properties of water are used for the simulation: density of 1.0 g/cm , viscosity of 1.0 cp, and 3

surface tension of 65 dyne/cm. During infiltration, some of the air in the pore space is not displaced by either

the water or the NAPL. It is assumed that during infiltration the maximum hydraulic conductivity to water is onehalf of the saturated hydraulic conductivity. From this assumption, HSSM automatically determines the amount

of air trapped in the pore space. 

Recharge

The average annual recharge rate at the release site is estimated to be 50 cm/year. When converted into

the required HSSM units of meters per day, the recharge rate is 0.0014 m/d.

Capillary Pressure Curve Model and the Porous Medium Properties

The tabulation of soil parameters developed by Carsel and Parrish (1988) will be used for the soil

properties because of the relatively large number of samples used in developing the statistics for the sand

classification. The parameters in Table 27 are taken from the tabulation (which is reproduced in Appendix 3.1).
[Section 5 Example Problems] 78

Table 27 Problem 2 Hydraulic Properties

Parameter Average value from

Carsel and Parrish

(1988)

Hydraulic conductivity, K 7.1 m/d s

Residual water content, 2wr 0.045

Saturated water content, 2m 0.43

van Genuchten capillary parameter """ 4.5 m-1

van Genuchten capillary parameter "n" 2.68

These parameters form the basis for several of the other required input parameters on the "Hydrologic

Parameters" dialog box. The parameter listed in Table 28 are derived from the soils data.

Table 28 Problem 2 Parameters Derived from the Hydraulic Properties

Parameter Rationale Value

Residual water HSSM requires residual saturation to be 0.10

saturation, S entered, rather than residual moisture content. wr

S = 2 /2 (0.045/0.43) wr wr m

Ratio of horizontal to The sandy soil is assumed to be only slightly 2.5

vertical conductivity anisotropic.

Porosity, 0 The porosity is taken as being equal to the 0.43

saturated water content.

Bulk density, Db In terms of porosity and solid density, the bulk 1.51 g/cm

density is D = D (1 - 0). b s

3

2.65 g/cm (1 - 0.43) 3

The aquifer saturated thickness is 15.0 meters, and the depth to the water table is 10.0 meters. For this

simulation, no smear zone is included; so the NAPL is allowed to spread out freely along the water table. Thus

the capillary thickness parameter is set to a minimum value of 0.01 m. 

The ground water gradient is estimated to be 1 foot per hundred or 0.01. The longitudinal dispersivity is

taken as 10 meters. This value follows from the rule of thumb that says that the longitudinal dispersivity could

be one tenth the distance to the receptor point (100 m). The horizontal transverse dispersivity is assumed to

be 1 meter and the vertical transverse dispersivity is assumed to be 0.1 m.
8208 mg/L ' 1.14 %

100 (0.72 g/cm 3 ) (1000 cm 3 /L) (1000 mg/g)

79 [Section 5 Example Problems]

(18)

At this point the "Hydrologic Parameters" dialog box of HSSM-WIN can be completely filled in (Figure 37).

Figure 37 Problem 2 completed Hydrologic Properties dialog box

Hydrocarbon Phase Properties

The first group of parameters is used to describe the properties of the NAPL itself, which is assumed to

be an inert oily phase. The density and viscosity of gasoline are typically near 0.74 g/cm and 0.45 cp, 3

respectively. The solubility of the NAPL is arbitrarily taken as 10 mg/l. A small amount of the NAPL phase

will dissolve during the simulation, but this amount has little effect on the dissolved constituent of interest. 

Residual NAPL saturations are specified for the aquifer (0.15) and the vadose zone (0.05). These values are

estimates, but reflect the fact that the residual in the aquifer is likely to be higher than that in the vadose zone

(Wilson et al., 1990). The soil/water partition coefficient for the NAPL phase is taken to be 0.83. The NAPL

or "oil" surface tension is assumed to be about half of the water/air surface tension, F or 35 dyne/cm. ao

Dissolved Constituent Properties

Since the object of the simulation is to estimate down gradient concentrations of a chemical of interest,

the dissolved constituent exists box is checked. The initial constituent concentration (of benzene) is calculated

from its mass percentage in the gasoline. The dissolved constituent check box is selected to tell HSSM that

a dissolved constituent of the NAPL should be simulated.

Since the benzene is present in the gasoline at a mass fraction of 1.14% and the density of the gasoline

is 0.72 g/cm , the initial concentration of benzene in the gasoline is 3
qo ' 0.4522 m/d '

1500 gal ft 3

7.5 gal

0.3048m

ft

3

B (2.0 m)

2 1.0 day

[Section 5 Example Problems] 80

(19)

The Oil/Water (NAPL/Water) partition coefficient, K , will be assumed to be equal to 311 as determined from o

the RAOULT utility (Appendices 3.2 and 6). The benzene partition coefficient between the soil and water, K , d

is 0.083 L/kg. The value is determined by multiplying the assumed fraction organic carbon (0.001) by the value

of K (83). The value of K is taken from Table 98 in Appendix 3.2. The water solubility of benzene is about oc oc

1750 mg/l. This value is an absolute limiting value for the simulation. The actual solubility of benzene in the

gasoline is determined by the partition coefficient. No degradation of the benzene will be assumed for the

HSSM-T model, so the half-life check box is unchecked.

Hydrocarbon Release

The release in this example is given as a volume released during a certain time interval. The appropriate

release definition for this situation is the specified flux release. The required input parameters are the

beginning time in days and the ending time in days, and the NAPL flux in meters per day. The beginning time

is 0.0 days and the ending time is 1.0 days. The NAPL flux, q , is calculated by dividing the release volume by o

the source area and the duration.

The completed dialog box is shown in Figure 38.

Figure 38 Problem 2 completed Hydrocarbon Phase Properties dialog box

Simulation Control Parameters

A number of parameters interact to control the various aspects of the simulation. These are listed in

Table 29.
81 [Section 5 Example Problems]

Table 29 Problem 2 Simulation Control Parameters

Parameter Rationale Value

Radius of the NAPL source, R From the problem definition 2.0 meters s

Radius multiplication factor Suggested value 1.001

Maximum NAPL saturation in Estimated from the NTHICK utility 0.3260

the lens, S described in Appendix 7 o(max)

Simulation ending time A time much greater than that expected 2500 days

for the NAPL lens to form

Maximum solution time step Limit of approximately less than 1 month 20 days

Minimum time between printed The model can produce output on very 0.1 days

time steps and mass balance small time intervals, such information is of

checks little usefulness.

OILENS Simulation Ending Criterion

The fourth option, "contaminant leached from lens," is chosen for the ending condition as this is the only

option that allows the HSSM-T model to be run. The fraction of mass remaining is chosen to be 0.01. The

OILENS portion of HSSM-KO will terminate when less than 1% of the mass that has entered the lens over the

length of the simulation remains in the lens. The other 99% will have been leached into the ground water. The

chemical constituent will still exist below the source in the vadose zone. This amount of chemical is contained

in the NAPL phase as residual saturation, and it never enters the lens.
[Section 5 Example Problems] 82

HSSM-T Model Parameters

Many previously entered parameters are used by HSSM-T. The remaining parameters are listed in Table

30.

Table 30 Problem 2 HSSM-T Model Parameters

Parameter Rationale Value

Percent maximum contaminant The radius that occurs when the mass flux 101

radius to the aquifer is maximum should be used. 

The value 101 is a flag that triggers this

selection.

Minimum output concentration The minimum concentration that HSSM-T 0.001 mg/l

will report. A non-zero value is required

for HSSM-T to function properly.

Beginning time Arbitrary value that will be overridden by a 100 days

successful HSSM-T simulation

Ending time Arbitrary value that will be overridden by a 5000 days

successful HSSM-T simulation

Time increment A 50-day time increment usually produces 50 days

smooth concentration history curves

NAPL Lens Profiles

HSSM can output profiles at various times during the simulation. The profiles represent the amount of

NAPL in the vadose zone pore space and the configuration of the NAPL lens. Because the motion of the

gasoline is relatively rapid, the profiles should be clustered toward the release time. To catch the NAPL as it

moves through the sandy vadose zone, for example, profile times less than about 1 day are needed. In this

example, however, the lens configuration is of more interest and seven somewhat later profile times are

selected: 25, 50, 75, 100, 125, 150 and 200 days. 

Receptor Well Locations

The six receptor locations for this simulation are at 25, 50, 75, 100, 125 and 150 meters away from the

center of the source, taken longitudinally in the flow direction. The completed dialog box is shown in Figure

39.
83 [Section 5 Example Problems]

Figure 39 Problem 2 completed Simulation Control dialog box parameters

Each graph generated by HSSM for this data set was shown previously in Figure 23 to Figure 28. This

example shows typical behavior for gasoline releases. There is relatively rapid flow and transport in the vadose

zone followed by the formation and decay of a NAPL lens at the water table. Subsequent leaching of the

chemical constituent of the NAPL (benzene) causes contamination of the aquifer. The time scales for lens

formation and decay, leaching, and transport to the 150 m receptor are on the order of 1 year, 4 years, and 11

years, respectively.
[Section 6 Contents of the Output Files] 84

Section 6 Contents of the Output Files

Although two graphical user interfaces are provided with HSSM, much of the useful and necessary

information produced by the model is not contained on the graphs produced by these software packages. The

main output files of the HSSM-KO and HSSM-T programs contain a summary of the input data and model

results. The following tables describe each part of these files, along with excerpts from the output files. Several

complete sets of output files are distributed on the HSSM-2 diskette.

6.1 HSSM-KO Output File

Table 31 outlines the contents of the HSSM-KO output file which has the extension .HSS. The output file

consists of a series of tables which contain the results from the simulation.

Table 31 HSSM Main Output File Contents

 Table Title Contents

Input Data 1. Echo print of the input data.

2. Parameters calculated directly from input data.

3. Water/air and NAPL/air capillary pressure curves used in the 

model.

Location of the Oil Front Position of the NAPL front during the simulation.

Location of the Constituent Position of the chemical constituent of interest during the simulation.

Front

OILENS Model Output--Oil Lens Description of the NAPL lens during the simulation.

Description

OILENS Model Output-- Description of leaching of aqueous contaminants during the

Aqueous Contaminants simulation.

Saturation and Concentration Variation with depth of vadose zone saturations and concentrations 

Profile at a user-specified time.

Radial Profile Through the Lens Variation with radius of the top and bottom of the OILENS at a userspecific time.

KOPT/OILENS Postprocessing Summary information from the simulation.

HSSM--Run Information Information on the numerical techniques used in the simulation.

If the model executes with no catastrophic errors, then the HSSM-KO output file is ended with the message:

*********************

SUCCESSFUL EXECUTION

*********************

Each component of the output file is described in further detail below. For each table in the output file, the

column headings and their meanings are described. An excerpt from the .HSS file follows each description.
85 [Section 6 Contents of the Output Files]

Table 32 Input Data 

Purpose: To provide an echo printing of the input data set and print out the results of preliminary

calculations

Section Contents

1 Echo printing of input data so the user can assure that the intended parameter values

have been entered.

2 Model parameters calculated from the input data.

3 Air/water and air/NAPL capillary pressure curves used in the simulation.

 **************************************************

 HSSM HYDROCARBON SPILL SIMULATION MODEL

 **************************************************

 KOPT KINEMATIC OILY POLLUTANT TRANSPORT

 OILENS RADIAL OIL LENS MOTION

 TSGPLUME TRANSIENT SOURCE GAUSSIAN PLUME

 **************************************************

 Benzene transport from 1500 gal gasoline spill 

 1.15% benzene in gasoline 

 sandy soil, properties from Carsel and Parrish 

 INPUT DATA

 ==========

 DATA FILES:

 HSSM-KO INPUT: x2bt.dat 

 HSSM-KO OUTPUT: x2bt.HSS 

 HSSM-KO PLOT 1: x2bt.PL1 

 HSSM-KO PLOT 2: x2bt.PL2 

 HSSM-KO PLOT 3: x2bt.PL3 

 HSSM-T INPUT: x2bt.PMI 

 HSSM-T OUTPUT: x2bt.TSG 

 HSSM-T PLOT: x2bt.PMP 

 INTERFACE FLAG = D

 WRITING CRITERIA = 1

 KOPT RUN FLAG = 1

 DISSOLVED CONSTITUENT FLAG = 1

 OILENS RUN FLAG = 1

 TSGPLUME RUN FLAG = 1

 CONSTANTS & MATRIX PROPERTIES...........

 SAT. VERT. HYD.CONDUCTIVITY = 7.100 (M/D)

 RATIO OF HORIZONTAL TO 

 VERTICAL CONDUCTIVITY = 2.500 (*)

 RELATIVE PERMEABILITY INDEX = 2 (*)

 POROSITY = .4300 (*)

 RESIDUAL WATER SATURATION = .1000 (*)
[Section 6 Contents of the Output Files] 86

 VAN GENUCHTEN'S N = 4.500 (*)

 WATER EVENT CHARACTERISTICS.............

 DYNAMIC VISCOSITY = 1.000 (CP)

 DENSITY = 1.000 (G/CC)

 RAIN TYPE : 1-FLUX 2-SAT. = 1 (*)

 WATER FLUX OR SATURATION = .1400E-02 (M/D OR *)

 MAX KRW DURING INFILTRATION = .5000 (*)

 DEPTH TO WATER TABLE = 10.00 (M)

 POLLUTANT EVENT CHARACTERISTICS.........

 DYNAMIC VISCOSITY = .4500 (CP)

 DENSITY = .7200 (G/CC)

 RESIDUAL NAPL SATURATION = .5000E-01 (*)

 OIL LOADING TYPE = 1 (*)

 CAPILLARY SUCTION PARAMETERS............

 VAN GENUCHTENS ALPHA = 2.680 (1/M)

 WATER SURFACE TENSION = 65.00 (DYNE/CM)

 OIL SURFACE TENSION = 35.00 (DYNE/CM)

 FLUX LOADING RATE = .4522 (M/D)

 BEGINNING TIME = .0000 (D)

 ENDING TIME = 1.000 (D)

 DISSOLVED CONSTITUENT PARAMETERS........

 INITIAL CONC. IN NAPL = 8208. (MG/L)

 NAPL/WATER PARTITION COEF. = 311.0 (*)

 SOIL/WATER PARTITION COEF. = .8300E-01 (L/KG)

 SOIL/WATER (HYDROCARBON) = .8300E-01 (L/KG)

 BULK DENSITY = 1.510 (G/CC)

 OILENS SUBMODEL PARAMETERS..............

 RADIUS OF POLLUTANT SOURCE = 2.000 (M)

 RADIUS MULTIPLYING FACTOR = 1.001 (*)

 THICKNESS OF CAP. FRINGE = .1000E-01 (M)

 AQUIFER'S VERT DISPERSIVITY = .1000 (M)

 GROUNDWATER GRADIENT = .1000E-01 (*)

 NAPL RESIDUAL IN AQUIFER = .1500 (*)

 MAX NAPL SATURATION IN LENS = .3260 (*)

 WATER SOLUBILITY CONTAMINANT= 1750. (MG/L)

 WATER SOLUBILITY OF OIL = 10.00 (MG/L)

 SIMULATION PARAMETERS...................

 SIMULATION ENDING TIME = 2500. (D)

 MAXIMUM RKF TIME STEP = 20.00 (D)

 MIN. TIME BETWEEN PRINTING = .1000 (D)

 ENDING CRITERIA = 4 (*)

 FACTOR FOR ENDING CRITERIA 4= .1000E-01 (*)

 PROFILES................................

 NUMBER OF PROFILES = 7 (*)

 AT TIMES: (D)

 25.0000 50.0000 75.0000

 100.0000 125.0000 150.0000

 200.0000

 TSGPLUME MODEL PARAMETERS...............

 LONGITUDINAL DISPERSIVITY 10.00 (M)
87 [Section 6 Contents of the Output Files]

 TRANSVERSE DISPERSIVITY 1.000 (M)

 PERCENT MAX. RADIUS 101.0 (M)

 MINIMUM OUTPUT CONC. .1000E-02 (MG/L)

 CONSTITUENT HALF LIFE .0000 (D)

 NUMBER OF RECEPTOR LOCATIONS 6 (*)

 BEGINNING TIME (D) 100.0 (D)

 ENDING TIME (D) 5000. (D)

 TIME INCREMENT (D) 50.00 (D)

 AQUIFER THICKNESS (M) 15.00 (M)

 RECEPTOR LOCATIONS 

 X Y

 25.00 .0000 

 50.00 .0000 

 75.00 .0000 

 100.0 .0000 

 125.0 .0000 

 150.0 .0000 

 LEGEND

 ======

 (*) DIMENSIONLESS OR NOT APPLICABLE

 (M) METERS

 (D) DAYS

 (CP) CENTIPOISE 1.0 CP = 0.01 GR/CM/SEC

 (M/D) METERS PER DAY

 (DYNE/CM) DYNE PER CENTIMETER

 (MG/L) MILLIGRAMS PER LITER

 (L/KG) LITERS PER KILOGRAM SOIL

 (G/CC) GRAMS PER CUBIC CENTIMETER

 ***END OF INPUT DATA***

Parameters calculated directly from the input data follow the echo printing of the input data set:

 CALCULATED PARAMETERS...................

 SAT VERT NAPL CONDUCTIVITY = 11.36 (M/D)

 AREA OF THE SOURCE = 12.57 (M^2)

 APPROX. BROOKS AND COREY 

 LAMBDA = 2.064 (*)

 AIR ENTRY HEAD = .2759 (M)

 TRAPPED AIR SATURATION = .1442 (*)

 WATER SATURATION = .2049 (*)

 WATER FLUX = .1400E-02 (M/D)

 MAX. OIL CONDUCTIVITY = 3.157 (M/D)

 POLLUTANT VOLUME FLUX = .4522 (M/D)

 TOTAL OIL LOADING, VOL/AREA = .4522 (M)

 TOTAL OIL MASS = 4091. (KG)

 TOTAL CONSTITUENT MASS = 46.64 (KG)
[Section 6 Contents of the Output Files] 88

The estimated capillary pressure curves for air/water and air/NAPL follow the input data in the name.HSS file:

 WATER-AIR, NAPL-AIR CAPILLARY PRESSURE CURVE

 ********************************************

 WATER or NAPL CAPILLARY CAPILLARY

 SATURATION HEAD (CM WATER) HEAD (CM NAPL)

 ===================================================

 .1200 1.7438 1.3041

 .1400 1.2464 .9322

 .1600 1.0242 .7659

 .1800 .8909 .6663

 .2000 .7997 .5980

 .2200 .7321 .5475

 .2400 .6794 .5081

 .2600 .6368 .4763

 .2800 .6015 .4499

 .3000 .5716 .4275

 .3200 .5458 .4082

 .3400 .5233 .3913

 .3600 .5034 .3765

 .3800 .4856 .3632

 .4000 .4697 .3512

 .4200 .4552 .3404

 .4400 .4420 .3306

 .4600 .4300 .3216

 .4800 .4189 .3132

 .5000 .4086 .3056

 .5200 .3990 .2984

 .5400 .3901 .2918

 .5600 .3818 .2856

 .5800 .3740 .2797

 .6000 .3667 .2743

 .6200 .3598 .2691

 .6400 .3533 .2642

 .6600 .3471 .2596

 .6800 .3413 .2552

 .7000 .3357 .2511

 .7200 .3304 .2471

 .7400 .3254 .2433

 .7600 .3206 .2397

 .7800 .3160 .2363

 .8000 .3116 .2330

 .8200 .3073 .2298

 .8400 .3033 .2268

 .8600 .2994 .2239

 .8800 .2957 .2211

 .9000 .2920 .2184

 .9200 .2886 .2158

 .9400 .2852 .2133

 .9600 .2820 .2109

 .9800 .2789 .2086

 1.0000 .2759 .2063
89 [Section 6 Contents of the Output Files]

Table 33 Location of the NAPL Front

Purpose: A summary of the NAPL distribution in the vadose zone.

Column Column Heading Contents

1 Step The number of time steps completed. These

numbers are usually not consecutive, because a

minimum printing interval should be chosen.

2 Time (D) The time in days since the beginning of the

simulation.

3 Depth (M) The depth of the sharp front at the leading edge of

the infiltrating NAPL.

4 Saturation The NAPL saturation at the front; NAPL saturations

behind the front are often lower than this value, as

can be seen on the saturation profiles.

5 Flux (M/D) NAPL flux at the front.

6 Runoff (KG) Runoff is produced when a NAPL flux boundary

condition is specified and the flux is greater than

the maximum dynamic flux allowed by the GreenAmpt model with zero ponding head.

7 Mass (KG) NAPL mass added to the profile per square meter.

8 Ponding (M) The surface ponding depth of NAPL.

NOTE: This output table is produced only up until a NAPL lens forms. At that time the OILENS model

output is produced.
[Section 6 Contents of the Output Files] 90

 **************************************************

 LOCATION OF THE NAPL FRONT

 **************************************************

 Benzene transport from 1500 gal gasoline spill 

 1.15% benzene in gasoline 

 sandy soil, properties from Carsel and Parrish 

 NAPL

 ------------------------------------------------

 STEP TIME DEPTH SATURATION FLUX RUNOFF MASS PONDING 

 (D) (M) (*) (M/D) (KG) (KG) (M) 

 ============================================================================

 1 .0000 .0000 .3957 .4522 .0000 .0000

 4 .2000 .5315 .3957 .4522 .0000 818.3 .0000

 5 .3000 .7972 .3957 .4522 .0000 1227. .0000

 7 .5000 1.3287 .3957 .4522 .0000 2046. .0000

 8 .6000 1.5944 .3957 .4522 .0000 2455. .0000

 9 .7000 1.8602 .3957 .4522 .0000 2864. .0000

 10 .8000 2.1259 .3957 .4522 .0000 3273. .0000

 11 .9000 2.3917 .3957 .4522 .0000 3682. .0000

 13 1.0107 2.6858 .3957 .4522 .0000 4091. .0000

 23 1.1182 2.9715 .3957 .4522 .0000 4091. .0000

 29 1.2248 3.2548 .3957 .4522 .0000 4091. .0000

 33 1.3330 3.5423 .3957 .4522 .0000 4092. .0000

 38 1.4399 3.8024 .3710 .3510 .0000 4092. .0000

 41 1.5691 4.0598 .3472 .2703 .0000 4091. .0000

 43 1.6771 4.2426 .3320 .2266 .0000 4091. .0000

 45 1.8050 4.4325 .3175 .1900 .0000 4091. .0000

 47 1.9668 4.6423 .3029 .1577 .0000 4091. .0000

 49 2.1530 4.8527 .2895 .1317 .0000 4091. .0000

 50 2.2657 4.9677 .2826 .1197 .0000 4091. .0000

 51 2.3909 5.0866 .2758 .1087 .0000 4091. .0000

 52 2.5290 5.2086 .2692 .0986 .0000 4091. .0000

 53 2.6809 5.3332 .2627 .0894 .0000 4091. .0000

 54 2.8478 5.4605 .2564 .0811 .0000 4091. .0000

 55 3.0310 5.5905 .2503 .0736 .0000 4091. .0000

{Intermediate results omitted}

 67 7.0717 7.3052 .1892 .0234 .0000 4089. .0000

 68 7.6604 7.4685 .1848 .0212 .0000 4089. .0000

 69 8.2492 7.6205 .1809 .0194 .0000 4089. .0000

 70 8.8379 7.7628 .1774 .0179 .0000 4089. .0000

 71 9.5411 7.9217 .1736 .0163 .0000 4089. .0000

 72 10.3414 8.0901 .1697 .0148 .0000 4089. .0000

 73 11.1417 8.2470 .1663 .0136 .0000 4089. .0000

 74 12.0723 8.4171 .1626 .0123 .0000 4089. .0000

 75 13.1191 8.5947 .1590 .0112 .0000 4089. .0000

 76 14.1658 8.7601 .1557 .0102 .0000 4089. .0000

 77 15.3753 8.9379 .1524 .0093 .0000 4089. .0000

 78 16.7325 9.1231 .1490 .0084 .0000 4088. .0000

 79 18.0897 9.2953 .1460 .0077 .0000 4088. .0000

 80 19.4469 9.4562 .1433 .0071 .0000 4088. .0000

 81 21.0820 9.6370 .1403 .0064 .0000 4087. .0000

 82 22.9444 9.8283 .1372 .0058 .0000 4087. .0000

 83 24.6391 9.9905 .1348 .0054 .0000 4086. .0000
91 [Section 6 Contents of the Output Files]

Table 34 Location of the Constituent Front

Purpose: A summary of the vadose zone distribution of the dissolved constituent.

Column Column Heading Contents

1 Step The number of time steps completed.

2 Time The time in days since the beginning of the

simulation.

3 Depth-Upper The depth in meters of the leading edge of the

constituent.

4 Depth-Lower The depth in meters of the trailing edge of the

constituent

5 Conc-water The water phase concentration of the constituent at

the leading edge.

6 Mass The total mass of the constituent in the vadose

zone.

