ofr20191080.pdf - effective solubility assessment for ... · pounds (vocs), in particular...

Prepared in cooperation with the California Department of Toxic Substances Control

Effective Solubility Assessment for Organic Analytes in Liquid Samples, BKK Class I Landfill, West Covina, California, 2014–16

Open-File Report 2019–1080

U.S. Department of the InteriorU.S. Geological Survey

Cover. Photograph showing the BKK Class I Landfill in West Covina, California. Base map modified from Google, DigitalGlobe 2019.


By Michelle M. Lorah, Emily H. Majcher, and Carol J. Morel

Prepared in cooperation with the California Department of Toxic Substances Control


U.S. Department of the InteriorU.S. Geological Survey

U.S. Department of the InteriorDAVID BERNHARDT, Secretary

U.S. Geological SurveyJames F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2019

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Suggested citation:Lorah, M.M., Majcher, E.H., and Morel, C.J., 2019, Effective solubility assessment for organic analytes in liquid samples, BKK Class I Landfill, West Covina, California, 2014–16: U.S. Geological Survey Open-File Report 2019–1080, 18 p., https://doi.org/10.3133/ofr20191080.

ISSN 2331-1258 (online)

http://www.usgs.gov

http://store.usgs.gov

https://doi.org/10.3133/ofr20191080

iii

Acknowledgments

We would like to thank the California Department of Toxic Substances Control (DTSC) for their support of this project under the management of Bruce Lewis. We would also like to acknowledge logistical support, including initial data assembling and review, by Kleinfelder (San Diego, CA), under contract to DTSC, particularly Michael Foster (Kleinfelder, San Diego, CA) and Jim Finegan (Kleinfelder, Riverside, CA).

iv

ContentsAcknowledgments ........................................................................................................................................iiiExecutive Summary .......................................................................................................................................1Introduction.....................................................................................................................................................1

Background............................................................................................................................................2Methods and Data Analysis .........................................................................................................................3Mole Fractions in Landfill Liquid Samples .................................................................................................4Effective Solubilities in Landfill Liquid Samples .......................................................................................7References Cited..........................................................................................................................................17

Figures

1. Graphs showing mole fractions for cosolvent analytes in liquid in-waste andsub-waste samples ......................................................................................................................5

2. Graph showing mole fractions for cosolvent analytes in liquid landfill gas(LFG)-well samples collected in 2016 ........................................................................................6

3. Graph showing comparison of mole fractions and volume fractions for thecosolvents 1,4-dioxane and acetone in liquid in-waste, sub-waste, and landfill gas(LFG)-well samples reported in Draft Leachate Investigation Report table 4–8 ................7

4. Graphs showing mole fractions for selected analytes in liquid in-waste andsub-waste samples, excluding cosolvents ..............................................................................8

5. Graph showing mole fractions for selected analytes in landfill gas (LFG)-wellsamples collected in 2016, excluding cosolvents ...................................................................9

6. Graph showing effective solubility, as percent of the measured concentrations, inall liquid samples (in-waste, sub-waste, and landfill gas [LFG]) reported in DraftLeachate Investigation Report table 4–8 ................................................................................10

7. Graphs showing effective solubility, as percent of the measured concentrations,for selected analytes in in-waste and sub-waste samples .................................................12

8. Graphs showing effective solubility, as percent of the measured concentrations,of chlorinated ethanes in samples from the in-waste and sub-waste wells ....................13

9. Graphs showing effective solubility, as percent of the measured concentrations,of chlorinated ethenes in samples from the in-waste and sub-waste wells ....................14

10. Graphs showing effective solubility, as percent of the measured concentrations,of chlorinated benzenes in samples from the in-waste and sub-waste wells .................15

11. Graphs showing effective solubility, as percent of the measured concentrations,of benzene, toluene, ethylbenzene, and xylenes (BTEX) and naphthalene insamples from the in-waste and sub-waste wells .................................................................16

Tables

1. Concentrations, aqueous solubilities (Csat), and specific gravities of compoundsthat were considered possible cosolvents and excluded from the effectivesolubility calculations because of their high aqueous solubilities .......................................6

2. Compounds with percent effective solubility less than 1 or 10 percent in all wellsfrom Draft Leachate Investigation Report table 4–8 ...............................................................9

v

Conversion Factors

International System of Units to U.S. customary units

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)Volume

liter (L) 33.81402 ounce, fluid (fl. oz)liter (L) 2.113 pint (pt)liter (L) 1.057 quart (qt)liter (L) 0.2642 gallon (gal)liter (L) 61.02 cubic inch (in3)

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)kilogram (kg) 2.205 pound, avoirdupois (lb)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as

°F = (1.8 × °C) + 32.

Supplemental InformationConcentrations of chemical constituents in water are given in either milligrams per liter (mg/L), micrograms per liter (µg/L), moles per liter or molar (M), or micromoles per liter (µmol/L).

AbbreviationsBTEX benzene, toluene, ethylbenzene, and xylenes

DTSC California Department of Toxic Substances Control

DNAPL(s) dense non-aqueous phase liquid(s)

EPA U.S. Environmental Protection Agency

Landfill BKK Class I Landfill

LFG landfill gas

LNAPL(s) light non-aqueous phase liquid(s)

NAPL(s) non-aqueous phase liquids

PAHs polycyclic aromatic hydrocarbons

PCBs polychlorinated biphenyls

SVOC(s) semi-volatile organic compound(s)

USGS U.S. Geological Survey

VOC(s) volatile organic compound(s)


By Michelle M. Lorah, Emily H. Majcher, and Carol J. Morel

Executive SummaryThe U.S. Geological Survey assessed the effective solu-

bilities of organic analytes at the BKK Class I Landfill site, West Covina, California, in cooperation with the California Department of Toxic Substances Control, using available data for liquid samples collected within (in-waste) and below (sub-waste) the landfill in 2014–16. The primary purpose of the effective solubility calculations was to determine the likely presence or absence of dense non-aqueous phase liquids (DNAPLs), which is important for understanding the sources, persistence, and movement of the leachate contaminants. Percent effective solubility (a measure of the degree of devia-tion of a measured liquid concentration of a compound from the aqueous effective solubility) greater than 1 percent is the threshold that commonly has been used to infer the pres-ence of DNAPLs or mixed DNAPLs in aqueous monitoring results. In the present study, however, thresholds higher than 1 percent were used because of elevated temperatures and concentrations of cosolvents in the liquid samples—thresholds of 10 percent or 100 percent, respectively, were used for liquid and solid (at 25 degrees Celsius) organic compounds for potential non-aqueous phase liquid presence.

Overall, the effective solubility calculations indicate the likely presence of DNAPLs or mixed DNAPLs in some samples for a range of compounds, including tetrachloroethene, trichloroethene, 1,1-dichloroethene, vinyl chloride, 1,2,4-trichlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, naphthalene, toluene, ethylbenzene, and xylenes. Samples with the highest calculated percent effec-tive solubilities for chlorinated ethenes, ethanes, and benzenes were from a location where liquid in the waste prism is known to be in contact with the groundwater beneath the landfill. Trends in the effective solubilities for the chlorinated ethenes and ethanes were generally consistent between the in-waste and sub-waste samples, supporting a similar source composi-tion for these liquids. Percent effective solubilities were less than 10 for the chlorinated ethanes in all the in-waste and sub-waste samples, indicating that DNAPL of these compounds is not present. Percent effective solubilities of chlorinated benzenes, ethylbenzene, and xylenes exceeded the 10-percent

effective solubility threshold in more of the sub-waste samples than the in-waste liquid samples. Volatilization also may influ-ence the patterns in the calculated effective solubilities but were not included in this study.

IntroductionLandfill leachates that can contain nutrients, metals,

and organic compounds are a major concern for groundwater and surface-water contamination nationwide (Cozzarelli and others, 2011; Masoner and others, 2014). Class I landfills, which received hazardous chemical wastes as well as non-hazardous wastes, can include a particularly wide range of inorganic and organic compounds (Pavelka and others, 1993); an understanding of the effect of these compound mixtures on the mobility of individual contaminants is needed to assess potential effects on water resources and leachate treatment methods. The U.S. Geological Survey (USGS) assessed the effective solubilities of organic analytes at the BKK Class I Landfill site, referred to as the Landfill, in cooperation with the California Department of Toxic Substances Control (DTSC) to provide an understanding of the effects of leach-ate chemistry (as reported in the Draft Leachate Investigation Report [Geosyntec, written commun., 2017]) on the chemical solubility of individual chemicals. Specifically, DTSC wanted the review of leachate chemistry data and solubility effects to focus on (1) analysis of chlorinated volatile organic com-pounds (VOCs), in particular 1,4-dioxane, vinyl chloride, and trichloroethene; (2) comparative assessment of representative metals and semi-volatile organic compounds (SVOCs), such as naphthalene; and (3) comparative assessment of the chemi-cal composition of liquid samples collected within (in-waste) and below (sub-waste) the landfill. Although a review of met-als data, as well as organic analytes, was requested by DTSC in relation to leachate chemistry effects on solubilities, this report only assesses the organic chemical data. Metal solubil-ity is greatly affected by pH and redox chemistry, for which little or no data are available in the Draft Leachate Investiga-tion Report (Geosyntec, written commun., 2017).

