EVALUATION OF NON-VOLATILE ORGANIC COMPOUNDS ...Tel (978) Nobis Engineering, Inc. 585 Middlesex...

Nobis Engineering, Inc. 585 Middlesex Street Lowell, MA 01851 Tel (978) 683-0891 Fax (978) 683-0966 www.nobisengineering.com

EPA Region 1 RAC 2 Contract No. EP-S1-06-03

September 22, 2009 Nobis Project No. 80028

Via Electronic Submittal

U.S. Environmental Protection Agency Attention: Mr. Byron Mah, Task Order Project Officer 1 Congress Street, Suite 1100 Mail Code: HBO Boston, Massachusetts 02114-2023

Subject: Transmittal of Evaluation of Non-VOCs Data Letter Report Davis Liquid Waste Superfund Site, Smithfield, Rhode Island Focused Feasibility Study Task Order No. 0028-RI-CO-0117

Dear Mr. Mah:

Enclosed is the Evaluation of Non-VOCs Data Letter Report, which was prepared in response to EPA’s request for Nobis Engineering, Inc. to: assess available, historical soil data to determine whether contaminants other than VOCs posed potential threats to groundwater quality, or posed potential health risks through direct contact exposures.

Should you have any questions or comments, please contact me at (978) 703-6003, or [email protected].

Sincerely,

NOBIS ENGINEERING, INC.

Liyang Chu Sr. Project Manager

Enclosure

c: File 80028/MA (w/enc.) D. McGrath/Nobis (w/enc.) C. Woods/Avatar (w/enc.)

ENGINEERING & CONSTRUCTION SOLUTIONS

mailto:[email protected]:www.nobisengineering.com

EVALUATION OF NON-VOCs DATA DAVIS LIQUID WASTE SITE

September 2009

1.0 INTRODUCTION Nobis Engineering, Inc. (Nobis) reviewed available historic information for the Davis Liquid

Waste Site (Site) to evaluate whether contaminants other than volatile organic compounds

(VOCs) in the former Source Area (Figure 1) soil may be potential contaminants of concern

(COCs) for the Focused Feasibility Study. As part of the Focused Feasibility Study

development, VOCs data had been

The evaluation consists of two assessments for non-VOCs in the former Source Area soil:

• whether soil contaminants represent potential leaching threats to groundwater quality,

and

• whether soil contaminants may pose potential direct contact threats.

The data reviewed were obtained from the following sources:

• Pre-Remedial Action Data: The most recent SVOCs and metals data for soil are presented in two reports: the

Remedial Investigation (CDM, 1986) and the Final Pre-Design Engineering Report II

(Woodward-Clyde, October 1993).

• Post-Remedial Action Data: The soils were not analyzed for non-VOCs after the completion of low-temperature

thermal remediation treatment and backfilling during the source control remedial action

(initiated in 1999).

The most recent groundwater samples with SVOC and metal results were collected in

2003 and 2004, respectively. SVOC data were obtained from the Phase 2 Pre-Design

Summary Report (ESS, 2004) and metals data were obtained directly from ESS in

interoffice communications.

MA-2181-2009-F 1 Nobis Engineering, Inc.

2.0 LEACHING OF SVOCS AND METALS TO GROUNDWATER This assessment consisted of: evaluating the 2003 and 2004 groundwater data to determine

whether SVOCs and metals posed potential risks through exposures to groundwater as drinking

water, identifying the chemicals or metals that were the principal risk drivers, and determining

whether groundwater non-VOC risk drivers were present in the former Source Area soils.

2.1 Non-VOC Groundwater Risks Cancer risks and non-cancer health hazards posed by maximum recent groundwater

concentrations of SVOCs and metals through drinking water exposures were evaluated in the

Conceptual Site Model Technical Memorandum Addendum risk evaluation (Nobis, 2009).

These groundwater risks do not take into consideration the distribution of the contaminants in

the plume. Results of the Conceptual Site Model Technical Memorandum Addendum risk

evaluation and comparisons of groundwater concentrations to drinking water standards

(Maximum Contaminant Levels [MCLs] or the Rhode Island GA Department of Environmental

Management [RIDEM] Objectives), and risk-based screening levels (i.e., EPA’s Regional

Screening Levels [RSLs] for tap water [EPA, 2009]) are summarized below.

2.1.1 SVOCs Risk Evaluation Summary Risks posed by overburden groundwater SVOCs and comparisons of site concentrations to

EPA RSLs for tap water and MCLs or RIDEM GA Objectives are summarized in Table 1.

Bis(2-chloroethyl)ether [BCEE], nitrobenzene, naphthalene, pentachlorophenol, and 2,4,6

trichlorophenol were identified as the primary contributors to the cancer risk estimate from

exposures to SVOCs in Site overburden groundwater used as drinking water. The prime

contributor to the non-cancer hazard index for SVOCs is 4,6-dinitro-2-methylphenol. Maximum

detected concentrations of: naphthalene; BCEE; nitrobenzene; 2,4,6-trichlorophenol; and

pentachlorophenol exceeded the cancer risk based EPA RSLs for tap water. Maximum

detected concentrations of 4,6-dinitro-2-methylphenol and 2,4-dinitrophenol exceeded the non-

cancer risk based EPA RSLs for tap water adjusted to a HI of 0.1. Only pentachlorophenol

exceeded the MCLs or RIDEM GA Objectives. BCEE, nitrobenzene, pentachlorophenol, 2,4,6

trichlorophenol, 4,6-dinitro-2-methylphenol, and 2,4-dinitrophenol were infrequently detected (1

in 20 samples each). Naphthalene was the only SVOC exceeding screening criteria in

overburden groundwater detected in more than 1 in 20 samples.


2.1.2

Risks posed by bedrock groundwater SVOCs and comparisons of site concentrations to EPA

RSLs for tap water and MCLs or RIDEM GA Objectives are summarized in Table 2. BCEE,

naphthalene, p-chloroaniline, and pentachlorophenol are the primary contributors to the

cancer risk estimate from exposures to SVOCs in Site bedrock groundwater used as drinking

water. BCEE was the prime contributor of cancer risk at 2.2 E-03. The estimated total Site

non-cancer HI from exposures to SVOCs in bedrock groundwater used as drinking water is

less than 1. Maximum detected concentrations of BCEE, naphthalene, p-chloroaniline, and

pentachlorophenol exceeded the cancer risk based EPA RSLs for tap water. The maximum

detected concentration of 2,4-dinitrophenol exceeded the non-cancer risk based EPA RSL for

tap water adjusted to a HI of 0.1. Only pentachlorophenol exceeded the MCLs or RIDEM GA

Objectives. Naphthalene, p-chloroaniline, pentachlorophenol, and 2,4-dinitrophenol were each

detected in 1 of 21 samples. BCEE was the only SVOC exceeding screening criteria in bedrock

groundwater detected in 4 of 21 samples.

Based on this evaluation, naphthalene and BCEE in groundwater were identified as possible

COCs for drinking water exposures because they exceeded screening criteria (RSLs) and were

present in more than 5 percent of the samples.

Distribution of SVOCs in Groundwater The distributions of potential SVOC COCs, BCEE and naphthalene, in the overburden and

bedrock groundwater are depicted in Figures 1 (overburden) and 2 (bedrock).

BCEE BCEE was not present in the former Source Area groundwater (Figures 1 and 2). BCEE was

infrequently detected in overburden groundwater (1/20), and was detected in 4 out of 21 wells in

the bedrock downgradient of former Source Area. Based on lack of BCEE presence in the

former Source Area groundwater, it is reasonable to conclude that the former Source Area soil

is not a current source of BCEE to groundwater. However, the source of the BCEE detected in

the 5 groundwater samples is unknown.