NOTE: This output table is produced only up until a NAPL lens forms. At that time the OILENS model

output takes over.
[Section 6 Contents of the Output Files] 92

 **************************************************

 LOCATION OF THE CONSTITUENT FRONT

 **************************************************

 Benzene transport from 1500 gal gasoline spill 

 1.15% benzene in gasoline 

 sandy soil, properties from Carsel and Parrish 

 CONSTITUENT

 --------------------------------------

 STEP TIME DEPTHS CONC-WATER MASS

 LOWER UPPER

 =======================================================

 4 .2000 .5294 .0000 26.3920 9.329 

 5 .3000 .7941 .0000 26.3920 13.99 

 7 .5000 1.3235 .0000 26.3920 23.32 

 8 .6000 1.5882 .0000 26.3920 27.99 

 9 .7000 1.8529 .0000 26.3920 32.65 

 10 .8000 2.1176 .0000 26.3920 37.32 

 11 .9000 2.3823 .0000 26.3920 41.98 

 13 1.0107 2.6753 .0000 26.3920 46.64 

 23 1.1182 2.9598 .0000 26.3920 46.65 

 29 1.2248 3.2419 .0000 26.3920 46.65 

 33 1.3330 3.5283 .0001 26.3920 46.65 

 38 1.4399 3.7864 .0001 26.3920 46.65 

 41 1.5691 4.0416 .0001 26.3920 46.65 

 43 1.6771 4.2226 .0001 26.3920 46.65 

 45 1.8050 4.4107 .0002 26.3920 46.64 

 47 1.9668 4.6184 .0002 26.3920 46.64 

 49 2.1530 4.8265 .0002 26.3920 46.64 

 50 2.2657 4.9403 .0003 26.3920 46.64 

 51 2.3909 5.0578 .0003 26.3920 46.64 

 52 2.5290 5.1784 .0003 26.3920 46.64 

 53 2.6809 5.3015 .0003 26.3920 46.64 

 54 2.8478 5.4273 .0004 26.3920 46.64 

 55 3.0310 5.5556 .0004 26.3920 46.64 

 56 3.2321 5.6864 .0005 26.3920 46.64 

 57 3.4528 5.8197 .0005 26.3920 46.64 

{Intermediate results omitted}

 65 6.0533 6.9350 .0010 26.3920 46.63 

 66 6.5365 7.0879 .0011 26.3920 46.63 

 67 7.0717 7.2452 .0012 26.3920 46.62 

 68 7.6604 7.4057 .0013 26.3920 46.62 

 69 8.2492 7.5551 .0015 26.3920 46.62 

 70 8.8379 7.6949 .0016 26.3920 46.62 

 71 9.5411 7.8510 .0017 26.3920 46.62 

 72 10.3414 8.0163 .0019 26.3920 46.62 

 73 11.1417 8.1702 .0021 26.3920 46.62 

 74 12.0723 8.3370 .0022 26.3920 46.62 

 75 13.1191 8.5113 .0025 26.3920 46.62 

 76 14.1658 8.6733 .0027 26.3920 46.62 

 77 15.3753 8.8475 .0029 26.3920 46.62 

 78 16.7325 9.0288 .0032 26.3920 46.62 

 79 18.0897 9.1973 .0035 26.3920 46.62 

 80 19.4469 9.3547 .0037 26.3920 46.61 

 81 21.0820 9.5316 .0041 26.3920 46.61 
93 [Section 6 Contents of the Output Files]

Table35 OILENS Model Output--NAPL Lens Description

Purpose: A summary of the NAPL lens configuration.

Column Column Heading Contents

1 Step The number of time steps completed.

2 Time The time in days since the beginning of the

simulation.

3 Lens Height The height in meters of the NAPL lens above the

spreading zone.

4 Lens Radius The radius in meters of the NAPL lens.

5 Lens Volume The volume of NAPL in the lens in cubic meters.

6 Residual Volume The volume of NAPL in cubic meters trapped at

residual above and below the lens

7 Volume Losses The cumulative volume of NAPL lost to dissolution

in cubic meters.

8 Cumulative Inflow The cumulative volume inflow of NAPL to the lens

in cubic meters. 

9 Percent Volume Error The percent error in calculated NAPL volume as

compared with the cumulative NAPL inflow to the

lens. This volume balance does not include NAPL

in the vadose zone. 
[Section 6 Contents of the Output Files] 94

 **************************************************

 * OILENS MODEL OUTPUT--OIL LENS DESCRIPTION *

 **************************************************

 Benzene transport from 1500 gal gasoline spill 

 1.15% benzene in gasoline 

 sandy soil, properties from Carsel and Parrish 

 LENS LENS LENS RESIDUAL VOLUME CUM. PERCENT

 TIME HEIGHT RADIUS VOLUME VOLUME LOSSES INFLOW VOLUME

 STEP (DAYS) (METERS) (METERS) (CU.M.) (CU.M.) (CU.M.) (CU.M.) ERROR

==============================================================================

 *** OIL FILLING CAPILLARY FRINGE

 *** TIME = 24.6391

 *** OIL SATURATION IN LENS = .3260

 *** CAPILLARY FRINGE OIL THICKNESS = .0100

 85 24.90 .0000 2.00 .02 .00 .00 .02 .20

 93 25.01 .0011 2.02 .02 .00 .00 .02 .14

 95 25.13 .0022 2.05 .03 .00 .00 .03 .11

 96 25.27 .0035 2.08 .04 .00 .00 .04 .08

 97 25.42 .0047 2.10 .05 .00 .00 .05 .06

 98 25.68 .0069 2.15 .07 .00 .00 .07 .03

 102 25.79 .0077 2.17 .08 .00 .00 .08 .03

 115 25.92 .0086 2.20 .08 .00 .00 .08 .03

 118 26.05 .0096 2.22 .09 .00 .00 .09 .02

 120 26.21 .0107 2.25 .10 .00 .00 .10 .02

{Intermediate results omitted}

 241 807.00 .0045 16.35 1.99 .58 .09 2.66 .04

 242 827.00 .0044 16.44 1.99 .59 .09 2.67 .05

 243 847.00 .0042 16.52 1.98 .60 .09 2.67 .06

 244 867.00 .0041 16.59 1.97 .60 .10 2.67 .07

 245 887.00 .0040 16.67 1.97 .61 .10 2.68 .08

 246 907.00 .0039 16.74 1.96 .62 .10 2.68 .10

 247 927.00 .0038 16.81 1.96 .62 .11 2.68 .11

 248 947.00 .0036 16.87 1.95 .63 .11 2.69 .13

 249 967.00 .0035 16.94 1.95 .63 .11 2.69 .14

 250 987.00 .0035 17.00 1.94 .64 .12 2.69 .16

 251 1007.00 .0034 17.05 1.94 .64 .12 2.69 .18

 252 1027.00 .0033 17.11 1.93 .65 .12 2.70 .19

 253 1047.00 .0032 17.16 1.93 .65 .13 2.70 .21

 254 1067.00 .0031 17.21 1.92 .65 .13 2.70 .23

 255 1087.00 .0030 17.26 1.92 .66 .13 2.70 .25

 256 1107.00 .0030 17.31 1.91 .66 .14 2.71 .27
95 [Section 6 Contents of the Output Files]

Table 36 OILENS Model Output--Aqueous Contaminants

Purpose: A summary of the OILENS output for the chemical constituent of the hydrocarbon.

Column Column Heading Contents

1 Time The time in days since the beginning of the

simulation.

2 Species Radius The effective radius for the constituent in meters.

3 NAPL Dissolution The dissolution rate of the NAPL in kilograms per

day.

4 Species Dissolution The dissolution rate of the constituent in kilograms

per day.

5 Species Dissolution The cumulative mass of the constituent dissolved

in kilograms.

6 Mass Degraded The cumulative mass of the constituent degraded

in kilograms.

7 Mass Remaining The mass of the constituent remaining in the lens

in kilograms.

8 Water Concentration The water phase concentration in milligrams per

liter of the constituent in contact with the ground

water.

9 Percent Mass Balance Error The calculated percent error in the constituent

mass, based on the mass influx to the lens.
[Section 6 Contents of the Output Files] 96

 **************************************************

 * OILENS MODEL OUTPUT--AQUEOUS CONTAMINANTS *

 **************************************************

 Benzene transport from 1500 gal gasoline spill 

 1.15% benzene in gasoline 

 sandy soil, properties from Carsel and Parrish 

 SPECIES OIL SPECIES SPECIES MASS MASS WATER P.C.

 TIME RADIUS DISSOL. DISSOL. DISSOL. DEGRADED REMAINING CONC. MASS

 (DAYS) (M) (KG/D) (KG/D) (KG) (KG) (KG) (MG/L) ERROR

==============================================================================

25.83 2.00 .525E-02 .551E-04 .00 .00 .00 .12 .00

25.96 2.03 .531E-02 .131E-02 .00 .00 .07 2.80 .00

26.12 2.06 .540E-02 .269E-02 .00 .00 .15 5.60 .00

26.29 2.09 .550E-02 .387E-02 .00 .00 .24 7.87 .00

26.40 2.10 .556E-02 .450E-02 .00 .00 .29 9.05 .00

26.52 2.13 .563E-02 .517E-02 .00 .00 .35 10.24 .00

26.65 2.15 .571E-02 .579E-02 .00 .00 .41 11.27 .00

26.79 2.17 .579E-02 .645E-02 .00 .00 .48 12.33 .00

26.96 2.20 .589E-02 .713E-02 .00 .00 .56 13.36 .00

27.15 2.24 .600E-02 .782E-02 .01 .00 .65 14.34 .00

27.36 2.27 .613E-02 .851E-02 .01 .00 .75 15.24 .00

27.58 2.31 .626E-02 .920E-02 .01 .00 .85 16.07 .00

27.81 2.34 .641E-02 .983E-02 .01 .00 .96 16.77 .00

28.06 2.39 .655E-02 .105E-01 .01 .00 1.07 17.44 .00

{Intermediate results omitted}

607.0 15.09 .102 .647E-02 20.53 .00 .50 .64 .00

627.0 15.22 .104 .585E-02 20.65 .00 .45 .57 .00

647.0 15.35 .105 .530E-02 20.76 .00 .40 .51 .00

667.0 15.47 .106 .483E-02 20.87 .00 .36 .46 .00

687.0 15.58 .108 .442E-02 20.96 .00 .33 .41 .00

707.0 15.69 .109 .406E-02 21.04 .00 .30 .38 .00

727.0 15.80 .110 .375E-02 21.12 .00 .27 .34 .00

747.0 15.90 .111 .347E-02 21.19 .00 .25 .31 .00

767.0 16.00 .112 .323E-02 21.26 .00 .23 .29 .00

787.0 16.09 .113 .302E-02 21.32 .00 .21 .27 .00

807.0 16.18 .114 .283E-02 21.38 .00 .20 .25 .00

827.0 16.26 .115 .267E-02 21.44 .00 .19 .23 .00

847.0 16.34 .116 .252E-02 21.49 .00 .17 .22 .00

867.0 16.42 .117 .238E-02 21.54 .00 .16 .21 .00

887.0 16.49 .118 .226E-02 21.58 .00 .15 .19 .00

907.0 16.56 .119 .216E-02 21.63 .00 .15 .18 .00

927.0 16.63 .120 .206E-02 21.67 .00 .14 .17 .00

947.0 16.69 .120 .197E-02 21.71 .00 .13 .17 .00

967.0 16.76 .121 .189E-02 21.75 .00 .13 .16 .00

987.0 16.82 .122 .181E-02 21.79 .00 .12 .15 .00

1007. 16.88 .122 .175E-02 21.82 .00 .11 .14 .00

1027. 16.93 .123 .168E-02 21.86 .00 .11 .14 .00

1047. 16.98 .124 .163E-02 21.89 .00 .11 .13 .00

1067. 17.04 .124 .157E-02 21.92 .00 .10 .13 .00

1087. 17.09 .125 .152E-02 21.95 .00 .10 .12 .00

1107. 17.13 .125 .148E-02 21.98 .00 .09 .12 .0
97 [Section 6 Contents of the Output Files]

Table 37 Saturation and Concentration Profile

Purpose: A summary of the saturations and concentrations in the vadose zone.

Column Column Heading Contents

1 Depth The depth in meters.

2 Saturation The NAPL phase saturation.

3 Concentration (water) The dissolved constituent concentration in the

water phase in milligrams per liter.

4 Dissolved NAPL Concentration The dissolved NAPL concentration in the water

phase in milligrams per liter.

NOTE: After an NAPL lens forms this profile is truncated at the top of the NAPL lens. A radial profile of the

NAPL lens is then produced.

 SATURATION AND CONCENTRATION PROFILE AT 25.0000

 **************************************************

 Benzene transport from 1500 gal gasoline spill 

 1.15% benzene in gasoline 

 sandy soil, properties from Carsel and Parrish 

 DEPTH SAT. CONC.(WATER) DISSOL. NAPL CONC

 =====================================================

 .0000 .0500 .0000 10.0000

 .0000 .0500 .0000 10.0000

 .0001 .0500 .0000 10.0000

 .0006 .0500 .0000 10.0000

 .0014 .0500 .0000 10.0000

 .0024 .0501 .0000 10.0000

 .0034 .0501 .0000 10.0000

 .0042 .0501 .0000 10.0000

 .0047 .0501 .0000 10.0000

 .0049 .0501 .0000 10.0000

 .0049 .0501 26.3920 10.0000

 .0898 .0524 26.3920 10.0000

 .4360 .0618 26.3920 10.0000

 .9960 .0725 26.3920 10.0000

 1.6731 .0814 26.3920 10.0000

 2.3501 .0885 26.3920 10.0000

 2.9101 .0936 26.3920 10.0000

 3.2563 .0965 26.3920 10.0000

 3.3412 .0972 26.3920 10.0000

 3.3412 .0972 26.3920 10.0000

 3.4263 .0978 26.3920 10.0000

 3.7730 .1005 26.3920 10.0000

 4.3338 .1044 26.3920 10.0000

 5.0119 .1089 26.3920 10.0000

 5.6899 .1130 26.3920 10.0000

 6.2507 .1162 26.3920 10.0000
[Section 6 Contents of the Output Files] 98

 6.5975 .1181 26.3920 10.0000

 6.6825 .1186 26.3920 10.0000

 6.6825 .1186 26.3920 10.0000

 6.7646 .1190 26.3920 10.0000

 7.0995 .1208 26.3920 10.0000

 7.6411 .1235 26.3920 10.0000

 8.2959 .1267 26.3920 10.0000

 8.9507 .1296 26.3920 10.0000

 9.4923 .1320 26.3920 10.0000

 9.8272 .1335 26.3920 10.0000

 9.9093 .1338 26.3920 10.0000

 9.9093 .1338 .0000 10.0000

 9.9114 .1338 .0000 10.0000

 9.9196 .1338 .0000 10.0000

 9.9330 .1339 .0000 10.0000

 9.9492 .1340 .0000 10.0000

 9.9654 .1340 .0000 10.0000

 9.9787 .1341 .0000 10.0000

 9.9870 .1341 .0000 10.0000

 9.9890 .1341 .0000 10.0000

 KOPT PROFILE MASS PER UNIT AREA:

 NAPL (KG/M/M) 323.8 

 DISSOLVED NAPL (KG/M/M) .2132E-01

 CONSTITUENT (KG/M/M) 3.708 

 KOPT PROFILE TOTAL MASS:

 CONSTITUENT (KG) 46.60 

 NAPL (KG) 4069. 
99 [Section 6 Contents of the Output Files]

Table 38 Radial Profile Through the NAPL Lens

Purpose: A radial description of the NAPL lens

Column Column Heading Contents

1 Radius Radial distance in meters.

2 Current NAPL Lens--Depth of The depth in meters from the ground surface to the

Top of Lens top of the current NAPL lens.

3 Current NAPL Lens--Depth of The depth in meters from the ground surface to the

Lens Bottom bottom of the current NAPL lens.

4 Maximum Extent of NAPL Lens-- The depth in meters from the ground surface to the

Depth of Top of Lens top of the thickest lens that has occurred previous

to this time. The NAPL is trapped at the vadose

zone residual between the depths for columns 2

and 4.

5 Maximum Extent of NAPL Lens-- The depth in meters from the ground surface to the

Depth of Top of Lens bottom of the thickest lens that has occurred

previous to this time. The NAPL is trapped at the

aquifer residual between the depths for columns 3

and 5.
[Section 6 Contents of the Output Files] 100

 **************************************************

 * RADIAL PROFILE THROUGH OIL LENS

 **************************************************

 TIME = 25.0000

 LENS RADIUS = 2.0213

 DEPTH TO WATER TABLE = 10.0000

 CURRENT OIL LENS MAXIMUM EXTENT OF OIL LENS

 RADIUS DEPTH OF DEPTH OF DEPTH OF DEPTH OF 

 TOP OF LENS LENS BOTTOM TOP OF LENS LENSBOTTOM

 ========== =========== =========== =========== ===========

 .0000 9.9890 10.0025 9.9890 10.0025

 2.0000 9.9890 10.0025 9.9890 10.0025

 2.0011 9.9891 10.0024 9.9891 10.0024

 2.0021 9.9891 10.0023 9.9891 10.0023

 2.0032 9.9891 10.0023 9.9891 10.0023

 2.0043 9.9891 10.0022 9.9891 10.0022

 2.0053 9.9892 10.0021 9.9892 10.0021

 2.0064 9.9892 10.0021 9.9892 10.0021

 2.0075 9.9892 10.0020 9.9892 10.0020

 2.0085 9.9893 10.0019 9.9893 10.0019

 2.0096 9.9893 10.0018 9.9893 10.0018

 2.0107 9.9893 10.0017 9.9893 10.0017

 2.0117 9.9894 10.0017 9.9894 10.0017

 2.0128 9.9894 10.0016 9.9894 10.0016

 2.0139 9.9894 10.0015 9.9894 10.0015

 2.0149 9.9895 10.0014 9.9895 10.0014

 2.0160 9.9895 10.0012 9.9895 10.0012

 2.0171 9.9896 10.0011 9.9896 10.0011

 2.0181 9.9896 10.0010 9.9896 10.0010

 2.0192 9.9897 10.0008 9.9897 10.0008

 2.0203 9.9898 10.0006 9.9898 10.0006

 2.0213 9.9900 10.0000 9.9900 10.0000

 CUMULATIVE INFLUX TO LENS 17.35 

 KOPT AND OILENS GLOBAL MASS BALANCES

 TOTAL NAPL MASS ADDED AT BOUNDARY (KG) 4091. 

 NAPL MASS RECOVERED BY MASS BALANCE (KG) 4086. 

 PER CENT ERROR -.1285 
101 [Section 6 Contents of the Output Files]

6.2 HSSM-T Output File

The HSSM-T output file contains the items shown in Table 39.

Table 39 HSSM-T Output File Summary

Table Title Contents

Input Data Echo printing of the input parameter values.

Reduced Input Mass Flux The mass flux history used by HSSM-T. The input

mass flux is reduced to 31 values.

Aquifer Concentration History Concentration histories for each receptor location.

Benzene transport from 1500 gal gasoline spill 

 1.15% benzene in gasoline 

 sandy soil, properties from Carsel and Parrish 

 TSGPLUME

 INPUT DATA:

 ===========

 HSSM-KO INPUT DATA FILE x2bt.dat 

 HSSM-KO OUTPUT FILE x2bt.HSS 

 HSSM-T INPUT FILE x2bt.PMI 

 HSSM-T OUTPUT FILE x2bt.TSG 

 HSSM-T PLOT FILE x2bt.PMP 

 HSSM ENDING PARAMETER, KKSTOP 4

 INTERFACE FLAG D

 LONG. DISPERSIVITY = 10.00 (M)

 TRANS. DISPERSIVITY = 1.000 (M)

 VERT. DISPERSIVITY = .1000 (M)

 SEEPAGE VELOCITY = .4128 (M/D)

 POROSITY = .4300 (*)

 AQUIFER THICKNESS = 15.00 (M)

 RETARDATION FACTOR = 1.291 (*)

 P.C. MAX RADIUS = 101.0 (*)

 MIN. AQUIFER CONC. = .1000E-02 (MG/L)

 DECAY COEFFICIENT = .0000 (1/D)

 BEGINNING TIME = 100.0 (D)

 ENDING TIME = 5000. (D)

 TIME INCREMENT = 50.00 (D)
[Section 6 Contents of the Output Files] 102

 NO. OBS. WELLS = 6 (*)

 X-LOCATION Y-LOCATION

 ---------- ----------

 25.00 .0000 

 50.00 .0000 

 75.00 .0000 

 100.0 .0000 

 125.0 .0000 

 150.0 .0000 

 RECHARGE RATE = .00 (M/D)

HSSM-KO is capable of producing very large output files, which if used directly in HSSM-T would cause

HSSM-T to execute very slowly. HSSM-T extracts a reduced mass flux input history from the HSSM-KO

output contained in file *.PMI. The reduced mass flux input always contains 31 points. 

 REDUCED INPUT MASS FLUX 

 HISTORY USED FOR COMPUTATION 

 =============================

 TIME MASS FLUX

 (D) (KG/D) 

 --------- ---------

 1 25.83 .5510E-04

 2 45.56 .3551E-01

 3 65.30 .5216E-01

 4 85.03 .6225E-01

 5 104.8 .6770E-01

 6 124.5 .6990E-01

 7 163.8 .6743E-01

 8 203.2 .6015E-01

 9 242.5 .5114E-01

 10 281.9 .4203E-01

 11 321.2 .3379E-01

 12 360.5 .2685E-01

 13 399.9 .2122E-01

 14 439.2 .1675E-01

 15 478.6 .1333E-01

 16 517.9 .1057E-01

 17 557.2 .8479E-02

 18 596.6 .6845E-02

 19 635.9 .5605E-02

 20 675.3 .4661E-02

 21 714.6 .3942E-02

 22 753.9 .3387E-02

 23 793.3 .2960E-02

 24 832.6 .2628E-02

 25 872.0 .2350E-02

 26 911.3 .2138E-02

 27 950.6 .1955E-02

 28 990.0 .1801E-02

 29 1029. .1674E-02

 30 1069. .1566E-02

 31 1108. .0000 
103 [Section 6 Contents of the Output Files]

 TIME STEP TOO SMALL RELATIVE TO MASS FLUX DURATION

 MODIFIED TIME STEP = 108.2 (D)

 MAXIMUM RADIUS = 17.13 (M)

 MAX. RADIUS TIME = 1107. (D)

 RADIUS AT MAX. FLUX = 8.510 (D)

 MAX. FLUX TIME = 124.5 (D)

 EFFECTIVE RADIUS = 8.510 (M)

 EFFECTIVE AREA = 227.5 (M^2)

 PENETRATION THICKNESS = 1.979 (M)

The HSSM-T results are written out as "aquifer concentration histories" for each of the receptor points. 

These consist of times and concentrations calculated for the receptor location.

 AQUIFER CONCENTRATION HISTORIES

 ===============================

 TIME RECEPTOR LOCATION

 ( X 25.00 )

 ( Y .00 )

 ---------- ----------

 30.09 .1002E-02

 51.74 1.696 

 73.38 5.004 

 84.20 6.450 

 96.65 7.876 

 108.5 8.974 

 119.7 9.813 

 130.4 10.43 

 140.5 10.86 

 150.1 11.13 

 159.7 11.30 

 169.8 11.41 

 172.4 11.43 

 174.9 11.44 

 175.7 11.44 

 177.5 11.44 

 179.0 11.44 

 180.5 11.43 

 182.7 11.43 

 186.1 11.40 

 191.5 11.35 

 200.9 11.22 

 217.7 10.90 

 249.2 9.985 

 311.5 7.751 

 370.6 5.721 

 426.8 4.175 

 480.2 3.071 

 530.9 2.290 
[Section 6 Contents of the Output Files] 104

 579.1 1.744 

 624.8 1.358 

 668.3 1.085 

 709.6 .8893 

 748.9 .7480 

 786.2 .6436 

 821.6 .5656 

 855.2 .5060 

 887.2 .4586 

 917.5 .4216 

 946.4 .3916 

 973.8 .3665 

 999.8 .3454 

 1025. .3278 

 1048. .3128 

 1070. .3000 

 1093. .2590 

 1116. .1526 

 1138. .7703E-01

 1159. .4481E-01

 1179. .2868E-01

 1198. .1956E-01

 1216. .1398E-01

 1233. .1035E-01

 1250. .7888E-02

 1265. .6158E-02

 1280. .4906E-02

 1294. .3978E-02

 1307. .3276E-02

 1320. .2735E-02

 1332. .2312E-02

 1343. .1976E-02

 1354. .1706E-02

 1364. .1486E-02

 1374. .1306E-02

 1383. .1157E-02

 1400. .9268E-03
105 [References]

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characterization and remediation, Journal of Contaminant Hydrology, 6, 107-163, 1990.

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Technology, Robert S. Kerr Environmental Research Laboratory, U.S. Environmental Protection Agency,

EPA/600/8-90/003, March 1990.

Parker, J.C., and R.J. Lenhard, Estimation of free hydrocarbon volume from fluid levels in monitoring

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Rawls, W.J., and D.L. Brakensiek, Prediction of soil water properties for hydrologic modeling,

Proceedings of Symposium on Watershed Management, 293-299, 1985.
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processes part I: Soil water retention and Green and Ampt infiltration parameters, Transactions of the

ASAE, 26, 1747-1752.

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in the unsaturated zone, Groundwater, 28, 688-692, 1990.

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17, 467-476, 1985.

