COMMONWEALTH OF MASSACHUSETTS EXECUTIVE OFFICE OF ENERGY & ENVIRONMENTAL AFFAIRS DEPARTMENT OF ENVIRONMENTAL PROTECTION ONE WINTER STREET, BOSTON, MA 02108 617-292-5500

DEVAL L. PATRICK Governor TIMOTHY P. MURRAY Lieutenant Governor

IAN A. BOWLES

Secretary

LAURIE BURT Commissioner

This information is available in alternate format. Call Donald M. Gomes, ADA Coordinator at 617-556-1057. TDD# 1-866-539-7622 or 1-617-574-6868.

MassDEP on the World Wide Web: http://www.mass.gov/dep

Printed on Recycled Paper

MEMORANDUM To: Kyle MacAfee, Project Manager, BWSC/NERO Through: Carol Rowan West, Director, ORS From: Nancy Bettinger, ORS Date: January 14, 2009 Subject: Draft Supplemental Phase II/III and Revised Phase IV Remedy Implementation Plan (RIP) MBTA Readville 5-Yard Facility RTN 3-2856 1.0 Introduction As requested, ORS has reviewed the November 5, 2008 Draft Supplemental Phase II/III report (referred to in this memorandum as the Supplemental Report). The Supplemental Report was prepared by Earth Tech AECOM and submitted to MassDEP on behalf of Massachusetts Bay Transportation Authority (MBTA). ORS has also reviewed selected portions of previous reports, including: • Phase IV Remedy Implementation Plan Amendment dated July 18, 2006, prepared by LFR • Final Phase II Comprehensive Site Assessment dated January 2003, prepared by Weston & Sampson Engineers,

Inc. • Final Phase III Identification, Evaluation and Selection of Remedial Alternatives dated April 2003, prepared by

Weston & Sampson Engineers, Inc. 2.0 Site Description and History The Readville Train Yard Site is a 42-acre parcel on the boundary between Boston and Dedham. It is owned by MBTA and operated by Amtrak. Materials used for railroad maintenance are currently stored within the 5-acre “Staging Area” in the south central area of the site. Such materials were historically stored throughout the site. During the 1800s the Readville Shop operations included repair and maintenance of locomotives and rail cars. The “Exclusion Zone” on the western end of the site was fenced in 2001 to limit access to the stockpiles containing soil and debris located in that area. A historical burn pit is also located in the Exclusion Zone. Historical data indicates the site has been impacted by lead, arsenic and petroleum hydrocarbons. The train yard property is bounded by residential neighborhoods to the north, east and west and by industrial facilities to the south. An 8 foot-tall fence surrounds the site, but it is not guarded, and so it is possible for nearby residents to enter the site.

2

3.0 Conclusions and Recommendations The final risk calculations were done using MassDEP’s Risk Assessment Shortforms and are documented in Appendix D of the Supplemental Report. The toxicity values and exposure factors employed in the Shortforms are consistent with the Massachusetts Contingency Plan (MCP) and with current MassDEP risk assessment guidance and practice. ORS’s main concerns center on the following components of the site assessment: • Connections between the site assessment and the risk assessment, including:

o Comparison of site concentrations with background levels o Delineation of exposure points (areas) o Determination of exposure point concentrations

• Links between the risk assessment and the remediation plans, including: o Determination of the relationship between foreseeable uses and exposure points o Calculation of risk-based remedial goals

ORS recommends requiring a revision of the Supplemental Report that includes the following risk assessment components: • Re-evaluation of background conditions and identification of COCs using a methodology consistent with MassDEP

guidance for background evaluations; • A clearer distinction between (a) foreseeable use(s), for which site conditions must pose “no significant risk” and (b)

uses that are not foreseeable, for which site conditions may pose a risk and an AUL will be necessary; • Identification of exposure points (exposure areas) that correspond with the foreseeable use(s) and represent areas

throughout which a receptor is equally likely to be exposed over time; • Calculation of exposure point concentrations that represent conservative estimates of average concentrations within

each exposure points; • Clearer documentation of risks associated with anticipated post-remedial site conditions; and • Calculation of risk-based remedial goals consistent with the risk assessment for the foreseeable site use(s).