Naphthalene All three detects of naphthalene occurred in the former Source Area overburden groundwater

(Figure 1). In the bedrock, naphthalene was only detected in one downgradient location

(Figure 2).


2.1.3

Based on naphthalene presence in the former Source Area groundwater, it is possible that the

former Source Area soil may be a current source of this SVOC to overburden groundwater. The

available data suggest that former Source Area soil is not a current source of naphthalene to

bedrock groundwater.

Metals Risk Evaluation Summary Risks posed by overburden groundwater metals and comparisons of Site concentrations to EPA

RSLs for tap water and MCLs or RIDEM GA Objectives are summarized in Table 3. Arsenic is

the sole contributor to the cancer risk estimate from exposures to metals in Site overburden

groundwater used as drinking water. The prime contributors to the total Site hazard indices (HI)

for metals are mercury and manganese. The maximum detected concentration of arsenic

exceeded the cancer risk based EPA RSL for tap water. Maximum detected concentrations of

cobalt, iron, manganese, and mercury exceeded the non-cancer risk based EPA RSLs for tap

water adjusted to a HI of 0.1. Only arsenic and mercury exceeded the MCLs or RIDEM GA

Objectives. Arsenic and mercury were each detected in 1 of 20 samples. Cobalt and iron were

detected more frequently, but non-cancer hazard indices for these metals were less than 1.

Manganese was the only metal risk driver in overburden groundwater detected in more than 1 in

20 samples.

Risks posed by bedrock groundwater metals and comparisons of Site concentrations to EPA

RSLs for tap water and MCLs or RIDEM GA Objectives are summarized in Table 4. Arsenic is

the sole contributor to the cancer risk from exposures to metals in Site bedrock groundwater

used as drinking water. The prime contributor to total Site HI for metals is manganese. The

maximum detected concentration of arsenic exceeded the cancer risk based EPA RSL for tap

water. Maximum detected concentrations of iron and manganese exceeded the non-cancer risk

based EPA RSLs for tap water adjusted to a HI of 0.1. The non-cancer HI for iron was less

than 1. Only arsenic exceeded the MCLs or RIDEM GA Objectives. Arsenic was detected in 2

of 17 samples, and manganese was detected in 13 of 17 samples. Arsenic and manganese

remain as potential concerns in bedrock groundwater.

Based on this evaluation, arsenic and manganese in groundwater were identified as possible

contaminants of concern for drinking water exposures.


2.1.4 Distribution of Metals in Groundwater The distributions of potential metal COCs, arsenic and manganese, in the overburden and

bedrock groundwater are depicted in Figures 3 (overburden) and 4 (bedrock).

Arsenic Arsenic was not detected in the former Source Area overburden groundwater. Arsenic was only

detected in 1 of 17 overburden samples, at a location that does not appear to be downgradient

the former Source Area.

Arsenic was not detected in the former Source Area bedrock groundwater. Arsenic was

detected in 2 of 20 bedrock samples; only one was located downgradient of the former Source

Area.

Based on lack of arsenic presence in the former Source Area groundwater and the infrequent

detections of arsenic, the former Source Area soil does not appear to be a source of arsenic to

overburden and bedrock groundwater.

Manganese Manganese was detected in all overburden samples and in most bedrock samples. Manganese

was detected in all former Source Area groundwater samples.

Manganese in soil is believed to be naturally occurring (see Section 2.2.2). Previous

assessments in the Conceptual Site Model Technical Memorandum Addendum (Nobis, 2009)

indicate that reductive dechlorination processes are ongoing within the volatile organic

compound (VOC) plumes associated with the Davis Liquid Waste Site. The naturally occurring

manganese is used by anaerobic microbes as electron acceptors in the reductive dechlorination

process, which results in the mobilization of the naturally occurring manganese from soil to

groundwater. However, the increased manganese concentrations in groundwater represent

potential risks.

2.2 Evaluation of Soil Leaching Potential To evaluate whether naphthalene and manganese in former Source Area soil represent potential leaching threats to groundwater quality (and thus become risk drivers), soil data from

the 1986 Remedial Investigation (RI) (CDM, 1986) and soil data from the former Source Area


presented in Final Pre-Design Engineering Report II (Woodward-Clyde, October 1993) were

reviewed and compared to EPA RSL risk-based soil screening levels (SSLs) for protection of

groundwater (based on a dilution attenuation factor [DAF] of 1) (EPA, 2009).

2.2.1 Remedial Investigation Soil Data A remedial investigation (RI) was completed in 1986 at the Davis Liquid Waste Site, which

included the collection of soil, groundwater, surface water, and sediment samples from

numerous locations throughout the Site. The RI identified extensive contamination of site soils,

overburden and bedrock groundwater, sediment, and surface water at the Site. Contamination

of each medium consisted primarily of VOCs. However, the RI also identified elevated

concentrations of SVOCs, PCBs, and pesticides, and metals.

Soil data collected during the RI are presented below. These data represent pre-remedial action

conditions.

Naphthalene Naphthalene was detected in 11 of 66 samples, with a geometric mean concentration of 6.93

mg/Kg (of positive detect values, only). The mean and all detected soil concentrations

exceeded the EPA risk-based SSL for protection of groundwater of 5.5 E-04 mg/Kg (at a DAF

of 1).

Manganese Manganese was detected in 92 of 95 samples, with a geometric mean of 150 mg/Kg (of positive

detect values, only). The mean and most of the detected manganese concentrations exceeded

the EPA risk-based SSL for protection of groundwater (57 mg/Kg at a DAF of 1).

2.2.2 Pre-Design Engineering Investigation Soil Data A pre-design engineering investigation (PDEI) was completed in 1993 that included the

collection of soil, groundwater, surface water, and sediment samples from numerous locations

throughout the Site (Woodward Clyde, 1993).

Eighty-nine soil samples were collected in 1991 for metals, VOC, and SVOC analyses. These

samples included some soil that has since been excavated, treated, and redistributed at the

Site, and included samples from outside of the former Source Area. Included in the soil


2.2.3

analyses was an evaluation of background metals conditions (excluding mercury). No

evaluation of background conditions was completed for the VOC or SVOC fractions. Thirty soil

samples from the former Source Area were included and are summarized in discussions below.

Naphthalene Prior to the source control remedial action, naphthalene was detected in 2 of 30 former Source

Area soil samples, ranging from 0.18 to 110 mg/Kg. Naphthalene was detected within the

Southern Disposal Area (in 1991), which has since been excavated and thermally treated.

Concentrations in both samples exceeded the naphthalene risk-based SSL of 0.00055 mg/Kg at

a DAF of 1.

Manganese Prior to the source control remedial action, manganese was detected in all 30 former Source

Area soil samples ranging from 54 mg/Kg to 1,120 mg/Kg. Twenty-nine of the thirty detected

concentrations exceeded the EPA risk-based SSL of 57 mg/Kg (at a DAF of 1). The

background concentration was 323 mg/Kg, also exceeding the EPA risk-based SSL. Because

24 out of 30 manganese results were below the background manganese concentration, it is

reasonable to conclude that manganese in former Source Area soils is naturally occurring.

Summary of Soil Leaching Potential Evaluation Using soil data developed prior to the source control Remedial Action, the leaching potential for

the two potential COCs, naphthalene and manganese, that may affect groundwater quality were

evaluated.

