EVALUATION OF THREE ORGANOCLAYS FOR ANADSORPTIVE BARRIER TO MANAGE DNAPL AND

DISSOLVED-PHASE POLYCYCLIC AROMATIC

HYDROCARBONS (PAHS) IN GROUND WATER

FINAL REPORT

by

Craig H. Benson, Seung-Hak Lee, and A. Hakan Ören

Geo Engineering Report No. 08-24

Geo Engineering Program University of Wisconsin-Madison

Madison, WI 53706 USA

30 September 2008

i

EXECUTIVE SUMMARY This study consisted of evaluation of an existing adsorptive barrier (AB), evaluation of three commercially available organoclays that might be used for a full-scale AB, and modeling for preliminary design of a full-scale AB intended to block the flow of DNAPL and to remove dissolved polycyclic aromatic hydrocarbons (PAHs) from ground water. Core samples from the existing AB were inspected for the presence of DNAPL and analyzed for total PAH concentrations. Batch tests were conducted on candidate organoclays using solutions prepared with a single PAH and multiple PAHs to determine adsorption isotherms and to evaluate competition for adsorption sites. Column tests were conducted to evaluate the primary mode of transport (DNAPL flow or aqueous-phase transport) and to evaluate adsorption of PAHs from the aqueous phase onto organoclay under flow-through conditions. Organoclays and sand-organoclay mixtures were evaluated in the column tests. Modeling of flow and transport was conducted using hydraulic and transport properties of the organoclays and aquifer materials to illustrate how the AB may perform in the field. The following are findings of the study: 1. The distribution of DNAPL in the existing AB was heterogeneous and inconsistent with the

expectations for an AB containing 25% organoclay. This may be due to heterogeneity of the AB material induced during installation or the presence of DNAPL within the periphery of the AB during construction.

2. Organoclays and organoclay-sand mixtures having at least 25% organoclay that are

solvated with DNAPL have conductivities less than 10-8 cm/s, whereas water-saturated organoclays have hydraulic conductivities on the order of 0.1-1 cm/s. Thus, the primary mechanism for transport of polycyclic aromatic hydrocarbons (PAHs) in organoclay ABs is advection in the aqueous phase. DNAPL migration through ABs constructed with organoclays is expected to be negligible.

3. Water migration is negligible in organoclays solvated with DNAPL. However, organoclays

solvated with DNAPL will release PAHs when contacted with water, even under quiescent conditions. PAHs released from DNAPL-solvated organoclays most likely will be adsorbed by the organoclay through which the water is flowing (see subsequent inferences in Finding 6).

4. Adsorption isotherms for PAHs and organoclays tend to be linear at low concentrations,

but non-linear when considered over a broader range. The non-linearity increases as the adsorbed concentration increases, and can be described by the Freundlich isotherm model. Greater adsorption of a given PAH occurs when the aqueous phase contains multiple PAHs.

5. Adsorption of PAHs was greatest for PM-199, followed by EC-199, and ET-1. PM-199

exhibited greater adsorption compared to EC-199 despite having slightly lower organic carbon content.

6. PAHs were detected sporadically in effluent from the column test conducted with 100%

ET-1 organoclay at 190 pore volumes of flow. However, consistent breakthrough of PAHs from this column has not occurred at 200 pore volumes of flow. No PAHs have been detected in the effluent from the other columns with organoclay or organoclay-sand mixtures at the time this report was prepared (168 pore volumes for the organoclay-sand

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mixtures, 200 pore volumes for the 100% organoclay). 7. DNAPL spreading calculations indicate that active monitoring and maintenance of DNAPL

upgradient of the AB will be necessary to ensure that the AB does not become blocked and the DNAPL will not migrate around the ends of the AB over time.

8. For a 0.6-m-thick AB, breakthrough of naphthalene will occur in 5-8 yr depending on the

target effluent concentration being considered (1.3-3.9 mg/L). For a 0.9-m-thick AB, breakthrough is anticipated in 8-12 yr depending on the target effluent concentration. If solvation of the organoclay is eliminated by actively managing DNAPL upstream of the AB, breakthrough at 3.9 mg/L will occur in 11 yr (0.6-m-thick AB) or 17 yr (0.9-m-thick AB).

Recommendations from the study are as follows: 1. Efforts should be made to ensure that the adsorptive material within the full-scale AB is as

uniform as practical. Greater uniformity can be achieved using 100% organoclay and by employing open trench or biopolymer slurry trench construction methods.

2. DNAPL spreading calculations indicate that active monitoring and maintenance of DNAPL

upgradient of the AB will be necessary to ensure that a significant portion of the AB does not become blocked and the DNAPL. Accordingly, an active monitoring and management scheme is recommended to minimize spreading of the DNAPL in the field. Managing spreading of the DNAPL will result in longer breakthrough times and greater lifespan of the AB.

3. PM-199 is recommended for the full-scale AB. PM-199 has very low conductivity to

DNAPL and the greatest affinity for PAHs of the organoclays that were evaluated. 4. The thickness of the AB may be increased in critical areas to increase the breakthrough

time.

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ACKNOWLEDGEMENT

Financial support for this study was provided by CH2M Hill, Inc. Cores from the

existing adsorptive barrier, bulk samples of DNAPL, and a bulk sample of ground water

were provided by Thomas Hutchinson of CH2M Hill. Kostas Dovantzis and Thomas

Hutchinson of CH2M Hill provided constructive feedback as the study progressed. The

findings and inferences in this report are solely those of the authors. Endorsement by

CH2M Hill is not implied and should not be assumed.

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LIST OF ACRONYMS AND SYMBOLS

DI = deionized (water)

DNAPL = dense non-aqueous phase liquid

EC-199 = organoclay manufactured by Biomin, Inc.

ET-1 = organoclay manufactured by Aqua Technologies, Inc.

foc = organic carbon fraction

Koc = organic carbon partition coefficient

Kow = octanol-water partition coefficient

PAH = polycyclic aromatic hydrocarbon

PM-199 = organoclay manufactured by CETCO

PTFE = polytetrafluoroethylene

PVF = pore volumes of flow

USCS = Unified Soil Classification System

XRD = x-ray diffraction

XRF = X-ray fluorescence

= van Genuchten’s a parameter for the capillary pressure curve

n = van Genuchten’s n parameter for the capillary pressure curve

r = residual water content in capillary pressure curve

s = saturated water content in capillary pressure curve

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TABLE OF CONTENTS

EXECUTIVE SUMMARY i

LIST OF ACRONYMS AND SYMBOLS iv

ACKNOWLEDGMENT ii

1. INTRODUCTION 1

2. MATERIALS 2 2.1 Organoclays 2 2.2 Aquifer Sands 3 2.3 Glass Beads 4 2.4 DNAPL 4 2.5 PAHs and PAH Solutions 4

3. EXPERIMENTAL METHODS 4 3.1 DNAPL Column Tests 4 3.2 DNAPL Dissolution Tests 6 3.3 DNAPL Solubility Tests 6 3.4 Dissolved PAH Batch Tests 6 3.5 Dissolved PAH Column Tests 7 3.6 Analytical Methods 8

4. EVALUATION OF EXISTING ADSORPTIVE BARRIER 8

5. RESULTS OF LABORATORY EXPERIMENTS 10 5.1 DNAPL Transport 10

5.1.1 Primary Migration Pathway 10 5.1.2 DNAPL Conductivity 12 5.1.3 Permanence of DNAPL 14

5.2 Dissolved-Phase Transport 16 5.2.1 Adsorption Behavior 17 5.2.2 Flow-Through Transport Behavior 18

6. PRACTICAL IMPLICATIONS 18 6.1 DNAPL Behavior at Upgradient Face 19 6.2 Transport of Dissolved PAH 20

7. CONCLUSIONS AND RECOMMENDATIONS 24

8. REFERENCES 26

TABLES 28

FIGURES 40

APPENDICES 75

1

1. INTRODUCTION

Historical activities associated with a former tie-treating facility at the

resulted in a dense non-aqueous phase

liquid (DNAPL) being discharged to the subsurface. This DNAPL, which is comprised

primarily of polycyclic aromatic hydrocarbons (PAHs), is migrating from the former tie-

treating facility to , and has impacted ground water.

An aerial photograph of the site showing the former tie-treating facility and

is presented in Fig. 1. A cross-section illustrating migration of the DNAPL toward

the lake is shown in Fig. 2a. To reduce the rate at which the DNAPL migrates into

, an adsorptive barrier (AB) consisting of 25% organoclay and 75% sand was

installed along the shoreline in Fall 2005 as an interim measure (Fig. 1, Fig. 2b).

Monitoring since construction has shown that the existing AB has been successful in

reducing discharges of DNAPL to . Consequently, a full-scale AB is

being evaluated for the site. The study described in this report was conducted to

support this evaluation.

The study consisted of (i) evaluation of the existing AB, (ii) evaluation of three

commercially available organoclays that might be used for the full-scale AB, and (iii)

preliminary modeling to assess the effectiveness of a full-scale application of the AB.

Evaluation of the existing AB included visual examination of cores collected from within

the AB and chemical analysis on sections of the cores to determine the total PAH

concentrations associated with the AB solid. Evaluation of the commercially available

organoclays included batch and column tests to evaluate transport characteristics of the

organoclay as well as physical tests to characterize the geotechnical and hydrological

properties of the organoclays. The preliminary modeling consisted of two-dimensional flow

and transport simulations to evaluate ground water velocities within the AB and

breakthrough curves for various locations on the effluent face along the length of the AB.

2

This report is divided into 8 sections. Section 2 describes the materials used in the

study. Experimental methods that were employed are described in Section 3. Section 4

describes the existing AB. Transport properties of the three organoclays are described in

Section 5 and the practical implications of preliminary modeling results are described in Section

6. Conclusions and recommendations are presented in Section 7. References are provided

in Section 8.

2. MATERIALS

2.1 Organoclays

Three organoclays were used in this study: ET-1 (Aqua Technologies of Wyoming, Inc.,

Casper, WY, USA), PM-199 (CETCO, Arlington Heights, IL, USA), and EC-199 (Biomin, Inc.,

Ferndale, MI, USA). Particle size distribution curves (ASTM D 422) for the organoclays are

shown in Fig. 3a. Mineralogical composition of the organoclays (determined by X-ray

diffraction) is summarized in Table 1. The organic carbon content (foc) and specific gravity of

solids (ASTM D 854) are summarized in Table 2. Organic carbon content was measured by

combustion at 925 °C using a LECO CNS carbon analyzer following the procedure in WSPL

(2005).

All three of the organoclays consist of sand-size granules and classify as poorly graded

sands (SP) in the Unified Soil Classification System (USCS). PM-199 contains more uniform

and smaller granules than ET-1 and EC-199. Each of the organoclays consists primarily of

montmorillonite, but also contains appreciable amounts of quartz, cristobalite (ET-1), and

feldspar (PM-199) (Table 1). EC-199 has the highest montmorillonite content (83%), whereas

PM-199 (62%) and ET-1 (64%) contain less (and comparable) amounts of montmorillonite.

The organic carbon content of the organoclays ranges from 15.5% (ET-1) to 26.9% (EC-199).

All three organoclays have lower specific gravity of solids (1.75-2.00) than is typical of

montmorillonite (2.65, Jo et al. 2004), which reflects the organic carbon amended to the mineral

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solid (Table 2).

Hydraulic conductivity to water for each organoclay was determined using ASTM D

2434. The hydraulic conductivities are high (0.12-0.39 cm/s) compared to those characteristic

of natural montmorillonites, which typically have hydraulic conductivities to water on the order of

10-10 to 10-8 cm/s (Mesri and Olson 1971). The organoclays have high hydraulic conductivity

because they do not hydrate in water. As a result, the hydraulic conductivity is characteristic of

the size and distribution of the sand-size granules in the organoclay rather than clay-size

particles typically associated with a natural clay. For example, EC-199 has the largest median

granule size, the least amount of fine granules, and is the most permeable of the organoclays.

Capillary pressure curves for each organoclay corresponding to an air (non-wetting fluid)

and water (wetting fluid) system were measured using the hanging column procedure described

in ASTM D 6836. These curves ultimately were not used in the analysis because the

properties of the organoclay changed markedly when solvated with DNAPL, precluding a

conventional multiphase flow and transport analysis (see Section 6). The capillary pressure

curves are provided in Appendix A.

2.2 Aquifer Sands

Aquifer sands used in the study were obtained from cores collected from the field site

(see discussion in Section 4). Analysis was conducted on samples obtained from portions of

cores T2-B2, T2-B3, and T2-B4 that were beneath the existing AB (Fig. 2b). Particle size

distribution, specific gravity of solids, and hydraulic conductivity of the sands were determined

using the same methods employed for the organoclays.

All three sand samples had a specific gravity of 2.65. The hydraulic conductivities

ranged between 0.059 (T2-B3) and 0.168 cm/s (T2-B2). Particle size distribution curves for the

sands are shown in Fig. 3b. These distributions are essentially identical, with sand fractions

ranging from 60% to 70% and gravel fractions from 28% to 38%.

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2.3 Glass Beads

Beads composed of soda-lime glass that are virtually chemically inert were used as

control materials. The glass beads had a specific gravity of 2.50, uniform gradation with

particle sizes between 0.4 and 0.8 mm, and roundness between 0.65 and 0.90 (as defined by

ASTM D 1155).

2.4 DNAPL

DNAPL samples from the field site were shipped to the University of Wisconsin-

Madison in sealed metal cans and then transferred into a 20-L carboy. The DNAPL density is

1.08 kg/L and the dynamic viscosity is 0.85 Pa-s at room temperature (21°C). PAH

concentrations in the DNAPL, determined using USEPA Method 8270C, are presented in Table

3. Naphthalene is the dominant PAH present in highest concentration in the DNAPL. However,

phenanthrene, fluoranthene, 2-methylnaphthalene, acenaphthene, fluorene, and pyrene are

also abundant.

2.5 PAHs and PAH Solutions

Naphthalene (99% purity), acenaphthene (99% purity), fluoranthene (99% purity), and

phenanthrene (98% purity) obtained from Aldrich Chemical, Inc. (Milwaukee, WI, USA) were

used to make aqueous PAH solutions for the batch and column tests. PAH solutions were

prepared by dissolving naphthalene, acenaphthene, fluoranthene, and/or phenanthrene in DI

water.

3. EXPERIMENTAL METHODS

3.1 DNAPL Column Tests

Column tests were conducted in cylindrical stainless-steel columns that had a diameter

5

of 60 mm and a height of 52 or 153 mm. The tests employed the same design as those in

Cope and Benson (2008). The longer columns were used for tests conducted with organoclay-

sand mixtures, whereas the shorter columns were used for tests conducted solely with

organoclay. Stainless steel plates containing a PTFE O-ring were placed on either end of the

column. PTFE tubing (4.8 mm inside diameter) was used for the influent and effluent lines,

except at the pump head, where flexible Viton® peristaltic tubing (0.89 mm ID) was used. A

glass microfiber filter was used to distribute flow uniformly along both ends of the specimen.

