Phase III MCP Report
181 North Washington Street, Boston, MA
AEG Project # 1667, MADEP RTN 3-12127
November 2007
TABLE OF CONTENTS
1
INTRODUCTION ............................................................................................................2
1.1
2
PURPOSE/CONTENTS ........................................................................................................ 2
REMEDIAL ACTION ALTERNATIVES ..............................................................4
2.1
SUMMARY OPINION ......................................................................................................... 4
2.2
REMEDIAL ACTION ALTERNATIVES IDENTIFICATION – SOIL ........................................... 5
2.2.1. Initial Screening for Soil ............................................................................................ 5
2.3
REMEDIAL ACTION ALTERNATIVES IDENTIFICATION – GROUNDWATER.......................... 7
2.3.1. Initial Screening for Groundwater............................................................................. 7
2.4
REMEDIAL ACTION EVALUATION .................................................................................. 10
2.4.1 Soil ............................................................................................................................ 10
2.4.2 Groundwater ............................................................................................................. 11
2.5
REMEDIAL ACTIONS EFFECTIVENESS ............................................................................. 12
2.6
REMEDIAL ACTIONS LONG/SHORT-TERM RELIABILITY ................................................. 13
2.7
REMEDIAL ACTIONS DIFFICULTY OF IMPLEMENTATION ................................................ 13
2.8
REMEDIAL ACTIONS COST COMPARISON ....................................................................... 13
2.9
REMEDIAL ACTIONS TECHNOLOGICAL FEASIBILITY ...................................................... 13
3
REMEDIAL ACTION SELECTION......................................................................14
4
PHASE III SUMMARY AND FINDINGS ............................................................14
5
COMPLETION STATEMENT AND LSP OPINION ......................................14
FIGURES
Figure 1
Figure 2
Figure 3
USGS Locus Map
Site Plan
MAGIS MAP
APPENDICES
Appendix A
Appendix B
Appendix C
Public Involvement Notices
BWSC Form 108 as E-filed
Copy of Letter of Agency
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Phase III MCP Report
181 North Washington Street, Boston, MA
1
AEG Project # 1667, MADEP RTN 3-12127
November 2007
INTRODUCTION
On behalf of Mr. Joseph Ruggiero, Sr., of Barrington, Rhode Island, Alliance Environmental
Group, Inc. (AEG) has completed the following Phase III – Identification, Evaluation, and
Selection of Comprehensive Remedial Action Alternatives (“Phase III”) for a Disposal Site
(hereinafter referred to as “Site”) assigned Release Tracking Number (RTN) 3-12127 by the
Massachusetts Department of Environmental Protection (MADEP). A United States Geological
Survey (USGS) Map showing the location of the Site is presented as Figure 1. In addition, a
plan depicting general Site conditions and locations of sampling points is attached as Figure 2.
Finally, a Massachusetts Geographical Information System (MAGIS) Map has been attached as
Figure 3.
1.1
Purpose/Contents
The primary purpose of this section of the report is to present the evaluation and selection of
remedial alternatives to achieve a Temporary or Permanent Solution at the Site. In accordance
with 310 CMR 40.0861, the results of the Phase III evaluation shall be documented in a
Remedial Action Plan (RAP). The RAP shall support the selection of a remedial action
alternative(s) by providing information of sufficient detail on the process of development and
evaluation of the recommended alternative(s).
As required by 310 CMR 40.0861(2) of the MCP for when a detailed evaluation is not required,
this RAP contains:
1) A description of all remedial action alternatives initially identified and the results of the
initial screening;
2) Justification for the selected alternatives;
3) The results of the evaluation of the feasibility of whether the implementation of a
Permanent solution is feasible;
4) A discussion of how the alternatives are likely to achieve a level of No Significant Risk;
5) An evaluation of the feasibility of reducing the levels of contaminants to levels that
achieve or approach background; and
6) A schedule for the implementation of Phase IV activities pursuant to 310 CMR 40.0870.
