RELEASE ABATEMENT MEASURE COMPLETION REPORT AND PERMANENT SOLUTION STATEMENT Commercial Property 343-349 Summer Street Somerville, Massachusetts 01607 RTN 3-33735 August 8, 2017 Prepared for: 351 Summer LLC c/o The Maggiore Companies 13 Wheeling Avenue Woburn, Massachusetts Prepared by: EnviroTrac Ltd. 2 Merchant Street, Suite 2 Sharon, Massachusetts 02067 A Full Service Environmental Consulting and Contracting Firm RAM Completion Report and Permanent Solution Statement Commercial Property, 343 Summer St., Somerville, MA; RTN 3-33735 August 8, 2017 TABLE OF CONTENTS Page # I. 0 INTRODUCTION.1 2.0 AREA AND DISPOSAL SITE DESCRIPTIONS [310 CMR 40.1056(2)(A)].1 2.1 Area Description.1 2.2 Disposal Site Description.2 2.3 Sensitive Receptors.2 3.0 RELEASE HISTORY.2 4.0 DESCRIPTION OF RELEASE CONDITIONS [310 CMR 40.0446(4)(A)].2 4.1 UST#1.2 4.2 UST#2.3 4.3 Post-Excavation.3 5.0 DESCRIPTION OF RELEASE ABATEMENT MEASURE [310 CMR 40.0446(4)(B)].3 5.1 Summary Of Assessment and/or Response Actions Completed [310 CMR 40.0446(4)(C)].4 6.0 DISPOSAL SITE CHARACTERIZATION.4 6.1 Soil and Groundwater Classification.4 6.2 Contaminants of Concern.5 7.0 CONCEPTUAL SITE MODEL [310 CMR 40.1056(2)(B)].5 7.1 Site Description and Source of Impacts.5 7.2 Disposal Site Geology and Hydrogeology.6 7.3 Extent of Disposal Site [310 CMR 40.1 056(2)(a)].6 7.4 Evaluation of Hot Spots [310 CMR 40.0006].6 8.0 EXPOSURE ASSESSMENT.7 8.1 Environmental Fate and Transport Characteristics.7 8.3 Current and Potential Receptors.7 8.4 Current and Potential Environmental and Ecological Receptors.7 8.5 Potential Future Use [310 CMR 40.1056(1 )(e), (f), and (g)].8 8.6 Exposure Point Concentrations.8 9.0 METHOD 1 RISK CHARACTERIZATION.8 9.1 Characterization of Risk of Harm to Human Health.8 9.2 Characterization of Risk of Harm to Public Welfare.9 9.3 Characterization of Risk of Harm to Safety.9 9.4 Characterization of Risk of Harm to the Environment.9 10.0 SOURCE CONTROL AND CONTROL OF SUBSURFACE MIGRATION [310 CMR 40.1056(2)(C) AND (D)].9 II. 0 LIGHT NONAQUEOUS PHASE LIQUID MOBILITY [310 CMR 40.1056(2)(3)].9 12.0 UPPER CONCENTRATION LIMITS [310 CMR 40.1056(1 )(J)].10 13.0 OPERATION, MAINTENANCE, AND/OR MONITORING [310 CMR 40.1056(2)(L)].10 14.0 FEASIBILITY EVALUATION [310 CMR 40.1056(2)(G)].10 15.0 DATA USEABILITY AND REPRESENTATIVENESS EVALUATION [310 CMR 40.1056(1)(K) AND (2)(K)].10 15.1 CSM Summary.11 15.2 Use OF Field Screening Data.11 15.3 Sampling Rationale - Number, Spatial Distribution, and Handling of Samples.11 15.4 TEMPORAL Distribution of Samples.11 15.5 Completeness.11 15.6 Inconsistency AND Uncertainty.11 15.7 Information Considered Unrepresentative.12 15.8 Data Usability Assessment.12 Page ii Enviroirac Environmental Services itl<T « bfiH fW>C^iW*tC,. * 3f : .1'"“ • .r«*'* 1f^ -iHht .t ••» If • - iip% ••■-► • I 'Ut^, ' M% ^ 4mnfjAec<?r t4 • Allu.yi. f «* * - ^ I t S •ir... il fr. 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RAM Completion Report and Permanent Solution Statement Commercial Property, 343 Summer St., Somerville, MA; RTN 3-33735 August 8, 2017 16.0 MANAGEMENT OF REMEDIATION WASTE [310 CMR 40.0446(4)(E)].13 17.0 FINDINGS AND CONCLUSIONS OF THE PERMANENT SOLUTION.13 18.0 FINDINGS AND CONCLUSIONS OF THE RAM [310 CMR 40.0446(4)(D) & (F)].13 19.0 PUBLIC NOTIFICATION CORRESPONDENCE [310 CMR 40.1403(D), (F), & (H), 40.1406, AND 40.0446].14 FIGURES Figure 1 Locus Map Figure 2 Site Plan Figure 3 MassGIS Priority Resource Map TABLES Table 1 Summary of Soil Data Table 2 Summary of Soil Exposure Point Concentrations APPENDICES Appendix A Remediation Waste Documentation - 2016 Appendix B Soil Laboratory Reports Appendix C Remediation Waste Documentation - 2017 Appendix D Public Notification Letters Appendix E RAM Plan Public Comment Response Page iii Enviroirac Environmeriial Services •r>i«nna-» lyw . At trcnmug C N" .