A more detailed discussion of concerns and questions identified by ORS is offered in the following section. 4.0 Discussion 4.1 Identification of Contaminants of Concern – Comparison of Site Concentrations to Background Levels • Section 2.10 of the Supplemental Report states that in 2002 Weston & Sampson collected eight surface samples

from eight baseline perimeter locations (BC/SS and BL/SS) and analyzed them for EPH with target analytes and 13 metals. The sample locations with prefixes BC/SS and BL/SS shown on Figure 2, however, appear to lie within the area likely to have been affected by historical operations. These are not background locations.

Site-specific background concentrations should be based on samples from locations well outside of the area impacted by rail yard operations. Although the suitability of the selected background locations could potentially be a major issue, it is unclear whether this site-specific background comparison is actually being incorporated into site management decisions. Comparisons of site concentrations to published background values are also presented in the reports, and those comparisons appear to be given more weight. Comparisons to published background values are discussed in the bullet point that follows.

• Section 2.10 of the Supplemental Report states that for all PAHs and metals, the Phase II Risk Characterization compared the 95th percentile concentrations to the corresponding 95th percentile Central Artery/Third Harbor

3

Tunnel urban background concentrations published by CDM. The comparisons are provided in Appendix A of the Phase II Risk Characterization (Appendix J) of the January 2003 Weston & Sampson Final Phase II Comprehensive Site Assessment Report. The method used to compare site concentrations to background levels for this site is inconsistent with the methodology recommended in Mass DEP’s 2002 Technical Update titled Background Levels of Polycyclic Aromatic Hydrocarbons and Metals in Soil. The Technical Update states that maximum site concentrations should be compared to DEP-published background concentrations. The methodology employed by Weston and Sampson is a less conservative (i.e., less protective) method for two reasons:

o The 95th percentile CDM urban background values presented in the table are generally higher than the DEP published concentrations. Using the CDM values entails a higher risk of incorrectly attributing elevated site concentrations to background conditions.

o The 95th percentile site concentrations are of course lower than the maximum site concentrations. Using

the 95th percentile rather than the maximum entails a higher risk of incorrectly attributing elevated site concentrations to background conditions.

4.2 Exposure Points • The risk assessment evaluates each of these “risk areas” as exposure points:

o Area 1 (Orphan Line): 0 – 0.5 ft and 0.5 – 3 ft depths o Area 2 (Ashcroft Street): 0 – 0.5 ft depth o Area 3 (Main Rail Yard): 0 – 0.5 ft; 0.5 – 3 ft; and > 3 ft depths. o Area 4 (Exclusion Zone): 0-0.5 ft; 0.5 – 3 ft; and > 3 ft depths.

These areas have been delineated based on historical site use, contaminant levels and soil management considerations. They are not based on current and foreseeable site uses and activities, so they should not necessarily be assumed to represent exposure points. Exposure points are areas over which a person or group of people would be equally likely to be exposed to all locations over time for specific activities and uses. Exposure points are not likely to be the same for all uses. Identification of exposure points is a key component of the risk assessment for both current and foreseeable exposures. To demonstrate a condition of “no significant risk” for foreseeable use, estimates of average contaminant concentrations within each exposure point should be compared to remedial goals associated with foreseeable uses. For example, if development of smaller parcels for commercial enterprises is a foreseeable use of the exclusion zone, exposure points within the exclusion zone should be approximately the size of lots typical for small commercial properties, and the quantitative risk calculations should focus on the most contaminated areas that are consistent in size with small commercial parcels of land. Similarly, if repeated trespassing is likely to occur in limited areas of the site with relatively high contaminant levels, exposure point concentrations for that scenario should be based on average concentrations in those smaller areas. If exposure point concentrations are averaged over areas that are too large, risks for specific uses and activities in portions of the site with relatively high concentrations will be underestimated. ORS is also concerned about the vertical dimension of exposure points in this risk assessment. The MCP requires consideration of surface soil exposures within in the top three feet of soil at a minimum. For Area 2, therefore, the 0.5 – 3 ft depth interval should be included in the assessment of surface soil exposures. 4.3 Exposure Point Concentrations

• From the poor correlation of XRF results with laboratory results, the level of certainty associated with each result

appears to be high. This uncertainty should be taken into account in any site management decisions based in whole or in part on the XRF data. Specific concerns about the accuracy of the data follow:

4

o On page 2, the Supplemental Report states: “Up to 30 samples per 500 cubic yards of soil were collected

by Earth Tech for x-ray fluorescence (XRF) screening in the field for lead and arsenic. Of these, one composite sample per 250 cubic yards (88 samples) was submitted for confirmatory laboratory analysis of total lead, TCLP lead, total arsenic, and EPH with target analytes.” The statement that a composite sample was submitted for confirmatory analysis begs the question of whether the XRF samples (a) were also composites, and so were comparable to the confirmatory lab samples, but not representative of the full range of concentrations present, or (b) were not composites, and so were not comparable to the confirmatory lab samples.

o From Figure 5, it appears that the error in predicting the laboratory analytical result for lead from XRF

analysis is frequently large. Further, for lead, XRF results appear to underestimate laboratory results fairly frequently. At a minimum, these errors and their implications for the risk assessment should be discussed in the uncertainty section, and taken into account in risk management decisions.

o Section 2.3.1.2 of the Supplemental Report notes that poor correlation was observed between Earth

Tech’s XRF arsenic reading and the arsenic soil concentrations by laboratory analysis. Based on this finding and on information from the manufacturer, the arsenic XRF data are not considered to be reliable.

In contrast to the lead XRF data, the arsenic XRF data appears to over-estimate laboratory-reported concentrations. In ORS’s view, this makes the XRF arsenic data more reliable than the XRF lead data for screening purposes, because the arsenic XRF data is less likely to under-estimate concentrations and exposures.

o The Supplemental Report states that a comparison of the lead XRF detections to the corresponding

laboratory results indicates that, in general, the XRF readings were slightly higher than the laboratory results. Figure 5, however, indicates the opposite is true.

o Earth Tech noted that the XRF and laboratory results for lead were in good agreement, with the exception

of the highest concentrations detected by the two methods. Therefore, Earth Tech performed a “Discordance Test” to determine whether this XRF reading was a statistical outlier and did not “fit” the distribution of the remainder of the data. Based on the results, it was considered appropriate to exclude this data point from the data set. With the exclusion of this outlier, good correlation was observed.

ORS believes that excluding this point may have resulted in a misleading conclusion about the correlation between XRF and lab data. There appear to be only two other points in the whole data set with XRF and laboratory results greater than 10,000 mg/kg. Those two remaining high points are bound to have an inordinate impact on the slope of the line as well as the R2 value.

o Considering the uncertainty associated with XRF analytical results and the low cost of laboratory metals analysis, the advantages of using this procedure so extensively at this site are not clear. The advantage of XRF is its real-time analysis capability, but at this site that does not appear to have been necessary to have real-time data for soil removal and management purposes.

• For each risk area, exposure point concentrations were evaluated over one or more of three depth intervals: 0 –

0.5 ft; 0.5 ft - 3 ft; and greater than 3 ft. In several places, the report refers to the 0 – 0.5 ft depth as surface soil and the 0.5 - 3 ft depth as shallow sub-surface soil. For the purpose of risk assessment, the MCP requires that surface soil exposures associated with current and foreseeable uses be evaluated for contamination to 3 feet below ground surface. Therefore, the final site management decisions about remediation and application of AULs must ensure that contaminant concentrations in the top three feet pose a condition of no significant risk for the relevant site activities and uses.

5

• In Section 2.13 the Supplemental Report states that acceptable use of the site can be achieved under all receptor

scenarios with hot spot removal, implementation of engineering controls and an AUL. It is unclear from the report how likely it is that removal of identified hotspots will truly reduce average concentrations. More specifically, it is unclear whether (a) the extent of each identified hotspot has been fully delineated prior to hotspot removal; and (b) post-removal confirmatory sampling has been or will be done in the vicinity of any and all soil removal locations.

Section 2.13.2.3 describes individual soil samples as hot spots. MassDEP generally views a high concentration detected in single sample as an indication that a hot spot may be present, and that further sampling is needed to determine whether an area with elevated concentrations (hot spot) is actually present. The report suggests that the concentration detected in a sample considered representative of a cell has been interpreted as representative of the levels throughout the cell. This suggestion is re-enforced by Figure 19, which shows hotspots as clusters of square cells. It is important to recognize, however, that a high concentration detected in a sample does not necessarily mean that high concentrations will be found throughout the cell. Similarly a low concentration does not necessarily mean that the soil throughout the cell has low levels. Post-removal sampling to demonstrate that overall levels are in fact lower after removal than before may be necessary.