2 Effective Solubility Assessment for Organic Analytes in Liquid Samples, BKK Class I Landfill

The primary purpose of assessing the effective solubilities of organic contaminants at the site was to determine the likely presence or absence of non-aqueous phase liquids (NAPLs), which is important for understanding the sources, persis-tence, and movement of the leachate contaminants within and between the in-waste and sub-waste liquids and the migration to deeper groundwater. Low-solubility organic contaminants that have densities greater than water, such as chlorinated sol-vents, coal tar (a complex mix of oils and polycyclic aromatic hydrocarbons, or PAHs), and polychlorinated biphenyls (PCBs), can exist as DNAPLs (dense non-aqueous phase liquids). Organic contaminants such as benzene, toluene, ethylbenzene, and xylenes (BTEX) that have densities lighter than water in their pure phase can exist as LNAPLs (light non-aqueous phase liquids). Mixed DNAPLs that contain compounds normally associated with LNAPLs (along with typical DNAPLs) also may be found, especially at industrial disposal sites such as the Landfill, where blending and mixing of a wide variety of organic compounds may have occurred (Kueper and Davies, 2009). In mixed DNAPLs, DNAPL com-pounds may partition into LNAPL fractions.

Although the presence of LNAPLs has been observed in the Landfill leachate drilling locations, the presence of DNAPL or mixed DNAPLs was considered unlikely based on measured concentrations below the aqueous solubility thresh-old of 1 percent that is commonly used as a “rule of thumb” to screen for the potential presence of DNAPL, as described in the Draft Leachate Investigation Report (Geosyntec, written commun., 2017). The 1-percent threshold has been used to infer the presence of DNAPLs in aqueous monitoring results where limited or no data are available from direct testing for the presence of DNAPLs through soil or water analyses meth-ods, such as hydrophobic dyes (U.S. Environmental Protec-tion Agency, 2004a; Kueper and Davies, 2009). However, the 1-percent threshold for considering groundwater concentra-tions indicative of NAPL presence refers to effective solubili-ties rather than aqueous solubilities, when the NAPL may contain more than one compound (Kueper and Davies, 2009).

Given the large number of organic contaminants mea-sured in liquid samples collected at the Landfill, effective solubilities need to be considered to empirically assess the potential presence of DNAPL. DNAPL can be present in municipal or combined use landfills and potentially pose a risk to underlying groundwater, particularly in unlined landfills such as the Landfill (U.S. Environmental Protection Agency, 2004a, b). In this report, the effective solubilities of the organic contaminants at the Landfill were estimated, and the results of these calculations in relation to the potential presence or absence of NAPLs within or below the Landfill waste are presented. It should be noted that this empirical method cannot distinguish the form in which DNAPLs may occur (residual DNAPL or DNAPL pools), and the form of the DNAPL would affect its mobility and dissolution rates (Essaid and others, 2015). These calculations can address one of the objectives developed by the California DTSC for leachate investigations at the Landfill—assess the presence and vertical

depth of DNAPLs released from the Landfill into the underly-ing native soils and bedrock. The effective solubilities also are used to compare the similarities and differences in the chemi-cal composition of the liquids within and below the waste. The data used in this report are provided in the supplemental information (https://doi.org/10.3133/ofr20191080).

Background

The aqueous solubility of a compound is defined as the equilibrium, or saturation concentration (Csat), of the organic compound liquid or solid in the aqueous phase, denoting the maximum concentration of a given chemical that can be dis-solved in pure water at a given temperature and pressure. The equilibrium solubility in water of an individual compound in a multi-component NAPL is referred to as the compound’s effective solubility. Because the various compounds in a multi-component NAPL can suppress each other’s individual aque-ous solubility, effective solubilities typically are lower than the reported aqueous solubilities for the individual compounds (Kueper and Davies, 2009).

The solubility of a compound is affected by its molecular structure and physical and chemical properties of the aque-ous solution. Temperature is the most important physical property to consider. Measured aqueous solubilities reported in the literature typically are for solutions at 20 or 25 degrees Celsius (°C), whereas liquid temperatures from the Landfill piezometers were as high as 50 °C (Geosyntec, written com-mun., 2017). Note that the Draft Leachate Investigation Report that contains these data will be available, when finalized, on a DTSC website (https://www.envirostor.dtsc.ca.gov/public/profile_report?global_id=19490005).

In general, for low molecular weight organic compounds that are a liquid at room temperature, such as chloroform, the solubility changes less than 20 percent with a 30 °C tempera-ture change (Schwarzenbach and others, 2003, chapter 5). The temperature effect becomes more important for compounds that are a gas or a solid at room temperature such as vinyl chloride or dibenzofuran. Within the temperature range of 25 to 50 °C measured at the Landfill, the solubility of a gas in water would decrease as temperature increases, whereas the solubility of a solid would increase. Examples from reported experimental data indicate that these temperature effects for gases and solids are between a factor of 2 to 2.5 change in solubility from the 25 °C values (Schwarzenbach and others, 2003, chapter 5).

Important chemical properties to consider include pH, ionic strength (dissolved salts), and the chemical com-position of the water (leachate, in this case), especially the concentration of cosolvents (Schwarzenbach and oth-ers, 2003). The effect of pH on the deviation of saturation concentrations from the compound’s reported aqueous solubility will be most important in acidic or basic water, as the reported values are measured in pure water with a neutral pH. The Draft Leachate Investigation Report (Geosyntec, written commun., 2017) gives near-neutral pH


https://www.envirostor.dtsc.ca.gov/public/profile_report?global_id=19490005


Methods and Data Analysis 3

values for sediment samples (pH 6.7–8.1; median 7.6) and for most liquid samples measured during well development (pH 4.58–6.93; median 6.52). Only 2 of the 13 wells had reported pH values below 6.4 during well development. Based on the measured near-neutral pH values, pH is not expected to be an important factor affecting solubility calculations for the Landfill. Ionic strength effects on aqueous solubilities generally are less than a factor of 1.5 to 3 at the moderate salt concentrations found in seawater (Schwarzenbach and others, 2003, chapter 5), which has an ionic strength of approximately 0.7 molar (M) (Davis and Masten, 2013). Although complete inorganic compositions of the liquid samples collected at the Landfill are unknown, the ionic strength of liquids in mature landfills (greater than 10 years old), such as the BKK Class I Landfill, is typically about 0.05 M (Davis and Masten, 2013). Thus, ionic strength effects are likely minor compared to pos-sible temperature and cosolvent effects.

Cosolvents include any highly water-miscible organic solvents that can change the solvation properties of the aque-ous phase. Completely water-miscible organic solvents include acetone and 1,4-dioxane, which are prevalent at the Landfill, and these solvents have been mostly studied for their solubil-ity effect on low-solubility organic solids, including PAHs and PCBs (Schwarzenbach and others, 2003). Limited data are available on the aqueous solubility effect of completely water-miscible solvents on liquid organic compounds or on the solubility effect of partially miscible organic solvents, such as n-alcohols (n greater than 3) and ethers. Schwarzenbach and others (2003) presented data that indicated the solubility effect of highly miscible organic solvents on other compounds exceeded a factor of 2 only when the cosolvent volume frac-tions were greater than 5 to 10 percent in the aqueous solu-tion. The solubility effect can then increase exponentially with increasing volume fractions of cosolvents. For example, the cosolvents 1,4-dioxane and acetone increased the solubil-ity of naphthalene (a solid) by a factor of 3 if 20 percent (by volume) of the solvent was present in water and by a factor of about 30 to 40 if 40 percent of the solvent was present in water (Schwarzenbach and others, 2003, table 5.8). The cosolvent solubility effect on organic contaminants that are liquids, such as trichloroethene or 1,2-dichloroethane, would be lower than the effect for solid contaminants.

Methods and Data AnalysisVOC and SVOC analytical results were obtained from

the Draft Leachate Investigation Report tables 4–8 and 4–9 (Geosyntec, written commun., 2017). The data include chemi-cal composition of the leachate liquids from 10 in-waste piezometers, 8 sub-waste piezometers, and 8 landfill gas (LFG) wells sampled in 2014–16 and 28 LFG wells sampled earlier in 2014 (Geosyntec, written commun., 2017, tables 4–8 and 4–9). In-waste piezometers have a 10-foot (ft) screened interval placed approximately 5 ft above the base of the

waste, and the sub-waste piezometers have a 5-ft screened interval placed in the native material directly underlying the Landfill. In contrast, the LFG wells, which are connected to an extraction system to manage landfill gas and liquid accu-mulation, intersect a large part of the waste with screened intervals from 40 to more than 100 ft long. The data uti-lized for calculations reported here include 59 sets of liquid samples and additional duplicates that were collected from these three well types during the Phase I and II investiga-tion (Geosyntec, written commun., 2017). Sampling methods and locations of the Phase II investigation are detailed in workplans (Geosyntec, 2013, 2015) that are available on a DTSC website (https://www.envirostor.dtsc.ca.gov/public/profile_report?global_id=19490005).