A detailed evaluation of alternatives is not provided, since, as discussed in Sections 2.2.1 and
2.3.1, the initial screenings identified alternatives that we believe meet the criteria provided in
310 CMR 40.0857(2).
The following sections present the results of the Phase III study.
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Phase III MCP Report
181 North Washington Street, Boston, MA
AEG Project # 1667, MADEP RTN 3-12127
November 2007
As required by 40.0863, AEG has notified the Chief Municipal Officer and Board of Health for
the City of Boston, MA. Copies of the notices have been provided in Appendix A.
The person responsible for this Phase III is:
Mr. Joseph Ruggiero, Sr.
One Nayatt Point Court
Barrington, RI 02806
401-245-3835
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Phase III MCP Report
181 North Washington Street, Boston, MA
AEG Project # 1667, MADEP RTN 3-12127
November 2007
2
REMEDIAL ACTION ALTERNATIVES
2.1
Summary Opinion
The results of a Method 2 Risk Assessment as summarized in the Revised Phase II Comprehensive Site Assessment (“Revised Phase II Report”), completed by AEG and dated
October 2007, demonstrate that a condition of Significant Risk exists for soil on the Site. As
such, a Phase III evaluation is presented below for soils. Based upon an evaluation of the
location and cost of remediating the residual soil contamination through removal and disposal, or
solidification/stabilization, which are the only feasible alternatives identified for remediation of
the lead in soil on the Site, and the likelihood that residual pockets of elevated levels of organic
contaminants of concern will remain in Site soils into the future if either of the two selected
alternatives for organic contaminants is implemented, it is considered not feasible to restore soils
at the Site to background. As such, and because the selected alternative for groundwater,
chemical oxidation, will also attenuate the levels or organics in Site soils, and because it has been
demonstrated that both lead and organics in groundwater are no longer at levels that present a
Significant Risk, pavement of the Site and implementation of an Activity and Use Limitation
(AUL) will ensure a condition of No Significant Risk is maintained for Site soils.
Concentrations of target contaminants in groundwater at the Site have been shown to be reduced
sufficiently following injection of sodium persulfate into the subsurface on August 8, 2007, as
part of the Immediate Response Action (IRA) being conducted at the Site. Based upon analytical
data from two monitoring events (9-28-07 and 11-14-07), and the results of a Method 2 Risk
Assessment, it has been demonstrated that the reduced concentrations of contaminants of
concern, if sustained, will pose No Significant Risk. Future monitoring and gauging will be
conducted to ensure that the reduced concentration of contaminants of concern is stable and a
Condition of No Significant Risk has been achieved. Pursuant to MADEP guidelines, two future
gauging/sampling/analytical events, one in February 2008 and one in May 2008, will be
conducted to document ground water conditions in relation to seasonal changes, and to ensure
that “rebound” of contaminants following the sodium persulfate injection does not occur. It is
anticipated, that this additional ground water monitoring will demonstrate that a permanent
solution to groundwater contamination has been achieved, and it will be appropriate to file a
Response Action Outcome Statement (RAO) for the entire Site.
As required under a MADEP Administrative Consent Order with Penalty (ACOP-NE-063A019), dated July 28, 2006, Section III (8)(B), AEG has prepared this Phase III study to meet
the administrative requirements therein. This Phase III evaluation is also intended to comply with
the requirements of 310 CMR 40.0850 et seq., which outlines the purpose and scope of a Phase III
report under the MCP; 310 CMR 40.0000.
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Phase III MCP Report
181 North Washington Street, Boston, MA
2.2
AEG Project # 1667, MADEP RTN 3-12127
November 2007
Remedial Action Alternatives Identification – Soil
The identification and evaluation of remedial action alternatives presented below includes an
initial screening of remedial action alternatives. Screening was limited to two alternatives for
each of the two classes of contaminants (organics and lead).