Naphthalene Naphthalene was detected in the former Source Area soil in both RI and PDEI samples at

concentrations that exceeded the EPA risk-based SSL for the protection of groundwater. The

former Source Area soils may be a source of naphthalene to groundwater. However, the soil

data represent conditions prior to low-temperature thermal desorption, removal of excavated

materials for off-site disposal, and redistribution of treated soil into the excavations during the

1999 - 2000 Remedial Action. Since the Remedial Action, the treated soil has been subjected

to precipitation infiltration and weathering. It is likely that current naphthalene concentrations

are lower than during the RI and PDEI. Because there is insufficient information to determine

current soil naphthalene concentrations, further sampling is recommended.


Manganese Most of the manganese detected in the former Source Area soils during the PDEI and

throughout the study area during the RI (i.e., geometric mean concentration) are below the

background level (reported in the PDEI). Therefore, the manganese throughout the study area

is likely to be naturally occurring. These manganese concentrations exceed the EPA risk-based

SSL for the protection of groundwater, indicating the potential for naturally occurring manganese

to leach to groundwater.

Considering the highly-reduced aquifer conditions (due in part to the reductive dechlorination

processes, as well as the natural anaerobic conditions typically associated with wetland

deposits), manganese in soil can be mobilized into groundwater. Therefore, it is likely that the

naturally occurring manganese in soil is contributing to the manganese detected in the

monitoring wells. However, the elevated manganese concentrations represent elevated health

risks if the groundwater is used as a potable supply.

3.0 DIRECT CONTACT EXPOSURE TO FORMER SOURCE AREA SOILS This assessment consisted of evaluating the available RI and PDEI soil data to determine

whether SVOCs, pesticides, polychlorinated biphenyls (PCBs), and metals posed potential

direct contact risks, and to determine whether additional data will be required to characterize the

current chemical distribution in the former Source Area soils.

As noted in the RI, heavy metals in soil were a concern at the Site and elevated concentrations

of SVOCs, PCBs, and pesticides were detected; however, non-VOCs data representative of

current Site soil conditions are very limited. Soil non-VOCs data are only available from the

1986 RI and pre-design engineering investigation, prior to remedial action activities. No tests

were performed to evaluate the potential effects of low-temperature thermal treatment on non-

VOCs. The lack of current data precludes accurate evaluation of current direct contact risks

from non-VOCs in soil. However, evaluation of pre-remedial soil data is useful in determining

potential worst-case current soil concentrations.

To evaluate the maximum potential risks from direct exposure to non-VOCs in soils, pre

remediation non-VOC soil data were compared to EPA and RIDEM direct exposure screening

criteria. Soil data from the RI and the PDEI were compared to EPA RSLs for residential soils


3.1

(EPA, 2009) with screening levels for non-carcinogens adjusted to correspond to hazard indices

of 0.1 and RIDEM Residential Soils Direct Exposure Contact criteria (RIDEM, 2004).

Non-VOC Risks for RI Data from Direct Contact Soil Exposures Soil SVOCs, pesticides, PCBs, and metals data were available from the 1986 RI for the study

area. For this evaluation, it was not possible to separate the former Source Area samples from

the entire data set. The RI Report developed geometric mean soil concentrations (detected

concentrations only), which were used in this evaluation, and may under represent more

contaminated soil in the former Source Area. Table 5 presents the comparison of geometric

mean concentrations to the screening criteria.

SVOCs - The geometric mean soil concentrations of all SVOCs were less than the RIDEM Residential Soils Direct Exposure Contact criteria. The geometric mean concentrations of all

SVOCs except naphthalene were less than the EPA RSL for residential soils. For purposes of

this evaluation EPA RSLs for non-carcinogens have been adjusted to correspond to hazard

indices of 0.1. Naphthalene was detected in 11 of 66 samples. The geometric mean

concentration of naphthalene (6.93 mg/Kg) and concentrations of most of the samples with

detected naphthalene exceeded the EPA residential soil RSL of 3.9 mg/Kg.

Based on exceedances of the RSL and how frequently naphthalene was detected in RI soil samples, this soil SVOC may pose potential direct contact risks. Based on the lack of RSL exceedances for other SVOCs in RI soil sample, the other SVOCs do not represent potential direct contact risks.

Pesticides - The geometric mean soil concentrations of all pesticides, except dieldrin, were less than the RIDEM Residential Soils Direct Exposure Contact criteria and the EPA RSLs for

residential soils, adjusted to hazard indices of 0.1 for non-carcinogens. Dieldrin was detected

just once in 69 samples at 0.5 mg/Kg. That concentration exceeds both the EPA RSL for

residential soils for dieldrin of 0.03 mg/Kg and the RIDEM Residential Direct Exposure Contact

criteria of 0.04 mg/Kg.

Based on the infrequent detection of dieldrin and lack of RSL exceedances for other pesticides in the RI soil samples, pesticides in soil do not represent potential direct contact risks.


3.2

PCBs - The geometric mean soil concentration (3.87 mg/Kg) of PCBs was less than the RIDEM Residential Soils Direct Exposure Contact criteria (10 mg/Kg), but exceeded the EPA RSL for

residential soils of 0.22 mg/Kg. PCBs were detected in 5 of 78 samples.

Based on exceedance of the RSL and how frequently PCBs were detected in the RI soil samples, PCBs in soil may pose potential direct contact risks.

Metals - The geometric mean soil concentrations of all metals except arsenic were less than the RIDEM Residential Soils Direct Exposure Contact criteria. The geometric mean concentrations

of arsenic, cobalt, and iron exceeded the EPA RSL for residential soils. As noted above,

arsenic was detected in 17 of 94 samples. The mean concentration (14 mg/Kg) and all detected

soil concentrations of arsenic exceeded the EPA residential soil RSL for arsenic of 0.39 mg/Kg.

Cobalt was detected in just 2 of 93 samples. Iron was detected in all 93 samples.

Based on this assessment of RI data, arsenic in soil may represent a potential direct contact risk. Based on the low detection frequency of cobalt, this metal in soil does not represent a potential direct contact risk. Iron is not considered to represent a potential direct contact risk because the RSL is based on concentrations needed to protect against nutritional deficiency rather than toxicity. Based on the lack of RSL exceedances for RI soil data, the other metals do not represent potential direct contact risks.

Non-VOC Risks PDEI Data from Direct Contact Soil Exposures Soils SVOCs and metals data for the former Source Area are available from the PDEI. Table 6

presents the summary of data compared to the screening criteria.

SVOCs - The maximum concentrations from the former Source Area soil samples of 1,2,4trichlorobenzene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene,

benzo(g,h,i)pyrene, bis(2-ethylhexyl)phthalate, chrysene, and naphthalene exceeded the

RIDEM Residential Soils Direct Exposure Contact [DEC] criteria.

The maximum concentrations of 1,2,4-trichlorobenzene, benzo(a)anthracene, benzo(a)pyrene,

benzo(b)fluoranthene, bis(2-ethylhexyl)phthalate, and naphthalene also exceeded the EPA RSL


for residential soils. For purposes of this evaluation EPA RSLs for non-carcinogens have been

adjusted to correspond to HIs of 0.1.

1,2,4-Trichlorobenzene was detected in 4 of 30 samples at concentrations ranging from 14 to

120 mg/Kg with each of these exceeding the adjusted EPA RSL of 8.7 mg/Kg.

Benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)pyrene, chrysene, and

naphthalene were each detected in 2 of 30 samples. Bis(2-ethylhexyl)phthalate was detected in

12 of 30 samples.

Based on exceedances of RSLs and RIDEM Residential Soil DECs, and frequency of detections, the eight SVOCs in soil discussed above may represent potential direct contact risks.

Metals - The maximum concentrations from the former Source Area soil samples of antimony, beryllium, lead, and manganese exceeded the RIDEM Residential Soils Direct Exposure

Contact criteria.