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Oil and Water Industries, 23-54, 1967.

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Management System, June, 1991.

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America Journal, 47, 3-8, 1983.

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Su, C., and R.H. Brooks, Water retention measurement for soils, Journal of the Irrigation and Drainage

Division, 105-112, 1980.

Tauxe, J.D., ShowFlow: A Practical Interface for Groundwater Modeling, Master's Thesis, The University

of Texas at Austin, 1990.

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soils, Soil Science Society of America Journal, Vol. 44, 892-898, 1980.

van Genuchten, M. Th., F.J. Leij, and S. R. Yates, The RETC Code for Quantifying the Hydraulic

Functions of Unsaturated Soils, US EPA, EPA/600/2-91/065. 

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EPA, EPA/600/6-90/004, 1990
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Wilson, J. L. and S. H. Conrad, Is physical displacement of residual hydrocarbons a realistic possibility

in aquifer restoration?, Proceedings of the NWWA/API Conference on Petroleum Hydrocarbons and

Organic Chemicals in Groundwater, Houston, November 5-7, 1984.

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Book, W. Bartok and A. F. Sarofim, eds., Wiley, New York, 1991.
109 [Appendix 1 The MS-DOS Interface]

Appendix 1 The MS-DOS Interface, HSSM-DOS

The DOS interface for HSSM is divided into the three major parts described below. All are independent

programs that can be executed separately from the DOS prompt. For the convenience of the user, a simple

menu program called HSSM-DOS can be used to run the programs in sequence. Each component of the DOS

interface is described in detail in the following sections.

1.1 The HSSM-DOS Menu program

HSSM-DOS has six options for running the components of HSSM. Running the model generally follows

the order of the menu options: creating and editing input data files with PRE-HSSM, running the simulations

with HSSM-KO and HSSM-T, and plotting the results with HSSM-PLT.

Table 40 HSSM-DOS Menu 

*********************************************

* MENU FOR HSSM *

*********************************************

1. Prepare Input Data Files RUN PRE-HSSM 

2. View Directory 

3. Run KOPT and OILENS RUN HSSM-KO 

4. Run TSGPLUME RUN HSSM-T 

5. Graph Results RUN HSSM-PLT

6. Exit 

*********************************************

ENTER SELECTION (1-6): 

The following sections introduce each portion of the DOS interface. Each of these descriptions contains

references to the sections that contain detailed information on using the interface components.

1.2 Data Entry in PRE-HSSM

PRE-HSSM is a simple interactive preprocessor for the HSSM. PRE-HSSM allows the user to create data

files by means of an interactive set of menus. The user has no need to know the structure of the data file.

Several input data sets may be created within one session of PRE-HSSM and saved in disk files for future use

by the HSSM. Also, data files created from earlier PRE-HSSM sessions may be read in and modified. The

parameter names and a brief description of their use are displayed within each menu of the preprocessor. The

data entry screens are discussed in detail in Appendix 1.8. Although this information is provided on-line, it does

not make the model self-explanatory. The user must refer to the user's guide for specific instructions on

running the model. All data entered in PRE-HSSM must be written to a file before it is used by HSSM. Any

data not saved before exiting PRE-HSSM or starting with a new data set will be lost. Minimal checking of

parameter values is done in PRE-HSSM, so the user must assure that the values are reasonable.
[Appendix 1 The MS-DOS Interface] 110

1.3 Computation by HSSM-KO and HSSM-T

The two executables, HSSM-KO and HSSM-T, perform the HSSM simulations. HSSM-KO contains the

KOPT and OILENS models and is run first. Using a previously created input data file, HSSM-KO creates a

formal output file, several plot files and, if the appropriate flags and conditions are set, the input data file for

HSSM-T. During execution, data is written into several temporary files. These files are concatenated upon

successful execution into the output and plot files. The temporary files are then deleted from the hard disk.

If HSSM-KO execution is interrupted, the temporary files remain on the hard disk. The program REBUILD can

then be used to create as many of the output files as possible. The TSGPLUME module of HSSM is run by

executing HSSM-T. This program also produces a formal output file and a plot file. Directions for use of the

DOS commands for HSSM-KO and HSSM-T are given in Appendix 1.9.

1.4 Graphing of Results in HSSM-PLT

Although much useful information is contained within the HSSM-KO and HSSM-T formal output files,

graphical display of the model results is also desirable and useful. HSSM-PLT allows the display and printing

of HSSM output. The plot files which are automatically created by HSSM-KO and HSSM-T are used by HSSMPLT to graph the output. Seven different types of graphs are available to the user. These graphs are displayed

on the screen and may be printed on several types of printers and plotters. Specific information for using

HSSM-PLT is given in appendix 1.10.

1.5 Quick Summary of the DOS Interface Commands

The following table lists the MS-DOS commands that can be used to run the HSSM without running the

HSSM-DOS menu program. The full details of the procedures are described in the following sections.

Table 41 Quick Summary of MS-DOS HSSM Commands

Command Action

For automated use of the interface:

HSSM-DOS Activates the DOS menu program which automatically executes the

commands listed below.

For manual entry of commands at the DOS prompt:

PRE-HSSM Executes the interactive input data preprocessor.

HSSM-KO name.DAT Executes the KOPT and OILENS modulates of HSSM, using the

name.DAT data set.

HSSM-T name.PMI Executes the TSGPLUME module of HSSM, using the name.PMI input

data set generated by previous execution of HSSM-KO.

HSSM-PLT Executes the interactive graphical post processor.

Note that HSSM requires a fixed set of file types for its input and output files. HSSM-T and HSSM-PLT only

function properly when the required files types are used. PRE-HSSM can be used to generate the required

file types automatically. The required files types are described in Table 15 of Section 4.7.
111 [Appendix 1 The MS-DOS Interface]

1.6 System Requirements

To use the DOS interface, the user should be generally familiar with personal computers, DOS, and the

HSSM model. Also, users are assumed to be knowledgeable about their system hardware (i.e., which output

device is connected to which port). The hardware and software requirements for using the MS-DOS interface

are listed below.

9 DOS 5.0 or higher

9 400 kilobytes of free RAM 

9 Hard drive (recommended) 

Usage of the HSSM-PLT graphics package requires the following :

9 Graphics device that is EGA, VGA, or better.

9 ANSI.SYS driver installed in the CONFIG.SYS file.

The following printers are supported:

 1) EPSON 9-pin, narrow carriage 

 2) EPSON 24-pin, LQ series, narrow carriage

 3) EPSON 24-pin, LQ series, wide carriage

 4) NEC Pinwriter, 24-pin, narrow carriage

 5) NEC Pinwriter, 24-pin, wide carriage 

 6) Okidata, 9-pin, narrow carriage 

 7) HP LaserJet/DeskJet - low res.

 8) HP LaserJet/DeskJet - medium res. 

 9) HP LaserJet/DeskJet - high res. 

10) HP PaintJet - 2 color, low res. 

11) HP PaintJet - 4 color, med res. 

12) HP PaintJet - 8 color, high res. 

13) HP PaintJet - 16 color, high res. 

14) Postscript printer 

15) HP - HPGL plotter 

16) HP LaserJet III - HPGL/2 mode 

17) Houston Instruments DM/PL plotter

The amount of available system memory may be checked by entering the DOS 5.0 MEM command. The

amount of memory available for running a DOS program will be displayed. This amount must exceed 400

kbytes in order to run HSSM-KO. Although DOS 5.0 is stated as the minimum level of DOS required to run

HSSM, earlier versions will likely be adequate; versions below 5.0 have not been tested.

1.7 Installation

The HSSM software is distributed on two high density diskettes. A backup copy of these diskettes should

be made and subsequent work should be performed from the backup copies. The distribution diskette for

HSSM-DOS (HSSM-1-d) contains the files indicated in Table 42.
[Appendix 1 The MS-DOS Interface] 112

 Table 42 Packing List of Files for the HSSM-DOS Interface

File Purpose

HSSM-DOS.EXE The DOS menu program

PRE-HSSM.EXE Interactive input data processor

HSSM-KO.EXE The KOPT and OILENS modules of HSSM

HSSM-T.EXE The TSGPLUME module of HSSM

HSSM-PLT.EXE Interactive graphical postprocessor

REBUILD.EXE A recovery program for interrupted simulations

CONFIG.PLT Hardware configuration file for HSSM-PLT.EXE

SIMPLEX1.FNT Font file for HSSM-PLT.EXE

README.TXT Read me file containing distribution information

RAOULT.EXE Utility to perform Raoult's Law Calculation

RAOULT.DAT Default data set for the RAOULT utility

SOPROP.EXE Utility to estimate soil properties with Rawls and Brakensiek's (1985) regression

equations.

NTHICK.EXE Utility to estimate NAPL thickness at the water table

The following describes how to install the model. Check the README.TXT file for information on

automated installation procedures, as they are under development as of this writing. To create the HSSM

directory enter the DOS command:

MKDIR C:\HSSM

where HSSM is the name of the HSSM-DOS subdirectory. With the HSSM-1-d diskette in drive A, copy all of

the files from the diskette into the HSSM directory with the DOS command:

COPY A:\*.* C:\HSSM

(The program can be installed from another drive, say B, by replacing "A:" in the previous command with

"B:"). The example problems and output files contained on diskette HSSM-2 should be installed into a

separate directory. Create the example problem directory by entering:

MKDIR C:\HSSM\EXAMPLE

After putting the HSSM-2 diskette into drive A, the files are copied to this directory by entering:

COPY A:\*.* C:\HSSM\EXAMPLE

Subdirectories can and should be created for each HSSM simulation. For example, to create a directory

PROJECT1, enter the command:

MKDIR C:\HSSM\PROJECT1
113 [Appendix 1 The MS-DOS Interface]

By issuing the DOS command

CD \HSSM\PROJECT1

before executing HSSM, all the input and output files for the simulation will be in C:\HSSM\PROJECT1. 

Installation of both the DOS and Windows interfaces on one machine is discussed in Appendix 9.

Once HSSM-DOS has been loaded onto your system, you must check the CONFIG.SYS file. The HSSMKO program opens a number of temporary files and CONFIG.SYS must be configured so that a sufficient

number of files may be opened. The CONFIG.SYS on your system needs to include the line

FILES = 30

(A number greater than 30 will also work.) To use HSSM from any directory add C:\HSSM to the path

statement in your AUTOEXEC.BAT file. After modifying these files you must reboot your system to allow the

change to take effect. 
[Appendix 1 The MS-DOS Interface] 114

1.8 Using the PRE-HSSM Preprocessor

The first step in running HSSM is to run the preprocessor PRE-HSSM to create and/or edit input data sets.

 PRE-HSSM is provided as a convenience to the user; its usage greatly facilitates the generation of input data

sets. For convenience, blank templates for each of these screens are provided in Appendix 12. These

templates are useful for assembling data sets and may be copied for repeated usage. Appendix 10 shows the

structure of the HSSM-KO and HSSM-T input data files for experienced users of HSSM who may wish to edit

directly their input data sets. 

 Table 43 Introductory PRE-HSSM Screen

 ***************************************************

 * *

 * PRE-HSSM VERSION 1.50 *

 * *

 * AN INTERACTIVE PREPROCESSOR FOR THE HSSM MODEL *

 * *

 * JIM WEAVER *

 * UNITED STATES ENVIRONMENTAL PROTECTION AGENCY *

 * R.S. KERR ENVIRONMENTAL RESEARCH LABORATORY *

 * ADA, OKLAHOMA 74820 *

 * DONALD COLLINGS *

 * NSI TECHNOLOGY SERVICES CORPORATION *

 * ENVIRONMENTAL SCIENCES *

 * ADA, OKLAHOMA 74820 *

 * NOV 7, 1992 *

 * *

 ***************************************************

DO YOU WANT TO READ AN EXISTING DATA FILE ?

 ENTER 0 OR <RETURN> IF NO

 ENTER 1 IF YES

 ENTER 2 TO VIEW DIRECTORY 

 ENTER 3 FOR SAMPLE INPUT DATA SET

 ENTER 4 TO EXIT THE PREPROCESSOR

 

The main screen for the PRE-HSSM preprocessor is shown in Table 43. The screen also displays the

file selection menu. The options available to the user are

0. Enter 0 or <RETURN> to create a new data set.

1. Enter 1 followed by <RETURN> to edit a previously created data set. The message

ENTER THE INPUT DATA FILE NAME

----+---*-40-character-limit*----+----* 

is written to the screen. Forty characters are allowed for the data file name. A DOS path name can be

included. If the file does not exist, the message

INPUT DATA FILE DOES NOT EXIST--REENTER

appears on the screen. If the file is not a valid HSSM input file, the message
115 [Appendix 1 The MS-DOS Interface]

INVALID INPUT DATA FILE

Stop - Program terminated.

appears and the program must be restarted.

2. Enter 2 followed by <RETURN> to view the current directory. This option executes the DOS command DIR

|MORE, so that the directory is viewed one screen at time. After completing the command the user is returned

to the file selection menu.

3. Enter 3 followed by <RETURN> to edit a sample data set. This data set is provided purely for the

convenience of the user and is not intended for application to specific problems.

4. Exit the preprocessor by entering 4 and pressing <RETURN>.

1.8.1 Saving Data to a File

Before discussing the individual PRE-HSSM data menus, the procedure for saving data to files and exiting

PRE-HSSM is explained. As previously noted, all data entered into PRE-HSSM must be written to a file before

exiting or restarting PRE-HSSM, otherwise all entries and/or changes will be lost. The user is prompted for

saving data before exiting or restarting.

 Table 44 Writing Data Files

WRITE THE INPUT VALUES TO A FILE ?

*****************************************

***ANY DATA ENTERED IN PRE-KOPT MUST ***

***BE WRITTEN TO A FILE BEFORE EXITING***

*****************************************

 ENTER 0 OR <RETURN> IF NO

 ENTER 1 IF YES

The screen shown in Table 44 prompts the user to decide whether or not to write the current data file to a disk

file. This screen is displayed after the user has chosen no changes in the main menu (Table 47). To save the

data to a disk file, enter 1; otherwise, press <RETURN>.
[Appendix 1 The MS-DOS Interface] 116

 Table 45 Selecting File Names

CHOOSE A FILE TO WRITE TO:

CURRENT INPUT FILE NAME: sample.dat

CURRENT OUTPUT FILE NAME: <<NONE>>

 ENTER 0 OR <RETURN> TO EXIT WITHOUT WRITING TO ANY FILE

 ENTER 1 TO CHANGE THE DATA FILE NAME

 ENTER 2 TO OVERWRITE THE CURRENT INPUT FILE

When 1 is entered on Table 44, Table 45 appears, displaying the current input file name and the current output

file name, and gives the user three options.

Enter 0 or <RETURN> to exit without writing any data file.

Enter 1 to change the name of the data file and write the data to that file.

Enter 2 to write the data to the current input file name.

Table 46 Exiting PRE-HSSM

DO YOU WANT TO CONTINUE ?

 ENTER 0 OR <RETURN> TO CONTINUE WITH THE SAME DATA SET

 ENTER 1 TO RESTART WITH A NEW DATA SET

 ENTER 2 TO EXIT THE PREPROCESSOR

After choosing whether or not to write a disk file, the user is prompted whether to continue PRE-HSSM or to

exit (Table 46).

0. Enter 0 or <RETURN> to continue with the same data set that has just been created or edited. This option

returns control to the PRE-HSSM Main Menu (Table 47).

1. Enter 1 and press <RETURN> to restart PRE-HSSM with a new data set. This option returns control to the

Introductory PRE-HSSM Screen (Table 43). 

2. Enter 2 and press <RETURN> to exit PRE-HSSM. By selecting this option the user is returned to the DOS

prompt. Data previously written to files is retained on the disk; data not previously written to files is lost.
117 [Appendix 1 The MS-DOS Interface]

1.8.2 PRE-HSSM Main Menu Commands

Table 47 lists the names of the PRE-HSSM data entry screens. Most of the lines in the main menu

correspond to one line in the data file used by the model. The following options are available for use with this

menu and each of its sixteen sub-menus:

1. Enter 0 or press <RETURN> for no changes to any data item.

2. Select a line number to view/edit the data fields associated with it by entering a line number from 1 to 16 and

pressing <RETURN>.

3. Enter -1 and press <RETURN> to view/edit all the sub-menus in sequence. This option will direct PREHSSM to go through each of the sub-menus. Once started, this option must be followed through to

completion. There is no way to escape out of the sequence without losing all data entered during the session.

Table 47 PRE-HSSM Main Menu

 HSSM INPUT DATA SCREENS

 1......SIMULATION CONTROL SWITCHES

 2......OUTPUT AND PLOT FILE NAMES

 3......RUN TITLE

 4......MATRIX PROPERTIES

 5......HYDROLOGIC PROPERTIES

 6......HYDROCARBON (NAPL) PHASE PROPERTIES

 7......CAPILLARY SUCTION APPROXIMATION

 8......NAPL FLUX, VOLUME OR CONSTANT HEAD

 9......DISSOLVED CONSTITUENT CONCENTRATION

 10.....EQUILIBRIUM LINEAR PARTITION COEFFICIENTS

 11.....OILENS SUB-MODEL.1

 12.....OILENS SUB-MODEL.2

 13.....SIMULATION PARAMETERS

 14.....NUMBER OF PROFILES

 15.....PROFILE TIMES

 16.....TSGPLUME INPUT PARAMETERS

CHANGE OR VIEW INPUT DATA VALUES ?

 ENTER 0 OR <RETURN> FOR NO CHANGES

 ENTER <LINE NUMBER> FOR A SINGLE LINE

 ENTER -1 FOR ALL LINES IN SEQUENCE
[Appendix 1 The MS-DOS Interface] 118

1.8.3 Creating and Editing HSSM Data Sets

The following pages document each data entry menu. They are listed in the order they would appear if

the user had chosen the -1 option on the PRE-HSSM main menu (review all items in the menu). The data

items are grouped primarily by function within the model. As a result some parameters appear on screens to

which, at first glance, they do not belong. This arrangement is due to the modularity of the code.

Each screen follows the following format: Each data item is numbered, and followed by its HSSM variable

name is a short description of its use and its current value. To change a value, enter the item number and

press <RETURN>, then enter the new value and press <RETURN> again. Each time a single modification

or a series of modifications is completed, the preprocessor displays the new data for inspection and approval.

Each data item may be modified any number of times while the screen is displayed, but only the values

displayed just before the screen is exited are saved in main memory (RAM). After modifying all desired data

items, the complete data set may be written to a disk file. Until this time all data is stored in RAM only, and will

be lost if PRE-HSSM is exited or aborted.

The following units are used in HSSM and are listed with their usage and abbreviation. Care must be

taken to assure that the inputs are converted to this set of units.

Table 48 Required Units for HSSM

Quantity Unit Abbreviation Used in

PRE-HSSM

Time day D

Depth meter M

Dynamic viscosity centipoise CP

Density grams/cubic centimeter G/CC

Surface tension dyne/centimeter DYNE/CM

Concentration milligrams/liter MG/L

Soil-water partition liters/kilogram L/KG

coefficient

Dispersivity meters M

Various dimensionless *
119 [Appendix 1 The MS-DOS Interface]

Table 49 Simulation Control Switches

 SCREEN 1. SIMULATION CONTROL SWITCHES

 1 IWR PRINTING SWITCH

 O NO OUTPUT FILES PRODUCED

 1 ALL OUTPUT FILES PRODUCED

 2 IKOPT ECHO PRINT ONLY (IF IWR = 1)

 0 READ AND ECHO PRINT DATA ONLY

 1 RUN KOPT MODEL

 3 ICONC DISSOLVED CONSTITUENT SWITCH

 0 NO CONSTITUENT PRESENT

 1 SIMULATE DISSOLVED CONSTITUENT

 4 ILENS OILENS SWITCH

 0 DO NOT RUN OILENS MODEL

 1 RUN OILENS MODEL

 5 ITSGP TSGPLUME SWITCH

 0 DO NOT CREATE TSGPLUME MODEL INPUT FILE

 1 CREATE TSGPLUME MODEL INPUT FILE

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the integer printing switch (0 or 1). Entering 0 causes no output to be produced, so normally 1 will be

entered for this variable.

2. Enter the integer KOPT/echo printing switch (0 or 1). Entering 0 will echo print the input data set without

performing a simulation (if IWR is set to 1). Entering 1 will cause the program to read the data and run the

KOPT module of HSSM. KOPT simulates the infiltration of the NAPL through the vadose zone. KOPT must

be run in order to run OILENS or TSGPLUME.

3. Enter the dissolved constituent switch (0 or 1). Entering 0 simulates NAPL phase flow without a dissolved

constituent. Entering 1 allows the simulation of a dissolved constituent within the NAPL phase. TSGPLUME

requires a dissolved constituent.

4. Enter the integer OILENS switch (0 or 1). Entering 0 will prevent the OILENS model from running. Entering

1 will allow the OILENS model to run, if the NAPL reaches the water in sufficient quantity. 

5. Enter the TSGPLUME data creation switch (0 or 1). Entering 0 will prevent HSSM-KO from creating the

TSGPLUME (HSSM-T) input data set. Entering 1 will allow HSSM-KO to create an input data set for

TSGPLUME, if there is a dissolved constituent which reaches the water table.

In order for HSSM-T and the HSSM-PLT post processor to function properly, a specified set of file types

(the three-character extension to the file name following the period; i.e., name.TYP) is required to be used by

HSSM-KO. The PRE-HSSM interface automatically assigns the required file names whenever a data set is

saved to the disk.
[Appendix 1 The MS-DOS Interface] 120

 Table 50 Run Title

 

 SCREEN 3. RUN TITLE

 1.. BENZENE TRANSPORT FROM 1500 GAL GASOLINE SPILL 

 2.. 1.15% BENZENE IN GASOLINE

 3.. SANDY SOIL, PROPERTIES FROM CARSEL AND PARISH

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

The Run Title Screen (Table 50 ) allows the user to enter three lines of up to 50 characters each of information

related to the data set. A 50-character ruler bar is displayed for convenience when entering the title. The

information from this screen is reproduced as headings throughout the output files generated by the

KOPT/OILENS.

9 Any one line may be modified by entering its number at the prompt, or

9 All three lines may be modified in succession by entering -1 at the prompt. 

9 The current title is accepted by pressing <RETURN> or entering 0.
121 [Appendix 1 The MS-DOS Interface]

Table 51 Porous Medium Properties

 SCREEN 4. MATRIX PROPERTIES

 1 WKS SATURATED VERTICAL HYDRAULIC

 CONDUCTIVITY (M/D) 7.1000

 2 RKS RATIO OF HORIZONTAL TO VERTICAL

 CONDUCTIVITY (*) 2.5000

 3 KRF RELATIVE PERMEABILITY SELECTION 2

 INDEX

 1 = BURDINE--BROOKS/COREY

 2 = BURDINE--EQUIVALENT VAN GENUCHTEN

 4 XLAMB PORE SIZE INDEX (*) 2.6800

 IF KRF = 1, LAMBDA

 IF KRF = 2, N

 5 ETA POROSITY (*) 0.4300

 6 SWR RESIDUAL WATER SATURATION (*) 0.1000

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the value of the saturated vertical water phase hydraulic conductivity, K , in meters per day. Saturated s

hydraulic conductivity is one of the most important parameters of the model. Estimation of this parameter is

described in Appendix 3.1 "Soil Properties." This appendix contains data from two tabulations of soil properties.

2. Enter the ratio of the horizontal saturated water phase conductivity to the saturated vertical water phase

hydraulic conductivity. Anisotropy is not treated directly in HSSM, rather the model uses the product of the ratio

RKS and the saturated vertical conductivity, K , to determine the hydraulic conductivity of the aquifer. This latter s

conductivity is also used for determining the effective conductivity to the NAPL for the lens spreading. The

relationships between the conductivities are summarized inTable 52.

Table 52 Summary of Hydraulic Conductivity Relationships

Model and Region Hydraulic Conductivity Used HSSM Variables

Vadose zone (KOPT) Vertical Ks

NAPL lens (OILENS) Horizontal K *RKS s

Aquifer (TSGPLUME) Horizontal K *RKS s

3. Select the capillary pressure model by entering 1 for Brooks and Corey or 2 for the equivalent van

Genuchten. 
Sw&Swr

1&Swr

' hce

hc

8

2w & 2wr

2m & 2wr

' 1

1 % (" hc )

n m

[Appendix 1 The MS-DOS Interface] 122

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Choose the capillary pressure model to be used in HSSM calculations. Further information on the selection

of the model parameters is given in Appendix 3.1 "Soil Properties." Either Brooks and Corey or van Genuchten

model parameters may be used. The appendix contains typical parameter values for each of these models.

Although the HSSM is designed to use the Brooks and Corey model, van Genuchten model parameters may

be entered as input. The van Genuchten model parameters are converted to approximately equivalent Brooks

and Corey model parameters by a procedure developed by Lenhard et al. (1989). 

For the Brooks and Corey Model:

The Brooks and Corey (1964) model equation which describes the relationship between saturation S and w

capillary head h is c given by

where the residual water saturation, S , the air wr ce entry head ,h , and the pore size distribution index, 8, are fitting

parameters.