2.2.1. Initial Screening for Soil
This initial screening is intended to identify remedial action alternatives which are reasonably
likely to be “feasible,” based on the oil and hazardous materials present (C5-C8 aliphatics, C9-C10
aromatics, and xylenes, which together constitute organic contaminants; and the sole inorganic
contaminant of concern, lead), media contaminated and Site characteristics. An alternative is
considered reasonably likely to be feasible, for the purpose of an initial screening if, as stated in
310 CMR 40.0856:
a) The technologies to be employed by the alternative are reasonably likely to
achieve a Permanent Solution; and
b) Individuals with the expertise needed to effectively implement available solutions
would be available, regardless of arrangements for securing their services.
The following sections evaluate the remedial action alternatives that could be employed at the
Site meeting the criteria described above, and describes the selection method that was used to
choose the recommended alternative in compliance with 310 CMR 40.0855 through 40.0859.
A.
Excavation and Removal (organics and lead)
The surest approach to reducing the levels of contaminants in soil to background is to excavate
them and dispose at a permitted facility. In this case, as the majority of the Site’s perimeter
consists of City streets, extensive shoring would be required (along with extensive dewatering) to
access all of the contaminated soils on the Site. Once the contaminated soils have been removed,
refilling of the Site would need to be accomplished with engineered fill, followed by repaving.
As some of the contaminated soils may extend beneath the Site structure, shoring of this building
would likely also be required.
B.
Cement-based Solidification/Stabilization (lead)
Solidification/stabilization (S/S) is a widely used treatment for a broad range of contaminants –
particularly those classified as hazardous in the United States. The treatment involves mixing a
binding reagent into the contaminated substance; in this case soil. This process protects human
health and the environment by immobilizing contaminants within the treated material, preventing
them from migrating in groundwater.
Although the terms solidification and stabilization sound similar, they describe different effects
that the binding reagents create to immobilize hazardous constituents. Solidification describes
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Phase III MCP Report
181 North Washington Street, Boston, MA
AEG Project # 1667, MADEP RTN 3-12127
November 2007
changes in the physical properties of a contaminated substance. The desired changes usually
include an increase in compressive strength, a decrease in permeability, and encapsulation of
hazardous constituents. Stabilization refers to chemical changes of the hazardous constituents
in the treated substance. The desired changes include converting the constituents into a form that
is less soluble, mobile, or toxic.
Commonly used binding reagents include Portland cement, cement kiln dust (CKD), and a
number of proprietary reagents. Portland cement is a generic material principally used in
concrete for construction. This material is also a versatile S/S binding reagent with the ability to
both solidify and stabilize a wide variety of contaminants. Portland cement-based mix designs
have been the most popular S/S treatments and have been applied to a greater variety of
contaminants than any other S/S binding reagent.
Cement is frequently selected for this reagent’s ability to:

Chemically bind free liquids

Reduce the permeability of the waste form

Encapsulate waste particles, surrounding them with an impermeable coating

Chemically fix hazardous constituents by reducing their solubility

Help reduce the toxicity of some contaminants
This is accomplished by bringing about physical changes to the waste form and, often, chemical
changes to the hazardous constituents themselves. Cement-based S/S has been used to treat
either or both inorganic and organic hazardous constituents. Due to the great variation of waste
constituents and media, a mix of reagents should be designed specifically for each waste that is
to be treated. Mix designs often include by-products or additives in addition to Portland cement.
Fly ash is often used to capitalize on the pozzalanic effect of this material when mixed with
hydrating Portland cement. Slag has minor cementitious properties and is sometimes used for
economy. Lime can be used to adjust pH or to drive off water utilizing the high heat of
hydration produced by these S/S binders.
As with removal and disposal, as S/S requires access to all of the soil so that it can be mixed with
the reagent, extensive shoring would be required (along with extensive dewatering) to access all
of the contaminated soils on the Site. Once the contaminated soils have been treated,
recompacting of the Site would need to be accomplished, followed by repaving. As some of the
contaminated soils may extend beneath the Site structure, shoring of this building would likely
also be required.
C.