The maximum concentrations of antimony, arsenic, cobalt, copper, iron, lead, and manganese

exceeded the EPA RSL for residential soils with screening levels for non-carcinogens adjusted

to correspond to HIs of 0.1.

Antimony was detected in 5 of 30 samples. Arsenic was detected in 25 of 30 samples.

Beryllium was detected in 26 of 30 samples. Cobalt was detected in 29 of 30 samples. Copper

was detected in 30 of 30 samples. Iron was detected in 30 of 30 samples. Lead was detected

in 28 of 30 samples. Manganese was detected in 30 of 30 samples.

Based on both the RI and PDEI results, arsenic appears to be naturally occurring in the soil;

most detected soil concentrations are below the background concentration of 5 mg/Kg. Arsenic,

while present in numerous soil samples, was reported above the background concentration in

only 3 of 93 samples during the PDEI. Iron is not considered to represent a potential direct

contact risk because the RSL is based on nutritional deficiency rather than toxicity. The

manganese throughout the study area is likely to be naturally occurring, based on the

comparison with background concentrations. Therefore, these three metals do not represent site-related potential direct contact risks.


3.3

Based on exceedances of RSLs and RIDEM Residential Soil DECs and frequency of detections in the PDEI soil data, the five metals (antimony, beryllium, cobalt, copper, and lead) discussed above may represent potential direct contact risks.

Summary of Non-VOC Risks from Direct Contact Soil Exposures The evaluation of RI and PDEI data are summarized below.

SVOCs - Based on the combined assessment of RI and PDEI data, the exceedances of RSLs and RIDEM Residential Soil DECs, and frequency of detections indicate that the eight

SVOCs (1,2,4-trichlorobenzene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene,

benzo(g,h,i)pyrene, bis(2-ethylhexyl)phthalate, chrysene, and naphthalene) in soil discussed

above may represent potential direct contact risks.

However, the soil in the former Source Area has since been thermally treated using low-

temperature desorption and the backfilled materials have been subject to additional precipitation

infiltration and leaching. The current SVOC concentrations in soil are anticipated to be lower.

Because the data used for the assessments represent pre-Remedial Action conditions, there is insufficient information to determine current SVOCs concentrations and potential direct contact risk, further sampling is recommended.

Pesticides – While evaluation of RI data indicated that pesticides in soil do not represent potential direct contact risks, the RI geometric mean concentrations are not representative of

former Source Area conditions. The RI data are representative of study area rather than the

former Source Area. No PDEI data were available. Therefore, it is recommended that

further sampling be conducted to obtain current pesticides data for the former Source Area.

PCBs – Evaluation of the RI data indicated PCBs in soil may pose potential direct contact risks. The RI data are not representative of former Source Area conditions and no PDEI data were

available. Therefore, it is recommended that further sampling be conducted to obtain current PCBs data for the former Source Area.


Metals – Based on the combined assessment of RI and PDEI data, the exceedances of RSLs and RIDEM Residential Soil DECs, and frequency of detections indicate that the five metals

(antimony, beryllium, cobalt, copper, and lead) in soil discussed above may represent potential

direct contact risks.

However, the RI and PDEI data are not representative of current soil conditions in the former

Source Area because the soil had been treated, mixed, and backfilled during the Remedial

Action and subject to additional precipitation infiltration and leaching. The current distribution of

metal concentrations in soil are anticipated to be altered. Because there is insufficient information to determine current metals concentrations and potential direct contact risks, further sampling is recommended.

4.0 CONCLUSIONS AND RECOMMENDATONS Nobis reviewed available RI and PDEI information to evaluate whether contaminants other than

VOCs in the former Source Area soil may represent potential leaching threats to groundwater

quality, or may pose potential direct contact threats.

Conclusions resulting from the evaluations are summarized below:

• Initial evaluation of non-VOC risks from groundwater indicated that BCEE, naphthalene,

arsenic, and manganese in groundwater posed potential risks under a drinking water

scenario.

• Evaluation of the distribution of these chemicals in groundwater and the soil leaching

potential indicated the following:

- BCEE was not detected in the former Source Area groundwater in the most recent

sampling. Therefore, the former Source Area soil is not a current source of BCEE to

groundwater.

- The source of the BCEE detected downgradient of the former Source Area is

unknown.


- Naphthalene detected in the former Source Area soil may be a current source to

overburden groundwater.

- While arsenic was detected in many soil samples, arsenic was not detected in the

former Source Area groundwater during the most recent sampling event. Therefore,

it is reasonable to conclude that the former Source Area soil is not a source of

arsenic to groundwater.

- Manganese in soil is believed to be naturally occurring. The on-going reductive

dechlorination of chlorinated solvents from the Davis Liquid Waste Site has mobilized

the naturally occurring manganese resulting in the elevated manganese

concentrations in groundwater within the VOC plumes.

• Evaluation of the direct contact exposures to the former Source Area soils indicated the

following:

- SVOCs - Eight SVOCs (1,2,4-trichlorobenzene, benzo(a)anthracene, benzo(a)pyrene,

benzo(b)fluoranthene, benzo(g,h,i)pyrene, bis(2-ethylhexyl)phthalate, chrysene, and

naphthalene) in soil may represent potential direct contact risks.

- Pesticides – Evaluation of RI data indicated that pesticides in soil do not represent

potential direct contact risks; however, the RI data (using the geometric mean values

of all RI samples) are not representative of and may underestimate former Source

Area conditions.

- PCBs – Evaluation of the RI data indicated PCBs in soil may pose potential direct

contact risks; however, the RI data are not representative of former Source Area

conditions.

- Metals – Five metals (antimony, beryllium, cobalt, copper, and lead) in soil may

represent potential direct contact risks.

-


• Soil currently situated in the former Source Area had been previously excavated,

thermally treated using low-temperature desorption, mixed, and backfilled into the

excavation. These soils have also been subjected to additional precipitation infiltration

and leaching, which may have decreased some contaminant concentrations. Therefore,

the current distribution of SVOCs, pesticides, PCBs, and metals within the former

Source Area soils is unknown. The current potential for leaching (naphthalene) and

direct contact risks (SVOCs, pesticides, PCBs, and metals) cannot be evaluated.

Recommendations based on the evaluation findings include the following:

• Further soil sampling is recommended to obtain current SVOCs, pesticides, PCBs, and

metals data in the former Source Area to better assess current potential leaching and

direct contact exposures.

• Additional sampling would be performed as part of the pre-design investigation (PDI) for

the Remedial Action.

• For the FFS, no remedial alternatives should be developed to address the unsaturated

former Source Area soils. Once the PDI is completed, the need to address potential

non-VOCs contaminants can be revisited.

• The FFS will address the saturated soil in the former Source Area, which contains VOCs

that are the current sources of groundwater contamination, as part of remedial

alternatives that address contaminated groundwater.


Table 1 Risk Estimates for Overburden Groundwater SVOCs Data - June 2003

Davis Liquid Waste Superfund Site Smithfield, Rhode Island

CAS Number Chemical

Minimum Conc.

Maximum Conc.