Literature values of the aqueous solubility and molecu-lar weights were tabulated for all analytes (Howard, 1989; Montgomery, 1991; Montgomery and Welkom, 1990; National Institutes of Health, 2018; U.S. Environmental Protection Agency, 2018). VOC and SVOC concentrations were con-verted to micromolar concentrations, and the mole fraction of each compound detected in a given sample was calculated. The accompanying spreadsheet provided as supplemental information (https://doi.org/10.3133/ofr20191080) shows the tabulated aqueous solubility and molecular weight values (table SI-1) and the mole fraction and effective solubility calculations (tables SI-2 to SI-9). Because the fractions of the compounds disposed of as NAPL in the waste are unknown, an effective solubility for each sample was calculated assum-ing the molar fractions of compounds in the liquid samples were representative of the possible NAPL molar fractions. The effective solubility for a compound is calculated from Raoult’s Law (Kueper and Davies, 2009):

Ceff = m × Csat (1)

where Ceff is the effective solubility (micromoles per

liter, µmol/L) of a compound;m is the unitless mole fraction of a compound in

the liquid sample; and Csat is the aqueous solubility of the compound

(µmol/L) at 25 °C from the literature.The degree of deviation of the measured liquid concen-

tration from the aqueous effective solubility, % Ceff , was then calculated as:

% Ceff = Cmeas / Ceff × 100 (2)

where Cmeas is the measured concentration (µmol/L) of the

compound.Generally, % Ceff greater than 1 percent is regarded as

likely NAPL contact or presence in groundwater (Kueper and Davies, 2009). These calculations (1) assume ideal partition-ing behavior between the NAPL and water, (2) do not account for possible changes in the NAPL composition over time, and





(3) do not consider the effect of cosolvents. Because of theelevated temperatures and the presence of cosolvents in theLandfill liquid samples (see Mole Fractions in Landfill LiquidSamples section), an additional margin of error was appliedto the calculation and greater than 10 percent or 100 percent(one to two orders of magnitude), respectively, were usedfor liquid and solid organic compounds as the threshold forpotential NAPL presence in the Landfill setting. The higherthreshold of 100 percent was used for the compounds that aresolid at 25ºC because of the higher cosolvent and temperatureeffects on the solubility of these organic contaminants. In addi-tion, the assumption that the molar fractions of compoundsin the liquid samples are representative of the possible NAPLmolar fractions does not account for loss to a vapor phase. Ifaqueous samples are from vented wells that may have beenaffected by landfill gas removal, known gas phase concentra-tions could be used to adjust to the aqueous concentrationsusing Henry’s Law (Kueper and Davies, 2009). The effectivesolubility calculations presented here do not incorporate gasphase concentrations.

Some compounds, including 1,4-dioxane and naphthalene, were analyzed both by VOC and SVOC methods and appeared twice in tabulated data in the Draft Leachate Investigation Report (Geosyntec, written commun., 2017); a comparison of concentrations showed that the two analyti-cal methods gave similar concentrations, however, the VOC results were typically higher than the SVOC results. The VOC results were used for all overlapping analytes in the assessment of effective solubilities.

Mole Fractions in Landfill Liquid Samples

Calculations of mole fractions in the samples were ini-tially performed with the complete organic analytes included in tables 4–8 and 4–9 in the Draft Leachate Investigation Report (Geosyntec, written commun., 2017) to determine the mole fractions of cosolvents in each sample (tables SI-3 and SI-9). Compounds with aqueous solubilities greater than 100,000 micromoles per liter (µmol/L) were considered as possible cosolvents, but some cosolvent compounds that had very low concentrations (table 1) were not included in the figures showing cosolvent importance in the samples (figs. 1 and 2). Of the 10 cosolvents that had high concentrations in the liquid samples, acetone and 1,4-dioxane had the highest aqueous solubilities by a factor of about 3 or more (table 1). The 10 cosolvents considered important (table 1), except ben-zyl alcohol, were noted as part of a group of 14 compounds that had average concentrations greater than 1,000 micro-grams per liter (µg/L) in liquid samples across the Landfill (Geosyntec, written commun., 2017). In general, 1,4-dioxane and (or) acetone (the most soluble of the cosolvents with high concentrations) were the most prevalent and had the highest

mole fractions in the in-waste, sub-waste, and LFG-well liquid samples (figs. 1 and 2).

Most in-waste samples had total mole fractions of cosolvents greater than 0.50 (50 percent by mass; fig. 1). Note that samples from many piezometers were collected on different dates, which is indicated in the last segment of the sample name (fig. 1); samples are referred to throughout this report simply by the piezometer name to include samples taken on different dates. Although two in-waste samples from TP940-3A (TP940-3A-01222015 and DUP-01222015 (TP940-3A) in fig. 1A) had relatively low total mole fractions of 0.35 and 0.48, another sample (DUP-01212015 (TP940-3A) in fig. 1A) had a cosolvent total mole fraction of 0.98, pos-sibly indicating a sample collection issue. Similarly, the sub-waste well samples had total mole fractions of cosolvents greater than 0.50, except that some, but not all, samples from TP740-2BR and TP940-4B had low total cosolvent mole frac-tions between 0.13 and 0.30 (fig. 1B). All except one of the samples from the LFG wells sampled in 2014 (table SI-9) and all of the 2016 LFG wells (fig. 2) had total mole fractions of cosolvents of 0.60 or higher, which was consistently higher than the in-waste or sub-waste cosolvent mole fractions. It is likely that the liquid in the longer-screened LFG wells is more affected by vapor losses than the in-waste or sub-waste sam-ples, resulting in a bias toward the highly soluble cosolvent compounds in the LFG samples. The longer screens (greater than 40 to 100 ft) in the LFG wells also may result in a bias toward the cosolvent compounds if these compounds are more widely distributed.

Assuming the mole fractions are equivalent to vol-ume fractions (density=1), cosolvent effects on the effective solubility calculations are likely significant for all samples except the one sample from sub-waste well TP940-4B that had a total mole fraction of cosolvents of about 10 percent (TP940-4B-09012016 in fig. 1B) (Schwarzenbach and oth-ers, 2003). Because the principles of cosolvent effects on the solubility of organic compounds consider the volume fraction of cosolvents in a sample (see Background section) rather than the mole fraction, the specific gravity of the cosolvent compounds (table 1) was used to calculate volume fractions of these compounds in the samples to verify this assumption (table SI-10). The calculated mole and volume fractions of the two most prevalent, high concentration cosolvents, acetone and 1,4-dioxane, are compared in figure 3. The mole and volume fractions showed a nearly 1:1 relation, supporting the validity of the use of mole fractions in this study to evaluate possible cosolvent effects. As observed for the results of mole fraction of cosolvents, only one sample from sub-waste well TP940-4B had a total volume fraction of cosolvents of slightly less than 10 percent; thus, cosolvent effects on the solubil-ity of other organic compounds could be considered minimal in this one sample (Schwarzenbach and others, 2003). All other samples had a greater than 10-percent volume fraction of cosolvents, and most samples had greater than 30 percent cosolvents by volume.

Mole Fractions in Landfill Liquid Samples 5

0.900.80

1.00

0.700.600.500.400.300.200.100.00

Mol

e fra

ctio

n

TP725-1

A-1209

15

TP725-1

A-0503

2016

TP740-1

A-0810

2016

TP740-1

A-0825

2016

TP740-2

A-1112

2015

TP740-2

A-0826

2016

TP740-2

AD-0826

2016

TP740-2

A-0907

2016

TP850-1

A-0830

2016

TP940-1

A-0123

2015

TP940-1

A-0901

2016

TP940-3

A-0121

2015

TP940-3

A-0122

2015

DUP-0121

2015

(TP94

0-3A)

DUP-0122

2015

(TP94

0-3A)

TP940-4

A-1210

2014

TP940-4

A-0901

2016

TP940-5

A-1209

15

TP940-5

A-0829

2016

TP940-6

A-0310

2016

TP940-6

AD-0310

2016

TP940-6

A-0615

2016

TP940-7

A-0830

2016

Sample number

A. In-waste samples

0.90

0.80

1.00

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0.00

Mol

e fra

ctio

n

TP725-1

B-0825

2016

TP725-1

B-0906

2016

TP740-2

BR-1112

2015

TP740-2

BR-0503

2016

TP740-2

BRD-0503

2016

TP740-2

BR-0826

2016

TP740-2

BR-0906

2016

TP740-2

BRD-0906

2016

TP940-1

B-1209

2014

TP940-1

B-0901

2016

TP940-1

B-0908

2016

TP940-2

B-AQ-90

TP940-2

B-AQ-10

0

TP940-2

B-AQ-12

0

TP940-2

B-AQ-13

0

TP940-3

B-0122

2015

TP940-3

B-0831

2016

TP940-4

B-1210

2014

TP940-4

B-0901

2016

TP940-4

B-0907

2016

TP940-5

B-0829

2016

TP940-5

B-0907

2016

TP940-6

B-0310

2016

TP940-6

B-0615

2016

TP940-6

B-0829

2016

TP940-6

B-0906

2016

TP940-7

B-0830

2016

Sample number

B. Sub-waste samples

1,4-Dioxane

4-Methyl-2-pentanone (MIBK)

2-Butanone (MEK)

Phenol

2-Methylphenol

Acetone

tert-Butyl alcohol (2-methyl-2-propanol)

3 & 4 Methylphenol

Benzyl alcohol

Isobutyl alcohol

EXPLANATION

Figure 1. Mole fractions for cosolvent analytes in liquid in-waste and sub-waste samples. (Calculated using all organic analytes in Draft Leachate Investigation Report table 4–8 [Geosyntec, written commun., 2017].)