Chemical Oxidation (organics)
In situ chemical oxidation is based on the delivery of chemical oxidants to contaminated media
in order to destroy the contaminants by converting them to innocuous compounds commonly
found in nature. The oxidants applied in this process are typically hydrogen peroxide (H2O2),
potassium permanganate (KMnO4), sodium persulfate (Na2S2O4), ozone, and, to a lesser extent,
dissolved oxygen (DO). The most common field applications thus far have been based on
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Phase III MCP Report
181 North Washington Street, Boston, MA
AEG Project # 1667, MADEP RTN 3-12127
November 2007
Fenton’s Reagent, whereby hydrogen peroxide is applied with an iron catalyst creating a
hydroxyl free radical. This hydroxyl free radical is capable of oxidizing complex organic
compounds. Residual hydrogen peroxide decomposes into water and oxygen in the subsurface,
and any remaining iron precipitates out. The volume and chemical composition of individual
treatments are based on the contaminant levels and volume, subsurface characteristics, and preapplication laboratory test results. The method for delivery of the chemical may vary. The
oxidant can be injected through a well or injector head directly into the subsurface, mixed with a
catalyst and injected, or combined with groundwater extracted from a site, and then injected and
circulated. In the case of hydrogen peroxide, stabilizers may be needed because of the
compound’s volatility. In situ chemical oxidation has been applied for the treatment of ground
water, sediment, and soil. It can be applied to a variety of soil types and sizes (silt and clay). It
is used to treat VOCs including DCE, TCE, PCE, benzene, toluene, ethylbenzene and xylene (or
together, BTEX, which are the main constituents of gasoline, the main target contaminants at the
Site), as well as semi-volatile organic chemicals (SVOCs), including pesticides, polycyclic
aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). The other oxidizers
mentioned above will achieve the same results, the decomposition of contaminants. However,
depending on a specific site’s conditions, e.g. soil composition, one oxidizer might be a better
choice than another.
2.3
Remedial Action Alternatives Identification – Groundwater
The identification and evaluation of remedial action alternatives presented below includes an
initial screening of remedial action alternatives. Screening was limited to three alternatives for
the organic contaminants in groundwater. Using low-flow protocols and field filtering (which
was deemed necessary as, in spite of high care in extracting samples from the wells, the samples
remained cloudy with particulates), lead has not shown up in groundwater analyzed from the last
two sampling rounds at levels of concern.
2.3.1. Initial Screening for Groundwater
This initial screening is intended to identify remedial action alternatives which are reasonably
likely to be “feasible”, based on the oil and hazardous materials present, media contaminated and
Site characteristics. An alternative is considered reasonably likely to be feasible, for the purpose
of an initial screening if, as stated in 310 CMR 40.0856:
a) The technologies to be employed by the alternative are reasonably likely to
achieve a Permanent Solution; and
b) Individuals with the expertise needed to effectively implement available solutions
would be available, regardless of arrangements for securing their services.
The following sections evaluate three remedial action alternatives that could be employed at the
Site that were identified as meeting the criteria described above and describes the selection
method that was used to choose the recommended alternative in compliance with 310 CMR
40.0855 through 40.0859.
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Phase III MCP Report
181 North Washington Street, Boston, MA
A.