Organoclays or organoclay-sand mixtures were placed into the columns in three layers, with

each layer tamped lightly with a rubber rod to simulate the modest densification that would

occur in the field if the material was dumped or poured into a trench.

Short-term preliminary column tests were initially conducted to identify the primary

mechanism for PAH transport through the organoclays (i.e., DNAPL flow or dissolved phase

transport). Duplicate tests were prepared using PM-199 and ET-1. Deionized (DI) water was

initially pumped through the organoclays using a peristaltic pump (Minipuls 2, Gilson, France).

After the flow rate was steady, the influent liquid was switched to DNAPL from the site. The tests

were conducted in an upflow mode at a constant flow rate (8 mL/hr). Pressure gages were

used to monitor the influent pressure, and the effluent was collected in a graduated cylinder at

atmospheric pressure.

Additional longer-term DNAPL column tests were conducted to characterize the

conductivity of the organoclays to the DNAPL. These tests were conducted in similar columns

as the preliminary tests. However, due to the very low conductivity of the organoclays to

DNAPL, the longer-term tests employed a constant head apparatus rather than a peristaltic

pump (Fig. 4). A hydraulic gradient of 5 was used for the longer columns, and 15 was used for

the shorter columns. As with the preliminary tests, organoclays in the longer-term DNAPL

column tests were saturated with DI water prior to introducing the DNAPL.

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3.2 DNAPL Dissolution Tests

Dissolution tests were conducted on DNAPL-solvated organoclays from the longer-term

column tests after the flow-through tests were terminated. The purpose of these dissolution

tests was to evaluate whether the PAHs solvating the organoclay would be released into ground

water contacting the AB. Samples of organoclay (27 g) were placed in a beaker filled with 200

mL of DI water. The beaker was sealed and stored in a quiescent state similar to that existing

in situ (no shaking or movement was permitted). Samples of the aqueous phase were

collected periodically with a syringe, mixed with 0.5 mL of HPLC-grade acetonitrile (Fisher

Scientific, Chicago, IL, USA) to enhance desorption from the HPLC column, and analyzed for

PAH concentrations using USEPA Method 8310.

3.3 DNAPL Solubility Tests

DNAPL solubility tests were conducted to evaluate maximum concentrations of DNAPL

that might be observed at the influent face of an AB. DNAPL-water mixtures (1:1 and 1:7) were

prepared using DI water in 40-mL glass vials without head space and sealed with PTFE-lined

screw caps. The vials were placed in a tumbler at 28 rpm. After 24 or 48 hr the vials were

removed from the tumbler and set on the bench for 1 hr to separate the aqueous and DNAPL

phases. A 0.5-mL aqueous sample was then collected and analyzed for PAHs using USEPA

Method 8310. PAH concentrations from the solubility tests are summarized in Table 4.

3.4 Dissolved PAH Batch Tests

Adsorption of PAHs to the three organoclays under equilibrium conditions was

evaluated with batch tests conducted with a single PAH (naphthalene, acenaphthene,

phenanthrene, or fluoranthene) and with a mixture of PAHs. The latter tests were conducted to

evaluate potential competition for sorption sites. Organoclay (0.01-0.3 g) was placed in a 40-

mL amber glass vial that was subsequently filled with an aqueous PAH solution. The vials

7

were sealed with screw caps containing PTFE-lined septa, and placed in a tumbler for 48 hr at

28 rpm. After 48 hr, a sample of the supernatant was collected with a syringe, mixed with 0.5

mL of HPLC-grade acetonitrile, and analyzed for PAHs using USEPA Method 8310. Control

tests conducted without sorbent indicated that losses were less than 0.1% of the initial

concentration. Thus, no correction for losses was made.

Kinetic sorption tests were conducted initially to determine the time required to reach

equilibrium. These tests were conducted using similar methods as the equilibrium tests,

except multiple replicate vials were prepared and dissolved-phase concentrations typical of field

conditions were used for the initial condition. Vials were removed from the tumbler periodically

and analyzed for naphthalene, acenaphthene, phenanthrene, and fluoranthene using USEPA

Method 8310. Concentrations from these tests are shown in Fig. 5 as a function of time.

Equilibrium is established in approximately 10 hr. Thus, the 48-hr reaction time used in the

equilibrium tests was sufficient to achieve equilibrium. Naphthalene was adsorbed at greater

solid-phase concentrations than the other PAHs used in the kinetic batch tests because the

initial dissolved-phase concentration of naphthalene was higher than the concentrations for the

other PAHs.

3.5. Dissolved PAH Column Tests

Column tests were conducted with organoclays, organoclay-sand mixtures, and glass

beads (control) to evaluate transport of dissolved PAHs under flow-through conditions (Fig. 6).

These tests were conducted with a peristaltic pump in essentially the same manner as the

preliminary DNAPL column tests. Influent solution (DI water followed by a PAH solution) was

introduced into the column in an upflow mode at a constant rate (6 mL/hr). The influent

solution was contained in a flexible 3-L PTFE bag and effluent solutions were collected in

sealed flasks. Samples of the column influent and effluent were collected periodically, mixed

with 0.5 mL of acetonitrile, and analyzed for PAH concentrations using USEPA Method 8310.

8

3.6 Analytical Methods

HPLC analysis for PAH concentrations was conducted with a SPD-M10Avp detector,

LC-10ATvp pump, and CTO-10Avp oven (Shimadzu, Kyoto, Japan). The HPLC was equipped

with a PinnacleTM II PAH 4 μm column (150 x 3.2 mm, Restek, Bellefonte, PA, USA) and a

PinnacleTM II PAH guard cartridge (10 x 2.1 mm, Restek, Bellefonte, PA, USA). A mixture of

acetonitrile and HPLC water was used as the mobile phase at a flow rate of 1.2 mL/min. The

oven temperature was set at 40 °C and the run time was 25 min, during which naphthalene was

detected at 6.57 min, acenaphthene at 9.10 min, phenanthrene at 10.28 min, and fluoranthene

at 11.72 min. The method detection limit (MDL) was estimated to be 4.9 μg/L for naphthalene,

2.4 μg/L for acenaphthene, 0.3 μg/L for phenanthrene, and 1.6 μg/L for fluoranthene.

4. EVALUATION OF EXISTING ADSORPTIVE BARRIER

Eleven core samples were collected from the AB and adjacent aquifer by .

Locations where the cores were collected are shown in Fig. 7. Eight cores were collected from

the AB and three cores were collected from the aquifer on the upgradient side of the AB. All

cores were collected with a direct push technique to a depth of approximately 9 m. The cores

were delivered to UW in clear acrylic tubes 45 or 55-mm in diameter and approximately 1 m

long. Each core was extruded from the acrylic tube by hand and examined visually for the

presence of DNAPL. Contrast between the dark color of the DNAPL and the light color of the

sand or AB was used to identify zones where DNAPL was present. Presence of DNAPL in

each core was classified as high, medium, or low based on the amount of DNAPL that was

visually observed.

The distribution of DNAPL in the existing AB based on the visual inspection is shown in

Fig. 8. The greatest presence of DNAPL was anticipated near the upgradient face of the AB,

and was expected to diminish rapidly with increasing distance from the entrance face as DNAPL

9

was adsorbed by the organoclay. Greater presence of DNAPL was observed in cores obtained

closer to the entrance face (B2 series cores in Fig. 8). However, the DNAPL did not

consistently diminish with distance from the entrance face. For example, complete penetration

of DNAPL occurred along transect T2, and the vertical distribution of DNAPL in core B2 from

transect T2 was inconsistent with the vertical distribution of DNAPL in the aquifer at the

entrance face (core B1 in transect T2). Similarly, greater DNAPL presence was observed in

core B4 (near the exit face) than in core B3 (mid point in the AB) in transect T3. DNAPL was

also observed in the aquifer material beneath the AB, which is consistent with the presence of a

lower zone of DNAPL upgradient of the AB (Fig. 2b).

Nine samples of core from the AB corresponding to locations with high, medium, and

low presence of DNAPL were analyzed for total PAH concentrations using USEPA Method 8310.

One sample of core from the aquifer sand having high DNAPL presence (T1-B3, 5.5-5.7 m bgs)

was also analyzed. Total concentrations of PAHs in the core samples are summarized in Table

5. On average, good agreement exists between the PAH concentrations and visually observed

presence of DNAPL (i.e., higher PAH concentration is present in samples with greater visual

presence of DNAPL). For example, the average naphthalene concentration is 2970 mg/kg in

the samples with high presence, 1960 mg/kg in the samples with moderate presence, and 530

mg/kg in the samples with low presence. However, on an individual core basis, the PAHs

concentrations are not always consistent with the amount of DNAPL that was visually present.

For example, the naphthalene concentration in T3-B2 (3.0~3.3 m bgs) with low DNAPL

presence is 1400 mg/kg, whereas the naphthalene concentration in T3-B2 (2.6~2.9 m) is 530

mg/kg, even though this section of T3-B2 appeared to contain a greater amount of DNAPL

(moderate DNAPL presence). The reason for these periodic inconsistencies cannot be

determined with certainty. However, they probably reflect differences in the rate of transport of

PAHs in the DNAPL and aqueous phases. That is, elevated naphthalene concentrations could

be present even if DNAPL was not visibly evident, if advection in the aqueous phase was the

10

primary mechanism controlling naphthalene transport through the existing AB.

A uniform AB containing 25% organoclay should have had very low conductivity to

DNAPL (see subsequent discussion in Section 5), which would have forced most of the DNAPL

to be located near the entrance face of the AB and would have resulted in a relatively sharp

DNAPL front in the AB. The irregular pattern of DNAPL in the AB and the broad distribution of

PAH concentrations suggests that the organoclay content in the AB was heterogeneous or that

the DNAPL was present within the periphery of the AB during installation of the organoclay.

Attempts were made to determine the distribution of organoclay content by conducting

analyses on core samples using X-ray fluorescence (XRF). Ratios of Al-to-Si were computed

from the XRF data in an attempt to identify regions with high organoclay content (high Al/Si ratio)

and low organoclay content (low Al/Si ratio). These attempts, however, were unsuccessful as

no consistency was present in the Al/Si ratios. Regardless, the evaluation of the existing AB

suggests that effectiveness of the full-scale AB will depend significantly on the degree of

homogeneity that can be achieved.

5. RESULTS OF LABORATORY EXPERIMENTS

5.1 DNAPL Transport

5.1.1 Primary Migration Pathway. The preliminary column tests with DNAPL (Section 3)

were conducted with 100% organoclay to evaluate whether the primary pathway for migration of

PAHs would be in the DNAPL or aqueous phases. These tests were conducted with PM-199

and ET-1 and employed a peristaltic pump to provide a constant flow rate.

Pressure rapidly increased at the influent end during these column tests. The influent

pressure for the column with PM-199 increased to 324 kPa within 6 hr, which burst the tubing at

the pump head and forced cessation of the test. For ET-1, DNAPL was observed at the

effluent end of the column in approximately 21 hr, which corresponded to 0.9 pore volumes of

flow (PVF). Flow from the effluent end diminished, and the pressure at the influent port

11

increased to 63 kPa, at which time the test with ET-1 was ceased to prevent bursting of the

tubing at the pump head.

After terminating the preliminary column tests, the organoclay was extruded and

inspected. For PM-199, the DNAPL migrated less than 10 mm distance from the influent port.

Most of the organoclay appeared unchanged by permeation, having retained the original

granular texture and color (Figs. 9a and b). However, at the very bottom of the column (influent

end), a thin layer (1 mm thick) was present where the organoclay had been transformed from its

original coarse-grained texture to a dark plastic gel-like material (Fig. 9c) that had similar

consistency as Na-montmorillonite hydrated with water. Above this gel-like layer, another layer

approximately 9-mm thick was present that transitioned in color from brown to yellow.

Constituents in the DNAPL apparently sorbed onto the organoclay surfaces in this layer (Fig. 9c),

although adsorbed PAH concentrations in this layer were not measured. Distinct granules of

organoclay were present in this 9-mm-thick zone.

The specimen of ET-1 removed from the column had different appearance (Fig. 10).

The entire column appeared saturated with DNAPL. The core was stained dark brown (Fig. 10b),

including the influent and effluent faces (Fig. 10a). In contrast to PM-199, granules of ET-1

remained visible after penetration by DNAPL (Fig. 10c).

The very low flow rate observed in these preliminary column tests, even with high

pressure at the influent end, suggests that DNAPL transport in the organoclay will be minimal.

Moreover, the hydraulic conductivity of water saturated organoclay is very high (Table 2). Thus,

the primary pathway for PAH transport should be advection of PAHs dissolved in the aqueous

phase (ground water). This is particularly true under natural conditions, where the hydraulic

gradient driving flow would be orders of magnitude lower than hydraulic gradient applied in the

laboratory, resulting in a very low rate of migration of DNAPL in the organoclay.

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5.1.2 DNAPL Conductivity. Longer-term column tests (Section 3) were conducted with

DNAPL as the permeant liquid to confirm that the very low DNAPL conductivity observed in the

preliminary tests would persist when the organoclays were permeated over longer periods of

time. Tests were conducted with 100% PM-199, ET-199, and ET-1 as well as with mixtures of

sand and PM-199 having organoclay contents of 10, 25, and 50%. A test was also conducted

with sand alone. As mentioned in Section 3, these tests were conducted using a constant

head applied using a burette filled with DNAPL to more accurately represent a field condition.

Test conditions for these experiments are summarized in Table 6. DNAPL hydraulic

conductivities corresponding to near equilibrium conditions are summarized in Table 7.

Graphs showing DNAPL conductivity vs. time for the tests conducted with 100%

organoclay are shown in Fig. 11. Similar behavior was obtained for each organoclay. The

DNAPL conductivity diminishes over time, with a rapid decrease occurring initially that is

followed by a gradual decrease that trends towards an equilibrium condition. In all cases, the

hydraulic conductivity was decreasing slightly when permeation with DNAPL ceased. Thus, a

true equilibrium condition (i.e., conductivity steady over time) was not achieved in any of the

column tests, and the DNAPL conductivities reported in Table 7 are a conservative upper bound

on the long-term equilibrium DNAPL conductivity. The DNAPL conductivities are correlated to

the organic carbon content of the organoclays (Fig. 12), which reflects the ability of the DNAPL

to solvate the mineral surface. Very low DNAPL conductivities were obtained for EC-199

(3.7x10-10 cm/s, 26.9% organic carbon) and PM-199 (7.6x10-10 cm/s, 25.0% organic carbon).

The DNAPL conductivity for ET-1 (3.4x10-9 cm/s, 15.5% organic carbon) was approximately one

order of magnitude higher than those of PM-199 and EC-199 (Table 7).