The high solubility of the cosolvent compounds (table 1) likely indicates that they would be an insignificant com-ponent of any NAPL, even mixed DNAPL, present at the site. Therefore, mole fractions of the organic analytes in the samples were recalculated excluding the cosolvent compounds for determination of effective solubilities and evaluation of NAPL presence (table SI-5). The recalculated mole frac-tions for selected compounds that were noted by DTSC as those of interest, including chlorinated solvents (chlorinated ethanes, chlorinated ethenes, and chlorinated benzenes) and naphthalene, are shown in figures 4 and 5. BTEX compounds also are included in these figures and subsequent figures show-ing effective solubility results because of the reported presence

of aromatic compounds in LNAPL at the site. For the chlo-rinated solvents, compounds such as 1,2-cis-dichloroethene, vinyl chloride, and 1,2-dichloroethane, that could be degrada-tion products of the higher chlorinated compounds, as well as having a direct disposal source, were included. The relative prevalence and mole fractions of the selected compounds are variable among the in-waste and sub-waste samples, although they share characteristic compounds (fig. 4). Vinyl chloride, chlorobenzene, and BTEX were prevalent in the in-waste and sub-waste samples, with mole fractions of each com-pound greater than 5 percent in many samples and as high as 50 percent (fig. 4). In addition, cis-1,2-dichlorothene had a rel-atively high mole fraction, especially in the in-waste samples,


0.90

0.80

1.00

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0.00

Mol

e fra

ctio

n

DW-4D-07

1120

16

DW-4D-08

0820

16

DW-7S-07

1220

16

DW-7S-08

0920

16

TD-2-07

1220

16

TD-2-08

0920

16

TF-1-07

1120

16

TF-1-08

0820

16

W66

0-DW-07

1320

16

W66

0-DW-08

0920

16

W74

0-14-0

8102

016

W74

0-14-0

8252

016

WE-03

R-0825

2016

WE-03

R-0908

2016

WSH-01

-0712

2016

WSH-01

-0809

2016

Sample number

1,4-Dioxane

4-Methyl-2-pentanone (MIBK)

2-Butanone (MEK)

Phenol

2-Methylphenol

Acetone

tert-Butyl alcohol (2-methyl-2-propanol)

3 & 4 Methylphenol

Benzyl alcohol

Isobutyl alcohol

EXPLANATION

Figure 2. Mole fractions for cosolvent analytes in liquid landfill gas (LFG)-well samples collected in 2016. (Calculated using all organic analytes in Draft Leachate Investigation Report table 4–8 [Geosyntec, written commun., 2017].)

Table 1. Concentrations, aqueous solubilities (Csat), and specific gravities of compounds that were considered possible cosolvents and excluded from the effective solubility calculations because of their high aqueous solubilities.

[“High concentration” cosolvents that resulted in mole fractions of greater than 0.015 in the samples were used in initial calculations of mole fractions to quantify their importance relative to those compounds possibly present in non-aqueous phase liquid; these compounds are included in figures 1 and 2. “Low concentration” cosolvents were detected at very low concentrations that resulted in mole fractions of less than 0.015; these compounds are excluded from figures 1 and 2 that show cosolvent importance in the samples. Median, mean, and maximum concentrations of cosolvent compounds reported in table 4–8 in the Draft Leachate Investigation Report (Geosyntec, written commun., 2017) are shown in micrograms per liter (µg/L); the maximum concentration was used to calculate the maximum percent solubility in each liquid sample. µmol/L, micromoles per liter; n, number of samples; g/mL, grams per milliliter; --, no data]

CosolventCsat

(µmol/L)Csat

(µg/L)

Number of detections

(n=66)

Median (µg/L)

Mean (µg/L)

Maximum (µg/L)

Maximum percent

solubility

Specific gravity (g/mL)

High concentration cosolvents4-Methyl-2-pentanone (MIBK) 1.90E+05 1.90E+07 41 820 2,044 13,000 6.8E−02 0.8023 & 4 Methylphenol 2.13E+05 2.30E+07 45 700 13,809 120,000 5.2E−01 1.0342-Methylphenol 2.31E+05 2.50E+07 24 330 10,041 100,000 4.0E−01 1.047Benzyl alcohol 3.97E+05 4.29E+07 19 32.0 610 3,800 8.9E−03 1.045Phenol 9.24E+05 8.70E+07 31 4,300 16,315 140,000 1.6E−01 1.072Isobutyl alcohol 1.15E+06 8.50E+07 4 1,600 1,478 2,600 3.1E−03 0.8022-Butanone (MEK) 3.09E+06 2.23E+08 39 9,100 16,749 97,000 4.3E−02 0.805tert-Butyl alcohol 4.27E+06 3.16E+08 53 1,200 1,318 4,800 1.5E−03 0.7891,4-Dioxane 1.14E+07 1.00E+09 61 8,700 13,881 56,000 5.6E−03 1.034Acetone 1.72E+07 1.00E+09 55 500 26,029 220,000 2.2E−02 0.785

Low concentration cosolventsBis(2-chloroisopropyl)ether 1.01E+05 1.72E+07 1 -- -- 14.0 8.1E−05 1.1034-Nitrophenol 1.80E+05 2.50E+07 1 -- -- 17.0 6.8E−05 1.479Methylene Chloride 1.97E+05 1.67E+07 10 96.0 365 2,500 1.5E−02 1.3222-Hexanone 3.49E+05 3.50E+07 15 570 819 2,000 5.7E−03 0.830Aniline 3.87E+05 3.61E+07 1 -- -- 29.0 8.0E−05 1.022Methyl tert-butyl ether 5.79E+05 5.10E+07 10 0.97 1.06 2.70 5.3E−06 0.7352-Picoline 1.07E+07 1.00E+09 1 6.50 6.50 6.50 6.5E−07 0.943Acetonitrile 2.44E+07 1.00E+09 8 138 351 1,000 1.0E−04 0.783

Effective Solubilities in Landfill Liquid Samples 7

0.000

0.200

0.400

0.600

0.800

1.000

Volu

me

fract

ion

0.000 0.200 0.400 0.600 0.800 1.000

Mole fraction

EXPLANATION

1,4-Dioxane

Acetone

Figure 3. Comparison of mole fractions and volume fractions for the cosolvents 1,4-dioxane and acetone in liquid in-waste, sub-waste, and landfill gas (LFG)-well samples reported in Draft Leachate Investigation Report table 4–8 (Geosyntec, written commun., 2017).

and was the predominant compound on a mole fraction basis in samples from TP740-1A. Many of the sub-waste samples, however, had distinctly higher mole fractions of the chlori-nated ethanes 1,1,2-trichloroethane, 1,1-dichloroethane, and 1,2-dichloroethane (greater than about 15 percent for one or more chlorinated ethanes) than was observed in the in-waste samples (less than 1 percent) (fig. 4). Mole fraction domi-nance of these chlorinated ethanes is the primary difference between some of the sub-waste and in-waste samples. This conclusion, based on mole fractions with cosolvents excluded, differs partly from the chemical characterization conclusion in the Draft Leachate Investigation Report (Geosyntec, written commun., 2017, p. 99) that the sub-waste liquid generally has a higher concentration of both chlorinated ethanes and ethenes than the in-waste liquid.

The LFG-well liquid samples from 2016 (fig. 5) generally had markedly lower mole fractions of the compounds of inter-est than those observed in the in-waste and sub-waste samples (fig. 4). Total mole fractions of the compounds of interest were less than 40 percent in all except four of the LFG-well liquid samples (fig. 5), whereas most in-waste and sub-waste samples had total mole fractions greater than 40 percent with cosolvents excluded (fig. 4). BTEX compounds were predomi-nant and accounted for the highest total mole fractions in the LFG well samples. Vinyl chloride also was prevalent in the LFG well samples, but at lower mole fractions than observed in the in-waste and sub-waste samples. Other compounds, excluding cosolvents, that did have high mole fractions in the LFG-well liquid samples included benzoic acid in samples from DW-4D (0.57 to 0.64 mole fraction) and tetrahydrofuran in samples from DW-7S, W660-DW, W740-14, WE-03R, and

WSH-01 (0.58 to 0.87 mole fraction) (table SI-6). As noted when discussing the higher mole fraction of cosolvents in the LFG-well samples, these wells have longer screened intervals and may be affected more by volatilization and landfill gas removal than the samples from the in-waste and sub-waste piezometers. Thus, effective solubility calculations largely focused on the in-waste and sub-waste piezometer samples because the LFG-well samples may not be representative of liquid chemistry in the landfill without accounting for gas phase concentrations.