AEG Project # 1667, MADEP RTN 3-12127
November 2007
Chemical Oxidation
In situ chemical oxidation is based on the delivery of chemical oxidants to contaminated media
in order to destroy the contaminants by converting them to innocuous compounds commonly
found in nature. The oxidants applied in this process are typically hydrogen peroxide (H2O2),
potassium permanganate (KMnO4), sodium persulfate (Na2S2O4), ozone, and, to a lesser extent,
dissolved oxygen (DO). The most common field applications thus far have been based on
Fenton’s Reagent, whereby hydrogen peroxide is applied with an iron catalyst creating a
hydroxyl free radical. This hydroxyl free radical is capable of oxidizing complex organic
compounds. Residual hydrogen peroxide decomposes into water and oxygen in the subsurface,
and any remaining iron precipitates out. The volume and chemical composition of individual
treatments are based on the contaminant levels and volume, subsurface characteristics, and preapplication laboratory test results. The method for delivery of the chemical may vary. The
oxidant can be injected through a well or injector head directly into the subsurface, mixed with a
catalyst and injected, or combined with groundwater extracted from a site, and then injected and
circulated. In the case of hydrogen peroxide, stabilizers may be needed because of the
compound’s volatility. In situ chemical oxidation has been applied for the treatment of ground
water, sediment, and soil. It can be applied to a variety of soil types and sizes (silt and clay). It
is used to treat VOCs including DCE, TCE, PCE, benzene, toluene, ethylbenzene and xylene (or
together, BTEX, which are the main constituents of gasoline, the main target contaminants at the
Site), as well as semi-volatile organic chemicals (SVOCs) including pesticides, polycyclic
aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). The other oxidizers
mentioned above will achieve the same results, the decomposition of contaminants. However,
depending on a specific site’s conditions, e.g. soil composition, one oxidizer might be a better
choice than another.
B.
In-Well Air Sparge System
The in-well air sparge system is designed to volatilize VOCs within groundwater and collect
generated vapors using a vacuum extraction system. The construction of remediation wells is
comprised of hydraulically separated upper and lower screened sections of a well within a
continuous aquifer. The lower well screen is ideally placed at or near the bottom of the
contaminated aquifer. The upper well screen, where groundwater is eventually discharged, is
installed immediately above the normal water table elevation.
The in-well sparge system supplies air to the bottom of the contaminated aquifer through the
well. The injected air results in a decrease in groundwater density that causes groundwater to
rise in the well. Contaminated groundwater that rises is discharged above the groundwater level
through the top screen, which allows treated groundwater to re-enter into the vadose zone where
it will cycle back to the contaminated portion of the aquifer. The air injected into the well also
allows contaminants to move from a dissolved phase to an air phase based upon Henry’s Law.
The air-phased solvents rise in bubbles and are released into the well to be captured by the
vacuum system. Air supply and vacuum extraction are connected to the wells through main lines
placed below grade. This treatment alternative draws contaminated groundwater in through the
lower screened interval.
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Phase III MCP Report
181 North Washington Street, Boston, MA
C.
AEG Project # 1667, MADEP RTN 3-12127
November 2007
Monitored Natural Attenuation (MNA)
When concentrations of contaminants are shown to decrease over time, and if initially
determined concentrations are within a magnitude or two of the appropriate risk based standard,
then it might be reasonable to do nothing other than monitor the situation over time. A
reasonable sampling/analysis frequency is typically twice a year at all affected groundwater
wells. Natural attenuation is the sum of natural processes that leads to the lessening of
contaminant concentrations in groundwater over time. The primary objective of MNA is to
demonstrate that natural processes will reduce contaminant concentrations in groundwater to
levels below regulatory standards before a point of compliance is reached. The point of
compliance can be a property boundary, a well, a stream, or some other potential receptor. MNA
as a remedial alternative is highly dependent on a good understanding of localized hydrogeologic
conditions and may require considerable information and monitoring over an extended period of
time. MNA is not an approach that will lead to rapid closure of a site.
MNA is seldom selected as a sole remedy. The MADEP expects source identification and
removal. This includes free product removal. Full delineation of the contaminant plume
including sentinel wells below regulatory levels is needed. It must be demonstrated that natural
attenuation is occurring before MNA can be considered as a portion of the remedy at a site. A
steady or decreasing plume front must be established. Institutional controls established and
maintained by the responsible party will be required with any MNA remedy including, but not
limited to, notices to property deeds, until attenuation to appropriate levels has been confirmed.