Brooks & Corey's 8

The parameter 8 is called the pore size distribution index, and is determined either by fitting the Brooks and

Corey model to the water/air capillary pressure curve P (S ) by a procedure outlined by Brooks and c w Corey

(1964) or by non-linear curve fitting (e.g., van Genuchten et al., 1991).

For the van Genuchten Model:

NOTE: selecting the van Genuchten model causes HSSM to calculate approximately equivalent Brooks and

Corey model parameters as described in Appendix 4.

van Genuchten's model is defined by

where

2 = volumetric water content w

h = capillary head with units of m c

2 = volumetric residual water content wr

2m = volumetric maximum water content

" = a parameter with units of m-1

n = a parameter

 m = a parameter (taken as a simple function of n)
Sw & Swr

1 & Swr

123 [Appendix 1 The MS-DOS Interface]

(22)

For HSSM the reduced water content term (the left hand side of van Genuchten's model is taken to be equal

to 

where the maximum water saturation, 2m, is assumed to equal the porosity. The parameters of van

Genuchten's model can be fitted to measured data by using a fitting program like RETC (van Genuchten et al.,

1991).

4. Enter either the Brooks and Corey 8 or van Genuchten n, depending on the capillary pressure curve model

selected.

5. Enter the porosity, 0

6. Enter the residual water saturation, which is determined from the measured capillary pressure curve.
2.74 x 10&4 m

d ' 10 cmyr

m

100 cm

yr

365 d

[Appendix 1 The MS-DOS Interface] 124

(23)

Table 53 Hydrologic Properties

 SCREEN 5. HYDROLOGIC PROPERTIES

 1 WMU DYNAMIC VISCOSITY OF WATER (CP) 1.0000

 2 WRHO DENSITY OF WATER (G/CC) 1.0000

 3 IRT RECHARGE INPUT TYPE 1

 1 = FLUX SPECIFIED

 2 = SATURATION SPECIFIED

 4 QW/SWMAX CONSTANT WATER FLUX OR SAT. 0.0140

 FLUX: (M/D)

 SATURATION: (*)

 5 XMKRW MAX. WATER RELATIVE PERMEABILITY

 DURING INFILTRATION (*) 0.5000

 6 WTABLE DEPTH TO WATER TABLE (M) 10.0000

 

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the dynamic viscosity of water, μ , in centipoise (cp). At 20 C the viscosity of water is 1.0 cp. w

o

2. Enter the density of water, D in g/cm . At 20 C density of pure water is 1 g/cm . w

3o 3

3. Enter the type of recharge condition desired. Recharge can be specified either by specifying a recharge rate

or be specifying a vadose zone residual water saturation. 

Enter 1 to select a recharge flux for the recharge input:

Enter 2 to select a vadose zone water saturation.

4. Enter the water flux, q , in m/d or the saturation, S (*), depending on the rainfall input type selected in w w(max)

item 3.

When annual recharge is chosen for the recharge input:

The value entered is the average annual recharge rate. For example, with an annual recharge rate of 10 cm/yr

the value entered is:

HSSM-KO calculates the water saturation (fraction of the pore space that is filled with water) from the recharge

rate. Large recharge rates may cause the available pore space to be completely filled with water, allowing no

NAPL to infiltrate. If such conditions are encountered an error message is written to the screen.
Kew ' Ks w krw

125 [Appendix 1 The MS-DOS Interface]

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When water saturation is chosen for the recharge input:

If 35% of the pore space is filled by water, then 0.35 is entered here. Using the other set of units: if the

volumetric moisture content is 0.14 and the porosity is 0.40, then the equivalent saturation of 0.35 is entered

here.

Typically the moisture content at or above the field capacity would be used here, after converting to saturation.

The relationship between volumetric moisture content, 2 , porosity, 0, and saturation, S , is given by 2 = 0S . w w ww

 From the saturation input, HSSM-KO calculates the associated water flux.

5. Enter the maximum water relative permeability during infiltration, k . Since air is normally trapped during rw(max)

infiltration, the effective hydraulic conductivity of the soil will be less than the saturated conductivity. The

relationship between effective conductivity to water, K , and saturated conductivity to water, K is given by ew sw

where k is called the relative permeability to rw water. The relative permeability equals zero when the saturation

is at or below residual, and equals one when the porous medium is completely saturated with water.

To account for trapping of the air phase, the maximum effective conductivity is restricted by the value set for

k . Typical values range from 0.4 to 0.6 (Bouwer 1966); 0.5 is often used (e.g., Brakensiek et al., 1981). rw(max)

The maximum water saturation is then determined from the k function that is used by HSSM. The remainder rw

of the pore space is assumed to be filled with trapped air. The water saturation calculated from k is then rw(max)

discarded, as only the trapped air saturation is used by the model.

5. Enter the depth to the water table from the release point in meters. The release point is usually at the

ground surface. 
EAPI ' 141.5

sp.gr. & 131.5

Kso ' Ksw

μw

μo

Do

Dw

[Appendix 1 The MS-DOS Interface] 126

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Table 54 Hydrocarbon (NAPL) Phase Properties

SCREEN 6 NAPL PHASE PROPERTIES

 1 PMU DYNAMIC VISCOSITY OF NAPL (CP) 0.4500

 2 PRHO NAPL DENSITY (G/CC) 0.7200

 3 SPR RESIDUAL OIL SATURATION (*) 0.0500

 4 IAT APPLICATION TYPE 1

 1 = FLUX SPECIFIED

 2 = VOLUME/AREA SPECIFIED

 3 = CONSTANT HEAD PONDING

 4 = VARIABLE PONDING AFTER

 CONSTANT HEAD PERIOD

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

 

1. Enter the NAPL phase viscosity, μ , in centipoise. Typical NAPL viscosities are given below in (26). o

2. Enter the NAPL phase density, Do, in g/cm . For OILENS simulations, the NAPL density must be less than 3

that of water. Densities greater than water may be used if no OILENS simulation is performed. Some typical

NAPL densities are given below in Table 55.

Hydrocarbon densities are sometimes expressed by the degrees API (Perry and Chilton, 1973) scale adopted

by the American Petroleum Institute. Degrees API is defined by

where sp.gr. is the specific of the NAPL measured at 70E F divided by the specific gravity of water measured

at 60E F. The degrees API scale runs from 0.0 to 100.0 and covers a range of specific gravities from 1.076

to 0.6112.

The densities and viscosities of the NAPL and water phases are used by HSSM-KO to estimate the saturated

hydraulic conductivity to the NAPL phase, K , by so

where K is the saturated hydraulic conductivity, μ and μ are the water and oil viscosities, and sw w o w o D and D are

the respective densities.
127 [Appendix 1 The MS-DOS Interface]

 Table 55 NAPL Densities and Viscosities at 20E C

Liquid Density Viscosity

g/cm cp 3

Gasoline 0.75 0.45

Water 1.00 1.00

No. 2 Fuel Oil 0.87 5.9

Transmission Fluid 0.89 80

3. Enter the residual NAPL phase saturation for the vadose zone, S . By definition, the NAPL phase does not orv

flow at saturations less than or equal to residual. In this model, the residual NAPL saturation is assumed to

be a known constant. Ideally, this would be obtained by measuring the NAPL/air capillary pressure curve in

the presence of the amount of water filling a portion of the pore space. Treating the residual NAPL saturation

as a constant is acknowledged to be an assumption, as in actuality the NAPL residual saturation may vary with

the hydraulic gradient and with time as the NAPL weathers (Wilson and Conrad, 1984.) Typically the residual

NAPL saturation in the vadose zone is less than that for the aquifer (with the same media properties). Typical

hydrocarbon residual saturations vary from 0.10 to 0.20 in the vadose zone, and from 0.15 to 0.50 in the

saturated zone (Mercer and Cohen, 1990). These values correspond more closely to "specific retention", as

the term is used in ground water hydrology, rather than true residuals at large capillary pressure values. A

different residual oil phase saturation for the saturated zone may be entered on the "NAPL Lens Sub-Model

Parameters. 1" menu (Table 64, item 6).

4. Enter the NAPL phase boundary condition for the simulation. Four options are provided for specifying the

way in which the NAPL enters the subsurface. Not all of the release parameters are needed for each release

option; those necessary are noted on the data screens.

Release Options

 Specified flux

Specifies a constant flux of NAPL, corresponding to a known rate of application of NAPL to the

ground surface for a specified time interval. Excess NAPL is assumed to run off at the surface.

 Specified volume/area

Specifies a volume per unit area of NAPL applied over a certain depth. This results in a fixed

volume applied instantaneously, corresponding to a land treatment system or a landfill.

 Constant head ponding

Specifies constant head ponding for a specified duration. The ponding depth abruptly goes

to zero at the end of the release. This condition is used to simulate a hydrocarbon tank rupture

which is contained within a berm, for example.
[Appendix 1 The MS-DOS Interface] 128

 Variable ponding after a period of constant head ponding

Specifies constant head ponding for a specified duration, followed by a gradual decrease to

zero head as the NAPL infiltrates.

The values of the necessary parameters are then entered in Table 58 , Table 59, Table 60, or Table 61. 
129 [Appendix 1 The MS-DOS Interface]

Table 56 Capillary Suction Approximation Parameters

 

 SCREEN 7. CAPILLARY SUCTION APPROXIMATION PARAMETERS

 1 HWE AIR ENTRY HEAD (M) 4.5000

 2 WSIG WATER SURFACE TENSION (DYNE/CM) 65.0000

 3 OSIG NAPL SURFACE TENSION (DYNE/CM) 35.0000

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

 

1. If the Brooks and Corey model has been selected, enter the absolute value of the air entry head, h , in ce

meters. This value is determined as a parameter from the water/air capillary pressure curve (see matrix

properties, Table 51). If the van Genuchten model has been selected, enter " in meters . -1

2. Enter the water/air surface tension, Faw, in dyne/cm. At 20EC the surface tension of pure water is 72.8

dyne/cm. A lower value, say 65 dyne/cm, may be appropriate for soils and/or contaminated sites.

3. Enter the NAPL/air surface tension, F , in dyne/cm. Table 57 shows typical surface tension values for oa

several petroleum products.

Table 57 Surface Tensions of Several

Fuels (Wu and Hottel, 1991)

Liquid Surface tension

(dyne/cm)

gasoline 26

kerosene 25-30

gas oil 25-30

lubricating fractions 34

fuel oils 29-32
[Appendix 1 The MS-DOS Interface] 130

 Table 58 Hydrocarbon (NAPL) Flux Boundary Condition

 SCREEN 8A. NAPL FLUX BOUNDARY CONDITION

 

 1 QP NAPL FLUX (M/D) 0.4522

 2 TPB NAPL EVENT BEGINNING TIME (D) 0.0000

 3 TPE NAPL EVENT ENDING TIME (D) 1.0000

 

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the constant NAPL flux, q , in meters per day. NAPL phase fluxes in excess of the maximum effective o

NAPL phase conductivity are assumed to run off.

2. Enter the beginning time of the NAPL release in days, usually this is zero.

3. Enter the ending time of the NAPL release in days.

Table 59 Hydrocarbon (NAPL) Volume Per Unit Area Boundary Condition

 SCREEN 8B. NAPL VOLUME/AREA BOUNDARY CONDITION 

 

 1 PVOL NAPL VOLUME/AREA (M) 0.4000

 2 DPL LOWER DEPTH OF NAPL ZONE (M) 0.5000

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the volume of the NAPL phase per unit surface area that is either placed in a land treatment facility or

a landfill (cubic meters/square meter). 

2. Enter the depth of the bottom of the contaminated zone, d (meters). pl
131 [Appendix 1 The MS-DOS Interface]

 Table 60 Hydrocarbon (NAPL) Constant Head Ponding Boundary Condition

 SCREEN 8C. CONSTANT NAPL HEAD BOUNDARY CONDITION 

 

 1 TPB NAPL EVENT BEGINNING TIME (D) 0.0000

 2 TPE NAPL EVENT ENDING TIME (D) 1.0000

 3 HS CONSTANT HEAD FOR IAT = 3 (M) 0.2000

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the beginning time of the NAPL release in days, usually this is zero.

2. Enter the ending time of the NAPL release in days.

3. Enter the depth of constant head ponding, H , in meters. s

 Table 61 Hydrocarbon (NAPL) Variable Head Ponding Boundary Condition

 SCREEN 8D. VARIABLE HEAD PONDING BOUNDARY CONDITION

 

 1 TPB NAPL EVENT BEGINNING TIME (D) 0.0000

 2 TPE END OF CONSTANT HEAD PERIOD (D) 1.0000

 3 HS CONSTANT HEAD FOR TPB TO TPE (M) 0.2000

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the beginning time of the NAPL release in days, usually this is zero.

2. Enter the ending time of the NAPL release in days.

3. Enter the depth of constant head ponding, H , in meters. s
Cb ' fb Dg

Cb (g/cm 3 ) ' 1.14%

100 (0.73 g/cm 3

) ' 0.0083g/cm 3

Cb (mg/L ) ' Cb (g/cm 3 ) 1000 cm 3

L

1000 mg

g ' 8300mg/L

[Appendix 1 The MS-DOS Interface] 132

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Table 62 Dissolved Constituent Concentration

 SCREEN 9. DISSOLVED CONSTITUENT CONCENTRATION

 1 COINI INITIAL CONCENTRATION IN NAPL (MG/L) 8208.0000

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the initial concentration of the chemical constituent in the NAPL phase, c , in mg/L. HSSM idealizes o(ini)

the multiphase/multicomponent system as consisting of an "NAPL" phase that contains some small fraction

of a dissolved constituent. The dissolved constituent can partition between the fluids and the solid. The

concentration in the NAPL of the chemical is entered here. For example benzene composes 1.14% by mass

of the idealized gasoline mixture used by Baehr & Corapcioglu (1987). The initial benzene (the dissolved

constituent) concentration in gasoline (the NAPL or "oil") is given by

where C is the concentration of benzene in the gasoline, f , is the mass fraction of benzene in gasoline, b b Dg is

the density of the gasoline. Therefore

Converting the gasoline concentration to the required units gives
co ' Ko cw

cs ' Kd cw

Kd ' f

o c Ko c

133 [Appendix 1 The MS-DOS Interface]

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(31)

(32)

Table 63 Equilibrium Linear Partition Coefficients

 SCREEN 10. EQUILIBRIUM LINEAR PARTITION COEFFICIENTS

 1 XXKO NAPL/WATER (*) 311.0000

 2 XXKS SOLID/WATER (L/KG) 0.8300

 3 XXKSH SOLID/WATER (HYDROCARBON) (L/KG) 0.8300

 4 RHOS BULK DENSITY (GR/CC) 1.5100

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the linear equilibrium partitioning coefficient between the NAPL and the water phase concentrations

of the chemical constituent. By definition

where K is the dimensionless partition coefficient between the NAPL phase (c ) and water phase (c ) o o w

concentrations of the chemical constituent. The partitioning between the NAPL phase and the water phase

depends on the composition of the NAPL. Estimation of K is o discussed in Appendix 3.2 "NAPL/Water Partition

Coefficient." A utility program for performing the necessary calculations, called RAOULT, is described in

Appendix 6.

2. Enter the linear equilibrium partitioning coefficient, K , in liters per kilogram between the soil and the water d

phase concentrations (c and c ) of the constituent. By definition s w

where K is the partition coefficient in liters per kilogram between the solid (c ) and water phase concentrations d s 

(c ). K is commonly w d estimated from the fraction organic carbon of the media, f , and the organic oc carbon

partition coefficient, K as oc

(44)(44) in Appendix 3 lists K values for several hydrocarbon constituents. oc

3. Enter the linear equilibrium partitioning coefficient between the soil and the water phase concentrations (cs

and c ) of the hydrocarbon phase. Like the solubility of the NAPL phase, discussed below, this parameter is w

not critical. This coefficient is used for estimating the partitioning of the dissolved fractions of the NAPL (i.e.,

all of the NAPL chemicals except the chemical constituent of interest).

4. Enter the bulk density, Db, of the soil in g/cm . Porosity, 0, and bulk density, Db are related by 3
Db ' Ds (1 & 0)

[Appendix 1 The MS-DOS Interface] 134

(33)

where Ds is the solids density. The density of quartz is approximately 2.65 g/cm . The values for porosity and 3

bulk density must be related by equation (33).
capillary

thickness

parameter

' smear zone thickness × residual NAPL saturation

maximum NAPL saturation in lens

135 [Appendix 1 The MS-DOS Interface]

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Table 64 OILENS Model Parameters, First Screen

 SCREEN 11. OILENS SUB-MODEL PARAMETERS.1

 1 RADI RADIUS OF SOURCE (M) 2.0000

 2 RMF RADIUS MULTIPLICATION FACTOR (*) 1.0010

 3 FRING CAPILLARY THICKNESS PARAMETER (M) 0.0100

 4 VDISP AQUIFER VERTICAL DISPERSIVITY (M) 0.1000

 5 GRAD GROUNDWATER GRADIENT (*) 0.0100

 6 SPRB AQUIFER RESIDUAL NAPL SATURATION (*) 0.1500

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the radius of the contaminant source, R , in meters. s When no OILENS simulation is desired (Run

OILENS is not selected on the Simulation Control Switches screen), a per unit area simulation can be

performed by entering 0.5642 as the radius of the source. The resulting source area is 1.0 m .2

2. Enter the value of the radius multiplication factor. A value of 1.001 is suggested for the radius multiplication

factor (RMF). The RMF is used to multiply the source radius for starting the OILENS model. This is necessary

since the OILENS equations are singular at the source radius. Starting the simulation at a small distance from

the true radius avoids this singularity. This procedure does, however, introduce a mass balance error into the

solution, so the minimum value of RMF which permits the simulation to proceed should be used. At no time

should the RMF exceed 1.1. When the singularity is encountered, the OILENS model will display the error

message

OILENS SINGULARITY ENCOUNTERED, INCREASE RMF

The RMF should then be increased and the simulation retried.

3. Enter the value of the capillary thickness parameter (meters). The capillary thickness parameter gives the

model a thickness which must build up in the capillary fringe before spreading of the NAPL occurs. Typically,

a value of 0.01m should be entered for this parameter. This results in a small thickness of NAPL that is built

up before spreading begins. 

The capillary thickness parameter can also be used to incorporate the effect of water table fluctuation on the

lens radius. Water table fluctuation can cause trapping of NAPL throughout a smear zone, and the trapped

NAPL is not available for radial spreading. To include this effect, the capillary thickness parameter should be

calculated by

The smear zone thickness should be taken as the maximum water table fluctuation. The residual NAPL

saturation and maximum NAPL saturation in the lens are described under Screens 6, 11 and 12.
[Appendix 1 The MS-DOS Interface] 136

4. Enter the vertical dispersivity of the aquifer, A , in meters. See the discussion of longitudinal V dispersivity

under (34) below. 

5. Enter the groundwater gradient. Typical maximum natural gradients are 0.005 to 0.02. Since pumping wells

are not allowed in TSGPLUME, natural gradients should be used here.

6. Enter the residual NAPL phase saturation in the aquifer, S . See notes above for vadose zone residual ors

NAPL saturation.
137 [Appendix 1 The MS-DOS Interface]

Table 65 OILENS Model Parameters, Second Screen

 SCREEN 12. OILENS SUB-MODEL PARAMETERS.2

 1 XMSOL MAX. NAPL SATURATION IN LENS (*) 0.3260

 2 SOLC CONSTITUENT WATER SOLUBILITY (MG/L) 1750.0000

 3 SOLH HYDROCARBON WATER SOLUBILITY (MG/L) 10.0000

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the saturation of the LNAPL, S , in the NAPL lens. In HSSM, the lens is idealized as a uniformity o(max)

saturated lens, although in actuality the NAPL saturation varies within the lens. The thickness of the lens in

HSSM represents the ratio of the volume of the lens to its area. Within the lens the NAPL has a certain

saturation. Estimation of the NAPL lens saturation is discussed in Appendix 3.3, and a utility called NTHICK

for performing the necessary calculation is described in Appendix 7.

2. Enter the chemical constituent water solubility, s , in k mg/L. The solubility entered here is the "pure

component" solubility which is tabulated in several sources (i.e., Mercer et al., 1990; Sims et al., 1991; USEPA,

1990). Several values are given in Table 98. The solubility is used by HSSM to limit the water phase

concentration. Appropriately chosen K values (which imply maximum water phase concentrations much less o

than the pure phase solubilities) make this parameter redundant for NAPLs composed of mixtures of chemicals.

3. Enter the NAPL water solubility in mg/L. This coefficient represents the solubility of all of the NAPL

constituents, except the chemical constituent that is simulated. The solubility of the chemical constituent is

entered separately. Further, this value is only used by the model in a substantial way if one of the ending

criteria is used. Therefore the value of the NAPL solubility is not a critical parameter. 

The value of NAPL solubility must be greater than zero if the OILENS Simulation ending criterion (see

below) is set to  "NAPL lens spreading stops." Bauman (1989) estimated that the typical solubility of gasoline

is on the order of 50 to 200 mg/L. 
[Appendix 1 The MS-DOS Interface] 138

Table 66 Simulation Control Parameters

 SCREEN 13. SIMULATION PARAMETERS

 1 TM SIMULATION ENDING TIME (D) 2500.0000

 2 DM MAXIMUM SOLUTION TIME STEP (D) 20.0000

 3 DTPR MINIMUM TIME BETWEEN PRINTED TIME STEPS

 AND MASS BALANCE CHECKS (D) 0.1000

 4 KSTOP ENDING CRITERION 4

 1 = USER SPECIFIED TIME

 2 = LENS SPREADING STOPS

 3 = MAXIMUM CONTAMINANT MASS FLUX TO AQUIFER

 4 = CONTAMINANT MASS FLUX IN OILENS < OPERC * MAX

 5 OPERC MINIMUM CONTAMINANT MASS IN LENS (*) 0.0100

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the simulation ending time in days. This time must always be specified, even though other stopping

options are available and may override the maximum simulation time.

2. Enter the maximum solution time step in days. This should be set as high as possible, although internal

error correction routines will often limit the actual size of the step taken. Values of up to 25 days are usually

acceptable. Overly large step sizes may introduce mass balance errors in the model results.

3. Enter the minimum time between printed time steps in days. Although the model uses a variable time step

ordinary differential equation solver, at times during the simulation HSSM takes very small steps. Results from

these steps are of little use and dramatically increase the size of the output files. This parameter prevents the

output of every solution step and should be set to 0.1 or 0.25 days. This parameter does not affect the

simulation itself, but only the information that is output.

For most chemicals leaching out of the lens, after the peak mass flux into the aquifer has passed, there is a

relatively long period of time where the mass flux into the aquifer slowly declines. During this time period, the

user set minimum time between printed time steps may be overridden in order to reduce the size of the output

and plot files. An additional criteria is added that the mass flux must change by at least 1.0 percent for the

results to be output. This feature cannot be overridden by the user.

 

4. The OILENS Simulation ending criterion determines how the HSSM-KO simulation terminates. Because

it is not possible to predict when certain events in the simulation will occur, several of the options cause the

simulation to end only after the event of interest has occurred. In these cases the user specified ending time

is overridden and the simulation continues. 

NOTE: The fourth option, "Contaminant leached from lens" must be chosen in order to use the 

HSSM-T model.

 User-specified ending time

Stop at the simulation ending time specified above.
139 [Appendix 1 The MS-DOS Interface]

 NAPL lens spreading stops

Stop the simulation when the NAPL lens stops spreading. If no NAPL lens forms before the specified ending

time, then the simulation stops at the specified ending time. If a lens does form, the ending time is overridden

and the simulation continues until the NAPL lens stops spreading. When the NAPL phase solubility is near

zero, it is possible that, in the model, the lens motion may never stop, since kinematic theory predicts that an

infinite amount of time is required for all of the NAPL to pass a given depth. The NAPL trickles into the lens

throughout the simulation, and NAPL lens motion stops when the flux into the lens drops below the NAPL

dissolution flux into the aquifer. If the NAPL solubility is zero and no chemical constituent is simulated, no NAPL

is dissolved and the motion may continue indefinitely. To avoid this problem, a non-zero NAPL solubility (see

Hydrocarbon Phase Parameters) is required for this situation.

 Maximum contaminant mass flux into aquifer

Stop the simulation when the maximum chemical constituent flux into the aquifer occurs. If no NAPL lens forms

before the specified ending time, the simulation stops at the specified ending time. If a lens forms, the ending

time is overridden and the simulation continues until the maximum mass flux occurs.

 Contaminant leached from lens drops below a given fraction of the total mass in the lens

Stop the simulation when the contaminant mass in the NAPL lens drops below a specified fraction of the

maximum contaminant mass that has been contained within the lens during the entire simulation. The fraction

is specified by the user. If no NAPL lens forms before the user-specified ending time (above), the simulation

stops at the specified ending time.

5. Enter the mass factor stopping criterion for the ending criterion  "Contaminant leached from lens". Two

percent (0.02) or less should be used for this factor. 
[Appendix 1 The MS-DOS Interface] 140

Table 67 Number of Profiles 

 SCREEN 14. PROFILES

 1 NTIMES NUMBER OF PROFILES DESIRED (UP TO 10) 10

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the number of KOPT saturation vs depth profiles (Saturation Profiles graph) and OILENS lens

thickness vs. radius profiles (NAPL Lens Profiles graph). Both are produced at specified times (screen 15)

along with mass balance approximations. Up to ten profiles are allowed.