• Section 2.13 of the Supplemental Report states that based on the types and concentrations of contaminants

detected, the Phase II Risk Characterization concluded that the soil from the stockpiles may be suitable for reuse in the Exclusion Zone. If the decision is made to grade stockpile soil to level ground in the exclusion zone, or if that has already been done, ORS would recommend extensive post-leveling sampling to confirm that the concentrations do not pose a significant risk for foreseeable uses.

4.4 Risk Characterization Risk calculations done using MassDEP Shortforms are presented in Appendix C of the Supplemental Report. Exposure point concentrations used in the calculations were the 95% upper confidence limit on the mean concentration for each risk area. For the exposure scenarios that were evaluated, the risk assessment per se is consistent with the requirements of the MCP and with current risk assessment guidance and practice (although smaller exposure points should perhaps have been used, as previously noted). Not all relevant scenarios were evaluated, though. The commercial/industrial exposure scenario was not included in the risk assessment. In our opinion, this decision leaves an important gap in the information needed for risk management decisions at this site. Considering that commercial/industrial exposures are likely to be the most intense exposures under the current site use, ORS believes it is necessary to document definitively that concentrations do not pose a risk for workers at the site. In addition to the “forward” risk estimates that were calculated using the Shortforms and presented in Appendix C, the Phase II assessment also includes calculation of risk-based concentrations (RBCs), which are concentrations associated with “no significant risk of harm to human health” for each chemical. The RBCs were “updated” by Gradient and presented in Appendix F of the July 2006 Phase IV Remedy Implementation Plan Amendment submitted by LFR The Gradient RBCs are presented in Table 1 of Appendix F and Compared with the Weston & Sampson RBCs in Table 2 of Appendix F. RBCs are important in the risk management process because they simplify the assessment of risk associated with each remedial option. Unfortunately, however, the Gradient RBCs do not appear to be consistent with current MassDEP risk assessment guidance and practice as reflected in the MassDEP Shortforms. ORS recommends requiring the inclusion of RBCs that are consistent with the exposure factors and toxicity values in MassDEP Shortforms in the final Supplemental Phase II/III report.

6

4.5 Risk management Section 2.13.2.2 states that an Activity and Use Limitation may be required at sites where the S-1 standards are not met in soil less than 15 feet below the ground surface (emphasis added). Just to be clear, an Activity and Use Limitation is always required if exposure point concentrations would pose a risk for the most sensitive site use (residential). 5.0 Miscellaneous Site Management Considerations ORS would like to offer two additional comments aimed at considering uncertainty about specific exposures and risks when making or approving site management decisions. The two aspects of the assessment that we believe are associated with exceptionally high uncertainty are: (1) potential exposures to airborne particulate matter in residential areas near the site; and (2) the risk management criteria that are currently used in conjunction with the EPA IUBK lead model. Specific concerns and recommendations are detailed in the sections that follow. 5.1 Potential Exposure to Airborne Particulate Matter In light of the possibility that surface soil with high concentrations of arsenic and lead will be left in place untreated, steps should be taken to ensure that nearby residents are not exposed to contaminated airborne particulate matter originating from the site. It is generally assumed that risks from direct contact exposures are higher, and that risk reduction activities aimed at direct contact exposures will limit airborne particulate exposures as well. In this case, however, it appears likely that soil with arsenic and lead concentrations ranging up to very high levels will be left in place, and so there is uncertainty about significance of risks from potential long-term exposure airborne particulate matter originating from the site. As a consequence, ORS recommends minimizing particulate exposures by requiring the owners/operators of this site to take steps to limit emissions by covering highly contaminated areas with clean soil or vegetation, and by employing dust control measures during storage hauling activities. 5.2 Risk Management Criteria Associated with the IEUBK Lead Model The lead IEUBK model developed by EPA to assess children’s risk quantifies exposure by estimating a blood lead level in units of micrograms per deciliter (µg/dl). The model characterizes risk by calculating the proportion of an exposed population whose blood lead level is expected to exceed the target (acceptable) concentration of 10 µg/dl. As a matter of practice for MCP risk assessments, lead exposures resulting in exceedances of 10 µg/dl for <5% of the exposed population have been considered to pose “no significant risk of harm” to human health. ORS has two concerns about this practice. First, a blood lead level of 10 is not considered a “no effects” level; adverse effects have been associated with lower concentrations. Second, protecting 95% of the population is not consistent with the margins of safety associated with the assessment and management of risk from exposures to other chemicals. For these reasons, ORS recommends that site managers exercise caution to ensure that actual exposures do not exceed the estimated exposures on which the risk assessment is based. If you have any questions about this memorandum, please feel free to contact Nancy Bettinger at (617)556-1159 or nancy.bettinger@state.ma.us. cc: Maureen Vallatini, OGC/ NERO