Effective Solubilities in Landfill Liquid Samples

The “percent effective solubilities,” which indicate the percent deviation of measured concentrations from the calculated effective solubilities (eq. 2), were calculated for the broad suite of compounds included in the volatile and semi-volatile analyses (excluding the cosolvents) (table SI-5). This group of compounds was used because mixed DNAPLs could be present at the site that might include compounds typically considered to be a LNAPL, such as benzene. Because of the added uncertainties from the elevated water temperatures and cosolvent presence, a percent effective solubility greater than 10 percent was considered as a reasonable threshold for indi-cating a likely NAPL presence for most compounds. However, a threshold of 100 percent was considered for compounds with very low aqueous solubilities (less than 250 µmol/L) that would show the greatest cosolvent and temperature effects, such as the PAHs like naphthalene (fig. 6). Thresholds lower than 10 percent or 100 percent could be used for the sample from TP940-4B-09012016 that had a low cosolvent mole fraction of about 10 percent, but another sample from the same sampling data had a higher cosolvent mole fraction.

The percent effective solubilities varied widely among the compounds considered but were within a range of 0.01 to 1,000 percent for most samples (fig. 6). The least soluble compounds had the highest percent effective solubili-ties (greater than 1,000 percent) and may be present in the unfiltered liquid samples as particulates or sorbed to particu-lates. Out of the 82 compounds included in the calculations, 32 compounds had percent effective solubilities of less than or equal to 10 in all samples (table 2). The compounds of spe-cific interest to DTSC that had less than 10 percent effective solubilities include 1,1,2-trichloroethane, 1,1-dichloroethane, 1,2-dichloroethane, and cis-1,2-dichloroethene. However, NAPLs with a wide mix of other compounds also are poten-tially present at the site.

The percent effective solubilities of chlorinated sol-vents, BTEX, and naphthalene, that are of specific interest, are shown in figure 7 for the in-waste and sub-waste samples. The in-waste and sub-waste samples showed similar patterns and ranges of percent effective solubilities for the selected compounds, although sub-waste samples from well TP940-6B


0.80

1.00

0.60

0.40

0.20

0.00

Mol

e fra

ctio

n

TP725-1

A-1209

15

TP725-1

A-0503

2016

TP740-1

A-0810

2016

TP740-1

A-0825

2016

TP740-2

A-1112

2015

TP740-2

A-0826

2016

TP740-2

AD-0826

2016

TP740-2

A-0907

2016

TP850-1

A-0830

2016

TP940-1

A-0123

2015

TP940-1

A-0901

2016

TP940-3

A-0121

2015

TP940-3

A-0122

2015

DUP-0121

2015

(TP94

0-3A)

DUP-0122

2015

(TP94

0-3A)

TP940-4

A-1210

2014

TP940-4

A-0901

2016

TP940-5

A-1209

15

TP940-5

A-0829

2016

TP940-6

A-0310

2016

TP940-6

AD-0310

2016

TP940-6

A-0615

2016

TP940-7

A-0830

2016

Sample number

A. In-waste samples

0.80

1.00

0.60

0.40

0.20

0.00

Mol

e fra

ctio

n

TP725-1

B-0825

2016

TP725-1

B-0906

2016

TP740-2

BR-1112

2015

TP740-2

BR-0503

2016

TP740-2

BRD-0503

2016

TP740-2

BR-0826

2016

TP740-2

BR-0906

2016

TP740-2

BRD-0906

2016

TP940-1

B-1209

2014

TP940-1

B-0901

2016

TP940-1

B-0908

2016

TP940-2

B-AQ-90

TP940-2

B-AQ-10

0

TP940-2

B-AQ-12

0

TP940-2

B-AQ-13

0

TP940-3

B-0122

2015

TP940-3

B-0831

2016

TP940-4

B-1210

2014

TP940-4

B-0901

2016

TP940-4

B-0907

2016

TP940-5

B-0829

2016

TP940-5

B-0907

2016

TP940-6

B-0310

2016

TP940-6

B-0615

2016

TP940-6

B-0829

2016

TP940-6

B-0906

2016

TP940-7

B-0830

2016

Sample number

B. Sub-waste samples

1,1,2,2-Tetrachloroethane

Tetrachloroethene

trans-1,2-Dichloroethene

1,3-Dichlorobenzene

Xylenes, total

1,1,2-Trichloroethane

Trichloroethene

Vinyl Chloride

1,2-Dichlorobenzene

Ethylbenzene

1,2-Dichloroethane

1,1-Dichloroethene

1,2,4-Trichlorobenzene

Chlorobenzene

Toluene

1,1-Dichloroethane

cis-1,2-Dichloroethene

1,4-Dichlorobenzene

Naphthalene

Benzene

EXPLANATION

Figure 4. Mole fractions for selected analytes in liquid in-waste and sub-waste samples, excluding cosolvents. (Calculated using all organic analytes in Draft Leachate Investigation Report table 4–8 [Geosyntec, written commun., 2017], excluding compounds in table 1.)


0.80

1.00

0.60

0.40

0.20

0.00

Mol

e fra

ctio

n

DW-4D-04

1120

16

DW-4D-08

0820

16

DW-7S-07

1220

16

DW-7S-08

0920

16

TD-2-07

1220

16

TD-2-08

0920

16

TF-1-07

1120

16

TF-1-08

0820

16

W66

0-DW-07

1320

16

W66

0-DW-08

0920

16

W74

0-14-0

8102

016

W74

0-14-0

8252

016

WE-03

R-0825

2016

WE-03

R-0908

2016

WSH-01

-0712

2016

WSH-01

-0809

2016

1,1,2,2-Tetrachloroethane

Tetrachloroethene


1,3-Dichlorobenzene

Xylenes, total

1,1,2-Trichloroethane

Trichloroethene

Vinyl Chloride

1,2-Dichlorobenzene

Ethylbenzene

1,1-Dichloroethene

1,2,4-Trichlorobenzene

Chlorobenzene

Toluene

1,1-Dichloroethane


1,4-Dichlorobenzene

Naphthalene

Benzene

EXPLANATION

Sample number

Figure 5. Mole fractions for selected analytes in landfill gas (LFG)-well samples collected in 2016, excluding cosolvents. (Calculated using all organic analytes in Draft Leachate Investigation Report table 4–8 [Geosyntec, written commun., 2017], excluding compounds in table 1.)

had the highest percent effective solubilities and consistently (except for naphthalene) exceeded those observed in the in-waste samples or other sub-waste samples (fig. 7). Sample TP940-6B was taken from a location where the groundwater is known to be in contact with the waste prism, and the well had liquid whether vented or sealed (Draft Leachate Investigation Report, Appendix Q [Geosyntec, written commun., 2017]). Among the in-waste samples, TP940-4A and TP940-6A consistently had the highest percent effective solubilities for the compounds of interest (fig. 7). TP940-4A and TP940-6A also were noted in the Draft Leachate Investigation Report as having liquid whether vented or sealed, and gas samples from TP940-6A had three to four orders of magnitude higher gas concentrations of chlorinated solvents and BTEX than those measured in TP940-6B (Geosyntec, written commun., 2017). If gas phase concentrations were accounted for in the calcula-tions with the liquid samples, percent effective solubilities for the TP940-6A liquid samples may be as high or higher than those calculated for TP940-6B.

The compounds shown in figure 7 are separated by class and shown in figures 8 to 11, plotted by the samples from in-waste and sub-waste piezometers. For the chlorinated ethanes, all of the in-waste and sub-waste samples had percent effec-tive solubilities less than 10, indicating that DNAPL or mixed DNAPL including these compounds likely is not present (fig. 8). The highest percent effective solubility for the chlori-nated ethanes was in samples from TP940-6B, where a range of about 4 to 5 percent effective solubility was calculated for 1,1,2-trichlorethane.

Table 2. Compounds with percent effective solubility less than 1 or 10 percent in all wells from Draft Leachate Investigation Report table 4–8 ([Geosyntec, written commun., 2017], excluding all cosolvents listed in table 1).

[%, percent; ≤, less than or equal to; >, greater than]

% Effective solubility ≤1 % Effective solubility >1 and ≤10

Allyl Chloride AlachlorBromobenzene 1,2,3-TrichloropropanePhenacetin Vinyl chlorideThionazin 1,1,2,2-Tetrachloroethane1,3,5-Trinitrobenzene Benzene3-Nitroaniline Benzoic acidn-Nitrosodi-n-butylamine 1,1,2-Trichloroethane1,3-Dichloropropene, total Ethyl methacrylateNitrobenzene 2,4-Dimethylphenol2-Nitrophenol Acetophenone Carbon disulfide 1,1-Dichloroethane1,2-Dichloropropane trans-1,2-Dichloroethene4-Chloro-3-methylphenol cis-1,2-DichloroetheneChloroethane Bis(2-chloroethyl)ethern-Nitrosodi-n-propylamine Chloroform

1,2-DichloroethaneIsophorone

10 Effective Solubility Assessm

ent for Organic Analytes in Liquid Samples, BKK Class I Landfill

TP725-1A-120915TP725-1A-05032016TP740-1A-08102016TP740-1A-08252016TP740-2A-11122015TP740-2A-08262016TP740-2AD-08262016TP740-2A-09072016TP850-1A-08302016TP940-1A-01232015TP940-1A-09012016