Graphs of DNAPL conductivity vs. time for the sand and organoclay-sand mixtures are

shown in Fig. 13. The temporal trends for the sand and organoclay-sand mixtures are similar

to those obtained from the tests conducted with 100% organoclay, with a rapid decrease in

hydraulic conductivity followed by a more gradual decrease (organoclay-sand mixtures) or

13

constant hydraulic conductivity (sand). The initial rapid decrease was observed in all of the

longer-term column tests, including the sand. Because the sand is essentially inert compared

to the organoclays, the initial drop in conductivity most likely reflects hydraulic stabilization to the

imposed influent boundary condition rather than solvation mechanisms. However, the

subsequent gradual decrease in DNAPL conductivity observed in all tests conducted with

organoclay most likely is related to solvation of the organoclay.

DNAPL conductivity vs. organoclay content is shown in Fig. 14. Addition of organoclay

to the sand causes a remarkable reduction in the DNAPL conductivity in a manner analogous to

the effect that addition of Na-montmorillonite has on the hydraulic conductivity of sand (e.g.,

Abichou et al. 2002). The most rapid reduction in DNAPL conductivity is obtained as the

organoclay content is increased from 0 to 25%, and DNAPL conductivities less than 10-8 cm/s

are obtained for organoclay contents greater than or equal to 25%. That is, from a practical

perspective, DNAPL flow is essentially arrested when the organoclay content is at least 25%.

In fact, when the organoclay content was at least 50%, no DNAPL emanated from the effluent

end of any of the column tests during the testing period (only pore water was expelled, and only

within the first 10 d).

The organoclays and organoclay-sand mixtures were inspected after the column tests

were terminated. Photographs of specimens from column tests on 100% organoclay are

shown in Fig. 15 (PM-199), Fig. 16 (EC-199), and Fig. 17 (ET-1). Penetration of DNAPL was

evident in all of the columns, and DNAPL was present as spots or as a layer at the effluent end

of the columns prepared with PM-199 (Fig. 15a) and EC-199 (Fig. 16a). No DNAPL was

present at the effluent end of the column conducted with ET-1, but this column was terminated

29 d earlier than the other columns.

Distinct granules of organoclay remained in all of the column tests conducted with 100%

organoclay (Fig. 15d for PM-199, Fig. 16c for EC-199, Fig. 17b for ET-1). Particles in the

columns of PM-199 and EC-199 generally were surrounded by DNAPL (black liquid in Figs. 15

14

and 16) and had a plastic consistency that could be smeared (Figs. 15c and 16b). In contrast,

ET-1 retained a granular and non-plastic friable structure after permeation (Fig. 17b). The

difference in texture suggests that the DNAPL solvates the surface of the PM-199 and EC-199

organoclays to form a plastic material, but interacts with the ET-1 organoclay in another manner.

This difference in behavior may be due to differences in the compounds used to organically

modify the clays. Photographs of the granules of PM-199 (Fig. 15d) and EC-1 (Fig. 16c) also

suggest that the organoclay granules are not fully solvated by the DNAPL. Most of the

solvation appears to occur on the exterior surfaces of the granules, whereas the interior of the

granules appears to be unsolvated. A very low conductivity rim may be forming around the

exterior of the organoclay granules, which restricts the rate at which DNAPL can migrate into the

interior of the granule along micropores and solvate interior surfaces. Consequently,

organoclays having smaller granule size may be more readily solvated and be less permeable

to DNAPL than those tested in this study. However, a detailed examination of the micropores

and solvation processes within the granules was beyond the scope of this study.

For the organoclay-sand mixtures with at least 25% organoclay, a distinct zone of

DNAPL penetration approximately 50-mm thick (Fig. 18b) was observed that was very similar to

the penetration observed in the columns with 100% organoclay. However, in contrast to the

columns with 100% organoclay, complete solvation of the organoclay granules (including the

interior surfaces) apparently occurred in the organoclay-sand mixtures. A dark gel-like

structure was evident in the pore space that was devoid of remnant granules (Fig. 18d). The

mixture also was plastic and could be smeared (Fig. 18c).

5.1.3 Permanence of DNAPL. Two sets of tests were conducted to evaluate whether the

DNAPL contained in the organoclay would be retained in the presence of water (e.g., when the

DNAPL source was no longer present and only ground water was contacting the AB). One set of

consisted of permeating the DNAPL solvated columns of 100% PM-199 and EC-199 with tap

15

water after the DNAPL permeation phase was complete. The other tests consisted of

quiescent dissolution experiments conducted with DNAPL-solvated organoclays. The

dissolution tests were conducted with 100% PM-199 and EC-199, and the 50% PM-199-sand

mixture.

Hydraulic conductivities obtained from the water permeation tests are shown in Fig. 11

and are summarized in Table 7. Water permeation was conducted for 29 d after 46 d of

DNAPL permeation. Very low hydraulic conductivities to water were obtained for both clays

throughout the duration of the test (9.6x10-10 cm/s for PM-199, 1.1x10-9 cm/s for EC-199).

These hydraulic conductivities are slightly higher than the DNAPL conductivities because of the

difference in viscosity and density of water relative to the DNAPL. Nevertheless, the hydraulic

conductivities are very low, which indicates that water will not migrate through the DNAPL-

solvated organoclay in appreciable amounts. Moreover, no DNAPL or water was discharged in

the effluent from the columns during the 29-d permeation period. Thus, the DNAPL should be

retained within the organoclay even after the source is removed and ground water is contacting

the AB.

Aqueous-phase concentrations of naphthalene, acenaphthene, and phenanthrene

recorded during the dissolution tests are shown in Fig. 19 along with the maximum

concentrations of each compound observed at the field site. The concentration increases

rapidly, and then levels off near the maximum concentration observed in the field after

approximately 100 hr. When compared with the 100% organoclay columns, higher

concentrations were obtained from the tests conducted with the 50% organoclay-sand mixture,

which may reflect less avid binding of the PAHs when less organoclay is present. Slightly higher

concentrations were also obtained for the tests conducted with PM-199 compared to the tests

with EC-199, which reflects the lower organic carbon content of PM-199 relative to EC-199.

The findings from the dissolution tests indicate that DNAPL-solvated organoclays in an

AB can serve as a long-term source for dissolution of PAHs in contacting ground water.

16

However, PAHs released from the organoclay most likely will be adsorbed by unsolvated

organoclays in other portions of the AB where ground water is flowing.

5.2 Dissolved-Phase Transport

Batch and column tests were conducted to assess adsorption of PAHs dissolved in the

aqueous phase to organoclays, and to evaluate transport under flow-through conditions as

would occur in the field. Naphthalene (logKow=3.30), acenaphthene (logKow=3.92),

phenanthrene (logKow=4.46), and fluoranthene (log Kow=5.16) were selected for testing because

these compounds have relatively high concentrations in the field relative to the

generic clean-up criteria (Fig. 20), their octanol-water partition coefficients (Kow) span a

relatively broad range for PAHs, and analysis for these compounds was available and reliable.

Concentrations of these compounds and other PAHs present in ground water at the field site are

summarized in Fig. 20 along with the relevant clean up criteria in , Part 201.

Target concentrations for batch and column testing were selected so that they would

represent concentrations near the upper bound observed in the field. The following target

concentrations were selected: naphthalene – 10 mg/L (batch) and 20 mg/L (column),

acenaphthene – 1 mg/L (batch) and 3.5 mg/L (column), fluoranthene – 1 mg/L (batch), and

phenanthrene – 1 mg/L (batch and column). Slightly higher target concentrations were used in

the column tests to offset losses ( 26% for naphthalene, 29% for acenaphthene, and 60% for

phenanthrene) in the column system. Only a limited number of tests were conducted with

fluoranthene because its extremely avid adsorption to organoclay rendered concentrations in

the batch equilibrium tests near the detection limit. Consequently, data for fluoranthene are not

presented in this section.

17

5.2.1 Adsorption Behavior. Adsorption isotherms for PM-199 for a single PAH and multiple

PAHs are shown in Fig. 21. Tests with a single PAH were only conducted with PM-199. Each

isotherm was fit with the Freundlich isotherm model, which can be described as

qe = KF Cen

where qe is the concentration adsorbed on the solid (mg/kg), Ce is the equilibrium concentration

in the aqueous phase (mg/L), KF is the Freundlich distribution coefficient (L/kg), and n is the

sorption exponent. A summary of the Freundlich parameters is in Table 8. A linear isotherm

(n = 1) was also fit to the data corresponding to lower concentrations where the isotherm was

approximately linear. Partition coefficients for the linear isotherm (Kd) are in Table 9.

As shown in Fig. 21, greater adsorption occurs in the presence of multiple compounds

than with a single compound in all cases, making competition for sorption sites between

compounds moot. In addition, for multiple compounds, the Freundlich n parameter is always

greater than 1, indicating that propensity for adsorption increases as the amount of PAH

adsorbed increases. These findings for multiple compounds are particularly important, as a

mixture of PAHs exists in the field.

Greater adsorption was also obtained with the more hydrophobic compounds (higher

Kow). For example, the highest KF was obtained with phenanthrene (logKow = 4.46) and the

lowest with naphthalene (logKow = 3.30) (Table 8). The effect of hydrophobicity is illustrated in

Fig. 22, which the shows a strong positive relationship between logKoc and logKow. The Koc in

Fig. 22 were computed as Kd ÷ foc using data from the tests conducted with PM-199 using a

single PAH.

A comparison of isotherms for all three organoclays is shown in Fig. 23 for tests

conducted with multiple PAHs. PM-199 consistently has the highest adsorption, and ET-1 the

lowest. For example, the Freundlich distribution coefficient for naphthalene (3888 L/kg) is 2

times higher than the Freundlich distribution coefficient for EC-199, and 10 times higher than for

18

ET-1. PM-199 and EC-199 were expected to have greater adsorption than ET-1 because of

the lower organic carbon content of ET-1. However, greater adsorption with PM-199 relative to

EC-199 was not anticipated given that EC-199 has slightly higher organic carbon content (Table

2). This difference is likely due to greater specific surface area for PM-199, which is comprised

of smaller granules than EC-199 (Fig. 2). The higher surface area of PM-199 probably offsets

the modest difference in organic carbon content that exists between PM-199 and EC-199.

5.2.2 Flow-Through Transport Behavior. Column tests are being conducted with each of the

organoclays and with organoclay-sand mixtures having 25% and 50% PM-199. A non-reactive

control test with glass beads is also being conducted. Effluent concentrations from the

columns are shown in Fig. 24 (100% organoclay) and Fig. 25 (organoclay-sand mixtures). At

the time this report was prepared, more than 200 PVF had passed through the columns with

100% organoclay and more than 168 PVF had passed through the columns with the

organoclay-sand mixtures.

PAH concentrations in the effluent have remained below detection limits in all but one of

the columns. The exception is the column containing 100% ET-1 organoclay (Fig. 24), for

which PAHs have been detected sporadically since 190 PVF (complete breakthrough has not

occurred in the ET-1 column). These findings are consistent with the isotherm parameters for

the batch tests conducted with multiple PAHs. Based on the partition coefficients obtained

from the batch tests, complete naphthalene breakthrough (effluent influent concentration) is

not anticipated until approximately 360 PVF for ET-1, 1880 PVF for EC-199, and 3890 PVF for

PM-199. For the organoclay-sand mixtures, complete naphthalene breakthrough is not

anticipated for 970 PVF (25% PM-199) or 1940 PVF (50% PM-199).

6. PRACTICAL IMPLICATIONS

Modeling was conducted using the adsorption parameters in Section 5 to assess the

19

expected performance of a full-scale AB. The AB was located along the shoreline from SB 03-

07 to SB 10-07 as shown in Fig. 26, and to be keyed into the underlying clay layer (Fig. 2). The

AB was assumed to be filled with 100% PM-199 organoclay. PM-199 was selected because it

exhibited the greatest affinity for PAHs, and had very low hydraulic conductivity to DNAPL.

Thus, PM-199 will block the flow of DNAPL and be the most effective in removing dissolved

PAHs from ground water passing through the AB. Similar results would be obtained for Abs

containing well-blended mixtures of sand and organoclay, except that breakthrough would occur

earlier in an AB containing a mixture ( breakthrough time for 100% organoclay x percentage of

organoclay in sand-organoclay mixture).

6.1 DNAPL Behavior at Upgradient Face

Column testing showed that DNAPL flows into organoclay at a very slow rate. Thus,

the full-scale AB is expected to act as a barrier to DNAPL flow, which will cause spreading of

DNAPL along the upgradient face. Simulations of this behavior were attempted with the

multiphase flow and transport simulator MOFAT (RSI 1991). However, these attempts were not

successful because solvation of the organoclay with DNAPL alters the hydraulic properties of

the organoclay in a manner that is fundamentally different than the assumptions employed in

conventional multiphase flow theory. Thus, spreading along the upgradient face was estimated

using an analytical mass-balance method, where the volume of DNAPL spreading within the AB

was equated to the volume of DNAPL flowing to the AB in the aquifer. The two primary DNAPL

layers were considered in the analysis (elevations 575 and 565 ft in Fig. 27). For each layer,

the DNAPL contacting the surface of the AB was assumed to be an ellipse, the DNAPL mobility

was assumed to be 1.4 m/yr (upper bound of the range in the field; ), and the

DNAPL was assumed to spread isotropically within the AB. DNAPL penetration into the AB

was assumed to occur for one year, resulting in 0.3 m of penetration at the rate observed in the

20

laboratory ( 25 mm/month).

The calculated spreading at the upgradient face is illustrated in Fig. 28. The spreading

calculation shows that the DNAPL-solvated zone at the upgradient face (heavy black line)

widens over time, and that a significant fraction of the AB (open rectangle) will be blocked

eventually if DNAPL is allowed to accumulate. Moreover, DNAPL may flow around the

northern end of the AB after 5 yr if spreading is unabated. However, these computations are

conservative, because all of the DNAPL flowing towards the AB is assumed to enter the AB and

then spread laterally. In the field, the DNAPL zone upgradient of the AB may widen as the AB

blocks flow, which will reduce spreading along the upgradient face and reduce the area of the

AB that becomes essentially impervious to water flow. Nevertheless, the potential exists for

spreading to occur relatively rapidly, which would block flow through the AB and significantly

alter the hydrology and transport pathways.

6.2 Transport of Dissolved PAHs

Flow and transport of dissolved PAHs through the AB was simulated with the variably

saturated flow and transport program HYDRUS (v1.02; im nek et al. 2007). HYDRUS solves

the variably saturated water flow equation and advection-dispersion-reaction equation for

dissolved contaminants using the finite-element method. HYDRUS was selected because it

accommodates both non-linear and linear isotherm models, and permits flow and transport

problems to be solved in multiple dimensions using a single software package having a

graphical user interface. For this analysis, saturated conditions were assumed for all simulations,

which is consistent with the field scenario.

Simulations were conducted for the two-dimensional domain shown in Fig. 29. The AB

is surrounded by 10 m of aquifer material in all directions, and a portion of the upgradient face is

blocked by DNAPL-solvated organoclay (the breadth of this blockage depends on the amount of

21

DNAPL spreading that is permitted, as described subsequently). Constant head conditions

were applied at the left and right side boundaries to induce the average hydraulic gradient (i)

observed in the field (i=0.01, ). No flow boundaries were applied on the north

and south surfaces of the domain, which were located sufficiently far from the AB to prevent

alterations in flow patterns within the AB. Hydraulic parameters used as input are summarized in

Table 10.