 Table 68 Profile Times

 SCREEN 15. PROFILE TIMES

 PR ( 1) = 1.0000

 PR ( 2) = 2.0000

 PR ( 3) = 4.0000

 PR ( 4) = 5.0000

 PR ( 5) = 7.5000

 PR ( 6) = 9.0000

 PR ( 7) = 720.0000

 PR ( 8) = 1000.0000

 PR ( 9) = 1500.0000

 PR (10) = 2000.0000

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

A maximum of ten profile times (days) may be entered depending on the value of NTIMES entered in

screen 14.
141 [Appendix 1 The MS-DOS Interface]

 Table 69 TSGPLUME Input Data Menu

 SCREEN 16. TSGPLUME DATA INPUT SCREENS

 1......TSGPLUME INPUT DATA

 2......SIMULATION TIME

 3......WELL LOCATIONS

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

 

From screen 16, three screens of TSGPLUME input data are assessed. None of these data are used in

KOPT/OILENS for simulation, but are processed and printed in the TSGPLUME input data file. After the

KOPT/OILENS simulation is completed the mass flux profile to the aquifer is added to the data file.

 Table 70 TSGPLUME Data

 SCREEN 16A. TSGPLUME DATA

 1 DLONG AQUIFER LONGITUDINAL DISPERSIVITY (M) 10.0

 2 DTRAN AQUIFER TRANSVERSE DISPERSIVITY (m) 1.0

 3 PMAX PERCENT MAX. CONTAM. RADIUS (*) 101.0

 4 CMINW MINIMUM OUTPUT CONCENTRATION (MG/L) 0.001

 5 ZLAM AQUIFER DECAY RATE COEFFICIENT (1/D) 0.0

 6 NWELL NUMBER OF RECEPTOR WELLS (*) 2

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the longitudinal dispersivity of the aquifer, A , in meters. L

2. Enter the horizontal transverse dispersivity of the aquifer, A , in meters. T
DL ' AL v

DT ' AT v

DV ' AV v

[Appendix 1 The MS-DOS Interface] 142

(35)

The dispersivities are defined by

where D , D , and D are the longitudinal, horizontal transverse, and vertical transverse dispersion coefficients; LT V

A , A , and A are likewise the longitudinal, horizontal transverse, and vertical transverse dispersivities; and v LT V

is the seepage velocity in the mean flow direction.

Dispersive mixing in aquifers results from solute transport through heterogeneous porous media. As the

contaminant plume spreads it "experiences" more heterogeneity and the apparent dispersion coefficient

increases. Thus the dispersion coefficients, D , D and D are not fundamental parameters, but exhibit scale LT V

dependence.

Gelhar et al. (1992) recently reviewed dispersivities determined at 59 sites and considered the reliability of the

dispersion coefficients. They concluded that there are no highly reliable longitudinal dispersion coefficients at

scales greater than 300m. Notably, at a given scale, dispersivities have been found to vary by 2 to 3 orders of

magnitude, although the lower values are more reliable. Based on these data, horizontal transverse

dispersivities are typically from 1/3 to almost 3 orders-of-magnitude lower than longitudinal dispersivities.

Vertical transverse dispersivities are typically (although based on a very limited data set) 1-2 orders-ofmagnitude lower than horizontal transverse dispersivities. The very low values of vertical transverse

dispersivities reflect roughly horizontal stratification of sedimentary materials. 

3. Enter the percentage of the maximum contaminant radius which is to be used in the TSGPLUME simulation,

which requires a constant radius for the input mass flux. 

Since the radius of the NAPL lens changes continuously during part of the simulation, it may not be possible

to preselect an appropriate lens radius for the TSGPLUME module. It is desirable, however, to match the

radius of the lens to the peak mass flux into the aquifer. Thus TSGPLUME simulation can use the radius which

occurs at the time of the maximum mass flux. With this approach the peak mass flux is not overly diluted due

to a large lens radius. (Nor is it "condensed" due to an overly small radius). The lens radius which occurs at

the time of the maximum mass flux is automatically selected if 101 is entered for the percent maximum

contaminant radius. Thus, the recommended value of this parameter is 101. It may be desirable for users to

determine the effect of varying the size of the source on the aquifer concentrations.

4. Enter the minimum concentration (mg/L) for TSGPLUME to include in the output. Concentrations below this

value will be reported as zero. A nonzero value of this parameter is required for proper execution of the

TSGPLUME module. Typically, a concentration of 0.001 mg/L is suitable for the minimum concentration. 

5. Enter the half-life of the constituent in the aquifer. This value is used only by the TSGPLUME model.

6. Enter the number of wells (a maximum of six) for which TSGPLUME is to calculate concentration vs time

for the Well Concentrations graph.
143 [Appendix 1 The MS-DOS Interface]

Table 71 TSGPLUME Simulation Time

 SCREEN 16B. TSGPLUME SIMULATION TIMES

 1 BEGT BEGINNING TIME (D) 100.0

 2 ENDT ENDING TIME (D) 5000.0

 3 TINC TIME INCREMENT (D) 50.0

 4 TAQU AQUIFER THICKNESS (M) 15.0

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

1. Enter the beginning time in days for the TSGPLUME simulation. See note below.

2. Enter the ending time in days for the TSGPLUME simulation. See note below.

3. Enter the time increment in days for TSGPLUME output between the beginning and ending times specified

above. Typically 50 or 100 days is adequate for the time increment. See note below.

NOTE: Before running the model, it is not possible to guess precisely when the contaminant arrives at or

passes a given receptor point. HSSM-T will override the user supplied beginning and ending times which

allows the model to produce smooth concentration histories at the receptor point. Particular effort is

expended in HSSM-T to calculate when the contaminant first arrives at the receptor point and when the

peak concentration arrives. The duration of mass flux into the aquifer is used to determine a proposed

time increment for HSSM-T output. If one hundredth of the mass flux input duration is greater than the

user specified time increment the user is prompted to increase the time increment:

*** TSGPLUME RECOMMENDS CHANGING THE TIME INCREMENT

*** FROM 0.5000 DAYS TO 98.60 DAYS

*** ACCEPT THE CHANGE ? (Y OR N)

HSSM-T is making the user an offer that shouldn't be refused, at least for an initial simulation. If the

resulting concentration history curve is not smooth enough, the user may reduce the time increment for

HSSM-T to produce a finer spacing in time.

If the user does not accept the change, he/she is prompted to decide between the original time

increment or to enter a new time increment.

 

4. Enter the thickness of the aquifer in meters.
[Appendix 1 The MS-DOS Interface] 144

Table 72 TSGPLUME Well Locations

 SCREEN 16C. WELL LOCATIONS

 

 # X Y

 ===== ========== ========== 

 1 25. 00.

 2 50. 00.

 ENTER 0 OR <RETURN> FOR NO CHANGE

 ENTER <ITEM NUMBER> TO CHANGE SINGLE ITEM 

 ENTER -1 TO CHANGE ALL ITEMS IN SEQUENCE

Enter up to six well locations, as X and Y coordinates in meters. X is directed along the longitudinal axis of the

plume (the direction of groundwater flow) and Y is directed transversely distance to the X axis. The origin of

the coordinate system is located at the center of the source (see Figure 9). The number of entries will be

truncated depending on the value of Number of receptor wells on Table 70.
145 [Appendix 1 The MS-DOS Interface]

1.9 Running the KOPT, OILENS and TSGPLUME Modules

This section describes the operation of the HSSM-KO and HSSM-T modules. These programs are the

heart of the simulation model. The DOS interface program (HSSM-DOS) can run the modules by shelling out

to DOS and issuing the commands listed below. The HSSM-DOS commands are listed in Table 40. The user

may also execute the commands directly from the DOS prompt.

Once an input data file has been created, the HSSM-KO module is executed by the DOS command

HSSM-KO NAME.DAT

where NAME.DAT is the input data file. The command assumes the default directory contains the HSSMKO.EXE file, or that the HSSM directory has been added to the path (see Appendix 1.7). Table 73 shows the

first screen that appears when HSSM-KO is executed. This screen identifies the model and the authors.

Pressing return displays the disclaimer screen (Table 74). Carefully note the disclaimer messages. Sound

scientific and engineering judgement is required when applying models and the user is responsible for the

application of the model.

 

Table 73 Introductory HSSM-KO Screen

 ***************************************************

 * *

 * HSSM *

 * *

 * HYDROCARBON SPILL SCREENING MODEL *

 * *

 * INCLUDING THE KOPT, OILENS AND TSGPLUME MODELS *

 * *

 * JAMES W. WEAVER *

 * UNITED STATES ENVIRONMENTAL PROTECTION AGENCY *

 * R.S. KERR ENVIRONMENTAL RESEARCH LABORATORY *

 * ADA, OKLAHOMA 74820 *

 * *

 * INCLUDING OILENS--HYDROCARBON MOVEMENT ON THE *

 * WATER TABLE *

 * RANDALL CHARBENEAU, SUSAN SHULTZ, MIKE JOHNSON *

 * ENVIRONMENTAL AND WATER RESOURCES ENGINEERING *

 * THE UNIVERSITY OF TEXAS AT AUSTIN *

 * *

 * VERSION 1.00 *

 ***************************************************
[Appendix 1 The MS-DOS Interface] 146

Table 74 Disclaimer Screen

 ***************************************************

 * WARNING: *

 * THIS PROGRAM SIMULATES IDEALIZED BEHAVIOR OF *

 * OILY-PHASE CONTAMINANTS IN IDEALIZED POROUS *

 * MEDIA, AND IS NOT INTENDED FOR APPLICATION TO *

 * HETEROGENEOUS SITES. *

 * THE MODEL RESULTS HAVE NOT BEEN VERIFIED BY *

 * EITHER LAB OR FIELD STUDIES. *

 * READ USER GUIDE FOR FURTHER INFORMATION BEFORE *

 * ATTEMPTING TO USE THIS PROGRAM. *

 * NEITHER THE AUTHORS, THE UNIVERSITY OF TEXAS, *

 * NOR THE UNITED STATES GOVERNMENT ACCEPTS ANY *

 * LIABILITY RESULTING FROM THE USAGE OF THE CODE *

 * THE U.S. E.P.A DOES NOT OFFICIALLY ENDORSE THE *

 * USE OF THIS CODE. *

 ***************************************************

A list of the file names used by HSSM-KO and HSSM-T is displayed in Table 75. 

Table 75 Output File Names and Run Options

OUTPUT AND PLOT FILE NAMES:

HSSM-KO INPUT DATA FILE BENZENE.DAT

HSSM-KO OUTPUT BENZENE.HSS

HSSM-KO PLOT 1 BENZENE.PL1 

HSSM-KO PLOT 2 BENZENE.PL2

HSSM-KO PLOT 3 BENZENE.PL3

HSSM-T INPUT DATA FILE BENZENE.PMI

HSSM-T OUTPUT BENZENE.TSG

HSSM-T PLOT BENZENE.PMP

TO RUN HSSM-KO ENTER <RETURN>

TO CHANGE INPUT FILE ENTER F

TO VIEW DIRECTORY ENTER D

TO EXIT ENTER 1 

The names must follow a strict naming convention for the TSGPLUME module (HSSM-T) and the HSSM-PLT

post-processor to function properly. For the user's convenience the correct file names are generated

automatically by PRE-HSSM. These should not be modified by the user.

As indicated in Table 75, the user may either run HSSM-KO, change the input data file, view the current

directory or exit the program. Upon beginning a simulation the model writes messages to the screen as the

computations proceed. These allow the simulation to be tracked by the user. Table 76 contains a typical set

of screen messages for a simulation.
147 [Appendix 1 The MS-DOS Interface]

Table 76 Typical HSSM-KO Screen Messages

 *** DATA INPUT 

 *** DATA INITIALIZATION 

 *** SIMULATION BEGINNING 

 *** OIL INFILTRATION 

 *** OIL REDISTRIBUTION 

 *** CHEMICAL REACHES WATER TABLE 

 *** OIL LENS FORMS 

 *** PROFILING AT 15.00 DAYS 

 *** PROFILING AT 30.00 DAYS 

 *** PROFILING AT 90.00 DAYS 

 *** PROFILING AT 130.00 DAYS 

 *** PROFILING AT 175.00 DAYS 

 *** SIMULATION END 

 *** POST PROCESSING 

 *** CREATING OUTPUT FILE:

 *** BENZENE.HSS

 *** PROCESSING PLOT FILE CONTENTS

 *** REPACKING FILE 18

 *** REPACKING FILE 19

 *** CREATING KOPT/OILENS PLOT FILE:

 *** BENZENE.PL1

 *** CREATING KOPT/OILENS PLOT FILE:

 *** BENZENE.PL2

 *** CREATING KOPT/OILENS PLOT FILE:

 *** BENZENE.PL3

 *** CREATING TSGPLUME DATA FILE:

 *** BENZENE.PMI

 *** HSSM END 

The HSSM-T implementation of TSGPLUME is designed to be used with HSSM-KO. If the data set for

HSSM-KO has switches set appropriately, and if the dissolved chemical of interest reaches the water table

(either through the formation of a NAPL lens or by the leaching from an immobilized NAPL body in the vadose

zone), then an input data set for TSGPLUME is created by running HSSM-KO. The necessary flags and

conditions for TSGPLUME data file generation are summarized in Table 77. These parameters are described

in detail in Appendix 1.8.2.
[Appendix 1 The MS-DOS Interface] 148

Table 77 HSSM-KO Data Switches for the Creation of TSGPLUME

 (HSSM-T) input Data Files

Condition or PRE-HSSM Screen Effect

switch

IWR = 1 Screen 1 (Table 49) Output and plot files produced

IKOPT = 1 Screen 1 (Table 49) KOPT module is run

ILENS = 1 Screen 1 (Table 49) OILENS module is run

ICONC = 1 Screen 1 (Table 49) Chemical constituent is included in the simulation.

ITSGP = 1 Screen 1 Table 49) Attempt to create the TSGPLUME (HSSM-T.EXE) input

data.

KSTOP = 4 Screen 13 (Table 66) End HSSM-KO.EXE simulation when a small fraction of

chemical constituent remains in the oil lens.

"large" Screen 13 (Table 66) Allow sufficient simulation time for chemical to reach the

simulation water table before ending simulation (with KSTOP = 4

ending time simulation ending time is over-ridden if the chemical

(TM) reaches the water table.)

Once HSSM-KO has run and produced an HSSM-T input data file, HSSM-T can be executed by entering the

command:

HSSM-T NAME.PMI

where NAME.PMI is the input data file. When HSSM-T executes, screen messages appear as shown in Table

78. After pressing return, the file names for the simulation appear as indicated in Table 79.
149 [Appendix 1 The MS-DOS Interface]

Table 78 Introductory HSSM-T Screen

 ***************************************************

 * *

 * TSGPLUME *

 * *

 * TRANSIENT SOURCE GAUSSIAN PLUME MODEL * 

 * *

 * *

 * MIKE JOHNSON *

 * RANDALL CHARBENEAU *

 * THE UNIVERSITY OF TEXAS AT AUSTIN *

 * *

 * JIM WEAVER *

 * ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY*

 * UNITED STATES ENVIRONMENTAL PROTECTION AGENCY *

 * *

 * VERSION 1.00 *

 ***************************************************

 

 Table 79 HSSM-T Output File Names and Run Options

OUTPUT AND PLOT FILE NAMES:

HSSM-KO INPUT DATA FILE BENZENE.DAT

HSSM-KO OUTPUT BENZENE.HSS

HSSM-T INPUT BENZENE.PMI

HSSM-T OUTPUT BENZENE.TSG

HSSM-T PLOT BENZENE.PMP

TO RUN TSGPLUME ENTER <RETURN>

TO CHANGE INPUT FILE ENTER F

TO VIEW DIRECTORY ENTER D

TO EXIT ENTER 1

When HSSM-T executes, a set of messages is written to the screen (Table 80). These messages inform the

user on the progress of the simulation. The example shown has only one receptor location; when more

receptors are used, more messages like these are produced.
[Appendix 1 The MS-DOS Interface] 150

Table 80 Typical HSSM-T Screen Messages 

 *** DATA INPUT 

 *** DATA INITIALIZATION 

 *** CALCULATING FLOATING POINT PRECISION

 ***

 *** COMPUTATION BEGINNING FOR RECEPTOR 1

 *** CALCULATING THE TOE TIME OF THE HISTORY

 *** SEARCH ALGORITHM COMPLETED IN 6 ITERATIONS

 *** COMPUTATION AT 18.18 DAYS COMPLETED

 *** COMPUTATION AT 18.44 DAYS COMPLETED

 *** COMPUTATION AT 33.41 DAYS COMPLETED

 *** COMPUTATION AT 48.38 DAYS COMPLETED

 *** COMPUTATION AT 63.35 DAYS COMPLETED

 *** COMPUTATION AT 78.32 DAYS COMPLETED

 *** COMPUTATION AT 83.32 DAYS COMPLETED

 *** COMPUTATION AT 88.32 DAYS COMPLETED

 *** COMPUTATION AT 93.32 DAYS COMPLETED

 *** COMPUTATION AT 98.32 DAYS COMPLETED

 *** COMPUTATION AT 103.3 DAYS COMPLETED

 *** COMPUTATION AT 108.3 DAYS COMPLETED

 

 {other similar messages omitted}

 

 *** COMPUTATION AT 553.3 DAYS COMPLETED

 *** COMPUTATION AT 603.3 DAYS COMPLETED

 *** COMPUTATION AT 653.3 DAYS COMPLETED

 *** COMPUTATION AT 703.3 DAYS COMPLETED

 *** COMPUTATION AT 753.3 DAYS COMPLETED

 *** COMPUTATION AT 803.3 DAYS COMPLETED

 *** COMPUTATION AT 853.3 DAYS COMPLETED

 ***

 *** OUTPUT FILE: 

 *** BENZENE1.TSG 

 *** PLOT FILE: 

 *** BENZENE1.PMP 

 *** TSGPLUME END 
151 [Appendix 1 The MS-DOS Interface]

1.10 Plotting HSSM Results with HSSM-PLT

The HSSM-PLT program is a graphics post-processor for the HSSM program. HSSM-PLT provides the

model users with on-screen visualizations of the output as well as optional hard copies. All inputs are made

through a menu, enabling the user to concentrate on the model's results. HSSM-PLT program is written in

Microsoft FORTRAN 77 version 5.0 and uses the INGRAF version 5.02 library of FORTRAN graphics routines.

1.10.1 Package Requirements

The plotting program is made up of the three files shown in Table 81. These are supplied on the HSSM-1-d

diskette and should be installed in the HSSM directory according to Appendix Table 41.

Table 81 Required Files for the HSSM-PLT Graphical Display

Program

File Function

HSSM-PLT.EXE The HSSM Graphical Display program

CONFIG.PLT User supplied information about the printer

hardware of the system

SIMPLEX1.FNT The Sutrasoft font file for lettering the displays.

All three files must be present in the same subdirectory for HSSM-PLT to work properly. 

1.10.2 Overview

HSSM-PLT was written with the INGRAF graphics library. The program displays a copyright notice that

will appear for approximately two seconds. The Sutrasoft copyright notice is displayed in compliance with the

licensing agreement for the INGRAF graphics library. For more information about INGRAF contact:

Sutrasoft (The Librarian, Inc.)

10506 Permian Dr.

Sugarland, TX 77487 

(713) 491-2088

FAX (713) 240-6883

HSSM-PLT displays a menu of choices which includes options to 1) exit the program, 2) configure output

devices, 3) select HSSM-KO and HSSM-T results files for plotting, and 4) select graphs for display. Options

2 through 4 display either screen messages or additional menus to guide the user. 

Table 82 lists the HSSM-PLT command sequence for graphing the results. The full details of the

procedures are described in the following sections.
[Appendix 1 The MS-DOS Interface] 152

Table 82 Quick Summary of HSSM-PLT Commands

Step Command or Menu Item Action

0 see Table 41 Generate HSSM results

1 Item 2 Select printer *

2 Item 3 Select HSSM-KO and HSSM-T

output files

3 Item 4 Graph results

4 press P Print the graph which is

displayed

5 Item 0 Exit

The printer selection is saved for future use of the program, so step 1 is executed only when the printer is *

selected initially or changed; or when writing to disk files. 

Title Screen

This screen shows the title, version number, and authorship information for the program. This data stays

on the screen until the user presses any key.

Menu Screen

The Menu Screen contains the user interface for all the HSSM-PLT program options. To make a selection,

the user presses the indicated key for the desired selection. For example, to exit the program a "0" (zero) key

is pressed and the program ends. The legal selections are 0 through 3 and any other key strokes are ignored.

Menu Option 1: Device Configuration

The Device Configuration option allows users to select the appropriate output device for his/her system.

The configuration data is stored in the config.plt file, so the user need only use this option when running the

program for the first time, when changing the printer, or when plotting to a disk file. The current output device

is displayed on the first line of Table 83. All of the supported output devices are displayed with an index

number. By entering the index number, the user selects an output device from the displayed list.
153 [Appendix 1 The MS-DOS Interface]

Table 83 Output Device Configuration Options

THE CURRENT OUTPUT DEVICE IS Postscript printer 

 

SELECT AN OUTPUT DEVICE 

 1 - EPSON 9-pin, narrow carriage 

 2 - EPSON 24-pin, LQ series, narrow 

 3 - EPSON 24-pin, LQ series, wide 

 4 - NEC Pinwriter, 24-pin, narrow 

 5 - NEC Pinwriter, 24-pin, wide 

 6 - Okidata, 9-pin, narrow 

 7 - HP LaserJet/DeskJet - low res 

 8 - HP LaserJet/DeskJet - medium res 

 9 - HP LaserJet/DeskJet - high res 

 10 - HP PaintJet - 2 color, low res 

 11 - HP PaintJet - 4 color, med res 

 12 - HP PaintJet - 8 color, high res 

 13 - HP PaintJet - 16 color, high res 

 14 - Postscript printer 

 15 - HP - HPGL plotter 

 16 - HP LaserJet III - HPGL/2 mode 

 17 - Houston Inst DM/PL plotter 

 ENTER DEVICE NUMBER : 

After the output device selection is made, the output port is assigned (Table 84). The screen follows the same

format as for the device: The current port is shown, followed by the possible port selections. By entering the

index number, the user selects an output port from the displayed list.
[Appendix 1 The MS-DOS Interface] 154

Table 84 Output Device Port Selection

THE CURRENT OUTPUT PORT IS LPT1: 

 SELECT AN OUTPUT PORT

 1 - PRN: 

 2 - LPT1: 

 3 - LPT2: 

 4 - COM1: 

 5 - COM2: 

 6 - AUX: 

 7 - FILE 

 ENTER PORT NUMBER: 

Option 7 sends the graph to an HPGL format disk file rather than an output device. When this option is

selected, the user is prompted for a filename in addition to the port number. Note that only the last graph written

to file is retained in the file. If more than one graph is desired to be written to a file, the configuration must be

reentered each time for each graph in order to change the name of the output file.

Menu Option 2: Selecting Input Files

Before graphing results, a set of HSSM results must be selected. All of the necessary plot files are read

by HSSM-PLT and become available for drawing specific graphs. If graphing is attempted before selecting

the plot files, a reminder to select a file is given. 

The first message that appears on the screen is

ENTER SUBDIRECTORY PATH NAME

PRESS <ENTER> TO USE CURRENT DIRECTORY:

The user may then press <ENTER> to use the current directory, or supply a DOS path name such as

c:\models\hssm\working

The user is prompted for a file name by the following message:

ENTER FILE NAME OR * FOR A DIRECTORY

USE THE ROOT ONLY - NO EXTENSIONS:

Pressing <ENTER> or an asterisk displays the current directory of HSSM-KO input files (files with extension

.DAT). Entering the root name, such as BENZENE, causes HSSM-PLT to begin reading the plot files. HSSMPLT adds the extensions to the root file name when it retrieves the plot files. For this example, the following

messages were written to the screen:
155 [Appendix 1 The MS-DOS Interface]

READING FILE c:\models\hssm\working\BENZENE.PL1 .... DONE

READING FILE c:\models\hssm\working\BENZENE.PL2 .... DONE

READING FILE c:\models\hssm\working\BENZENE.PL3 .... DONE

FILE c:\models\hssm\working\BENZENE.PMP DOES NOT EXIST

READING FILE c:\models\hssm\working\BENZENE.HSS .... DONE

PRESS ANY KEY TO CONTINUE

The plot files BENZENE.PL1, BENZENE.PL2, BENZENE.PL3 and the main result file BENZENE.HSS were

read successfully. The HSSM-T plot file BENZENE.PMP did not exist as HSSM-T had not been run for this

data set.

Menu Option 3: Selecting Graphs

After the input file has been selected, graphs can be generated. Option 3 from the main menu brings up

the graph menu. If no input file has been selected then an error message is displayed. The legal entries for

the graph menu are 0 - 7 and all other key strokes will be ignored. Each of the graphs is described in detail

in the next section. Generally, after the graph is drawn on the screen, pressing any key will bring the user back

to the graphics menu. However, if the user presses the <P> key, the graph will be printed according to the data

in the CONFIG.PLT file. 
[Appendix 1 The MS-DOS Interface] 156

1.11 Graphical Presentation of HSSM Output

 Two basic types of graphs are produced by the DOS graphics post-processor. These are profiles which

present the spatial variation of a parameter at a given time, and histories which present the time variation of a

parameter at a given location. The graphics present a visual summary of the output from a successful HSSM

simulation. Results from each of the modules of HSSM are contained in one or more of the graphs. (35) gives

information on each of the graphs provided. 