Average Conc. Units Location of Maximum

Detection Frequency

EPA Regional Screening Levels for Tap Water

RIDEM GA/MCL Objectives

Cancer Risk estimate

Hazard Index estimate

(2)

Criteria Value

Frequency of Detects

Above Criteria

Criteria Value

(1)


Above Criteria

(3) (4)

95-95-4 2,4,5-Trichlorophenol 10 10 0.50 ug/L OW-094-O 1/20 370 N 0/20 NA 0/20 NA 2.7E-03 88-06-2 2,4,6-Trichlorophenol 10 10 0.50 ug/L OW-094-O 1/20 6.1 C 1/20 NA 0/20 1.6E-06 NA 120-83-2 2,4-Dichlorophenol 10 10 0.50 ug/L OW-094-O 1/20 11 N 0/20 NA 0/20 NA 9.1E-02 105-67-9 2,4-Dimethylphenol 1 10 1.1 ug/L OW-094-O 3/20 73 N 0/20 NA 0/20 NA 1.4E-02 51-28-5 2,4-Dinitrophenol 58 58 2.9 ug/L OW-094-O 1/20 7.3 N 1/20 NA 0/20 NA 7.9E-01 95-57-8 2-Chlorophenol 10 10 0.50 ug/L OW-094-O 1/20 18 N 0/20 NA 0/20 NA 5.6E-02 91-57-6 2-Methylnaphthalene 1 4 0.35 ug/L OW-094-O 3/20 15 N 0/20 NA 0/20 NA 2.7E-02 95-48-7 2-Methylphenol 10 10 0.50 ug/L OW-094-O 1/20 180 N 0/20 NA 0/20 NA 5.6E-03 88-75-5 2-Nitrophenol 10 10 0.50 ug/L OW-094-O 1/20 NA 0/20 NA 0/20 NA NA 534-52-1 4,6-Dinitro-2-methylphenol 24 24 1.2 ug/L OW-094-O 1/20 0.37 N 1/20 NA 0/20 NA 6.5E+00 59-50-7 4-Chloro-3-methylphenol 10 10 0.50 ug/L OW-094-O 1/20 NA 0/20 NA 0/20 NA NA 106-44-5 4-Methylphenol 2 15 1.4 ug/L OW-109-O 3/20 18.0 N 0/20 NA 0/20 NA 8.3E-02 100-02-7 4-Nitrophenol 48 48 2.4 ug/L OW-094-O 1/20 NA 0/20 NA 0/20 NA NA 98-86-2 Acetophenone 3 3 0.15 ug/L OW-094-O 1/20 370 N 0/20 NA 0/20 NA 8.1E-04 111-44-4 Bis(2-chloroethyl)ether 2 2 0.10 ug/L OW-043 1/20 0.012 C 1/20 NA 0/20 1.7E-04 NA 91-20-3 Naphthalene 3 5 0.60 ug/L OW-094-O 3/20 0.14 C 3/20 20 0/20 3.6E-05 NA 98-95-3 Nitrobenzene 5 5 0.25 ug/L OW-052 1/20 0.12 C 1/20 NA 0/20 4.2E-05 NA 87-86-5 Pentachlorophenol 4 4 0.20 ug/L OW-094-O 1/20 0.56 C 1/20 1 1/20 7.1E-06 NA 108-95-2 Phenol 10 10 0.50 ug/L OW-094-O 1/20 1100 N 0/20 NA 0/20 NA 9.1E-04 Notes: Total risks from SVOCs 2.5E-04 7.6E+00

NA - Values for cited substances are not available.

Data from ESS 2006, postive detect analytes shown.

(1) - RIDEM Rules and Regulations for the Investigation and Remediation of Hazardous Materials Releases; Table 3 GA Groundwater Objectives

(2) - EPA Regional Screening Levels April 2009; Tap Water Scenario. C = Cancerous; N = Noncancerous. Non-cancer based values have been adjusted to correspond to HQ=0.1.

(3) - Cancer risk = maximum concentration/cancer based screening value x 10-6

(4) - Hazard Index = maximum concentration/non-cancer based screening value x 0.1

analyte that exceeds screening criteria or poses excess risk.

MA-2181-2009-F Nobis Engineering, Inc.

Table 2 Risk Estimates for Bedrock Groundwater SVOCs Data June 2003


CAS Number Chemical

Minimum Conc.

Maximum Conc.

Average Conc. Units Location of Maximum

Detection Frequency





(2)

Criteria Value


Above Criteria

Criteria Value

(1)


Above Criteria

(3) (4)

105-67-9 2,4-Dimethylphenol 2 2 0.09 ug/L OW-094-R 1/21 73 N 0/21 NA 0/21 NA 2.7E-03 51-28-5 2,4-Dinitrophenol 60 60 2.7 ug/L OW-112-R 1/21 7.3 N 1/21 NA 0/21 NA 8.2E-01 91-57-6 2-Methylnaphthalene 2 2 0.09 ug/L OW-101-R 1/21 15 N 0/21 NA 0/21 NA 1.3E-02 95-48-7 2-Methylphenol 1 1 0.05 ug/L OW-094-R 1/21 180 N 0/21 NA 0/21 NA 5.6E-04 106-44-5 4-Methylphenol 7 7 0.32 ug/L OW-101-R 1/21 18.0 N 0/21 NA 0/21 NA 3.9E-02

208-96-8 Acenaphthylene 10 10 1.4 ug/L OW-105-R, OW-094-R, OW-101-R 3/21 NA 0/21 NA 0/21 NA NA

98-86-2 Acetophenone 3 3 0.14 ug/L OW-101-R 1/21 370 N 0/21 NA 0/21 NA 8.1E-04 111-44-4 Bis(2-chloroethyl)ether 4 25 2.1 ug/L OW-101-R 4/21 0.012 C 4/21 NA 0/21 2.1E-03 NA 91-20-3 Naphthalene 5 5 0.23 ug/L OW-101-R 1/21 0.14 C 1/21 20 0/21 3.6E-05 NA 106-47-8 p-Chloroaniline 10 10 0.45 ug/L OW-112-R 1/21 0.34 C 1/21 NA 0/21 2.9E-05 NA 87-86-5 Pentachlorophenol 3 3 0.14 ug/L OW-112-R 1/21 0.56 C 1/21 1 1/21 5.4E-06 NA 108-95-2 Phenol 1 3 0.18 ug/L OW-094-R 2/21 1100 N 0/21 NA 0/21 NA 2.7E-04 Notes: Total risks from SVOCs 2.2E-03 8.8E-01









Table 3 Risk Estimates for Overburden Groundwater Metals Data Fall 2004


CAS Number Chemical

Minimum Conc.

Maximum Conc.

Average Conc. Units

Location of Maximum

Detection Frequency





(2)

Criteria Value

Frequency of Detects Above Criteria (1)

Criteria Value


Above Criteria

(3) (4)

7429-90-5 Aluminum 25 348 17.8 ug/L OW-055 2/20 3700 N 0/20 NA 0/20 9.41E-03 7440-38-2 Arsenic 19.2 19.2 0.96 ug/L OW-105-O 1/20 0.045 C 1/20 10 1/20 4.27E-04 7440-39-3 Barium 5.8 56.9 20.6 ug/L OW-055 20/20 730 N 0/20 2000 0/20 7.79E-03 7440-70-2 Calcium 1730 34600 11977 ug/L OW-043 20/20 NA 0/20 NA 0/20 7440-48-4 Cobalt 5.5 9.6 0.72 ug/L OW-034 2/20 1.1 N 2/20 NA 0/20 8.73E-01 7439-89-6 Iron 221 25600 6197 ug/L OW-052 14/20 2600 N 8/20 NA 0/20 9.85E-01 7439-92-1 Lead 3.3 3.3 0.17 ug/L OW-109-O 1/20 15 0/20 15 0/20 7439-95-4 Magnesium 422 4100 2130 ug/L OW-021 20/20 NA 0/20 NA 0/20 7439-96-5 Manganese 24.3 4780 1424 ug/L OW-94-O 20/20 88 N 16/20 NA 0/20 5.43E+00 7439-97-6 Mercury (elemental) 33.1 33.1 1.7 ug/L OW-045 1/20 0.057 N 1/20 2 1/20 5.81E+01 7440-09-7 Potassium 530 5520 2675 ug/L OW-102-O 20/20 NA 0/20 NA 0/20 7440-23-5 Sodium 2350 19800 6343 ug/L OW-103-O 20/20 NA 0/20 NA 0/20 7440-66-6 Zinc 134 155 13.8 ug/L OW-055 2/20 1100 N 0/20 NA 0/20 1.41E-02 Notes: Total risks from Metals 4.27E-04 6.54E+01

All concentrations are reported in ug/L









Table 4 Risk Estimates for Bedrock Groundwater Metals Data Fall 2004


CAS Number Chemical

Minimum Conc.