Parameters for naphthalene were used for the transport modeling. Of the PAHs

considered, adsorption of naphthalene was the least favorable. Thus, naphthalene is

anticipated to breakthrough the earliest. The dry density of the AB was assumed to be 0.84

Mg/m3 and the porosity was assumed to be 0.47, which correspond to conditions in the column

test conducted with PM-199. Multicomponent isotherms obtained from the batch tests with

multiple PAHs were used to simulate the field condition. Diffusion was ignored due to the high

ground water velocities. The longitudinal dispersivity was assumed to be one-tenth of the

barrier thickness, and the transverse dispersivity was assumed to be one-tenth of the

longitudinal dispersivity (Fetter 1999). Concentration at the upgradient face was assumed to

be uniform and invariant with time. Three different concentrations were used at the upgradient

face:

12 mg/L, which is slightly higher than the maximum concentration obtained from the dissolution test on DNAPL-solvated PM-199; this concentration is intended to represent conditions where water is contacting the DNAPL-solvated organoclay near the edges of the DNAPL-solvated zone,

7 mg/L, which is a typical naphthalene concentration existing in the field (

2007), and 0.1 mg/L, which represents the low concentrations observed in the vicinity of the

southern portion of the AB.

Ground water velocities predicted in the middle of the AB are shown in Fig. 30

as a function of distance from the north end of the AB for three cases of flow blockage

due to DNAPL solvation of the organoclay: (a) immediately after construction (i.e., DNAPL

22

directly upstream of the AB inducing immediate solvation of the organoclay), (b) after 1 yr

of DNAPL spreading, and (c) after 2 yr of DNAPL spreading. Velocities are higher at the

edges of the DNAPL-solvated zone (marked ‘NAPL’ in Fig. 30) due to the focusing of

flow that occurs as ground water migrates around the DNAPL-solvated organoclay, which

is nearly impervious to water flow. These peak velocities increase over time as the zone

of DNAPL solvation becomes wider, which enhances focusing. In fact, if spreading is

allowed to persist unabated, the velocity will increase as much as 20% over five years

(to 0.9 m/d at the northern edge of the zone solvated with DNAPL, not shown in Fig.

30).

Three velocities within the profiles were selected as characteristic of flow through

the AB (noted as squares in Fig. 30):

0.75 m/d, which represents a peak velocity where flow focuses at the northern edge

of the DNAPL-solvated zone (0.78 m/d for 2 yr of DNAPL spreading), 0.60 m/d, which represents peak velocities in the northern and southern ends of the

AB away from the focused flow, and 0.55 m/d, which represents typical velocities in the northern and southern ends of the

AB,

Effluent concentrations from a 0.6-m-thick AB are shown in Fig. 31 for adsorption

following the Freundlich isotherm model. Similar predictions are shown in Fig. 32 for a 0.6-m-

thick AB with adsorption following a linear model, in Fig. 33 for a 0.9-m-thick AB with adsorption

following a Freundlich model, and in Fig. 34 for a 0.9-m-thick AB with adsorption following a

linear model.

Initial and more rapid breakthrough occurs earlier along with a more rapid rise in

effluent concentrations when the ground water velocity is higher (Fig. 31c) or the concentration

at the upgradient face is higher (e.g., Fig. 31a). The most rapid breakthrough and the highest

effluent concentrations are anticipated near the northern edge of the DNAPL-solvated zone (Fig.

23

31c, Co = 12 mg/L) due to the high velocity in this region (Fig. 30) and the elevated

concentrations anticipated as ground water contacts the DNAPL-solvated organoclay. In

contrast, much longer breakthrough times are anticipated in the southern regions of the AB,

where velocities and concentrations are lower (Fig. 31a, Co = 0.1 mg/L). Intermediate

breakthrough times and concentrations are anticipated in the northern portion of the AB in

regions away from the DNAPL-solvated zone (Fig. 31b, Co = 7 or 12 mg/L).

Comparison of Figs. 31 and 32 indicates that initial breakthrough occurs later and a

more rapid rise in concentration occurs when a linear isotherm is used. The field condition is

anticipated to fall between the conditions predicted with the linear and Freundlich isotherm

models. Later initial breakthrough times associated with the linear model are anticipated, as

linear adsorption behavior should occur at the low concentrations associated with initial

breakthrough. The less rapid rise in concentrations associated with the Freundlich model

should also be anticipated, because the Freundlich isotherm accounts for the non-linearity of the

isotherm at higher concentrations.

Predicted breakthrough times corresponding to target effluent concentrations of 1.3, 2.6,

and 3.9 mg/L ( 10, 20, and 30% of the aqueous solubility for naphthalene) are summarized in

Tables 11-13. This range of target concentrations is lower than observed naphthalene

concentrations downstream of the proposed AB and thus would not induce a downstream

concentration gradient. Earliest breakthrough at 1.3 mg/L is anticipated to occur in

approximately 5 yr at the northern end of the DNAPL-solvated organoclay (0.6-m-thick AB) and

at approximately 8 yr for a 0.9-m-thick AB. These breakthrough times increase as the target

effluent concentrations increase (Tables 11-12); at 3.9 mg/L, the earliest breakthrough time is

approximately 8 yr (0.6-m-thick AB) or 12 yr (0.9-m-thick AB) (Table 13). Comparison of the

initial breakthrough times shows that the initial breakthrough time can be increased

approximately linearly by increasing the thickness of the AB. Thus, the AB could be made

24

thicker in the most critical regions (e.g., edges of the DNAPL-solvated organoclay) to increase

the overall lifetime.

The importance of managing DNAPL solvation at the influent face of the AB is illustrated

by comparing the breakthrough times for 3.9 mg/L that are reported in Tables 14 and 15.

Breakthrough times in Table 15 correspond to an AB where DNAPL is actively captured before

reaching the face of the AB (e.g., in an upstream trench), which precludes solvation of the

organoclay and formation of an impermeable zone on the upstream face of the barrier. As a

result, focusing of flow is greatly eliminated as illustrated by the velocity profile shown in Fig. 15

(some focusing exists within the AB due to the higher hydraulic conductivity of the organoclay

relative to the aquifer materials). The lower flow velocities result in considerably longer

breakthrough times ( 11 yr for a 0.6-m-thick AB; 17 yr for a 0.9-m-thick AB).

7. CONCLUSIONS AND RECOMMENDATIONS

This study was conducted to support the full-scale design of an adsorptive barrier (AB)

to retain DNAPL and dissolved PAHs at the

. The study consisted of an evaluation of an existing AB at the site, evaluation of

three commercially available organoclays (PM-199, EC-199, and ET-1) that might be used for a

full-scale AB, and modeling for preliminary design. Evaluation of the candidate organoclays

included column tests to quantify the primary transport mode and to confirm transport conditions

under flow-through conditions, and batch tests to quantify adsorption of dissolved PAHs.

The following conclusions follow from the findings of these activities:

1. The distribution of DNAPL in the existing AB was heterogeneous and inconsistent with the

expectations for an AB containing 25% organoclay, which suggests that the organoclay-

sand mixture used in the existing AB was heterogeneous or that DNAPL was within the periphery of the AB during installation.

2. DNAPL migration occurs at a very low rate in organoclay and organoclay-sand mixtures

having at least 25% organoclay. Thus, the primary mechanism for PAH transport in an

25

organoclay AB will be advection of PAHs dissolved in the aqueous phase. DNAPL

conductivities on the order of 10-9 cm/s (ET-1) and 10-10 cm/s (PM-199, EC-199) were obtained for the organoclays. Organoclay-sand mixtures containing at least 25%

organoclay had DNAPL conductivities less than 10-8 cm/s. In contrast, hydraulic conductivity of water-saturated organoclay is on the order of 0.1 cm/s. DNAPL migration

in solvated organoclay should be negligible.

3. Water migration is negligible in organoclays solvated with DNAPL. Hydraulic

conductivities to water on the order of 10-9 cm/s were obtained for the DNAPL-solvated organoclays.

4. Organoclays solvated with DNAPL will release PAHs when contacted with water, even under quiescent conditions. For the dissolution experiments conducted in this study,

concentrations in the aqueous phase under equilibrium conditions were similar to the

maximum PAH concentrations observed in the field. PAHs released from DNAPL-solvated organoclays likely will be adsorbed by the organoclay through which the water is

flowing.

5. Adsorption isotherms for PAHs and organoclays tend to be linear at low concentrations,

but non-linear when considered over a broader range. The non-linearity increases as the adsorbed concentration increases, and can be described by the Freundlich isotherm

model. Greater adsorption also occurs when the aqueous phase contains multiple PAHs. These findings suggest that competition for sorption sites is not an issue when

organoclays are used to adsorb PAHs from the aqueous phase.

6. Adsorption of PAHs was greatest for PM-199, followed by EC-199 and ET-1. PM-199

exhibited greater adsorption compared to EC-199 despite having slightly lower organic carbon content. Greater surface area associated with the smaller granules comprising

PM-199 is believed to be responsible for the greater adsorption behavior of PM-199.

7. PAHs were detected in effluent from only one of the column tests (100% ET-1 organoclay)

after 190 PVF. However, these detections have been sporadic and complete

breakthrough has not occurred. No PAHs have been detected in effluent from any of the other organoclays or organoclay-sand mixtures after 200 PVF and 151 d (organoclays) or

168 PVF and 141 d (mixtures). These observations are consistent with the partitioning observed in the batch adsorption tests.

8. Ground water velocities will vary along the alignment of the AB due to the different hydraulic conductivities in regions of the AB that are solvated or not solvated with DNAPL.

The highest velocities are anticipated at the northern edge of the AB where the flow rate increases due to focusing that occurs as water migrates around the DNAPL-solvated

organoclay.

9. For a 0.6-m-thick AB, breakthrough of naphthalene will occur at the northern edge of the

26

DNAPL-solvated organoclay in 5-8 yr depending on the target effluent concentration being

considered (1.3-3.9 mg/L). For a 0.9-m-thick AB, breakthrough at the northern edge of the DNAPL-solvated organoclay is anticipated in 8-12 yr depending on the target effluent

concentration. If solvation of the organoclay is eliminated by actively managing DNAPL upstream of the AB, breakthrough at 3.9 mg/L will occur in 11 yr (0.6-m-thick AB) or 17 yr

(0.9-m-thick AB).

Based on the findings of this study, the following recommendations are made: 1. Construction methods should be selected that will enhance the likelihood of achieving a

uniform AB. Methods to increase uniformity include construction with an open trench or a biopolymer slurry trench and use of 100% organoclay.

2. DNAPL spreading calculations indicate that active monitoring and maintenance of DNAPL

upgradient of the AB will be necessary to ensure that a significant portion of the AB does not become blocked by DNAPL solvation. Accordingly, an active monitoring and

management scheme is recommended to retain spreading of the DNAPL in the field.

Managing spreading of the DNAPL (or eliminating DNAPL solvation) will also result in longer breakthrough times.

3. PM-199 is recommended for the full-scale AB. PM-199 has very low conductivity to

DNAPL and the greatest affinity for PAHs of the organoclays that were evaluated.

4. The thickness of the AB may be increased in critical areas to increase the breakthrough

time.

8. REFERENCES Abichou, T., Benson, C., and Edil, T. (2002), Micro-Structure and Hydraulic Conductivity of Simulated Sand-Bentonite Mixtures, Clays and Clay Minerals, 50(5), 537-545.

2007 Cope, D. and Benson, C. (2008), Grey-Iron Foundry Slags as Reactive Media for Removing Trichloroethylene from Groundwater, Environmental Science and Technology, in review. Fetter, C. (1999), Contaminant Hydrogeology, Upper Saddle River, NJ, Prentice Hall, 1999 Jo, H., Benson, C., and Edil, T. (2004), Hydraulic Conductivity and Cation Exchange in Non-Prehydrated and Prehydrated Bentonite Permeated with Weak Inorganic Salt Solutions, Clays

and Clay Minerals, 52(6), 661-679. Mesri, G. and Olson, R. (1971), Mechanisms Controlling the Permeability of Clays, Clays and

Clay Minerals, 19, 151-158.

27

RSI (1991), MOFAT: A Two-Dimensional Finite Element Program for Multiphase Flow and Multicomponent Transport, Resources & Systems International, Inc., Blacksburg VA, 1991

im nek, J.; ejna, M.; van Genuchten, M. (2007), The HYDRUS Software Package for

Simulating the Two- and Three-Dimensional Movement of Water, Heat, and Multiple Solutes

in Variably-Saturated Media, Version 1.02. USEPA (2008), Estimation Programs Interface (EPI) Suite™ for Microsoft® Windows, v 3.20, United States Environmental Protection Agency, Washington, DC, USA. WSPL (2005), Carbon (Total, Organic, and Inorganic), Standard Method, Wisconsin Soil and Plant Analysis Laboratory, University of Wisconsin, Madison, WI.

28

TABLES

29

Table 1. Mineralogical composition of the organoclays as

determined by XRD.

Relative Abundance (%) Mineral Constituents

PM-199 ET-1 EC-199

Quartz 14 20 8

Cristobalite - 12 -

Tridymite 2 1 -

Plagioclase Feldspar 12 3 2

K-Feldspar 2 <1 2

Calcite 1 <1 -

Dolomite 1 - -

Halite 5 - 5

Gypsum - - <1

Hornblende - - -

Illite 1 - <1

Smectite 62 64 83

Table 2. Geotechnical properties of organoclays.

Organoclay Specific Gravity

of Solids Organic Carbon

Content (%) Hydraulic Conductivity

(cm/s)

PM-199 1.75 25.0 0.14

ET-1 2.00 15.5 0.12

EC-199 1.75 26.9 0.39

30

Table 3. PAH concentrations in DNAPL [PAHs account for 50% (by

wt.) of total liquid analyzed].

Compound Concentration (mg/kg)

2-Methylnaphthalene 22000

Acenaphthene 20000

Acenaphthylene 420

Anthracene 7200

Benzo(a)anthracene 5900

Benzo(a)pyrene 2800

Benzo(b)fluoranthene 4300

Benzo(g,h,i)perylene 1000

Benzo(k)fluoranthene 1500

Chrysene 4100

Dibenzo(a,h)anthracene <49

Fluoranthene 27000

Fluorene 20000

Indeno(1,2,3-cd)pyrene 910

Naphthalene 120000

Phenanthrene 74000

Pyrene 19000

31

Table 4. PAH concentrations from DNAPL solubility tests along with maximum

concentrations observed in ground water at the field site, effective solubilities computed using Raoult’s Law, and solubilities reported by USEPA’s EPI Suite (v.3.20).