Table 85 HSSM Graphics

Graph Title HSSM Module Description

Number

1 Saturation Profiles KOPT Vadose zone liquid saturations from the

surface to the water table

2 NAPL Front Position KOPT Location of the NAPL front in the vadose

History * zone

3 NAPL Lens Profiles OILENS Cross-section of the NAPL lens on the

water table

4 NAPL Lens Radius OILENS History of the radius of the NAPL lens

History and the effective radius of the

contaminant

5 Contaminant Mass Flux OILENS History of the mass flux from the NAPL

History lens to the aquifer

6 NAPL Lens OILENS History of the mass in the NAPL lens

Contaminant Mass

Balance

7 Receptor Concentration TSGPLUME History of the contaminant concentrations

Histories at the receptor points

* Only the MS-DOS interface produces the NAPL Front Position History.

The graphs produced by HSSM-PLT are very similar to those produced by HSSM-WIN. Examples of the

HSSM-WIN graphs are shown in Section 4.8. 
[Appendix 2 DOS Example] 157

Appendix 2 DOS Example Problem

In this Appendix, an example problem is presented that illustrates the use of the DOS interface. This

problem is the same as the first example presented in Section 5. The complete set of input and output files for

this example is distributed on the HSSM-2 diskette.

2.1 Gasoline Arrival Time at the Water Table

An emergency response and monitoring plan is being prepared for an above ground storage tank facility.

 An estimate is needed of how long it would take gasoline to reach the water table and what monitoring

frequency would be required to detect a leak before gasoline reaches the water table. The soil has been

classified as a sandy clay loam soil. In this example, the water table lies at a depth of 5.0 meters. All of the

parameters for the model run are saved in the file X1STF.DAT, which is found on the example problems

diskette HSSM-2. PRE-HSSM can be used to page through this file as the example is studied. 

This problem needs the use of the KOPT module with no dissolved contaminant. A "per unit area"

simulation should be performed because only the transport time through the vadose zone is required. The MSDOS interface will be used to demonstrate how HSSM is used for this problem. Of all the input data required

for the model, only the following parameters are required for the "KOPT only" simulation. PRE-HSSM places

necessary zeros in the data file for the unused parameters.

Screen 1. Printing Option Switches

Only the output file production and KOPT options are used in the example simulation as shown in Table 86.

Table 86 Problem 1 Printing Option Switches

Parameter Rationale Value

IWR Produce Output files 1

IKOPT Run KOPT 1

ICONC No dissolved constituent 0

ILENS Do not run OILENS 0

ITSGP Do not write HSSM-T input file 0

Screen 2 File Names

The required file names are generated automatically when the data set is saved by PRE-HSSM. The stem

for this data set is X1STF. 
Ks ' 270 02

h 2

ce

82

(8 % 1) (8 % 2) ' 8.68 x 10&4 cm/s

[Appendix 2 DOS Example] 158

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Screen 3 Run Title

Gasoline Release from an Aboveground Storage Tank Fac.

Gasoline Arrival Time at the Water Table

KOPT Simulation Only

Screen 4 Porous Medium Properties

The porous medium properties listed on Screen 4 are estimated from Brakensiek et al.'s soil parameter

tabulation. The values shown in Table 87 are taken from the tabulation reproduced in Appendix 3.1.

Table 87 Problem 1 Porous Medium Properties

Parameter Value

Air Entry Head, hce 46.3 cm

Brooks and Corey's Pore Size 0.368

Distribution Index, 8

Residual Water Content, 2wr 0.075

Porosity, 0 0.406

The hydraulic conductivity in cm/s of the system is then estimated from (Brakensiek et al., 1981)

where the air entry head is in cm. The value is then converted to the units of meters per day by multiplying by

864 to give a K of 0.75 m/d. From the basic soil property information, s the following parameters are determined

(Table 88).

Table 88 Problem 1 Hydraulic Conductivity and Capillary Pressure Curve Parameters

Parameter Rationale Value

Ratio of Horizontal to Arbitrary value as this parameter is not used in 5.0

Vertical Conductivity KOPT

Relative Permeability Index The Brooks and Corey Model is used 1

Air Entry Head, h The required units for HSSM are meters. This ce 0.463 m

parameter is entered on screen 7

Residual Water Saturation, HSSM requires saturation input rather than 0.18

S "content" input (0.075 / 0.406) wr
[Appendix 2 DOS Example] 159

Screen 5 Hydrologic Properties

The parameters shown in Table 89 are used for the Hydrologic Properties screen.

 

Table 89 Problem 1 Hydrologic Properties

Parameter Rationale Value

Water Phase Density, Dw Standard value 1.0 g/cm3

Water Phase Viscosity, μ Standard value 1.0 cp w

Recharge Input Type Specify Saturation 2

Water Saturation, S Specified water saturation 0.35 w(max)

Maximum Relative Permeability Assume 0.5 0.5

During Infiltration, krw(max)

Depth of Water Table Arbitrary for this problem 5 m

 

The depth to the water table is stated to be arbitrary because KOPT only treats the vadose zone above the

water table (and capillary fringe). The model results should be checked for the time at which the NAPL front

crosses the 5 meter depth.

 

Screen 6 Hydrocarbon (NAPL) Phase Properties

Table 90 Problem 1 Hydrocarbon (NAPL) Phase Properties

Parameter Rationale Value

Oil Phase Viscosity, μ Typical value for gasoline 0.45 cp o

Oil Phase Density, Do Typical value for gasoline 0.74 g/cm3

Residual Oil Saturation (vadose Estimated 0.10

zone), Sorv

Oil Application Type Select a constant head ponding 3

scenario
[Appendix 2 DOS Example] 160

Screen 7 Capillary Suction Approximation Parameters

The capillary suction approximation parameters are used to add the effect of capillary suction on the

infiltrating NAPL. The air entry head of the Brooks and Corey model (0.46 m) is entered on this screen. The

surface tension of water is taken as 65 dyne/cm to account for the fact that the published values of surface

tension are for very pure water. The NAPL surface tension is taken to be 35.0 dyne/cm.

Screen 8c Hydrocarbon (NAPL) Constant Head Ponding Boundary Condition

Because the constant head release scenario was chosen on Screen 6, the constant head ponding

boundary condition screen appears on screen 8. The beginning time, ending time and ponding time are

entered on this screen. The release is assumed to begin at time of 0 days and end at a time of 1 day. During

this interval the ponding depth is assumed to remain constant at 0.05 m (5 cm).

Screen 11 OILENS Model Parameters, First Screen

OILENS is not used in the present simulation. The radius of the source must be specified, however, and

this parameter is grouped with the OILENS parameters. Only a "per unit area" simulation is desired for this

example, so the source radius is set to 0.5642 meters so that the resulting source area is 1.00 meters. None

of the other parameters on this screen need to be entered.

Screen 13 Simulation Control Parameters

Table 91 Problem 1 Simulation Control Parameters

Parameter Rationale Value

Simulation Ending Time Simulate the release for 25 days, since gasoline is a 25 days

low viscosity fluid and can reach the water table

relatively rapidly in a permeable media.

Maximum Solution Time Step Use a relatively small value, because only 25 days 0.1 day

are simulated

Minimum Time Between Printed Use a value smaller that the minimum solution time 0.05 day

Time Steps step.

Ending Criterion Stop the simulation at the specified time 1

Minimum mass factor Not used for this simulation 0.01

Screen 14 Number of Profiles and Screen 15 Profile Times

Use 5 profiles during the simulation. The times should be small, since the gasoline is expected to reach

the water table relatively rapidly. Use times of 0.25, 0.5, 1.0, 2.0 and 5.0 days (6, 12, 24, 48 and 60 hours).
[Appendix 2 DOS Example] 161

Model Results

The model is executed by entering the command

HSSM-KO X1STF.DAT

The saturation profiles from the simulation are shown in Figure 40. These profiles were drawn with the

HSSM-PLT program. The depth of the sharp front increases with time and the first three profiles show uniform

NAPL saturations. The last two profiles show varying NAPL saturations, because they occur at 48 and 60

hours which both are past the end of the release (24 hours). Figure 41 shows the NAPL front position. This

graph indicates that over the 25-day duration of the simulation, the NAPL does not go deeper than about 3.6

meters.
[Appendix 2 DOS Example] 162

Figure 40 Saturation profiles

Figure 41 The front position
[Appendix 2 DOS Example] 163

Figure 42 Storage tank facility example with increased conductivity

With complete confidence in the accuracy of the input data, it could be assumed that the gasoline never

reaches the water table. However, most of the model parameters used in this example have been estimated

from published tabulations. Rather than accepting the results of one simulation as being authoritative, several

simulations should be run in order to get some feel for the effects of parameter variability. If the hydraulic

conductivity was in fact 10 times greater than the average value of 0.75 m/d, the gasoline would flow deeper

into the subsurface. Because of the constant head ponding condition assumed for this case, the gasoline would

also flow faster. The constant head ponding condition does not specify the volume of gasoline which enters

the soil; it only indicates that enough gasoline is supplied to maintain the 0.05 m ponding depth for one day.

Figure 42 shows the NAPL front position when the hydraulic conductivity is 7.5 m/d. By 25 days, the gasoline

would reach 24 meters deep, if not for the water table 5.0 meters deep. From the X2STF.HSS file, the depth

of 5 meters was reached within 9.8 hours. 

This example has focussed on the role of the hydraulic conductivity in determining the depth of the

gasoline. The effect of variation in other parameters can likewise be demonstrated. Some of the other

uncertain parameters are the assumed release condition, moisture content, and capillary pressure parameters.
qw ' & Ks

dh

dl

Sw & Swr

1 & Swr

' hce

hc

8

[Appendix 3 Sources of Parameter Data] 164

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(38)

Appendix 3 Sources of Parameter Data

The data that are used in models are of crucial importance for determining the quality of the results and

their applicability to the real world problems they are intended to simulate. Often where model applications fail

to be realistic, the failure is due to data limitations and lack of fundamental understanding of site specific

transport processes, both hydrologic and chemical. The following section does not address directly all of these

issues, rather it describes the uses and limitations of estimated parameter values. The discussion below is

intended to highlight the importance of several HSSM input parameters. Further detailed information on

parameter values is given in Section 4.6 for HSSM-WIN and in Appendix 1 for HSSM-DOS. For convenience,

both of these sections contain the same information.

Unarguably, the best sources for parameter values are site- and pollutant-specific data obtained under

an appropriate quality assurance/quality control program. There is no substitute for measured data.

Unfortunately such data are not always available and recourse must be made to estimated or tabulated

parameter values. When this type of data is used for modeling, it must be recognized that very significant

uncertainty is being introduced into the simulation results. The model results may be useful, however, for

addressing such issues as comparison of the effects of various pollutant or soil properties on transport. For

example, given a soil type, perhaps defined by parameters selected from a nationwide tabulation, how does

the transport of benzene compare with that of toluene? HSSM model results may provide some understanding

of relative transport effects. Because of practical and theoretical limitations in understanding subsurface

transport, site specific prediction of future contaminant behavior is questionable with any model.

3.1 Soil Properties

Of primary importance are the soil properties: saturated hydraulic conductivity, K , and the water/air s

capillary pressure curve, P (S), (a.k.a. the moisture characteristic curve or the moisture retention curve). Note c

that the term "saturated hydraulic conductivity" refers to the conductivity to water as defined by Darcy's Law:

where q is the water flux, K is the hydraulic conductivity, and w s -dh/dl is the hydraulic (head) gradient. The

capillary pressure curve depends on some of the same features of the porous medium as does K . These s

features include the grain and pore size distribution, and the sand, silt, clay and loam fractions. There may be

relationships between K and parameters describing the P (S) curve (Brutsaert, 1967; Brakensiek et al., 1981; s c

Carsel and Parrish, 1988).

Brooks and Corey (1964) presented the following power-law relationship between capillary pressure and

reduced saturation 

where S is the irreducible (residual) water saturati wr on, 8 is called the pore size distribution index, and h is the ce

air entry head. In practice S , 8, and h are parameters which are fitted to an experimental data set. wr ce
2w & 2wr

2m & 2wr

' 1

1 % ("h)

n

m

2w ' 0 Sw

Ks ' C

2m &2wr

hce

2 82

(8 % 1) (8 % 2)

165 [Appendix 3 Sources of Parameter Data]

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(40)

(41)

van Genuchten (1980) proposed a similar model

where 2 is the residual water content, 2 is the maximum water content, and ", n, and m are parameters. wr m 

Note that the water content, 2w w , the saturation, S , and the porosity, 0, are related by

2wr m , 2 , ", n, and m can be parameters which are fitted to an experimental data set. Usually m is taken to be

a simple function of n (i.e., m = 1-1/n).

Brakensiek et al. (1981) tabulated Brooks and Corey parameters from a number of soil samples and

organized the results by soil classification. The hydraulic conductivity in cm/s was calculated from the following

formula from Brutsaert (1967) 

where C is a constant taken as 270 by Brakensiek et al. (1981) and as 21 by Rawls et al. (1983). Thus this

tabulation consists of measured P (S) data fitted to the Brooks and Corey model and calculated K values. c s

Table 92 shows Brakensiek et al. (1981) results with their statistical distributions of parameter values. For each

parameter, Brakensiek et al. chose the most suitable distribution and presented their result in terms of means

and standard deviations of transformed distributions (e.g., log normal). Table 92 shows the untransformed

values which would be used directly to generate a capillary pressure curve. These values were developed by

using the statistical distributions given by Brakensiek et al. (1981) to generate a distribution of each parameter.

 The mean values of the distributions were determined and are shown in Table 92. All of the values of the pore

size distribution index, 8, are low, which indicates wide pore size distributions (well sorted materials). Some

sands, in particular, may be more uniform and be better represented by a higher value. Brooks and Corey

parameters for several sands whose capillary pressure curves were measured at RSKERL are presented in

Table 93. These examples have higher 8 values than does the tabulation.
[Appendix 3 Sources of Parameter Data] 166

 Table 92 Average Soil Properties Determined from 

Brakensiek et al. (1981)

Soil Texture Class 8 h 0 2

(number of samples) (cm) ce wr

Sand (19) 0.573 35.3 0.349 0.017

Loamy Sand (69) 0.460 15.9 0.410 0.024

Sandy Loam (166) 0.398 29.2 0.423 0.048

Loam (83) 0.258 50.9 0.452 0.034

Silt Loam (199) 0.216 69.6 0.484 0.018

Sand Clay Loam (129) 0.368 46.3 0.406 0.075

Clay Loam (112) 0.283 42.3 0.476 0.087

Silty Clay Loam (175) 0.178 57.8 0.473 0.054

Silty Clay (26) 0.212 41.7 0.476 0.085

Clay (108) 0.214 64.0 0.475 0.106

Table 93 Brooks and Corey Parameters for Selected Sands

Sand hce 8 S

(cm) (*) (*)wr

Lincoln 42.8 1.69 0.09

Oil Creek 53.9 4.19 0.04

Traverse City 24.0 2.43 0.0

c109 23.7 3.86 0.01

c190 10.2 4.65 0.08

In the Brakensiek et al. tabulation, sand has a higher air entry value (35.3 cm) than loamy sand (15.9 cm). This

suggests that Brakensiek et al.'s sand data are dominated by relatively fine sands of wide pore size distribution.

Notice also that the clay type has a lower air entry value (64.0 cm) than does the silt loam (69.6 cm). In some

of the texture classes only a small number of samples were used to generate the parameter values, which is

a probable reason for the anomalous parameters. As a result, the aforementioned features of the tabulation

suggest that it may only be useful as a rough guide for estimating parameter values.

Carsel and Parrish (1988) presented a tabulation of data based on van Genuchten's (1980) model and

soil texture data. K , s wr m ", n, 2 , and 2 were estimated from regression equations developed previously by Rawls

and Brakensiek (1985) for Brooks and Corey parameters. Carsel and Parrish used an asymptotic

approximation to convert the Brooks and Corey h and ce 8 values to van Genuchten " and n values. The results

of the Carsel and Parrish (1988) tabulation are reproduced in Table 94 for the saturated and residual water

contents, Table 95 for the parameters n and ", and Table 96 for hydraulic conductivity.
167 [Appendix 3 Sources of Parameter Data]

Table 94 Descriptive Statistics from Carsel and Parrish (1988) Data Set

Soil type Saturated Water Content 2m Residual Water Content 2r

sample size mean standard sample size mean standard 

deviation deviation

Clay* 400 0.38 0.09 353 0.068 0.034

Clay Loam 364 0.41 0.09 363 0.095 0.010

Loam 735 0.43 0.10 735 0.078 0.013

Loamy 315 0.41 0.09 315 0.057 0.015

Sand

Silt 82 0.46 0.11 82 0.034 0.010

Silt Loam 1093 0.45 0.08 1093 0.067 0.015

Silty Clay 374 0.36 0.07 371 0.070 0.023

Silty Clay 641 0.43 0.07 641 0.089 0.009

Loam

Sand 246 0.43 0.06 246 0.045 0.010

Sandy Clay 46 0.38 0.05 46 0.100 0.013

Sandy Clay 214 0.39 0.07 214 0.100 0.006

Loam

Sandy 1183 0.41 0.09 1183 0.065 0.017

Loam

 
[Appendix 3 Sources of Parameter Data] 168

Table 95 Descriptive Statistics from Carsel and Parrish (1988) Data Set

Soil type n ", (m ) -1

sample size mean standard sample size mean standard 

deviation deviation

Clay* 400 1.09 0.09 400 0.80 1.2

Clay Loam 364 1.31 0.09 363 1.9 1.5

Loam 735 1.56 0.11 735 3.6 2.1

Loamy 315 2.28 0.27 315 12.4 4.3

Sand

Silt 82 1.37 0.05 82 1.6 0.70

Silt Loam 1093 1.41 0.12 1093 2.0 1.2

Silty Clay 374 1.09 0.06 126 .50 0.50

Silty Clay 641 1.23 0.06 641 1.0 0.60

Loam

Sand 246 2.68 0.29 246 14.5 2.9

Sandy Clay 46 1.23 0.10 46 2.7 1.7

Sandy Clay 214 1.48 0.13 214 5.9 3.8

Loam

Sandy 1183 1.89 0.17 1183 7.5 3.7

Loam

 
f(PS, PC, 0) ' [ bo % j bijk PS i PC j 0k ]

169 [Appendix 3 Sources of Parameter Data]

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Table 96 Descriptive Statistics from Carsel

and Parrish (1988) Data Set

Soil type Hydraulic Conductivity K , (m/d) s

sample size mean standard

deviation

Clay* 114 0.048 0.10

Clay Loam 345 0.062 0.17

Loam 735 0.25 0.44

Loamy 315 3.5 2.7

Sand

Silt 88 0.060 0.079

Silt Loam 1093 0.11 0.30

Silty Clay 126 0.0048 0.026

Silty Clay 592 0.017 0.046

Loam

Sand 246 7.1 3.7

Sandy Clay 46 0.029 0.067

Sandy Clay 214 0.31 0.66

Loam

Sandy 1183 1.1 1.4

Loam

 

* The clay type represents an agricultural soil with clay content of 60% or less.

As a third approach to estimating the soil hydraulic properties, Rawls and Brakensiek (1985) developed

regression equations for the Brooks and Corey parameters. The required data for use of the regressions are

the percent sand, PS, the percent clay, PC, and the porosity, 0. The general form of the regression equations

is
[Appendix 3 Sources of Parameter Data] 170

To apply the regression equations, the percent sand must be between 5 and 70 and the percent clay must be

between 5 and 60. Table 97 gives the values of the regression coefficients for estimating the residual water

content, 2 , the natural log of the hydraulic conductivity, K , entry head, h , and pore size distribution index, 8. r s ce

Appendix 5 describes a utility program called SOPROP which uses the regression equations to estimate these

hydraulic properties.

Table 97 Regression Coefficients from Rawls and Brakensiek (1985)

Coefficient ln( K ) 2 ln (h ) ln (8) s r ce

b -8.96847 -0.0182482 5.3396738 -0.784281 o

b -- 0.00087269 -- 0.0177544 100

b -0.028212 0.00513488 0.1845038 -- 010

b 19.52348 0.02939286 -2.48394546 -1.062498 001

b 0.00018107 -- -- -0.00005304 200

b -0.0094125 -0.00015395 -0.00213853 -0.00273493 020

b -8.395215 -- -- 1.11134946 002

b -- -- -- -- 110

b 0.077718 -0.0010827 -0.0435649 -0.03088295 101

b -- -- -0.61745089 -- 011

b 0.0000173 -- -0.00001282 -0.00000235 210

b 0.02733 0.00030703 0.00895359 0.00798746 021

b 0.001434 -- -0.00072472 -- 201

b -0.0000035 -- 0.0000054 -- 120

b -- -0.0023584 0.50028060 -0.00674491 012

b -0.00298 -- 0.00143598 0.00026587 202

b -0.019492 -0.00018233 -0.00855375 -0.00610522 022

Before continuing, the accuracy of using tabulated "average" parameter values is illustrated through a

comparison of measured capillary pressure curves with the average for sand. Figure 43 shows the average

curve for Brakensiek et al.'s sand and data from several sands measured at RSKERL using a technique

developed by Su and Brooks (1980). These sands are not meant to be a representative sample, but were

materials used in several experiments. The class "sand" is seen to contain much variability and the average

curve does not necessarily represent any particular sand.
171 [Appendix 3 Sources of Parameter Data]

Figure 43 Comparison of average capillary pressure curves with measured data

The 20/30, C109 and "Texas" sands are commercial products with relatively uniform pore size

distributions. The curves appear almost as step functions. The TCS sand from Traverse City, Michigan, and

the Lincoln and Oil Creek sands, both from Pontotoc County, Oklahoma, are natural materials. Oil Creek has

a uniform pore size distribution and is not very representative of sands in general. The Lincoln has a wider

distribution of pore sizes than the others and has a less abrupt curve. The Carsel and Parrish average curve

has a much lower air entry head, suggesting that their data set was dominated by coarse sands. Data, such

as shown in Figure 43, may be fitted to either of the capillary pressure models by non-linear curve fitting

procedures. The model called Retention Curve (RETC) by van Genuchten et al. (1991) is a special purpose

program for fitting these models to data.
co ' Ko cw

Ko '

Tk j

coj

Tj

sk (k

[Appendix 3 Sources of Parameter Data] 172

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3.2 NAPL/Water Partition Coefficient

Partitioning of chemicals constituents which compose the NAPL between the NAPL and water phase is

another phenomena of major importance. In HSSM this partitioning is assumed to follow a linear equilibrium

relationship

where c is the concentration in NAPL, c is the concentration in water, and K is the dimensionless NAPL/water ow o

partition coefficient. The magnitude of this coefficient has a major influence on the model results as it partially

determines how much of the chemical is released from the NAPL to the water.

K depends on the composition of the NAPL. Based on their work with 31 gasoline samples, Cline et al. o

(1991) suggest that Raoult's Law can be used to estimate K for gasoline mixtures. Raoult's Law provides an o

estimate of K for the k constituent of a NAPL that is composed of a total of j constituents as o

th

where Tj is the molecular weight of the j constituent (g/mol), c is the concentration of the j constituent in the oj

th th

oil phase (g/L), s is the solubility of species k in water (g/L), and ( is the activity coefficient of the k species. k k

th

The activity coefficients equal 1.0 for ideal solutions. Equation (44) indicates that the magnitude of K depends o

on the composition of the NAPL, so it is not possible to tabulate values of K for universal application. Table o 

98 contains partitioning and solubility data for several organic compounds of interest.

 

Table 98 Partitioning Characteristics ( Mercer et al., 1990, Cline et al., 1991, Chemical a bc

Information Systems, 1994)

Constituent Water Solubility K

(mg/L) (mL/g) or (L/kg) oc

benzene 1750 83 a

ethylbenzene 152 1100 a

toluene 535 300 a

m-xylene 130 982 a

o-xylene 175 830 a

p-xylene 196 870 a

MTBE methyl tert-butyl ether 48000 11.2 b c
173 [Appendix 3 Sources of Parameter Data]

The compositional dependence of K presents a o o problem in that K varies with the composition of the

NAPL: gasoline, diesel, fuel, oil, etc. In order to apply equation (44) the concentration C of each component oj

or general class of components in the NAPL mixture must be known. Further, as more soluble components

of the NAPL are lost, K may change. Cline et al.'s (1991) measured partition coefficients for benzene and o

toluene, however, showed only a slight variation with concentration.

Baehr and Corapcioglu (1987) used a simplified mixture to represent gasoline which is shown in Table 99.

From this composition several K 's are calculated from equation (44) and are listed in Table 100. Note that o

benzene, toluene and o-xylene are all hydrophobic, but the degree of hydrophobicity varies widely. Included

in the tables are data for methyl tert-butyl ether (MTBE), an octane enhancer which may occupy up to 15% of

gasoline by volume (Cline et al., 1991). The values calculated by using the mixture of Baehr and Corapcioglu

(1987) compare favorably with the values measured by Cline et al.(1991).