TP940-3A-01212015TP940-3A-01222015DUP-01212015 (TP940-3A)DUP-01222015 (TP940-3A)TP940-4A-12102014TP940-4A-09012016TP940-5A-120915TP940-5A-08292016TP940-6A-03102016TP940-6AD-03102016TP940-6A-06152016

TP940-7A-08302016TP725-1B-08252016TP725-1B-09062016TP740-2BR-11122015TP740-2BR-05032016TP740-2BRD-05032016TP740-2BR-08262016TP740-2BR-09062016TP740-2BRD-09062016TP940-1B-12092014TP940-1B-09012016

TP940-1B-09082016

TP940-2B-AQ-100TP940-2B-AQ-120TP940-2B-AQ-130TP940-3B-01222015TP940-3B-08312016TP940-4B-12102014TP940-4B-09012016TP940-4B-09072016TP940-5B-08292016

TP940-5B-09072016TP940-6B-03102016TP940-6B-06152016TP940-6B-08292016TP940-6B-09062016TP940-7B-08302016DW-4D-07112016DW-4D-08082016DW-7S-07122016DW-7S-08092016TD-2-07122016

TD-2-08092016TF-1-07112016TF-1-08082016W660-DW-07132016W660-DW-08092016W740-14-08102016W740-14-08252016WE-03R-08252016WE-03R-09082016WSH-01-07122016WSH-01-08092016

EXPLANATION

TP940-2B-AQ-90

[Black sample numbers, in-waste; blue sample numbers, sub-waste; brown sample numbers, LFG]

Isodrin

Benzo[a]anthracene

Pyrene

Bis(2-e

thylhexy

l)phthalate

Fluoranthene

PhenanthreneAnthracene

Di-n-octyl

phthalate

Butyl benzyl

phtalateFlu

orene

Ethyl Parathion

AcenaphtheneDibenzo

furan

2-Chloronaphthalene

Sulfotepp

n-Butyl

benzene

Acenaphthylene

sec-B

utylbenze

ne

Methyl parathion

2-Methyln

aphthalene

p-Isopropylt

oluene

n-Nitro

sodiphenyla

mine(as diphenyla

mine)

1-Methyln

aphthalenePhorate

tert-Butyl

benzene

Naphthalene

1,2,4-

Trichlorobenze

ne

1,3,5-

Trimethylb

enzene

Isopropylb

enzene

1,2,4-

Trimethylb

enzene

n-Propylb

enzene

1,4-D

ichlorobenzene

1,2,3-

Trimethylb

enzene

4-Chlorotoluene

1,3-D

ichlorobenzene

Isosa

frole

Alachlor

Tetra

chloroetheneXyle

nes, total

1,2-D

ichlorobenzene

1.0E−05

1.0E−04

1.0E−03

1.0E−02

1.0E−01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07Ef

fect

ive

solu

bilit

y, in

per

cent

Csat less than 250 micromoles per liter

Figure 6. Effective solubility, as percent of the measured concentrations, in all liquid samples (in-waste, sub-waste, and landfill gas [LFG]) reported in Draft Leachate Investigation Report table 4–8 (Geosyntec, written commun., 2017). (Analytes arranged in order of increasing aqueous solubility [Csat].)

Effective Solubilities in Landfill Liquid Samples

11

TP725-1A-120915TP725-1A-05032016TP740-1A-08102016TP740-1A-08252016TP740-2A-11122015TP740-2A-08262016TP740-2AD-08262016TP740-2A-09072016TP850-1A-08302016TP940-1A-01232015TP940-1A-09012016

TP940-3A-01212015TP940-3A-01222015DUP-01212015 (TP940-3A)DUP-01222015 (TP940-3A)TP940-4A-12102014TP940-4A-09012016TP940-5A-120915TP940-5A-08292016TP940-6A-03102016TP940-6AD-03102016TP940-6A-06152016

TP940-7A-08302016TP725-1B-08252016TP725-1B-09062016TP740-2BR-11122015TP740-2BR-05032016TP740-2BRD-05032016TP740-2BR-08262016TP740-2BR-09062016TP740-2BRD-09062016TP940-1B-12092014TP940-1B-09012016

TP940-1B-09082016

TP940-2B-AQ-100TP940-2B-AQ-120TP940-2B-AQ-130TP940-3B-01222015TP940-3B-08312016TP940-4B-12102014TP940-4B-09012016TP940-4B-09072016TP940-5B-08292016

TP940-5B-09072016TP940-6B-03102016TP940-6B-06152016TP940-6B-08292016TP940-6B-09062016TP940-7B-08302016DW-4D-07112016DW-4D-08082016DW-7S-07122016DW-7S-08092016TD-2-07122016

TD-2-08092016TF-1-07112016TF-1-08082016W660-DW-07132016W660-DW-08092016W740-14-08102016W740-14-08252016WE-03R-08252016WE-03R-09082016WSH-01-07122016WSH-01-08092016

EXPLANATION

TP940-2B-AQ-90

[Black sample numbers, in-waste; blue sample numbers, sub-waste; brown sample numbers, LFG]

Styrene

Ethylbenze

ne

Dichlorodifluoromethane

Bromobenzene

1,1-D

ichloroethene

2-Chlorotoluene

Tetra

hydrofuran

Phenacetin

Chlorobenzene

Thionazin

Diethyl phthalate

1,3,5-

Trinitro

benzene

Toluene

3-Nitro

aniline

n-Nitro

sodi-n

-butylamine

Trichloroethene

1,2,3-

Trichloropropane

1,3-D

ichloropropene, total

Nitrobenze

neVinyl

Chloride

1,1,2,

2-Tetra

chloroethane2-N

itrophenol

Carbon disulfid

eBenze

ne

1,2-D

ichloropropane

4-Chloro-3-

methylphenol

Benzoic acid

1,1,2-

TrichloroethaneAlly

l Chlorid

e

Ethyl methacryl

ate

2,4-D

imethylp

henol

Acetophenone

1,1-D

ichloroethane

trans-1

,2-Dichloroethene

cis-1,2

-Dichloroethene

Bis (2-chloroethyl)

etherChloroethane

n-Nitro

sodi-n

-propylamine

Chloroform

1,2-D

ichloroethaneIso

phorone

1.0E−05

1.0E−04

1.0E−03

1.0E−02

1.0E−01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

Figure 6. Effective solubility, as percent of the measured concentrations, in all liquid samples (in-waste, sub-waste, and landfill gas [LFG]) reported in Draft Leachate Investigation Report table 4–8 (Geosyntec, written commun., 2017). (Analytes arranged in order of increasing aqueous solubility [Csat].)—Continued


1,000.000

100.000

10.000

1.000

0.100

0.010

0.001

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

1,1,2,

2-Tetra

chloroethane

1,1,2-

Trichloroethane

1,2-D

ichloroethane

1,1-D

ichloroethane

Tetra

chloroethene

Trichloroethene

1,1-D

ichloroethene

cis-1,2

-Dichloroethene

trans-1

,2-Dichloroethene

Vinyl Chlorid

e

1,2,4-

Trichlorobenze

ne

1,4-D

ichlorobenzene

1,3-D

ichlorobenzene

1,2-D

ichlorobenzene

Chlorobenzene

Naphthalene

Xylenes,

total

Ethylbenze

ne

Toluene

Benzene

Selected compounds

TP725-1B-08252016

TP940-1B-12092014

TP940-2B-AQ-100

TP940-3B-08312016

TP940-5B-08292016

TP940-6B-08292016

TP725-1B-09062016

TP740-2BR-08262016

TP940-1B-09012016

TP940-2B-AQ-120

TP940-4B-12102014

TP940-5B-09072016

TP940-6B-09062016

TP740-2BR-11122015

TP740-2BR-09062016

TP940-1B-09082016

TP940-2B-AQ-130

TP940-4B-09012016

TP940-6B-03102016

TP940-7B-08302016

TP740-2BR-05032016

TP740-2BRD-09062016

TP940-2B-AQ-90

TP940-3B-01222015

TP940-4B-09072016

TP940-6B-06152016

EXPLANATION

B. Sub-waste

1,000.000

100.000

10.000

1.000

0.100

0.010

0.001

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

1,1,2,

2-Tetra

chloroethane

1,1,2-

Trichloroethane

1,2-D

ichloroethane

1,1-D

ichloroethane

Tetra

chloroethene

Trichloroethene

1,1-D

ichloroethene

cis-1,2

-Dichloroethene

trans-1

,2-Dichloroethene

Vinyl Chlorid

e

1,2,4-

Trichlorobenze

ne

1,4-D

ichlorobenzene

1,3-D

ichlorobenzene

1,2-D

ichlorobenzene

Chlorobenzene

Naphthalene

Xylenes,

total

Ethylbenze

ne

Toluene

Benzene

Selected compounds

TP725-1A-120915

TP740-2A-11122015

TP850-1A-08302016

TP940-4A-09012016

TP940-6AD-03102016

TP725-1A-05032016

TP740-2A-08262016

TP940-1A-01232015

DUP-01212015 (TP940-3A)

TP940-5A-120915

TP940-6A-06152016

TP-1A-08102016

TP740-2AD-08262016

TP940-1A-09012016

TP940-5A-08292016

TP940-7A-08302016

TP740-1A-08252016

TP740-2A-09072016

TP940-3A-01212015

TP940-4A-12102014

TP940-6A-03102016

EXPLANATION

A. In-waste

Figure 7. Effective solubility, as percent of the measured concentrations, for selected analytes in in-waste and sub-waste samples. (Data from Draft Leachate Investigation Report table 4–8 [Geosyntec, written commun., 2017].)