Uncertainty associated with estimated rates of attenuation over protracted periods of time is a
major consideration with MNA. Hydrologic and geochemical conditions amenable to natural
attenuation can change due to natural or anthropogenic causes and the mobility of a plume can
change over time. Natural attenuation of contaminants in groundwater must be monitored over
significant periods of time to evaluate the continued performance of natural attenuation. MNA
should not be considered a presumptive remedy, but should be evaluated along with active
remediation options to restore groundwater to its desired quality considering cost, technical
practicability, meeting remedial objectives, and protection of human health and the environment.
There are numerous types of natural attenuation, including biological and physical forms.
Certain types of biological degradation require aerobic conditions and others require anaerobic
conditions. Determining the type of natural attenuation or the lack of it is very important at a
site. It is important to know what specific mechanism is responsible for the reduction of
mobility, toxicity, or bioavailability of contaminants so the long-term effectiveness of the
mechanism can be evaluated. Parameters evaluated to determine natural attenuation would
necessarily be site-specific, but common indicator parameters include the presence or absence of
degradation daughter products, pH, Oxidation Reduction Potential (ORP), evaluation of local
concentrations of iron, oxygen, sulfate and nitrates in groundwater, etc.
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Phase III MCP Report
181 North Washington Street, Boston, MA
2.4
AEG Project # 1667, MADEP RTN 3-12127
November 2007
Remedial Action Evaluation
2.4.1 Soil
The MCP (specifically 310 CMR 40.0857(2)) provides that a detailed evaluation of the above
alternatives is not required in those cases where the selected alternative meets the following
criteria:
a) Is proven to be effective in remediating the types of oil and hazardous materials present
at the disposal site, based upon experience gained at other disposal sites with similar site
and contaminant conditions;
b) Results in the reuse, recycling, destruction, detoxification, treatment or any combination
thereof of the oil and hazardous material present at the disposal site;
c) Can be implemented in a manner that will not pose a significant risk of harm to heath,
safety, public welfare or the environment, as described in 310 CMR 40.0900; and
d) Is likely to result in the reduction and/or control of oil and/or hazardous material at the
disposal site to a degree and in a manner such that the requirements of a Class A
Response Action Outcome as set forth in 310 CMR 40.1000 will be met.
We believe that either Alternative A or B, removal and disposal, or solidification/stabilization
(S/S) meet the four criteria for the lead contamination, as follows:
1) Proven Effective: Removal and disposal would, on the face of it, restore the Site to
background for lead in soil, as long as replacement soil was “clean.” S/S has been
employed at many sites and will, if conducted per manufacturer’s recommendations,
reduce the mobility potential of the lead.
2) Reuse, Recycling, Destruction of the Contaminants: The lead present in soil after S/S
would not be as mobile as it is now, which is now, apparently, not significant. Any soil
removed and disposed from the Site would be done so pursuant to applicable regulations.
3) Implement in a Manner that Poses No Significant Risk: Removal and disposal and/or S/S
would be conducted using dewatering technology so that any contaminants mobilized
during remediation would be captured before migrating off-Site.
4) Reduce and/or Control Contaminants to Meet Class A-3 RAO: As discussed above,
while technically feasible, the location and cost of removing residual soils and/or
conducting S/S make these alternatives economically infeasible. Ongoing testing has
confirmed that the residual soil contamination is not an ongoing source of ground water
contamination. Further monitoring will confirm this.
We believe that Alternative C, chemical oxidation meets the four criteria for the organics
contamination, as follows:
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Phase III MCP Report
181 North Washington Street, Boston, MA
AEG Project # 1667, MADEP RTN 3-12127
November 2007
1) Proven Effective: Chemical oxidation has proven highly successful in lowering the
levels of organic contamination. The only requirement is that the injected chemicals
come into contact with the residual contaminants.
2) Reuse, Recycling, Destruction of the Contaminants: To the extent that the chemicals can
be injected so as to maximize contact with the contaminants, the organics will be mostly
destroyed.
3) Implement in a Manner that Poses No Significant Risk: Injection of the chemicals, if
conducted pursuant to 310 CMR 40.0046 and recognized hazmat health and safety
protocols, will pose No Significant Risk.