COMMONWEALTH OF MASSACHUSETTS EXECUTIVE OFFICE OF ENERGY & ENVIRONMENTAL AFFAIRS DEPARTMENT OF ENVIRONMENTAL PROTECTION NORTHEAST REGIONAL OFFICE 205B Lowell Street, Wilmington, MA 01887 • (978) 694-3200

DEVAL L. PATRICK Governor TIMOTHY P. MURRAY Lieutenant Governor

IAN A. BOWLES

Secretary

LAURIE BURT Commissioner

This information is available in alternate format. Call Donald M. Gomes, ADA Coordinator at 617-556-1057. TDD# 866-539-7622 or 617-574-6868. http://www.mass.gov/dep • Fax (978) 694-3499

Printed on Recycled Paper

March 23, 2008 Massachusetts Bay Transportation Authority 10 Park Plaza, Room 6720 Boston, MA 02116-3900 Attention: Mr. Scott Darling III, Environmental and Land Use Counsel Subject: MassDEP’s comments, Readville 5 Yard Supplemental Phase II Comprehensive Site

Assessment, Phase III Remedial Action Plan and Revised Phase IV Remedy Implementation Plan, MassDEP Release Tracking Numbers 3-2856 and 3-18777

Dear Attorney Darling, On September 11, 2008, the Massachusetts Department of Environmental Protection (MassDEP) received a draft of a Supplemental Phase II Comprehensive Site Assessment (CSA), Phase III Remedial Action Plan (RAP) and revised Phase IV Remedy Implementation Plan (RIP) for the Readville 5 Yard, entitled “Draft Phase IV Remedial Implementation Plan (RIP), Release Tracking Number 3-2856.” This report was prepared by Earth Tech/AECOM (Earth Tech) on behalf of the Massachusetts Bay Transportation Authority (MBTA). Based on preliminary comments provided to the MBTA on October 17, 2008, a revised version of the above-referenced document was received on November 5, 2008. The purpose of this letter is to provide the MBTA with MassDEP’s final comments on the proposed document. As part of the review of the initial and revised documents, MassDEP consulted work previously performed by both Levine Fricke Recon, Inc. (LFR) and Weston & Sampson Engineers, Inc. (W&S) for this site, and enlisted MassDEP’s Office of Research & Standards for additional technical support. The site is a 42-acre former railroad yard that is divided between the city of Boston and town of Dedham. The supplemental CSA and RAP are used to support a RIP that proposes to remediate the parcel to commercial/industrial use standards to achieve a Class A-3 Response Action Outcome, supported by an Activity and Use Limitation to limit future development options to commercial/industrial uses. This proposed cleanup plan is based on work previously submitted by W&S and LFR, as well as additional work performed by Earth Tech.

Readville Phase II/III/IV Comments Page 2

In accordance with the Consent Judgment, Commonwealth of Massachusetts v. Massachusetts Bay Transportation Authority (MBTA), Civil Action #01-04492E, dated February 23, 2004, the MBTA must file a RIP for the site for review and approval by MassDEP.

As with MassDEP’s initial comments of October 17, 2008, the following comments are

grouped by submittal. MassDEP has also reiterated those comments from the previous letter, as appropriate: Phase II CSA

MassDEP noted several concerns with the treatment of data and the assumptions used to characterize risk at the disposal site. The following issues require correction or more thorough documentation in order to demonstrate the site characterization and risk-based cleanup goals have been developed in a conservative manner: 1) The identification of “background” concentrations of metals and Polycyclic Aromatic

Hydrocarbons (PAHs), originally conducted in 2002, was based upon 8 samples collected within the delineated bounds of the disposal site. The MCP defines “background” to include the detection of compounds that are ubiquitous and consistently present and/or associated with wood and coal ash. The assessments conducted to date fail to adequately evaluate the concentrations of metals and PAHs that represent “background” concentrations outside the delineated disposal site. In addition, the report fails to document that the sample results presented are not associated in whole or in part with other rail yard-related activities which led to a release on the site.