Compound DNAPL-Water Ratio

Mixing Time (hr)

Conc. (mg/L)

Approximate Maximum

Concentration in Ground

Water (mg/L)1

Effective Solubility

(mg/L)

EPI Aqueous Solubility at 25 °C (mg/L)

24 0.72 5-35

48 1.83 24 0.78

Acenaphthene

20-20 48 1.24

0.5 0.2 3.9

24 26.4 5-35

48 30.2 24 26.7 Naphthalene

20-20 48 27.1

11.0 13.7 31.0

24 0.63 5-35

48 3.44 24 0.83

Phenanthrene 20-20

48 1.39

0.2 0.2 1.2

Note: 1Maximum concentration obtained from data shown in Fig. 20.

Table 5. Total PAH concentrations (mg/kg) for core samples from existing AB and adjacent aquifer material.

DNAPL Presence

High High High High Medium Medium Medium Low Low Low

Location of Sample (m bgs) Compound

T2-B4 (1.4-1.8)

T1-B3 (1.8-2.1)

T3-B2 (1.3-1.8)

T1-B3 (5.5-5.7)

T2-B4 (2.6-3.3)

T3-B2 (2.6-2.9)

T1-B3 (1.6-1.8)

T3-B2 (3.0-3.3)

T2-B4 (2.4-2.9)

T1-B2 (1.6-1.8)

2-Methylnaphthalene 500 500 310 180 200 120 370 45 0.12 250

Acenaphthene 200 220 120 39 < 16 55 170 < 14 < 0.014 110

Acenaphthylene <32 < 16 < 16 < 34 < 18 < 18 < 15 < 16 < 0.016 < 19

Anthracene 280 320 240 340 100 66 220 9.4 0.075 110

Benzo(a)anthracene 78 75 45 9.2 36 30 50 3.1 0.014 31

Benzo(a)pyrene 31 43 14 < 3.3 11 6.7 22 1.7 < 0.0011 11

Benzo(b)fluoranthene 20 29 12 4.1 7.9 5.4 16 < 1.1 0.057 8.8

Benzo(g,h,i)perylene < 6.2 13 < 3.4 < 6.5 < 3.8 < 3.8 6 < 3.3 < 0.003 < 4.1

Benzo(k)fluoranthene 14 15 6.7 < 3.3 5.2 2.6 11 < 2.2 < 0.002 5.1

Chrysene 86 110 48 14 38 2.1 79 3.7 0.041 45

Dibenzo(a,h)anthracene < 5.2 < 3.4 < 3.4 < 5.4 < 3.8 < 3.8 < 3.2 < 3.3 < 0.003 < 4.1

Fluoranthene 140 340 190 70 170 92 260 10 0.12 180

Fluorene 260 250 78 110 80 61 200 < 6.7 0.077 130

Indeno(1,2,3-cd)pyrene < 3.1 20 5.7 < 3.3 < 2.5 < 2.5 10 < 2.2 < 0.002 6.6

Naphthalene 1600 5200 2100 250 4700 530 660 1400 0.25 190

Phenanthrene 320 710 200 250 300 170 560 25 0.069 360

Pyrene 160 190 100 35 95 41 130 7.2 0.086 79

Note: All samples from existing AB cores except T1-B3, which is aquifer sand beneath AB.

33

Table 6. Dry densities and pore volumes of organoclays and organoclay-sand

mixtures used in DNAPL conductivity tests. All mixtures prepared with PM-199 organoclay. Percentage shown in materials column is for organoclay fraction of organoclay-sand mixture.

Material Column Height

(mm) Dry Density

(Mg/m3) Pore Volume

(mL)

PM-199 52 0.80 79

ET-1 52 0.68 72

EC-199 52 0.77 78

0% PM-199 153 1.74 136

10% PM-199 153 1.59 149

25% PM-199 153 1.37 172

50% PM-199 153 1.11 189

Table 7. Summary of conductivities for organoclays and organoclay-sand mixtures. All mixtures prepared with PM-199 organoclay. Percentage shown in materials column is for organoclay fraction of organoclay-sand mixture.

Material Permeant

Liquid Test

Duration (d) Hydraulic

Conductivity (cm/s)

PM-199 DNAPL/Water 75 7.6X10-10 (for DNAPL) 9.6X10-10 (for water)

ET-1 DNAPL 46 3.4X10-9

EC-199 DNAPL/Water 75 3.7X10-10 (for DNAPL)

1.1X10-9 (for water)

0% PM-199 DNAPL 1 4.1X10-5

10% PM-199 DNAPL 1 2.6X10-6

25% PM-199 DNAPL 42 8.6X10-9

50% PM-199 DNAPL 42 2.8X10-9

34

Table 8. Parameters of Freundlich isotherm model fitted to batch test data.

KF (L/kg) n R2 Organoclay PAHs

Single Multiple Single Multiple Single Multiple

Naphthalene 3285 3888 1.13 1.23 0.99 0.99

Acenaphthene 6236 20,500 0.60 1.06 0.97 0.99 PM-199

Phenanthrene 57,480 3,259,000 0.93 1.83 0.98 0.90

Naphthalene - 361 - 1.23 - 0.59

Acenaphthene - 1749 - 1.02 - 0.93 ET-1

Phenanthrene - 13,430 - 1.19 - 0.98

Naphthalene - 1876 - 1.28 - 0.98

Acenaphthene - 10,630 - 1.04 - 0.97 EC-199

Phenanthrene - 263,400 - 1.56 - 0.77

Table 9. Partition coefficient for linear isotherm (K) and normalized distribution coefficient for the organic carbon fraction (Koc) for PM-199 organoclay.

Compound Kd

(L/kg) R2

Koc

(L/kg)

Naphthalene 3945 0.99 15,780

Acenaphthene 11,240 0.89 44960

Phenanthrene 72,970 0.99 291880

Table 10. Hydraulic parameters used in HYDRUS for flow simulations.

Hydraulic Properties

Material θr θs α (m-1) n

Saturated Hydraulic Conductivity

Water Saturated AB

0.135 0.63 6.24 6.51 0.14

Aquifer 0.045 0.43 14.5 2.68 0.06

DNAPL-Solvated AB

0.068 0.43 0.08 1.09 9.6 x 10-10

35

Table 11. Elapsed time when effluent concentrations exceed 1.3 mg/L at the

downgradient face of AB with partial blockage by NAPL-solvated organoclay.

Barrier thickness

(m)

Ground Water

Velocity (m/d)

Initial Concentration at Upgradient Face (mg/L)

Initial breakthrough time (yr) -

Freundlich model

Initial breakthrough

time (yr) - linear model

12 7.0 7.5 0.55

7 7.9 8.7

12 6.4 6.9

7 7.2 8.0 0.60

0.1 - -

0.6

0.75 12 5.1 5.5

12 10.5 11.3 0.55

7 11.8 13.1

12 9.7 10.4

7 10.8 12.0 0.60

0.1 - -

0.9

0.75 12 7.7 8.3

36

Table 12. Elapsed time when effluent concentrations exceed 2.6 mg/L at the

downgradient face of AB with partial blockage by NAPL-solvated organoclay.

Barrier thickness

(m)

Ground Water

Velocity (m/d)

Initial Concentration at Upgradient Face (mg/L)

Initial breakthrough time (yr) -

Freundlich model

Initial breakthrough

time (yr) - linear model

12 9.6 9.2 0.55

7 11.3 11.1

12 8.8 8.4

7 10.4 10.2 0.60

0.1 - -

0.75 12 7.0 6.7

0.6

0.78 12 6.6 6.5

12 14.4 13.8 0.55

7 17.0 16.7

12 13.2 12.6

7 15.6 15.3 0.60

0.1 - -

0.75 12 10.6 10.1

0.9

0.78 12 10.1 9.7

37

Table 13. Elapsed time when effluent concentrations exceed 3.9 mg/L at the

downgradient face of AB with partial blockage by NAPL-solvated organoclay.

Barrier thickness

(m)

Ground Water

Velocity (m/d)

Initial Concentration at Upgradient Face (mg/L)

Initial breakthrough time (yr) -

Freundlich model

Initial breakthrough

time (yr) - linear model

12 11.9 10.6 0.55

7 14.9 13.6

12 10.9 9.7

7 13.6 12.4 0.60

0.1 - -

0.75 12 8.7 7.7

0.6

0.78 12 8.1 7.4

12 17.8 15.8 0.55

7 22.3 20.3

12 16.3 14.5

7 20.5 18.7 0.60

0.1 - -

0.75 12 13.0 11.6

0.9

0.78 12 12.5 11.2

38

Table 14. Elapsed time when effluent concentrations exceed 2.6 mg/L at the

downgradient face of AB without blockage by NAPL-solvated organoclay.

Barrier thickness

(m)

Ground Water

Velocity (m/d)

Initial Concentration at Upgradient Face (mg/L)

Initial breakthrough time (yr) -

Freundlich model

Initial breakthrough

time (yr) - linear model

12 10.0 9.8

7 11.8 11.9 0.6 0.55

0.1 - -

12 15.4 14.7

7 18.1 17.8 0.9 0.55

0.1 - -

39

Table 15. Elapsed time when effluent concentrations exceed 3.9 mg/L at the

downgradient face of AB without blockage by NAPL-solvated organoclay.

Barrier thickness

(m)

Ground Water

Velocity (m/d)

Initial Concentration at Upgradient Face (mg/L)

Initial breakthrough time (yr) -

Freundlich model

Initial breakthrough

time (yr) - linear model

12 12.3 11.3

7 15.5 14.5 0.52

0.1 - -

12 11.9 10.6

0.6

0.55 7 14.9 13.6

12 19.0 16.9

7 23.9 21.7 0.52

0.1 - -

12 17.8 15.8

0.9

0.55 7 22.3 20.3

40

FIGURES

41

Fig. 1. Aerial view of site showing former tie-treating facility and location of existing AB (adapted from ).

Existing ABExisting AB

42

(a)

(b)

Fig. 2. Cross sections B-B’ (a) and D-D’ (b) showing DNAPL zone and existing AB. Refer to Fig. 1 for spatial referencing.

43

0

20

40

60

80

100

0.010.1110

PM-199ET-1EC-199

Per

cent

Fin

er (%

)

Particle Diameter (mm)

(a)

0

20

40

60

80

100

0.010.1110100

T2-B2T2-B3T2-B4

Per

cent

Fin

er (%

)

Particle Size (mm)

(b)

Fig. 3. Particle size distributions of organoclays (a) and aquifer materials (b).

44

Fig. 4. Apparatus for DNAPL conductivity tests conducted with PM-199, ET-1, and EC-199.

45

0

50

100

150

200

800

1000

1200

1400

0 10 20 30 40 50

(a)

NaphthaleneAcenaphtenePhenanthreneFluoranthene

Am

ount

Sor

bed

(mg/

kg)

Elapsed Time (hours)

0

50

100

150

200

800

1000

1200

1400

0 10 20 30 40 50

(b)

Am

ount

Sor

bed

(mg/

kg)

Elapsed Time (hours)

0

50

100

150

200

800

1000

1200

1400

0 10 20 30 40 50

(c)

Am

ount

Sor

bed

(mg/

kg)

Elapsed Time (hours)

Fig. 5. Sorption kinetics of PM-199 (a), ET-1 (b), and EC-199 (c) for naphthalene, acenaphthene, phenanthrene, and fluoranthene.

46

Fig. 6. Photograph of column tests for dissolved PAHs (naphthalene, acenaphthene, and phenanthrene) using glass beads (control), PM-199, ET-1, EC-199, 25% organoclay-sand mixture, and 50% organoclay-sand mixture.

47

Fig. 7. Location of cores from existing AB.

T3

T2

T1

0.45 m

81 m

G.W. flow

North

South

B1 B2 B3 B4

B1 B2 B3 B4

B1 B2 B3

7.5

m7.

5 m

T3

T2

T1

0.45 m

81 m

G.W. flow

North

South

B1 B2 B3 B4

B1 B2 B3 B4

B1 B2 B3

7.5

m7.

5 m

48

Fig. 8. DNAPL distribution in core samples from existing AB.

0.0 m

9.0 m

4.5 m

0.0 m

9.0 m

4.5 m

0.0 m

9.0 m

4.5 m

PAB depth (3.3 m)

High

Medium

Low

T3

T2

T1

B1 B2 B3 B4

B1 B2 B3 B4

B1 B2 B3

0.0 m

9.0 m

4.5 m

0.0 m

9.0 m

4.5 m

0.0 m

9.0 m

4.5 m

PAB depth (3.3 m)

High

Medium

Low

0.0 m

9.0 m

4.5 m

0.0 m

9.0 m

4.5 m

0.0 m

9.0 m

4.5 m

PAB depth (3.3 m)

High

Medium

Low

High

Medium

Low

T3

T2

T1

B1 B2 B3 B4

B1 B2 B3 B4

B1 B2 B3

49

Fig. 9. Top view (a), side view (b), and cross-sectional view of influent end (c) of PM-199 after

preliminary column test. Black zone at bottom in (c) is thin (1 mm) layer of gel-like organoclay solvated with DNAPL.

(a)

(b)

(c)

50

Fig. 10. Top view (a), side view (b), and cross-sectional view (c) of ET-1 after preliminary

column test.

(a)

(b)

(c)

51

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

0.0

0.5

1.0

1.5

2.0

0 20 40 60 80

(a)

NAPL ConductivityQ

out/Q

in

NA

PL

Con

duct

ivity

(cm

/s)

Qout /Q

in

Days

WaterNAPL

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

0.0

0.5

1.0

1.5

2.0

0 10 20 30 40 50

(b)

NA

PL

Con

duct

ivity

(cm

/s)

Qout /Q

in

Days

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 20 40 60 80

(c)

NA

PL

Con

duct

ivity

(cm

/s)

Qout /Q

in

Days

WaterNAPL

Fig. 11. DNAPL conductivity of PM-199 (a), ET-1 (b), and EC-199 (c), and subsequent hydraulic conductivity to water; open circles

are ratio of incremental effluent volume to influent volume; conductivity was calculated based on the influent flow rate.

52

0.0

1.0 10-9

2.0 10-9

3.0 10-9

4.0 10-9

5.0 10-9

10 15 20 25 30 35

KDNAPL

(cm/s) = 7.5x10-9 - 2.7 OC

DN

AP

L C

ondu

ctiv

ity (c

m/s

)

Organic Carbon Content (%)

Fig. 12. DNAPL conductivity of organoclays as a function of organic carbon content

53

10-9

10-8

10-7

10-6

10-5

10-4

10-3

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0 2.5

(a)

NAPL Conductivity Q

out/Q

in

NA

PL

Con

duct

ivity

(cm

/s)

Qout /Q

in

Pore Volumes of Flow (PVF)

10-9

10-8

10-7

10-6

10-5

10-4

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

(b)

NA

PL

Con

duct

ivity

(cm

/s)

Qout /Q

in

Pore Volumes of Flow (PVF)

10-9

10-8

10-7

10-6

10-5

10-4

10-3

0.0

0.5

1.0

1.5

2.0

0 10 20 30 40 50

(c)

NA

PL

Con

duct

ivity

(cm

/s)

Qout /Q

in

Days

10-9

10-8

10-7

10-6

10-5

10-4

0.0

0.5

1.0

1.5

2.0

0 10 20 30 40 50

(d)

NA

PL

Con

duct

ivity

(cm

/s)

Qout /Q

in

Days

Fig. 13. DNAPL conductivity for organoclay-sand mixtures with organoclay contents of 0 (a), 10

(b), 25 (c), and 50% (d) by weight; open circles are ratio of incremental effluent volume to influent volume; conductivity calculated using influent flow rate.