4) Reduce and/or Control Contaminants to Meet Class A-3 RAO: As discussed above, if
the chemicals come into direct contact with the contaminants, this methodology will
successfully lower the levels of organics contamination below present levels, which
presently are where an A-3 RAO can be filed for the Site. As the soil on the Site varies
from a clean gravel in the areas where USTs once resided, to a low permeability silt near
the northerly perimeter of the Site, an extensive set of new injection points would be
needed to reduce the levels of organics in soil to at or approaching background. The cost
of such a program is economically infeasible. Ongoing testing has confirmed that the
residual soil contamination is not an ongoing source of ground water contamination.
Further monitoring has and will confirm this.
Overall, while technically feasible, Alternative A, B and C are all economically infeasible in
accordance with the evaluation required by the MCP 40.0860. The most economically feasible
solution that meets the benefit-cost analysis required by 40.0860(7) is to maintain the barrier to
direct contact with contaminated soils, which exist below 4 feet from surface grade, with
implementation of an Activity and Use Limitation.
2.4.2 Groundwater
The MCP (specifically 310 CMR 40.0857(2)) provides that a detailed evaluation of the above
alternatives is not required in those cases where the selected alternative meets the following
criteria:
a) Is proven to be effective in remediating the types of oil and hazardous material present at
the disposal site, based upon experience gained at other disposal sites with similar site
and contaminant conditions;
b) Results in the reuse, recycling, destruction, detoxification, treatment or any combination
thereof of the oil and hazardous material present at the disposal site;
c) Can be implemented in a manner that will not pose a significant risk of harm to heath,
safety, public welfare or the environment, as described in 310 CMR 40.0900; and
d) Is likely to result in the reduction and/or control of oil and/or hazardous material at the
disposal site to a degree and in a manner such that the requirements of a Class A
Response Action Outcome as set forth in 310 CMR 40.1000 will be met.
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Phase III MCP Report
181 North Washington Street, Boston, MA
AEG Project # 1667, MADEP RTN 3-12127
November 2007
We believe that Alternatives A, B, and C meet the four criteria for the organics contamination, as
follows:
1) Proven Effective: All of the Alternatives are proven and often-used remedies. Chemical
oxidation (Alternative A) is the most rapid of the three options (and would markedly
accelerate the current natural breakdown of the contaminants in the soil and
groundwater); followed by an in-well sparge system; and then MNA.
2) Reuse, Recycling, Destruction of the Contaminants: The organics in the groundwater
would be destroyed through chemical oxidation; and removed through in-well air
sparging or MNA. Sodium persulfate was injected into the subsurface of the Site as part
of an IRA. The organic contaminants present in ground water after application of the
sodium persulfate have reduced significantly and will continue to be degraded through
oxidation and natural in-situ processes;
3) Implement in a Manner that Poses No Significant Risk: MNA would pose No Significant
Risk. In-well air sparging, if conducted pursuant to applicable protocols, including air
quality regulations, would pose No Significant Risk. Chemical oxidation, was conducted
pursuant to 310 CMR 40.0046 and recognized hazmat health and safety protocols, and
posed No Significant Risk. Groundwater monitoring has been and will continue to be
implemented in a manner that ensures Site conditions pose No Significant Risk;
4) Reduce and/or Control Contaminants to Meet Class A-3 RAO: As discussed above,
while technically feasible, the location and cost of removing residual soils and/or
conducting S/S make these alternatives economically infeasible. Ongoing testing has
confirmed that the residual soil contamination is not an ongoing source of ground water
contamination. Further monitoring will confirm this.
2.5
Remedial Actions Effectiveness
All of the identified remedial actions would have likely achieved a permanent solution and
provide a level of No Significant Risk over time. However, chemical oxidation (sodium
persulfate) was injected into the subsurface of the Site in August of 2007 as part of an IRA. The
sodium persulfate has been shown to have effectively reduced concentrations of organic
contaminants in ground water, therefore, completion of the chemical oxidation remedy is the
remedy selected here. It has been shown through two analytical rounds on groundwater taken
from monitoring wells at the Site that the injection of sodium persulfate has reduced
concentrations of contaminants in groundwater to concentrations that pose No Significant Risk.