Table 99 Pseudo-Gasoline Mixture (Baehr and Corapcioglu, 1987)

Constituent Initial C Molecular oj

(g/cm ) weight 3

Tj

benzene 0.0082 (1.14%) 78

toluene 0.0426 (6.07%) 92

xylene 0.0718 (10.00%) 106

1-hexene 0.0159 (2.22%) 84

cyclohexane 0.0021 (0.29%) 84

h-hexane 0.0204 (2.84%) 86

other aromatics 0.0740 (10.31%) 106

other paraffins (C -C ) 0.3367 (46.91%) 97.2 4 8

heavy ends (> C ) 0.1451 (20.21%) 128 8
Ko '

1 × 106 Do

To

sk

Tk

[Appendix 3 Sources of Parameter Data] 174

(45)

 Table 100 Fuel/Water Partition Coefficients Measured by Cline et al. (1991)

compared with K values calculated from Corapacioglu and Baehr (1987) in o 

parentheses.

 Constituent Average Coefficient of

K variation o

% dev.

MTBE 15.5 19

methyl tert-butyl ether

benzene 350 (312) 21

toluene 1250 (1202) 14

ethylbenzene 4500 13

m-,p-xylene 4350 12

o-xylene 3630 (4440) 12

n-propylbenzene 18500 30

3-,4-ethyltoluene 12500 19

1,2,3-trimethylbenzene 13800 20

Assuming ideality, Cline et al. (1991) used a further approximation to Raoult's law, which can be stated

as

where Do is the NAPL phase density (g/ml), T is the average molecular weight of the NAPL phase (g/mol), Tk

o

is the molecular weight of constituent k (g/mol), and S is the solubility of the constituent of interest in mg/L. k

Cline et al.(1991) demonstrated that this approximation provided an adequate fit to the measured partition

coefficients from their 31 samples of gasoline. Cline et al. used an average gasoline density of 0.74 g/ml and

average gasoline molecular weight of 100-105 g/mol. The measured partition coefficients showed

approximately 30% variation, and the fitted Raoult's law relationship adequately represented the trend of the

values on a log-log plot. Appendix 6 describes a utility program called RAOULT which performs the Raoult's

law calculations using equations (44) and (45).

In addition to the partition coefficient, the composition of the NAPL is important in determining the

constituent concentrations in the contaminated ground water. Since the water phase concentration depends

on the oil phase concentration, the composition of the NAPL dictates both the partition coefficient and the

amount of constituent that is available for contamination of the water phase. 
1w ' Sw & Swr

1 & Swr

' hc e

z

8

, z > hce

pbij ' pbaw

Fij

Faw

' Dw g hc e

Fij

Fa w

pcij ' )Dij g z

175 [Appendix 3 Sources of Parameter Data]

(46)

(47)

(48)

3.3 Estimation of the Maximum NAPL Saturation in the Lens

When LNAPL accumulates in a lens it displaces water from the capillary fringe and from below the water

table. Not all of the wetting phase is displaced, and the LNAPL saturation increases from the base of the lens

towards the top. The distribution of LNAPL near the water table is determined by the forces of gravity and

capillarity, and by the dynamics of water table fluctuations. The usual way of monitoring LNAPL thickness is

through observation wells. Under conditions where the water table is static, these observation wells record the

true energy distribution within the formation, independent of capillary forces. Because the observation wells

have a large radius, the capillary pressure is negligible. When the water table fluctuates, such as in a tidal

environment, the observation well LNAPL thickness may show little resemblance to the actual thickness within

the formation (Kemblowski and Chiang, 1990). HSSM assumes that the water table is static and requires that

an average LNAPL saturation within the lens be estimated. This appendix outlines the method for estimating

the average LNAPL saturation and Appendix 7 describes the NTHICK utility for performing these calculations.

The maximum LNAPL phase saturation in the lens is determined through approximation of the LNAPL

distribution in the capillary fringe. The soil moisture retention curve gives the distribution of water in a twophase, air-water system, which using the Brooks and Corey model is

where z is measured upward from the water table and 1w is the reduced water saturation. At elevations below

the entry head, h , 1 is equal to one. Equation (46) gives the reduced water saturation as a function of ce w

elevation above the water table under conditions of vertical equilibrium. To apply this model to a multiphase

system that includes free product at the water table, one must determine how the equilibrium behavior for an

air-LNAPL and LNAPL-water system can be estimated from those for the air-water system. If changes in the

soil structure (swelling, etc.) are neglected, then the difference in behavior from one fluid system to another can

be attributed only to differences in fluid properties. The development of expressions for relationships between

the fluid distributions begins with the Brooks and Corey parameters for the air-water system: h , 8 and S . For ce wr

multiple fluid systems the subscripts 'w', 'o' and 'a' designate the water, NAPL and air phases. The first

generalization of equation (46) gives relationships for the entry pressures in a system composed of fluids i and

j

where p is the bubbling bij (or entry) pressure in a system composed of fluids i and j, Fij is the interfacial tension

between fluids i and j, and g is the acceleration of gravity. p is the entry pressure that is associated with the baw

entry head, h . Equation ce (47) follows from the assumption that the maximum pore size remains constant and

that the entry pressure depends only on the surface tension. The capillary pressure between fluids i and j, pcij

is defined by
1j ' Dw hce Fij

)Dij Faw z

8

' hceij

z

8

hceij ' Dw hc e Fij

)Dij Faw

1w ' 1w( pcow) ' hceow

z & zow

8

1t ' 1t( pcao ) ' hceao

z & zao

8

[Appendix 3 Sources of Parameter Data] 176

(49)

(50)

(51)

(52)

where )Dij is the difference in density between fluids i and j, and the datum z is chosen at the elevation where

the capillary pressure vanishes. This gives

for z $ h where j is the wetting phase and cij

Similar scaling relationships were introduced by Leverett (1941) and later used by van Dam (1967), Schiegg

(1985), Parker et al. (1987), Cary et al. (1989), Demond and Roberts (1991), and others. For the air-NAPL

system )D may be taken as equalling D , because of the low density of air. ao o

In a three-phase system, water is taken as the wetting fluid, the LNAPL is taken as being of intermediate

wettability, while air is the nonwetting fluid. The implication of this wettability order is that water resides in the

small pores, LNAPL in the intermediate pores and air in the largest pores. Since the capillary pressure

relationships are defined for two-fluid pairs, one has to work with the fluid pairs separately in a three-phase

system. This approach has been developed by Leverett (1941) and adopted by Schiegg (1985), Parker et al.

(1987) and others. The Leverett assumption is that the water saturation in a three phase system depends only

on the NAPL-water capillary pressure, while the total liquid saturation, S = S + S , is a function of the interfacial two

curvature of the air-NAPL interface, independent of the number or proportions of liquids contained in the porous

medium. With the Brooks and Corey power-law retention model, these relationships may be written as

 

and

where z and z are the elevations at which the corresponding capillary pressures would vanish. ow ao

Since the LNAPL residual saturations above and below the water table may be different, the scaling

functions for the reduced saturations are 
1w(pcow) ' Sw & Swr

1 & Swr & Sors

1t(pcao) ' St & Swr & Sorv

1 & Swr & Sorv

' Sw % So & Swr & Sorv

1 & Swr & Sorv

za w & zow ' Do

Dw

bo

za o & zaw ' Dw & Do

Dw

bo

Do ' m 2t & 2w dz

177 [Appendix 3 Sources of Parameter Data]

(53)

(54)

(55)

(56)

(57)

and

where S is the water retention or "field capacity", and S and S are the residual NAPL saturations in the wr ors orv

saturated and vadose zones, respectively.

Together, equations (51) through (54) determine the fluid distribution near the water table. What is still

lacking is a determination of the capillary pressure datums z and z . However, these are the levels at which ow ao

one would find the fluid interfaces in observations wells where capillary forces are absent, and the problem

reduces to the standard manometer problem from hydrostatics. Let the elevation z be that of the free water aw

interface in the absence of NAPL, while z and z are the corresponding elevations when a NAPL layer of ao ow

apparent thickness b and density D is present. A simple calculation from hydrostatics shows that o o

 where D is the density of water. One also finds that w

The total thickness of the hydrocarbon present in the free product region, exclusive of any hydrocarbon

trapped above or below the water table, is found by integrating the difference between the total liquid content

and the water content over the free product region:

This usage of the NAPL layer thickness, D , corresponds to that of Schwille (1967) who used it for the o ratio

between the amount of NAPL spreading laterally on the groundwater surface and the area occupied by it.

Other authors have referred to the NAPL layer thickness as that which may be observed visually in a laboratory

apparatus. 

The total liquid and water contents are estimated using a modified form of the Brooks and Corey capillary

pressure function with h equal to the elevation above the fluid interface as seen in an observation well. The c
hceow ' Dw Fow

(Dw & Do ) Fa w

hceao ' Dw Fao

Do Faw

hc e

Do ' " % $(bo ) bo

" ' 0 8 1 & Swr & Sors hceow & 8 1 & Swr & Sorv hceao

1 & 8

$ ( bo ) ' 0 (1 & Swr) % P

1 & P

0 Sorv

& 0 (1 & Swr & Sors)

1 & 8

( 1 & P) hceow

bo

8

P ' Fao

Fow

Dw & Do

Do

1 & Swr & Sorv

1 & Swr & Sors

1/8

[Appendix 3 Sources of Parameter Data] 178

(58)

(59)

(60)

(61)

(62)

(63)

elevation for the water content is measured from the level of the hydrocarbon-water interface while the elevation

for the total liquid content is measured from the level of the air-hydrocarbon interface in the well. The

nonwetting phase entry heads for the hydrocarbon-water, and air-hydrocarbon fluid systems, h and h ceow ceao

respectively, are estimated from

and

where h is the ce normal air entry head for the air-water system. With equations (51) to (54) the integral in

equation (57) can be evaluated. The result may be written as

where 
So(max) ' Do

0 bo

' 1

0

"

bo

% $

179 [Appendix 3 Sources of Parameter Data]

(64)

Similar results have been presented by Farr et al. (1990) and Parker and Lenhard (1989). In equation (60),

b is the hydrocarbon layer thickness one would o see in a large capillary (observation well), and S and S are orv ors

the residual hydrocarbon saturations above and below the lens, respectively. The function $(b ) has only a o

weak dependence on b , especially at moderate to large LNAPL layer thicknesses. o This implies that the

relationship between D and b is nearly linear. o o The ratio of the averaged formation thickness, D , and the o

observation well thickness, b , gives the average NAPL saturation in the lens o
8 ' m

1&m

(1 & 0.5

1

m )

hce ' S

( 1

8

)

(

"

(S

( &1

m )

( & 1)1 & m

m ' 1 & 1

n

S( ' 0.72 & 0.35 exp (& n 4)

[Appendix 4 Capillary Parameters] 180

(65)

(66)

(67)

(68)

Appendix 4 Approximate Conversion of Capillary Pressure Curve

Parameters

KOPT and OILENS are designed primarily to use Brooks and Corey's model, however, HSSM-KO allows

the entry of van Genuchten capillary pressure parameters. These are not used directly by the model but rather

are automatically converted into approximately equivalent Brooks and Corey parameters by a method proposed

by Lenhard et al. (1989). Since van Genuchten's model is not equivalent in form to the Brooks and Corey

model, the parameters are not exactly equivalent. The conversion is given by

where

and S is defined by Lenhard et al.'s (1989) empirical relation *

Figure 44 and Figure 45 compare the Brooks and Corey model with van Genuchten's model for equivalent

parameter sets. The equivalent parameter sets are shown in Table 101.

 Table 101 Equivalent Capillary Pressure Curve Parameters

Soil Texture Brooks and Corey van Genuchten

22 8 m r ce h n "

Sand 0.43 0.0443 1.1852 4.628 2.7953 0.1417

Sandy Clay loam 0.39 0.1121 0.3887 8.0941 1.4321 0.0858
181 [Appendix 4 Capillary Parameters]

Figure 44 Comparison of equivalent Brooks and Corey and van Genuchten parameters for sandy soil

Figure 45 Comparison of equivalent Brooks and Corey and van Genuchten parameters for sandy clay loam soil.
[Appendix 5 The SOPROP Utility] 182

Appendix 5 The Soil Property Regression Utility (SOPROP)

The SOPROP utility is provided with HSSM in order to estimate soil properties from the set of regression

equations developed by Rawls and Brakensiek (1985). SOPROP is executed from the DOS prompt by the

command:

SOPROP

No input or output files are required as all the input to and output from the utility are directed to the screen. The

user is prompted for 1) the percent sand, PS , 2) the percent clay, PC, and 3) the porosity, 0. The hydraulic

conductivity and Brooks and Corey parameters are calculated and then written to the screen as shown in Table

102. Recall that the data upon which the regression equations are from agricultural and forest soils; so the

SOPROP output is appropriate for similar soils with percent sand between 5.0 and 70.0 and percent clay

between 5.0 and 60.0.

Table 102 SOPROP Screen Output

 *********************************************

 Estimate of soil hydraulic properties

 from Rawls and Brakensiek (1985)

 regression equations

 *********************************************

 for the soil with:

 70.0000 percent sand

 5.0000 percent clay

 .3500 porosity

 the estimated hydraulic parameters are:

 hydraulic conductivity .4257 m/d 

 Brooks and Corey parameters:

 residual water saturation .1403

 air entry head .1754 m 

 pore size distribution index .4902

 ***successful execution of soprop

The range of parameter values that are produced by these equations are shown in Table 103. One

extreme occurs when the percent sand is at its maximum value (70%) and the percent clay is at its minimum

value (5%). The hydraulic conductivity, as expected, is highest (0.92 m/d) with highest porosity (0.40).

Hydraulic conductivities greater than this value are out of the range of the tabulated parameters which form the

basis for the regression equations. Likewise another extreme occurs when the percent sand is a minimum (5%)

and the percent clay is a maximum (60%). With low porosity (0.30) the conductivity is low (2.3 x 10 m/d) and -7 

the air entry head is high (6.4 m). 
183 [Appendix 5 The SOPROP Utility]

Table 103 Range of parameter values produced by the Rawls and Brakensiek (1985) regression

equations 

SOPROP input parameters SOPROP results

Percent Percent Porosity K S h 8

sand clay (m/d) (m) s wr ce

70 5 0.40 0.92 0.12 0.14 0.46

70 5 0.35 0.43 0.14 0.18 0.49

70 5 0.30 0.18 0.18 0.24 0.53

70 5 0.25 0.065 0.22 0.33 0.58

5 60 0.50 1.5 x 10 0.21 1.3 0.12 -3

5 60 0.40 1.3 x 10 0.16 2.9 0.053 -5

5 60 0.30 2.3 x 10 0.023 6.4 0.015 -7
[Appendix 6 The RAOULT Utility] 184

Appendix 6 The RAOULT Utility

Calculation of the NAPL/water partition coefficient, K , is simplified through the usage of the o RAOULT

utility. This utility uses the composition of the hydrocarbon phase for determining the partition coefficient with

equations (44) and (45). The utility is executed by typing

RAOULT

at the DOS prompt. The program automatically reads a default data set for gasoline and begins execution of

the program.

Table 104 shows the default data set screen messages written by RAOULT. The data is taken from Baehr

and Corapcioglu (1987) and is contained in the file RAOULT.DAT. The data file may be edited or the data

changed interactively by entering a 'Y' at the "Change the input data ?" prompt. The procedures for changing

the data are given below. 

Table 104 RAOULT Utility Main Screen

 **************************************************

 Raoults Law Partitioning Calculation

 **************************************************

 Chemical Solubility Conc. Molecular Activity 

 (mg/L) (g/cm3) Weight Coefficient

 ==================== ========== ========== ========== ==========

 1 benzene 1750.0000 .0082 78.0000 1.0000

 2 toluene 535.0000 .0426 92.0000 1.0000

 3 xylenes 167.0000 .0718 106.0000 1.0000

 4 1-hexene .0000 .0159 84.0000 1.0000

 5 cyclohexane .0000 .0021 84.0000 1.0000

 6 n-hexane .0000 .0204 86.0000 1.0000

 7 other_aromatics .0000 .0740 106.0000 1.0000

 8 other_paraffins .0000 .3367 97.2000 1.0000

 9 heavy_ends .0000 .1451 128.0000 1.0000

Change the input data ? (Y or N)

With no changes in the input data set (answer 'N' to the "Change the input data ?" prompt, see Table 105),

RAOULT determines the density of the hydrocarbon and its average molecular weight. These quantities are

used to calculate the hydrocarbon/water partition coefficient using equations (44) and (45). The two results are

similar and are denoted as determined by the composition basis and the average molecular weight basis,

respectively. The user has the option of calculating partition coefficients for other constituents or exiting the

utility.
185 [Appendix 6 The RAOULT Utility]

Table 105 Sample RAOULT Calculation for the Benzene Constituent of Gasoline

Change the input data ? (Y or N)

N

 Hydrocarbon density = .7168

 Avg. Molecular Weight = 104.0458

Select constituent of interest by number

1

 Calculated Hydrocarbon/Water Partition Coefficient:

 Composition basis:

 311.6757

 Average molecular weight basis:

 307.0647

Exit ? (Y or N)

Y

 *** successful execution of raoult

The default hydrocarbon composition can be changed by direct editing of the RAOULT.DAT data file. The

default data set is shown in Table 106. The data set is mostly free format input, with the exceptions noted. The

first line contains the number of chemicals composing the hydrocarbon; in this case nine. RAOULT will accept

200 chemicals composing the hydrocarbon phase. The rest of the lines contain the data for each chemical.

The chemical name is given first and must be contained within the first 20 spaces of each line. The name may

contain any combination of letters, numbers, or other keyboard characters; it may not, however, contain any

blanks. In the default data set, blanks are replaced by underscores (as in "other_aromatics"). RAOULT

terminates the chemical name at the column where the first number is found, so all 20 of the spaces allocated

for the chemical name do not have to be used. Each line contains the following data for the chemical:

9 concentration of the chemical in the NAPL in g/cm ,3

9 pure compound aqueous solubility of the chemical in mg/L,

9 molecular weight of the chemical (g/mol), and

9 the activity coefficient.

Here the activity coefficients are taken as being equal to 1.0. Each of the data items must be separated by at

least one blank.

 
[Appendix 6 The RAOULT Utility] 186

Table 106 Default RAOULT.DAT Data Set

 9

 benzene 0.0082 1750. 78. 1.

 toluene 0.0426 535. 92. 1.

 xylenes 0.0718 167. 106. 1.

 1-hexene 0.0159 0. 84. 1.

 cyclohexane 0.0021 0. 84. 1.

 n-hexane 0.0204 0. 86. 1.

 other_aromatics 0.0740 0. 106. 1.

 other_paraffins 0.3367 0. 97.2 1.

 heavy_ends 0.1451 0. 128. 1.

The data can also be modified interactively within RAOULT by answering 'Y' to the "Change the input data

?" prompt. Table 107 shows the sequence of prompts for changing the benzene solubility from 1750 mg/L

to 1780 mg/L and the resulting calculated partition coefficients. 
187 [Appendix 6 The RAOULT Utility]

Table 107 Interactive Modification of the RAOULT Default Data Set

Change the input data ? (Y or N)

Y

Select item to change by number

1

Select data item to change

1 Name

2 Solubility

3 Concentration

4 Molecular Weight

5 Activity Coefficient

2

Enter the new solubility in mg/L

1780.

Change another data item? (Y or N)

N

 Chemical Solubility Conc. Molecular Activity 

 (mg/L) (g/cm3) Weight Coefficient

 ==================== ========== ========== ========== ==========

 1 benzene 1780.0000 .0082 78.0000 1.0000

 2 toluene 535.0000 .0426 92.0000 1.0000

 3 xylenes 167.0000 .0718 106.0000 1.0000

 4 1-hexene .0000 .0159 84.0000 1.0000

 5 cyclohexane .0000 .0021 84.0000 1.0000

 6 n-hexane .0000 .0204 86.0000 1.0000

 7 other_aromatics .0000 .0740 106.0000 1.0000

 8 other_paraffins .0000 .3367 97.2000 1.0000

 9 heavy_ends .0000 .1451 128.0000 1.0000

Change the input data ? (Y or N)

N

 Hydrocarbon density = .7168

 Avg. Molecular Weight = 104.0458

Select constituent of interest by number

1

 Calculated Hydrocarbon/Water Partition Coefficient:

 Composition basis:

 306.4227

 Average molecular weight basis:

 301.8895

Exit ? (Y or N)

Y

 *** successful execution of raoult
[Appendix 7 The NTHICK Utility] 188

Appendix 7 The NTHICK Utility

A utility program, NTHICK, is provided with HSSM for calculating the averaged LNAPL saturation in the

lens, S , based upon the theory presented in Appendix 3.3. NTHICK uses the values from the HSSM-KO o(max)

input data set to develop a relationship between observation well thicknesses, averaged formation LNAPL

thicknesses and the average LNAPL saturations. NTHICK requires a number of parameters taken from the

HSSM-KO input data set. These parameters are listed in Table 108 and can be written into the NTHICK input

file manually (Table 109). Manual data entry, however, is not necessary because HSSM-KO automatically

creates a file with the extension .NTH that contains almost all of the NTHICK input parameters. Only the

LNAPL/water interfacial tension, Fow, which is not used by HSSM-KO or HSSM-T, must be added to the .NTH

file produced by HSSM-KO. NTHICK prompts for the value of Fow if it is not found in the .NTH file, and rewrites

the file including the F value as the 5 line of the *.NTH file. The program also writes all output to the input ow

th

data file (*.NTH). This process does not interfere with later running of NTHICK with the data set; any earlier

results are lost, however, when the program is rerun with a previously used input data file.

Table 108 NTHICK required input data

*.NTH data file line Parameters

Line 1 Porosity, 0

Air entry head, h (m) ce

Brooks and Corey's 8

Residual water saturation, Swr

Line 2 Vadose zone residual LNAPL saturation, Sorv

Aquifer residual LNAPL saturation, Sors

Line 3 Water surface tension, F (dyne/cm) aw

LNAPL surface tension, F (dyne/cm) ao 

Line 4 Water density, D (g/cm ) w

3

LNAPL density, D (g/cm ) o

3

Line 5 LNAPL/water interfacial tension, F (dyne/cm) ow

Table 109 NTHICK Input Data File

 .4000 0.07 1.500 .10

 .12500 .25

 70.000 30.0000

 1.0000 .7200

 45.0000
189 [Appendix 7 The NTHICK Utility]

The result of the program is a list of thicknesses and LNAPL saturations. Table 110 shows a typical set

of output messages from NTHICK. The messages are written both to the screen and to the input data file as

noted above. First NTHICK echoes the input data set. It follows with the calculated list of observation well

thicknesses in meters, averaged formation thicknesses in meters and LNAPL saturations in the lens. The lens

thicknesses obviously vary with radius and no one value of S is exactly correct for the whole lens. o(max)

HSSM requires, however, a single value of LNAPL saturation in the lens as input. A procedure for

determining a value of S is given in the following section. o(max)

Table 110 Typical NTHICK Output Messages

 *********************************************

 Estimate of NAPL saturation in OILENS

 *********************************************

 Porosity .4000 (*)

 Air entry head .0700 (m)

 Brooks and Corey lambda 1.5000 (*)

 Residual water saturation .1000 (*)

 Vadose zone residual NAPL sat. .1250 (*)

 Aquifer residual NAPL sat. .2500 (*)

 Water surface tension 70.0000 (dyne/cm)

 NAPL surface tension 30.0000 (dyne/cm)

 Water density 1.0000 (g/cc)

 NAPL density .7200 (g/cc)

 NAPL/water interfacial tension 45.0000 (dyne/cm)

 Observation Averaged NAPL 

 Well Formation Saturation

 Thickness Thickness 

 (m) (m) 

 ============ ============ ==========

 .1190 .0005 .0112

 .2690 .0382 .3553

 .4190 .0877 .5230

 .5690 .1404 .6167

 .7190 .1945 .6764

 .8690 .2495 .7177

 1.0190 .3049 .7481

 1.1690 .3607 .7714

 1.3190 .4167 .7898

 1.4690 .4729 .8047

 1.6190 .5292 .8171

 1.7690 .5856 .8276

 1.9190 .6421 .8365

Exit the program ? (Y or N)

The "Exit the program ?" prompt at the end of Table 110 either terminates the program by answering "N,"

or by answering "Y" continues to the estimation of the NAPL saturation for a specific NAPL formation thickness.
[Appendix 7 The NTHICK Utility] 190

Table 111 shows the series of NTHICK prompts that occurs when the program execution continues. The user

is asked to enter the NAPL thickness in the formation in meters: here 0.1410 m is used. As shown in Appendix

7.1 below, the NAPL formation thickness is obtained from the HSSM model output. NTHICK responds by

echoing the specified average NAPL thickness (.1410) and calculating the associated NAPL lens saturation

(.3217).

Table 111 NAPL Saturation Estimation in NTHICK

Exit the program ? (Y or N)

n

Enter the average NAPL thickness in the formation (m)

.1410

 Specified avg. NAPL thickness in the formation = .1410 (m)

 NAPL lens saturation = .3217 (*)

7.1 Procedure for Using NTHICK

As noted above, the LNAPL lens saturation depends on the thickness of the lens. A procedure for using

NTHICK for determining the lens saturation is given below:

 Develop a data set for HSSM-KO including a trial value of S and several profile times. o(max)

 Run HSSM-KO.