54

10-10

10-9

10-8

10-7

10-6

10-5

10-4

0 25 50 75 100

DN

APL

Con

duct

ivity

(cm

/s)

Organoclay Content in the Mixture (%)

Fig. 14. DNAPL conductivity as a function of organoclay content in organoclay-sand mixture.

55

Fig. 15. Top view (a), side view (b), cross sectional view (by wire saw) (c), and cross sectional

view by cracking (d) of PM-199 after DNAPL conductivity test.

(a) (b)

(c) (d)

56

Fig. 16. Top view (a), cross sectional view (by wire saw) (b), and cross sectional view by

cracking (c) of EC-199 after DNAPL conductivity test.

(a)

(b)

(c)

57

Fig. 17. Top view (a) and cross sectional view (b) of ET-1 after DNAPL conductivity test.

(a)

(b)

58

Fig. 18. Top view (a), side view (b), cross sectional view (by wire saw) (c), and cross sectional

view by cracking (d) of 25% mixture of organoclay and sand after DNAPL conductivity test.

(a) (b)

(c) (d)

59

0

2

4

6

8

10

12

14

0 50 100 150 200 250

(a)

PM 19950%EC-199Field Highest Data

Con

cent

ratio

n (m

g/L)

Time (hours)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 50 100 150 200 250

(b)

Con

cent

ratio

n (m

g/L)

Time (hours)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0 50 100 150 200 250

(c)

Con

cent

ratio

n (m

g/L)

Time (hours)

Fig. 19. Dissolution of naphthalene (a), acenaphthene (b), and phenanthrene (c) into water

from DNAPL-solvated organoclays under quiescent conditions.

60

1 x 10-1

1 x 100

1 x 101

1 x 102

1 x 103

1 x 104

1 x 1052-

Met

hyln

apht

hale

ne

Acen

apht

hene

Benz

on (a

) ant

hrac

ene

Car

bazo

le

Chr

ysen

e

Dib

enzo

fura

n

Fluo

rant

hene

Fluo

rene

Nap

htha

lene

Phe

nant

hren

e

Con

cent

ratio

n (μ

g/L)

Lowest of the , Part 201 Generic Cleanup Criteria

Fig. 20. Distribution of dissolved PAH concentrations in ground water around the existing AB.

generic cleanup criteria for PAHs are 19 μg/L for acenaphthene, 13 μg/L for naphthalene, 1.6 μg/L for fluoranthene, and 2.4 μg/L for phenanthrene.

61

0

10000

20000

30000

40000

50000

0 1 2 3 4 5 6 7 8

(a)

Single CompoundMultiple Compounds

q e(mg/

kg)

Ce (mg/L)

0

1000

2000

3000

4000

5000

6000

7000

0.0 0.1 0.2 0.3 0.4 0.5

(b)

q e(mg/

kg)

Ce (mg/L)

0

2000

4000

6000

8000

10000

0.00 0.02 0.04 0.06 0.08 0.10 0.12

(c)

q e(mg/

kg)

Ce (mg/L)

Fig. 21. Adsorption isotherms of PM-199 for naphthalene (a), acenaphthene (b), and

phenanthrene (c) with fits of Freundlich isotherm model for solutions prepared with a single PAH or multiple PAHs.

62

3.0

3.5

4.0

4.5

5.0

5.5

6.0

3.0 3.5 4.0 4.5 5.0 5.5 6.0

log

K oc

log Kow

Fig. 22. Relationship between organic carbon partition coefficient (Koc) and octanol-water

partition coefficient (Kow) for PM-199; fitted line corresponds to log Koc = 1.08 log Kow + 0.554 (R2=0.96). Koc is in L/kg.

63

0

10000

20000

30000

40000

50000

60000

0 2 4 6 8 10 12

(a)

PM-199ET-1EC-199

q e(mg/

kg)

Ce (mg/L)

0

1000

2000

3000

4000

5000

6000

0.0 0.2 0.4 0.6 0.8 1.0 1.2

(b)q e(m

g/kg

)

Ce (mg/L)

0

1000

2000

3000

4000

5000

6000

0.0 0.1 0.2 0.3 0.4 0.5

(c)

q e(mg/

kg)

Ce (mg/L)

?

Fig. 23. Adsorption isotherms of PM-199, ET-1 and EC-199 for naphthalene (a),

acenaphthene (b), and phenanthrene (c) with fits of Freundlich isotherm model.

64

0

5

10

15

20

25

0 50 100 150 200 250 300

(a)

Glass BeadsPM 199ET-1EC-199Field Highest Conc.

Con

cent

ratio

n (m

g/L)

PVF

0.0

2.0

4.0

6.0

8.0

10.0

0 50 100 150 200 250 300

(b)

Con

cent

ratio

n (m

g/L)

PVF

0.0

1.0

2.0

3.0

4.0

5.0

0 50 100 150 200 250 300

(c)

Con

cent

ratio

n (m

g/L)

PVF

Fig. 24. Effluent concentration of naphthalene (a), acenaphthene (b), and phenanthrene (c)

from the columns containing glass beads (control), PM-199, ET-1, and EC-199.

65

0

5

10

15

20

25

0 50 100 150 200 250 300

(a)

Glass BeadsPM 19925%50%Field Highest Conc.

Con

cent

ratio

n (m

g/L)

PVF

0.0

2.0

4.0

6.0

8.0

10.0

0 50 100 150 200 250 300

(b)

Con

cent

ratio

n (m

g/L)

PVF

0.0

1.0

2.0

3.0

4.0

5.0

0 50 100 150 200 250 300

(c)

Con

cent

ratio

n (m

g/L)

PVF

Fig. 25. Effluent concentration of naphthalene (a), acenaphthene (b) and phenanthrene (c)

from columns containing PM-199 (replicate), 25% organoclay-sand mixture, and 50 % organoclay-sand mixture.

66

Fig. 26. Location (red dashed line) and dimensions of hypothetical full-scale AB.

Existing AB

Hypothetical AB

Existing AB

Hypothetical AB

Existing AB

Hypothetical AB

67

Fig. 27. Area covered by hypothetical full-scale AB and elevations at which two primary DNAPL layers exist.

Hypothetical AB region

D’ D

176 m

9 m

Elevation at which primary NAPL plume exist

575 ft

565 ft

Hypothetical AB region

D’ D

176 m

9 m

Elevation at which primary NAPL plume exist

575 ft

565 ft

68

Fig. 28. DNAPL spreading (heavy black line) at the upgradient face (open rectangle) of AB at elevation 575 and 565 ft for 0, 1, 2, 5, and 10 yr after installation of the AB.

NAPLElevation (ft)Time elapsed (yr)

575

0 1 2 5

565

North (SB 10-07)

South(SB 03-07)

North (SB 10-07)

South(SB 03-07)

63.13 m

79.69 m

53.44 m

76.56 m

61.26 m

83.43 m 86.87 m 95.95 m

59.54 m 55.00 m

71.26 m

64.04 m 72.30 m 91.14 m

67.13 m 57.71 m

10

108.47 m

48.74 m

114.04 m

46.26 m

(Not in scale)NAPLNAPLElevation (ft)

Time elapsed (yr)

575

0 1 2 5

565

North (SB 10-07)

South(SB 03-07)

North (SB 10-07)

South(SB 03-07)

63.13 m

79.69 m

53.44 m

76.56 m

61.26 m

83.43 m 86.87 m 95.95 m

59.54 m 55.00 m

71.26 m

64.04 m 72.30 m 91.14 m

67.13 m 57.71 m

10

108.47 m

48.74 m

114.04 m

46.26 m

(Not in scale)

69

Fig. 29. Domain used in HYDRUS for flow and transport simulations.

Not in scale

AB

Aquifer

NAPL10 m

10 m

10 m

GW

63 m

N

S

80 m

0.6 m

10 m

33 m

Not in scale

AB

Aquifer

NAPL10 m

10 m

10 m

GW

63 m

N

S

80 m

0.6 m

10 m

33 m AB

Aquifer

NAPL10 m

10 m

10 m

GW

63 m

N

S

80 m

0.6 m

10 m

33 m

Not to Scale

70

0

0.2

0.4

0.6

0.8

1

Gro

undw

ater

Vel

ocity

(m/d

ay)

N

Aquifer

Aquifer

S

PAB

NAPL

0.60 m/day

0.75 m/day

0.60 m/day

0.55 m/day 0.55 m/day

(a)

0

0.2

0.4

0.6

0.8

1

Gro

undw

ater

Vel

ocity

(m/d

ay)

N

Aquifer

Aquifer

S

PAB

NAPL

0.60 m/day

0.78 m/day

0.60 m/day

0.55 m/day 0.55 m/day

(b)

0

0.2

0.4

0.6

0.8

1

0 40 80 120 160

Gro

undw

ater

Vel

ocity

(m/d

ay)

Distance from North End of Domain (m)

N

Aquifer

Aquifer

S

PAB

NAPL

0.60 m/day

0.78 m/day

0.60 m/day

0.55 m/day 0.55 m/day

(c)

Fig. 30. Groundwater velocity profile at mid-plane along alignment of the AB immediately after

contact between NAPL and organoclay (0 yr), 1 yr after contact (b), and 2 yr after contact.

71

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 5 10 15 20

C0=12 mg/L

C0=7 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(a)

Vs=0.55 m/day

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 5 10 15 20

C0=12 mg/L

C0=7 mg/L

C0=0.1 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(b)

Vs=0.60 m/day

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 5 10 15 20

C0=12 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(c)

Vs=0.75 m/day

Fig. 31. Naphthalene concentration at the effluent face of 0.6-m-thick AB using a Freundlich

isotherm model for a groundwater velocity of 0.55 (a), 0.60 (b), and 0.75 m/d (c).

72

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 5 10 15 20

C0=12 mg/L

C0=7 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(a)

Vs=0.55 m/day

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 5 10 15 20

C0=12 mg/L

C0=7 mg/L

C0=0.1 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(b)

Vs=0.60 m/day

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 5 10 15 20

C0=12 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(c)

Vs=0.75 m/day

Fig. 32. Naphthalene concentration at the effluent face of 0.6-m-thick AB using a linear isotherm model

for a groundwater velocity of 0.55 (a), 0.60 (b), and 0.75 m/d (c).

73

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 5 10 15 20

C0=12 mg/L

C0=7 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(a)

Vs=0.55 m/day

0.0

2.0

4.0

6.0

8.0

10.0

0 5 10 15 20

C0=12 mg/L

C0=7 mg/L

C0=0.1 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(b)

Vs=0.60 m/day

0.0

2.0

4.0

6.0

8.0

10.0

0 5 10 15 20

C0=12 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(c)

Vs=0.75 m/day

Fig. 33. Naphthalene concentration at the effluent face of 0.9-m-thick AB using a Freundlich

isotherm model for a groundwater velocity of 0.55 (a), 0.60 (b), and 0.75 m/d (c).

74

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 5 10 15 20

C0=12 mg/L

C0=7 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(a)

Vs=0.55 m/day

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 5 10 15 20

C0=12 mg/L

C0=7 mg/L

C0=0.1 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(b)

Vs=0.60 m/day

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 5 10 15 20

C0=12 mg/L

Con

cent

ratio

n at

the

dow

n-gr

adie

nt fa

ce o

f AB

(mg/

L)

Time elpased (yr)

(c)

Vs=0.75 m/day

Fig. 34. Naphthalene concentration at the effluent face of 0.9-m-thick AB using a linear

isotherm model for a groundwater velocity of 0.58 (a), 0.65 (b), and 0.90 m/d (c).

75

0.45

0.5

0.55

0.6

0.65

0 40 80 120 160

Gro

undw

ater

Vel

ocity

(m/d

ay)

Distance from North End of Domain (m)

N

Aquifer

Aquifer

S

PAB

0.52 m/d

0.55 m/d

Fig. 35. Groundwater velocity profile at mid-plane along alignment of AB without blockage by

NAPL-solvated organoclay

76

APPENDIX A – CAPILLARY PRESSURE CURVES

77

0.001

0.01

0.1

1

10

100

0 10 20 30 40 50 60 70

(a)

Experimental DataFitted Data

Cap

illar

y P

ress

ure

(kP

a)

Volumetric Water Content (%)

0.01

0.1

1

10

100

0 10 20 30 40 50

(b)

Cap

illar

y P

ress

ure

(kP

a)

Volumetric Water Content (%)

0.001

0.01

0.1

1

10

100

0 10 20 30 40 50 60 70

(c)

Cap

illar

y P

ress

ure

(kP

a)

Volumetric Water Content (%)

Fig. A1. Capillary pressure curves for PM-199 (a), ET-1, (b), and EC-199 (c) for an air-

deionized water system.