2) The report states that the Risk Characterization compared the 95th percentile concentrations

for all detected PAHs and metals to their corresponding 95th percentile Central Artery/Third Harbor Tunnel urban background concentrations published by CDM. These comparisons were provided in the January 2003 Weston & Sampson Final Phase II Comprehensive Site Assessment Report. The method used to compare site concentrations to background levels is inconsistent with the guidance provided in MassDEP’s 2002 Technical Update titled “Background Levels of Polycyclic Aromatic Hydrocarbons and Metals in Soil”. The Technical Update states that maximum site concentrations should be compared to MassDEP-published background concentrations. The methodology employed by Weston and Sampson is a less conservative method for two reasons:

a) The 95th percentile CDM urban background values presented in the table are generally

higher than MassDEP published concentrations. Use of the CDM values in the comparison creates the possibility of incorrectly attributing elevated site concentrations to background conditions, which would not provide a conservative estimate of risk.

b) The 95th percentile site concentrations are lower than the maximum site concentrations.

Using the 95th percentile rather than the maximum increases the risk of incorrectly attributing elevated site concentrations to background conditions.

Readville Phase II/III/IV Comments Page 3

The comparison, as presented, fails to demonstrate that the approach used is at least as conservative as MassDEP guidance.

3) MassDEP is concerned with the delineation of “Hot Spots” as distinct points on the site. The detection of elevated concentrations requires additional sampling to more fully delineate the extent (area & depth) of the “Hot Spot” for proper site characterization. Furthermore, such information is required to properly evaluate remedial options and feasibility under Phase III activities.

4) MassDEP is concerned with the treatment of XRF screening data for the purpose of

evaluating risk at the site. Additional information must be provided to accept the use of XRF data in the calculation of Exposure Point Concentrations (EPCs).

a) The correlation of screening results to laboratory data excluded one high lead result,

based on a statistical test; however the evaluation should have considered whether additional data points with high lead concentrations should also have been excluded. As lower range lead concentrations determined by XRF underestimate lead concentrations as determined by laboratory data, a significant portion of the screening data used may not accurately represent the true EPC for lead on the site. Proper evaluation of the screening data is important in order to derive a conservative EPC for lead, and to accurately describe the uncertainty with the use of screening data. Unless the XRF data can be shown to provide a conservative EPC, additional laboratory data should be generated to calculate the lead EPC.

b) Conversely, the arsenic XRF screening data was discarded for a poor correlation with

laboratory data; however the arsenic concentrations determined by XRF tended to overestimate laboratory arsenic concentrations. Such screening data is deemed conservative for the purpose of risk assessment. The use of such screening data would be in keeping with the requirements of 310 CMR 40.0926(3), which states in part: “In estimating the Exposure Point Concentrations, the objective shall be to identify a conservative estimate of the average concentration contacted by a receptor at the Exposure Point over the period of exposure.” The XRF screening data should be included in the EPC calculation for arsenic, unless additional arsenic laboratory data is generated to recalculate the arsenic EPC.

5) For the purpose of determining risk, the MCP considers soil from 0-3 feet below ground surface to be surficial soil, and as such should be considered a distinct exposure point. EPCs must be developed in accordance with the matrix at 310 CMR 40.0933(9).

6) Table 1 and Table 2 of Appendix C-2 show data sets for lead at the 0-0.5 ft. depth in Area 2.

The values listed in the data sets are different. The lower of the 2 numbers, 375 milligrams per kilogram (mg/kg) was used in the risk assessment; however it is not clear if this value is the correct and representative value. The tables must be clarified, and if necessary, corrected. The risk posed by lead should be recalculated with the correct EPC.