Lead in groundwater was sampled in the latest two rounds using low-flow technology and field
filtering (as samples continued to be cloudy in spite of careful removal from the well), and found
to be below a level of Significant Risk through a Method 2 Risk Assessment.
It has been demonstrated, as reported in the Revised Phase II Report, that the injection of sodium
persulfate has reduced groundwater contamination to the point where a Method 2 Risk
Assessment shows a condition of No Significant Risk. Restoration to background of the non-
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181 North Washington Street, Boston, MA
AEG Project # 1667, MADEP RTN 3-12127
November 2007
persistent contaminants of concern will occur through continued natural biological processes and
oxidation of the contaminants from residual sodium persulfate. It will also reduce the soil
concentrations in areas where sodium persulfate contacts contaminated soil.
2.6
Remedial Actions Long/Short-Term Reliability
It is the opinion of AEG that any one of the remedial alternatives above for the Site would have
long-term reliability relative to remediation of the groundwater and soil at the Site.
2.7
Remedial Actions Difficulty of Implementation
The implementation of the selected alternative did not disrupt activities at the Site for more than
one day. Otherwise, the injection process was not difficult and did not present any long-term
deleterious effects at the Site.
2.8
Remedial Actions Cost Comparison
As the selected remedial technology was implemented during the IRA process, costs were not
considered in this Phase III assessment. However, as discussed above, aside from MNA and
implementing an AUL at the Site, the other alternatives considered for remediation of the soil
and groundwater at the Site we not economically feasible. Cost was one of the factors
considered in the selection of chemical oxidation during the IRA process.
2.9
Remedial Actions Technological Feasibility
All remedial action options that were considered here for the Site are considered technologically
feasible because they all include proven methods that can render a level of No Significant Risk.
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181 North Washington Street, Boston, MA
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AEG Project # 1667, MADEP RTN 3-12127
November 2007
REMEDIAL ACTION SELECTION
Relative to groundwater, as the MADEP has specifically ruled out MNA as an allowable remedy
for the Site, and based upon the facts that chemical oxidation methodology is a proven
technology, was chosen as the preferred response action, was injected into the subsurface of the
Site in August of 2007 as part of the IRA process, and appears to be reducing concentrations of
contaminants in ground water to a condition of No Significant Risk, it is the remedy selected
here to achieve a permanent solution..
Relative to soil, as excavation and removal, and/or stabilization and solidification has been
shown above to be economically infeasible in accordance with 40.0860, implementation of an
integral pavement over the entire Site along with an AUL is the remedy selected here.
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PHASE III SUMMARY AND FINDINGS
AEG has completed this Phase III report in accordance with 40.0850 of the MCP. The Phase III
included identification and evaluation of various response actions that would likely yield a
condition of No Significant Risk at the Site pertaining to contaminated soil and groundwater (the
risk to health has been demonstrated to be at a level of No Significant Risk for indoor air
effects). The MADEP-preferred alternative for groundwater, chemical oxidation, has already
been implemented at the Site as part of an IRA process and currently is being monitored, as
discussed above. The selected remedy for soil, implementation of an Activity and Use
Limitation, will be implemented prior to filing of the Response Action for the Site. In the
meantime, the entire Site has recently been paved. As such, the barrier to direct contact that will
be maintained through the AUL is already in place.
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COMPLETION STATEMENT AND LSP OPINION
This Phase III Report has been completed in accordance with 310 CMR 40.0000 of the MCP. At
this time, a remedial action toward rendering a level of No Significant Risk has already been
implemented through the IRA process.
AEG’s office is located at 124 Mt. Auburn Street, Suite 200N, Cambridge, Massachusetts 02138.
AEG can be contacted at (617) 492-6500.
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