APPENDIX B – SATURATED HYDRAULIC CONDUCTIVITY

Sample: T2-B2 28.2-30.0 Cell Diameter 63 mmDescription: Aquifer Sand Cell Height 14 cmDate: 7 Mar 2008 Cell Area 31.17 cm2

Tested by: Jeremy Baugh Cell Volume 436.4 cm3

Weight of Dry Soil g Standpipe Diameter 70 mmDry Unit Weight 0.00 kN/m3 Tube Outer Diameter 12.5 mmΔH 11 cm Standpipe Area 37.26 cm2

Gradient, i 0.79

Outflow h1 h2 h1 - h2 Inflow k(mL) (m:s) (s) (cm) (cm) (cm) (mL) (cm/s)

1 451 2:04.16 124 56.9 44.7 12.2 455 0.148 0.992 470 1:56.13 116 44.7 31.7 13.0 484 0.165 0.973 486 1:58.49 118 31.7 18.2 13.5 503 0.168 0.974 507 2:07.11 127 57.0 43.3 13.7 510 0.163 0.995 539 2:09.79 130 43.3 28.5 14.8 551 0.169 0.986 432 1:42.73 103 28.5 16.3 12.2 455 0.171 0.95

Constant Head Permeability

Test Time Qout/Qin

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0 1 2 3 4 5 6 7Test Number

Hy

dra

uli

c C

on

du

cti

vit

y (

cm

/s)

0.75

1.00

1.25

Qo

ut/

Qin

Hydraulic ConductivityQout/Qin

Sample: T2-B3 28-30 Cell Diameter 63 mmDescription: Aquifer Sand Cell Height 14 cmDate: 7 Mar 2008 Cell Area 31.17 cm2

Tested by: Jeremy Baugh Cell Volume 436.4 cm3

Weight of Dry Soil 881.1 g Standpipe Diameter 70 mmDry Unit Weight 19.81 kN/m3 Tube Outer Diameter 12.5 mmΔH 11 cm Standpipe Area 37.26 cm2

Gradient, i 0.79

Outflow h1 h2 h1 - h2 Inflow k(mL) (m:s) (s) (cm) (cm) (cm) (mL) (cm/s)

1 461 5:07.01 307 56.9 44.4 12.5 466 0.061 0.992 468 5:11.49 311 44.4 - - - 0.061 -3 448 5:19.60 320 31.3 18.7 12.6 469 0.057 0.954 431 4:46.66 287 55.8 44.0 11.8 440 0.061 0.985 485 5:13.13 313 44.0 31.5 12.5 466 0.063 1.046 450 5:15.61 316 54.7 42.1 12.6 469 0.058 0.967 490 5:36.16 336 42.1 29.1 13.0 484 0.060 1.018 497 5:38.39 338 29.1 15.1 14.0 522 0.060 0.959 529 6:04.33 364 57.9 43.7 14.2 529 0.059 1.00

10 515 5:59.96 360 43.7 29.4 14.3 533 0.058 0.9711 491 5:41.23 341 29.4 15.7 13.7 510 0.059 0.96

Constant Head Permeability

Test Time Qout/Qin

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 2 4 6 8 10 12Test Number

Hy

dra

uli

c C

on

du

cti

vit

y (

cm

/s)

0.75

1.00

1.25

Qo

ut/

Qin

Hydraulic ConductivityQout/Qin

Sample: T2-B4 28.5-30.0 Cell Diameter 63 mmDescription: Aquifer Sand Cell Height 14 cmDate: 7 Mar 2008 Cell Area 31.17 cm2

Tested by: Jeremy Baugh Cell Volume 436.4 cm3

Weight of Dry Soil 819.7 g Standpipe Diameter 70 mmDry Unit Weight 18.43 kN/m3 Tube Outer Diameter 12.5 mmΔH 11 cm Standpipe Area 37.26 cm2

Gradient, i 0.79

Outflow h1 h2 h1 - h2 Inflow k(mL) (m:s) (s) (cm) (cm) (cm) (mL) (cm/s)

1 405 1:54.95 115 - 41.0 - - 0.144 -2 398 1:48.96 109 41.0 30.1 10.9 406 0.149 0.983 430 2:00.08 120 30.1 18.0 12.1 451 0.146 0.954 518 2:29.94 150 56.8 42.9 13.9 518 0.141 1.005 419 2:05.64 126 42.9 31.5 11.4 425 0.136 0.996 446 2:11.43 131 30.2 17.7 12.5 466 0.139 0.96

Qout/QinTest Time

Constant Head Permeability

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0 1 2 3 4 5 6 7Test Number

Hy

dra

uli

c C

on

du

cti

vit

y (

cm

/s)

0.75

1.00

1.25

Qo

ut/

Qin

Hydraulic ConductivityQout/Qin

Sample: PM199 Cell Diameter 63 mmDescription: Organoclay Sample Height 15 cmDate: 5 May 2008 Cell Area 31.17 cm2

Tested by: Jeremy Baugh Sample Volume 467.6 cm3

Weight of Dry Soil 369.8 g Standpipe Diameter 70 mmDry Unit Weight 7.76 kN/m3 Tube Outer Diameter 12.5 mmΔH 11 cm Standpipe Area 37.26 cm2

Gradient, i 0.73

Outflow h1 h2 h1 - h2 Inflow k(mL) (m:s) (s) (cm) (cm) (cm) (mL) (cm/s)

1 455 1:59.76 120 58.1 45.7 12.4 462 0.166 0.982 503 2:11.08 131 45.7 31.9 13.8 514 0.168 0.983 583 2:34.48 154 31.9 15.6 16.3 607 0.166 0.964 511 2:13.14 133 58.6 44.8 13.8 514 0.168 0.995 500 2:13.89 134 44.8 31.2 13.6 507 0.163 0.996 524 2:26.59 147 31.2 16.6 14.6 544 0.156 0.967 521 2:33.33 153 58.5 44.4 14.1 525 0.149 0.998 519 2:33.68 154 44.4 30.2 14.2 529 0.147 0.989 520 2:38.93 159 30.2 15.7 14.5 540 0.143 0.9610 510 2:32.55 153 58.5 44.7 13.8 514 0.146 0.9911 514 2:35.03 155 44.7 30.6 14.1 525 0.145 0.9812 503 2:35.58 156 30.6 16.6 14.0 522 0.141 0.9613 512 2:35.48 155 58.2 44.4 13.8 514 0.144 1.0014 509 2:38.71 159 44.4 30.4 14.0 522 0.140 0.9815 510 2:40.33 160 30.4 16.2 14.2 529 0.139 0.96

Constant Head Permeability

Test Time Qout/Qin

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0 2 4 6 8 10 12 14 16

Test Number

Hy

dra

uli

c C

on

du

cti

vit

y (

cm

/s)

0.75

1.00

1.25

Qo

ut/

Qin

Hydraulic ConductivityQout/Qin

Sample: ET-1 Cell Diameter 63 mmDescription: Organoclay Sample Height 14 cmDate: 31 Mar 2008 Cell Area 31.17 cm2

Tested by: Jeremy Baugh Sample Volume 436.4 cm3

Weight of Dry Soil 314.7 g Standpipe Diameter 70 mmDry Unit Weight 7.07 kN/m3 Tube Outer Diameter 12.5 mmΔH 11 cm Standpipe Area 37.26 cm2

Gradient, i 0.79

Outflow h1 h2 h1 - h2 Inflow k(mL) (m:s) (s) (cm) (cm) (cm) (mL) (cm/s)

1 561 1:53.77 114 55.8 40.6 15.2 566 0.201 0.992 562 1:58.81 119 34.4 18.8 15.6 581 0.193 0.973 469 1:45.58 106 57.0 44.4 12.6 469 0.181 1.004 540 2:05.96 126 44.4 29.6 14.8 551 0.175 0.985 460 1:47.55 108 29.6 16.7 12.9 481 0.174 0.966 520 2:10.70 131 57.5 43.5 14.0 522 0.162 1.007 528 2:15.03 135 43.5 29.1 14.4 537 0.160 0.988 462 1:59.64 120 29.1 16.1 13.0 484 0.157 0.959 519 2:06.40 126 58.4 44.4 14.0 522 0.168 1.0010 519 2:08.58 129 44.4 30.3 14.1 525 0.164 0.9911 467 1:56.59 117 30.3 17.3 13.0 484 0.163 0.9612 540 2:20.34 140 57.5 43.0 14.5 540 0.157 1.0013 550 2:27.17 147 43.0 27.9 15.1 563 0.153 0.9814 436 1:56.67 117 27.9 15.8 12.1 451 0.152 0.9715 472 2:06.29 126 57.2 44.3 12.9 481 0.153 0.9816 503 2:18.02 138 44.3 30.6 13.7 510 0.149 0.9917 520 2:25.27 145 30.6 16.0 14.6 544 0.146 0.9618 480 2:16.24 136 58.8 45.8 13.0 484 0.144 0.9919 544 2:37.14 157 45.8 31.0 14.8 551 0.141 0.9920 560 2:44.01 164 31.0 15.4 15.6 581 0.139 0.9621 486 2:26.33 146 58.0 44.8 13.2 492 0.136 0.9922 542 2:45.23 165 44.8 30.0 14.8 551 0.134 0.9823 550 1:57.39 117 58.0 43.1 14.9 555 0.192 0.9924 548 2:01.05 121 43.1 28.1 15.0 559 0.185 0.9825 474 1:46.93 107 28.1 14.9 13.2 492 0.181 0.9626 497 2:06.52 127 58.6 45.2 13.4 499 0.160 1.0027 478 2:05.87 126 45.2 32.3 12.9 481 0.155 0.9928 500 2:13.39 133 32.3 18.4 13.9 518 0.153 0.9729 510 2:24.98 145 57.9 44.2 13.7 510 0.144 1.0030 502 2:25.11 145 44.2 30.3 13.9 518 0.141 0.9731 509 2:29.55 150 30.3 16.3 14.0 522 0.139 0.9832 432 2:11.15 131 57.7 46.0 11.7 436 0.135 0.9933 524 2:41.14 161 46.0 31.7 14.3 533 0.133 0.9834 579 2:59.02 179 31.7 15.6 16.1 600 0.132 0.9735 512 2:40.39 160 58.1 44.2 13.9 518 0.131 0.9936 520 2:46.33 166 44.2 30.0 14.2 529 0.128 0.9837 530 2:50.12 170 30.0 15.2 14.8 551 0.127 0.96

Outflow h1 h2 h1 - h2 Inflow k(mL) (m:s) (s) (cm) (cm) (cm) (mL) (cm/s)

38 562 3:00.12 180 58.0 42.9 15.1 563 0.127 1.0039 517 2:49.67 170 42.9 28.7 14.2 529 0.124 0.9840 528 2:54.64 175 28.7 14.1 14.6 544 0.123 0.9741 497 2:32.36 152 58.1 44.8 13.3 496 0.133 1.0042 500 2:44.28 164 44.8 31.2 13.6 507 0.124 0.99

Test Time Qout/Qin

Constant Head Permeability

Test Time Qout/Qin

0.00

0.05

0.10

0.15

0.20

0.25

0 5 10 15 20 25 30 35 40 45Test Number

Hy

dra

uli

c C

on

du

cti

vit

y (

cm

/s)

0.75

1.00

1.25

Qo

ut/

Qin

Hydraulic ConductivityQout/Qin

Sample: EC-199 Cell Diameter 63 mmDescription: Organoclay Sample Height 14 cmDate: 26 Mar 2008 Cell Area 31.17 cm2

Tested by: Jeremy Baugh Sample Volume 436.4 cm3

Weight of Dry Soil 369.9 g Standpipe Diameter 70 mmDry Unit Weight 8.31 kN/m3 Tube Outer Diameter 12.5 mmΔH 11 cm Standpipe Area 37.26 cm2

Gradient, i 0.79

Outflow h1 h2 h1 - h2 Inflow k(mL) (m:s) (s) (cm) (cm) (cm) (mL) (cm/s)

1 785 1:10.15 70 43.2 21.5 21.7 808 0.458 0.972 721 1:09.70 70 - 36.5 - - 0.421 -3 730 1:11.09 71 36.5 16.1 20.4 760 0.420 0.964 772 1:18.73 79 56.4 35.4 21.0 782 0.399 0.995 680 1:09.09 69 35.4 16.3 19.1 712 0.402 0.966 745 1:21.58 82 57.0 36.7 20.3 756 0.371 0.997 742 1:09.68 70 57.9 37.7 20.2 753 0.433 0.998 765 1:12.23 72 37.7 16.3 21.4 797 0.434 0.969 777 1:13.51 74 57.4 37.8 19.6 730 0.429 1.06

10 768 1:17.54 78 37.8 16.8 21.0 782 0.402 0.9811 760 1:20.27 80 57.6 37.0 20.6 768 0.388 0.9912 758 1:21.16 81 37.0 15.8 21.2 790 0.382 0.9613 740 1:21.27 81 57.7 37.4 20.3 756 0.373 0.9814 748 1:21.83 82 37.4 16.5 20.9 779 0.372 0.9615 794 1:23.34 83 57.7 36.1 21.6 805 0.391 0.9916 740 1:17.75 78 36.1 15.6 20.5 764 0.387 0.97

Constant Head Permeability

Test Time Qout/Qin

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0 2 4 6 8 10 12 14 16 18Test Number

Hy

dra

uli

c C

on

du

cti

vit

y

(cm

/s)

0.75

1.00

1.25Q

ou

t/Q

in

Hydraulic ConductivityQout/Qin

APPENDIX C – GEOTECHNICAL PROPERTIES

Sample ID: Test Date: 20 Mar 2008

Weight of Air Dry Sample = 1441.8 g Initials: JB

Sieve No.Sieve

OpeningWeight Retainedon Each Sieve

Percent Retainedon Each Sieve

CumulativePercent Retained

Percent Finer

(mm) (g) (%) (%) (%)2" 50.80 0.0 0.00 0.00 100.00

1 1/4" 31.50 0.0 0.00 0.00 100.001" 25.40 146.2 10.14 10.14 89.86

3/4" 19.10 77.4 5.37 15.51 84.491/2" 12.70 63.9 4.43 19.94 80.063/8" 9.51 66.7 4.63 24.57 75.43

4 4.75 120.8 8.38 32.95 67.0510 2.00 218.1 15.13 48.08 51.9220 0.850 344.9 23.93 72.01 27.9940 0.425 250.6 17.38 89.39 10.6160 0.250 104.5 7.25 96.64 3.36

100 0.150 15.7 1.09 97.73 2.27200 0.075 8.2 0.57 98.30 1.70Pan 24.5 1.70

Total Weight (g) = 1441.5

Geotechnics Laboratory

T2-B2 28.2-30.0

Mechanical Particle Size Analysis - ASTM D 422

University of Wisconsin-Madison

www.uwgeoengineering.org

0

10

20

30

40

50

60

70

80

90

100

0.010.1110100

Particle Size (mm)

Pe

rce

nt

Fin

er

(%)

Mechanical

Sedimentation

#4 #10 #20 #40 #60 #100 #200

Sample ID: Test Date: 20 Mar 2008

Weight of Air Dry Sample = 1405.4 g Initials: JB

Sieve No.Sieve

OpeningWeight Retainedon Each Sieve

Percent Retainedon Each Sieve

CumulativePercent Retained

Percent Finer

(mm) (g) (%) (%) (%)2" 50.80 0.0 0.00 0.00 100.00

1 1/4" 31.50 0.0 0.00 0.00 100.001" 25.40 100.6 7.16 7.16 92.84

3/4" 19.10 69.2 4.93 12.09 87.911/2" 12.70 109.0 7.76 19.85 80.153/8" 9.51 90.2 6.42 26.27 73.73

4 4.75 165.5 11.78 38.05 61.9510 2.00 164.2 11.69 49.74 50.2620 0.850 216.6 15.42 65.16 34.8440 0.425 282.2 20.09 85.26 14.7460 0.250 132.2 9.41 94.67 5.33

100 0.150 25.1 1.79 96.45 3.55200 0.075 13.8 0.98 97.44 2.56Pan 36.0 2.56

Total Weight (g) = 1404.6

Geotechnics Laboratory

T2-B3 28-30

Mechanical Particle Size Analysis - ASTM D 422

University of Wisconsin-Madison

www.uwgeoengineering.org

0

10

20

30

40

50

60

70

80

90

100

0.010.1110100

Particle Size (mm)

Perc

en

t F

iner

(%)

Mechanical

Sedimentation

#4 #10 #20 #40 #60 #100 #200

Sample ID: Test Date: 20 Mar 2008

Weight of Air Dry Sample = 946.8 g Initials: JB

Sieve No.Sieve

OpeningWeight Retainedon Each Sieve

Percent Retainedon Each Sieve

CumulativePercent Retained

Percent Finer

(mm) (g) (%) (%) (%)2" 50.80 0.0 0.00 0.00 100.00

1 1/4" 31.50 62.5 6.60 6.60 93.401" 25.40 40.8 4.31 10.91 89.09

3/4" 19.10 13.3 1.40 12.32 87.681/2" 12.70 29.6 3.13 15.44 84.563/8" 9.51 38.2 4.03 19.48 80.52

4 4.75 83.1 8.78 28.25 71.7510 2.00 148.8 15.72 43.97 56.0320 0.850 236.4 24.97 68.94 31.0640 0.425 197.3 20.84 89.78 10.2260 0.250 76.2 8.05 97.82 2.18

100 0.150 8.9 0.94 98.76 1.24200 0.075 3.6 0.38 99.14 0.86Pan 8.1 0.86

Total Weight (g) = 946.8

Geotechnics Laboratory

T2-B4 28.5-30.0

Mechanical Particle Size Analysis - ASTM D 422

University of Wisconsin-Madison

www.uwgeoengineering.org

0

10

20

30

40

50

60

70

80

90

100

0.010.1110100

Particle Size (mm)

Pe

rce

nt

Fin

er

(%)

Mechanical

Sedimentation

#4 #10 #20 #40 #60 #100 #200

Sample I.D. Test Date

193.1 g

200.0 cm3

0.97 g/cm3

126.00 g65.25 %

0.19 cm2

Left

Manometer

Reading

Right

Manometer

Reading

ReadingWater Expelled

from Soil

Sample

Suction

Grav.