Readville Phase II/III/IV Comments Page 4 7) The calculations used to derive the chemical-specific risk based cleanup concentrations are

not in keeping with the requirements of 310 CMR 40.0992(2), in that the risk assessment calculations do not appear to be sufficiently conservative and consistent with current MassDEP risk assessment guidance and practice as reflected in the MassDEP Short Forms. MassDEP is providing the following examples for reference, and are not intended to represent a complete discussion of divergence from MassDEP regulation, guidance and practice:

a) The risk assessments, as prepared by W& S and LFR, used an averaging period of 27,375

days (75 years) instead of 25,550 days (70 years). MassDEP supplanted its guidance for the averaging period in 2002, and uses the reduced period in its exposure assumptions (including the Human Health Short Form recommended in MassDEP’s letter of December 4, 2007). If the lower averaging period is used, the risk-based cleanup concentrations would be lower than those presented.

b) The risk assessment prepared for LFR by Gradient Corporation changed the assumption

for the exposed skin area of a future commercial worker on the site from 4,188 cm2 (a male aged 18-25) to 3,477 cm2 (a female aged 18-75), in keeping with MassDEP guidance issued for dermal adherence factors in 2002; however the risk assessment also used the higher body weight of a male (70 kg) instead of a body weight more representative of the female receptor chosen. If the properly correlated body weight is used (female aged 18-25, 58 kg), the risk-based cleanup concentrations would be lower than those presented.

c) The calculation for the risk posed by lead involved the use of the Adult Blood Lead

Model created for the US Environmental Protection Agency (EPA). Gradient Corporation’s position at the time was that the EPA method is more conservative than MassDEP’s Reference Dose (RfD) approach. 310 CMR 40.0993(5)(a) of the MCP states in part that primary consideration shall be given to toxicity values published by MassDEP. The risk assessment must clearly demonstrate that the use of such model is at least as conservative as the use of MassDEP’s RfD approach in calculating the risk posed by exposure to lead on site.

d) The risk assessment fails to consider the potential risk(s) posed by long-term exposure of

adjacent residents to wind-blown dust from the site. The assessment must be expanded to include this exposure route.

A risk assessment for future commercial/industrial use of the site is necessary to confirm the appropriate goals for remediation are selected. The use of receptor and exposure assumptions used in MassDEP’s Short Forms and guidance should be employed to assure a conservative and appropriate evaluation of the risk(s) posed by the site are properly documented.

Readville Phase II/III/IV Comments Page 5 8) It is unclear how the 8 mg/kg risk-based cleanup goal was calculated for polychlorinated

biphenyls (PCBs). A PCB risk-based cleanup goal does not appear to have been originally calculated by W&S or included in LFR’s submittals. This value is critical to understanding the decision to reuse stockpiles containing PCBs on the disposal site.

9) The risk assessment, as revised by LFR and used here, calculated risk-based concentrations

for individual contaminants of concern by back-calculating from a risk limit of 1x10-5 for Excess Lifetime Cancer Risk and a Hazard Index of 1. The cumulative exposure risk assessment evaluated the cancer and non-cancer risks associated with exposure to all contaminants except arsenic and lead, which were evaluated separately. A clear demonstration must be presented that exposure to the collective targeted cleanup concentrations is protective of human health, using the above-referenced risk limits.

10) A fundamental issue with the risk assessment is the assumption that future risks will be

controlled through the use of an Activity and Use Limitation (AUL). The proposed AUL will restrict future development to commercial/industrial uses; however, it is unclear how the AUL will prevent activities that would contradict those proposed for the purposes of the risk assessment. For example, the risk assessment fails to specify that an AUL will exclude any future redevelopment that may entail the subdivision of the 37-acre parcel into two or more smaller parcels. Unless this is prevented, subdivision of the parcel may fundamentally change the calculated EPCs for the site and potentially negate the findings of No Significant Risk. 310 CMR 40.0923(1) and 40.0923(4) state that all foreseeable future uses of the site must be considered in the risk assessment, and any limitations and/or restrictions in the AUL proposed must be clearly documented in the assessment. The provided risk assessment and description of the AUL to be employed fails to adequately describe the required limitations and restrictions required to maintain a condition of No Significant Risk.

Phase III RAP 1) MassDEP believes the comments provided for the review of the Phase II above will alter the

risk-based standards selected as remediation goals for the site. Since this will also alter the volume of soil that requires remediation, the RAP will need to be revised accordingly.