10.00

1.00

0.10

0.01

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

TP725-1

B-0825

2016

TP725-1

B-0906

2016

TP740-2

BR-1112

2015

TP740-2

BR-0503

2016

TP740-2

BRD-0503

2016

TP740-2

BR-0826

2016

TP740-2

BR-0906

2016

TP740-2

BRD-0906

2016

TP940-1

B-1209

2014

TP940-1

B-0901

2016

TP940-1

B-0908

2016

TP940-2

B-AQ-90

TP940-2

B-AQ-10

0

TP940-2

B-AQ-12

0

TP940-2

B-AQ-13

0

TP940-3

B-0122

2015

TP940-3

B-0831

2016

TP940-4

B-1210

2014

TP940-4

B-0901

2016

TP940-4

B-0907

2016

TP940-5

B-0829

2016

TP940-5

B-0907

2016

TP940-6

B-0310

2016

TP940-6

B-0615

2016

TP940-6

B-0829

2016

TP940-6

B-0906

2016

TP940-7

B-0830

2016

Sample number

B. Chlorinated ethanes in samples from sub-waste wells

10.00

1.00

0.10

0.01

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

TP725-1

A-1209

15

TP725-1

A-0503

2016

TP740-1

A-0810

2016

TP740-1

A-0825

2016

TP740-2

A-1112

2015

TP740-2

A-0826

2016

TP740-2

AD-0826

2016

TP740-2

A-0907

2016

TP850-1

A-0830

2016

TP940-1

A-0123

2015

TP940-1

A-0901

2016

TP940-3

A-0121

2015

TP940-3

A-0122

2015

DUP-0121

2015

(TP94

0-3A)

DUP-0122

2015

(TP94

0-3A)

TP940-4

A-1210

2014

TP940-4

A-0901

2016

TP940-5

A-1209

15

TP940-5

A-0829

2016

TP940-6

A-0310

2016

TP940-6

AD-0310

2016

TP940-6

A-0615

2016

TP940-7

A-0830

2016

Sample number

A. Chlorinated ethanes in samples from in-waste wells

EXPLANATION

1,1,2,2-Tetrachloroethane 1,1,2-Trichloroethane 1,2-Dichloroethane 1,1-Dichloroethane 10-percent threshold

Figure 8. Effective solubility, as percent of the measured concentrations, of chlorinated ethanes in samples from the in-waste and sub-waste wells.


TP725-1

B-0825

2016

TP725-1

B-0906

2016

TP740-2

BR-1112

2015

TP740-2

BR-0503

2016

TP740-2

BRD-0503

2016

TP740-2

BR-0826

2016

TP740-2

BR-0906

2016

TP740-2

BRD-0906

2016

TP940-1

B-1209

2014

TP940-1

B-0901

2016

TP940-1

B-0908

2016

TP940-2

B-AQ-90

TP940-2

B-AQ-10

0

TP940-2

B-AQ-12

0

TP940-2

B-AQ-13

0

TP940-3

B-0122

2015

TP940-3

B-0831

2016

TP940-4

B-1210

2014

TP940-4

B-0901

2016

TP940-4

B-0907

2016

TP940-5

B-0829

2016

TP940-5

B-0907

2016

TP940-6

B-0310

2016

TP940-6

B-0615

2016

TP940-6

B-0829

2016

TP940-6

B-0906

2016

TP940-7

B-0830

2016

Sample number

1,000.000

100.000

10.000

1.000

0.100

0.010

0.001

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

B. Chlorinated ethenes in samples from sub-waste wells

1,000.000

100.000

10.000

1.000

0.100

0.010

0.001

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

TP725-1

A-1209

15

TP725-1

A-0503

2016

TP740-1

A-0810

2016

TP740-1

A-0825

2016

TP740-2

A-1112

2015

TP740-2

A-0826

2016

TP740-2

AD-0826

2016

TP740-2

A-0907

2016

TP850-1

A-0830

2016

TP940-1

A-0123

2015

TP940-1

A-0901

2016

TP940-3

A-0121

2015

TP940-3

A-0122

2015

DUP-0121

2015

(TP94

0-3A)

DUP-0122

2015

(TP94

0-3A)

TP940-4

A-1210

2014

TP940-4

A-0901

2016

TP940-5

A-1209

15

TP940-5

A-0829

2016

TP940-6

A-0310

2016

TP940-6

AD-0310

2016

TP940-6

A-0615

2016

TP940-7

A-0830

2016

Sample number

A. Chlorinated ethenes in samples from in-waste wells

EXPLANATION

Tetrachloroethene

Trichloroethene

1,1-Dichloroethene



Vinyl Chloride

10-percent threshold

Figure 9. Effective solubility, as percent of the measured concentrations, of chlorinated ethenes in samples from the in-waste and sub-waste wells.


TP725-1

B-0825

2016

TP725-1

B-0906

2016

TP740-2

BR-1112

2015

TP740-2

BR-0503

2016

TP740-2

BRD-0503

2016

TP740-2

BR-0826

2016

TP740-2

BR-0906

2016

TP740-2

BRD-0906

2016

TP940-1

B-1209

2014

TP940-1

B-0901

2016

TP940-1

B-0908

2016

TP940-2

B-AQ-90

TP940-2

B-AQ-10

0

TP940-2

B-AQ-12

0

TP940-2

B-AQ-13

0

TP940-3

B-0122

2015

TP940-3

B-0831

2016

TP940-4

B-1210

2014

TP940-4

B-0901

2016

TP940-4

B-0907

2016

TP940-5

B-0829

2016

TP940-5

B-0907

2016

TP940-6

B-0310

2016

TP940-6

B-0615

2016

TP940-6

B-0829

2016

TP940-6

B-0906

2016

TP940-7

B-0830

2016

Sample number

1,000.00

100.00

10.00

1.00

0.10

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

B. Chlorinated benzenes in samples from sub-waste wells

TP725-1

A-1209

15

TP725-1

A-0503

2016

TP740-1

A-0810

2016

TP740-1

A-0825

2016

TP740-2

A-1112

2015

TP740-2

A-0826

2016

TP740-2

AD-0826

2016

TP740-2

A-0907

2016

TP850-1

A-0830

2016

TP940-1

A-0123

2015

TP940-1

A-0901

2016

TP940-3

A-0121

2015

TP940-3

A-0122

2015

DUP-0121

2015

(TP94

0-3A)

DUP-0122

2015

(TP94

0-3A)

TP940-4

A-1210

2014

TP940-4

A-0901

2016

TP940-5

A-1209

15

TP940-5

A-0829

2016

TP940-6

A-0310

2016

TP940-6

AD-0310

2016

TP940-6

A-0615

2016

TP940-7

A-0830

2016

Sample number

1,000.00

100.00

10.00

1.00

0.10

Effe

ctiv

e so

lubi

lity,

in p

erce

ntA. Chlorinated benzenes in samples from in-waste wells

1,2,4-Trichlorobenzene 1,4-Dichlorobenzene 1,3-Dichlorobenzene 1,2-Dichlorobenzene Chlorobenzene 10-percent threshold

EXPLANATION

Figure 10. Effective solubility, as percent of the measured concentrations, of chlorinated benzenes in samples from the in-waste and sub-waste wells.


TP725-1

B-0825

2016

TP725-1

B-0906

2016

TP740-2

BR-1112

2015

TP740-2

BR-0503

2016

TP740-2

BRD-0503

2016

TP740-2

BR-0826

2016

TP740-2

BR-0906

2016

TP740-2

BRD-0906

2016

TP940-1

B-1209

2014

TP940-1

B-0901

2016

TP940-1

B-0908

2016

TP940-2

B-AQ-90

TP940-2

B-AQ-10

0

TP940-2

B-AQ-12

0

TP940-2

B-AQ-13

0

TP940-3

B-0122

2015

TP940-3

B-0831

2016

TP940-4

B-1210

2014

TP940-4

B-0901

2016

TP940-4

B-0907

2016

TP940-5

B-0829

2016

TP940-5

B-0907

2016

TP940-6

B-0310

2016

TP940-6

B-0615

2016

TP940-6

B-0829

2016

TP940-6

B-0906

2016

TP940-7

B-0830

2016

Sample number

1,000.00

100.00

10.00

1.00

0.10

0.01

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

B. BTEX and naphthalene in samples from sub-waste wells

TP725-1

A-1209

15

TP725-1

A-0503

2016

TP740-1

A-0810

2016

TP740-1

A-0825

2016

TP740-2

A-1112

2015

TP740-2

A-0826

2016

TP740-2

AD-0826

2016

TP740-2

A-0907

2016

TP850-1

A-0830

2016

TP940-1

A-0123

2015

TP940-1

A-0901

2016

TP940-3

A-0121

2015

TP940-3

A-0122

2015

DUP-0121

2015

(TP94

0-3A)

DUP-0122

2015

(TP94

0-3A)

TP940-4

A-1210

2014

TP940-4

A-0901

2016

TP940-5

A-1209

15

TP940-5

A-0829

2016

TP940-6

A-0310

2016

TP940-6

AD-0310

2016

TP940-6

A-0615

2016

TP940-7

A-0830

2016

Sample number

1,000.00

100.00

10.00

1.00

0.10

0.01

Effe

ctiv

e so

lubi

lity,

in p

erce

nt

A. BTEX and naphthalene in samples from in-waste wells

Naphthalene Xylenes, total Ethylbenzene Toluene Benzene 10-percent threshold

EXPLANATION

Figure 11. Effective solubility, as percent of the measured concentrations, of benzene, toluene, ethylbenzene, and xylenes (BTEX) and naphthalene in samples from the in-waste and sub-waste wells. (A 100-percent threshold is used for naphthalene.)