 Edit the *.HSS output file and determine the maximum thickness of the lens. The maximum thickness of

the lens can be determined from the lens profiles. The maximum thickness of the lens is read by subtracting

the maximum depth of the top and bottom of the lens (columns 4 and 5 of the first row of data in Table 112).

 The output in this table is from the X2BT.DAT data set described in Section 5.2.

If this thickness is not greater than the difference between columns 2 and 3, then the lens has not yet

reached its maximum extent and a later profile time must be used. In this case the maximum lens extent from

columns 4 and 5 is 10.0943 m - 9.9533 m = 0.1410 m, which is greater than the current lens extent from

columns 2 and 3 of 10.0440 m - 9.9729 m = 0.0711 m. Since the maximum lens extent is greater than the

current lens extent, this profile can be used for determining the lens thickness and the thickness 0.1410 m is

entered into NTHICK.

 Run NTHICK with the thickness determined from step . The thickness is entered interactively in the

second part of the NTHICK screen messages (Table 111). NTHICK calculates the associated lens saturation

S . o(max)

 Average the input S from step  and that from step . o(max)

 Rerun HSSM with the S determined in step . o(max)

 Repeat until the S values are o(max) within 0.01. If this procedure fails to converge within a few trials, a

bisection approach should be used (Forsythe et al., 1977).
191 [Appendix 7 The NTHICK Utility]

Table 112

 Lens profile from the *.HSS output file

 **************************************************

 * RADIAL PROFILE THROUGH OIL LENS

 **************************************************

 TIME = 200.0000

 LENS RADIUS = 10.6437

 DEPTH TO WATER TABLE = 10.0000

 CURRENT NAPL LENS MAXIMUM EXTENT OF NAPL LENS

 RADIUS DEPTH OF DEPTH OF DEPTH OF DEPTH OF 

 TOP OF LENS LENS BOTTOM TOP OF LENS LENS BOTTOM

 ========== =========== =========== =========== ===========

 (1) (2) (3) (4) (5)

 .0000 9.9729 10.0440 9.9533 10.0943

 2.0000 9.9729 10.0440 9.9533 10.0943

 2.4322 9.9739 10.0413 9.9579 10.0827

 2.8644 9.9748 10.0390 9.9617 10.0727

 3.2966 9.9757 10.0368 9.9650 10.0642

 3.7287 9.9764 10.0348 9.9680 10.0567

 4.1609 9.9772 10.0330 9.9704 10.0503

 4.5931 9.9779 10.0312 9.9726 10.0446

 5.0253 9.9785 10.0295 9.9746 10.0397

 5.4575 9.9792 10.0278 9.9762 10.0354

 5.8897 9.9798 10.0262 9.9777 10.0315

 6.3218 9.9804 10.0246 9.9790 10.0282

 6.7540 9.9811 10.0229 9.9802 10.0251

 7.1862 9.9817 10.0213 9.9812 10.0226

 7.6184 9.9823 10.0197 9.9821 10.0202

 8.0506 9.9830 10.0180 9.9830 10.0181

 8.4828 9.9837 10.0162 9.9837 10.0162

 8.9149 9.9844 10.0143 9.9844 10.0143

 9.3471 9.9852 10.0123 9.9852 10.0123

 9.7793 9.9861 10.0099 9.9861 10.0099

 10.2115 9.9873 10.0069 9.9873 10.0069

 10.6437 9.9900 10.0000 9.9900 10.0000

 CUMULATIVE INFLUX TO LENS 1555. 

 KOPT AND OILENS GLOBAL MASS BALANCES

 TOTAL NAPL MASS ADDED AT BOUNDARY (KG) 4091. 

 NAPL MASS RECOVERED BY MASS BALANCE (KG) 4059. 

 PER CENT ERROR -.7962 
[Appendix 7 The NTHICK Utility] 192

7.2 Example NTHICK Calculation Sequence

Table 113 shows an example sequence of NTHICK and HSSM-KO results which are used to define the

input parameter, S . Co o(max) o(max) lumn (a) lists the trial values of S that were used in the X2BT.DAT data set. In

the first trial the value was arbitrarily set to 0.5000. Column (b) gives the maximum NAPL lens thickness in

meters as determined from the X2BT.HSS file as discussed above. These values were used in NTHICK to

determine the appropriate value of S for the lens (column c). Since the values in columns (a) and (c) do o(max)

not match (0.5000 vs. 0.2253), the appropriate input value was not used and another trial is needed. The

second trial begins with S set to o(max) the average of the previous values in columns (a) and (c), that is 0.5 times

(0.5000 + 0.2253) = 0.3627. The sequence of running HSSM-KO, determining the maximum NAPL lens

thickness, and estimating the appropriate value of S o(max) continues until the values in column (a) and (c) match

fairly closely. In this example it took four iterations to find the correct value of about 0.32 for S . o(max)

Table 113 Example sequence of NTHICK and HSSM-KO results

Trial Initial NAPL Saturation Maximum NAPL lens NAPL Saturation from

S thickness NTHICK o(max)

(a) (b) (c)

1 0.5000 0.0803 0.2253

2 0.3627 0.1219 0.2948

3 0.3288 0.1393 0.3194

4 0.3240 0.1421 0.3231
193 [Appendix 8 The REBUILD Utility]

Appendix 8 The REBUILD Utility

Both of the computational modules of HSSM use temporary files for writing output and plot files. Only at

the end of a successful simulation are the temporary files concatenated into output and plot files named as the

user has specified. If a simulation is interrupted for any reason, the concatenation of the temporary files will

not occur. The user would be left with bits and pieces of the simulation output scattered among the temporary

files. The REBUILD utility is designed to create the main output files (name.HSS and name.TSG) from the

temporary files. It also attempts to create the plot files. It is not uncommon, however, that the plot files have

incomplete lines or data sets and cannot be plotted. REBUILD does not attempt to recreate the HSSM-T input

data file on the assumption that an interrupted simulation cannot have the proper mass flux distribution to run

HSSM-T. REBUILD is executed by simply typing

REBUILD

from DOS or by selecting menu option (3c) "Run REBUILD" from Windows. REBUILD uses the temporary files,

if they exist, to gather the correct file names for "rebuilding." Thus REBUILD is totally automated. 
[Appendix 9 Dual Installation] 194

Appendix 9 Dual Installation of the DOS and Windows Interfaces

 

Both interfaces can be installed on the same machine by following these instructions:

 Complete the DOS installation process described in Section 1.7.

 Add the HSSM directory to the path as described in Section 1.7.

 Complete the Windows installation procedure described in Sections 4.3 and 4.3.3. The HSSM directory

should be the same as used for the DOS installation.

The dual installation results in one copy each of HSSM-KO.EXE, HSSM-T.EXE and the other files being copied

to the hard drive. All of the components of the interfaces are found in this one directory. HSSM can then be

run from any DOS directory or from Windows. DOS and Windows input files can be used with either interface.

Windows, however, places the full directory path for the plot and output file names in the HSSM input file (see

Table 15). This practice may lead to confusion if the files are later used with the DOS interface, because the

output and plot files may be placed in a directory other than that occupied by the input file. The confusion does

not arise when using the Windows interface, because HSSM-WIN automatically updates the file names to

match the current input file's directory.
195 [Appendix 10 HSSM-KO Data Files]

Appendix 10 Direct Editing of HSSM-KO Data Files

Sometimes it is convenient to edit data files directly, without using HSSM-WIN or PRE-HSSM. Table 114

shows the items which appear on each line of a valid data file. All data is entered format free; i.e., no special

spacing is required, although at least one space must separate each data item. In general an entry is required

for each variable given, even for features not used in a particular simulation; therefore, the use of PRE-HSSM

or HSSM-WIN for generating input files is recommended.

Table 114 HSSM-KO Input Data File Structure

C ******************************************************************

C *

C * KOPT REQUIRED INPUT DATA

C * DATA FILES MAY BE PREPARED OR EDITED BY USING THE PREHSSM

C * PREPROCESSOR

C *

C * INPUT ARGUMENTS:

C * IRO READ ONLY INDEX

C * IWO WRITE ONLY INDEX

C *

C * OUTPUT ARGUMENTS: NONE

C *

C * NOTES:

C * 1. ALL VARIABLE NAMES ARE IN ACCORDANCE WITH FORTRAN NAMC * ING CONVENTIONS--NAMES BEGINNING WITH I THROUGH M ARE

C * INTEGERS, ALL OTHERS ARE REALS.

C * 2. ALL INPUT IS FREE-FORMAT

C * 3. ZEROS SHOULD BE READ IN FIELDS PERTAINING TO UNUSED VALUES

C * 4. INPUT DATA UNITS ARE SPECIFIED AS FOLLOWS

C * (*) DIMENSIONLESS OR NOT APPLICABLE

C * (M) METERS

C * (D) DAYS

C * (C) DEGREES C

C * (CP) CENTIPOISE 1.0 CP = 0.01 GR/CM/SEC

C * (M/D) METERS PER DAY

C * (M2/D) METERS SQUARED PER DAY

C * (MG/L) MILLIGRAMS PER LITER

C * (L/KG) LITERS PER KILOGRAM SOIL

C * (GR/CC) GRAMS PER CUBIC CENTIMETER

C *

C * LINE 1.....PRINT OUTPUT FLAG...................................

C * IWR OUTPUT WRITING FACTOR (*)

C * 0 SUPPRESS ALL OUTPUT

C * 1 PRODUCE OUTPUT

C * IREO FOR IWR=1, READ AND ECHO PRINT INPUT DATA ONLY (*)

C * 0 READ AND ECHO PRINT INPUT DATA ONLY

C * 1 RUN MODEL

C *

C * LINE 2-4...RUN TITLE...(5A10/5A10/5A10)........................

C * NT(15) RUN TITLE 3 LINES OF 50 CHARACTERS EACH (*)

C *

C * LINE 5.....MATRIX PROPERTIES...................................

C * WKS SATURATED VERTICAL HYDRAULIC CONDUCTIVITY (WATER) (M/D)

C * RKS RATIO OF HORIZONTAL TO VERTICAL CONDUCTIVITY (*)
[Appendix 10 HSSM-KO Data Files] 196

C * KRF RELATIVE PERMEABILITY MODEL SELECTION INDEX (*)

C * 1 BURDINE--BROOKS & COREY MODEL

C * XLAMB PORE SIZE DISTRIBUTION INDEX (*)

C * FOR KRF = 1, ENTER LAMBDA

C * ETA POROSITY (*)

C * SWR RESIDUAL WATER SATURATION (*)

C *

C * LINE 6.....WATER PROPERTIES....................................

C * WMU DYNAMIC VISCOSITY OF WATER (CP)

C * WRHO DENSITY OF WATER (GR/CC)

C * IRT RAINFALL INPUT TYPE: 1=FLUX SPECIFIED (*)

C * 2=SATURATION SPECIFIED (*)

C * QW/SWMAX CONSTANT WATER FLUX OR SATURATION (M/D) OR (*)

C * XMKRW MAX WATER RELATIVE PERMEABILITY DURING INFILTRATION (*)

C * WTABLE DEPTH TO WATER TABLE (M)

C *

C * LINE 7.....OIL CHARACTERISTICS.................................

C * PMU DYNAMIC VISCOSITY OF OIL (CP)

C * PRHO OIL DENSITY (GR/CC)

C * SPR RESIDUAL (TRAPPED) OIL SATURATION (*)

C * IAT OIL INPUT TYPE 1=FLUX SPECIFIED (*)

C * 2=VOLUME/AREA SPECIFIED

C * 3=CONSTANT PONDING DEPTH

C * 4=VARIABLE AFTER CONSTANT PERIOD

C *

C * LINE 8.....CAPILLARY SUCTION APPROXIMATION.(ADDITIONAL PARAMETERS)

C * HWE AIR ENTRY HEAD (M)

C * WSIG WATER SURFACE TENSION (DYNE/CM)

C * OSIG OIL SURFACE TENSION (DYNE/CM)

C

C * LINE 9.....(FOR IAT=1 AND IAT=3)...OIL FLUX.....................

C * QP OIL FLUX FOR IAT = 1 CASES (M/D)

C * TPB OIL EVENT BEGINNING TIME (D)

C * TPE OIL EVENT ENDING TIME (D)

C * HS CONSTANT HEAD FOR IAT=3 CASES (M)

C *

C * LINE 9.....(FOR IAT = 2)...OIL VOLUME..........................

C * PVOL OIL VOLUME/AREA INCORPORATED INTO THE SOIL (M)

C * DPL LOWER DEPTH OF INITIALLY POLLUTED ZONE (M)

C *

C * LINE 10....DISSOLVED CONSTITUENT...............................

C * COINI INITIAL CONCENTRATION IN OIL (SEE NOTE 5.) (MG/L)

C *

C * LINE 11....DISSOLVED CONSTITUENT...............................

C * PARTITIONING COEFFICIENTS:

C * XXKO OIL/WATER (C0 = XXKW*CW) (*)

C * XXKV OIL/AIR (CA = XXKV*CO) (*)

C * XXKS SOLID/WATER (CONSTITUENT) (L/KG)

C * XXKSH SOLID/WATER (HYDROCARBON) (L/KG)

C * RHOS BULK DENSITY OF MATRIX (GR/CC)

C *

C * LINE 12....VOLATILIZATION MODEL................................

C * DAIR DIFFUSION COEFFICIENT FOR CONSTITUENT IN AIR (M2/D)

C * DWV DIFFUSION COEFFICIENT FOR WATER VAPOR (M2/D)

C * EVAP WATER EVAPORATION RATE (VOL./AREA/TIME) (M/D)

C * TEMP TEMPERATURE (C)

C * RH RELATIVE HUMIDITY (*)

C *
197 [Appendix 10 HSSM-KO Data Files]

C * LINE 13....OILENS SUB-MODEL PARAMETERS (1).....................

C * RADI SOURCE RADIUS (M)

C * RMF RADIUS MULTIPLYING FACTOR (*)

C * FRING HEIGHT OF CAPILLARY FRINGE (M)

C * VDISP VERTICAL DISPERSIVITY OF AQUIFER (M2/D)

C * GRAD GROUNDWATER GRADIENT (*)

C * SPRB TRAPPED OIL SATURATION BELOW THE WATER TABLE (*)

C *

C * LINE 14....OILENS SUB-MODEL PARAMETERS (2).....................

C * SOLC WATER SOLUBILITY OF CONSTITUENT (MG/L)

C * SOLH WATER SOLUBILITY OF HYDROCARBON (OIL) (MG/L)

C *

C * LINE 15....SIMULATION PARAMETERS...............................

C * TM SIMULATION ENDING TIME (SEE KSTOP) (D)

C * DM MAXIMUM SOLUTION TIME STEP (D)

C * DTPR MINIMUM TIME BETWEEN PRINTED TIME STEPS AND (D)

C * MASS BALANCE CHECKS

C * KSTOP ENDING CRITERIA (*)

C * 1 USER SPECIFIED ENDING TIME (TM)

C * 2 OIL LENS MOTION STOPS

C * 3 CONSTITUENT MASS FLUX TO AQUIFER LESS THAN MAXIMUM

C * 4 CONSTITUENT MASS IN OIL LENS LESS THAN OPERC*

C * MAXIMUM CUMULATIVE INFLUX TO LENS

C * (1 IS DEFAULT FOR NO OILENS SIMULATION OR WHEN OIL

C * DOES NOT REACH THE WATER TABLE BEFORE TIME = TM)

C * OPERC FACTOR USED WITH KSTOP = 4 (0.0 < OPERC < 1.0) (*)

C *

C * LINE 16....PROFILES............................................

C * NTIMES NUMBER OF PROFILES (UP TO 10) (*)

C *

C * LINE 17........................................................

C * PR(NTIMES) PROFILE TIMES (D)

C * OMIT LINE 17 IF NTIMES = 0

C *

C * LINE 18....TSGPLUME INPUT PARAMETERS...........................

C * DLONG AQUIFER LONGITUDINAL DISPERSIVITY (M)

C * DTRAN AQUIFER TRANSVERSE DISPERSIVITY (M)

C * PMAX PERCENT OF MAXIMUM CONSTITUENT RADIUS (*)

C * CMINW MIMINUM RECEPTOR WELL CONCENTRATION OF INTEREST (MG/L)

C * NWELL NUMBER OF RECEPTOR WELLS (UP TO 8) (*)

C *

C * LINE 19....TSGPLUME INPUT PARAMETERS 2..........................

C * BEGT BEGINNING TIME (D)

C * ENDT ENDING TIME (D)

C * TINC TIME INCREMENT (D)

C * TAQU AQUIFER THICKNESS (M)

C *

C * LINE 20........................................................

C * XWELL(I) X-COORDINATE OF RECEPTOR WELL (M)

C * YWELL(I) Y-COORDINATE OF RECEPTOR WELL (M)

C *

C ******************************************************************
[Appendix 11 HSSM-T Data Files] 198

Appendix 11 Direct Editing of HSSM-T Data Files

The required parameters for HSSM-T are listed in Table 115. As with HSSM-KO, all input data is format

free. It is recommended to create new HSSM-T input data files by running HSSM-KO.

Table 115 HSSM-T Input Data File Structure

C ******************************************************************

C * TSGPLUME INPUT DATA

C *

C * LINE 1

C * IFILE KOPT/OILENS INPUT DATA FILE (A40)

C * LINE 2

C * OFILE KOPT/OILENS OUTPUT DATA FILE (A40)

C * LINE 3

C * TFILE TSGPLUME INPUT DATA FILE (A40)

C * LINE 4

C * KKSTOP KOPT/OILENS STOPPING CRITERIA (A40)

C * LINE 5

C * AL LONGITUDINAL DISPERSIVITY (M)

C * AT TRANSVERSE DISPERSIVITY (M)

C * AV VERTICAL DISPERSIVITY (M)

C * VEL SEEPAGE VELOCITY (M/D)

C * POR POROSITY (*)

C * TAQU AQUIFER THICKNESS (M)

C * LINE 6

C * R RETARDATION FACTOR (*)

C * PMAX PERCENT MAXIMUM CONTAMINANT RADIUS (*)

C * CMIN MINIMUM OUTPUT CONCENTRATION (MG/L)

C * ZLAM AQUIFER DECAY COEFFICIENT (1/D)

C * LINE 7

C * BTIME BEGINNING TIME (D)

C * ETIME ENDING TIME (D)

C * TINTE TIME INCREMENT (D)

C * LINE 8

C * NWELL NUMBER OF RECEPTOR WELLS (*)

C * LINE 9 TO 9 + NWELL-1

C * XX X COORDINATE OF WELL (M)

C * XY Y COORDINATE OF WELL (M)

C * LINE 9 + NWELL TO END

C * TI TIME (*)

C * RC RADIUS OF CONTAMINANT (M)

C * HF HYDROCARBON FLUX (KG/D)

C * CF CONTAMINANT FLUX (KG/D)

C

C ******************************************************************
199 [Appendix 12 PRE-HSSM Data Templates]

Appendix 12 PRE-HSSM Input Data Templates

The following tables are to be used as input data templates for the MS-DOS version of HSSM. Each input

data screen in PRE-HSSM is represented by a template. These pages are intended as aids for preparing input

data sets.

Simulation Control Switches

Variable Description Value

IFACE Interface Flag D

IWR Print Flag

IKOPT KOPT Flag

ICONC Concentration Flag

ILENS OILENS Flag

ITSGP TSGPLUME Flag

Output File Names

File Description Stem Name

*.HSS HSSM-KO Formatted Output File

*.PL1 HSSM-KO Plot File 1

*.PL2 HSSM-KO Plot File 2

*.PL3 HSSM-KO Plot File 3

*.PMI HSSM-T Input Data File

*.TSG HSSM-T Formatted Output File

*.PMP HSSM-T Plot File

Run Title
[Appendix 12 PRE-HSSM Data Templates] 200

Matrix Properties

Variable Description Value

WKS Saturated Hydraulic Conductivity (m/d)

RKS Ratio of Horizontal to Vertical Conductivity

KRF Relative Permeability Selection Index

XLAMB If KRF = 1 Brooks and Corey's Lambda

If KRF = 2 van Genuchten's n 

ETA Porosity

SWR Residual Water Saturation

Hydrologic Properties

Variable Description Value

WMU Dynamic Viscosity of Water (cp)

WRHO Density of Water (g/cm )3

IRT Recharge Input type

QW/SWMAX If IRT = 1 Water Flux (m/d) 

If IRT = 2 Water Saturation

XMKRW Maximum Relative Permeability During Infiltration

WTABLE Depth to the Water Table (m)

NAPL Phase Properties

Variable Description Value

PMU NAPL Dynamic Viscosity (cp) 

PHRO NAPL Density (g/cm )3

SPR Vadose Zone NAPL Trapped Saturation (*)

IAT NAPL Application Type

1=flux specified

2=volume/area specified

3=constant head ponding 

4= variable ponding after constant head period
201 [Appendix 12 PRE-HSSM Data Templates]

Capillary Suction Approximation Parameters

Variable Description Value

HWE If KRF = 1 Brooks and Corey's Air Entry Head (m)

If KRF = 2 van Genuchten's " (1/m)

WSIG Surface Tension of Water (dyne/cm)

OSIG Surface Tension of NAPL (dyne/cm)

NAPL Flux Boundary Condition (IAT = 1)

Variable Description Value

QP NAPL flux (m/d)

TPB NAPL Event Beginning Time (d)

TPE NAPL Event Ending Time (d)

NAPL Volume/Area Boundary Condition (IAT = 2)

Variable Description Value

PVOL NAPL Volume/Area (m)

DPL Lower Depth of the NAPL Zone (m)

Constant NAPL Head or Variable Head Ponding (IAT = 3, 4)

Variable Description Value

TPB NAPL Event Beginning Time (d)

TPE NAPL Event Ending Time (d)

HS Constant Head (m)

Dissolved Constituent Concentration

Variable Description Value

COINI Initial Concentration in NAPL (mg/l)
[Appendix 12 PRE-HSSM Data Templates] 202

Equilibrium Linear Partition Coefficients

Variable Description Value

XXKO NAPL/Water

XXKS Chemical Consitutent Solid/Water (L/Kg)

XXKSH NAPL Solid/Water (L/Kg)

RHOS Bulk Density (g/cm )3

OILENS MODEL PARAMETERS: 1

Variable Description Value

RADI Radius of the Source (m)

RMF Radius Multiplication Factor (*)

FRING Lens Spreading Parameter (m)

VDISP Vertical Dispersivity of Aquifer (m)

VEL Groundwater [Darcy] Velocity (m/d)

SPRB Aquifer Trapped NAPL Saturation (*)

OILENS MODEL PARAMETERS: 2

Variable Description Value

XMSOL Maximum NAPL Saturation in Lens

SOLC Constituent Water Solubility (mg/L)

SOLH Hydrocarbon (NAPL) Water Solubility (mg/L)

Simulation Parameters

Variable Description Value

TM Simulation Ending Time (d)

DM Maximum Solution Time Step (d)

DTPR Minimum Time Between Printed Time Steps (d)

KSTOP Ending Criterion

OPERC Mass Fraction (KSTOP = 4)
203 [Appendix 12 PRE-HSSM Data Templates]

Profiles

Variable Description Value

NTIMES Number of Profile Times

Profile Times

Variable Description Value

PR(1) Profile Time (d)

PR(2) Profile Time (d)

PR(3) Profile Time (d)

PR(4) Profile Time (d)

PR(5) Profile Time (d)

PR(6) Profile Time (d)

PR(7) Profile Time (d)

PR(8) Profile Time (d)

PR(9) Profile Time (d)

PR(10) Profile Time (d)

TSGPLUME Data

Variable Description Value

DLONG Aquifer Longitudinal Dispersivity (m)

DTRANS Aquifer Transverse Dispersivity (m)

PMAX Percent Maximum Contaminant Radius

CMINW Minimum Output Concentration (mg/L)

ZLAM Aquifer Decay Rate Coefficient (1/d)

NWELL Number of Receptor Points
[Appendix 12 PRE-HSSM Data Templates] 204

TSGPLUME Simulation Times

Variable Description Value

BEGT Beginning Time (d)

ENDT Ending Time (d)

TINC Time Increment (d)

TAQU Aquifer Thickness (m)

Receptor Well Locations

Variable Description X Value Y Value

X(1), Y(1) X and Y Coordinates of Receptor 1

X(2), Y(2) X and Y Coordinates of Receptor 2

X(3), Y(3) X and Y Coordinates of Receptor 3

X(4), Y(4) X and Y Coordinates of Receptor 4

X(5), Y(5) X and Y Coordinates of Receptor 5

X(6), Y(6) X and Y Coordinates of Receptor 6
205 [Appendix 13 HSSM-WIN Data Templates]

Appendix 13 HSSM-WIN Input Data Templates

The following figures are to be used as input data templates for the MS-Windows interface (HSSM-WIN).

 Each input dialog box in HSSM-WIN is represented by a template. These pages are intended as aids in

preparing input data sets.
[Appendix 13 HSSM-WIN Data Templates] 206
207 [Appendix 13 HSSM-WIN Data Templates]
[Appendix 13 HSSM-WIN Data Templates] 208