2) The alternative chosen in Section 3.4, Recommended Remedial Alternative, proposes to

remove most soil stockpiles on site with contamination above risk-based standards and all Hot Spots on the site. However, the remedial proposal for the remainder of the site proposes removing approximately 8% of the soil with contaminant concentrations over Upper Concentration Limits (UCLs) and none of the soils identified as being above the appropriate risk-based concentrations. The basis for this choice is Earth Tech’s position that removal of additional (or all) soils above either UCLs or risk-based concentrations will not produce any benefit, and may increase short-term risk to remediation workers. MassDEP does not agree with this approach and requires a revised evaluation. Since the submittal of the original Phase III RAP by Weston & Sampson on April 30 2003, the risks posed by site contaminants have been reevaluated and the final use of the property has been selected. The RAP must document that the original feasibility analysis prepared by Weston & Sampson is still valid and applicable. Particular attention must be paid to evaluation of techniques that will result

Readville Phase II/III/IV Comments Page 6

in the reuse, recycling, destruction, detoxification or treatment of oil and/or hazardous material pursuant to 310 CMR 40.0858(1), 40.0858(2), 40.0585(5) and 40.0858(6).

Phase IV RIP

The Operation, Maintenance and Monitoring (OMM) portion of the RIP must be revised in order to present a complete plan in accordance with 310 CMR 40.0874(3)(d). 1) The confirmatory sampling section of the OMM indicates post-excavation screening for lead

will be conducted using an x-ray fluorescence meter. Up to 107 confirmatory samples will be sent to a laboratory for analysis of lead and arsenic. The description of the sampling indicates that this work will be done to “meet the risk-based goals of this area”. It is unclear from this statement as to whether this sampling is to be performed in the designated sampling grids that are to be excavated, in Hot Spot areas, or beneath the stockpiles proposed to be removed (including those piles that are proposed to be reused on site). In addition, as the proposed remediation areas vary greatly in terms of areal extent, it is unclear how the sampling program will be designed to adequately characterize each excavation in order to confirm remedial goals have been met. A thorough discussion addressing these issues should be included in the RIP.

2) In a similar vein, the proposal indicates areas will be regraded as part of the site work. The

proposal does not detail the amount of grading (extent, depth of cut/fills, etc.) or propose additional sampling to confirm that additional risk reduction measures are not warranted due to the exposure/relocation of contaminated soils on site. A detailed discussion of the grading plan is required.

3) Under section 4.4.1 Performance Monitoring Plan, the document states “Sufficient post-

excavation monitoring will occur to comply with 310 CMR 40.0046.” This statement is meant to address the application of Remedial Additives in situ. The RIP must be revised to better explain the remediation procedure for the TCLP-failed soils, including a discussion of the type of media to be evaluated during the application, the proposed monitoring locations and the type of analysis to be conducted.

4) Neither the OMM Plan nor the Health and Safety Plan discuss the development of risk-based

construction worker exposure limits for incorporation into the Health and Safety Plan. Such development must include not only limits for the workers undertaking response actions on the site, but also consider potential exposures to the surrounding residential population during the proposed work on site.

Readville Phase II/III/IV Comments Page 7

If you have any questions regarding any of the above comments please contact Kyle MacAfee at (978) 694-3393 or kyle.macafee@state.ma.us.

Sincerely, Kyle MacAfee Environmental Engineer MassDEP is providing this final document copy to you electronically. A signed copy of

the original document is on file at MassDEP's Northeast Regional Office located in Wilmington, Massachusetts.

Stephen Johnson Deputy Regional Director

Bureau of Waste Site Cleanup Attachments: MassDEP’s October 17, 2008 letter MassDEP/ORS Memorandum to the File cc: Maureen Vallatini, OGC/NERO

Bill Pardee, Esq., Office of the Attorney General, Environmental Protection Division, Bill.Pardee@ago.state.ma.us

Ms. Janis Kearney, Dir. Of Environmental Compliance, MBTA JKearney@mbta.com Elissa J. Brown, Earth Tech/AECOM, Elissa.Brown@earthtech.com

Mr. Bryan Glasscock, Boston Environment Department, 1 City Hall Plaza, Room 805, Boston, MA 02201 Mr. John Shea, Boston Public Health Commission, Environmental Health Office, 1010 Massachusetts Ave., Boston, MA 02118 Mr. William Keegan, Town Administrator, Dedham Town Hall, 26 Bryant St., Dedham, MA 02026 Ms. Catherine Cardinale, Director, Dedham Board of Health, Dedham Town Hall, 26 Bryant St., Dedham, MA 02026

PIP repositories 1. Dedham Public Library,

2. Boston Public Library - Hyde Park Branch Ms. Carol Hanna, 303 Milton St., Dedham, MA 02026

MassDEP File