• c».. .‘^ nti^Mtmt(\/. wua lo tmSn tr_..'... MWI? ' . £i»a/r!ua,'«03QM'.« ■ tt' *. (Q)04l$t^ rmf^ r» ^‘>aa^'A VI. ru 0 ^1 1 ♦* «« i- ••• -• 3i qR>, * u ■ ' •C/T^'l -• ( ■i I { ..j‘i ^ >:»i| «*iH7n#8 vktoT 9 * 41 ‘^1 -.; - 3 W- =; , . v> <f > ' ‘ ha,^ A .£3 \ III ^: ii.»l>i^ . .!^-r jB - ( ^P . :s<- ""11 •' tii/^ 3 xjtjOliftqA / i.' -i ' V ’'^^■' ' i' uSi'S^ '■ ' ..*? ■ »■,'? RAM Completion Report and Permanent Solution Statement Commercial Property, 343 Summer St., Somerville, MA; RTN 3-33735 August 8, 2017 1.0 INTRODUCTION EnviroTrac Ltd. (EnviroTrac) prepared this Release Abatement Measure Completion (RAMC) Report and Permanent Solution Statement (PSS) on behalf of 351 Summer LLC for the commercial property located at 343-349 Summer Street in Somerville, Massachusetts (the Site). This RAMC/PSS is being submitted to the Massachusetts Department of Environmental Protection (MassDEP) to address Release Tracking Number (RTN) 3-33735 and was prepared in accordance with the requirements of the Massachusetts Contingency Plan (MCP) as set forth at 310 CMR 40.1040, 40.1041, and 40.1056. On August 8, 2016, EnviroTrac monitored the completion of tests pits excavated by Koster and Sons Construction, Inc. During the test pit activities, an UST was encountered and damaged by the backhoe. As the result of the UST damage, approximately 20-30 gallons of petroleum was released to the surrounding soil. The released petroleum constituted a Sudden Release, which met the MCP two-hour notification criteria. In response to the release, both the MassDEP and the Somerville Fire Department were notified. Upon notification, MassDEP assigned RTN 3- 33735 to the release. Further details relating to the release are discussed in Section 4.0. During August and September, 2016 IRA field activities were conducted. The current property owner, 351 Summer LLC, acquired the property on February 6, 2017 from The Dakota Group. An Immediate Response Action Plan and IF^ Completion Report for RTN 3-33735 were submitted to MassDEP on March 16, 2017. Based on the results of a Method 1 Risk Characterization (M1RC), a condition of No Significant Risk (NSR) has been achieved for RTN 3-33735. Other conditions applicable to a Permanent Solution (310 CMR 40.1040(1)) and a Permanent Solution with No Conditions (310 CMR 40.1041(1)) have also been achieved. This PSS is not related to any other Permanent or Temporary Solution Statements and is applicable to the entire Disposal Site; therefore, additional Response Actions are not required for any other portion of the Disposal Site (310 CMR 40.1056(1)(d)). 2.0 AREA AND DISPOSAL SITE DESCRIPTIONS [310 CMR 40.1056(2)(a)] 2.1 Area Description The Site is comprised of one parcel of land and is located at 343-349 Summer Street in Somerville, Massachusetts. The parcel is identified by the City of Somerville Assessor’s Office as Map #25, Block D, Lot #33. A Locus Map is provided as Figure 1. The Site consists of a 0.39 acre irregular-shaped vacant parcel of land located in an area of mixed commercial and residential use. The Massachusetts Bay Transportation Authority (MBTA) Red Line runs directly below the Site within a bedrock tunnel approximately 80 feet below ground surface (bgs). A MBTA Red Line vent structure is located at the southern portion of the parcel. 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