Water

Content

Volumetric

Water

Content

(cm) (cm) (cm) (mL) (kPa) (%) (%)

222.4 222.4 3.5 0.0 0.000 65.3 63.0222.4 221.2 13.4 1.9 0.118 64.3 62.1223 220.5 15.3 2.2 0.245 64.1 61.9

224.7 218.6 19.9 3.1 0.598 63.6 61.4226.6 216.8 51.2 9.1 0.961 60.6 58.5228 215.6 133.7 24.7 1.216 52.4 50.6230 213.2 204 38.1 1.648 45.5 44.0230 213.2 3.5 38.1 1.648 45.5 44.0

231.6 212 216 78.5 1.923 24.6 23.8231.6 212 8 78.5 1.923 24.6 23.8236 207.5 90 94.1 2.795 16.5 16.0245 199 101 96.1 4.512 15.5 14.9268 176 110 97.9 9.024 14.6 14.1

77.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.577.0 0.000 25.4 24.5

StandPipe Area, a =

Volume, V =

Dry Unit Weight = Water WT =

Saturated Water Content =

PM-199

WT of Sample =

Large Scale Hanging Column Test On Sandy SoilASTM D 6836 - 02 (Method B)

0.001 63.000 63.0000 0.000 0.000

0.12 62.060 63.0000 -0.940 0.885

0.25 61.879 62.9998 -1.121 1.256

θr = 13.5029 0.60 61.442 62.9321 -1.490 2.220

θs = 63.0000 0.96 58.469 61.5544 -3.086 9.523

α = 0.6236 1.22 50.631 56.9954 -6.364 40.506

n = 6.5147 1.65 43.953 38.9589 4.994 24.936

m = 0.8465 1.65 43.953 38.9589 4.994 24.936

1.92 23.765 28.0217 -4.257 18.119

1.92 23.765 28.0217 -4.257 18.119

2.80 15.975 15.7623 0.213 0.045

4.51 14.930 13.6676 1.262 1.594

0.001 63.0000 9.02 14.075 13.5065 0.568 0.323

0.025 63.0000 Residual = 10.9585895

0.05 63.0000

0.075 63.0000 press plate data (FROM PAGE 2)

0.1 63.0000 water activity meter data (FROM PAGE 2)

0.25 62.9998

0.5 62.9789

0.6 62.9308

0.75 62.7055

0.85 62.3397

1 61.1473

1.25 56.0036

1.5 45.9491

2 25.7329

2.5 17.5901

3 15.0462

4 13.8226

5 13.5965

6 13.5372

7 13.5176

8 13.5099

9 13.5066

10 13.5050

15 13.5032

20 13.5030

30 13.5029

40 13.5029

50 13.5029

60 13.5029

70 13.5029

80 13.5029

90 13.5029

100 13.5029

500 13.5029

1000 13.5029

5000 13.5029

10000 13.5029

25000 13.5029

5.00E+04 13.5029

1.00E+05 13.5029

5.00E+05 13.5029

7.50E+05 13.5029

1.00E+06 13.5029

Fit van Genuchten Eqn to SWCC Data

FOR GRAPHING

Suction (kPa) VWC

FOR FITTING

(ΔWC)2ΔWC (%)Predicted

VWCApplied Suction

(kPa)Measured

VWC

van Genuchten Eqn

( )

m

nrs

r

1

1⎥⎦

⎤⎢⎣

⎡

αψ+=

θ−θθ−θ

=Θ

PM-199

0.001

0.01

0.1

1

10

100

0 10 20 30 40 50 60 70

Volumetric Water Content

Su

cti

on

(kP

a)

Fitted Data

Pressure Plate Test

Sample I.D. Test Date

187.7 g

200.0 cm3

0.94 g/cm3

127.00 g67.66 %

0.19 cm2

Left

Manometer

Reading

Right

Manometer

Reading

ReadingWater Expelled

from Soil

Sample

Suction

Grav.

Water

Content

Volumetric

Water

Content

(cm) (cm) (cm) (mL) (kPa) (%) (%)

209.5 209.5 1.7 0.0 0.000 67.7 63.5210 209.2 18.4 3.2 0.078 66.0 61.9

210.5 208.5 31 5.6 0.196 64.7 60.7211.8 207.4 72.7 13.5 0.432 60.5 56.8212.4 207 119 22.3 0.530 55.8 52.4213.8 205.4 173.5 32.6 0.824 50.3 47.2215.2 204 220 41.5 1.099 45.6 42.8215.2 204 14 41.5 1.099 45.6 42.8216.5 202.6 218 80.2 1.363 24.9 23.4216.5 202.6 14 80.2 1.363 24.9 23.4216.5 202.6 85.4 93.8 1.363 17.7 16.6220 199 98.6 96.3 2.060 16.4 15.3

225.5 193.7 108 98.1 3.119 15.4 14.5231 188.1 110 98.5 4.208 15.2 14.3249 170.3 115.5 99.5 7.719 14.6 13.7258 161 117 99.8 9.514 14.5 13.6

StandPipe Area, a =

Volume, V =

Dry Unit Weight = Water WT =

Saturated Water Content =

EC-199

WT of Sample =

Large Scale Hanging Column Test On Sandy SoilASTM D 6836 - 02 (Method B)

0.001 63.500 63.5000 0.000 0.000

0.08 61.914 63.4993 -1.586 2.515

0.20 60.717 63.4625 -2.746 7.541

θr = 12.6211 0.43 56.755 62.3355 -5.581 31.142

θs = 63.5000 0.53 52.357 60.7428 -8.386 70.330

α = 1.0461 0.82 47.179 49.4282 -2.249 5.059

n = 4.3916 1.10 42.762 35.3296 7.432 55.234

m = 0.7723 1.10 42.796 35.3296 7.466 55.742

1.36 23.382 25.7884 -2.407 5.793

1.36 23.369 25.7884 -2.420 5.855

1.36 16.599 25.7884 -9.190 84.454

2.06 15.345 16.2887 -0.944 0.892

0.001 63.5000 3.12 14.452 13.5387 0.913 0.833

0.015 63.5000 4.21 14.262 12.9545 1.307 1.708

0.025 63.5000 7.72 13.739 12.6637 1.075 1.156

0.035 63.5000 9.51 13.597 12.6421 0.954 0.911

0.05 63.4999 Residual = 20.57281551

0.075 63.4995

0.1 63.4981 press plate data (FROM PAGE 2)

0.125 63.4948 water activity meter data (FROM PAGE 2)

0.25 63.3915

0.3 63.2592

0.4 62.6597

0.5 61.3294

0.75 53.0995

0.85 48.0620

1 40.1126

1.25 29.2706

1.5 22.6083

2 16.6601

3 13.6675

4 13.0170

5 12.8070

6 12.7213

7 12.6805

8 12.6589

9 12.6464

10 12.6388

15 12.6256

20 12.6228

30 12.6215

40 12.6213

50 12.6212

60 12.6212

70 12.6211

80 12.6211

90 12.6211

100 12.6211

500 12.6211

1000 12.6211

5000 12.6211

10000 12.6211

25000 12.6211

5.00E+04 12.6211

1.00E+05 12.6211

5.00E+05 12.62117.50E+05 12.62111.00E+06 12.6211

MeasuredVWC

van Genuchten Eqn

Fit van Genuchten Eqn to SWCC Data

FOR GRAPHING

Suction (kPa) VWC

FOR FITTING

(ΔWC)2ΔWC (%)Predicted

VWCApplied Suction

(kPa)

( )

m

nrs

r

1

1⎥⎦

⎤⎢⎣

⎡

αψ+=

θ−θθ−θ

=Θ

EC-199

0.001

0.01

0.1

1

10

100

0 10 20 30 40 50 60 70

Volumetric Water Content

Su

cti

on

(kP

a)

Fitted Data

Pressure Plate Test

Sample: PM-199Description: OrganoclayDate: 5 Mar 2008Tested by: Jeremy BaughFlask volume: 500 mL

Weight of Flask W1 184.45 gWeight of Moist Soil 50.54 gWeight of Dry Soil W2 49.39 gWeight of Flask + Soil + Water W1 + W2 + W3 703.47 gTemperature T1 22.5 °CWeight of Flask + Water W1 + W4 682.27 gTemperature T2 23.5 °CWeight of Equal Volume of Water W4 - W3 28.19 gGs at Temperature W2 / (W4 - W3) 1.75Temperature Correction A 0.99945Gs at Temperature of 20 °C A Gs 1.75

Can #: MCGCan weight 31.04 gCan + Wet Soil 78.87 gCan + Dry Soil 77.78 gMoisture Content 2.33 %

Moisture Content of Soil

ASTM D 854

Specific Gravity

Sample: ET-1Description: OrganoclayDate: 6 Mar 2008Tested by: Jeremy BaughFlask volume: 500 mL

Weight of Flask W1 194.90 gWeight of Moist Soil 50.88 gWeight of Dry Soil W2 50.45 gWeight of Flask + Soil + Water W1 + W2 + W3 718.28 gTemperature T1 21.5 °CWeight of Flask + Water W1 + W4 693.03 gTemperature T2 23.5 °CWeight of Equal Volume of Water W4 - W3 25.20 gGs at Temperature W2 / (W4 - W3) 2.00Temperature Correction A 0.99968Gs at Temperature of 20 °C A Gs 2.00

Can #: H2Can weight 30.84 gCan + Wet Soil 75.56 gCan + Dry Soil 75.18 gMoisture Content 0.86 %

Specific Gravity

ASTM D 854

Moisture Content of Soil

Sample: EC-199Description: OrganoclayDate: 6 Mar 2008Tested by: Jeremy BaughFlask volume: 500 mL

Weight of Flask W1 184.45 gWeight of Moist Soil 51.32 gWeight of Dry Soil W2 50.09 gWeight of Flask + Soil + Water W1 + W2 + W3 703.82 gTemperature T1 21.0 °CWeight of Flask + Water W1 + W4 682.27 gTemperature T2 23.5 °CWeight of Equal Volume of Water W4 - W3 28.54 gGs at Temperature W2 / (W4 - W3) 1.76Temperature Correction A 0.99979Gs at Temperature of 20 °C A Gs 1.75

Can #: X2Can weight 30.76 gCan + Wet Soil 87.31 gCan + Dry Soil 85.95 gMoisture Content 2.46 %

Specific Gravity

ASTM D 854

Moisture Content of Soil

Jennifer ProtoPromega

Lab No. 5638Acct. No. 557320

May 15, 2008

Re: 3 Samples Submitted April 21, 2008

Results reported on an 'as received' basis. Unit: 1,000 ppb = ppm = mg/kg = mg/liter. 1% = 10,000ppm. The UW Soil and Plant Analysis Lab OA/QC protocol includes verifying results primarily basedon instrument performance, duplicate analysis and elemental recovery based on reference materials.Please contact the lab for details or additional requests.

Sample OC

ID %

EC-199 26.88PM 199 24.97ET-1 15.46

Phone: (608) 262-4364

Soil and Plant Analysis Lab8452 Mineral Point RoadVerona, WI 53593-8696 Fax: (608) 833-1277

APPENDIX D – DNAPL SPREADING CALCULATION

Assumptions

1) Cross section of DNAPL contacting the barrier is ellipse, and the initial

size of DNAPL ellipse on the barrier is approximately equal to the size of

DNAPL plume shown in Figure 27.

2) DNAPL mobility is 1.4 m/yr (CH2M HILL, 2007)

3) DNAPL can penetrate into the barrier to 0.3 m

4) DNAPL spreading occurs isotropically

Initial size of DNAPL plumes and initial length of open edge at the northern part

of barrier were obtained from ‘Conceptual Cross Section D-D’, Remedial

Investigation, Phase I – NAPL Site Characterization,

same as Figure 27, but to scale)

and properly scaled up:

Initial size of DNAPL at 575 ft: a = 39.85 m, and b = 0.42 m

Initial size of DNAPL at 565 ft; a = 26.72 m, and b = 1.41 m

Initial length of open edge at 575 ft = 63.13 m

Initial length of open edge at 565 ft = 76.56 m

The volume of DNAPL newly transported to the barrier (V) is equal to the

product of area increment ( A) and DNAPL penetration into the barrier (0.3 m).

V = initial area of DNAPL (a x b x ) x DNAPL mobility (1.4 m/yr) x time

elapsed (yr)

Barrier Boundary

DNAPL at 575

DNAPL at 565

a

a

b

b

r

r

r

r

A = {(a + r) x (b + r) x } – {a x b x }

V = A x 0.3 m

Thus, r is calculated by solving 2nd order equation with respect to r, which is

summarized in following Table.

Time elapsed (yr)

1 2 5 10 Elevation

(ft) V (m3) r (m) V (m3) r (m) V (m3) R (m) V (m3) R (m)

575 73.57 1.87 147.13 3.59 367.83 8.13 735.67 14.39

565 165.62 5.33 331.24 9.43 828.10 18.85 1656.2 30.30

The horizontal spreading of DNAPL (L) is equal to (2 x r), and the length of

edge at northern part of barrier (E) is equal to (initial length of edge – r), thus:

Time elapsed (yr)

1 2 5 10 Elevation

(ft) E (m) L (m) E (m) L (m) E (m) L (m) E (m) L (m)

575 61.26 83.43 59.54 86.87 55.00 95.95 48.74 108.47

565 71.26 64.04 67.13 72.30 57.71 91.14 46.26 114.04