References Cited 17

For the chlorinated ethenes in the in-waste samples, percent effective solubilities were greater than 10 percent for tetrachloroethene in TP940-4A and TP940-6A, and for tetrachloroethene and 1,1-dichloroethene in TP940-6AD, indicating possible DNAPL or mixed DNAPL presence with these compounds (fig. 9). The sub-waste piezometer pairs of TP940-4B and TP940-6B also showed greater than 10 percent effective solubilities of tetrachloroethene, indicating the likely presence of DNAPL or mixed DNAPL near these locations (fig. 9). Piezometer TP940-6B also had greater than 10 percent effective solubilities of 1,1-dichloroethene, trichloroethene, and vinyl chloride. In addition, effective solubilities were greater than 10 percent for tetrachloroethene in two samples from TP740-5B.

In general, the effective solubilities in the in-waste and sub-waste samples showed similar patterns for the chlori-nated ethenes and ethanes, with low percent effective solu-bilities occurring in the paired piezometers TP725-1A/1B and TP740-2A/2BR and high percent effective solubili-ties occurring in the paired piezometers TP940-4A/4B and TP940-6A/6B (figs. 8 and 9). The similar patterns in effective solubilities of the chlorinated ethane and ethene compounds in the in-waste and sub-waste piezometers may be partly due to a similar pattern of influence of volatilization on the liquid samples and indicate that biodegradation likely has not had any greater effect on the chlorinated solvents in the in-waste liquid than the sub-waste liquid.

For the chlorinated benzenes in the in-waste samples, percent effective solubilities were greater than 10 percent for 1,2,4-trichlorobenzene in samples from TP725-1A, TP940-5A, and TP940-6A, whereas 1,4-dichlorobenzene exceeded the 10-percent threshold in samples from TP940-1A, TP940-4A, TP940-6A, and TP940-7A (fig. 10). The percent effective solubilities of 1,2-dichlorobenzene were greater than 10 percent in the same in-waste samples as observed for 1,4-dichlorobenzene, except for TP940-1A. In con-trast to the chlorinated ethenes and ethanes, the pattern of percent effective solubilities for the chlorinated benzenes was somewhat different in the sub-waste samples than the in-waste samples. The 10-percent threshold was exceeded for 1,2,4-trichlorobenzene in samples from only one of the paired piezometers that exceeded the threshold in the in-waste samples (TP940-5B) and was also exceeded in TP940-3B and TP940-7B. Elevated percent effective solubilities for 1,4-dichlorobenzene and 1,2-dichlorobenzene were more widespread in the sub-waste samples than the in-waste sam-ples, with the 10-percent threshold equaled or exceeded for both compounds in sub-waste samples from wells TP940-1B, TP940-2B-AQ-90, TP940-2B-AQ-100, TP940-2B-AQ-120, TP940-4B, TP940-5B, and TP940-6B and in in-waste samples from wells TP940-4A, TP940-6A, and TP940-7A (fig. 10). The 10-percent threshold also was exceeded for 1,4-dichlorobenzene in the sub-waste sample from well TP725-1B and in-waste samples from TP940-1A (fig. 10).

If the more conservative threshold of 100 percent effec-tive solubility is considered for naphthalene, DNAPL or

mixed DNAPL presence is indicated by samples from in-waste piezometers TP940-4A and TP940-6A and sub-waste piezometers TP940-2B-AQ-100, TP940-4B, and TP940-5B (fig. 11). The pattern of percent effective solubilities for BTEX in the in-waste and sub-waste piezometer samples is similar to the pattern for the chlorinated benzenes, with more detec-tions and more samples above the 10-percent threshold in the sub-waste samples than the in-waste samples (figs. 10 and 11). Of the BTEX compounds, percent effective solubilities greater than the 10-percent threshold were most widespread for ethylbenzene and total xylenes (fig. 11). Percent effective solubilities for benzene were less than 10 percent (and often less than 1 percent) for all in-waste and sub-waste samples, whereas the percent effective solubilities for toluene were greater than 10 percent only in samples from TP940-4A and TP940-6B (fig. 11). Considering the known presence of LNAPL at the site, the low BTEX percent effective solubilities may indicate that volatilization, and perhaps biodegradation, is decreasing these concentrations in the liquid samples. Again, it should be noted that accounting for measured gas concentra-tions of the compounds of interest would likely increase the percent effective solubilities, especially for the more volatile constituents.

Overall, these effective solubility calculations indicate the likely presence of DNAPLs or mixed DNAPLs at the site for some compounds. Percent effective solubilities were highest for many chlorinated ethenes, ethanes, and benzenes in the samples from paired in-waste/sub-waste piezometers TP940-6A and TP940-6B, which is in a location where the groundwater is known to be in contact with the waste prism. The agreement in trends in the effective solubilities for the chlorinated ethenes and ethanes between the in-waste and sub-waste samples supports a similar source composition and does not appear to support substantial differences in anaero-bic degradation affecting these liquids. The more widespread detections and exceedance of the 10-percent effective solubil-ity threshold of the chlorinated benzenes and BTEX in the sub-waste samples than the in-waste samples may indicate some variability in sources for these two liquids, although volatilization effects also may influence the patterns in the calculated effective solubilities.

References Cited

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Cozzarelli, I.M., Böhlke, J.K., Masoner, J., Breit, G.N., Lorah, M.M., Tuttle, M.L.W., and Jaeschke, J.B., 2011, Biogeochemical evolution of a landfill leachate plume, Norman, Oklahoma: Groundwater, v. 49, no. 5, p. 663–687, accessed July 23, 2019, athttps://doi.org/10.1111/j.1745-6584.2010.00792.x.

https://www.atsdr.cdc.gov/substances/index.asp

https://doi.org/10.1111/j.1745-6584.2010.00792.x


Davis, M.L., and Masten, S.J., 2013, Principles of environmental engineering and Science (3d ed.): New York, McGraw Hill, 704 p.

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Geosyntec, 2015, EE/CA Phase II Leachate Investigation Work Plan, BKK Class I Landfill, West Covina, California, September 2, accessed May 20, 2019, at https://www.envirostor.dtsc.ca.gov/public/final_documents2?global_id=19490005&doc_id=60380333.

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Masoner, J.R., Kolpin, D.W., Furlong, E.T., Cozzarelli, I.M., Gray, J.L., and Schwab, E.A., 2014, Contaminants of emerging concern in fresh leachate from landfills in the conterminous United States: Environmental Science: Processes and Impacts, v. 16, no. 10, p. 2335–2354, accessed July 23, 2019, at https://pubs.rsc.org/en/content/articlehtml/2014/em/c4em00124a.

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Pavelka, C., Loehr, R.C., and Haikola, B., 1993, Hazardous waste landfill leachate characteristics: Waste Management, v. 13, no. 8, p. 573–580.

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U.S. Environmental Protection Agency, 2004a, Site char-acterization technologies for DNAPL Investigations: EPA 542-R-04-017, Office of Solid Waste and Emergency Response (5102G), accessed May 16, 2019, at https://semspub.epa.gov/work/HQ/134428.pdf.

U.S. Environmental Protection Agency, 2004b, DNAPL Remediation: Selected projects approaching regulatory closure: EPA 542-R-04-016, Solid Waste and Emergency Response (5102G), December 2004, accessed May 16, 2019, at https://www.epa.gov/sites/production/files/2015-04/documents/dnapl_remed_542r04016.pdf.

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https://pubs.rsc.org/en/content/articlehtml/2014/em/c4em00124a

https://pubs.rsc.org/en/content/articlehtml/2014/em/c4em00124a

https://chem.nlm.nih.gov/chemidplus/

https://chem.nlm.nih.gov/chemidplus/

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https://semspub.epa.gov/work/HQ/134428.pdf

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https://www.epa.gov/sites/production/files/2015-04/documents/dnapl_remed_542r04016.pdf

https://comptox.epa.gov/dashboard

https://comptox.epa.gov/dashboard

For additional information, contact:Director, MD-DE-DC Water Science CenterU.S. Geological Survey5522 Research Park DriveBaltimore, MD 21228

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Lorah and others—Effective Solubility A

ssessment for O

rganic Analytes in Liquid Sam

ples, BKK Class I Landfill—


ISSN 2331-1258 (online)https://doi.org/10.3133/ofr20191080


ofr20191080.pdf - effective solubility assessment for ... · pounds (vocs), in particular...

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