Maximum Conc.

Average Conc. Units

Location of Maximum

Detection Frequency





(2)

Criteria Value

Frequency of Detects Above Criteria (1)

Criteria Value


Above Criteria

(3) (4)

7429-90-5 Aluminum 237 2340 152 ug/L OW-109-R 2/17 3700 N 0/17 NA 0/17 NA 6.32E-02 7440-38-2 Arsenic 11.8 17.6 1.7 ug/L OW-109-R 2/17 0.045 C 2/17 10 2/17 3.91E-04 NA 7440-39-3 Barium 5 332 50 ug/L OW-041 12/17 730 N 0/17 2000 0/17 NA 4.55E-02 7440-70-2 Calcium 7750 270000 57085 ug/L OW-112-R 17/17 NA 0/17 NA 0/17 NA NA 7439-89-6 Iron 266 22800 2755 ug/L OW-101-R 10/17 2600 N 4/17 NA 0/17 NA 8.77E-01 7439-92-1 Lead 3.9 3.9 0.23 ug/L OW-109-R 1/17 15 0/17 15 0/17 NA NA 7439-95-4 Magnesium 352 25900 3812 ug/L OW-103-R 17/17 NA 0/17 NA 0/17 NA NA 7439-96-5 Manganese 13.3 7960 1122 ug/L OW-101-R 13/17 88 N 8/17 NA 0/17 NA 9.05E+00 7440-09-7 Potassium 1510 15000 4562 ug/L OW-103-R 17/17 NA 0/17 NA 0/17 NA NA 7440-23-5 Sodium 4090 266000 30698 ug/L OW-103-R 17/17 NA 0/17 NA 0/17 NA NA 7440-66-6 Zinc 117 117 6.9 ug/L OW-102-R 1/17 1100 N 0/17 NA 0/17 NA 1.06E-02 Notes: Total risks from Metals 3.91E-04 1.00E+01

All concentrations are reported in ug/L









Table 5 Summary of Non-VOCs RI Soil Data Davis Liquid Waste Superfund Site

Smithfield, Rhode Island

Soil Direct Contact Screening

Chemical Geometric

Mean Conc. 1 Units Detection Frequency

Screening Value

Screening Value Source 2

Screening Value

Screening Value Source 2

SVOCs

1,2,4-Trichlorobenzene 4.74 mg/Kg 11/69 96 RI DEC-Res 8.7 EPA RSL 2-Methylnaphthalene 9.11 mg/Kg 7/69 123 RI DEC-Res 31 EPA RSL 4-Methylphenol 6.7 mg/Kg 1/75 NL RI DEC-Res 31 EPA RSL bis(2-Ethylhexyl)phthalate 8.03 mg/Kg 20/54 NL RI DEC-Res 35 EPA RSL Butyl benzyl phthalate 2.58 mg/Kg 9/67 NL RI DEC-Res 260 EPA RSL Chrysene 2.4 mg/Kg 1/69 NL RI DEC-Res 15 EPA RSL Di-n-butyl phthalate 8.5 mg/Kg 3/63 NL RI DEC-Res 610 EPA RSL Di-n-octyl phthalate 4.8 mg/Kg 6/68 NL RI DEC-Res NL EPA RSL Fluoranthene 0.987 mg/Kg 2/69 20 RI DEC-Res 230 EPA RSL Naphthalene 6.93 mg/Kg 11/66 54 RI DEC-Res 3.9 EPA RSL n-Nitrosodiphenylamine 4.72 mg/Kg 15/69 NL RI DEC-Res 99 EPA RSL Pentachlorophenol 2.1 mg/Kg 1/69 5.3 RI DEC-Res 3 EPA RSL Phenanthrene 5.565 mg/Kg 10/69 40 RI DEC-Res NL EPA RSL Phenol 114 mg/Kg 2/69 6,000 RI DEC-Res 1,800 EPA RSL Pyrene 6.36 mg/Kg 5/70 13 RI DEC-Res 170 EPA RSL

Pesticides/PCBs

4,4'-DDD 0.25 mg/Kg 3/69 NL RI DEC-Res 2 EPA RSL

4,4'-DDE 0.57 mg/Kg 1/75 NL RI DEC-Res 1.4 EPA RSL

4,4'-DDT 0.014 mg/Kg 1/77 NL RI DEC-Res 1.7 EPA RSL

alpha-(HCCH) 0.189 mg/Kg 1/69 NL RI DEC-Res NL EPA RSL

Dieldrin 0.5 mg/Kg 1/69 0.04 RI DEC-Res 0.03 EPA RSL

Heptachlor epoxide 0.003 mg/Kg 1/69 NL RI DEC-Res 0.053 EPA RSL

PCBs 3.87 mg/Kg 5/78 10 RI DEC-Res 0.22 EPA RSL

Metals

Aluminum 4926 mg/Kg 93/93 NL RI DEC-Res 7700 EPA RSL Arsenic 14 mg/Kg 17/94 7 RI DEC-Res 0.39 EPA RSL Barium 207.9 mg/Kg 9/104 5,500 RI DEC-Res 1500 EPA RSL Cadmium 3.95 mg/Kg 17/103 39 RI DEC-Res 7 EPA RSL Chromium 14.3 mg/Kg 52/109 1,400 RI DEC-Res 12000 EPA RSL Cobalt 27.9 mg/Kg 2/93 NL RI DEC-Res 2.3 EPA RSL Copper 55.26 mg/Kg 56/104 3,100 RI DEC-Res 310 EPA RSL Iron 10049 mg/Kg 93/93 NL RI DEC-Res 5500 EPA RSL Lead 18.6 mg/Kg 70/73 150 RI DEC-Res 400 EPA RSL Manganese 150 mg/Kg 92/95 390 RI DEC-Res 180 EPA RSL Mercury 0.32 mg/Kg 15/82 23 RI DEC-Res 0.43 EPA RSL Nickel 81.7 mg/Kg 8/102 1,000 RI DEC-Res 150 EPA RSL Selenium 2.9 mg/Kg 1/89 390 RI DEC-Res 39 EPA RSL Sodium 1404 mg/Kg 3/99 NL RI DEC-Res NL EPA RSL Tin 58.4 mg/Kg 21/93 NL RI DEC-Res 4700 EPA RSL Zinc 71.3 mg/Kg 91/94 6,000 RI DEC-Res 2300 EPA RSL

Notes: 1. Data provided by the Remedial Investigation produced by CDM in 1986, for entire Study Area. 2. Screening Values derived from the following sources:

- EPA RSL: Risk-Based SL for Residential Soil (Cancer Risk =1E-06 or Hazard Index =1.0) from EPA Regional Screening Levels. Source: http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/index.htm. - RI DEC-Res - Rhode Island Department of Environmental Management Rules and Regulations for the Investigation and Remediation of Hazardous Materials Releases; Residential Direct Exposure Category - NL - no limit established

Analyte and its exceedances of soil screening criteria are highlighted by yellow boxes


http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/index.htm

Table 6 Summary of Non-VOCs PDEI Soil Data Collected From the Former Source Area


Chemical Minimum Conc. 1

Maximum Conc. 1

Units Detection Frequency

Soil Direct Contact Screening 2

Screening Value

Screening Value

Source

Freq. above RIDEM

DEC-Res

Screening Value

Screening Value

Source

Freq. above EPA Screening

Level

Metals

Aluminum 1,520 13,100 mg/Kg 30/30 NL - - 7,700 EPA RSL 0/30 Antimony 2.4 56 mg/Kg 5/30 10 RI DEC-Res 1/30 3.1 EPA RSL 1/30 Arsenic 0.045 3.8 mg/Kg 25/30 7 RI DEC-Res 0/30 0.39 EPA RSL 25/30 Barium 14.3 392 mg/Kg 30/30 5,500 RI DEC-Res 0/30 1,500 EPA RSL 0/30 Beryllium 0.23 0.94 mg/Kg 26/30 0.4 RI DEC-Res 12/30 16 EPA RSL 0/30 Cadmium 0.69 2.5 mg/Kg 13/30 39 RI DEC-Res 0/30 7 EPA RSL 0/30 Calcium 189 26,100 mg/Kg 30/30 NL - - NL - -Chromium 2.2 119 mg/Kg 30/30 1,400 RI DEC-Res 0/30 12,000 EPA RSL 0/30 Cobalt 0.64 8.4 mg/Kg 29/30 NL RI DEC-Res 0/30 2.3 EPA RSL 18/30 Copper 4 353 mg/Kg 30/30 3,100 RI DEC-Res 0/30 310 EPA RSL 1/30 Iron 4,790 26,500 mg/Kg 30/30 NL - - 5,500 EPA RSL 29/30 Lead 2 2,710 mg/Kg 28/30 150 RI DEC-Res 4/30 400 EPA RSL 2/30 Magnesium 496 6,130 mg/Kg 30/30 NL - - NL - -Manganese 54 1,120 mg/Kg 30/30 390 RI DEC-Res 2/30 180 EPA RSL 17/30 Mercury 0.26 0.41 mg/Kg 4/30 23 RI DEC-Res 0/30 0.43 EPA RSL 0/30 Nickel 1 31 mg/Kg 30/30 1,000 RI DEC-Res 0/30 150 EPA RSL 0/30 Potassium 742 3,050 mg/Kg 30/30 NL - - NL - -Silver 0.23 0.45 mg/Kg 5/30 200 RI DEC-Res 0/30 39 EPA RSL 0/30 Sodium 36.6 607 mg/Kg 14/30 NL - - NL - -Tin 4.1 6.2 mg/Kg 6/30 NL - - 4,700 EPA RSL 0/30 Vanadium 3.3 29.8 mg/Kg 30/30 550 RI DEC-Res 0/30 39 EPA RSL 0/30 Zinc 21.2 486.0 mg/Kg 30/30 6,000 RI DEC-Res 0/30 2,300 EPA RSL 0/30

SVOCs

1,2,4-Trichlorobenzene 14 120 mg/Kg 4/30 96 RI DEC-Res 1/30 8.7 EPA RSL 4/30 1,2-Dichlorobenzene 0.075 17 mg/Kg 7/30 510 RI DEC-Res 0/30 200 EPA RSL 0/30 2,6-Dinitrotoluene 5.2 5 mg/Kg 1/30 NL - - 6.1 EPA RSL 0/30 2-Methylnaphthalene 5.90 9 mg/Kg 5/30 123 RI DEC-Res 0/30 31 EPA RSL 0/30 Benzo(a)anthracene 0.17 1.6 mg/Kg 2/30 0.9 RI DEC-Res 1/30 0.15 EPA RSL 2/30 Benzo(a)pyrene 0.22 1.5 mg/Kg 2/30 0.4 RI DEC-Res 1/30 0.015 EPA RSL 2/30 Benzo(b)fluoranthene 0.48 2.8 mg/Kg 2/30 0.9 RI DEC-Res 1/30 0.15 EPA RSL 2/30 Benzo(g,h,i)perylene 0.31 1.7 mg/Kg 2/30 0.8 RI DEC-Res 1/30 NL - --Benzoic Acid 0.075 0.31 mg/Kg 8/30 NL - - 24,000 EPA RSL 0/30 bis(2-ethylhexyl)phthalate 0.068 63 mg/Kg 12/30 46 RI DEC-Res 2/30 35 EPA RSL 3/30 Butylbenzylphthalate 5.7 100 mg/Kg 3/30 NL - - 260 EPA RSL 0/30 Chrysene 0.21 1.7 mg/Kg 2/30 0.4 RI DEC-Res 1/30 15 EPA RSL 0/30 di-N-butylphthalate 0 30 mg/Kg 4/30 NL - - 610 EPA RSL 0/30 Fluoranthene 0.20 1.9 mg/Kg 2/30 20 RI DEC-Res 0/30 230 EPA RSL 0/30 Naphthalene 0.18 110.00 mg/Kg 2/30 54 RI DEC-Res 1/30 3.9 EPA RSL 1/30 n-Nitrosodiphenylamine 0.17 3.900 mg/Kg 3/30 NL - - 99 EPA RSL 0/30 Pentachlorophenol 0.045 0.045 mg/Kg 1/30 5.3 RI DEC-Res 0/30 3 EPA RSL 0/30 Phenanthrene 0.86 0.98 mg/Kg 2/30 40 RI DEC-Res 0/30 NL - 0/30 Pyrene 0.22 2.1 mg/Kg 2/30 13 RI DEC-Res 0/30 170 EPA RSL 0/30 Notes: 1. Data provided by the Final Pre-Design Engineering Report II, October, 1993. 2. Screening Values derived from the following sources:

- EPA RSL: Risk-Based SL for Residential Soil (Cancer Risk =1E-06 or Hazard Index =1.0) from EPA Regional - RI DEC-Res - Rhode Island Department of Environmental Management Rules and Regulations for the - NL - no limit established

Exceedances of soil screening criteria are highlighted by yellow boxes


460

450

NOTES:

1. Surface contours based on Round 6 Report (ESS, 2006). 2. Limit of disposal areas are based on Remedial Action Report (LEA, 2001). 3. SVOC data obtained from Spring 2003 round of groundwater sampling. 4. Regional Screening Levels (RSL) obtained from http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm

Brook

Latham

4J

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400450460 470

390380

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OW-083

OW-081

OW-055

OW-054 OW-052 OW-051

OW-046OW-045 OW-043

OW-038

OW-034

OW-024

OW-021

OW-012

OW-011

OW-008

OW-006

OW-304-O

OW-303-OOW-302-O

OW-301-O

OW-300-O OW-200-OOW-112-O

OW-111-O

OW-109-O

OW-107-O

OW-105-O

OW-103-O

OW-102-O

OW-096-OOW-095-O

OW-094-O

OW-093-O

CHECKED BY: LCPREPARED BY: DFM

PROJECT NO. 80028 DATE: 09/08/09 Rev. 00

FIGURE 1

Nobis Engineering, Inc. 585 Middlesex Street

Lowell, MA 01851 (978) 683-0891

www.nobisengineering.com

300 0 300150 Feet

APPROXIMATE SCALE

LegendOverburden Monitoring Well Used for Sample Collection

Overburden Monitoring Well Not Used for Sample Collection

Former Northern (NDA) & Southern Disposal Areas (SDA)

Approximate Limit of Former Source Area

Approximate Stream Location

Approximate Pond Location

Approximate Wetland Areas

Approximate Surface Contour

Approximate Limit of 1999 PDI Grid Soil Sampling

Overburden Monitoring Well Used for Sample Collection With Detections of bis(2-Chloroethyl)ether or Naphthalene

EXTENT OF SPRING 2003 OVERBURDEN GROUNDWATER SVOC CONTAMINATION

DAVIS LIQUID WASTE SITE SMITHFIELD, RHODE ISLAND

R:\8

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SVOCs Data Color Scheme All data in ug/L

bis(2-Chloroethyl)etherNaphthalene 256J S ubs tanc e M CL RS L

bis (2-Chloroethy l)ether - 0.012 Naphthalene - 0.14

460

450

NOTES: 1. Surface contours based on Round 6 Report (ESS, 2006). 2. Limit of disposal areas are based on Remedial Action Report (LEA, 2001). 3. SVOC data obtained from June 2003 round of groundwater sampling.

Latham

Brook

255J

11

7J

4J

410

420

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430

400450460 470

390380

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450 430

460

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460

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OW-085

OW-084

OW-082

OW-080

OW-079

OW-077

OW-041

OW-036

OW-033

OW-025

OW-007

OW-201-R

OW-200-ROW-112-R

OW-111-R

OW-110-R

OW-109-R

OW-107-R

OW-105-R

OW-103-R

OW-102-R

OW-101-R

OW-096-ROW-095-R

OW-094-R



FIGURE 2 EXTENT OF SPRING 2003 BEDROCK

GROUNDWATER SVOC CONTAMINATION DAVIS LIQUID WASTE SITE

SMITHFIELD, RHODE ISLANDNobis Engineering, Inc. 585 Middlesex Street

Lowell, MA 01851 (978) 683-0891


300 0 300150 Feet

APPROXIMATE SCALE

LegendBedrock Monitoring Well Used for Sample Collection

Bedrock Monitoring Well Not Used for Sample Collection








Bedrock Monitoring Well Used for Sample Collection With Detections of bis(2-Chloroethyl)ether or Naphthalene

SVOCs Data Color Scheme All data in ug/L

bis(2-Chloroethyl)etherNaphthalene 256J S ubs tanc e M CL RS L

bis (2-Chloroethy l)ether - 0.012 Naphthalene - 0.14

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L

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atham

240

19.21,340

84.626.1

702

118

4,180

1,5103,9404,070

2,690 1,1302,560

4,780

534 51.7

88.3

123

24.3

282 410

420

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430

400450460 470

390380

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OW-083

OW-081

OW-055

OW-054

OW-052 OW-051

OW-046

OW-045 OW-043

OW-038

OW-034

OW-024

OW-021

OW-012

OW-011

OW-008

OW-006

OW-304-O

OW-303-OOW-302-O OW-301-O

OW-300-O OW-200-O

OW-112-O

OW-111-O

OW-109-O

OW-107-O

OW-105-O

OW-103-O

OW-102-O

OW-096-OOW-095-O

OW-094-O

OW-093-O



FIGURE 3


Lowell, MA 01851 (978) 683-0891


300 0 300150 Feet

APPROXIMATE SCALE

LegendOverburden Monitoring Well Used for Sample Collection

Overburden Monitoring Well Not Used for Sample Collection








Overburden Monitoring Well Used for Sample Collection With Detections of Arsenic and Manganese

EXTENT OF FALL 2004 OVERBURDEN GROUNDWATER METALS CONTAMINATION


S ubs tanc e M CL RS L A rs enic 10 0.045 M anganes e 50 880

NOTES: 1. Surface contours based on Round 6 Report (ESS, 2006). 2. Limit of disposal areas are based on Remedial Action Report (LEA, 2001). 3. Arsenic and manganese data obtained from Fall 2004 round of groundwater sampling. 4. Source: http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm 5. MCL value cited for Manganese is a secondary drinking water value, not a primary MCL.

Metals Data Color Scheme All data in ug/L

ArsenicManganese 19.21,340

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460

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NOTES: 1. Surface contours based on Round 6 Report (ESS, 2006). 2. Limit of disposal areas are based on Remedial Action Report (LEA, 2001). 3. Arsenic and manganese data obtained from Fall 2004 round of groundwater sampling. 4. Maximum Contaminant Limit (MCL) and Regional Screening Level (RSL) values obtained from http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm 5. MCL value cited for Manganese is a secondary drinking water value, not a primary MCL.

Latham

Brook

15.4J

7,960

1,600

11.84,850 2,320

412

3,050 249 147

47.7J

17.619.7J13.3J

686

21.1J

410

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400450460 470

390380

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410

410

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450 OW-086

OW-085

OW-084

OW-082

OW-080

OW-079

OW-077

OW-041

OW-036

OW-033

OW-025

OW-007

OW-202-R

OW-201-R

OW-200-ROW-112-R

OW-111-R

OW-110-R

OW-109-R

OW-107-R

OW-105-R

OW-103-R

OW-102-R

OW-101-R

OW-096-ROW-095-R

OW-094-R



FIGURE 4 EXTENT OF FALL 2004 BEDROCK

GROUNDWATER ARSENIC & MANGANESE CONTAMINATION



Lowell, MA 01851 (978) 683-0891


300 0 300150 Feet

APPROXIMATE SCALE

LegendBedrock Monitoring Well Used for Sample Collection

Bedrock Monitoring Well Not Used for Sample Collection








Bedrock Monitoring Well Used for Sample Collection With Detections of Arsenic and/or Manganese

S ubs tanc e M CL RS L A rs enic 10 0.045 M anganes e 50 880

Metals Data Color Scheme All data in ug/L

ArsenicManganese 19.21,340

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TRANSMITTAL LETTER1.0 INTRODUCTION2.0 LEACHING OF SVOCs AND METALS TO GROUNDWATER2.1 Non-VOC Groundwater Risks2.1.1 SVOCs Risk Evaluation Summary2.1.2 Distribution of SVOCs in Groundwater2.1.3 Metals Risk Evaluation Summary2.1.4 Distribution of Metals in Groundwater

2.2 Evaluation of Soil Leaching Potential2.2.1 Remedial Investigation Soil Data2.2.2 Pre-Design Engineering Investigation Soil Data2.2.3 Summary of Soil Leaching Potential Evaluation

3.0 DIRECT CONTACT EXPOSURE TO FORMER SOURCE AREA SOILS3.1 Non-VOC Risks for RI Data from Direct Contact Soil Exposures3.2 Non-VOC Risks PDEI Data from Direct Contact Soil Exposures3.3 Summary of Non-VOC Risks from Direct Contact Soil Exposures

4.0 CONCLUSIONS and RECOMMENDATONSTABLES1 - Risk Estimates for Overburden Groundwater SVOCs Data - June 20032 - Risk Estimates for Bedrock Groundwater SVOCs Data June 20033 - Risk Estimates for Overburden Groundwater Metals Data Fall 20044 - Risk Estimates for Bedrock Groundwater Metals Data Fall 20045 - Summary of Non-VOCs RI Soil Data6 - Summary of Non-VOCs PDEI Soil Data Collected From the Former Source Area

FIGURES1 - Extent of Spring 2003 Overburden groundwater SVOC Contamination2 - Extent of Spring 2003 Bedrock Groundwater SVOC Contamination3 - Extent of Fall 2004 Overburden Groundwater Metals Contamination4 - Extent of Fall 2004 Bedrock Groundwater Arsenic & Manganese Contamination

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EVALUATION OF NON-VOLATILE ORGANIC COMPOUNDS ...Tel (978) Nobis Engineering, Inc. 585 Middlesex...

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Transcript of EVALUATION OF NON-VOLATILE ORGANIC COMPOUNDS ...Tel (978) Nobis Engineering, Inc. 585 Middlesex...